Cardinal features of involuntary force variability can arise from the closed-loop control of viscoelastic afferented muscles

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Laine, Christopher M.; Valero-Cuevas, Francisco J.

2018-01-01

Involuntary force variability below 15 Hz arises from, and is influenced by, many factors including descending neural drive, proprioceptive feedback, and mechanical properties of muscles and tendons. However, their potential interactions that give rise to the well-structured spectrum of involuntary force variability are not well understood due to a lack of experimental techniques. Here, we investigated the generation, modulation, and interactions among different sources of force variability using a physiologically-grounded closed-loop simulation of an afferented muscle model. The closed-loop simulation included a musculotendon model, muscle spindle, Golgi tendon organ (GTO), and a tracking controller which enabled target-guided force tracking. We demonstrate that closed-loop control of an afferented musculotendon suffices to replicate and explain surprisingly many cardinal features of involuntary force variability. Specifically, we present 1) a potential origin of low-frequency force variability associated with co-modulation of motor unit firing rates (i.e.,‘common drive’), 2) an in-depth characterization of how proprioceptive feedback pathways suffice to generate 5-12 Hz physiological tremor, and 3) evidence that modulation of those feedback pathways (i.e., presynaptic inhibition of Ia and Ib afferents, and spindle sensitivity via fusimotor drive) influence the full spectrum of force variability. These results highlight the previously underestimated importance of closed-loop neuromechanical interactions in explaining involuntary force variability during voluntary ‘isometric’ force control. Furthermore, these results provide the basis for a unifying theory that relates spinal circuitry to various manifestations of altered involuntary force variability in fatigue, aging and neurological disease. PMID:29309405

Cardinal features of involuntary force variability can arise from the closed-loop control of viscoelastic afferented muscles.

Science.gov (United States)

Nagamori, Akira; Laine, Christopher M; Valero-Cuevas, Francisco J

2018-01-01

Involuntary force variability below 15 Hz arises from, and is influenced by, many factors including descending neural drive, proprioceptive feedback, and mechanical properties of muscles and tendons. However, their potential interactions that give rise to the well-structured spectrum of involuntary force variability are not well understood due to a lack of experimental techniques. Here, we investigated the generation, modulation, and interactions among different sources of force variability using a physiologically-grounded closed-loop simulation of an afferented muscle model. The closed-loop simulation included a musculotendon model, muscle spindle, Golgi tendon organ (GTO), and a tracking controller which enabled target-guided force tracking. We demonstrate that closed-loop control of an afferented musculotendon suffices to replicate and explain surprisingly many cardinal features of involuntary force variability. Specifically, we present 1) a potential origin of low-frequency force variability associated with co-modulation of motor unit firing rates (i.e.,'common drive'), 2) an in-depth characterization of how proprioceptive feedback pathways suffice to generate 5-12 Hz physiological tremor, and 3) evidence that modulation of those feedback pathways (i.e., presynaptic inhibition of Ia and Ib afferents, and spindle sensitivity via fusimotor drive) influence the full spectrum of force variability. These results highlight the previously underestimated importance of closed-loop neuromechanical interactions in explaining involuntary force variability during voluntary 'isometric' force control. Furthermore, these results provide the basis for a unifying theory that relates spinal circuitry to various manifestations of altered involuntary force variability in fatigue, aging and neurological disease.

Bradykinin Contributes to Sympathetic and Pressor Responses Evoked by Activation of Skeletal Muscle Afferents P2X in Heart Failure

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Jihong Xing

2016-11-01

Full Text Available Background/Aims: Published data suggest that purinergic P2X receptors of muscle afferent nerves contribute to the enhanced sympathetic nervous activity (SNA and blood pressure (BP responses during static exercise in heart failure (HF. In this study, we examined engagement of bradykinin (BK in regulating responses of SNA and BP evoked by P2X stimulation in rats with HF. We further examined cellular mechanisms responsible for BK. We hypothesized that BK potentiates P2X currents of muscle dorsal root ganglion (DRG neurons, and this effect is greater in HF due to upregulation of BK kinin B2 and P2X3 receptor. As a result, BK amplifies muscle afferents P2X-mediated SNA and BP responses. Methods: Renal SNA and BP responses were recorded in control rats and rats with HF. Western Blot analysis and patch-clamp methods were employed to examine the receptor expression and function of DRG neurons involved in the effects of BK. Results: BK injected into the arterial blood supply of the hindlimb muscles heightened the reflex SNA and BP responses induced by P2X activation with α,β-methylene ATP to a greater degree in HF rats. In addition, HF upregulated the protein expression of kinin B2 and P2X3 in DRG and the prior application of BK increased the magnitude of α,β-methylene ATP-induced currents in muscle DRG neurons from HF rats. Conclusion: BK plays a facilitating role in modulating muscle afferent P2X-engaged reflex sympathetic and pressor responses. In HF, P2X responsivness is augmented due to increases in expression of kinin B2 and P2X3 receptors and P2X current activity.

Ultrasonography as a tool to study afferent feedback from the muscle-tendon complex during human walking

DEFF Research Database (Denmark)

Cronin, Neil J.; Klint, Richard af; Grey, Michael James

2011-01-01

In humans, one of the most common tasks in everyday life is walking, and sensory afferent feedback from peripheral receptors, particularly the muscle spindles and Golgi tendon organs (GTO), makes an important contribution to the motor control of this task. One factor that can complicate the ability...... with an examination of muscle activation to give a broader insight to neuromuscular interaction during walking. Despite the advances in understanding that these techniques have brought, there is clearly still a need for more direct methods to study both neural and mechanical parameters during human walking in order...... of these receptors to act as length, velocity and force transducers is the complex pattern of interaction between muscle and tendinous tissues, as tendon length is often considerably greater than muscle fibre length in the human lower limb. In essence, changes in muscle-tendon mechanics can influence the firing...

Light and electron microscopy of contacts between primary afferent fibres and neurones with axons ascending the dorsal columns of the feline spinal cord.

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Maxwell, D J; Koerber, H R; Bannatyne, B A

1985-10-01

In addition to primary afferent fibres, the dorsal columns of the cat spinal cord contain ascending second-order axons which project to the dorsal column nuclei. The aim of the present study was to obtain morphological evidence that certain primary afferent axons form monosynaptic contacts with cells of origin of this postsynaptic dorsal column pathway. In ten adult cats, neurones with axons ascending the dorsal columns were retrogradely labelled with horseradish peroxidase using a pellet implantation method in the thoracic dorsal columns. In the lumbosacral regions of the same animals, primary afferent fibres were labelled intra-axonally with ionophoretic application of horseradish peroxidase. Tissue containing labelled axons was prepared for light and combined light and electron microscopy. Ultrastructural examination demonstrated that slowly adapting (Type I), hair follicle, Pacinian corpuscle and group Ia muscle spindle afferents formed monosynaptic contacts with labelled cells and light microscopical analysis suggested that they also received monosynaptic input from rapidly adapting (Krause) afferents. This evidence suggests that sensory information from large-diameter cutaneous and muscle spindle afferent fibres is conveyed disynaptically via the postsynaptic dorsal column pathway to the dorsal column nuclei. Some of the input to this pathway is probably modified in the spinal cord as the majority of primary afferent boutons forming monosynaptic contacts were postsynaptic to other axon terminals. The postsynaptic dorsal column system appears to constitute a major somatosensory pathway in the cat.

Muscle spindle thixotropy affects force perception through afferent-induced facilitation of the motor pathways as revealed by the Kohnstamm effect.

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Monjo, Florian; Forestier, Nicolas

2018-04-01

This study was designed to explore the effects of intrafusal thixotropy, a property affecting muscle spindle sensitivity, on the sense of force. For this purpose, psychophysical measurements of force perception were performed using an isometric force matching paradigm of elbow flexors consisting of matching different force magnitudes (5, 10 and 20% of subjects' maximal voluntary force). We investigated participants' capacity to match these forces after their indicator arm had undergone voluntary isometric conditioning contractions known to alter spindle thixotropy, i.e., contractions performed at long ('hold long') or short muscle lengths ('hold short'). In parallel, their reference arm was conditioned at the intermediate muscle length ('hold-test') at which the matchings were performed. The thixotropy hypothesis predicts that estimation errors should only be observed at low force levels (up to 10% of the maximal voluntary force) with overestimation of the forces produced following 'hold short' conditioning and underestimation following 'hold long' conditioning. We found the complete opposite, especially following 'hold-short' conditioning where subjects underestimated the force they generated with similar relative error magnitudes across force levels. In a second experiment, we tested the hypothesis that estimation errors depended on the degree of afferent-induced facilitation using the Kohnstamm phenomenon as a probe of motor pathway excitability. Because the stronger post-effects were observed following 'hold-short' conditioning, it appears that the conditioning-induced excitation of spindle afferents leads to force misjudgments by introducing a decoupling between the central effort and the cortical motor outputs.

Anatomy and physiology of phrenic afferent neurons.

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Nair, Jayakrishnan; Streeter, Kristi A; Turner, Sara M F; Sunshine, Michael D; Bolser, Donald C; Fox, Emily J; Davenport, Paul W; Fuller, David D

2017-12-01

Large-diameter myelinated phrenic afferents discharge in phase with diaphragm contraction, and smaller diameter fibers discharge across the respiratory cycle. In this article, we review the phrenic afferent literature and highlight areas in need of further study. We conclude that 1 ) activation of both myelinated and nonmyelinated phrenic sensory afferents can influence respiratory motor output on a breath-by-breath basis; 2 ) the relative impact of phrenic afferents substantially increases with diaphragm work and fatigue; 3 ) activation of phrenic afferents has a powerful impact on sympathetic motor outflow, and 4 ) phrenic afferents contribute to diaphragm somatosensation and the conscious perception of breathing. Much remains to be learned regarding the spinal and supraspinal distribution and synaptic contacts of myelinated and nonmyelinated phrenic afferents. Similarly, very little is known regarding the potential role of phrenic afferent neurons in triggering or modulating expression of respiratory neuroplasticity. Copyright © 2017 the American Physiological Society.

Separation and estimation of muscle spindle and tension receptor populations by vibration of the biceps muscle in the frog.

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Giszter, S F; Kargo, W J

2002-10-01

Frog spinal cord reflex behaviors have been used to test the idea of spinal primitives. We have suggested a significant role for proprioception in regulation of primitives. However the in vivo behavior of spindle and golgi tendon receptors in frogs in response to vibration are not well described and the proportions of these proprioceptors are not established. In this study, we examine the selectivity of muscle vibration in the spinal frog. The aim of the study was (1) to examine how hindlimb muscle spindles and GTO receptors are activated by muscle vibration and (2) to estimate the relative numbers of GTO receptors and spindle afferents in a selected muscle, for comparison with the mammal. Single muscle afferents from the biceps muscle were identified in the dorsal roots. These were tested in response to biceps vibration, intramuscular stimulation and biceps nerve stimulation. Biceps units were categorized into two types: First, spindle afferents which had a high conduction velocity (approximately 20-30 m/s), responded reliably (were entrained 1:1) to muscle vibration, and exhibited distinct pauses to shortening muscle contractions. Second, golgi tendon organ afferents, which had a lower conduction velocity (approximately 10-20 m/s), responded less reliably to muscle vibration at physiologic muscle lengths, but responded more reliably at extended lengths or with background muscle contraction, and exhibited distinct bursts to shortening muscle contractions. Vibration responses of these units were tested with and without muscle curarization. Ensemble (suction electrode) recordings from the dorsal roots were used to provide rough estimates of the proportions of the two muscle afferent types.

Afferent innervation of the utricular macula in pigeons

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Si, Xiaohong; Zakir, Mridha Md; Dickman, J. David

2003-01-01

Biotinylated dextran amine (BDA) was used to retrogradely label afferents innervating the utricular macula in adult pigeons. The pigeon utriclar macula consists of a large rectangular-shaped neuroepithelium with a dorsally curved anterior edge and an extended medioposterior tail. The macula could be demarcated into several regions based on cytoarchitectural differences. The striola occupied 30% of the macula and contained a large density of type I hair cells with fewer type II hair cells. Medial and lateral extrastriola zones were located outside the striola and contained only type II hair cells. A six- to eight-cell-wide band of type II hair cells existed near the center of the striola. The reversal line marked by the morphological polarization of hair cells coursed throughout the epithelium, near the peripheral margin, and through the center of the type II band. Calyx afferents innervated type I hair cells with calyceal terminals that contained between 2 and 15 receptor cells. Calyx afferents were located only in the striola region, exclusive of the type II band, had small total fiber innervation areas and low innervation densities. Dimorph afferents innervated both type I and type II hair cells with calyceal and bouton terminals and were primarily located in the striola region. Dimorph afferents had smaller calyceal terminals with few type I hair cells, extended fiber branches with bouton terminals and larger innervation areas. Bouton afferents innervated only type II hair cells in the extrastriola and type II band regions. Bouton afferents innervating the type II band had smaller terminal fields with fewer bouton terminals and smaller innervation areas than fibers located in the extrastriolar zones. Bouton afferents had the most bouton terminals on the longest fibers, the largest innervation areas with the highest innervation densities of all afferents. Among all afferents, smaller terminal innervation fields were observed in the striola and large fields were

Development of fusimotor innervation correlates with group Ia afferents but is independent of neurotrophin-3

NARCIS (Netherlands)

Ringstedt, T; Copray, S; Walro, J; Kucera, J

1998-01-01

Fusimotor neurons, group Ia afferents and muscle spindles are absent in mutant mice lacking the gene for neurotrophin-3 (NT3). To partition the effect of Ia afferent or spindle absence from that of NT3 deprivation on fusimotor neuron development, we examined the fusimotor system in a mutant mouse

Immunomodulation of afferent neurons in guinea-pig isolated airway.

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Riccio, M M; Myers, A C; Undem, B J

1996-03-01

1. The trachea, larynx and main bronchi with the right vagus nerve and nodose ganglion were isolated from guinea-pigs passively immunized 24 h previously with serum containing anti-ovalbumin antibody. 2. The airways were placed in one compartment of a Perspex chamber for recording of isometric tension while the nodose ganglion and attached vagus nerve were pulled into another compartment. Action potentials arriving from single airway afferent nerve endings were monitored extracellularly using a glass microelectrode positioned near neuronal cell bodies in the ganglion. Mechanosensitivity of the nerve endings was quantified using calibrated von Frey filaments immediately before and after exposure to antigen (10 micrograms ml-1 ovalbumin). 3. Ten endings responded to the force exerted by the lowest filament (0.078 mN) and were not further investigated. In airways from thirteen immunized guinea-pigs, the mechanical sensitivity of A delta afferent fibres (conduction velocity = 4.3 +/- 0.6 m s-1) was enhanced 4.1 +/- 0.9-fold following airway exposure to antigen (P action potential generation except in one instance when the receptive field was located over the smooth muscle. This ending also responded to methacholine suggesting that spatial changes in the receptive field, induced by muscle contraction, were responsible for the activation. 5. The mediators responsible for these effects are unknown, although histamine, prostaglandins, leukotrienes and tachykinins do not appear to be essential. The increase in mechanical responsiveness was not associated with the smooth muscle contraction since leukotriene C4, histamine and tachykinins, which all caused a similar contraction to antigen, did not affect mechanical thresholds. Moreover, the antigen-induced increases in excitability persisted beyond the duration of the smooth muscle contraction. 6. These results demonstrate that antigen-antibody-mediated inflammatory processes may enhance the excitability of vagal afferent

Movement and afferent representations in human motor areas: a simultaneous neuroimaging and transcranial magnetic/peripheral nerve-stimulation study

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Hitoshi eShitara

2013-09-01

Full Text Available Neuroimaging combined with transcranial magnetic stimulation (TMS to primary motor cortex (M1 is an emerging technique that can examine motor-system functionality through evoked activity. However, because sensory afferents from twitching muscles are widely represented in motor areas the amount of evoked activity directly resulting from TMS remains unclear. We delivered suprathreshold TMS to left M1 or electrically stimulated the right median nerve (MNS in 18 healthy volunteers while simultaneously conducting functional magnetic resonance imaging and monitoring with electromyography (EMG. We examined in detail the localization of TMS-, muscle afferent- and superficial afferent-induced activity in M1 subdivisions. Muscle afferent- and TMS-evoked activity occurred mainly in rostral M1, while superficial afferents generated a slightly different activation distribution. In 12 participants who yielded quantifiable EMG, differences in brain activity ascribed to differences in movement-size were adjusted using integrated information from the EMGs. Sensory components only explained 10-20% of the suprathreshold TMS-induced activity, indicating that locally and remotely evoked activity in motor areas mostly resulted from the recruitment of neural and synaptic activity. The present study appears to justify the use of fMRI combined with suprathreshold TMS to M1 for evoked motor network imaging.

Interdependency between mechanical parameters and afferent nerve discharge in remodeled diabetic Goto-Kakizaki rat intestine.

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Zhao, Jingbo; Yang, Jian; Liao, Donghua; Gregersen, Hans

2017-01-01

Gastrointestinal disorders are very common in diabetic patients, but the pathogenesis is still not well understood. Peripheral afferent nerves may be involved due to the complex regulation of gastrointestinal function by the enteric nervous system. We aimed to characterize the stimulus-response function of afferent fibers innervating the jejunum in the Goto-Kakizaki (GK) type 2 diabetic rat model. A key question is whether changes in afferent firing arise from remodeled tissue or from adaptive afferent processes. Seven 32-week-old male GK rats and seven age-matched normal Wistar rats were studied. Firing from mesenteric afferent nerves was recorded in excised jejunal segments of seven GK rats and seven normal Wistar rats during ramp test, stress relaxation test, and creep test. The circumferential stress-strain, spike rate increase ratio (SRIR), and single unit firing rates were calculated for evaluation of interdependency of the mechanical stimulations and the afferent nerve discharge. Elevated sensitivity to mechanical stimuli was found for diabetic nerve bundles and single unit activity ( P <0.05). The stress relaxed less in the diabetic intestinal segment ( P <0.05). Linear association between SRIR and the thickness of circumferential muscle layer was found at high stress levels as well as for SRIR and the glucose level. Altered viscoelastic properties and elevated mechanosensitivity were found in the GK rat intestine. The altered nerve signaling is related to muscle layer remodeling and glucose levels and may contribute to gastrointestinal symptoms experienced by diabetic patients.

Peripheral innervation patterns of vestibular nerve afferents in the bullfrog utriculus

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Baird, Richard A.; Schuff, N. R.

1994-01-01

Vestibular nerve afferents innervating the bullfrog utriculus differ in their response dynamics and sensitivity to natural stimulation. They also supply hair cells that differ markedly in hair bundle morphology. To examine the peripheral innervation patterns of individual utricular afferents more closely, afferent fibers were labeled by the extracellular injection of horseradish peroxidase (HRP) into the vestibular nerve after sectioning the vestibular nerve medial to Scarpa's ganglion to allow the degeneration of sympathetic and efferent fibers. The peripheral arborizations of individual afferents were then correlated with the diameters of their parent axons, the regions of the macula they innervate, and the number and type of hair cells they supply. The utriculus is divided by the striola, a narrow zone of distinctive morphology, into media and lateral parts. Utiricular afferents were classified as striolar or extrastriolar according to the epithelial entrance of their parent axons and the location of their terminal fields. In general, striolar afferents had thicker parent axons, fewer subepithelial bifurcations, larger terminal fields, and more synaptic endings than afferents in extrstriolar regions. Afferents in a juxtastriolar zone, immediately adjacent to the medial striola, had innervation patterns transitional between those in the striola and more peripheral parts of the medial extrastriola. moast afferents innervated only a single macular zone. The terminal fields of striolar afferents, with the notable exception of a few afferents with thin parent axons, were generally confined to one side of the striola. Hair cells in the bullfrog utriculus have perviously been classified into four types based on hair bundle morphology. Afferents in the extrastriolar and juxtastriolar zones largely or exclusively innervated Type B hair cells, the predominant hair cell type in the utricular macula. Striolar afferents supplied a mixture of four hair cell types, but largely

C-tactile afferent stimulating touch carries a positive affective value.

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Pawling, Ralph; Cannon, Peter R; McGlone, Francis P; Walker, Susannah C

2017-01-01

The rewarding sensation of touch in affiliative interactions is hypothesized to be underpinned by a specialized system of nerve fibers called C-Tactile afferents (CTs), which respond optimally to slowly moving, gentle touch, typical of a caress. However, empirical evidence to support the theory that CTs encode socially relevant, rewarding tactile information in humans is currently limited. While in healthy participants, touch applied at CT optimal velocities (1-10cm/sec) is reliably rated as subjectively pleasant, neuronopathy patients lacking large myelinated afferents, but with intact C-fibres, report that the conscious sensation elicited by stimulation of CTs is rather vague. Given this weak perceptual impact the value of self-report measures for assessing the specific affective value of CT activating touch appears limited. Therefore, we combined subjective ratings of touch pleasantness with implicit measures of affective state (facial electromyography) and autonomic arousal (heart rate) to determine whether CT activation carries a positive affective value. We recorded the activity of two key emotion-relevant facial muscle sites (zygomaticus major-smile muscle, positive affect & corrugator supercilii-frown muscle, negative affect) while participants evaluated the pleasantness of experimenter administered stroking touch, delivered using a soft brush, at two velocities (CT optimal 3cm/sec & CT non-optimal 30cm/sec), on two skin sites (CT innervated forearm & non-CT innervated palm). On both sites, 3cm/sec stroking touch was rated as more pleasant and produced greater heart rate deceleration than 30cm/sec stimulation. However, neither self-report ratings nor heart rate responses discriminated stimulation on the CT innervated arm from stroking of the non-CT innervated palm. In contrast, significantly greater activation of the zygomaticus major (smiling muscle) was seen specifically to CT optimal, 3cm/sec, stroking on the forearm in comparison to all other stimuli

C-tactile afferent stimulating touch carries a positive affective value.

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Ralph Pawling

Full Text Available The rewarding sensation of touch in affiliative interactions is hypothesized to be underpinned by a specialized system of nerve fibers called C-Tactile afferents (CTs, which respond optimally to slowly moving, gentle touch, typical of a caress. However, empirical evidence to support the theory that CTs encode socially relevant, rewarding tactile information in humans is currently limited. While in healthy participants, touch applied at CT optimal velocities (1-10cm/sec is reliably rated as subjectively pleasant, neuronopathy patients lacking large myelinated afferents, but with intact C-fibres, report that the conscious sensation elicited by stimulation of CTs is rather vague. Given this weak perceptual impact the value of self-report measures for assessing the specific affective value of CT activating touch appears limited. Therefore, we combined subjective ratings of touch pleasantness with implicit measures of affective state (facial electromyography and autonomic arousal (heart rate to determine whether CT activation carries a positive affective value. We recorded the activity of two key emotion-relevant facial muscle sites (zygomaticus major-smile muscle, positive affect & corrugator supercilii-frown muscle, negative affect while participants evaluated the pleasantness of experimenter administered stroking touch, delivered using a soft brush, at two velocities (CT optimal 3cm/sec & CT non-optimal 30cm/sec, on two skin sites (CT innervated forearm & non-CT innervated palm. On both sites, 3cm/sec stroking touch was rated as more pleasant and produced greater heart rate deceleration than 30cm/sec stimulation. However, neither self-report ratings nor heart rate responses discriminated stimulation on the CT innervated arm from stroking of the non-CT innervated palm. In contrast, significantly greater activation of the zygomaticus major (smiling muscle was seen specifically to CT optimal, 3cm/sec, stroking on the forearm in comparison to all

Population coding of forelimb joint kinematics by peripheral afferents in monkeys.

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Tatsuya Umeda

Full Text Available Various peripheral receptors provide information concerning position and movement to the central nervous system to achieve complex and dexterous movements of forelimbs in primates. The response properties of single afferent receptors to movements at a single joint have been examined in detail, but the population coding of peripheral afferents remains poorly defined. In this study, we obtained multichannel recordings from dorsal root ganglion (DRG neurons in cervical segments of monkeys. We applied the sparse linear regression (SLiR algorithm to the recordings, which selects useful input signals to reconstruct movement kinematics. Multichannel recordings of peripheral afferents were performed by inserting multi-electrode arrays into the DRGs of lower cervical segments in two anesthetized monkeys. A total of 112 and 92 units were responsive to the passive joint movements or the skin stimulation with a painting brush in Monkey 1 and Monkey 2, respectively. Using the SLiR algorithm, we reconstructed the temporal changes of joint angle, angular velocity, and acceleration at the elbow, wrist, and finger joints from temporal firing patterns of the DRG neurons. By automatically selecting a subset of recorded units, the SLiR achieved superior generalization performance compared with a regularized linear regression algorithm. The SLiR selected not only putative muscle units that were responsive to only the passive movements, but also a number of putative cutaneous units responsive to the skin stimulation. These results suggested that an ensemble of peripheral primary afferents that contains both putative muscle and cutaneous units encode forelimb joint kinematics of non-human primates.

Interdependency between mechanical parameters and afferent nerve discharge in remodeled diabetic Goto-Kakizaki rat intestine

Directory of Open Access Journals (Sweden)

Zhao J

2017-12-01

Full Text Available Jingbo Zhao,1 Jian Yang,1 Donghua Liao,1 Hans Gregersen2 1Giome Academia, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; 2Giome Center, Department of Surgery, Chinese University of Hong Kong and Prince of Wales Hospital, Shatin, Hong Kong Background: Gastrointestinal disorders are very common in diabetic patients, but the pathogenesis is still not well understood. Peripheral afferent nerves may be involved due to the complex regulation of gastrointestinal function by the enteric nervous system. Objective: We aimed to characterize the stimulus–response function of afferent fibers innervating the jejunum in the Goto-Kakizaki (GK type 2 diabetic rat model. A key question is whether changes in afferent firing arise from remodeled tissue or from adaptive afferent processes. Design: Seven 32-week-old male GK rats and seven age-matched normal Wistar rats were studied. Firing from mesenteric afferent nerves was recorded in excised jejunal segments of seven GK rats and seven normal Wistar rats during ramp test, stress relaxation test, and creep test. The circumferential stress–strain, spike rate increase ratio (SRIR, and single unit firing rates were calculated for evaluation of interdependency of the mechanical stimulations and the afferent nerve discharge. Results: Elevated sensitivity to mechanical stimuli was found for diabetic nerve bundles and single unit activity (P<0.05. The stress relaxed less in the diabetic intestinal segment (P<0.05. Linear association between SRIR and the thickness of circumferential muscle layer was found at high stress levels as well as for SRIR and the glucose level. Conclusion: Altered viscoelastic properties and elevated mechanosensitivity were found in the GK rat intestine. The altered nerve signaling is related to muscle layer remodeling and glucose levels and may contribute to gastrointestinal symptoms experienced by diabetic patients. Keywords: afferents, spike rate, stress–strain, creep

A comparative analysis of the encapsulated end-organs of mammalian skeletal muscles and of their sensory nerve endings.

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Banks, R W; Hulliger, M; Saed, H H; Stacey, M J

2009-06-01

to be located closer to the main divisions of the nerve. Next, based on a sample of tendon organs from several hind-foot muscles of the cat, we demonstrate the existence in at least a large proportion of tendon organs of a structural substrate to account for multiple spike-initiation sites and pacemaker switching, namely the distribution of sensory terminals supplied by the different first-order branches of the Ib afferent to separate, parallel, tendinous compartments of individual tendon organs. We then show that the numbers of spindles, tendon organs and paciniform corpuscles vary independently in a sample of (mainly) hind-foot muscles of the cat. Grouping muscles by anatomical region in the cat indicated the existence of a gradual proximo-distal decline in the overall average size of the afferent complement of muscle spindles from axial through hind limb to intrinsic foot muscles, but with considerable muscle-specific variability. Finally, we present some comparative data on muscle-spindle afferent complements of rat, rabbit and guinea pig, one particularly notable feature being the high incidence of multiple primary endings in the rat.

Detection thresholds of macaque otolith afferents.

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Yu, Xiong-Jie; Dickman, J David; Angelaki, Dora E

2012-06-13

The vestibular system is our sixth sense and is important for spatial perception functions, yet the sensory detection and discrimination properties of vestibular neurons remain relatively unexplored. Here we have used signal detection theory to measure detection thresholds of otolith afferents using 1 Hz linear accelerations delivered along three cardinal axes. Direction detection thresholds were measured by comparing mean firing rates centered on response peak and trough (full-cycle thresholds) or by comparing peak/trough firing rates with spontaneous activity (half-cycle thresholds). Thresholds were similar for utricular and saccular afferents, as well as for lateral, fore/aft, and vertical motion directions. When computed along the preferred direction, full-cycle direction detection thresholds were 7.54 and 3.01 cm/s(2) for regular and irregular firing otolith afferents, respectively. Half-cycle thresholds were approximately double, with excitatory thresholds being half as large as inhibitory thresholds. The variability in threshold among afferents was directly related to neuronal gain and did not depend on spike count variance. The exact threshold values depended on both the time window used for spike count analysis and the filtering method used to calculate mean firing rate, although differences between regular and irregular afferent thresholds were independent of analysis parameters. The fact that minimum thresholds measured in macaque otolith afferents are of the same order of magnitude as human behavioral thresholds suggests that the vestibular periphery might determine the limit on our ability to detect or discriminate small differences in head movement, with little noise added during downstream processing.

Inhibition of Parkinsonian tremor with cutaneous afferent evoked by transcutaneous electrical nerve stimulation.

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Hao, Man-Zhao; Xu, Shao-Qin; Hu, Zi-Xiang; Xu, Fu-Liang; Niu, Chuan-Xin M; Xiao, Qin; Lan, Ning

2017-07-14

Recent study suggests that tremor signals are transmitted by way of multi-synaptic corticospinal pathway. Neurophysiological studies have also demonstrated that cutaneous afferents exert potent inhibition to descending motor commands by way of spinal interneurons. We hypothesize in this study that cutaneous afferents could also affect the transmission of tremor signals, thus, inhibit tremor in patients with PD. We tested this hypothesis by activating cutaneous afferents in the dorsal hand skin innervated by superficial radial nerve using transcutaneous electrical nerve stimulation (TENS). Eight patients with PD having tremor dominant symptom were recruited to participate in this study using a consistent experimental protocol for tremor inhibition. Resting tremor and electromyogram (EMG) of muscles in the upper extremity of these subjects with PD were recorded, while surface stimulation was applied to the dorsal skin of the hand. Fifteen seconds of data were recorded for 5 s prior to, during and post stimulation. Power spectrum densities (PSDs) of tremor and EMG signals were computed for each data segment. The peak values of PSDs in three data segments were compared to detect evidence of tremor inhibition. At stimulation intensity from 1.5 to 1.75 times of radiating sensation threshold, apparent suppressions of tremor at wrist, forearm and upper arm and in the EMGs were observed immediately at the onset of stimulation. After termination of stimulation, tremor and rhythmic EMG bursts reemerged gradually. Statistical analysis of peak spectral amplitudes showed a significant difference in joint tremors and EMGs during and prior to stimulation in all 8 subjects with PD. The average percentage of suppression was 61.56% in tremor across all joints of all subjects, and 47.97% in EMG of all muscles. The suppression appeared to occur mainly in distal joints and muscles. There was a slight, but inconsistent effect on tremor frequency in the 8 patients with PD tested. Our

Modulation of the masseteric reflex by gastric vagal afferents.

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Pettorossi, V E

1983-04-01

Several investigations have shown that the vagal nerve can affect the reflex responses of the masticatory muscles acting at level either of trigeminal motoneurons or of the mesencephalic trigeminal nucleus (MTN). The present experiments have been devoted to establish the origin of the vagal afferent fibres involved in modulating the masseteric reflex. In particular, the gastric vagal afferents were taken into consideration and selective stimulations of such fibres were performed in rabbit. Conditioning electrical stimulation of truncus vagalis ventralis (TVV) reduced the excitability of the MTN cells as shown by a decrease of the antidromic response recorded from the semilunar ganglion and elicited by MTN single-shock electrical stimulation. Sympathetic and cardiovascular influences were not involved in these responses. Mechanical stimulation of gastric receptors, by means of gastric distension, clearly diminished the amplitude of twitch tension of masseteric reflex and inhibited the discharge frequency of proprioceptive MTN units. The effect was phasic and depended upon the velocity of distension. Thus the sensory volleys originating from rapid adapting receptors reach the brain stem through vagal afferents and by means of a polysynaptic connection inhibits the masseteric reflex at level of MTN cells.

Repeated Muscle Injury as a Presumptive Trigger for Chronic Masticatory Muscle Pain

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Dean Dessem

2011-01-01

Full Text Available skeletal muscles sustain a significant loss of maximal contractile force after injury, but terminally damaged fibers can eventually be replaced by the growth of new muscle (regeneration, with full restoration of contractile force over time. After a second injury, limb muscles exhibit a smaller reduction in maximal force and reduced inflammation compared with that after the initial injury (i.e., repeated bout effect. In contrast, masticatory muscles exhibit diminished regeneration and persistent fibrosis, after a single injury; following a second injury, plasma extravasation is greater than after a single injury and maximal force is decreased more than after the initial injury. Thus, masticatory muscles do not exhibit a repeated bout effect and are instead increasingly damaged by repeated injury. We propose that the impaired ability of masticatory muscles to regenerate contributes to chronic muscle pain by leading to an accumulation of tissue damage, fibrosis, and a persistent elevation and prolonged membrane translocation of nociceptive channels such as P2X3 as well as enhanced expression of neuropeptides including CGRP within primary afferent neurons. These transformations prime primary afferent neurons for enhanced responsiveness upon subsequent injury thus triggering and/or exacerbating chronic muscle pain.

Heart failure induces changes in acid-sensing ion channels in sensory neurons innervating skeletal muscle.

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Gibbons, David D; Kutschke, William J; Weiss, Robert M; Benson, Christopher J

2015-10-15

Heart failure is associated with diminished exercise capacity, which is driven, in part, by alterations in exercise-induced autonomic reflexes triggered by skeletal muscle sensory neurons (afferents). These overactive reflexes may also contribute to the chronic state of sympathetic excitation, which is a major contributor to the morbidity and mortality of heart failure. Acid-sensing ion channels (ASICs) are highly expressed in muscle afferents where they sense metabolic changes associated with ischaemia and exercise, and contribute to the metabolic component of these reflexes. Therefore, we tested if ASICs within muscle afferents are altered in heart failure. We used whole-cell patch clamp to study the electrophysiological properties of acid-evoked currents in isolated, labelled muscle afferent neurons from control and heart failure (induced by myocardial infarction) mice. We found that the percentage of muscle afferents that displayed ASIC-like currents, the current amplitudes, and the pH dose-response relationships were not altered in mice with heart failure. On the other hand, the biophysical properties of ASIC-like currents were significantly different in a subpopulation of cells (40%) from heart failure mice. This population displayed diminished pH sensitivity, altered desensitization kinetics, and very fast recovery from desensitization. These unique properties define these channels within this subpopulation of muscle afferents as being heteromeric channels composed of ASIC2a and -3 subunits. Heart failure induced a shift in the subunit composition of ASICs within muscle afferents, which significantly altered their pH sensing characteristics. These results might, in part, contribute to the changes in exercise-mediated reflexes that are associated with heart failure. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Serotonin, dopamine and noradrenaline adjust actions of myelinated afferents via modulation of presynaptic inhibition in the mouse spinal cord.

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David L García-Ramírez

Full Text Available Gain control of primary afferent neurotransmission at their intraspinal terminals occurs by several mechanisms including primary afferent depolarization (PAD. PAD produces presynaptic inhibition via a reduction in transmitter release. While it is known that descending monoaminergic pathways complexly regulate sensory processing, the extent these actions include modulation of afferent-evoked PAD remains uncertain. We investigated the effects of serotonin (5HT, dopamine (DA and noradrenaline (NA on afferent transmission and PAD. Responses were evoked by stimulation of myelinated hindlimb cutaneous and muscle afferents in the isolated neonatal mouse spinal cord. Monosynaptic responses were examined in the deep dorsal horn either as population excitatory synaptic responses (recorded as extracellular field potentials; EFPs or intracellular excitatory postsynaptic currents (EPSCs. The magnitude of PAD generated intraspinally was estimated from electrotonically back-propagating dorsal root potentials (DRPs recorded on lumbar dorsal roots. 5HT depressed the DRP by 76%. Monosynaptic actions were similarly depressed by 5HT (EFPs 54%; EPSCs 75% but with a slower time course. This suggests that depression of monosynaptic EFPs and DRPs occurs by independent mechanisms. DA and NA had similar depressant actions on DRPs but weaker effects on EFPs. IC50 values for DRP depression were 0.6, 0.8 and 1.0 µM for 5HT, DA and NA, respectively. Depression of DRPs by monoamines was nearly-identical in both muscle and cutaneous afferent-evoked responses, supporting a global modulation of the multimodal afferents stimulated. 5HT, DA and NA produced no change in the compound antidromic potentials evoked by intraspinal microstimulation indicating that depression of the DRP is unrelated to direct changes in the excitability of intraspinal afferent fibers, but due to metabotropic receptor activation. In summary, both myelinated afferent-evoked DRPs and monosynaptic

Physiological recruitment of motor units by high-frequency electrical stimulation of afferent pathways.

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Dideriksen, Jakob L; Muceli, Silvia; Dosen, Strahinja; Laine, Christopher M; Farina, Dario

2015-02-01

Neuromuscular electrical stimulation (NMES) is commonly used in rehabilitation, but electrically evoked muscle activation is in several ways different from voluntary muscle contractions. These differences lead to challenges in the use of NMES for restoring muscle function. We investigated the use of low-current, high-frequency nerve stimulation to activate the muscle via the spinal motoneuron (MN) pool to achieve more natural activation patterns. Using a novel stimulation protocol, the H-reflex responses to individual stimuli in a train of stimulation pulses at 100 Hz were reliably estimated with surface EMG during low-level contractions. Furthermore, single motor unit recruitment by afferent stimulation was analyzed with intramuscular EMG. The results showed that substantially elevated H-reflex responses were obtained during 100-Hz stimulation with respect to a lower stimulation frequency. Furthermore, motor unit recruitment using 100-Hz stimulation was not fully synchronized, as it occurs in classic NMES, and the discharge rates differed among motor units because each unit was activated only after a specific number of stimuli. The most likely mechanism behind these observations is the temporal summation of subthreshold excitatory postsynaptic potentials from Ia fibers to the MNs. These findings and their interpretation were also verified by a realistic simulation model of afferent stimulation of a MN population. These results suggest that the proposed stimulation strategy may allow generation of considerable levels of muscle activation by motor unit recruitment that resembles the physiological conditions. Copyright © 2015 the American Physiological Society.

The role in masseter muscle activities of functionally elicited periodontal afferents from abutment teeth under overdentures.

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Mushimoto, E

1981-09-01

Five overdenture wearers with a small number of remaining natural teeth were selected to evaluate the effect of the afferent input from periodontal mechanoreceptors on masseter activity in man. As a control, a full denture wearer was included. The subjects were instructed to chew a piece of gum, and/or tap their teeth. Surface EmG from the bilateral masseter muscles were recorded and analysed. When functional pressure was applied, during chewing, to the abutment teeth as well as to mucosa through the denture base, masseter activities were encouraged. Following application of anaesthesia to the periodontal membrane of the abutments, masseter activities were reduced. The duration of the silent period (SP) appearing in the EMG burst following tooth tapping was significantly increased with root support compared to mucosal support only. With topical anaesthesia of the periodontal tissues, SP duration decreased significantly. In conclusion, it has become apparent that the pressure sensibility of abutment teeth bearing functional pressure under an overdenture base is capable of facilitating masseter activity, as one of the sources of oral sensory input during mastication.

Induction and modulation of referred muscle pain in humans

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Laursen, René Johannes

correlated to pain intensity, and LP and RP thresholds were reproducible within and between sessions. Experimentally (electrical stimulation and infusion of hypertonic saline) induced muscle pain seems to be mediated by myelinated and unmyelinated afferents and the peripheral component of RP by myelinated...... afferents. Furthermore, cutaneous anesthesia of the RP area resulted in a reduction of RP intensity of 22%, while a complete nerve block of afferents from the RP area resulted in a 40% reduction. In summary, observations from the presented experiments suggest that elicitation of referred muscle pain...... is depending on and correlated to local muscle pain. Peripheral input from the RP area is involved, but is not a necessary condition for RP to appear. The present studies as well as others suggest that central hyperexcitability is involved in the generation of RP, but further investigations on mechanisms of RP...

Severe hypoxia affects exercise performance independently of afferent feedback and peripheral fatigue.

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Millet, Guillaume Y; Muthalib, Makii; Jubeau, Marc; Laursen, Paul B; Nosaka, Kazunori

2012-04-01

To test the hypothesis that hypoxia centrally affects performance independently of afferent feedback and peripheral fatigue, we conducted two experiments under complete vascular occlusion of the exercising muscle under different systemic O(2) environmental conditions. In experiment 1, 12 subjects performed repeated submaximal isometric contractions of the elbow flexor to exhaustion (RCTE) with inspired O(2) fraction fixed at 9% (severe hypoxia, SevHyp), 14% (moderate hypoxia, ModHyp), 21% (normoxia, Norm), or 30% (hyperoxia, Hyper). The number of contractions (performance), muscle (biceps brachii), and prefrontal near-infrared spectroscopy (NIRS) parameters and high-frequency paired-pulse (PS100) evoked responses to electrical muscle stimulation were monitored. In experiment 2, 10 subjects performed another RCTE in SevHyp and Norm conditions in which the number of contractions, biceps brachii electromyography responses to electrical nerve stimulation (M wave), and transcranial magnetic stimulation responses (motor-evoked potentials, MEP, and cortical silent period, CSP) were recorded. Performance during RCTE was significantly reduced by 10-15% in SevHyp (arterial O(2) saturation, SpO(2) = ∼75%) compared with ModHyp (SpO(2) = ∼90%) or Norm/Hyper (SpO(2) > 97%). Performance reduction in SevHyp occurred despite similar 1) metabolic (muscle NIRS parameters) and functional (changes in PS100 and M wave) muscle states and 2) MEP and CSP responses, suggesting comparable corticospinal excitability and spinal and cortical inhibition between SevHyp and Norm. It is concluded that, in SevHyp, performance and central drive can be altered independently of afferent feedback and peripheral fatigue. It is concluded that submaximal performance in SevHyp is partly reduced by a mechanism related directly to brain oxygenation.

Afferent nerves regulating the cough reflex: Mechanisms and Mediators of Cough in Disease

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Canning, Brendan J.

2010-01-01

Bronchopulmonary C-fibers and acid-sensitive, capsaicin-insensitive mechanoreceptors innervating the larynx, trachea and large bronchi regulate the cough reflex. These vagal afferent nerves may interact centrally with sensory input arising from afferent nerves innervating the intrapulmonary airways or even extrapulmonary afferents such as those innervating the nasal mucosa and esophagus to produce chronic cough or enhanced cough responsiveness. The mechanisms of cough initiation in health and in disease are briefly described. PMID:20172253

Acylcarnitines as markers of exercise-associated fuel partitioning, xenometabolism, and potential signals to muscle afferent neurons.

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Zhang, Jie; Light, Alan R; Hoppel, Charles L; Campbell, Caitlin; Chandler, Carol J; Burnett, Dustin J; Souza, Elaine C; Casazza, Gretchen A; Hughen, Ronald W; Keim, Nancy L; Newman, John W; Hunter, Gary R; Fernandez, Jose R; Garvey, W Timothy; Harper, Mary-Ellen; Fiehn, Oliver; Adams, Sean H

2017-01-01

that a weight-loss/fitness intervention alters plasma xenometabolites [i.e. cis-3,4-methylene-heptanoylcarnitine and γ-butyrobetaine (a co-metabolite possibly derived in part from gut bacteria)], suggesting that host metabolic health regulated gut microbe metabolism. Finally, we considered whether acylcarnitine metabolites signal to muscle-innervating afferents; palmitoylcarnitine at concentrations as low as 1-10 μm activated a subset (∼2.5-5%) of these neurons ex vivo. This supports the hypothesis that in addition to tracking exercise-associated shifts in fuel metabolism, muscle acylcarnitines act as signals of exertion to short-loop somatosensory-motor circuits or to the brain. © 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.

Modulation of long-latency afferent inhibition by the amplitude of sensory afferent volley.

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Turco, Claudia V; El-Sayes, Jenin; Fassett, Hunter J; Chen, Robert; Nelson, Aimee J

2017-07-01

Long-latency afferent inhibition (LAI) is the inhibition of the transcranial magnetic stimulation (TMS) motor-evoked potentials (MEP) by the sensory afferent volley following electrical stimulation of a peripheral nerve. It is unknown how the activation of sensory afferent fibers relates to the magnitude of LAI. This study investigated the relationship between LAI and the sensory nerve action potentials (SNAP) from the median nerve (MN) and the digital nerves (DN) of the second digit. LAI was obtained by delivering nerve stimulation 200 ms before a TMS pulse delivered over the motor cortex. Experiment 1 assessed the magnitude of LAI following stimulation of the contralateral MN or DN using nerve stimulus intensities relative to the maximum SNAP (SNAP max ) of that nerve and two TMS intensities (0.5- and 1-mV MEP). Results indicate that MN LAI is maximal at ~50% SNAP max , when presumably all sensory afferents are recruited for TMS of 0.5-mV MEP. For DN, LAI appears at ~50% SNAP max and does not increase with further recruitment of sensory afferents. Experiment 2 investigated the magnitude of LAI following ipsilateral nerve stimulation at intensities relative to SNAP max Results show minimal LAI evoked by ipsilateral MN and no LAI following ipsilateral DN stimulation. Implications for future studies investigating LAI include adjusting nerve stimulation to 50% SNAP max to obtain maximal LAI. Additionally, MN LAI can be used as a marker for neurological disease or injury by using a nerve stimulation intensity that can evoke a depth of LAI capable of increasing or decreasing. NEW & NOTEWORTHY This is the first investigation of the relationship between long-latency afferent inhibition (LAI) and the sensory afferent volley. Differences exist between median and digital nerve LAI. For the median nerve, LAI increases until all sensory fibers are presumably recruited. In contrast, digital nerve LAI does not increase with the recruitment of additional sensory fibers but

Chloride is essential for contraction of afferent arterioles after agonists and potassium

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Jensen, B L; Ellekvist, Peter; Skøtt, O

1997-01-01

to norepinephrine, angiotensin II (ANG II), and potassium were measured after chloride depletion and compared with controls. Chloride depletion did not change arteriolar diameters, but the response to norepinephrine was markedly reduced when chloride was substituted with gluconate (n = 6) or isethionate (n = 6......). Reintroduction of chloride fully restored the sensitivity to norepinephrine. Contractions after ANG II and potassium were totally abolished in the absence of chloride (n = 6). In additional experiments (n = 7), the arteriolar contraction to 100 mM potassium was abolished only 1 min after removal of extracellular......A depolarizing chloride efflux has been suggested to activate voltage-dependent calcium channels in renal afferent arteriolar smooth muscle cells in response to vasoconstrictors. To test this proposal, rabbit afferent arterioles were microperfused, and the contractile dose responses...

Force encoding in muscle spindles during stretch of passive muscle.

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Kyle P Blum

2017-09-01

Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

Force encoding in muscle spindles during stretch of passive muscle.

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Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

2017-09-01

Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

Abdominal and internal intercostal motoneurones are strong synergists for expiration but are not synergists for Group I monosynaptic afferent inputs

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Ford, Tim W; Meehan, Claire Francesca; Kirkwood, Peter

2014-01-01

, 9 being in Group B Dist motoneurones. The complete absence of heteronymous monosynaptic Group I reflex excitation between muscles that are synergistically activated in expiration leads us to conclude that such connections from muscle spindle afferents of the thoracic nerves have little role...... in controlling expiratory movements but, where present, support other motor acts....

Bilateral sensory deprivation of trigeminal afferent fibers on corticomotor control of human tongue musculature: A preliminary study

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Kothari, Mohit; Baad-Hansen, Lene; Svensson, Peter

2016-01-01

Background: Transcranial magnetic stimulation (TMS) has demonstrated changes in motor evoked potentials (MEPs) in human limb muscles following modulation of sensory afferent inputs. Objective: The aim of the present study was to determine whether bilateral local anaesthesia (LA) of the lingual ne...

Vascular smooth muscle cells express the alpha(1A) subunit of a P-/Q-type voltage-dependent Ca(2+)Channel, and It is functionally important in renal afferent arterioles

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Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D

2000-01-01

In the present study, we tested whether the alpha(1A) subunit, which encodes a neuronal isoform of voltage-dependent Ca(2+) channels (VDCCs) (P-/Q-type), was present and functional in vascular smooth muscle and renal resistance vessels. By reverse transcription-polymerase chain reaction...... preglomerular resistance vessels and aorta, as well as mesangial cells, and that P-type VDCCs contribute to Ca(2+) influx in aortic and renal VSMCs and are involved in depolarization-mediated contraction in renal afferent arterioles....

Monosynaptic Ia projections from intrinsic hand muscles to forearm motoneurones in humans.

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Marchand-Pauvert, V; Nicolas, G; Pierrot-Deseilligny, E

2000-05-15

Heteronymous Ia excitatory projections from intrinsic hand muscles to human forearm motoneurones (MNs) were investigated. Changes in firing probability of single motor units (MUs) in the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) were studied after electrical stimuli were applied to the median and ulnar nerve at wrist level and to the corresponding homonymous nerve at elbow level. Homonymous facilitation, occurring at the same latency as the H reflex, and therefore attributed to monosynaptic Ia EPSPs, was found in all the sampled units. In many MUs an early facilitation was also evoked by heteronymous low-threshold afferents from intrinsic hand muscles. The low threshold (between 0.5 and 0.6 times motor threshold (MT)) and the inability of a pure cutaneous stimulation to reproduce this effect indicate that it is due to stimulation of group I muscle afferents. Evidence for a similar central delay (monosynaptic) in heteronymous as in homonymous pathways was accepted when the difference in latencies of the homonymous and heteronymous peaks did not differ from the estimated supplementary afferent conduction time from wrist to elbow level by more than 0.5 ms (conduction velocity in the fastest Ia afferents between wrist and elbow levels being equal to 69 m s-1). A statistically significant heteronymous monosynaptic Ia excitation from intrinsic hand muscles supplied by both median and ulnar nerves was found in MUs belonging to all forearm motor nuclei tested (although not in ECU MUs after ulnar stimulation). It was, however, more often found in flexors than in extensors, in wrist than in finger muscles and in muscles operating in the radial than in the ulnar side. It is argued that the connections of Ia afferents from intrinsic hand muscles to forearm MNs, which are stronger and more widely distributed than in the cat

Group II muscle afferents probably contribute to the medium latency soleus stretch reflex during walking in humans

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Grey, Michael James; Ladouceur, Michel; Andersen, Jacob B.

2001-01-01

1. The objective of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. 2. Fourteen healthy subjects walked on a treadmill at approximately 3.5 km h(-1) with the left ankle...... = 0.007), whereas the short latency component was unchanged (P = 0.653). 7. An ankle block with lidocaine hydrochloride was performed to suppress the cutaneous afferents of the foot and ankle. Neither the short (P = 0.453) nor medium (P = 0.310) latency reflexes were changed. 8. Our results support...

The role of the renal afferent and efferent nerve fibres in heart failure

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Lindsea C Booth

2015-10-01

Full Text Available Renal nerves contain afferent, sensory and efferent, sympathetic nerve fibres. In heart failure (HF there is an increase in renal sympathetic nerve activity, which can lead to renal vasoconstriction, increased renin release and sodium retention. These changes are thought to contribute to renal dysfunction, which is predictive of poor outcome in patients with HF. In contrast, the role of the renal afferent nerves remains largely unexplored in HF. This is somewhat surprising as there are multiple triggers in HF that have the potential to increase afferent nerve activity, including increased venous pressure and reduced kidney perfusion. Some of the few studies investigating renal afferents in HF have suggested that at least the sympatho-inhibitory reno-renal reflex is blunted. In experimentally induced HF, renal denervation, both surgical and catheter-based, has been associated with some improvements in renal and cardiac function. It remains unknown whether the effects are due to removal of the efferent renal nerve fibres, afferent renal nerve fibres, or a combination of both. Here, we review the effects of HF on renal efferent and afferent nerve function and critically assess the latest evidence supporting renal denervation as a potential treatment in HF.

The role of the renal afferent and efferent nerve fibers in heart failure

Science.gov (United States)

Booth, Lindsea C.; May, Clive N.; Yao, Song T.

2015-01-01

Renal nerves contain afferent, sensory and efferent, sympathetic nerve fibers. In heart failure (HF) there is an increase in renal sympathetic nerve activity (RSNA), which can lead to renal vasoconstriction, increased renin release and sodium retention. These changes are thought to contribute to renal dysfunction, which is predictive of poor outcome in patients with HF. In contrast, the role of the renal afferent nerves remains largely unexplored in HF. This is somewhat surprising as there are multiple triggers in HF that have the potential to increase afferent nerve activity, including increased venous pressure and reduced kidney perfusion. Some of the few studies investigating renal afferents in HF have suggested that at least the sympatho-inhibitory reno-renal reflex is blunted. In experimentally induced HF, renal denervation, both surgical and catheter-based, has been associated with some improvements in renal and cardiac function. It remains unknown whether the effects are due to removal of the efferent renal nerve fibers or afferent renal nerve fibers, or a combination of both. Here, we review the effects of HF on renal efferent and afferent nerve function and critically assess the latest evidence supporting renal denervation as a potential treatment in HF. PMID:26483699

Estimation of the number of angiotensin II AT1 receptors in rat kidney afferent and efferent arterioles

DEFF Research Database (Denmark)

Razga, Zsolt; Nyengaard, Jens Randel

2007-01-01

of angiotensin II AT1 receptors along the length of the arterioles and per arteriole, we combined immunoelectron microscopy with stereology. RESULTS: The number of AT1 receptor molecules was significantly lower in the renin-positive smooth muscle cells (SMCs) than in the renin-negative SMCs of the afferent...

Dynamic modulation of corticospinal excitability and short-latency afferent inhibition during onset and maintenance phase of selective finger movement.

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Cho, Hyun Joo; Panyakaew, Pattamon; Thirugnanasambandam, Nivethida; Wu, Tianxia; Hallett, Mark

2016-06-01

During highly selective finger movement, corticospinal excitability is reduced in surrounding muscles at the onset of movement but this phenomenon has not been demonstrated during maintenance of movement. Sensorimotor integration may play an important role in selective movement. We sought to investigate how corticospinal excitability and short-latency afferent inhibition changes in active and surrounding muscles during onset and maintenance of selective finger movement. Using transcranial magnetic stimulation (TMS) and paired peripheral stimulation, input-output recruitment curve and short-latency afferent inhibition (SAI) were measured in the first dorsal interosseus and abductor digiti minimi muscles during selective index finger flexion. Motor surround inhibition was present only at the onset phase, but not at the maintenance phase of movement. SAI was reduced at onset but not at the maintenance phase of movement in both active and surrounding muscles. Our study showed dynamic changes in corticospinal excitability and sensorimotor modulation for active and surrounding muscles in different movement states. SAI does not appear to contribute to motor surround inhibition at the movement onset phase. Also, there seems to be different inhibitory circuit(s) other than SAI for the movement maintenance phase in order to delineate the motor output selectively when corticospinal excitability is increased in both active and surrounding muscles. This study enhances our knowledge of dynamic changes in corticospinal excitability and sensorimotor interaction in different movement states to understand normal and disordered movements. Published by Elsevier Ireland Ltd.

Giant renin secretory granules in beige mouse renal afferent arterioles

DEFF Research Database (Denmark)

Jensen, B L; Rasch, Ruth; Nyengaard, Jens Randel

1997-01-01

The mutant beige mouse (C57BL/6 bg) has a disease characterised by abnormally enlarged cytoplasmic granules in a variety of cells. With the purpose of establishing a suitable cellular model for studying renin secretion, the present study was undertaken to compare renin granule morphology in beige...... (average granular volume 0.681 microm3), whereas 1-2 large granules were present per cell in beige mice. The volume of afferent arteriole that contained secretory granules was lower in the beige mice. We conclude that the beige mouse synthesizes, stores and releases active renin. Renin secretory granules...... in beige mice are grossly enlarged with 1-2 granules per juxtaglomerular cell. Compared with control mice, a similar amount of total renin granule volume per afferent arteriole is contained in a smaller part of beige mouse afferent arteriole. Granular cells from beige mice could therefore be a valuable...

Afferent connectivity of the zebrafish habenulae

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Katherine Jane Turner

2016-04-01

Full Text Available The habenulae are bilateral nuclei located in the dorsal diencephalon that are conserved across vertebrates.Here we describe the main afferents to the habenulae in larval and adult zebrafish.We observe afferents from the subpallium, nucleus rostrolateralis,posterior tuberculum, posterior hypothalamic lobe, median raphe, olfactory bulb to the right habenula and from the parapineal to the lefthabenula.In addition,we find afferents from a ventrolateral telencephalic nucleus that neurochemical and hodological data identify as the ventral entopeduncular nucleus(vENT,confirming and extending observations of Amo et al.(2014.Fate map and marker studies suggest that vENT originates from the diencephalic prethalamic eminence and extends into the lateral telencephalon from 48 to 120 hpf.No afferents to the habenula were observed from the dorsal entopeduncular nucleus(dENT.Consequently,we confirm that the vENT(and not the dENT should be considered as the entopeduncular nucleus proper in zebrafish.Furthermore,comparison with data in other vertebrates suggests that the vENT is a conserved basal ganglia nucleus,being homologous to the entopeduncular nucleus of mammals(internal segment of the globus pallidus of primates by both embryonic origin and projections,as previously suggested by Amo et al.(2014.Key words: habenula,connections,afferents,entopeduncular nucleus,posterior tuberculum,basal ganglia,zebrafish

Afferent Connectivity of the Zebrafish Habenulae

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Turner, Katherine J.; Hawkins, Thomas A.; Yáñez, Julián; Anadón, Ramón; Wilson, Stephen W.; Folgueira, Mónica

2016-01-01

The habenulae are bilateral nuclei located in the dorsal diencephalon that are conserved across vertebrates. Here we describe the main afferents to the habenulae in larval and adult zebrafish. We observe afferents from the subpallium, nucleus rostrolateralis, posterior tuberculum, posterior hypothalamic lobe, median raphe; we also see asymmetric afferents from olfactory bulb to the right habenula, and from the parapineal to the left habenula. In addition, we find afferents from a ventrolateral telencephalic nucleus that neurochemical and hodological data identify as the ventral entopeduncular nucleus (vENT), confirming and extending observations of Amo et al. (2014). Fate map and marker studies suggest that vENT originates from the diencephalic prethalamic eminence and extends into the lateral telencephalon from 48 to 120 hour post-fertilization (hpf). No afferents to the habenula were observed from the dorsal entopeduncular nucleus (dENT). Consequently, we confirm that the vENT (and not the dENT) should be considered as the entopeduncular nucleus “proper” in zebrafish. Furthermore, comparison with data in other vertebrates suggests that the vENT is a conserved basal ganglia nucleus, being homologous to the entopeduncular nucleus of mammals (internal segment of the globus pallidus of primates) by both embryonic origin and projections, as previously suggested by Amo et al. (2014). PMID:27199671

Transient receptor potential A1 channel contributes to activation of the muscle reflex.

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Koba, Satoshi; Hayes, Shawn G; Sinoway, Lawrence I

2011-01-01

This study was undertaken to elucidate the role played by transient receptor potential A1 channels (TRPA1) in activating the muscle reflex, a sympathoexcitatory drive originating in contracting muscle. First, we tested the hypothesis that stimulation of the TRPA1 located on muscle afferents reflexly increases sympathetic nerve activity. In decerebrate rats, allyl isothiocyanate, a TRPA1 agonist, was injected intra-arterially into the hindlimb muscle circulation. This led to a 33% increase in renal sympathetic nerve activity (RSNA). The effect of allyl isothiocyanate was a reflex because the response was prevented by sectioning the sciatic nerve. Second, we tested the hypothesis that blockade of TRPA1 reduces RSNA response to contraction. Thirty-second continuous static contraction of the hindlimb muscles, induced by electrical stimulation of the peripheral cut ends of L(4) and L(5) ventral roots, increased RSNA and blood pressure. The integrated RSNA during contraction was reduced by HC-030031, a TRPA1 antagonist, injected intra-arterially (163 ± 24 vs. 95 ± 21 arbitrary units, before vs. after HC-030031, P reflex. Increases in RSNA in response to injection into the muscle circulation of arachidonic acid, bradykinin, and diprotonated phosphate, which are metabolic by-products of contraction and stimulants of muscle afferents during contraction, were reduced by HC-030031. These observations suggest that the TRPA1 located on muscle afferents is part of the muscle reflex and further support the notion that arachidonic acid metabolites, bradykinin, and diprotonated phosphate are candidates for endogenous agonists of TRPA1.

[Acute pancreatitis and afferent loop syndrome. Case report].

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Barajas-Fregoso, Elpidio Manuel; Romero-Hernández, Teodoro; Macías-Amezcua, Michel Dassaejv

2013-01-01

The afferent syndrome loop is a mechanic obstruction of the afferent limb before a Billroth II or Roux-Y reconstruction, secondary in most of case to distal or subtotal gastrectomy. Clinical case: Male 76 years old, with antecedent of cholecystectomy, gastric adenocarcinoma six years ago, with subtotal gastrectomy and Roux-Y reconstruction. Beginning a several abdominal pain, nausea and vomiting, abdominal distension, without peritoneal irritation sings. Amylase 1246 U/L, lipase 3381 U/L. Computed Tomography with thickness wall and dilatation of afferent loop, pancreas with diffuse enlargement diagnostic of acute pancreatitis secondary an afferent loop syndrome. The afferent loop syndrome is presented in 0.3%-1% in all cases with Billroth II reconstruction, with a mortality of up to 57%, the obstruction lead accumulation of bile, pancreatic and intestinal secretions, increasing the pressure and resulting in afferent limb, bile conduct and Wirsung conduct dilatation, triggering an inflammatory response that culminates in pancreatic inflammation. The severity of the presentation is related to the degree and duration of the blockage.

The oculomotor system of decapod cephalopods: eye muscles, eye muscle nerves, and the oculomotor neurons in the central nervous system.

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Budelmann, B U; Young, J Z

1993-04-29

Fourteen extraocular eye muscles are described in the decapods Loligo and Sepioteuthis, and thirteen in Sepia; they are supplied by four eye muscle nerves. The main action of most of the muscles is a linear movement of the eyeball, only three muscles produce strong rotations. The arrangement, innervation and action of the decapod eye muscles are compared with those of the seven eye muscles and seven eye muscle nerves in Octopus. The extra muscles in decapods are attached to the anterior and superior faces of the eyes. At least, the anterior muscles, and presumably also the superior muscles, are concerned with convergent eye movements for binocular vision during fixation and capture of prey by the tentacles. The remaining muscles are rather similar in the two cephalopod groups. In decapods, the anterior muscles include conjunctive muscles; these cross the midline and each presumably moves both eyes at the same time during fixation. In the squids Loligo and Sepioteuthis there is an additional superior conjunctive muscle of perhaps similar function. Some of the anterior muscles are associated with a narrow moveable plate, the trochlear cartilage; it is attached to the eyeball by trochlear membranes. Centripetal cobalt fillings showed that all four eye muscle nerves have fibres that originate from somata in the ipsilateral anterior lateral pedal lobe, which is the oculomotor centre. The somata of the individual nerves show different but overlapping distributions. Bundles of small presumably afferent fibres were seen in two of the four nerves. They do not enter the anterior lateral pedal lobe but run to the ventral magnocellular lobe; some afferent fibres enter the brachio-palliovisceral connective and run perhaps as far as the palliovisceral lobe.

Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability

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Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

2017-01-01

Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 (n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 (n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability. PMID:28392766

Large Polyglutamine Repeats Cause Muscle Degeneration in SCA17 Mice

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Shanshan Huang

2015-10-01

Full Text Available In polyglutamine (polyQ diseases, large polyQ repeats cause juvenile cases with different symptoms than those of adult-onset patients, who carry smaller expanded polyQ repeats. The mechanisms behind the differential pathology mediated by different polyQ repeat lengths remain unknown. By studying knockin mouse models of spinal cerebellar ataxia-17 (SCA17, we found that a large polyQ (105 glutamines in the TATA-box-binding protein (TBP preferentially causes muscle degeneration and reduces the expression of muscle-specific genes. Direct expression of TBP with different polyQ repeats in mouse muscle revealed that muscle degeneration is mediated only by the large polyQ repeats. Different polyQ repeats differentially alter TBP’s interaction with neuronal and muscle-specific transcription factors. As a result, the large polyQ repeat decreases the association of MyoD with TBP and DNA promoters. Our findings suggest that specific alterations in protein interactions by large polyQ repeats may account for the unique pathology in juvenile polyQ diseases.

Large Polyglutamine Repeats Cause Muscle Degeneration in SCA17 Mice

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Huang, Shanshan; Yang, Su; Guo, Jifeng; Yan, Sen; Gaertig, Marta A.; Li, Shihua; Li, Xiao-Jiang

2015-01-01

SUMMARY In polyglutamine (polyQ) diseases, large polyQ repeats cause juvenile cases with different symptoms than adult-onset patients, who carry smaller expanded polyQ repeats. The mechanisms behind the differential pathology mediated by different polyQ repeat lengths remain unknown. By studying knock-in mouse models of spinal cerebellar ataxia-17 (SCA17), we found that a large polyQ (105 glutamines) in the TATA box-binding protein (TBP) preferentially causes muscle degeneration and reduces the expression of muscle-specific genes. Direct expression of TBP with different polyQ repeats in mouse muscle revealed that muscle degeneration is mediated only by the large polyQ repeats. Different polyQ repeats differentially alter TBP’s interaction with neuronal and muscle-specific transcription factors. As a result, the large polyQ repeat decreases the association of MyoD with TBP and DNA promoters. Our findings suggest that specific alterations in protein interactions by large polyQ repeats may account for the unique pathology in juvenile polyQ diseases. PMID:26387956

Profiling of G protein-coupled receptors in vagal afferents reveals novel gut-to-brain sensing mechanisms.

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Egerod, Kristoffer L; Petersen, Natalia; Timshel, Pascal N; Rekling, Jens C; Wang, Yibing; Liu, Qinghua; Schwartz, Thue W; Gautron, Laurent

2018-06-01

G protein-coupled receptors (GPCRs) act as transmembrane molecular sensors of neurotransmitters, hormones, nutrients, and metabolites. Because unmyelinated vagal afferents richly innervate the gastrointestinal mucosa, gut-derived molecules may directly modulate the activity of vagal afferents through GPCRs. However, the types of GPCRs expressed in vagal afferents are largely unknown. Here, we determined the expression profile of all GPCRs expressed in vagal afferents of the mouse, with a special emphasis on those innervating the gastrointestinal tract. Using a combination of high-throughput quantitative PCR, RNA sequencing, and in situ hybridization, we systematically quantified GPCRs expressed in vagal unmyelinated Na v 1.8-expressing afferents. GPCRs for gut hormones that were the most enriched in Na v 1.8-expressing vagal unmyelinated afferents included NTSR1, NPY2R, CCK1R, and to a lesser extent, GLP1R, but not GHSR and GIPR. Interestingly, both GLP1R and NPY2R were coexpressed with CCK1R. In contrast, NTSR1 was coexpressed with GPR65, a marker preferentially enriched in intestinal mucosal afferents. Only few microbiome-derived metabolite sensors such as GPR35 and, to a lesser extent, GPR119 and CaSR were identified in the Na v 1.8-expressing vagal afferents. GPCRs involved in lipid sensing and inflammation (e.g. CB1R, CYSLTR2, PTGER4), and neurotransmitters signaling (CHRM4, DRD2, CRHR2) were also highly enriched in Na v 1.8-expressing neurons. Finally, we identified 21 orphan GPCRs with unknown functions in vagal afferents. Overall, this study provides a comprehensive description of GPCR-dependent sensing mechanisms in vagal afferents, including novel coexpression patterns, and conceivably coaction of key receptors for gut-derived molecules involved in gut-brain communication. Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.

FUSIMOTOR EFFECTS OF MIDBRAIN STIMULATION ON JAW MUSCLE-SPINDLES OF THE ANESTHETIZED CAT

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TAYLOR, A; JUCH, PJW

The effects of electrical stimulation within the midbrain on fusimotor output to the jaw elevator muscles were studied in anaesthetized cats. Muscle spindle afferents recorded in the mesencephalic trigeminal nucleus were categorised as primary or secondary by their responses to succinylcholine

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) with chronic cough and preserved muscle stretch reflexes: evidence for selective sparing of afferent Ia fibres.

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Infante, Jon; García, Antonio; Serrano-Cárdenas, Karla M; González-Aguado, Rocío; Gazulla, José; de Lucas, Enrique M; Berciano, José

2018-04-25

The aim of this study was to describe five patients with cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) with chronic cough and preserved limb muscle stretch reflexes. All five patients were in the seventh decade of age, their gait imbalance having been initiated in the fifth decade. In four patients cough antedated gait imbalance between 15 and 29 years; cough was spasmodic and triggered by variable factors. Established clinical picture included severe hypopallesthesia predominating in the lower limbs with postural imbalance, and variable degree of cerebellar axial and appendicular ataxia, dysarthria and horizontal gaze-evoked nystagmus. Upper- and lower-limb tendon jerks were preserved, whereas jaw jerk was absent. Vestibular function testing showed bilateral impairment of the vestibulo-ocular reflex. Nerve conduction studies demonstrated normal motor conduction parameters and absence or severe attenuation of sensory nerve action potentials. Somatosensory evoked potentials were absent or severely attenuated. Biceps and femoral T-reflex recordings were normal, while masseter reflex was absent or attenuated. Sympathetic skin responses were normal. Cranial MRI showed vermian and hemispheric cerebellar atrophy predominating in lobules VI, VII and VIIa. We conclude that spasmodic cough may be an integral part of the clinical picture in CANVAS, antedating the appearance of imbalance in several decades and that sparing of muscle spindle afferents (Ia fibres) is probably the pathophysiological basis of normoreflexia.

Cerebro-afferent vessel and pupillary basal diameter variation induced by stomatognathic trigeminal proprioception: a case report.

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De Cicco, Vincenzo

2012-09-03

A patient affected by asymmetric hemodynamics of cerebro-afferent vessels underwent duplex color scanner investigations in occlusal proprioceptive un- and rebalance conditions. Pupillometric video-oculographic examinations were performed in order to spot connected trigeminal proprioceptive motor patterns able to interfere on sympathetic autonomic activity. The aim of this case report is to verify if involuntary jaw closing during swallowing, executed in unbalance and rebalance myoelectric activity, would be able to modify cerebral hemodynamics. A 56-year-old Caucasian Italian woman affected by asymmetric blood flow of cerebro-afferent vessels underwent an electromyographic investigation of her occlusal muscles in order to assess their occlusal functional balance. The extreme asymmetry of myoelectric activity in dental occlusion evidenced by electromyographic values suggested the rebalancing of the functions of occlusal muscles through concurrent transcutaneous stimulation of the trigeminal nerve supra- and submandibular motor branches. The above-mentioned method allowed the detection of a symmetric craniomandibular muscular relation that can be kept constant through the use of a cusp bite modeled on the inferior dental arch: called orthotic-syntropic bite for its peculiar use of electrostimulation. A few days later, the patient underwent a duplex color scanner investigation and pupillometric video-oculographic examinations in occlusal unbalance and rebalance conditions. A comparative data analysis showed that an unbalanced dental occlusal function may represent an interferential pattern on cerebral hemodynamics velocity and pupillometric evaluations have proved useful both in the analysis of locus coeruleus functional modalities and as a diagnostic tool in the assessment of pathologies involving locus coeruleus and autonomic systems. The inclusion of myoelectric masseter examinations can be useful in patients with asymmetric hemodynamics of cerebro-afferent

Convergence of cranial visceral afferents within the solitary tract nucleus.

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McDougall, Stuart J; Peters, James H; Andresen, Michael C

2009-10-14

Primary afferent axons within the solitary tract (ST) relay homeostatic information via glutamatergic synapses directly to second-order neurons within the nucleus of the solitary tract (NTS). These primary afferents arise from multiple organ systems and relay multiple sensory modalities. How this compact network organizes the flow of primary afferent information will shape central homeostatic control. To assess afferent convergence and divergence, we recorded ST-evoked synaptic responses in pairs of medial NTS neurons in horizontal brainstem slices. ST shocks activated EPSCs along monosynaptic or polysynaptic pathways. Gradations in shock intensity discriminated multiple inputs and stimulus recruitment profiles indicated that each EPSC was unitary. In 24 pairs, 75% were second-order neurons with 64% receiving one direct ST input with the remainder receiving additional convergent ST afferent inputs (22% two; 14% three monosynaptic ST-EPSCs). Some (34%) second-order neurons received polysynaptic EPSCs. Neurons receiving only higher-order inputs were uncommon (13%). Most ST-EPSCs were completely independent, but 4 EPSCs of a total of 81 had equal thresholds, highly correlated latencies, and synchronized synaptic failures consistent with divergence from a single source ST axon or from a common interneuron producing a pair of polysynaptic EPSCs. We conclude that ST afferent inputs are remarkably independent with little evidence of substantial shared information. Individual cells receive highly focused information from the viscera. Thus, afferent excitation of second-order NTS neurons is generally dominated by single visceral afferents and therefore focused on a single afferent modality and/or organ region.

Histological identification of phrenic afferent projections to the spinal cord.

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Nair, Jayakrishnan; Bezdudnaya, Tatiana; Zholudeva, Lyandysha V; Detloff, Megan R; Reier, Paul J; Lane, Michael A; Fuller, David D

2017-02-01

Limited data are available regarding the spinal projections of afferent fibers in the phrenic nerve. We describe a method that robustly labels phrenic afferent spinal projections in adult rats. The proximal end of the cut phrenic nerve was secured in a microtube filled with a transganglionic tracer (cholera toxin β-subunit, CT-β, or Cascade Blue) and tissues harvested 96-h later. Robust CT-β labeling occurred in C3-C5 dorsal root ganglia cell bodies and phrenic afferent projections were identified in the mid-cervical dorsal horn (laminae I-III), intermediate grey matter (laminae IV, VII) and near the central canal (laminae X). Afferent fiber labeling was reduced or absent when CT-β was delivered to the intrapleural space or directly to the hemidiaphragm. Soaking the phrenic nerve with Cascade Blue also produced robust labeling of mid-cervical dorsal root ganglia cells bodies, and primary afferent fibers were observed in spinal grey matter and dorsal white matter. Our results show that the 'nerve soak' method effectively labels both phrenic motoneurons and phrenic afferent projections, and show that primary afferents project throughout the ipsilateral mid-cervical gray matter. Copyright © 2016. Published by Elsevier B.V.

Afferent loop syndrome: Role of sonography and CT

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Lee, Dong Ho; Lim, Jae Hoon; Ko, Young Tae [Kyung Hee University Hospital, Seoul (Korea, Republic of)

1992-03-15

Afferent loop syndrome(ALS) is caused by obstruction of the afferent loop after subtotal gastrectomy with Billroth II gastrojejunostomy. Prompt diagnosis of ALS is important as perforation of the loop occurs. The aim of study is to ascertain the sonography and CT to diagnose ALS. We describe the radiologic findings in ten patients with ALS. The cause of ALS, established at surgery, included cancer recurrence (n=4), internal hernia (n=4), marginal ulcer (n=1), and development of cancer at the anastomosis site (n=1). Abdominal X-ray and sonography were performed in all cases, upper GI series in five cases and computed tomography in two cases. The dilated afferent loop was detected in only two cases out often patients in retrospective review of abdominal X-ray. ALS with recurrence of cancer was diagnosed in three cases by upper GI series. Of the cases that had sonography, the afferent loop was seen in the upper abdomen crossing transversely over the midline in all ten patients. The cause of ALS were predicated on the basis of the sonograms in three of the five patients. In two cases of computed tomography, the dilated afferent loop and recurrent cancer at the remnant stomach were seen.Our experience suggests that the diagnosis of afferent syndrome can be made on the basis of the typical anatomic location and shape of the dilated bowel loop in both sonography and computed tomography.

Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow.

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Jensen, Elisa P; Poulsen, Steen S; Kissow, Hannelouise; Holstein-Rathlou, Niels-Henrik; Deacon, Carolyn F; Jensen, Boye L; Holst, Jens J; Sorensen, Charlotte M

2015-04-15

Glucagon-like peptide (GLP)-1 has a range of extrapancreatic effects, including renal effects. The mechanisms are poorly understood, but GLP-1 receptors have been identified in the kidney. However, the exact cellular localization of the renal receptors is poorly described. The aim of the present study was to localize renal GLP-1 receptors and describe GLP-1-mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and that activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using (125)I-labeled GLP-1, (125)I-labeled exendin-4 (GLP-1 analog), and (125)I-labeled exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1-mediated effects on blood pressure, renal blood flow (RBF), heart rate, renin secretion, urinary flow rate, and Na(+) and K(+) excretion were investigated in anesthetized rats. Effects of GLP-1 on afferent arterioles were investigated in isolated mouse kidneys. Specific binding of (125)I-labeled GLP-1, (125)I-labeled exendin-4, and (125)I-labeled exendin 9-39 was observed in the renal vasculature, including afferent arterioles. Infusion of GLP-1 increased blood pressure, RBF, and urinary flow rate significantly in rats. Heart rate and plasma renin concentrations were unchanged. Exendin 9-39 inhibited the increase in RBF. In isolated murine kidneys, GLP-1 and exendin-4 significantly reduced the autoregulatory response of afferent arterioles in response to stepwise increases in pressure. We conclude that GLP-1 receptors are located in the renal vasculature, including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases RBF in normotensive rats. Copyright © 2015 the American Physiological Society.

Jaw-muscle fiber architecture in tufted capuchins favors generating relatively large muscle forces without compromising jaw gape

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Taylor, Andrea B.; Vinyard, Christopher J.

2009-01-01

Cebus apella is renowned for its dietary flexibility and capacity to exploit hard and tough objects. Cebus apella differs from other capuchins in displaying a suite of craniodental features that have been functionally and adaptively linked to their feeding behavior, particularly the generation and dissipation of relatively large jaw forces. We compared fiber architecture of the masseter and temporalis muscles between the tufted capuchin (C. apella; n = 12 ) and two “untufted” capuchins (C. capuchinus, n = 3; C. albifrons, n = 5). These three species share broadly similar diets, but tufted capuchins occasionally exploit mechanically challenging tissues. We tested the hypothesis that C. apella exhibits architectural properties of their jaw muscles that facilitate relatively large forces, including relatively greater physiologic cross-sectional areas (PCSA), more pinnate fibers, and lower ratios of mass to tetanic tension (Mass/P0). Results show some evidence supporting these predictions, as C. apella has relatively greater superficial masseter, whole masseter, and temporalis PCSAs, significantly so only for the temporalis following Bonferroni adjustment. Capuchins did not differ in pinnation angle or Mass/P0. As an architectural trade-off between maximizing muscle force and muscle excursion/contraction velocity, we also tested the hypothesis that C. apella exhibits relatively shorter muscle fibers. Contrary to our prediction, there are no significant differences in relative fiber lengths between tufted and untufted capuchins. Therefore, we attribute the relatively greater PCSAs in C. apella primarily to their larger muscle masses. These findings suggest that relatively large jaw-muscle PCSAs can be added to the suite of masticatory features that have been functionally linked to the exploitation of a more resistant diet by C. apella. By enlarging jaw-muscle mass to increase PCSA, rather than reducing fiber lengths and increasing pinnation, tufted capuchins appear

A new function for ATP: activating cardiac sympathetic afferents during myocardial ischemia.

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Fu, Liang-Wu; Longhurst, John C

2010-12-01

Myocardial ischemia activates cardiac sympathetic afferents leading to chest pain and reflex cardiovascular responses. Brief myocardial ischemia leads to ATP release in the interstitial space. Furthermore, exogenous ATP and α,β-methylene ATP (α,β-meATP), a P2X receptor agonist, stimulate cutaneous group III and IV sensory nerve fibers. The present study tested the hypothesis that endogenous ATP excites cardiac afferents during ischemia through activation of P2 receptors. Nerve activity of single unit cardiac sympathetic afferents was recorded from the left sympathetic chain or rami communicates (T(2)-T(5)) in anesthetized cats. Single fields of 45 afferents (conduction velocities = 0.25-4.92 m/s) were identified in the left ventricle with a stimulating electrode. Five minutes of myocardial ischemia stimulated 39 of 45 cardiac afferents (8 Aδ, 37 C fibers). Epicardial application of ATP (1-4 μmol) stimulated six ischemically sensitive cardiac afferents in a dose-dependent manner. Additionally, epicardial ATP (2 μmol), ADP (2 μmol), a P2Y agonist, and α,β-meATP (0.5 μmol) significantly activated eight other ischemically sensitive afferents. Third, pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid, a P2 receptor antagonist, abolished the responses of six afferents to epicardial ATP (2 μmol) and attenuated the ischemia-related increase in activity of seven other afferents by 37%. In the absence of P2 receptor blockade, cardiac afferents responded consistently to repeated application of ATP (n = 6) and to recurrent myocardial ischemia (n = 6). Finally, six ischemia-insensitive cardiac spinal afferents did not respond to epicardial ATP (2-4 μmol), although these afferents did respond to epicardial bradykinin. Taken together, these data indicate that, during ischemia, endogenously released ATP activates ischemia-sensitive, but not ischemia-insensitive, cardiac spinal afferents through stimulation of P2 receptors likely located on the cardiac sensory

The effect of type of afferent feedback timed with motor imagery on the induction of cortical plasticity

DEFF Research Database (Denmark)

Mrachacz-Kersting, Natalie; Voigt, Michael; Stevenson, Andrew James Thomas

2017-01-01

: 8-35 mAmp) or a passive ankle movement (amplitude and velocity matched to a normal gait cycle) was applied such that the first afferent inflow would coincide with the PN of the MRCP. The change in the output of the primary motor cortex (M1) was quantified by applying single transcranial magnetic...... compared these two interventions (BCIFES and BCIpassive) where the afferent input was timed to arrive at the motor cortex during the PN of the MRCP. Twelve healthy participants attended two experimental sessions. They were asked to perform 30 dorsiflexion movements timed to a cue while continuous...... stimuli to the area of M1 controlling the tibialis anterior (TA) muscle and measuring the motor evoked potential (MEP). Spinal changes were assessed pre and post by eliciting the TA stretch reflex. Both BCIFES and BCIpassive led to significant increases in the excitability of the cortical projections...

Afferent activity to necklace glomeruli is dependent on external stimuli

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Munger Steven D

2009-03-01

Full Text Available Abstract Background The main olfactory epithelium (MOE is a complex organ containing several functionally distinct subpopulations of sensory neurons. One such subpopulation is distinguished by its expression of the guanylyl cyclase GC-D. The axons of GC-D-expressing (GC-D+ neurons innervate 9–15 "necklace" glomeruli encircling the caudal main olfactory bulb (MOB. Chemosensory stimuli for GC-D+ neurons include two natriuretic peptides, uroguanylin and guanylin, and CO2. However, the biologically-relevant source of these chemostimuli is unclear: uroguanylin is both excreted in urine, a rich source of olfactory stimuli for rodents, and expressed in human nasal epithelium; CO2 is present in both inspired and expired air. Findings To determine whether the principal source of chemostimuli for GC-D+ neurons is external or internal to the nose, we assessed the consequences of removing external chemostimuli for afferent activity to the necklace glomeruli. To do so, we performed unilateral naris occlusions in Gucy2d-Mapt-lacZ +/- mice [which express a β-galactosidase (β-gal reporter specifically in GC-D+ neurons] followed by immunohistochemistry for β-gal and a glomerular marker of afferent activity, tyrosine hydroxylase (TH. We observed a dramatic decrease in TH immunostaining, consistent with reduced or absent afferent activity, in both necklace and non-necklace glomeruli ipsilateral to the occluded naris. Conclusion Like other MOB glomeruli, necklace glomeruli exhibit a large decrease in afferent activity upon removal of external stimuli. Thus, we conclude that activity in GC-D+ neurons, which specifically innervate necklace glomeruli, is not dependent on internal stimuli. Instead, GC-D+ neurons, like other OSNs in the MOE, primarily sense the external world.

Tuning of spinal networks to frequency components of spike trains in individual afferents.

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Koerber, H R; Seymour, A W; Mendell, L M

1991-10-01

Cord dorsum potentials (CDPs) evoked by primary afferent fiber stimulation reflect the response of postsynaptic dorsal horn neurons. The properties of these CDPs have been shown to vary in accordance with the type of primary afferent fiber stimulated. The purpose of the present study was to determine the relationships between frequency modulation of the afferent input trains, the amplitude modulation of the evoked CDPs, and the type of primary afferent stimulated. The somata of individual primary afferent fibers were impaled in the L7 dorsal root ganglion of alpha-chloralose-anesthetized cats. Action potentials (APs) were evoked in single identified afferents via the intracellular microelectrode while simultaneously recording the response of dorsal horn neurons as CDPs, or activity of individual target interneurons recorded extracellularly or intracellularly. APs were evoked in afferents using temporal patterns identical to the responses of selected afferents to natural stimulation of their receptive fields. Two such physiologically realistic trains, one recorded from a hair follicle and the other from a slowly adapting type 1 receptor, were chosen as standard test trains. Modulation of CDP amplitude in response to this frequency-modulated afferent activity varied according to the type of peripheral mechanoreceptor innervated. Dorsal horn networks driven by A beta afferents innervating hair follicles, rapidly adapting pad (Krause end bulb), and field receptors seemed "tuned" to amplify the onset of activity in single afferents. Networks driven by afferents innervating down hair follicles and pacinian corpuscles required more high-frequency activity to elicit their peak response. Dorsal horn networks driven by afferents innervating slowly adapting receptors including high-threshold mechanoreceptors exhibited some sensitivity to the instantaneous frequency, but in general they reproduced the activity in the afferent fiber much more faithfully. Responses of

Presynaptic control of group Ia afferents in relation to acquisition of a visuo-motor skill in healthy humans

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Perez, Monica A.; Lungholt, Bjarke K.S.; Nielsen, Jens Bo

2005-01-01

Sensory information continuously converges on the spinal cord during a variety of motor behaviours. Here, we examined presynaptic control of group Ia afferents in relation to acquisition of a novel motor skill. We tested whether repetition of two motor tasks with different degrees of difficulty......, a novel visuo-motor task involving the ankle muscles, and a control task involving simple voluntary ankle movements, would induce changes in the size of the soleus H-reflex. The slope of the H-reflex recruitment curve and the H-max/M-max ratio were depressed after repetition of the visuo-motor skill task...... of the monosynaptic Ia facilitation of the soleus H-reflex evoked by femoral nerve stimulation. The D1 inhibition was increased and the femoral nerve facilitation was decreased following the visuo-motor skill task, suggesting an increase in presynaptic inhibition of Ia afferents. No changes were observed...

Cross-Modal Calibration of Vestibular Afference for Human Balance.

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Martin E Héroux

Full Text Available To determine how the vestibular sense controls balance, we used instantaneous head angular velocity to drive a galvanic vestibular stimulus so that afference would signal that head movement was faster or slower than actual. In effect, this changed vestibular afferent gain. This increased sway 4-fold when subjects (N = 8 stood without vision. However, after a 240 s conditioning period with stable balance achieved through reliable visual or somatosensory cues, sway returned to normal. An equivalent galvanic stimulus unrelated to sway (not driven by head motion was equally destabilising but in this situation the conditioning period of stable balance did not reduce sway. Reflex muscle responses evoked by an independent, higher bandwidth vestibular stimulus were initially reduced in amplitude by the galvanic stimulus but returned to normal levels after the conditioning period, contrary to predictions that they would decrease after adaptation to increased sensory gain and increase after adaptation to decreased sensory gain. We conclude that an erroneous vestibular signal of head motion during standing has profound effects on balance control. If it is unrelated to current head motion, the CNS has no immediate mechanism of ignoring the vestibular signal to reduce its influence on destabilising balance. This result is inconsistent with sensory reweighting based on disturbances. The increase in sway with increased sensory gain is also inconsistent with a simple feedback model of vestibular reflex action. Thus, we propose that recalibration of a forward sensory model best explains the reinterpretation of an altered reafferent signal of head motion during stable balance.

Isolation of TRPV1 independent mechanisms of spontaneous and asynchronous glutamate release at primary afferent to NTS synapses.

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Axel J. Fenwick

2014-01-01

Full Text Available Cranial visceral afferents contained within the solitary tract (ST contact second-order neurons in the nucleus of the solitary tract (NTS and release the excitatory amino acid glutamate via three distinct exocytosis pathways; synchronous, asynchronous, and spontaneous release. The presence of TRPV1 in the central terminals of a majority of ST afferents conveys activity-dependent asynchronous glutamate release and provides a temperature sensitive calcium conductance which largely determines the rate of spontaneous vesicle fusion. TRPV1 is present in unmyelinated C-fiber afferents and these facilitated forms of glutamate release may underlie the relative strength of C-fibers in activating autonomic reflex pathways. However, pharmacological blockade of TRPV1 signaling eliminates only ~50% of the asynchronous profile and attenuates the temperature sensitivity of spontaneous release indicating additional thermosensitive calcium influx pathways may exist which mediate these forms of vesicle release. In the present study we isolate the contribution of TRPV1 independent forms of glutamate release at ST-NTS synapses. We found ST afferent innervation at NTS neurons and synchronous vesicle release from TRPV1 KO mice was not different to control animals; however, only half of TRPV1 KO ST afferents completely lacked asynchronous glutamate release. Further, temperature driven spontaneous rates of vesicle release were not different from 33˚ - 37˚C between control and TRPV1 KO afferents. These findings suggest additional temperature dependent mechanisms controlling asynchronous and thermosensitive spontaneous release at physiological temperatures, possibly mediated by additional thermosensitive TRP channels in primary afferent terminals.

Expression of the transient receptor potential channels TRPV1, TRPA1 and TRPM8 in mouse trigeminal primary afferent neurons innervating the dura

Science.gov (United States)

2012-01-01

Background Migraine and other headache disorders affect a large percentage of the population and cause debilitating pain. Activation and sensitization of the trigeminal primary afferent neurons innervating the dura and cerebral vessels is a crucial step in the “headache circuit”. Many dural afferent neurons respond to algesic and inflammatory agents. Given the clear role of the transient receptor potential (TRP) family of channels in both sensing chemical stimulants and mediating inflammatory pain, we investigated the expression of TRP channels in dural afferent neurons. Methods We used two fluorescent tracers to retrogradely label dural afferent neurons in adult mice and quantified the abundance of peptidergic and non-peptidergic neuron populations using calcitonin gene-related peptide immunoreactivity (CGRP-ir) and isolectin B4 (IB4) binding as markers, respectively. Using immunohistochemistry, we compared the expression of TRPV1 and TRPA1 channels in dural afferent neurons with the expression in total trigeminal ganglion (TG) neurons. To examine the distribution of TRPM8 channels, we labeled dural afferent neurons in mice expressing farnesylated enhanced green fluorescent protein (EGFPf) from a TRPM8 locus. We used nearest-neighbor measurement to predict the spatial association between dural afferent neurons and neurons expressing TRPA1 or TRPM8 channels in the TG. Results and conclusions We report that the size of dural afferent neurons is significantly larger than that of total TG neurons and facial skin afferents. Approximately 40% of dural afferent neurons exhibit IB4 binding. Surprisingly, the percentage of dural afferent neurons containing CGRP-ir is significantly lower than those of total TG neurons and facial skin afferents. Both TRPV1 and TRPA1 channels are expressed in dural afferent neurons. Furthermore, nearest-neighbor measurement indicates that TRPA1-expressing neurons are clustered around a subset of dural afferent neurons. Interestingly, TRPM

Role of capsaicin- and heat-sensitive afferents in stimulation of acupoint-induced pain and analgesia in humans.

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Lei, Jing; Ye, Gang; Wu, Jiang-Tao; Pertovaara, Antti; You, Hao-Jun

2017-09-01

We investigated role of capsaicin-sensitive afferents within and without the areas of Zusanli (ST36)/Shangjuxu (ST37) acupoints along the stomach (ST) meridian in the perception and modulation of pain assessed by visual analog scale of pain and its distribution rated by subjects, pressure pain threshold (PPT), and heat pain threshold (HPT) in humans. Compared with the treatment of non-acupoint area, capsaicin (100µg/50µl) administered into either ST36 or ST37 acupoint caused the strongest pain intensity and the most extensive pain distribution, followed by rapid onset, bilateral, long-lasting secondary mechanical hyperalgesia and slower onset secondary heat hypoalgesia (1day after the capsaicin treatment). Between treatments of different acupoints, capsaicin administrated into the ST36 acupoint exhibited the stronger pain intensity and more widespread pain distribution compared with the treatment of ST37 acupoint. A period of 30- to 45-min, but not 15-min, 43°C heating-needle stimulation applied to the ST36 acupoint significantly enhanced the HPT, and had no effect on PPT. Upon trapezius muscle pain elicited by the i.m. injection of 5.8% saline, pre-emptive treatment of the contralateral ST36 acupoint with 43°C heating-needle stimulation alleviated the ongoing muscle pain, reduced painful area, and reversed the decrease in HPT. It is suggested that (1) pain elicited from the acupoint and non-acupoint areas differs significantly, which are supposed to be dependent on the different distributions and contributions of capsaicin-sensitive afferents. (2) Non-painful heat stimulation is a valid approach in prevention of ongoing muscle pain with associated post-effects of peripheral and central sensitization. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Abnormal muscle afferent function in a model of Taxol chemotherapy-induced painful neuropathy

OpenAIRE

Chen, Xiaojie; Green, Paul G.; Levine, Jon D.

2011-01-01

Despite muscle pain being a well-described symptom in patients with diverse forms of peripheral neuropathy, the role of neuropathic mechanisms in muscle pain have received remarkably little attention. We have recently demonstrated in a well-established model of chemotherapy-induced painful neuropathy (CIPN) that the anti-tumor drug paclitaxel (Taxol) produces mechanical hyperalgesia in skeletal muscle, of similar time course to and with shared mechanism with cutaneous symptoms. In the present...

Mechano- and metabosensitive alterations after injection of botulinum toxin into gastrocnemius muscle.

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Caron, Guillaume; Rouzi, Talifujiang; Grelot, Laurent; Magalon, Guy; Marqueste, Tanguy; Decherchi, Patrick

2014-07-01

This study was designed to investigate effects of motor denervation by Clostridium botulinum toxin serotype A (BoNT/A) on the afferent activity of fibers originating from the gastrocnemius muscle of rats. Animals were randomized in two groups, 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle. Locomotor activity was evaluated once per day during 12 days with a test based on footprint measurements of walking rats (sciatic functional index). At the end of the functional assessment period, electrophysiological tests were used to measure muscle properties, metabosensitive afferent fiber responses to chemical (KCl and lactic acid) injections, electrically induced fatigue (EIF), and mechanosensitive responses to tendon vibrations. Additionally, ventilatory response was recorded during repetitive muscle contractions. Then, rats were sacrificed, and the BoNT/A-injected muscles were weighed. Twelve days postinjection we observed a complete motor denervation associated with a significant muscle atrophy and loss of force to direct muscle stimulation. In the BoNT/A group, the metabosensitive responses to KCl injections were unaltered. However, we observed alterations in responses to EIF and to 1 mM of lactic acid (which induces the greatest activation). The ventilatory adjustments during repetitive muscle activation were abolished, and the mechanosensitive fiber responses to tendon vibrations were reduced. These results indicate that BoNT/A alters the sensorimotor loop and may induce insufficient motor and physiological adjustments in patients in whom a motor denervation with BoNT/A was performed. Copyright © 2014 Wiley Periodicals, Inc.

Artificial control of muscle by endoneural multi electrode stimulation and sensing

NARCIS (Netherlands)

Rutten, Wim; Bouwman, R.L.M.

1991-01-01

Artificial electrical stimulation of motor nerves for muscle control can be made selective by using intrafascicular micro electrode arrays which contact many individual or small groups of nerve fibres. If at the same time te electrode arrays could record afferent information from the stimulated

Functional recovery of anterior semicircular canal afferents following hair cell regeneration in birds

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Boyle, Richard; Highstein, Stephen M.; Carey, John P.; Xu, Jinping

2002-01-01

Streptomycin sulfate (1.2 g/kg i.m.) was administered for 5 consecutive days to 5-7-day-old white Leghorn chicks; this causes damage to semicircular canal hair cells that ultimately regenerate to reform the sensory epithelium. During the recovery period, electrophysiological recordings were taken sequentially from anterior semicircular canal primary afferents using an indentation stimulus of the canal that has been shown to mimic rotational stimulation. Chicks were assigned to an early (14-18 days; n = 8), intermediate (28-34 days; n = 5), and late (38-58 days; n = 4) period based on days after treatment. Seven untreated chicks, 15-67 days old, provided control data. An absence of background and indent-induced discharge was the prominent feature of afferents in the early period: only "silent" afferents were encountered in 5/8 experiments. In several of these chicks, fascicles of afferent fibers were seen extending up to the epithelium that was void of hair cells, and intra- and extracellular biocytin labeling revealed afferent processes penetrating into the supporting cell layer of the crista. In 3/8 chicks 74 afferents could be characterized, and they significantly differed from controls (n = 130) by having a lower discharge rate and a negligible response to canal stimulation. In the intermediate period there was considerable variability in discharge properties of 121 afferents, but as a whole the number of "silent" fibers in the canal nerve diminished, the background rate increased, and a response to canal stimulation detected. Individually biocytin-labeled afferents had normal-appearing terminal specializations in the sensory epithelium by 28 days poststreptomycin. In the late period, afferents (n = 58) remained significantly different from controls in background discharge properties and response gain. The evidence suggests that a considerable amount of variability exists between chicks in the return of vestibular afferent function following ototoxic injury and

Fine structural survey of the intermediate subnucleus of the nucleus tractus solitarii and its glossopharyngeal afferent terminals.

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Hayakawa, Tetsu; Maeda, Seishi; Tanaka, Koichi; Seki, Makoto

2005-10-01

The intermediate subnucleus of the nucleus tractus solitarii (imNTS) receives somatosensory inputs from the soft palate and pharynx, and projects onto the nucleus ambiguus, thus serving as a relay nucleus for swallowing. The ultrastructure and synaptology of the rat imNTS, and its glossopharyngeal afferent terminals, have been examined with cholera toxin-conjugated horseradish peroxidase (CT-HRP) as an anterograde tracer. The imNTS contained oval or ellipsoid-shaped, small to medium-sized neurons (18.2 x 11.4 microm) with little cytoplasm, few cell organelles and an irregularly shaped nucleus. The cytoplasm often contained one or two nucleolus-like stigmoid bodies. The average number of axosomatic terminals was 1.8 per profile. About 83% of them contained round vesicles and formed asymmetric synaptic contacts (Gray's type I), while about 17% contained pleomorphic vesicles and formed symmetric synaptic contacts (Gray's type II). The neuropil contained small or large axodendritic terminals, and about 92% of them were Gray's type I. When CT-HRP was injected into the nodose ganglion, many labeled terminals were found in the imNTS. All anterogradely labeled terminals contacted dendrites but not somata. The labeled terminals were usually large (2.69+/-0.09 mum) and exclusively of Gray's type I. They often contacted more than two dendrites, were covered with glial processes, and formed synaptic glomeruli. A small unlabeled terminal occasionally made an asymmetric synaptic contact with a large labeled terminal. The large glossopharyngeal afferent terminals and the neurons containing stigmoid bodies characterized the imNTS neurons that received pharyngeal afferents.

Common neural structures activated by epidural and transcutaneous lumbar spinal cord stimulation: Elicitation of posterior root-muscle reflexes.

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Ursula S Hofstoetter

Full Text Available Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diameter afferent fibers within lumbar and upper sacral posterior roots. Recent pilot studies suggested that the surface electrode-based method of transcutaneous spinal cord stimulation (SCS may produce similar neuromodulatory effects as caused by epidural SCS. Neurophysiological and computer modeling studies proposed that this noninvasive technique stimulates posterior-root fibers as well, likely activating similar input structures to the spinal cord as epidural stimulation. Here, we add a yet missing piece of evidence substantiating this assumption. We conducted in-depth analyses and direct comparisons of the electromyographic (EMG characteristics of short-latency responses in multiple leg muscles to both stimulation techniques derived from ten individuals with SCI each. Post-activation depression of responses evoked by paired pulses applied either epidurally or transcutaneously confirmed the reflex nature of the responses. The muscle responses to both techniques had the same latencies, EMG peak-to-peak amplitudes, and waveforms, except for smaller responses with shorter onset latencies in the triceps surae muscle group and shorter offsets of the responses in the biceps femoris muscle during epidural stimulation. Responses obtained in three subjects tested with both methods at different time points had near-identical waveforms per muscle group as well as same onset latencies. The present results strongly corroborate the activation of common neural input structures to the lumbar spinal cord-predominantly primary afferent fibers within multiple posterior roots-by both techniques and add to unraveling the

TRPV1 marks synaptic segregation of multiple convergent afferents at the rat medial solitary tract nucleus.

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James H Peters

Full Text Available TRPV1 receptors are expressed on most but not all central terminals of cranial visceral afferents in the caudal solitary tract nucleus (NTS. TRPV1 is associated with unmyelinated C-fiber afferents. Both TRPV1+ and TRPV1- afferents enter NTS but their precise organization remains poorly understood. In horizontal brainstem slices, we activated solitary tract (ST afferents and recorded ST-evoked glutamatergic excitatory synaptic currents (ST-EPSCs under whole cell voltage clamp conditions from neurons of the medial subnucleus. Electrical shocks to the ST produced fixed latency EPSCs (jitter<200 µs that identified direct ST afferent innervation. Graded increases in shock intensity often recruited more than one ST afferent and ST-EPSCs had consistent threshold intensity, latency to onset, and unique EPSC waveforms that characterized each unitary ST afferent contact. The TRPV1 agonist capsaicin (100 nM blocked the evoked TRPV1+ ST-EPSCs and defined them as either TRPV1+ or TRPV1- inputs. No partial responses to capsaicin were observed so that in NTS neurons that received one or multiple (2-5 direct ST afferent inputs--all were either blocked by capsaicin or were unaltered. Since TRPV1 mediates asynchronous release following TRPV1+ ST-evoked EPSCs, we likewise found that recruiting more than one ST afferent further augmented the asynchronous response and was eliminated by capsaicin. Thus, TRPV1+ and TRPV1- afferents are completely segregated to separate NTS neurons. As a result, the TRPV1 receptor augments glutamate release only within unmyelinated afferent pathways in caudal medial NTS and our work indicates a complete separation of C-type from A-type afferent information at these first central neurons.

Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow

DEFF Research Database (Denmark)

Jensen, Elisa Pouline; Poulsen, Steen Seier; Kissow, Hannelouise

2015-01-01

was to localize renal GLP-1 receptors and describe GLP-1 mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using 125I-GLP-1......, 125I-exendin-4 (GLP-1 analog) and 125I-exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1 mediated effects on blood pressure (BP), renal blood flow (RBF), heart rate (HR), renin secretion, urinary flow rate and Na+ and K+ excretion were...... conclude that GLP-1 receptors are located in the renal vasculature including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases renal blood flow in normotensive rats....

Role of TRPV1 and ASIC3 channels in experimental occlusal interference-induced hyperalgesia in rat masseter muscle.

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Xu, X X; Cao, Y; Ding, T T; Fu, K Y; Li, Y; Xie, Q F

2016-04-01

Masticatory muscle pain may occur following immediate occlusal alteration by dental treatment. The underlying mechanisms are poorly understood. Transient receptor potential vanilloid-1 (TRPV1) and acid-sensing ion channel-3 (ASIC3) mediate muscle hyperalgesia under various pathologic conditions. We have developed a rat model of experimental occlusal interference (EOI) that consistently induces mechanical hyperalgesia in jaw muscles. Whether TRPV1 and ASIC3 mediate this EOI-induced hyperalgesia is unknown. Rat model of EOI-induced masseter hyperalgesia was established. Real-time polymerase chain reaction, Western blot and retrograde labelling combined with immunofluorescence were performed to evaluate the modulation of TRPV1 and ASIC3 expression in trigeminal ganglia (TGs) and masseter afferents of rats after EOI. The effects of intramuscular administration of TRPV1 and ASIC3 antagonists on the EOI-induced hyperalgesia in masseter muscle were examined. After EOI, gene expressions and protein levels of TRPV1 and ASIC3 in bilateral TGs were up-regulated. The percentage of ASIC3- (but not TRPV1-) positive neurons in masseter afferents increased after EOI. More small-sized and small to medium-sized masseter afferents expressed TRPV1 and ASIC3 separately following EOI. These changes peaked at day 7 and then returned to original status within 10 days after EOI. Intramuscular administration of the TRPV1 antagonist AMG-9810 partially reversed this mechanical hyperalgesia in masseter muscle. No improvement was exhibited after administration of the ASIC3 antagonist APETx2. Co-injection of AMG-9810 and APETx2 enhanced the effect of AMG-9810 administration alone. Peripheral TRPV1 and ASIC3 contribute to the development of the EOI-induced mechanical hyperalgesia in masseter muscle. © 2015 European Pain Federation - EFIC®

MR features of a case of afferent loop syndrome presenting as obstructive jaundice

International Nuclear Information System (INIS)

Chevallier, P.; Souci, J.; Oddo, F.; Diaine, B.; Padovani, B.; Gueyffier, C.

2001-01-01

The afferent loop syndrome corresponds to an acute or chronic obstruction of the afferent loop following a partial gastrectomy with Billroth II gastro-jejunal anastomosis. We describe the case of a 77-year-old man with history of partial gastrectomy for peptic ulcer disease performed 31 years ago and currently admitted for jaundice and poor general status. MR imaging showed dilatation of biliary and pancreatic ducts and showed a soft tissue mass between the afferent loop and the residual stomach. Endoscopy showed complete obstruction of the afferent loop by a biopsy-proven adenocarcinoma. The patient died of sepsis shortly after endoscopy of septicemia. (authors)

Neck muscle vibration can improve sensorimotor function in patients with neck pain.

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Beinert, Konstantin; Keller, Martin; Taube, Wolfgang

2015-03-01

People with neck pain display a diminished joint position sense and disturbed postural control, which is thought to be a result of impaired somatosensory afferent activity and/or integration. Afferent processing can be artificially manipulated by vibration and was shown to reduce motor performance in healthy subjects. However, the effect of vibration on sensorimotor function in neck pain patients is scarcely investigated. To assess the effect of neck muscle vibration on joint position sense and postural control in neck pain subjects and healthy controls. Case control study. Thirteen neck pain patients and 10 healthy controls participated in the present study. Cervical joint position sense and dynamic and static postural stability. Short-term, targeted neck muscle vibration with 100 Hz was applied after baseline measurement. Vibration had opposite effects in patients and healthy subjects. Patients showed improved joint position sense (pneck pain. Thus, vibration may be used to counteract sensorimotor impairment of the cervical spine. Potential underlying mechanisms are discussed. Copyright © 2015. Published by Elsevier Inc.

Afferent control of central pattern generators: experimental analysis of scratching in the decerebrate cat.

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Baev, K V; Esipenko, V B; Shimansky, Y P

1991-01-01

Systematic quantitative analysis of changes in the spinal scratching generator motor activity evoked by tonic and phasic peripheral afferent signals during "fictitious" scratching was carried out in the cat. Correlations between the kinematics of hindlimb scratching movement, sensory inflow, and primary afferent depolarization were investigated. Reliable correlations between the parameters of generator motor activity during fictitious scratching were revealed: they depended on tonic peripheral afferent inflow. The functional role of these dependencies consists of providing stability for aiming the hindlimb to the itch site. It was shown that scratching generator reaction to a phasic sensory signal depended significantly on afferent input, signal intensity, and its arrival phase in the cycle of motor activity. Phase correction of "scratching" rhythm was performed by inhibition of the current stage of "scratching" cycle, the inhibition magnitude depending on the intensity of a sensory signal run along high threshold afferent fibers. The moments in the scratching cycle, in which the afferent signal caused no rearrangement in scratching generator activity, were discovered for all investigated afferent inputs. These moments corresponded to the transitions from one scratching cycle phase to another. Integral afferent activity was distributed unevenly in the cycle during real scratching. The main part of it was observed just in that scratching cycle part which included the above mentioned no rearrangement phase points. The data obtained allowed us to conclude that the scratching generator should be considered as a working program for the motor optimal control system containing the intrinsic model of the controlled object dynamics (e.g. hindlimb scratching movement dynamics), which produces an inner analog of peripheral flow. This inner flow interacts with peripheral afferent inflow just as one of the latter components. Centrally originated modulation of primary afferent

Limb venous distension evokes sympathetic activation via stimulation of the limb afferents in humans

Science.gov (United States)

Cui, Jian; McQuillan, Patrick M.; Blaha, Cheryl; Kunselman, Allen R.

2012-01-01

We have recently shown that a saline infusion in the veins of an arterially occluded human forearm evokes a systemic response with increases in muscle sympathetic nerve activity (MSNA) and blood pressure. In this report, we examined whether this response was a reflex that was due to venous distension. Blood pressure (Finometer), heart rate, and MSNA (microneurography) were assessed in 14 young healthy subjects. In the saline trial (n = 14), 5% forearm volume normal saline was infused in an arterially occluded arm. To block afferents in the limb, 90 mg of lidocaine were added to the same volume of saline in six subjects during a separate visit. To examine whether interstitial perfusion of normal saline alone induced the responses, the same volume of albumin solution (5% concentration) was infused in 11 subjects in separate studies. Lidocaine abolished the MSNA and blood pressure responses seen with saline infusion. Moreover, compared with the saline infusion, an albumin infusion induced a larger (MSNA: Δ14.3 ± 2.7 vs. Δ8.5 ± 1.3 bursts/min, P blood pressure responses. These data suggest that venous distension activates afferent nerves and evokes a powerful systemic sympathoexcitatory reflex. We posit that the venous distension plays an important role in evoking the autonomic adjustments seen with postural stress in human subjects. PMID:22707559

A predictive model of muscle excitations based on muscle modularity for a large repertoire of human locomotion conditions

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Jose eGonzalez-Vargas

2015-09-01

Full Text Available Humans can efficiently walk across a large variety of terrains and locomotion conditions with little or no mental effort. It has been hypothesized that the nervous system simplifies neuromuscular control by using muscle synergies, thus organizing multi-muscle activity into a small number of coordinative co-activation modules. In the present study we investigated how muscle modularity is structured across a large repertoire of locomotion conditions including five different speeds and five different ground elevations. For this we have used the non-negative matrix factorization technique in order to explain EMG experimental data with a low-dimensional set of four motor components. In this context each motor components is composed of a non-negative factor and the associated muscle weightings. Furthermore, we have investigated if the proposed descriptive analysis of muscle modularity could be translated into a predictive model that could: 1 Estimate how motor components modulate across locomotion speeds and ground elevations. This implies not only estimating the non-negative factors temporal characteristics, but also the associated muscle weighting variations. 2 Estimate how the resulting muscle excitations modulate across novel locomotion conditions and subjects.The results showed three major distinctive features of muscle modularity: 1 the number of motor components was preserved across all locomotion conditions, 2 the non-negative factors were consistent in shape and timing across all locomotion conditions, and 3 the muscle weightings were modulated as distinctive functions of locomotion speed and ground elevation. Results also showed that the developed predictive model was able to reproduce well the muscle modularity of un-modeled data, i.e. novel subjects and conditions. Muscle weightings were reconstructed with a cross-correlation factor greater than 70% and a root mean square error less than 0.10. Furthermore, the generated muscle excitations

Gut vagal afferents differentially modulate innate anxiety and learned fear.

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Klarer, Melanie; Arnold, Myrtha; Günther, Lydia; Winter, Christine; Langhans, Wolfgang; Meyer, Urs

2014-05-21

Vagal afferents are an important neuronal component of the gut-brain axis allowing bottom-up information flow from the viscera to the CNS. In addition to its role in ingestive behavior, vagal afferent signaling has been implicated modulating mood and affect, including distinct forms of anxiety and fear. Here, we used a rat model of subdiaphragmatic vagal deafferentation (SDA), the most complete and selective vagal deafferentation method existing to date, to study the consequences of complete disconnection of abdominal vagal afferents on innate anxiety, conditioned fear, and neurochemical parameters in the limbic system. We found that compared with Sham controls, SDA rats consistently displayed reduced innate anxiety-like behavior in three procedures commonly used in preclinical rodent models of anxiety, namely the elevated plus maze test, open field test, and food neophobia test. On the other hand, SDA rats exhibited increased expression of auditory-cued fear conditioning, which specifically emerged as attenuated extinction of conditioned fear during the tone re-exposure test. The behavioral manifestations in SDA rats were associated with region-dependent changes in noradrenaline and GABA levels in key areas of the limbic system, but not with functional alterations in the hypothalamus-pituitary-adrenal grand stress. Our study demonstrates that innate anxiety and learned fear are both subjected to visceral modulation through abdominal vagal afferents, possibly via changing limbic neurotransmitter systems. These data add further weight to theories emphasizing an important role of afferent visceral signals in the regulation of emotional behavior. Copyright © 2014 the authors 0270-6474/14/347067-10$15.00/0.

Thyroid hormone is required for the pruning of afferent type II spiral ganglion neurons in the mouse cochlea

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Sundaresan, Srividya; Balasubbu, Suganthalakshmi; Mustapha, Mirna

2015-01-01

Afferent connections to the sensory inner and outer hair cells in the cochlea refine and functionally mature during the thyroid hormone (TH)- critical period of inner ear development that occurs perinatally in rodents. In this study, we investigated the effects of hypothyroidism on afferent type II innervation to outer hair cells (OHCs) using the Snell dwarf mouse (Pit1dw). Using a transgenic approach to specifically label type II spiral ganglion neurons, we found that a lack of TH causes persistence of excess type II SGN connections to the OHCs, as well as continued expression of the hair cell functional marker, otoferlin, in the OHCs beyond the maturation period. We also observed a concurrent delay in efferent attachment to the OHCs. Supplementing with TH during the early postnatal period from postnatal day (P) 3 to P4 reversed the defect in type II SGN pruning but did not alter otoferlin expression. Our results show that hypothyroidism causes a defect in the large-scale pruning of afferent type II spiral ganglion neurons in the cochlea, and a delay in efferent attachment and the maturation of otoferlin expression. Our data suggest that the state of maturation of hair cells, as determined by otoferlin expression, may not regulate the pruning of their afferent innervation. PMID:26592716

Vibration sensitivity of human muscle spindles and Golgi tendon organs.

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Fallon, James B; Macefield, Vaughan G

2007-07-01

The responses of the various muscle receptors to vibration are more complicated than a naïve categorization into stretch (muscle spindle primary ending), length (muscle spindle secondary endings), and tension (Golgi tendon organs) receptors. To emphasize the similarity of responses to small length changes, we recorded from 58 individual muscle afferents subserving receptors in the ankle or toe dorsiflexors of awake human subjects (32 primary endings, 20 secondary endings, and six Golgi tendon organs). Transverse sinusoidal vibration was applied to the distal tendon of the receptor-bearing muscle, while subjects either remained completely relaxed or maintained a weak isometric contraction of the appropriate muscle. In relaxed muscle, few units responded in a 1:1 manner to vibration, and there was no evidence of a preferred frequency of activation. In active muscle the response profiles of all three receptor types overlapped, with no significant difference in threshold between receptor types. These results emphasize that when intramuscular tension increases during a voluntary contraction, Golgi tendon organs and muscle spindle secondary endings, not just muscle spindle primary endings, can effectively encode small imposed length changes.

Age-related changes of neurochemically different subpopulations of cardiac spinal afferent neurons in rats.

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Guić, Maja Marinović; Runtić, Branka; Košta, Vana; Aljinović, Jure; Grković, Ivica

2013-08-01

This study investigated the effect of aging on cardiac spinal afferent neurons in the rat. A patch loaded with retrograde tracer Fast Blue (FB) was applied to all chambers of the rat heart. Morphological and neurochemical characteristics of labeled cardiac spinal afferent neurons were assessed in young (2 months) and old (2 years) rats using markers for likely unmyelinated (isolectin B4; IB4) and myelinated (neurofilament 200; N52) neurons. The number of cardiac spinal afferent neurons decreased in senescence to 15% of that found in young rats (1604 vs. 248). The size of neuronal soma as well as proportion of IB4+ neurons increased significantly, whereas the proportion of N52+ neurons decreased significantly in senescence. Unlike somatic spinal afferents, neurochemically different populations of cardiac spinal afferent neurons experience morphological and neurochemical changes related to aging. A major decrease in total number of cardiac spinal afferent neurons occurs in senescence. The proportion of N52+ neurons decreased in senescence, but it seems that nociceptive innervation is preserved due to increased proportion and size of IB4+ unmyelinated neurons. Copyright © 2013 Elsevier Inc. All rights reserved.

Information analysis of posterior canal afferents in the turtle, Trachemys scripta elegans.

Science.gov (United States)

Rowe, Michael H; Neiman, Alexander B

2012-01-24

We have used sinusoidal and band-limited Gaussian noise stimuli along with information measures to characterize the linear and non-linear responses of morpho-physiologically identified posterior canal (PC) afferents and to examine the relationship between mutual information rate and other physiological parameters. Our major findings are: 1) spike generation in most PC afferents is effectively a stochastic renewal process, and spontaneous discharges are fully characterized by their first order statistics; 2) a regular discharge, as measured by normalized coefficient of variation (cv*), reduces intrinsic noise in afferent discharges at frequencies below the mean firing rate; 3) coherence and mutual information rates, calculated from responses to band-limited Gaussian noise, are jointly determined by gain and intrinsic noise (discharge regularity), the two major determinants of signal to noise ratio in the afferent response; 4) measures of optimal non-linear encoding were only moderately greater than optimal linear encoding, indicating that linear stimulus encoding is limited primarily by internal noise rather than by non-linearities; and 5) a leaky integrate and fire model reproduces these results and supports the suggestion that the combination of high discharge regularity and high discharge rates serves to extend the linear encoding range of afferents to higher frequencies. These results provide a framework for future assessments of afferent encoding of signals generated during natural head movements and for comparison with coding strategies used by other sensory systems. This article is part of a Special Issue entitled: Neural Coding. Copyright © 2011 Elsevier B.V. All rights reserved.

Long-term sensitization of mechanosensitive and -insensitive afferents in mice with persistent colorectal hypersensitivity

OpenAIRE

Feng, Bin; La, Jun-ho; Schwartz, Erica S.; Tanaka, Takahiro; McMurray, Timothy P.; Gebhart, G. F.

2012-01-01

Afferent input contributes significantly to the pain and colorectal hypersensitivity that characterize irritable bowel syndrome. In the present study, we investigated the contributions of mechanically sensitive and mechanically insensitive afferents (MIAs; or silent afferents) to colorectal hypersensitivity. The visceromotor response to colorectal distension (CRD; 15–60 mmHg) was recorded in mice before and for weeks after intracolonic treatment with zymosan or saline. After CRD tests, the di...

Capsaicin-sensitive intestinal mucosal afferent mechanism and body fat distribution.

Science.gov (United States)

Leung, Felix W

2008-07-04

This report summarizes clinical and experimental data in support of the hypothesis that capsaicin-sensitive intestinal mucosal afferent mechanism plays a role in regulating body fat distribution. Epidemiological data have revealed that the consumption of foods containing capsaicin is associated with a lower prevalence of obesity. Rural Thai people consume diets containing 0.014% capsaicin. Rodents fed a diet containing 0.014% capsaicin showed no change in caloric intake but a significant 24% and 29% reduction in the visceral (peri-renal) fat weight. Increase in intestinal blood flow facilitates nutrient energy absorption and decrease in adipose tissue blood flow facilitates storage of nutrient energy in adipose tissue. Stimulation of intestinal mucosal afferent nerves increases intestinal blood flow, but decreases visceral (mesenteric) adipost tissue blood flow. In in vitro cell studies capsaicin has a direct effect on adipocytes. Intravenous capsaicin produces measurable plasma level and subcutaneous capsaicin retards accumulation of adipose tissue. The data on a direct effect of oral capsaicin on adipose tissue at remote sites, however, are conflicting. Capsaicin absorbed from the gut lumen is almost completely metabolized before reaching the general circulation. Oral capsaicin significantly increases transient receptor potential vanilloid type-1 (TRPV1) channel expression as well as TRPV1 messenger ribonucleic acid (mRNA) in visceral adipose tissue. In TRPV1 knockout mice on a high fat diet the body weight was not significantly different in the absence or presence of oral capsaicin. In rodent experiments, daily intragastric administration of capsaicin for two weeks led to defunctionalization of intestinal mucosal afferent nerves, manifested by loss of acute mucosal capsaicin-induced effects; but not the corneal afferent nerves, with preservation of the paw wiping reflex of the eye exposed briefly to dilute capsaicin. The latter indicated the absence of an oral

Functional role of peripheral opioid receptors in the regulation of cardiac spinal afferent nerve activity during myocardial ischemia

Science.gov (United States)

Longhurst, John C.

2013-01-01

Thinly myelinated Aδ-fiber and unmyelinated C-fiber cardiac sympathetic (spinal) sensory nerve fibers are activated during myocardial ischemia to transmit the sensation of angina pectoris. Although recent observations showed that myocardial ischemia increases the concentrations of opioid peptides and that the stimulation of peripheral opioid receptors inhibits chemically induced visceral and somatic nociception, the role of opioids in cardiac spinal afferent signaling during myocardial ischemia has not been studied. The present study tested the hypothesis that peripheral opioid receptors modulate cardiac spinal afferent nerve activity during myocardial ischemia by suppressing the responses of cardiac afferent nerve to ischemic mediators like bradykinin and extracellular ATP. The nerve activity of single unit cardiac afferents was recorded from the left sympathetic chain (T2–T5) in anesthetized cats. Forty-three ischemically sensitive afferent nerves (conduction velocity: 0.32–3.90 m/s) with receptive fields in the left and right ventricles were identified. The responses of these afferent nerves to repeat ischemia or ischemic mediators were further studied in the following protocols. First, epicardial administration of naloxone (8 μmol), a nonselective opioid receptor antagonist, enhanced the responses of eight cardiac afferent nerves to recurrent myocardial ischemia by 62%, whereas epicardial application of vehicle (PBS) did not alter the responses of seven other cardiac afferent nerves to ischemia. Second, naloxone applied to the epicardial surface facilitated the responses of seven cardiac afferent nerves to epicardial ATP by 76%. Third, administration of naloxone enhanced the responses of seven other afferent nerves to bradykinin by 85%. In contrast, in the absence of naloxone, cardiac afferent nerves consistently responded to repeated application of ATP (n = 7) or bradykinin (n = 7). These data suggest that peripheral opioid peptides suppress the

Afferent loop syndrome - a case report

International Nuclear Information System (INIS)

Borges, Ana Karina Nascimento; Pinheiro, Marco Antonio Lopes; Galvao, Cristine Norwig

2000-01-01

The afferent loop syndrome occurs in patients with previous gastric surgery for tumor, when there is anastomotic edema, use of inappropriate reconstruction technique for gastro jejunostomy or recurrent gastric cancer. Complaints such jaundice, intermittent abdominal distension associated with pain, and vomiting should be investigated in order to rule out this syndrome. (author)

Acute cholangitis due to afferent loop syndrome after a Whipple procedure: a case report.

Science.gov (United States)

Spiliotis, John; Karnabatidis, Demetrios; Vaxevanidou, Archodoula; Datsis, Anastasios C; Rogdakis, Athanasios; Zacharis, Georgios; Siamblis, Demetrios

2009-08-25

Patients with resection of stomach and especially with Billroth II reconstruction (gastro jejunal anastomosis), are more likely to develop afferent loop syndrome which is a rare complication. When the afferent part is obstructed, biliary and pancreatic secretions accumulate and cause the distention of this part. In the case of a complete obstruction (rare), there is a high risk developing necrosis and perforation. This complication has been reported once in the literature. A 54-year-old Greek male had undergone a pancreato-duodenectomy (Whipple procedure) one year earlier due to a pancreatic adenocarcinoma. Approximately 10 months after the initial operation, the patient started having episodes of cholangitis (fever, jaundice) and abdominal pain. This condition progressively worsened and the suspicion of local recurrence or stenosis of the biliary-jejunal anastomosis was discussed. A few days before his admission the patient developed signs of septic cholangitis. Our case demonstrates a rare complication with serious clinical manifestation of the afferent loop syndrome. This advanced form of afferent loop syndrome led to the development of huge enterobiliary reflux, which had a serious clinical manifestation as cholangitis and systemic sepsis, due to bacterial overgrowth, which usually present in the afferent loop. The diagnosis is difficult and the interventional radiology gives all the details to support the therapeutic decision making. A variety of factors can contribute to its development including adhesions, kinking and angulation of the loop, stenosis of gastro-jejunal anastomosis and internal herniation. In order to decompress the afferent loop dilatation due to adhesions, a lateral-lateral jejunal anastomosis was performed between the afferent loop and a small bowel loop.

Afferent control of central pattern generators: experimental analysis of locomotion in the decerebrate cat.

Science.gov (United States)

Baev, K V; Esipenko, V B; Shimansky YuP

1991-01-01

Changes in the motor activity of the spinal locomotor generator evoked by tonic and phasic peripheral afferent signals during fictitious locomotion of both slow and fast rhythms were analysed in the cat. The tonic afferent inflow was conditioned by the position of the hindlimb. The phasic afferent signals were imitated by electrical stimulation of hindlimb nerves. The correlation between the kinematics of hindlimb locomotor movement and sensory inflow was investigated during actual locomotion. Reliable correlations between motor activity parameters during fictitious locomotion were revealed in cases of both slow and fast "locomotor" rhythms. The main difference between these cases was that correlations "duration-intensity" were positive in the first and negative in the second case. The functional role of "locomotor" pattern dependence on tonic sensory inflow consisted of providing stability for planting the hindlimb on the ground. For any investigated afferent input the phase moments in the "locomotor" cycle were found, in which an afferent signal caused no rearrangement in locomotor generator activity. These moments corresponded to the transitions between "flexion" and "extension" phases and to the bursts of integral afferent activity observed during real locomotion. The data obtained are compared with the results previously described for the scratching generator. The character of changes in "locomotor" activity in response to tonic and phasic sensory signals was similar to that of such changes in "scratching" rhythm in the case of fast "locomotion". Intensification of the "flexion" phase caused by phasic high-intensity stimulation of cutaneous afferents during low "locomotor" rhythm was changed to inhibition (such as observed during "scratching") when this rhythm was fast. It is concluded that the main regularities of peripheral afferent control for both the locomotor and scratching generators are the same. Moreover, these central pattern generators are just

Comparative Analyses between Skeletal Muscle miRNAomes from Large White and Min Pigs Revealed MicroRNAs Associated with Postnatal Muscle Hypertrophy.

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Sheng, Xihui; Wang, Ligang; Ni, Hemin; Wang, Lixian; Qi, Xiaolong; Xing, Shuhan; Guo, Yong

2016-01-01

The molecular mechanism regulated by microRNAs (miRNAs) that underlies postnatal hypertrophy of skeletal muscle is complex and remains unclear. Here, the miRNAomes of longissimus dorsi muscle collected at five postnatal stages (60, 120, 150, 180, and 210 days after birth) from Large White (commercial breed) and Min pigs (indigenous breed of China) were analyzed by Illumina sequencing. We identified 734 miRNAs comprising 308 annotated miRNAs and 426 novel miRNAs, of which 307 could be considered pig-specific. Comparative analysis between two breeds suggested that 60 and 120 days after birth were important stages for skeletal muscle hypertrophy and intramuscular fat accumulation. A total of 263 miRNAs were significantly differentially expressed between two breeds at one or more developmental stages. In addition, the differentially expressed miRNAs between every two adjacent developmental stages in each breed were determined. Notably, ssc-miR-204 was significantly more highly expressed in Min pig skeletal muscle at all postnatal stages compared with its expression in Large White pig skeletal muscle. Based on gene ontology and KEGG pathway analyses of its predicted target genes, we concluded that ssc-miR-204 may exert an impact on postnatal hypertrophy of skeletal muscle by regulating myoblast proliferation. The results of this study will help in elucidating the mechanism underlying postnatal hypertrophy of skeletal muscle modulated by miRNAs, which could provide valuable information for improvement of pork quality and human myopathy.

Neuronal thresholds and choice-related activity of otolith afferent fibers during heading perception.

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Yu, Xiong-jie; Dickman, J David; DeAngelis, Gregory C; Angelaki, Dora E

2015-05-19

How activity of sensory neurons leads to perceptual decisions remains a challenge to understand. Correlations between choices and single neuron firing rates have been found early in vestibular processing, in the brainstem and cerebellum. To investigate the origins of choice-related activity, we have recorded from otolith afferent fibers while animals performed a fine heading discrimination task. We find that afferent fibers have similar discrimination thresholds as central cells, and the most sensitive fibers have thresholds that are only twofold or threefold greater than perceptual thresholds. Unlike brainstem and cerebellar nuclei neurons, spike counts from afferent fibers do not exhibit trial-by-trial correlations with perceptual decisions. This finding may reflect the fact that otolith afferent responses are poorly suited for driving heading perception because they fail to discriminate self-motion from changes in orientation relative to gravity. Alternatively, if choice probabilities reflect top-down inference signals, they are not relayed to the vestibular periphery.

Somatosympathetic vasoconstrictor reflexes in human spinal cord injury: responses to innocuous and noxious sensory stimulation below lesion

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Vaughan G Macefield

2012-06-01

Full Text Available It is known that the sudden increases in blood pressure associated with autonomic dysreflexia in people with spinal cord injury (SCI is due to a spinally-mediated reflex activation of sympathetic vasoconstrictor neurones supplying skeletal muscle and the gut. Apart from visceral inputs, such as those originating from a distended bladder, there is a prevailing opinion that autonomic dysreflexia can be triggered by noxious stimulation below the lesion. However, do noxious inputs really cause an increase in blood pressure in SCI? Using microelectrodes inserted into a peripheral nerve to record sympathetic nerve activity we had previously shown that selective stimulation of small-diameter afferents in muscle or skin, induced by bolus injection of hypertonic saline into the tibialis anterior muscle or the overlying skin, evokes a sustained increase in muscle sympathetic nerve activity and blood pressure and a transient increase in skin sympathetic nerve activity and decrease in skin blood flow. We postulated that these sympathetic responses would be exaggerated in SCI, with a purely noxious stimulus causing long-lasting increases in blood pressure and long-lasting decreases in skin blood flow. Surprisingly, though, we found that intramuscular or subcutaneous injection of hypertonic saline into the leg caused negligible changes in these parameters. Conversely, weak electrical stimulation over the abdominal wall, which in able-bodied subjects is not painful and activates large-diameter cutaneous afferents, caused a marked increase in blood pressure in SCI but not in able-bodied subjects. This suggests that it is activation of large-diameter somatic afferents, not small-diameter afferents, that triggers increases in sympathetic outflow in SCI. Whether the responses to activation of large-diameter afferents reflect plastic changes in the spinal cord in SCI is unknown.

Contributions of central command and muscle feedback to sympathetic nerve activity in contracting human skeletal muscle

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Daniel eBoulton

2016-05-01

Full Text Available During voluntary contractions, muscle sympathetic nerve activity (MSNA to contracting muscles increases in proportion to force but the underlying mechanisms are not clear. To shed light on these mechanisms, particularly the influences of central command and muscle afferent feedback, the present study tested the hypothesis that MSNA is greater during voluntary compared with electrically-evoked contractions. Seven male subjects performed a series of 1-minute isometric dorsiflexion contractions (left leg separated by 2-minute rest periods, alternating between voluntary and electrically-evoked contractions at similar forces (5-10 % of maximum. MSNA was recorded continuously (microneurography from the left peroneal nerve and quantified from cardiac-synchronised, negative-going spikes in the neurogram. Compared with pre-contraction values, MSNA increased by 51 ± 34 % (P 0.05. MSNA analysed at 15-s intervals revealed that this effect of voluntary contraction appeared 15-30 s after contraction onset (P < 0.01, remained elevated until the end of contraction, and disappeared within 15 s after contraction. These findings suggest that central command, and not feedback from contracting muscle, is the primary mechanism responsible for the increase in MSNA to contracting muscle. The time-course of MSNA suggests that there is a longer delay in the onset of this effect compared with its cessation after contraction.

Inhibition of micturition reflex by activation of somatic afferents in posterior femoral cutaneous nerve.

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Tai, Changfeng; Shen, Bing; Mally, Abhijith D; Zhang, Fan; Zhao, Shouguo; Wang, Jicheng; Roppolo, James R; de Groat, William C

2012-10-01

This study determined if activation of somatic afferents in posterior femoral cutaneous nerve (PFCN) could modulate the micturition reflex recorded under isovolumetric conditions in α-chloralose anaesthetized cats. PFCN stimulation inhibited reflex bladder activity and significantly (P acid (AA). The optimal frequency for PFCN stimulation-induced bladder inhibition was between 3 and 10 Hz, and a minimal stimulation intensity of half of the threshold for inducing anal twitching was required. Bilateral pudendal nerve transection eliminated PFCN stimulation-induced anal twitching but did not change the stimulation-induced bladder inhibition, excluding the involvement of pudendal afferent or efferent axons in PFCN afferent inhibition.Mechanical or electrical stimulation on the skin surface in the PFCN dermatome also inhibited bladder activity. Prolonged (2 × 30 min) PFCN stimulation induced a post-stimulation inhibition that persists for at least 2 h. This study revealed a new cutaneous-bladder reflex activated by PFCN afferents. Although the mechanisms and physiological functions of this cutaneous-bladder reflex need to be further studied, our data raise the possibility that stimulation of PFCN afferents might be useful clinically for the treatment of overactive bladder symptoms.

Withdrawal and restoration of central vagal afferents within the dorsal vagal complex following subdiaphragmatic vagotomy.

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Peters, James H; Gallaher, Zachary R; Ryu, Vitaly; Czaja, Krzysztof

2013-10-15

Vagotomy, a severing of the peripheral axons of the vagus nerve, has been extensively utilized to determine the role of vagal afferents in viscerosensory signaling. Vagotomy is also an unavoidable component of some bariatric surgeries. Although it is known that peripheral axons of the vagus nerve degenerate and then regenerate to a limited extent following vagotomy, very little is known about the response of central vagal afferents in the dorsal vagal complex to this type of damage. We tested the hypothesis that vagotomy results in the transient withdrawal of central vagal afferent terminals from their primary central target, the nucleus of the solitary tract (NTS). Sprague-Dawley rats underwent bilateral subdiaphragmatic vagotomy and were sacrificed 10, 30, or 60 days later. Plastic changes in vagal afferent fibers and synapses were investigated at the morphological and functional levels by using a combination of an anterograde tracer, synapse-specific markers, and patch-clamp electrophysiology in horizontal brain sections. Morphological data revealed that numbers of vagal afferent fibers and synapses in the NTS were significantly reduced 10 days following vagotomy and were restored to control levels by 30 days and 60 days, respectively. Electrophysiology revealed transient decreases in spontaneous glutamate release, glutamate release probability, and the number of primary afferent inputs. Our results demonstrate that subdiaphragmatic vagotomy triggers transient withdrawal and remodeling of central vagal afferent terminals in the NTS. The observed vagotomy-induced plasticity within this key feeding center of the brain may be partially responsible for the response of bariatric patients following gastric bypass surgery. Copyright © 2013 Wiley Periodicals, Inc.

Error correction in bimanual coordination benefits from bilateral muscle activity: evidence from kinesthetic tracking

NARCIS (Netherlands)

Ridderikhoff, A.; Peper, C.E.; Beek, P.J.

2007-01-01

Although previous studies indicated that the stability properties of interlimb coordination largely result from the integrated timing of efferent signals to both limbs, they also depend on afference-based interactions. In the present study, we examined contributions of afference-based error

Cortical Presynaptic Control of Dorsal Horn C–Afferents in the Rat

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Martínez-Lorenzana, Guadalupe; Condés-Lara, Miguel; Rojas-Piloni, Gerardo

2013-01-01

Lamina 5 sensorimotor cortex pyramidal neurons project to the spinal cord, participating in the modulation of several modalities of information transmission. A well-studied mechanism by which the corticospinal projection modulates sensory information is primary afferent depolarization, which has been characterized in fast muscular and cutaneous, but not in slow-conducting nociceptive skin afferents. Here we investigated whether the inhibition of nociceptive sensory information, produced by activation of the sensorimotor cortex, involves a direct presynaptic modulation of C primary afferents. In anaesthetized male Wistar rats, we analyzed the effects of sensorimotor cortex activation on post tetanic potentiation (PTP) and the paired pulse ratio (PPR) of dorsal horn field potentials evoked by C–fiber stimulation in the sural (SU) and sciatic (SC) nerves. We also explored the time course of the excitability changes in nociceptive afferents produced by cortical stimulation. We observed that the development of PTP was completely blocked when C-fiber tetanic stimulation was paired with cortex stimulation. In addition, sensorimotor cortex activation by topical administration of bicuculline (BIC) produced a reduction in the amplitude of C–fiber responses, as well as an increase in the PPR. Furthermore, increases in the intraspinal excitability of slow-conducting fiber terminals, produced by sensorimotor cortex stimulation, were indicative of primary afferent depolarization. Topical administration of BIC in the spinal cord blocked the inhibition of C–fiber neuronal responses produced by cortical stimulation. Dorsal horn neurons responding to sensorimotor cortex stimulation also exhibited a peripheral receptive field and responded to stimulation of fast cutaneous myelinated fibers. Our results suggest that corticospinal inhibition of nociceptive responses is due in part to a modulation of the excitability of primary C–fibers by means of GABAergic inhibitory

Facilitation of the main generator source of earthworm muscle contraction by a peripheral neuron

Directory of Open Access Journals (Sweden)

Chang Y.C.

1998-01-01

Full Text Available A constant facilitation of responses evoked in the earthworm muscle contraction generator neurons by responses evoked in the neurons of its peripheral nervous system was demonstrated. It is based on the proposal that these two responses are bifurcations of an afferent response evoked by the same peripheral mechanical stimulus but converging again on this central neuron. A single-peaked generator response without facilitation was demonstrated by sectioning the afferent route of the peripheral facilitatory modulatory response, or conditioning response (CR. The multipeaked response could be restored by restimulating the sectioned modulatory neuron with an intracellular substitutive conditioning stimulus (SCS. These multi-peaked responses were proposed to be the result of reverberating the original single peaked unconditioned response (UR through a parallel (P neuronal circuit which receives the facilitation of the peripheral modulatory neuron. This peripheral modulatory neuron was named "Peri-Kästchen" (PK neuron because it has about 20 peripheral processes distributed on the surface of a Kästchen of longitudinal muscle cells on the body wall of this preparation as revealed by the Lucifer Yellow-CH-filling method.

Comparison of the large muscle group widths of the pelvic limb in seven breeds of dogs.

Science.gov (United States)

Sabanci, Seyyid Said; Ocal, Mehmet Kamil

2018-05-14

Orthopaedic diseases are common in the pelvic limbs of dogs, and reference values for large muscle groups of the pelvic limb may aid in diagnosis such diseases. As such, the objective of this study was to compare the large muscle groups of the pelvic limb in seven breeds of dogs. A total of 126 dogs from different breeds were included, and the widths of the quadriceps, hamstring and gastrocnemius muscles were measured from images of the lateral radiographies. The width of the quadriceps was not different between the breeds, but the widths of the hamstring and gastrocnemius muscles were significantly different between the breeds. The widest hamstring and gastrocnemius muscles were seen in the Rottweilers and the Boxers, respectively. The narrowest hamstring and gastrocnemius muscles were seen in the Belgian Malinois and the Golden retrievers, respectively. All ratios between the measured muscles differed significantly between the breeds. Doberman pinschers and Belgian Malinois had the highest ratio of gastrocnemius width:hamstring width. Doberman pinschers had also the highest ratio of quadriceps width:hamstring width. German shepherds had the highest ratio of gastrocnemius width:quadriceps width. The lowest ratios of quadriceps width:hamstring width were determined in the German shepherds. The ratios of the muscle widths may be used as reference values to assess muscular atrophy or hypertrophy in cases of bilateral or unilateral orthopaedic diseases of the pelvic limbs. Further studies are required to determine the widths and ratios of the large muscle groups of the pelvic limbs in other dog breeds. © 2018 Blackwell Verlag GmbH.

TRPV1 Channels and Gastric Vagal Afferent Signalling in Lean and High Fat Diet Induced Obese Mice.

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Stephen J Kentish

Full Text Available Within the gastrointestinal tract vagal afferents play a role in control of food intake and satiety signalling. Activation of mechanosensitive gastric vagal afferents induces satiety. However, gastric vagal afferent responses to mechanical stretch are reduced in high fat diet mice. Transient receptor potential vanilloid 1 channels (TRPV1 are expressed in vagal afferents and knockout of TRPV1 reduces gastro-oesophageal vagal afferent responses to stretch. We aimed to determine the role of TRPV1 on gastric vagal afferent mechanosensitivity and food intake in lean and HFD-induced obese mice.TRPV1+/+ and -/- mice were fed either a standard laboratory diet or high fat diet for 20wks. Gastric emptying of a solid meal and gastric vagal afferent mechanosensitivity was determined.Gastric emptying was delayed in high fat diet mice but there was no difference between TRPV1+/+ and -/- mice on either diet. TRPV1 mRNA expression in whole nodose ganglia of TRPV1+/+ mice was similar in both dietary groups. The TRPV1 agonist N-oleoyldopamine potentiated the response of tension receptors in standard laboratory diet but not high fat diet mice. Food intake was greater in the standard laboratory diet TRPV1-/- compared to TRPV1+/+ mice. This was associated with reduced response of tension receptors to stretch in standard laboratory diet TRPV1-/- mice. Tension receptor responses to stretch were decreased in high fat diet compared to standard laboratory diet TRPV1+/+ mice; an effect not observed in TRPV1-/- mice. Disruption of TRPV1 had no effect on the response of mucosal receptors to mucosal stroking in mice on either diet.TRPV1 channels selectively modulate gastric vagal afferent tension receptor mechanosensitivity and may mediate the reduction in gastric vagal afferent mechanosensitivity in high fat diet-induced obesity.

Monosynaptic connections between primary afferents and giant neurons in the turtle spinal dorsal horn

DEFF Research Database (Denmark)

Fernández, A; Radmilovich, M; Russo, R E

1996-01-01

This paper reports the occurrence of monosynaptic connections between dorsal root afferents and a distinct cell type-the giant neuron-deep in the dorsal horn of the turtle spinal cord. Light microscope studies combining Nissl stain and transganglionic HRP-labeling of the primary afferents have...

Compensatory hypertrophy of the teres minor muscle after large rotator cuff tear model in adult male rat.

Science.gov (United States)

Ichinose, Tsuyoshi; Yamamoto, Atsushi; Kobayashi, Tsutomu; Shitara, Hitoshi; Shimoyama, Daisuke; Iizuka, Haku; Koibuchi, Noriyuki; Takagishi, Kenji

2016-02-01

Rotator cuff tear (RCT) is a common musculoskeletal disorder in the elderly. The large RCT is often irreparable due to the retraction and degeneration of the rotator cuff muscle. The integrity of the teres minor (TM) muscle is thought to affect postoperative functional recovery in some surgical treatments. Hypertrophy of the TM is found in some patients with large RCTs; however, the process underlying this hypertrophy is still unclear. The objective of this study was to determine if compensatory hypertrophy of the TM muscle occurs in a large RCT rat model. Twelve Wistar rats underwent transection of the suprascapular nerve and the supraspinatus and infraspinatus tendons in the left shoulder. The rats were euthanized 4 weeks after the surgery, and the cuff muscles were collected and weighed. The cross-sectional area and the involvement of Akt/mammalian target of rapamycin (mTOR) signaling were examined in the remaining TM muscle. The weight and cross-sectional area of the TM muscle was higher in the operated-on side than in the control side. The phosphorylated Akt/Akt protein ratio was not significantly different between these sides. The phosphorylated-mTOR/mTOR protein ratio was significantly higher on the operated-on side. Transection of the suprascapular nerve and the supraspinatus and infraspinatus tendons activates mTOR signaling in the TM muscle, which results in muscle hypertrophy. The Akt-signaling pathway may not be involved in this process. Nevertheless, activation of mTOR signaling in the TM muscle after RCT may be an effective therapeutic target of a large RCT. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Effects of microgravity on muscle and cerebral cortex: a suggested interaction

Science.gov (United States)

D'Amelio, F.; Fox, R. A.; Wu, L. C.; Daunton, N. G.; Corcoran, M. L.

The ``slow'' antigravity muscle adductor longus was studied in rats after 14 days of spaceflight (SF). The techniques employed included standard methods for light microscopy, neural cell adhesion molecule (N-CAM) immunocytochemistry and electron microscopy. Light and electron microscopy revealed myofiber atrophy, segmental necrosis and regenerative myofibers. Regenerative myofibers were N-CAM immunoreactive (N-CAM-IR). The neuromuscular junctions showed axon terminals with a decrease or absence of synaptic vesicles, degenerative changes, vacant axonal spaces and changes suggestive of axonal sprouting. No alterations of muscle spindles was seen either by light or electron microscopy. These observations suggest that muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight. In a separate study, GABA immunoreactivity (GABA-IR) was evaluated at the level of the hindlimb representation of the rat somatosensory cortex after 14 days of hindlimb unloading by tail suspension (``simulated'' microgravity). A reduction in number of GABA-immunoreactive cells with respect to the control animals was observed in layer Va and Vb. GABA-IR terminals were also reduced in the same layers, particularly those terminals surrounding the soma and apical dendrites of pyramidal cells in layer Vb. On the basis of previous morphological and behavioral studies of the neuromuscular system after spaceflight and hindlimb suspension it is suggested that after limb unloading there are alterations of afferent signaling and feedback information from intramuscular receptors to the cerebral cortex due to modifications in the reflex organization of hindlimb muscle groups. We propose that the changes observed in GABA immunoreactivity of cells and terminals is an expression of changes in their modulatory activity to compensate for the alterations in the afferent information.

Ultrastructure of the central subnucleus of the nucleus tractus solitarii and the esophageal afferent terminals in the rat.

Science.gov (United States)

Hayakawa, Tetsu; Takanaga, Akinori; Tanaka, Koichi; Maeda, Seishi; Seki, Makoto

2003-03-01

The central subnucleus of the nucleus tractus solitarii (ceNTS) receives afferent projections from the esophageal wall and projects to the nucleus ambiguus, thus serving as a relay nucleus for peristalsis of the esophagus. Here we examine the synaptic organization of the ceNTS, and its esophageal afferents by using transganglionic anterograde transport of cholera toxin-conjugated horseradish peroxidase (CT-HRP). When CT-HRP was injected into the subdiaphragmatic esophagus, many anterogradely labeled terminals were found only in the ceNTS. The ceNTS was composed of round or oval-shaped, small neurons (14.7x8.7 micro m) containing sparse organelles and an irregularly shaped nucleus. The average number of axosomatic terminals was only 1.3 per section cut through the nucleolus. Most of them (92%) contained round vesicles and formed asymmetric synaptic contacts (Gray's type I), and a few (8%) contained pleomorphic vesicles and formed symmetric synaptic contacts (Gray's type II). All anterogradely labeled terminals contacted dendrites but not the neuronal somata. The labeled terminals were large (2.55+/-0.07 micro m) and exclusively Gray's type I. More than half of them (60%) contacted small dendrites (less than 1 micro m in diameter), and contained dense-cored vesicles. More than 40% of the labeled terminals contacted two to four dendrites, thus forming a synaptic glomerulus. Sometimes a labeled terminal that contacted an unlabeled terminal by an adherent junction was found within the glomerulus. The large terminals and these complex synaptic relations appeared to characterize the esophageal afferent projections in the ceNTS.

On the nature of the afferent fibers of oculomotor nerve.

Science.gov (United States)

Manni, E; Draicchio, F; Pettorossi, V E; Carobi, C; Grassi, S; Bortolami, R; Lucchi, M L

1989-03-01

The oculogyric nerves contain afferent fibers originating from the ophthalmic territory, the somata of which are located in the ipsilateral semilunar ganglion. These primary sensory neurons project to the Subnucleus Gelatinosus of the Nucleus Caudalis Trigemini, where they make presynaptic contact with the central endings of the primary trigeminal afferents running in the fifth cranial nerve. After complete section of the trigeminal root, the antidromic volleys elicited in the trunk of the third cranial nerve by stimulating SG of NCT consisted of two waves belonging to the A delta and C groups. The area of both components of the antidromic volleys decreased both after bradykinin and hystamine injection into the corresponding cutaneous region and after thermic stimulation of the ipsilateral trigeminal ophthalmic territory. The reduction of such potentials can be explained in terms of collision between the antidromic volleys and those elicited orthodromically by chemical and thermic stimulation. Also, capsaicin applied on the nerve induced an immediate increase, followed by a long lasting decrease, of orthodromic evoked response area. These findings bring further support to the nociceptive nature of the afferent fibers running into the oculomotor nerve.

Heat pulse excitability of vestibular hair cells and afferent neurons.

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Rabbitt, Richard D; Brichta, Alan M; Tabatabaee, Hessam; Boutros, Peter J; Ahn, JoongHo; Della Santina, Charles C; Poppi, Lauren A; Lim, Rebecca

2016-08-01

In the present study we combined electrophysiology with optical heat pulse stimuli to examine thermodynamics of membrane electrical excitability in mammalian vestibular hair cells and afferent neurons. We recorded whole cell currents in mammalian type II vestibular hair cells using an excised preparation (mouse) and action potentials (APs) in afferent neurons in vivo (chinchilla) in response to optical heat pulses applied to the crista (ΔT ≈ 0.25°C per pulse). Afferent spike trains evoked by heat pulse stimuli were diverse and included asynchronous inhibition, asynchronous excitation, and/or phase-locked APs synchronized to each infrared heat pulse. Thermal responses of membrane currents responsible for APs in ganglion neurons were strictly excitatory, with Q10 ≈ 2. In contrast, hair cells responded with a mix of excitatory and inhibitory currents. Excitatory hair cell membrane currents included a thermoelectric capacitive current proportional to the rate of temperature rise (dT/dt) and an inward conduction current driven by ΔT An iberiotoxin-sensitive inhibitory conduction current was also evoked by ΔT, rising in protein biophysics and manipulate cellular excitability. Copyright © 2016 the American Physiological Society.

The visceromotor and somatic afferent nerves of the penis.

Science.gov (United States)

Diallo, Djibril; Zaitouna, Mazen; Alsaid, Bayan; Quillard, Jeanine; Ba, Nathalie; Allodji, Rodrigue Sètchéou; Benoit, Gérard; Bedretdinova, Dina; Bessede, Thomas

2015-05-01

Innervation of the penis supports erectile and sensory functions. This article aims to study the efferent autonomic (visceromotor) and afferent somatic (sensory) nervous systems of the penis and to investigate how these systems relate to vascular pathways. Penises obtained from five adult cadavers were studied via computer-assisted anatomic dissection (CAAD). The number of autonomic and somatic nerve fibers was compared using the Kruskal-Wallis test. Proximally, penile innervation was mainly somatic in the extra-albugineal sector and mainly autonomic in the intracavernosal sector. Distally, both sectors were almost exclusively supplied by somatic nerve fibers, except the intrapenile vascular anastomoses that accompanied both somatic and autonomic (nitrergic) fibers. From this point, the neural immunolabeling within perivascular nerve fibers was mixed (somatic labeling and autonomic labeling). Accessory afferent, extra-albugineal pathways supplied the outer layers of the penis. There is a major change in the functional type of innervation between the proximal and distal parts of the intracavernosal sector of the penis. In addition to the pelvis and the hilum of the penis, the intrapenile neurovascular routes are the third level where the efferent autonomic (visceromotor) and the afferent somatic (sensory) penile nerve fibers are close. Intrapenile neurovascular pathways define a proximal penile segment, which guarantees erectile rigidity, and a sensory distal segment. © 2015 International Society for Sexual Medicine.

Cellular mechanisms for presynaptic inhibition of sensory afferents

DEFF Research Database (Denmark)

Perrier, Jean-Francois Marie; delgado-lezama, rodolfo; Christensen, Rasmus Kordt

It is well established that presynaptic inhibition of primary afferents involves the activation of GABAA receptors located on presynaptic terminals. However, the source of GABA remains unknown. In an integrated preparation of the spinal cord of the adult turtle, we evoked dorsal root potentials...

Peptide and lipid modulation of glutamatergic afferent synaptic transmission in the solitary tract nucleus

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Michael C. Andresen

2013-01-01

Full Text Available The brainstem nucleus of the solitary tract (NTS holds the first central neurons in major homeostatic reflex pathways. These homeostatic reflexes regulate and coordinate multiple organ systems from gastrointestinal to cardiopulmonary functions. The core of many of these pathways arise from cranial visceral afferent neurons that enter the brain as the solitary tract (ST with more than two-thirds arising from the gastrointestinal system. About one quarter of ST afferents have myelinated axons but the majority are classed as unmyelinated C-fibers. All ST afferents release the fast neurotransmitter glutamate with remarkably similar, high-probability release characteristics. Second order NTS neurons receive surprisingly limited primary afferent information with one or two individual inputs converging on single second order NTS neurons. A- and C-fiber afferents never mix at NTS second order neurons. Many transmitters modify the basic glutamatergic excitatory postsynaptic current (EPSC often by reducing glutamate release or interrupting terminal depolarization. Thus, a distinguishing feature of ST transmission is presynaptic expression of G-protein coupled receptors for peptides common to peripheral or forebrain (e.g. hypothalamus neuron sources. Presynaptic receptors for angiotensin (AT1, vasopressin (V1a, oxytocin (OT, opioid (MOR, ghrelin (GHSR1 and cholecystokinin (CCK differentially control glutamate release on particular subsets of neurons with most other ST afferents unaffected. Lastly, lipid-like signals are transduced by two key ST presynaptic receptors, the transient receptor potential vanilloid type 1 (TRPV1 and the cannabinoid receptor (CB1 that oppositely control glutamate release. Increasing evidence suggests that peripheral nervous signaling mechanisms are repurposed at central terminals to control excitation and are major sites of signal integration of peripheral and central inputs particularly from the hypothalamus.

Afferent projections to the deep mesencephalic nucleus in the rat

International Nuclear Information System (INIS)

Veazey, R.B.; Severin, C.M.

1982-01-01

Afferent projections to the deep mesencephalic nucleus (DMN) of the rat were demonstrated with axonal transport techniques. Potential sources for projections to the DMN were first identified by injecting the nucleus with HRP and examining the cervical spinal cord, brain stem, and cortex for retrogradely labeled neurons. Areas consistently labeled were then injected with a tritiated radioisotope, the tissue processed for autoradiography, and the DMN examined for anterograde labeling. Afferent projections to the medial and/or lateral parts of the DMN were found to originate from a number of spinal, bulbar, and cortical centers. Rostral brain centers projecting to both medial and lateral parts of the DMN include the ipsilateral motor and somatosensory cortex, the entopeduncular nucleus, and zona incerta. at the level of the midbrain, the ipsilateral substantia nigra and contralateral DMN likewise project to the DMN. Furthermore, the ipsilateral superior colliculus projects to the DMN, involving mainly the lateral part of the nucleus. Afferents from caudal centers include bilateral projections from the sensory nucleus of the trigeminal complex and the nucleus medulla oblongata centralis, as well as from the contralateral dentate nucleus. The projections from the trigeminal complex and nucleus medullae oblongatae centralis terminate in the intermediate and medial parts of the DMN, whereas projections from the contralateral dentate nucleus terminate mainly in its lateral part. In general, the afferent connections of the DMN arise from diverse areas of the brain. Although most of these projections distribute throughout the entire extent of the DMN, some of them project mainly to either medial or lateral parts of the nucleus, thus suggesting that the organization of the DMN is comparable, at least in part, to that of the reticular formation of the pons and medulla, a region in which hodological differences between medial and lateral subdivisions are known to exist

Heat pulse excitability of vestibular hair cells and afferent neurons

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Brichta, Alan M.; Tabatabaee, Hessam; Boutros, Peter J.; Ahn, JoongHo; Della Santina, Charles C.; Poppi, Lauren A.; Lim, Rebecca

2016-01-01

In the present study we combined electrophysiology with optical heat pulse stimuli to examine thermodynamics of membrane electrical excitability in mammalian vestibular hair cells and afferent neurons. We recorded whole cell currents in mammalian type II vestibular hair cells using an excised preparation (mouse) and action potentials (APs) in afferent neurons in vivo (chinchilla) in response to optical heat pulses applied to the crista (ΔT ≈ 0.25°C per pulse). Afferent spike trains evoked by heat pulse stimuli were diverse and included asynchronous inhibition, asynchronous excitation, and/or phase-locked APs synchronized to each infrared heat pulse. Thermal responses of membrane currents responsible for APs in ganglion neurons were strictly excitatory, with Q10 ≈ 2. In contrast, hair cells responded with a mix of excitatory and inhibitory currents. Excitatory hair cell membrane currents included a thermoelectric capacitive current proportional to the rate of temperature rise (dT/dt) and an inward conduction current driven by ΔT. An iberiotoxin-sensitive inhibitory conduction current was also evoked by ΔT, rising in heat pulse excitability in vestibular sensory organs and provide quantitative methods for rational application of optical heat pulses to examine protein biophysics and manipulate cellular excitability. PMID:27226448

Chloride regulates afferent arteriolar contraction in response to depolarization

DEFF Research Database (Denmark)

Hansen, P B; Jensen, B L; Skott, O

1998-01-01

-Renal vascular reactivity is influenced by the level of dietary salt intake. Recent in vitro data suggest that afferent arteriolar contractility is modulated by extracellular chloride. In the present study, we assessed the influence of chloride on K+-induced contraction in isolated perfused rabbit...... afferent arterioles. In 70% of vessels examined, K+-induced contraction was abolished by acute substitution of bath chloride. Consecutive addition of Cl- (30, 60, 80, 100, 110, and 117 mmol/L) restored the sensitivity to K+, and half-maximal response was observed at 82 mmol/L chloride. The calcium channel...... antagonist diltiazem (10(-6) mol/L) abolished K+-induced contractions. Bicarbonate did not modify the sensitivity to chloride. Norepinephrine (10(-6) mol/L) induced full contraction in depolarized vessels even in the absence of chloride. Iodide and nitrate were substituted for chloride with no inhibitory...

Intercellular K⁺ accumulation depolarizes Type I vestibular hair cells and their associated afferent nerve calyx.

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Contini, D; Zampini, V; Tavazzani, E; Magistretti, J; Russo, G; Prigioni, I; Masetto, S

2012-12-27

Mammalian vestibular organs contain two types of sensory receptors, named Type I and Type II hair cells. While Type II hair cells are contacted by several small afferent nerve terminals, the basolateral surface of Type I hair cells is almost entirely enveloped by a single large afferent nerve terminal, called calyx. Moreover Type I, but not Type II hair cells, express a low-voltage-activated outward K(+) current, I(K,L), which is responsible for their much lower input resistance (Rm) at rest as compared to Type II hair cells. The functional meaning of I(K,L) and associated calyx is still enigmatic. By combining the patch-clamp whole-cell technique with the mouse whole crista preparation, we have recorded the current- and voltage responses of in situ hair cells. Outward K(+) current activation resulted in K(+) accumulation around Type I hair cells, since it induced a rightward shift of the K(+) reversal potential the magnitude of which depended on the amplitude and duration of K(+) current flow. Since this phenomenon was never observed for Type II hair cells, we ascribed it to the presence of a residual calyx limiting K(+) efflux from the synaptic cleft. Intercellular K(+) accumulation added a slow (τ>100ms) depolarizing component to the cell voltage response. In a few cases we were able to record from the calyx and found evidence for intercellular K(+) accumulation as well. The resulting depolarization could trigger a discharge of action potentials in the afferent nerve fiber. Present results support a model where pre- and postsynaptic depolarization produced by intercellular K(+) accumulation cooperates with neurotransmitter exocytosis in sustaining afferent transmission arising from Type I hair cells. While vesicular transmission together with the low Rm of Type I hair cells appears best suited for signaling fast head movements, depolarization produced by intercellular K(+) accumulation could enhance signal transmission during slow head movements. Copyright �

Cholecystokinin enhances visceral pain-related affective memory via vagal afferent pathway in rats

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Cao Bing

2012-06-01

Full Text Available Abstract Background Pain contains both sensory and affective dimensions. Using a rodent visceral pain assay that combines the colorectal distension (CRD model with the conditioned place avoidance (CPA paradigms, we measured a learned behavior that directly reflects the affective component of visceral pain, and showed that perigenual anterior cingulate cortex (pACC activation is critical for memory processing involved in long-term visceral affective state and prediction of aversive stimuli by contextual cue. Progress has been made and suggested that activation of vagal afferents plays a role in the behavioral control nociception and memory storage processes. In human patients, electrical vagus nerve stimulation enhanced retention of verbal learning performance. Cholecystokinin-octapeptide (CCK, which is a gastrointestinal hormone released during feeding, has been shown to enhance memory retention. Mice access to food immediately after training session enhanced memory retention. It has been well demonstrated that CCK acting on vagal afferent fibers mediates various physiological functions. We hypothesize that CCK activation of vagal afferent enhances visceral pain-related affective memory. Results In the presented study, infusion of CCK-8 at physiological concentration combining with conditional training significantly increased the CRD-induced CPA scores, and enhanced the pain affective memory retention. In contrast, CCK had no effect on CPA induced by non-nociceptive aversive stimulus (U69,593. The physiological implications were further strengthened by the similar effects observed in the rats with duodenal infusion of 5% peptone, which has been shown to induce increases in plasma CCK levels. CCK-8 receptor antagonist CR-1409 or perivagal application of capsaicin abolished the effect of CCK on aversive visceral pain memory, which was consistent with the notion that vagal afferent modulates affective aspects of visceral pain. CCK does not change

Cholecystokinin enhances visceral pain-related affective memory via vagal afferent pathway in rats.

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Cao, Bing; Zhang, Xu; Yan, Ni; Chen, Shengliang; Li, Ying

2012-06-09

Pain contains both sensory and affective dimensions. Using a rodent visceral pain assay that combines the colorectal distension (CRD) model with the conditioned place avoidance (CPA) paradigms, we measured a learned behavior that directly reflects the affective component of visceral pain, and showed that perigenual anterior cingulate cortex (pACC) activation is critical for memory processing involved in long-term visceral affective state and prediction of aversive stimuli by contextual cue. Progress has been made and suggested that activation of vagal afferents plays a role in the behavioral control nociception and memory storage processes.In human patients, electrical vagus nerve stimulation enhanced retention of verbal learning performance. Cholecystokinin-octapeptide (CCK), which is a gastrointestinal hormone released during feeding, has been shown to enhance memory retention. Mice access to food immediately after training session enhanced memory retention. It has been well demonstrated that CCK acting on vagal afferent fibers mediates various physiological functions. We hypothesize that CCK activation of vagal afferent enhances visceral pain-related affective memory. In the presented study, infusion of CCK-8 at physiological concentration combining with conditional training significantly increased the CRD-induced CPA scores, and enhanced the pain affective memory retention. In contrast, CCK had no effect on CPA induced by non-nociceptive aversive stimulus (U69,593). The physiological implications were further strengthened by the similar effects observed in the rats with duodenal infusion of 5% peptone, which has been shown to induce increases in plasma CCK levels. CCK-8 receptor antagonist CR-1409 or perivagal application of capsaicin abolished the effect of CCK on aversive visceral pain memory, which was consistent with the notion that vagal afferent modulates affective aspects of visceral pain. CCK does not change the nociceptive response (visceral pain

Experimental muscle pain produces central modulation of proprioceptive signals arising from jaw muscle spindles.

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Capra, N F; Ro, J Y

2000-05-01

The aim of the present study was to investigate the effects of intramuscular injection with hypertonic saline, a well-established experimental model for muscle pain, on central processing of proprioceptive input from jaw muscle spindle afferents. Fifty-seven cells were recorded from the medial edge of the subnucleus interpolaris (Vi) and the adjacent parvicellular reticular formation from 11 adult cats. These cells were characterized as central units receiving jaw muscle spindle input based on their responses to electrical stimulation of the masseter nerve, muscle palpation and jaw stretch. Forty-five cells, which were successfully tested with 5% hypertonic saline, were categorized as either dynamic-static (DS) (n=25) or static (S) (n=20) neurons based on their responses to different speeds and amplitudes of jaw movement. Seventy-six percent of the cells tested with an ipsilateral injection of hypertonic saline showed a significant modulation of mean firing rates (MFRs) during opening and/or holding phases. The most remarkable saline-induced change was a significant reduction of MFR during the hold phase in S units (100%, 18/18 modulated). Sixty-nine percent of the DS units (11/16 modulated) also showed significant changes in MFRs limited to the hold phase. However, in the DS neurons, the MFRs increased in seven units and decreased in four units. Finally, five DS neurons showed significant changes of MFRs during both opening and holding phases. Injections of isotonic saline into the ipsilateral masseter muscle had little effect, but hypertonic saline injections made into the contralateral masseter muscle produced similar results to ipsilateral injections with hypertonic saline. These results unequivocally demonstrate that intramuscular injection with an algesic substance, sufficient to produce muscle pain, produces significant changes in the proprioceptive properties of the jaw movement-related neurons. Potential mechanisms involved in saline-induced changes in the

Structure of the afferent terminals in terminal ganglion of a cricket and persistent homology.

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Jacob Brown

Full Text Available We use topological data analysis to investigate the three dimensional spatial structure of the locus of afferent neuron terminals in crickets Acheta domesticus. Each afferent neuron innervates a filiform hair positioned on a cercus: a protruding appendage at the rear of the animal. The hairs transduce air motion to the neuron signal that is used by a cricket to respond to the environment. We stratify the hairs (and the corresponding afferent terminals into classes depending on hair length, along with position. Our analysis uncovers significant structure in the relative position of these terminal classes and suggests the functional relevance of this structure. Our method is very robust to the presence of significant experimental and developmental noise. It can be used to analyze a wide range of other point cloud data sets.

Merkel cells transduce and encode tactile stimuli to drive Aβ-afferent impulses

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Ikeda, Ryo; Cha, Myeounghoon; Ling, Jennifer; Jia, Zhanfeng; Coyle, Dennis; Gu, Jianguo G.

2014-01-01

SUMMARY Sensory systems for detecting tactile stimuli have evolved from touch-sensing nerves in invertebrates to complicated tactile end-organs in mammals. Merkel discs are tactile end-organs consisting of Merkel cells and Aβ-afferent nerve endings, and are localized in fingertips, whisker hair follicles and other touch-sensitive spots. Merkel discs transduce touch into slowly adapting impulses to enable tactile discrimination, but their transduction and encoding mechanisms remain unknown. Using rat whisker hair follicles, we show that Merkel cells rather than Aβ-afferent nerve endings are primary sites of tactile transduction, and identify the Piezo2 ion channel as the Merkel cell mechanical transducer. Piezo2 transduces tactile stimuli into Ca2+-action potentials in Merkel cells, which drive Aβ-afferent nerve endings to fire slowly adapting impulses. We further demonstrate that Piezo2 and Ca2+-action potentials in Merkel cells are required for behavioral tactile responses. Our findings provide insights into how tactile end-organs function and have clinical implications for tactile dysfunctions. PMID:24746027

Differential roles of stretch-sensitive pelvic nerve afferents innervating mouse distal colon and rectum

OpenAIRE

Feng, Bin; Brumovsky, Pablo R.; Gebhart, Gerald F.

2010-01-01

Information about colorectal distension (i.e., colorectal dilation by increased intraluminal pressure) is primarily encoded by stretch-sensitive colorectal afferents in the pelvic nerve (PN). Despite anatomic differences between rectum and distal colon, little is known about the functional roles of colonic vs. rectal afferents in the PN pathway or the quantitative nature of mechanosensory encoding. We utilized an in vitro mouse colorectum-PN preparation to investigate pressure-encoding charac...

Spinal afferent neurons projecting to the rat lung and pleura express acid sensitive channels

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Kummer Wolfgang

2006-07-01

Full Text Available Abstract Background The acid sensitive ion channels TRPV1 (transient receptor potential vanilloid receptor-1 and ASIC3 (acid sensing ion channel-3 respond to tissue acidification in the range that occurs during painful conditions such as inflammation and ischemia. Here, we investigated to which extent they are expressed by rat dorsal root ganglion neurons projecting to lung and pleura, respectively. Methods The tracer DiI was either injected into the left lung or applied to the costal pleura. Retrogradely labelled dorsal root ganglion neurons were subjected to triple-labelling immunohistochemistry using antisera against TRPV1, ASIC3 and neurofilament 68 (marker for myelinated neurons, and their soma diameter was measured. Results Whereas 22% of pulmonary spinal afferents contained neither channel-immunoreactivity, at least one is expressed by 97% of pleural afferents. TRPV1+/ASIC3- neurons with probably slow conduction velocity (small soma, neurofilament 68-negative were significantly more frequent among pleural (35% than pulmonary afferents (20%. TRPV1+/ASIC3+ neurons amounted to 14 and 10% respectively. TRPV1-/ASIC3+ neurons made up between 44% (lung and 48% (pleura of neurons, and half of them presumably conducted in the A-fibre range (larger soma, neurofilament 68-positive. Conclusion Rat pleural and pulmonary spinal afferents express at least two different acid-sensitive channels that make them suitable to monitor tissue acidification. Patterns of co-expression and structural markers define neuronal subgroups that can be inferred to subserve different functions and may initiate specific reflex responses. The higher prevalence of TRPV1+/ASIC3- neurons among pleural afferents probably reflects the high sensitivity of the parietal pleura to painful stimuli.

Influence of oculomotor nerve afferents on central endings of primary trigeminal fibers.

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Manni, E; Bortolami, R; Pettorossi, V E; Lucchi, M L; Callegari, E; Draicchio, F

1987-12-01

Painful fibers running in the third nerve and originating from the ophthalmic trigeminal area send their central projections at level of substantia gelatinosa of nucleus caudalis trigemini. The central endings of these fibers form axoaxonic synapses with trigeminal fibers entering the brain stem through the trigeminal root. The effect of electrical stimulation of the third nerve central stump on the central endings of trigeminal afferent fibers consists in an increased excitability, possibly resulting in a presynaptic inhibition. This inhibitory influence is due to both direct and indirect connections of the third nerve afferent fibers with the trigeminal ones.

Combined genetic and pharmacological inhibition of TRPV1 and P2X3 attenuates colorectal hypersensitivity and afferent sensitization

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Kiyatkin, Michael E.; Feng, Bin; Schwartz, Erica S.

2013-01-01

The ligand-gated channels transient receptor potential vanilloid 1 (TRPV1) and P2X3 have been reported to facilitate colorectal afferent neuron sensitization, thus contributing to organ hypersensitivity and pain. In the present study, we hypothesized that TRPV1 and P2X3 cooperate to modulate colorectal nociception and afferent sensitivity. To test this hypothesis, we employed TRPV1-P2X3 double knockout (TPDKO) mice and channel-selective pharmacological antagonists and evaluated combined channel contributions to behavioral responses to colorectal distension (CRD) and afferent fiber responses to colorectal stretch. Baseline responses to CRD were unexpectedly greater in TPDKO compared with control mice, but zymosan-produced CRD hypersensitivity was absent in TPDKO mice. Relative to control mice, proportions of mechanosensitive and -insensitive pelvic nerve afferent classes were not different in TPDKO mice. Responses of mucosal and serosal class afferents to mechanical probing were unaffected, whereas responses of muscular (but not muscular/mucosal) afferents to stretch were significantly attenuated in TPDKO mice; sensitization of both muscular and muscular/mucosal afferents by inflammatory soup was also significantly attenuated. In pharmacological studies, the TRPV1 antagonist A889425 and P2X3 antagonist TNP-ATP, alone and in combination, applied onto stretch-sensitive afferent endings attenuated responses to stretch; combined antagonism produced greater attenuation. In the aggregate, these observations suggest that 1) genetic manipulation of TRPV1 and P2X3 leads to reduction in colorectal mechanosensation peripherally and compensatory changes and/or disinhibition of other channels centrally, 2) combined pharmacological antagonism produces more robust attenuation of mechanosensation peripherally than does antagonism of either channel alone, and 3) the relative importance of these channels appears to be enhanced in colorectal hypersensitivity. PMID:23989007

The Renal Nerves in Chronic Heart Failure: Afferent and Efferent Mechanisms

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Alicia Marie Schiller

2015-08-01

Full Text Available The function of the renal nerves has been an area of scientific and medical interest for many years. The recent advent of a minimally invasive catheter-based method of renal denervation has renewed excitement in understanding the afferent and efferent actions of the renal nerves in multiple diseases. While hypertension has been the focus of much this work, less attention has been given to the role of the renal nerves in the development of chronic heart failure (CHF. Recent studies from our laboratory and those of others implicate an essential role for the renal nerves in the development and progression of CHF. Using a rabbit tachycardia model of CHF and surgical unilateral renal denervation, we provide evidence for both renal efferent and afferent mechanisms in the pathogenesis of CHF. Renal denervation prevented the decrease in renal blood flow observed in CHF while also preventing increases in Angiotensin-II receptor protein in the microvasculature of the renal cortex. Renal denervation in CHF also reduced physiological markers of autonomic dysfunction including an improvement in arterial baroreflex function, heart rate variability, and decreased resting cardiac sympathetic tone. Taken together, the renal sympathetic nerves are necessary in the pathogenesis of CHF via both efferent and afferent

Plane of vertebral movement eliciting muscle lengthening history in the low back influences the decrease in muscle spindle responsiveness of the cat.

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Ge, Weiqing; Cao, Dong-Yuan; Long, Cynthia R; Pickar, Joel G

2011-12-01

Proprioceptive feedback is thought to play a significant role in controlling both lumbopelvic and intervertebral orientations. In the lumbar spine, a vertebra's positional history along the dorsal-ventral axis has been shown to alter the position, movement, and velocity sensitivity of muscle spindles in the multifidus and longissimus muscles. These effects appear due to muscle history. Because spinal motion segments have up to 6 degrees of freedom for movement, we were interested in whether the axis along which the history is applied differentially affects paraspinal muscle spindles. We tested the null hypothesis that the loading axis, which creates a vertebra's positional history, has no effect on a lumbar muscle spindle's subsequent response to vertebral position or movement. Identical displacements were applied along three orthogonal axes directly at the L(6) spinous process using a feedback motor system under displacement control. Single-unit nerve activity was recorded from 60 muscle spindle afferents in teased filaments from L(6) dorsal rootlets innervating intact longissimus or multifidus muscles of deeply anesthetized cats. Muscle lengthening histories along the caudal-cranial and dorsal-ventral axis, compared with the left-right axis, produced significantly greater reductions in spindle responses to vertebral position and movement. The spinal anatomy suggested that the effect of a lengthening history is greatest when that history had occurred along an axis lying within the anatomical plane of the facet joint. Speculation is made that the interaction between normal spinal mechanics and the inherent thixotropic property of muscle spindles poses a challenge for feedback and feedforward motor control of the lumbar spine.

Fine structure of primary afferent axon terminals projecting from rapidly adapting mechanoreceptors of the toe and foot pads of the cat.

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Maxwell, D J; Bannatyne, B A; Fyffe, R E; Brown, A G

1984-04-01

Two Pacinian corpuscle afferents and two rapidly adapting afferents from Krause corpuscles were intra-axonally labelled with horseradish peroxidase in the lumbosacral enlargement of the cat's spinal cord. Tissue was prepared for combined light and electron microscopical analysis. Boutons from both classes of afferent had similar ultrastructural appearances. They both formed from one to three synaptic junctions with dendritic shafts and spines and received axo-axonic synapses. In addition, both categories of bouton were seen to be presynaptic to structures interpreted as vesicle-containing dendrites. It is concluded that both types of afferent fibre are subject to presynaptic control and that they synapse with dorsal horn neurones which are possibly interneurones involved in primary afferent depolarization and post-synaptic dorsal column neurones.

Short-latency crossed responses in the human biceps femoris muscle

DEFF Research Database (Denmark)

Stevenson, Andrew J T; Kamavuako, Ernest N; Geertsen, Svend Sparre

2015-01-01

Interlimb reflexes contribute to the central neural coordination between different limbs in both humans and animals. Although commissural interneurons have only been directly identified in animals, spinally mediated interlimb reflexes have been discovered in a number of human lower limb muscles......, indicating their existence in humans. The aim of the present study was to investigate whether short-latency crossed-spinal reflexes are present in the contralateral biceps femoris (cBF) muscle following ipsilateral knee (iKnee) joint rotations during a sitting task, where participants maintained a slight pre...... pathways (likely involving commissural interneurons) from ipsilateral afferents to common motoneurons in the contralateral leg can likely explain the perturbation direction-dependent reversal in the sign of the short-latency cBF reflex. This article is protected by copyright. All rights reserved....

"Proprioceptive signature" of cursive writing in humans: a multi-population coding.

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Roll, Jean-Pierre; Albert, Frédéric; Ribot-Ciscar, Edith; Bergenheim, Mikael

2004-08-01

The goal of the present study was to investigate the firing behavior of populations of muscle spindle afferents in all the muscles acting on the ankle while this joint was being subjected to "writing-like" movements. First it was proposed to determine whether the ensemble of muscle spindles give rise to a unique, specific, and reproducible feedback information characterizing each letter, number or short word. Secondly, we analyzed how the proprioceptive feedback on the whole encodes the spatial and temporal characteristics of writing movements using the "vector population model". The unitary activity of 51 primary and secondary muscle spindle afferents was recorded in the tibial and common peroneal nerves at the level of the popliteal fossea, using the microneurographic method. The units recorded from belonged to the tibialis anterior, the extensor digitorum longus, the extensor hallucis longus, the peroneus lateralis, the gastrocnemius-soleus and the tibialis posterior muscles. The "writing-like" movements were randomly imposed at a "natural" velocity via a computer-controlled machine in a two-dimensional space. In general, muscle spindle afferents from any of the six muscles responded according to the tuning properties of the parent muscle, i.e. increasing their discharge rate during the phases where the direction of movement was within the preferred sensory sector of the parent muscle. The whole trajectory of the writing movements was coded in turn by the activity of Ia afferents arising from all the muscles acting on the joint. Both single afferent responses and population responses were found to be highly specific and reproducible with each graphic sign. The complex multi-muscle afferent pattern involved, with its timing and distribution in the muscle space, seems to constitute a true "proprioceptive signature" for each graphic symbol. The ensemble of muscle spindle afferents were therefore found to encode the instantaneous direction and velocity of writing

GABA in Paraventricular Nucleus Regulates Adipose Afferent Reflex in Rats.

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Lei Ding

Full Text Available Chemical stimulation of white adipose tissue (WAT induces adipose afferent reflex (AAR, and thereby causes a general sympathetic activation. Paraventricular nucleus (PVN is important in control of sympathetic outflow. This study was designed to investigate the role of γ-aminobutyric acid (GABA in PVN in regulating the AAR.Experiments were carried out in anesthetized rats. Renal sympathetic nerve activity (RSNA and mean arterial pressure (MAP were continuously recorded. AAR was evaluated by the RSNA and MAP responses to electrical stimulation of the right epididymal WAT (eWAT afferent nerve. Electrical stimulation of eWAT afferent nerve increase RSNA. Bilateral microinjection of the GABAA receptor agonist isoguvacine or the GABAB receptor agonist baclofen attenuated the AAR. The effect of isoguvacine on the AAR was greater than that of baclofen. The GABAA receptor antagonist gabazine enhanced the AAR, while the GABAB receptor antagonist CGP-35348 had no significant effect on the AAR. Bilateral PVN microinjection of vigabatrin, a selective GABA-transaminase inhibitor, to increase endogenous GABA levels in the PVN abolished the AAR. The inhibitory effect of vigabatrin on the AAR was attenuated by the pretreatment with gabazine or CGP-35348. Pretreatment with combined gabazine and CGP-35348 abolished the effects of vigabatrin.Activation of GABAA or GABAB receptors in the PVN inhibits the AAR. Blockade of GABAA receptors in the PVN enhances the AAR. Endogenous GABA in the PVN plays an important role in regulating the AAR.

Electrically evoked local muscle contractions cause an increase in hippocampal BDNF.

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Maekawa, Takahiro; Ogasawara, Riki; Tsutaki, Arata; Lee, Kihyuk; Nakada, Satoshi; Nakazato, Koichi; Ishii, Naokata

2018-05-01

High-intensity exercise has recently been shown to cause an increase in brain-derived neurotropic factor (BDNF) in the hippocampus. Some studies have suggested that myokines secreted from contracting skeletal muscle, such as irisin (one of the truncated form of fibronectin type III domain-containing protein 5 (FNDC5)), play important roles in this process. Thus, we hypothesized that locally evoked muscle contractions may cause an increase of BDNF in the hippocampus through some afferent mechanisms. Under anesthesia, Sprague-Dawley rats were fixed on a custom-made dynamometer and their triceps surae muscles were made to maximally contract via delivery of electric stimulations of the sciatic nerve (100 Hz with 1-ms pulse and 3-s duration). Following 50 repeated maximal isometric contractions, the protein expressions of BDNF and activation of its receptor in the hippocampus significantly increased compared with the sham-operated control rats. However, the expression of both BDNF and FNDC5 within stimulated muscles did not significantly increase, nor did their serum concentrations change. These results indicate that local muscular contractions under unconsciousness can induce BDNF expression in the hippocampus. This effect may be mediated by peripheral reception of muscle contraction, but not by systemic factors.

Afferent Loop Syndrome after Roux-en-Y Total Gastrectomy Caused by Volvulus of the Roux-Limb

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Hideki Katagiri

2016-01-01

Full Text Available Afferent loop syndrome is a rare complication of gastric surgery. An obstruction of the afferent limb can present in various ways. A 73-year-old man presented with one day of persistent abdominal pain, gradually radiating to the back. He had a history of total gastrectomy with a Roux-en-Y reconstruction. Abdominal computed tomography scan revealed dilation of the duodenum and small intestine in the left upper quadrant. Exploratory laparotomy showed volvulus of the biliopancreatic limb that caused afferent loop syndrome. In this patient, the 50 cm long limb was the cause of volvulus. It is important to fashion a Roux-limb of appropriate length to prevent this complication.

The modulation of visceral functions by somatic afferent activity.

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Sato, A; Schmidt, R F

1987-01-01

We began by briefly reviewing the historical background of neurophysiological studies of the somato-autonomic reflexes and then discussed recent studies on somatic-visceral reflexes in combination with autonomic efferent nerve activity and effector organ responses. Most of the studies that have advanced our knowledge in this area have been carried out on anesthetized animals, thus eliminating emotional factors. We would like to emphasize again that the functions of many, or perhaps all visceral organs can be modulated by somato-sympathetic or somato-parasympathetic reflex activity induced by a appropriate somatic afferent stimulation in anesthetized animals. As mentioned previously, some autonomic nervous outflow, e.g. the adrenal sympathetic nerve activity, is involved in the control of hormonal secretion. John F. Fulton wrote in his famous textbook "Physiology of the Nervous System" (1949) that the posterior pituitary neurosecretion system (i.e. for oxytocin and vasopressin) could be considered a part of the parasympathetic nervous system. In the study of body homeostasis and environmental adaptation it would seem very important to further analyze the contribution of somatic afferent input to the autonomic nervous and hormonal regulation of visceral organ activity. Also, some immunological functions have been found to be influenced by autonomic nerves or hormones (e.g. adrenal cortical hormone and catecholamines). Finally, we must take into account, as we have briefly discussed, that visceral functions can be modulated by somatic afferent input via various degrees of integration of autonomic nerves, hormones, and immunological processes. We trust that such research will be expanded to higher species of mammals, and that ultimately this knowledge of somato-visceral reflexes obtained in the physiological laboratory will become clinically useful in influencing visceral functions.

The renal nerves in chronic heart failure: efferent and afferent mechanisms

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Schiller, Alicia M.; Pellegrino, Peter R.; Zucker, Irving H.

2015-01-01

The function of the renal nerves has been an area of scientific and medical interest for many years. The recent advent of a minimally invasive catheter-based method of renal denervation has renewed excitement in understanding the afferent and efferent actions of the renal nerves in multiple diseases. While hypertension has been the focus of much this work, less attention has been given to the role of the renal nerves in the development of chronic heart failure (CHF). Recent studies from our laboratory and those of others implicate an essential role for the renal nerves in the development and progression of CHF. Using a rabbit tachycardia model of CHF and surgical unilateral renal denervation, we provide evidence for both renal efferent and afferent mechanisms in the pathogenesis of CHF. Renal denervation prevented the decrease in renal blood flow observed in CHF while also preventing increases in Angiotensin-II receptor protein in the microvasculature of the renal cortex. Renal denervation in CHF also reduced physiological markers of autonomic dysfunction including an improvement in arterial baroreflex function, heart rate variability, and decreased resting cardiac sympathetic tone. Taken together, the renal sympathetic nerves are necessary in the pathogenesis of CHF via both efferent and afferent mechanisms. Additional investigation is warranted to fully understand the role of these nerves and their role as a therapeutic target in CHF. PMID:26300788

Measurement of the relative afferent pupillary defect in retinal detachment.

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Bovino, J A; Burton, T C

1980-07-01

A swinging flashlight test and calibrated neutral density filters were used to quantitate the depth of relative afferent pupillary defects in ten patients with retinal detachment. Postoperatively, the pupillary responses returned to normal in seven of nine patients with anatomically successful surgery.

[Myofibroblasts and afferent signalling in the urinary bladder. A concept].

Science.gov (United States)

Neuhaus, J; Scholler, U; Freick, K; Schwalenberg, T; Heinrich, M; Horn, L C; Stolzenburg, J U

2008-09-01

Afferent signal transduction in the urinary bladder is still not clearly understood. An increasing body of evidence supports the view of complex interactions between urothelium, suburothelial myofibroblasts, and sensory nerves. Bladder tissue from tumour patients was used in this study. Methods included confocal immunofluorescence, polymerase chain reaction, calcium imaging, and fluorescence recovery after photobleaching (FRAP).Myofibroblasts express muscarinic and purinergic receptors. They show constitutive spontaneous activity in calcium imaging, which completely depends on extracellular calcium. Stimulation with carbachol and ATP-evoked intracellular calcium transients also depend on extracellular calcium. The intensive coupling between the cells is significantly diminished by incubation with TGF-beta 1. Myofibroblasts form an important cellular element within the afferent signalling of the urinary bladder. They possess all features required to take part in the complex interactions with urothelial cells and sensory nerves. Modulation of their function by cytokines may provide a pathomechanism for bladder dysfunction.

A murine model of a novel surgical architecture for proprioceptive muscle feedback and its potential application to control of advanced limb prostheses

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Clites, Tyler R.; Carty, Matthew J.; Srinivasan, Shriya; Zorzos, Anthony N.; Herr, Hugh M.

2017-06-01

Objective. Proprioceptive mechanisms play a critical role in both reflexive and volitional lower extremity control. Significant strides have been made in the development of bionic limbs that are capable of bi-directional communication with the peripheral nervous system, but none of these systems have been capable of providing physiologically-relevant muscle-based proprioceptive feedback through natural neural pathways. In this study, we present the agonist-antagonist myoneural interface (AMI), a surgical approach with the capacity to provide graded kinesthetic feedback from a prosthesis through mechanical activation of native mechanoreceptors within residual agonist-antagonist muscle pairs. Approach. (1) Sonomicrometery and electroneurography measurement systems were validated using a servo-based muscle tensioning system. (2) A heuristic controller was implemented to modulate functional electrical stimulation of an agonist muscle, using sonomicrometric measurements of stretch from a mechanically-coupled antagonist muscle as feedback. (3) One AMI was surgically constructed in the hindlimb of each rat. (4) The gastrocnemius-soleus complex of the rat was cycled through a series of ramp-and-hold stretches in two different muscle architectures: native (physiologically-intact) and AMI (modified). Integrated electroneurography from the tibial nerve was compared across the two architectures. Main results. Correlation between stretch and afferent signal demonstrated that the AMI is capable of provoking graded afferent signals in response to ramp-and-hold stretches, in a manner similar to the native muscle architecture. The response magnitude in the AMI was reduced when compared to the native architecture, likely due to lower stretch amplitudes. The closed-loop control system showed robustness at high stretch magnitudes, with some oscillation at low stretch magnitudes. Significance. These results indicate that the AMI has the potential to communicate meaningful kinesthetic

Afferent and Efferent Connections of the Cortex-Amygdala Transition Zone in Mice.

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Cádiz-Moretti, Bernardita; Abellán-Álvaro, María; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

2016-01-01

The transitional zone between the ventral part of the piriform cortex and the anterior cortical nucleus of the amygdala, named the cortex-amygdala transition zone (CxA), shows two differential features that allow its identification as a particular structure. First, it receives dense cholinergic and dopaminergic innervations as compared to the adjacent piriform cortex and amygdala, and second, it receives projections from the main and accessory olfactory bulbs. In this work we have studied the pattern of afferent and efferent projections of the CxA, which are mainly unknown, by using the retrograde tracer Fluorogold and the anterograde tracer biotinylated dextranamine. The results show that the CxA receives a relatively restricted set of intratelencephalic connections, originated mainly by the olfactory system and basal forebrain, with minor afferents from the amygdala. The only relevant extratelencephalic afference originates in the ventral tegmental area (VTA). The efferent projections of the CxA reciprocate the inputs from the piriform cortex and olfactory amygdala. In addition, the CxA projects densely to the basolateral amygdaloid nucleus and the olfactory tubercle. The extratelencephalic projections of the CxA are very scarce, and target mainly hypothalamic structures. The pattern of connections of the CxA suggests that it is indeed a transitional area between the piriform cortex and the cortical amygdala. Double labeling with choline acetyltransferase indicates that the afferent projection from the basal forebrain is the origin of its distinctive cholinergic innervation, and double labeling with dopamine transporter shows that the projection from the VTA is the source of dopaminergic innervation. These connectivity and neurochemical features, together with the fact that it receives vomeronasal in addition to olfactory information, suggest that the CxA may be involved in processing olfactory information endowed with relevant biological meaning, such as odors

Kv1 channels and neural processing in vestibular calyx afferents

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Frances L Meredith

2015-06-01

Full Text Available Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K+ channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K+ channels could help alleviate vestibular dysfunction on earth and in space.

Kv1 channels and neural processing in vestibular calyx afferents.

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Meredith, Frances L; Kirk, Matthew E; Rennie, Katherine J

2015-01-01

Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K(+) channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K(+) channels could help alleviate vestibular dysfunction on earth and in space.

Afferent projections to the pontine micturition center in the cat

NARCIS (Netherlands)

Kuipers, R; Mouton, LJ; Holstege, G; Kuiper, Rutger

2006-01-01

The pontine micturition center (PMC) or Barrington's nucleus controls micturition by way of its descending projections to the sacral spinal cord. However, little is known about the afferents to the PMC that control its function and may be responsible for dysfunction in patients with

The urodelean Mauthner cell. Morphology of the afferent synapses to the M-cell of larval Salamandra salamandra

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Cioni, C.; De Palma, F.; De Vito, L.; Stefanelli, A. [Rome, Univ. (Italy). Dipt. di Biologia Animale e dell`Uomo

1997-12-31

In the present work the fine morphology and the distribution of the afferent synapses to the Mauthner cell of larval Salamandra salamandra are described. The aim of the study is to characterize the synaptic bed in the larvae of this terrestrial salamander in order to compare it with that of larval axolotl and larval anurans. Four main types of afferent endings have been identified: myelinated club endings, round-vesicle end bulbs, flattened-vesicle end bulbs and spiral fibers endings. The M-cell afferent synaptology of larval stages of terrestrial amphibians is quite similar to that previously observed in larval stages of aquatic species. This fact can be related to the fundamental similarities between the larval lifestyles.

The urodelean Mauthner cell. Morphology of the afferent synapses to the M-cell of larval Salamandra salamandra

Energy Technology Data Exchange (ETDEWEB)

Cioni, C; De Palma, F; De Vito, L; Stefanelli, A [Rome, Univ. (Italy). Dipt. di Biologia Animale e dell` Uomo

1998-12-31

In the present work the fine morphology and the distribution of the afferent synapses to the Mauthner cell of larval Salamandra salamandra are described. The aim of the study is to characterize the synaptic bed in the larvae of this terrestrial salamander in order to compare it with that of larval axolotl and larval anurans. Four main types of afferent endings have been identified: myelinated club endings, round-vesicle end bulbs, flattened-vesicle end bulbs and spiral fibers endings. The M-cell afferent synaptology of larval stages of terrestrial amphibians is quite similar to that previously observed in larval stages of aquatic species. This fact can be related to the fundamental similarities between the larval lifestyles.

Cooling reduces the cutaneous afferent firing response to vibratory stimuli in glabrous skin of the human foot sole.

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Lowrey, Catherine R; Strzalkowski, Nicholas D J; Bent, Leah R

2013-02-01

Skin on the foot sole plays an important role in postural control. Cooling the skin of the foot is often used to induce anesthesia to determine the role of skin in motor and balance control. The effect of cooling on the four classes of mechanoreceptor in the skin is largely unknown, and thus the aim of the present study was to characterize the effects of cooling on individual skin receptors in the foot sole. Such insight will better isolate individual receptor contributions to balance control. Using microneurography, we recorded 39 single nerve afferents innervating mechanoreceptors in the skin of the foot sole in humans. Afferents were identified as fast-adapting (FA) or slowly adapting (SA) type I or II (FA I n = 16, FA II n = 7, SA I n = 6, SA II n = 11). Receptor response to vibration was compared before and after cooling of the receptive field (2-20 min). Overall, firing response was abolished in 30% of all receptors, and this was equally distributed across receptor type (P = 0.69). Longer cooling times were more likely to reduce firing response below 50% of baseline; however, some afferent responses were abolished with shorter cooling times (2-5 min). Skin temperature was not a reliable indicator of the level of receptor activation and often became uncoupled from receptor response levels, suggesting caution in the use of this parameter as an indicator of anesthesia. When cooled, receptors preferentially coded lower frequencies in response to vibration. In response to a sustained indentation, SA receptors responded more like FA receptors, primarily coding "on-off" events.

Afferent-mediated modulation of the soleus muscle activity during the stance phase of human walking

DEFF Research Database (Denmark)

Nazarena, Mazzaro; Grey, Michael James; do Nascimento, Omar Feix

2006-01-01

The aim of this study was to investigate the contribution of proprioceptive feedback to the amplitude modulation of the soleus muscle activity during human walking. We have previously shown that slow-velocity, small-amplitude ankle dorsiflexion enhancements and reductions applied during the stance...

Thyroid hormone is required for pruning, functioning and long-term maintenance of afferent inner hair cell synapses.

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Sundaresan, Srividya; Kong, Jee-Hyun; Fang, Qing; Salles, Felipe T; Wangsawihardja, Felix; Ricci, Anthony J; Mustapha, Mirna

2016-01-01

Functional maturation of afferent synaptic connections to inner hair cells (IHCs) involves pruning of excess synapses formed during development, as well as the strengthening and survival of the retained synapses. These events take place during the thyroid hormone (TH)-critical period of cochlear development, which is in the perinatal period for mice and in the third trimester for humans. Here, we used the hypothyroid Snell dwarf mouse (Pit1(dw)) as a model to study the role of TH in afferent type I synaptic refinement and functional maturation. We observed defects in afferent synaptic pruning and delays in calcium channel clustering in the IHCs of Pit1(dw) mice. Nevertheless, calcium currents and capacitance reached near normal levels in Pit1(dw) IHCs by the age of onset of hearing, despite the excess number of retained synapses. We restored normal synaptic pruning in Pit1(dw) IHCs by supplementing with TH from postnatal day (P)3 to P8, establishing this window as being critical for TH action on this process. Afferent terminals of older Pit1(dw) IHCs showed evidence of excitotoxic damage accompanied by a concomitant reduction in the levels of the glial glutamate transporter, GLAST. Our results indicate that a lack of TH during a critical period of inner ear development causes defects in pruning and long-term homeostatic maintenance of afferent synapses. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Reciprocal inhibition between motor neurons of the tibialis anterior and triceps surae in humans.

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Yavuz, Utku Ş; Negro, Francesco; Diedrichs, Robin; Farina, Dario

2018-05-01

Motor neurons innervating antagonist muscles receive reciprocal inhibitory afferent inputs to facilitate the joint movement in the two directions. The present study investigates the mutual transmission of reciprocal inhibitory afferent inputs between the tibialis anterior (TA) and triceps surae (soleus and medial gastrocnemius) motor units. We assessed this mutual mechanism in large populations of motor units for building a statistical distribution of the inhibition amplitudes during standardized input to the motor neuron pools to minimize the effect of modulatory pathways. Single motor unit activities were identified using high-density surface electromyography (HDsEMG) recorded from the TA, soleus (Sol), and medial gastrocnemius (GM) muscles during isometric dorsi- and plantarflexion. Reciprocal inhibition on the antagonist muscle was elicited by electrical stimulation of the tibial (TN) or common peroneal nerves (CPN). The probability density distributions of reflex strength for each muscle were estimated to examine the strength of mutual transmission of reciprocal inhibitory input. The results showed that the strength of reciprocal inhibition in the TA motor units was fourfold greater than for the GM and the Sol motor units. This suggests an asymmetric transmission of reciprocal inhibition between ankle extensor and flexor muscles. This asymmetry cannot be explained by differences in motor unit type composition between the investigated muscles since we sampled low-threshold motor units in all cases. Therefore, the differences observed for the strength of inhibition are presumably due to a differential reciprocal spindle afferent input and the relative contribution of nonreciprocal inhibitory pathways. NEW & NOTEWORTHY We investigated the mutual transmission of reciprocal inhibition in large samples of motor units using a standardized input (electrical stimulation) to the motor neurons. The results demonstrated that the disynaptic reciprocal inhibition exerted

Mechanoreceptor afferent activity compared with receptor field dimensions and pressure changes in feline urinary bladder.

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Downie, J W; Armour, J A

1992-11-01

The relationship between vesical mechanoreceptor field dimensions and afferent nerve activity recorded in pelvic plexus nerve filaments was examined in chloralose-anesthetized cats. Orthogonal receptor field dimensions were monitored with piezoelectric ultrasonic crystals. Reflexly generated bladder contractile activity made measurements difficult, therefore data were collected from cats subjected to actual sacral rhizotomy. Afferent activity was episodic and was initiated at different pressure and receptor field dimension thresholds. Maximum afferent activity did not correlate with maximum volume or pressure. Furthermore, activity was not linearly related to intravesical pressure, receptor field dimensions, or calculated wall tension. Pressure-length hysteresis of the receptor fields occurred. The responses of identified afferent units and their associated receptor field dimensions to brief contractions elicited by the ganglion stimulant 1,1-dimethyl-4-phenylpiperazinium iodide (2.5-20 micrograms i.a.), studied under constant volume or constant pressure conditions, are compatible with bladder mechanoreceptors behaving as tension receptors. Because activity generated by bladder mechanoreceptors did not correlate in a simple fashion with intravesical pressure or receptor field dimensions, it is concluded that such receptors are influenced by the viscoelastic properties of the bladder wall. Furthermore, as a result of the heterogeneity of the bladder wall, receptor field tension appears to offer a more precise relationship with the activity of bladder wall mechanoreceptors than does intravesical pressure.

Anatomy and physiology of the afferent visual system.

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Prasad, Sashank; Galetta, Steven L

2011-01-01

The efficient organization of the human afferent visual system meets enormous computational challenges. Once visual information is received by the eye, the signal is relayed by the retina, optic nerve, chiasm, tracts, lateral geniculate nucleus, and optic radiations to the striate cortex and extrastriate association cortices for final visual processing. At each stage, the functional organization of these circuits is derived from their anatomical and structural relationships. In the retina, photoreceptors convert photons of light to an electrochemical signal that is relayed to retinal ganglion cells. Ganglion cell axons course through the optic nerve, and their partial decussation in the chiasm brings together corresponding inputs from each eye. Some inputs follow pathways to mediate pupil light reflexes and circadian rhythms. However, the majority of inputs arrive at the lateral geniculate nucleus, which relays visual information via second-order neurons that course through the optic radiations to arrive in striate cortex. Feedback mechanisms from higher cortical areas shape the neuronal responses in early visual areas, supporting coherent visual perception. Detailed knowledge of the anatomy of the afferent visual system, in combination with skilled examination, allows precise localization of neuropathological processes and guides effective diagnosis and management of neuro-ophthalmic disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

Fusimotor control of spindle sensitivity regulates central and peripheral coding of joint angles.

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Lan, Ning; He, Xin

2012-01-01

Proprioceptive afferents from muscle spindles encode information about peripheral joint movements for the central nervous system (CNS). The sensitivity of muscle spindle is nonlinearly dependent on the activation of gamma (γ) motoneurons in the spinal cord that receives inputs from the motor cortex. How fusimotor control of spindle sensitivity affects proprioceptive coding of joint position is not clear. Furthermore, what information is carried in the fusimotor signal from the motor cortex to the muscle spindle is largely unknown. In this study, we addressed the issue of communication between the central and peripheral sensorimotor systems using a computational approach based on the virtual arm (VA) model. In simulation experiments within the operational range of joint movements, the gamma static commands (γ(s)) to the spindles of both mono-articular and bi-articular muscles were hypothesized (1) to remain constant, (2) to be modulated with joint angles linearly, and (3) to be modulated with joint angles nonlinearly. Simulation results revealed a nonlinear landscape of Ia afferent with respect to both γ(s) activation and joint angle. Among the three hypotheses, the constant and linear strategies did not yield Ia responses that matched the experimental data, and therefore, were rejected as plausible strategies of spindle sensitivity control. However, if γ(s) commands were quadratically modulated with joint angles, a robust linear relation between Ia afferents and joint angles could be obtained in both mono-articular and bi-articular muscles. With the quadratic strategy of spindle sensitivity control, γ(s) commands may serve as the CNS outputs that inform the periphery of central coding of joint angles. The results suggest that the information of joint angles may be communicated between the CNS and muscles via the descending γ(s) efferent and Ia afferent signals.

Percutaneous Transhepatic Duodenal Drainage as an Alternative Approach in Afferent Loop Obstruction with Secondary Obstructive Jaundice in Recurrent Gastric Cancer

International Nuclear Information System (INIS)

Yao, N.-S.; Wu, C.-W.; Tiu, Chui-Mei; Liu, Jacqueline M.; Whang-Peng, Jacqueline; Chen, L.-T.

1998-01-01

Two cases are reported of chronic, partial afferent loop obstruction with resultant obstructive jaundice in recurrent gastric cancer. The diagnosis was made by characteristic clinical presentations, abdominal computed tomography, and cholescintigraphy. Percutaneous transhepatic duodenal drainage (PTDD) provided effective palliation for both afferent loop obstruction and biliary stasis. We conclude that cholescintigraphy is of value in making the diagnosis of partial afferent loop obstruction and in differentiating the cause of obstructive jaundice in such patients, and PTDD provides palliation for those patients in whom surgical intervention is not feasible

Afferent Endocrine Control of Eating

DEFF Research Database (Denmark)

Langhans, Wolfgang; Holst, Jens Juul

2016-01-01

The afferent endocrine factors that control eating can be separated into different categories. One obvious categorization is by the time course of their effects, with long-term factors that signal adiposity and short-term factors that operate within the time frame of single meals. The second...... obvious categorization is by the origin of the endocrine signalling molecules. The level of knowledge concerning the physiological mechanisms and relevance of the hormones that are implicated in the control of eating is clearly different. With the accumulating knowledge about the hormones' actions......, various criteria have been developed for when the effect of a hormone can be considered 'physiologic'. This chapter treats the hormones separately and categorizes them by origin. It discusses ALL hormones that are implicated in eating control such as Gastrointestinal (GI) hormone and glucagon-like peptide...

Flexible adaptation to an artificial recurrent connection from muscle to peripheral nerve in man.

Science.gov (United States)

Kato, Kenji; Sasada, Syusaku; Nishimura, Yukio

2016-02-01

Controlling a neuroprosthesis requires learning a novel input-output transformation; however, how subjects incorporate this into limb control remains obscure. To elucidate the underling mechanisms, we investigated the motor adaptation process to a novel artificial recurrent connection (ARC) from a muscle to a peripheral nerve in healthy humans. In this paradigm, the ulnar nerve was electrically stimulated in proportion to the activation of the flexor carpi ulnaris (FCU), which is ulnar-innervated and monosynaptically innervated from Ia afferents of the FCU, defined as the "homonymous muscle," or the palmaris longus (PL), which is not innervated by the ulnar nerve and produces similar movement to the FCU, defined as the "synergist muscle." The ARC boosted the activity of the homonymous muscle and wrist joint movement during a visually guided reaching task. Participants could control muscle activity to utilize the ARC for the volitional control of wrist joint movement and then readapt to the absence of the ARC to either input muscle. Participants reduced homonymous muscle recruitment with practice, regardless of the input muscle. However, the adaptation process in the synergist muscle was dependent on the input muscle. The activity of the synergist muscle decreased when the input was the homonymous muscle, whereas it increased when it was the synergist muscle. This reorganization of the neuromotor map, which was maintained as an aftereffect of the ARC, was observed only when the input was the synergist muscle. These findings demonstrate that the ARC induced reorganization of neuromotor map in a targeted and sustainable manner. Copyright © 2016 the American Physiological Society.

Superior ophthalmic vein enlargement and increased muscle index in dysthyroid optic neuropathy.

Science.gov (United States)

Lima, Breno da Rocha; Perry, Julian D

2013-01-01

To compare superior ophthalmic vein diameter and extraocular muscle index in patients with thyroid eye disease with or without optic neuropathy. High-resolution CT scan images of 40 orbits of 20 patients with history of thyroid eye disease (with or without optic neuropathy), who underwent orbital decompression surgery from January 2007 to November 2009, were retrospectively reviewed. Superior ophthalmic vein diameter was measured in coronal and axial planes. Extraocular muscle index was calculated according to the method proposed by Barrett et al. The clinical diagnosis of optic neuropathy was based on characteristic signs that included afferent pupillary defect, decreased visual acuity, visual field defects, and dyschromatopsia. Orbits were divided in 2 groups based on presence or absence of optic neuropathy. Superior ophthalmic vein diameter was significantly higher in orbits with concomitant optic neuropathy (mean 2.4 ± 0.4mm, p optic neuropathy (mean 57.9% ± 5.7%, p = 0.0002). Muscle index greater than 50% was present in all patients with dysthyroid optic neuropathy. This study suggests that patients with thyroid eye disease with enlarged superior ophthalmic vein and increased extraocular muscle index are more likely to have concomitant optic neuropathy.

Interactions between visceral afferent signaling and stimulus processing

Directory of Open Access Journals (Sweden)

Hugo D Critchley

2015-08-01

Full Text Available Visceral afferent signals to the brain influence thoughts, feelings and behaviour. Here we highlight the findings of a set of empirical investigations in humans concerning body-mind interaction that focus on how feedback from states of autonomic arousal shapes cognition and emotion. There is a longstanding debate regarding the contribution of the body, to mental processes. Recent theoretical models broadly acknowledge the role of (autonomically-mediated physiological arousal to emotional, social and motivational behaviours, yet the underlying mechanisms are only partially characterized. Neuroimaging is overcoming this shortfall; first, by demonstrating correlations between autonomic change and discrete patterns of evoked, and task-independent, neural activity; second, by mapping the central consequences of clinical perturbations in autonomic response and; third, by probing how dynamic fluctuations in peripheral autonomic state are integrated with perceptual, cognitive and emotional processes. Building on the notion that an important source of the brain’s representation of physiological arousal is derived from afferent information from arterial baroreceptors, we have exploited the phasic nature of these signals to show their differential contribution to the processing of emotionally-salient stimuli. This recent work highlights the facilitation at neural and behavioral levels of fear and threat processing that contrasts with the more established observations of the inhibition of central pain processing during baroreceptors activation. The implications of this body-brain-mind axis are discussed.

Primary afferent terminal sprouting after a cervical dorsal rootlet section in the macaque monkey.

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Darian-Smith, Corinna

2004-03-01

We examined the role of primary afferent neurons in the somatosensory cortical "reactivation" that occurs after a localized cervical dorsal root lesion (Darian-Smith and Brown [2000] Nat. Neurosci. 3:476-481). After section of the dorsal rootlets that enervate the macaque's thumb and index finger (segments C6-C8), the cortical representation of these digits was initially silenced but then re-emerged for these same digits over 2-4 postlesion months. Cortical reactivation was accompanied by the emergence of physiologically detectable input from these same digits within dorsal rootlets bordering the lesion site. We investigated whether central axonal sprouting of primary afferents spared by the rhizotomy could mediate this cortical reactivation. The cortical representation of the hand was mapped electrophysiologically 15-25 weeks after the dorsal rootlet section to define this reactivation. Cholera toxin subunit B conjugated to horseradish peroxidase was then injected into the thumb and index finger pads bilaterally to label the central terminals of any neurons that innervated these digits. Primary afferent terminal proliferation was assessed in the spinal dorsal horn and cuneate nucleus at 7 days and 15-25 postlesion weeks. Labeled terminal bouton distributions were reconstructed and the "lesion" and control sides compared within each monkey. Distributions were significantly larger on the side of the lesion in the dorsal horn and cuneate nucleus at 15-25 weeks after the dorsal rootlet section, than those mapped only 7 days postlesion. Our results provide direct evidence for localized sprouting of spared (uninjured) primary afferent terminals in the dorsal horn and cuneate nucleus after a restricted dorsal root injury. Copyright 2004 Wiley-Liss, Inc.

Decoding tactile afferent activity to obtain an estimate of instantaneous force and torque applied to the fingerpad

Science.gov (United States)

Birznieks, Ingvars; Redmond, Stephen J.

2015-01-01

Dexterous manipulation is not possible without sensory information about object properties and manipulative forces. Fundamental neuroscience has been unable to demonstrate how information about multiple stimulus parameters may be continuously extracted, concurrently, from a population of tactile afferents. This is the first study to demonstrate this, using spike trains recorded from tactile afferents innervating the monkey fingerpad. A multiple-regression model, requiring no a priori knowledge of stimulus-onset times or stimulus combination, was developed to obtain continuous estimates of instantaneous force and torque. The stimuli consisted of a normal-force ramp (to a plateau of 1.8, 2.2, or 2.5 N), on top of which −3.5, −2.0, 0, +2.0, or +3.5 mNm torque was applied about the normal to the skin surface. The model inputs were sliding windows of binned spike counts recorded from each afferent. Models were trained and tested by 15-fold cross-validation to estimate instantaneous normal force and torque over the entire stimulation period. With the use of the spike trains from 58 slow-adapting type I and 25 fast-adapting type I afferents, the instantaneous normal force and torque could be estimated with small error. This study demonstrated that instantaneous force and torque parameters could be reliably extracted from a small number of tactile afferent responses in a real-time fashion with stimulus combinations that the model had not been exposed to during training. Analysis of the model weights may reveal how interactions between stimulus parameters could be disentangled for complex population responses and could be used to test neurophysiologically relevant hypotheses about encoding mechanisms. PMID:25948866

Persistent pain after spinal cord injury is maintained by primary afferent activity.

Science.gov (United States)

Yang, Qing; Wu, Zizhen; Hadden, Julia K; Odem, Max A; Zuo, Yan; Crook, Robyn J; Frost, Jeffrey A; Walters, Edgar T

2014-08-06

Chronic pain caused by insults to the CNS (central neuropathic pain) is widely assumed to be maintained exclusively by central mechanisms. However, chronic hyperexcitablility occurs in primary nociceptors after spinal cord injury (SCI), suggesting that SCI pain also depends upon continuing activity of peripheral sensory neurons. The present study in rats (Rattus norvegicus) found persistent upregulation after SCI of protein, but not mRNA, for a voltage-gated Na(+) channel, Nav1.8, that is expressed almost exclusively in primary afferent neurons. Selectively knocking down Nav1.8 after SCI suppressed spontaneous activity in dissociated dorsal root ganglion neurons, reversed hypersensitivity of hindlimb withdrawal reflexes, and reduced ongoing pain assessed by a conditioned place preference test. These results show that activity in primary afferent neurons contributes to ongoing SCI pain. Copyright © 2014 the authors 0270-6474/14/3410765-05$15.00/0.

Muscle activation described with a differential equation model for large ensembles of locally coupled molecular motors.

Science.gov (United States)

Walcott, Sam

2014-10-01

Molecular motors, by turning chemical energy into mechanical work, are responsible for active cellular processes. Often groups of these motors work together to perform their biological role. Motors in an ensemble are coupled and exhibit complex emergent behavior. Although large motor ensembles can be modeled with partial differential equations (PDEs) by assuming that molecules function independently of their neighbors, this assumption is violated when motors are coupled locally. It is therefore unclear how to describe the ensemble behavior of the locally coupled motors responsible for biological processes such as calcium-dependent skeletal muscle activation. Here we develop a theory to describe locally coupled motor ensembles and apply the theory to skeletal muscle activation. The central idea is that a muscle filament can be divided into two phases: an active and an inactive phase. Dynamic changes in the relative size of these phases are described by a set of linear ordinary differential equations (ODEs). As the dynamics of the active phase are described by PDEs, muscle activation is governed by a set of coupled ODEs and PDEs, building on previous PDE models. With comparison to Monte Carlo simulations, we demonstrate that the theory captures the behavior of locally coupled ensembles. The theory also plausibly describes and predicts muscle experiments from molecular to whole muscle scales, suggesting that a micro- to macroscale muscle model is within reach.

Rates of ubiquitin conjugation increase when muscles atrophy, largely through activation of the N-end rule pathway

Science.gov (United States)

Solomon, V.; Baracos, V.; Sarraf, P.; Goldberg, A. L.

1998-01-01

The rapid loss of muscle mass that accompanies many disease states, such as cancer or sepsis, is primarily a result of increased protein breakdown in muscle, and several observations have suggested an activation of the ubiquitin-proteasome system. Accordingly, in extracts of atrophying muscles from tumor-bearing or septic rats, rates of 125I-ubiquitin conjugation to endogenous proteins were found to be higher than in control extracts. On the other hand, in extracts of muscles from hypothyroid rats, where overall proteolysis is reduced below normal, the conjugation of 125I-ubiquitin to soluble proteins decreased by 50%, and treatment with triiodothyronine (T3) restored ubiquitination to control levels. Surprisingly, the N-end rule pathway, which selectively degrades proteins with basic or large hydrophobic N-terminal residues, was found to be responsible for most of these changes in ubiquitin conjugation. Competitive inhibitors of this pathway that specifically block the ubiquitin ligase, E3alpha, suppressed most of the increased ubiquitin conjugation in the muscle extracts from tumor-bearing and septic rats. These inhibitors also suppressed ubiquitination in normal extracts toward levels in hypothyroid extracts, which showed little E3alpha-dependent ubiquitination. Thus, the inhibitors eliminated most of the differences in ubiquitination under these different pathological conditions. Moreover, 125I-lysozyme, a model N-end rule substrate, was ubiquitinated more rapidly in extracts from tumor-bearing and septic rats, and more slowly in those from hypothyroid rats, than in controls. Thus, the rate of ubiquitin conjugation increases in atrophying muscles, and these hormone- and cytokine-dependent responses are in large part due to activation of the N-end rule pathway.

Afferent Neural Feedback Overrides the Modulating Effects of Arousal, Hypercapnia and Hypoxemia on Neonatal Cardio-respiratory Control.

Science.gov (United States)

Lumb, Kathleen J; Schneider, Jennifer M; Ibrahim, Thowfique; Rigaux, Anita; Hasan, Shabih U

2018-04-20

Evidence at whole animal, organ-system, and cellular and molecular levels suggests that afferent volume feedback is critical for establishment of adequate ventilation at birth. Due to the irreversible nature of vagal ablation studies to date, it was difficult to quantify the roles of afferent volume input, arousal and changes in blood gas tensions on neonatal respiratory control. During reversible perineural vagal block, profound apneas, and hypoxemia and hypercarbia were observed necessitating termination of perineural blockade. Respiratory depression and apneas were independent of the sleep states. We demonstrate that profound apneas and life-threatening respiratory failure in vagally denervated animals do not result from lack of arousal or hypoxemia. Change in sleep state and concomitant respiratory depression result from lack of afferent volume feedback, which appears to be critical for the maintenance of normal breathing patterns and adequate gas exchange during the early postnatal period. Afferent volume feedback plays a vital role in neonatal respiratory control. Mechanisms for the profound respiratory depression and life-threatening apneas observed in vagally denervated neonatal animals remain unclear. We investigated the roles of sleep states, hypoxic-hypercapnia and afferent volume feedback on respiratory depression using reversible perineural vagal block during early postnatal period. Seven lambs were instrumented during the first 48h of life to record/analyze sleep states, diaphragmatic electromyograph, arterial blood gas tensions, systemic arterial blood pressure and rectal temperature. Perineural cuffs were placed around the vagi to attain reversible blockade. Post-operatively, during the awake state, both vagi were blocked using 2% xylocaine for up to 30 minutes. Compared with baseline values, pHa, PaO 2 and SaO 2 decreased and PaCO 2 increased during perineural blockade (P Respiratory depression and apneas were independent of sleep states. This

Glucose-dependent trafficking of 5-HT3 receptors in rat gastrointestinal vagal afferent neurons

Science.gov (United States)

Babic, Tanja; Troy, Amanda E; Fortna, Samuel R; Browning, Kirsteen N

2012-01-01

Background Intestinal glucose induces gastric relaxation via vagally mediated sensory-motor reflexes. Glucose can alter the activity of gastrointestinal (GI) vagal afferent (sensory) neurons directly, via closure of ATP-sensitive potassium channels, as well as indirectly, via the release of 5-hydroxytryptamine (5-HT) from mucosal enteroendocrine cells. We hypothesized that glucose may also be able to modulate the ability of GI vagal afferent neurons to respond to the released 5-HT, via regulation of neuronal 5-HT3 receptors. Methods Whole cell patch clamp recordings were made from acutely dissociated GI-projecting vagal afferent neurons exposed to equiosmolar Krebs’ solution containing different concentrations of D-glucose (1.25–20mM) and the response to picospritz application of 5-HT assessed. The distribution of 5-HT3 receptors in neurons exposed to different glucose concentrations was also assessed immunohistochemically. Key Results Increasing or decreasing extracellular D-glucose concentration increased or decreased, respectively, the 5-HT-induced inward current as well as the proportion of 5-HT3 receptors associated with the neuronal membrane. These responses were blocked by the Golgi-disrupting agent Brefeldin-A (5µM) suggesting involvement of a protein trafficking pathway. Furthermore, L-glucose did not mimic the response of D-glucose implying that metabolic events downstream of neuronal glucose uptake are required in order to observe the modulation of 5-HT3 receptor mediated responses. Conclusions & Inferences These results suggest that, in addition to inducing the release of 5-HT from enterochromaffin cells, glucose may also increase the ability of GI vagal sensory neurons to respond to the released 5-HT, providing a means by which the vagal afferent signal can be amplified or prolonged. PMID:22845622

Dural afferents express acid-sensing ion channels: a role for decreased meningeal pH in migraine headache.

Science.gov (United States)

Yan, Jin; Edelmayer, Rebecca M; Wei, Xiaomei; De Felice, Milena; Porreca, Frank; Dussor, Gregory

2011-01-01

Migraine headache is one of the most common neurological disorders. The pathological conditions that directly initiate afferent pain signaling are poorly understood. In trigeminal neurons retrogradely labeled from the cranial meninges, we have recorded pH-evoked currents using whole-cell patch-clamp electrophysiology. Approximately 80% of dural-afferent neurons responded to a pH 6.0 application with a rapidly activating and rapidly desensitizing ASIC-like current that often exceeded 20nA in amplitude. Inward currents were observed in response to a wide range of pH values and 30% of the neurons exhibited inward currents at pH 7.1. These currents led to action potentials in 53%, 30% and 7% of the dural afferents at pH 6.8, 6.9 and 7.0, respectively. Small decreases in extracellular pH were also able to generate sustained window currents and sustained membrane depolarizations. Amiloride, a non-specific blocker of ASIC channels, inhibited the peak currents evoked upon application of decreased pH while no inhibition was observed upon application of TRPV1 antagonists. The desensitization time constant of pH 6.0-evoked currents in the majority of dural afferents was less than 500ms which is consistent with that reported for ASIC3 homomeric or heteromeric channels. Finally, application of pH 5.0 synthetic-interstitial fluid to the dura produced significant decreases in facial and hind-paw withdrawal threshold, an effect blocked by amiloride but not TRPV1 antagonists, suggesting that ASIC activation produces migraine-related behavior in vivo. These data provide a cellular mechanism by which decreased pH in the meninges following ischemic or inflammatory events directly excites afferent pain-sensing neurons potentially contributing to migraine headache. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

New perspectives concerning feedback influences on cardiorespiratory control during rhythmic exercise and on exercise performance.

Science.gov (United States)

Dempsey, Jerome A

2012-09-01

The cardioaccelerator and ventilatory responses to rhythmic exercise in the human are commonly viewed as being mediated predominantly via feedforward 'central command' mechanisms, with contributions from locomotor muscle afferents to the sympathetically mediated pressor response. We have assessed the relative contributions of three types of feedback afferents on the cardiorespiratory response to voluntary, rhythmic exercise by inhibiting their normal 'tonic' activity in healthy animals and humans and in chronic heart failure. Transient inhibition of the carotid chemoreceptors during moderate intensity exercise reduced muscle sympathetic nerve activity (MSNA) and increased limb vascular conductance and blood flow; and reducing the normal level of respiratory muscle work during heavier intensity exercise increased limb vascular conductance and blood flow. These cardiorespiratory effects were prevented via ganglionic blockade and were enhanced in chronic heart failure and in hypoxia. Blockade of μ opioid sensitive locomotor muscle afferents, with preservation of central motor output via intrathecal fentanyl: (a) reduced the mean arterial blood pressure (MAP), heart rate and ventilatory responses to all steady state exercise intensities; and (b) during sustained high intensity exercise, reduced O(2) transport, increased central motor output and end-exercise muscle fatigue and reduced endurance performance. We propose that these three afferent reflexes - probably acting in concert with feedforward central command - contribute significantly to preserving O(2) transport to locomotor and to respiratory muscles during exercise. Locomotor muscle afferents also appear to provide feedback concerning the metabolic state of the muscle to influence central motor output, thereby limiting peripheral fatigue development.

Afferent projections to the different medial amygdala subdivisions: a retrograde tracing study in the mouse.

Science.gov (United States)

Cádiz-Moretti, Bernardita; Otero-García, Marcos; Martínez-García, Fernando; Lanuza, Enrique

2016-03-01

The medial amygdaloid nucleus (Me) is a key node in the socio-sexual brain, composed of anterior (MeA), posteroventral (MePV) and posterodorsal (MePD) subdivisions. These subdivisions have been suggested to play a different role in reproductive and defensive behaviours. In the present work we analyse the afferents of the three Me subdivisions using restricted injections of fluorogold in female outbred CD1 mice. The results reveal that the MeA, MePV and MePD share a common pattern of afferents, with some differences in the density of retrograde labelling in several nuclei. Common afferents to Me subdivisions include: the accessory olfactory bulbs, piriform cortex and endopiriform nucleus, chemosensory amygdala (receiving direct inputs from the olfactory bulbs), posterior part of the medial bed nucleus of the stria terminalis (BSTM), CA1 in the ventral hippocampus and posterior intralaminar thalamus. Minor projections originate from the basolateral amygdala and amygdalo-hippocampal area, septum, ventral striatum, several allocortical and periallocortical areas, claustrum, several hypothalamic structures, raphe and parabrachial complex. MeA and MePV share minor inputs from the frontal cortex (medial orbital, prelimbic, infralimbic and dorsal peduncular cortices), but differ in the lack of main olfactory projections to the MePV. By contrast, the MePD receives preferential projections from the rostral accessory olfactory bulb, the posteromedial BSTM and the ventral premammillary nucleus. In summary, the common pattern of afferents to the Me subdivisions and their interconnections suggest that they play cooperative instead of differential roles in the various behaviours (e.g., sociosexual, defensive) in which the Me has been shown to be involved.

F response and H reflex analysis of physiological unity of gravity and antigravity muscles in man.

Science.gov (United States)

García, H A; Fisher, M A

1977-01-01

Observational differences between reflex (H reflex) and antidromic (F response) activation of segmental motoneurons by a peripheral electrical stimulus are described. In contrast to H reflexes, the percentage of F responses found after a series of stimuli is directly related to the pick-up field of the recording electrode consistent with this response being due to the variable activation of a small fraction of the available motoneuron pool. Despite the differing physiological mechanisms, both F responses and H reflexes can be used to demonstrate similar relative "central excitatory states" for antigravity muscles (i.e. extensors in the lower extremity and flexors in the upper extremity) and their antagonist gravity muscles. H reflexes were elicited not only in their usual location in certain antigravity muscles but also in unusual locations by length/tension changes in agonist and antagonist groups as well as by passive stretch. The data argue for the physiological unity of similarly acting gravity and antigravity muscles as well as supporting a meaningful role of group II afferents in normal segmental motoneuron pool excitability.

Na+-independent, nifedipine-resistant rat afferent arteriolar Ca2+ responses to noradrenaline

DEFF Research Database (Denmark)

Salomonsson, Max; Braunstein, Thomas Hartig; von Holstein-Rathlou, Niels-Henrik

2010-01-01

Abstract Aim: In rat afferent arterioles we investigated the role of Na(+) entry in noradrenaline (NA)-induced depolarization and voltage-dependent Ca(2+) entry together with the importance of the transient receptor potential channel (TRPC) subfamily for non-voltage-dependent Ca(2+) entry. Methods...

Chicken (Gallus domesticus) inner ear afferents

Science.gov (United States)

Hara, H.; Chen, X.; Hartsfield, J. F.; Hara, J.; Martin, D.; Fermin, C. D.

1998-01-01

Neurons from the vestibular (VG) and the statoacoustic (SAG) ganglion of the chick (Gallus domesticus) were evaluated histologically and morphometrically. Embryos at stages 34 (E8 days), 39 (E13 days) and 44 (E18 days) were sacrificed and temporal bones microdissected. Specimens were embedded in JB-4 methacrylate plastic, and stained with a mixture of 0.2% toluidine blue (TB) and 0.1% basic Fuschin in 25% ethanol or with a mixture of 2% TB and 1% paraphenylenediamine (PDA) for axon and myelin measurement study. Images of the VIIIth nerve were produced by a V150 (R) color imaging system and the contour of 200-300 neuronal bodies (perikarya) was traced directly on a video screen with a mouse in real time. The cross-sectional area of VG perikarya was 67.29 micrometers2 at stage 34 (E8), 128.46 micrometers2 at stage 39 (E13) and 275.85 micrometers2 at stage 44 (E18). The cross-sectional area of SAG perikarya was 62.44 micrometers2 at stage 34 (E8), 102.05 micrometers2 at stage 39 (E13) and 165.02 micrometers2 at stage 44 (E18). A significant cross-sectional area increase of the VG perikarya between stage 39 (E13) and stage 44 (E18) was determined. We randomly measured the cross-sectional area of myelin and axoplasm of hatchling afferent nerves, and found a correspondence between axoplasmic and myelin cross-sectional area in the utricular, saccular and semicircular canal nerve branches of the nerve. The results suggest that the period between stage 34 (E8) and 39 (E13) is a critical period for afferent neuronal development. Physiological and behavioral vestibular properties of developing and maturing hatchlings may change accordingly. The results compliment previous work by other investigators and provide valuable anatomical measures useful to correlate physiological data obtained from stimulation of the whole nerve or its parts.

Force sensor in simulated skin and neural model mimic tactile SAI afferent spiking response to ramp and hold stimuli.

Science.gov (United States)

Kim, Elmer K; Wellnitz, Scott A; Bourdon, Sarah M; Lumpkin, Ellen A; Gerling, Gregory J

2012-07-23

The next generation of prosthetic limbs will restore sensory feedback to the nervous system by mimicking how skin mechanoreceptors, innervated by afferents, produce trains of action potentials in response to compressive stimuli. Prior work has addressed building sensors within skin substitutes for robotics, modeling skin mechanics and neural dynamics of mechanotransduction, and predicting response timing of action potentials for vibration. The effort here is unique because it accounts for skin elasticity by measuring force within simulated skin, utilizes few free model parameters for parsimony, and separates parameter fitting and model validation. Additionally, the ramp-and-hold, sustained stimuli used in this work capture the essential features of the everyday task of contacting and holding an object. This systems integration effort computationally replicates the neural firing behavior for a slowly adapting type I (SAI) afferent in its temporally varying response to both intensity and rate of indentation force by combining a physical force sensor, housed in a skin-like substrate, with a mathematical model of neuronal spiking, the leaky integrate-and-fire. Comparison experiments were then conducted using ramp-and-hold stimuli on both the spiking-sensor model and mouse SAI afferents. The model parameters were iteratively fit against recorded SAI interspike intervals (ISI) before validating the model to assess its performance. Model-predicted spike firing compares favorably with that observed for single SAI afferents. As indentation magnitude increases (1.2, 1.3, to 1.4 mm), mean ISI decreases from 98.81 ± 24.73, 54.52 ± 6.94, to 41.11 ± 6.11 ms. Moreover, as rate of ramp-up increases, ISI during ramp-up decreases from 21.85 ± 5.33, 19.98 ± 3.10, to 15.42 ± 2.41 ms. Considering first spikes, the predicted latencies exhibited a decreasing trend as stimulus rate increased, as is observed in afferent recordings. Finally, the SAI afferent's characteristic response

Rimonabant induced anorexia in rodents is not mediated by vagal or sympathetic gut afferents

DEFF Research Database (Denmark)

Madsen, Andreas Nygaard; Jelsing, Jacob; van de Wall, Esther H E M

2009-01-01

The selective CB1 receptor antagonist rimonabant is a novel weight control agent. Although CB1 receptors and binding sites are present in both the rodent central and peripheral nervous systems, including the afferent vagus nerve, the role of gut afferents in mediating anorexia following CB1R...... blockade is still debated. In the present study we examined rimonabant-induced anorexia in male C57BL/6J mice with subdiaphragmatic vagotomy (VGX) as well as in male Sprague-Dawley rats subjected to either subdiaphragmatic vagal deafferentation (SDA) alone or in combination with a complete celiac...... system, are required for rimonabant to inhibit food intake leading to the hypothesis that centrally located CB1 receptors are the prime mediators of rimonabant-induced anorexia....

Characterization of spinal afferent neurons projecting to different chambers of the rat heart.

Science.gov (United States)

Guić, Maja Marinović; Kosta, Vana; Aljinović, Jure; Sapunar, Damir; Grković, Ivica

2010-01-29

The pattern of distribution of spinal afferent neurons (among dorsal root ganglia-DRGs) that project to anatomically and functionally different chambers of the rat heart, as well as their morphological and neurochemical characteristics were investigated. Retrograde tracing using a patch loaded with Fast blue (FB) was applied to all four chambers of the rat heart and labeled cardiac spinal afferents were characterized by using three neurochemical markers. The majority of cardiac projecting neurons were found from T1 to T4 DRGs, whereas the peak was at T2 DRG. There was no difference in the total number of FB-labeled neurons located in ipsilateral and contralateral DRGs regardless of the chambers marked with the patch. However, significantly more FB-labeled neurons projected to the ventricles compared to the atria (859 vs. 715). The proportion of isolectin B(4) binding in FB-labeled neurons was equal among all neurons projecting to different heart chambers (2.4%). Neurofilament 200 positivity was found in greater proportions in DRG neurons projecting to the left side of the heart, whereas calretinin-immunoreactivity was mostly represented in neurons projecting to the left atrium. Spinal afferent neurons projecting to different chambers of the rat heart exhibit a variety of neurochemical phenotypes depending on binding capacity for isolectin B(4) and immunoreactivity for neurofilament 200 and calretinin, and thus represent important baseline data for future studies. (c) 2009 Elsevier Ireland Ltd. All rights reserved.

Afferent and efferent projections of the anterior cortical amygdaloid nucleus in the mouse.

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Cádiz-Moretti, Bernardita; Abellán-Álvaro, María; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

2017-09-01

The anterior cortical amygdaloid nucleus (ACo) is a chemosensory area of the cortical amygdala that receives afferent projections from both the main and accessory olfactory bulbs. The role of this structure is unknown, partially due to a lack of knowledge of its connectivity. In this work, we describe the pattern of afferent and efferent projections of the ACo by using fluorogold and biotinylated dextranamines as retrograde and anterograde tracers, respectively. The results show that the ACo is reciprocally connected with the olfactory system and basal forebrain, as well as with the chemosensory and basomedial amygdala. In addition, it receives dense projections from the midline and posterior intralaminar thalamus, and moderate projections from the posterior bed nucleus of the stria terminalis, mesocortical structures and the hippocampal formation. Remarkably, the ACo projects moderately to the central nuclei of the amygdala and anterior bed nucleus of the stria terminalis, and densely to the lateral hypothalamus. Finally, minor connections are present with some midbrain and brainstem structures. The afferent projections of the ACo indicate that this nucleus might play a role in emotional learning involving chemosensory stimuli, such as olfactory fear conditioning. The efferent projections confirm this view and, given its direct output to the medial part of the central amygdala and the hypothalamic 'aggression area', suggest that the ACo can initiate defensive and aggressive responses elicited by olfactory or, to a lesser extent, vomeronasal stimuli. © 2017 Wiley Periodicals, Inc.

Immobilization induces changes in presynaptic control of group Ia afferents in healthy humans

DEFF Research Database (Denmark)

Jensen, Jesper Lundbye; Nielsen, Jens Bo

2008-01-01

immobilized the left foot and ankle joint for 2 weeks in 12 able-bodied subjects. Disynaptic reciprocal inhibition of soleus (SOL) motoneurones and presynaptic control of SOL group Ia afferents was measured before and after the immobilization as well as following 2 weeks of recovery. Following immobilization...... maximal voluntary plantar- and dorsiflexion torque (MVC) was significantly reduced and the maximal SOL H-reflex amplitude increased with no changes in Mmax. Decreased presynaptic inhibition of the Ia afferents likely contributed to the increase of the H-reflex size, since we observed a significant...... decrease in the long-latency depression of the SOL H-reflex evoked by peroneal nerve stimulation (D2 inhibition) and an increase in the size of the monosynaptic Ia facilitation of the SOL H-reflex evoked by femoral nerve stimulation. These two measures provide independent evidence of changes in presynaptic...

Middle cerebral artery blood velocity depends on cardiac output during exercise with a large muscle mass

NARCIS (Netherlands)

Ide, K.; Pott, F.; van Lieshout, J. J.; Secher, N. H.

1998-01-01

We tested the hypothesis that pharmacological reduction of the increase in cardiac output during dynamic exercise with a large muscle mass would influence the cerebral blood velocity/perfusion. We studied the relationship between changes in cerebral blood velocity (transcranial Doppler), rectus

Reflexes in the shoulder muscles elicited from the human coracoacromial ligament.

Science.gov (United States)

Diederichsen, Louise Pyndt; Nørregaard, Jesper; Krogsgaard, Michael; Fischer-Rasmussen, Torsten; Dyhre-Poulsen, Poul

2004-09-01

Morphological studies have demonstrated mechanoreceptors in the capsuloligamentous structures of the shoulder joint, however knowledge of the role these joint receptors play in the control of shoulder stability is limited. We therefore investigated the effect of electrically induced afferent activity from mechanoreceptors in the coracoacromial ligament (CAL) on the activity of voluntary activated shoulder muscles in healthy humans. In study I, wire electrodes, for electrical stimulation, were inserted into the CAL in eight normal shoulders. In study II, a needle electrode was inserted into the CAL in seven normal shoulders. Electric activity was recorded from eight shoulder muscles by surface and intramuscular electrodes. During isometric contractions, electrical stimulation was applied to the CAL at two different stimulus intensities, a weak stimulus (stim-1) and a stronger stimulus (stim-2). In both experiments, electrical stimulation of the CAL elicited a general inhibition in the voluntary activated shoulder muscles. In study I the average latencies (mean+/-SE) of the muscular inhibition were 66+/-4 ms (stim-1) and 62+/-4 ms (stim-2) during isometric flexion and 73+/-3 ms (stim-1) and 73+/-5 ms (stim-2) during isometric extension. In study II the average latency (mean+/-SE) of the response was 66+/-4 ms (stim-1) during isometric flexion. Our results demonstrated a response, probably of reflex origin, from mechanoreceptors in the CAL to the shoulder muscles. The existence of this synaptic connection between mechanoreceptors in CAL and the shoulder muscles suggest a role of these receptors in muscle coordination and in the functional joint stability.

Distribution of TTX-sensitive voltage-gated sodium channels in primary sensory endings of mammalian muscle spindles.

Science.gov (United States)

Carrasco, Dario I; Vincent, Jacob A; Cope, Timothy C

2017-04-01

Knowledge of the molecular mechanisms underlying signaling of mechanical stimuli by muscle spindles remains incomplete. In particular, the ionic conductances that sustain tonic firing during static muscle stretch are unknown. We hypothesized that tonic firing by spindle afferents depends on sodium persistent inward current (INaP) and tested for the necessary presence of the appropriate voltage-gated sodium (NaV) channels in primary sensory endings. The NaV 1.6 isoform was selected for both its capacity to produce INaP and for its presence in other mechanosensors that fire tonically. The present study shows that NaV 1.6 immunoreactivity (IR) is concentrated in heminodes, presumably where tonic firing is generated, and we were surprised to find NaV 1.6 IR strongly expressed also in the sensory terminals, where mechanotransduction occurs. This spatial pattern of NaV 1.6 IR distribution was consistent for three mammalian species (rat, cat, and mouse), as was tonic firing by primary spindle afferents. These findings meet some of the conditions needed to establish participation of INaP in tonic firing by primary sensory endings. The study was extended to two additional NaV isoforms, selected for their sensitivity to TTX, excluding TTX-resistant NaV channels, which alone are insufficient to support firing by primary spindle endings. Positive immunoreactivity was found for NaV 1.1 , predominantly in sensory terminals together with NaV 1.6 and for NaV 1.7 , mainly in preterminal axons. Differential distribution in primary sensory endings suggests specialized roles for these three NaV isoforms in the process of mechanosensory signaling by muscle spindles. NEW & NOTEWORTHY The molecular mechanisms underlying mechanosensory signaling responsible for proprioceptive functions are not completely elucidated. This study provides the first evidence that voltage-gated sodium channels (NaVs) are expressed in the spindle primary sensory ending, where NaVs are found at every site

Neuromorphic meets neuromechanics, part I: the methodology and implementation

Science.gov (United States)

Niu, Chuanxin M.; Jalaleddini, Kian; Sohn, Won Joon; Rocamora, John; Sanger, Terence D.; Valero-Cuevas, Francisco J.

2017-04-01

Objective: One goal of neuromorphic engineering is to create ‘realistic’ robotic systems that interact with the physical world by adopting neuromechanical principles from biology. Critical to this is the methodology to implement the spinal circuitry responsible for the behavior of afferented muscles. At its core, muscle afferentation is the closed-loop behavior arising from the interactions among populations of muscle spindle afferents, alpha and gamma motoneurons, and muscle fibers to enable useful behaviors. Approach. We used programmable very- large-scale-circuit (VLSI) hardware to implement simple models of spiking neurons, skeletal muscles, muscle spindle proprioceptors, alpha-motoneuron recruitment, gamma motoneuron control of spindle sensitivity, and the monosynaptic circuitry connecting them. This multi-scale system of populations of spiking neurons emulated the physiological properties of a pair of antagonistic afferented mammalian muscles (each simulated by 1024 alpha- and gamma-motoneurones) acting on a joint via long tendons. Main results. This integrated system was able to maintain a joint angle, and reproduced stretch reflex responses even when driving the nonlinear biomechanics of an actual cadaveric finger. Moreover, this system allowed us to explore numerous values and combinations of gamma-static and gamma-dynamic gains when driving a robotic finger, some of which replicated some human pathological conditions. Lastly, we explored the behavioral consequences of adopting three alternative models of isometric muscle force production. We found that the dynamic responses to rate-coded spike trains produce force ramps that can be very sensitive to tendon elasticity, especially at high force output. Significance. Our methodology produced, to our knowledge, the first example of an autonomous, multi-scale, neuromorphic, neuromechanical system capable of creating realistic reflex behavior in cadaveric fingers. This research platform allows us to explore

Anodal Direct Current Stimulation of the Cerebellum Reduces Cerebellar Brain Inhibition but Does Not Influence Afferent Input from the Hand or Face in Healthy Adults.

Science.gov (United States)

Doeltgen, Sebastian H; Young, Jessica; Bradnam, Lynley V

2016-08-01

The cerebellum controls descending motor commands by outputs to primary motor cortex (M1) and the brainstem in response to sensory feedback. The cerebellum may also modulate afferent input en route to M1 and the brainstem. The objective of this study is to determine if anodal transcranial direct current stimulation (tDCS) to the cerebellum influences cerebellar brain inhibition (CBI), short afferent inhibition (SAI) and trigeminal reflexes (TRs) in healthy adults. Data from two studies evaluating effects of cerebellar anodal and sham tDCS are presented. The first study used a twin coil transcranial magnetic stimulation (TMS) protocol to investigate CBI and combined TMS and cutaneous stimulation of the digit to assess SAI. The second study evaluated effects on trigemino-cervical and trigemino-masseter reflexes using peripheral nerve stimulation of the face. Fourteen right-handed healthy adults participated in experiment 1. CBI was observed at baseline and was reduced by anodal cerebellar DCS only (P < 0.01). There was SAI at interstimulus intervals of 25 and 30 ms at baseline (both P < 0.0001), but cerebellar tDCS had no effect. Thirteen right-handed healthy adults participated in experiment 2. Inhibitory reflexes were evoked in the ipsilateral masseter and sternocleidomastoid muscles. There was no effect of cerebellar DCS on either reflex. Anodal DCS reduced CBI but did not change SAI or TRs in healthy adults. These results require confirmation in individuals with neurological impairment.

Prostaglandin potentiates 5-HT responses in stomach and ileum innervating visceral afferent sensory neurons

Energy Technology Data Exchange (ETDEWEB)

Kim, Sojin; Jin, Zhenhua; Lee, Goeun [Department of Physiology, School of Medicine, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Park, Yong Seek; Park, Cheung-Seog [Department of Microbiology, School of Medicine, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Jin, Young-Ho, E-mail: jinyh@khu.ac.kr [Department of Physiology, School of Medicine, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

2015-01-02

Highlights: • Prostaglandin E2 (PGE{sub 2}) effect was tested on visceral afferent neurons. • PGE{sub 2} did not evoke response but potentiated serotonin (5-HT) currents up to 167%. • PGE{sub 2}-induced potentiation was blocked by E-prostanoid type 4 receptors antagonist. • PGE{sub 2} effect on 5-HT response was also blocked by protein kinase A inhibitor KT5720. • Thus, PGE{sub 2} modulate visceral afferent neurons via synergistic signaling with 5-HT. - Abstract: Gastrointestinal disorder is a common symptom induced by diverse pathophysiological conditions that include food tolerance, chemotherapy, and irradiation for therapy. Prostaglandin E{sub 2} (PGE{sub 2}) level increase was often reported during gastrointestinal disorder and prostaglandin synthetase inhibitors has been used for ameliorate the symptoms. Exogenous administration of PGE{sub 2} induces gastrointestinal disorder, however, the mechanism of action is not known. Therefore, we tested PGE{sub 2} effect on visceral afferent sensory neurons of the rat. Interestingly, PGE{sub 2} itself did not evoked any response but enhanced serotonin (5-HT)-evoked currents up to 167% of the control level. The augmented 5-HT responses were completely inhibited by a 5-HT type 3 receptor antagonist, ondansetron. The PGE{sub 2}-induced potentiation were blocked by a selective E-prostanoid type4 (EP{sub 4}) receptors antagonist, L-161,982, but type1 and 2 receptor antagonist AH6809 has no effect. A membrane permeable protein kinase A (PKA) inhibitor, KT5720 also inhibited PGE{sub 2} effects. PGE{sub 2} induced 5-HT current augmentation was observed on 15% and 21% of the stomach and ileum projecting neurons, respectively. Current results suggest a synergistic signaling in visceral afferent neurons underlying gastrointestinal disorder involving PGE{sub 2} potentiation of 5-HT currents. Our findings may open a possibility for screen a new type drugs with lower side effects than currently using steroidal prostaglandin

Effect of a muscle relaxant, chlorphenesin carbamate, on the spinal neurons of rats.

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Kurachi, M; Aihara, H

1984-09-01

The effects of chlorphenesin carbamate (CPC) and mephenesin on spinal neurons were investigated in spinal rats. CPC (50 mg/kg i.v.) inhibited the mono-(MSR) and poly-synaptic reflex (PSR), the latter being more susceptible than the former to CPC depression. Mephenesin also inhibited MSR and PSR, though the effects were short in duration. CPC had no effect on the dorsal root potential evoked by the stimulation of the dorsal root, while mephenesin reduced the dorsal root-dorsal root reflex. The excitability of motoneuron was reduced by the administration of CPC or mephenesin. The excitability of primary afferent terminal was unchanged by CPC, while it was inhibited by mephenesin. Neither CPC nor mephenesin influenced the field potential evoked by the dorsal root stimulation. Both CPC and mephenesin had no effect on the synaptic recovery. These results suggest that both CPC and mephenesin inhibit the firing of motoneurons by stabilizing the neuronal membrane, while mephenesin additionally suppresses the dorsal root reflex and the excitability of the primary afferent terminal. These inhibitory actions of CPC on spinal activities may contribute, at least partly, to its muscle relaxing action.

Evaluation of afferent pain pathways in adrenomyeloneuropathic patients.

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Yagüe, Sara; Veciana, Misericordia; Casasnovas, Carlos; Ruiz, Montserrat; Pedro, Jordi; Valls-Solé, Josep; Pujol, Aurora

2018-03-01

Patients with adrenomyeloneuropathy may have dysfunctions of visual, auditory, motor and somatosensory pathways. We thought on examining the nociceptive pathways by means of laser evoked potentials (LEPs), to obtain additional information on the pathophysiology of this condition. In 13 adrenomyeloneuropathic patients we examined LEPs to leg, arm and face stimulation. Normative data were obtained from 10 healthy subjects examined in the same experimental conditions. We also examined brainstem auditory evoked potentials (BAEPs), pattern reversal full-field visual evoked potentials (VEPs), motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs). Upper and lower limb MEPs and SEPs, as well as BAEPs, were abnormal in all patients, while VEPs were abnormal in 3 of them (23.1%). LEPs revealed abnormalities to stimulation of the face in 4 patients (30.7%), the forearm in 4 patients (30.7%) and the leg in 10 patients (76.9%). The pathologic process of adrenomyeloneuropathy is characterized by a preferential involvement of auditory, motor and somatosensory tracts and less severely of the visual and nociceptive pathways. This non-inflammatory distal axonopathy preferably damages large myelinated spinal tracts but there is also partial involvement of small myelinated fibres. LEPs studies can provide relevant information about afferent pain pathways involvement in adrenomyeloneuropathic patients. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Physiological properties of afferents to the rat cerebellum during normal development and after postnatal x irradiation

International Nuclear Information System (INIS)

Puro, D.G.

1975-01-01

The consequences of an altered cerebellar cortical development on afferent transmission and terminal organization were analyzed in adult rats which had received x irradiation to the cerebellum postnatally. Rats, anesthetized with 0.5 percent halothane, were studied in various ages from day 3 to adult. The ascending mossy and climbing fiber systems were activated by electrical stimulation of the limbs with needle electrodes. Stimulation of the motor cortex activated the descending climbing fiber pathways. Extracellular responses from cerebellar Purkinje cells were observed on an oscilloscope as poststimulus time histograms were constructed ''on-line''. Conclusions and assertions include: (1) Synaptogenesis between incoming afferent fibers and target neurons takes place early in cerebellar cortical development. (2) Mossy fiber transmission is mature before the bulk of cerebellar synaptogenesis occurs. (3) The ascending and descending components of the climbing fiber system mature, with respect to latency, in synchrony. (4) The terminal synaptic organization has little effect on the development of transmission characteristics in these afferent systems. (5) One possible mechanism by which an adult neural structure can have an abnormal synaptic organization is to maintain immature synaptic relationships due to the neonatal loss of interneurons

Loop myopexy with true muscle transplantation for very large angle heavy eye syndrome patient

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Jitendra Jethani

2015-01-01

Full Text Available A 42-year-old man presenting with complaints of squint for last 20 years. His visual acuity was 20/400 in right eye (RE and 20/30 in left eye (LE with glasses. His refraction was RE -16.75/-2.5 D cycl 180 and LE was -14.5/-1.5 D cycl 180. His axial length was 31.23 mm In RE and 29.72 mm in LE. On examination we found he had RE large esotropia with hypotropia measuring 130 pd base out and 40 pd base up in RE. A computerized tomography scan revealed that the superior rectus (SR was shifted nasally, and lateral rectus (LR was shifted inferiorly. A RE medial rectus (MR recession and LR resection with muscle transplantation on the MR was done. A loop myopexy was done to correct the path of the LR and SR. The patient had only 18 pd eso and 20 pd hypo on follow-up after 3 months. Loop myopexy in conjunction with muscle transplantation is a safe and effective procedure for large angle esotropia associated with heavy eye syndrome.

Effects of intra-articular hyaluronic acid injection on immunohistochemical characterization of joint afferents in a rat model of knee osteoarthritis.

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Ikeuchi, M; Izumi, M; Aso, K; Sugimura, N; Kato, T; Tani, T

2015-03-01

Intra-articular hyaluronic acid (HA) injection, known as viscosupplementation, is a widely used therapy for pain relief in knee osteoarthritis (OA). Long-term clinical efficacy of HA has been reported in spite of a relatively short residence time. Herein, we evaluated our hypothesis that intra-articular HA injection could reduce the OA-associated changes in joint afferents. OA was induced by intra-articular injection of mono-iodoacetate in rats. Animals in the OA + HA group were given three weekly intra-articular HA injections. Pain-related behaviours, including weight-bearing asymmetry and mechanical hyperalgesia of the paw, knee joint histology and immunohistochemistry of joint afferents identified by retrograde labelling, were compared between groups (naïve, OA and OA + HA). OA rats showed pain-related behaviours and up-regulation of pain-related neurochemical markers [calcitonin gene-related peptide (CGRP), tyrosine receptor kinase A (TrkA) and acid-sensing ion channel 3 (ASIC3)] in joint afferents. HA injections reduced not only the severity of OA and pain behaviours but also OA-associated neurochemical changes in joint afferents. The differences between OA and OA + HA were statistically significant in CGRP (61 ± 10% vs. 51 ± 10%; p = 0.0406) but not significant in TrkA (62 ± 10% vs. 54 ± 9%; p = 0.0878) and ASIC3 (38 ± 9% vs. 32 ± 8%; p = 0.3681). Intra-articular HA injections reduced the severity of OA, decreased mechanical hyperalgesia of the paw, but not weight-bearing asymmetry, and attenuated OA-associated up-regulation of CGRP, but not TrkA and ASIC3, in joint afferents. The modulatory effects of HA on joint afferents is one of the underlying mechanisms of the gap between HA residence time and duration of clinical efficacy. © 2014 European Pain Federation - EFIC®

Psychoactive bacteria Lactobacillus rhamnosus (JB-1) elicits rapid frequency facilitation in vagal afferents.

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Perez-Burgos, Azucena; Wang, Bingxian; Mao, Yu-Kang; Mistry, Bhavik; McVey Neufeld, Karen-Anne; Bienenstock, John; Kunze, Wolfgang

2013-01-15

Mounting evidence supports the influence of the gut microbiome on the local enteric nervous system and its effects on brain chemistry and relevant behavior. Vagal afferents are involved in some of these effects. We previously showed that ingestion of the probiotic bacterium Lactobacillus rhamnosus (JB-1) caused extensive neurochemical changes in the brain and behavior that were abrogated by prior vagotomy. Because information can be transmitted to the brain via primary afferents encoded as neuronal spike trains, our goal was to record those induced by JB-1 in vagal afferents in the mesenteric nerve bundle and thus determine the nature of the signals sent to the brain. Male Swiss Webster mice jejunal segments were cannulated ex vivo, and serosal and luminal compartments were perfused separately. Bacteria were added intraluminally. We found no evidence for translocation of labeled bacteria across the epithelium during the experiment. We recorded extracellular multi- and single-unit neuronal activity with glass suction pipettes. Within minutes of application, JB-1 increased the constitutive single- and multiunit firing rate of the mesenteric nerve bundle, but Lactobacillus salivarius (a negative control) or media alone were ineffective. JB-1 significantly augmented multiunit discharge responses to an intraluminal distension pressure of 31 hPa. Prior subdiaphragmatic vagotomy abolished all of the JB-1-evoked effects. This detailed exploration of the neuronal spike firing that encodes behavioral signaling to the brain may be useful to identify effective psychoactive bacteria and thereby offer an alternative new perspective in the field of psychiatry and comorbid conditions.

Partial Aminoglycoside Lesions in Vestibular Epithelia Reveal Broad Sensory Dysfunction Associated with Modest Hair Cell Loss and Afferent Calyx Retraction.

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Sultemeier, David R; Hoffman, Larry F

2017-01-01

Although the effects of aminoglycoside antibiotics on hair cells have been investigated for decades, their influences on the dendrites of primary afferent neurons have not been widely studied. This is undoubtedly due to the difficulty in disassociating pathology to dendritic processes from that resulting from loss of the presynaptic hair cell. This was overcome in the present investigation through development of a preparation using Chinchilla laniger that enabled direct perilymphatic infusion. Through this strategy we unmasked gentamicin's potential effects on afferent calyces. The pathophysiology of the vestibular neuroepithelia after post-administration durations of 0.5 through 6 months was assessed using single-neuron electrophysiology, immunohistochemistry, and confocal microscopy. Hair cell densities within cristae central zones (0.5-, 1-, 2-, and 6-months) and utricle peri- and extrastriola (6-months) regions were determined, and damage to calretinin-immunoreactive calyces was quantified. Gentamicin-induced hair cell loss exhibited a profile that reflected elimination of a most-sensitive group by 0.5-months post-administration (18.2%), followed by loss of a second group (20.6%) over the subsequent 5.5 months. The total hair cell loss with this gentamicin dose (approximately 38.8%) was less than the estimated fraction of type I hair cells in the chinchilla's crista central zone (approximately 60%), indicating that viable type I hair cells remained. Extensive lesions to afferent calyces were observed at 0.5-months, though stimulus-evoked modulation was intact at this post-administration time. Widespread compromise to calyx morphology and severe attenuation of stimulus-evoked afferent discharge modulation was found at 1 month post-administration, a condition that persisted in preparations examined through the 6-month post-administration interval. Spontaneous discharge was robust at all post-administration intervals. All calretinin-positive calyces had retracted

Afferent thermosensory function in relapsing-remitting multiple sclerosis following exercise-induced increases in body temperature.

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Filingeri, Davide; Chaseling, Georgia; Hoang, Phu; Barnett, Michael; Davis, Scott L; Jay, Ollie

2017-08-01

What is the central question of this study? Between 60 and 80% of multiple sclerosis (MS) patients experience transient worsening of symptoms with increased body temperature (heat sensitivity). As sensory abnormalities are common in MS, we asked whether afferent thermosensory function is altered in MS following exercise-induced increases in body temperature. What is the main finding and its importance? Increases in body temperature of as little as ∼0.4°C were sufficient to decrease cold, but not warm, skin thermosensitivity (∼10%) in MS, across a wider temperature range than in age-matched healthy individuals. These findings provide new evidence on the impact of heat sensitivity on afferent function in MS, which could be useful for clinical evaluation of this neurological disease. In multiple sclerosis (MS), increases in body temperature result in transient worsening of clinical symptoms (heat sensitivity or Uhthoff's phenomenon). Although the impact of heat sensitivity on efferent physiological function has been investigated, the effects of heat stress on afferent sensory function in MS are unknown. Hence, we quantified afferent thermosensory function in MS following exercise-induced increases in body temperature with a new quantitative sensory test. Eight relapsing-remitting MS patients (three men and five women; 51.4 ± 9.1 years of age; Expanded Disability Status Scale score 2.8 ± 1.1) and eight age-matched control (CTR) subjects (five men and three women; 47.4 ± 9.1 years of age) rated the perceived magnitude of two cold (26 and 22°C) and two warm stimuli (34 and 38°C) applied to the dorsum of the hand before and after 30 min cycling in the heat (30°C air; 30% relative humidity). Exercise produced similar increases in mean body temperature in MS [+0.39°C (95% CI: +0.21, +0.53) P = 0.001] and CTR subjects [+0.41°C (95% CI: +0.25, +0.58) P = 0.001]. These changes were sufficient to decrease thermosensitivity significantly to all cold [26

Emergence of gamma motor activity in an artificial neural network model of the corticospinal system.

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Grandjean, Bernard; Maier, Marc A

2017-02-01

Muscle spindle discharge during active movement is a function of mechanical and neural parameters. Muscle length changes (and their derivatives) represent its primary mechanical, fusimotor drive its neural component. However, neither the action nor the function of fusimotor and in particular of γ-drive, have been clearly established, since γ-motor activity during voluntary, non-locomotor movements remains largely unknown. Here, using a computational approach, we explored whether γ-drive emerges in an artificial neural network model of the corticospinal system linked to a biomechanical antagonist wrist simulator. The wrist simulator included length-sensitive and γ-drive-dependent type Ia and type II muscle spindle activity. Network activity and connectivity were derived by a gradient descent algorithm to generate reciprocal, known target α-motor unit activity during wrist flexion-extension (F/E) movements. Two tasks were simulated: an alternating F/E task and a slow F/E tracking task. Emergence of γ-motor activity in the alternating F/E network was a function of α-motor unit drive: if muscle afferent (together with supraspinal) input was required for driving α-motor units, then γ-drive emerged in the form of α-γ coactivation, as predicted by empirical studies. In the slow F/E tracking network, γ-drive emerged in the form of α-γ dissociation and provided critical, bidirectional muscle afferent activity to the cortical network, containing known bidirectional target units. The model thus demonstrates the complementary aspects of spindle output and hence γ-drive: i) muscle spindle activity as a driving force of α-motor unit activity, and ii) afferent activity providing continuous sensory information, both of which crucially depend on γ-drive.

Combined genetic and pharmacological inhibition of TRPV1 and P2X3 attenuates colorectal hypersensitivity and afferent sensitization

OpenAIRE

Kiyatkin, Michael E.; Feng, Bin; Schwartz, Erica S.; Gebhart, G. F.

2013-01-01

The ligand-gated channels transient receptor potential vanilloid 1 (TRPV1) and P2X3 have been reported to facilitate colorectal afferent neuron sensitization, thus contributing to organ hypersensitivity and pain. In the present study, we hypothesized that TRPV1 and P2X3 cooperate to modulate colorectal nociception and afferent sensitivity. To test this hypothesis, we employed TRPV1-P2X3 double knockout (TPDKO) mice and channel-selective pharmacological antagonists and evaluated combined chann...

Optimization of Large Gel 2D Electrophoresis for Proteomic Studies of Skeletal Muscle

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Reed, Patrick W.; Densmore, Allison; Bloch, Robert J.

2013-01-01

We describe improved methods for large format, 2-dimensional gel electrophoresis (2-DE) that improve protein solubility and recovery, minimize proteolysis, and reduce the loss of resolution due to contaminants and manipulations of the gels, and thus enhance quantitative analysis of protein spots. Key modifications are: (i) the use of 7M urea + 2 M thiourea, instead of 9M urea, in sample preparation and in the tops of the gel tubes; (ii) standardized deionization of all solutions containing urea with a mixed bed ion exchange resin and removal of urea from the electrode solutions; and (iii) use of a new gel tank and cooling device that eliminate the need to run two separating gels in the SDS dimension. These changes make 2D-GE analysis more reproducible and sensitive, with minimal artifacts. Application of this method to the soluble fraction of muscle tissues reliably resolves ~1800 protein spots in adult human skeletal muscle and over 2800 spots in myotubes. PMID:22589104

Chewing-induced hypertension in afferent baroreflex failure: a sympathetic response?

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Fuente Mora, Cristina; Norcliffe-Kaufmann, Lucy; Palma, Jose-Alberto; Kaufmann, Horacio

2015-11-01

What is the central question of this study? Our goal was to understand the autonomic responses to eating in patients with congenital afferent baroreflex failure, by documenting changes in blood pressure and heart rate with chewing, swallowing and stomach distension. What is the main finding and its importance? Patients born with lesions in the afferent baroreceptor pathways have an exaggerated pressor response to food intake. This appears to be a sympathetically mediated response, triggered by chewing, that occurs independently of swallowing or distension of the stomach. The chewing-induced pressor response may be useful as a counter-manoeuvre to prevent orthostatic hypotension in these patients. Familial dysautonomia (FD) is a rare genetic disease with extremely labile blood pressure resulting from baroreflex deafferentation. Patients have marked surges in sympathetic activity, frequently surrounding meals. We conducted an observational study to document the autonomic responses to eating in patients with FD and to determine whether sympathetic activation was caused by chewing, swallowing or stomach distension. Blood pressure and R-R intervals were measured continuously while chewing gum (n = 15), eating (n = 20) and distending the stomach by percutaneous endoscopic gastrostomy tube feeding (n = 9). Responses were compared with those of normal control subjects (n = 10) and of patients with efferent autonomic failure (n = 10) who have chronically impaired sympathetic outflow. In patients with FD, eating was associated with a marked but transient pressor response (P Chewing gum evoked a similar increase in blood pressure that was higher in patients with FD than in control subjects (P = 0.0001), but was absent in patients with autonomic failure. In patients with FD, distending the stomach by percutaneous endoscopic gastrostomy tube feeding failed to elicit a pressor response. The results provide indirect evidence that chewing triggers sympathetic

Organization of diencephalic and brainstem afferent projections to the lateral septum in the rat

NARCIS (Netherlands)

Luiten, Paul G.M.; Kuipers, Folkert; Schuitmaker, Hans

1982-01-01

Ascending diencephalic and brainstem afferents to the lateral septal column were studied by retrograde transport of horseradish peroxidase following microiontophoretic injections in the various subdivisions of the lateral septal area. Predominantly ispilateral cells, of which several coincide with

Differential vulnerability of 3 rapidly conducting somatosensory pathways in the dog with vitamin B6 neuropathy.

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Schaeppi, U; Krinke, G

1985-09-01

In anesthetized dogs with chronically implanted cortical electrodes somatic sensory-evoked potentials (SEPs) were produced by electrical stimulation at neural, muscular or cutaneous sites of the contralateral hind leg. Stimulation of the tibial nerve at the calcaneus or of the short flexor muscles of the hind paw caused SEPs having characteristics following activation of rapidly conducting afferents from muscle spindles. Stimulation of the glabrous skin of the central pad resulted in SEPs arriving after a more protracted latency evidently related to activation of afferents from Merkel cells, Krause and Pacinian corpuscles known to be located at these sites. Stimulation of the hairy skin from the dorsal surface of the hindpaw produced a further type of SEP presumably resulting from activation of afferents from receptors of tylotrich hair follicles. Vitamin B6-induced neuropathy involves the selective degeneration of the largest neurons in the spinal ganglia and of associated long peripheral and central neurites performing rapid impulse transmission. In the course of vitamin B6 neuropathy the relatively slow impulse transmission following stimulation of the central pad was more severely impaired than the faster one after activation of afferents from muscle spindles or receptors from hair follicles. This allows us to conclude that in the dog afferents from the glabrous skin of the central pad conduct centrally via the dorsal columns, susceptible to vitamin B6 intoxication, while muscle and hair receptor afferents ascend in the dorsal spinocerebellar and spinocervical tract, respectively, which are vitamin B6 resistant.

Cervical joint position sense in neck pain. Immediate effects of muscle vibration versus mental training interventions: a RCT.

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Beinert, K; Preiss, S; Huber, M; Taube, W

2015-12-01

Impaired cervical joint position sense is a feature of chronic neck pain and is commonly argued to rely on abnormal cervical input. If true, muscle vibration, altering afferent input, but not mental interventions, should have an effect on head repositioning acuity and neck pain perception. The aim of the present study was to determine the short-term effects of neck muscle vibration, motor imagery, and action observation on cervical joint position sense and pressure pain threshold in people with chronic neck pain. Forty-five blinded participants with neck pain received concealed allocation and were randomized in three treatment groups. A blinded assessor performed pre- and post-test measurement. Patients were recruited from secondary outpatient clinics in the southwest of Germany. Chronic, non specific neck pain patients without arm pain were recruited for this study. A single intervention session of 5 minutes was delivered to each blinded participant. Patients were either allocated to one of the following three interventions: (1) neck muscle vibration; (2) motor imagery; (3) action observation. Primary outcomes were cervical joint position sense acuity and pressure pain threshold. Repeated measures ANOVAs were used to evaluate differences between groups and subjects. Repositioning acuity displayed significant time effects for vibration, motor imagery, and action observation (all Ppain threshold demonstrated a time*group effect (P=0.042) as only vibration significantly increased pressure pain threshold (P=0.01). Although motor imagery and action observation did not modulate proprioceptive, afferent input, they nevertheless improved cervical joint position sense acuity. This indicates that, against the common opinion, changes in proprioceptive input are not prerequisite to improve joint repositioning performance. However, the short-term applications of these cognitive treatments had no effect on pressure pain thresholds, whereas vibration reduced pressure pain

Somatic modulation of spinal reflex bladder activity mediated by nociceptive bladder afferent nerve fibers in cats.

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Xiao, Zhiying; Rogers, Marc J; Shen, Bing; Wang, Jicheng; Schwen, Zeyad; Roppolo, James R; de Groat, William C; Tai, Changfeng

2014-09-15

The goal of the present study was to determine if supraspinal pathways are necessary for inhibition of bladder reflex activity induced by activation of somatic afferents in the pudendal or tibial nerve. Cats anesthetized with α-chloralose were studied after acute spinal cord transection at the thoracic T9/T10 level. Dilute (0.25%) acetic acid was used to irritate the bladder, activate nociceptive afferent C-fibers, and trigger spinal reflex bladder contractions (amplitude: 19.3 ± 2.9 cmH2O). Hexamethonium (a ganglionic blocker, intravenously) significantly (P reflex bladder contractions to 8.5 ± 1.9 cmH2O. Injection of lidocaine (2%, 1-2 ml) into the sacral spinal cord or transection of the sacral spinal roots and spinal cord further reduced the contraction amplitude to 4.2 ± 1.3 cmH2O. Pudendal nerve stimulation (PNS) at frequencies of 0.5-5 Hz and 40 Hz but not at 10-20 Hz inhibited reflex bladder contractions, whereas tibial nerve stimulation (TNS) failed to inhibit bladder contractions at all tested frequencies (0.5-40 Hz). These results indicate that PNS inhibition of nociceptive afferent C-fiber-mediated spinal reflex bladder contractions can occur at the spinal level in the absence of supraspinal pathways, but TNS inhibition requires supraspinal pathways. In addition, this study shows, for the first time, that after acute spinal cord transection reflex bladder contractions can be triggered by activating nociceptive bladder afferent C-fibers using acetic acid irritation. Understanding the sites of action for PNS or TNS inhibition is important for the clinical application of pudendal or tibial neuromodulation to treat bladder dysfunctions. Copyright © 2014 the American Physiological Society.

Lectin Ulex europaeus agglutinin I specifically labels a subset of primary afferent fibers which project selectively to the superficial dorsal horn of the spinal cord.

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Mori, K

1986-02-19

To examine differential carbohydrate expression among different subsets of primary afferent fibers, several fluorescein-isothiocyanate conjugated lectins were used in a histochemical study of the dorsal root ganglion (DRG) and spinal cord of the rabbit. The lectin Ulex europaeus agglutinin I specifically labeled a subset of DRG cells and primary afferent fibers which projected to the superficial laminae of the dorsal horn. These results suggest that specific carbohydrates containing L-fucosyl residue is expressed selectively in small diameter primary afferent fibers which subserve nociception or thermoception.

Osmoregulatory processes and skeletal muscle metabolism

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Boschmann, Michael; Gottschalk, Simone; Adams, Frauke; Luft, Friedrich C.; Jordan, Jens

Prolonged microgravity during space flight is associated with a decrease in blood and extracellular volume. These changes in water and electrolyte balance might activate catabolic processes which contribute finally to the loss of muscle and bone mass and strength. Recently, we found a prompt increase that energy expenditure by about 30% in both normal and overweight men and women after drinking 500 ml water. This effect is mediated by an increased sympathetic nervous system activity, obviously secondary to stimulation of osmosensitive afferent neurons in the liver, and skeletal muscle is possibly one effector organ. Therefore, we tested the hypothesis that this thermogenic response to water is accompanied by a stimulation of aerobic glucose metabolism in skeletal muscle. To this end, 16 young healthy volunteers (8 men) were studied. After an overnight fast (12h), a microdialysis probe was implanted into the right M. quadriceps femoris vastus lateralis and subsequently perfused with Ringer's solution (+50 mM ethanol). After 1h, volunteers were asked to drink 500 ml water (22° C) followed by continuing microdialysis for another 90 min. Dialysates (15 min fractions) were analyzed for [ethanol], [glucose], [lactate], [pyruvate], and [glycerol] in order to assess changes in muscle tissue perfusion (ethanol dilution technique), glycolysis and lipolysis. Blood samples were taken and heart rate (HR) and blood pressure (BP) were monitored. Neither HR and systolic and diastolic BP, nor plasma [glucose], [lactate], [insulin], and [C peptide] changed significantly after water drinking. Also, tissue perfusion and dialysate [glucose] did not change significantly. However, dialysate [lactate] increased by about 10 and 20% and dialysate [pyruvate] by about 100 and 200% in men and women, respectively. In contrast, dialysate [glycerol] decreased by about 30 and 20% in men and women, respectively. Therefore, drinking of 500 ml water stimulates aerobic glucose metabolism and inhibits

MR features of a case of afferent loop syndrome presenting as obstructive jaundice; IRM d'un syndrome de l'anse afferente revele par un ictere obstructif

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Chevallier, P.; Souci, J.; Oddo, F.; Diaine, B.; Padovani, B. [Centre Hospitalier Regional et Universitaire de Nice, Hopital Archet 2., Service d' Imagerie Medicale, 06 - Nice (France); Gueyffier, C. [Centre Hospitalier Regional de Cannes, Service d' Hepato-Gastro-enterologie, 06 - Cannes (France)

2001-02-01

The afferent loop syndrome corresponds to an acute or chronic obstruction of the afferent loop following a partial gastrectomy with Billroth II gastro-jejunal anastomosis. We describe the case of a 77-year-old man with history of partial gastrectomy for peptic ulcer disease performed 31 years ago and currently admitted for jaundice and poor general status. MR imaging showed dilatation of biliary and pancreatic ducts and showed a soft tissue mass between the afferent loop and the residual stomach. Endoscopy showed complete obstruction of the afferent loop by a biopsy-proven adenocarcinoma. The patient died of sepsis shortly after endoscopy of septicemia. (authors)

Afferent and Efferent Connections of the Optic Tectum in the Carp (Cyprinus carpio L.)

NARCIS (Netherlands)

Luiten, P.G.M.

1981-01-01

The afferent and efferent connections of the tectum opticum in the carp (Cyprinus carpio L.) were studied with the HRP method. Following iontophoretic peroxidase injections in several parts of the rectum anterograde transport of the enzyme revealed tectal projections to the lateral geniculate

Your Muscles

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... and you need to throw up. The muscles push the food back out of the stomach so it comes up ... body the power it needs to lift and push things. Muscles in your neck and the top part of your back aren't as large, but they are capable ...

Peripheral afferent mechanisms underlying acupuncture inhibition of cocaine behavioral effects in rats.

Directory of Open Access Journals (Sweden)

Seol Ah Kim

Full Text Available Administration of cocaine increases locomotor activity by enhancing dopamine transmission. To explore the peripheral mechanisms underlying acupuncture treatment for drug addiction, we developed a novel mechanical acupuncture instrument (MAI for objective mechanical stimulation. The aim of this study was to evaluate whether acupuncture inhibition of cocaine-induced locomotor activity is mediated through specific peripheral nerves, the afferents from superficial or deep tissues, or specific groups of nerve fibers. Mechanical stimulation of acupuncture point HT7 with MAI suppressed cocaine-induced locomotor activity in a stimulus time-dependent manner, which was blocked by severing the ulnar nerve or by local anesthesia. Suppression of cocaine-induced locomotor activity was elicited after HT7 stimulation at frequencies of either 50 (for Meissner corpuscles or 200 (for Pacinian corpuscles Hz and was not affected by block of C/Aδ-fibers in the ulnar nerve with resiniferatoxin, nor generated by direct stimulation of C/Aδ-fiber afferents with capsaicin. These findings suggest that HT7 inhibition of cocaine-induced locomotor activity is mediated by A-fiber activation of ulnar nerve that originates in superficial and deep tissue.

Influence of temperature on muscle recruitment and muscle function in vivo.

Science.gov (United States)

Rome, L C

1990-08-01

Temperature has a large influence on the maximum velocity of shortening (Vmax) and maximum power output of muscle (Q10 = 1.5-3). In some animals, maximum performance and maximum sustainable performance show large temperature sensitivities, because these parameters are dependent solely on mechanical power output of the muscles. The mechanics of locomotion (sarcomere length excursions and muscle-shortening velocities, V) at a given speed, however, are precisely the same at all temperatures. Animals compensate for the diminished power output of their muscles at low temperatures by compressing their recruitment order into a narrower range of locomotor speeds, that is, recruiting more muscle fibers and faster fiber types at a given speed. By examining V/Vmax, I calculate that fish at 10 degrees C must recruit 1.53-fold greater fiber cross section than at 20 degrees C. V/Vmax also appears to be an important design constraint in muscle. It sets the lowest V and the highest V over which a muscle can be used effectively. Because the Vmax of carp slow red muscle has a Q10 of 1.6 between 10 and 20 degrees C, the slow aerobic fibers can be used over a 1.6-fold greater range of swim speeds at the warmer temperature. In some species of fish, Vmax can be increased during thermal acclimation, enabling animals to swim at higher speeds.

Stability of Kinesthetic Perception in Efferent-Afferent Spaces: The Concept of Iso-perceptual Manifold.

Science.gov (United States)

Latash, Mark L

2018-02-21

The main goal of this paper is to introduce the concept of iso-perceptual manifold for perception of body configuration and related variables (kinesthetic perception) and to discuss its relation to the equilibrium-point hypothesis and the concepts of reference coordinate and uncontrolled manifold. Hierarchical control of action is postulated with abundant transformations between sets of spatial reference coordinates for salient effectors at different levels. Iso-perceptual manifold is defined in the combined space of afferent and efferent variables as the subspace corresponding to a stable percept. Examples of motion along an iso-perceptual manifold (perceptually equivalent motion) are considered during various natural actions. Some combinations of afferent and efferent signals, in particular those implying a violation of body's integrity, give rise to variable percepts by artificial projection onto iso-perceptual manifolds. This framework is used to interpret unusual features of vibration-induced kinesthetic illusions and to predict new illusions not yet reported in the literature. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Ablation of capsaicin sensitive afferent nerves impairs defence but not rapid repair of rat gastric mucosa.

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Pabst, M A; Schöninkle, E; Holzer, P

1993-07-01

Capsaicin sensitive afferent neurones have previously been reported to play a part in gastric mucosal protection. The aim of this study was to investigate whether these nociceptive neurones strengthen mucosal defence against injury or promote rapid repair of the damaged mucosa, or both. This hypothesis was examined in anaesthetised rats whose stomachs were perfused with ethanol (25 or 50% in saline, wt/wt) for 30 minutes. The gastric mucosa was inspected 0 and 180 minutes after ethanol had been given at the macroscopic, light, and scanning electron microscopic level. Rapid repair of the ethanol injured gastric mucosa (reduction of deep injury, partial re-epithelialisation of the denuded surface) took place in rats anaesthetised with phenobarbital, but not in those anaesthetised with urethane. Afferent nerve ablation as a result of treating rats with a neurotoxic dose of capsaicin before the experiment significantly aggravated ethanol induced damage as shown by an increase in the area and depth of mucosal erosions. Rapid repair of the injured mucosa, however, as seen in rats anesthetised with phenobarbital 180 minutes after ethanol was given, was similar in capsaicin and vehicle pretreated animals. Ablation of capsaicin sensitive afferent neurones was verified by a depletion of calcitonin gene related peptide from the gastric corpus wall. These findings indicate that nociceptive neurones control mechanisms of defence against acute injury but are not required for rapid repair of injured mucosa.

Distal muscle activity alterations during the stance phase of gait in restless leg syndrome (RLS) patients.

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Dafkin, Chloe; Green, Andrew; Olivier, Benita; McKinon, Warrick; Kerr, Samantha

2018-05-01

To assess if there is a circadian variation in electromyographical (EMG) muscle activity during gait in restless legs syndrome (RLS) patients and healthy control participants. Gait assessment was done in 14 RLS patients and 13 healthy control participants in the evening (PM) and the morning (AM). Muscle activity was recorded bilaterally from the tibialis anterior (TA), lateral gastrocnemius (GL), rectus femoris (RF) and biceps femoris (BF) muscles. A circadian variation during the stance phase in only TA (PM > AM, p  Controls, p < 0.05) during early stance and decreased GL activity (RLS < Controls, p < 0.01) during terminal stance in comparison to control participants in the evening. No other significant differences were noted between RLS patients and control participants. Activation of GL during the swing phase was noted in 79% of RLS patients and in 23% of control participants in the morning compared to 71% and 38% in the evening, respectively. EMG muscle activity shows no circadian variation in RLS patients. Evening differences in gait muscle activation patterns between RLS patients and control participants are evident. These results extend our knowledge about alterations in spinal processing during gait in RLS. A possible explanation for these findings is central pattern generator sensitization caused by increased sensitivity in cutaneous afferents in RLS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Maintained changes in motoneuronal excitability by short‐lasting synaptic inputs in the decerebrate cat

DEFF Research Database (Denmark)

Crone, C.; Hultborn, H.; Kiehn, O.

1988-01-01

1. During investigation of the tonic stretch reflex in the unanaesthetized decerebrate cat we observed that a short train of impulses in Ia afferents from the soleus muscle (or its synergists) may cause a prolonged activity in the soleus muscle as judged by EMG and tension recordings. This excita......1. During investigation of the tonic stretch reflex in the unanaesthetized decerebrate cat we observed that a short train of impulses in Ia afferents from the soleus muscle (or its synergists) may cause a prolonged activity in the soleus muscle as judged by EMG and tension recordings...

Concurrent gradients of ribbon volume and AMPA-receptor patch volume in cochlear afferent synapses on gerbil inner hair cells.

Science.gov (United States)

Zhang, Lichun; Engler, Sina; Koepcke, Lena; Steenken, Friederike; Köppl, Christine

2018-07-01

The Mongolian gerbil is a classic animal model for age-related hearing loss. As a prerequisite for studying age-related changes, we characterized cochlear afferent synaptic morphology in young adult gerbils, using immunolabeling and quantitative analysis of confocal microscopic images. Cochlear wholemounts were triple-labeled with a hair-cell marker, a marker of presynaptic ribbons, and a marker of postsynaptic AMPA-type glutamate receptors. Seven cochlear positions covering an equivalent frequency range from 0.5 - 32 kHz were evaluated. The spatial positions of synapses were determined in a coordinate system with reference to their individual inner hair cell. Synapse numbers confirmed previous reports for gerbils (on average, 20-22 afferents per inner hair cell). The volumes of presynaptic ribbons and postsynaptic glutamate receptor patches were positively correlated: larger ribbons associated with larger receptor patches and smaller ribbons with smaller patches. Furthermore, the volumes of both presynaptic ribbons and postsynaptic receptor patches co-varied along the modiolar-pillar and the longitudinal axes of their hair cell. The gradients in ribbon volume are consistent with previous findings in cat, guinea pig, mouse and rat and further support a role in differentiating the physiological properties of type I afferents. However, the positive correlation between the volumes of pre- and postsynaptic elements in the gerbil is different to the opposing gradients found in the mouse, suggesting species-specific differences in the postsynaptic AMPA receptors that are unrelated to the fundamental classes of type I afferents. Copyright © 2018 Elsevier B.V. All rights reserved.

Transmission between type II hair cells and bouton afferents in the turtle posterior crista.

Science.gov (United States)

Holt, Joseph C; Xue, Jin-Tang; Brichta, Alan M; Goldberg, Jay M

2006-01-01

Synaptic activity was recorded with sharp microelectrodes during rest and during 0.3-Hz sinusoidal stimulation from bouton afferents identified by their efferent-mediated inhibitory responses. A glutamate antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) decreased quantal size (qsize) while lowering external Ca(2+) decreased quantal rate (qrate). Miniature excitatory postsynaptic potentials (mEPSPs) had effective durations (qdur) of 3.5-5 ms. Their timing was consistent with Poisson statistics. Mean qsizes ranged in different units from 0.25 to 0.73 mV and mean qrates from 200 to 1,500/s; there was an inverse relation across the afferent population between qrate and qsize. qsize distributions were consistent with the independent release of variable-sized quanta. Channel noise, measured during AMPA-induced depolarizations, was small compared with quantal noise. Excitatory responses were larger than inhibitory responses. Peak qrates, which could approach 3,000/s, led peak excitatory mechanical stimulation by 40 degrees . Quantal parameters varied with stimulation phase with qdur and qsize being maximal during inhibitory stimulation. Voltage modulation (vmod) was in phase with qrate and had a peak depolarization of 1.5-3 mV. On average, 80% of vmod was accounted for by quantal activity; the remaining 20% was a nonquantal component that persisted in the absence of quantal activity. The extracellular accumulation of glutamate and K(+) are potential sources of nonquantal transmission and may provide a basis for the inverse relation between qrate and qsize. Comparison of the phases of synaptic and spike activity suggests that both presynaptic and postsynaptic mechanisms contribute to variations across afferents in the timing of spikes during sinusoidal stimulation.

Vasodilatation of afferent arterioles and paradoxical increase of renal vascular resistance by furosemide in mice

DEFF Research Database (Denmark)

Oppermann, Mona; Hansen, Pernille B; Castrop, Hayo

2007-01-01

Loop diuretics like furosemide have been shown to cause renal vasodilatation in dogs and humans, an effect thought to result from both a direct vascular dilator effect and from inhibition of tubuloglomerular feedback. In isolated perfused afferent arterioles preconstricted with angiotensin II or ...

Afferent Pathway-Mediated Effect of α1 Adrenergic Antagonist, Tamsulosin, on the Neurogenic Bladder After Spinal Cord Injury.

Science.gov (United States)

Han, Jin-Hee; Kim, Sung-Eun; Ko, Il-Gyu; Kim, Jayoung; Kim, Khae Hawn

2017-09-01

The functions of the lower urinary tract (LUT), such as voiding and storing urine, are dependent on complex central neural networks located in the brain, spinal cord, and peripheral ganglia. Thus, the functions of the LUT are susceptible to various neurologic disorders including spinal cord injury (SCI). SCI at the cervical or thoracic levels disrupts voluntary control of voiding and the normal reflex pathways coordinating bladder and sphincter functions. In this context, it is noteworthy that α1-adrenoceptor blockers have been reported to relieve voiding symptoms and storage symptoms in elderly men with benign prostatic hyperplasia (BPH). Tamsulosin, an α1-adrenoceptor blocker, is also considered the most effective regimen for patients with LUT symptoms such as BPH and overactive bladder (OAB). In the present study, the effects of tamsulosin on the expression of c-Fos, nerve growth factor (NGF), and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) in the afferent micturition areas, including the pontine micturition center (PMC), the ventrolateral periaqueductal gray matter (vlPAG), and the spinal cord (L5), of rats with an SCI were investigated. SCI was found to remarkably upregulate the expression of c-Fos, NGF, and NADPH-d in the afferent pathway of micturition, the dorsal horn of L5, the vlPAG, and the PMC, resulting in the symptoms of OAB. In contrast, tamsulosin treatment significantly suppressed these neural activities and the production of nitric oxide in the afferent pathways of micturition, and consequently, attenuated the symptoms of OAB. Based on these results, tamsulosin, an α1-adrenoceptor antagonist, could be used to attenuate bladder dysfunction following SCI. However, further studies are needed to elucidate the exact mechanism and effects of tamsulosin on the afferent pathways of micturition.

Afferent loop syndrome - a case report; Sindrome da alca aferente - relato de um caso

Energy Technology Data Exchange (ETDEWEB)

Borges, Ana Karina Nascimento; Pinheiro, Marco Antonio Lopes; Galvao, Cristine Norwig [Fundacao Pio XII - Hospital do Cancer de Barretos, SP (Brazil)

2000-02-01

The afferent loop syndrome occurs in patients with previous gastric surgery for tumor, when there is anastomotic edema, use of inappropriate reconstruction technique for gastro jejunostomy or recurrent gastric cancer. Complaints such jaundice, intermittent abdominal distension associated with pain, and vomiting should be investigated in order to rule out this syndrome. (author)

Effects of periodontal afferent inputs on corticomotor excitability in humans

DEFF Research Database (Denmark)

Zhang, Y; Boudreau, S; Wang, M

2010-01-01

for the first dorsal interosseous (FDI) as an internal control. Burning pain intensity and mechanical sensitivity ratings to a von Frey filament applied to the application site were recorded on an electronic visual analogue scale (VAS). All subjects reported a decreased mechanical sensitivity (anova: P = 0......-injection for the LA (anovas: P > 0.22) or capsaicin (anovas: P > 0.16) sessions. These findings suggest that a transient loss or perturbation in periodontal afferent input to the brain from a single incisor is insufficient to cause changes in corticomotor excitability of the face MI, as measured by TMS in humans....

Spatial factors and muscle spindle input influence the generation of neuromuscular responses to stimulation of the human foot

Science.gov (United States)

Layne, Charles S.; Forth, Katharine E.; Abercromby, Andrew F. J.

2005-05-01

Removal of the mechanical pressure gradient on the soles leads to physiological adaptations that ultimately result in neuromotor degradation during spaceflight. We propose that mechanical stimulation of the soles serves to partially restore the afference associated with bipedal loading and assists in attenuating the negative neuromotor consequences of spaceflight. A dynamic foot stimulus device was used to stimulate the soles in a variety of conditions with different stimulation locations, stimulation patterns and muscle spindle input. Surface electromyography revealed the lateral side of the sole elicited the greatest neuromuscular response in ankle musculature, followed by the medial side, then the heel. These responses were modified by preceding stimulation. Neuromuscular responses were also influenced by the level of muscle spindle input. These results provide important information that can be used to guide the development of a "passive" countermeasure that relies on sole stimulation and can supplement existing exercise protocols during spaceflight.

Expression of phosphorylated cAMP response element binding protein (p-CREB) in bladder afferent pathways in VIP-/- mice with cyclophosphamide (CYP)-induced cystitis

DEFF Research Database (Denmark)

Jensen, Dorthe G; Studeny, Simon; May, Victor

2008-01-01

The expression of phosphorylated cAMP response element binding protein (p-CREB) in dorsal root ganglia (DRG) with and without cyclophosphamide (CYP)-induced cystitis (150 mg/kg, i.p; 48 h) was determined in VIP(-/-) and wild-type (WT) mice. p-CREB immunoreactivity (IR) was determined in bladder...... (Fast blue) afferent cells. Nerve growth factor (NGF) bladder content was determined by enzyme-linked immunosorbent assays. Basal expression of p-CREB-IR in DRG of VIP(-/-) mice was (p DRG compared to WT mice. CYP treatment in WT mice increased (p ...-CREB-IR in L1, L2, L5-S1 DRG. CYP treatment in VIP(-/-) mice (p DRG compared to WT with CYP. In WT mice, bladder afferent cells (20-38%) in DRG expressed p-CREB-IR under basal conditions. With CYP, p-CREB-IR increased in bladder afferent cells (60...

P2-28: An Amplification of Feedback from Facial Muscles Strengthened Sympathetic Activations to Emotional Facial Cues

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Younbyoung Chae

2012-10-01

Full Text Available The facial feedback hypothesis suggests that feedback from cutaneous and muscular afferents influences our emotions during the control of facial expressions. Enhanced facial expressiveness is correlated with an increase in autonomic arousal, and self-reported emotional experience, while limited facial expression attenuates these responses. The present study was aimed at investigating the difference in emotional response in imitated versus observed facial expressions. For this, we measured the facial electromyogram of the corrugator muscle as well as the skin conductance response (SCR while participants were either imitating or simply observing emotional facial expressions. We found that participants produced significantly greater facial electromyogram activation during imitations compared to observations of angry faces. Similarly, they exhibited significantly greater SCR during imitations to angry faces compared to observations. An amplification of feedback from face muscles during imitation strengthened sympathetic activation to negative emotional cues. These findings suggest that manipulations of muscular feedback could modulate the bodily expression of emotion and perhaps also the emotional response itself.

Activation of afferent renal nerves modulates RVLM-projecting PVN neurons.

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Xu, Bo; Zheng, Hong; Liu, Xuefei; Patel, Kaushik P

2015-05-01

Renal denervation for the treatment of hypertension has proven to be successful; however, the underlying mechanism/s are not entirely clear. To determine if preautonomic neurons in the paraventricular nucleus (PVN) respond to afferent renal nerve (ARN) stimulation, extracellular single-unit recording was used to investigate the contribution of the rostral ventrolateral medulla (RVLM)-projecting PVN (PVN-RVLM) neurons to the response elicited during stimulation of ARN. In 109 spontaneously active neurons recorded in the PVN of anesthetized rats, 25 units were antidromically activated from the RVLM. Among these PVN-RVLM neurons, 84% (21/25) were activated by ARN stimulation. The baseline discharge rate was significantly higher in these neurons than those PVN-RVLM neurons not activated by ARN stimulation (16%, 4/25). The responsiveness of these neurons to baroreflex activation induced by phenylephrine and activation of cardiac sympathetic afferent reflex (CSAR) was also examined. Almost all of the PVN neurons that responded to ARN stimulation were sensitive to baroreflex (95%) and CSAR (100%). The discharge characteristics for nonevoked neurons (not activated by RVLM antidromic stimulation) showed that 23% of these PVN neurons responded to ARN stimulation. All the PVN neurons that responded to ARN stimulation were activated by N-methyl-D-aspartate, and these responses were attenuated by the glutamate receptor blocker AP5. These experiments demonstrated that sensory information originating in the kidney is integrated at the level of preautonomic neurons within the PVN, providing a novel mechanistic insight for use of renal denervation in the modulation of sympathetic outflow in disease states such as hypertension and heart failure. Copyright © 2015 the American Physiological Society.

Anorexia-cachexia syndrome in hepatoma tumour-bearing rats requires the area postrema but not vagal afferents and is paralleled by increased MIC-1/GDF15.

Science.gov (United States)

Borner, Tito; Arnold, Myrtha; Ruud, Johan; Breit, Samuel N; Langhans, Wolfgang; Lutz, Thomas A; Blomqvist, Anders; Riediger, Thomas

2017-06-01

The cancer-anorexia-cachexia syndrome (CACS) negatively affects survival and therapy success in cancer patients. Inflammatory mediators and tumour-derived factors are thought to play an important role in the aetiology of CACS. However, the central and peripheral mechanisms contributing to CACS are insufficiently understood. The area postrema (AP) and the nucleus tractus solitarii are two important brainstem centres for the control of eating during acute sickness conditions. Recently, the tumour-derived macrophage inhibitory cytokine-1 (MIC-1) emerged as a possible mediator of cancer anorexia because lesions of these brainstem areas attenuated the anorectic effect of exogenous MIC-1 in mice. Using a rat hepatoma tumour model, we examined the roles of the AP and of vagal afferents in the mediation of CACS. Specifically, we investigated whether a lesion of the AP (APX) or subdiaphragmatic vagal deafferentation (SDA) attenuate anorexia, body weight, muscle, and fat loss. Moreover, we analysed MIC-1 levels in this tumour model and their correlation with tumour size and the severity of the anorectic response. In tumour-bearing sham-operated animals mean daily food intake significantly decreased. The anorectic response was paralleled by a significant loss of body weight and muscle mass. APX rats were protected against anorexia, body weight loss, and muscle atrophy after tumour induction. In contrast, subdiaphragmatic vagal deafferentation did not attenuate cancer-induced anorexia or body weight loss. Tumour-bearing rats had substantially increased MIC-1 levels, which positively correlated with tumour size and cancer progression and negatively correlated with food intake. These findings demonstrate the importance of the AP in the mediation of cancer-dependent anorexia and body weight loss and support a pathological role of MIC-1 as a tumour-derived factor mediating CACS, possibly via an AP-dependent action. © 2016 The Authors. Journal of Cachexia, Sarcopenia and Muscle

The Bone-Muscle Relationship in Men and Women

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Thomas F. Lang

2011-01-01

Full Text Available Muscle forces are a strong determinant of bone structure, particularly during the process of growth and development. The gender divergence in the bone-muscle relationship becomes strongly evident during adolescence. In females, growth is characterized by increased estrogen levels and increased mass and strength of bone relative to that of muscle, whereas in men, increases in testosterone fuel large increases in muscle, resulting in muscle forces that coincide with a large growth in bone dimensions and strength. In adulthood, significant age-related losses are observed for both bone and muscle tissues. Large decrease in estrogen levels in women appears to diminish the skeleton's responsiveness to exercise more than in men. In contrast, the aging of the muscle-bone axis in men is a function of age related declines in both hormones. In addition to the well-known age related changes in the mechanical loading of bone by muscle, newer studies appear to provide evidence of age- and gender-related variations in molecular signaling between bone and muscle that are independent of purely mechanical interactions. In summary, gender differences in the acquisition and age-related loss in bone and muscle tissues may be important for developing gender-specific strategies for using exercise to reduce bone loss with aging.

Could a functional artificial skeletal muscle be useful in muscle wasting?

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Fuoco, Claudia; Cannata, Stefano; Gargioli, Cesare

2016-05-01

Regardless of the underlying cause, skeletal muscle wasting is detrimental for a person's life quality, leading to impaired strength, locomotion, and physiological activity. Here, we propose a series of studies presenting tissue engineering-based approaches to reconstruct artificial muscle in vitro and in vivo. Skeletal muscle tissue engineering is attracting more and more attention from scientists, clinicians, patients, and media, thanks to the promising results obtained in the last decade with animal models of muscle wasting. The use of novel and refined biomimetic scaffolds mimicking three-dimensional muscle environment, thus supporting cell survival and differentiation, in combination with well characterized myogenic stem/progenitor cells, revealed the noteworthy potential of these technologies for creating artificial skeletal muscle tissue. In vitro, the production of three-dimensional muscle structures offer the possibility to generate a drug-screening platform for patient-specific pharmacological treatment, opening new frontiers in the development of new compounds with specific therapeutic actions. In vivo, three-dimensional artificial muscle biomimetic constructs offer the possibility to replace, in part or entirely, wasted muscle by means of straight reconstruction and/or by enhancing endogenous regeneration. Reports of tissue engineering approaches for artificial muscle building appeared in large numbers in the specialized press lately, advocating the suitability of this technology for human application upon scaling up and a near future applicability for medical care of muscle wasting. http://links.lww.com/COCN/A9

Thrombospondins 1 and 2 are important for afferent synapse formation and function in the inner ear.

Science.gov (United States)

Mendus, Diana; Sundaresan, Srividya; Grillet, Nicolas; Wangsawihardja, Felix; Leu, Rose; Müller, Ulrich; Jones, Sherri M; Mustapha, Mirna

2014-04-01

Thrombospondins (TSPs) constitute a family of secreted extracellular matrix proteins that have been shown to be involved in the formation of synapses in the central nervous system. In this study, we show that TSP1 and TSP2 are expressed in the cochlea, and offer the first description of their putative roles in afferent synapse development and function in the inner ear. We examined mice with deletions of TSP1, TSP2 and both (TSP1/TSP2) for inner ear development and function. Immunostaining for synaptic markers indicated a significant decrease in the number of formed afferent synapses in the cochleae of TSP2 and TSP1/TSP2 knockout (KO) mice at postnatal day (P)29. In functional studies, TSP2 and TSP1/TSP2 KO mice showed elevated auditory brainstem response (ABR) thresholds as compared with wild-type littermates, starting at P15, with the most severe phenotype being seen for TSP1/TSP2 KO mice. TSP1/TSP2 KO mice also showed reduced wave I amplitudes of ABRs and vestibular evoked potentials, suggesting synaptic dysfunction in both the auditory and vestibular systems. Whereas ABR thresholds in TSP1 KO mice were relatively unaffected at early ages, TSP1/TSP2 KO mice showed the most severe phenotype among all of the genotypes tested, suggesting functional redundancy between the two genes. On the basis of the above results, we propose that TSPs play an important role in afferent synapse development and function of the inner ear. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Anorexia‐cachexia syndrome in hepatoma tumour‐bearing rats requires the area postrema but not vagal afferents and is paralleled by increased MIC‐1/GDF15

Science.gov (United States)

Borner, Tito; Arnold, Myrtha; Ruud, Johan; Breit, Samuel N.; Langhans, Wolfgang; Lutz, Thomas A.; Blomqvist, Anders

2016-01-01

Abstract Background The cancer‐anorexia‐cachexia syndrome (CACS) negatively affects survival and therapy success in cancer patients. Inflammatory mediators and tumour‐derived factors are thought to play an important role in the aetiology of CACS. However, the central and peripheral mechanisms contributing to CACS are insufficiently understood. The area postrema (AP) and the nucleus tractus solitarii are two important brainstem centres for the control of eating during acute sickness conditions. Recently, the tumour‐derived macrophage inhibitory cytokine‐1 (MIC‐1) emerged as a possible mediator of cancer anorexia because lesions of these brainstem areas attenuated the anorectic effect of exogenous MIC‐1 in mice. Methods Using a rat hepatoma tumour model, we examined the roles of the AP and of vagal afferents in the mediation of CACS. Specifically, we investigated whether a lesion of the AP (APX) or subdiaphragmatic vagal deafferentation (SDA) attenuate anorexia, body weight, muscle, and fat loss. Moreover, we analysed MIC‐1 levels in this tumour model and their correlation with tumour size and the severity of the anorectic response. Results In tumour‐bearing sham‐operated animals mean daily food intake significantly decreased. The anorectic response was paralleled by a significant loss of body weight and muscle mass. APX rats were protected against anorexia, body weight loss, and muscle atrophy after tumour induction. In contrast, subdiaphragmatic vagal deafferentation did not attenuate cancer‐induced anorexia or body weight loss. Tumour‐bearing rats had substantially increased MIC‐1 levels, which positively correlated with tumour size and cancer progression and negatively correlated with food intake. Conclusions These findings demonstrate the importance of the AP in the mediation of cancer‐dependent anorexia and body weight loss and support a pathological role of MIC‐1 as a tumour‐derived factor mediating CACS, possibly via an AP�

Mechanical modeling of skeletal muscle functioning

NARCIS (Netherlands)

van der Linden, B.J.J.J.

1998-01-01

For movement of body or body segments is combined effort needed of the central nervous system and the muscular-skeletal system. This thesis deals with the mechanical functioning of skeletal muscle. That muscles come in a large variety of geometries, suggest the existence of a relation between muscle

Identification of the main generator source of longitudinal muscle contraction in the earthworm ventral nerve cord

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Chang Y.C.

1998-01-01

Full Text Available The main generator source of a longitudinal muscle contraction was identified as an M (mechanical-stimulus-sensitive circuit composed of a presynaptic M-1 neuron and a postsynaptic M-2 neuron in the ventral nerve cord of the earthworm, Amynthas hawayanus, by simultaneous intracellular response recording and Lucifer Yellow-CH injection with two microelectrodes. Five-peaked responses were evoked in both neurons by a mechanical, but not by an electrical, stimulus to the mechanoreceptor in the shaft of a seta at the opposite side of an epidermis-muscle-nerve-cord preparation. This response was correlated to 84% of the amplitude, 73% of the rising rate and 81% of the duration of a longitudinal muscle contraction recorded by a mechano-electrical transducer after eliminating the other possible generator sources by partitioning the epidermis-muscle piece of this preparation. The pre- and postsynaptic relationship between these two neurons was determined by alternately stimulating and recording with two microelectrodes. Images of the Lucifer Yellow-CH-filled M-1 and M-2 neurons showed that both of them are composed of bundles of longitudinal processes situated on the side of the nerve cord opposite to stimulation. The M-1 neuron has an afferent process (A1 in the first nerve at the stimulated side of this preparation and the M-2 neuron has two efferent processes (E1 and E3 in the first and third nerves at the recording side where their effector muscle cell was identified by a third microelectrode.

Peripheral Mechanisms of Ischemic Myalgia

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Luis F. Queme

2017-12-01

Full Text Available Musculoskeletal pain due to ischemia is present in a variety of clinical conditions including peripheral vascular disease (PVD, sickle cell disease (SCD, complex regional pain syndrome (CRPS, and even fibromyalgia (FM. The clinical features associated with deep tissue ischemia are unique because although the subjective description of pain is common to other forms of myalgia, patients with ischemic muscle pain often respond poorly to conventional analgesic therapies. Moreover, these patients also display increased cardiovascular responses to muscle contraction, which often leads to exercise intolerance or exacerbation of underlying cardiovascular conditions. This suggests that the mechanisms of myalgia development and the role of altered cardiovascular function under conditions of ischemia may be distinct compared to other injuries/diseases of the muscles. It is widely accepted that group III and IV muscle afferents play an important role in the development of pain due to ischemia. These same muscle afferents also form the sensory component of the exercise pressor reflex (EPR, which is the increase in heart rate and blood pressure (BP experienced after muscle contraction. Studies suggest that afferent sensitization after ischemia depends on interactions between purinergic (P2X and P2Y receptors, transient receptor potential (TRP channels, and acid sensing ion channels (ASICs in individual populations of peripheral sensory neurons. Specific alterations in primary afferent function through these receptor mechanisms correlate with increased pain related behaviors and altered EPRs. Recent evidence suggests that factors within the muscles during ischemic conditions including upregulation of growth factors and cytokines, and microvascular changes may be linked to the overexpression of these different receptor molecules in the dorsal root ganglia (DRG that in turn modulate pain and sympathetic reflexes. In this review article, we will discuss the

The neural response properties and cortical organization of a rapidly adapting muscle sensory group response that overlaps with the frequencies that elicit the kinesthetic illusion.

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Marasco, Paul D; Bourbeau, Dennis J; Shell, Courtney E; Granja-Vazquez, Rafael; Ina, Jason G

2017-01-01

Kinesthesia is the sense of limb movement. It is fundamental to efficient motor control, yet its neurophysiological components remain poorly understood. The contributions of primary muscle spindles and cutaneous afferents to the kinesthetic sense have been well studied; however, potential contributions from muscle sensory group responses that are different than the muscle spindles have not been ruled out. Electrophysiological recordings in peripheral nerves and brains of male Sprague Dawley rats with a degloved forelimb preparation provide evidence of a rapidly adapting muscle sensory group response that overlaps with vibratory inputs known to generate illusionary perceptions of limb movement in humans (kinesthetic illusion). This group was characteristically distinct from type Ia muscle spindle fibers, the receptor historically attributed to limb movement sensation, suggesting that type Ia muscle spindle fibers may not be the sole carrier of kinesthetic information. The sensory-neural structure of muscles is complex and there are a number of possible sources for this response group; with Golgi tendon organs being the most likely candidate. The rapidly adapting muscle sensory group response projected to proprioceptive brain regions, the rodent homolog of cortical area 3a and the second somatosensory area (S2), with similar adaption and frequency response profiles between the brain and peripheral nerves. Their representational organization was muscle-specific (myocentric) and magnified for proximal and multi-articulate limb joints. Projection to proprioceptive brain areas, myocentric representational magnification of muscles prone to movement error, overlap with illusionary vibrational input, and resonant frequencies of volitional motor unit contraction suggest that this group response may be involved with limb movement processing.

How Insect Flight Steering Muscles Work

OpenAIRE

Walker, Simon M.; Schwyn, Daniel A.; Mokso, Rajmund; Wicklein, Martina; Müller, Tonya; Doube, Michael; Stampanoni, Marco; Krapp, Holger G.; Taylor, Graham K.

2014-01-01

Dipteran flies are amongst the smallest and most agile of flying animals. Their wings are driven indirectly by large power muscles, which cause cyclical deformations of the thorax that are amplified through the intricate wing hinge. Asymmetric flight manoeuvres are controlled by 13 pairs of steering muscles acting directly on the wing articulations. Collectively the steering muscles account for

Stimulation of renal afferent fibers leads to activation of catecholaminergic and non-catecholaminergic neurons in the medulla oblongata.

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Nishi, Erika E; Martins, Beatriz S; Milanez, Maycon I O; Lopes, Nathalia R; de Melo, Jose F; Pontes, Roberto B; Girardi, Adriana C; Campos, Ruy R; Bergamaschi, Cássia T

2017-05-01

Presympathetic neurons in the rostral ventrolateral medulla (RVLM) including the adrenergic cell groups play a major role in the modulation of several reflexes required for the control of sympathetic vasomotor tone and blood pressure (BP). Moreover, sympathetic vasomotor drive to the kidneys influence natriuresis and diuresis by inhibiting the cAMP/PKA pathway and redistributing the Na + /H + exchanger isoform 3 (NHE3) to the body of the microvilli in the proximal tubules. In this study we aimed to evaluate the effects of renal afferents stimulation on (1) the neurochemical phenotype of Fos expressing neurons in the medulla oblongata and (2) the level of abundance and phosphorylation of NHE3 in the renal cortex. We found that electrical stimulation of renal afferents increased heart rate and BP transiently and caused activation of tyrosine hydroxylase (TH)-containing neurons in the RVLM and non-TH neurons in the NTS. Additionally, activation of the inhibitory renorenal reflex over a 30-min period resulted in increased natriuresis and diuresis associated with increased phosphorylation of NHE3 at serine 552, a surrogate for reduced activity of this exchanger, in the contralateral kidney. This effect was not dependent of BP changes considering that no effects on natriuresis or diuresis were found in the ipsilateral-stimulated kidney. Therefore, our data show that renal afferents leads to activation of catecholaminergic and non-catecholaminergic neurons in the medulla oblongata. When renorenal reflex is induced, NHE3 exchanger activity appears to be decreased, resulting in decreased sodium and water reabsorption in the contralateral kidney. Copyright © 2017 Elsevier B.V. All rights reserved.

Afferent input selects NMDA receptor subtype to determine the persistency of hippocampal LTP in freely behaving mice

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Jesús Javier Ballesteros

2016-10-01

Full Text Available The glutamatergic N-methyl-D-aspartate receptor (NMDAR is critically involved in many forms of hippocampus-dependent memory that may be enabled by synaptic plasticity. Behavioral studies with NMDAR antagonists and NMDAR subunit (GluN2 mutants revealed distinct contributions from GluN2A- and GluN2B-containing NMDARs to rapidly and slowly acquired memory performance. Furthermore, studies of synaptic plasticity, in genetically modified mice in vitro, suggest that GluN2A and GluN2B may contribute in different ways to the induction and longevity of synaptic plasticity. In contrast to the hippocampal slice preparation, in behaving mice, the afferent frequencies that induce synaptic plasticity are very restricted and specific. In fact, it is the stimulus pattern, and not variations in afferent frequency that determine the longevity of long-term potentiation (LTP. Here, we explored the contribution of GluN2A and GluN2B to LTP of differing magnitudes and persistencies in freely behaving mice. We applied differing high-frequency stimulation (HFS patterns at 100 Hz to the hippocampal CA1 region, to induce NMDAR-dependent LTP in wild-type (WT mice, that endured for 24h (late (L-LTP. In GluN2A-KO mice, E-LTP (HFS, 50 pulses was significantly reduced in magnitude and duration, whereas LTP (HFS, 2 x 50 pulses and L-LTP (HFS, 4 x 50 pulses were unaffected compared to responses in WT animals. By contrast, pharmacological antagonism of GluN2B in WT had no effect on E-LTP but significantly prevented LTP. E- LTP and LTP were significantly impaired by GluN2B antagonism in GluN2A-KO mice. These data indicate that the pattern of afferent stimulation is decisive for the recruitment of distinct GluN2A and GluN2B signaling pathways that in turn determine the persistency of hippocampal LTP. Whereas brief bursts of patterned stimulation preferentially recruit GluN2A and lead to weak and short-lived forms of LTP, prolonged, more intense, afferent activation recruits GluN2B

Effects of adding Braun jejunojejunostomy to standard Whipple procedure on reduction of afferent loop syndrome - a randomized clinical trial.

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Kakaei, Farzad; Beheshtirouy, Samad; Nejatollahi, Seyed Moahammad Reza; Rashidi, Iqbal; Asvadi, Touraj; Habibzadeh, Afshin; Oliaei-Motlagh, Mohammad

2015-12-01

Whipple surgery (pancreaticodeudenectomy) has a high complication rate. We aimed to evaluate whether adding Braun jejunojejunostomy (side-to-side anastomosis of afferent and efferent loops distal to the gastrojejunostomy site) to a standard Whipple procedure would reduce postoperative complications. We conducted a randomized clinical trial comparing patients who underwent standard Whipple surgery (standard group) and patients who underwent standard Whipple surgery with Braun jejunojejunostomy (Braun group). Patients were followed for 1 month after the procedure and postoperative complications were recorded. Our study included 30 patients: 15 in the Braun and 15 in the standard group. In the Braun group, 4 (26.7%) patients experienced 6 complications, whereas in the standard group, 7 (46.7%) patients experienced 11 complications (p = 0.14). Complications in the Braun group were gastrointestinal bleeding and wound infection (n = 1 each) and delayed gastric emptying and pulmonary infection (n = 2 each). Complications in the standard group were death, pancreatic anastomosis leak and biliary anastomosis leak (n = 1 each); gastrointestinal bleeding (n = 2); and afferent loop syndrome and delayed gastric emptying (n = 3 each). There was no significant difference between groups in the subtypes of complications. Our results showed that adding Braun jejunojejunostomy to standard Whipple procedure was associated with lower rates of afferent loop syndrome and delayed gastric emptying. However, more studies are needed to define the role of Braun jejunojejunostomy in this regard. IRCT2014020316473N1 (www.irct.ir).

Innervation of the mammalian esophagus.

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Neuhuber, Winfried L; Raab, Marion; Berthoud, Hans-Rudolf; Wörl, Jürgen

2006-01-01

Understanding the innervation of the esophagus is a prerequisite for successful treatment of a variety of disorders, e.g., dysphagia, achalasia, gastroesophageal reflux disease (GERD) and non-cardiac chest pain. Although, at first glance, functions of the esophagus are relatively simple, their neuronal control is considerably complex. Vagal motor neurons of the nucleus ambiguus and preganglionic neurons of the dorsal motor nucleus innervate striated and smooth muscle, respectively. Myenteric neurons represent the interface between the dorsal motor nucleus and smooth muscle but they are also involved in striated muscle innervation. Intraganglionic laminar endings (IGLEs) represent mechanosensory vagal afferent terminals. They also establish intricate connections with enteric neurons. Afferent information is implemented by the swallowing central pattern generator in the brainstem, which generates and coordinates deglutitive activity in both striated and smooth esophageal muscle and orchestrates esophageal sphincters as well as gastric adaptive relaxation. Disturbed excitation/inhibition balance in the lower esophageal sphincter results in motility disorders, e.g., achalasia and GERD. Loss of mechanosensory afferents disrupts adaptation of deglutitive motor programs to bolus variables, eventually leading to megaesophagus. Both spinal and vagal afferents appear to contribute to painful sensations, e.g., non-cardiac chest pain. Extrinsic and intrinsic neurons may be involved in intramural reflexes using acetylcholine, nitric oxide, substance P, CGRP and glutamate as main transmitters. In addition, other molecules, e.g., ATP, GABA and probably also inflammatory cytokines, may modulate these neuronal functions.

Is back pain during childhood or adolescence associated with muscle strength, muscle endurance or aerobic capacity

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Lardon, Arnaud; Leboeuf-Yde, Charlotte; Le Scanff, Christine

2015-01-01

BACKGROUND: Back pain is a common condition during childhood and adolescence. The causes of back pain are largely unknown but it seems plausible that some physical factors such as back muscle strength, back muscle endurance and aerobic capacity may play a role in its development, in particular...... aerobic capacity and back pain is not clear. CONCLUSIONS: High back muscle endurance in extension appears protective of back pain in youngsters, but the roles of high back muscle strength in extension and aerobic capacity are less clear....

Change in muscle fascicle length influences the recruitment and discharge rate of motor units during isometric contractions.

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Pasquet, Benjamin; Carpentier, Alain; Duchateau, Jacques

2005-11-01

This study examines the effect of fascicle length change on motor-unit recruitment and discharge rate in the human tibialis anterior (TA) during isometric contractions of various intensities. The torque produced during dorsiflexion and the surface and intramuscular electromyograms (EMGs) from the TA were recorded in eight subjects. The behavior of the same motor unit (n = 59) was compared at two ankle joint angles (+10 and -10 degrees around the ankle neutral position). Muscle fascicle length of the TA was measured noninvasively using ultrasonography recordings. When the ankle angle was moved from 10 degrees plantarflexion to 10 degrees dorsiflexion, the torque produced during maximal voluntary contraction (MVC) was significantly reduced [35.2 +/- 3.3 vs. 44.3 +/- 4.2 (SD) Nm; P Motor units were activated at a lower recruitment threshold for short compared with long muscle fascicle length, either when expressed in absolute values (2.1 +/- 2.5 vs. 3.6 +/- 3.7 Nm; P motor-unit recruitment were observed at a given absolute or relative torque when muscle fascicles were shortened. However, the data indicate that increased rate coding was mainly present at low torque level (recruitment of additional motor units played a dominant role at higher torque level and decreased compliance (10-35% MVC). Taken together, the results suggest that the central command is modulated by the afferent proprioceptive information during submaximal contractions performed at different muscle fascicle lengths.

Peripheral Receptor Mechanisms Underlying Orofacial Muscle Pain and Hyperalgesia

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Saloman, Jami L.

Musculoskeletal pain conditions, particularly those associated with temporomandibular joint and muscle disorders (TMD) are severely debilitating and affect approximately 12% of the population. Identifying peripheral nociceptive mechanisms underlying mechanical hyperalgesia, a prominent feature of persistent muscle pain, could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. This study provides evidence of functional interactions between ligand-gated channels, P2X3 and TRPV1/TRPA1, in trigeminal sensory neurons, and proposes that these interactions underlie the development of mechanical hyperalgesia. In the masseter muscle, direct P2X3 activation, via the selective agonist αβmeATP, induced a dose- and time-dependent hyperalgesia. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810, or the TRPA1 antagonist, AP18. P2X3 was co-expressed with both TRPV1 and TRPA1 in masseter muscle afferents confirming the possibility for intracellular interactions. Moreover, in a subpopulation of P2X3 /TRPV1 positive neurons, capsaicin-induced Ca2+ transients were significantly potentiated following P2X3 activation. Inhibition of Ca2+-dependent kinases, PKC and CaMKII, prevented P2X3-mechanical hyperalgesia whereas blockade of Ca2+-independent PKA did not. Finally, activation of P2X3 induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal sensory neurons. Significant phosphorylation was observed at 15 minutes, the time point at which behavioral hyperalgesia was prominent. Similar data were obtained regarding another nonselective cation channel, the NMDA receptor (NMDAR). Our data propose P2X3 and NMDARs interact with TRPV1 in a facilitatory manner, which could contribute to the peripheral sensitization underlying masseter hyperalgesia. This study offers novel mechanisms by which individual pro-nociceptive ligand

Trichinella spiralis in human muscle (image)

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This is the parasite Trichinella spiralis in human muscle tissue. The parasite is transmitted by eating undercooked meats, especially pork. The cysts hatch in the intestines and produce large numbers of larvae that migrate into muscle tissue. The cysts ...

Striated Muscle Function, Regeneration, and Repair

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Shadrin, I.Y.; Khodabukus, A.; Bursac, N.

2016-01-01

As the only striated muscle tissues in the body, skeletal and cardiac muscle share numerous structural and functional characteristics, while exhibiting vastly different size and regenerative potential. Healthy skeletal muscle harbors a robust regenerative response that becomes inadequate after large muscle loss or in degenerative pathologies and aging. In contrast, the mammalian heart loses its regenerative capacity shortly after birth, leaving it susceptible to permanent damage by acute injury or chronic disease. In this review, we compare and contrast the physiology and regenerative potential of native skeletal and cardiac muscles, mechanisms underlying striated muscle dysfunction, and bioengineering strategies to treat muscle disorders. We focus on different sources for cellular therapy, biomaterials to augment the endogenous regenerative response, and progress in engineering and application of mature striated muscle tissues in vitro and in vivo. Finally, we discuss the challenges and perspectives in translating muscle bioengineering strategies to clinical practice. PMID:27271751

The neural response properties and cortical organization of a rapidly adapting muscle sensory group response that overlaps with the frequencies that elicit the kinesthetic illusion.

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Paul D Marasco

Full Text Available Kinesthesia is the sense of limb movement. It is fundamental to efficient motor control, yet its neurophysiological components remain poorly understood. The contributions of primary muscle spindles and cutaneous afferents to the kinesthetic sense have been well studied; however, potential contributions from muscle sensory group responses that are different than the muscle spindles have not been ruled out. Electrophysiological recordings in peripheral nerves and brains of male Sprague Dawley rats with a degloved forelimb preparation provide evidence of a rapidly adapting muscle sensory group response that overlaps with vibratory inputs known to generate illusionary perceptions of limb movement in humans (kinesthetic illusion. This group was characteristically distinct from type Ia muscle spindle fibers, the receptor historically attributed to limb movement sensation, suggesting that type Ia muscle spindle fibers may not be the sole carrier of kinesthetic information. The sensory-neural structure of muscles is complex and there are a number of possible sources for this response group; with Golgi tendon organs being the most likely candidate. The rapidly adapting muscle sensory group response projected to proprioceptive brain regions, the rodent homolog of cortical area 3a and the second somatosensory area (S2, with similar adaption and frequency response profiles between the brain and peripheral nerves. Their representational organization was muscle-specific (myocentric and magnified for proximal and multi-articulate limb joints. Projection to proprioceptive brain areas, myocentric representational magnification of muscles prone to movement error, overlap with illusionary vibrational input, and resonant frequencies of volitional motor unit contraction suggest that this group response may be involved with limb movement processing.

Intracellular signalling pathways in the vasoconstrictor response of mouse afferent arterioles to adenosine

DEFF Research Database (Denmark)

Hansen, Pernille B. Lærkegaard; Friis, Ulla Glenert; Uhrenholt, Torben Rene

2007-01-01

of calcium from the sarcoplasmic reticulum (SR), stimulated presumably by IP(3), is involved in the adenosine contraction mechanism of the afferent arteriole. In agreement with this notion is the observation that 2 aminoethoxydiphenyl borate (100 microM) blocked the adenosine-induced constriction whereas...... was abolished by IAA-94. Furthermore, the vasoconstriction caused by adenosine was significantly inhibited by 5 microM nifedipine (control 8.3 +/- 0.2 microM, ado 3.6 +/- 0.6 microM, ado + nifedipine 6.8 +/- 0.2 microM) suggesting involvement of voltage-dependent calcium channels. CONCLUSION: We conclude...

Adenosine induces vasoconstriction through Gi-dependent activation of phospholipase C in isolated perfused afferent arterioles of mice

DEFF Research Database (Denmark)

Hansen, Pernille B; Castrop, Hayo; Briggs, Josie

2003-01-01

-induced vasoconstriction was stable for up to 30 min and was most pronounced in the most distal part of the afferent arterioles. Adenosine did not cause vasoconstriction in arterioles from A1AR-/- mice. Pretreatment with pertussis toxin (PTX) (400 ng/ml) for 2 h blocked the vasoconstricting action of adenosine or N(6...

Liver afferents contribute to water drinking-induced sympathetic activation in human subjects: a clinical trial.

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Marcus May

Full Text Available Water drinking acutely increases sympathetic activity in human subjects. In animals, the response appears to be mediated through transient receptor potential channel TRPV4 activation on osmosensitive hepatic spinal afferents, described as osmopressor response. We hypothesized that hepatic denervation attenuates water drinking-induced sympathetic activation. We studied 20 liver transplant recipients (44±2.6 years, 1.2±0.1 years post transplant as model of hepatic denervation and 20 kidney transplant recipients (43±2.6 years, 0.8±0.1 years post transplant as immunosuppressive drug matched control group. Before and after 500 ml water ingestion, we obtained venous blood samples for catecholamine analysis. We also monitored brachial and finger blood pressure, ECG, and thoracic bioimpedance. Plasma norepinephrine concentration had changed by 0.01±0.07 nmol/l in liver and by 0.21±0.07 nmol/l in kidney transplant recipients (p<0.05 between groups after 30-40 minutes of water drinking. While blood pressure and systemic vascular resistance increased in both groups, the responses tended to be attenuated in liver transplant recipients. Our findings support the idea that osmosensitive hepatic afferents are involved in water drinking-induced sympathetic activation in human subjects.ClinicalTrials.gov NCT01237431.

Meningeal norepinephrine produces headache behaviors in rats via actions both on dural afferents and fibroblasts.

Science.gov (United States)

Wei, Xiaomei; Yan, Jin; Tillu, Dipti; Asiedu, Marina; Weinstein, Nicole; Melemedjian, Ohannes; Price, Theodore; Dussor, Gregory

2015-10-01

Stress is commonly reported to contribute to migraine although mechanisms by which this may occur are not fully known. The purpose of these studies was to examine whether norepinephrine (NE), the primary sympathetic efferent transmitter, acts on processes in the meninges that may contribute to the pain of migraine. NE was applied to rat dura using a behavioral model of headache. Primary cultures of rat trigeminal ganglia retrogradely labeled from the dura mater and of rat dural fibroblasts were prepared. Patch-clamp electrophysiology, Western blot, and ELISA were performed to examine the effects of NE. Conditioned media from NE-treated fibroblast cultures was applied to the dura using the behavioral headache model. Dural injection both of NE and media from NE-stimulated fibroblasts caused cutaneous facial and hindpaw allodynia in awake rats. NE application to cultured dural afferents increased action potential firing in response to current injections. Application of NE to dural fibroblasts increased phosphorylation of ERK and caused the release of interleukin-6 (IL-6). These data demonstrate that NE can contribute to pro-nociceptive signaling from the meninges via actions on dural afferents and dural fibroblasts. Together, these actions of NE may contribute to the headache phase of migraine. © International Headache Society 2015.

Liver Afferents Contribute to Water Drinking-Induced Sympathetic Activation in Human Subjects: A Clinical Trial

Science.gov (United States)

May, Marcus; Gueler, Faikah; Barg-Hock, Hannelore; Heiringhoff, Karl-Heinz; Engeli, Stefan; Heusser, Karsten; Diedrich, André; Brandt, André; Strassburg, Christian P.; Tank, Jens; Sweep, Fred C. G. J.; Jordan, Jens

2011-01-01

Water drinking acutely increases sympathetic activity in human subjects. In animals, the response appears to be mediated through transient receptor potential channel TRPV4 activation on osmosensitive hepatic spinal afferents, described as osmopressor response. We hypothesized that hepatic denervation attenuates water drinking-induced sympathetic activation. We studied 20 liver transplant recipients (44±2.6 years, 1.2±0.1 years post transplant) as model of hepatic denervation and 20 kidney transplant recipients (43±2.6 years, 0.8±0.1 years post transplant) as immunosuppressive drug matched control group. Before and after 500 ml water ingestion, we obtained venous blood samples for catecholamine analysis. We also monitored brachial and finger blood pressure, ECG, and thoracic bioimpedance. Plasma norepinephrine concentration had changed by 0.01±0.07 nmol/l in liver and by 0.21±0.07 nmol/l in kidney transplant recipients (pwater drinking. While blood pressure and systemic vascular resistance increased in both groups, the responses tended to be attenuated in liver transplant recipients. Our findings support the idea that osmosensitive hepatic afferents are involved in water drinking-induced sympathetic activation in human subjects. Trial Registration ClinicalTrials.gov NCT01237431 PMID:22016786

Gastric electrical stimulation decreases gastric distension-induced central nociception response through direct action on primary afferents.

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Wassila Ouelaa

Full Text Available BACKGROUND & AIMS: Gastric electrical stimulation (GES is an effective therapy to treat patients with chronic dyspepsia refractory to medical management. However, its mechanisms of action remain poorly understood. METHODS: Gastric pain was induced by performing gastric distension (GD in anesthetized rats. Pain response was monitored by measuring the pseudo-affective reflex (e.g., blood pressure variation, while neuronal activation was determined using c-fos immunochemistry in the central nervous system. Involvement of primary afferents was assessed by measuring phosphorylation of ERK1/2 in dorsal root ganglia. RESULTS: GES decreased blood pressure variation induced by GD, and prevented GD-induced neuronal activation in the dorsal horn of the spinal cord (T9-T10, the nucleus of the solitary tract and in CRF neurons of the hypothalamic paraventricular nucleus. This effect remained unaltered within the spinal cord when sectioning the medulla at the T5 level. Furthermore, GES prevented GD-induced phosphorylation of ERK1/2 in dorsal root ganglia. CONCLUSIONS: GES decreases GD-induced pain and/or discomfort likely through a direct modulation of gastric spinal afferents reducing central processing of visceral nociception.

Function of skeletal muscle tissue formed after myoblast transplantation into irradiated mouse muscles.

Science.gov (United States)

Wernig, A; Zweyer, M; Irintchev, A

2000-01-15

1. Pretreatment of muscles with ionising radiation enhances tissue formation by transplanted myoblasts but little is known about the effects on muscle function. We implanted myoblasts from an expanded, male-donor-derived, culture (i28) into X-ray irradiated (16 Gy) or irradiated and damaged soleus muscles of female syngeneic mice (Balb/c). Three to 6 months later the isometric contractile properties of the muscles were studied in vitro, and donor nuclei were visualised in muscle sections with a Y chromosome-specific DNA probe. 2. Irradiated sham-injected muscles had smaller masses than untreated solei and produced less twitch and tetanic force (all by about 18 %). Injection of 106 myoblasts abolished these deficiencies and innervation appeared normal. 3. Cryodamage of irradiated solei produced muscle remnants with few (1-50) or no fibres. Additional myoblast implantation led to formation of large muscles (25 % above normal) containing numerous small-diameter fibres. Upon direct electrical stimulation, these muscles produced considerable twitch (53 % of normal) and tetanic forces (35 % of normal) but innervation was insufficient as indicated by weak nerve-evoked contractions and elevated ACh sensitivity. 4. In control experiments on irradiated muscles, reinnervation was found to be less complete after botulinum toxin paralysis than after nerve crush indicating that proliferative arrest of irradiated Schwann cells may account for the observed innervation deficits. 5. Irradiation appears to be an effective pretreatment for improving myoblast transplantation. The injected cells can even produce organised contractile tissue replacing whole muscle. However, impaired nerve regeneration limits the functional performance of the new muscle.

Muscle Atrophy Reversed by Growth Factor Activation of Satellite Cells in a Mouse Muscle Atrophy Model

DEFF Research Database (Denmark)

Hauerslev, Simon; Vissing, John; Krag, Thomas O

2014-01-01

mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength.......Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory...... factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth...

New twist on artificial muscles.

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Haines, Carter S; Li, Na; Spinks, Geoffrey M; Aliev, Ali E; Di, Jiangtao; Baughman, Ray H

2016-10-18

Lightweight artificial muscle fibers that can match the large tensile stroke of natural muscles have been elusive. In particular, low stroke, limited cycle life, and inefficient energy conversion have combined with high cost and hysteretic performance to restrict practical use. In recent years, a new class of artificial muscles, based on highly twisted fibers, has emerged that can deliver more than 2,000 J/kg of specific work during muscle contraction, compared with just 40 J/kg for natural muscle. Thermally actuated muscles made from ordinary polymer fibers can deliver long-life, hysteresis-free tensile strokes of more than 30% and torsional actuation capable of spinning a paddle at speeds of more than 100,000 rpm. In this perspective, we explore the mechanisms and potential applications of present twisted fiber muscles and the future opportunities and challenges for developing twisted muscles having improved cycle rates, efficiencies, and functionality. We also demonstrate artificial muscle sewing threads and textiles and coiled structures that exhibit nearly unlimited actuation strokes. In addition to robotics and prosthetics, future applications include smart textiles that change breathability in response to temperature and moisture and window shutters that automatically open and close to conserve energy.

Proprioceptive Feedback through a Neuromorphic Muscle Spindle Model

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Lorenzo Vannucci

2017-06-01

Full Text Available Connecting biologically inspired neural simulations to physical or simulated embodiments can be useful both in robotics, for the development of a new kind of bio-inspired controllers, and in neuroscience, to test detailed brain models in complete action-perception loops. The aim of this work is to develop a fully spike-based, biologically inspired mechanism for the translation of proprioceptive feedback. The translation is achieved by implementing a computational model of neural activity of type Ia and type II afferent fibers of muscle spindles, the primary source of proprioceptive information, which, in mammals is regulated through fusimotor activation and provides necessary adjustments during voluntary muscle contractions. As such, both static and dynamic γ-motoneurons activities are taken into account in the proposed model. Information from the actual proprioceptive sensors (i.e., motor encoders is then used to simulate the spindle contraction and relaxation, and therefore drive the neural activity. To assess the feasibility of this approach, the model is implemented on the NEST spiking neural network simulator and on the SpiNNaker neuromorphic hardware platform and tested on simulated and physical robotic platforms. The results demonstrate that the model can be used in both simulated and real-time robotic applications to translate encoder values into a biologically plausible neural activity. Thus, this model provides a completely spike-based building block, suitable for neuromorphic platforms, that will enable the development of sensory-motor closed loops which could include neural simulations of areas of the central nervous system or of low-level reflexes.

Receptor units responding to movement in the octopus mantle.

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Boyle, P R

1976-08-01

1. A preparation of the mantle of Octopus which is inverted over a solid support and which exposes the stellate ganglion and associated nerves is described. 2. Afferent activity can be recorded from stellar nerves following electrical stimulation of the pallial nerve. The latency and frequency of the phasic sensory response is correlated with the contraction of the mantle musculature. 3. It is proposed that receptors cells located in the muscle, and their activity following mantle contraction, form part of a sensory feedback system in the mantle. Large, multipolar nerve cells that were found between the two main layers of circular muscle in the mantle could be such receptors.

What Is an Artificial Muscle? A Systemic Approach.

OpenAIRE

Bertrand Tondu

2015-01-01

Artificial muscles define a large category of actuators we propose to analyze in a systemic framework by considering any artificial muscle as an open-loop stable system for any output which represents an artificial muscle dimension resulting from its “contraction”, understood in a broad meaning. This approach makes it possible to distinguish the artificial muscle from other actuators and to specify an original model for a linear artificial muscle, according to the theory of linear systems. Su...

Artificial muscles from fishing line and sewing thread.

Science.gov (United States)

Haines, Carter S; Lima, Márcio D; Li, Na; Spinks, Geoffrey M; Foroughi, Javad; Madden, John D W; Kim, Shi Hyeong; Fang, Shaoli; Jung de Andrade, Mônica; Göktepe, Fatma; Göktepe, Özer; Mirvakili, Seyed M; Naficy, Sina; Lepró, Xavier; Oh, Jiyoung; Kozlov, Mikhail E; Kim, Seon Jeong; Xu, Xiuru; Swedlove, Benjamin J; Wallace, Gordon G; Baughman, Ray H

2014-02-21

The high cost of powerful, large-stroke, high-stress artificial muscles has combined with performance limitations such as low cycle life, hysteresis, and low efficiency to restrict applications. We demonstrated that inexpensive high-strength polymer fibers used for fishing line and sewing thread can be easily transformed by twist insertion to provide fast, scalable, nonhysteretic, long-life tensile and torsional muscles. Extreme twisting produces coiled muscles that can contract by 49%, lift loads over 100 times heavier than can human muscle of the same length and weight, and generate 5.3 kilowatts of mechanical work per kilogram of muscle weight, similar to that produced by a jet engine. Woven textiles that change porosity in response to temperature and actuating window shutters that could help conserve energy were also demonstrated. Large-stroke tensile actuation was theoretically and experimentally shown to result from torsional actuation.

The projection and synaptic organisation of NTS afferent connections with presympathetic neurons, GABA and nNOS neurons in the paraventricular nucleus of the hypothalamus

Science.gov (United States)

Affleck, V.S.; Coote, J.H.; Pyner, S.

2012-01-01

Elevated sympathetic nerve activity, strongly associated with cardiovascular disease, is partly generated from the presympathetic neurons of the paraventricular nucleus of the hypothalamus (PVN). The PVN-presympathetic neurons regulating cardiac and vasomotor sympathetic activity receive information about cardiovascular status from receptors in the heart and circulation. These receptors signal changes via afferent neurons terminating in the nucleus tractus solitarius (NTS), some of which may result in excitation or inhibition of PVN-presympathetic neurons. Understanding the anatomy and neurochemistry of NTS afferent connections within the PVN could provide important clues to the impairment in homeostasis cardiovascular control associated with disease. Transynaptic labelling has shown the presence of neuronal nitric oxide synthase (nNOS)-containing neurons and GABA interneurons that terminate on presympathetic PVN neurons any of which may be the target for NTS afferents. So far NTS connections to these diverse neuronal pools have not been demonstrated and were investigated in this study. Anterograde (biotin dextran amine – BDA) labelling of the ascending projection from the NTS and retrograde (fluorogold – FG or cholera toxin B subunit – CTB) labelling of PVN presympathetic neurons combined with immunohistochemistry for GABA and nNOS was used to identify the terminal neuronal targets of the ascending projection from the NTS. It was shown that NTS afferent terminals are apposed to either PVN-GABA interneurons or to nitric oxide producing neurons or even directly to presympathetic neurons. Furthermore, there was evidence that some NTS axons were positive for vesicular glutamate transporter 2 (vGLUT2). The data provide an anatomical basis for the different functions of cardiovascular receptors that mediate their actions via the NTS–PVN pathways. PMID:22698695

Two horizontal rectus eye muscle surgery combined with botulinum toxin for the treatment of very large angle esotropia. A pilot study.

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Khan, Arif O

2005-01-01

To evaluate the effectiveness of a proposed new protocol for the primary treatment for very large angle esotropia: two muscle horizontal rectus muscle surgery with simultaneous botulinum toxin A injection in a small pilot study. Eight patients who had esotropia at near (ET') greater than 60 prism diopters (in actuality 70 to 100 prism diopters ET') underwent 2 muscle horizontal rectus surgery with simultaneous botulinum toxin A injection of the medial rectus intraoperatively. This was the only surgical procedure for all patients included in this report. Seven patients underwent bilateral medial rectus recession and bilateral injection, and one patient underwent a unilateral medial rectus recession / lateral rectus resection procedure with unilateral medial rectus injection. Postoperatively, 6 of the 8 patients demonstrated residual esotropia at near of less than 10 prism diopters and were considered "successful" by the conventional criteria of binocular alignment within 8 prism diopters of orthotropia. Two undercorrections occurred in patients with 100 and 85 prism diopters of preop ET' respectively. But 3 other patients with such large deviations had satisfactory results. All patients and families were satisfied with postoperative binocular alignment, so no further surgery was undertaken. The patient who underwent unilateral surgery had the least surgical effect and was the largest undercorrection, probably because only one medial rectus received a Botox injection. Considering only the bilateral cases, results were "successful" in 6 of 7 cases. Most patients suffered an extended period of Botox induced exotropia in the postop' period before recovery from the paresis. One patient had a transient, successfully treated, postoperative strabismic amblyopia while exotropic. Bilateral medial rectus recession with simultaneous botulinum injection is a safe and effective primary surgical procedure for very large angle esotropia. A more extensive study is indicated to

Embryohistiogenesis of Vascular Tufts of Glomeruli: a Possible Hypothesis.

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Dabiri, Shahriar; Moeini-Aghtaei, Mohammad Mehdi; Dabiri, Bahram

2017-10-01

Embryogenesis of the kidney glomeruli, especially its vascular component, has not been well documented. Glomeruli capillary tuft is surrounded and enveloped by visceral epithelial cells, which is a unique portal system that connects afferent with efferent arteriole without interaction with venular circulation. We hypothesized that the portal system embryologically has developed by extension of the intima of afferent arteriole into the stroma of glomerulus. We also hypothesized that juxtaglomeruli apparatus was developed from remnants of smooth muscle cells of the media of afferent arteriole at the anastomosing site with the Bowman capsule entrance. We studied 5 human fetal kidneys by hematoxylin-eosin, periodic acid-Schiff, and immunoperoxidase staining techniques. Hematoxylin-eosin staining of fetal kidney showed presence of erythrocytes in early vesicle form of glomeruli that was confirmed by immunohistochemical staining with CD31, smooth muscle actin, and CD34 markers. These stains showed extension of extraglomerular arterioles to the glomeruli. Periodic acid-Schiff staining showed also the continuity of the basement membrane in extraglomeruli and internal glomerular vascular tufts. This study shows that there is a relationship between the metanephric blast cells and major vessel critical for angiogenesis. When afferent arteriole come in contact with the immature glomeruli, its intima migrates into the glomerular tuft to form intraglomerular capillary system, while its smooth muscle remains at the entrance orifice and develops juxtaglomerular apparatus cells.

Afferent connections of nervus facialis and nervus glossopharyngeus in the pigeon (Columba livia) and their role in feeding behavior.

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Dubbeldam, J L

1984-01-01

The afferent connections of the facial nerve and glossopharyngeal nerve in the pigeon have been studied with the Fink-Heimer I method after ganglion lesions. The nucleus ventrolateralis anterior of the solitary complex and an indistinct cell group S VII medial to the nucleus interpolaris of the descending trigeminal tract are the terminal fields for facial afferents. The n. ventrolateralis anterior also receives an important projection from the distal glossopharyngeal ganglion. Other projection areas of this ganglion are the n. presulcalis , n. centralis anterior, n. intermedius anterior and the parasolitary nucleus. Both ganglia have only ipsilateral projections. A lesion in the jugular ganglion complex causes degeneration throughout the ipsilateral solitary complex, in the contralateral n. commissuralis and n. centralis posterior and in the n. cuneatus externus. The lack of a substantial contribution to the trigeminal system is ascribed to the absence of mechanoreceptors in the tongue. The implications for the organization of neuronal pathways related to the feeding behavior are discussed.

Lack of on-going adaptations in the soleus muscle activity during walking in patients affected by large-fiber neuropathy

DEFF Research Database (Denmark)

Nazarena, Mazzaro; Grey, Michael James; Sinkjær, Thomas

2005-01-01

The aim of this study was to investigate the contribution of feedback from large-diameter sensory fibers to the adaptation of soleus muscle activity after small ankle trajectory modifications during human walking. Small-amplitude and slow-velocity ankle dorsiflexion enhancements and reductions were...... applied during the stance phase of the gait cycle to mimic the normal variability of the ankle trajectory during walking. Patients with demyelination of large sensory fibers (Charcot-Marie-Tooth type 1A and antibodies to myelin-associated glycoprotein neuropathy) and age-matched controls participated...... duration (P ankle dorsiflexion was, respectively, enhanced or reduced. In the patients, the soleus EMG increased during the dorsiflexion...

Duodenal activation of cAMP-dependent protein kinase induces vagal afferent firing and lowers glucose production in rats.

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Rasmussen, Brittany A; Breen, Danna M; Luo, Ping; Cheung, Grace W C; Yang, Clair S; Sun, Biying; Kokorovic, Andrea; Rong, Weifang; Lam, Tony K T

2012-04-01

The duodenum senses nutrients to maintain energy and glucose homeostasis, but little is known about the signaling and neuronal mechanisms involved. We tested whether duodenal activation of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase A (PKA) is sufficient and necessary for cholecystokinin (CCK) signaling to trigger vagal afferent firing and regulate glucose production. In rats, we selectively activated duodenal PKA and evaluated changes in glucose kinetics during the pancreatic (basal insulin) pancreatic clamps and vagal afferent firing. The requirement of duodenal PKA signaling in glucose regulation was evaluated by inhibiting duodenal activation of PKA in the presence of infusion of the intraduodenal PKA agonist (Sp-cAMPS) or CCK1 receptor agonist (CCK-8). We also assessed the involvement of a neuronal network and the metabolic impact of duodenal PKA activation in rats placed on high-fat diets. Intraduodenal infusion of Sp-cAMPS activated duodenal PKA and lowered glucose production, in association with increased vagal afferent firing in control rats. The metabolic and neuronal effects of duodenal Sp-cAMPS were negated by coinfusion with either the PKA inhibitor H89 or Rp-CAMPS. The metabolic effect was also negated by coinfusion with tetracaine, molecular and pharmacologic inhibition of NR1-containing N-methyl-d-aspartate (NMDA) receptors within the dorsal vagal complex, or hepatic vagotomy in rats. Inhibition of duodenal PKA blocked the ability of duodenal CCK-8 to reduce glucose production in control rats, whereas duodenal Sp-cAMPS bypassed duodenal CCK resistance and activated duodenal PKA and lowered glucose production in rats on high-fat diets. We identified a neural glucoregulatory function of duodenal PKA signaling. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

Ia Afferent input alters the recruitment thresholds and firing rates of single human motor units.

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Grande, G; Cafarelli, E

2003-06-01

Vibration of the patellar tendon recruits motor units in the knee extensors via excitation of muscle spindles and subsequent Ia afferent input to the alpha-motoneuron pool. Our first purpose was to determine if the recruitment threshold and firing rate of the same motor unit differed when recruited involuntarily via reflex or voluntarily via descending spinal pathways. Although Ia input is excitatory to the alpha-motoneuron pool, it has also been shown paradoxically to inhibit itself. Our second purpose was to determine if vibration of the patellar tendon during a voluntary knee extension causes a change in the firing rate of already recruited motor units. In the first protocol, 10 subjects voluntarily reproduced the same isometric force profile of the knee extensors that was elicited by vibration of the patellar tendon. Single motor unit recordings from the vastus lateralis (VL) were obtained with tungsten microelectrodes and unitary behaviour was examined during both reflex and voluntary knee extensions. Recordings from 135 single motor units showed that both recruitment thresholds and firing rates were lower during reflex contractions. In the second protocol, 7 subjects maintained a voluntary knee extension at 30 N for approximately 40-45 s. Three bursts of patellar tendon vibration were superimposed at regular intervals throughout the contraction and changes in the firing rate of already recruited motor units were examined. A total of 35 motor units were recorded and each burst of superimposed vibration caused a momentary reduction in the firing rates and recruitment of additional units. Our data provide evidence that Ia input modulates the recruitment thresholds and firing rates of motor units providing more flexibility within the neuromuscular system to grade force at low levels of force production.

The Human Skeletal Muscle Proteome Project

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Gonzalez-Freire, Marta; Semba, Richard D.; Ubaida-Mohien, Ceereena

2017-01-01

Skeletal muscle is a large organ that accounts for up to half the total mass of the human body. A progressive decline in muscle mass and strength occurs with ageing and in some individuals configures the syndrome of ‘sarcopenia’, a condition that impairs mobility, challenges autonomy, and is a ri...

Influence of limb temperature on cutaneous silent periods.

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Kofler, Markus; Valls-Solé, Josep; Vasko, Peter; Boček, Václav; Štetkárová, Ivana

2014-09-01

The cutaneous silent period (CSP) is a spinal inhibitory reflex mediated by small-diameter afferents (A-delta fibers) and large-diameter efferents (alpha motoneurons). The effect of limb temperature on CSPs has so far not been assessed. In 27 healthy volunteers (11 males; age 22-58 years) we recorded median nerve motor and sensory action potentials, median nerve F-wave and CSPs induced by noxious digit II stimulation in thenar muscles in a baseline condition at room temperature, and after randomly submersing the forearm in 42 °C warm or 15 °C cold water for 20 min each. In cold limbs, distal and proximal motor and sensory latencies as well as F-wave latencies were prolonged. Motor and sensory nerve conduction velocities were reduced. Compound motor and sensory nerve action potential amplitudes did not differ significantly from baseline. CSP onset and end latencies were more delayed than distal and proximal median nerve motor and sensory latencies, whereas CSP duration was not affected. In warm limbs, opposite but smaller changes were seen in nerve conduction studies and CSPs. The observed CSP shift "en bloc" towards longer latencies without affecting CSP duration during limb cooling concurs with slower conduction velocity in both afferent and efferent fibers. Disparate conduction slowing in afferents and efferents, however, suggests that nociceptive EMG suppression is mediated by fibers of different size in the afferent than in the efferent arm, indirectly supporting the contribution of A-delta fibers as the main afferent input. Limb temperature should be taken into account when testing CSPs in the clinical setting, as different limb temperatures affect CSP latencies more than large-diameter fiber conduction function. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

[Nosological classification and assessment of muscle dysmorphia].

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Babusa, Bernadett; Túry, Ferenc

2011-01-01

Muscle dysmorphia is a recently described psychiatric disorder, characterized by a pathological preoccupation with muscle size. In spite of their huge muscles, muscle dysmorphia sufferers believe that they are insufficiently large and muscular therefore would like to be bigger and more muscular. Male bodybuilders are at high-risk for the disorder. The nosological classification of muscle dysmorphia has been changed over the years. However, consensus has not emerged so far. Most of the ongoing debate has conceptualized muscle dysmorphia as an eating disorder, obsessive-compulsive disorder and body dysmorphic disorder. There are a number of arguments for and againts. In the present study the authors do not take a position on the diagnostic classification of muscle dysmorphia. The purpose of the study is to review the present approaches relating to the diagnostic classification of muscle dysmporphia. Many different questionnaires were developed for the assessment of muscle dysmorphia. Currently, there is a lack of assessment methods measuring muscle dysmorphia symptoms in Hungary. As a secondary purpose the study also presents the Hungarian version of the Muscle Appearance Satisfaction Scale (Mayville et al., 2002).

Hydraulically actuated artificial muscles

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Meller, M. A.; Tiwari, R.; Wajcs, K. B.; Moses, C.; Reveles, I.; Garcia, E.

2012-04-01

Hydraulic Artificial Muscles (HAMs) consisting of a polymer tube constrained by a nylon mesh are presented in this paper. Despite the actuation mechanism being similar to its popular counterpart, which are pneumatically actuated (PAM), HAMs have not been studied in depth. HAMs offer the advantage of compliance, large force to weight ratio, low maintenance, and low cost over traditional hydraulic cylinders. Muscle characterization for isometric and isobaric tests are discussed and compared to PAMs. A model incorporating the effect of mesh angle and friction have also been developed. In addition, differential swelling of the muscle on actuation has also been included in the model. An application of lab fabricated HAMs for a meso-scale robotic system is also presented.

Muscle Deoxygenation Causes Muscle Fatigue

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Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

1999-01-01

Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

In situ hybridisation of a large repertoire of muscle-specific transcripts in fish larvae: the new superficial slow-twitch fibres exhibit characteristics of fast-twitch differentiation.

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Chauvigné, F; Ralliere, C; Cauty, C; Rescan, P Y

2006-01-01

Much of the present information on muscle differentiation in fish concerns the early embryonic stages. To learn more about the maturation and the diversification of the fish myotomal fibres in later stages of ontogeny, we investigated, by means of in situ hybridisation, the developmental expression of a large repertoire of muscle-specific genes in trout larvae from hatching to yolk resorption. At hatching, transcripts for fast and slow muscle protein isoforms, namely myosins, tropomyosins, troponins and myosin binding protein C were present in the deep fast and the superficial slow areas of the myotome, respectively. During myotome expansion that follows hatching, the expression of fast isoforms became progressively confined to the borders of the fast muscle mass, whereas, in contrast, slow muscle isoform transcripts were uniformly expressed in all the slow fibres. Transcripts for several enzymes involved in oxidative metabolism such as citrate synthase, cytochrome oxidase component IV and succinate dehydrogenase, were present throughout the whole myotome of hatching embryos but in later stages became concentrated in slow fibre as well as in lateral fast fibres. Surprisingly, the slow fibres that are added externally to the single superficial layer of the embryonic (original) slow muscle fibres expressed not only slow twitch muscle isoforms but also, transiently, a subset of fast twitch muscle isoforms including MyLC1, MyLC3, MyHC and myosin binding protein C. Taken together these observations show that the growth of the myotome of the fish larvae is associated with complex patterns of muscular gene expression and demonstrate the unexpected presence of fast muscle isoform-expressing fibres in the most superficial part of the slow muscle.

Bio-inspired, Moisture-Powered Hybrid Carbon Nanotube Yarn Muscles.

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Kim, Shi Hyeong; Kwon, Cheong Hoon; Park, Karam; Mun, Tae Jin; Lepró, Xavier; Baughman, Ray H; Spinks, Geoffrey M; Kim, Seon Jeong

2016-03-14

Hygromorph artificial muscles are attractive as self-powered actuators driven by moisture from the ambient environment. Previously reported hygromorph muscles have been largely limited to bending or torsional motions or as tensile actuators with low work and energy densities. Herein, we developed a hybrid yarn artificial muscle with a unique coiled and wrinkled structure, which can be actuated by either changing relative humidity or contact with water. The muscle provides a large tensile stroke (up to 78%) and a high maximum gravimetric work capacity during contraction (2.17 kJ kg(-1)), which is over 50 times that of the same weight human muscle and 5.5 times higher than for the same weight spider silk, which is the previous record holder for a moisture driven muscle. We demonstrate an automatic ventilation system that is operated by the tensile actuation of the hybrid muscles caused by dew condensing on the hybrid yarn. This self-powered humidity-controlled ventilation system could be adapted to automatically control the desired relative humidity of an enclosed space.

Oscillatory blood pressure response to the onset of cycling exercise in men

DEFF Research Database (Denmark)

Barbosa, Thales C; Fernandes, Igor A; Magalhães-Jr, Nisval

2015-01-01

to this pattern is unclear. What is the main finding and its importance? We demonstrate that attenuation of group III/IV muscle afferent feedback by spinal fentanyl impairs the pressor response after 10 s of moderate leg cycling exercise, but this afferent feedback does not appear to be necessary for induction...... of the oscillatory pattern of blood pressure at the onset of exercise. We investigated whether attenuation of the central projections of group III/IV skeletal muscle afferents via lumbar intrathecal administration of the μ-opioid receptor agonist fentanyl affects the oscillatory blood pressure (BP) response...... to the onset of dynamic exercise. Eight healthy, recreationally active men (28 ± 3 years old) performed 40 s of cycling at 80 W (60 r.p.m.) before (control) and after fentanyl administration, while heart rate, stroke volume, cardiac output, systolic, mean and diastolic BP and total vascular conductance were...

Assessment of muscle function using hybrid PET/MRI

DEFF Research Database (Denmark)

Haddock, Bryan; Holm, Søren; Poulsen, Jákup M.

2017-01-01

-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with 18F-FDG PET/MRI and muscle groups were evaluated for increases in 18F-FDG uptake and MRI T2......Purpose: The aim of this study was to determine the relationship between relative glucose uptake and MRI T2 changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans. Methods: Ten young healthy recreationally active men (age 21 – 28 years) were injected with 18F...... values. Results: A significant linear correlation between 18F-FDG uptake and changes in muscle T2 (R2 = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between 18F-FDG uptake...

Comparative anatomy and muscle architecture of selected hind limb muscles in the Quarter Horse and Arab.

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Crook, T C; Cruickshank, S E; McGowan, C M; Stubbs, N; Wakeling, J M; Wilson, A M; Payne, R C

2008-02-01

The Quarter Horse (bred for acceleration) and the Arab (bred for endurance) are situated at either end of the equine athletic spectrum. Studies into the form and function of the leg muscles in human sprint and endurance runners have demonstrated that differences exist in their muscle architecture. It is not known whether similar differences exist in the horse. Six Quarter Horse and six Arab fresh hind limb cadavers were dissected to gain information on the muscle mass and architecture of the following muscles: gluteus medius; biceps femoris; semitendinosus; vastus lateralis; gastrocnemius; tibialis cranialis and extensor digitorum longus. Specifically, muscle mass, fascicle length and pennation angle were quantified and physiological cross-sectional area (PCSA) and maximum isometric force were estimated. The hind limb muscles of the Quarter Horse were of a significantly greater mass, but had similar fascicle lengths and pennation angles when compared with those of the Arab; this resulted in the Quarter Horse hind limb muscles having greater PCSAs and hence greater isometric force potential. This study suggests that Quarter Horses as a breed inherently possess large strong hind limb muscles, with the potential to accelerate their body mass more rapidly than those of the Arab.

Sensitization of dural afferents underlies migraine-related behavior following meningeal application of interleukin-6 (IL-6

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Yan Jin

2012-01-01

Full Text Available Abstract Background Migraine headache is one of the most common neurological disorders, but the pathophysiology contributing to migraine is poorly understood. Intracranial interleukin-6 (IL-6 levels have been shown to be elevated during migraine attacks, suggesting that this cytokine may facilitate pain signaling from the meninges and contribute to the development of headache. Methods Cutaneous allodynia was measured in rats following stimulation of the dura with IL-6 alone or in combination with the MEK inhibitor, U0126. The number of action potentials and latency to the first action potential peak in response to a ramp current stimulus as well as current threshold were measured in retrogradely-labeled dural afferents using patch-clamp electrophysiology. These recordings were performed in the presence of IL-6 alone or in combination with U0126. Association between ERK1 and Nav1.7 following IL-6 treatment was also measured by co-immunoprecipitation. Results Here we report that in awake animals, direct application of IL-6 to the dura produced dose-dependent facial and hindpaw allodynia. The MEK inhibitor U0126 blocked IL-6-induced allodynia indicating that IL-6 produced this behavioral effect through the MAP kinase pathway. In trigeminal neurons retrogradely labeled from the dura, IL-6 application decreased the current threshold for action potential firing. In response to a ramp current stimulus, cells treated with IL-6 showed an increase in the numbers of action potentials and a decrease in latency to the first spike, an effect consistent with phosphorylation of the sodium channel Nav1.7. Pretreatment with U0126 reversed hyperexcitability following IL-6 treatment. Moreover, co-immunoprecipitation experiments demonstrated an increased association between ERK1 and Nav1.7 following IL-6 treatment. Conclusions Our results indicate that IL-6 enhances the excitability of dural afferents likely via ERK-mediated modulation of Nav1.7 and these responses

Ventromedial hypothalamic expression of Bdnf is required to establish normal patterns of afferent GABAergic connectivity and responses to hypoglycemia

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Anna Kamitakahara

2016-02-01

Full Text Available Objective: The ventromedial nucleus of the hypothalamus (VMH controls energy and glucose homeostasis through direct connections to a distributed network of nuclei in the hypothalamus, midbrain, and hindbrain. Structural changes in VMH circuit morphology have the potential to alter VMH function throughout life, however, molecular signals responsible for specifying its neural connections are not fully defined. The VMH contains a high density of neurons that express brain-derived neurotrophic factor (BDNF, a potent neurodevelopmental effector known to regulate neuronal survival, growth, differentiation, and connectivity in a number of neural systems. In the current study, we examined whether BDNF impacts the afferent and efferent connections of the VMH, as well as energy homeostatic function. Methods: To determine if BDNF is required for VMH circuit formation, a transgenic mouse model was used to conditionally delete Bdnf from steroidogenic factor 1 (SF1 expressing neurons of the VMH prior to the onset of establishing neural connections with other regions. Projections of SF1 expressing neurons were visualized with a genetically targeted fluorescent label and immunofluorescence was used to measure the density of afferents to SF1 neurons in the absence of BDNF. Physiological changes in body weight and circulating blood glucose were also evaluated in the mutant mice. Results: Our findings suggest that BDNF is required to establish normal densities of GABAergic afferents onto SF1 neurons located in the ventrolateral part of the VMH. Furthermore, loss of BDNF from VMH SF1 neurons results in impaired physiological responses to insulin-induced hypoglycemia. Conclusion: The results of this study indicate that BDNF is required for formation and/or maintenance of inhibitory inputs to SF1 neurons, with enduring effects on glycemic control. Author Video: Author Video Watch what authors say about their articles Keywords: Ventromedial nucleus of the hypothalamus

Adding muscle where you need it: non-uniform hypertrophy patterns in elite sprinters.

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Handsfield, G G; Knaus, K R; Fiorentino, N M; Meyer, C H; Hart, J M; Blemker, S S

2017-10-01

Sprint runners achieve much higher gait velocities and accelerations than average humans, due in part to large forces generated by their lower limb muscles. Various factors have been explored in the past to understand sprint biomechanics, but the distribution of muscle volumes in the lower limb has not been investigated in elite sprinters. In this study, we used non-Cartesian MRI to determine muscle sizes in vivo in a group of 15 NCAA Division I sprinters. Normalizing muscle sizes by body size, we compared sprinter muscles to non-sprinter muscles, calculated Z-scores to determine non-uniformly large muscles in sprinters, assessed bilateral symmetry, and assessed gender differences in sprinters' muscles. While limb musculature per height-mass was 22% greater in sprinters than in non-sprinters, individual muscles were not all uniformly larger. Hip- and knee-crossing muscles were significantly larger among sprinters (mean difference: 30%, range: 19-54%) but only one ankle-crossing muscle was significantly larger (tibialis posterior, 28%). Population-wide asymmetry was not significant in the sprint population but individual muscle asymmetries exceeded 15%. Gender differences in normalized muscle sizes were not significant. The results of this study suggest that non-uniform hypertrophy patterns, particularly large hip and knee flexors and extensors, are advantageous for fast sprinting. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Dense-body aggregates as plastic structures supporting tension in smooth muscle cells.

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Zhang, Jie; Herrera, Ana M; Paré, Peter D; Seow, Chun Y

2010-11-01

The wall of hollow organs of vertebrates is a unique structure able to generate active tension and maintain a nearly constant passive stiffness over a large volume range. These properties are predominantly attributable to the smooth muscle cells that line the organ wall. Although smooth muscle is known to possess plasticity (i.e., the ability to adapt to large changes in cell length through structural remodeling of contractile apparatus and cytoskeleton), the detailed structural basis for the plasticity is largely unknown. Dense bodies, one of the most prominent structures in smooth muscle cells, have been regarded as the anchoring sites for actin filaments, similar to the Z-disks in striated muscle. Here, we show that the dense bodies and intermediate filaments formed cable-like structures inside airway smooth muscle cells and were able to adjust the cable length according to cell length and tension. Stretching the muscle cell bundle in the relaxed state caused the cables to straighten, indicating that these intracellular structures were connected to the extracellular matrix and could support passive tension. These plastic structures may be responsible for the ability of smooth muscle to maintain a nearly constant tensile stiffness over a large length range. The finding suggests that the structural plasticity of hollow organs may originate from the dense-body cables within the smooth muscle cells.

Spinal cord stimulation paresthesia and activity of primary afferents.

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North, Richard B; Streelman, Karen; Rowland, Lance; Foreman, P Jay

2012-10-01

A patient with failed back surgery syndrome reported paresthesia in his hands and arms during a spinal cord stimulation (SCS) screening trial with a low thoracic electrode. The patient's severe thoracic stenosis necessitated general anesthesia for simultaneous decompressive laminectomy and SCS implantation for chronic use. Use of general anesthesia gave the authors the opportunity to characterize the patient's unusual distribution of paresthesia. During SCS implantation, they recorded SCS-evoked antidromic potentials at physiologically relevant amplitudes in the legs to guide electrode placement and in the arms as controls. Stimulation of the dorsal columns at T-8 evoked potentials in the legs (common peroneal nerves) and at similar thresholds, consistent with the sensation of paresthesia in the arms, in the right ulnar nerve. The authors' electrophysiological observations support observations by neuroanatomical specialists that primary afferents can descend several (in this case, at least 8) vertebral segments in the spinal cord before synapsing or ascending. This report thus confirms a physiological basis for unusual paresthesia distribution associated with thoracic SCS.

Function and morphology correlates of rectal nerve mechanoreceptors innervating the guinea pig internal anal sphincter.

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Lynn, P A; Brookes, S J H

2011-01-01

Mechanoreceptors to the internal anal sphincter (IAS) contribute to continence and normal defecation, yet relatively little is known about their function or morphology. We investigated the function and structure of mechanoreceptors to the guinea pig IAS. Extracellular recordings from rectal nerve branches to the IAS in vitro, combined with anterograde labeling of recorded nerve trunks, were used to characterize extrinsic afferent nerve endings activated by circumferential distension. Slowly adapting, stretch-sensitive afferents were recorded in rectal nerves to the IAS. Ten of 11 were silent under basal conditions and responded to circumferential stretch in a saturating linear manner. Rectal nerve afferents responded to compression with von Frey hairs with low thresholds (0.3-0.5 mN) and 3.4 ± 0.5 discrete, elongated mechanosensitive fields of innervation aligned parallel to circular muscle bundles (length = 62 ± 16 mm, n = 10). Anterogradely labeled rectal nerve axons typically passed through sparse irregular myenteric ganglia adjacent to the IAS, before ending in extensive varicose arrays within the circular muscle and, to a lesser extent, the longitudinal muscle overlying the IAS. Few (8%) IAS myenteric ganglia contained intraganglionic laminar endings. In eight preparations, mechanotransduction sites were mapped in combination with successful anterograde fills. Mechanotransduction sites were strongly associated with extensive fine varicose arrays within the circular muscle (P IAS are likely to correspond to extensive fine varicose arrays within the circular muscle. © 2010 Blackwell Publishing Ltd.

Muscular responses appear to be associated with existence of kinesthetic perception during combination of tendon co-vibration and motor imagery.

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Shibata, Eriko; Kaneko, Fuminari; Katayose, Masaki

2017-11-01

The afferent inputs from peripheral sensory receptors and efferent signals from the central nervous system that underlie intentional movement can contribute to kinesthetic perception. Previous studies have revealed that tendon vibration to wrist muscles elicits an excitatory response-known as the antagonist vibratory response-in muscles antagonistic to the vibrated muscles. Therefore, the present study aimed to further investigate the effect of tendon vibration combined with motor imagery on kinesthetic perception and muscular activation. Two vibrators were applied to the tendons of the left flexor carpi radialis and extensor carpi radialis. When the vibration frequency was the same between flexors and extensors, no participant perceived movement and no muscle activity was induced. When participants imagined flexing their wrists during tendon vibration, the velocity of perceptual flexion movement increased. Furthermore, muscle activity of the flexor increased only during motor imagery. These results demonstrate that kinesthetic perception can be induced during the combination of motor imagery and co-vibration, even with no experience of kinesthetic perception from an afferent input with co-vibration at the same frequency. Although motor responses were observed during combined co-vibration and motor imagery, no such motor responses were recorded during either co-vibration alone or motor imagery alone, suggesting that muscular responses during the combined condition are associated with kinesthetic perception. Thus, the present findings indicate that kinesthetic perception is influenced by the interaction between afferent input from muscle spindles and the efferent signals that underlie intentional movement. We propose that the physiological behavior resulting from kinesthetic perception affects the process of modifying agonist muscle activity, which will be investigated in a future study.

Afferent neuronal control of type-I gonadotropin releasing hormone (GnRH neurons in the human

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Erik eHrabovszky

2013-09-01

Full Text Available Understanding the regulation of the human menstrual cycle represents an important ultimate challenge of reproductive neuroendocrine research. However, direct translation of information from laboratory animal experiments to the human is often complicated by strikingly different and unique reproductive strategies and central regulatory mechanisms that can be present in even closely related animal species. In all mammals studied so far, type-I gonadotropin releasing hormone (GnRH synthesizing neurons form the final common output way from the hypothalamus in the neuroendocrine control of the adenohypophysis. Under various physiological and pathological conditions, hormonal and metabolic signals either regulate GnRH neurons directly or act on upstream neuronal circuitries to influence the pattern of pulsatile GnRH secretion into the hypophysial portal circulation. Neuronal afferents to GnRH cells convey important metabolic-, stress-, sex steroid-, lactational- and circadian signals to the reproductive axis, among other effects. This article gives an overview of the available neuroanatomical literature that described the afferent regulation of human GnRH neurons by peptidergic, monoaminergic and amino acidergic neuronal systems. Recent studies of human genetics provided evidence that central peptidergic signaling by kisspeptins and neurokinin B play particularly important roles in puberty onset and later, in the sex steroid-dependent feedback regulation of GnRH neurons. This review article places special emphasis on the topographic distribution, sexual dimorphism, aging-dependent neuroanatomical changes and plastic connectivity to GnRH neurons of the critically important human hypothalamic kisspeptin and neurokinin B systems.

Novel skeletal muscle ryanodine receptor mutation in a large Brazilian family with malignant hyperthermia.

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McWilliams, S; Nelson, T; Sudo, R T; Zapata-Sudo, G; Batti, M; Sambuughin, N

2002-07-01

Malignant hyperthermia (MH) is an autosomal dominant disorder that predisposes susceptible individuals to a potentially life-threatening crisis when exposed to commonly used anesthetics. Mutations in the skeletal muscle calcium release channel, ryanodine receptor (RYR1) are associated with MH in over 50% of affected families. Linkage analysis of the RYR1 gene region at 19q13 was performed in a large Brazilian family and a distinct disease co-segregating haplotype was revealed in the majority of members with diagnosis of MH. Subsequent sequencing of RYR1 mutational hot spots revealed a nucleotide substitution of C to T at position 7062, causing a novel amino acid change from Arg2355 to Cys associated with MH in the family. Haplotype analysis of the RYR1 gene area at 19q13 in the family with multiple MH members is an important tool in identification of genetic cause underlying this disease.

Whole-Brain Monosynaptic Afferent Inputs to Basal Forebrain Cholinergic System

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Rongfeng Hu

2016-10-01

Full Text Available The basal forebrain cholinergic system (BFCS robustly modulates many important behaviors, such as arousal, attention, learning and memory, through heavy projections to cortex and hippocampus. However, the presynaptic partners governing BFCS activity still remain poorly understood. Here, we utilized a recently developed rabies virus-based cell-type-specific retrograde tracing system to map the whole-brain afferent inputs of the BFCS. We found that the BFCS receives inputs from multiple cortical areas, such as orbital frontal cortex, motor cortex, and insular cortex, and that the BFCS also receives dense inputs from several subcortical nuclei related to motivation and stress, including lateral septum (LS, central amygdala (CeA, paraventricular nucleus of hypothalamus (PVH, dorsal raphe (DRN and parabrachial nucleus (PBN. Interestingly, we found that the BFCS receives inputs from the olfactory areas and the entorhinal-hippocampal system. These results greatly expand our knowledge about the connectivity of the mouse BFCS and provided important preliminary indications for future exploration of circuit function.

Association of occlusal interference-induced masseter muscle hyperalgesia and P2X3 receptors in the trigeminal subnucleus caudalis and midbrain periaqueductal gray.

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Sun, Shuzhen; Qi, Dong; Yang, Yingying; Ji, Ping; Kong, Jingjing; Wu, Qingting

2016-03-02

P2X3 receptor plays a role in nociception transmission of orofacial pain in temporomandibular disorder patients. A previous study found that P2X3 receptors in masseter muscle afferent neurons and the trigeminal ganglia were involved in masseter muscle pain induced by inflammation caused by chemical agents or eccentric muscle contraction. In this study, we attempted to investigate changes in P2X3 receptors in the trigeminal subnucleus caudalis (Vc) and midbrain periaqueductal gray (PAG) in relation to the hyperalgesia of masseter muscles induced by occlusal interference. Experimental occlusal interference by crown application was established in 30 rats and another 30 rats were treated as sham controls. On days 1, 3, 7, 14, and 28 after crown application, the mechanical pain threshold was examined by von-Frey filaments. The expression of the P2X3 receptor in Vc and PAG was investigated by immunohistochemistry and quantitative PCR. We found that mechanical pain threshold of bilateral masseter muscles decreased significantly after occlusal interference, which remained for the entire experimental period. The mRNA expression of the P2X3 receptor increased significantly and the number of P2X3R-positive neurons increased markedly in Vc and PAG accordingly. These results indicate that the upregulated expression of P2X3 receptors in Vc and PAG may contribute toward the development of orofacial pain induced by occlusal interference and P2X3 receptors in the PAG may play a key role in the supraspinal antiociception effect.

Thyroid Hormone Signaling in Male Mouse Skeletal Muscle Is Largely Independent of D2 in Myocytes

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Werneck-de-Castro, Joao P.; Fonseca, Tatiana L.; Ignacio, Daniele L.; Fernandes, Gustavo W.; Andrade-Feraud, Cristina M.; Lartey, Lattoya J.; Ribeiro, Marcelo B.; Ribeiro, Miriam O.; Gereben, Balazs

2015-01-01

The type 2 deiodinase (D2) activates the prohormone T4 to T3. D2 is expressed in skeletal muscle (SKM), and its global inactivation (GLOB-D2KO mice) reportedly leads to skeletal muscle hypothyroidism and impaired differentiation. Here floxed Dio2 mice were crossed with mice expressing Cre-recombinase under the myosin light chain 1f (cre-MLC) to disrupt D2 expression in the late developmental stages of skeletal myocytes (SKM-D2KO). This led to a loss of approximately 50% in D2 activity in neonatal and adult SKM-D2KO skeletal muscle and about 75% in isolated SKM-D2KO myocytes. To test the impact of Dio2 disruption, we measured soleus T3 content and found it to be normal. We also looked at the expression of T3-responsive genes in skeletal muscle, ie, myosin heavy chain I, α-actin, myosin light chain, tropomyosin, and serca 1 and 2, which was preserved in neonatal SKM-D2KO hindlimb muscles, at a time that coincides with a peak of D2 activity in control animals. In adult soleus the baseline level of D2 activity was about 6-fold lower, and in the SKM-D2KO soleus, the expression of only one of five T3-responsive genes was reduced. Despite this, adult SKM-D2KO animals performed indistinguishably from controls on a treadmill test, running for approximately 16 minutes and reached a speed of about 23 m/min; muscle strength was about 0.3 mN/m·g body weight in SKM-D2KO and control ankle muscles. In conclusion, there are multiple sources of D2 in the mouse SKM, and its role is limited in postnatal skeletal muscle fibers. PMID:26214036

Skeletal Muscle Regeneration, Repair and Remodelling in Aging: The Importance of Muscle Stem Cells and Vascularization.

Science.gov (United States)

Joanisse, Sophie; Nederveen, Joshua P; Snijders, Tim; McKay, Bryon R; Parise, Gianni

2017-01-01

Sarcopenia is the age-related loss of skeletal muscle mass and strength. Ultimately, sarcopenia results in the loss of independence, which imposes a large financial burden on healthcare systems worldwide. A critical facet of sarcopenia is the diminished ability for aged muscle to regenerate, repair and remodel. Over the years, research has focused on elucidating underlying mechanisms of sarcopenia and the impaired ability of muscle to respond to stimuli with aging. Muscle-specific stem cells, termed satellite cells (SC), play an important role in maintaining muscle health throughout the lifespan. It is well established that SC are essential in skeletal muscle regeneration, and it has been hypothesized that a reduction and/or dysregulation of the SC pool, may contribute to accelerated loss of skeletal muscle mass that is observed with advancing age. The preservation of skeletal muscle tissue and its ability to respond to stimuli may be impacted by reduced SC content and impaired function observed with aging. Aging is also associated with a reduction in capillarization of skeletal muscle. We have recently demonstrated that the distance between type II fibre-associated SC and capillaries is greater in older compared to younger adults. The greater distance between SC and capillaries in older adults may contribute to the dysregulation in SC activation ultimately impairing muscle's ability to remodel and, in extreme circumstances, regenerate. This viewpoint will highlight the importance of optimal SC activation in addition to skeletal muscle capillarization to maximize the regenerative potential of skeletal muscle in older adults. © 2016 S. Karger AG, Basel.

The spatiotemporal relationships between chondroitin sulfate proteoglycans and terminations of calcitonin gene related peptide and parvalbumin immunoreactive afferents in the spinal cord of mouse embryos.

Science.gov (United States)

Wang, Liqing; Yu, Chao; Wang, Jun; Zhao, Hui; Chan, Sun-On

2017-08-10

Chondroitin sulfate (CS) proteoglycans (PGs) are a family of complex molecules in the extracellular matrix and cell surface that regulate axon growth and guidance during development of the central nervous system. In this study, the expression of CSPGs was investigated in the mouse spinal cord at late embryonic and neonatal stages using CS-56 antibody. CS immunoreactivity was observed abundantly in ventral regions of spinal cord of embryonic day (E) 15 embryos. At E16 to E18, CS expression spread dorsally, but never reached the superficial layers of the dorsal horn. This pattern was maintained until postnatal day 4, the latest stage examined. Antibodies against calcitonin gene related peptide (CGRP) and parvalbumin (PV) were employed to label primary afferents from nociceptors and proprioceptors, respectively. CGRP-immunoreactive fibers terminated in the superficial regions of the dorsal horn where CSPGs were weakly expressed, whereas PV-immunoreactive fibers were found in CSPG-rich regions in the ventral horn. Therefore, we conclude that CS expression is spatiotemporally regulated in the spinal cord, which correlates to the termination of sensory afferents. This pattern suggests a role of CSPGs on patterning afferents in the spinal cord, probably through a differential response of axons to these growth inhibitory molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

Cardiac troponin T and fast skeletal muscle denervation in ageing.

Science.gov (United States)

Xu, Zherong; Feng, Xin; Dong, Juan; Wang, Zhong-Min; Lee, Jingyun; Furdui, Cristina; Files, Daniel Clark; Beavers, Kristen M; Kritchevsky, Stephen; Milligan, Carolanne; Jin, Jian-Ping; Delbono, Osvaldo; Zhang, Tan

2017-10-01

Ageing skeletal muscle undergoes chronic denervation, and the neuromuscular junction (NMJ), the key structure that connects motor neuron nerves with muscle cells, shows increased defects with ageing. Previous studies in various species have shown that with ageing, type II fast-twitch skeletal muscle fibres show more atrophy and NMJ deterioration than type I slow-twitch fibres. However, how this process is regulated is largely unknown. A better understanding of the mechanisms regulating skeletal muscle fibre-type specific denervation at the NMJ could be critical to identifying novel treatments for sarcopenia. Cardiac troponin T (cTnT), the heart muscle-specific isoform of TnT, is a key component of the mechanisms of muscle contraction. It is expressed in skeletal muscle during early development, after acute sciatic nerve denervation, in various neuromuscular diseases and possibly in ageing muscle. Yet the subcellular localization and function of cTnT in skeletal muscle is largely unknown. Studies were carried out on isolated skeletal muscles from mice, vervet monkeys, and humans. Immunoblotting, immunoprecipitation, and mass spectrometry were used to analyse protein expression, real-time reverse transcription polymerase chain reaction was used to measure gene expression, immunofluorescence staining was performed for subcellular distribution assay of proteins, and electromyographic recording was used to analyse neurotransmission at the NMJ. Levels of cTnT expression in skeletal muscle increased with ageing in mice. In addition, cTnT was highly enriched at the NMJ region-but mainly in the fast-twitch, not the slow-twitch, muscle of old mice. We further found that the protein kinase A (PKA) RIα subunit was largely removed from, while PKA RIIα and RIIβ are enriched at, the NMJ-again, preferentially in fast-twitch but not slow-twitch muscle in old mice. Knocking down cTnT in fast skeletal muscle of old mice: (i) increased PKA RIα and reduced PKA RIIα at the NMJ; (ii

Myoglobin plasma level related to muscle mass and fiber composition: a clinical marker of muscle wasting?

Science.gov (United States)

Weber, Marc-André; Kinscherf, Ralf; Krakowski-Roosen, Holger; Aulmann, Michael; Renk, Hanna; Künkele, Annette; Edler, Lutz; Kauczor, Hans-Ulrich; Hildebrandt, Wulf

2007-08-01

Progressive muscle wasting is a central feature of cancer-related cachexia and has been recognized as a determinant of poor prognosis and quality of life. However, until now, no easily assessable clinical marker exists that allows to predict or to track muscle wasting. The present study evaluated the potential of myoglobin (MG) plasma levels to indicate wasting of large locomotor muscles and, moreover, to reflect the loss of MG-rich fiber types, which are most relevant for daily performance. In 17 cancer-cachectic patients (weight loss 22%) and 27 age- and gender-matched healthy controls, we determined plasma levels of MG and creatine kinase (CK), maximal quadriceps muscle cross-sectional area (CSA) by magnetic resonance imaging, muscle morphology and fiber composition in biopsies from the vastus lateralis muscle, body cell mass (BCM) by impedance technique as well as maximal oxygen uptake (VO(2)max). In cachectic patients, plasma MG, muscle CSA, BCM, and VO(2)max were 30-35% below control levels. MG showed a significant positive correlation to total muscle CSA (r = 0.65, p max as an important functional readout. CK plasma levels appear to be less reliable because prolonged increases are observed in even subclinical myopathies or after exercise. Notably, cancer-related muscle wasting was not associated with increases in plasma MG or CK in this study.

Satellite cells in human skeletal muscle plasticity

Directory of Open Access Journals (Sweden)

Tim eSnijders

2015-10-01

Full Text Available Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodelling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodelling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodelling in the wider context of satellite cell biology whose literature is largely based on animal and cell models.

Satellite cells in human skeletal muscle plasticity.

Science.gov (United States)

Snijders, Tim; Nederveen, Joshua P; McKay, Bryon R; Joanisse, Sophie; Verdijk, Lex B; van Loon, Luc J C; Parise, Gianni

2015-01-01

Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodeling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodeling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodeling in the wider context of satellite cell biology whose literature is largely based on animal and cell models.

The Effects of Group Relaxation Training/Large Muscle Exercise, and Parental Involvement on Attention to Task, Impulsivity, and Locus of Control among Hyperactive Boys.

Science.gov (United States)

Porter, Sally S.; Omizo, Michael M.

1984-01-01

The study examined the effects of group relaxation training/large muscle exercise and parental involvement on attention to task, impulsivity, and locus of control among 34 hyperactive boys. Following treatment both experimental groups recorded significantly higher attention to task, lower impulsivity, and lower locus of control scores. (Author/CL)

Effects of tripolar TENS on slow and fast motoneurons: a preliminary study using H-reflex recovery curve method.

Science.gov (United States)

Simorgh, L; Torkaman, G; Firoozabadi, S M

2008-01-01

This study aimed at examining the effect of tripolar TENS of vertebral column on the activity of slow and fast motoneurons on 10 healthy non-athlete women aged 22.7 +/- 2.21 yrs. H-reflex recovery curve of soleus (slow) and gastrocnemius (fast) muscles were recorded before and after applying tripolar TENS. For recording of this curve, rectangular paired stimuli were applied on tibial nerve (with 40-520 ISI, frequency of 0.2 Hz and pulse width of 600 micros). Our findings showed that maximum H-reflex recovery in gastrocnemius muscle appeared in the shorter ISI, while in soleus muscle, it appeared in the longer ISI and its amplitude slightly decreased after applying tripolar TENS. It is suggested that tripolar TENS excites not only the skin but also Ia and Ib afferents in the dorsal column. A Synaptic interaction of these afferents in spinal cord causes the inhibition of type I MNs and facilitation of type II MNs. This effect can be used in muscle tone modulation.

Myositis ossificans in rectus abdominis muscle: case report

International Nuclear Information System (INIS)

Ko, Eun Sook; Na, Jae Boem

2004-01-01

Myositis ossificans is an ossifying inflammatory lesion occurring within skeletal muscle. Myositis ossificans usually arises in the large muscles of the extremities and this lesion is characterized by progression of mineralization from periphery to center. In the early phase, myositis ossificans simulates malignant soft tissue tumor without dense mineralization. Traumatic myositis ossificans in rectus abdominis muscle has been reported worldwide. The radiologic findings of early active myositis ossificans in rectus abdominis muscle are ill defined heterogenous hypoechoic mass on US, hemorrhage, early strong enhancement and early peripheral mineralization on CT and MR

Myositis ossificans in rectus abdominis muscle: case report

Energy Technology Data Exchange (ETDEWEB)

Ko, Eun Sook; Na, Jae Boem [Gyeongsang National University College of Medicine, Jinju (Korea, Republic of)

2004-10-15

Myositis ossificans is an ossifying inflammatory lesion occurring within skeletal muscle. Myositis ossificans usually arises in the large muscles of the extremities and this lesion is characterized by progression of mineralization from periphery to center. In the early phase, myositis ossificans simulates malignant soft tissue tumor without dense mineralization. Traumatic myositis ossificans in rectus abdominis muscle has been reported worldwide. The radiologic findings of early active myositis ossificans in rectus abdominis muscle are ill defined heterogenous hypoechoic mass on US, hemorrhage, early strong enhancement and early peripheral mineralization on CT and MR.

Three-dimensional ultrasound strain imaging of skeletal muscles

NARCIS (Netherlands)

Gijsbertse, Kaj; Sprengers, Andre M.; Nillesen, Maartje; Hansen, Hendrik H.G.; Verdonschot, Nico; De Korte, Chris L.

2015-01-01

Muscle contraction is characterized by large deformation and translation, which requires a multi-dimensional imaging modality to reveal its behavior. Previous work on ultrasound strain imaging of the muscle contraction was limited to 2D and bi-plane techniques. In this study, a three-dimensional

A food-predictive cue attributed with incentive salience engages subcortical afferents and efferents of the paraventricular nucleus of the thalamus.

Science.gov (United States)

Haight, Joshua L; Fuller, Zachary L; Fraser, Kurt M; Flagel, Shelly B

2017-01-06

The paraventricular nucleus of the thalamus (PVT) has been implicated in behavioral responses to reward-associated cues. However, the precise role of the PVT in these behaviors has been difficult to ascertain since Pavlovian-conditioned cues can act as both predictive and incentive stimuli. The "sign-tracker/goal-tracker" rat model has allowed us to further elucidate the role of the PVT in cue-motivated behaviors, identifying this structure as a critical component of the neural circuitry underlying individual variation in the propensity to attribute incentive salience to reward cues. The current study assessed differences in the engagement of specific PVT afferents and efferents in response to presentation of a food-cue that had been attributed with only predictive value or with both predictive and incentive value. The retrograde tracer fluorogold (FG) was injected into the PVT or the nucleus accumbens (NAc) of rats, and cue-induced c-Fos in FG-labeled cells was quantified. Presentation of a predictive stimulus that had been attributed with incentive value elicited c-Fos in PVT afferents from the lateral hypothalamus, medial amygdala (MeA), and the prelimbic cortex (PrL), as well as posterior PVT efferents to the NAc. PVT afferents from the PrL also showed elevated c-Fos levels following presentation of a predictive stimulus alone. Thus, presentation of an incentive stimulus results in engagement of subcortical brain regions; supporting a role for the hypothalamic-thalamic-striatal axis, as well as the MeA, in mediating responses to incentive stimuli; whereas activity in the PrL to PVT pathway appears to play a role in processing the predictive qualities of reward-paired stimuli. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Fluid-driven origami-inspired artificial muscles

Science.gov (United States)

Li, Shuguang; Vogt, Daniel M.; Rus, Daniela; Wood, Robert J.

2017-12-01

Artificial muscles hold promise for safe and powerful actuation for myriad common machines and robots. However, the design, fabrication, and implementation of artificial muscles are often limited by their material costs, operating principle, scalability, and single-degree-of-freedom contractile actuation motions. Here we propose an architecture for fluid-driven origami-inspired artificial muscles. This concept requires only a compressible skeleton, a flexible skin, and a fluid medium. A mechanical model is developed to explain the interaction of the three components. A fabrication method is introduced to rapidly manufacture low-cost artificial muscles using various materials and at multiple scales. The artificial muscles can be programed to achieve multiaxial motions including contraction, bending, and torsion. These motions can be aggregated into systems with multiple degrees of freedom, which are able to produce controllable motions at different rates. Our artificial muscles can be driven by fluids at negative pressures (relative to ambient). This feature makes actuation safer than most other fluidic artificial muscles that operate with positive pressures. Experiments reveal that these muscles can contract over 90% of their initial lengths, generate stresses of ˜600 kPa, and produce peak power densities over 2 kW/kg—all equal to, or in excess of, natural muscle. This architecture for artificial muscles opens the door to rapid design and low-cost fabrication of actuation systems for numerous applications at multiple scales, ranging from miniature medical devices to wearable robotic exoskeletons to large deployable structures for space exploration.

Computed tomographic features of afferent loop syndrome: pictorial essay

Energy Technology Data Exchange (ETDEWEB)

Zissin, R. [Tel-Aviv Univ., Dept. of Diagnostic Imaging, Sapir Medical Center, Kfar Saba, Sackler Faculty of Medicine, Tel Aviv (Israel); Hertz, M. [Tel-Aviv Univ., Dept. of Diagnostic Imaging, Chaim Sheba Medical Center, Tel Hashomer, Tel Aviv (Israel); Paran, H. [Tel-Aviv Univ., Dept. of Diagnostic Imaging, Surgery ' A' , Sapir Medical Center, Kfar Saba, Sackler Faculty of Medicine, Tel Aviv (Israel); Osadchy, A. [Tel-Aviv Univ., Dept. of Diagnostic Imaging, Sapir Medical Center, Kfar Saba, Sackler Faculty of Medicine, Tel Aviv (Israel); Gayer, G. [Tel-Aviv Univ., Dept. of Diagnostic Imaging, Assaf Harofe Medical Center, Zrifin, Sackler Faculty of Medicine, Tel Aviv (Israel)

2005-04-15

This pictorial essay reviews the computed tomography (CT) findings of afferent loop syndrome (ALS) in various pathological conditions to demonstrate the contribution of a common imaging modality-that is, abdominal CT, used nowadays for various abdominal complaints-to the diagnosis of ALS. ALS is caused by obstruction of the duodenum and jejunum proximal to a gastrojejunostomy anastomosis. It is a rare complication after Billroth II subtotal gastrectomy and even more rare after total or subtotal gastrectomy with Roux-en-Y reconstruction. Although currently advanced medical treatment and endoscopic interventions have dramatically decreased the necessity of surgery for peptic ulcer disease, ALS may appear years after previously common operations. Alternatively, the use of surgical resection for early gastric cancer nowadays leads to an increasing rate of malignancy-related ALS. Clinically, ALS may be difficult to diagnose as its presentation may be vague and nonspecific, but it has a characteristic appearance on CT. Clinicians and radiologists should therefore be familiar with this rare complication. Prompt recognition and correct diagnosis of this syndrome and its probable etiology are important as a guide for treatment. This review illustrates the CT features of ALS in various conditions. (author)

Abdominal muscle function and incisional hernia

DEFF Research Database (Denmark)

Jensen, K K; Kjaer, M; Jorgensen, L N

2014-01-01

PURPOSE: Although ventral incisional hernia (VIH) repair in patients is often evaluated in terms of hernia recurrence rate and health-related quality of life, there is no clear consensus regarding optimal operative treatment based on these parameters. It was proposed that health-related quality...... of life depends largely on abdominal muscle function (AMF), and the present review thus evaluates to what extent AMF is influenced by VIH and surgical repair. METHODS: The PubMed and EMBASE databases were searched for articles following a systematic strategy for inclusion. RESULTS: A total of seven...... studies described AMF in relation to VIH. Five studies examined AMF using objective isokinetic dynamometers to determine muscle strength, and two studies examined AMF by clinical examination-based muscle tests. CONCLUSION: Both equipment-related and functional muscle tests exist for use in patients...

Neuromuscular organization of avian flight muscle: architecture of single muscle fibres in muscle units of the pectoralis (pars thoracicus) of pigeon (Columba livia)

Science.gov (United States)

Sokoloff, A. J.

1999-01-01

The M. pectoralis (pars thoracicus) of pigeons (Columba livia) is comprised of short muscle fibres that do not extend from muscle origin to insertion but overlap 'in-series'. Individual pectoralis motor units are limited in territory to a portion of muscle length and are comprised of either fast twitch, oxidative and glycolytic fibres (FOG) or fast twitch and glycolytic fibres (FG). FOG fibres make up 88 to 90% of the total muscle population and have a mean diameter one-half of that of the relatively large FG fibres. Here we report on the organization of individual fibres identified in six muscle units depleted of glycogen, three comprised of FOG fibres and three comprised of FG fibres. For each motor unit, fibre counts revealed unequal numbers of depleted fibres in different unit cross-sections. We traced individual fibres in one unit comprised of FOG fibres and a second comprised of FG fibres. Six fibres from a FOG unit (total length 15.45 mm) ranged from 10.11 to 11.82 mm in length and averaged (± s.d.) 10.74 ± 0.79 mm. All originated bluntly (en mass) from a fascicle near the proximal end of the muscle unit and all terminated intramuscularly. Five of these ended in a taper and one ended bluntly. Fibres coursed on average for 70% of the muscle unit length. Six fibres from a FG unit (total length 34.76 mm) ranged from 8.97 to 18.38 mm in length and averaged 15.32 ± 3.75 mm. All originated bluntly and terminated intramuscularly; one of these ended in a taper and five ended bluntly. Fibres coursed on average for 44% of the muscle unit length. Because fibres of individual muscle units do not extend the whole muscle unit territory, the effective cross-sectional area changes along the motor unit length. These non-uniformities in the distribution of fibres within a muscle unit emphasize that the functional interactions within and between motor units are complex.

Electrochemically Powered, Energy-Conserving Carbon Nanotube Artificial Muscles.

Science.gov (United States)

Lee, Jae Ah; Li, Na; Haines, Carter S; Kim, Keon Jung; Lepró, Xavier; Ovalle-Robles, Raquel; Kim, Seon Jeong; Baughman, Ray H

2017-08-01

While artificial muscle yarns and fibers are potentially important for many applications, the combination of large strokes, high gravimetric work capacities, short cycle times, and high efficiencies are not realized for these fibers. This paper demonstrates here electrochemically powered carbon nanotube yarn muscles that provide tensile contraction as high as 16.5%, which is 12.7 times higher than previously obtained. These electrochemical muscles can deliver a contractile energy conversion efficiency of 5.4%, which is 4.1 times higher than reported for any organic-material-based artificial muscle. All-solid-state parallel muscles and braided muscles, which do not require a liquid electrolyte, provide tensile contractions of 11.6% and 5%, respectively. These artificial muscles might eventually be deployed for a host of applications, from robotics to perhaps even implantable medical devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of drugs of abuse on putative rostromedial tegmental neurons, inhibitory afferents to midbrain dopamine cells.

Science.gov (United States)

Lecca, Salvatore; Melis, Miriam; Luchicchi, Antonio; Ennas, Maria Grazia; Castelli, Maria Paola; Muntoni, Anna Lisa; Pistis, Marco

2011-02-01

Recent findings have underlined the rostromedial tegmental nucleus (RMTg), a structure located caudally to the ventral tegmental area, as an important site involved in the mechanisms of aversion. RMTg contains γ-aminobutyric acid neurons responding to noxious stimuli, densely innervated by the lateral habenula and providing a major inhibitory projection to reward-encoding midbrain dopamine (DA) neurons. One of the key features of drug addiction is the perseverance of drug seeking in spite of negative and unpleasant consequences, likely mediated by response suppression within neural pathways mediating aversion. To investigate whether the RMTg has a function in the mechanisms of addicting drugs, we studied acute effects of morphine, cocaine, the cannabinoid agonist WIN55212-2 (WIN), and nicotine on putative RMTg neurons. We utilized single unit extracellular recordings in anesthetized rats and whole-cell patch-clamp recordings in brain slices to identify and characterize putative RMTg neurons and their responses to drugs of abuse. Morphine and WIN inhibited both firing rate in vivo and excitatory postsynaptic currents (EPSCs) evoked by stimulation of rostral afferents in vitro, whereas cocaine inhibited discharge activity without affecting EPSC amplitude. Conversely, nicotine robustly excited putative RMTg neurons and enhanced EPSCs, an effect mediated by α7-containing nicotinic acetylcholine receptors. Our results suggest that activity of RMTg neurons is profoundly influenced by drugs of abuse and, as important inhibitory afferents to midbrain DA neurons, they might take place in the complex interplay between the neural circuits mediating aversion and reward.

Skeletal muscle proteomics: current approaches, technical challenges and emerging techniques

LENUS (Irish Health Repository)

Ohlendieck, Kay

2011-02-01

Abstract Background Skeletal muscle fibres represent one of the most abundant cell types in mammals. Their highly specialised contractile and metabolic functions depend on a large number of membrane-associated proteins with very high molecular masses, proteins with extensive posttranslational modifications and components that exist in highly complex supramolecular structures. This makes it extremely difficult to perform conventional biochemical studies of potential changes in protein clusters during physiological adaptations or pathological processes. Results Skeletal muscle proteomics attempts to establish the global identification and biochemical characterisation of all members of the muscle-associated protein complement. A considerable number of proteomic studies have employed large-scale separation techniques, such as high-resolution two-dimensional gel electrophoresis or liquid chromatography, and combined them with mass spectrometry as the method of choice for high-throughput protein identification. Muscle proteomics has been applied to the comprehensive biochemical profiling of developing, maturing and aging muscle, as well as the analysis of contractile tissues undergoing physiological adaptations seen in disuse atrophy, physical exercise and chronic muscle transformation. Biomedical investigations into proteome-wide alterations in skeletal muscle tissues were also used to establish novel biomarker signatures of neuromuscular disorders. Importantly, mass spectrometric studies have confirmed the enormous complexity of posttranslational modifications in skeletal muscle proteins. Conclusions This review critically examines the scientific impact of modern muscle proteomics and discusses its successful application for a better understanding of muscle biology, but also outlines its technical limitations and emerging techniques to establish new biomarker candidates.

Charge movements and transverse tubular ultrastructure in organ cultured skeletal muscle.

Science.gov (United States)

Cullen, M J; Hollingworth, S; Marshall, M W; Robson, E

1990-04-01

A study was made of charge movements and the transverse tubular systems in rat EDL and soleus muscle fibres maintained for up to five days in organ culture. In the cultured EDL muscle the maximum amount of charge moved was about one third of that in innervated muscle. Charge movements in innervated soleus fibres are small, less than 10 nC/microF, and difficult to resolve. They remain small following organ culturing. The ultrastructural study examined the concentration of junctional feet because of their proposed key role in excitation-contraction coupling. The general architecture of the triads and the spacing of the feet in both muscle types was largely unchanged by culturing. In cultured EDL muscles the small changes in feet concentration did not parallel the large fall in charge movement. The results reported here support a previous conclusion that, in mammalian muscle, there is not a simple relation between charge and feet. The stimulation of cultured soleus muscles with a fast twitch pattern of electrical activity produced no observable changes in morphology.

Nuclear Positioning in Muscle Development and Disease

Directory of Open Access Journals (Sweden)

Eric eFolker

2013-12-01

Full Text Available Muscle disease as a group is characterized by muscle weakness, muscle loss, and impaired muscle function. Although the phenotype is the same, the underlying cellular pathologies, and the molecular causes of these pathologies, are diverse. One common feature of many muscle disorders is the mispositioning of myonuclei. In unaffected individuals myonuclei are spaced throughout the periphery of the muscle fiber such that the distance between nuclei is maximized. However, in diseased muscles, the nuclei are often clustered within the center of the muscle cell. Although this phenotype has been acknowledged for several decades, it is often ignored as a contributor to muscle weakness. Rather, these nuclei are taken only as a sign of muscle repair. Here we review the evidence that mispositioned myonuclei are not merely a symptom of muscle disease but also a cause. Additionally, we review the working models for how myonuclei move from two different perspectives, from that of the nucleus and from that of the cytoskeleton. We further compare and contrast these mechanisms with the mechanisms of nuclear movement in other cell types both to draw general themes for nuclear movement and to identify muscle-specific considerations. Finally, we focus on factors that can be linked to muscle disease and find that genes that regulate myonuclear movement and positioning have been linked to muscular dystrophy. Although the cause-effect relationship is largely speculative, recent data indicate that the position of nuclei should no longer be considered only a means to diagnose muscle disease.

Morphological changes in different populations of bladder afferent neurons detected by herpes simplex virus (HSV) vectors with cell-type-specific promoters in mice with spinal cord injury.

Science.gov (United States)

Shimizu, Nobutaka; Doyal, Mark F; Goins, William F; Kadekawa, Katsumi; Wada, Naoki; Kanai, Anthony J; de Groat, William C; Hirayama, Akihide; Uemura, Hirotsugu; Glorioso, Joseph C; Yoshimura, Naoki

2017-11-19

Functional and morphological changes in C-fiber bladder afferent pathways are reportedly involved in neurogenic detrusor overactivity (NDO) after spinal cord injury (SCI). This study examined the morphological changes in different populations of bladder afferent neurons after SCI using replication-defective herpes simplex virus (HSV) vectors encoding the mCherry reporter driven by neuronal cell-type-specific promoters. Spinal intact (SI) and SCI mice were injected into the bladder wall with HSV mCherry vectors driven by the cytomegalovirus (CMV) promoter, CGRP promoter, TRPV1 promoter or neurofilament 200 (NF200) promoter. Two weeks after vector inoculation into the bladder wall, L1 and L6 dorsal root ganglia (DRG) were removed bilaterally for immunofluorescent staining using anti-mCherry antibody. The number of CMV promoter vector-labeled neurons was not altered after SCI. The number of CGRP and TRPV1 promoter vector-labeled neurons was significantly increased whereas the number of NF200 vector-labeled neurons was decreased in L6 DRG after SCI. The median size of CGRP promoter-labeled C-fiber neurons was increased from 247.0 in SI mice to 271.3μm 2 in SCI mice whereas the median cell size of TRPV1 promoter vector-labeled neurons was decreased from 245.2 in SI mice to 216.5μm 2 in SCI mice. CGRP and TRPV1 mRNA levels of laser-captured bladder afferent neurons labeled with Fast Blue were significantly increased in SCI mice compared to SI mice. Thus, using a novel HSV vector-mediated neuronal labeling technique, we found that SCI induces expansion of the CGRP- and TRPV1-expressing C-fiber cell population, which could contribute to C-fiber afferent hyperexcitability and NDO after SCI. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Skeletal muscle substrate metabolism during exercise: methodological considerations

DEFF Research Database (Denmark)

Van Hall, Gerrit; González-Alonso, J; Sacchetti, M

1999-01-01

and the respiratory exchange ratio. However, if the aim is to quantify limb or muscle metabolism, invasive measurements have to be carried out, such as the determination of blood flow, arterio-venous (a-v) difference measurements for O2 and relevant substrates, and biopsies of the active muscle. As many substrates...... substrates. There are several methodological concerns to be aware of when studying the metabolic response to exercise in human subjects. These concerns include: (1) the muscle mass involved in the exercise is largely unknown (bicycle or treadmill). Moreover, whether the muscle sample obtained from a limb......; (3) the use of net limb glycerol release to estimate lipolysis is probably not valid (triacylglycerol utilization by muscle), since glycerol can be metabolized in skeletal muscle; (4) the precision of blood-borne substrate concentrations during exercise measured by a-v difference is hampered since...

Fluid-driven origami-inspired artificial muscles.

Science.gov (United States)

Li, Shuguang; Vogt, Daniel M; Rus, Daniela; Wood, Robert J

2017-12-12

Artificial muscles hold promise for safe and powerful actuation for myriad common machines and robots. However, the design, fabrication, and implementation of artificial muscles are often limited by their material costs, operating principle, scalability, and single-degree-of-freedom contractile actuation motions. Here we propose an architecture for fluid-driven origami-inspired artificial muscles. This concept requires only a compressible skeleton, a flexible skin, and a fluid medium. A mechanical model is developed to explain the interaction of the three components. A fabrication method is introduced to rapidly manufacture low-cost artificial muscles using various materials and at multiple scales. The artificial muscles can be programed to achieve multiaxial motions including contraction, bending, and torsion. These motions can be aggregated into systems with multiple degrees of freedom, which are able to produce controllable motions at different rates. Our artificial muscles can be driven by fluids at negative pressures (relative to ambient). This feature makes actuation safer than most other fluidic artificial muscles that operate with positive pressures. Experiments reveal that these muscles can contract over 90% of their initial lengths, generate stresses of ∼600 kPa, and produce peak power densities over 2 kW/kg-all equal to, or in excess of, natural muscle. This architecture for artificial muscles opens the door to rapid design and low-cost fabrication of actuation systems for numerous applications at multiple scales, ranging from miniature medical devices to wearable robotic exoskeletons to large deployable structures for space exploration. Copyright © 2017 the Author(s). Published by PNAS.

Extraocular muscle architecture in hawks and owls.

Science.gov (United States)

Plochocki, Jeffrey H; Segev, Tamar; Grow, Wade; Hall, Margaret I

2018-02-06

A complete and accurate understanding of extraocular muscle function is important to the veterinary care of the avian eye. This is especially true for birds of prey, which rely heavily on vision for survival and yet are prone to ocular injury and disease. To better understand the function of extraocular muscles in birds of prey, we studied extraocular muscle architecture grossly and histologically. This sample was composed of two each of the following species: red-tailed hawk (Buteo jamaicensis), Harris's hawk (Parabuteo unicinctus), great horned owl (Bubo virginianus), and barn owl (Tyto alba). All extraocular muscles were dissected and weighed. To analyze muscle fiber architecture, the superior oblique and quadratus muscles were dissected, weighed, and sectioned at 5 μm thickness in the transverse plane. We calculated the physiologic cross-sectional area and the ratio of muscle mass to predicted effective maximum tetanic tension. Hawk and owl extraocular muscles exhibit significant physiological differences that play roles in ocular movements and closure of the nictitating membrane. Owls, which do not exhibit extraocular movement, have muscle architecture suited to stabilize the position of a massive, tubular eye that protrudes significantly from the orbit. Hawks, which have a more globose eye that is largely contained within the orbit, do not require as much muscular stability and instead have muscle architecture that facilitates rapid eye movement. © 2018 American College of Veterinary Ophthalmologists.

Lung vagal afferent activity in rats with bleomycin-induced lung fibrosis.

Science.gov (United States)

Schelegle, E S; Walby, W F; Mansoor, J K; Chen, A T

2001-05-01

Bleomycin treatment in rats results in pulmonary fibrosis that is characterized by a rapid shallow breathing pattern, a decrease in quasi-static lung compliance and a blunting of the Hering-Breuer Inflation Reflex. We examined the impulse activity of pulmonary vagal afferents in anesthetized, mechanically ventilated rats with bleomycin-induced lung fibrosis during the ventilator cycle and static lung inflations/deflations and following the injection of capsaicin into the right atrium. Bleomycin enhanced volume sensitivity of slowly adapting stretch receptors (SARs), while it blunted the sensitivity of these receptors to increasing transpulmonary pressure. Bleomycin treatment increased the inspiratory activity, while it decreased the expiratory activity of rapidly adapting stretch receptors (RARs). Pulmonary C-fiber impulse activity did not appear to be affected by bleomycin treatment. We conclude that the fibrosis-related shift in discharge profile and enhanced volume sensitivity of SARs combined with the increased inspiratory activity of RARs contributes to the observed rapid shallow breathing of bleomycin-induced lung fibrosis.

Effect of Preoperative Fatty Degeneration of the Rotator Cuff Muscles on the Clinical Outcome of Patients With Intact Tendons After Arthroscopic Rotator Cuff Repair of Large/Massive Cuff Tears.

Science.gov (United States)

Ohzono, Hiroki; Gotoh, Masafumi; Nakamura, Hidehiro; Honda, Hirokazu; Mitsui, Yasuhiro; Kakuma, Tatsuyuki; Okawa, Takahiro; Shiba, Naoto

2017-11-01

Fatty degeneration of the rotator cuff muscles is associated not only with postoperative retear but also with postoperative muscle weakness; therefore, fatty changes in the muscles may affect the clinical outcome even in patients with these tears who have intact tendons after arthroscopic rotator cuff repair (ARCR). To evaluate the effect of fatty infiltration on the clinical outcome in patients with intact tendons after arthroscopic repair of large/massive cuff tears. Case-control study; Level of evidence, 3. One hundred fifty-five consecutive patients with large/massive rotator cuff tears underwent ARCR. Of these, 55 patients (mean ± SD age, 64.4 ± 9.1 years) in whom intact tendons after surgery were confirmed with magnetic resonance imaging at final follow-up (mean ± SD, 2.5 ± 1.4 years) were included in this study. Depending on their University of California Los Angeles (UCLA) score at the final follow-up, they were assigned to either the unsatisfactory group (score ≤27; n = 12) or the satisfactory group (score >27; n = 43). Various clinical parameters affecting the clinical outcome were examined through univariate and multivariate analyses. The UCLA score of all patients significantly improved from 18.1 ± 4.4 points preoperatively to 29.8 ± 4.5 points postoperatively ( P muscles, with area under the curve values of 0.79 (sensitivity 91% and specificity 51%) and 0.84 (sensitivity 100% and specificity 54%) in the infraspinatus and subscapularis, respectively. Preoperative fatty degeneration of the infraspinatus and/or subscapularis with Goutallier stage 2 or higher was significantly associated with worse outcome in patients with large/massive tears who had intact tendons after ARCR.

Development of rigor mortis is not affected by muscle volume.

Science.gov (United States)

Kobayashi, M; Ikegaya, H; Takase, I; Hatanaka, K; Sakurada, K; Iwase, H

2001-04-01

There is a hypothesis suggesting that rigor mortis progresses more rapidly in small muscles than in large muscles. We measured rigor mortis as tension determined isometrically in rat musculus erector spinae that had been cut into muscle bundles of various volumes. The muscle volume did not influence either the progress or the resolution of rigor mortis, which contradicts the hypothesis. Differences in pre-rigor load on the muscles influenced the onset and resolution of rigor mortis in a few pairs of samples, but did not influence the time taken for rigor mortis to reach its full extent after death. Moreover, the progress of rigor mortis in this muscle was biphasic; this may reflect the early rigor of red muscle fibres and the late rigor of white muscle fibres.

Adductor muscle pyo-myositis simulating appendicitis: CT and MR imaging findings

International Nuclear Information System (INIS)

Coumbaras, M.; Le Hir, P.; Jomaah, N.; Arrive, L.; Tubiana, J.M.

2001-01-01

Pyo-myositis is a primary bacterial infection of skeletal muscle. This infection tends to occur in the large muscles of the lower extremity. Pyo-myositis of the proximal muscles of the thigh can simulate acute abdominal disease. Early diagnosis improves the outcome. Delayed diagnosis may lead to septicemia and shock. We report the CT and MRI findings in a patient with pyo-myositis of the proximal muscles of the thigh. (authors)

Visuomotor contribution to force variability in the plantarflexor and dorsiflexor muscles

OpenAIRE

Tracy, Brian L.

2007-01-01

The visual correction employed during isometric contractions of large proximal muscles contributes variability to the descending command and alters fluctuations in muscle force. This study explored the contribution of visuomotor correction to isometric force fluctuations for the more distal dorsiflexor (DF) and plantarflexor (PF) muscles of the ankle. Twenty-one healthy adults performed steady isometric contractions with the DF and PF muscles both with (VIS) and without (NOVIS) visual feedbac...

Functional and histopathological identification of the respiratory failure in a DMSXL transgenic mouse model of myotonic dystrophy

Directory of Open Access Journals (Sweden)

Petrica-Adrian Panaite

2013-05-01

Acute and chronic respiratory failure is one of the major and potentially life-threatening features in individuals with myotonic dystrophy type 1 (DM1. Despite several clinical demonstrations showing respiratory problems in DM1 patients, the mechanisms are still not completely understood. This study was designed to investigate whether the DMSXL transgenic mouse model for DM1 exhibits respiratory disorders and, if so, to identify the pathological changes underlying these respiratory problems. Using pressure plethysmography, we assessed the breathing function in control mice and DMSXL mice generated after large expansions of the CTG repeat in successive generations of DM1 transgenic mice. Statistical analysis of breathing function measurements revealed a significant decrease in the most relevant respiratory parameters in DMSXL mice, indicating impaired respiratory function. Histological and morphometric analysis showed pathological changes in diaphragmatic muscle of DMSXL mice, characterized by an increase in the percentage of type I muscle fibers, the presence of central nuclei, partial denervation of end-plates (EPs and a significant reduction in their size, shape complexity and density of acetylcholine receptors, all of which reflect a possible breakdown in communication between the diaphragmatic muscles fibers and the nerve terminals. Diaphragm muscle abnormalities were accompanied by an accumulation of mutant DMPK RNA foci in muscle fiber nuclei. Moreover, in DMSXL mice, the unmyelinated phrenic afferents are significantly lower. Also in these mice, significant neuronopathy was not detected in either cervical phrenic motor neurons or brainstem respiratory neurons. Because EPs are involved in the transmission of action potentials and the unmyelinated phrenic afferents exert a modulating influence on the respiratory drive, the pathological alterations affecting these structures might underlie the respiratory impairment detected in DMSXL mice. Understanding

Cooling improves the writing performance of patients with writer's cramp.

Science.gov (United States)

Pohl, Christoph; Happe, Jörg; Klockgether, Thomas

2002-11-01

Cooling of hand and forearm muscles by immersion in 15 degrees C cold water for 5 minutes improved the writing performance of patients with writer's cramp. Since abnormal processing of muscle spindle afferent discharges contributes to the pathology of writer's cramp, this effect might result from a reduction in muscle spindle activity by lowering muscle temperature. Cooling is a simple, cheap, and safe procedure, providing temporary relief for patients with writer's cramp. Copyright 2002 Movement Disorder Society

Relationships Between Lower-Body Muscle Structure and Lower-Body Strength, Power, and Muscle-Tendon Complex Stiffness.

Science.gov (United States)

Secomb, Josh L; Lundgren, Lina E; Farley, Oliver R L; Tran, Tai T; Nimphius, Sophia; Sheppard, Jeremy M

2015-08-01

The purpose of this study was to determine whether any relationships were present between lower-body muscle structure and strength and power qualities. Fifteen elite male surfing athletes performed a battery of lower-body strength and power tests, including countermovement jump (CMJ), squat jump (SJ), isometric midthigh pull (IMTP), and had their lower-body muscle structure assessed with ultrasonography. In addition, lower-body muscle-tendon complex (MTC) stiffness and dynamic strength deficit (DSD) ratio were calculated from the CMJ and IMTP. Significant relationships of large to very large strength were observed between the vastus lateralis (VL) thickness of the left (LVL) and right (RVL) leg and peak force (PF) (r = 0.54-0.77, p well as IMTP PF (r = 0.53-0.60, p = 0.02-0.04). Furthermore, large relationships were found between left lateral gastrocnemius (LG) pennation angle and SJ and IMTP PF (r = 0.53, p = 0.04, and r = 0.70, p < 0.01, respectively) and between LG and IMTP relative PF (r = 0.63, p = 0.01). Additionally, large relationships were identified between lower-body MTC stiffness and DSD ratio (r = 0.68, p < 0.01), right (LG) pennation angle (r = 0.51, p = 0.05), CMJ PF (r = 0.60, p = 0.02), and jump height (r = 0.53, p = 0.04). These results indicate that greater VL thickness and increased LG pennation angle are related to improved performance in the CMJ, SJ, and IMTP. Furthermore, these results suggest that lower-body MTC stiffness explains a large amount of variance in determining an athlete's ability to rapidly apply force during a dynamic movement.

Strength and power of knee extensor muscles

Directory of Open Access Journals (Sweden)

Knežević Olivera

2011-01-01

Full Text Available In the studies of human neuromuscular function, the function of leg muscles has been most often measured, particularly the function of the knee extensors. Therefore, this review will be focused on knee extensors, methods for assessment of its function, the interdependence of strength and power, relations that describe these two abilities and the influence of various factors on their production (resistance training, stretching, movement tasks, age, etc.. Given that it consists of four separate muscles, the variability of their anatomical characteristics affects their participation in strength and power production, depending on the type of movement and motion that is performed. Since KE is active in a variety of activities it must be able to generate great strength in a large and diverse range of muscle lengths and high shortening velocities, in respect to different patterns of strength production, and thus different generation capacities within the muscle (Blazevich et al., 2006. It has been speculated that KE exerts its Pmax at workloads close to subject's own body weight or lower (Rahmani et al., 2001, which is very close to the maximum dynamic output hypothesis (MDI of Jaric and Markovic (2009. Changes under the influence of resistance training or biological age are variously manifested in muscle's morphological, physiological and neural characteristics, and thus in strength and power. Understanding the issues related to strength and power as abilities of great importance for daily activities, is also important for sports and rehabilitation. Performances improvement in sports in which leg muscles strength and power are crucial, as well as recovery after the injuries, are largely dependent on the research results regarding KE function. Also, the appropriate strength balance between knee flexors and extensors is important for the knee joint stability, so that the presence of imbalance between these two muscle groups might be a risk factor for

Feedforward neural control of toe walking in humans.

Science.gov (United States)

Lorentzen, Jakob; Willerslev-Olsen, Maria; Hüche Larsen, Helle; Svane, Christian; Forman, Christian; Frisk, Rasmus; Farmer, Simon Francis; Kersting, Uwe; Nielsen, Jens Bo

2018-03-23

Activation of ankle muscles at ground contact during toe walking is unaltered when sensory feedback is blocked or the ground is suddenly dropped. Responses in the soleus muscle to transcranial magnetic stimulation, but not peripheral nerve stimulation, are facilitated at ground contact during toe walking. We argue that toe walking is supported by feedforward control at ground contact. Toe walking requires careful control of the ankle muscles in order to absorb the impact of ground contact and maintain a stable position of the joint. The present study aimed to clarify the peripheral and central neural mechanisms involved. Fifteen healthy adults walked on a treadmill (3.0 km h -1 ). Tibialis anterior (TA) and soleus (Sol) EMG, knee and ankle joint angles, and gastrocnemius-soleus muscle fascicle lengths were recorded. Peripheral and central contributions to the EMG activity were assessed by afferent blockade, H-reflex testing, transcranial magnetic brain stimulation (TMS) and sudden unloading of the planter flexor muscle-tendon complex. Sol EMG activity started prior to ground contact and remained high throughout stance. TA EMG activity, which is normally seen around ground contact during heel strike walking, was absent. Although stretch of the Achilles tendon-muscle complex was observed after ground contact, this was not associated with lengthening of the ankle plantar flexor muscle fascicles. Sol EMG around ground contact was not affected by ischaemic blockade of large-diameter sensory afferents, or the sudden removal of ground support shortly after toe contact. Soleus motor-evoked potentials elicited by TMS were facilitated immediately after ground contact, whereas Sol H-reflexes were not. These findings indicate that at the crucial time of ankle stabilization following ground contact, toe walking is governed by centrally mediated motor drive rather than sensory driven reflex mechanisms. These findings have implications for our understanding of the control of

Can Measured Synergy Excitations Accurately Construct Unmeasured Muscle Excitations?

Science.gov (United States)

Bianco, Nicholas A; Patten, Carolynn; Fregly, Benjamin J

2018-01-01

Accurate prediction of muscle and joint contact forces during human movement could improve treatment planning for disorders such as osteoarthritis, stroke, Parkinson's disease, and cerebral palsy. Recent studies suggest that muscle synergies, a low-dimensional representation of a large set of muscle electromyographic (EMG) signals (henceforth called "muscle excitations"), may reduce the redundancy of muscle excitation solutions predicted by optimization methods. This study explores the feasibility of using muscle synergy information extracted from eight muscle EMG signals (henceforth called "included" muscle excitations) to accurately construct muscle excitations from up to 16 additional EMG signals (henceforth called "excluded" muscle excitations). Using treadmill walking data collected at multiple speeds from two subjects (one healthy, one poststroke), we performed muscle synergy analysis on all possible subsets of eight included muscle excitations and evaluated how well the calculated time-varying synergy excitations could construct the remaining excluded muscle excitations (henceforth called "synergy extrapolation"). We found that some, but not all, eight-muscle subsets yielded synergy excitations that achieved >90% extrapolation variance accounted for (VAF). Using the top 10% of subsets, we developed muscle selection heuristics to identify included muscle combinations whose synergy excitations achieved high extrapolation accuracy. For 3, 4, and 5 synergies, these heuristics yielded extrapolation VAF values approximately 5% lower than corresponding reconstruction VAF values for each associated eight-muscle subset. These results suggest that synergy excitations obtained from experimentally measured muscle excitations can accurately construct unmeasured muscle excitations, which could help limit muscle excitations predicted by muscle force optimizations.

Blockade of chloride channels by DIDS stimulates renin release and inhibits contraction of afferent arterioles

DEFF Research Database (Denmark)

Jensen, B L; Skøtt, O

1996-01-01

or without ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] and DIDS were not additive. In the absence of chloride, basal renin release was suppressed and the stimulatory effect of DIDS was abolished. The DIDS-induced enhancement of renin release was not dependent on bicarbonate....... Norepinephrine (5 x 10(-7)-1 x 10(-6) M) and angiotensin II (1 x 10(-8)-10(-6) M) evoked reversible and dose-dependent contractions of microperfused rabbit afferent arterioles. DIDS (0.5 mM) did not affect the basal diameter of the arterioles but strongly inhibited the response to angiotensin II and attenuated...

Muscle Activity Adaptations to Spinal Tissue Creep in the Presence of Muscle Fatigue

Science.gov (United States)

Nougarou, François

2016-01-01

Aim The aim of this study was to identify adaptations in muscle activity distribution to spinal tissue creep in presence of muscle fatigue. Methods Twenty-three healthy participants performed a fatigue task before and after 30 minutes of passive spinal tissue deformation in flexion. Right and left erector spinae activity was recorded using large-arrays surface electromyography (EMG). To characterize muscle activity distribution, dispersion was used. During the fatigue task, EMG amplitude root mean square (RMS), median frequency and dispersion in x- and y-axis were compared before and after spinal creep. Results Important fatigue-related changes in EMG median frequency were observed during muscle fatigue. Median frequency values showed a significant main creep effect, with lower median frequency values on the left side under the creep condition (p≤0.0001). A significant main creep effect on RMS values was also observed as RMS values were higher after creep deformation on the right side (p = 0.014); a similar tendency, although not significant, was observed on the left side (p = 0.06). A significant creep effects for x-axis dispersion values was observed, with higher dispersion values following the deformation protocol on the left side (p≤0.001). Regarding y-axis dispersion values, a significant creep x fatigue interaction effect was observed on the left side (p = 0.016); a similar tendency, although not significant, was observed on the right side (p = 0.08). Conclusion Combined muscle fatigue and creep deformation of spinal tissues led to changes in muscle activity amplitude, frequency domain and distribution. PMID:26866911

A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

Science.gov (United States)

Randolph, Matthew E.; Pavlath, Grace K.

2015-01-01

The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

The acute response of pericytes to muscle-damaging eccentric contraction and protein supplementation in human skeletal muscle.

Science.gov (United States)

De Lisio, Michael; Farup, Jean; Sukiennik, Richard A; Clevenger, Nicole; Nallabelli, Julian; Nelson, Brett; Ryan, Kelly; Rahbek, Stine K; de Paoli, Frank; Vissing, Kristian; Boppart, Marni D

2015-10-15

Skeletal muscle pericytes increase in quantity following eccentric exercise (ECC) and contribute to myofiber repair and adaptation in mice. The purpose of the present investigation was to examine pericyte quantity in response to muscle-damaging ECC and protein supplementation in human skeletal muscle. Male subjects were divided into protein supplement (WHY; n = 12) or isocaloric placebo (CHO; n = 12) groups and completed ECC using an isokinetic dynamometer. Supplements were consumed 3 times/day throughout the experimental time course. Biopsies were collected prior to (PRE) and 3, 24, 48, and 168 h following ECC. Reflective of the damaging protocol, integrin subunits, including α7, β1A, and β1D, increased (3.8-fold, 3.6-fold and 3.9-fold, respectively, P muscle-damaging ECC increases α7β1 integrin content in human muscle, yet pericyte quantity is largely unaltered. Future studies should focus on the capacity for ECC to influence pericyte function, specifically paracrine factor release as a mechanism toward pericyte contribution to repair and adaptation postexercise. Copyright © 2015 the American Physiological Society.

Peripheral δ-opioid receptors attenuate the exercise pressor reflex.

Science.gov (United States)

Leal, Anna K; Yamauchi, Katsuya; Kim, Joyce; Ruiz-Velasco, Victor; Kaufman, Marc P

2013-10-15

In rats with ligated femoral arteries, the exercise pressor reflex is exaggerated, an effect that is attenuated by stimulation of peripheral μ-opioid receptors on group IV metabosensitive afferents. In contrast, δ-opioid receptors are expressed mostly on group III mechanosensitive afferents, a finding that prompted us to determine whether stimulation of these opioid receptors could also attenuate the exaggerated exercise pressor reflex in "ligated" rats. We found femoral arterial injection of [D-Pen2,D-Pen5]enkephalin (DPDPE; 1.0 μg), a δ-opioid agonist, significantly attenuated the pressor and cardioaccelerator components of the exercise pressor reflex evoked by hindlimb muscle contraction in both rats with ligated and patent femoral arteries. DPDPE significantly decreased the pressor responses to muscle mechanoreflex activation, evoked by tendon stretch, in ligated rats only. DPDPE (1.0 μg) had no effect in either group on the pressor and cardioaccelerator responses to capsaicin (0.2 μg), which primarily stimulates group IV afferents. DPDPE (1.0 μg) had no effect on the pressor and cardioaccelerator responses to lactic acid (24 mM), which stimulates group III and IV afferents, in rats with patent femoral arteries but significantly decreased the pressor response in ligated rats. Western blots revealed the amount of protein comprising the δ-opioid receptor was greater in dorsal root ganglia innervating hindlimbs with ligated femoral arteries than in dorsal root ganglia innervating hindlimbs with patent femoral arteries. Our findings support the hypothesis that stimulation of δ-opioid receptors on group III afferents attenuated the exercise pressor reflex.

Assessment of muscle function using hybrid PET/MRI: comparison of 18F-FDG PET and T2-weighted MRI for quantifying muscle activation in human subjects

International Nuclear Information System (INIS)

Haddock, Bryan; Holm, Soeren; Poulsen, Jakup M.; Enevoldsen, Lotte H.; Larsson, Henrik B.W.; Kjaer, Andreas; Suetta, Charlotte

2017-01-01

The aim of this study was to determine the relationship between relative glucose uptake and MRI T 2 changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans. Ten young healthy recreationally active men (age 21 - 28 years) were injected with 18 F-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with 18 F-FDG PET/MRI and muscle groups were evaluated for increases in 18 F-FDG uptake and MRI T 2 values. A significant linear correlation between 18 F-FDG uptake and changes in muscle T 2 (R 2 = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between 18 F-FDG uptake and changes in muscle T 2 did not vary among subjects. This is the first assessment of skeletal muscle activation using hybrid PET/MRI and the first study to demonstrate a high correlation between 18 F-FDG uptake and changes in muscle T 2 with physical exercise. Accordingly, it seems that changes in muscle T 2 may be used as a surrogate marker for glucose uptake and lead to an improved insight into the metabolic changes that occur with muscle activation. Such knowledge may lead to improved treatment strategies in patients with neuromuscular pathologies such as stroke, spinal cord injuries and muscular dystrophies. (orig.)

Neurochemical characterization of sea lamprey taste buds and afferent gustatory fibers: presence of serotonin, calretinin, and CGRP immunoreactivity in taste bud bi-ciliated cells of the earliest vertebrates.

Science.gov (United States)

Barreiro-Iglesias, Antón; Villar-Cerviño, Verona; Villar-Cheda, Begoña; Anadón, Ramón; Rodicio, María Celina

2008-12-01

Neuroactive substances such as serotonin and other monoamines have been suggested to be involved in the transmission of gustatory signals from taste bud cells to afferent fibers. Lampreys are the earliest vertebrates that possess taste buds, although these differ in structure from taste buds in jawed vertebrates, and their neurochemistry remains unknown. We used immunofluorescence methods with antibodies raised against serotonin, tyrosine hydroxylase (TH), gamma-aminobutyric acid (GABA), glutamate, calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), calretinin, and acetylated alpha-tubulin to characterize the neurochemistry and innervation of taste buds in the sea lamprey, Petromyzon marinus L. For localization of proliferative cells in taste buds we used bromodeoxyuridine labeling and proliferating cell nuclear antigen immunohistochemistry. Results with both markers indicate that proliferating cells are restricted to a few basal cells and that almost all cells in taste buds are nonproliferating. A large number of serotonin-, calretinin-, and CGRP-immunoreactive bi-ciliated cells were revealed in lamprey taste buds. This suggests that serotonin participates in the transmission of gustatory signals and indicates that this substance appeared early on in vertebrate evolution. The basal surface of the bi-ciliated taste bud cells was contacted by tubulin-immunoreactive fibers. Some of the fibers surrounding the taste bud were calretinin immunoreactive. Lamprey taste bud cells or afferent fibers did not exhibit TH, GABA, glutamate, or NPY immunoreactivity, which suggests that expression of these substances evolved in taste buds of some gnathostomes lines after the separation of gnathostomes and lampreys. (c) 2008 Wiley-Liss, Inc.

Effects of spaceflight on the muscles of the murine shoulder.

Science.gov (United States)

Shen, Hua; Lim, Chanteak; Schwartz, Andrea G; Andreev-Andrievskiy, Alexander; Deymier, Alix C; Thomopoulos, Stavros

2017-12-01

Mechanical loading is necessary for the development and maintenance of the musculoskeletal system. Removal of loading via microgravity, paralysis, or bed rest leads to rapid loss of muscle mass and function; however, the molecular mechanisms that lead to these changes are largely unknown, particularly for the spaceflight (SF) microgravity environment. Furthermore, few studies have explored these effects on the shoulder, a dynamically stabilized joint with a large range of motion; therefore, we examined the effects of microgravity on mouse shoulder muscles for the 15-d Space Transportation System (STS)-131, 13-d STS-135, and 30-d Bion-M1 missions. Mice from STS missions were euthanized within 4 h after landing, whereas mice from the Bion-M1 mission were euthanized within 14 h after landing. The motion-generating deltoid muscle was more sensitive to microgravity than the joint-stabilizing rotator cuff muscles. Mice from the STS-131 mission exhibited reduced myogenic ( Myf5 and -6 ) and adipogenic ( Pparg , Cebpa , and Lep ) gene expression, whereas either no change or an increased expression of these genes was observed in mice from the Bion-M1 mission. In summary, muscle responses to microgravity were muscle-type specific, short-duration SF caused dramatic molecular changes to shoulder muscles and responses to reloading upon landing were rapid.-Shen, H., Lim, C., Schwartz, A. G., Andreev-Andrievskiy, A., Deymier, A. C., Thomopoulos, S. Effects of spaceflight on the muscles of the murine shoulder. © FASEB.

What would 5-HT do? Regional diversity of 5-HT1 receptor modulation of primary afferent neurotransmission

OpenAIRE

Connor, Mark

2012-01-01

5-HT (serotonin) is a significant modulator of sensory input to the CNS, but the only analgesics that selectively target G-protein-coupled 5-HT receptors are highly specific for treatment of headache. Two recent papers in BJP shed light on this puzzling situation by showing that primary afferent neurotransmission to the superficial layers of the spinal and trigeminal dorsal is inhibited by different subtypes of the 5-HT1 receptor – 5-HT1B(and 1D) in the trigeminal dorsal horn and 5-HT1A in th...

Agonist muscle adaptation accompanied by antagonist muscle atrophy in the hindlimb of mice following stretch-shortening contraction training.

Science.gov (United States)

Rader, Erik P; Naimo, Marshall A; Ensey, James; Baker, Brent A

2017-02-02

The vast majority of dynamometer-based animal models for investigation of the response to chronic muscle contraction exposure has been limited to analysis of isometric, lengthening, or shortening contractions in isolation. An exception to this has been the utilization of a rat model to study stretch-shortening contractions (SSCs), a sequence of consecutive isometric, lengthening, and shortening contractions common during daily activity and resistance-type exercise. However, the availability of diverse genetic strains of rats is limited. Therefore, the purpose of the present study was to develop a dynamometer-based SSC training protocol to induce increased muscle mass and performance in plantarflexor muscles of mice. Young (3 months old) C57BL/6 mice were subjected to 1 month of plantarflexion SSC training. Hindlimb muscles were analyzed for muscle mass, quantitative morphology, myogenesis/myopathy relevant gene expression, and fiber type distribution. The main aim of the research was achieved when training induced a 2-fold increase in plantarflexion peak torque output and a 19% increase in muscle mass for the agonist plantaris (PLT) muscle. In establishing this model, several outcomes emerged which raised the value of the model past that of being a mere recapitulation of the rat model. An increase in the number of muscle fibers per transverse muscle section accounted for the PLT muscle mass gain while the antagonist tibialis anterior (TA) muscle atrophied by 30% with preferential atrophy of type IIb and IIx fibers. These alterations were accompanied by distinct gene expression profiles. The findings confirm the development of a stretch-shortening contraction training model for the PLT muscle of mice and demonstrate that increased cross-sectional fiber number can occur following high-intensity SSC training. Furthermore, the TA muscle atrophy provides direct evidence for the concept of muscle imbalance in phasic non-weight bearing muscles, a concept largely

Organization of sensory input to the nociceptive-specific cutaneous trunk muscle reflex in rat, an effective experimental system for examining nociception and plasticity

Science.gov (United States)

Petruska, Jeffrey C.; Barker, Darrell F.; Garraway, Sandra M.; Trainer, Robert; Fransen, James W.; Seidman, Peggy A.; Soto, Roy G.; Mendell, Lorne M.; Johnson, Richard D.

2013-01-01

Detailed characterization of neural circuitries furthers our understanding of how nervous systems perform specific functions and enables the use of those systems to test hypotheses. We have characterized the sensory input to the cutaneous trunk muscle (CTM; also cutaneus trunci (rat) or cutaneus maximus (mouse)) reflex (CTMR), which manifests as a puckering of the dorsal thoracolumbar skin and is selectively driven by noxious stimuli. CTM electromyography (EMG) and neurogram recordings in naïve rats revealed that CTMR responses were elicited by natural stimuli and electrical stimulation of all segments from C4 to L6, a much greater extent of segmental drive to the CTMR than previously described. Stimulation of some subcutaneous paraspinal tissue can also elicit this reflex. Using a selective neurotoxin, we also demonstrate differential drive of the CTMR by trkA-expressing and non-expressing small diameter afferents. These observations highlight aspects of the organization of the CTMR system which make it attractive for studies of nociception and anesthesiology and plasticity of primary afferents, motoneurons, and the propriospinal system. We use the CTMR system to qualitatively and quantitatively demonstrate that experimental pharmacological treatments can be compared to controls applied either to the contralateral side or to another segment, with the remaining segments providing controls for systemic or other treatment effects. These data indicate the potential for using the CTMR system as both an invasive and non-invasive quantitative assessment tool providing improved statistical power and reduced animal use. PMID:23983104

Muscle satellite cell heterogeneity and self-renewal

Science.gov (United States)

Motohashi, Norio; Asakura, Atsushi

2014-01-01

Adult skeletal muscle possesses extraordinary regeneration capacities. After muscle injury or exercise, large numbers of newly formed muscle fibers are generated within a week as a result of expansion and differentiation of a self-renewing pool of muscle stem cells termed muscle satellite cells. Normally, satellite cells are mitotically quiescent and reside beneath the basal lamina of muscle fibers. Upon regeneration, satellite cells are activated, and give rise to daughter myogenic precursor cells. After several rounds of proliferation, these myogenic precursor cells contribute to the formation of new muscle fibers. During cell division, a minor population of myogenic precursor cells returns to quiescent satellite cells as a self-renewal process. Currently, accumulating evidence has revealed the essential roles of satellite cells in muscle regeneration and the regulatory mechanisms, while it still remains to be elucidated how satellite cell self-renewal is molecularly regulated and how satellite cells are important in aging and diseased muscle. The number of satellite cells is decreased due to the changing niche during ageing, resulting in attenuation of muscle regeneration capacity. Additionally, in Duchenne muscular dystrophy (DMD) patients, the loss of satellite cell regenerative capacity and decreased satellite cell number due to continuous needs for satellite cells lead to progressive muscle weakness with chronic degeneration. Thus, it is necessary to replenish muscle satellite cells continuously. This review outlines recent findings regarding satellite cell heterogeneity, asymmetric division and molecular mechanisms in satellite cell self-renewal which is crucial for maintenance of satellite cells as a muscle stem cell pool throughout life. In addition, we discuss roles in the stem cell niche for satellite cell maintenance, as well as related cell therapies for approaching treatment of DMD. PMID:25364710

Muscle Satellite Cell Heterogeneity and Self-Renewal

Directory of Open Access Journals (Sweden)

Norio eMotohashi

2014-01-01

Full Text Available Adult skeletal muscle possesses extraordinary regeneration capacities. After muscle injury or exercise, large numbers of newly formed muscle fibers are generated within a week as a result of expansion and differentiation of a self-renewing pool of muscle stem cells termed muscle satellite cells. Normally, satellite cells are mitotically quiescent and reside beneath the basal lamina of muscle fibers. Upon regeneration, satellite cells are activated, and give rise to daughter myogenic precursor cells. After several rounds of proliferation, these myogenic precursor cells contribute to the formation of new muscle fibers. During cell division, a minor population of myogenic precursor cells returns to quiescent satellite cells as a self-renewal process. Currently, accumulating evidence has revealed the essential roles of satellite cells in muscle regeneration and the regulatory mechanisms, while it still remains to be elucidated how satellite cell self-renewal is molecularly regulated and how satellite cells are important in aging and diseased muscle. The number of satellite cells is decreased due to the changing niche during ageing, resulting in attenuation of muscle regeneration capacity. Additionally, in Duchenne muscular dystrophy (DMD patients, the loss of satellite cell regenerative capacity and decreased satellite cell number due to continuous needs for satellite cells lead to progressive muscle weakness with chronic degeneration. Thus, it is necessary to replenish muscle satellite cells continuously. This review outlines recent findings regarding satellite cell heterogeneity, asymmetric division and molecular mechanisms in satellite cell self-renewal which is crucial for maintenance of satellite cells as a muscle stem cell pool throughout life. In addition, we discuss roles in the stem cell niche for satellite cell maintenance, as well as related cell therapies for approaching treatment of DMD.

Short-term plasticity in a monosynaptic reflex pathway to forearm muscles after continuous robot-assisted passive stepping

Directory of Open Access Journals (Sweden)

Tsuyoshi Nakajima

2016-07-01

Full Text Available Both active and passive rhythmic limb movements reduce the amplitude of spinal cord Hoffmann (H- reflexes in muscles of moving and distant limbs. This could have clinical utility in remote modulation of the pathologically hyperactive reflexes found in spasticity after stroke or spinal cord injury. However, such clinical translation is currently hampered by a lack of critical information regarding the minimum or effective duration of passive movement needed for modulating spinal cord excitability. We therefore investigated the H-reflex modulation in the flexor carpi radialis (FCR muscle during and after various durations (5, 10, 15, and 30 min of passive stepping in 11 neurologically normal subjects. Passive stepping was performed by a robotic gait trainer system (Lokomat® while a single pulse of electrical stimulation to the median nerve elicited H-reflexes in the FCR. The amplitude of the FCR H-reflex was significantly suppressed during passive stepping. Although 30 minutes of passive stepping was sufficient to elicit a persistent H-reflex suppression that lasted up to 15 minutes, 5 minutes of passive stepping was not. The duration of H-reflex suppression correlated with that of the stepping. These findings suggest that the accumulation of stepping-related afferent feedback from the leg plays a role in generating short-term interlimb plasticity in the circuitry of the FCR H-reflex.

Intermuscular force transmission between human plantarflexor muscles in vivo

DEFF Research Database (Denmark)

Bojsen-Møller, Jens; Schwartz, Sidse; Kalliokoski, Kari K

2010-01-01

of the present study was to investigate if intermuscular force transmission occurs within and between human plantarflexor muscles in vivo. Seven subjects performed four types of either active contractile tasks or passive joint manipulations: passive knee extension, voluntary isometric plantarflexion, voluntary...... surae muscles was seen during passive hallux extension. Large interindividual differences with respect to deep plantarflexor activation during voluntary contractions were observed. The present results suggest that force may be transmitted between the triceps surae muscles in vivo, while only limited...

Gait phase detection from sciatic nerve recordings in functional electrical stimulation systems for foot drop correction

International Nuclear Information System (INIS)

Chu, Jun-Uk; Song, Kang-Il; Han, Sungmin; Suh, Jun-Kyo Francis; Choi, Kuiwon; Youn, Inchan; Lee, Soo Hyun; Kang, Ji Yoon; Hwang, Dosik

2013-01-01

Cutaneous afferent activities recorded by a nerve cuff electrode have been used to detect the stance phase in a functional electrical stimulation system for foot drop correction. However, the implantation procedure was difficult, as the cuff electrode had to be located on the distal branches of a multi-fascicular nerve to exclude muscle afferent and efferent activities. This paper proposes a new gait phase detection scheme that can be applied to a proximal nerve root that includes cutaneous afferent fibers as well as muscle afferent and efferent fibers. To test the feasibility of this scheme, electroneurogram (ENG) signals were measured from the rat sciatic nerve during treadmill walking at several speeds, and the signal properties of the sciatic nerve were analyzed for a comparison with kinematic data from the ankle joint. On the basis of these experiments, a wavelet packet transform was tested to define a feature vector from the sciatic ENG signals according to the gait phases. We also propose a Gaussian mixture model (GMM) classifier and investigate whether it could be used successfully to discriminate feature vectors into the stance and swing phases. In spite of no significant differences in the rectified bin-integrated values between the stance and swing phases, the sciatic ENG signals could be reliably classified using the proposed wavelet packet transform and GMM classification methods. (paper)

Primary afferent depolarization and changes in extracellular potassium concentration induced by L-glutamate and L-proline in the isolated spinal cord of the frog.

Science.gov (United States)

Vyklický, L; Vyskocil, F; Kolaj, M; Jastreboff, P

1982-10-08

To test the hypothesis that L-proline acts as an antagonist on glutamate receptors [17, 18], the interaction between L-glutamate and L-proline was studied in the isolated spinal cord of the frog. Glutamate at concentrations of 10(-6) -5 x 10(-3) mol/l depolarized the primary afferent fibres and increased extracellular potassium concentration, [K+]e, by 0.3-4 mmol/l. Repeated applications lead to inactivation of the response. L-Proline at 5 x 10(-3) -10(-2) mol/l, also depolarized the primary afferents and increased [K+]e by 0.5-2 mmol/l, but there was only a slight decrease of the effects after repeated application. The effects were additive when the amino acids were applied simultaneously. The effect of L-proline was still present when it was applied during inactivation of the glutamate receptors. This suggests that L-glutamate and L-proline act on different receptors.

Glucagon-like peptide 1 interacts with ghrelin and leptin to regulate glucose metabolism and food intake through vagal afferent neuron signaling.

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Ronveaux, Charlotte C; Tomé, Daniel; Raybould, Helen E

2015-04-01

Emerging evidence has suggested a possible physiologic role for peripheral glucagon-like peptide 1 (GLP-1) in regulating glucose metabolism and food intake. The likely site of action of GLP-1 is on vagal afferent neurons (VANs). The vagal afferent pathway is the major neural pathway by which information about ingested nutrients reaches the central nervous system and influences feeding behavior. Peripheral GLP-1 acts on VANs to inhibit food intake. The mechanism of the GLP-1 receptor (GLP-1R) is unlike other gut-derived receptors; GLP-1Rs change their cellular localization according to feeding status rather than their protein concentrations. It is possible that several gut peptides are involved in mediating GLP-1R translocation. The mechanism of peripheral GLP-1R translocation still needs to be elucidated. We review data supporting the role of peripheral GLP-1 acting on VANs in influencing glucose homeostasis and feeding behavior. We highlight evidence demonstrating that GLP-1 interacts with ghrelin and leptin to induce satiation. Our aim was to understand the mechanism of peripheral GLP-1 in the development of noninvasive antiobesity treatments. © 2015 American Society for Nutrition.

Exercise induced capillary growth in human skeletal muscle and the dynamics of VEGF

DEFF Research Database (Denmark)

Høier, Birgitte; Hellsten, Ylva

2014-01-01

, such as shear stress and passive stretch, lead to cellular signalling, enhanced expression of angiogenic factors and initiation of capillary growth. The most central angiogenic factor in skeletal muscle capillary growth is vascular endothelial growth factor (VEGF). During muscle contraction, VEGF increases...... in the muscle interstitium, acts on VEGF receptors on the capillary endothelium and thereby stimulates angiogenic processes. A primary source of muscle interstitial VEGF during exercise is the skeletal muscle fibers which contain large stores of VEGF within vesicles. We propose that, during muscle activity...

Muscle atrophy reversed by growth factor activation of satellite cells in a mouse muscle atrophy model.

Directory of Open Access Journals (Sweden)

Simon Hauerslev

Full Text Available Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth control factor, myostatin and atrophy markers MAFbx and MuRF1. Hypoxia-induced atrophy was partially restored by hepatocyte growth factor combined with leukemia inhibitory factor treatment. Dividing satellite cells were three-fold increased in the treatment group compared to control. Finally, we demonstrated that myostatin regulates satellite cell activation and myogenesis in vivo following treatment, consistent with previous findings in vitro. Our results suggest, not only a novel in vivo pharmacological treatment directed specifically at activating the satellite cells, but also a myostatin dependent mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength.

Assessment of muscle function using hybrid PET/MRI: comparison of {sup 18}F-FDG PET and T2-weighted MRI for quantifying muscle activation in human subjects

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Haddock, Bryan; Holm, Soeren; Poulsen, Jakup M.; Enevoldsen, Lotte H.; Larsson, Henrik B.W.; Kjaer, Andreas; Suetta, Charlotte [Rigshospitalet Glostrup, Copenhagen University Hospital, Department of Clinical Physiology, Nuclear Medicine and PET, Glostrup (Denmark)

2017-04-15

The aim of this study was to determine the relationship between relative glucose uptake and MRI T{sub 2} changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans. Ten young healthy recreationally active men (age 21 - 28 years) were injected with {sup 18}F-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with {sup 18}F-FDG PET/MRI and muscle groups were evaluated for increases in {sup 18}F-FDG uptake and MRI T{sub 2} values. A significant linear correlation between {sup 18}F-FDG uptake and changes in muscle T{sub 2} (R {sup 2} = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between {sup 18}F-FDG uptake and changes in muscle T{sub 2} did not vary among subjects. This is the first assessment of skeletal muscle activation using hybrid PET/MRI and the first study to demonstrate a high correlation between {sup 18}F-FDG uptake and changes in muscle T{sub 2} with physical exercise. Accordingly, it seems that changes in muscle T{sub 2} may be used as a surrogate marker for glucose uptake and lead to an improved insight into the metabolic changes that occur with muscle activation. Such knowledge may lead to improved treatment strategies in patients with neuromuscular pathologies such as stroke, spinal cord injuries and muscular dystrophies. (orig.)

Skeletal muscle mechanics: questions, problems and possible solutions.

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Herzog, Walter

2017-09-16

Skeletal muscle mechanics have been studied ever since people have shown an interest in human movement. However, our understanding of muscle contraction and muscle mechanical properties has changed fundamentally with the discovery of the sliding filament theory in 1954 and associated cross-bridge theory in 1957. Nevertheless, experimental evidence suggests that our knowledge of the mechanisms of contraction is far from complete, and muscle properties and muscle function in human movement remain largely unknown.In this manuscript, I am trying to identify some of the crucial challenges we are faced with in muscle mechanics, offer possible solutions to questions, and identify problems that might be worthwhile exploring in the future. Since it is impossible to tackle all (worthwhile) problems in a single manuscript, I identified three problems that are controversial, important, and close to my heart. They may be identified as follows: (i) mechanisms of muscle contraction, (ii) in vivo whole muscle mechanics and properties, and (iii) force-sharing among synergistic muscles. These topics are fundamental to our understanding of human movement and movement control, and they contain a series of unknowns and challenges to be explored in the future.It is my hope that this paper may serve as an inspiration for some, may challenge current beliefs in selected areas, tackle important problems in the area of muscle mechanics, physiology and movement control, and may guide and focus some of the thinking of future muscle mechanics research.

Mapping Muscles Activation to Force Perception during Unloading.

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Simone Toma

Full Text Available It has been largely proved that while judging a force humans mainly rely on the motor commands produced to interact with that force (i.e., sense of effort. Despite of a large bulk of previous investigations interested in understanding the contributions of the descending and ascending signals in force perception, very few attempts have been made to link a measure of neural output (i.e., EMG to the psychophysical performance. Indeed, the amount of correlation between EMG activity and perceptual decisions can be interpreted as an estimate of the contribution of central signals involved in the sensation of force. In this study we investigated this correlation by measuring the muscular activity of eight arm muscles while participants performed a quasi-isometric force detection task. Here we showed a method to quantitatively describe muscular activity ("muscle-metric function" that was directly comparable to the description of the participants' psychophysical decisions about the stimulus force. We observed that under our experimental conditions, muscle-metric absolute thresholds and the shape of the muscle-metric curves were closely related to those provided by the psychophysics. In fact a global measure of the muscles considered was able to predict approximately 60% of the perceptual decisions total variance. Moreover the inter-subjects differences in psychophysical sensitivity showed high correlation with both participants' muscles sensitivity and participants' joint torques. Overall, our findings gave insights into both the role played by the corticospinal motor commands while performing a force detection task and the influence of the gravitational muscular torque on the estimation of vertical forces.

Isolation and characterization of the inositol trisphosphate receptor from smooth muscle

International Nuclear Information System (INIS)

Chadwick, C.C.; Saito, A.; Fleischer, S.

1990-01-01

The release of Ca 2+ from internal stores is requisite to muscle contraction. In skeletal muscle and heart, the Ca 2+ release channels (ryanodine receptor) of sarcoplasmic reticulum, involved in excitation-contraction coupling, have recently been isolated and characterized. In smooth muscle, inositol 1,4,5-trisphosphate (IP 3 ) is believed to mobilize Ca 2+ from internal stores and thereby modulate contraction. The authors describe the isolation of an IP 3 receptor from smooth muscle. Bovine aorta smooth muscle microsomes were solubilized with 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate, and the IP 3 receptor was purified by sucrose gradient centrifugation and column chromatography with heparin-agarose and wheat germ agglutinin-agarose. The receptor is an oligomer of a single polypeptide with a M r of 224,000 as determined by SDS/PAGE. Negative-staining electron microscopy reveals that the receptor is a large pinwheel-like structure having surface dimensions of ∼250 x 250 angstrom with fourfold symmetry. The IP 3 receptor from smooth muscle is similar to the ryanodine receptor with regard to its large size and fourfold symmetry, albeit distinct with regard to appearance, protomer size, and ligand binding

Expression of smooth muscle and non-muscle myosin heavy chain isoforms in cultured vascular smooth muscle cells

International Nuclear Information System (INIS)

Rovner, A.S.; Murphy, R.A.; Owens, G.K.

1986-01-01

Immunocytochemical studies of cultured smooth muscle cells (SMCs) have disagreed on the nature of myosin expression. This investigation was undertaken to test for the presence of heterogeneous myosin heavy chain (MHC) isoforms in cell culture as a possible explanation for these results. Previously, Rovner et al. detected two MHCs in intact smooth muscles which differed in molecular weight by ca. 4000 daltons (SM1 and SM2) using a 3-4% acrylamide gradient SDS gel system. When sub-confluent primary cultures of rat aorta SMCs were assayed by this system, SM1 and SM2 were seen, along with large amounts of a third, unique MHC, NM, which closely resembled the MHC from human platelet in size and antigenicity. Data from 35 S-methionine autoradiograms showed that the log growth phase SMC cultures were producing almost exclusively NM, but the growth arrest, post-confluent cultures synthesized increased relative amounts of the SM MHC forms and contained comparable amounts of SM1, SM2, and NM. The same patterns of MHC synthesis were seen in sub-passaged SMCs. The expression of the SM-specific forms of myosin in quiescent, post-confluent cultures parallels that of smooth muscle actin suggesting that density induced growth arrest promotes cytodifferentiation in cultured vascular SMCs

Direct measurement of skeletal muscle fatigue in patients with chronic heart failure.

OpenAIRE

Buller, N P; Jones, D; Poole-Wilson, P A

1991-01-01

Skeletal muscle function was measured as force production and fatigue in both the quadriceps (a large locomotive muscle) and adductor pollicis (a small intrinsic hand muscle) in five healthy volunteers, five patients with mild chronic heart failure, and five patients with severe chronic heart failure. The quadriceps of patients with chronic heart failure had a reduced muscle cross sectional area, a reduced maximum isometric force production, and an increased tendency to fatigue. Isometric for...

Continuous detection of weak sensory signals in afferent spike trains: the role of anti-correlated interspike intervals in detection performance.

Science.gov (United States)

Goense, J B M; Ratnam, R

2003-10-01

An important problem in sensory processing is deciding whether fluctuating neural activity encodes a stimulus or is due to variability in baseline activity. Neurons that subserve detection must examine incoming spike trains continuously, and quickly and reliably differentiate signals from baseline activity. Here we demonstrate that a neural integrator can perform continuous signal detection, with performance exceeding that of trial-based procedures, where spike counts in signal- and baseline windows are compared. The procedure was applied to data from electrosensory afferents of weakly electric fish (Apteronotus leptorhynchus), where weak perturbations generated by small prey add approximately 1 spike to a baseline of approximately 300 spikes s(-1). The hypothetical postsynaptic neuron, modeling an electrosensory lateral line lobe cell, could detect an added spike within 10-15 ms, achieving near ideal detection performance (80-95%) at false alarm rates of 1-2 Hz, while trial-based testing resulted in only 30-35% correct detections at that false alarm rate. The performance improvement was due to anti-correlations in the afferent spike train, which reduced both the amplitude and duration of fluctuations in postsynaptic membrane activity, and so decreased the number of false alarms. Anti-correlations can be exploited to improve detection performance only if there is memory of prior decisions.

Energy conservation attenuates the loss of skeletal muscle excitability during intense contractions

DEFF Research Database (Denmark)

Macdonald, W A; Ørtenblad, N; Nielsen, Ole Bækgaard

2007-01-01

High-frequency stimulation of skeletal muscle has long been associated with ionic perturbations, resulting in the loss of membrane excitability, which may prevent action potential propagation and result in skeletal muscle fatigue. Associated with intense skeletal muscle contractions are large...... with control muscles, the resting metabolites ATP, phosphocreatine, creatine, and lactate, as well as the resting muscle excitability as measured by M-waves, were unaffected by treatment with BTS plus dantrolene. Following 20 or 30 s of continuous 60-Hz stimulation, BTS-plus-dantrolene-treated muscles showed...... changes in muscle metabolites. However, the role of metabolites in the loss of muscle excitability is not clear. The metabolic state of isolated rat extensor digitorum longus muscles at 30 degrees C was manipulated by decreasing energy expenditure and thereby allowed investigation of the effects of energy...

Effect of neonatal capsaicin treatment on neural activity in the medullary dorsal horn of neonatal rats evoked by electrical stimulation to the trigeminal afferents: an optical, electrophysiological, and quantitative study.

Science.gov (United States)

Takuma, S

2001-07-06

To elucidate which glutamate receptors, NMDA or non-NMDA, have the main role in synaptic transmission via unmyelinated afferents in the trigeminal subnucleus caudalis (the medullary dorsal horn), and to examine the early functional effects of neonatal capsaicin treatment to the subnucleus caudalis, optical recording, field potential recording, and quantitative study using electron micrographs were employed. A medulla oblongata isolated from a rat 5--7 days old was sectioned horizontally 400-microm thick or parasagittally and stained with a voltage-sensitive dye, RH482 or RH795. Single-pulse stimulation with high intensity to the trigeminal afferents evoked optical responses mainly in the subnucleus caudalis. The optical signals were composed of two phases, a fast component followed by a long-lasting component. The spatiotemporal properties of the optical signals were well correlated to those of the field potentials recorded simultaneously. The fast component was eliminated by 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX; 10 microM), while the long-lasting component was not. The latter increased in amplitude under a condition of low Mg(2+) but was significantly reduced by DL-2-amino-5-phosphonovaleric acid (AP5; 30 microM). Neonatal capsaicin treatment also reduced the long-lasting component markedly. In addition, the decreases in the ratio of unmyelinated axons to myelinated axons and in the ratio of unmyelinated axons to Schwann cell subunits of trigeminal nerve roots both showed significant differences (P<0.05, Student's t-test) between the control group and the neonatal capsaicin treatment group. This line of evidence indirectly suggests that synaptic transmission via unmyelinated afferents in the subnucleus caudalis is mediated substantially by NMDA glutamate receptors and documented that neonatal capsaicin treatment induced a functional alteration of the neural transmission in the subnucleus caudalis as well as a morphological alteration of primary afferents

Oxygen Generating Biomaterials Preserve Skeletal Muscle Homeostasis under Hypoxic and Ischemic Conditions

Science.gov (United States)

2013-08-26

injection” protocol for myogenic cell transplantation throughout large volumes of muscles in a Duchenne muscular dystrophy patient: eighteen months follow-up...Oxygen Generating Biomaterials Preserve Skeletal Muscle Homeostasis under Hypoxic and Ischemic Conditions Catherine L. Ward, Benjamin T. Corona...investigation was to determine if sodium percarbonate (SPO), an oxygen generating biomaterial, is capable of maintaining resting skeletal muscle

Control performance of pneumatic artificial muscle

Science.gov (United States)

Saga, Norihiko; Chonan, Seiji

2007-01-01

The robot in the future will be lightened and, in addition, the complex tasks will be done by the consumption of less energy. To achieve this, the development of an artificial muscle actuator which is as soft as a human-being becomes indispensable. At present, the artificial muscle actuator used is the McKibben type, but the heat and mechanical loss of this actuator are large because of the friction caused by the expansion and contraction of the sleeve. Therefore, we developed the artificial muscle tube where the Carbon fiber of the high intensity had been built into the silicon tube. In this report, the results of the examined the mechanical property of silicone rubber is reported, and the shrinking characteristics, response characteristics, and control performance as a pneumatic actuator are reported.

Protonmotive force in muscle mitochondria

International Nuclear Information System (INIS)

Stumpf, D.A.; Haas, R.; Eguren, L.A.; Parks, J.K.; Eilert, R.E.

1982-01-01

The protonmotive force (delta p) of muscle mitochondria was measured by estimating the distribution of 14C-labeled TPMP (trimethylphenylphosphonium iodide) and 14C-labeled acetate across the inner membrane of muscle mitochondria. The matrix volume was simultaneously determined using 3H-labeled H2O and 3H-labeled mannitol and repeated drying to distinguish the label in these 2 compounds. Rapid separation of mitochondria from the incubation medium by centrifugation through silicone oil avoids the problems of potential anaerobic conditions associated with conventional centrifugation and large volumes of trapped media associated with filtration. The value for delta p (mean +/- SD) was 192+/- 26 mV in 30 determinations with rat muscle mitochondria during state 4. Measurement of oxygen consumption allowed calculation of membrane conductance (Cm,H+) which was 0.49 +/- 0.18 nmol of H+/min/mg protein/mV. The values for delta p and Cm,H+ are reported for a variety of experimental conditions and are consistent with Mitchell's chemiosmotic theory. Biopsy specimens obtained from human muscle gave state-4 delta p values of 197+/- 30 mV (n .5) and Cm,H+ values of 0.52 +/- 0.12 nmol of H+/min/mg/mV (n . 4). This delta p assay is the first described for coupled mammalian muscle mitochondria and will be useful in assessing membrane function

MicroRNA Dysregulation in Aging and Pathologies of the Skeletal Muscle.

Science.gov (United States)

McCormick, Rachel; Goljanek-Whysall, Katarzyna

2017-01-01

Skeletal muscle is one of the biggest organs of the body with important mechanistic and metabolic functions. Muscle homeostasis is controlled by environmental, genetic, and epigenetic factors. Indeed, MiRNAs, small noncoding RNAs robust regulators of gene expression, have and have been shown to regulate muscle homeostasis on several levels: through controlling myogenesis, muscle growth (hypertrophy) and atrophy, as well as interactions of muscle with other tissues. Given the large number of MiRNA target genes and the important role of MiRNAs in most physiological processes and various diseases, MiRNAs may have an enormous potential as therapeutic targets against numerous disorders, including pathologies of muscle. The purpose of this review is to present the current knowledge of the role of MiRNAs in skeletal muscle homeostasis and pathologies and the potential of MiRNAs as therapeutics for skeletal muscle wasting, with particular focus on the age- and disease-related loss of muscle mass and function. © 2017 Elsevier Inc. All rights reserved.

Changes in motor unit behavior following isometric fatigue of the first dorsal interosseous muscle

Science.gov (United States)

Rymer, William Z.; Lowery, Madeleine M.; Suresh, Nina L.

2015-01-01

The neuromuscular strategies employed to compensate for fatigue-induced muscle force deficits are not clearly understood. This study utilizes surface electromyography (sEMG) together with recordings of a population of individual motor unit action potentials (MUAPs) to investigate potential compensatory alterations in motor unit (MU) behavior immediately following a sustained fatiguing contraction and after a recovery period. EMG activity was recorded during abduction of the first dorsal interosseous in 12 subjects at 20% maximum voluntary contraction (MVC), before and directly after a 30% MVC fatiguing contraction to task failure, with additional 20% MVC contractions following a 10-min rest. The amplitude, duration and mean firing rate (MFR) of MUAPs extracted with a sEMG decomposition system were analyzed, together with sEMG root-mean-square (RMS) amplitude and median frequency (MPF). MUAP duration and amplitude increased immediately postfatigue and were correlated with changes to sEMG MPF and RMS, respectively. After 10 min, MUAP duration and sEMG MPF recovered to prefatigue values but MUAP amplitude and sEMG RMS remained elevated. MU MFR and recruitment thresholds decreased postfatigue and recovered following rest. The increase in MUAP and sEMG amplitude likely reflects recruitment of larger MUs, while recruitment compression is an additional compensatory strategy directly postfatigue. Recovery of MU MFR in parallel with MUAP duration suggests a possible role for metabolically sensitive afferents in MFR depression postfatigue. This study provides insight into fatigue-induced neuromuscular changes by examining the properties of a large population of concurrently recorded single MUs and outlines possible compensatory strategies involving alterations in MU recruitment and MFR. PMID:25761952

Muscle metabolism during graded quadriceps exercise in man

DEFF Research Database (Denmark)

Helge, Jørn W; Stallknecht, Bente; Galbo, Henrik

2007-01-01

, oxidation of plasma free fatty acids increases and accordingly oxidation of other fat sources decreases. These findings are in contrast to whole body measurements performed during graded exercise involving a large muscle mass during which fat oxidation peaks at around 60% of .......The aim of the study was to examine local muscle metabolism in response to graded exercise when the involved muscle mass is too small to elicit marked hormonal changes and local blood flow restriction. Nine healthy overnight fasted male subjects performed knee extension exercise with both thighs...... intensity. In conclusion, in the presence of a high blood flow and oxygen supply and only small hormonal changes, total fat oxidation in muscle increases from rest to light exercise, but then remains constant with exercise intensity up to heavy exercise. However, with increasing exercise intensity...

Wnt and β-Catenin Signaling and Skeletal Muscle Myogenesis in Response to Muscle Damage and Resistance Exercise and Training

Directory of Open Access Journals (Sweden)

Dan Newmire

2015-10-01

Full Text Available The factors that regulate skeletal muscle hypertrophy in human adults in response to resistance training (RT has largely focused on endogenous endocrine responses. However, the endocrine response to RT as having an obligatory role in muscle hypertrophy has come under scrutiny, as other mechanisms and pathways seem to also be involved in up-regulating muscle protein synthesis (MPS. Skeletal muscle myogenesis is a multifactorial process of tissue growth and repair in response to resistance training is regulated by many factors.  As a result, satellite cell-fused myogenesis is a possible factor in skeletal muscle regeneration and hypertrophy in response to RT.  The Wnt family ligands interact with various receptors and activate different downstream signaling pathways and have been classified as either canonical (β-catenin dependent or non-canonical (β-catenin independent.  Wnt is secreted from numerous tissues in a paracrine fashion. The Wnt/β-catenin signaling pathway is a highly-regulated and intricate pathway that is essential to skeletal muscle myogenesis.  The canonical Wnt/β-catenin pathway may influence satellite cells to myogenic commitment, differentiation, and fusion into muscle fibers in response to injury or trauma, self-renewal, and normal basal turnover.  The current literature has shown that, in response mechanical overload from acute resistance exercise and chronic resistance training, that the Wnt/β-catenin signaling pathway is stimulated which may actuate the process of muscle repair and hypertrophy in response to exercise-induced muscle damage. The purpose of this review is to elaborate on the Wnt/β-catenin signaling  pathway, the current literature investigating the relationship of the Wnt/β-catenin pathway and its effects on myogenesis is response to muscle damage and resistance exercise and training.      Keywords: skeletal muscle, hypertrophy, myogenesis, cell signaling, protein synthesis, resistance

Rotator cuff muscle degeneration and tear severity related to myogenic, adipogenic, and atrophy genes in human muscle.

Science.gov (United States)

Shah, Shivam A; Kormpakis, Ioannis; Cavinatto, Leonardo; Killian, Megan L; Thomopoulos, Stavros; Galatz, Leesa M

2017-12-01

Large rotator cuff tear size and advanced muscle degeneration can affect reparability of tears and compromise tendon healing. Clinicians often rely on direct measures of rotator cuff tear size and muscle degeneration from magnetic resonance imaging (MRI) to determine whether the rotator cuff tear is repairable. The objective of this study was to identify the relationship between gene expression changes in rotator cuff muscle degeneration to standard data available to clinicians. Radiographic assessment of preoperative rotator cuff tear severity was completed for 25 patients with varying magnitudes of rotator cuff tears. Tear width and retraction were measured using MRI, and Goutallier grade, tangent (tan) sign, and Thomazeau grade were determined. Expression of myogenic-, adipogenic-, atrophy-, and metabolism-related genes in biopsied muscles were correlated with tear width, tear retraction, Goutallier grade, tan sign, and Thomazeau grade. Tear width positively correlated with Goutallier grade in both the supraspinatus (r = 0.73) and infraspinatus (r = 0.77), along with tan sign (r = 0.71) and Thomazeau grade (r = 0.68). Decreased myogenesis (Myf5), increased adipogenesis (CEBPα, Lep, Wnt10b), and decreased metabolism (PPARα) correlated with radiographic assessments. Gene expression changes suggest that rotator cuff tears lead to a dramatic molecular response in an attempt to maintain normal muscle tissue, increase adipogenesis, and decrease metabolism. Fat accumulation and muscle atrophy appear to stem from endogenous changes rather than from changes mediated by infiltrating cells. Results suggest that chronic unloading of muscle, induced by rotator cuff tear, disrupts muscle homeostasis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2808-2814, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Muscle mechanics and neuromuscular control

NARCIS (Netherlands)

Hof, AL

The purpose of this paper is to demonstrate that the properties of the mechanical system, especially muscle elasticity and limb mass, to a large degree determine force output and movement. This makes the control demands of the central nervous system simpler and more robust. In human triceps surae, a

Blockade of acid sensing ion channels attenuates the exercise pressor reflex in cats.

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Hayes, Shawn G; Kindig, Angela E; Kaufman, Marc P

2007-06-15

Although thin fibre muscle afferents possess acid sensing ion channels (ASICs), their contribution to the exercise pressor reflex is not known. This lack of information is partly attributable to the fact that there is no known selective in vivo antagonist for ASICs. Although amiloride has been shown to antagonize ASICs, it also has been shown to antagonize voltage-gated sodium channels, thereby impairing impulse conduction in sensory nerves. Our aim was to test the hypothesis that lactic acid accumulation in exercising muscle acted on ASICs located on thin fibre muscle afferents to evoke the metabolic component of the exercise pressor reflex. To test this hypothesis, we determined in decerebrate cats if amiloride attenuated the pressor and cardioaccelerator responses to static contraction, to tendon stretch and to arterial injections of lactic acid and capsaicin. We found a dose of amiloride (0.5 microg kg(-1); i.a.) that attenuated the pressor and cardioaccelerator responses to both contraction and lactic acid injection, but had no effect on the responses to stretch and capsaicin. A higher dose of amiloride (5 microg kg(-1), i.a.) not only blocked the pressor and cardioaccelerator responses to lactic acid and contraction, but also attenuated the responses to stretch and to capsaicin, manoeuvers in which ASICs probably play no significant role. In addition, we found that the low dose of amiloride (0.5 microg kg(-1)) had no effect on the responses of muscle spindles to tendon stretch and to succinylcholine, whereas the high dose (5 microg kg(-1)) attenuated the responses to both. Our data suggest the low dose of amiloride used in our experiments selectively blocked ASICs, whereas the high dose blocked ASICs and impulse conduction in muscle afferents. We conclude that ASICs play a role in the metabolic component of the exercise pressor reflex.

Electrically controllable artificial PAN muscles

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Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

1996-02-01

Artificial muscles made with polyacrylonitrile (PAN) fibers are traditionally activated in electrolytic solution by changing the pH of the solution by the addition of acids and/or bases. This usually consumes a considerable amount of weak acids or bases. Furthermore, the synthetic muscle (PAN) itself has to be impregnated with an acid or a base and must have an appropriate enclosure or provision for waste collection after actuation. This work introduces a method by which the PAN muscle may be elongated or contracted in an electric field. We believe this is the first time that this has been achieved with PAN fibers as artificial muscles. In this new development the PAN muscle is first put in close contact with one of the two platinum wires (electrodes) immersed in an aqueous solution of sodium chloride. Applying an electric voltage between the two wires changes the local acidity of the solution in the regions close to the platinum wires. This is because of the ionization of sodium chloride molecules and the accumulation of Na+ and Cl- ions at the negative and positive electrode sites, respectively. This ion accumulation, in turn, is accompanied by a sharp increase and decrease of the local acidity in regions close to either of the platinum wires, respectively. An artificial muscle, in close contact with the platinum wire, because of the change in the local acidity will contract or expand depending on the polarity of the electric field. This scheme allows the experimenter to use a fixed flexible container of an electrolytic solution whose local pH can be modulated by an imposed electric field while the produced ions are basically trapped to stay in the neighborhood of a given electrode. This method of artificial muscle activation has several advantages. First, the need to use a large quantity of acidic or alkaline solutions is eliminated. Second, the use of a compact PAN muscular system is facilitated for applications in active musculoskeletal structures. Third, the

Modeling of the energy savings of variable recruitment McKibben muscle bundles

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Meller, Michael A.; Chipka, Jordan B.; Bryant, Matthew J.; Garcia, Ephrahim

2015-03-01

McKibben artificial muscles are often utilized in mobile robotic applications that require compliant and light weight actuation capable of producing large forces. In order to increase the endurance of these mobile robotic platforms, actuation efficiency must be addressed. Since pneumatic systems are rarely more than 30% efficient due to the compressibility of the working fluid, the McKibben muscles are hydraulically powered. Additionally, these McKibben artificial muscles utilize an inelastic bladder to reduce the energy losses associated with elastic energy storage in the usual rubber tube bladders. The largest energy losses in traditional valve-controlled hydraulic systems are found in the valving implementation to match the required loads. This is performed by throttling, which results in large pressure drops over the control valves and significant fluid power being wasted as heat. This paper discusses how these throttling losses are reduced by grouping multiple artificial muscles to form a muscle bundle where, like in skeletal muscle, more elements that make up the muscle bundle are recruited to match the load. This greatly lessens the pressure drops by effectively changing the actuator area, leading to much higher efficiencies over a broader operation envelope. Simulations of several different loading scenarios are discussed that reveal the benefits of such an actuation scheme.

Children with migraine: Provocation of headache via pressure to myofascial trigger points in the trapezius muscle? - A prospective controlled observational study.

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Landgraf, M N; Biebl, J T; Langhagen, T; Hannibal, I; Eggert, T; Vill, K; Gerstl, L; Albers, L; von Kries, R; Straube, A; Heinen, F

2018-02-01

The objective was to evaluate a supposed clinical interdependency of myofascial trigger points and migraine in children. Such interdependency would support an interaction of spinal and trigeminal afferences in the trigemino-cervical complex as a contributing factor in migraine. Children ≤18 years with the confirmed diagnosis of migraine were prospectively investigated. Comprehensive data on medical history, clinical neurological and psychological status were gathered. Trigger points in the trapezius muscle were identified by palpation and the threshold of pressure pain at these points was measured. Manual pressure was applied to the trigger points, and the occurrence and duration of induced headache were recorded. At a second consultation (4 weeks after the first), manual pressure with the detected pressure threshold was applied to non-trigger points within the same trapezius muscle (control). Headache and related parameters were again recorded and compared to the results of the first consultation. A total of 13 girls and 13 boys with migraine and a median age of 14.5 (Range 6.3-17.8) years took part in the study. Manual pressure to trigger points in the trapezius muscle led to lasting headache after termination of the manual pressure in 13 patients while no patient experienced headache when manual pressure was applied to non-trigger points at the control visit (p complex, especially in adolescents. In children with migraine headache can often be induced by pressure to myofascial trigger points, but not by pressure to non-trigger points in the trapezius muscle. This supports the hypothesis of a trigemino-cervical-complex in the pathophysiology of migraine, which might have implications for innovative therapies in children with migraine. © 2017 European Pain Federation - EFIC®.

Comparative anatomy of the cheek muscles within the Centromochlinae subfamily (Ostariophysi, Siluriformes, Auchenipteridae).

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Sarmento-Soares, Luisa Maria; Porto, Marcovan

2006-02-01

Glanidium melanopterum Miranda Ribeiro, a typical representative of the subfamily Centromochlinae (Siluriformes: Auchenipteridae), is herein described myologically and compared to other representative species within the group, Glanidium ribeiroi, G. leopardum, Tatia neivai, T. intermedia, T. creutzbergi, Centromochlus heckelii, and C. existimatus. The structure of seven pairs of striated cephalic muscles was compared anatomically: adductor mandibulae, levator arcus palatini, dilatator operculi, adductor arcus palatini, extensor tentaculi, retractor tentaculi, and levator operculi. We observed broad adductor mandibulae muscles in both Glanidium and Tatia, catfishes with depressed heads and smaller eyes. Similarities between muscles were observed: the presence of a large aponeurotic insertion for the levator arcus palatini muscle; an adductor arcus palatini muscle whose origin spread over the orbitosphenoid, pterosphenoid, and parasphenoid; and the extensor tentaculi muscle broadly attached to the autopalatine. There is no retractor tentaculi muscle in either the Glanidium or Tatia species. On the other hand, in Centromochlus, with forms having large eyes and the tallest head, the adductor mandibulae muscles are slim; there is a thin aponeurotic or muscular insertion for the levator arcus palatini muscle; the adductor arcus palatini muscle originates from a single osseous process, forming a keel on the parasphenoid; the extensor tentaculi muscle is loosely attached to the autopalatine, permitting exclusive rotating and sliding movements between this bone and the maxillary. The retractor tentaculi muscle is connected to the maxilla through a single tendon, so that both extensor and retractor tentaculi muscles contribute to a wide array of movements of the maxillary barbels. A discussion on the differences in autopalatine-maxillary movements among the analyzed groups is given. (c) 2005 Wiley-Liss, Inc.

Feasibility of Muscle Synergy Outcomes in Clinics, Robotics, and Sports: A Systematic Review

Directory of Open Access Journals (Sweden)

Juri Taborri

2018-01-01

Full Text Available In the last years, several studies have been focused on understanding how the central nervous system controls muscles to perform a specific motor task. Although it still remains an open question, muscle synergies have come to be an appealing theory to explain the modular organization of the central nervous system. Even though the neural encoding of muscle synergies remains controversial, a large number of papers demonstrated that muscle synergies are robust across different tested conditions, which are within a day, between days, within a single subject, and between subjects that have similar demographic characteristics. Thus, muscle synergy theory has been largely used in several research fields, such as clinics, robotics, and sports. The present systematical review aims at providing an overview on the applications of muscle synergy theory in clinics, robotics, and sports; in particular, the review is focused on the papers that provide tangible information for (i diagnosis or pathology assessment in clinics, (ii robot-control design in robotics, and (iii athletes’ performance assessment or training guidelines in sports.

STAT3 Activation in Skeletal Muscle Links Muscle Wasting and the Acute Phase Response in Cancer Cachexia

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Kunzevitzky, Noelia; Guttridge, Denis C.; Khuri, Sawsan; Koniaris, Leonidas G.; Zimmers, Teresa A.

2011-01-01

Background Cachexia, or weight loss despite adequate nutrition, significantly impairs quality of life and response to therapy in cancer patients. In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response. Acute phase proteins, including fibrinogen and serum amyloid A (SAA) are synthesized by hepatocytes in response to IL-6 as part of the innate immune response. To gain insight into the relationships among these observations, we studied mice with moderate and severe Colon-26 (C26)-carcinoma cachexia. Methodology/Principal Findings Moderate and severe C26 cachexia was associated with high serum IL-6 and IL-6 family cytokines and highly similar patterns of skeletal muscle gene expression. The top canonical pathways up-regulated in both were the complement/coagulation cascade, proteasome, MAPK signaling, and the IL-6 and STAT3 pathways. Cachexia was associated with increased muscle pY705-STAT3 and increased STAT3 localization in myonuclei. STAT3 target genes, including SOCS3 mRNA and acute phase response proteins, were highly induced in cachectic muscle. IL-6 treatment and STAT3 activation both also induced fibrinogen in cultured C2C12 myotubes. Quantitation of muscle versus liver fibrinogen and SAA protein levels indicates that muscle contributes a large fraction of serum acute phase proteins in cancer. Conclusions/Significance These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer. Through IL-6/STAT3 activation, skeletal muscle is induced to synthesize acute phase proteins, thus establishing a molecular link between the observations of high IL-6, increased acute phase response proteins and muscle wasting in cancer. These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such

Sex hormones and skeletal muscle weakness

DEFF Research Database (Denmark)

Sipilä, Sarianna; Narici, Marco; Kjaer, Michael

2013-01-01

Human ageing is accompanied with deterioration in endocrine functions the most notable and well characterized of which being the decrease in the production of sex hormones. Current research literature suggests that low sex hormone concentration may be among the key mechanism for sarcopenia...... and muscle weakness. Within the European large scale MYOAGE project, the role of sex hormones, estrogens and testosterone, in causing the aging-related loss of muscle mass and function was further investigated. Hormone replacement therapy (HRT) in women is shown to diminish age-associated muscle loss, loss...... properties. HRT influences gene expression in e.g. cytoskeletal and cell-matrix proteins, has a stimulating effect upon IGF-I, and a role in IL-6 and adipokine regulation. Despite low circulating steroid-hormone level, postmenopausal women have a high local concentration of steroidogenic enzymes in skeletal...

The muscle stem cell niche : regulation of satellite cells during regeneration

NARCIS (Netherlands)

Boonen, K.J.M.; Post, M.J.

2008-01-01

Satellite cells are considered to be adult skeletal muscle stem cells. Their ability to regenerate large muscle defects is highly dependent on their specific niche. When these cells are cultured in vitro, the loss of this niche leads to a loss of proliferative capacity and defective regeneration

CORRELATIONS BETWEEN MUSCLE MASS, MUSCLE STRENGTH, PHYSICAL PERFORMANCE, AND MUSCLE FATIGUE RESISTANCE IN COMMUNITY-DWELLING ELDERLY SUBJECTS

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Elizabeth

2016-03-01

Full Text Available Objective: To determine the correlations between muscle mass, muscle strength, physical performance, and muscle fatigue resistance in community-dwelling elderly people in order to elucidate factors which contribute to elderly’s performance of daily activities. Methods: A cross-sectional study was conducted on community-dwelling elderly in Bandung from September to December 2014. One hundred and thirty elderly, 60 years old or above, were evaluated using bioelectrical impedance analysis to measure muscle mass; grip strength to measure muscle strength and muscle fatigue resistance; habitual gait speed to measure physical performance; and Global Physical Activity Questionnaire (GPAQ to assess physical activity. Results: There were significant positive correlations between muscle mass (r=0,27, p=0,0019, muscle strength (r=0,26, p=0,0024, and physical performance (r=0,32, p=0,0002 with muscle fatigue resistance. Physical performance has the highest correlation based on multiple regression test (p=0,0025. In association with muscle mass, the physical activity showed a significant positive correlation (r=0,42, p=0,0000. Sarcopenia was identified in 19 (14.61% of 130 subjects. Conclusions: It is suggested that muscle mass, muscle strength, and physical performance influence muscle fatigue resistance.

A new model of strabismic amblyopia: Loss of spatial acuity due to increased temporal dispersion of geniculate X-cell afferents on to cortical neurons.

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Crewther, D P; Crewther, S G

2015-09-01

Although the neural locus of strabismic amblyopia has been shown to lie at the first site of binocular integration, first in cat and then in primate, an adequate mechanism is still lacking. Here we hypothesise that increased temporal dispersion of LGN X-cell afferents driven by the deviating eye onto single cortical neurons may provide a neural mechanism for strabismic amblyopia. This idea was investigated via single cell extracellular recordings of 93 X and 50 Y type LGN neurons from strabismic and normal cats. Both X and Y neurons driven by the non-deviating eye showed shorter latencies than those driven by either the strabismic or normal eyes. Also the mean latency difference between X and Y neurons was much greater for the strabismic cells compared with the other two groups. The incidence of lagged X-cells driven by the deviating eye of the strabismic cats was higher than that of LGN X-cells from normal animals. Remarkably, none of the cells recorded from the laminae driven by the non-deviating eye were of the lagged class. A simple computational model was constructed in which a mixture of lagged and non-lagged afferents converge on to single cortical neurons. Model cut-off spatial frequencies to a moving grating stimulus were sensitive to the temporal dispersion of the geniculate afferents. Thus strabismic amblyopia could be viewed as a lack of developmental tuning of geniculate lags for neurons driven by the amblyopic eye. Monocular control of fixation by the non-deviating eye is associated with reduced incidence of lagged neurons, suggesting that in normal vision, lagged neurons might play a role in maintaining binocular connections for cortical neurons. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of respiratory muscle training (RMT) in children with infantile-onset Pompe disease and respiratory muscle weakness.

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Jones, Harrison N; Crisp, Kelly D; Moss, Tronda; Strollo, Katherine; Robey, Randy; Sank, Jeffrey; Canfield, Michelle; Case, Laura E; Mahler, Leslie; Kravitz, Richard M; Kishnani, Priya S

2014-01-01

Respiratory muscle weakness is a primary therapeutic challenge for patients with infantile Pompe disease. We previously described the clinical implementation of a respiratory muscle training (RMT) regimen in two adults with late-onset Pompe disease; both demonstrated marked increases in inspiratory and expiratory muscle strength in response to RMT. However, the use of RMT in pediatric survivors of infantile Pompe disease has not been previously reported. We report the effects of an intensive RMT program on maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) using A-B-A (baseline-treatment-posttest) single subject experimental design in two pediatric survivors of infantile Pompe disease. Both subjects had persistent respiratory muscle weakness despite long-term treatment with alglucosidase alfa. Subject 1 demonstrated negligible to modest increases in MIP/MEP (6% increase in MIP, d=0.25; 19% increase in MEP, d=0.87), while Subject 2 demonstrated very large increases in MIP/MEP (45% increase in MIP, d=2.38; 81% increase in MEP, d=4.31). Following three-month RMT withdrawal, both subjects maintained these strength increases and demonstrated maximal MIP and MEP values at follow-up. Intensive RMT may be a beneficial treatment for respiratory muscle weakness in pediatric survivors of infantile Pompe disease.

MUSCLE: multiple sequence alignment with high accuracy and high throughput.

Science.gov (United States)

Edgar, Robert C

2004-01-01

We describe MUSCLE, a new computer program for creating multiple alignments of protein sequences. Elements of the algorithm include fast distance estimation using kmer counting, progressive alignment using a new profile function we call the log-expectation score, and refinement using tree-dependent restricted partitioning. The speed and accuracy of MUSCLE are compared with T-Coffee, MAFFT and CLUSTALW on four test sets of reference alignments: BAliBASE, SABmark, SMART and a new benchmark, PREFAB. MUSCLE achieves the highest, or joint highest, rank in accuracy on each of these sets. Without refinement, MUSCLE achieves average accuracy statistically indistinguishable from T-Coffee and MAFFT, and is the fastest of the tested methods for large numbers of sequences, aligning 5000 sequences of average length 350 in 7 min on a current desktop computer. The MUSCLE program, source code and PREFAB test data are freely available at http://www.drive5. com/muscle.

Transposition and Intermingling of Galphai2 and Galphao afferences into single vomeronasal glomeruli in the Madagascan lesser Tenrec Echinops telfairi.

Directory of Open Access Journals (Sweden)

Rodrigo Suárez

2009-11-01

Full Text Available The vomeronasal system (VNS mediates pheromonal communication in mammals. From the vomeronasal organ, two populations of sensory neurons, expressing either Galphai2 or Galphao proteins, send projections that end in glomeruli distributed either at the rostral or caudal half of the accessory olfactory bulb (AOB, respectively. Neurons at the AOB contact glomeruli of a single subpopulation. The dichotomic segregation of AOB glomeruli has been described in opossums, rodents and rabbits, while Primates and Laurasiatheres present the Galphai2-pathway only, or none at all (such as apes, some bats and aquatic species. We studied the AOB of the Madagascan lesser tenrec Echinops telfairi (Afrotheria: Afrosoricida and found that Galphai2 and Galphao proteins are expressed in rostral and caudal glomeruli, respectively. However, the segregation of vomeronasal glomeruli at the AOB is not exclusive, as both pathways contained some glomeruli transposed into the adjoining subdomain. Moreover, some glomeruli seem to contain intermingled afferences from both pathways. Both the transposition and heterogeneity of vomeronasal afferences are features, to our knowledge, never reported before. The organization of AOB glomeruli suggests that synaptic integration might occur at the glomerular layer. Whether intrinsic AOB neurons may make synaptic contact with axon terminals of both subpopulations is an interesting possibility that would expand our understanding about the integration of vomeronasal pathways.

Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.

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Katsetos, Christos D; Bianchi, Michael A; Jaffery, Fizza; Koutzaki, Sirma; Zarella, Mark; Slater, Robert

2014-06-01

An instance of isolated unilateral temporalis muscle hypertrophy (reactive masticatory muscle hypertrophy with fiber type 1 predominance) confirmed by muscle biopsy with histochemical fiber typing and image analysis in a 62 year-old man is reported. The patient presented with bruxism and a painful swelling of the temple. Absence of asymmetry or other abnormalities of the craniofacial skeleton was confirmed by magnetic resonance imaging and cephalometric analyses. The patient achieved symptomatic improvement only after undergoing botulinum toxin injections. Muscle biopsy is key in the diagnosis of reactive masticatory muscle hypertrophy and its distinction from masticatory muscle myopathy (hypertrophic branchial myopathy) and other non-reactive causes of painful asymmetric temporalis muscle enlargement.

Regulatory T cells suppress muscle inflammation and injury in muscular dystrophy

Science.gov (United States)

Villalta, S. Armando; Rosenthal, Wendy; Martinez, Leonel; Kaur, Amanjot; Sparwasser, Tim; Tidball, James G.; Margeta, Marta; Spencer, Melissa J.; Bluestone, Jeffrey A.

2016-01-01

We examined the hypothesis that regulatory T cells (Tregs) modulate muscle injury and inflammation in the mdx mouse model of Duchenne muscular dystrophy (DMD). Although Tregs were largely absent in the muscle of wildtype mice and normal human muscle, they were present in necrotic lesions, displayed an activated phenotype and showed increased expression of interleukin (IL)-10 in dystrophic muscle from mdx mice. Depletion of Tregs exacerbated muscle injury and the severity of muscle inflammation, which was characterized by an enhanced interferon-gamma (IFNγ) response and activation of M1 macrophages. To test the therapeutic value of targeting Tregs in muscular dystrophy, we treated mdx mice with IL-2/anti-IL-2 complexes (IL-2c), and found that Tregs and IL-10 concentrations were increased in muscle, resulting in reduced expression of cyclooygenase-2 and decreased myofiber injury. These findings suggest that Tregs modulate the progression of muscular dystrophy by suppressing type 1 inflammation in muscle associated with muscle fiber injury, and highlight the potential of Treg-modulating agents as therapeutics for DMD. PMID:25320234

Identification and characterization of novel smoothelin isoforms in vascular smooth muscle.

Science.gov (United States)

Krämer, J; Quensel, C; Meding, J; Cardoso, M C; Leonhardt, H

2001-01-01

Smoothelin is a cytoskeletal protein specifically expressed in differentiated smooth muscle cells and has been shown to colocalize with smooth muscle alpha actin. In addition to the small smoothelin isoform of 59 kD, we recently identified a large smoothelin isoform of 117 kD. The aim of this study was to identify and characterize novel smoothelin isoforms. The genomic structure and sequence of the smoothelin gene were determined by genomic PCR, RT-PCR and DNA sequencing. Comparison of the cDNA and genomic sequences shows that the small smoothelin isoform is generated by transcription initiation 10 kb downstream of the start site of the large isoform. In addition to the known smoothelin cDNA (c1 isoform) we identified two novel cDNA variants (c2 and c3 isoform) that are generated by alternative splicing within a region, which shows similarity to the spectrin family of F-actin cross-linking proteins. Visceral organs express the c1 form, while the c2 form prevails in well-vascularized tissue as analyzed by RT-PCR. We then generated specific antibodies against the major smoothelin isoforms and could show by Western blotting and immunohistochemistry that the large isoform is specifically expressed in vascular smooth muscle cells, while the small isoform is abundant in visceral smooth muscle. These results strongly suggest that the smoothelin gene contains a vascular and a visceral smooth muscle promoter. The cell-type-specific expression of smoothelin isoforms that are associated with actin filaments may play a role in the modulation of the contractile properties of different smooth muscle cell types. Copyright 2001 S. Karger AG, Basel

Evaluation of muscle hyperactivity of the grimacing muscles by unilateral tight eyelid closure and stapedius muscle tone.

Science.gov (United States)

Shiba, Masato; Matsuo, Kiyoshi; Ban, Ryokuya; Nagai, Fumio

2012-10-01

Muscle hyperactivity of grimacing muscles, including the orbicularis oculi and corrugator supercilii muscles that cause crow's feet and a glabellar frown line with ageing, cannot be accurately evaluated by surface observation. In 71 subjects, this study investigated the extent to which grimacing muscles are innervated by the bilateral motor cortices, whether the corticofacial projection to the grimacing muscles affects the facially innervated stapedius muscle tone by measuring static compliance of the tympanic membrane, and whether unilateral tight eyelid closure with contraction of the grimacing muscles changes static compliance. Unilateral tight eyelid closure and its subsequent change in the contralateral vertical medial eyebrow position revealed that motor neurons of the orbicularis oculi and corrugator supercilii muscles were innervated by the bilateral motor cortices with weak-to-strong contralateral dominance. The orbicularis oculi, corrugator supercilii, and stapedius muscles innervated by the bilateral motor cortices had increased muscle hyperactivity, which lowered the vertical medial eyebrow position and decreased the static compliance of the tympanic membrane more than those innervated by the unilateral motor cortex. Unilateral enhanced tight eyelid closure with contraction of the grimacing muscles in certain subjects ipsilaterally decreased the static compliance with increased contraction of the stapedius muscle, which probably occurs to immobilise the tympanic membrane and protect the inner ear from loud sound. Evaluation of unilateral tight eyelid closure and the subsequent change in the contralateral vertical medial eyebrow position as well as a measurement of the static compliance for the stapedius muscle tone has revealed muscle hyperactivity of grimacing muscles.

Measuring anisotropic muscle stiffness properties using elastography.

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Green, M A; Geng, G; Qin, E; Sinkus, R; Gandevia, S C; Bilston, L E

2013-11-01

Physiological and pathological changes to the anisotropic mechanical properties of skeletal muscle are still largely unknown, with only a few studies quantifying changes in vivo. This study used the noninvasive MR elastography (MRE) technique, in combination with diffusion tensor imaging (DTI), to measure shear modulus anisotropy in the human skeletal muscle in the lower leg. Shear modulus measurements parallel and perpendicular to the fibre direction were made in 10 healthy subjects in the medial gastrocnemius, soleus and tibialis anterior muscles. The results showed significant differences in the medial gastrocnemius (μ‖ = 0.86 ± 0.15 kPa; μ⊥ = 0.66 ± 0.19 kPa, P < 0.001), soleus (μ‖ = 0.83 ± 0.22 kPa; μ⊥ = 0.65 ± 0.13 kPa, P < 0.001) and the tibialis anterior (μ‖ = 0.78 ± 0.24 kPa; μ⊥ = 0.66 ± 0.16 kPa, P = 0.03) muscles, where the shear modulus measured in the direction parallel is greater than that measured in the direction perpendicular to the muscle fibres. No significant differences were measured across muscle groups. This study provides the first direct estimates of the anisotropic shear modulus in the triceps surae muscle group, and shows that the technique may be useful for the probing of mechanical anisotropy changes caused by disease, aging and injury. Copyright © 2013 John Wiley & Sons, Ltd.

[Trigeminal purinergic P2X4 receptor involved in experimental occlusal interference-induced hyperalgesia in rat masseter muscle].

Science.gov (United States)

Xu, Xiaoxiang; Cao, Ye; Ding, Tingting; Fu, Kaiyuan; Xie, Qiufei

2016-03-01

To explore the expression of purinergic p2X4 receptor (P2X4R) in trigeminal ganglion of rats after occlusal interference. Investigation of peripheral receptor mechanism of occlusal interference-induced masticatory muscle pain will aid the development of drug intervention against this condition. Experimental occlusal interference was established by application of 0.4 mm metal crown to the upper right first molar of male Sprague-Dawley rats. Real-time PCR assay was used to investigate P2X4R mRNA level in trigeminal ganglion in rats with occlusal interference for 3, 7, 10 and 14 days and in control rats without occlusal interference (n=5 in each). Retrograde labelling combining immunofluorescence was performed to evaluate the percentage of P2X4R-positive cells in masseter afferent neurons (n=5 in each group). Graded concentrations of P2XR antagonist TNP-ATP (0.1, 10, 125, 250, 500 μmol/L) or saline (n=5 in each group) was administrated in right masseter and the mechanical sensitivity of bilateral masseters was measured before occlusal interference application, before the injection, and 30 min as well as 60 min after the injection. Compared with control rats (P2X4R mRNA: right side: 1.00±0.26, left side: 0.94± 0.21; percentage of P2X4R-positive masseter afferents: right side: [64.3±6.3]%, left side: [67.7±5.8]%), the level of P2X4R mRNA in bilateral trigeminal ganglia (right side: 5.98±3.56; left side: 5.06±2.88) of rats with occlusal interference for 7 days up-regulated (Pocclusal interference-induced masseter hyperalgesia.

Gene expression studies of developing bovine longissimus muscle from two different beef cattle breeds

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Byrne Keren A

2007-08-01

Full Text Available Abstract Background The muscle fiber number and fiber composition of muscle is largely determined during prenatal development. In order to discover genes that are involved in determining adult muscle phenotypes, we studied the gene expression profile of developing fetal bovine longissimus muscle from animals with two different genetic backgrounds using a bovine cDNA microarray. Fetal longissimus muscle was sampled at 4 stages of myogenesis and muscle maturation: primary myogenesis (d 60, secondary myogenesis (d 135, as well as beginning (d 195 and final stages (birth of functional differentiation of muscle fibers. All fetuses and newborns (total n = 24 were from Hereford dams and crossed with either Wagyu (high intramuscular fat or Piedmontese (GDF8 mutant sires, genotypes that vary markedly in muscle and compositional characteristics later in postnatal life. Results We obtained expression profiles of three individuals for each time point and genotype to allow comparisons across time and between sire breeds. Quantitative reverse transcription-PCR analysis of RNA from developing longissimus muscle was able to validate the differential expression patterns observed for a selection of differentially expressed genes, with one exception. We detected large-scale changes in temporal gene expression between the four developmental stages in genes coding for extracellular matrix and for muscle fiber structural and metabolic proteins. FSTL1 and IGFBP5 were two genes implicated in growth and differentiation that showed developmentally regulated expression levels in fetal muscle. An abundantly expressed gene with no functional annotation was found to be developmentally regulated in the same manner as muscle structural proteins. We also observed differences in gene expression profiles between the two different sire breeds. Wagyu-sired calves showed higher expression of fatty acid binding protein 5 (FABP5 RNA at birth. The developing longissimus muscle of

A population of Pax7-expressing muscle progenitor cells show differential responses to muscle injury dependent on developmental stage and injury extent

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Stefanie eKnappe

2015-08-01

Full Text Available Muscle regeneration in vertebrates occurs by the activation of quiescent progenitor cells that express pax7 and replace and repair damaged fibers. We have developed a mechanical injury paradigm in zebrafish to determine whether developmental stage and injury size affect the regeneration dynamics of damaged muscle. We found that both small, focal injuries and large injuries affecting the entire myotome lead to the expression of myf5 and myogenin. Their expression was prolonged in older larvae, indicating a slower process of regeneration. We characterized the endogenous behavior of a population of muscle-resident Pax7-expressing cells using a pax7a:eGFP transgenic line and found that GFP+ cell migration in the myotome dramatically declined between 5 and 7 days post fertilization (dpf. Following a small injury, we observed that GFP+ cells responded by extending processes, before migrating to the injured fibers. Furthermore, these cells responded more rapidly to injury in 4dpf larvae compared to 7dpf. Interestingly, we did not see GFP+ fibers after repair of small injuries, indicating that pax7a-expressing cells did not contribute to fiber formation in this injury context. On the contrary, numerous GFP+ fibers could be observed after a large single myotome injury. Both injury models were accompanied by an increased number of proliferating GFP+ cells, which was more pronounced in larvae injured at 4dpf than 7dpf, This indicates intriguing developmental differences, even at these relatively early ages. Our data also suggests an interesting disparity in the role that pax7a-expressing muscle progenitor cells play during muscle regeneration, which may reflect the extent of muscle damage.

Muscle force depends on the amount of transversal muscle loading.

Science.gov (United States)

Siebert, Tobias; Till, Olaf; Stutzig, Norman; Günther, Michael; Blickhan, Reinhard

2014-06-03

Skeletal muscles are embedded in an environment of other muscles, connective tissue, and bones, which may transfer transversal forces to the muscle tissue, thereby compressing it. In a recent study we demonstrated that transversal loading of a muscle with 1.3Ncm(-2) reduces maximum isometric force (Fim) and rate of force development by approximately 5% and 25%, respectively. The aim of the present study was to examine the influence of increasing transversal muscle loading on contraction dynamics. Therefore, we performed isometric experiments on rat M. gastrocnemius medialis (n=9) without and with five different transversal loads corresponding to increasing pressures of 1.3Ncm(-2) to 5.3Ncm(-2) at the contact area between muscle and load. Muscle loading was induced by a custom-made plunger which was able to move in transversal direction. Increasing transversal muscle loading resulted in an almost linear decrease in muscle force from 4.8±1.8% to 12.8±2% Fim. Compared to an unloaded isometric contraction, rate of force development decreased from 20.2±4.0% at 1.3Ncm(-2) muscle loading to 34.6±5.7% at 5.3Ncm(-2). Experimental observation of the impact of transversal muscle loading on contraction dynamics may help to better understand muscle tissue properties. Moreover, applying transversal loads to muscles opens a window to analyze three-dimensional muscle force generation. Data presented in this study may be important to develop and validate muscle models which enable simulation of muscle contractions under compression and enlighten the mechanisms behind. Copyright © 2014 Elsevier Ltd. All rights reserved.

Large asymmetric hypertrophy of rectus abdominis muscle in professional tennis players.

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Joaquin Sanchis-Moysi

Full Text Available PURPOSE: To determine the volume and degree of asymmetry of the musculus rectus abdominis (RA in professional tennis players. METHODS: The volume of the RA was determined using magnetic resonance imaging (MRI in 8 professional male tennis players and 6 non-active male control subjects. RESULTS: Tennis players had 58% greater RA volume than controls (P = 0.01, due to hypertrophy of both the dominant (34% greater volume, P = 0.02 and non-dominant (82% greater volume, P = 0.01 sides, after accounting for age, the length of the RA muscle and body mass index (BMI as covariates. In tennis players, there was a marked asymmetry in the development of the RA, which volume was 35% greater in the non-dominant compared to the dominant side (P<0.001. In contrast, no side-to-side difference in RA volume was observed in the controls (P = 0.75. The degree of side-to-side asymmetry increased linearly from the first lumbar disc to the pubic symphysis (r = 0.97, P<0.001. CONCLUSIONS: Professional tennis is associated with marked hypertrophy of the musculus rectus abdominis, which achieves a volume that is 58% greater than in non-active controls. Rectus abdominis hypertrophy is more marked in the non-dominant than in the dominant side, particularly in the more distal regions. Our study supports the concept that humans can differentially recruit both rectus abdominis but also the upper and lower regions of each muscle. It remains to be determined if this disequilibrium raises the risk of injury.

Intramuscular dissection of a large ganglion cyst into the gastrocnemius muscle.

Science.gov (United States)

Nicholson, Luke T; Freedman, Harold L

2012-07-01

Ganglion cysts are lesions resulting from the myxoid degeneration of the connective tissue associated with joint capsules and tendon sheaths. Most common around the wrist joint, ganglion cysts may be found elsewhere in the body, including in and around the knee joint. Uncommonly, ganglion cysts can present intramuscularly. Previous reports document the existence of intramuscular ganglia, often without histologic confirmation. This article describes a case of an intramuscular ganglion cyst in the medial gastrocnemius muscle of a 53-year-old woman. The patient initially presented for discomfort associated with the lesion. Examination was consistent with intramuscular cystic lesion of unknown etiology. Ultrasound and magnetic resonance imaging revealed the origin of the mass at the semimembranosus-gastrocnemius bursa. Because of its location, the mass was initially suspected to be a dissecting Baker's cyst, an uncommon but previously reported diagnosis. The patient underwent surgical excision, and examination of the intact specimen revealed a thin, fibrous, walled cyst with no lining epithelium, which was consistent with a ganglion cyst. To the authors' knowledge, this is the first report in the orthopedic literature of a ganglion cyst dissecting into the gastrocnemius muscle. Because ganglion cysts commonly require excision for definitive treatment and do not respond well to treatment measures implemented for Baker's cysts, including resection of underlying meniscal tears, the authors believe it is important for orthopedic surgeons to be able to distinguish between Baker's and other cysts associated with the knee joint, including ganglion cysts, which may require more definitive treatment. Copyright 2012, SLACK Incorporated.

Composition of Muscle Fiber Types in Rat Rotator Cuff Muscles.

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Rui, Yongjun; Pan, Feng; Mi, Jingyi

2016-10-01

The rat is a suitable model to study human rotator cuff pathology owing to the similarities in morphological anatomy structure. However, few studies have reported the composition muscle fiber types of rotator cuff muscles in the rat. In this study, the myosin heavy chain (MyHC) isoforms were stained by immunofluorescence to show the muscle fiber types composition and distribution in rotator cuff muscles of the rat. It was found that rotator cuff muscles in the rat were of mixed fiber type composition. The majority of rotator cuff fibers labeled positively for MyHCII. Moreover, the rat rotator cuff muscles contained hybrid fibers. So, compared with human rotator cuff muscles composed partly of slow-twitch fibers, the majority of fast-twitch fibers in rat rotator cuff muscles should be considered when the rat model study focus on the pathological process of rotator cuff muscles after injury. Gaining greater insight into muscle fiber types in rotator cuff muscles of the rat may contribute to elucidate the mechanism of pathological change in rotator cuff muscles-related diseases. Anat Rec, 299:1397-1401, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Mechanomyogram for identifying muscle activity and fatigue.

Science.gov (United States)

Yang, Zhao Feng; Kumar, Dinesh Kant; Arjunan, Sridhar Poosapadi

2009-01-01

Mechanomyogram is the recording of the acoustic activity associated with the muscle contraction. While discovered nearly a decade ago with the intention of providing an alternate to the surface electromyogram, it has not yet been investigated thoroughly and there are no current applications associated with MMG. This paper reports an experimental study of MMG against force of contraction and muscle fatigue during cyclic contraction. The results indicate that there is a relationship between the intensity of the MMG recording and force of contraction. A change in the intensity of MMG is also observed with the onset of muscle fatigue. However, the inter-subject variation is very large. The results also indicate that the spectrum of the MMG is very inconsistent and not a useful feature of the signal.

Selective activation of primary afferent fibers evaluated by sine-wave electrical stimulation

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Katafuchi Toshihiko

2005-03-01

Full Text Available Abstract Transcutaneous sine-wave stimuli at frequencies of 2000, 250 and 5 Hz (Neurometer are thought to selectively activate Aβ, Aδ and C afferent fibers, respectively. However, there are few reports to test the selectivity of these stimuli at the cellular level. In the present study, we analyzed action potentials (APs generated by sine-wave stimuli applied to the dorsal root in acutely isolated rat dorsal root ganglion (DRG preparations using intracellular recordings. We also measured excitatory synaptic responses evoked by transcutaneous stimuli in substantia gelatinosa (SG neurons of the spinal dorsal horn, which receive inputs predominantly from C and Aδ fibers, using in vivo patch-clamp recordings. In behavioral studies, escape or vocalization behavior of rats was observed with both 250 and 5 Hz stimuli at intensity of ~0.8 mA (T5/ T250, whereas with 2000 Hz stimulation, much higher intensity (2.14 mA, T2000 was required. In DRG neurons, APs were generated at T5/T250 by 2000 Hz stimulation in Aβ, by 250 Hz stimulation both in Aβ and Aδ, and by 5 Hz stimulation in all three classes of DRG neurons. However, the AP frequencies elicited in Aβ and Aδ by 5 Hz stimulation were much less than those reported previously in physiological condition. With in vivo experiments large amplitude of EPSCs in SG neurons were elicited by 250 and 5 Hz stimuli at T5/ T250. These results suggest that 2000 Hz stimulation excites selectively Aβ fibers and 5 Hz stimulation activates noxious transmission mediated mainly through C fibers. Although 250 Hz stimulation activates both Aδ and Aβ fibers, tactile sensation would not be perceived when painful sensation is produced at the same time. Therefore, 250 Hz was effective stimulus frequency for activation of Aδ fibers initiating noxious sensation. Thus, the transcutaneous sine-wave stimulation can be applied to evaluate functional changes of sensory transmission by comparing thresholds with the three

Protein and amino acid metabolism in skeletal muscle

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Wu, Guoyao.

1989-01-01

Isolated chick extensor digitorum communis (EDC) muscles and, in some experiments, rat skeletal muscles were used to study a number of aspects of protein and amino acid metabolism. (1) Chick EDC muscles synthesize and release large amounts of alanine and glutamine, which indirectly obtain their amino groups from branched-chain amino acids (BCAA). (2) Acetoacetate or DL-{beta}-hydroxybutyrate (4 mM) decrease (P < 0.01) alanine synthesis and BCAA transamination in EDC muscles from 24-h fasted chicks by decreasing (P < 0.01) intracellular concentrations of pyruvate due to inhibition of glycolysis. (3) Glutamine is extensively degraded in skeletal muscles from both chicks and rats, thus challenging the traditional view that glutamine oxidation is negligible in skeletal muscle. The cytosolic glutamine aminotransferases L and K in the rat and the mitochondrial phosphate-activated glutaminase in the chick play important roles in the conversion of glutamine to {alpha}-ketoglutarate for further oxidation. (4) Although methionine has been reported to be extensively transaminated in rat skeletal muscle preparations in the absence of other amino acids, transamination of methionine is absent or negligible in chick and rat skeletal muscles in the presence of physiological concentrations of amino acids. (5) Glutamine at 1.0-15 mM increases (P < 0.01) protein synthesis ({sup 3}H-phenylalanine incorporation), and at 10.0-15.0 mM decreases (P < 0.05) protein degradation ({sup 3}H-phenylalanine release from prelabelled protein in vivo) in EDC muscles from fed chicks as compared to muscles incubated in the absence of glutamine. (6) Acetoacetate or DL-{beta}-hydroxybutyrate (4 mM) has a small but significant inhibitory effect (P < 0.05) on the rate of protein synthesis, but has no effect (P > 0.05) on the rate of protein degradation in EDC muscles from fed chicks.

Stretching skeletal muscle: chronic muscle lengthening through sarcomerogenesis.

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Alexander M Zöllner

Full Text Available Skeletal muscle responds to passive overstretch through sarcomerogenesis, the creation and serial deposition of new sarcomere units. Sarcomerogenesis is critical to muscle function: It gradually re-positions the muscle back into its optimal operating regime. Animal models of immobilization, limb lengthening, and tendon transfer have provided significant insight into muscle adaptation in vivo. Yet, to date, there is no mathematical model that allows us to predict how skeletal muscle adapts to mechanical stretch in silico. Here we propose a novel mechanistic model for chronic longitudinal muscle growth in response to passive mechanical stretch. We characterize growth through a single scalar-valued internal variable, the serial sarcomere number. Sarcomerogenesis, the evolution of this variable, is driven by the elastic mechanical stretch. To analyze realistic three-dimensional muscle geometries, we embed our model into a nonlinear finite element framework. In a chronic limb lengthening study with a muscle stretch of 1.14, the model predicts an acute sarcomere lengthening from 3.09[Formula: see text]m to 3.51[Formula: see text]m, and a chronic gradual return to the initial sarcomere length within two weeks. Compared to the experiment, the acute model error was 0.00% by design of the model; the chronic model error was 2.13%, which lies within the rage of the experimental standard deviation. Our model explains, from a mechanistic point of view, why gradual multi-step muscle lengthening is less invasive than single-step lengthening. It also explains regional variations in sarcomere length, shorter close to and longer away from the muscle-tendon interface. Once calibrated with a richer data set, our model may help surgeons to prevent muscle overstretch and make informed decisions about optimal stretch increments, stretch timing, and stretch amplitudes. We anticipate our study to open new avenues in orthopedic and reconstructive surgery and enhance

Deltoid contracture: a case with multiple muscle contractures.

Science.gov (United States)

Chen, Hsin-Chang; Huang, Tung-Fu; Chou, Po-Hsin; Chen, Tain-Hsiung

2008-11-01

Deltoid contracture is relatively uncommon. The literature consists primarily of case reports and few articles on large case series. The pathogenesis has been well studied. Muscle contractures can occur in the deltoid, biceps, triceps, gluteus and quadriceps muscles; however, cases of multiple muscle contractures are rare. We reported a patient with multiple contractures of the bilateral deltoid, bilateral gluteus, and bilateral quadriceps muscles, who had received repeated intramuscular injections during childhood and adulthood. The radiographic, including magnetic resonance imaging (MRI), features of the bone and joint abnormalities are presented. Some literatures reported that damage to the structures of the body due to intramuscular injection is related to the site of injection, age of the patient, and the volume, pH, chemical composition, and diffusional capacity of the injectate. Our patient had muscular contracture induced by needle injection regardless of her age, medication and injection site.

Non-invasive assessment of muscle stiffness in patients with Duchenne muscular dystrophy.

Science.gov (United States)

Lacourpaille, Lilian; Hug, François; Guével, Arnaud; Péréon, Yann; Magot, Armelle; Hogrel, Jean-Yves; Nordez, Antoine

2015-02-01

Assessment of muscle mechanical properties may provide clinically valuable information for follow-up of patients with Duchenne muscular dystrophy (DMD) through the course of their disease. In this study we aimed to assess the effect of DMD on stiffness of relaxed muscles using elastography (supersonic shear imaging). Fourteen DMD patients and 13 control subjects were studied. Six muscles were measured at 2 muscle lengths (shortened and stretched): gastrocnemius medialis (GM); tibialis anterior (TA); vastus lateralis (VL); biceps brachii (BB); triceps brachii (TB); and abductor digiti minimi (ADM). Stiffness was significantly higher in DMD patients compared with controls for all the muscles (main effect for population, P muscle lengths) to large (d = 0.86 for BB/stretched). Supersonic shear imaging is a sensitive non-invasive technique to assess the increase in muscle stiffness associated with DMD. © 2014 Wiley Periodicals, Inc.

A Simplified Method for Tissue Engineering Skeletal Muscle Organoids in Vitro

Science.gov (United States)

Shansky, Janet; DelTatto, Michael; Chromiak, Joseph; Vandenburgh, Herman

1996-01-01

Tissue-engineered three dimensional skeletal muscle organ-like structures have been formed in vitro from primary myoblasts by several different techniques. This report describes a simplified method for generating large numbers of muscle organoids from either primary embryonic avian or neonatal rodent myoblasts, which avoids the requirements for stretching and other mechanical stimulation.

Muscle dysmorphia: current insights.

Science.gov (United States)

Tod, David; Edwards, Christian; Cranswick, Ieuan

2016-01-01

Since 1997, there has been increasing research focusing on muscle dysmorphia, a condition underpinned by people's beliefs that they have insufficient muscularity, in both the Western and non-Western medical and scientific communities. Much of this empirical interest has surveyed nonclinical samples, and there is limited understanding of people with the condition beyond knowledge about their characteristics. Much of the existing knowledge about people with the condition is unsurprising and inherent in the definition of the disorder, such as dissatisfaction with muscularity and adherence to muscle-building activities. Only recently have investigators started to explore questions beyond these limited tautological findings that may give rise to substantial knowledge advances, such as the examination of masculine and feminine norms. There is limited understanding of additional topics such as etiology, prevalence, nosology, prognosis, and treatment. Further, the evidence is largely based on a small number of unstandardized case reports and descriptive studies (involving small samples), which are largely confined to Western (North American, British, and Australian) males. Although much research has been undertaken since the term "muscle dysmorphia" entered the psychiatric lexicon in 1997, there remains tremendous scope for knowledge advancement. A primary task in the short term is for investigators to examine the extent to which the condition exists among well-defined populations to help determine the justification for research funding relative to other public health issues. A greater variety of research questions and designs may contribute to a broader and more robust knowledge base than currently exists. Future work will help clinicians assist a group of people whose quality of life and health are placed at risk by their muscular preoccupation.

Muscle Bioenergetic Considerations for Intrinsic Laryngeal Skeletal Muscle Physiology

Science.gov (United States)

Sandage, Mary J.; Smith, Audrey G.

2017-01-01

Purpose: Intrinsic laryngeal skeletal muscle bioenergetics, the means by which muscles produce fuel for muscle metabolism, is an understudied aspect of laryngeal physiology with direct implications for voice habilitation and rehabilitation. The purpose of this review is to describe bioenergetic pathways identified in limb skeletal muscle and…

The Management of Myofascial Pain Syndrome

African Journals Online (AJOL)

QuickSilver

pain syndrome (MFPS) was attributed to an inflammation of fibrous tissue ... Afferent nerve fibres to muscle are classified as groups I, II,. III and IV. .... tion of pain. There is evidence that pain caused by peripheral .... C. Occupational therapy.

Management of spastic hand by selective peripheral neurotomies

African Journals Online (AJOL)

Wael Fouad

2011-08-20

Aug 20, 2011 ... focalized on muscles that are under the control of a single or few peripheral nerves. Objective: This ... obtained by sectioning both afferents and efferents fibers of ... elbow, medial to the biceps brachii tendon; both median and.

Effects of protein supplements on muscle damage, soreness and recovery of muscle function and physical performance: a systematic review.

Science.gov (United States)

Pasiakos, Stefan M; Lieberman, Harris R; McLellan, Tom M

2014-05-01

demonstrating ingestion of a protein supplement following a bout of exercise attenuates muscle soreness and/or lowers markers of muscle damage. However, beneficial effects such as reduced muscle soreness and markers of muscle damage become more evident when supplemental protein is consumed after daily training sessions. Furthermore, the data suggest potential ergogenic effects associated with protein supplementation are greatest if participants are in negative nitrogen and/or energy balance. Small sample numbers and lack of dietary control limited the effectiveness of several investigations. In addition, studies did not measure the effects of protein supplementation on direct indices of muscle damage such as myofibrillar disruption and various measures of protein signaling indicative of a change in rates of protein synthesis and degradation. As a result, the interpretation of the data was often limited. Overwhelmingly, studies have consistently demonstrated the acute benefits of protein supplementation on post-exercise muscle anabolism, which, in theory, may facilitate the recovery of muscle function and performance. However, to date, when protein supplements are provided, acute changes in post-exercise protein synthesis and anabolic intracellular signaling have not resulted in measureable reductions in muscle damage and enhanced recovery of muscle function. Limitations in study designs together with the large variability in surrogate markers of muscle damage reduced the strength of the evidence-base.

The muscle CT of thigh in chronic Werdnig-Hoffmann disease

International Nuclear Information System (INIS)

Horikawa, Hirosei; Konagaya, Masaaki; Takayanagi, Tetsuya; Otsuji, Hideaki

1986-01-01

In this paper, the muscle CT of thigh in chronic Werdnig-Hoffmann disease (chronic WH) was evaluated. The subjects were five cases of chronic WH (3 males and 2 females, ages ranging from 6 to 22 years) and four control males. All cases showed symmetrical muscular weakness. The proximal muscle were more affected than the distal in the upper limbs. But the muscle strength of hip adduction was relatively spared as compared with other strength of lower limbs. The CT scan was carried out at the upper quarter level between lesser trochanter and medial condyle of the femur. The muscle CT of cases aged 6 and 7 years showed the severely decreased cross-sectional area of muscle without significant decrease in density. The atrophic muscles were surrounded by a large amount of low density area. The hamstring muscles and the adductor muscles, especially adductor longus muscle (ALM), were less affected than the quadriceps femoris muscles. Spotty and moth-eaten low density areas were observed dominantly in the severely affected muscles. In the advanced cases, only ALM could be identified on the CT image. The other muscles were unable to be identified because of severe atrophy with extremely low density. These CT findings suggest the process of muscular wastings of chronic WH as follows; at first muscle fibers are atrophied due to denervation and sooner or later replaced with fat tissue. Moreover, the preservation of ALM suggests that loss of anterior horn cells does not always go on homogeneously. (author)

Optimizing the Distribution of Leg Muscles for Vertical Jumping.

Directory of Open Access Journals (Sweden)

Jeremy D Wong

Full Text Available A goal of biomechanics and motor control is to understand the design of the human musculoskeletal system. Here we investigated human functional morphology by making predictions about the muscle volume distribution that is optimal for a specific motor task. We examined a well-studied and relatively simple human movement, vertical jumping. We investigated how high a human could jump if muscle volume were optimized for jumping, and determined how the optimal parameters improve performance. We used a four-link inverted pendulum model of human vertical jumping actuated by Hill-type muscles, that well-approximates skilled human performance. We optimized muscle volume by allowing the cross-sectional area and muscle fiber optimum length to be changed for each muscle, while maintaining constant total muscle volume. We observed, perhaps surprisingly, that the reference model, based on human anthropometric data, is relatively good for vertical jumping; it achieves 90% of the jump height predicted by a model with muscles designed specifically for jumping. Alteration of cross-sectional areas-which determine the maximum force deliverable by the muscles-constitutes the majority of improvement to jump height. The optimal distribution results in large vastus, gastrocnemius and hamstrings muscles that deliver more work, while producing a kinematic pattern essentially identical to the reference model. Work output is increased by removing muscle from rectus femoris, which cannot do work on the skeleton given its moment arm at the hip and the joint excursions during push-off. The gluteus composes a disproportionate amount of muscle volume and jump height is improved by moving it to other muscles. This approach represents a way to test hypotheses about optimal human functional morphology. Future studies may extend this approach to address other morphological questions in ethological tasks such as locomotion, and feature other sets of parameters such as properties of

Recent applications of X-ray microanalysis in muscle pathology

International Nuclear Information System (INIS)

Wroblewski, R.; Edstrom, L.

1984-01-01

X-ray microanalysis of single muscle fibres visualized in the scanning- and scanning-transmission mode of electron microscopy has been applied to human muscle biopsies to quantify changes of intracellular elements in different muscle disorders. To detect elements representing diffusible ions, cryofixation and cryosectioning was performed and analyses were conducted on freeze-dried cryosections 6μm thick. Changes in the concentration of elements were found to differentiate certain muscular disorders. A large increase in sodium (Na) and chlorine (Cl), and a decrease in potassium (K) was typical of myotubular myopathy, while a moderate increase in Na and Cl was found in central core disease and nemaline myopathy

Effects of oblique muscle surgery on the rectus muscle pulley

International Nuclear Information System (INIS)

Okanobu, Hirotaka; Kono, Reika; Ohtsuki, Hiroshi

2011-01-01

The purpose of this study was to determine the position of rectus muscle pulleys in Japanese eyes and to evaluate the effect of oblique muscle surgery on rectus muscle pulleys. Quasi-coronal plane MRI was used to determine area centroids of the 4 rectus muscles. The area centroids of the rectus muscles were transformed to 2-dimensional coordinates to represent pulley positions. The effects of oblique muscle surgery on the rectus muscle pulley positions in the coronal plane were evaluated in 10 subjects with cyclovertical strabismus and, as a control, pulley locations in 7 normal Japanese subjects were calculated. The mean positions of the rectus muscle pulleys in the coronal plane did not significantly differ from previous reports on normal populations, including Caucasians. There were significant positional shifts of the individual horizontal and vertical rectus muscle pulleys in 3 (100%) patients with inferior oblique advancement, but not in eyes with inferior oblique recession and superior oblique tendon advancement surgery. The surgical cyclorotatory effect was significantly correlated with the change in the angle of inclination formed by the line connecting the vertical rectus muscles (p=0.0234), but weakly correlated with that of the horizontal rectus muscles. The most important factor that affects the pulley position is the amount of ocular torsion, not the difference in surgical procedure induced by oblique muscle surgery. (author)

Proprioceptive perturbations of stability during gait

NARCIS (Netherlands)

Duysens, J.; Beerepoot, V.P.; Veltink, Petrus H.; Weerdesteyn, V.; Smits-Engelsman, B.C.M.

2008-01-01

Through recent studies, the role of proprioceptors in reactions to perturbations during gait has been finally somewhat better understood. The input from spindle afferents has been investigated with tendon taps, vibration and other forms of muscle stretches, including some resembling natural

Mitochondrial function in human skeletal muscle following high-altitude exposure

DEFF Research Database (Denmark)

Jacobs, Robert A; Boushel, Robert; Wright-Paradis, Cynthia

2013-01-01

Studies regarding mitochondrial modifications in human skeletal muscle following acclimatization to high altitude are conflicting, and these inconsistencies may be due to the prevalence of representing mitochondrial function through static and isolated measurements of specific mitochondrial...... characteristics. The aim of this study, therefore, was to investigate mitochondrial function in response to high-altitude acclimatization through measurements of respiratory control in the vastus lateralis muscle. Skeletal muscle biopsies were obtained from 10 lowland natives prior to and again after a total of 9......-11 days of exposure to 4559 m. High-resolution respirometry was performed on the muscle samples to compare respiratory chain function and respiratory capacities. Respirometric analysis revealed that mitochondrial function was largely unaffected, because high-altitude exposure did not affect the capacity...

Muscle metaboreflex and autonomic regulation of heart rate in humans

DEFF Research Database (Denmark)

Fisher, James P; Adlan, Ahmed M; Shantsila, Alena

2013-01-01

) conditions, but attenuated with β-adrenergic blockade (0.2 ± 1 beats min(-1); P > 0.05 vs. rest). Thus muscle metaboreflex activation-mediated increases in HR are principally attributable to increased cardiac sympathetic activity, and only following exercise with a large muscle mass (PEI following leg......We elucidated the autonomic mechanisms whereby heart rate (HR) is regulated by the muscle metaboreflex. Eight male participants (22 ± 3 years) performed three exercise protocols: (1) enhanced metaboreflex activation with partial flow restriction (bi-lateral thigh cuff inflation) during leg cycling...... exercise, (2) isolated muscle metaboreflex activation (post-exercise ischaemia; PEI) following leg cycling exercise, (3) isometric handgrip followed by PEI. Trials were undertaken under control (no drug), β1-adrenergic blockade (metoprolol) and parasympathetic blockade (glycopyrrolate) conditions. HR...

Semimembranosus muscle herniation: a rare case with emphasis on muscle biomechanics

Energy Technology Data Exchange (ETDEWEB)

Naffaa, Lena [American University of Beirut, Department of Diagnostic Radiology, P.O. Box 11-0236, Riad El-Solh, Beirut (Lebanon); Moukaddam, Hicham [Saint Rita Medical Center, Lima, OH (United States); Samim, Mohammad [New York University, Department of Radiology, Hospital for Joint Disease, New York, NY (United States); Lemieux, Aaron [University of California, San Diego School of Medicine, La Jolla, CA (United States); Smitaman, Edward [University of California, San Diego, Teleradiology and Education Center, San Diego, CA (United States)

2017-03-15

Muscle herniations are rare and most reported cases involve muscles of the lower leg. We use a case of muscle herniation involving the semimembranosus muscle, presenting as a painful mass in an adolescent male after an unspecified American football injury, to highlight a simple concept of muscle biomechanics as it pertains to muscle hernia(s): decreased traction upon muscle fibers can increase conspicuity of muscle herniation(s) - this allows a better understanding of the apt provocative maneuvers to employ, during dynamic ultrasound or magnetic resonance imaging, in order to maximize diagnostic yield and, thereby, limit patient morbidity related to any muscle herniation. Our patient subsequently underwent successful decompressive fasciotomy and has since returned to his normal daily activities. (orig.)

Semimembranosus muscle herniation: a rare case with emphasis on muscle biomechanics

International Nuclear Information System (INIS)

Naffaa, Lena; Moukaddam, Hicham; Samim, Mohammad; Lemieux, Aaron; Smitaman, Edward

2017-01-01

Muscle herniations are rare and most reported cases involve muscles of the lower leg. We use a case of muscle herniation involving the semimembranosus muscle, presenting as a painful mass in an adolescent male after an unspecified American football injury, to highlight a simple concept of muscle biomechanics as it pertains to muscle hernia(s): decreased traction upon muscle fibers can increase conspicuity of muscle herniation(s) - this allows a better understanding of the apt provocative maneuvers to employ, during dynamic ultrasound or magnetic resonance imaging, in order to maximize diagnostic yield and, thereby, limit patient morbidity related to any muscle herniation. Our patient subsequently underwent successful decompressive fasciotomy and has since returned to his normal daily activities. (orig.)

Neurophysiological changes in the afferent somatosensory system indices in the case of vertebrogenic spine pathology in miners

Directory of Open Access Journals (Sweden)

Sharbanu Battakova

2013-04-01

Full Text Available Objectives: The aim of the paper was to prove that job conditions impact the state of the afferent part of the somatosensory system in miners. Materials and Methods: Data analysis of the electrophysiological examination of the syndrome in 148 patients, aged from 28 to 55 years, with a mild, moderate and severe degree of the pain syndrome was performed. The control group included 28 people without any pain symptoms. The method used was that of somatosensory stimulated potential (SSP with the potentials amplitude and latency main components taken into consideration. Results: It was proven that the true decrease of the somatosensory stimulated potential SSP N22 (p < 0.05 component amplitudes by 41%; N30 component amplitude tend to decrease by 26%. This proves that the true N22 (p < 0.01 component latency increase by 63.8% corresponds to afferent excitation wave conductibility under the pain syndrome of vertebral pathology through sensitivity pathways mainly in the posterior spinal cord columns and then, through the parts of the brain stem, involving the cerebral cortex, which is confirmed by the fact that the P38 and P46 components amplitudes tend to decrease. In addition to this, the proven N10–N13 (p < 0.05, N13–N20 (p < 0.05, N10–N20 (p < 0.05 intervals increases by 43.5–41.8–38.7%, respectively, correspond to the nervous impulse conductibility through the peripheral nervous system structures and allow to reveal the subclinical slowdown of impulse conductibility, which indicates that the conducting system is changed even under a mild pain syndrome. Conclusions: It was found that the data obtained allow for the better understanding of how the neuropathological pain syndrome under vertebral spine pathology is formed.

Performance in the heat

DEFF Research Database (Denmark)

Nybo, Lars; Rasmussen, Peter; Sawka, Michael N.

2014-01-01

by neurotransmitter activity of the dopaminergic system, but inhibitory signals from thermoreceptors arising secondary to the elevated core, muscle and skin temperatures and augmented afferent feedback from the increased ventilation and the cardiovascular stressing (perhaps baroreceptor sensing of blood pressure...... thermoregulation and oxygen delivery to the active skeletal muscle. In contrast, during submaximal intensity exercise at a fixed intensity, muscle blood flow and oxygen consumption remain unchanged and the potential influence from cardiovascular stressing and/or high skin temperature is not related to decreased...

Determining the sub-cellular localization of proteins within Caenorhabditis elegans body wall muscle.

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Meissner, Barbara; Rogalski, Teresa; Viveiros, Ryan; Warner, Adam; Plastino, Lorena; Lorch, Adam; Granger, Laure; Segalat, Laurent; Moerman, Donald G

2011-01-01

Determining the sub-cellular localization of a protein within a cell is often an essential step towards understanding its function. In Caenorhabditis elegans, the relatively large size of the body wall muscle cells and the exquisite organization of their sarcomeres offer an opportunity to identify the precise position of proteins within cell substructures. Our goal in this study is to generate a comprehensive "localizome" for C. elegans body wall muscle by GFP-tagging proteins expressed in muscle and determining their location within the cell. For this project, we focused on proteins that we know are expressed in muscle and are orthologs or at least homologs of human proteins. To date we have analyzed the expression of about 227 GFP-tagged proteins that show localized expression in the body wall muscle of this nematode (e.g. dense bodies, M-lines, myofilaments, mitochondria, cell membrane, nucleus or nucleolus). For most proteins analyzed in this study no prior data on sub-cellular localization was available. In addition to discrete sub-cellular localization we observe overlapping patterns of localization including the presence of a protein in the dense body and the nucleus, or the dense body and the M-lines. In total we discern more than 14 sub-cellular localization patterns within nematode body wall muscle. The localization of this large set of proteins within a muscle cell will serve as an invaluable resource in our investigation of muscle sarcomere assembly and function.

Muscle Contraction.

Science.gov (United States)

Sweeney, H Lee; Hammers, David W

2018-02-01

SUMMARYMuscle cells are designed to generate force and movement. There are three types of mammalian muscles-skeletal, cardiac, and smooth. Skeletal muscles are attached to bones and move them relative to each other. Cardiac muscle comprises the heart, which pumps blood through the vasculature. Skeletal and cardiac muscles are known as striated muscles, because the filaments of actin and myosin that power their contraction are organized into repeating arrays, called sarcomeres, that have a striated microscopic appearance. Smooth muscle does not contain sarcomeres but uses the contraction of filaments of actin and myosin to constrict blood vessels and move the contents of hollow organs in the body. Here, we review the principal molecular organization of the three types of muscle and their contractile regulation through signaling mechanisms and discuss their major structural and functional similarities that hint at the possible evolutionary relationships between the cell types. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

The role of muscle spindles in constraining motor control

DEFF Research Database (Denmark)

Nielsen, Bjørn Gilbert

2002-01-01

support to the idea that gamma-motoneuron activity might be essential for cancelling expected stimuli rather than only for programming servo-controlled equilibrium positions of the limbs. It is concluded that the best performance of a movement is obtained when expected afference is cancelled by gamma...

Optimizing the Distribution of Leg Muscles for Vertical Jumping

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