In vivo calcium imaging from dentate granule cells with wide-field fluorescence microscopy.

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Yuichiro Hayashi

Full Text Available A combination of genetically-encoded calcium indicators and micro-optics has enabled monitoring of large-scale dynamics of neuronal activity from behaving animals. In these studies, wide-field microscopy is often used to visualize neural activity. However, this method lacks optical sectioning capability, and therefore its axial resolution is generally poor. At present, it is unclear whether wide-field microscopy can visualize activity of densely packed small neurons at cellular resolution. To examine the applicability of wide-field microscopy for small-sized neurons, we recorded calcium activity of dentate granule cells having a small soma diameter of approximately 10 micrometers. Using a combination of high numerical aperture (0.8 objective lens and independent component analysis-based image segmentation technique, activity of putative single granule cell activity was separated from wide-field calcium imaging data. The result encourages wider application of wide-field microscopy in in vivo neurophysiology.

Electrophysiological characterization of granule cells in the dentate gyrus immediately after birth

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Andrea ePedroni

2014-02-01

Full Text Available Granule cells (GCs in the dentate gyrus are generated mainly postnatally. Between embryonic day 10 and 14, neural precursors migrate from the primary dentate matrix to the dentate gyrus where they differentiate into neurons. Neurogenesis reaches a peak at the end of the first postnatal week and it is completed at the end of the first postnatal month. This process continues at a reduced rate throughout life. Interestingly, immediately after birth, GCs exhibit a clear GABAergic phenotype. Only later they integrate the classical glutamatergic trisynaptic hippocampal circuit. Here, whole patch clamp recordings, in current clamp mode, were performed from immature GCs, intracellularly loaded with biocytin (in hippocampal slices from P0-P3 old rats in order to compare their morphological characteristics with their electrophysiological properties. The vast majority of GCs were very immature with small somata, few dendritic branches terminating with small varicosities and growth cones. In spite of their immaturity their axons reached often the CA3 area. Immature GCs generated, upon membrane depolarization, either rudimentary sodium spikes or more clear overshooting action potentials that fired repetitively. They exhibited also low threshold calcium spikes. In addition, most spiking neurons showed spontaneous synchronized network activity, reminiscent of giant depolarizing potentials (GDPs generated in the hippocampus by the synergistic action of glutamate and GABA, both depolarizing and excitatory. This early synchronized activity, absent during adult neurogenesis, may play a crucial role in the refinement of local neuronal circuits within the developing dentate gyrus.

Local and Long-Range Circuit Connections to Hilar Mossy Cells in the Dentate Gyrus

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Sun, Yanjun; Grieco, Steven F.; Holmes, Todd C.

2017-01-01

Abstract Hilar mossy cells are the prominent glutamatergic cell type in the dentate hilus of the dentate gyrus (DG); they have been proposed to have critical roles in the DG network. To better understand how mossy cells contribute to DG function, we have applied new viral genetic and functional circuit mapping approaches to quantitatively map and compare local and long-range circuit connections of mossy cells and dentate granule cells in the mouse. The great majority of inputs to mossy cells consist of two parallel inputs from within the DG: an excitatory input pathway from dentate granule cells and an inhibitory input pathway from local DG inhibitory neurons. Mossy cells also receive a moderate degree of excitatory and inhibitory CA3 input from proximal CA3 subfields. Long range inputs to mossy cells are numerically sparse, and they are only identified readily from the medial septum and the septofimbrial nucleus. In comparison, dentate granule cells receive most of their inputs from the entorhinal cortex. The granule cells receive significant synaptic inputs from the hilus and the medial septum, and they also receive direct inputs from both distal and proximal CA3 subfields, which has been underdescribed in the existing literature. Our slice-based physiological mapping studies further supported the identified circuit connections of mossy cells and granule cells. Together, our data suggest that hilar mossy cells are major local circuit integrators and they exert modulation of the activity of dentate granule cells as well as the CA3 region through “back-projection” pathways. PMID:28451637

The GABAA Antagonist DPP-4-PIOL Selectively Antagonises Tonic over Phasic GABAergic Currents in Dentate Gyrus Granule Cells

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Boddum, Kim; Frølund, Bente; Kristiansen, Uffe

2014-01-01

that phasic and tonic GABAA receptor currents can be selectively inhibited by the antagonists SR 95531 and the 4-PIOL derivative, 4-(3,3-diphenylpropyl)-5-(4-piperidyl)-3-isoxazolol hydrobromide (DPP-4-PIOL), respectively. In dentate gyrus granule cells, SR 95531 was found approximately 4 times as potent...

The granule cell density of the dentate gyrus following administration of Urtica dioica extract to young diabetic rats.

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Fazeli, S A; Gharravi, A M; Ghafari, S; Jahanshahi, M; Golalipour, M J

2008-08-01

Urtica dioica L. Stinging nettle has long been known worldwide as a medicinal plant. To study the benefits of the nettle in diabetic encephalopathy, the granule cell density of the dentate gyrus of diabetic rats was studied following administration of Urtica dioica extract. A total of 24 male albino Wistar rats were allocated equally to normal, diabetic, preventive and treatment groups. Hyperglycaemia was induced by streptozotocin (80 mg/kg) in the animals of the diabetic and treatment groups. One week after injection of the streptozotocin the animals in the treatment group received a hydroalcoholic extract of Urtica dioica (100 mg/kg/day) for 4 weeks intraperitoneally. The rats of the preventive group received hydroalcoholic extract of U. dioica (100 mg/kg/day) IP for the first 5 days and an injection of streptozotocin (80 mg/kg) on the 6th day. After 5 weeks of study all the rats were sacrificed and coronal sections were taken from the dorsal hippocampal formation of the right cerebral hemispheres and stained with cresyl violet. The area densities of the granule cells were measured and compared in the four groups. The density was lower in the diabetic rats compared with the controls (p > 0.05). The preventive group showed lower cell density than the controls (p > 0.05). The densities in the treated rats were higher than in the diabetic rats (p > 0.05). Furthermore, the control and treated rats showed similar densities (p > 0.05). It seems that U. dioica extract can help compensate for granule cell loss in the diabetic rat dentate gyrus, which can ameliorate cognitive impairment in diabetes. However, preventive use of the extract showed no significant benefit.

Hilar mossy cells of the dentate gyrus: a historical perspective

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Helen E Scharfman

2013-01-01

Full Text Available The circuitry of the dentate gyrus of the hippocampus is unique compared to other hippocampal subfields because there are two glutamatergic principal cells instead of one: granule cells, which are the vast majority of the cells in the dentate gyrus, and the so-called ‘mossy cells.’ The distinctive appearance of mossy cells, the extensive divergence of their axons, and their vulnerability to excitotoxicity relative to granule cells has led to a great deal of interest in mossy cells. Nevertheless, there is no consensus about the normal functions of mossy cells and the implications of their vulnerability. There even seems to be some ambiguity about exactly what mossy cells are. Here we review initial studies of mossy cells, characteristics that define them, and suggest a practical definition to allow investigators to distinguish mossy cells from other hilar neurons even if all morphological and physiological information is unavailable due to technical limitations of their experiments. In addition, hypotheses are discussed about the role of mossy cells in the dentate gyrus network, reasons for their vulnerability and their implications for disease.

Conserved properties of dentate gyrus neurogenesis across postnatal development revealed by single-cell RNA sequencing.

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Hochgerner, Hannah; Zeisel, Amit; Lönnerberg, Peter; Linnarsson, Sten

2018-02-01

The dentate gyrus of the hippocampus is a brain region in which neurogenesis persists into adulthood; however, the relationship between developmental and adult dentate gyrus neurogenesis has not been examined in detail. Here we used single-cell RNA sequencing to reveal the molecular dynamics and diversity of dentate gyrus cell types in perinatal, juvenile, and adult mice. We found distinct quiescent and proliferating progenitor cell types, linked by transient intermediate states to neuroblast stages and fully mature granule cells. We observed shifts in the molecular identity of quiescent and proliferating radial glia and granule cells during the postnatal period that were then maintained through adult stages. In contrast, intermediate progenitor cells, neuroblasts, and immature granule cells were nearly indistinguishable at all ages. These findings demonstrate the fundamental similarity of postnatal and adult neurogenesis in the hippocampus and pinpoint the early postnatal transformation of radial glia from embryonic progenitors to adult quiescent stem cells.

Pyramid-like basket cells in the granular layer of the dentate gyrus in the rat.

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Seress, L

1978-01-01

Basket cells of the dentate gyrus were identified using Nissl (cresyl violet) staining. It has been found that the ratio between basket and granule cells is 1:150--210. Only a few glial cells, mainly astroglia, were found in the granular layer of the dentate gyrus. In accordance with earlier data it was found that the granule cells and glial cells originate mainly postnatally, but the basket cells, like the pyramidal cells of the hippocampus, originate prenatally. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:701192

The dentate mossy fibers

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Blaabjerg, Morten; Zimmer, Jens

2007-01-01

Hippocampal mossy fibers are the axons of the dentate granule cells and project to hippocampal CA3 pyramidal cells and mossy cells of the dentate hilus (CA4) as well as a number of interneurons in the two areas. Besides their role in hippocampal function, studies of which are still evolving...

Reduction of the immunostainable length of the hippocampal dentate granule cells' primary cilia in 3xAD-transgenic mice producing human A{beta}{sub 1-42} and tau

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Chakravarthy, Balu, E-mail: Balu.Chakravarthy@nrc-cnrc.gc.ca [Human Health Therapeutics, National Research Council of Canada, Ottawa, ON (Canada); Gaudet, Chantal; Menard, Michel; Brown, Leslie; Atkinson, Trevor [Human Health Therapeutics, National Research Council of Canada, Ottawa, ON (Canada); LaFerla, Frank M. [Department of Neurobiology and Behavior, University of California, Irvine, CA (United States); Ito, Shingo [Human Health Therapeutics, National Research Council of Canada, Ottawa, ON (Canada); Armato, Ubaldo; Dal Pra, Ilaria [Department of Life and Reproduction Sciences, University of Verona Medical School, Verona (Italy); Whitfield, James [Human Health Therapeutics, National Research Council of Canada, Ottawa, ON (Canada)

2012-10-12

Highlights: Black-Right-Pointing-Pointer A{beta} and tau-induced neurofibrillary tangles play a key role in Alzheimer's disease. Black-Right-Pointing-Pointer A{beta}{sub 1-42} and mutant tau protein together reduce the primary cilium length. Black-Right-Pointing-Pointer This shortening likely reduces cilium-dependent neurogenesis and memory function. Black-Right-Pointing-Pointer This provides a model of an A{beta}/tau targeting of a neuronal signaling organelle. -- Abstract: The hippocampal dentate gyrus is one of the two sites of continuous neurogenesis in adult rodents and humans. Virtually all dentate granule cells have a single immobile cilium with a microtubule spine or axoneme covered with a specialized cell membrane loaded with receptors such as the somatostatin receptor 3 (SSTR3), and the p75 neurotrophin receptor (p75{sup NTR}). The signals from these receptors have been reported to stimulate neuroprogenitor proliferation and the post-mitotic maturation of newborn granule cells into functioning granule cells. We have found that in 6-24-months-old triple transgenic Alzheimer's disease model mice (3xTg-AD) producing both A{beta}{sub 1-42} and the mutant human tau protein tau{sub P301L,} the dentate granule cells still had immunostainable SSTR3- and p75{sup NTR}-bearing cilia but they were only half the length of the immunostained cilia in the corresponding wild-type mice. However, the immunostainable length of the granule cell cilia was not reduced either in 2xTg-AD mice accumulating large amounts of A{beta}{sub 1-42} or in mice accumulating only a mutant human tau protein. Thus it appears that a combination of A{beta}{sub 1-42} and tau protein accumulation affects the levels of functionally important receptors in 3xTg-AD mice. These observations raise the important possibility that structural and functional changes in granule cell cilia might have a role in AD.

Migration and distribution of two populations of hippocampal granule cell precursors during the perinatal and postnatal periods

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Altman, J.; Bayer, S.A.

1990-01-01

Methacrylate-embedded sections and short-survival thymidine radiograms of the hippocampal dentate gyrus were examined in perinatal and postnatal rats in order to trace the site of origin and migration of the precursors of granule cells and study the morphogenesis of the granular layer. The densely packed, spindle-shaped cells of the secondary dentate matrix (a derivative of the primary dentate neuroepithelium) stream in a subpial position towards the granular layer of the internal dentate limb during the perinatal and early postnatal periods. By an accretionary process, the crest of the granular layer forms on day E21 and on the subsequent days the granular layer of the internal dentate limb expands progressively in a lateral direction. Granule cells differentiation, as judged by the transformation of polymorph, darkly staining small cells into rounder, lightly staining larger granule cells, follows the same gradient from the external dentate limb to the internal dentate limb. The secondary dentate matrix is in a process of dissolution by day P5. This matrix is the source of what will later become the outer shell of the granular layer composed of early generated granule cells. The thicker inner shell of the granular layer, formed during the infantile and juvenile periods, derives from an intrinsic, tertiary germinal matrix. On day E22, the dentate migration of the secondary dentate matrix becomes partitioned into two components: (a) the subpial component of extradentate origin, referred to in this context as the first dentate migration, and (b) the second dentate migration. The latter is distributed in the basal polymorph layer throughout the entire dentate gyrus and is henceforth recognized as the tertiary dentate matrix. The tertiary dentate matrix is prominent between days P3 and P10

Early natural stimulation through environmental enrichment accelerates neuronal development in the mouse dentate gyrus.

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Na Liu

Full Text Available The dentate gyrus is the primary afferent into the hippocampal formation, with important functions in learning and memory. Granule cells, the principle neuronal type in the dentate gyrus, are mostly formed postnatally, in a process that continues into adulthood. External stimuli, including environmental enrichment, voluntary exercise and learning, have been shown to significantly accelerate the generation and maturation of dentate granule cells in adult rodents. Whether, and to what extent, such environmental stimuli regulate the development and maturation of dentate granule cells during early postnatal development is largely unknown. Furthermore, whether natural stimuli affect the synaptic properties of granule cells had been investigated neither in newborn neurons of the adult nor during early development. To examine the effect of natural sensory stimulation on the dentate gyrus, we reared newborn mice in an enriched environment (EE. Using immunohistochemistry, we showed that dentate granule cells from EE-reared mice exhibited earlier morphological maturation, manifested as faster peaking of doublecortin expression and elevated expression of mature neuronal markers (including NeuN, calbindin and MAP2 at the end of the second postnatal week. Also at the end of the second postnatal week, we found increased density of dendritic spines across the entire dentate gyrus, together with elevated levels of postsynaptic scaffold (post-synaptic density 95 and receptor proteins (GluR2 and GABA(ARγ2 of excitatory and inhibitory synapses. Furthermore, dentate granule cells of P14 EE-reared mice had lower input resistances and increased glutamatergic and GABAergic synaptic inputs. Together, our results demonstrate that EE-rearing promotes morphological and electrophysiological maturation of dentate granule cells, underscoring the importance of natural environmental stimulation on development of the dentate gyrus.

Preventing effect of L-type calcium channel blockade on electrophysiological alterations in dentate gyrus granule cells induced by entorhinal amyloid pathology.

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Hamid Gholami Pourbadie

Full Text Available The entorhinal cortex (EC is one of the earliest affected brain regions in Alzheimer's disease (AD. EC-amyloid pathology induces synaptic failure in the dentate gyrus (DG with resultant behavioral impairment, but there is little known about its impact on neuronal properties in the DG. It is believed that calcium dyshomeostasis plays a pivotal role in the etiology of AD. Here, the effect of the EC amyloid pathogenesis on cellular properties of DG granule cells and also possible neuroprotective role of L-type calcium channel blockers (CCBs, nimodipine and isradipine, were investigated. The amyloid beta (Aβ 1-42 was injected bilaterally into the EC of male rats and one week later, electrophysiological properties of DG granule cells were assessed. Voltage clamp recording revealed appearance of giant sIPSC in combination with a decrease in sEPSC frequency which was partially reversed by CCBs in granule cells from Aβ treated rats. EC amyloid pathogenesis induced a significant reduction of input resistance (Rin accompanied by a profound decreased excitability in the DG granule cells. However, daily administration of CCBs, isradipine or nimodipine (i.c.v. for 6 days, almost preserved the normal excitability against Aβ. In conclusion, lower tendency to fire AP along with reduced Rin suggest that DG granule cells might undergo an alteration in the membrane ion channel activities which finally lead to the behavioral deficits observed in animal models and patients with early-stage Alzheimer's disease.

Early effects of trimethyltin on the dentate gyrus basket cells: a morphological study

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Chang, L.W.; Dyer, R.S.

1985-01-01

Electrophysiological evidence for reduction of recurrent inhibition in the dentate gyrus in animals exposed to trimethyltin (TMT) suggested alterations in the inhibitory neurons (basket cells) by TMT. The present study was designed to investigate the morphology of basket cells after TMT exposure. Long-Evans hooded rats were injected with TMT chloride in a dose of 6.0 mg/kg body weight (b.w.). Tissue samples from the dentate gyri were examined by both light and electron microscopy at 24 and 72 h after TMT exposure. Except for isolated basket cell damage at 72 h, no remarkable pathological changes were observed with light microscopy. Consistent with previous data, electron microscopy revealed that the basket cells of the dentate gyrus are large neurons situated just below the granule cell layer with characteristic large, infolded nuclei and intranuclear filamentous rods. Increased cytoplasmic density and degenerative changes of the Golgi complex were evident in the basket cells as early as 24 h after TMT exposure. By 72 h, neuronal vacuolation, accumulation of lysosomes, and occasional neuronal necrosis were observed. No significant pathological changes were found among the granule cells at this time. This report provides the first morphological evidence for early damage to the basket cells by TMT, which may account for the reduction of recurrent inhibition and hyperexcitability among the granule cells reported previously.

Intracellular Zn(2+) signaling in the dentate gyrus is required for object recognition memory.

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Takeda, Atsushi; Tamano, Haruna; Ogawa, Taisuke; Takada, Shunsuke; Nakamura, Masatoshi; Fujii, Hiroaki; Ando, Masaki

2014-11-01

The role of perforant pathway-dentate granule cell synapses in cognitive behavior was examined focusing on synaptic Zn(2+) signaling in the dentate gyrus. Object recognition memory was transiently impaired when extracellular Zn(2+) levels were decreased by injection of clioquinol and N,N,N',N'-tetrakis-(2-pyridylmethyl) ethylendediamine. To pursue the effect of the loss and/or blockade of Zn(2+) signaling in dentate granule cells, ZnAF-2DA (100 pmol, 0.1 mM/1 µl), an intracellular Zn(2+) chelator, was locally injected into the dentate molecular layer of rats. ZnAF-2DA injection, which was estimated to chelate intracellular Zn(2+) signaling only in the dentate gyrus, affected object recognition memory 1 h after training without affecting intracellular Ca(2+) signaling in the dentate molecular layer. In vivo dentate gyrus long-term potentiation (LTP) was affected under the local perfusion of the recording region (the dentate granule cell layer) with 0.1 mM ZnAF-2DA, but not with 1-10 mM CaEDTA, an extracellular Zn(2+) chelator, suggesting that the blockade of intracellular Zn(2+) signaling in dentate granule cells affects dentate gyrus LTP. The present study demonstrates that intracellular Zn(2+) signaling in the dentate gyrus is required for object recognition memory, probably via dentate gyrus LTP expression. Copyright © 2014 Wiley Periodicals, Inc.

Reduction of the immunostainable length of the hippocampal dentate granule cells’ primary cilia in 3xAD-transgenic mice producing human Aβ1-42 and tau

International Nuclear Information System (INIS)

Chakravarthy, Balu; Gaudet, Chantal; Ménard, Michel; Brown, Leslie; Atkinson, Trevor; LaFerla, Frank M.; Ito, Shingo; Armato, Ubaldo; Dal Prà, Ilaria; Whitfield, James

2012-01-01

Highlights: ► Aβ and tau-induced neurofibrillary tangles play a key role in Alzheimer’s disease. ► Aβ 1-42 and mutant tau protein together reduce the primary cilium length. ► This shortening likely reduces cilium-dependent neurogenesis and memory function. ► This provides a model of an Aβ/tau targeting of a neuronal signaling organelle. -- Abstract: The hippocampal dentate gyrus is one of the two sites of continuous neurogenesis in adult rodents and humans. Virtually all dentate granule cells have a single immobile cilium with a microtubule spine or axoneme covered with a specialized cell membrane loaded with receptors such as the somatostatin receptor 3 (SSTR3), and the p75 neurotrophin receptor (p75 NTR ). The signals from these receptors have been reported to stimulate neuroprogenitor proliferation and the post-mitotic maturation of newborn granule cells into functioning granule cells. We have found that in 6–24-months-old triple transgenic Alzheimer’s disease model mice (3xTg-AD) producing both Aβ 1-42 and the mutant human tau protein tau P301L, the dentate granule cells still had immunostainable SSTR3- and p75 NTR -bearing cilia but they were only half the length of the immunostained cilia in the corresponding wild-type mice. However, the immunostainable length of the granule cell cilia was not reduced either in 2xTg-AD mice accumulating large amounts of Aβ 1-42 or in mice accumulating only a mutant human tau protein. Thus it appears that a combination of Aβ 1-42 and tau protein accumulation affects the levels of functionally important receptors in 3xTg-AD mice. These observations raise the important possibility that structural and functional changes in granule cell cilia might have a role in AD.

Kindling-induced potentiation of excitatory and inhibitory inputs to hippocampal dentate granule cells. II. Effects of the NMDA antagonist MK-801.

LENUS (Irish Health Repository)

Robinson, G B

1991-10-18

The effect of the non-competitive N-methyl-D-aspartate antagonist MK-801 on the early development of kindling-induced potentiation was examined in the rabbit hippocampal dentate gyrus. MK-801 (0.5 mg\\/kg) was administered 2 h before each daily kindling stimulation was applied to the perforant path. This treatment continued for the first 10 days of kindling. MK-801 depressed the growth of the afterdischarge duration and suppressed development of behavioral seizures. MK-801 did not block kindling-induced potentiation of either the perforant path-dentate granule cell population spike or excitatory postsynaptic potential. Random impulse train stimulation and non-linear systems analytic techniques were used to examine kindling-induced potentiation of presumed GABAergic recurrent inhibitory circuits. Both the magnitude and duration of kindling-induced response inhibition, to the second of each pair of impulses within the train, were reduced in rabbits pretreated with MK-801. These results suggest that MK-801 differentially affects kindling-induced potentiation of excitatory and inhibitory circuits within the rabbit hippocampal dentate gyrus.

Dentate gyrus and hilus transection blocks seizure propagation and granule cell dispersion in a mouse model for mesial temporal lobe epilepsy.

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Pallud, Johan; Häussler, Ute; Langlois, Mélanie; Hamelin, Sophie; Devaux, Bertrand; Deransart, Colin; Depaulis, Antoine

2011-03-01

Epilepsy-associated changes of the anatomical organization of the dentate gyrus and hilus may play a critical role in the initiation and propagation of seizures in mesial temporal lobe epilepsy (MTLE). This study evaluated the role of longitudinal projections in the propagation of hippocampal paroxysmal discharges (HPD) in dorsal hippocampus by performing a selective transection in a mouse model for MTLE obtained by a single unilateral intrahippocampal injection of kainic acid (KA). Full transections of the dentate gyrus and hilus were performed in the transverse axis at 22 days after KA injection when spontaneous HPD were fully developed. They: (i) significantly reduced the occurrence of HPD; (ii) increased their duration at the KA injection site; (iii) abolished their spread along the longitudinal axis of the hippocampal formation and; (iv) limited granule cell dispersion (GCD) of the dentate gyrus posterior to the transection. These data suggest that: (i) longitudinal projections through the dentate gyrus and hilus are involved in HPD spread; (ii) distant hippocampal circuits participate in the generation and cessation of HPD and; (iii) GCD requires continuous HPD to develop, even when seizures are established. Our data reveal a critical role for longitudinal projections in the generation and spread of hippocampal seizures. Copyright © 2010 Wiley-Liss, Inc.

Chronic Fluoxetine Induces the Enlargement of Perforant Path-Granule Cell Synapses in the Mouse Dentate Gyrus

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Kitahara, Yosuke; Ohta, Keisuke; Hasuo, Hiroshi; Shuto, Takahide; Kuroiwa, Mahomi; Sotogaku, Naoki; Togo, Akinobu; Nakamura, Kei-ichiro; Nishi, Akinori

2016-01-01

A selective serotonin reuptake inhibitor is the most commonly prescribed antidepressant for the treatment of major depression. However, the mechanisms underlying the actions of selective serotonin reuptake inhibitors are not fully understood. In the dentate gyrus, chronic fluoxetine treatment induces increased excitability of mature granule cells (GCs) as well as neurogenesis. The major input to the dentate gyrus is the perforant path axons (boutons) from the entorhinal cortex (layer II). Through voltage-sensitive dye imaging, we found that the excitatory neurotransmission of the perforant path synapse onto the GCs in the middle molecular layer of the mouse dentate gyrus (perforant path-GC synapse) is enhanced after chronic fluoxetine treatment (15 mg/kg/day, 14 days). Therefore, we further examined whether chronic fluoxetine treatment affects the morphology of the perforant path-GC synapse, using FIB/SEM (focused ion beam/scanning electron microscopy). A three-dimensional reconstruction of dendritic spines revealed the appearance of extremely large-sized spines after chronic fluoxetine treatment. The large-sized spines had a postsynaptic density with a large volume. However, chronic fluoxetine treatment did not affect spine density. The presynaptic boutons that were in contact with the large-sized spines were large in volume, and the volumes of the mitochondria and synaptic vesicles inside the boutons were correlated with the size of the boutons. Thus, the large-sized perforant path-GC synapse induced by chronic fluoxetine treatment contains synaptic components that correlate with the synapse size and that may be involved in enhanced glutamatergic neurotransmission. PMID:26788851

Long-term potentiation in hilar circuitry modulates gating by the dentate gyrus.

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Wright, Brandon J; Jackson, Meyer B

2014-07-16

The dentate gyrus serves as a gateway to the hippocampus, filtering and processing sensory inputs as an animal explores its environment. The hilus occupies a strategic position within the dentate gyrus from which it can play a pivotal role in these functions. Inputs from dentate granule cells converge on the hilus, and excitatory hilar mossy cells redistribute these signals back to granule cells to transform a pattern of cortical input into a new pattern of output to the hippocampal CA3 region. Using voltage-sensitive dye to image electrical activity in rat hippocampal slices, we explored how long-term potentiation (LTP) of different excitatory synapses modifies the flow of information. Theta burst stimulation of the perforant path potentiated responses throughout the molecular layer, but left responses in the CA3 region unchanged. By contrast, theta burst stimulation of the granule cell layer potentiated responses throughout the molecular layer, as well as in the CA3 region. Theta burst stimulation of the granule cell layer potentiated CA3 responses not only to granule cell layer stimulation but also to perforant path stimulation. Potentiation of responses in the CA3 region reflected NMDA receptor-dependent LTP of upstream synapses between granule cells and mossy cells, with no detectable contribution from NMDA receptor-independent LTP of local CA3 mossy fiber synapses. Potentiation of transmission to the CA3 region required LTP in both granule cell→mossy cell and mossy cell→granule cell synapses. This bidirectional plasticity enables hilar circuitry to regulate the flow of information through the dentate gyrus and on to the hippocampus. Copyright © 2014 the authors 0270-6474/14/349743-11$15.00/0.

Neurotrophin and FGF Signaling Adapter Proteins, FRS2 and FRS3, Regulate Dentate Granule Cell Maturation and Excitatory Synaptogenesis.

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Nandi, Sayan; Alviña, Karina; Lituma, Pablo J; Castillo, Pablo E; Hébert, Jean M

2018-01-15

Dentate granule cells (DGCs) play important roles in cognitive processes. Knowledge about how growth factors such as FGFs and neurotrophins contribute to the maturation and synaptogenesis of DGCs is limited. Here, using brain-specific and germline mouse mutants we show that a module of neurotrophin and FGF signaling, the FGF Receptor Substrate (FRS) family of intracellular adapters, FRS2 and FRS3, are together required for postnatal brain development. In the hippocampus, FRS promotes dentate gyrus morphogenesis and DGC maturation during developmental neurogenesis, similar to previously published functions for both neurotrophins and FGFs. Consistent with a role in DGC maturation, two-photon imaging revealed that Frs2,3-double mutants have reduced numbers of dendritic branches and spines in DGCs. Functional analysis further showed that double-mutant mice exhibit fewer excitatory synaptic inputs onto DGCs. These observations reveal roles for FRS adapters in DGC maturation and synaptogenesis and suggest that FRS proteins may act as an important node for FGF and neurotrophin signaling in postnatal hippocampal development. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Characteristic of Extracellular Zn2+ Influx in the Middle-Aged Dentate Gyrus and Its Involvement in Attenuation of LTP.

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Takeda, Atsushi; Koike, Yuta; Osaw, Misa; Tamano, Haruna

2018-03-01

An increased influx of extracellular Zn 2+ into neurons is a cause of cognitive decline. The influx of extracellular Zn 2+ into dentate granule cells was compared between young and middle-aged rats because of vulnerability of the dentate gyrus to aging. The influx of extracellular Zn 2+ into dentate granule cells was increased in middle-aged rats after injection of AMPA and high K + into the dentate gyrus, but not in young rats. Simultaneously, high K + -induced attenuation of LTP was observed in middle-aged rats, but not in young rats. The attenuation was rescued by co-injection of CaEDTA, an extracellular Zn 2+ chelator. Intracellular Zn 2+ in dentate granule cells was also increased in middle-aged slices with high K + , in which the increase in extracellular Zn 2+ was the same as young slices with high K + , suggesting that ability of extracellular Zn 2+ influx into dentate granule cells is greater in middle-aged rats. Furthermore, extracellular zinc concentration in the hippocampus was increased age-dependently. The present study suggests that the influx of extracellular Zn 2+ into dentate granule cells is more readily increased in middle-aged rats and that its increase is a cause of age-related attenuation of LTP in the dentate gyrus.

Corruption of the dentate gyrus by "dominant" granule cells: Implications for dentate gyrus function in health and disease.

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Scharfman, Helen E; Myers, Catherine E

2016-03-01

The dentate gyrus (DG) and area CA3 of the hippocampus are highly organized lamellar structures which have been implicated in specific cognitive functions such as pattern separation and pattern completion. Here we describe how the anatomical organization and physiology of the DG and CA3 are consistent with structures that perform pattern separation and completion. We then raise a new idea related to the complex circuitry of the DG and CA3 where CA3 pyramidal cell 'backprojections' play a potentially important role in the sparse firing of granule cells (GCs), considered important in pattern separation. We also propose that GC axons, the mossy fibers, already known for their highly specialized structure, have a dynamic function that imparts variance--'mossy fiber variance'--which is important to pattern separation and completion. Computational modeling is used to show that when a subset of GCs become 'dominant,' one consequence is loss of variance in the activity of mossy fiber axons and a reduction in pattern separation and completion in the model. Empirical data are then provided using an example of 'dominant' GCs--subsets of GCs that develop abnormally and have increased excitability. Notably, these abnormal GCs have been identified in animal models of disease where DG-dependent behaviors are impaired. Together these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network. Copyright © 2015 Elsevier Inc. All rights reserved.

Semaphorin 5A inhibits synaptogenesis in early postnatal- and adult-born hippocampal dentate granule cells.

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Duan, Yuntao; Wang, Shih-Hsiu; Song, Juan; Mironova, Yevgeniya; Ming, Guo-li; Kolodkin, Alex L; Giger, Roman J

2014-10-14

Human SEMAPHORIN 5A (SEMA5A) is an autism susceptibility gene; however, its function in brain development is unknown. In this study, we show that mouse Sema5A negatively regulates synaptogenesis in early, developmentally born, hippocampal dentate granule cells (GCs). Sema5A is strongly expressed by GCs and regulates dendritic spine density in a cell-autonomous manner. In the adult mouse brain, newly born Sema5A-/- GCs show an increase in dendritic spine density and increased AMPA-type synaptic responses. Sema5A signals through PlexinA2 co-expressed by GCs, and the PlexinA2-RasGAP activity is necessary to suppress spinogenesis. Like Sema5A-/- mutants, PlexinA2-/- mice show an increase in GC glutamatergic synapses, and we show that Sema5A and PlexinA2 genetically interact with respect to GC spine phenotypes. Sema5A-/- mice display deficits in social interaction, a hallmark of autism-spectrum-disorders. These experiments identify novel intra-dendritic Sema5A/PlexinA2 interactions that inhibit excitatory synapse formation in developmentally born and adult-born GCs, and they provide support for SEMA5A contributions to autism-spectrum-disorders.

Behavioral experience induces zif268 expression in mature granule cells but suppresses its expression in immature granule cells

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Huckleberry, Kylie A.; Kane, Gary A.; Mathis, Rita J.; Cook, Sarah G.; Clutton, Jonathan E.; Drew, Michael R.

2015-01-01

Thousands of neurons are born each day in the dentate gyrus (DG), but many of these cells die before reaching maturity. Both death and survival of adult-born neurons are regulated by neuronal activity in the DG. The immediate-early gene (IEG) zif268 appears to be an important mediator of these effects, as its expression can be induced by neural activity and knockout of zif268 impairs survival of adult-born neurons (Richardson et al., 1992; Veyrac et al., 2013). Despite the apparent importance of zif268 for adult neurogenesis, its behavior-induced expression has not been fully characterized in adult-born neurons. Here we characterize behavior-evoked expression of zif268 in mature and newborn dentate granule cells (DGCs). We first quantified zif268 expression in doublecortin-positive (DCX+) immature neurons and in the general granule cell population after brief exposure to a novel environment (NE). In the general granule cell population, zif268 expression peaked 1 h after NE exposure and returned to baseline by 8 h post-exposure. However, in the DCX+ cells, zif268 expression was suppressed relative to home cage for at least 8 h post-exposure. We next asked whether suppression of zif268 in DCX+ immature cells occurs in other behavioral paradigms that recruit the hippocampus. Exposure to Morris water maze (MWM) training, an enriched environment, or a NE caused approximately equal suppression of zif268 expression in DCX+ cells and approximately equal activation of zif268 expression among the general granule cell population. The same behavioral procedures activated zif268 expression in 6-week-old BrdU-labeled adult-born neurons, indicating that zif268 suppression is specific to immature neurons. Finally, we asked whether zif268 suppression varied as a function of age within the DCX+ population, which ranges in age from 0 to approximately 4 weeks. NE exposure had no significant effect on zif268 expression in 2- or 4-week-old BrdU-labeled neurons, but it significantly

Factors specifying the development of synapse number in the rat dentate gyrus: effects of partial target loss

International Nuclear Information System (INIS)

Lewis, E.R.; Cotman, C.W.

1980-01-01

The development of the dentate gyrus has been studied under conditions of partial reduction of granule cell number. Neonatal rats were subjected to X-irradiation, a procedure which reduces the number of granule cells to 20% of control values. In X-irradiated rats, quantitative analyses were performed on cells in the entorhinal cortex which give rise to the perforant path projection to the dentate granule cells, and on the remaining, undamaged dentate granule cells. These residual cells were examined morphologically for possible hyperdevelopment in comparison to granule cells from control animals. Granule cells in X-irradiated animals were similar to granule cells in control animals with respect to dendritic structure and synaptic density. The number of neurons in both the medical and lateral entorhinal cortices in X-irradiated animals appeared normal until day 12, at which time a selective reduction in cell numbers became apparent. By day 30, 25-55% of the cells of origin of the perforant path were absent in X-irradiated animals. It is hypothesized that these cells are subject to retrograde transynaptic degeneration as a result of target removal. Further, it appears that granule cells play an important role in determining the density of their innervation. (Auth.)

Adult neurogenesis modifies excitability of the dentate gyrus

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Taruna eIkrar

2013-12-01

Full Text Available Adult-born dentate granule neurons contribute to memory encoding functions of the dentate gyrus (DG such as pattern separation. However, local circuit-mechanisms by which adult-born neurons partake in this process are poorly understood. Computational, neuroanatomical and electrophysiological studies suggest that sparseness of activation in the granule cell layer (GCL is conducive for pattern separation. A sparse coding scheme is thought to facilitate the distribution of similar entorhinal inputs across the GCL to decorrelate overlapping representations and minimize interference. Here we used fast voltage-sensitive dye (VSD imaging combined with laser photostimulation and electrical stimulation to examine how selectively increasing adult DG neurogenesis influences local circuit activity and excitability. We show that DG of mice with more adult-born neurons exhibits decreased strength of neuronal activation and more restricted excitation spread in GCL while maintaining effective output to CA3c. Conversely, blockade of adult hippocampal neurogenesis changed excitability of the DG in the opposite direction. Analysis of GABAergic inhibition onto mature dentate granule neurons in the DG of mice with more adult-born neurons shows a modest readjustment of perisomatic inhibitory synaptic gain without changes in overall inhibitory tone, presynaptic properties or GABAergic innervation pattern. Retroviral labeling of connectivity in mice with more adult-born neurons showed increased number of excitatory synaptic contacts of adult-born neurons onto hilar interneurons. Together, these studies demonstrate that adult hippocampal neurogenesis modifies excitability of mature dentate granule neurons and that this non-cell autonomous effect may be mediated by local circuit mechanisms such as excitatory drive onto hilar interneurons. Modulation of DG excitability by adult-born dentate granule neurons may enhance sparse coding in the GCL to influence pattern

BACE1 Deficiency Causes Abnormal Neuronal Clustering in the Dentate Gyrus

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Hailong Hou

2017-07-01

Full Text Available BACE1 is validated as Alzheimer's β-secretase and a therapeutic target for Alzheimer's disease. In examining BACE1-null mice, we discovered that BACE1 deficiency develops abnormal clusters of immature neurons, forming doublecortin-positive neuroblasts, in the developing dentate gyrus, mainly in the subpial zone (SPZ. Such clusters were rarely observed in wild-type SPZ and not reported in other mouse models. To understand their origins and fates, we examined how neuroblasts in BACE1-null SPZ mature and migrate during early postnatal development. We show that such neuroblasts are destined to form Prox1-positive granule cells in the dentate granule cell layer, and mainly mature to form excitatory neurons, but not inhibitory neurons. Mechanistically, higher levels of reelin potentially contribute to abnormal neurogenesis and timely migration in BACE1-null SPZ. Altogether, we demonstrate that BACE1 is a critical regulator in forming the dentate granule cell layer through timely maturation and migration of SPZ neuroblasts.

Mosaic organization of the hippocampal neuroepithelium and the multiple germinal sources of dentate granule cells

International Nuclear Information System (INIS)

Altman, J.; Bayer, S.A.

1990-01-01

This study deals with the site of origin, migration, and settling of the principal cell constituents of the rat hippocampus during the embryonic period. The results indicate that the hippocampal neuroepithelium consists of three morphogenetically discrete components--the Ammonic neuroepithelium, the primary dentate neuroepithelium, and the fimbrial glioepithelium--and that these are discrete sources of the large neurons of Ammon's horn, the smaller granular neurons of the dentate gyrus, and the glial cells of the fimbria. The putative Ammonic neuroepithelium is marked in short-survival thymidine radiograms by a high level of proliferative activity and evidence of interkinetic nuclear migration from day E16 until day E19. On days E16 and E17 a diffuse band of unlabeled cells forms outside the Ammonic neuroepithelium. These postmitotic cells are considered to be stratum radiatum and stratum oriens neurons, which are produced in large numbers as early as day E15. A cell-dense layer, the incipient stratum pyramidale, begins to form on day E18 and spindle-shaped cells can be traced to it from the Ammonic neuroepithelium. This migratory band increases in size for several days, then declines, and finally disappears by day E22. It is inferred that this migration contains the pyramidal cells of Ammon's horn that are produced mostly on days E17 through E20. The putative primary dentate neuroepithelium is distinguished from the Ammonic neuroepithelium during the early phases of embryonic development by its location, shape, and cellular dynamics. It is located around a ventricular indentation, the dentate notch, contains fewer mitotic cells near the lumen of the ventricle than the Ammonic neuroepithelium, and shows a different labeling pattern both in short-survival and sequential-survival thymidine radiograms

Reduced tonic inhibition in the dentate gyrus contributes to chronic stress-induced impairments in learning and memory.

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Lee, Vallent; MacKenzie, Georgina; Hooper, Andrew; Maguire, Jamie

2016-10-01

It is well established that stress impacts the underlying processes of learning and memory. The effects of stress on memory are thought to involve, at least in part, effects on the hippocampus, which is particularly vulnerable to stress. Chronic stress induces hippocampal alterations, including but not limited to dendritic atrophy and decreased neurogenesis, which are thought to contribute to chronic stress-induced hippocampal dysfunction and deficits in learning and memory. Changes in synaptic transmission, including changes in GABAergic inhibition, have been documented following chronic stress. Recently, our laboratory demonstrated shifts in EGABA in CA1 pyramidal neurons following chronic stress, compromising GABAergic transmission and increasing excitability of these neurons. Interestingly, here we demonstrate that these alterations are unique to CA1 pyramidal neurons, since we do not observe shifts in EGABA following chronic stress in dentate gyrus granule cells. Following chronic stress, there is a decrease in the expression of the GABAA receptor (GABAA R) δ subunit and tonic GABAergic inhibition in dentate gyrus granule cells, whereas there is an increase in the phasic component of GABAergic inhibition, evident by an increase in the peak amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). Given the numerous changes observed in the hippocampus following stress, it is difficult to pinpoint the pertinent contributing pathophysiological factors. Here we directly assess the impact of a reduction in tonic GABAergic inhibition of dentate gyrus granule cells on learning and memory using a mouse model with a decrease in GABAA R δ subunit expression specifically in dentate gyrus granule cells (Gabrd/Pomc mice). Reduced GABAA R δ subunit expression and function in dentate gyrus granule cells is sufficient to induce deficits in learning and memory. Collectively, these findings suggest that the reduction in GABAA R δ subunit-mediated tonic inhibition

Reduced tonic inhibition in the dentate gyrus contributes to chronic stress-induced impairments in learning and memory

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Hooper, Andrew; Maguire, Jamie

2016-01-01

It is well established that stress impacts the underlying processes of learning and memory. The effects of stress on memory are thought to involve, at least in part, effects on the hippocampus, which is particularly vulnerable to stress. Chronic stress induces hippocampal alterations, including but not limited to dendritic atrophy and decreased neurogenesis, which are thought to contribute to chronic stress-induced hippocampal dysfunction and deficits in learning and memory. Changes in synaptic transmission, including changes in GABAergic inhibition, have been documented following chronic stress. Recently, our laboratory demonstrated shifts in EGABA in CA1 pyramidal neurons following chronic stress, compromising GABAergic transmission and increasing excitability of these neurons. Interestingly, here we demonstrate that these alterations are unique to CA1 pyramidal neurons, since we do not observe shifts in EGABA following chronic stress in dentate gyrus granule cells. Following chronic stress, there is a decrease in the expression of the GABAA receptor (GABAAR) δ subunit and tonic GABAergic inhibition in dentate gyrus granule cells; whereas, there is an increase in the phasic component of GABAergic inhibition, evident by an increase in the peak amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). Given the numerous changes observed in the hippocampus following stress, it is difficult to pinpoint the pertinent contributing pathophysiological factors. Here we directly assess the impact of a reduction in tonic GABAergic inhibition of dentate gyrus granule cells on learning and memory using a mouse model with a decrease in GABAAR δ subunit expression specifically in dentate gyrus granule cells (Gabrd/Pomc mice). Reduced GABAAR δ subunit expression and function in dentate gyrus granule cells is sufficient to induce deficits in learning and memory. Collectively, these findings suggest that the reduction in GABAAR δ subunit-mediated tonic inhibition in

Denervation-induced homeostatic dendritic plasticity in morphological granule cell models

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Hermann Cuntz

2014-03-01

Full Text Available Neuronal death and subsequent denervation of target areas are major consequences of several neurological conditions such asischemia or neurodegeneration (Alzheimer's disease. The denervation-induced axonal loss results in reorganization of the dendritic tree of denervated neurons. The dendritic reorganization has been previously studied using entorhinal cortex lesion (ECL. ECL leads to shortening and loss of dendritic segments in the denervated outer molecular layer of the dentate gyrus. However, the functional importance of these long-term dendritic alterations is not yet understood and their impact on neuronal electrical properties remains unclear. Here we analyzed what happens to the electrotonic structure and excitability of dentate granule cells after lesion-induced alterations of their dendritic morphology, assuming all other parameters remain equal. We performed comparative electrotonic analysis in anatomically and biophysically realistic compartmental models of 3D-reconstructed healthy and denervated granule cells. Using the method of morphological modeling based on optimization principles minimizing the amount of wiring and maximizing synaptic democracy, we built artificial granule cells which replicate morphological features of their real counterparts. Our results show that somatofugal and somatopetal voltage attenuation in the passive cable model are strongly reduced in denervated granule cells. In line with these predictions, the attenuation both of simulated backpropagating action potentials and forward propagating EPSPs was significantly reduced in dendrites of denervated neurons. Intriguingly, the enhancement of action potential backpropagation occurred specifically in the denervated dendritic layers. Furthermore, simulations of synaptic f-I curves revealed a homeostatic increase of excitability in denervated granule cells. In summary, our morphological and compartmental modeling indicates that unless modified by changes of

Proteomic profiling of the epileptic dentate gyrus

OpenAIRE

Li, Aiqing; Choi, Yun-Sik; Dziema, Heather; Cao, Ruifeng; Cho, Hee-Yeon; Jung, Yeon Joo; Obrietan, Karl

2010-01-01

The development of epilepsy is often associated with marked changes in central nervous system cell structure and function. Along these lines, reactive gliosis and granule cell axonal sprouting within the dentate gyrus of the hippocampus are commonly observed in individuals with temporal lobe epilepsy. Here we used the pilocarpine model of temporal lobe epilepsy in mice to screen the proteome and phosphoproteome of the dentate gyrus to identify molecular events that are altered as part of the ...

Decreased surface expression of the δ subunit of the GABAA receptor contributes to reduced tonic inhibition in dentate granule cells in a mouse model of fragile X syndrome.

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Zhang, Nianhui; Peng, Zechun; Tong, Xiaoping; Lindemeyer, A Kerstin; Cetina, Yliana; Huang, Christine S; Olsen, Richard W; Otis, Thomas S; Houser, Carolyn R

2017-11-01

While numerous changes in the GABA system have been identified in models of Fragile X Syndrome (FXS), alterations in subunits of the GABA A receptors (GABA A Rs) that mediate tonic inhibition are particularly intriguing. Considering the key role of tonic inhibition in controlling neuronal excitability, reduced tonic inhibition could contribute to FXS-associated disorders such as hyperactivity, hypersensitivity, and increased seizure susceptibility. The current study has focused on the expression and function of the δ subunit of the GABA A R, a major subunit involved in tonic inhibition, in granule cells of the dentate gyrus in the Fmr1 knockout (KO) mouse model of FXS. Electrophysiological studies of dentate granule cells revealed a marked, nearly four-fold, decrease in tonic inhibition in the Fmr1 KO mice, as well as reduced effects of two δ subunit-preferring pharmacological agents, THIP and DS2, supporting the suggestion that δ subunit-containing GABA A Rs are compromised in the Fmr1 KO mice. Immunohistochemistry demonstrated a small but statistically significant decrease in δ subunit labeling in the molecular layer of the dentate gyrus in Fmr1 KO mice compared to wildtype (WT) littermates. The discrepancy between the large deficits in GABA-mediated tonic inhibition in granule cells in the Fmr1 KO mice and only modest reductions in immunolabeling of the δ subunit led to studies of surface expression of the δ subunit. Cross-linking experiments followed by Western blot analysis demonstrated a small, non-significant decrease in total δ subunit protein in the hippocampus of Fmr1 KO mice, but a four-fold decrease in surface expression of the δ subunit in these mice. No significant changes were observed in total or surface expression of the α4 subunit protein, a major partner of the δ subunit in the forebrain. Postembedding immunogold labeling for the δ subunit demonstrated a large, three-fold, decrease in the number of symmetric synapses with

Hilar mossy cells of the dentate gyrus: a historical perspective

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Scharfman, Helen E.; Myers, Catherine E.

2013-01-01

The circuitry of the dentate gyrus (DG) of the hippocampus is unique compared to other hippocampal subfields because there are two glutamatergic principal cells instead of one: granule cells, which are the vast majority of the cells in the DG, and the so-called “mossy cells.” The distinctive appearance of mossy cells, the extensive divergence of their axons, and their vulnerability to excitotoxicity relative to granule cells has led to a great deal of interest in mossy cells. Nevertheless, there is no consensus about the normal functions of mossy cells and the implications of their vulnerability. There even seems to be some ambiguity about exactly what mossy cells are. Here we review initial studies of mossy cells, characteristics that define them, and suggest a practical definition to allow investigators to distinguish mossy cells from other hilar neurons even if all morphological and physiological information is unavailable due to technical limitations of their experiments. In addition, hypotheses are discussed about the role of mossy cells in the DG network, reasons for their vulnerability and their implications for disease. PMID:23420672

a-Band Oscillations in Intracellular Membrane Potentials of Dentate Gyrus Neurons in Awake Rodents

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Anderson, Ross W.; Strowbridge, Ben W.

2014-01-01

The hippocampus and dentate gyrus play critical roles in processing declarative memories and spatial information. Dentate granule cells, the first relay in the trisynaptic circuit through the hippocampus, exhibit low spontaneous firing rates even during locomotion. Using intracellular recordings from dentate neurons in awake mice operating a…

A million-plus neuron model of the hippocampal dentate gyrus: Dependency of spatio-temporal network dynamics on topography.

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Hendrickson, Phillip J; Yu, Gene J; Song, Dong; Berger, Theodore W

2015-01-01

This paper describes a million-plus granule cell compartmental model of the rat hippocampal dentate gyrus, including excitatory, perforant path input from the entorhinal cortex, and feedforward and feedback inhibitory input from dentate interneurons. The model includes experimentally determined morphological and biophysical properties of granule cells, together with glutamatergic AMPA-like EPSP and GABAergic GABAA-like IPSP synaptic excitatory and inhibitory inputs, respectively. Each granule cell was composed of approximately 200 compartments having passive and active conductances distributed throughout the somatic and dendritic regions. Modeling excitatory input from the entorhinal cortex was guided by axonal transport studies documenting the topographical organization of projections from subregions of the medial and lateral entorhinal cortex, plus other important details of the distribution of glutamatergic inputs to the dentate gyrus. Results showed that when medial and lateral entorhinal cortical neurons maintained Poisson random firing, dentate granule cells expressed, throughout the million-cell network, a robust, non-random pattern of spiking best described as spatiotemporal "clustering". To identify the network property or properties responsible for generating such firing "clusters", we progressively eliminated from the model key mechanisms such as feedforward and feedback inhibition, intrinsic membrane properties underlying rhythmic burst firing, and/or topographical organization of entorhinal afferents. Findings conclusively identified topographical organization of inputs as the key element responsible for generating a spatio-temporal distribution of clustered firing. These results uncover a functional organization of perforant path afferents to the dentate gyrus not previously recognized: topography-dependent clusters of granule cell activity as "functional units" that organize the processing of entorhinal signals.

Structural plasticity in the dentate gyrus- revisiting a classic injury model.

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Julia V. Perederiy

2013-02-01

Full Text Available The adult brain is in a continuous state of remodeling. This is nowhere more true than in the dentate gyrus, where competing forces such as neurodegeneration and neurogenesis dynamically modify neuronal connectivity, and can occur simultaneously. This plasticity of the adult nervous system is particularly important in the context of traumatic brain injury or deafferentation. In this review, we summarize a classic injury model, lesioning of the perforant path, which removes the main extrahippocampal input to the dentate gyrus. Early studies revealed that in response to deafferentation, axons of remaining fiber systems and dendrites of mature granule cells undergo lamina-specific changes, providing one of the first examples of structural plasticity in the adult brain. Given the increasing role of adult-generated new neurons in the function of the dentate gyrus, we also compare the response of newborn and mature granule cells following lesioning of the perforant path. These studies provide insights not only to plasticity in the dentate gyrus, but also to the response of neural circuits to brain injury.

Effect of Aggregated β-Amyloid (1-42 on Synaptic Plasticity of Hippocampal Dentate Gyrus Granule Cells in Vivo

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Shirin Babri

2012-12-01

Full Text Available Introduction: Alzheimer’s disease (AD is a common neurodegenerative disorder in elderly people with an impairment of cognitive decline and memory loss. β-amyloid (Aβ as a potent neurotoxic peptide has a pivotal role in the pathogenesis of AD. This disease begins with impairment in synaptic functions before developing into later neuro­degeneration and neuronal loss. The aim of this study was to evaluate the synaptic plasticity and electrophysiological function of granule cells in hippocampal dentate gyrus (DG after intracerebroventricular (i.c.v. administration of aggregated Aβ (1-42 peptide in vivo. Methods: Animals were divided to control and Aβ (1-42 groups. Long-term potentia­tion (LTP in perforant path-DG synapses was assessed in order to investigate the effect of aggregated Aβ (1-42 on synaptic plasticity. Field excitatory post-synaptic potential (fEPSP slope and population spike (PS amplitude were measured. Results: Administration of Aβ (1-42 significantly decreased fEPSP slope and PS amplitude in Aβ (1-42 group comparing with the control group and had no effect on baseline activity of neurons. Conclusion: The present study indicates that administration of aggregated form of Aβ (1-42 into the lateral ventricle effectively inhibits LTP in granular cells of the DG in hippocampus in vivo.

Intrinsic neurophysiological properties of hilar ectopic and normotopic dentate granule cells in human temporal lobe epilepsy and a rat model.

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Althaus, A L; Sagher, O; Parent, J M; Murphy, G G

2015-02-15

Hilar ectopic dentate granule cells (DGCs) are a salient feature of aberrant plasticity in human temporal lobe epilepsy (TLE) and most rodent models of the disease. Recent evidence from rodent TLE models suggests that hilar ectopic DGCs contribute to hyperexcitability within the epileptic hippocampal network. Here we investigate the intrinsic excitability of DGCs from humans with TLE and the rat pilocarpine TLE model with the objective of comparing the neurophysiology of hilar ectopic DGCs to their normotopic counterparts in the granule cell layer (GCL). We recorded from 36 GCL and 7 hilar DGCs from human TLE tissue. Compared with GCL DGCs, hilar DGCs in patient tissue exhibited lower action potential (AP) firing rates, more depolarized AP threshold, and differed in single AP waveform, consistent with an overall decrease in excitability. To evaluate the intrinsic neurophysiology of hilar ectopic DGCs, we made recordings from retrovirus-birthdated, adult-born DGCs 2-4 mo after pilocarpine-induced status epilepticus or sham treatment in rats. Hilar DGCs from epileptic rats exhibited higher AP firing rates than normotopic DGCs from epileptic or control animals. They also displayed more depolarized resting membrane potential and wider AP waveforms, indicating an overall increase in excitability. The contrasting findings between disease and disease model may reflect differences between the late-stage disease tissue available from human surgical specimens and the earlier disease stage examined in the rat TLE model. These data represent the first neurophysiological characterization of ectopic DGCs from human hippocampus and prospectively birthdated ectopic DGCs in a rodent TLE model. Copyright © 2015 the American Physiological Society.

Role of corticosteroid hormones in the dentate gyrus.

NARCIS (Netherlands)

Joëls, M.

2007-01-01

Dentate granule cells are enriched with receptors for the stress hormone corticosterone, i.e., the high-affinity mineralocorticoid receptor (MR), which is already extensively occupied with low levels of the hormone, and the glucocorticoid receptor (GR), which is particularly activated after stress.

Status Epilepticus Induced Spontaneous Dentate Gyrus Spikes: In Vivo Current Source Density Analysis.

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Sean P Flynn

Full Text Available The dentate gyrus is considered to function as an inhibitory gate limiting excitatory input to the hippocampus. Following status epilepticus (SE, this gating function is reduced and granule cells become hyper-excitable. Dentate spikes (DS are large amplitude potentials observed in the dentate gyrus (DG of normal animals. DS are associated with membrane depolarization of granule cells, increased activity of hilar interneurons and suppression of CA3 and CA1 pyramidal cell firing. Therefore, DS could act as an anti-excitatory mechanism. Because of the altered gating function of the dentate gyrus following SE, we sought to investigate how DS are affected following pilocarpine-induced SE. Two weeks following lithium-pilocarpine SE induction, hippocampal EEG was recorded in male Sprague-Dawley rats with 16-channel silicon probes under urethane anesthesia. Probes were placed dorso-ventrally to encompass either CA1-CA3 or CA1-DG layers. Large amplitude spikes were detected from EEG recordings and subject to current source density analysis. Probe placement was verified histologically to evaluate the anatomical localization of current sinks and the origin of DS. In 9 of 11 pilocarpine-treated animals and two controls, DS were confirmed with large current sinks in the molecular layer of the dentate gyrus. DS frequency was significantly increased in pilocarpine-treated animals compared to controls. Additionally, in pilocarpine-treated animals, DS displayed current sinks in the outer, middle and/or inner molecular layers. However, there was no difference in the frequency of events when comparing between layers. This suggests that following SE, DS can be generated by input from medial and lateral entorhinal cortex, or within the dentate gyrus. DS were associated with an increase in multiunit activity in the granule cell layer, but no change in CA1. These results suggest that following SE there is an increase in DS activity, potentially arising from

Differential Structural Development of Adult-Born Septal Hippocampal Granule Cells in the Thy1-GFP Mouse, Nuclear Size as a New Index of Maturation.

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Tijana Radic

Full Text Available Adult neurogenesis is frequently studied in the mouse hippocampus. We examined the morphological development of adult-born, immature granule cells in the suprapyramidal blade of the septal dentate gyrus over the period of 7-77 days after mitosis with BrdU-labeling in 6-weeks-old male Thy1-GFP mice. As Thy1-GFP expression was restricted to maturated granule cells, it was combined with doublecortin-immunolabeling of immature granule cells. We developed a novel classification system that is easily applicable and enables objective and direct categorization of newborn granule cells based on the degree of dendritic development in relation to the layer specificity of the dentate gyrus. The structural development of adult-generated granule cells was correlated with age, albeit with notable differences in the time course of development between individual cells. In addition, the size of the nucleus, immunolabeled with the granule cell specific marker Prospero-related homeobox 1 gene, was a stable indicator of the degree of a cell's structural maturation and could be used as a straightforward parameter of granule cell development. Therefore, further studies could employ our doublecortin-staging system and nuclear size measurement to perform investigations of morphological development in combination with functional studies of adult-born granule cells. Furthermore, the Thy1-GFP transgenic mouse model can be used as an additional investigation tool because the reporter gene labels granule cells that are 4 weeks or older, while very young cells could be visualized through the immature marker doublecortin. This will enable comparison studies regarding the structure and function between young immature and older matured granule cells.

Naringin attenuates granule cell dispersion in the dentate gyrus in a mouse model of temporal lobe epilepsy.

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Jang, Hannah; Jeong, Kyoung Hoon; Kim, Sang Ryong

2016-07-01

Morphological abnormalities of the dentate gyrus (DG) are an important phenotype in the hippocampus of patients with temporal lobe epilepsy. We recently reported that naringin, a bioflavonoid in grapefruit and citrus fruits, exerts beneficial effects in the kainic acid (KA) mouse model of epilepsy. We found that naringin treatment reduced seizure activities and decreased autophagic stress and neuroinflammation in the hippocampus following in vivo lesion with KA. However, it remains unclear whether naringin may also attenuate seizure-induced morphological changes in the DG, collectively known as granule cell dispersion (GCD). To clarify whether naringin treatment reduces GCD, we evaluated the effects of intraperitoneal injection of naringin on GCD and activation of mammalian target of rapamycin complex 1 (mTORC1), an important regulator of GCD, following intrahippocampal injection of KA. Our results showed that naringin treatment significantly reduced KA-induced GCD and mTORC1 activation, which was confirmed by assessing the phosphorylated form of the mTORC1 substrate, 4E-BP1, in the hippocampus. These results suggest that naringin treatment may help prevent epilepsy-induced hippocampal injury by inhibiting mTORC1 activation and thereby reducing GCD in the hippocampus in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

Facilitation of granule cell epileptiform activity by mossy fiber-released zinc in the pilocarpine model of temporal lobe epilepsy.

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Timofeeva, Olga; Nadler, J Victor

2006-03-17

Recurrent mossy fiber synapses in the dentate gyrus of epileptic brain facilitate the synchronous firing of granule cells and may promote seizure propagation. Mossy fiber terminals contain and release zinc. Released zinc inhibits the activation of NMDA receptors and may therefore oppose the development of granule cell epileptiform activity. Hippocampal slices from rats that had experienced pilocarpine-induced status epilepticus and developed a recurrent mossy fiber pathway were used to investigate this possibility. Actions of released zinc were inferred from the effects of chelation with 1 mM calcium disodium EDTA (CaEDTA). When granule cell population bursts were evoked by mossy fiber stimulation in the presence of 6 mM K(+) and 30 microM bicuculline, CaEDTA slowed the rate at which evoked bursting developed, but did not change the magnitude of the bursts once they had developed fully. The effects of CaEDTA were then studied on the pharmacologically isolated NMDA receptor- and AMPA/kainate receptor-mediated components of the fully developed bursts. CaEDTA increased the magnitude of NMDA receptor-mediated bursts and reduced the magnitude of AMPA/kainate receptor-mediated bursts. CaEDTA did not affect the granule cell bursts evoked in slices from untreated rats by stimulating the perforant path in the presence of bicuculline and 6 mM K(+). These results suggest that zinc released from the recurrent mossy fibers serves mainly to facilitate the recruitment of dentate granule cells into population bursts.

Dentate Gyrus-Specific Knockdown of Adult Neurogenesis Impairs Spatial and Object Recognition Memory in Adult Rats

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Jessberger, Sebastian; Clark, Robert E.; Broadbent, Nicola J.; Clemenson, Gregory D., Jr.; Consiglio, Antonella; Lie, D. Chichung; Squire, Larry R.; Gage, Fred H.

2009-01-01

New granule cells are born throughout life in the dentate gyrus of the hippocampal formation. Given the fundamental role of the hippocampus in processes underlying certain forms of learning and memory, it has been speculated that newborn granule cells contribute to cognition. However, previous strategies aiming to causally link newborn neurons…

Decrement of GABAA receptor-mediated inhibitory postsynaptic currents in dentate granule cells in epileptic hippocampus.

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Isokawa, M

1996-05-01

1. Inhibitory postsynaptic currents (IPSCs) were studied in hippocampal dentate granule cells (DGCs) in the pilocarpine model and human temporal lobe epilepsy, with the use of the whole cell patch-clamp recording technique in slice preparations. 2. In the pilocarpine model, hippocampal slices were prepared from rats that were allowed to experience spontaneous seizures for 2 mo. Human hippocampal specimens were obtained from epileptic patients who underwent surgical treatment for medically intractable seizures. 3. IPSCs were generated by single perforant path stimulation and recorded at a membrane potential (Vm) of 0 mV near the reversal potential of glutamate excitatory postsynaptic currents in the voltage-clamp recording. IPSCs were pharmacologically identified as gamma-aminobutyric acid-A (GABAA) IPSCs by 10 microM bicuculline methiodide. 4. During low-frequency stimulation, IPSCs were not different in amplitude among non-seizure-experienced rat hippocampi, human nonsclerotic hippocampi, seizure-experienced rat hippocampi, and human sclerotic hippocampi. In the last two groups of DGCs, current-clamp recordings indicated the presence of prolonged excitatory postsynaptic potentials (EPSPs) mediated by the N-methyl-D-aspartate (NMDA) receptor. 5. High-frequency stimulation, administered at Vm = -30 mV to activate NMDA currents, reduced GABAA IPSC amplitude specifically in seizure-experienced rat hippocampi (t = 2.5, P < 0.03) and human sclerotic hippocampi (t = 7.7, P < 0.01). This reduction was blocked by an NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid (APV) (50 microM). The time for GABAA IPSCs to recover to their original amplitude was also shortened by the application of APV. 6. I conclude that, when intensively activated, NMDA receptor-mediated excitatory transmission may interact with GABAergic synaptic inhibition in DGCs in seizure-experienced hippocampus to transiently reduce GABA(A) receptor-channel function. Such interactions may contribute to

Interictal psychosis following temporal lobe surgery: dentate gyrus pathology.

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Thom, M; Kensche, M; Maynard, J; Liu, J; Reeves, C; Goc, J; Marsdon, D; Fluegel, D; Foong, J

2014-10-01

De novo interictal psychosis, albeit uncommon, can develop in patients following temporal lobe surgery for epilepsy. Pathological alterations of the dentate gyrus, including cytoarchitectural changes, immaturity and axonal reorganization that occur in epilepsy, may also underpin co-morbid psychiatric disorders. Our aim was to study candidate pathways that may be associated with the development of interictal psychosis post-operatively in patients with hippocampal sclerosis (HS). A total of 11 patients with HS who developed interictal psychosis (HS-P) post-operatively were compared with a matched surgical HS group without psychosis (HS-NP). Resected tissues were investigated for the extent of granule cell dispersion, mossy fibre sprouting and calbindin expression in the granule cells. We quantified doublecortin, mini-chromosome maintenance protein 2 (MCM2) and reelin-expressing neuronal populations in the dentate gyrus as well as the distribution of cannabinoid type 1 receptor (CBR1). The patterns of neuronal loss and gliosis were similar in both groups. HS-P patients demonstrated less mossy fibre sprouting and granule cell dispersion (p gyrus pathology found in HS-P patients could indicate underlying differences in the cellular response to seizures. These mechanisms may predispose to the development of psychosis in epilepsy and warrant further investigation.

Balloon cells associated with granule cell dispersion in the dentate gyrus in hippocampal sclerosis.

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Thom, M; Martinian, L; Caboclo, L O; McEvoy, A W; Sisodiya, S M

2008-06-01

Granule cell dispersion (GCD) is a common finding in hippocampal sclerosis in patients with intractable focal epilepsy. It is considered to be an acquired, post-developmental rather than a pre-existing abnormality, involving dispersion of either mature or newborn neurones, but the precise factors regulating it and its relationship to seizures are unknown. We present two cases of GCD with associated CD34-immunopositive balloon cells, a cell phenotype associated with focal cortical dysplasia type IIB, considered to be a developmental cortical lesion promoting epilepsy. This observation opens up the debate regarding the origin of balloon cells and CD34 expression and their temporal relationship to seizures.

Behavioral experience induces zif268 expression in mature granule cells but suppresses its expression in immature granule cells

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Kylie A. Huckleberry

2015-08-01

Full Text Available Thousands of neurons are born each day in the dentate gyrus (DG, but many of these cells die before reaching maturity. Both death and survival of adult-born neurons are regulated by neuronal activity in DG. The immediate-early gene (IEG zif268 is an important mediator of these effects, as its expression is induced by neural activity and knockout of zif268 impairs survival of adult-born neurons (Veyrac et al., 2013. Despite the apparent importance of zif268 for adult neurogenesis, its behavior-induced expression has not been fully characterized in adult-born neurons. Here we characterize behavior-evoked expression of zif268 in mature and newborn dentate granule cells (DGCs. In the general granule cell population, zif268 expression peaked 1 hour after novel environment exposure and returned to baseline by 8 hours post-exposure. However, in the doublecortin-positive (DCX+ immature neurons, zif268 expression was suppressed relative to home cage for at least 8 hours post-exposure. We next determined that exposure to water maze training, an enriched environment, or a novel environment caused approximately equal suppression of zif268 expression in DCX+ cells and approximately equal activation of zif268 in the general DGC population and in 6-week-old adult-born neurons. Finally, we asked whether zif268 suppression varied as a function of age within the DCX+ population, which ranges in age from 0 to approximately 4 weeks. Novel environment exposure had no significant effect on zif268 expression in 2- or 4-week-old BrdU-labeled neurons, but it significantly suppressed zif268 expression in 3-week-old neurons. In summary, behavioral experience transiently activated expression of zif268 in mature DGCs but caused a more long-lasting suppression of zif268 expression in immature, adult-born DGCs. We hypothesize that zif268 suppression inhibits memory-related synaptic plasticity in immature DGCs or mediates learning-induced apoptosis of immature adult

Single K ATP channel opening in response to action potential firing in mouse dentate granule neurons.

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Tanner, Geoffrey R; Lutas, Andrew; Martínez-François, Juan Ramón; Yellen, Gary

2011-06-08

ATP-sensitive potassium channels (K(ATP) channels) are important sensors of cellular metabolic state that link metabolism and excitability in neuroendocrine cells, but their role in nonglucosensing central neurons is less well understood. To examine a possible role for K(ATP) channels in modulating excitability in hippocampal circuits, we recorded the activity of single K(ATP) channels in cell-attached patches of granule cells in the mouse dentate gyrus during bursts of action potentials generated by antidromic stimulation of the mossy fibers. Ensemble averages of the open probability (p(open)) of single K(ATP) channels over repeated trials of stimulated spike activity showed a transient increase in p(open) in response to action potential firing. Channel currents were identified as K(ATP) channels through blockade with glibenclamide and by comparison with recordings from Kir6.2 knock-out mice. The transient elevation in K(ATP) p(open) may arise from submembrane ATP depletion by the Na(+)-K(+) ATPase, as the pump blocker strophanthidin reduced the magnitude of the elevation. Both the steady-state and stimulus-elevated p(open) of the recorded channels were higher in the presence of the ketone body R-β-hydroxybutyrate, consistent with earlier findings that ketone bodies can affect K(ATP) activity. Using perforated-patch recording, we also found that K(ATP) channels contribute to the slow afterhyperpolarization following an evoked burst of action potentials. We propose that activity-dependent opening of K(ATP) channels may help granule cells act as a seizure gate in the hippocampus and that ketone-body-mediated augmentation of the activity-dependent opening could in part explain the effect of the ketogenic diet in reducing epileptic seizures.

The forced swimming-induced behavioural immobility response involves histone H3 phospho-acetylation and c-Fos induction in dentate gyrus granule neurons via activation of the N-methyl-D-aspartate/extracellular signal-regulated kinase/mitogen- and stress-activated kinase signalling pathway.

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Chandramohan, Yalini; Droste, Susanne K; Arthur, J Simon C; Reul, Johannes M H M

2008-05-01

The hippocampus is involved in learning and memory. Previously, we have shown that the acquisition of the behavioural immobility response after a forced swim experience is associated with chromatin modifications and transcriptional induction in dentate gyrus granule neurons. Given that both N-methyl-D-aspartate (NMDA) receptors and the extracellular signal-regulated kinases (ERK) 1/2 signalling pathway are involved in neuroplasticity processes underlying learning and memory, we investigated in rats and mice whether these signalling pathways regulate chromatin modifications and transcriptional events participating in the acquisition of the immobility response. We found that: (i) forced swimming evoked a transient increase in the number of phospho-acetylated histone H3-positive [P(Ser10)-Ac(Lys14)-H3(+)] neurons specifically in the middle and superficial aspects of the dentate gyrus granule cell layer; (ii) antagonism of NMDA receptors and inhibition of ERK1/2 signalling blocked forced swimming-induced histone H3 phospho-acetylation and the acquisition of the behavioural immobility response; (iii) double knockout (DKO) of the histone H3 kinase mitogen- and stress-activated kinases (MSK) 1/2 in mice completely abolished the forced swimming-induced increases in histone H3 phospho-acetylation and c-Fos induction in dentate granule neurons and the behavioural immobility response; (iv) blocking mineralocorticoid receptors, known not to be involved in behavioural immobility in the forced swim test, did not affect forced swimming-evoked histone H3 phospho-acetylation in dentate neurons; and (v) the pharmacological manipulations and gene deletions did not affect behaviour in the initial forced swim test. We conclude that the forced swimming-induced behavioural immobility response requires histone H3 phospho-acetylation and c-Fos induction in distinct dentate granule neurons through recruitment of the NMDA/ERK/MSK 1/2 pathway.

Synaptic Plasticity and Excitation-Inhibition Balance in the Dentate Gyrus: Insights from In Vivo Recordings in Neuroligin-1, Neuroligin-2, and Collybistin Knockouts.

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Jedlicka, Peter; Muellerleile, Julia; Schwarzacher, Stephan W

2018-01-01

The hippocampal dentate gyrus plays a role in spatial learning and memory and is thought to encode differences between similar environments. The integrity of excitatory and inhibitory transmission and a fine balance between them is essential for efficient processing of information. Therefore, identification and functional characterization of crucial molecular players at excitatory and inhibitory inputs is critical for understanding the dentate gyrus function. In this minireview, we discuss recent studies unraveling molecular mechanisms of excitatory/inhibitory synaptic transmission, long-term synaptic plasticity, and dentate granule cell excitability in the hippocampus of live animals. We focus on the role of three major postsynaptic proteins localized at excitatory (neuroligin-1) and inhibitory synapses (neuroligin-2 and collybistin). In vivo recordings of field potentials have the advantage of characterizing the effects of the loss of these proteins on the input-output function of granule cells embedded in a network with intact connectivity. The lack of neuroligin-1 leads to deficient synaptic plasticity and reduced excitation but normal granule cell output, suggesting unaltered excitation-inhibition ratio. In contrast, the lack of neuroligin-2 and collybistin reduces inhibition resulting in a shift towards excitation of the dentate circuitry.

Synaptic Plasticity and Excitation-Inhibition Balance in the Dentate Gyrus: Insights from In Vivo Recordings in Neuroligin-1, Neuroligin-2, and Collybistin Knockouts

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Peter Jedlicka

2018-01-01

Full Text Available The hippocampal dentate gyrus plays a role in spatial learning and memory and is thought to encode differences between similar environments. The integrity of excitatory and inhibitory transmission and a fine balance between them is essential for efficient processing of information. Therefore, identification and functional characterization of crucial molecular players at excitatory and inhibitory inputs is critical for understanding the dentate gyrus function. In this minireview, we discuss recent studies unraveling molecular mechanisms of excitatory/inhibitory synaptic transmission, long-term synaptic plasticity, and dentate granule cell excitability in the hippocampus of live animals. We focus on the role of three major postsynaptic proteins localized at excitatory (neuroligin-1 and inhibitory synapses (neuroligin-2 and collybistin. In vivo recordings of field potentials have the advantage of characterizing the effects of the loss of these proteins on the input-output function of granule cells embedded in a network with intact connectivity. The lack of neuroligin-1 leads to deficient synaptic plasticity and reduced excitation but normal granule cell output, suggesting unaltered excitation-inhibition ratio. In contrast, the lack of neuroligin-2 and collybistin reduces inhibition resulting in a shift towards excitation of the dentate circuitry.

The GAD-given Right of Dentate Gyrus Granule Cells to Become GABAergic

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Mody, Istvan

2002-01-01

low-affinity neurotrophin receptor p75NTR, perhaps as part of a programmed developmental switch, can convert the phenotype of the sympathetic neuron from noradrenergic to cholinergic 4. Other examples of two fast neurotransmitters released from the same neuron include GABA and glycine in interneurons of the spinal cord 5 and glutamate and dopamine in ventral midbrain dopamine neurons 6. Of all CNS neurons, the granule cells of the dentate gyrus appear to be the champions of neurotransmitter colocalization: glutamate, enkephalin, dynorphin, zinc, and finally GABA 2, 7, 8, 9. With this many transmitters in a single neuron, there are probably different ways in which they can be released. Dynorphin and other opioid peptides can be released directly from the dendrites to inhibit excitatory transmission 8. A similar mechanism may take place for GABA, as described in cortical GABAergic neurons 10. PMID:15309121

Hilar somatostatin interneuron loss reduces dentate gyrus inhibition in a mouse model of temporal lobe epilepsy.

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Hofmann, Gabrielle; Balgooyen, Laura; Mattis, Joanna; Deisseroth, Karl; Buckmaster, Paul S

2016-06-01

In patients with temporal lobe epilepsy, seizures usually start in the hippocampus, and dentate granule cells are hyperexcitable. Somatostatin interneurons are a major subpopulation of inhibitory neurons in the dentate gyrus, and many are lost in patients and animal models. However, surviving somatostatin interneurons sprout axon collaterals and form new synapses, so the net effect on granule cell inhibition remains unclear. The present study uses optogenetics to activate hilar somatostatin interneurons and measure the inhibitory effect on dentate gyrus perforant path-evoked local field potential responses in a mouse model of temporal lobe epilepsy. In controls, light activation of hilar somatostatin interneurons inhibited evoked responses up to 40%. Epileptic pilocarpine-treated mice exhibited loss of hilar somatostatin interneurons and less light-induced inhibition of evoked responses. These findings suggest that severe epilepsy-related loss of hilar somatostatin interneurons can overwhelm the surviving interneurons' capacity to compensate by sprouting axon collaterals. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

Is Arc mRNA Unique: A Search for mRNAs That Localize to the Distal Dendrites of Dentate Gyrus Granule Cells Following Neural Activity

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Christopher A. de Solis

2017-10-01

Full Text Available There have been several attempts to identify which RNAs are localized to dendrites; however, no study has determined which RNAs localize to the dendrites following the induction of synaptic activity. We sought to identify all RNA transcripts that localize to the distal dendrites of dentate gyrus granule cells following unilateral high frequency stimulation of the perforant pathway (pp-HFS using Sprague Dawley rats. We then utilized laser microdissection (LMD to very accurately dissect out the distal 2/3rds of the molecular layer (ML, which contains these dendrites, without contamination from the granule cell layer, 2 and 4 h post pp-HFS. Next, we purified and amplified RNA from the ML and performed an unbiased screen for 27,000 RNA transcripts using Affymetrix microarrays. We determined that Activity Regulated Cytoskeletal Protein (Arc/Arg3.1 mRNA, exhibited the greatest fold increase in the ML at both timepoints (2 and 4 h. In total, we identified 31 transcripts that increased their levels within the ML following pp-HFS across the two timepoints. Of particular interest is that one of these identified transcripts was an unprocessed micro-RNA (pri-miR132. Fluorescent in situ hybridization and qRT-PCR were used to confirm some of these candidate transcripts. Our data indicate Arc is a unique activity dependent gene, due to the magnitude that its activity dependent transcript localizes to the dendrites. Our study determined other activity dependent transcripts likely localize to the dendrites following neural activity, but do so with lower efficiency compared to Arc.

Extended Interneuronal Network of the Dentate Gyrus

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Gergely G. Szabo

2017-08-01

Full Text Available Local interneurons control principal cells within individual brain areas, but anecdotal observations indicate that interneuronal axons sometimes extend beyond strict anatomical boundaries. Here, we use the case of the dentate gyrus (DG to show that boundary-crossing interneurons with cell bodies in CA3 and CA1 constitute a numerically significant and diverse population that relays patterns of activity generated within the CA regions back to granule cells. These results reveal the existence of a sophisticated retrograde GABAergic circuit that fundamentally extends the canonical interneuronal network.

Weakened Intracellular Zn2+-Buffering in the Aged Dentate Gyrus and Its Involvement in Erasure of Maintained LTP.

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Takeda, Atsushi; Tamano, Haruna; Murakami, Taku; Nakada, Hiroyuki; Minamino, Tatsuya; Koike, Yuta

2018-05-01

Memory is lost by the increased influx of extracellular Zn 2+ into neurons. It is possible that intracellular Zn 2+ dynamics is modified even at non-zincergic medial perforant pathway-dentate granule cell synapses along with aging and that vulnerability to the modification is linked to age-related cognitive decline. To examine these possibilities, vulnerability of long-term potentiation (LTP) maintenance, which underlies memory retention, to modification of synaptic Zn 2+ dynamics was compared between young and aged rats. The influx of extracellular Zn 2+ into dentate granule cells was increased in aged rats after injection of high K + into the dentate gyrus, but not in young rats. This increase impaired maintained LTP in aged rats. However, the impairment was rescued by co-injection of CaEDTA, an extracellular Zn 2+ chelator, or CNQX, an AMPA receptor antagonist, which suppressed the Zn 2+ influx. Maintained LTP was also impaired in aged rats after injection of ZnAF-2DA into the dentate gyrus that chelates intracellular Zn 2+ , but not in young rats. Interestingly, the capacity of chelating intracellular Zn 2+ with intracellular ZnAF-2 was almost lost in the aged dentate gyrus 2 h after injection of ZnAF-2DA into the dentate gyrus, suggesting that intracellular Zn 2+ -buffering is weakened in the aged dentate gyrus, compared to the young dentate gyrus. In the dentate gyrus of aged rats, maintained LTP is more vulnerable to modification of intracellular Zn 2+ dynamics than in young rats, probably due to weakened intracellular Zn 2+ -buffering.

Chronic unpredictable stress alters gene expression in rat single dentate granule cells

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Qin, Y.J.; Karst, H.; Joëls, M.

2004-01-01

The rat adrenal hormone corticosterone binds to low and high affinity receptors, discretely localized in brain, including the dentate gyrus. Differential activation of the two receptor types under physiological conditions alters gene expression and functional characteristics of hippocampal neurones.

Adiponectin regulates contextual fear extinction and intrinsic excitability of dentate gyrus granule neurons through AdipoR2 receptors.

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Zhang, D; Wang, X; Wang, B; Garza, J C; Fang, X; Wang, J; Scherer, P E; Brenner, R; Zhang, W; Lu, X-Y

2017-07-01

Post-traumatic stress disorder (PTSD) is characterized by exaggerated fear expression and impaired fear extinction. The underlying molecular and cellular mechanisms of PTSD are largely unknown. The current pharmacological and non-pharmacological treatments for PTSD are either ineffective or temporary with high relapse rates. Here we report that adiponectin-deficient mice exhibited normal contextual fear conditioning but displayed slower extinction learning. Infusions of adiponectin into the dentate gyrus (DG) of the hippocampus in fear-conditioned mice facilitated extinction of contextual fear. Whole-cell patch-clamp recordings in brain slices revealed that intrinsic excitability of DG granule neurons was enhanced by adiponectin deficiency and suppressed after treatment with the adiponectin mimetic AdipoRon, which were associated with increased input resistance and hyperpolarized resting membrane potential, respectively. Moreover, deletion of AdipoR2, but not AdipoR1 in the DG, resulted in augmented fear expression and reduced extinction, accompanied by intrinsic hyperexcitability of DG granule neurons. Adiponectin and AdipoRon failed to induce facilitation of fear extinction and elicit inhibition of intrinsic excitability of DG neurons in AdipoR2 knockout mice. These results indicated that adiponectin action via AdipoR2 was both necessary and sufficient for extinction of contextual fear and intrinsic excitability of DG granule neurons, implying that enhancing or dampening DG neuronal excitability may cause resistance to or facilitation of extinction. Therefore, our findings provide a functional link between adiponectin/AdipoR2 activation, DG neuronal excitability and contextual fear extinction, and suggest that targeting adiponectin/AdipoR2 may be used to strengthen extinction-based exposure therapies for PTSD.

Ramipril mitigates radiation-induced impairment of neurogenesis in the rat dentate gyrus

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Jenrow, Kenneth A; Brown, Stephen L; Liu, Jianguo; Kolozsvary, Andrew; Lapanowski, Karen; Kim, Jae Ho

2010-01-01

Sublethal doses of whole brain irradiation (WBI) are commonly administered therapeutically and frequently result in late delayed radiation injuries, manifesting as severe and irreversible cognitive impairment. Neural progenitors within the subgranular zone (SGZ) of the dentate gyrus are among the most radiosensitive cell types in the adult brain and are known to participate in hippocampal plasticity and normal cognitive function. These progenitors and the specialized SZG microenvironment required for neuronal differentiation are the source of neurogenic potential in the adult dentate gyrus, and provide a continuous supply of immature neurons which may then migrate into the adjacent granule cell layer to become mature granule cell neurons. The extreme radiosensitivity of these progenitors and the SGZ microenvironment suggests the hippocampus as a prime target for radiation-induced cognitive impairment. The brain renin-angiotensin system (RAS) has previously been implicated as a potent modulator of neurogenesis within the SGZ and selective RAS inhibitors have been implicated as mitigators of radiation brain injury. Here we investigate the angiotensin converting enzyme (ACE) inhibitor, ramipril, as a mitigator of radiation injury in this context. Adult male Fisher 344 rats received WBI at doses of 10 Gy and 15 Gy. Ramipril was administered beginning 24 hours post-WBI and maintained continuously for 12 weeks. Ramipril produced small but significant reductions in the deleterious effects of radiation on progenitor proliferation and neuronal differentiation in the rat dentate gyrus following 10 Gy-WBI, but was not effective following 15 Gy-WBI. Ramipril also reduced the basal rate of neurogenesis within the SGZ in unirradiated control rats. Our results indicate that chronic ACE inhibition with ramipril, initiated 24 hours post-irradiation, may reduce apoptosis among SGZ progenitors and/or inflammatory disruption of neurogenic signaling within SGZ microenvironment, and

CXCL12-mediated feedback from granule neurons regulates generation and positioning of new neurons in the dentate gyrus.

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Abe, Philipp; Wüst, Hannah M; Arnold, Sebastian J; van de Pavert, Serge A; Stumm, Ralf

2018-03-14

Adult hippocampal neurogenesis is implicated in learning and memory processing. It is tightly controlled at several levels including progenitor proliferation as well as migration, differentiation and integration of new neurons. Hippocampal progenitors and immature neurons reside in the subgranular zone (SGZ) and are equipped with the CXCL12-receptor CXCR4 which contributes to defining the SGZ as neurogenic niche. The atypical CXCL12-receptor CXCR7 functions primarily by sequestering extracellular CXCL12 but whether CXCR7 is involved in adult neurogenesis has not been assessed. We report that granule neurons (GN) upregulate CXCL12 and CXCR7 during dentate gyrus maturation in the second postnatal week. To test whether GN-derived CXCL12 regulates neurogenesis and if neuronal CXCR7 receptors influence this process, we conditionally deleted Cxcl12 and Cxcr7 from the granule cell layer. Cxcl12 deletion resulted in lower numbers, increased dispersion and abnormal dendritic growth of immature GN and reduced neurogenesis. Cxcr7 ablation caused an increase in progenitor proliferation and progenitor numbers and reduced dispersion of immature GN. Thus, we provide a new mechanism where CXCL12-signals from GN prevent dispersion and support maturation of newborn GN. CXCR7 receptors of GN modulate the CXCL12-mediated feedback from GN to the neurogenic niche. © 2018 Wiley Periodicals, Inc.

Age-dependent kinetics of dentate gyrus neurogenesis in the absence of cyclin D2

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Ansorg Anne

2012-05-01

Full Text Available Abstract Background Adult neurogenesis continuously adds new neurons to the dentate gyrus and the olfactory bulb. It involves the proliferation and subsequent differentiation of neuronal progenitors, and is thus closely linked to the cell cycle machinery. Cell cycle progression is governed by the successive expression, activation and degradation of regulatory proteins. Among them, D-type cyclins control the exit from the G1 phase of the cell cycle. Cyclin D2 (cD2 has been shown to be required for the generation of new neurons in the neurogenic niches of the adult brain. It is differentially expressed during hippocampal development, and adult cD2 knock out (cD2KO mice virtually lack neurogenesis in the dentate gyrus and olfactory bulb. In the present study we examined the dynamics of postnatal and adult neurogenesis in the dentate gyrus (DG of cD2KO mice. Animals were injected with bromodeoxyuridine at seven time points during the first 10 months of life and brains were immunohistochemically analyzed for their potential to generate new neurons. Results Compared to their WT litters, cD2KO mice had considerably reduced numbers of newly born granule cells during the postnatal period, with neurogenesis becoming virtually absent around postnatal day 28. This was paralleled by a reduction in granule cell numbers, in the volume of the granule cell layer as well as in apoptotic cell death. CD2KO mice did not show any of the age-related changes in neurogenesis and granule cell numbers that were seen in WT litters. Conclusions The present study suggests that hippocampal neurogenesis becomes increasingly dependent on cD2 during early postnatal development. In cD2KO mice, hippocampal neurogenesis ceases at a time point at which the tertiary germinative matrix stops proliferating, indicating that cD2 becomes an essential requirement for ongoing neurogenesis with the transition from developmental to adult neurogenesis. Our data further support the notion that

Dissection of Hippocampal Dentate Gyrus from Adult Mouse

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Hagihara, Hideo; Toyama, Keiko; Yamasaki, Nobuyuki; Miyakawa, Tsuyoshi

2009-01-01

The hippocampus is one of the most widely studied areas in the brain because of its important functional role in memory processing and learning, its remarkable neuronal cell plasticity, and its involvement in epilepsy, neurodegenerative diseases, and psychiatric disorders. The hippocampus is composed of distinct regions; the dentate gyrus, which comprises mainly granule neurons, and Ammon's horn, which comprises mainly pyramidal neurons, and the two regions are connected by both anatomic and functional circuits. Many different mRNAs and proteins are selectively expressed in the dentate gyrus, and the dentate gyrus is a site of adult neurogenesis; that is, new neurons are continually generated in the adult dentate gyrus. To investigate mRNA and protein expression specific to the dentate gyrus, laser capture microdissection is often used. This method has some limitations, however, such as the need for special apparatuses and complicated handling procedures. In this video-recorded protocol, we demonstrate a dissection technique for removing the dentate gyrus from adult mouse under a stereomicroscope. Dentate gyrus samples prepared using this technique are suitable for any assay, including transcriptomic, proteomic, and cell biology analyses. We confirmed that the dissected tissue is dentate gyrus by conducting real-time PCR of dentate gyrus-specific genes, tryptophan 2,3-dioxygenase (TDO2) and desmoplakin (Dsp), and Ammon's horn enriched genes, Meis-related gene 1b (Mrg1b) and TYRO3 protein tyrosine kinase 3 (Tyro3). The mRNA expressions of TDO2 and Dsp in the dentate gyrus samples were detected at obviously higher levels, whereas Mrg1b and Tyro3 were lower levels, than those in the Ammon's horn samples. To demonstrate the advantage of this method, we performed DNA microarray analysis using samples of whole hippocampus and dentate gyrus. The mRNA expression of TDO2 and Dsp, which are expressed selectively in the dentate gyrus, in the whole hippocampus of alpha

Delayed coupling to feedback inhibition during a critical period for the integration of adult-born granule cells.

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Temprana, Silvio G; Mongiat, Lucas A; Yang, Sung M; Trinchero, Mariela F; Alvarez, Diego D; Kropff, Emilio; Giacomini, Damiana; Beltramone, Natalia; Lanuza, Guillermo M; Schinder, Alejandro F

2015-01-07

Developing granule cells (GCs) of the adult dentate gyrus undergo a critical period of enhanced activity and synaptic plasticity before becoming mature. The impact of developing GCs on the activity of preexisting dentate circuits remains unknown. Here we combine optogenetics, acute slice electrophysiology, and in vivo chemogenetics to activate GCs at different stages of maturation to study the recruitment of local target networks. We show that immature (4-week-old) GCs can efficiently drive distal CA3 targets but poorly activate proximal interneurons responsible for feedback inhibition (FBI). As new GCs transition toward maturity, they reliably recruit GABAergic feedback loops that restrict spiking of neighbor GCs, a mechanism that would promote sparse coding. Such inhibitory loop impinges only weakly in new cohorts of young GCs. A computational model reveals that the delayed coupling of new GCs to FBI could be crucial to achieve a fine-grain representation of novel inputs in the dentate gyrus. Copyright © 2015 Elsevier Inc. All rights reserved.

Ramipril mitigates radiation-induced impairment of neurogenesis in the rat dentate gyrus

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Lapanowski Karen

2010-02-01

Full Text Available Abstract Background Sublethal doses of whole brain irradiation (WBI are commonly administered therapeutically and frequently result in late delayed radiation injuries, manifesting as severe and irreversible cognitive impairment. Neural progenitors within the subgranular zone (SGZ of the dentate gyrus are among the most radiosensitive cell types in the adult brain and are known to participate in hippocampal plasticity and normal cognitive function. These progenitors and the specialized SZG microenvironment required for neuronal differentiation are the source of neurogenic potential in the adult dentate gyrus, and provide a continuous supply of immature neurons which may then migrate into the adjacent granule cell layer to become mature granule cell neurons. The extreme radiosensitivity of these progenitors and the SGZ microenvironment suggests the hippocampus as a prime target for radiation-induced cognitive impairment. The brain renin-angiotensin system (RAS has previously been implicated as a potent modulator of neurogenesis within the SGZ and selective RAS inhibitors have been implicated as mitigators of radiation brain injury. Here we investigate the angiotensin converting enzyme (ACE inhibitor, ramipril, as a mitigator of radiation injury in this context. Methods Adult male Fisher 344 rats received WBI at doses of 10 Gy and 15 Gy. Ramipril was administered beginning 24 hours post-WBI and maintained continuously for 12 weeks. Results Ramipril produced small but significant reductions in the deleterious effects of radiation on progenitor proliferation and neuronal differentiation in the rat dentate gyrus following 10 Gy-WBI, but was not effective following 15 Gy-WBI. Ramipril also reduced the basal rate of neurogenesis within the SGZ in unirradiated control rats. Conclusions Our results indicate that chronic ACE inhibition with ramipril, initiated 24 hours post-irradiation, may reduce apoptosis among SGZ progenitors and/or inflammatory

Hilar granule cells of the mouse dentate gyrus: effects of age, septotemporal location, strain, and selective deletion of the proapoptotic gene BAX.

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Bermudez-Hernandez, Keria; Lu, Yi-Ling; Moretto, Jillian; Jain, Swati; LaFrancois, John J; Duffy, Aine M; Scharfman, Helen E

2017-09-01

The dentate gyrus (DG) principal cells are glutamatergic granule cells (GCs), and they are located in a compact cell layer. However, GCs are also present in the adjacent hilar region, but have been described in only a few studies. Therefore, we used the transcription factor prospero homeobox 1 (Prox1) to quantify GCs at postnatal day (PND) 16, 30, and 60 in a common mouse strain, C57BL/6J mice. At PND16, there was a large population of Prox1-immunoreactive (ir) hilar cells, with more in the septal than temporal hippocampus. At PND30 and 60, the size of the hilar Prox1-ir cell population was reduced. Similar numbers of hilar Prox1-expressing cells were observed in PND30 and 60 Swiss Webster mice. Prox1 is usually considered to be a marker of postmitotic GCs. However, many Prox1-ir hilar cells, especially at PND16, were not double-labeled with NeuN, a marker typically found in mature neurons. Most hilar Prox1-positive cells at PND16 co-expressed doublecortin (DCX) and calretinin, markers of immature GCs. Double-labeling with a marker of actively dividing cells, Ki67, was not detected. These results suggest that, surprisingly, a large population of cells in the hilus at PND16 are immature GCs (Type 2b and Type 3 cells). We also asked whether hilar Prox1-ir cell numbers are modifiable. To examine this issue, we conditionally deleted the proapoptotic gene BAX in Nestin-expressing cells at a time when there are numerous immature GCs in the hilus, PND2-8. When these mice were examined at PND60, the numbers of Prox1-ir hilar cells were significantly increased compared to control mice. However, deletion of BAX did not appear to change the proportion that co-expressed NeuN, suggesting that the size of the hilar Prox1-expressing population is modifiable. However, deleting BAX, a major developmental disruption, does not appear to change the proportion that ultimately becomes neurons.

Functional circuits of new neurons in the dentate gyrus

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Carmen eVivar

2013-02-01

Full Text Available The hippocampus is crucial for memory formation. New neurons are added throughout life to the hippocampal dentate gyrus (DG, a brain area considered important for differential storage of similar experiences and contexts. To better understand the functional contribution of adult neurogenesis to pattern separation processes, we recently used a novel synapse specific trans-neuronal tracing approach to identify the (sub cortical inputs to new dentate granule cells. It was observed that newly born neurons receive sequential innervation from structures important for memory function. Initially, septal-hippocampal cells provide input to new neurons, followed after about one month by perirhinal and lateral entorhinal cortex. These cortical areas are deemed relevant to encoding of novel environmental information and may enable pattern separation. Here, we review the developmental time-course and proposed functional relevance of new neurons, within the context of their unique neural circuitry.  

The number of granule cells in rat hippocampus is reduced after chronic mild stress and re-established after chronic escitalopram treatment

DEFF Research Database (Denmark)

Jayatissa, Magdalena N; Bisgaard, Christina; West, Mark J

2008-01-01

mild stress and chronic escitalopram treatment. Furthermore, we investigated which classes of immature granule cells are affected by stress and targeted by escitalopram. Rats were initially exposed to 2weeks of CMS and 4weeks of escitalopram treatment with concurrent exposure to stress. The behavioral...... changes, indicating a decrease in sensitivity to a reward, were assessed in terms of sucrose consumption. We found a significant 22.4% decrease in the total number of granule cells in the stressed rats. This decrease was reversed in the stressed escitalopram treated rats that responded to the treatment......, but not in the rats that did not respond to escitalopram treatment. These changes were not followed by alterations in the volume of the granule cell layer. We also showed a differential regulation of dentate neurons, in different stages of development, by chronic stress and chronic escitalopram treatment. Our study...

Cultured subventricular zone progenitor cells transduced with neurogenin-2 become mature glutamatergic neurons and integrate into the dentate gyrus.

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Xia Chen

Full Text Available We have previously shown that transplantation of immature DCX+/NeuN+/Prox1+ neurons (found in the neonatal DG, but not undifferentiated neuronal progenitor cells (NPCs from ventral subventricular zone (SVZ, results in neuronal maturation in vivo within the dentate niche. Here we investigated whether we could enhance the integration of SVZ NPCs by forced expression of the proneural gene Neurogenin 2 (NEUROG2. NPCs cultured from neonatal GFP-transgenic rat SVZ for 7 days in a non-differentiating medium were transduced with a retrovirus encoding NEUROG2 and DsRed or the DsRed reporter gene alone (control. By 3 days post-transduction, the NEUROG2-transduced cells maintained in culture contained mostly immature neurons (91% DCX+; 76% NeuN+, whereas the control virus-transduced cells remained largely undifferentiated (30% DCX+; <1% NeuN+. At 6 weeks following transplantation into the DG of adult male rats, there were no neurons among the transplanted cells treated with the control virus but the majority of the NEUROG2-transduced DsRed+ SVZ cells became mature neurons (92% NeuN+; DCX-negative. Although the NEUROG2-transduced SVZ cells did not express the dentate granule neuron marker Prox1, most of the NEUROG2-transduced SVZ cells (78% expressed the glutamatergic marker Tbr1, suggesting the acquisition of a glutamatergic phenotype. Moreover, some neurons extended dendrites into the molecular layer, grew axons containing Ankyrin G+ axonal initial segments, and projected into the CA3 region, thus resembling mature DG granule neurons. A proportion of NEUROG2 transduced cells also expressed c-Fos and P-CREB, two markers of neuronal activation. We conclude that NEUROG2-transduction is sufficient to promote neuronal maturation and integration of transplanted NPCs from SVZ into the DG.

Bilateral reorganization of the dentate gyrus in hippocampal sclerosis

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Thom, M; Martinian, L; Catarino, C; Yogarajah, M; Koepp, M J.; Caboclo, L; Sisodiya, S M.

2009-01-01

Background: Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. Methods: Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21–96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. Results: Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. Conclusion: Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon. GLOSSARY AED = antiepileptic drug; CA1p = CA1-predominant hippocampal sclerosis; CHS = classical hippocampal sclerosis; EFG = end folium gliosis; EFS = end folium sclerosis; GCD = granule cell dispersion; GCL = granule cell layer; HS = hippocampal sclerosis; MFS = mossy fiber sprouting; MTLE = mesial temporal lobe epilepsy; NPY = neuropeptide Y; ROI = region of interest; SE = status epilepticus; TLE = temporal lobe epilepsy. PMID:19710404

Seizure frequency correlates with loss of dentate gyrus GABAergic neurons in a mouse model of temporal lobe epilepsy

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Buckmaster, Paul S.; Abrams, Emily; Wen, Xiling

2018-01-01

Epilepsy occurs in one of 26 people. Temporal lobe epilepsy is common and can be difficult to treat effectively. It can develop after brain injuries that damage the hippocampus. Multiple pathophysiological mechanisms involving the hippocampal dentate gyrus have been proposed. This study evaluated a mouse model of temporal lobe epilepsy to test which pathological changes in the dentate gyrus correlate with seizure frequency and help prioritize potential mechanisms for further study. FVB mice (n = 127) that had experienced status epilepticus after systemic treatment with pilocarpine 31–61 days earlier were video-monitored for spontaneous, convulsive seizures 9 hr/day every day for 24–36 days. Over 4,060 seizures were observed. Seizure frequency ranged from an average of one every 3.6 days to one every 2.1 hr. Hippocampal sections were processed for Nissl stain, Prox1-immunocytochemistry, GluR2-immunocytochemistry, Timm stain, glial fibrillary acidic protein-immunocytochemistry, glutamic acid decarboxylase in situ hybridization, and parvalbumin-immunocytochemistry. Stereological methods were used to measure hilar ectopic granule cells, mossy cells, mossy fiber sprouting, astrogliosis, and GABAergic interneurons. Seizure frequency was not significantly correlated with the generation of hilar ectopic granule cells, the number of mossy cells, the extent of mossy fiber sprouting, the extent of astrogliosis, or the number of GABAergic interneurons in the molecular layer or hilus. Seizure frequency significantly correlated with the loss of GABAergic interneurons in or adjacent to the granule cell layer, but not with the loss of parvalbumin-positive interneurons. These findings prioritize the loss of granule cell layer interneurons for further testing as a potential cause of temporal lobe epilepsy. PMID:28425097

Seizure frequency correlates with loss of dentate gyrus GABAergic neurons in a mouse model of temporal lobe epilepsy.

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Buckmaster, Paul S; Abrams, Emily; Wen, Xiling

2017-08-01

Epilepsy occurs in one of 26 people. Temporal lobe epilepsy is common and can be difficult to treat effectively. It can develop after brain injuries that damage the hippocampus. Multiple pathophysiological mechanisms involving the hippocampal dentate gyrus have been proposed. This study evaluated a mouse model of temporal lobe epilepsy to test which pathological changes in the dentate gyrus correlate with seizure frequency and help prioritize potential mechanisms for further study. FVB mice (n = 127) that had experienced status epilepticus after systemic treatment with pilocarpine 31-61 days earlier were video-monitored for spontaneous, convulsive seizures 9 hr/day every day for 24-36 days. Over 4,060 seizures were observed. Seizure frequency ranged from an average of one every 3.6 days to one every 2.1 hr. Hippocampal sections were processed for Nissl stain, Prox1-immunocytochemistry, GluR2-immunocytochemistry, Timm stain, glial fibrillary acidic protein-immunocytochemistry, glutamic acid decarboxylase in situ hybridization, and parvalbumin-immunocytochemistry. Stereological methods were used to measure hilar ectopic granule cells, mossy cells, mossy fiber sprouting, astrogliosis, and GABAergic interneurons. Seizure frequency was not significantly correlated with the generation of hilar ectopic granule cells, the number of mossy cells, the extent of mossy fiber sprouting, the extent of astrogliosis, or the number of GABAergic interneurons in the molecular layer or hilus. Seizure frequency significantly correlated with the loss of GABAergic interneurons in or adjacent to the granule cell layer, but not with the loss of parvalbumin-positive interneurons. These findings prioritize the loss of granule cell layer interneurons for further testing as a potential cause of temporal lobe epilepsy. © 2017 Wiley Periodicals, Inc.

High Plasticity of New Granule Cells in the Aging Hippocampus

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Mariela F. Trinchero

2017-10-01

Full Text Available Summary: During aging, the brain undergoes changes that impair cognitive capacity and circuit plasticity, including a marked decrease in production of adult-born hippocampal neurons. It is unclear whether development and integration of those new neurons are also affected by age. Here, we show that adult-born granule cells (GCs in aging mice are scarce and exhibit slow development, but they display a remarkable potential for structural plasticity. Retrovirally labeled 3-week-old GCs in middle-aged mice were small, underdeveloped, and disconnected. Neuronal development and integration were accelerated by voluntary exercise or environmental enrichment. Similar effects were observed via knockdown of Lrig1, an endogenous negative modulator of neurotrophin receptors. Consistently, blocking neurotrophin signaling by Lrig1 overexpression abolished the positive effects of exercise. These results demonstrate an unparalleled degree of plasticity in the aging brain mediated by neurotrophins, whereby new GCs remain immature until becoming rapidly recruited to the network by activity. : Trinchero et al. show that development of new granule cells born in the adult hippocampus is strongly influenced by age. In the aging hippocampus, new neurons remain immature for prolonged intervals, yet voluntary exercise triggers their rapid growth and functional synaptogenesis. This extensive structural remodeling is mediated by neurotrophins. Keywords: adult neurogenesis, dentate gyrus, functional integration, neurotrophins, synaptogenesis, exercise

Dentate gyrus expression of nestin-immunoreactivity in patients with drug-resistant temporal lobe epilepsy and hippocampal sclerosis.

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D'Alessio, L; Konopka, H; Escobar, E; Acuña, A; Oddo, S; Solís, P; Seoane, E; Kochen, S

2015-04-01

Granule cells pathology in dentate gyrus, have received considerable attention in terms of understanding the pathophysiology of temporal lobe epilepsy with hippocampal sclerosis. The aim of this study was to determine the nestin (an intermediate filament protein expressed by newly formed cells), immunoreactivity (IR) in granular cells layers of hippocampal tissue extirpated during epilepsy surgical procedure, in patients with drug-resistant epilepsy. Hippocampal sections of 16 patients with hippocampal sclerosis and drug-resistant temporal lobe epilepsy were processed using immunoperoxidase with antibody to nestin. Archival material from 8 normal post-mortem hippocampus, were simultaneously processed. Reactive area for nestin-IR, the total number of positive nestin cells per field (20×), and the MGV (mean gray value) was determined by computerized image analysis (ImageJ), and compared between groups. Student's t test was used for statistical analysis. Nestin-IR cells were found in granule cells layers of both controls and patients. Larger reactive somas (p gyrus may reflect changes in dentate gyrus neuroplasticity associated to chronic temporal epilepsy with hippocampal sclerosis. Further studies are required to determine the clinical implications on memory an emotional alterations such as depression. Copyright © 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

The dentate gyrus: fundamental neuroanatomical organization (dentate gyrus for dummies).

OpenAIRE

Amaral David G; Scharfman Helen E; Lavenex Pierre

2007-01-01

The dentate gyrus is a simple cortical region that is an integral portion of the larger functional brain system called the hippocampal formation. In this review, the fundamental neuroanatomical organization of the dentate gyrus is described, including principal cell types and their connectivity, and a summary of the major extrinsic inputs of the dentate gyrus is provided. Together, this information provides essential information that can serve as an introduction to the dentate gyrus — a “dent...

Cdk5 regulates accurate maturation of newborn granule cells in the adult hippocampus.

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Sebastian Jessberger

2008-11-01

Full Text Available Newborn granule cells become functionally integrated into the synaptic circuitry of the adult dentate gyrus after a morphological and electrophysiological maturation process. The molecular mechanisms by which immature neurons and the neurites extending from them find their appropriate position and target area remain largely unknown. Here we show that single-cell-specific knockdown of cyclin-dependent kinase 5 (cdk5 activity in newborn cells using a retrovirus-based strategy leads to aberrant growth of dendritic processes, which is associated with an altered migration pattern of newborn cells. Even though spine formation and maturation are reduced in cdk5-deficient cells, aberrant dendrites form ectopic synapses onto hilar neurons. These observations identify cdk5 to be critically involved in the maturation and dendrite extension of newborn neurons in the course of adult neurogenesis. The data presented here also suggest a mechanistic dissociation between accurate dendritic targeting and subsequent synapse formation.

Somatic Arc protein expression in hippocampal granule cells is increased in response to environmental change but independent of task-specific learning.

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Cleland, J P; Willis, E F; Bartlett, P F; Vukovic, J

2017-09-29

Activated neurons express immediate-early genes, such as Arc. Expression of Arc in the hippocampal granule cell layer, an area crucial for spatial learning and memory, is increased during acquisition of spatial learning; however, it is unclear whether this effect is related to the task-specific learning process or to nonspecific aspects of the testing procedure (e.g. exposure to the testing apparatus and exploration of the environment). Herein, we show that Arc-positive cells numbers are increased to the same extent in the granule cell layer after both acquisition of a single spatial learning event in the active place avoidance task and exploration of the testing environment, as compared to naïve (i.e. caged) mice. Repeated exposure the testing apparatus and environment did not reduce Arc expression. Furthermore, Arc expression did not correlate with performance in both adult and aged animals, suggesting that exploration of the testing environment, rather than the specific acquisition of the active place avoidance task, induces Arc expression in the dentate granule cell layer. These findings thus suggest that Arc is an experience-induced immediate-early gene.

Human iPSC Derived GABA Ergic Precursor Cell Therapy for Chronic Epilepsy

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2016-10-01

of hMGE progenitors (obtained from hPSCs expanded from human embryonic stem cells) that were transduced with DREADDs through CRISPR/Cas9 technology...regions and cell layers of the hippocampus, which include the subgranular zone and the dentate hilus in the dentate gyrus, and strata oriens and...have migrated extensively in the dentate hilus (A3) and into different layers of the CA1 subfield. DG, dentate gyrus; DH, dentate hilus; GCL, granule

Survival of mossy cells of the hippocampal dentate gyrus in humans with mesial temporal lobe epilepsy.

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Seress, László; Abrahám, Hajnalka; Horváth, Zsolt; Dóczi, Tamás; Janszky, József; Klemm, Joyce; Byrne, Richard; Bakay, Roy A E

2009-12-01

Hippocampal sclerosis can be identified in most patients with mesial temporal lobe epilepsy (TLE). Surgical removal of the sclerotic hippocampus is widely performed to treat patients with drug-resistant mesial TLE. In general, both epilepsy-prone and epilepsy-resistant neurons are believed to be in the hippocampal formation. The hilar mossy cells of the hippocampal dentate gyrus are usually considered one of the most vulnerable types of neurons. The aim of this study was to clarify the fate of mossy cells in the hippocampus in epileptic humans. Of the 19 patients included in this study, 15 underwent temporal lobe resection because of drug-resistant TLE. Four patients were used as controls because they harbored tumors that had not invaded the hippocampus and they had experienced no seizures. Histological evaluation of resected hippocampal tissues was performed using immunohistochemistry. Mossy cells were identified in the control as well as the epileptic hippocampi by using cocaine- and amphetamine-regulated transcript peptide immunohistochemistry. In most cases the number of mossy cells was reduced and thorny excrescences were smaller in the epileptic hippocampi than in controls; however, there was a significant loss of pyramidal cells and a partial loss of granule cells in the same epileptic hippocampi in which mossy cell loss was apparent. The loss of mossy cells could be correlated with the extent of hippocampal sclerosis, patient age at seizure onset, duration of epilepsy, and frequency of seizures. In many cases large numbers of mossy cells were present in the hilus of the dentate gyrus when most pyramidal neurons of the CA1 and CA3 areas of the Ammon's horn were lost, suggesting that mossy cells may not be more vulnerable to epileptic seizures than the hippocampal pyramidal neurons.

Progressive behavioral changes during the maturation of rats with early radiation-induced hypoplasia of fascia dentata granule cells

International Nuclear Information System (INIS)

Mickley, G.A.; Ferguson, J.L.; Mulvihill, M.A.; Nemeth, T.J.

1989-01-01

Localized exposure of the neonatal rat brain to X-rays produces neuronal hypoplasia specific to the granule cell layer of the hippocampal dentate gyrus. This brain damage causes locomotor hyperactivity, slowed acquisition of passive avoidance tasks and long bouts of spontaneous turning (without reversals) in a bowl apparatus. Here we report how these behavioral deficits change as a function of subject aging and behavioral test replications. Portions of the neonatal rat cerebral hemispheres were X-irradiated in order to selectively damage the granule cells of the dentate gyrus. The brains of experimental animals received a fractionated dose of X rays (13 Gy total) over postnatal days 1 to 16 and control animals were sham-irradiated. Rats between the ages of 71-462 days were tested 3 separate times on each of the following 3 behavioral tests: (1) spontaneous locomotion, (2) passive avoidance acquisition, and (3) spontaneous circling in a large plastic hemisphere. Rats with radiation-induced damage to the fascia dentata exhibited long bouts of slow turns without reversals. Once they began, irradiated subjects perseverated in turning to an extent significantly greater than sham-irradiated control subjects. This irradiation effect was significant during all test series. Moreover, in time, spontaneous perseverative turning was significantly potentiated in rats with hippocampal damage but increased only slightly in controls. Early radiation exposure produced locomotor hyperactivity in young rats. While activity levels of controls remained fairly stable throughout the course of the experiment, the hyperactivity of the irradiated animals decreased significantly as they matured

A natural form of learning can increase and decrease the survival of new neurons in the dentate gyrus.

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Olariu, Ana; Cleaver, Kathryn M; Shore, Lauren E; Brewer, Michelle D; Cameron, Heather A

2005-01-01

Granule cells born in the adult dentate gyrus undergo a 4-week developmental period characterized by high susceptibility to cell death. Two forms of hippocampus-dependent learning have been shown to rescue many of the new neurons during this critical period. Here, we show that a natural form of associative learning, social transmission of food preference (STFP), can either increase or decrease the survival of young granule cells in adult rats. Increased numbers of pyknotic as well as phospho-Akt-expressing BrdU-labeled cells were seen 1 day after STFP training, indicating that training rapidly induces both cell death and active suppression of cell death in different subsets. A single day of training for STFP increased the survival of 8-day-old BrdU-labeled cells when examined 1 week later. In contrast, 2 days of training decreased the survival of BrdU-labeled cells and the density of immature neurons, identified with crmp-4. This change from increased to decreased survival could not be accounted for by the ages of the cells. Instead, we propose that training may initially increase young granule cell survival, then, if continued, cause them to die. This complex regulation of cell death could potentially serve to maintain granule cells that are actively involved in memory consolidation, while rapidly using and discarding young granule cells whose training is complete to make space for new naïve neurons. Published 2005 Wiley-Liss, Inc.

Analyzing dendritic growth in a population of immature neurons in the adult dentate gyrus using laminar quantification of disjointed dendrites

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Shira eRosenzweig

2011-03-01

Full Text Available In the dentate gyrus of the hippocampus, new granule neurons are continuously produced throughout adult life. A prerequisite for the successful synaptic integration of these neurons is the sprouting and extension of dendrites into the molecular layer of the dentate gyrus. Thus, studies aimed at investigating the developmental stages of adult neurogenesis often use dendritic growth as an important indicator of neuronal health and maturity. Based on the known topography of the dentate gyrus, characterized by distinct laminar arrangement of granule neurons and their extensions, we have developed a new method for analysis of dendritic growth in immature adult-born granule neurons. The method is comprised of laminar quantification of cell bodies, primary, secondary and tertiary dendrites separately and independently from each other. In contrast to most existing methods, laminar quantification of dendrites does not require the use of exogenous markers and does not involve arbitrary selection of individual neurons. The new method relies on immonuhistochemical detection of endogenous markers such as doublecortin to perform a comprehensive analysis of a sub-population of immature neurons. Disjointed, orphan dendrites that often appear in the thin histological sections are taken into account. Using several experimental groups of rats and mice, we demonstrate here the suitable techniques for quantifying neurons and dendrites, and explain how the ratios between the quantified values can be used in a comparative analysis to indicate variations in dendritic growth and complexity.

Properties of doublecortin-(DCX-expressing cells in the piriform cortex compared to the neurogenic dentate gyrus of adult mice.

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Friederike Klempin

Full Text Available The piriform cortex receives input from the olfactory bulb and (via the entorhinal cortex sends efferents to the hippocampus, thereby connecting the two canonical neurogenic regions of the adult rodent brain. Doublecortin (DCX is a cytoskeleton-associated protein that is expressed transiently in the course of adult neurogenesis. Interestingly, the adult piriform cortex, which is usually considered non-neurogenic (even though some reports exist that state otherwise, also contains an abundant population of DCX-positive cells. We asked how similar these cells would be to DCX-positive cells in the course of adult hippocampal neurogenesis. Using BAC-generated transgenic mice that express GFP under the DCX promoter, we studied DCX-expression and electrophysiological properties of DCX-positive cells in the mouse piriform cortex in comparison with the dentate gyrus. While one class of cells in the piriform cortex indeed showed features similar to newly generated immature granule neurons, the majority of DCX cells in the piriform cortex was mature and revealed large Na+ currents and multiple action potentials. Furthermore, when proliferative activity was assessed, we found that all DCX-expressing cells in the piriform cortex were strictly postmitotic, suggesting that no DCX-positive "neuroblasts" exist here as they do in the dentate gyrus. We conclude that DCX in the piriform cortex marks a unique population of postmitotic neurons with a subpopulation that retains immature characteristics associated with synaptic plasticity. DCX is thus, per se, no marker of neurogenesis but might be associated more broadly with plasticity.

Effects of rapamycin treatment after controlled cortical impact injury on neurogenesis and synaptic reorganization in the mouse dentate gyrus

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Corwin R Butler

2015-11-01

Full Text Available Post-traumatic epilepsy (PTE is one consequence of traumatic brain injury (TBI. A prominent cell signaling pathway activated in animal models of both TBI and epilepsy is the mammalian target of rapamycin (mTOR. Inhibition of mTOR with rapamycin has shown promise as a potential modulator of epileptogenesis in several animal models of epilepsy, but cellular mechanisms linking mTOR expression and epileptogenesis are unclear. In this study, the role of mTOR in modifying functional hippocampal circuit reorganization after focal TBI induced by controlled cortical impact was investigated. Rapamycin (3 or 10 mg/kg, an inhibitor of mTOR signaling, was administered by intraperitoneal injection beginning on the day of injury and continued daily until tissue collection. Relative to controls, rapamycin treatment reduced dentate granule cell area in the hemisphere ipsilateral to the injury two weeks post-injury. Brain injury resulted in a significant increase in doublecortin immunolabeling in the dentate gyrus ipsilateral to the injury, indicating increased neurogenesis shortly after TBI. Rapamycin treatment prevented the increase in doublecortin labeling, with no overall effect on Fluoro-Jade B staining in the ipsilateral hemisphere, suggesting that rapamycin treatment reduced posttraumatic neurogenesis but did not prevent cell loss after injury. At later times post-injury (8-13 weeks, evidence of mossy fiber sprouting and increased recurrent excitation of dentate granule cells was detected, which were attenuated by rapamycin treatment. Rapamycin treatment also diminished seizure prevalence relative to vehicle-treated controls after TBI. Collectively, these results support a role for adult neurogenesis in PTE development and suggest that suppression of epileptogenesis by mTOR inhibition includes effects on post-injury neurogenesis.

Long-term potentiation expands information content of hippocampal dentate gyrus synapses.

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Bromer, Cailey; Bartol, Thomas M; Bowden, Jared B; Hubbard, Dusten D; Hanka, Dakota C; Gonzalez, Paola V; Kuwajima, Masaaki; Mendenhall, John M; Parker, Patrick H; Abraham, Wickliffe C; Sejnowski, Terrence J; Harris, Kristen M

2018-03-06

An approach combining signal detection theory and precise 3D reconstructions from serial section electron microscopy (3DEM) was used to investigate synaptic plasticity and information storage capacity at medial perforant path synapses in adult hippocampal dentate gyrus in vivo. Induction of long-term potentiation (LTP) markedly increased the frequencies of both small and large spines measured 30 minutes later. This bidirectional expansion resulted in heterosynaptic counterbalancing of total synaptic area per unit length of granule cell dendrite. Control hemispheres exhibited 6.5 distinct spine sizes for 2.7 bits of storage capacity while LTP resulted in 12.9 distinct spine sizes (3.7 bits). In contrast, control hippocampal CA1 synapses exhibited 4.7 bits with much greater synaptic precision than either control or potentiated dentate gyrus synapses. Thus, synaptic plasticity altered total capacity, yet hippocampal subregions differed dramatically in their synaptic information storage capacity, reflecting their diverse functions and activation histories.

Dentate network activity is necessary for spatial working memory by supporting CA3 sharp-wave ripple generation and prospective firing of CA3 neurons.

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Sasaki, Takuya; Piatti, Verónica C; Hwaun, Ernie; Ahmadi, Siavash; Lisman, John E; Leutgeb, Stefan; Leutgeb, Jill K

2018-02-01

Complex spatial working memory tasks have been shown to require both hippocampal sharp-wave ripple (SWR) activity and dentate gyrus (DG) neuronal activity. We therefore asked whether DG inputs to CA3 contribute to spatial working memory by promoting SWR generation. Recordings from DG and CA3 while rats performed a dentate-dependent working memory task on an eight-arm radial maze revealed that the activity of dentate neurons and the incidence rate of SWRs both increased during reward consumption. We then found reduced reward-related CA3 SWR generation without direct input from dentate granule neurons. Furthermore, CA3 cells with place fields in not-yet-visited arms preferentially fired during SWRs at reward locations, and these prospective CA3 firing patterns were more pronounced for correct trials and were dentate-dependent. These results indicate that coordination of CA3 neuronal activity patterns by DG is necessary for the generation of neuronal firing patterns that support goal-directed behavior and memory.

Effects of TRPV1 activation on synaptic excitation in the dentate gyrus of a mouse model of temporal lobe epilepsy.

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Bhaskaran, Muthu D; Smith, Bret N

2010-06-01

Temporal lobe epilepsy (TLE) is a condition characterized by an imbalance between excitation and inhibition in the temporal lobe. Hallmarks of this change are axon sprouting and accompanying synaptic reorganization in the temporal lobe. Synthetic and endogenous cannabinoids have variable therapeutic potential in treating intractable temporal lobe epilepsy, in part because cannabinoid ligands can bind multiple receptor types. This study utilized in vitro electrophysiological methods to examine the effect of transient receptor potential vanilloid type 1 (TRPV1) activation in dentate gyrus granule cells in a murine model of TLE. Capsaicin, a selective TRPV1 agonist had no measurable effect on overall synaptic input to granule cells in control animals, but significantly enhanced spontaneous and miniature EPSC frequency in mice with TLE. Exogenous application of anandamide, an endogenous cannabinoid that acts at both TRPV1 and cannabinoid type 1 receptors (CB1R), also enhanced glutamate release in the presence of a CB1R antagonist. Anandamide reduced the EPSC frequency when TRPV1 were blocked with capsazepine. Western blot analysis of TRPV1 receptor indicated protein expression was significantly greater in the dentate gyrus of mice with TLE compared with control mice. This study indicates that a prominent cannabinoid agonist can increase excitatory circuit activity in the synaptically reorganized dentate gyrus of mice with TLE by activating TRPV1 receptors, and suggests caution in designing anticonvulsant therapy based on modulating the endocannabinoid system. Copyright (c) 2009 Elsevier Inc. All rights reserved.

Blockade of intracellular Zn2+ signaling in the dentate gyrus erases recognition memory via impairment of maintained LTP.

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Tamano, Haruna; Minamino, Tatsuya; Fujii, Hiroaki; Takada, Shunsuke; Nakamura, Masatoshi; Ando, Masaki; Takeda, Atsushi

2015-08-01

There is no evidence on the precise role of synaptic Zn2+ signaling on the retention and recall of recognition memory. On the basis of the findings that intracellular Zn2+ signaling in the dentate gyrus is required for object recognition, short-term memory, the present study deals with the effect of spatiotemporally blocking Zn2+ signaling in the dentate gyrus after LTP induction and learning. Three-day-maintained LTP was impaired 1 day after injection of clioquinol into the dentate gyrus, which transiently reduced intracellular Zn2+ signaling in the dentate gyrus. The irreversible impairment was rescued not only by co-injection of ZnCl2 , which ameliorated the loss of Zn2+ signaling, but also by pre-injection of Jasplakinolide, a stabilizer of F-actin, prior to clioquinol injection. Simultaneously, 3-day-old space recognition memory was impaired 1 day after injection of clioquinol into the dentate gyrus, but not by pre-injection of Jasplakinolide. Jasplakinolide also rescued both impairments of 3-day-maintained LTP and 3-day-old memory after injection of ZnAF-2DA into the dentate gyrus, which blocked intracellular Zn2+ signaling in the dentate gyrus. The present paper indicates that the blockade and/or loss of intracellular Zn2+ signaling in the dentate gyrus coincidently impair maintained LTP and recognition memory. The mechanism maintaining LTP via intracellular Zn2+ signaling in dentate granule cells, which may be involved in the formation of F-actin, may retain space recognition memory. © 2015 Wiley Periodicals, Inc.

Involvement of over-expressed BMP4 in pentylenetetrazol kindling-induced cell proliferation in the dentate gyrus of adult rats

International Nuclear Information System (INIS)

Yin Jinbo; Ma Yuxin; Yin Qing; Xu Haiwei; An Ning; Liu Shiyong; Fan Xiaotang; Yang Hui

2007-01-01

The dentate gyrus (DG) of the hippocampus is one of a few regions in the adult mammalian brain characterized by ongoing neurogenesis. Proliferation of neural precursors in the granule cell layer of the DG has been identified in pentylenetetrazol (PTZ) kindling epilepsy model, however, little is known about the molecular mechanism. We previously reported that the expression pattern of bone morphogenetic proteins-4 (BMP4) mRNA in the hippocampus was developmentally regulated and mainly localized in the DG of the adult. To explore the role of BMP4 in epileptic activity, we detected BMP4 expression in the DG during PTZ kindling process and explore its correlation with cell proliferation combined with bromodeoxyuridine (BrdU) labeling technique. We found that dynamic changes in BMP4 level and BrdU labeled cells dependent on the kindling stage of PTZ induced seizure-prone state. The number of BMP4 mRNA-positive cells and BrdU labeled cells reached the top level 1 day after PTZ kindled, then declined to base level 2 months later. Furthermore, there was a significant correlation between increased BMP4 mRNA expression and increased number of BrdU labeled cells. After effectively blocked expression of BMP4 with antisense oligodeoxynucleotides(ASODN), the BrdU labeled cells in the dentate gyrus subgranular zone(DG-SGZ) and hilus were significantly decreased 16d after First PTZ injection and 1, 3, 7, 14d after kindled respectively. These findings suggest that increased proliferation in the DG of the hippocampus resulted from kindling epilepsy elicited by PTZ maybe be modulated by BMP4 over-expression

Acute restraint stress decreases c-fos immunoreactivity in hilar mossy cells of the adult dentate gyrus

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Moretto, Jillian N.; Duffy, Áine M.

2017-01-01

Although a great deal of information is available about the circuitry of the mossy cells (MCs) of the dentate gyrus (DG) hilus, their activity in vivo is not clear. The immediate early gene c-fos can be used to gain insight into the activity of MCs in vivo, because c-fos protein expression reflects increased neuronal activity. In prior work, it was identified that control rats that were perfusion-fixed after removal from their home cage exhibited c-fos immunoreactivity (ir) in the DG in a spatially stereotyped pattern: ventral MCs and dorsal granule cells (GCs) expressed c-fos protein (Duffy et al., Hippocampus 23:649–655, 2013). In this study, we hypothesized that restraint stress would alter c-fos-ir, because MCs express glucocorticoid type 2 receptors and the DG is considered to be involved in behaviors related to stress or anxiety. We show that acute restraint using a transparent nose cone for just 10 min led to reduced c-fos-ir in ventral MCs compared to control rats. In these comparisons, c-fos-ir was evaluated 30 min after the 10 min-long period of restraint, and if evaluation was later than 30 min c-fos-ir was no longer suppressed. Granule cells (GCs) also showed suppressed c-fos-ir after acute restraint, but it was different than MCs, because the suppression persisted for over 30 min after the restraint. We conclude that c-fos protein expression is rapidly and transiently reduced in ventral hilar MCs after a brief period of restraint, and suppressed longer in dorsal GCs. PMID:28190104

Aberrant Epigenetic Gene Regulation in GABAergic Interneuron Subpopulations in the Hippocampal Dentate Gyrus of Mouse Offspring Following Developmental Exposure to Hexachlorophene.

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Watanabe, Yousuke; Abe, Hajime; Nakajima, Kota; Ideta-Otsuka, Maky; Igarashi, Katsuhide; Woo, Gye-Hyeong; Yoshida, Toshinori; Shibutani, Makoto

2018-05-01

Maternal hexachlorophene (HCP) exposure causes transient disruption of hippocampal neurogenesis in mouse offspring. We examined epigenetically hypermethylated and downregulated genes related to this HCP-induced disrupted neurogenesis. Mated female mice were dietary exposed to 0 or 100 ppm HCP from gestational day 6 to postnatal day (PND) 21 on weaning. The hippocampal dentate gyrus of male offspring was subjected to methyl-capture sequencing and real-time reverse transcription-polymerase chain reaction analyses on PND 21. Validation analyses on methylation identified three genes, Dlx4, Dmrt1, and Plcb4, showing promoter-region hypermethylation. Immunohistochemically, DLX4+, DMRT1+, and PLCB4+ cells in the dentate hilus co-expressed GAD67, a γ-aminobutyric acid (GABA)ergic neuron marker. HCP decreased all of three subpopulations as well as GAD67+ cells on PND 21. PLCB4+ cells also co-expressed the metabotropic glutamate receptor, GRM1. HCP also decreased transcript level of synaptic plasticity-related genes in the dentate gyrus and immunoreactive granule cells for synaptic plasticity-related ARC. On PND 77, all immunohistochemical cellular density changes were reversed, whereas the transcript expression of the synaptic plasticity-related genes fluctuated. Thus, HCP-exposed offspring transiently reduced the number of GABAergic interneurons. Among them, subpopulations expressing DLX4, DMRT1, or PLCB4 were transiently reduced in number through an epigenetic mechanism. Considering the role of the Dlx gene family in GABAergic interneuron migration and differentiation, the decreased number of DLX4+ cells may be responsible for reducing those GABAergic interneurons regulating neurogenesis. The effect on granule cell synaptic plasticity was sustained until the adult stage, and reduced GABAergic interneurons active in GRM1-PLCB4 signaling may be responsible for the suppression on weaning.

Potassium conductances mediate bidirectional state-dependent modulation of action potential evoked dendritic calcium signals in dentate gyrus granule cells

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János Brunner

2014-03-01

Full Text Available Backpropagating action potentials (bAPs and local calcium signals that they trigger are fundamental for dendritic functions. Here we addressed the question what extent the changes of local dendritic membrane properties can contribute to the shaping of the coupling between dendritic action potentials and the local calcium responses. Using a combination of in vitro electrophysiological and confocal imaging techniques we found that activation of dendritic GIRK channels via mGlu2 or GABAB receptors enhanced the bAP¬-triggered calcium signals in the dendrites of dentate gyrus granule cells (GCs. The enhancement of calcium signals was significant only in those dendritic regions, where these receptors are predominantly expressed. Similarly to GIRK channel activation, somatic hyperpolarization by DC current injection (from -64 mV to -77 mV, significantly increased bAP-associated calcium signals in the proximal dendrites. The hyperpolarization was associated with a decrease in the input resistance due to the rectification of the membrane potential of GCs. The effect of hyperpolarization on the calcium signals was maintained when T-type calcium currents were blocked but it decreased when GIRK channels were inhibited. Simultaneous dual somato-dendritic recordings from GCs showed that somatic hyperpolarization accelerated the repolarization phase of dendritic bAP in the proximal region whereas the rising phase and peak amplitude was not affected. We hypothesize that the larger driving force for calcium ions during the faster repolarization can contribute to the increasing in calcium signals. Employment of previously recorded dendritic bAP waveforms from hyperpolarized membrane potential as voltage command evoked larger calcium currents in nucleated patches compared to bAP waveform from the same recording at depolarized membrane potential. Furthermore, addition of native, high-voltage activated, inactivating potassium conductance by somatic dynamic clamp

Vaccine adjuvants: Tailor-made mast-cell granules

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Gunzer, Matthias

2012-03-01

Mast cells induce protective immune responses through secretion of stimulatory granules. Microparticles modelled after mast-cell granules are now shown to replicate and enhance the functions of their natural counterparts and to direct the character of the resulting immunity.

Dentate Gyrus circuitry features improve performance of sparse approximation algorithms.

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Panagiotis C Petrantonakis

Full Text Available Memory-related activity in the Dentate Gyrus (DG is characterized by sparsity. Memory representations are seen as activated neuronal populations of granule cells, the main encoding cells in DG, which are estimated to engage 2-4% of the total population. This sparsity is assumed to enhance the ability of DG to perform pattern separation, one of the most valuable contributions of DG during memory formation. In this work, we investigate how features of the DG such as its excitatory and inhibitory connectivity diagram can be used to develop theoretical algorithms performing Sparse Approximation, a widely used strategy in the Signal Processing field. Sparse approximation stands for the algorithmic identification of few components from a dictionary that approximate a certain signal. The ability of DG to achieve pattern separation by sparsifing its representations is exploited here to improve the performance of the state of the art sparse approximation algorithm "Iterative Soft Thresholding" (IST by adding new algorithmic features inspired by the DG circuitry. Lateral inhibition of granule cells, either direct or indirect, via mossy cells, is shown to enhance the performance of the IST. Apart from revealing the potential of DG-inspired theoretical algorithms, this work presents new insights regarding the function of particular cell types in the pattern separation task of the DG.

Radial glial cells in the adult dentate gyrus: what are they and where do they come from?

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Berg, Daniel A; Bond, Allison M; Ming, Guo-Li; Song, Hongjun

2018-01-01

Adult neurogenesis occurs in the dentate gyrus in the mammalian hippocampus. These new neurons arise from neural precursor cells named radial glia-like cells, which are situated in the subgranular zone of the dentate gyrus. Here, we review the emerging topic of precursor heterogeneity in the adult subgranular zone. We also discuss how this heterogeneity may be established during development and focus on the embryonic origin of the dentate gyrus and radial glia-like stem cells. Finally, we discuss recently developed single-cell techniques, which we believe will be critical to comprehensively investigate adult neural stem cell origin and heterogeneity.

Sampling the Mouse Hippocampal Dentate Gyrus

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Lisa Basler

2017-12-01

Full Text Available Sampling is a critical step in procedures that generate quantitative morphological data in the neurosciences. Samples need to be representative to allow statistical evaluations, and samples need to deliver a precision that makes statistical evaluations not only possible but also meaningful. Sampling generated variability should, e.g., not be able to hide significant group differences from statistical detection if they are present. Estimators of the coefficient of error (CE have been developed to provide tentative answers to the question if sampling has been “good enough” to provide meaningful statistical outcomes. We tested the performance of the commonly used Gundersen-Jensen CE estimator, using the layers of the mouse hippocampal dentate gyrus as an example (molecular layer, granule cell layer and hilus. We found that this estimator provided useful estimates of the precision that can be expected from samples of different sizes. For all layers, we found that a smoothness factor (m of 0 generally provided better estimates than an m of 1. Only for the combined layers, i.e., the entire dentate gyrus, better CE estimates could be obtained using an m of 1. The orientation of the sections impacted on CE sizes. Frontal (coronal sections are typically most efficient by providing the smallest CEs for a given amount of work. Applying the estimator to 3D-reconstructed layers and using very intense sampling, we observed CE size plots with m = 0 to m = 1 transitions that should also be expected but are not often observed in real section series. The data we present also allows the reader to approximate the sampling intervals in frontal, horizontal or sagittal sections that provide CEs of specified sizes for the layers of the mouse dentate gyrus.

Persistent discharges in dentate gyrus perisoma-inhibiting interneurons require hyperpolarization-activated cyclic nucleotide-gated channel activation.

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Elgueta, Claudio; Köhler, Johannes; Bartos, Marlene

2015-03-11

Parvalbumin (PV)-expressing perisoma-inhibiting interneurons (PIIs) of the dentate gyrus integrate rapidly correlated synaptic inputs and generate short-duration action potentials that propagate along the axon to their output synapses, supporting fast inhibitory signaling onto their target cells. Here we show that PV-PIIs in rat and mouse dentate gyrus (DG) integrate their intrinsic activity over time and can turn into a persistent firing mode characterized by the ability to generate long-lasting trains of action potentials at ∼50 Hz in the absence of additional inputs. Persistent firing emerges in the axons remote from the axon initial segment and markedly depends on hyperpolarization-activated cyclic nucleotide-gated channel (HCNC) activation. Persistent firing properties are modulated by intracellular Ca(2+) levels and somatic membrane potential. Detailed computational single-cell PIIs models reveal that HCNC-mediated conductances can contribute to persistent firing during conditions of a shift in their voltage activation curve to more depolarized potentials. Paired recordings from PIIs and their target granule cells show that persistent firing supports strong inhibitory output signaling. Thus, persistent firing may emerge during conditions of intense activation of the network, thereby providing silencing to the circuitry and the maintenance of sparse activity in the dentate gyrus. Copyright © 2015 the authors 0270-6474/15/354131-09$15.00/0.

UVC-induced stress granules in mammalian cells.

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Mohamed Taha Moutaoufik

Full Text Available Stress granules (SGs are well characterized cytoplasmic RNA bodies that form under various stress conditions. We have observed that exposure of mammalian cells in culture to low doses of UVC induces the formation of discrete cytoplasmic RNA granules that were detected by immunofluorescence staining using antibodies to RNA-binding proteins. UVC-induced cytoplasmic granules are not Processing Bodies (P-bodies and are bone fide SGs as they contain TIA-1, TIA-1/R, Caprin1, FMRP, G3BP1, PABP1, well known markers, and mRNA. Concomitant with the accumulation of the granules in the cytoplasm, cells enter a quiescent state, as they are arrested in G1 phase of the cell cycle in order to repair DNA damages induced by UVC irradiation. This blockage persists as long as the granules are present. A tight correlation between their decay and re-entry into S-phase was observed. However the kinetics of their formation, their low number per cell, their absence of fusion into larger granules, their persistence over 48 hours and their slow decay, all differ from classical SGs induced by arsenite or heat treatment. The induction of these SGs does not correlate with major translation inhibition nor with phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α. We propose that a restricted subset of mRNAs coding for proteins implicated in cell cycling are removed from the translational apparatus and are sequestered in a repressed form in SGs.

Effects of neonatal. gamma. -ray irradiation on rat hippocampus: Pt. 1; Postnatal maturation of hippocampal cells

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Represa, A; Dessi, F; Beaudoin, M; Ben-Ari, Y [Institut National de la Sante et de la Recherche Medicale (INSERM), 75 - Paris (France)

1991-01-01

The axons of dentate granule cells, the mossy fibres, establish synaptic contacts with the thorny excrescences of the apical dendrite of CA3 pyramidal neurons. Dentate granule cells develop postnatally in rats, whereas the CA3 pyramidal cells are generated before birth. In the present studies, using unilateral neonatal {gamma}-ray irradiation to destroy the granule cells in one hemisphere, we have studied the effect of mossy fibre deprivation on the development of their targets. We show that such ''degranulation'' prevents the normal development of giant thorny excrescences, suggesting that the development of thorny excrescences in CA3 pyramidal neurons is under the control of mossy fibres. In contrast, irradiation of the hippocampus of the neonatal rat does not affect the development of the dendritic arborization of CA3 pyramidal cells and their non-mossy dendritic spines. (author).

Platelet granule exocytosis: A comparison with chromaffin cells

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Jennifer eFitch-Tewfik

2013-06-01

Full Text Available The rapid secretion of bioactive amines from chromaffin cells constitutes an important component of the fight or flight response of mammals to stress. Platelets respond to stresses within the vasculature by rapidly secreting cargo at sites of injury, inflammation, or infection. Although chromaffin cells derive from the neural crest and platelets from bone marrow megakaryocytes, both have evolved a heterogeneous assemblage of granule types and a mechanism for efficient release. This article will provide an overview of granule formation and exocytosis in platelets with an emphasis on areas in which the study of chromaffin cells has influenced that of platelets and on similarities between the two secretory systems. Commonalities include the use of transporters to concentrate bioactive amines and other cargos into granules, the role of cytoskeletal remodeling in granule exocytosis, and the use of granules to provide membrane for cytoplasmic projections. The SNAREs and SNARE accessory proteins used by each cell type will also be considered. Finally, we will discuss the newly appreciated role of dynamin family proteins in regulated fusion pore formation. This evaluation of the comparative cell biology of regulated exocytosis in platelets and chromaffin cells demonstrates a convergence of mechanisms between two disparate cell types both tasked with responding rapidly to physiological stimuli.

Norepinephrine induces pathway-specific long-lasting potentiation and depression in the hippocampal dentate gyrus.

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Dahl, D; Sarvey, J M

1989-01-01

The study presented here indicates that norepinephrine (NE) selectively induces long-lasting modifications of synaptically mediated responses in the dentate gyrus of the rat hippocampal slice. A low concentration of NE (1.0 microM; in the presence of 50 microM phentolamine, an alpha-adrenergic antagonist) or a 1.0 microM concentration of the specific beta-adrenergic agonist isoproterenol induced long-lasting pathway-specific alterations of granule cell electrophysiological responses. Excitatory postsynaptic potentials and population spikes evoked by stimulation of the medial perforant pathway (PP) were potentiated for more than 45 min. In contrast, responses to lateral PP stimulation were depressed for the same period. Both potentiation and depression were blocked by the beta-adrenergic antagonist propranolol (1.0 microM). These results indicate that NE can act differentially on projections to the dentate gyrus arising in the entorhinal cortex. Such selective persistent modifications of cortical circuits may be involved in processes in the mammalian brain underlying attention, learning, and memory. PMID:2734319

Distorted secretory granule composition in mast cells with multiple protease deficiency.

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Grujic, Mirjana; Calounova, Gabriela; Eriksson, Inger; Feyerabend, Thorsten; Rodewald, Hans-Reimer; Tchougounova, Elena; Kjellén, Lena; Pejler, Gunnar

2013-10-01

Mast cells are characterized by an abundance of secretory granules densely packed with inflammatory mediators such as bioactive amines, cytokines, serglycin proteoglycans with negatively charged glycosaminoglycan side chains of either heparin or chondroitin sulfate type, and large amounts of positively charged proteases. Despite the large biological impact of mast cell granules and their contents on various pathologies, the mechanisms that regulate granule composition are incompletely understood. In this study, we hypothesized that granule composition is dependent on a dynamic electrostatic interrelationship between different granule compounds. As a tool to evaluate this possibility, we generated mice in which mast cells are multideficient in a panel of positively charged proteases: the chymase mouse mast cell protease-4, the tryptase mouse mast cell protease-6, and carboxypeptidase A3. Through a posttranslational effect, mast cells from these mice additionally lack mouse mast cell protease-5 protein. Mast cells from mice deficient in individual proteases showed normal morphology. In contrast, mast cells with combined protease deficiency displayed a profound distortion of granule integrity, as seen both by conventional morphological criteria and by transmission electron microscopy. An assessment of granule content revealed that the distorted granule integrity in multiprotease-deficient mast cells was associated with a profound reduction of highly negatively charged heparin, whereas no reduction in chondroitin sulfate storage was observed. Taken together with previous findings showing that the storage of basic proteases conversely is regulated by anionic proteoglycans, these data suggest that secretory granule composition in mast cells is dependent on a dynamic interrelationship between granule compounds of opposite electrical charge.

Abnormal ion content, hydration and granule expansion of the secretory granules from cystic fibrosis airway glandular cells

International Nuclear Information System (INIS)

Baconnais, S.; Delavoie, F.; Zahm, J.M.; Milliot, M.; Terryn, C.; Castillon, N.; Banchet, V.; Michel, J.; Danos, O.; Merten, M.; Chinet, T.; Zierold, K.; Bonnet, N.; Puchelle, E.; Balossier, G.

2005-01-01

The absence or decreased expression of cystic fibrosis transmembrane conductance regulator (CFTR) induces increased Na + absorption and hyperabsorption of the airway surface liquid (ASL) resulting in a dehydrated and hyperviscous ASL. Although the implication of abnormal airway submucosal gland function has been suggested, the ion and water content in the Cystic Fibrosis (CF) glandular secretory granules, before exocytosis, is unknown. We analyzed, in non-CF and CF human airway glandular cell lines (MM-39 and KM4, respectively), the ion content in the secretory granules by electron probe X-ray microanalysis and the water content by quantitative dark field imaging on freeze-dried cryosections. We demonstrated that the ion content (Na + , Mg 2+ , P, S and Cl - ) is significantly higher and the water content significantly lower in secretory granules from the CF cell line compared to the non-CF cell line. Using videomicroscopy, we observed that the secretory granule expansion was deficient in CF glandular cells. Transfection of CF cells with CFTR cDNA or inhibition of non-CF cells with CFTR inh -172, respectively restored or decreased the water content and granule expansion, in parallel with changes in ion content. We hypothesize that the decreased water and increased ion content in glandular secretory granules may contribute to the dehydration and increased viscosity of the ASL in CF

Constitutively polarized granules prime KHYG-1 NK cells.

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Suck, Garnet; Branch, Donald R; Aravena, Paola; Mathieson, Mark; Helke, Simone; Keating, Armand

2006-09-01

The major mechanism for NK cell lysis of tumor cells is granule-mediated cytotoxicity. Polarization of granules is a prelude to the release of their cytotoxic contents in response to target-cell binding. We describe the novel observation of constitutive granule polarization in the cytotoxic NK cell line, KHYG-1. Continuous degranulation of KHYG-1 cells, however, does not occur and still requires target-cell contact. Disruption of microtubules with colcemid is sufficient to disperse the granules in KHYG-1 and significantly decreases cytotoxicity. A similar effect is not obtained by inhibiting extracellular signal-related kinase 2 (ERK2), the most distal kinase investigated in the cytolytic pathway. Disruption of microtubules significantly down-regulates activation receptors, NKp44 and NKG2D, implicating them as potential microtubule-trafficking receptors. Such changes in upstream receptor expression may have caused deactivation of ERK2, since NKG2D cross-linking also leads to receptor down-regulation and diminished ERK phosphorylation. Thus, a functional role for NKG2D in KHYG-1 cytotoxicity is demonstrated. Moreover, the novel primed state may contribute to the high cytotoxicity exhibited by KHYG-1.

Morphological Constraints on Cerebellar Granule Cell Combinatorial Diversity.

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Gilmer, Jesse I; Person, Abigail L

2017-12-13

Combinatorial expansion by the cerebellar granule cell layer (GCL) is fundamental to theories of cerebellar contributions to motor control and learning. Granule cells (GrCs) sample approximately four mossy fiber inputs and are thought to form a combinatorial code useful for pattern separation and learning. We constructed a spatially realistic model of the cerebellar GCL and examined how GCL architecture contributes to GrC combinatorial diversity. We found that GrC combinatorial diversity saturates quickly as mossy fiber input diversity increases, and that this saturation is in part a consequence of short dendrites, which limit access to diverse inputs and favor dense sampling of local inputs. This local sampling also produced GrCs that were combinatorially redundant, even when input diversity was extremely high. In addition, we found that mossy fiber clustering, which is a common anatomical pattern, also led to increased redundancy of GrC input combinations. We related this redundancy to hypothesized roles of temporal expansion of GrC information encoding in service of learned timing, and we show that GCL architecture produces GrC populations that support both temporal and combinatorial expansion. Finally, we used novel anatomical measurements from mice of either sex to inform modeling of sparse and filopodia-bearing mossy fibers, finding that these circuit features uniquely contribute to enhancing GrC diversification and redundancy. Our results complement information theoretic studies of granule layer structure and provide insight into the contributions of granule layer anatomical features to afferent mixing. SIGNIFICANCE STATEMENT Cerebellar granule cells are among the simplest neurons, with tiny somata and, on average, just four dendrites. These characteristics, along with their dense organization, inspired influential theoretical work on the granule cell layer as a combinatorial expander, where each granule cell represents a unique combination of inputs

Study of light scattering by a granulated coated sphere - a model of granulated blood cells

NARCIS (Netherlands)

Yurkin, M.A.; de Kanter, D.; Hoekstra, A.G.

2008-01-01

We performed extensive simulations of light scattering by granulated coated sphere model using the discrete dipole approximation and varying model parameters in the ranges of sizes and refractive indices of granulated blood cells. We compared these results with predictions of Maxwell-Garnett

Vanillin and 4-hydroxybenzyl alcohol promotes cell proliferation and neuroblast differentiation in the dentate gyrus of mice via the increase of brain-derived neurotrophic factor and tropomyosin-related kinase B.

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Cho, Jeong-Hwi; Park, Joon Ha; Ahn, Ji Hyeon; Lee, Jae-Chul; Hwang, In Koo; Park, Seung Min; Ahn, Ji Yun; Kim, Dong Won; Cho, Jun Hwi; Kim, Jong-Dai; Kim, Young-Myeong; Won, Moo-Ho; Kang, Il-Jun

2016-04-01

4-Hydroxy‑3-methoxybenzaldehyde (vanillin) and 4-hydroxybenzyl alcohol (4-HBA) are well‑known phenolic compounds, which possess various therapeutic properties and are widely found in a variety of plants. In the present study, the effects of vanillin and 4‑HBA were first investigated on cell proliferation, as well as neuronal differentiation and integration of granule cells in the dentate gyrus (DG) of adolescent mice using Ki‑67, doublecortin (DCX) immunohistochemistry and 5‑bromo‑2'‑deoxyuridine (BrdU)/feminizing Locus on X 3 (NeuN) double immunofluorescence. In both the vanillin and 4‑HBA groups, the number of Ki‑67+ cells, DCX+ neuroblasts and BrdU+/NeuN+ neurons were significantly increased in the subgranular zone of the DG, as compared with the vehicle group. In addition, the levels of brain‑derived neurotrophic factor (BDNF) and tropomyosin‑related kinase B (TrkB), a BDNF receptor, were significantly increased in the DG in the vanillin and 4‑HBA groups compared with the vehicle group. These results indicated that vanillin and 4‑HBA enhanced cell proliferation, neuroblast differentiation and integration of granule cells in the DG of adolescent mice . These neurogenic effects of vanillin and 4‑HBA may be closely associated with increases in BDNF and TrkB.

Biochemical and microscopic evidence for the internalization and degradation of heparin-containing mast cell granules by bovine endothelial cells

International Nuclear Information System (INIS)

Atkins, F.M.; Friedman, M.M.; Metcalfe, D.D.

1985-01-01

Incubation of [ 35 S]heparin-containing mast cell granules with cultured bovine endothelial cells was followed by the appearance of 35 S-granule-associated radioactivity within the endothelial cells and a decrease in radioactivity in the extracellular fluid. These changes occurred during the first 24 hours of incubation and suggested ingestion of the mast cell granules by the endothelial cells. Periodic electron microscopic examination of the monolayers confirmed this hypothesis by demonstrating apposition of the granules to the plasmalemma of endothelial cells, which was followed by the engulfment of the granules by cytoplasmic projections. Under light microscopic examination, mast cell granules within endothelial cells then appeared to undergo degradation. The degradation of [ 35 S]heparin in mast cell granules was demonstrated by a decrease in the amount of intracellular [ 35 S]heparin proteoglycan after 24 hours and the appearance of free [ 35 S]sulfate in the extracellular compartment. Intact endothelial cells were more efficient at degrading [ 35 S]heparin than were cell lysates or cell supernatants. These data provide evidence of the ability of endothelial cells to ingest mast cell granules and degrade native heparin that is presented as a part of the mast cell granule

Competition from newborn granule cells does not drive axonal retraction of silenced old granule cells in the adult hippocampus

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Carla M Lopez

2012-11-01

Full Text Available In the developing nervous system synaptic refinement, typified by the neuromuscular junction where supernumerary connections are eliminated by axon retraction leaving the postsynaptic target innervated by a single dominant input, critically regulates neuronal circuit formation. Whether such competition based pruning continues in established circuits of mature animals remains unknown. This question is particularly relevant in the context of adult neurogenesis where newborn cells must integrate into preexisting circuits, and thus, potentially compete with functionally mature synapses to gain access to their postsynaptic targets. The hippocampus plays an important role in memory formation/retrieval and the dentate gyrus subfield (DG exhibits continued neurogenesis into adulthood. Therefore, this region contains both mature granule cells (old GCs and immature recently born GCs that are generated throughout adult life (young GCs, providing a neurogenic niche model to examine the role of competition in synaptic refinement. Recent work from an independent group in developing animals indicated that embryonically/early postnatal generated GCs placed at a competitive disadvantage by selective expression of tetanus toxin (TeTX to prevent synaptic release rapidly retracted their axons, and that this retraction was driven by competition from newborn GCs lacking TeTX. In contrast, following 3-6 months of selective TeTX expression in old GCs of adult mice we did not observe any evidence of axon retraction. Indeed ultrastructural analyses indicated that the terminals of silenced GCs even maintained synaptic contact with their postsynaptic targets. Furthermore, we did not detect any significant differences in the electrophysiological properties between old GCs in control and TeTX conditions. Thus, our data demonstrate a remarkable stability in the face of a relatively prolonged period of altered synaptic competition between two populations of neurons within the

Qualitative analysis neurons in the adult human dentate nucleus

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Marić Dušica

2012-01-01

Full Text Available Although many relevant findings regarding to the morphology and cytoarchitectural development of the dentate nucleus have been presented so far, very little qualitative information has been collected on neuronal morphology in the adult human dentate nucleus. The neurons were labelled by Golgi staining from thirty human cerebella, obtained from medico-legal forensic autopsies of adult human bodies and free of significant brain pathology. The human dentate neurons were qualitatively analyzed and these cells were classified into two main classes: the small and the large multipolar neurons. Considering the shape of the cell body, number of the primary dendrites, shape of the dendritic tree and their position within the dentate nucleus, three subclasses of the large multipolar neurons have been recognized. The classification of neurons from the human dentate nucleus has been qualitatively confirmed in fetuses and premature infants. This study represents the first qualitative analysis and classification of the large multipolar neurons in the dentate nucleus of the adult human.

Oxytocin Depolarizes Fast-Spiking Hilar Interneurons and Induces GABA Release onto Mossy Cells of the Rat Dentate Gyrus

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Harden, Scott W.; Frazier, Charles J.

2016-01-01

Delivery of exogenous oxytocin (OXT) to central oxytocin receptors (OXT-Rs) is currently being investigated as a potential treatment for conditions such as post-traumatic stress disorder (PTSD), depression, social anxiety, and autism spectrum disorder (ASD). Despite significant research implicating central OXT signaling in modulation of mood, affect, social behavior, and stress response, relatively little is known about the cellular and synaptic mechanisms underlying these complex actions, particularly in brain regions which express the OXT-R but lie outside of the hypothalamus (where OXT-synthesizing neurons reside). We report that bath application of low concentrations of the selective OXT-R agonist Thr4,Gly7-OXT (TGOT) reliably and robustly drives GABA release in the dentate gyrus in an action potential dependent manner. Additional experiments led to identification of a small subset of small hilar interneurons that are directly depolarized by acute application of TGOT. From a physiological perspective, TGOT-responsive hilar interneurons have high input resistance, rapid repolarization velocity during an action potential, and a robust afterhyperpolarization. Further, they fire irregularly (or stutter) in response to moderate depolarization, and fire quickly with minimal spike frequency accommodation in response to large current injections. From an anatomical perspective, TGOT responsive hilar interneurons have dense axonal arborizations in the hilus that were found close proximity with mossy cell somata and/or proximal dendrites, and also invade the granule cell layer. Further, they have primary dendrites that always extend into the granule cell layer, and sometimes have clear arborizations in the molecular layer. Overall, these data reveal a novel site of action for OXT in an important limbic circuit, and represent a significant step towards better understanding how endogenous OXT may modulate flow of information in hippocampal networks. PMID:27068005

Ethanol extract of Oenanthe javanica increases cell proliferation and neuroblast differentiation in the adolescent rat dentate gyrus

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Bai Hui Chen

2015-01-01

Full Text Available Oenanthe javanica is an aquatic perennial herb that belongs to the Oenanthe genus in Apiaceae family, and it displays well-known medicinal properties such as protective effects against glutamate-induced neurotoxicity. However, few studies regarding effects of Oenanthe javanica on neurogenesis in the brain have been reported. In this study, we examined the effects of a normal diet and a diet containing ethanol extract of Oenanthe javanica on cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus of adolescent rats using Ki-67 (an endogenous marker for cell proliferation and doublecortin (a marker for neuroblast. Our results showed that Oenanthe javanica extract significantly increased the number of Ki-67-immunoreactive cells and doublecortin-immunoreactive neuroblasts in the subgranular zone of the dentate gyrus in the adolescent rats. In addition, the immunoreactivity of brain-derived neurotrophic factor was significantly increased in the dentate gyrus of the Oenanthe javanica extract-treated group compared with the control group. However, we did not find that vascular endothelial growth factor expression was increased in the Oenanthe javanica extract-treated group compared with the control group. These results indicate that Oenanthe javanica extract improves cell proliferation and neuroblast differentiation by increasing brain-derived neurotrophic factor immunoreactivity in the rat dentate gyrus.

Mossy cells in epilepsy: rigor mortis or vigor mortis?

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Ratzliff, Annad d H; Santhakumar, Vijayalakshmi; Howard, Allyson; Soltesz, Ivan

2002-03-01

Mossy cells are bi-directionally connected through a positive feedback loop to granule cells, the principal cells of the dentate gyrus. This recurrent circuit is strategically placed between the entorhinal cortex and the hippocampal CA3 region. In spite of their potentially pro-convulsive arrangement with granule cells, mossy cells have not been seriously considered to promote seizures, because mossy cells, allegedly one of the most vulnerable cell types in the entire mammalian brain, have long been 'known' to die en masse in epilepsy. However, new data suggest that rumors of the rapid demise of the mossy cells might have been greatly exaggerated.

Radial glial cells in the adult dentate gyrus: what are they and where do they come from? [version 1; referees: 2 approved

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Daniel A. Berg

2018-03-01

Full Text Available Adult neurogenesis occurs in the dentate gyrus in the mammalian hippocampus. These new neurons arise from neural precursor cells named radial glia-like cells, which are situated in the subgranular zone of the dentate gyrus. Here, we review the emerging topic of precursor heterogeneity in the adult subgranular zone. We also discuss how this heterogeneity may be established during development and focus on the embryonic origin of the dentate gyrus and radial glia-like stem cells. Finally, we discuss recently developed single-cell techniques, which we believe will be critical to comprehensively investigate adult neural stem cell origin and heterogeneity.

PlexinA2 Forward Signaling through Rap1 GTPases Regulates Dentate Gyrus Development and Schizophrenia-like Behaviors

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Xiao-Feng Zhao

2018-01-01

Full Text Available Summary: Dentate gyrus (DG development requires specification of granule cell (GC progenitors in the hippocampal neuroepithelium, as well as their proliferation and migration into the primordial DG. We identify the Plexin family members Plxna2 and Plxna4 as important regulators of DG development. Distribution of immature GCs is regulated by Sema5A signaling through PlxnA2 and requires a functional PlxnA2 GTPase-activating protein (GAP domain and Rap1 small GTPases. In adult Plxna2−/− but not Plxna2-GAP-deficient mice, the dentate GC layer is severely malformed, neurogenesis is compromised, and mossy fibers form aberrant synaptic boutons within CA3. Behavioral studies with Plxna2−/− mice revealed deficits in associative learning, sociability, and sensorimotor gating—traits commonly observed in neuropsychiatric disorder. Remarkably, while morphological defects are minimal in Plxna2-GAP-deficient brains, defects in fear memory and sensorimotor gating persist. Since allelic variants of human PLXNA2 and RAP1 associate with schizophrenia, our studies identify a biochemical pathway important for brain development and mental health. : Zhao et al. find that Sema5A-PlexinA2 forward signaling through Rap1 GTPases is required for progenitor distribution in the developing mouse dentate gyrus. Adult Plxna2−/−, but not Plxna2-GAP-deficient, mice show defects in dentate morphology, neurogenesis, and mossy fiber connectivity. Plxna2−/− and Plxna2-GAP mice exhibit behavioral defects suggestive of neuropsychiatric illness. Keywords: PlexinA2, semaphoring, Rap1, GAP, dentate gyrus, adult neurogenesis, mossy fiber, fear memory, sensorimotor gating, schizophrenia

Control over the morphology and segregation of Zebrafish germ cell granules during embryonic development

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Nakkrasae La-Iad

2008-05-01

Full Text Available Abstract Background Zebrafish germ cells contain granular-like structures, organized around the cell nucleus. These structures share common features with polar granules in Drosophila, germinal granules in Xenopus and chromatoid bodies in mice germ cells, such as the localization of the zebrafish Vasa, Piwi and Nanos proteins, among others. Little is known about the structure of these granules as well as their segregation in mitosis during early germ-cell development. Results Using transgenic fish expressing a fluorescently labeled novel component of Zebrafish germ cell granules termed Granulito, we followed the morphology and distribution of the granules. We show that whereas these granules initially exhibit a wide size variation, by the end of the first day of development they become a homogeneous population of medium size granules. We investigated this resizing event and demonstrated the role of microtubules and the minus-end microtubule dependent motor protein Dynein in the process. Last, we show that the function of the germ cell granule resident protein the Tudor domain containing protein-7 (Tdrd7 is required for determination of granule morphology and number. Conclusion Our results suggest that Zebrafish germ cell granules undergo a transformation process, which involves germ cell specific proteins as well as the microtubular network.

Acute ethanol exposure inhibits silencing of cerebellar Golgi cell firing induced by granule cell axon input

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Paolo eBotta

2014-02-01

Full Text Available Golgi cells (GoCs are specialized interneurons that provide inhibitory input to granule cells in the cerebellar cortex. GoCs are pacemaker neurons that spontaneously fire action potentials, triggering spontaneous inhibitory postsynaptic currents in granule cells and also contributing to the generation tonic GABAA receptor-mediated currents in granule cells. In turn, granule cell axons provide feedback glutamatergic input to GoCs. It has been shown that high frequency stimulation of granule cell axons induces a transient pause in GoC firing in a type 2-metabotropic glutamate receptor (mGluR2-dependent manner. Here, we investigated the effect ethanol on the pause of GoC firing induced by high frequency stimulation of granule cell axons. GoC electrophysiological recordings were performed in parasagittal cerebellar vermis slices from postnatal day 23 to 26 rats. Loose-patch cell-attached recordings revealed that ethanol (40 mM reversibly decreases the pause duration. An antagonist of mGluR2 reduced the pause duration but did not affect the effect of ethanol. Whole-cell voltage-clamp recordings showed that currents evoked by an mGluR2 agonist were not significantly affected by ethanol. Perforated-patch experiments in which hyperpolarizing and depolarizing currents were injected into GoCs demonstrated that there is an inverse relationship between spontaneous firing and pause duration. Slight inhibition of the Na+/K+ pump mimicked the effect of ethanol on pause duration. In conclusion, ethanol reduces the granule cell axon-mediated feedback mechanism by reducing the input responsiveness of GoCs. This would result in a transient increase of GABAA receptor-mediated inhibition of granule cells, limiting information flow at the input stage of the cerebellar cortex.

Prenatal alcohol exposure affects progenitor cell numbers in olfactory bulbs and dentate gyrus of vervet monkeys

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Burke, Mark W; Inyatkin, Alexey; Ptito, Maurice

2016-01-01

vervet monkey (Chlorocebus sabeus) to (1) investigate the normal developmental sequence of post-natal proliferation in the olfactory bulb and dentate gyrus and (2) determine the effects of naturalistic prenatal ethanol exposure on proliferation at three different ages (neonate, five months and two years......). Using design-based stereology, we found an age-related decrease of actively proliferating cells in the olfactory bulb and dentate gyrus for both control and FAE groups. Furthermore, at the neonatal time point, the FAE group had fewer actively proliferating cells as compared to the control group...

Plasticity of hippocampal stem/progenitor cells to enhance neurogenesis in response to kainate-induced injury is lost by middle age

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Hattiangady, Bharathi; Rao, Muddanna S.; Shetty, Ashok K.

2008-01-01

A remarkable up-regulation of neurogenesis through increased proliferation of neural stem/progenitor cells (NSCs) is a well-known plasticity displayed by the young dentate gyrus (DG) following brain injury. To ascertain whether this plasticity is preserved during aging, we quantified DG neurogenesis in the young adult, middle-aged and aged F344 rats after kainic acid induced hippocampal injury. Measurement of new cells that are added to the dentate granule cell layer (GCL) between post-injury...

High pressure and [Ca2+] produce an inverse modulation of synaptic input strength, network excitability and frequency response in the rat dentate gyrus

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Thomas I Talpalar

2016-09-01

Full Text Available Hyperbaric environments induce the high pressure neurological syndrome (HPNS characterized by hyperexcitability of the central nervous system and memory impairment. Human divers and other animals experience the HPNS at pressures beyond 1.1 MPa. High pressure depresses synaptic transmission and alters its dynamics in various animal models. Medial perforant path (MPP synapses connecting the medial entorhinal cortex with the hippocampal formation are suppressed by 50% at 10.1MPa. Reduction of synaptic inputs is paradoxically associated with enhanced ability of dentate gyrus’ granule cells to generate spikes at high pressure. This mechanism allows MPP inputs to elicit standard granule cell outputs at 0.1 -25 Hz frequencies under hyperbaric conditions. An increased postsynaptic gain of MPP inputs probably allows diving animals to perform in hyperbaric environments, but makes them vulnerable to high intensity/frequency stimuli producing hyperexcitability. Increasing extracellular Ca2+ (Ca2+o partially reverted pressure-mediated depression of MPP inputs and increased MPP’s low-pass filter properties. We postulated that raising Ca2+o in addition to increase synaptic inputs may reduce network excitability in the dentate gyrus potentially improving its function and reducing sensitivity to high intensity and pathologic stimuli. For this matter, we activated the MPP with single and 50 Hz frequency stimuli that simulated physiologic and deleterious conditions, while assessing the granule cell’s output under various conditions of pressure and Ca2+o. Our results reveal that pressure and Ca2+o produce an inverse modulation on synaptic input strength and network excitability. These coincident phenomena suggest a potential general mechanism of networks that adjusts gain as an inverse function of synaptic inputs’ strength. Such mechanism may serve for adaptation to variable pressure and other physiological and pathological conditions and may explain the

Probing α4βδ GABAA Receptor Heterogeneity

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Hoestgaard-Jensen, Kirsten; Dalby, Nils Ole; Krall, Jacob

2014-01-01

in cerebellar granule cells. In contrast, the compound did not elicit significant currents in dentate gyrus granule cells or in striatal medium spiny neurons (MSNs), indicating predominant expression of extrasynaptic α4β2δ receptors in these cells. Interestingly, Thio-THIP evoked differential degrees...... recorded from dentate gyrus granule cells, most likely by targeting perisynaptic α4βδ receptors expressed at distal dendrites of these cells. Being the first published ligand capable of discriminating between β2- and β3-containing receptor subtypes, Thio-THIP could be a valuable tool in explorations...

Contribution of constitutively proliferating precursor cell subtypes to dentate neurogenesis after cortical infarcts

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Oberland Julia

2010-11-01

Full Text Available Abstract Background It is well known that focal ischemia increases neurogenesis in the adult dentate gyrus of the hippocampal formation but the cellular mechanisms underlying this proliferative response are only poorly understood. We here investigated whether precursor cells which constitutively proliferate before the ischemic infarct contribute to post-ischemic neurogenesis. To this purpose, transgenic mice expressing green fluorescent protein (GFP under the control of the nestin promoter received repetitive injections of the proliferation marker bromodeoxyuridine (BrdU prior to induction of cortical infarcts. We then immunocytochemically analyzed the fate of these BrdU-positive precursor cell subtypes from day 4 to day 28 after the lesion. Results Quantification of BrdU-expressing precursor cell populations revealed no alteration in number of radial glia-like type 1 cells but a sequential increase of later precursor cell subtypes in lesioned animals (type 2a cells at day 7, type 3 cells/immature neurons at day 14. These alterations result in an enhanced survival of mature neurons 4 weeks postinfarct. Conclusions Focal cortical infarcts recruit dentate precursor cells generated already before the infarct and significantly contribute to an enhanced neurogenesis. Our findings thereby increase our understanding of the complex cellular mechanisms of postlesional neurogenesis.

Olfactory granule cell development in normal and hyperthyroid rats.

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Brunjes, P C; Schwark, H D; Greenough, W T

1982-10-01

Dendritic development was examined in olfactory bulbs of both normal 7-, 14-, 21- and 60-day-old rats and littermates treated on postnatal days 1-4 with 1 microgram/g body weight of L-thyroxine sodium. Tissue was processed via the Golgi-Cox technique and subjected to quantitative analyses of mitral and internal layer granule cell development. These populations of granule cells were selected because their pattern of late proliferation suggested potentially greater susceptibility to postnatal hormonal alterations. Although neonatal hyperthyroidism induces widespread acceleration of maturation, including precocious chemosensitivity, granule cell development was unaffected relative to littermate controls. Both normal and hyperthyroid groups exhibited an inverted U-shaped pattern of cellular development, with rapid dendritic dendritic growth and expansion occurring during the earliest ages tested, but with loss of processes and dendritic field size occurring after day 21.

Neurogenesis in the septal and temporal part of the adult rat dentate gyrus.

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Bekiari, Chryssa; Giannakopoulou, Aggeliki; Siskos, Nikistratos; Grivas, Ioannis; Tsingotjidou, Anastasia; Michaloudi, Helen; Papadopoulos, Georgios C

2015-04-01

Structural and functional dissociation between the septal and the temporal part of the dentate gyrus predispose for possible differentiations in the ongoing neurogenesis process of the adult hippocampus. In this study, BrdU-dated subpopulations of the rat septal and temporal dentate gyrus (coexpressing GFAP, DCX, NeuN, calretinin, calbindin, S100, caspase-3 or fractin) were quantified comparatively at 2, 5, 7, 14, 21, and 30 days after BrdU administration in order to examine the successive time-frames of the neurogenesis process, the glial or neuronal commitment of newborn cells and the occurring apoptotic cell death. Newborn neurons' migration from the neurogenic subgranular zone to the inner granular cell layer and expression of glutamate NMDA and AMPA receptors were also studied. BrdU immunocytochemistry revealed comparatively higher numbers of BrdU(+) cells in the septal part, but stereological analysis of newborn and total granule cells showed an identical ratio in the two parts, indicating an equivalent neurogenic ability, and a common topographical pattern along each part's longitudinal and transverse axis. Similarly, both parts exhibited extremely low levels of newborn glial and apoptotic cells. However, despite the initially equal division rate and pattern of the septal and temporal proliferating cells, their later proliferative profile diverged in the two parts. Dynamic differences in the differentiation, migration and maturation process of the two BrdU-incorporating subpopulations of newborn neurons were also detected, along with differences in their survival pattern. Therefore, we propose that various factors, including developmental date birth, local DG microenvironment and distinct functionality of the two parts may be the critical regulators of the ongoing neurogenesis process, leading the septal part to a continuous, rapid, and less-disciplined genesis rate, whereas the quiescent temporal microenvironment preserves a quite steady, less

A Voltage-Based STDP Rule Combined with Fast BCM-Like Metaplasticity Accounts for LTP and Concurrent "Heterosynaptic" LTD in the Dentate Gyrus In Vivo.

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Peter Jedlicka

2015-11-01

Full Text Available Long-term potentiation (LTP and long-term depression (LTD are widely accepted to be synaptic mechanisms involved in learning and memory. It remains uncertain, however, which particular activity rules are utilized by hippocampal neurons to induce LTP and LTD in behaving animals. Recent experiments in the dentate gyrus of freely moving rats revealed an unexpected pattern of LTP and LTD from high-frequency perforant path stimulation. While 400 Hz theta-burst stimulation (400-TBS and 400 Hz delta-burst stimulation (400-DBS elicited substantial LTP of the tetanized medial path input and, concurrently, LTD of the non-tetanized lateral path input, 100 Hz theta-burst stimulation (100-TBS, a normally efficient LTP protocol for in vitro preparations produced only weak LTP and concurrent LTD. Here we show in a biophysically realistic compartmental granule cell model that this pattern of results can be accounted for by a voltage-based spike-timing-dependent plasticity (STDP rule combined with a relatively fast Bienenstock-Cooper-Munro (BCM-like homeostatic metaplasticity rule, all on a background of ongoing spontaneous activity in the input fibers. Our results suggest that, at least for dentate granule cells, the interplay of STDP-BCM plasticity rules and ongoing pre- and postsynaptic background activity determines not only the degree of input-specific LTP elicited by various plasticity-inducing protocols, but also the degree of associated LTD in neighboring non-tetanized inputs, as generated by the ongoing constitutive activity at these synapses.

Effects of butternut squash extract on dentate gyrus cell proliferation and spatial learning in male adult rats

Institute of Scientific and Technical Information of China (English)

Mohsen Marzban; Sara Soleimani Asl; Hassan Fallah Huseini; Mahdi Tondar; Samira Choopani; Mehdi Mehdizadeh

2011-01-01

Previous studies reported that some plants, including butternut squash, exert positive effects on the brain. However, few studies have examined the effects of butternut squash on learning, memory, and neurogenesis. This study studied the effects of butternut squash extract on spatial learning and cell proliferation in the dentate gyrus of healthy male rats. Thirty-five male Wistar rats were intrap-eritoneally injected with 0, 50, 100, 200 and 400 mg/kg butternut squash extract once daily for 2 months. After the last administration, rat's spatial memory was studied using the Morris water maze. Finally, rats were sacrificed and hippocampal sections were prepared for light microscopy and bromodeoxyuridine immunohistochemistry studies. The results revealed that escape latency and swim distance decreased in all treatment groups compared with the control rats, and that the number of bromodeoxyuridine-positive cells in the dentate gyrus was significantly increased in the treatment groups compared with the controls. These findings suggest that butternut squash extract improves the learning and memory abilities of male rats, and increases the proliferation of dentate gyrus cells.

Prenatal Alcohol Exposure Affects Progenitor Cell Numbers in Olfactory Bulbs and Dentate Gyrus of Vervet Monkeys

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Mark W. Burke

2016-10-01

Full Text Available Fetal alcohol exposure (FAE alters hippocampal cell numbers in rodents and primates, and this may be due, in part, to a reduction in the number or migration of neuronal progenitor cells. The olfactory bulb exhibits substantial postnatal cellular proliferation and a rapid turnover of newly formed cells in the rostral migratory pathway, while production and migration of postnatal neurons into the dentate gyrus may be more complex. The relatively small size of the olfactory bulb, compared to the hippocampus, potentially makes this structure ideal for a rapid analysis. This study used the St. Kitts vervet monkey (Chlorocebus sabeus to (1 investigate the normal developmental sequence of post-natal proliferation in the olfactory bulb and dentate gyrus and (2 determine the effects of naturalistic prenatal ethanol exposure on proliferation at three different ages (neonate, five months and two years. Using design-based stereology, we found an age-related decrease of actively proliferating cells in the olfactory bulb and dentate gyrus for both control and FAE groups. Furthermore, at the neonatal time point, the FAE group had fewer actively proliferating cells as compared to the control group. These data are unique with respect to fetal ethanol effects on progenitor proliferation in the primate brain and suggest that the olfactory bulb may be a useful structure for studies of cellular proliferation.

BTG1 is required to maintain the pool of stem and progenitor cells of dentate gyrus and subventricular zone

OpenAIRE

Stefano eFarioli-Vecchioli; Laura eMicheli; Daniele eSaraulli; Manuela eCeccarelli; Sara eCannas; Raffaella eScardigli; Luca eLeonardi; Irene eCinà; Marco eCostanzi; Maria Teresa eCiotti; Pedro eMoreira; Jean-Pierre eRouault; Vincenzo eCestari; Felice eTirone

2012-01-01

Btg1 belongs to a family of cell cycle inhibitory genes. We observed that Btg1 is highly expressed in adult neurogenic niches, i.e., the dentate gyrus and subventricular zone (SVZ). Thus, we generated Btg1 knockout mice to analyze the role of Btg1 in the process of generation of adult new neurons.Ablation of Btg1 causes a transient increase of the proliferating dentate gyrus stem and progenitor cells at post-natal day 7; however, at two months of age the number of these proliferating cells, a...

GABA-independent GABAA Receptor Openings Maintain Tonic Currents

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Wlodarczyk, Agnieszka I.; Sylantyev, Sergiy; Herd, Murray B.; Kersanté, Flavie; Lambert, Jeremy J.; Rusakov, Dmitri A.; Linthorst, Astrid C.E.; Semyanov, Alexey; Belelli, Delia; Pavlov, Ivan; Walker, Matthew C.

2013-01-01

Activation of GABAA receptors (GABAARs) produces two forms of inhibition: ‘phasic’ inhibition generated by the rapid, transient activation of synaptic GABAARs by presynaptic GABA release, and tonic inhibition generated by the persistent activation of peri- or extrasynaptic GABAARs which can detect extracellular GABA. Such tonic GABAAR-mediated currents are particularly evident in dentate granule cells in which they play a major role in regulating cell excitability. Here we show that in rat dentate granule cells in ex-vivo hippocampal slices, tonic currents are predominantly generated by GABA-independent GABAA receptor openings. This tonic GABAAR conductance is resistant to the competitive GABAAR antagonist SR95531, which at high concentrations acts as a partial agonist, but can be blocked by an open channel blocker picrotoxin. When slices are perfused with 200 nM GABA, a concentration that is comparable to cerebrospinal fluid concentrations but is twice that measured by us in the hippocampus in vivo using zero-net-flux microdialysis, negligible GABA is detected by dentate granule cells. Spontaneously opening GABAARs, therefore, maintain dentate granule cell tonic currents in the face of low extracellular GABA concentrations. PMID:23447601

Somatostatin-positive interneurons in the dentate gyrus of mice provide local- and long-range septal synaptic inhibition.

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Yuan, Mei; Meyer, Thomas; Benkowitz, Christoph; Savanthrapadian, Shakuntala; Ansel-Bollepalli, Laura; Foggetti, Angelica; Wulff, Peer; Alcami, Pepe; Elgueta, Claudio; Bartos, Marlene

2017-04-03

Somatostatin-expressing-interneurons (SOMIs) in the dentate gyrus (DG) control formation of granule cell (GC) assemblies during memory acquisition. Hilar-perforant-path-associated interneurons (HIPP cells) have been considered to be synonymous for DG-SOMIs. Deviating from this assumption, we show two functionally contrasting DG-SOMI-types. The classical feedback-inhibitory HIPPs distribute axon fibers in the molecular layer. They are engaged by converging GC-inputs and provide dendritic inhibition to the DG circuitry. In contrast, SOMIs with axon in the hilus, termed hilar interneurons (HILs), provide perisomatic inhibition onto GABAergic cells in the DG and project to the medial septum. Repetitive activation of glutamatergic inputs onto HIPP cells induces long-lasting-depression (LTD) of synaptic transmission but long-term-potentiation (LTP) of synaptic signals in HIL cells. Thus, LTD in HIPPs may assist flow of spatial information from the entorhinal cortex to the DG, whereas LTP in HILs may facilitate the temporal coordination of GCs with activity patterns governed by the medial septum.

Cellular Functions of the Autism Risk Factor PTCHD1 in Mice.

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Tora, David; Gomez, Andrea M; Michaud, Jean-Francois; Yam, Patricia T; Charron, Frédéric; Scheiffele, Peter

2017-12-06

The gene patched domain containing 1 ( PTCHD1 ) is mutated in patients with autism spectrum disorders and intellectual disabilities and has been hypothesized to contribute to Sonic hedgehog (Shh) signaling and synapse formation. We identify a panel of Ptchd1-interacting proteins that include postsynaptic density proteins and the retromer complex, revealing a link to critical regulators of dendritic and postsynaptic trafficking. Ptchd1 knock-out (KO) male mice exhibit cognitive alterations, including defects in a novel object recognition task. To test whether Ptchd1 is required for Shh-dependent signaling, we examined two Shh-dependent cell populations that express high levels of Ptchd1 mRNA: cerebellar granule cell precursors and dentate granule cells in the hippocampus. We found that proliferation of these neuronal precursors was not altered significantly in Ptchd1 KO male mice. We used whole-cell electrophysiology and anatomical methods to assess synaptic function in Ptchd1-deficient dentate granule cells. In the absence of Ptchd1, we observed profound disruption in excitatory/inhibitory balance despite normal dendritic spine density on dentate granule cells. These findings support a critical role of the Ptchd1 protein in the dentate gyrus, but indicate that it is not required for structural synapse formation in dentate granule cells or for Shh-dependent neuronal precursor proliferation. SIGNIFICANCE STATEMENT The mechanisms underlying neuronal and cellular alterations resulting from patched domain containing 1 ( Ptchd1 ) gene mutations are unknown. The results from this study support an association with dendritic trafficking complexes of Ptchd1. Loss-of-function experiments do not support a role in sonic hedgehog-dependent signaling, but reveal a disruption of synaptic transmission in the mouse dentate gyrus. The findings will help to guide ongoing efforts to understand the etiology of neurodevelopmental disorders arising from Ptchd1 deficiency. Copyright �

Morphometry of Hilar Ectopic Granule Cells in the Rat

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Pierce, Joseph P.; McCloskey, Daniel P.; Scharfman, Helen E.

2014-01-01

Granule cell (GC) neurogenesis in the dentate gyrus (DG) does not always proceed normally. After severe seizures (e.g., status epilepticus [SE]) and some other conditions, newborn GCs appear in the hilus. Hilar ectopic GCs (EGCs) can potentially provide insight into the effects of abnormal location and seizures on GC development. Additionally, hilar EGCs that develop after SE may contribute to epileptogenesis and cognitive impairments that follow SE. Thus, it is critical to understand how EGCs differ from normal GCs. Relatively little morphometric information is available on EGCs, especially those restricted to the hilus. This study quantitatively analyzed the structural morphology of hilar EGCs from adult male rats several months after pilocarpineinduced SE, when they are considered to have chronic epilepsy. Hilar EGCs were physiologically identified in slices, intracellularly labeled, processed for light microscopic reconstruction, and compared to GC layer GCs, from both the same post-SE tissue and the NeuroMorpho database (normal GCs). Consistently, hilar EGC and GC layer GCs had similar dendritic lengths and field sizes, and identifiable apical dendrites. However, hilar EGC dendrites were topologically more complex, with more branch points and tortuous dendritic paths. Three-dimensional analysis revealed that, remarkably, hilar EGC dendrites often extended along the longitudinal DG axis, suggesting increased capacity for septotemporal integration. Axonal reconstruction demonstrated that hilar EGCs contributed to mossy fiber sprouting. This combination of preserved and aberrant morphological features, potentially supporting convergent afferent input to EGCs and broad, divergent efferent output, could help explain why the hilar EGC population could impair DG function. PMID:21344409

Neurogenesis in temporal lobe epilepsy: relationship between histological findings and changes in dentate gyrus proliferative properties.

Science.gov (United States)

Marucci, Gianluca; Giulioni, Marco; Rubboli, Guido; Paradisi, Michela; Fernández, Mercedes; Del Vecchio, Giovanna; Pozzati, Eugenio

2013-02-01

The relationship between hippocampal histopathological abnormalities, epileptogenesis and neurogenesis remains rather unclear. Tissue samples including the subgranular zone of dentate gyrus (DG) were freshly collected for tissue culture for neurospheres generation in 16 patients who underwent surgery for drug-resistant temporal lobe epilepsy. Remaining tissues were histologically examined to assess the presence of mesial temporal sclerosis (MTS) and focal cortical dysplasia. MTS was detected in 8 cases. Neurospheres were formed in 10/16 cases. Only three out of these 10 cases exhibited MTS; on the contrary 5/6 cases lacking neurosphere proliferation presented MTS. There was a significant correlation between presence of MTS and absence of proliferation (p = 0.0389). We also observed a correlation between history of febrile seizures (FS) and presence of MTS (p = 0.0004) and among the 6 cases lacking neurosphere proliferation, 4 cases (66.6%) had experienced prolonged FS. Among "proliferating" cases the percentage of granular cells pathology (GCP) was lower (20% vs 50%) compared to "non proliferating" cases. A decreased potential to generate neurosphere from the SGZ is related to MTS and to alterations of dentate gyrus granule cells, especially in MTS type 1b and GCP type 1. These histological findings may have different prognostic implications, regarding seizure and neuropsychological outcome, compared to patients with other epileptogenic lesions (such as FCD, glioneuronal tumours, vascular lesions). Copyright © 2012 Elsevier B.V. All rights reserved.

Formation of tRNA granules in the nucleus of heat-induced human cells

International Nuclear Information System (INIS)

Miyagawa, Ryu; Mizuno, Rie; Watanabe, Kazunori; Ijiri, Kenichi

2012-01-01

Highlights: ► tRNAs are tranlocated into the nucleus in heat-induced HeLa cells. ► tRNAs form the unique granules in the nucleus. ► tRNA ganules overlap with nuclear stress granules. -- Abstract: The stress response, which can trigger various physiological phenomena, is important for living organisms. For instance, a number of stress-induced granules such as P-body and stress granule have been identified. These granules are formed in the cytoplasm under stress conditions and are associated with translational inhibition and mRNA decay. In the nucleus, there is a focus named nuclear stress body (nSB) that distinguishes these structures from cytoplasmic stress granules. Many splicing factors and long non-coding RNA species localize in nSBs as a result of stress. Indeed, tRNAs respond to several kinds of stress such as heat, oxidation or starvation. Although nuclear accumulation of tRNAs occurs in starved Saccharomyces cerevisiae, this phenomenon is not found in mammalian cells. We observed that initiator tRNA Met (Meti) is actively translocated into the nucleus of human cells under heat stress. During this study, we identified unique granules of Meti that overlapped with nSBs. Similarly, elongator tRNA Met was translocated into the nucleus and formed granules during heat stress. Formation of tRNA granules is closely related to the translocation ratio. Then, all tRNAs may form the specific granules.

Formation of tRNA granules in the nucleus of heat-induced human cells

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Miyagawa, Ryu [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Biological Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan); Mizuno, Rie [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Watanabe, Kazunori, E-mail: watanabe@ric.u-tokyo.ac.jp [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Ijiri, Kenichi [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Biological Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

2012-02-03

Highlights: Black-Right-Pointing-Pointer tRNAs are tranlocated into the nucleus in heat-induced HeLa cells. Black-Right-Pointing-Pointer tRNAs form the unique granules in the nucleus. Black-Right-Pointing-Pointer tRNA ganules overlap with nuclear stress granules. -- Abstract: The stress response, which can trigger various physiological phenomena, is important for living organisms. For instance, a number of stress-induced granules such as P-body and stress granule have been identified. These granules are formed in the cytoplasm under stress conditions and are associated with translational inhibition and mRNA decay. In the nucleus, there is a focus named nuclear stress body (nSB) that distinguishes these structures from cytoplasmic stress granules. Many splicing factors and long non-coding RNA species localize in nSBs as a result of stress. Indeed, tRNAs respond to several kinds of stress such as heat, oxidation or starvation. Although nuclear accumulation of tRNAs occurs in starved Saccharomyces cerevisiae, this phenomenon is not found in mammalian cells. We observed that initiator tRNA{sup Met} (Meti) is actively translocated into the nucleus of human cells under heat stress. During this study, we identified unique granules of Meti that overlapped with nSBs. Similarly, elongator tRNA{sup Met} was translocated into the nucleus and formed granules during heat stress. Formation of tRNA granules is closely related to the translocation ratio. Then, all tRNAs may form the specific granules.

The Prohormone VGF Regulates β Cell Function via Insulin Secretory Granule Biogenesis

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Samuel B. Stephens

2017-09-01

Full Text Available The prohormone VGF is expressed in neuroendocrine and endocrine tissues and regulates nutrient and energy status both centrally and peripherally. We and others have shown that VGF-derived peptides have direct action on the islet β cell as secretagogues and cytoprotective agents; however, the endogenous function of VGF in the β cell has not been described. Here, we demonstrate that VGF regulates secretory granule formation. VGF loss-of-function studies in both isolated islets and conditional knockout mice reveal a profound decrease in stimulus-coupled insulin secretion. Moreover, VGF is necessary to facilitate efficient exit of granule cargo from the trans-Golgi network and proinsulin processing. It also functions to replenish insulin granule stores following nutrient stimulation. Our data support a model in which VGF operates at a critical node of granule biogenesis in the islet β cell to coordinate insulin biosynthesis with β cell secretory capacity.

Measurement of the internal pH of mast cell granules using microvolumetric fluorescence and isotopic techniques

International Nuclear Information System (INIS)

De Young, M.B.; Nemeth, E.F.; Scarpa, A.

1987-01-01

The intragranular pH of isolated mast cell granules was measured. Because of the minute amounts of isolated granules available, two techniques were developed by modifying aminoacridine fluorescence and [ 14 C]methylamine accumulation techniques to permit measurements with microliter sample volumes. Granule purity was demonstrated by electron microscopy, ruthenium red exclusion, and biochemical (histamine, mast cell granule protease) analysis. The internal pH was determined to be 5.55 +/- 0.06, indicating that the pH environment within mast cell granules is not significantly different from that of previously studied granule types (i.e., chromaffin, platelet, pancreatic islet, and pituitary granules). Collapse of the pH gradient by NH+4 was demonstrated with both techniques. No evidence of Cl-/OH- or specific cation/H+ transport was found, and major chloride permeability could not be unequivocably demonstrated. Ca 2+ and Cl- at concentrations normally present extracellularly destabilized granules in the presence of NH+4, but this phenomenon does not necessarily indicate a role for these ions in the exocytotic release of granule contents from intact cells. The pH measurement techniques developed for investigating the properties of granules in mast cells may be useful for studying other granules that can be obtained only in limited quantities

Btg1 is Required to Maintain the Pool of Stem and Progenitor Cells of the Dentate Gyrus and Subventricular Zone

Science.gov (United States)

Farioli-Vecchioli, Stefano; Micheli, Laura; Saraulli, Daniele; Ceccarelli, Manuela; Cannas, Sara; Scardigli, Raffaella; Leonardi, Luca; Cinà, Irene; Costanzi, Marco; Ciotti, Maria Teresa; Moreira, Pedro; Rouault, Jean-Pierre; Cestari, Vincenzo; Tirone, Felice

2012-01-01

Btg1 belongs to a family of cell cycle inhibitory genes. We observed that Btg1 is highly expressed in adult neurogenic niches, i.e., the dentate gyrus and subventricular zone (SVZ). Thus, we generated Btg1 knockout mice to analyze the role of Btg1 in the process of generation of adult new neurons. Ablation of Btg1 causes a transient increase of the proliferating dentate gyrus stem and progenitor cells at post-natal day 7; however, at 2 months of age the number of these proliferating cells, as well as of mature neurons, greatly decreases compared to wild-type controls. Remarkably, adult dentate gyrus stem and progenitor cells of Btg1-null mice exit the cell cycle after completing the S phase, express p53 and p21 at high levels and undergo apoptosis within 5 days. In the SVZ of adult (two-month-old) Btg1-null mice we observed an equivalent decrease, associated to apoptosis, of stem cells, neuroblasts, and neurons; furthermore, neurospheres derived from SVZ stem cells showed an age-dependent decrease of the self-renewal and expansion capacity. We conclude that ablation of Btg1 reduces the pool of dividing adult stem and progenitor cells in the dentate gyrus and SVZ by decreasing their proliferative capacity and inducing apoptosis, probably reflecting impairment of the control of the cell cycle transition from G1 to S phase. As a result, the ability of Btg1-null mice to discriminate among overlapping contextual memories was affected. Btg1 appears, therefore, to be required for maintaining adult stem and progenitor cells quiescence and self-renewal. PMID:22969701

Btg1 is Required to Maintain the Pool of Stem and Progenitor Cells of the Dentate Gyrus and Subventricular Zone

OpenAIRE

Farioli-Vecchioli, Stefano; Micheli, Laura; Saraulli, Daniele; Ceccarelli, Manuela; Cannas, Sara; Scardigli, Raffaella; Leonardi, Luca; Cinà, Irene; Costanzi, Marco; Ciotti, Maria Teresa; Moreira, Pedro; Rouault, Jean-Pierre; Cestari, Vincenzo; Tirone, Felice

2012-01-01

Btg1 belongs to a family of cell cycle inhibitory genes. We observed that Btg1 is highly expressed in adult neurogenic niches, i.e., the dentate gyrus and subventricular zone (SVZ). Thus, we generated Btg1 knockout mice to analyze the role of Btg1 in the process of generation of adult new neurons. Ablation of Btg1 causes a transient increase of the proliferating dentate gyrus stem and progenitor cells at post-natal day 7; however, at 2 months of age the number of these proliferating cells, as...

Turnover of pigment granules: cyclic catabolism and anabolism of ommochromes within epidermal cells.

Science.gov (United States)

Insausti, T C; Casas, J

2009-12-01

Ommochromes are end products of the tryptophan metabolism in arthropods. While the anabolism of ommochromes has been well studied, the catabolism is totally unknown. In order to study it, we used the crab-spider Misumena vatia, which is able to change color reversibly in a few days, from yellow to white and back. Ommochromes is the only pigment class responsible for the body coloration in this animal. The aim of this study was to analyze the fine structure of the epidermal cells in bleaching spiders, in an attempt to correlate morphological changes with the fate of the pigment granules. Central to the process of bleaching is the lysis of the ommochrome granules. In the same cell, intact granules and granules in different degradation stages are found. The degradation begins with granule autolysis. Some components are extruded in the extracellular space and others are recycled via autophagy. Abundant glycogen appears associated to granulolysis. In a later stage of bleaching, ommochrome progranules, typical of white spiders, appear in the distal zone of the same epidermal cell. Catabolism and anabolism of pigment granules thus take place simultaneously in spider epidermal cells. A cyclic pathway of pigment granules formation and degradation, throughout a complete cycle of color change is proposed, together with an explanation for this turnover, involving photoprotection against UV by ommochromes metabolites. The presence of this turnover for melanins is discussed.

Selection of distinct populations of dentate granule cells in response to inputs as a mechanism for pattern separation in mice

OpenAIRE

Deng, Wei; Mayford, Mark; Gage, Fred H

2013-01-01

eLife digest Being able to keep memories of similar events separate in your mind is an essential part of remembering. If you use the same carpark every day, recalling where you left your car this morning is challenging, not because you have to remember an event from long ago, but because you have to distinguish between many similar memories. Keeping memories distinct is one of the functions of a subregion of the hippocampus called the dentate gyrus. The process of taking complex memories and ...

Neurons of the dentate molecular layer in the rabbit hippocampus.

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Francisco J Sancho-Bielsa

Full Text Available The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals' life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow and biocytin injections, eight neuronal morphological types have been detected in the molecular layer of developing adult and old rabbits. Six of them appear as interneurons displaying smooth dendrites and GABA immunoreactivity: those here called as globoid, vertical, small horizontal, large horizontal, inverted pyramidal and polymorphic. Additionally there are two GABA negative types: the sarmentous and ectopic granular neurons. The distribution of the somata and dendritic trees of these neurons shows preferences for a definite sublayer of the molecular layer: small horizontal, sarmentous and inverted pyramidal neurons are preferably found in the outer third of the molecular layer; vertical, globoid and polymorph neurons locate the intermediate third, while large horizontal and ectopic granular neurons occupy the inner third or the juxtagranular molecular layer. Our results reveal substantial differences in the morphology and electrophysiological behaviour between each neuronal archetype in the dentate molecular layer, allowing us to propose a new classification for this neural population.

Synaptic reorganization of inhibitory hilar interneuron circuitry after traumatic brain injury in mice

Science.gov (United States)

Hunt, Robert F.; Scheff, Stephen W.; Smith, Bret N.

2011-01-01

Functional plasticity of synaptic networks in the dentate gyrus has been implicated in the development of posttraumatic epilepsy and in cognitive dysfunction after traumatic brain injury, but little is known about potentially pathogenic changes in inhibitory circuits. We examined synaptic inhibition of dentate granule cells and excitability of surviving GABAergic hilar interneurons 8–13 weeks after cortical contusion brain injury in transgenic mice that express enhanced green fluorescent protein in a subpopulation of inhibitory neurons. Whole-cell voltage-clamp recordings in granule cells revealed a reduction in spontaneous and miniature IPSC frequency after head injury; no concurrent change in paired-pulse ratio was found in granule cells after paired electrical stimulation of the hilus. Despite reduced inhibitory input to granule cells, action potential and EPSC frequencies were increased in hilar GABA neurons from slices ipsilateral to the injury, versus those from control or contralateral slices. Further, increased excitatory synaptic activity was detected in hilar GABA neurons ipsilateral to the injury after glutamate photostimulation of either the granule cell or CA3 pyramidal cell layers. Together, these findings suggest that excitatory drive to surviving hilar GABA neurons is enhanced by convergent input from both pyramidal and granule cells, but synaptic inhibition of granule cells is not fully restored after injury. This rewiring of circuitry regulating hilar inhibitory neurons may reflect an important compensatory mechanism, but it may also contribute to network destabilization by increasing the relative impact of surviving individual interneurons in controlling granule cell excitability in the posttraumatic dentate gyrus. PMID:21543618

Sleep loss disrupts Arc expression in dentate gyrus neurons.

Science.gov (United States)

Delorme, James E; Kodoth, Varna; Aton, Sara J

2018-04-07

Sleep loss affects many aspects of cognition, and memory consolidation processes occurring in the hippocampus seem particularly vulnerable to sleep loss. The immediate-early gene Arc plays an essential role in both synaptic plasticity and memory formation, and its expression is altered by sleep. Here, using a variety of techniques, we have characterized the effects of brief (3-h) periods of sleep vs. sleep deprivation (SD) on the expression of Arc mRNA and Arc protein in the mouse hippocampus and cortex. By comparing the relative abundance of mature Arc mRNA with unspliced pre-mRNA, we see evidence that during SD, increases in Arc across the cortex, but not hippocampus, reflect de novo transcription. Arc increases in the hippocampus during SD are not accompanied by changes in pre-mRNA levels, suggesting that increases in mRNA stability, not transcription, drives this change. Using in situ hybridization (together with behavioral observation to quantify sleep amounts), we find that in the dorsal hippocampus, SD minimally affects Arc mRNA expression, and decreases the number of dentate gyrus (DG) granule cells expressing Arc. This is in contrast to neighboring cortical areas, which show large increases in neuronal Arc expression after SD. Using immunohistochemistry, we find that Arc protein expression is also differentially affected in the cortex and DG with SD - while larger numbers of cortical neurons are Arc+, fewer DG granule cells are Arc+, relative to the same regions in sleeping mice. These data suggest that with regard to expression of plasticity-regulating genes, sleep (and SD) can have differential effects in hippocampal and cortical areas. This may provide a clue regarding the susceptibility of performance on hippocampus-dependent tasks to deficits following even brief periods of sleep loss. Copyright © 2018. Published by Elsevier Inc.

Sequestration of highly expressed mRNAs in cytoplasmic granules, P-bodies, and stress granules enhances cell viability.

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Anna Lavut

Full Text Available Transcriptome analyses indicate that a core 10%-15% of the yeast genome is modulated by a variety of different stresses. However, not all the induced genes undergo translation, and null mutants of many induced genes do not show elevated sensitivity to the particular stress. Elucidation of the RNA lifecycle reveals accumulation of non-translating mRNAs in cytoplasmic granules, P-bodies, and stress granules for future regulation. P-bodies contain enzymes for mRNA degradation; under stress conditions mRNAs may be transferred to stress granules for storage and return to translation. Protein degradation by the ubiquitin-proteasome system is elevated by stress; and here we analyzed the steady state levels, decay, and subcellular localization of the mRNA of the gene encoding the F-box protein, UFO1, that is induced by stress. Using the MS2L mRNA reporter system UFO1 mRNA was observed in granules that colocalized with P-bodies and stress granules. These P-bodies stored diverse mRNAs. Granules of two mRNAs transported prior to translation, ASH1-MS2L and OXA1-MS2L, docked with P-bodies. HSP12 mRNA that gave rise to highly elevated protein levels was not observed in granules under these stress conditions. ecd3, pat1 double mutants that are defective in P-body formation were sensitive to mRNAs expressed ectopically from strong promoters. These highly expressed mRNAs showed elevated translation compared with wild-type cells, and the viability of the mutants was strongly reduced. ecd3, pat1 mutants also exhibited increased sensitivity to different stresses. Our interpretation is that sequestration of highly expressed mRNAs in P-bodies is essential for viability. Storage of mRNAs for future regulation may contribute to the discrepancy between the steady state levels of many stress-induced mRNAs and their proteins. Sorting of mRNAs for future translation or decay by individual cells could generate potentially different phenotypes in a genetically identical

Stimulation of mast cells leads to cholesterol accumulation in macrophages in vitro by a mast cell granule-mediated uptake of low density lipoprotein

International Nuclear Information System (INIS)

Kokkonen, J.O.; Kovanen, P.T.

1987-01-01

The uptake of low density lipoprotein (LDL) by cultured mouse macrophages was markedly promoted by isolated rat mast cell granules present in the culture medium. The granule-mediated uptake of 125 I-LDL enhanced the rate of cholesteryl ester synthesis in the macrophages, the result being accumulation of cholesteryl esters in these cells. Binding of LDL to the granules was essential for the granule-mediated uptake of LDL by macrophages, for the uptake process was prevented by treating the granules with avidin or protamine chloride or by treating LDL with 1,2-cyclohexanedione, all of which inhibit the binding of LDL to the granules. Inhibition of granule phagocytosis by the macrophages with cytochalasin B also abolished the granule-mediated uptake of LDL. Finally, mouse macrophage monolayers and LDL were incubated in the presence of isolated rat serosal mast cells. Stimulation of the mast cells with compound 48/80, a degranulating agent, resulted in dose-dependent release of secretory granules from the mast cells and a parallel increase in 14 C cholesteryl ester synthesis in the macrophages. The results show that, in this in vitro model, the sequence of events leading to accumulation of cholesteryl esters in macrophages involves initial stimulation of mast cells, subsequent release of their secretory granules, binding of LDL to the exocytosed granules, and, finally, phagocytosis of the LDL-containing granules by macrophages

Evidence for evoked release of adenosine and glutamate from cultured cerebellar granule cells

International Nuclear Information System (INIS)

Schousboe, A.; Frandsen, A.; Drejer, J.

1989-01-01

Evoked release of [ 3 H]-D-aspartate which labels the neurotransmitter glutamate pool in cultured cerebellar granule cells was compared with evoked release of adenosine from similar cultures. It was found that both adenosine and [3H]-D-aspartate could be released from the neurons in a calcium dependent manner after depolarization of the cells with either 10-100 microM glutamate or 50 mM KCl. Cultures of cerebellar granule cells treated with 50 microM kainate to eliminate GABAergic neurons behaved in the same way. This together with the observation that cultured astrocytes did not exhibit a calcium dependent, potassium stimulated adenosine release strongly suggest that cerebellar granule cells release adenosine in a neurotransmitter-like fashion together with glutamate which is the classical neurotransmitter of these neurons. Studies of the metabolism of adenosine showed that in the granule cells adenosine is rapidly metabolized to ATP, ADP, and AMP, but in spite of this, adenosine was found to be released preferential to ATP

MicroRNAs Promote Granule Cell Expansion in the Cerebellum Through Gli2.

Science.gov (United States)

Constantin, Lena; Wainwright, Brandon J

2015-12-01

MicroRNAs (miRNAs) are important regulators of cerebellar function and homeostasis. Their deregulation results in cerebellar neuronal degeneration and spinocerebellar ataxia type 1 and contributes to medulloblastoma. Canonical miRNA processing involves Dicer, which cleaves precursor miRNAs into mature double-stranded RNA duplexes. In order to address the role of miRNAs in cerebellar granule cell precursor development, loxP-flanked exons of Dicer1 were conditionally inactivated using the granule cell precursor-specific Atoh1-Cre recombinase. A reduction of 87% in Dicer1 transcript was achieved in this conditional Dicer knockdown model. Although knockdown resulted in normal survival, mice had disruptions to the cortical layering of the anterior cerebellum, which resulted from the premature differentiation of granule cell precursors in this region during neonatal development. This defect manifested as a thinner external granular layer with ectopic mature granule cells, and a depleted internal granular layer. We found that expression of the activator components of the Hedgehog-Patched pathway, the Gli family of transcription factors, was perturbed in conditional Dicer knockdown mice. We propose that loss of Gli2 mRNA mediated the anterior-restricted defect in conditional Dicer knockdown mice and, as proof of principle, were able to show that miR-106b positively regulated Gli2 mRNA expression. These findings confirm the importance of miRNAs as positive mediators of Hedgehog-Patched signalling during granule cell precursor development.

N-methyl-D-aspartate promotes the survival of cerebellar granule cells in culture

DEFF Research Database (Denmark)

Balázs, R; Jørgensen, Ole Steen; Hack, N

1988-01-01

Our previous studies on the survival-promoting influence of elevated concentrations of extracellular K+ ([K+]e) on cultured cerebellar granule cells led to the proposal that depolarization in vitro mimics the effect of the earliest afferent inputs received by the granule cells in vivo. This, in t...

Cuprizone decreases intermediate and late-stage progenitor cells in hippocampal neurogenesis of rats in a framework of 28-day oral dose toxicity study

International Nuclear Information System (INIS)

Abe, Hajime; Tanaka, Takeshi; Kimura, Masayuki; Mizukami, Sayaka; Saito, Fumiyo; Imatanaka, Nobuya; Akahori, Yumi; Yoshida, Toshinori; Shibutani, Makoto

2015-01-01

Developmental exposure to cuprizone (CPZ), a demyelinating agent, impairs intermediate-stage neurogenesis in the hippocampal dentate gyrus of rat offspring. To investigate the possibility of alterations in adult neurogenesis following postpubertal exposure to CPZ in a framework of general toxicity studies, CPZ was orally administered to 5-week-old male rats at 0, 120, or 600 mg/kg body weight/day for 28 days. In the subgranular zone (SGZ), 600 mg/kg CPZ increased the number of cleaved caspase-3 + apoptotic cells. At ≥ 120 mg/kg, the number of SGZ cells immunoreactive for TBR2, doublecortin, or PCNA was decreased, while that for SOX2 was increased. In the granule cell layer, CPZ at ≥ 120 mg/kg decreased the number of postmitotic granule cells immunoreactive for NEUN, CHRNA7, ARC or FOS. In the dentate hilus, CPZ at ≥ 120 mg/kg decreased phosphorylated TRKB + interneurons, although the number of reelin + interneurons was unchanged. At 600 mg/kg, mRNA levels of Bdnf and Chrna7 were decreased, while those of Casp4, Casp12 and Trib3 were increased in the dentate gyrus. These data suggest that CPZ in a scheme of 28-day toxicity study causes endoplasmic reticulum stress-mediated apoptosis of granule cell lineages, resulting in aberrations of intermediate neurogenesis and late-stage neurogenesis and following suppression of immediate early gene-mediated neuronal plasticity. Suppression of BDNF signals to interneurons caused by decreased cholinergic signaling may play a role in these effects of CPZ. The effects of postpubertal CPZ on neurogenesis were similar to those observed with developmental exposure, except for the lack of reelin response, which may contribute to a greater decrease in SGZ cells. - Highlights: • Effect of 28-day CPZ exposure on hippocampal neurogenesis was examined in rats. • CPZ suppressed intermediate neurogenesis and late-stage neurogenesis in the dentate gyrus. • CPZ suppressed BDNF signals to interneurons by decrease of cholinergic

Cuprizone decreases intermediate and late-stage progenitor cells in hippocampal neurogenesis of rats in a framework of 28-day oral dose toxicity study

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Abe, Hajime; Tanaka, Takeshi; Kimura, Masayuki; Mizukami, Sayaka [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193 (Japan); Saito, Fumiyo; Imatanaka, Nobuya; Akahori, Yumi [Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004 (Japan); Yoshida, Toshinori [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Shibutani, Makoto, E-mail: mshibuta@cc.tuat.ac.jp [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan)

2015-09-15

Developmental exposure to cuprizone (CPZ), a demyelinating agent, impairs intermediate-stage neurogenesis in the hippocampal dentate gyrus of rat offspring. To investigate the possibility of alterations in adult neurogenesis following postpubertal exposure to CPZ in a framework of general toxicity studies, CPZ was orally administered to 5-week-old male rats at 0, 120, or 600 mg/kg body weight/day for 28 days. In the subgranular zone (SGZ), 600 mg/kg CPZ increased the number of cleaved caspase-3{sup +} apoptotic cells. At ≥ 120 mg/kg, the number of SGZ cells immunoreactive for TBR2, doublecortin, or PCNA was decreased, while that for SOX2 was increased. In the granule cell layer, CPZ at ≥ 120 mg/kg decreased the number of postmitotic granule cells immunoreactive for NEUN, CHRNA7, ARC or FOS. In the dentate hilus, CPZ at ≥ 120 mg/kg decreased phosphorylated TRKB{sup +} interneurons, although the number of reelin{sup +} interneurons was unchanged. At 600 mg/kg, mRNA levels of Bdnf and Chrna7 were decreased, while those of Casp4, Casp12 and Trib3 were increased in the dentate gyrus. These data suggest that CPZ in a scheme of 28-day toxicity study causes endoplasmic reticulum stress-mediated apoptosis of granule cell lineages, resulting in aberrations of intermediate neurogenesis and late-stage neurogenesis and following suppression of immediate early gene-mediated neuronal plasticity. Suppression of BDNF signals to interneurons caused by decreased cholinergic signaling may play a role in these effects of CPZ. The effects of postpubertal CPZ on neurogenesis were similar to those observed with developmental exposure, except for the lack of reelin response, which may contribute to a greater decrease in SGZ cells. - Highlights: • Effect of 28-day CPZ exposure on hippocampal neurogenesis was examined in rats. • CPZ suppressed intermediate neurogenesis and late-stage neurogenesis in the dentate gyrus. • CPZ suppressed BDNF signals to interneurons by decrease of

Light scattering on PHA granules protects bacterial cells against the harmful effects of UV radiation.

Science.gov (United States)

Slaninova, Eva; Sedlacek, Petr; Mravec, Filip; Mullerova, Lucie; Samek, Ota; Koller, Martin; Hesko, Ondrej; Kucera, Dan; Marova, Ivana; Obruca, Stanislav

2018-02-01

Numerous prokaryotes accumulate polyhydroxyalkanoates (PHA) in the form of intracellular granules. The primary function of PHA is the storage of carbon and energy. Nevertheless, there are numerous reports that the presence of PHA granules in microbial cells enhances their stress resistance and fitness when exposed to various stress factors. In this work, we studied the protective mechanism of PHA granules against UV irradiation employing Cupriavidus necator as a model bacterial strain. The PHA-accumulating wild type strain showed substantially higher UV radiation resistance than the PHA non-accumulating mutant. Furthermore, the differences in UV-Vis radiation interactions with both cell types were studied using various spectroscopic approaches (turbidimetry, absorption spectroscopy, and nephelometry). Our results clearly demonstrate that intracellular PHA granules efficiently scatter UV radiation, which provides a substantial UV-protective effect for bacterial cells and, moreover, decreases the intracellular level of reactive oxygen species in UV-challenged cells. The protective properties of the PHA granules are enhanced by the fact that granules specifically bind to DNA, which in turn provides shield-like protection of DNA as the most UV-sensitive molecule. To conclude, the UV-protective action of PHA granules adds considerable value to their primary storage function, which can be beneficial in numerous environments.

A Role for Serglycin Proteoglycan in Mast Cell Apoptosis Induced by a Secretory Granule-mediated Pathway*

Science.gov (United States)

Melo, Fabio Rabelo; Waern, Ida; Rönnberg, Elin; Åbrink, Magnus; Lee, David M.; Schlenner, Susan M.; Feyerabend, Thorsten B.; Rodewald, Hans-Reimer; Turk, Boris; Wernersson, Sara; Pejler, Gunnar

2011-01-01

Mast cell secretory granules (secretory lysosomes) contain large amounts of fully active proteases bound to serglycin proteoglycan. Damage to the granule membrane will thus lead to the release of serglycin and serglycin-bound proteases into the cytosol, which potentially could lead to proteolytic activation of cytosolic pro-apoptotic compounds. We therefore hypothesized that mast cells are susceptible to apoptosis induced by permeabilization of the granule membrane and that this process is serglycin-dependent. Indeed, we show that wild-type mast cells are highly sensitive to apoptosis induced by granule permeabilization, whereas serglycin-deficient cells are largely resistant. The reduced sensitivity of serglycin−/− cells to apoptosis was accompanied by reduced granule damage, reduced release of proteases into the cytosol, and defective caspase-3 activation. Mechanistically, the apoptosis-promoting effect of serglycin involved serglycin-dependent proteases, as indicated by reduced sensitivity to apoptosis and reduced caspase-3 activation in cells lacking individual mast cell-specific proteases. Together, these findings implicate serglycin proteoglycan as a novel player in mast cell apoptosis. PMID:21123167

Altered expression of the cell cycle regulatory protein cyclin D1 in the rat dentate gyrus after adrenalectomy-induced granular cell lass

NARCIS (Netherlands)

Postigo, JA; Van der Werf, YD; Korf, J; Krugers, HJ

1998-01-01

The loss of dentate gyrus (DG) granular cells after removal of the rat adrenal glands (ADX) is mediated by a process that is apoptotic in nature. The present study was initiated to compare changes in the immunocytochemical distribution of the cell-cycle regulatory protein cyclin D1, which has been

Developmental cuprizone exposure impairs oligodendrocyte lineages differentially in cortical and white matter tissues and suppresses glutamatergic neurogenesis signals and synaptic plasticity in the hippocampal dentate gyrus of rats

International Nuclear Information System (INIS)

Abe, Hajime; Saito, Fumiyo; Tanaka, Takeshi; Mizukami, Sayaka; Hasegawa-Baba, Yasuko; Imatanaka, Nobuya; Akahori, Yumi; Yoshida, Toshinori; Shibutani, Makoto

2016-01-01

Developmental cuprizone (CPZ) exposure impairs rat hippocampal neurogenesis. Here, we captured the developmental neurotoxicity profile of CPZ using a region-specific expression microarray analysis in the hippocampal dentate gyrus, corpus callosum, cerebral cortex and cerebellar vermis of rat offspring exposed to 0, 0.1, or 0.4% CPZ in the maternal diet from gestation day 6 to postnatal day (PND) 21. Transcripts of those genes identified as altered were subjected to immunohistochemical analysis on PNDs 21 and 77. Our results showed that transcripts for myelinogenesis-related genes, including Cnp, were selectively downregulated in the cerebral cortex by CPZ at ≥ 0.1% or 0.4% on PND 21. CPZ at 0.4% decreased immunostaining intensity for 2′,3′-cyclic-nucleotide 3′-phosphodiesterase (CNPase) and CNPase + and OLIG2 + oligodendrocyte densities in the cerebral cortex, whereas CNPase immunostaining intensity alone was decreased in the corpus callosum. By contrast, a striking transcript upregulation for Klotho gene and an increased density of Klotho + oligodendrocytes were detected in the corpus callosum at ≥ 0.1%. In the dentate gyrus, CPZ at ≥ 0.1% or 0.4% decreased the transcript levels for Gria1, Grin2a and Ptgs2, genes related to the synapse and synaptic transmission, and the number of GRIA1 + and GRIN2A + hilar γ-aminobutyric acid (GABA)-ergic interneurons and cyclooxygenase-2 + granule cells. All changes were reversed at PND 77. Thus, developmental CPZ exposure reversibly decreased mature oligodendrocytes in both cortical and white matter tissues, and Klotho protected white matter oligodendrocyte growth. CPZ also reversibly targeted glutamatergic signals of GABAergic interneuron to affect dentate gyrus neurogenesis and synaptic plasticity in granule cells. - Highlights: • We examined developmental cuprizone (CPZ) neurotoxicity in maternally exposed rats. • Multiple brain region-specific global gene expression profiling was performed. • CPZ decreased

Developmental cuprizone exposure impairs oligodendrocyte lineages differentially in cortical and white matter tissues and suppresses glutamatergic neurogenesis signals and synaptic plasticity in the hippocampal dentate gyrus of rats

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Abe, Hajime [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193 (Japan); Saito, Fumiyo [Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004 (Japan); Tanaka, Takeshi; Mizukami, Sayaka [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193 (Japan); Hasegawa-Baba, Yasuko [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Imatanaka, Nobuya; Akahori, Yumi [Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004 (Japan); Yoshida, Toshinori [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Shibutani, Makoto, E-mail: mshibuta@cc.tuat.ac.jp [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan)

2016-01-01

Developmental cuprizone (CPZ) exposure impairs rat hippocampal neurogenesis. Here, we captured the developmental neurotoxicity profile of CPZ using a region-specific expression microarray analysis in the hippocampal dentate gyrus, corpus callosum, cerebral cortex and cerebellar vermis of rat offspring exposed to 0, 0.1, or 0.4% CPZ in the maternal diet from gestation day 6 to postnatal day (PND) 21. Transcripts of those genes identified as altered were subjected to immunohistochemical analysis on PNDs 21 and 77. Our results showed that transcripts for myelinogenesis-related genes, including Cnp, were selectively downregulated in the cerebral cortex by CPZ at ≥ 0.1% or 0.4% on PND 21. CPZ at 0.4% decreased immunostaining intensity for 2′,3′-cyclic-nucleotide 3′-phosphodiesterase (CNPase) and CNPase{sup +} and OLIG2{sup +} oligodendrocyte densities in the cerebral cortex, whereas CNPase immunostaining intensity alone was decreased in the corpus callosum. By contrast, a striking transcript upregulation for Klotho gene and an increased density of Klotho{sup +} oligodendrocytes were detected in the corpus callosum at ≥ 0.1%. In the dentate gyrus, CPZ at ≥ 0.1% or 0.4% decreased the transcript levels for Gria1, Grin2a and Ptgs2, genes related to the synapse and synaptic transmission, and the number of GRIA1{sup +} and GRIN2A{sup +} hilar γ-aminobutyric acid (GABA)-ergic interneurons and cyclooxygenase-2{sup +} granule cells. All changes were reversed at PND 77. Thus, developmental CPZ exposure reversibly decreased mature oligodendrocytes in both cortical and white matter tissues, and Klotho protected white matter oligodendrocyte growth. CPZ also reversibly targeted glutamatergic signals of GABAergic interneuron to affect dentate gyrus neurogenesis and synaptic plasticity in granule cells. - Highlights: • We examined developmental cuprizone (CPZ) neurotoxicity in maternally exposed rats. • Multiple brain region-specific global gene expression profiling

Corticosterone Facilitates Fluoxetine-Induced Neuronal Plasticity in the Hippocampus

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Kobayashi, Katsunori; Ikeda, Yumiko; Asada, Minoru; Inagaki, Hirofumi; Kawada, Tomoyuki; Suzuki, Hidenori

2013-01-01

The hippocampal dentate gyrus has been implicated in a neuronal basis of antidepressant action. We have recently shown a distinct form of neuronal plasticity induced by the serotonergic antidepressant fluoxetine, that is, a reversal of maturation of the dentate granule cells in adult mice. This “dematuration” is induced in a large population of dentate neurons and maintained for at least one month after withdrawal of fluoxetine, suggesting long-lasting strong influence of dematuration on brain functioning. However, reliable induction of dematuration required doses of fluoxetine higher than suggested optimal doses for mice (10 to 18 mg/kg/day), which casts doubt on the clinical relevance of this effect. Since our previous studies were performed in naive mice, in the present study, we reexamined effects of fluoxetine using mice treated with chronic corticosterone that model neuroendocrine pathophysiology associated with depression. In corticosterone-treated mice, fluoxetine at 10 mg/kg/day downregulated expression of mature granule cell markers and attenuated strong frequency facilitation at the synapse formed by the granule cell axon mossy fiber, suggesting the induction of granule cell dematuration. In addition, fluoxetine caused marked enhancement of dopaminergic modulation at the mossy fiber synapse. In vehicle-treated mice, however, fluoxetine at this dose had no significant effects. The plasma level of fluoxetine was comparable to that in patients taking chronic fluoxetine, and corticosterone did not affect it. These results indicate that corticosterone facilitates fluoxetine-induced plastic changes in the dentate granule cells. Our finding may provide insight into neuronal mechanisms underlying enhanced responsiveness to antidepressant medication in certain pathological conditions. PMID:23675498

Deficits in synaptic function occur at medial perforant path-dentate granule cell synapses prior to Schaffer collateral-CA1 pyramidal cell synapses in the novel TgF344-Alzheimer's Disease Rat Model.

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Smith, Lindsey A; McMahon, Lori L

2018-02-01

Alzheimer's disease (AD) pathology begins decades prior to onset of clinical symptoms, and the entorhinal cortex and hippocampus are among the first and most extensively impacted brain regions. The TgF344-AD rat model, which more fully recapitulates human AD pathology in an age-dependent manner, is a next generation preclinical rodent model for understanding pathophysiological processes underlying the earliest stages of AD (Cohen et al., 2013). Whether synaptic alterations occur in hippocampus prior to reported learning and memory deficit is not known. Furthermore, it is not known if specific hippocampal synapses are differentially affected by progressing AD pathology, or if synaptic deficits begin to appear at the same age in males and females in this preclinical model. Here, we investigated the time-course of synaptic changes in basal transmission, paired-pulse ratio, as an indirect measure of presynaptic release probability, long-term potentiation (LTP), and dendritic spine density at two hippocampal synapses in male and ovariectomized female TgF344-AD rats and wildtype littermates, prior to reported behavioral deficits. Decreased basal synaptic transmission begins at medial perforant path-dentate granule cell (MPP-DGC) synapses prior to Schaffer-collateral-CA1 (CA3-CA1) synapses, in the absence of a change in paired-pulse ratio (PPR) or dendritic spine density. N-methyl-d-aspartate receptor (NMDAR)-dependent LTP magnitude is unaffected at CA3-CA1 synapses at 6, 9, and 12months of age, but is significantly increased at MPP-DGC synapses in TgF344-AD rats at 6months only. Sex differences were only observed at CA3-CA1 synapses where the decrease in basal transmission occurs at a younger age in males versus females. These are the first studies to define presymptomatic alterations in hippocampal synaptic transmission in the TgF344-AD rat model. The time course of altered synaptic transmission mimics the spread of pathology through hippocampus in human AD and provides

Dentate Gyrus

OpenAIRE

Allen Institute for Brain Science; Rachel A. Dalley; Lydia L. Ng; Angela L. Guillozet-Bongaarts

2008-01-01

This report contains a gene expression summary of the dentate gyrus (DG), derived from the Allen Brain Atlas (ABA) _in situ_ hybridization mouse data set. The structure's location and morphological characteristics in the mouse brain are described using the Nissl data found in the Allen Reference Atlas. Using an established algorithm, the expression values of the dentate gyrus were compared to the values of the macro/parent-structure, in this case the hippocampal region, for the purpose o...

Direct conversion of injury-site myeloid cells to fibroblast-like cells of granulation tissue.

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Sinha, Mithun; Sen, Chandan K; Singh, Kanhaiya; Das, Amitava; Ghatak, Subhadip; Rhea, Brian; Blackstone, Britani; Powell, Heather M; Khanna, Savita; Roy, Sashwati

2018-03-05

Inflammation, following injury, induces cellular plasticity as an inherent component of physiological tissue repair. The dominant fate of wound macrophages is unclear and debated. Here we show that two-thirds of all granulation tissue fibroblasts, otherwise known to be of mesenchymal origin, are derived from myeloid cells which are likely to be wound macrophages. Conversion of myeloid to fibroblast-like cells is impaired in diabetic wounds. In cross-talk between keratinocytes and myeloid cells, miR-21 packaged in extracellular vesicles (EV) is required for cell conversion. EV from wound fluid of healing chronic wound patients is rich in miR-21 and causes cell conversion more effectively compared to that by fluid from non-healing patients. Impaired conversion in diabetic wound tissue is rescued by targeted nanoparticle-based delivery of miR-21 to macrophages. This work introduces a paradigm wherein myeloid cells are recognized as a major source of fibroblast-like cells in the granulation tissue.

Protection of Dentate Hilar Cells from Prolonged Stimulation by Intracellular Calcium Chelation

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Scharfman, Helen E.; Schwartzkroin, Philip A.

1989-10-01

Prolonged afferent stimulation of the rat dentate gyrus in vivo leads to degeneration only of those cells that lack immunoreactivity for the calcium binding proteins parvalbumin and calbindin. In order to test the hypothesis that calcium binding proteins protect against the effects of prolonged stimulation, intracellular recordings were made in hippocampal slices from cells that lack immunoreactivity for calcium binding proteins. Calcium binding protein--negative cells showed electrophysiological signs of deterioration during prolonged stimulation; cells containing calcium binding protein did not. When neurons without calcium binding proteins were impaled with microelectrodes containing the calcium chelator BAPTA, and BAPTA was allowed to diffuse into the cells, these cells showed no deterioration. These results indicate that, in a complex tissue of the central nervous system, an activity-induced increase in intracellular calcium can trigger processes leading to cell deterioration, and that increasing the calcium binding capacity of a cell decreases its vulnerability to damage.

Evaluation of the protective effects of tocotrienol-rich fraction from palm oil on the dentate gyrus following chronic restraint stress in rats

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Saiful Bhari Talip

2013-06-01

Full Text Available Exposure to chronic restraint stress has been shown to cause a number of morphological changes in the hippocampal formation of rats. Tocotrienol, an isoform of vitamin E, exhibits numerous health benefits, different from those of tocopherol. Recent studies have demonstrated that tocotrienol prevents stress-induced changes in the gastric mucosa, thus indicating that it may also protect other organs such as the brain from the damaging effects of stress. Therefore, the aim of the present study was to investigate the protective effect of tocotrienol-rich fraction (TRF extracted from palm oil on the dentate gyrus of rats following exposure to chronic restraint stress. Thirty-six male Sprague Dawley rats were divided into four groups: control, stress, tocotrienol and combination of stress and tocotrienol. Animals were stressed by restraining them for 5 hours every day for 21 consecutive days. TRF was administered via oral gavage at a dose of 200 mg/kg body weight. Our results showed that the plasma corticosterone level was significantly increased in response to stress, compared to the control. The results confirmed previous findings that chronic restraint stress suppresses cellular proliferation and reduces granule cell number in the dentate gyrus. However, TRF supplementation failed to prevent or minimize these stress-induced changes. Therefore, we conclude that TRF at the current dosage is not effective in preventing the morphological changes in the dentate gyrus induced by chronic restraint stress.

Wolfram syndrome 1 gene (WFS1) product localizes to secretory granules and determines granule acidification in pancreatic beta-cells.

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Hatanaka, Masayuki; Tanabe, Katsuya; Yanai, Akie; Ohta, Yasuharu; Kondo, Manabu; Akiyama, Masaru; Shinoda, Koh; Oka, Yoshitomo; Tanizawa, Yukio

2011-04-01

Wolfram syndrome is an autosomal recessive disorder characterized by juvenile-onset insulin-dependent diabetes mellitus and optic atrophy. The gene responsible for the syndrome (WFS1) encodes an endoplasmic reticulum (ER) resident transmembrane protein. The Wfs1-null mouse exhibits progressive insulin deficiency causing diabetes. Previous work suggested that the function of the WFS1 protein is connected to unfolded protein response and to intracellular Ca(2+) homeostasis. However, its precise molecular function in pancreatic β-cells remains elusive. In our present study, immunofluorescent and electron-microscopic analyses revealed that WFS1 localizes not only to ER but also to secretory granules in pancreatic β-cells. Intragranular acidification was assessed by measuring intracellular fluorescence intensity raised by the acidotrophic agent, 3-[2,4-dinitroanilino]-3'-amino-N-methyldipropyramine. Compared with wild-type β-cells, there was a 32% reduction in the intensity in WFS1-deficient β-cells, indicating the impairment of granular acidification. This phenotype may, at least partly, account for the evidence that Wfs1-null islets have impaired proinsulin processing, resulting in an increased circulating proinsulin level. Morphometric analysis using electron microscopy evidenced that the density of secretory granules attached to the plasma membrane was significantly reduced in Wfs1-null β-cells relative to that in wild-type β-cells. This may be relevant to the recent finding that granular acidification is required for the priming of secretory granules preceding exocytosis and may partly explain the fact that glucose-induced insulin secretion is profoundly impaired in young prediabetic Wfs1-null mice. These results thus provide new insights into the molecular mechanisms of β-cell dysfunction in patients with Wolfram syndrome.

A septo-temporal molecular gradient of sfrp3 in the dentate gyrus differentially regulates quiescent adult hippocampal neural stem cell activation.

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Sun, Jiaqi; Bonaguidi, Michael A; Jun, Heechul; Guo, Junjie U; Sun, Gerald J; Will, Brett; Yang, Zhengang; Jang, Mi-Hyeon; Song, Hongjun; Ming, Guo-li; Christian, Kimberly M

2015-09-04

A converging body of evidence indicates that levels of adult hippocampal neurogenesis vary along the septo-temporal axis of the dentate gyrus, but the molecular mechanisms underlying this regional heterogeneity are not known. We previously identified a niche mechanism regulating proliferation and neuronal development in the adult mouse dentate gyrus resulting from the activity-regulated expression of secreted frizzled-related protein 3 (sfrp3) by mature neurons, which suppresses activation of radial glia-like neural stem cells (RGLs) through inhibition of Wingless/INT (WNT) protein signaling. Here, we show that activation rates within the quiescent RGL population decrease gradually along the septo-temporal axis in the adult mouse dentate gyrus, as defined by MCM2 expression in RGLs. Using in situ hybridization and quantitative real-time PCR, we identified an inverse septal-to-temporal increase in the expression of sfrp3 that emerges during postnatal development. Elimination of sfrp3 and its molecular gradient leads to increased RGL activation, preferentially in the temporal region of the adult dentate gyrus. Our study identifies a niche mechanism that contributes to the graded distribution of neurogenesis in the adult dentate gyrus and has important implications for understanding functional differences associated with adult hippocampal neurogenesis along the septo-temporal axis.

Conditional induction of Math1 specifies embryonic stem cells to cerebellar granule neuron lineage and promotes differentiation into mature granule neurons.

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Srivastava, Rupali; Kumar, Manoj; Peineau, Stéphane; Csaba, Zsolt; Mani, Shyamala; Gressens, Pierre; El Ghouzzi, Vincent

2013-04-01

Directing differentiation of embryonic stem cells (ESCs) to specific neuronal subtype is critical for modeling disease pathology in vitro. An attractive means of action would be to combine regulatory differentiation factors and extrinsic inductive signals added to the culture medium. In this study, we have generated mature cerebellar granule neurons by combining a temporally controlled transient expression of Math1, a master gene in granule neuron differentiation, with inductive extrinsic factors involved in cerebellar development. Using a Tetracyclin-On transactivation system, we overexpressed Math1 at various stages of ESCs differentiation and found that the yield of progenitors was considerably increased when Math1 was induced during embryonic body stage. Math1 triggered expression of Mbh1 and Mbh2, two target genes directly involved in granule neuron precursor formation and strong expression of early cerebellar territory markers En1 and NeuroD1. Three weeks after induction, we observed a decrease in the number of glial cells and an increase in that of neurons albeit still immature. Combining Math1 induction with extrinsic factors specifically increased the number of neurons that expressed Pde1c, Zic1, and GABAα6R characteristic of mature granule neurons, formed "T-shaped" axons typical of granule neurons, and generated synaptic contacts and action potentials in vitro. Finally, in vivo implantation of Math1-induced progenitors into young adult mice resulted in cell migration and settling of newly generated neurons in the cerebellum. These results show that conditional induction of Math1 drives ESCs toward the cerebellar fate and indicate that acting on both intrinsic and extrinsic factors is a powerful means to modulate ESCs differentiation and maturation into a specific neuronal lineage. Copyright © 2012 AlphaMed Press.

Dipeptidyl peptidase IV is sorted to the secretory granules in pancreatic islet A-cells

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Poulsen, Mona Dam; Hansen, Gert Helge; Dabelsteen, Erik

1993-01-01

Dipeptidyl peptidase IV (DP IV:EC 3.4.14.5) was localized in endocrine cells of pig pancreas by immunohistochemical and enzyme histochemical methods. Immunolight microscopy with both monoclonal and polyclonal antibodies demonstrated DP IV immunoreactivity in cells located in the peripheral part...... of the islets of Langerhans. The antigen is enzymatically active, as shown by enzyme histochemical analysis with a synthetic DP IV substrate. By immunoelectron microscopy (immunogold labeling), the labeling of DP IV in the islets was associated with the secretory granules of the A-cells, as identified by double...... labeling using a monoclonal glucagon antibody as the second primary antibody. These results show that DP IV is sorted to secretory granules in the pig pancreatic islet A-cells. Furthermore, this secretory granule enzyme, as opposed to intestinal brush border DP IV, is suggested to be a soluble protein...

Early x-irradiation of rats. Part 2. Effect of granule cells and their dendrodendritic synapses in the olfactory bulb

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Halasz, N

1987-01-01

Low, repeated doses of X-rays from a Co/sup 60/ source were used to impair the development of the granule cells and their dendritic terminals in the olfactory bulb, and the resulting effect was studied under light and electron microscopes at 9 days of age. Irradiation of rats from embryonic day 18 (in utero) to postnatal day 5 resulted, among others, in maldevelopment of the (internal) granule cell and external plexiform layers. This was accompanied by a decrease in the number and the density of the granule cells, and the remaining granule cells contained less ribosomes, regardless of their position within the layer. This implies that both supposed subtypes of granule cells were effected. In the external plexiform layer, a reduced number of mature dendrodendritic synapses and signs of harmed granule gemmules were observed. The results suggest that intrauterinal plus postnatal irradiation with low, repeated doses of X-rays may be an effective tool impairing the development of prenatally forming neurons.

Notch1 deficiency in postnatal neural progenitor cells in the dentate gyrus leads to emotional and cognitive impairment.

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Feng, Shufang; Shi, Tianyao; Qiu, Jiangxia; Yang, Haihong; Wu, Yan; Zhou, Wenxia; Wang, Wei; Wu, Haitao

2017-10-01

It is well known that Notch1 signaling plays a crucial role in embryonic neural development and adult neurogenesis. The latest evidence shows that Notch1 also plays a critical role in synaptic plasticity in mature hippocampal neurons. So far, deeper insights into the function of Notch1 signaling during the different steps of adult neurogenesis are still lacking, and the mechanisms by which Notch1 dysfunction is associated with brain disorders are also poorly understood. In the current study, we found that Notch1 was highly expressed in the adult-born immature neurons in the hippocampal dentate gyrus. Using a genetic approach to selectively ablate Notch1 signaling in late immature precursors in the postnatal hippocampus by cross-breeding doublecortin (DCX) + neuron-specific proopiomelanocortin (POMC)-α Cre mice with floxed Notch1 mice, we demonstrated a previously unreported pivotal role of Notch1 signaling in survival and function of adult newborn neurons in the dentate gyrus. Moreover, behavioral and functional studies demonstrated that POMC-Notch1 -/- mutant mice showed anxiety and depressive-like behavior with impaired synaptic transmission properties in the dentate gyrus. Finally, our mechanistic study showed significantly compromised phosphorylation of cAMP response element-binding protein (CREB) in Notch1 mutants, suggesting that the dysfunction of Notch1 mutants is associated with the disrupted pCREB signaling in postnatally generated immature neurons in the dentate gyrus.-Feng, S., Shi, T., Qiu, J., Yang, H., Wu, Y., Zhou, W., Wang, W., Wu, H. Notch1 deficiency in postnatal neural progenitor cells in the dentate gyrus leads to emotional and cognitive impairment. © FASEB.

A STEREOLOGICAL ANALYSIS OF THE EFFECT OF EARLY POSTNATAL ETHANOL EXPOSURE ON NEURONAL NUMBERS IN RAT DENTATE GYRUS

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Takanori Miki

2011-05-01

Full Text Available Maternal ethanol ingestion during pregnancy can cause fetal alcohol syndrome (FAS in their offspring. Among the symptoms of FAS, damage to the central nervous system has emerged as one of the most serious problems. We have previously shown that a relatively high dose of ethanol exposure during early postnatal life can cause alterations in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rat pups to ethanol during early postnatal life had effects on the total number of the dentate gyrus neurons. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 to 15. Ethanol exposure was achieved by placing rat pups in a chamber containing ethanol vapour for 3 hours a day. The blood ethanol concentration was found to be about 430 mg/dL at the end of the exposure period. Groups of ethanol treated (ET, separation controls (SC and mother reared controls (MRC were anaesthetised and killed at 16-days-of-age by perfusion with phosphate-buffered 2.5% glutaraldehyde. The Cavalieri principle was used to determine the volume of subdivisions of the dentate gyrus, and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There was, on average, about 421,000 granule cells in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This value was significantly smaller than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. It is concluded that neurons in the hilus region of the dentate gyrus may be particularly vulnerable to the effects of a high dose of ethanol exposure during PND 10-15. It is likely that this deficit was due to neuronal death induced by some mechanisms related to

Liver X receptor β regulates the development of the dentate gyrus and autistic-like behavior in the mouse.

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Cai, Yulong; Tang, Xiaotong; Chen, Xi; Li, Xin; Wang, Ying; Bao, Xiaohang; Wang, Lian; Sun, Dayu; Zhao, Jinghui; Xing, Yan; Warner, Margaret; Xu, Haiwei; Gustafsson, Jan-Åke; Fan, Xiaotang

2018-03-20

The dentate gyrus (DG) of the hippocampus is a laminated brain region in which neurogenesis begins during early embryonic development and continues until adulthood. Recent studies have implicated that defects in the neurogenesis of the DG seem to be involved in the genesis of autism spectrum disorders (ASD)-like behaviors. Liver X receptor β (LXRβ) has recently emerged as an important transcription factor involved in the development of laminated CNS structures, but little is known about its role in the development of the DG. Here, we show that deletion of the LXRβ in mice causes hypoplasia in the DG, including abnormalities in the formation of progenitor cells and granule cell differentiation. We also found that expression of Notch1, a central mediator of progenitor cell self-renewal, is reduced in LXRβ-null mice. In addition, LXRβ deletion in mice results in autistic-like behaviors, including abnormal social interaction and repetitive behavior. These data reveal a central role for LXRβ in orchestrating the timely differentiation of neural progenitor cells within the DG, thereby providing a likely explanation for its association with the genesis of autism-related behaviors in LXRβ-deficient mice.

Axo-somatic synapses in the normal and X-irradiated dendate gyrus; factors affecting the density of afferent innervation

International Nuclear Information System (INIS)

Lee, K.S.; Gerbrandt, L.; Lynch, G.

1982-01-01

The density of synaptic input to the somata of dentate gyrus granule cells was examined utilizing quantitative electron microscopic techniques. In control (non-irradiated) material, greater numbers of axo-somatic synapses were observed in the superficial, earlier-generated cells as compared to the deep, later-generated cells. We further studied the X-irradiated dentate gyrus, in which the majority of granule cells were destroyed during postnatal genesis. The surviving cells displayed a density of innervation on their somata which exceeded that observed in either layer of the control material. These data are discussed in terms of the possible contribution of afferent-target cell interactions to the regulation of the density of synaptic innervation. (Auth.)

Axo-somatic synapses in the normal and X-irradiated dendate gyrus; factors affecting the density of afferent innervation

Energy Technology Data Exchange (ETDEWEB)

Lee, K S [Max-Planck-Institut fuer Psychiatrie, Muenchen (Germany, F.R.); Gerbrandt, L [Neuroscience Research Program, Boston, MA (USA); Lynch, G [California Univ., Irvine (USA)

1982-10-07

The density of synaptic input to the somata of dentate gyrus granule cells was examined utilizing quantitative electron microscopic techniques. In control (non-irradiated) material, greater numbers of axo-somatic synapses were observed in the superficial, earlier-generated cells as compared to the deep, later-generated cells. We further studied the X-irradiated dentate gyrus, in which the majority of granule cells were destroyed during postnatal genesis. The surviving cells displayed a density of innervation on their somata which exceeded that observed in either layer of the control material. These data are discussed in terms of the possible contribution of afferent-target cell interactions to the regulation of the density of synaptic innervation.

Lamotrigine increases the number of BrdU-labeled cells in the rat hippocampus

DEFF Research Database (Denmark)

Kondziella, Daniel; Strandberg, Joakim; Lindquist, Catarina

2011-01-01

Antidepressant medication and electroconvulsive therapy stabilize mood symptoms and increase hippocampal neurogenesis. We examined whether lamotrigine, suggested to give rise to mood-stabilizing and antidepressant effects in addition to its antiepileptic properties, also increases the number of n...... in the granule cell layer of the dentate gyrus showed an increased number of newborn cells in rats receiving lamotrigine (42.6 ± 3.5 cells/slice) compared with valproate (31.6 ± 2.8) and controls (32.2 ± 3.1; P...

PDK1 Deficit Impairs the Development of the Dentate Gyrus in Mice.

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Xu, Min; Han, Xiaoning; Liu, Rui; Li, Yanjun; Qi, Cui; Yang, Zhongzhou; Zhao, Chunjie; Gao, Jun

2018-02-06

3-Phosphoinositide-dependent protein kinase-1 (PDK1) is crucial for the development of the dentate gyrus (DG), the first gateway receiving afferent inputs from the entorhinal cortex. However, the role of PDK1 in DG development is unclear. In the present study, by crossing Pdk1fl/fl mice with the Emx1-cre line, we identified that the ablation of PDK1 disrupted the development of DG via decreasing the proliferation, and increasing the differentiation of dentate neural progenitor cells, downregulating AKT activity and upregulating GSK3β signaling. Moreover, PDK1 deletion disrupted the distribution of Reelin+ cells and decreased the level of Reelin mRNA which may contribute to the defective migration of progenitor cells and the disrupted radial glial scaffolds. Furthermore, the inhibition of GSK3β activity partially restored the decreased proliferation of primary neural stem cells in vitro. Taken together, our data indicated that the ablation of PDK1 affected the proliferation and differentiation of dentate neural progenitor cells in mice. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Differentiation and functional incorporation of embryonic stem cell-derived GABAergic interneurons in the dentate gyrus of mice with temporal lobe epilepsy.

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Maisano, Xu; Litvina, Elizabeth; Tagliatela, Stephanie; Aaron, Gloster B; Grabel, Laura B; Naegele, Janice R

2012-01-04

Cell therapies for neurological disorders require an extensive knowledge of disease-associated neuropathology and procedures for generating neurons for transplantation. In many patients with severe acquired temporal lobe epilepsy (TLE), the dentate gyrus exhibits sclerosis and GABAergic interneuron degeneration. Mounting evidence suggests that therapeutic benefits can be obtained by transplanting fetal GABAergic progenitors into the dentate gyrus in rodents with TLE, but the scarcity of human fetal cells limits applicability in patient populations. In contrast, virtually limitless quantities of neural progenitors can be obtained from embryonic stem (ES) cells. ES cell-based therapies for neurological repair in TLE require evidence that the transplanted neurons integrate functionally and replace cell types that degenerate. To address these issues, we transplanted mouse ES cell-derived neural progenitors (ESNPs) with ventral forebrain identities into the hilus of the dentate gyrus of mice with TLE and evaluated graft differentiation, mossy fiber sprouting, cellular morphology, and electrophysiological properties of the transplanted neurons. In addition, we compared electrophysiological properties of the transplanted neurons with endogenous hilar interneurons in mice without TLE. The majority of transplanted ESNPs differentiated into GABAergic interneuron subtypes expressing calcium-binding proteins parvalbumin, calbindin, or calretinin. Global suppression of mossy fiber sprouting was not observed; however, ESNP-derived neurons formed dense axonal arborizations in the inner molecular layer and throughout the hilus. Whole-cell hippocampal slice electrophysiological recordings and morphological analyses of the transplanted neurons identified five basic types; most with strong after-hyperpolarizations and smooth or sparsely spiny dendritic morphologies resembling endogenous hippocampal interneurons. Moreover, intracellular recordings of spontaneous EPSCs indicated that

The lysine acetyltransferase activator Brpf1 governs dentate gyrus development through neural stem cells and progenitors.

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Linya You

2015-03-01

Full Text Available Lysine acetylation has recently emerged as an important post-translational modification in diverse organisms, but relatively little is known about its roles in mammalian development and stem cells. Bromodomain- and PHD finger-containing protein 1 (BRPF1 is a multidomain histone binder and a master activator of three lysine acetyltransferases, MOZ, MORF and HBO1, which are also known as KAT6A, KAT6B and KAT7, respectively. While the MOZ and MORF genes are rearranged in leukemia, the MORF gene is also mutated in prostate and other cancers and in four genetic disorders with intellectual disability. Here we show that forebrain-specific inactivation of the mouse Brpf1 gene causes hypoplasia in the dentate gyrus, including underdevelopment of the suprapyramidal blade and complete loss of the infrapyramidal blade. We trace the developmental origin to compromised Sox2+ neural stem cells and Tbr2+ intermediate neuronal progenitors. We further demonstrate that Brpf1 loss deregulates neuronal migration, cell cycle progression and transcriptional control, thereby causing abnormal morphogenesis of the hippocampus. These results link histone binding and acetylation control to hippocampus development and identify an important epigenetic regulator for patterning the dentate gyrus, a brain structure critical for learning, memory and adult neurogenesis.

Neurogenesis paradoxically decreases both pattern separation and memory interference

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Rory eFinnegan

2015-10-01

Full Text Available The hippocampus has been the focus of memory research for decades. While the functional role of this structure is not fully understood, it is widely recognized as being vital for rapid yet accurate encoding of associative memories. Since the discovery of adult hippocampal neurogenesis in the dentate gyrus by Altman and Das in the 1960's, many theories and models have been put forward to explain the functional role it plays in learning and memory. These models postulate different ways new in which neurons are introduced into the dentate gyrus and their functional importance for learning and memory. Few if any previous models have incorporated the full range of unique properties of young adult-born dentate granule cells and their developmental trajectory. In this paper, we propose a novel computational model of the dentate gyrus that incorporates the developmental trajectory of the adult-born dentate granule cells, including changes in synaptic plasticity, connectivity, excitability and lateral inhibition, using a modified version of the Restricted Boltzmann machine. Our results show superior performance on memory reconstruction tasks for both recent and distally learned items, when the unique characteristics of young dentate granule cells are taken into account. Even though the hyperexcitability of the young neurons generates more overlapping neural codes, reducing pattern separation, the unique properties of the young neurons nonetheless contribute to reducing retroactive and proactive interference, at both short and long time scales. The sparse connectivity is particularly important for generating distinct memory traces for highly overlapping patterns that are learned within the same context.

Three-dimensional ultrastructural analyses of anterior pituitary gland expose spatial relationships between endocrine cell secretory granule localization and capillary distribution.

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Yoshitomi, Munetake; Ohta, Keisuke; Kanazawa, Tomonoshin; Togo, Akinobu; Hirashima, Shingo; Uemura, Kei-Ichiro; Okayama, Satoko; Morioka, Motohiro; Nakamura, Kei-Ichiro

2016-10-31

Endocrine and endothelial cells of the anterior pituitary gland frequently make close appositions or contacts, and the secretory granules of each endocrine cell tend to accumulate at the perivascular regions, which is generally considered to facilitate secretory functions of these cells. However, three-dimensional relationships between the localization pattern of secretory granules and blood vessels are not fully understood. To define and characterize these spatial relationships, we used scanning electron microscopy (SEM) three-dimensional reconstruction method based on focused ion-beam slicing and scanning electron microscopy (FIB/SEM). Full three-dimensional cellular architectures of the anterior pituitary tissue at ultrastructural resolution revealed that about 70% of endocrine cells were in apposition to the endothelial cells, while almost 30% of endocrine cells were entirely isolated from perivascular space in the tissue. Our three-dimensional analyses also visualized the distribution pattern of secretory granules in individual endocrine cells, showing an accumulation of secretory granules in regions in close apposition to the blood vessels in many cases. However, secretory granules in cells isolated from the perivascular region tended to distribute uniformly in the cytoplasm of these cells. These data suggest that the cellular interactions between the endocrine and endothelial cells promote an uneven cytoplasmic distribution of the secretory granules.

Mathematical modeling and statistical analysis of calcium-regulated insulin granule exocytosis in ß-cells from mice and humans

DEFF Research Database (Denmark)

Pedersen, Morten Gram; Cortese, Giuliana; Eliasson, Lena

2011-01-01

Insulin is released from pancreatic ß-cells as a result of Ca2+-evoked exocytosis of dense-core granules. Secretion is biphasic, which has been suggested to correspond to the release of different granule pools. Here we review and carefully reanalyze previously published patch-clamp data on depola......Insulin is released from pancreatic ß-cells as a result of Ca2+-evoked exocytosis of dense-core granules. Secretion is biphasic, which has been suggested to correspond to the release of different granule pools. Here we review and carefully reanalyze previously published patch-clamp data...... on depolarization-evoked Ca2+-currents and corresponding capacitance measurements. Using a statistical mixed-effects model, we show that the data indicate that pool depletion is negligible in response to short depolarizations in mouse ß-cells. We then review mathematical models of granule dynamics and exocytosis...

Poly (ADP-ribose polymerase plays an important role in intermittent hypoxia-induced cell death in rat cerebellar granule cells

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Chiu Sheng-Chun

2012-03-01

Full Text Available Abstract Background Episodic cessation of airflow during sleep in patients with sleep apnea syndrome results in intermittent hypoxia (IH. Our aim was to investigate the effects of IH on cerebellar granule cells and to identify the mechanism of IH-induced cell death. Methods Cerebellar granule cells were freshly prepared from neonatal Sprague-Dawley rats. IH was created by culturing the cerebellar granule cells in the incubators with oscillating O2 concentration at 20% and 5% every 30 min for 1-4 days. The results of this study are based on image analysis using a confocal microscope and associated software. Cellular oxidative stress increased with increase in IH. In addition, the occurrence of cell death (apoptosis and necrosis increased as the duration of IH increased, but decreased in the presence of an iron chelator (phenanthroline or poly (ADP-ribose polymerase (PARP inhibitors [3-aminobenzamide (3-AB and DPQ]. The fluorescence of caspase-3 remained the same regardless of the duration of IH, and Western blots did not detect activation of caspase-3. However, IH increased the ratio of apoptosis-inducing factor (AIF translocation to the nucleus, while PARP inhibitors (3-AB reduced this ratio. Results According to our findings, IH increased oxidative stress and subsequently leading to cell death. This effect was at least partially mediated by PARP activation, resulting in ATP depletion, calpain activation leading to AIF translocation to the nucleus. Conclusions We suggest that IH induces cell death in rat primary cerebellar granule cells by stimulating oxidative stress PARP-mediated calpain and AIF activation.

Updating the lamellar hypothesis of hippocampal organization

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Robert S Sloviter

2012-12-01

Full Text Available In 1971, Andersen and colleagues proposed that excitatory activity in the entorhinal cortex propagates topographically to the dentate gyrus, and on through a trisynaptic circuit lying within transverse hippocampal slices or lamellae [Andersen, Bliss, and Skrede. 1971. Lamellar organization of hippocampal pathways. Exp Brain Res 13, 222-238]. In this way, a relatively simple structure might mediate complex functions in a manner analogous to the way independent piano keys can produce a nearly infinite variety of unique outputs. The lamellar hypothesis derives primary support from the lamellar distribution of dentate granule cell axons (the mossy fibers, which innervate dentate hilar neurons and area CA3 pyramidal cells and interneurons within the confines of a thin transverse hippocampal segment. Following the initial formulation of the lamellar hypothesis, anatomical studies revealed that unlike granule cells, hilar mossy cells, CA3 pyramidal cells, and Layer II entorhinal cells all form axonal projections that are more divergent along the longitudinal axis than the clearly lamellar mossy fiber pathway. The existence of pathways with translamellar distribution patterns has been interpreted, incorrectly in our view, as justifying outright rejection of the lamellar hypothesis [Amaral and Witter. 1989. The three-dimensional organization of the hippocampal formation: a review of anatomical data. Neuroscience 31, 571-591]. We suggest that the functional implications of longitudinally-projecting axons depend not on whether they exist, but on what they do. The observation that focal granule cell layer discharges normally inhibit, rather than excite, distant granule cells suggests that longitudinal axons in the dentate gyrus may mediate "lateral" inhibition and define lamellar function, rather than undermine it. In this review, we attempt a reconsideration of the evidence that most directly impacts the physiological concept of hippocampal lamellar

Is the goal of mastication reached in young dentates, aged dentates and aged denture wearers?

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Mishellany-Dutour, Anne; Renaud, Johanne; Peyron, Marie-Agnès; Rimek, Frank; Woda, Alain

2008-01-01

The objective of the present study was to assess the impact of age and dentition status on masticatory function. A three-arm case-control study was performed. Group 1 (n 14) was composed of young fully dentate subjects (age 35.6 +/- 10.6 years), group 2 (n 14) of aged fully dentate subjects (age 68.8 +/- 7.0 years) and group 3 (n 14) of aged full denture wearers (age 68.1 +/- 7.2 years). Mastication adaptation was assessed in the course of chewing groundnuts and carrots to swallowing threshold. Particle size distribution of the chewed food, electromyographic (EMG) activity of the masseter and temporalis muscles during chewing, and resting and stimulated whole saliva rates were measured. Aged dentate subjects used significantly more chewing strokes to reach swallowing threshold than younger dentate subjects (P < 0.05), with increased particle size reduction, longer chewing sequence duration (P < 0.05) and greater total EMG activity (P < 0.05) for both groundnuts and carrots. In addition, aged denture wearers made significantly more chewing strokes than aged dentate subjects (P < 0.001) to reach swallowing threshold for groundnuts. Particle size reduction at time of swallowing was significantly poorer for denture wearers than for their aged dentate counterparts, despite an increase in chewing strokes, sequence duration and EMG activity per sequence. Masticatory function was thus adapted to ageing, but was impaired in denture wearers, who failed to adapt fully to their deficient masticatory apparatus.

Host cell subversion by Toxoplasma GRA16, an exported dense granule protein that targets the host cell nucleus and alters gene expression.

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Bougdour, Alexandre; Durandau, Eric; Brenier-Pinchart, Marie-Pierre; Ortet, Philippe; Barakat, Mohamed; Kieffer, Sylvie; Curt-Varesano, Aurélie; Curt-Bertini, Rose-Laurence; Bastien, Olivier; Coute, Yohann; Pelloux, Hervé; Hakimi, Mohamed-Ali

2013-04-17

After invading host cells, Toxoplasma gondii multiplies within a parasitophorous vacuole (PV) that is maintained by parasite proteins secreted from organelles called dense granules. Most dense granule proteins remain within the PV, and few are known to access the host cell cytosol. We identify GRA16 as a dense granule protein that is exported through the PV membrane and reaches the host cell nucleus, where it positively modulates genes involved in cell-cycle progression and the p53 tumor suppressor pathway. GRA16 binds two host enzymes, the deubiquitinase HAUSP and PP2A phosphatase, which exert several functions, including regulation of p53 and the cell cycle. GRA16 alters p53 levels in a HAUSP-dependent manner and induces nuclear translocation of the PP2A holoenzyme. Additionally, certain GRA16-deficient strains exhibit attenuated virulence, indicating the importance of these host alterations in pathogenesis. Therefore, GRA16 represents a potentially emerging subfamily of exported dense granule proteins that modulate host function. Copyright © 2013 Elsevier Inc. All rights reserved.

The Stress Granule RNA-Binding Protein TIAR-1 Protects Female Germ Cells from Heat Shock in Caenorhabditis elegans

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Gabriela Huelgas-Morales

2016-04-01

Full Text Available In response to stressful conditions, eukaryotic cells launch an arsenal of regulatory programs to protect the proteome. One major protective response involves the arrest of protein translation and the formation of stress granules, cytoplasmic ribonucleoprotein complexes containing the conserved RNA-binding proteins TIA-1 and TIAR. The stress granule response is thought to preserve mRNA for translation when conditions improve. For cells of the germline—the immortal cell lineage required for sexual reproduction—protection from stress is critically important for perpetuation of the species, yet how stress granule regulatory mechanisms are deployed in animal reproduction is incompletely understood. Here, we show that the stress granule protein TIAR-1 protects the Caenorhabditis elegans germline from the adverse effects of heat shock. Animals containing strong loss-of-function mutations in tiar-1 exhibit significantly reduced fertility compared to the wild type following heat shock. Analysis of a heat-shock protein promoter indicates that tiar-1 mutants display an impaired heat-shock response. We observed that TIAR-1 was associated with granules in the gonad core and oocytes during several stressful conditions. Both gonad core and oocyte granules are dynamic structures that depend on translation; protein synthesis inhibitors altered their formation. Nonetheless, tiar-1 was required for the formation of gonad core granules only. Interestingly, the gonad core granules did not seem to be needed for the germ cells to develop viable embryos after heat shock. This suggests that TIAR-1 is able to protect the germline from heat stress independently of these structures.

The Stress Granule RNA-Binding Protein TIAR-1 Protects Female Germ Cells from Heat Shock in Caenorhabditis elegans.

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Huelgas-Morales, Gabriela; Silva-García, Carlos Giovanni; Salinas, Laura S; Greenstein, David; Navarro, Rosa E

2016-04-07

In response to stressful conditions, eukaryotic cells launch an arsenal of regulatory programs to protect the proteome. One major protective response involves the arrest of protein translation and the formation of stress granules, cytoplasmic ribonucleoprotein complexes containing the conserved RNA-binding proteins TIA-1 and TIAR. The stress granule response is thought to preserve mRNA for translation when conditions improve. For cells of the germline-the immortal cell lineage required for sexual reproduction-protection from stress is critically important for perpetuation of the species, yet how stress granule regulatory mechanisms are deployed in animal reproduction is incompletely understood. Here, we show that the stress granule protein TIAR-1 protects the Caenorhabditis elegans germline from the adverse effects of heat shock. Animals containing strong loss-of-function mutations in tiar-1 exhibit significantly reduced fertility compared to the wild type following heat shock. Analysis of a heat-shock protein promoter indicates that tiar-1 mutants display an impaired heat-shock response. We observed that TIAR-1 was associated with granules in the gonad core and oocytes during several stressful conditions. Both gonad core and oocyte granules are dynamic structures that depend on translation; protein synthesis inhibitors altered their formation. Nonetheless, tiar-1 was required for the formation of gonad core granules only. Interestingly, the gonad core granules did not seem to be needed for the germ cells to develop viable embryos after heat shock. This suggests that TIAR-1 is able to protect the germline from heat stress independently of these structures. Copyright © 2016 Huelgas-Morales et al.

Intracisternal granules in the adipokinetic cells of locusts are not degraded and apparently function as supplementary stores of secretory material.

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Harthoorn, L F; Diederen, J H; Oudejans, R C; Verstegen, M M; Vullings, H G; Van der Horst, D J

2000-01-01

The intracisternal granules in locust adipokinetic cells appear to represent accumulations of secretory material within cisternae of the rough endoplasmic reticulum. An important question is whether these granules are destined for degradation or represent stores of (pro)hormones. Two strategies were used to answer this question. First, cytochemistry was applied to elucidate the properties of intracisternal granules. The endocytic tracers horseradish peroxidase and wheat-germ agglutinin-conjugated horseradish peroxidase were used to facilitate the identification of endocytic, autophagic, and lysosomal organelles, which may be involved in the degradation of intracisternal granules. No intracisternal granules could be found within autophagosomes, and granules fused with endocytic and lysosomal organelles were not observed, nor could tracer be found within the granules. The lysosomal enzyme acid phosphatase was absent from the granules. Second, biochemical analysis of the content of intracisternal granules revealed that these granules contain prohormones as well as hormones. Prohormones were present in relatively higher amounts compared with ordinary secretory granules. Since the intracisternal granules in locust adipokinetic cells are not degraded and contain intact (pro)hormones it is concluded that they function as supplementary stores of secretory material.

Organization of spinocerebellar projection map in three types of agranular cerebellum: Purkinje cells vs. granule cells as organizer element

International Nuclear Information System (INIS)

Arsenio Nunes, M.L.; Sotelo, C.; Wehrle, R.

1988-01-01

The organization of the spinocerebellar projection was analysed by the anterograde axonal WGA-HRP (horseradish peroxidase-wheat germ agglutinin conjugate) tracing method in three different types of agranular cerebellar cortex either induced experimentally by X-irradiation or occurring spontaneously in weaver (wv/wv) and staggerer (sg/sg) mutant mice. The results of this study show that in the X-irradiated rat and weaver mouse, in both of which the granule cells are directly affected and die early in development, the spinal axons reproduce, with few differences, the normal spinocerebellar pattern. Conversely, in staggerer mouse, in which the Purkinje cells are intrinsically affected and granule neurons do not seem to be primarily perturbed by the staggerer gene action, the spinocerebellar organization is severely modified. These findings appear somewhat paradoxical because if granule cells, the synaptic targets of mossy spinocerebellar fibers, were necessary for the organization of spinocerebellar projection, the staggerer cerebellum would exhibit a much more normal projectional map than the weaver and the X-irradiated cerebella. It is, therefore, obvious that granule cells, and even specific synaptogenesis, are not essential for the establishment of the normal spinocerebellar topography. On the other hand, the fact that the Purkinje cells are primarily affected in the unique agranular cortex in which the spinocerebellar organization is severely modified suggests that these neurons could be the main element in the organization of the spinocerebellar projection map. This hypothesis is discussed in correlation with already-reported findings on the zonation of the cerebellar cortex by biochemically different clusters of Purkinje cells

Orexin 1 and orexin 2 receptor antagonism in the basolateral amygdala modulate long-term potentiation of the population spike in the perforant path-dentate gyrus-evoked field potential in rats.

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Ardeshiri, Motahareh Rouhi; Hosseinmardi, Narges; Akbari, Esmaeil

2018-03-01

Involvement of amygdalo-hippocampal substructures in patients with narcolepsy due to deficiencies in the orexinergic system, and the presence of hippocampus-dependent memory impairments in this disorder, have led us to investigate the effects of orexin 1 and 2 receptor antagonism in the basolateral amygdala (BLA) on long-term potentiation (LTP) of dentate gyrus (DG) granular cells. We used a 200-Hz high-frequency stimulation protocol in anesthetized rats. We studied the long-term synaptic plasticity of perforant path-dentate gyrus granule cells following the inactivation of orexin receptors before and after tetanic stimulation. LTP of the DG population spike was attenuated in the presence of orexin 1 and 2 receptor antagonism (treatment with SB-334867-A and TCS-OX2-29, respectively) in the BLA when compared to that observed following treatment with dimethyl sulfoxide (DMSO). However, the population excitatory post-synaptic potentials were not affected. Moreover, when orexin 1 and 2 receptors in the BLA were blocked after LTP induction, there were no differences between the DMSO and treatment groups. Our findings suggest that the orexinergic system of the BLA plays a modulatory role in the regulation of hippocampal plasticity in rats. Copyright © 2018 Elsevier Inc. All rights reserved.

Gamma-radiation produces abnormal Bergmann fibers and ectopic granule cells in mouse cerebellar cortex

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Inouye, Minoru; Hayasaka, Shizu; Funahashi, Atsushi; Yamamura, Hideki

1992-01-01

Morphological changes in Bergmann glial fibers in the developing cerebellar cortex produced by exposure to gamma-rays were investigated in association with ectopic granule cells. Six-day-old mice that had been exposed to 3 Gy of gamma-radiation were killed 6 hours after exposure or at 7 through 30 days of age. Their cerebella were examined histologically and immunohistochemically for glial fibrillary acidic protein in Bergmann fibers. Extensive cell death took place in the external granular layer (EGL) of the cerebellum from 6 through 24 hours after exposure. This led to the thinning of the EGL and a decrease in the number of migrating cells in the molecular layer. The number of Bergmann cells was not decreased, but the fibers in the molecular layer were distorted; whereas, in the control these fibers were straight and perpendicular to the pial surface. The EGL began to recover 2 days after exposure, and abnormally oriented migrating cells were seen. At 17 days of age, some cell clustering was observed in the molecular layer of the irradiated cerebellum. Distortion of the Bergmann fibers was marked in regions where ectopic granule cells appeared at 30 days of age. These findings suggest that the distortion of Bergmann fibers leads to the production of ectopic granule cells after exposure to gamma-radiation. (author)

KIF20A-Mediated RNA Granule Transport System Promotes the Invasiveness of Pancreatic Cancer Cells

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Keisuke Taniuchi

2014-12-01

Full Text Available Pancreatic cancers are aggressive because they are highly invasive and highly metastatic; moreover, effective treatments for aggressive pancreatic cancers are lacking. Here, we report that the motor kinesin protein KIF20A promoted the motility and invasiveness of pancreatic cancer cells through transporting the RNA-binding protein IGF2BP3 and IGF2BP3-bound transcripts toward cell protrusions along microtubules. We previously reported that IGF2BP3 and its target transcripts are assembled into cytoplasmic stress granules of pancreatic cancer cells, and that IGF2BP3 promotes the motility and invasiveness of pancreatic cancer cells through regulation of localized translation of IGF2BP3-bound transcripts in cell protrusions. We show that knockdown of KIF20A inhibited accumulation of IGF2BP3-containing stress granules in cell protrusions and suppressed local protein expression from specific IGF2BP3-bound transcripts, ARF6 and ARHGEF4, in the protrusions. Our results provide insight into the link between regulation of KIF20A-mediated trafficking of IGF2BP3-containing stress granules and modulation of the motility and invasiveness in pancreatic cancers.

On the origins of the universal dynamics of endogenous granules in mammalian cells.

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Vanapalli, Siva A; Li, Yixuan; Mugele, Frieder; Duits, Michel H G

2009-12-01

Endogenous granules (EGs) that consist of lipid droplets and mitochondria have been commonly used to assess intracellular mechanical properties via multiple particle tracking microrheology (MPTM). Despite their widespread use, the nature of interaction of EGs with the cytoskeletal network and the type of forces driving their dynamics--both of which are crucial for the interpretation of the results from MPTM technique--are yet to be resolved. In this report, we study the dynamics of endogenous granules in mammalian cells using particle tracking methods. We find that the ensemble dynamics of EGs is diffusive in three types of mammalian cells (endothelial cells, smooth muscle cells and fibroblasts), thereby suggesting an apparent universality in their dynamical behavior. Moreover, in a given cell, the amplitude of the mean-squared displacement for EGs is an order of magnitude larger than that of injected particles. This observation along with results from ATP depletion and temperature intervention studies suggests that cytoskeletal active forces drive the dynamics of EGs. To elucidate the dynamical origin of the diffusive-like nonthermal motion, we consider three active force generation mechanisms--molecular motor transport, actomyosin contractility and microtubule polymerization forces. We test these mechanisms using pharmacological interventions. Experimental evidence and model calculations suggest that EGs are intimately linked to microtubules and that microtubule polymerization forces drive their dynamics. Thus, endogenous granules could serve as non-invasive probes for microtubule network dynamics in mammalian cells.

Influence of Spray-dried Hydroxyapatite-5-Fluorouracil Granules on Cell Lines Derived from Tissues of Mesenchymal Origin

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Tim Scharnweber

2008-11-01

Full Text Available In our previous work we described the preparation and characterization of spray dried hydroxyapatite micro granules loaded with 5-fluorouracil (5-FU. These loaded particles are used as a model drug delivery system (DDS. In this study we examined the in vitro response of two cell lines derived from different tissues to 5-FU loaded granules (LG. Both cell lines, either L929 cells of a mouse fibroblast lineage or cells originating from a rat osteosarcoma (ROS 17/2.8 showed a dose dependent decrease in cell proliferation in response to 5-FU-, either dissolved in the culture medium or loaded onto particles. The response of the two cell lines to loaded and nonloaded particles was different. The effect of LG and of a corresponding concentration of free 5-FU was practically the same for the ROS 17/2.8 cells indicating that ROS 17/2.8 cells were not affected by the carrier material. In contrast, L929 cells showed a slight decrease in cell proliferation also in the presence of granules not loaded with 5-FU. This is thought to be attributed to the inhibition of mitogenesis by phosphocitrates, already demonstrated in fibroblasts. In summary, we found that the loaded 5-FU kept its effectivity after the spray drying process and that the response towards the granules varied with cell type. This is the first step towards a tissue specific DDS.

Effect of dentate gyrus disruption on remembering what happened where

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Min W Jung

2015-06-01

Full Text Available Our previous studies using Bax knockout (Bax-KO mice, in which newly generated granule cells continue to accumulate, disrupting neural circuitry specifically in the dentate gyrus (DG, suggest the involvement of the DG in binding the internally-generated spatial map with sensory information on external landmarks (spatial map-object association in forming a distinct spatial context for each environment. In order to test whether the DG is also involved in binding the internal spatial map with sensory information on external events (spatial map-event association, we tested the behavior of Bax-KO mice in a delayed-non-match-to-place task. Performance of Bax-KO mice was indistinguishable from that of wild-type mice as long as there was no interruption during the delay period (tested up to 5 min, suggesting that on-line maintenance of working memory is intact in Bax-KO mice. However, Bax-KO mice showed profound performance deficits when they were removed from the maze during the delay period (interruption condition with a sufficiently long (65 s delay, suggesting that episodic memory was impaired in Bax-KO mice. Together with previous findings, these results suggest the role of the DG in binding spatial information derived from dead reckoning and nonspatial information, such as external objects and events, in the process of encoding episodic memory.

Temporal changes in prosaposin expression in the rat dentate gyrus after birth.

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Midori Morishita

Full Text Available Neurogenesis in the hippocampal dentate gyrus occurs constitutively throughout postnatal life. Adult neurogenesis includes a multistep process that ends with the formation of a postmitotic and functionally integrated new neuron. During adult neurogenesis, various markers are expressed, including GFAP, nestin, Pax6, polysialic acid-neural cell adhesion molecule (PSA-NCAM, neuronal nuclei (NeuN, doublecortin, TUC-4, Tuj-1, and calretinin. Prosaposin is the precursor of saposins A-D; it is found in various organs and can be excreted. Strong prosaposin expression has been demonstrated in the developing brain including the hippocampus, and its neurotrophic activity has been proposed. This study investigated changes in prosaposin in the dentate gyrus of young and adult rats using double immunohistochemistry with antibodies to prosaposin, PSA-NCAM, and NeuN. Prosaposin immunoreactivity was intense in the dentate gyrus at postnatal day 3 (P3 and P7, but decreased gradually after P14. In the dentate gyrus at P28, immature PSA-NCAM-positive neurons localized exclusively in the subgranular zone were prosaposin-negative, whereas mature Neu-N-positive neurons were positive for prosaposin. Furthermore, these prosaposin-negative immature neurons were saposin B-positive, suggesting that the neurons take up and degrade prosaposin. In situ hybridization assays showed that prosaposin in the adult dentate gyrus is dominantly the Pro+9 type, a secreted type of prosaposin. These results imply that prosaposin secreted from mature neurons stimulates proliferation and maturation of immature neurons in the dentate gyrus.

Temporal changes in prosaposin expression in the rat dentate gyrus after birth.

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Morishita, Midori; Nabeka, Hiroaki; Shimokawa, Tetsuya; Miyawaki, Kyojy; Doihara, Takuya; Saito, Shouichiro; Kobayashi, Naoto; Matsuda, Seiji

2014-01-01

Neurogenesis in the hippocampal dentate gyrus occurs constitutively throughout postnatal life. Adult neurogenesis includes a multistep process that ends with the formation of a postmitotic and functionally integrated new neuron. During adult neurogenesis, various markers are expressed, including GFAP, nestin, Pax6, polysialic acid-neural cell adhesion molecule (PSA-NCAM), neuronal nuclei (NeuN), doublecortin, TUC-4, Tuj-1, and calretinin. Prosaposin is the precursor of saposins A-D; it is found in various organs and can be excreted. Strong prosaposin expression has been demonstrated in the developing brain including the hippocampus, and its neurotrophic activity has been proposed. This study investigated changes in prosaposin in the dentate gyrus of young and adult rats using double immunohistochemistry with antibodies to prosaposin, PSA-NCAM, and NeuN. Prosaposin immunoreactivity was intense in the dentate gyrus at postnatal day 3 (P3) and P7, but decreased gradually after P14. In the dentate gyrus at P28, immature PSA-NCAM-positive neurons localized exclusively in the subgranular zone were prosaposin-negative, whereas mature Neu-N-positive neurons were positive for prosaposin. Furthermore, these prosaposin-negative immature neurons were saposin B-positive, suggesting that the neurons take up and degrade prosaposin. In situ hybridization assays showed that prosaposin in the adult dentate gyrus is dominantly the Pro+9 type, a secreted type of prosaposin. These results imply that prosaposin secreted from mature neurons stimulates proliferation and maturation of immature neurons in the dentate gyrus.

Effects of Scopolamine and Melatonin Cotreatment on Cognition, Neuronal Damage, and Neurogenesis in the Mouse Dentate Gyrus.

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Chen, Bai Hui; Ahn, Ji Hyeon; Park, Joon Ha; Choi, Soo Young; Lee, Yun Lyul; Kang, Il Jun; Hwang, In Koo; Lee, Tae-Kyeong; Shin, Bich-Na; Lee, Jae-Chul; Hong, Seongkweon; Jeon, Yong Hwan; Shin, Myoung Cheol; Cho, Jun Hwi; Won, Moo-Ho; Lee, Young Joo

2018-03-01

It has been demonstrated that melatonin plays important roles in memory improvement and promotes neurogenesis in experimental animals. We examined effects of melatonin on cognitive deficits, neuronal damage, cell proliferation, neuroblast differentiation and neuronal maturation in the mouse dentate gyrus after cotreatment of scopolamine (anticholinergic agent) and melatonin. Scopolamine (1 mg/kg) and melatonin (10 mg/kg) were intraperitoneally injected for 2 and/or 4 weeks to 8-week-old mice. Scopolamine treatment induced significant cognitive deficits 2 and 4 weeks after scopolamine treatment, however, cotreatment of scopolamine and melatonin significantly improved spatial learning and short-term memory impairments. Two and 4 weeks after scopolamine treatment, neurons were not damaged/dead in the dentate gyrus, in addition, no neuronal damage/death was shown after cotreatment of scopolamine and melatonin. Ki67 (a marker for cell proliferation)- and doublecortin (a marker for neuroblast differentiation)-positive cells were significantly decreased in the dentate gyrus 2 and 4 weeks after scopolamine treatment, however, cotreatment of scopolamine and melatonin significantly increased Ki67- and doublecortin-positive cells compared with scopolamine-treated group. However, double immunofluorescence for NeuN/BrdU, which indicates newly-generated mature neurons, did not show double-labeled cells (adult neurogenesis) in the dentate gyrus 2 and 4 weeks after cotreatment of scopolamine and melatonin. Our results suggest that melatonin treatment recovers scopolamine-induced spatial learning and short-term memory impairments and restores or increases scopolamine-induced decrease of cell proliferation and neuroblast differentiation, but does not lead to adult neurogenesis (maturation of neurons) in the mouse dentate gyrus following scopolamine treatment.

Releasing dentate nucleus cells from Purkinje cell inhibition generates output from the cerebrocerebellum.

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Takahiro Ishikawa

Full Text Available The cerebellum generates its vast amount of output to the cerebral cortex through the dentate nucleus (DN that is essential for precise limb movements in primates. Nuclear cells in DN generate burst activity prior to limb movement, and inactivation of DN results in cerebellar ataxia. The question is how DN cells become active under intensive inhibitory drive from Purkinje cells (PCs. There are two excitatory inputs to DN, mossy fiber and climbing fiber collaterals, but neither of them appears to have sufficient strength for generation of burst activity in DN. Therefore, we can assume two possible mechanisms: post-inhibitory rebound excitation and disinhibition. If rebound excitation works, phasic excitation of PCs and a concomitant inhibition of DN cells should precede the excitation of DN cells. On the other hand, if disinhibition plays a primary role, phasic suppression of PCs and activation of DN cells should be observed at the same timing. To examine these two hypotheses, we compared the activity patterns of PCs in the cerebrocerebellum and DN cells during step-tracking wrist movements in three Japanese monkeys. As a result, we found that the majority of wrist-movement-related PCs were suppressed prior to movement onset and the majority of wrist-movement-related DN cells showed concurrent burst activity without prior suppression. In a minority of PCs and DN cells, movement-related increases and decreases in activity, respectively, developed later. These activity patterns suggest that the initial burst activity in DN cells is generated by reduced inhibition from PCs, i.e., by disinhibition. Our results indicate that suppression of PCs, which has been considered secondary to facilitation, plays the primary role in generating outputs from DN. Our findings provide a new perspective on the mechanisms used by PCs to influence limb motor control and on the plastic changes that underlie motor learning in the cerebrocerebellum.

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...

Proneurotrophin-3 promotes cell cycle withdrawal of developing cerebellar granule cell progenitors via the p75 neurotrophin receptor.

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Zanin, Juan Pablo; Abercrombie, Elizabeth; Friedman, Wilma J

2016-07-19

Cerebellar granule cell progenitors (GCP) proliferate extensively in the external granule layer (EGL) of the developing cerebellum prior to differentiating and migrating. Mechanisms that regulate the appropriate timing of cell cycle withdrawal of these neuronal progenitors during brain development are not well defined. The p75 neurotrophin receptor (p75(NTR)) is highly expressed in the proliferating GCPs, but is downregulated once the cells leave the cell cycle. This receptor has primarily been characterized as a death receptor for its ability to induce neuronal apoptosis following injury. Here we demonstrate a novel function for p75(NTR) in regulating proper cell cycle exit of neuronal progenitors in the developing rat and mouse EGL, which is stimulated by proNT3. In the absence of p75(NTR), GCPs continue to proliferate beyond their normal period, resulting in a larger cerebellum that persists into adulthood, with consequent motor deficits.

Ectopic Expression of α6 and δ GABAA Receptor Subunits in Hilar Somatostatin Neurons Increases Tonic Inhibition and Alters Network Activity in the Dentate Gyrus

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Tong, Xiaoping; Peng, Zechun; Zhang, Nianhui; Cetina, Yliana; Huang, Christine S.; Wallner, Martin; Otis, Thomas S.

2015-01-01

The role of GABAA receptor (GABAAR)-mediated tonic inhibition in interneurons remains unclear and may vary among subgroups. Somatostatin (SOM) interneurons in the hilus of the dentate gyrus show negligible expression of nonsynaptic GABAAR subunits and very low tonic inhibition. To determine the effects of ectopic expression of tonic GABAAR subtypes in these neurons, Cre-dependent viral vectors were used to express GFP-tagged GABAAR subunits (α6 and δ) selectively in hilar SOM neurons in SOM-Cre mice. In single-transfected animals, immunohistochemistry demonstrated strong expression of either the α6 or δ subunit; in cotransfected animals, both subunits were consistently expressed in the same neurons. Electrophysiology revealed a robust increase of tonic current, with progressively larger increases following transfection of δ, α6, and α6/δ subunits, respectively, indicating formation of functional receptors in all conditions and likely coassembly of the subunits in the same receptor following cotransfection. An in vitro model of repetitive bursting was used to determine the effects of increased tonic inhibition in hilar SOM interneurons on circuit activity in the dentate gyrus. Upon cotransfection, the frequency of GABAAR-mediated bursting in granule cells was reduced, consistent with a reduction in synchronous firing among hilar SOM interneurons. Moreover, in vivo studies of Fos expression demonstrated reduced activation of α6/δ-cotransfected neurons following acute seizure induction by pentylenetetrazole. The findings demonstrate that increasing tonic inhibition in hilar SOM interneurons can alter dentate gyrus circuit activity during strong stimulation and suggest that tonic inhibition of interneurons could play a role in regulating excessive synchrony within the network. SIGNIFICANCE STATEMENT In contrast to many hippocampal interneurons, somatostatin (SOM) neurons in the hilus of the dentate gyrus have very low levels of nonsynaptic GABAARs and exhibit

Effects of x irradiation on the postnatally-forming granule cell populations in the olfactory bulb, hippocampus, and cerebellum of the rat

International Nuclear Information System (INIS)

Bayer, S.A.; Altman, J.

1975-01-01

Beginning on the second postnatal day, either two (2X group), four (4X group) or six (6X group) daily or alternate daily exposures to low-level x irradiation (150 to 200 R) were used to interfere with the acquisition of granule cells in the olfactory bulb, hippocampus, and cerebellum of the rat. At 60 days of age, the relationship between post-irradiation recovery and permanent granule cell loss was assessed with two quantitative techniques. First, the total number of granule cells was determined to estimate the magnitude of permanent loss. Secondly, the number of labeled granule cells were counted on day 60 after a 3 H-thymidine injection given on either day 15 or on day 20 to estimate differential rates of cell proliferation during the recovery period. Permanent loss of granule cells was sustained in all regions by all schedules of irradiation. The time for the most effective exposures was earlier in the hippocampus and olfactory bulb than in the cerebellum. In all regions, both the irradiated groups and the controls showed a decrease in the level of cell proliferation between 15 and 20 days. The number of cells that could be labeled after either the 15 or 20 day injection was below control levels for all groups in the hippocampus, at control levels for all groups in the cerebellum, and either at (2X and 4X) or below (6X) control levels in the olfactory bulb. These results are discussed in the light of the formation time of the granule cells in each region

Effects of x-irradiation on the postnatally-forming granule cell populations in the olfactory bulb, hippocampus, and cerebellum of the rat

International Nuclear Information System (INIS)

Bayer, S.A.; Altman, J.

1975-01-01

Beginning on the second postnatal day, either two (2X group), four (4X group) or six (6X group) daily or alternate daily exposures to low-level x irradiation (150-200 r) were used to interfere with the acquisition of granule cells in the olfactory bulb, hippocampus, and cerebellum of the rat. At 60 days of age, the relationship between post-irradiation recovery and permanent granule cell loss was assessed with two quantitative techniques. First, the total number of granule cells was determined to estimate the magnitude of permanent loss. Secondly, the number of labeled granule cells were counted on day 60 after a 3 H-thymidine injection given on either day 15 or on day 20 to estimate differential rates of cell proliferation during the recovery period. Permanent loss of granule cells was sustained in all regions by all schedules of irradiation. The time for the most effective exposures was earlier in the hippocampus and olfactory bulb than in the cerebellum. In all regions, both the irradiated groups and the controls showed a decrease in the level of cell proliferation between 15 and 20 days. The number of cells that could be labeled after either the 15 or 20 day injection was below control levels for all groups in the hippocampus, at control levels for all groups in the cerebellum, and either at (2X and 4X) or below (6X) control levels in the olfactory bulb. These results are discussed in the light of the formation time of the granule cells in each region

Spontaneous calcium waves in granule cells in cerebellar slice cultures

DEFF Research Database (Denmark)

Apuschkin, Mia; Ougaard, Maria; Rekling, Jens C

2013-01-01

Multiple regions in the CNS display propagating correlated activity during embryonic and postnatal development. This activity can be recorded as waves of increased calcium concentrations in spiking neurons or glia cells, and have been suggested to be involved in patterning, axonal guidance and es......, that the propagating wave activity is carried through the tissue by axonal collaterals formed by neighboring granule cells, and further suggest that the correlated activity may be related to processes that ensure correct postnatal wiring of the cerebellar circuits....

Loss of Melanin by Eye Retinal Pigment Epithelium Cells Is Associated with Its Oxidative Destruction in Melanolipofuscin Granules.

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Dontsov, A E; Sakina, N L; Ostrovsky, M A

2017-08-01

The effect of superoxide radicals on melanin destruction and degradation of melanosomes isolated from cells of retinal pigment epithelium (RPE) of the human eye was studied. We found that potassium superoxide causes destruction of melanin in melanosomes of human and bovine RPE, as well as destruction of melanin from the ink bag of squid, with the formation of fluorescent decay products having an emission maximum at 520-525 nm. The initial kinetics of the accumulation of the fluorescent decay products is linear. Superoxide radicals lead simultaneously to a decrease in the number of melanosomes and to a decrease in concentration of paramagnetic centers in them. Complete degradation of melanosomes leads to the formation of a transparent solution containing dissolved proteins and melanin degradation products that do not exhibit paramagnetic properties. To completely degrade one melanosome of human RPE, 650 ± 100 fmol of superoxide are sufficient. The concentration of paramagnetic centers in a melanolipofuscin granule of human RPE is on average 32.5 ± 10.4% (p melanin undergoing a destruction process in these granules. RPE cells also contain intermediate granules that have an EPR signal with a lower intensity than that of melanolipofuscin granules, but higher than that of lipofuscin granules. This signal is due to the presence of residual melanin in these granules. Irradiation of a mixture of melanosomes with lipofuscin granules with blue light (450 nm), in contrast to irradiation of only melanosomes, results in the appearance of fluorescent melanin degradation products. We suggest that one of the main mechanisms of age-related decrease in melanin concentration in human RPE cells is its destruction in melanolipofuscin granules under the action of superoxide radicals formed during photoinduced oxygen reduction by lipofuscin fluorophores.

The life cycle of platelet granules.

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Sharda, Anish; Flaumenhaft, Robert

2018-01-01

Platelet granules are unique among secretory vesicles in both their content and their life cycle. Platelets contain three major granule types-dense granules, α-granules, and lysosomes-although other granule types have been reported. Dense granules and α-granules are the most well-studied and the most physiologically important. Platelet granules are formed in large, multilobulated cells, termed megakaryocytes, prior to transport into platelets. The biogenesis of dense granules and α-granules involves common but also distinct pathways. Both are formed from the trans -Golgi network and early endosomes and mature in multivesicular bodies, but the formation of dense granules requires trafficking machinery different from that of α-granules. Following formation in the megakaryocyte body, both granule types are transported through and mature in long proplatelet extensions prior to the release of nascent platelets into the bloodstream. Granules remain stored in circulating platelets until platelet activation triggers the exocytosis of their contents. Soluble N -ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, located on both the granules and target membranes, provide the mechanical energy that enables membrane fusion during both granulogenesis and exocytosis. The function of these core fusion engines is controlled by SNARE regulators, which direct the site, timing, and extent to which these SNAREs interact and consequently the resulting membrane fusion. In this review, we assess new developments in the study of platelet granules, from their generation to their exocytosis.

The roles of BDNF, pCREB and Wnt3a in the latent period preceding activation of progenitor cell mitosis in the adult dentate gyrus by fluoxetine.

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Scarlett B Pinnock

2010-10-01

Full Text Available The formation of new neurons continues into adult life in the dentate gyrus of the rat hippocampus, as in many other species. Neurogenesis itself turns out to be highly labile, and is regulated by a number of factors. One of these is the serotoninergic system: treatment with drugs (such as the SSRI fluoxetine markedly stimulates mitosis in the progenitor cells of the dentate gyrus. But this process has one remarkable feature: it takes at least 14 days of continuous treatment to be effective. This is despite the fact that the pharmacological action of fluoxetine occurs within an hour or so of first administration. This paper explores the role of BDNF in this process, using the effect of a Trk antagonist (K252a on the labelling of progenitor cells with the mitosis marker Ki67 and the associated expression of pCREB and Wnt3a. These experiments show that (i Fluoxetine increased Ki67 counts, as well as pCREB and Wnt3a expression in the dentate gyrus. The action of fluoxetine on the progenitor cells and on pCREB (but not Wnt3a depends upon Trk receptor activation, since it was prevented by icv infusion of K252a. (ii These receptors are required for both the first 7 days of fluoxetine action, during which no apparent change in progenitor mitosis occurs, as well as the second 7 days. Increased pCREB was always associated with progenitor cell mitosis, but Wnt3a expression may be necessary but not sufficient for increased progenitor cell proliferation. These results shed new light on the action of fluoxetine on neurogenesis in the adult dentate gyrus, and have both clinical and experimental interest.

Regrowing the adult brain: NF-κB controls functional circuit formation and tissue homeostasis in the dentate gyrus.

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Yvonne Imielski

Full Text Available Cognitive decline during aging is correlated with a continuous loss of cells within the brain and especially within the hippocampus, which could be regenerated by adult neurogenesis. Here we show that genetic ablation of NF-κB resulted in severe defects in the neurogenic region (dentate gyrus of the hippocampus. Despite increased stem cell proliferation, axogenesis, synaptogenesis and neuroprotection were hampered, leading to disruption of the mossy fiber pathway and to atrophy of the dentate gyrus during aging. Here, NF-κB controls the transcription of FOXO1 and PKA, regulating axogenesis. Structural defects culminated in behavioral impairments in pattern separation. Re-activation of NF-κB resulted in integration of newborn neurons, finally to regeneration of the dentate gyrus, accompanied by a complete recovery of structural and behavioral defects. These data identify NF-κB as a crucial regulator of dentate gyrus tissue homeostasis suggesting NF-κB to be a therapeutic target for treating cognitive and mood disorders.

Regrowing the Adult Brain: NF-κB Controls Functional Circuit Formation and Tissue Homeostasis in the Dentate Gyrus

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Imielski, Yvonne; Schwamborn, Jens C.; Lüningschrör, Patrick; Heimann, Peter; Holzberg, Magdalena; Werner, Hendrikje; Leske, Oliver; Püschel, Andreas W.; Memet, Sylvie; Heumann, Rolf; Israel, Alain; Kaltschmidt, Christian; Kaltschmidt, Barbara

2012-01-01

Cognitive decline during aging is correlated with a continuous loss of cells within the brain and especially within the hippocampus, which could be regenerated by adult neurogenesis. Here we show that genetic ablation of NF-κB resulted in severe defects in the neurogenic region (dentate gyrus) of the hippocampus. Despite increased stem cell proliferation, axogenesis, synaptogenesis and neuroprotection were hampered, leading to disruption of the mossy fiber pathway and to atrophy of the dentate gyrus during aging. Here, NF-κB controls the transcription of FOXO1 and PKA, regulating axogenesis. Structural defects culminated in behavioral impairments in pattern separation. Re-activation of NF-κB resulted in integration of newborn neurons, finally to regeneration of the dentate gyrus, accompanied by a complete recovery of structural and behavioral defects. These data identify NF-κB as a crucial regulator of dentate gyrus tissue homeostasis suggesting NF-κB to be a therapeutic target for treating cognitive and mood disorders. PMID:22312433

Nitrous Oxide Induces Prominent Cell Proliferation in Adult Rat Hippocampal Dentate Gyrus

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Farah Chamaa

2018-05-01

Full Text Available The identification of distinct and more efficacious antidepressant treatments is highly needed. Nitrous oxide (N2O is an N-methyl-D-aspartic acid (NMDA antagonist that has been reported to exhibit antidepressant effects in treatment-resistant depression (TRD patients. Yet, no studies have investigated the effects of sub-anesthetic dosages of N2O on hippocampal cell proliferation and neurogenesis in adult brain rats. In our study, adult male Sprague-Dawley rats were exposed to single or multiple exposures to mixtures of 70% N2O and 30% oxygen (O2. Sham groups were exposed to 30% O2 and the control groups to atmospheric air. Hippocampal cell proliferation was assessed by bromodeoxyuridine (BrdU incorporation, and BrdU-positive cells were counted in the dentate gyrus (DG using confocal microscopy. Results showed that while the rates of hippocampal cell proliferation were comparable between the N2O and sham groups at day 1, levels increased by 1.4 folds at day 7 after one session exposure to N2O. Multiple N2O exposures significantly increased the rate of hippocampal cell proliferation to two folds. Therefore, sub-anesthetic doses of N2O, similar to ketamine, increase hippocampal cell proliferation, suggesting that there will ultimately be an increase in neurogenesis. Future studies should investigate added N2O exposures and their antidepressant behavioral correlates.

Weaver mutant mouse cerebellar granule cells respond normally to chronic depolarization

DEFF Research Database (Denmark)

Bjerregaard, Annette; Mogensen, Helle Smidt; Hack, N

1997-01-01

We studied the effects of chronic K(+)-induced membrane depolarization and treatment with N-methyl-D-aspartate (NMDA) on cerebellar granule cells (CGCs) from weaver mutant mice and non-weaver litter-mates. The weaver mutation is a Gly-to-Ser substitution in a conserved region of the Girk2 G prote...

Early postischemic 45Ca accumulation in rat dentate hilus

International Nuclear Information System (INIS)

Benveniste, H.; Diemer, N.H.

1988-01-01

Several studies have found postischemic regional accumulation of calcium to be time-dependent and coincident with the progression of ischemic cell change. In the most vulnerable cells in the hippocampus one would therefore expect to find a primary and specific early uptake of calcium after ischemia. Autoradiograms of 45 Ca and 3 H-inulin distribution were investigated before and 1 h after 20 min ischemia in the rat hippocampus. Two different methodological approaches were used for administration of 45 Ca: (a) administration via microdialysis probes, (b) intraventricular injection. During control conditions the 45 Ca autoradiograms showed variations in distribution volume in accordance with 3 H-inulin determination of extracellular space size. One hour after ischemia a massive accumulation of 45 Ca was found in the dentate hilus. No change in the distribution pattern of 3 H-inulin could be demonstrated 1 h after ischemia. We suggest that 45 Ca accumulation in dentate hilus 1 h after ischemia is a result of increased Ca 2+ uptake before irreversible cell damage occurs and is not due to passive influx of calcium across a leaky plasma membrane

Suspension of Mitotic Activity in Dentate Gyrus of the Hibernating Ground Squirrel

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Victor I. Popov

2011-01-01

Full Text Available Neurogenesis occurs in the adult mammalian hippocampus, a region of the brain important for learning and memory. Hibernation in Siberian ground squirrels provides a natural model to study mitosis as the rapid fall in body temperature in 24 h (from 35-36°C to +4–6°C permits accumulation of mitotic cells at different stages of the cell cycle. Histological methods used to study adult neurogenesis are limited largely to fixed tissue, and the mitotic state elucidated depends on the specific phase of mitosis at the time of day. However, using an immunohistochemical study of doublecortin (DCX and BrdU-labelled neurons, we demonstrate that the dentate gyrus of the ground squirrel hippocampus contains a population of immature cells which appear to possess mitotic activity. Our data suggest that doublecortin-labelled immature cells exist in a mitotic state and may represent a renewable pool for generation of new neurons within the dentate gyrus.

Bmi1 overexpression in the cerebellar granule cell lineage of mice affects cell proliferation and survival without initiating medulloblastoma formation

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Hourinaz Behesti

2013-01-01

BMI1 is a potent inducer of neural stem cell self-renewal and neural progenitor cell proliferation during development and in adult tissue homeostasis. It is overexpressed in numerous human cancers – including medulloblastomas, in which its functional role is unclear. We generated transgenic mouse lines with targeted overexpression of Bmi1 in the cerebellar granule cell lineage, a cell type that has been shown to act as a cell of origin for medulloblastomas. Overexpression of Bmi1 in granule cell progenitors (GCPs led to a decrease in cerebellar size due to decreased GCP proliferation and repression of the expression of cyclin genes, whereas Bmi1 overexpression in postmitotic granule cells improved cell survival in response to stress by altering the expression of genes in the mitochondrial cell death pathway and of Myc and Lef-1. Although no medulloblastomas developed in ageing cohorts of transgenic mice, crosses with Trp53−/− mice resulted in a low incidence of medulloblastoma formation. Furthermore, analysis of a large collection of primary human medulloblastomas revealed that tumours with a BMI1high TP53low molecular profile are significantly enriched in Group 4 human medulloblastomas. Our data suggest that different levels and timing of Bmi1 overexpression yield distinct cellular outcomes within the same cellular lineage. Importantly, Bmi1 overexpression at the GCP stage does not induce tumour formation, suggesting that BMI1 overexpression in GCP-derived human medulloblastomas probably occurs during later stages of oncogenesis and might serve to enhance tumour cell survival.

Overexpression of Mineralocorticoid Receptors in the Mouse Forebrain Partly Alleviates the Effects of Chronic Early Life Stress on Spatial Memory, Neurogenesis and Synaptic Function in the Dentate Gyrus

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Sofia Kanatsou

2017-05-01

Full Text Available Evidence from human studies suggests that high expression of brain mineralocorticoid receptors (MR may promote resilience against negative consequences of stress exposure, including childhood trauma. We examined, in mice, whether brain MR overexpression can alleviate the effects of chronic early life stress (ELS on contextual memory formation under low and high stress conditions, and neurogenesis and synaptic function of dentate gyrus granular cells. Male mice were exposed to ELS by housing the dam with limited nesting and bedding material from postnatal day (PND 2 to 9. We investigated the moderating role of MRs by using forebrain-specific transgenic MR overexpression (MR-tg mice. Low-stress contextual (i.e., object relocation memory formation was hampered by ELS in wildtype but not MR-tg mice. Anxiety like behavior and high-stress contextual (i.e., fear memory formation were unaffected by ELS and/or MR expression level. At the cellular level, an interaction effect was observed between ELS and MR overexpression on the number of doublecortin-positive cells, with a significant difference between the wildtype ELS and MR-tg ELS groups. No interaction was found regarding Ki-67 and BrdU staining. A significant interaction between ELS and MR expression was further observed with regard to mEPSCs and mIPSC frequency. The ratio of evoked EPSC/IPSC or NMDA/AMPA responses was unaffected. Overall, these results suggest that ELS affects contextual memory formation under low stress conditions as well as neurogenesis and synaptic transmission in dentate granule cells, an effect that can be alleviated by MR-overexpression.

Simulating spinal border cells and cerebellar granule cells under locomotion--a case study of spinocerebellar information processing.

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Anton Spanne

Full Text Available The spinocerebellar systems are essential for the brain in the performance of coordinated movements, but our knowledge about the spinocerebellar interactions is very limited. Recently, several crucial pieces of information have been acquired for the spinal border cell (SBC component of the ventral spinocerebellar tract (VSCT, as well as the effects of SBC mossy fiber activation in granule cells of the cerebellar cortex. SBCs receive monosynaptic input from the reticulospinal tract (RST, which is an important driving system under locomotion, and disynaptic inhibition from Ib muscle afferents. The patterns of activity of RST neurons and Ib afferents under locomotion are known. The activity of VSCT neurons under fictive locomotion, i.e. without sensory feedback, is also known, but there is little information on how these neurons behave under actual locomotion and for cerebellar granule cells receiving SBC input this is completely unknown. But the available information makes it possible to simulate the interactions between the spinal and cerebellar neuronal circuitries with a relatively large set of biological constraints. Using a model of the various neuronal elements and the network they compose, we simulated the modulation of the SBCs and their target granule cells under locomotion and hence generated testable predictions of their general pattern of modulation under this condition. This particular system offers a unique opportunity to simulate these interactions with a limited number of assumptions, which helps making the model biologically plausible. Similar principles of information processing may be expected to apply to all spinocerebellar systems.

In Vivo Dentate Nucleus Gamma-aminobutyric Acid Concentration in Essential Tremor vs. Controls.

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Louis, Elan D; Hernandez, Nora; Dyke, Jonathan P; Ma, Ruoyun E; Dydak, Ulrike

2018-04-01

Despite its high prevalence, essential tremor (ET) is among the most poorly understood neurological diseases. The presence and extent of Purkinje cell (PC) loss in ET is the subject of controversy. PCs are a major storehouse of central nervous system gamma-aminobutyric acid (GABA), releasing GABA at the level of the dentate nucleus. It is therefore conceivable that cerebellar dentate nucleus GABA concentration could be an in vivo marker of PC number. We used in vivo 1 H magnetic resonance spectroscopy (MRS) to quantify GABA concentrations in two cerebellar volumes of interest, left and right, which included the dentate nucleus, comparing 45 ET cases to 35 age-matched controls. 1 H MRS was performed using a 3.0-T Siemens Tim Trio scanner. The MEGA-PRESS J-editing sequence was used for GABA detection in two cerebellar volumes of interest (left and right) that included the dentate nucleus. The two groups did not differ with respect to our primary outcome of GABA concentration (given in institutional units). For the right dentate nucleus, [GABA] in ET cases = 2.01 ± 0.45 and [GABA] in controls = 1.86 ± 0.53, p = 0.17. For the left dentate nucleus, [GABA] in ET cases = 1.68 ± 0.49 and [GABA] controls = 1.80 ± 0.53, p = 0.33. The controls had similar dentate nucleus [GABA] in the right vs. left dentate nucleus (p = 0.52); however, in ET cases, the value on the right was considerably higher than that on the left (p = 0.001). We did not detect a reduction in dentate nucleus GABA concentration in ET cases vs. One interpretation of the finding is that it does not support the existence of PC loss in ET; however, an alternative interpretation is the observed pattern could be due to the effects of terminal sprouting in ET (i.e., collateral sprouting from surviving PCs making up for the loss of GABA-ergic terminals from PC degeneration). Further research is needed.

Ex vivo study of dentate gyrus neurogenesis in human pharmacoresistant temporal lobe epilepsy.

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Paradisi, M; Fernández, M; Del Vecchio, G; Lizzo, G; Marucci, G; Giulioni, M; Pozzati, E; Antonelli, T; Lanzoni, G; Bagnara, G P; Giardino, L; Calzà, L

2010-10-01

Neurogenesis in adult humans occurs in at least two areas of the brain, the subventricular zone of the telencephalon and the subgranular layer of the dentate gyrus in the hippocampal formation. We studied dentate gyrus subgranular layer neurogenesis in patients subjected to tailored antero-mesial temporal resection including amygdalohippocampectomy due to pharmacoresistant temporal lobe epilepsy (TLE) using the in vitro neurosphere assay. Sixteen patients were enrolled in the study; mesial temporal sclerosis (MTS) was present in eight patients. Neurogenesis was investigated by ex vivo neurosphere expansion in the presence of mitogens (epidermal growth factor + basic fibroblast growth factor) and spontaneous differentiation after mitogen withdrawal. Growth factor synthesis was investigated by qRT-PCR in neurospheres. We demonstrate that in vitro proliferation of cells derived from dentate gyrus of TLE patients is dependent on disease duration. Moreover, the presence of MTS impairs proliferation. As long as in vitro proliferation occurs, neurogenesis is maintained, and cells expressing a mature neurone phenotype (TuJ1, MAP2, GAD) are spontaneously formed after mitogen withdrawal. Finally, formed neurospheres express mRNAs encoding for growth (vascular endothelial growth factor) as well as neurotrophic factors (brain-derived neurotrophic factor, ciliary neurotrophic factor, glial-derived neurotrophic factor, nerve growth factor). We demonstrated that residual neurogenesis in the subgranular layer of the dentate gyrus in TLE is dependent on diseases duration and absent in MTS. © 2010 The Authors. Neuropathology and Applied Neurobiology © 2010 British Neuropathological Society.

Improved Light Conversion Efficiency Of Dye-Sensitized Solar Cell By Dispersing Submicron-Sized Granules Into The Nano-Sized TiO2 Layer

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Song S.A.

2015-06-01

Full Text Available In this work, TiO2 nanoparticles and submicron-sized granules were synthesized by a hydrothermal method and spray pyrolysis, respectively. Submicron-sized granules were dispersed into the nano-sized TiO2 layer to improve the light conversion efficiency. Granules showed better light scattering, but lower in terms of the dye-loading quantity and recombination resistance compared with nanoparticles. Consequently, the nano-sized TiO2 layer had higher cell efficiency than the granulized TiO2 layer. When dispersed granules into the nanoparticle layer, the light scattering was enhanced without the loss of dye-loading quantities. The dispersion of granulized TiO2 led to increase the cell efficiency up to 6.51%, which was about 5.2 % higher than that of the electrode consisting of only TiO2 nanoparticles. Finally, the optimal hydrothermal temperature and dispersing quantity of granules were found to be 200°C and 20 wt%, respectively.

Exercise improves cognitive responses to psychological stress through enhancement of epigenetic mechanisms and gene expression in the dentate gyrus.

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Andrew Collins

Full Text Available We have shown previously that exercise benefits stress resistance and stress coping capabilities. Furthermore, we reported recently that epigenetic changes related to gene transcription are involved in memory formation of stressful events. In view of the enhanced coping capabilities in exercised subjects we investigated epigenetic, gene expression and behavioral changes in 4-weeks voluntarily exercised rats.Exercised and control rats coped differently when exposed to a novel environment. Whereas the control rats explored the new cage for the complete 30-min period, exercised animals only did so during the first 15 min after which they returned to sleeping or resting behavior. Both groups of animals showed similar behavioral responses in the initial forced swim session. When re-tested 24 h later however the exercised rats showed significantly more immobility behavior and less struggling and swimming. If rats were killed at 2 h after novelty or the initial swim test, i.e. at the peak of histone H3 phospho-acetylation and c-Fos induction, then the exercised rats showed a significantly higher number of dentate granule neurons expressing the histone modifications and immediate-early gene induction.Thus, irrespective of the behavioral response in the novel cage or initial forced swim session, the impact of the event at the dentate gyrus level was greater in exercised rats than in control animals. Furthermore, in view of our concept that the neuronal response in the dentate gyrus after forced swimming is involved in memory formation of the stressful event, the observations in exercised rats of enhanced neuronal responses as well as higher immobility responses in the re-test are consistent with the reportedly improved cognitive performance in these animals. Thus, improved stress coping in exercised subjects seems to involve enhanced cognitive capabilities possibly resulting from distinct epigenetic mechanisms in dentate gyrus neurons.

The immature dentate gyrus represents a shared phenotype of mouse models of epilepsy and psychiatric disease.

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Shin, Rick; Kobayashi, Katsunori; Hagihara, Hideo; Kogan, Jeffrey H; Miyake, Shinichi; Tajinda, Katsunori; Walton, Noah M; Gross, Adam K; Heusner, Carrie L; Chen, Qian; Tamura, Kouichi; Miyakawa, Tsuyoshi; Matsumoto, Mitsuyuki

2013-06-01

There is accumulating evidence to suggest psychiatric disorders, such as bipolar disorder and schizophrenia, share common etiologies, pathophysiologies, genetics, and drug responses with many of the epilepsies. Here, we explored overlaps in cellular/molecular, electrophysiological, and behavioral phenotypes between putative mouse models of bipolar disorder/schizophrenia and epilepsy. We tested the hypothesis that an immature dentate gyrus (iDG), whose association with psychosis in patients has recently been reported, represents a common phenotype of both diseases. Behaviors of calcium/calmodulin-dependent protein kinase II alpha (α-CaMKII) heterozygous knock-out (KO) mice, which are a representative bipolar disorder/schizophrenia model displaying iDG, and pilocarpine-treated mice, which are a representative epilepsy model, were tested followed by quantitative polymerase chain reaction (qPCR)/immunohistochemistry for mRNA/protein expression associated with an iDG phenotype. In vitro electrophysiology of dentate gyrus granule cells (DG GCs) was examined in pilocarpine-treated epileptic mice. The two disease models demonstrated similar behavioral deficits, such as hyperactivity, poor working memory performance, and social withdrawal. Significant reductions in mRNA expression and immunoreactivity of the mature neuronal marker calbindin and concomitant increases in mRNA expression and immunoreactivity of the immature neuronal marker calretinin represent iDG signatures that are present in both mice models. Electrophysiologically, we have confirmed that DG GCs from pilocarpine-treated mice represent an immature state. A significant decrease in hippocampal α-CaMKII protein levels was also found in both models. Our data have shown iDG signatures from mouse models of both bipolar disorder/schizophrenia and epilepsy. The evidence suggests that the iDG may, in part, be responsible for the abnormal behavioral phenotype, and that the underlying pathophysiologies in epilepsy

Repeated Neck Restraint Stress Bidirectionally Modulates Excitatory Transmission in the Dentate Gyrus and Performance in a Hippocampus-dependent Memory Task.

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Spyrka, Jadwiga; Hess, Grzegorz

2018-05-21

The consequences of stress depend on characteristics of the stressor, including the duration of exposure, severity, and predictability. Exposure of mice to repeated neck restraint has been shown to bidirectionally modulate the potential for long-term potentiation (LTP) in the dentate gyrus (DG) in a manner dependent on the number of restraint repetitions, but the influence of repeated brief neck restraint on electrophysiology of single DG neurons has not yet been investigated. Here, we aimed at finding the effects of 1, 3, 7, 14, or 21 daily neck restraint sessions lasting 10 min on electrophysiological characteristics of DG granule cells as well as excitatory and inhibitory synaptic inputs to these neurons. While the excitability of DG granule cells and inhibitory synaptic transmission were unchanged, neck restraint decreased the frequency of spontaneous excitatory currents after three repetitions but enhanced it after 14 and 21 repetitions. The consequences of repeated neck restraint on hippocampus-dependent memory were investigated using the object location test (OLT). Neck restraint stress impaired cognitive performance in the OLT after three repetitions but improved it after 14 and 21 repetitions. Mice subjected to three neck restraint sessions displayed an increase in the measures of depressive and anxiety-like behaviors, however, prolongation of the exposure to neck restraint resulted in a gradual decline in the intensity of these measures. These data indicate that stress imposed by an increasing number of repeated neck restraint episodes bidirectionally modulates both excitatory synaptic transmission in the DG and cognitive performance in the object location memory task. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

The presence of PHB granules in cytoplasm protects non-halophilic bacterial cells against the harmful impact of hypertonic environments.

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Obruca, Stanislav; Sedlacek, Petr; Mravec, Filip; Krzyzanek, Vladislav; Nebesarova, Jana; Samek, Ota; Kucera, Dan; Benesova, Pavla; Hrubanova, Kamila; Milerova, Miluse; Marova, Ivana

2017-10-25

Numerous prokaryotes accumulate polyhydroxybutyrate (PHB) intracellularly as a storage material. It has also been proposed that PHB accumulation improves bacterial stress resistance. Cupriavidus necator and its PHB non-accumulating mutant were employed to investigate the protective role of PHB under hypertonic conditions. The presence of PHB granules enhanced survival of the bacteria after exposure to hypertonic conditions. Surprisingly, when coping with such conditions, the bacteria did not utilize PHB to harvest carbon or energy, suggesting that, in the osmotic upshock of C. necator, the protective mechanism of PHB granules is not associated with their hydrolysis. The presence of PHB granules influenced the overall properties of the cells, since challenged PHB-free cells underwent massive plasmolysis accompanied by damage to the cell membrane and the leakage of cytoplasm content, while no such effects were observed in PHB containing bacteria. Moreover, PHB granules demonstrated "liquid-like" properties indicating that they can partially repair and stabilize cell membranes by plugging small gaps formed during plasmolysis. In addition, the level of dehydration and changes in intracellular pH in osmotically challenged cells were less pronounced for PHB-containing cultures, demonstrating the important role of PHB for bacterial survival under hyperosmotic conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of the Polyhydroxybutyrate Granules in Mammalian Cultured Cells

OpenAIRE

Elustondo, Pia; Zakharian, Eleonora; Pavlov, Evgeny

2012-01-01

Poly-3-hydroxybutyrate (PHB) is a biological polyester present in bacteria and eukaryotic cells. Long-chain (or storage) sPHB (up to 100,000 residues) is typically present in PHB-accumulating bacteria and localized in specialized granules known as carbonosomes. In these organisms, sPHB plays a major role as carbon and energy storage. On the other hand, short-chain (or complexed) cPHB (10–100 residues) is present in eukaryotic organisms, including mammals as well as in many bacteria. Previous ...

Retrograde monosynaptic tracing reveals the temporal evolution of inputs onto new neurons in the adult dentate gyrus and olfactory bulb

Science.gov (United States)

Deshpande, Aditi; Bergami, Matteo; Ghanem, Alexander; Conzelmann, Karl-Klaus; Lepier, Alexandra; Götz, Magdalena; Berninger, Benedikt

2013-01-01

Identifying the connectome of adult-generated neurons is essential for understanding how the preexisting circuitry is refined by neurogenesis. Changes in the pattern of connectivity are likely to control the differentiation process of newly generated neurons and exert an important influence on their unique capacity to contribute to information processing. Using a monosynaptic rabies virus-based tracing technique, we studied the evolving presynaptic connectivity of adult-generated neurons in the dentate gyrus (DG) of the hippocampus and olfactory bulb (OB) during the first weeks of their life. In both neurogenic zones, adult-generated neurons first receive local connections from multiple types of GABAergic interneurons before long-range projections become established, such as those originating from cortical areas. Interestingly, despite fundamental similarities in the overall pattern of evolution of presynaptic connectivity, there were notable differences with regard to the development of cortical projections: although DG granule neuron input originating from the entorhinal cortex could be traced starting only from 3 to 5 wk on, newly generated neurons in the OB received input from the anterior olfactory nucleus and piriform cortex already by the second week. This early glutamatergic input onto newly generated interneurons in the OB was matched in time by the equally early innervations of DG granule neurons by glutamatergic mossy cells. The development of connectivity revealed by our study may suggest common principles for incorporating newly generated neurons into a preexisting circuit. PMID:23487772

Glucose Toxic Effects on Granulation Tissue Productive Cells: The Diabetics’ Impaired Healing

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Jorge Berlanga-Acosta

2013-01-01

Full Text Available Type 2 diabetes mellitus is a metabolic noncommunicable disease with an expanding pandemic magnitude. Diabetes predisposes to lower extremities ulceration and impairs the healing process leading to wound chronification. Diabetes also dismantles innate immunity favoring wound infection. Amputation is therefore acknowledged as one of the disease’s complications. Hyperglycemia is the proximal detonator of systemic and local toxic effectors including proinflammation, acute-phase proteins elevation, and spillover of reactive oxygen and nitrogen species. Insulin axis deficiency weakens wounds’ anabolism and predisposes to inflammation. The systemic accumulation of advanced glycation end-products irreversibly impairs the entire physiology from cells-to-organs. These factors in concert hamper fibroblasts and endothelial cells proliferation, migration, homing, secretion, and organization of a productive granulation tissue. Diabetic wound bed may turn chronically inflammed, procatabolic, and an additional source of circulating pro-inflammatory cytokines, establishing a self-perpetuating loop. Diabetic fibroblasts and endothelial cells may bear mitochondrial damages becoming prone to apoptosis, which impairs granulation tissue cellularity and perfusion. Endothelial progenitor cells recruitment and tubulogenesis are also impaired. Failure of wound reepithelialization remains a clinical challenge while it appears to be biologically multifactorial. Ulcer prevention by primary care surveillance, education, and attention programs is of outmost importance to reduce worldwide amputation figures.

Visualization of cytolytic T cell differentiation and granule exocytosis with T cells from mice expressing active fluorescent granzyme B.

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Pierre Mouchacca

Full Text Available To evaluate acquisition and activation of cytolytic functions during immune responses we generated knock in (KI mice expressing Granzyme B (GZMB as a fusion protein with red fluorescent tdTomato (GZMB-Tom. As for GZMB in wild type (WT lymphocytes, GZMB-Tom was absent from naïve CD8 and CD4 T cells in GZMB-Tom-KI mice. It was rapidly induced in most CD8 T cells and in a subpopulation of CD4 T cells in response to stimulation with antibodies to CD3/CD28. A fraction of splenic NK cells expressed GZMB-Tom ex vivo with most becoming positive upon culture in IL-2. GZMB-Tom was present in CTL granules and active as a protease when these degranulated into cognate target cells, as shown with target cells expressing a specific FRET reporter construct. Using T cells from mice expressing GZMB-Tom but lacking perforin, we show that the transfer of fluorescent GZMB-Tom into target cells was dependent on perforin, favoring a role for perforin in delivery of GZMB at the target cells' plasma membranes. Time-lapse video microscopy showed Ca++ signaling in CTL upon interaction with cognate targets, followed by relocalization of GZMB-Tom-containing granules to the synaptic contact zone. A perforin-dependent step was next visualized by the fluorescence signal from the non-permeant dye TO-PRO-3 at the synaptic cleft, minutes before the labeling of the target cell nucleus, characterizing a previously undescribed synaptic event in CTL cytolysis. Transferred OVA-specific GZMB-Tom-expressing CD8 T cells acquired GZMB-Tom expression in Listeria monocytogenes-OVA infected mice as soon as 48h after infection. These GZMB-Tom positive CD8 T cells localized in the splenic T-zone where they interacted with CD11c positive dendritic cells (DC, as shown by GZMB-Tom granule redistribution to the T/DC contact zone. GZMB-Tom-KI mice thus also provide tools to visualize acquisition and activation of cytolytic function in vivo.

Failure of Neuronal Maturation in Alzheimer Disease Dentate Gyrus

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Li, Bin; Yamamori, Hidenaga; Tatebayashi, Yoshitaka; Shafit-Zagardo, Bridget; Tanimukai, Hitoshi; Chen, She; Iqbal, Khalid; Grundke-Iqbal, Inge

2011-01-01

The dentate gyrus, an important anatomic structure of the hippocampal formation, is one of the major areas in which neurogenesis takes place in the adult mammalian brain. Neurogenesis in the dentate gyrus is thought to play an important role in hippocampus-dependent learning and memory. Neurogenesis has been reported to be increased in the dentate gyrus of patients with Alzheimer disease, but it is not known whether the newly generated neurons differentiate into mature neurons. In this study, the expression of the mature neuronal marker high molecular weight microtubule-associated protein (MAP) isoforms MAP2a and b was found to be dramatically decreased in Alzheimer disease dentate gyrus, as determined by immunohistochemistry and in situ hybridization. The total MAP2, including expression of the immature neuronal marker, the MAP2c isoform, was less affected. These findings suggest that newly generated neurons in Alzheimer disease dentate gyrus do not become mature neurons, although neuroproliferation is increased. PMID:18091557

3β-Methyl-Neurosteroid Analogs are Preferential Positive Allosteric Modulators and Direct Activators of Extrasynaptic δGABA-A Receptors in the Hippocampus Dentate Gyrus Subfield.

Science.gov (United States)

Chuang, Shu-Hui; Reddy, Doodipala Samba

2018-03-30

Neurosteroids are powerful modulators of GABA-A receptors. Ganaxolone (3α-hydroxy-3β-methyl-5α-pregnan-20-one, GX) and synthetic analogs of the neurosteroid allopregnanolone (AP) are designed to treat epilepsy and related conditions. However, their precise mechanism of action in native neurons remains unclear. Here, we sought to determine the mode of action of GX and its analogs at GABA-A receptors in native hippocampal neurons by analyzing extrasynaptic receptor-mediated tonic currents and synaptic receptor-mediated phasic currents. Concentration-response profiles of GX were determined in two cell types: δ-containing dentate gyrus granule cells (DGGCs) and γ2-containing CA1 pyramidal cells (CA1PCs). GX produced significantly greater potentiation of the GABA-A receptor-activated chloride currents in DGGCs (500%) than CA1PCs (200%). In the absence of GABA, GX evoked 2-fold greater inward currents in DGGCs than CA1PCs, which were 2-fold greater than AP within DGGCs. In hippocampus slices, GX potentiated and directly activated tonic currents in DGGCs. These responses were significantly diminished in DGGCs from δ-subunit knockout (δKO) mice, confirming GX's selectivity for δGABA-A receptors. Like AP, GX potentiation of tonic currents was prevented by protein kinase C inhibition. Furthermore, GX's protection against hippocampus kindled seizures was significantly diminished in δKO mice. GX analogs exhibited greater potency and efficacy than GX on δGABA-A receptor-mediated tonic inhibition. In summary, these results provide strong evidence that GX and its analogs are preferential allosteric modulators and direct activators of extrasynaptic δGABA-A receptors regulating network inhibition and seizures in the dentate gyrus. Therefore, these findings provide a mechanistic rationale for the clinical use of synthetic neurosteroids in epilepsy and seizure disorders. The American Society for Pharmacology and Experimental Therapeutics.

Secretory granule formation and membrane recycling by the trans-Golgi network in adipokinetic cells of Locusta migratoria in relation to flight and rest.

Science.gov (United States)

Diederen, J H; Vullings, H G

1995-03-01

The influence of flight activity on the formation of secretory granules and the concomitant membrane recycling by the trans-Golgi network in the peptidergic neurosecretory adipokinetic cells of Locusta migratoria was investigated by means of ultrastructural morphometric methods. The patterns of labelling of the trans-Golgi network by the exogenous adsorptive endocytotic tracer wheat-germ agglutinin-conjugated horse-radish peroxidase and by the endogenous marker enzyme acid phosphatase were used as parameters and were measured by an automatic image analysis system. The results show that endocytosed fragments of plasma membrane with bound peroxidase label were transported to the trans-Golgi network and used to build new secretory granules. The amounts of peroxidase and especially of acid phosphatase within the trans-Golgi network showed a strong tendency to be smaller in flight-stimulated cells than in non-stimulated cells. The amounts of acid phosphatase in the immature secretory granules originating from the trans-Golgi network were significantly smaller in stimulated cells. The number of immature secretory granules positive for acid phosphatase tended to be higher in stimulated cells. Thus, flight stimulation of adipokinetic cells for 1 h influences the functioning of the trans-Golgi network; this most probably results in a slight enhancement of the production of secretory granules by the trans-Golgi network.

Hippocampal development in the rat: cytogenesis and morphogenesis examined with autoradiography and low-level x-irradiation

International Nuclear Information System (INIS)

Bayer, S.A.; Altman, J.

1974-01-01

The cytogenesis and morphogenesis of the rat hippocampus was examined with the techniques of 3 H-thymidine autoradiography, cell pyknosis produced by low-level x-irradiation, and quantitative histology. The procedure of progressively delayed cumulative labelling was used for autoradiography. Groups of rats were injected with four successive daily doses of 3 H-thymidine during non-overlapping periods ranging from birth to day 19. They were killed at 60 days of age, and the percentage of labelled cells was determined. Cell pyknosis in Ammon's horn reaches a maximal level prenatally and declines rapidly during the early postnatal period. Cell pyknosis in the dentate gyrus reaches its highest level during the second postnatal week and declines gradually with some radiosensitive cells still present in the adult. Immature granule cells are also at their highest level during the second postnatal week, while mature granule cells gradually accumulate to attain asymptotic levels at around two months of age. The alignment of the pyramidal cells to form the characteristic curvature of Ammon's horn occurs shortly after pyramidal cell cytogenesis is completed. Mechanisms for the morphological development of the dentate gyrus along with a consideration of the possible migratory route of granule cell precursors are discussed. (U.S.)

Neuroadaptations in the dentate gyrus following contextual cued reinstatement of methamphetamine seeking.

Science.gov (United States)

Takashima, Yoshio; Fannon, McKenzie J; Galinato, Melissa H; Steiner, Noah L; An, Michelle; Zemljic-Harpf, Alice E; Somkuwar, Sucharita S; Head, Brian P; Mandyam, Chitra D

2018-02-13

Abstinence from unregulated methamphetamine self-administration increases hippocampal dependent, context-driven reinstatement of methamphetamine seeking. The current study tested the hypothesis that alterations in the functional properties of granule cell neurons (GCNs) in the dentate gyrus (DG) of the hippocampus in concert with altered expression of synaptic plasticity-related proteins and ultrastructural changes in the DG are associated with enhanced context-driven methamphetamine-seeking behavior. Whole-cell patch-clamp recordings were performed in acute brain slices from methamphetamine naïve (controls) and methamphetamine experienced animals (during acute withdrawal, during abstinence, after extinction and after reinstatement). Spontaneous excitatory postsynaptic currents (sEPSCs) and intrinsic excitability were recorded from GCNs. Reinstatement of methamphetamine seeking increased sEPSC frequency and produced larger amplitude responses in GCNs compared to controls and all other groups. Reinstatement of methamphetamine seeking reduced spiking capability in GCNs compared to controls, and all other groups, as indicated by reduced intrinsic spiking elicited by increasing current injections, membrane resistance and fast after hyperpolarization. In rats that reinstated methamphetamine seeking, these altered electrophysiological properties of GCNs were associated with enhanced expression of Fos, GluN2A subunits and PSD95 and reduced expression of GABA A subunits in the DG and enhanced expression of synaptic PSD in the molecular layer. The alterations in functional properties of GCNs and plasticity related proteins in the DG paralleled with no changes in structure of microglial cells in the DG. Taken together, our results demonstrate that enhanced reinstatement of methamphetamine seeking results in alterations in intrinsic spiking and spontaneous glutamatergic synaptic transmission in the GCNs and concomitant increases in neuronal activation of GCNs, and expression

N-methyl-D-aspartate promotes the survival of cerebellar granule cells: pharmacological characterization

DEFF Research Database (Denmark)

Balázs, R; Hack, N; Jørgensen, Ole Steen

1989-01-01

The survival of cerebellar granule cells in culture is promoted by chronic exposure to N-methyl-D-aspartate (NMDA). The effect is due to the stimulation of 'conventional' NMDA receptor-ionophore complex: it is concentration dependent, voltage dependent and blocked by the selective antagonists D-2...

Dentate gyrus progenitor cell proliferation after the onset of spontaneous seizures in the tetanus toxin model of temporal lobe epilepsy.

Science.gov (United States)

Jiruska, Premysl; Shtaya, Anan B Y; Bodansky, David M S; Chang, Wei-Chih; Gray, William P; Jefferys, John G R

2013-06-01

Temporal lobe epilepsy alters adult neurogenesis. Existing experimental evidence is mainly from chronic models induced by an initial prolonged status epilepticus associated with substantial cell death. In these models, neurogenesis increases after status epilepticus. To test whether status epilepticus is necessary for this increase, we examined precursor cell proliferation and neurogenesis after the onset of spontaneous seizures in a model of temporal lobe epilepsy induced by unilateral intrahippocampal injection of tetanus toxin, which does not cause status or, in most cases, detectable neuronal loss. We found a 4.5 times increase in BrdU labeling (estimating precursor cells proliferating during the 2nd week after injection of toxin and surviving at least up to 7days) in dentate gyri of both injected and contralateral hippocampi of epileptic rats. Radiotelemetry revealed that the rats experienced 112±24 seizures, lasting 88±11s each, over a period of 8.6±1.3days from the first electrographic seizure. On the first day of seizures, their duration was a median of 103s, and the median interictal period was 23min, confirming the absence of experimentally defined status epilepticus. The total increase in cell proliferation/survival was due to significant population expansions of: radial glial-like precursor cells (type I; 7.2×), non-radial type II/III neural precursors in the dentate gyrus stem cell niche (5.6×), and doublecortin-expressing neuroblasts (5.1×). We conclude that repeated spontaneous brief temporal lobe seizures are sufficient to promote increased hippocampal neurogenesis in the absence of status epilepticus. Copyright © 2013 Elsevier Inc. All rights reserved.

The dentate nucleus in children: normal development and patterns of disease

Energy Technology Data Exchange (ETDEWEB)

McErlean, Aoife; Abdalla, Khaled; Donoghue, Veronica; Ryan, Stephanie [Children' s University Hospital, Radiology Department, Dublin (Ireland)

2010-03-15

The dentate nuclei lie deep within the cerebellum and play a vital role in the pathways involved in fine motor control and coordination. They are susceptible to a variety of diseases. Some pathological processes preferentially affect the dentate nuclei, while concomitant basal ganglia or white matter involvement can be a striking finding in others. A familiarity with the normal appearance of the dentate nuclei at different ages in combination with the radiological distribution of pathology in the brain allows the paediatric radiologist to develop a logical approach to the interpretation of MR imaging of these deep cerebellar nuclei. In this article we review the normal appearance and MR features of the dentate nuclei, including changes that are seen with myelination. We describe the specific imaging characteristics of childhood diseases that involve the dentate nuclei, and develop a systematic approach to the differential diagnosis of dentate nucleus abnormalities on MR imaging. (orig.)

The dentate nucleus in children: normal development and patterns of disease

International Nuclear Information System (INIS)

McErlean, Aoife; Abdalla, Khaled; Donoghue, Veronica; Ryan, Stephanie

2010-01-01

The dentate nuclei lie deep within the cerebellum and play a vital role in the pathways involved in fine motor control and coordination. They are susceptible to a variety of diseases. Some pathological processes preferentially affect the dentate nuclei, while concomitant basal ganglia or white matter involvement can be a striking finding in others. A familiarity with the normal appearance of the dentate nuclei at different ages in combination with the radiological distribution of pathology in the brain allows the paediatric radiologist to develop a logical approach to the interpretation of MR imaging of these deep cerebellar nuclei. In this article we review the normal appearance and MR features of the dentate nuclei, including changes that are seen with myelination. We describe the specific imaging characteristics of childhood diseases that involve the dentate nuclei, and develop a systematic approach to the differential diagnosis of dentate nucleus abnormalities on MR imaging. (orig.)

Nonreutilizaton of adrenal chromaffin granule membranes following secretion

International Nuclear Information System (INIS)

Nobiletti, J.B.

1985-01-01

The intracellular postexocytotic fate of the adrenal chromaffin granule membrane (reutilization vs. nonreutilization) was addressed through two experimental approaches. First, ( 3 H) leucine pulse-chase labeling experiments were conducted in two systems - the isolated retrograde perfused cat adrenal gland and cultured bovine adrenal chromaffin cells to compare chromaffin granule soluble dopamine-B-hydroxylase (DBH) turnover (marker for granule soluble content turnover) to that of membrane-bound DBH (marker for granule membrane turnover). Experiments in cat adrenal glands showed that at all chase periods the granule distribution of radiolabeled DBH was in agreement with the DBH activity distribution (73% membrane-bound/27% soluble) - a result consistent with parallel turnover of soluble and membrane-bound DBH. Experiments in cultured bovine cells showed that labeled soluble and membrane-bound DBH had parallel turnover patterns and at all chase period, the distribution of radiolabeled DBH between the soluble contents and membranes was similar to the DBH activity distribution (50% soluble/50% membrane-bound). The above experiments showed that the soluble contents and membranes turnover in parallel and are consistent with nonreutilization of chromaffin granule membranes following exocytosis. Isolated retrograde perfused bovine adrenal glands were subjected to repetitive acetylcholine stimulation to induce exocytosis and then the dense and less-dense chromaffin granule fractions were isolated. Since both approaches gave results consistent with membrane nonreutilization, the authors conclude that once a chromaffin granule is involved in exocytosis, its membrane is not reutilized for the further synthesis, storage, and secretion of catecholamines

AMP Kinase Activation Alters Oxidant-Induced Stress Granule Assembly by Modulating Cell Signaling and Microtubule Organization.

Science.gov (United States)

Mahboubi, Hicham; Koromilas, Antonis E; Stochaj, Ursula

2016-10-01

Eukaryotic cells assemble stress granules (SGs) when translation initiation is inhibited. Different cell signaling pathways regulate SG production. Particularly relevant to this process is 5'-AMP-activated protein kinase (AMPK), which functions as a stress sensor and is transiently activated by adverse physiologic conditions. Here, we dissected the role of AMPK for oxidant-induced SG formation. Our studies identified multiple steps of de novo SG assembly that are controlled by the kinase. Single-cell analyses demonstrated that pharmacological AMPK activation prior to stress exposure changed SG properties, because the granules became more abundant and smaller in size. These altered SG characteristics correlated with specific changes in cell survival, cell signaling, cytoskeletal organization, and the abundance of translation initiation factors. Specifically, AMPK activation increased stress-induced eukaryotic initiation factor (eIF) 2α phosphorylation and reduced the concentration of eIF4F complex subunits eIF4G and eIF4E. At the same time, the abundance of histone deacetylase 6 (HDAC6) was diminished. This loss of HDAC6 was accompanied by increased acetylation of α-tubulin on Lys40. Pharmacological studies further confirmed this novel AMPK-HDAC6 interplay and its importance for SG biology. Taken together, we provide mechanistic insights into the regulation of SG formation. We propose that AMPK activation stimulates oxidant-induced SG formation but limits their fusion into larger granules. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Arachnoid granulation affected by subarachnoid hemorrhage

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R.P. Chopard

1993-11-01

Full Text Available The purpose of this study was to investigate using light microscopy the fibro-cellular components of arachnoid granulations affected by mild and severe subarachnoid hemorrage. The erythrocytes were in the channels delimitated by collagenous and elastic bundles and arachnoid cells, showing their tortuous and intercommunicating row from the pedicle to the fibrous capsule. The core portion of the pedicle and the center represented a principal route to the bulk outflow of cerebrospinal fluid and erythrocytes. In the severe hemorrhage, the fibrocellular components are desorganized, increasing the extracellular channels. We could see arachnoid granulations without erythrocytes, which cells showed big round nucleous suggesting their transformation into phagocytic cells.

Endothelin-1 stimulates the release of preloaded [3H]D-aspartate from cultured cerebellar granule cells

International Nuclear Information System (INIS)

Lin, W.W.; Lee, C.Y.; Chuang, D.M.

1990-01-01

We have recently reported that endothelin-1 (ET) induces phosphoinositide hydrolysis in primary cultures of rat cerebellar granule cells. Here we found that ET in a dose-dependent manner (1-30 nM) stimulated the release of preloaded [ 3 H]D-aspartate from granule cells. The ET-induced aspartate release was completely blocked in the absence of extracellular Ca 2+ , but was unaffected by 1 mM Co 2+ or 1 microM dihydropyridine derivatives (nisoldipine and nimodipine). At higher concentration (10 microM) of nisoldipine and nimodipine, the release was partially inhibited. Short-term pretreatment of cells with phorbol 12,13-dibutyrate (PDBu) potentiated the ET-induced aspartate release, while long-term pretreatment with PDBu attenuated the release. Long-term exposure of cells to pertussis toxin (PTX), on the other hand, potentiated the ET-induced effects. Our results suggest that ET has a neuromodulatory function in the central nervous system

PHB granules are attached to the nucleoid via PhaM in Ralstonia eutropha.

Science.gov (United States)

Wahl, Andreas; Schuth, Nora; Pfeiffer, Daniel; Nussberger, Stephan; Jendrossek, Dieter

2012-11-16

Poly(3-hydroxybutyrate) (PHB) granules are important storage compounds of carbon and energy in many prokaryotes which allow survival of the cells in the absence of suitable carbon sources. Formation and subcellular localization of PHB granules was previously assumed to occur randomly in the cytoplasm of PHB accumulating bacteria. However, contradictionary results on subcellular localization of PHB granules in Ralstonia eutropha were published, recently. Here, we provide evidence by transmission electron microscopy that PHB granules are localized in close contact to the nucleoid region in R. eutropha during growth on nutrient broth. Binding of PHB granules to the nucleoid is mediated by PhaM, a PHB granule associated protein with phasin-like properties that is also able to bind to DNA and to phasin PhaP5. Over-expression of PhaM resulted in formation of many small PHB granules that were always attached to the nucleoid region. In contrast, PHB granules of ∆phaM strains became very large and distribution of granules to daughter cells was impaired. Association of PHB granules to the nucleoid region was prevented by over-expression of PhaP5 and clusters of several PHB granules were mainly localized near the cell poles. Subcellular localization of PHB granules is controlled in R. eutropha and depends on the presence and concentrations of at least two PHB granule associated proteins, PhaM and PhaP5.

Dynamic properties of sensory stimulation evoked responses in mouse cerebellar granule cell layer and molecular layer.

Science.gov (United States)

Bing, Yan-Hua; Zhang, Guang-Jian; Sun, Lei; Chu, Chun-Ping; Qiu, De-Lai

2015-01-12

Sensory information coming from climbing fiber and mossy fiber-granule cell pathways, generates motor-related outputs according to internal rules of integration and computation in the cerebellar cortex. However, the dynamic properties of sensory information processing in mouse cerebellar cortex are less understood. Here, we studied the dynamic properties of sensory stimulation-evoked responses in the cerebellar granule cell layer (GCL) and molecular layer (ML) by electrophysiological recordings method. Our data showed that air-puff stimulation (5-10 ms in duration) of the ipsilateral whisker pad evoked single-peak responses in the GCL and ML; whereas a duration of stimulation ≥30 ms in GCL and ≥60 ms in ML, evoked double-peak responses that corresponded with stimulation-on and -off responses via mossy fiber pathway. The highest frequency of stimulation train for evoking GCL responses was 33 Hz. In contrast, the highest frequency of stimulation train for evoking ML responses was 4 Hz. These results indicate that the cerebellar granule cells transfer the high-fidelity sensory information from mossy fibers, which is cut-off by molecular layer interneurons (MLIs). Our results suggest that the MLIs network acts as a low-pass filter during the processing of high-frequency sensory information. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A review on granules initiation and development inside UASB Reactor and the main factors affecting granules formation process

Energy Technology Data Exchange (ETDEWEB)

Habeeb, S.A.; Latiff, Ab Aziz Bin Abdul; Daud, Zawawi Bin; Ahmad, Zulkifli Bin [Civil and Environmental Engineering, University Tun Hussein Onn Malaysia (Malaysia)

2011-07-01

Decades of investigations and explorations in the field of anaerobic wastewater treatment have resulted in significant indications about the role importance of sludge granules in biodegradation anaerobic process. It is believed that the development of anaerobic granules is reflecting an important role on the performance of reactor. An overview on the concept of up-flow anaerobic sludge bed (UASB) reactor operation as well as the main parts that reactor consists of is briefly explained in this paper, whereas the major theories of anaerobic granules formation are listed by related researchers. The correlations and compositions of such sludge granule have been specifically explained. It is believed that the extracellular polymer (ECP) is totally responsible of bacterial cell correlations and the formation of bacterial communities in the form of granules. In addition, the dependable factors for the performance of anaerobic granules formation process e.g. temperature, organic loading rate, pH, and alkalinity, nutrients, and cations and heavy metals have been discussed in this paper. Strong evidences proved that the process of gas production in the form of biogas is related to the methanogens activities, which are practically found in the core of granules. The aim of this review is to explore and assess the mechanisms of granules initiation and development inside UASB reactor.

The survival of cultured mouse cerebellar granule cells is not dependent on elevated potassium-ion concentration

DEFF Research Database (Denmark)

Mogensen, Helle Smidt; Hack, N; Balázs, R

1994-01-01

The effects of K(+)-induced membrane depolarization were studied on the survival and biochemical parameters in mouse and rat cerebellar granule cells grown in micro-well cultures. Cell numbers were determined by estimating DNA content using the Hoechst 33258 fluorochrome binding assay. DNA from d...

MMP-13 regulates growth of wound granulation tissue and modulates gene expression signatures involved in inflammation, proteolysis, and cell viability.

Directory of Open Access Journals (Sweden)

Mervi Toriseva

Full Text Available Proteinases play a pivotal role in wound healing by regulating cell-matrix interactions and availability of bioactive molecules. The role of matrix metalloproteinase-13 (MMP-13 in granulation tissue growth was studied in subcutaneously implanted viscose cellulose sponge in MMP-13 knockout (Mmp13(-/- and wild type (WT mice. The tissue samples were harvested at time points day 7, 14 and 21 and subjected to histological analysis and gene expression profiling. Granulation tissue growth was significantly reduced (42% at day 21 in Mmp13(-/- mice. Granulation tissue in Mmp13(-/- mice showed delayed organization of myofibroblasts, increased microvascular density at day 14, and virtual absence of large vessels at day 21. Gene expression profiling identified differentially expressed genes in Mmp13(-/- mouse granulation tissue involved in biological functions including inflammatory response, angiogenesis, cellular movement, cellular growth and proliferation and proteolysis. Among genes linked to angiogenesis, Adamts4 and Npy were significantly upregulated in early granulation tissue in Mmp13(-/- mice, and a set of genes involved in leukocyte motility including Il6 were systematically downregulated at day 14. The expression of Pdgfd was downregulated in Mmp13(-/- granulation tissue in all time points. The expression of matrix metalloproteinases Mmp2, Mmp3, Mmp9 was also significantly downregulated in granulation tissue of Mmp13(-/- mice compared to WT mice. Mmp13(-/- mouse skin fibroblasts displayed altered cell morphology and impaired ability to contract collagen gel and decreased production of MMP-2. These results provide evidence for an important role for MMP-13 in wound healing by coordinating cellular activities important in the growth and maturation of granulation tissue, including myofibroblast function, inflammation, angiogenesis, and proteolysis.

Sensorimotor Representations in Cerebellar Granule Cells in Larval Zebrafish Are Dense, Spatially Organized, and Non-temporally Patterned.

Science.gov (United States)

Knogler, Laura D; Markov, Daniil A; Dragomir, Elena I; Štih, Vilim; Portugues, Ruben

2017-05-08

A fundamental question in neurobiology is how animals integrate external sensory information from their environment with self-generated motor and sensory signals in order to guide motor behavior and adaptation. The cerebellum is a vertebrate hindbrain region where all of these signals converge and that has been implicated in the acquisition, coordination, and calibration of motor activity. Theories of cerebellar function postulate that granule cells encode a variety of sensorimotor signals in the cerebellar input layer. These models suggest that representations should be high-dimensional, sparse, and temporally patterned. However, in vivo physiological recordings addressing these points have been limited and in particular have been unable to measure the spatiotemporal dynamics of population-wide activity. In this study, we use both calcium imaging and electrophysiology in the awake larval zebrafish to investigate how cerebellar granule cells encode three types of sensory stimuli as well as stimulus-evoked motor behaviors. We find that a large fraction of all granule cells are active in response to these stimuli, such that representations are not sparse at the population level. We find instead that most responses belong to only one of a small number of distinct activity profiles, which are temporally homogeneous and anatomically clustered. We furthermore identify granule cells that are active during swimming behaviors and others that are multimodal for sensory and motor variables. When we pharmacologically change the threshold of a stimulus-evoked behavior, we observe correlated changes in these representations. Finally, electrophysiological data show no evidence for temporal patterning in the coding of different stimulus durations. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Late maturation of adult-born neurons in the temporal dentate gyrus.

Science.gov (United States)

Snyder, Jason S; Ferrante, Sarah C; Cameron, Heather A

2012-01-01

Hippocampal function varies along its septotemporal axis, with the septal (dorsal) pole more frequently involved in spatial learning and memory and the temporal (ventral) pole playing a greater role in emotional behaviors. One feature that varies across these subregions is adult neurogenesis. New neurons are more numerous in the septal hippocampus but are more active in the temporal hippocampus during water maze training. However, many other aspects of adult neurogenesis remain unexplored in the context of septal versus temporal subregions. In addition, the dentate gyrus contains another functionally important anatomical division along the transverse axis, with the suprapyramidal blade showing greater experience-related activity than the infrapyramidal blade. Here we ask whether new neurons differ in their rates of survival and maturation along the septotemporal and transverse axes. We found that neurogenesis is initially higher in the infrapyramidal than suprapyramidal blade, but these cells are less likely to survive, resulting in similar densities of neurons in the two blades by four weeks. Across the septotemporal axis, neurogenesis was higher in septal than temporal pole, while the survival rate of new neurons did not differ. Maturation was assessed by immunostaining for the neuronal marker, NeuN, which increases in expression level with maturation, and for the immediate-early gene, Arc, which suggests a neuron is capable of undergoing activity-dependent synaptic plasticity. Maturation occurred approximately 1-2 weeks earlier in the septal pole than in the temporal pole. This suggests that septal neurons may contribute to function sooner; however, the prolonged maturation of new temporal neurons may endow them with a longer window of plasticity during which their functions could be distinct from those of the mature granule cell population. These data point to subregional differences in new neuron maturation and suggest that changes in neurogenesis could alter

Linking macroscopic with microscopic neuroanatomy using synthetic neuronal populations.

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Schneider, Calvin J; Cuntz, Hermann; Soltesz, Ivan

2014-10-01

Dendritic morphology has been shown to have a dramatic impact on neuronal function. However, population features such as the inherent variability in dendritic morphology between cells belonging to the same neuronal type are often overlooked when studying computation in neural networks. While detailed models for morphology and electrophysiology exist for many types of single neurons, the role of detailed single cell morphology in the population has not been studied quantitatively or computationally. Here we use the structural context of the neural tissue in which dendritic trees exist to drive their generation in silico. We synthesize the entire population of dentate gyrus granule cells, the most numerous cell type in the hippocampus, by growing their dendritic trees within their characteristic dendritic fields bounded by the realistic structural context of (1) the granule cell layer that contains all somata and (2) the molecular layer that contains the dendritic forest. This process enables branching statistics to be linked to larger scale neuroanatomical features. We find large differences in dendritic total length and individual path length measures as a function of location in the dentate gyrus and of somatic depth in the granule cell layer. We also predict the number of unique granule cell dendrites invading a given volume in the molecular layer. This work enables the complete population-level study of morphological properties and provides a framework to develop complex and realistic neural network models.

Synaptic properties of SOM- and CCK-expressing cells in dentate gyrus interneuron networks.

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Savanthrapadian, Shakuntala; Meyer, Thomas; Elgueta, Claudio; Booker, Sam A; Vida, Imre; Bartos, Marlene

2014-06-11

Hippocampal GABAergic cells are highly heterogeneous, but the functional significance of this diversity is not fully understood. By using paired recordings of synaptically connected interneurons in slice preparations of the rat and mouse dentate gyrus (DG), we show that morphologically identified interneurons form complex neuronal networks. Synaptic inhibitory interactions exist between cholecystokinin (CCK)-expressing hilar commissural associational path (HICAP) cells and among somatostatin (SOM)-containing hilar perforant path-associated (HIPP) interneurons. Moreover, both interneuron types inhibit parvalbumin (PV)-expressing perisomatic inhibitory basket cells (BCs), whereas BCs and HICAPs rarely target HIPP cells. HICAP and HIPP cells produce slow, weak, and unreliable inhibition onto postsynaptic interneurons. The time course of inhibitory signaling is defined by the identity of the presynaptic and postsynaptic cell. It is the slowest for HIPP-HIPP, intermediately slow for HICAP-HICAP, but fast for BC-BC synapses. GABA release at interneuron-interneuron synapses also shows cell type-specific short-term dynamics, ranging from multiple-pulse facilitation at HICAP-HICAP, biphasic modulation at HIPP-HIPP to depression at BC-BC synapses. Although dendritic inhibition at HICAP-BC and HIPP-BC synapses appears weak and slow, channelrhodopsin 2-mediated excitation of SOM terminals demonstrates that they effectively control the activity of target interneurons. They markedly reduce the discharge probability but sharpen the temporal precision of action potential generation. Thus, dendritic inhibition seems to play an important role in determining the activity pattern of GABAergic interneuron populations and thereby the flow of information through the DG circuitry. Copyright © 2014 the authors 0270-6474/14/348197-13$15.00/0.

Autophagy meets fused in sarcoma-positive stress granules.

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Matus, Soledad; Bosco, Daryl A; Hetz, Claudio

2014-12-01

Mutations in fused in sarcoma and/or translocated in liposarcoma (FUS, TLS or FUS) are linked to familial cases of amyotrophic lateral sclerosis (ALS). Mutant FUS selectively accumulates into discrete cytosolic structures known as stress granules under various stress conditions. In addition, mutant FUS expression can alter the dynamics and morphology of stress granules. Although the link between mutant FUS and stress granules is well established, the mechanisms modulating stress granule formation and disassembly in the context of ALS are poorly understood. In this issue of Neurobiology of Aging, Ryu et al. uncover the impact of autophagy on the potential toxicity of mutant FUS-positive stress granules. The authors provide evidence indicating that enhanced autophagy activity reduces the number of stress granules, which in the case of cells containing mutant FUS-positive stress granules, is neuroprotective. Overall, this study identifies an intersection between the proteostasis network and alterations in RNA metabolism in ALS through the dynamic assembly and disassembly of stress granules. Copyright © 2014 Elsevier Inc. All rights reserved.

Temporal associations for spatial events: the role of the dentate gyrus.

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Morris, Andrea M; Curtis, Brian J; Churchwell, John C; Maasberg, David W; Kesner, Raymond P

2013-11-01

Previous research suggests that the dorsal dentate gyrus (DG) hippocampal subregion mediates spatial processing functions. However, a novel role for the DG in temporal processing for spatial information has begun to emerge based on the development of a computational model of neurogenesis. According to this model, adult born granule cells in the DG contribute to a temporal associative integration process for events presented closer in time. Currently, there is a paucity of behavioral evidence to support the temporal integration theory. Therefore, we developed a novel behavioral paradigm to investigate the role of the dDG in temporal integration for proximal and distal spatial events. Male Long-Evans rats were randomly assigned to a control group or to receive bilateral intracranial infusions of colchicine into the dDG. Following recovery from surgery, each rat was tested on a cued-recall of sequence paradigm. In this task, animals were allowed to explore identical objects placed in designated spatial locations on a cheeseboard maze across 2 days (e.g., Day 1: A and B; Day 2: C and D). One week later, animals were given a brief cue (A or C) followed by a preference test between spatial location B and D. Control animals had a significant preference for the spatial location previously paired with the cue (the temporal associate) whereas dDG lesioned animals failed to show a preference. These findings suggest that selective colchicine-induced dDG lesions are capable of disrupting the formation of temporal associations between spatial events presented close in time. Copyright © 2013 Elsevier B.V. All rights reserved.

Subchronic Crude Khat ( Catha edulis F.) Extract Administration ...

African Journals Online (AJOL)

People chew khat (Catha edulis F.), believing that it improves memory, ... Morphometric analysis revealed a significant reduction in weight of brain as well as ... properties of the dentate granule cells, including volume of the granular layer of ...

Early events of secretory granule formation in the rat parotid acinar cell under the influence of isoproterenol. An ultrastructural and lectin cytochemical study

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F D’Amico

2009-12-01

Full Text Available The events involved in the maturation process of acinar secretory granules of rat parotid gland were investigated ultrastructurally and cytochemically by using a battery of four lectins [Triticum vulgaris agglutinin (WGA, Ulex europaeus agglutinin I (UEA-I, Glycine max agglutinin (SBA, Arachys hypogaea agglutinin (PNA]. In order to facilitate the study, parotid glands were chronically stimulated with isoproterenol to induce secretion. Specimens were embedded in the Lowicryl K4M resin. The trans-Golgi network (TGN derived secretory granules, which we refer to as immature secretory granules, were found to be intermediate structures in the biogenesis process of the secretory granules in the rat parotid acinar cell. These early structures do not seem to be the immediate precursor of the mature secretory granules: in fact, a subsequent interaction process between these early immature granule forms and TGN elements seems to occur, leading, finally, to the mature granules. These findings could explain the origin of the polymorphic subpopulations of the secretory granules in the normal acinar cells of the rat parotid gland. The lectin staining patterns were characteristic of each lectin. Immature and mature secretory gran- ules were labelled with WGA, SBA, PNA, and lightly with UEA-I. Cis and intermediate cisternae of the Golgi apparatus were labelled with WGA, and trans cisternae with WGA and SBA.

Electroconvulsive stimulation results in long-term survival of newly generated hippocampal neurons in rats

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Olesen, Mikkel Vestergaard; Wörtwein, Gitta; Folke, Jonas

2017-01-01

Electroconvulsive stimulation (ECS) is one of the strongest stimulators of hippocampal neurogenesis in rodents that represents a plausible mechanism for the efficacy of electroconvulsive therapy (ECT) in major depressive disorder. Using design-based stereological cell counting, we recently...... in neurogenesis facilitates the behavioral outcome of the forced swim test (FST), an animal model of depression. The results showed that ECS in conjunction with CRS stimulates hippocampal neurogenesis, and that a significant quantity of the newly formed hippocampal neurons survives up to 12 months. The new Brd......U-positive neurons showed time-dependent attrition of ∼40% from day 1 to 3 months, with no further decline between 3 and 12 months. ECS did not affect the number of pre-existing dentate granule neurons or the volume of the dentate granule cell layer, suggesting no damaging effect of the treatment. Finally, we found...

Polyhydroxyalkanoate (PHA) Granules Have no Phospholipids

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Bresan, Stephanie; Sznajder, Anna; Hauf, Waldemar; Forchhammer, Karl; Pfeiffer, Daniel; Jendrossek, Dieter

2016-01-01

Polyhydroxybutyrate (PHB) granules, also designated as carbonosomes, are supra-molecular complexes in prokaryotes consisting of a PHB polymer core and a surface layer of structural and functional proteins. The presence of suspected phospholipids in the surface layer is based on in vitro data of isolated PHB granules and is often shown in cartoons of the PHB granule structure in reviews on PHB metabolism. However, the in vivo presence of a phospholipid layer has never been demonstrated. We addressed this topic by the expression of fusion proteins of DsRed2EC and other fluorescent proteins with the phospholipid-binding domain (LactC2) of lactadherin in three model organisms. The fusion proteins specifically localized at the cell membrane of Ralstonia eutropha but did not co-localize with PHB granules. The same result was obtained for Pseudomonas putida, a species that accumulates another type of polyhydroxyalkanoate (PHA) granules related to PHB. Notably, DsRed2EC-LactC2 expressed in Magnetospirillum gryphiswaldense was detected at the position of membrane-enclosed magnetosome chains and at the cytoplasmic membrane but not at PHB granules. In conclusion, the carbonosomes of representatives of α-proteobacteria, β-proteobacteria and γ-proteobacteria have no phospholipids in vivo and we postulate that the PHB/PHA granule surface layers in natural producers generally are free of phospholipids and consist of proteins only. PMID:27222167

Dentate gyrus network dysfunctions precede the symptomatic phase in a genetic mouse model of seizures

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Oana eToader

2013-08-01

Full Text Available Neuronal circuit disturbances that lead to hyperexcitability in the cortico-hippocampal network are one of the landmarks of temporal lobe epilepsy. The dentate gyrus (DG network plays an important role in regulating the excitability of the entire hippocampus by filtering and integrating information received via the perforant path. Here, we investigated possible epileptogenic abnormalities in the function of the DG neuronal network in the Synapsin II (Syn II knockout mouse (Syn II-/-, a genetic mouse model of epilepsy. Syn II is a presynaptic protein whose deletion in mice reproducibly leads to generalized seizures starting at the age of two months. We made use of a high-resolution microelectrode array (4096 electrodes and patch-clamp recordings, and found that in acute hippocampal slices of young pre-symptomatic (3-6 weeks-old Syn II-/- mice excitatory synaptic output of the mossy fibers is reduced. Moreover, we showed that the main excitatory neurons present in the polymorphic layer of the DG, hilar mossy cells, display a reduced excitability. We also provide evidence of a predominantly inhibitory regulatory output from mossy cells to granule cells, through feed-forward inhibition, and show that the excitatory-inhibitory ratio is increased in both pre-symptomatic and symptomatic Syn II-/- mice. These results support the key role of the hilar mossy neurons in maintaining the normal excitability of the hippocampal network and show that the late epileptic phenotype of the Syn II-/- mice is preceded by neuronal circuitry dysfunctions. Our data provide new insights into the mechanisms of epileptogenesis in the Syn II-/- mice and open the possibility for early diagnosis and therapeutic interventions.

Convergent evolution of germ granule nucleators: A hypothesis.

Science.gov (United States)

Kulkarni, Arpita; Extavour, Cassandra G

2017-10-01

Germ cells have been considered "the ultimate stem cell" because they alone, during normal development of sexually reproducing organisms, are able to give rise to all organismal cell types. Morphological descriptions of a specialized cytoplasm termed 'germ plasm' and associated electron dense ribonucleoprotein (RNP) structures called 'germ granules' within germ cells date back as early as the 1800s. Both germ plasm and germ granules are implicated in germ line specification across metazoans. However, at a molecular level, little is currently understood about the molecular mechanisms that assemble these entities in germ cells. The discovery that in some animals, the gene products of a small number of lineage-specific genes initiate the assembly (also termed nucleation) of germ granules and/or germ plasm is the first step towards facilitating a better understanding of these complex biological processes. Here, we draw on research spanning over 100years that supports the hypothesis that these nucleator genes may have evolved convergently, allowing them to perform analogous roles across animal lineages. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Zinc sulfide in intestinal cell granules of Ancylostoma caninum adults

Energy Technology Data Exchange (ETDEWEB)

Gianotti, A.J.; Clark, D.T.; Dash, J. (Portland State Univ., OR (USA))

1991-04-01

A source of confusion has existed since the turn of the century about the reddish brown, weakly birefringent 'sphaerocrystals' located in the intestines of strongyle nematodes, Strongylus and Ancylostoma. X-ray diffraction and energy dispersive spectrometric analyses were used for accurate determination of the crystalline order and elemental composition of the granules in the canine hookworm Ancylostoma caninum. The composition of the intestinal pigmented granules was identified unequivocally as zinc sulfide. It seems most probable that the granules serve to detoxify high levels of metallic ions (specifically zinc) present due to the large intake of host blood.

Protracted postnatal neurogenesis and radiosensitivity in the rabbit's dentate gyrus

International Nuclear Information System (INIS)

Gueneau, G.; Baille, V.; Dubos, M.; Court, L.

1986-01-01

In the hippocampal formation of a 3-month-old rabbit submitted to a 4.5 Gy gamma irradiation a cytologic study with light and electron microscopy allowed us to make clear the dentate gyrus particular radiosensitivity as soon as the first hours after irradiation. The pycnosis lesion observed in the subgranular zone has drawn our attention in particular. We apply ourselves to describe and precise the lesion and its evolution; thanks to an autoradiographic study, we have shown its link with late postnatal neurogenesis which goes on in this zone and at last we have used the subgranular cells 'radiosensitivity as a biological test allowing to compare the various rays' effects (gamma and neutron rays). In the brain of a one-month-old monkey submitted to a 4 Gy total irradiation the same pycnotic lesion is observed: 1) in the dentate gyrus's subgranular zone and 2) in the cerebellum's outer granular layer. These two postnatal proliferative zones remain particularly sensitive to ionizing radiations. (orig.)

Methamphetamine decreases dentate gyrus stem cell self-renewal and shifts the differentiation towards neuronal fate

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Sofia Baptista

2014-09-01

Full Text Available Methamphetamine (METH is a highly addictive psychostimulant drug of abuse that negatively interferes with neurogenesis. In fact, we have previously shown that METH triggers stem/progenitor cell death and decreases neuronal differentiation in the dentate gyrus (DG. Still, little is known regarding its effect on DG stem cell properties. Herein, we investigate the impact of METH on mice DG stem/progenitor cell self-renewal functions. METH (10 nM decreased DG stem cell self-renewal, while 1 nM delayed cell cycle in the G0/G1-to-S phase transition and increased the number of quiescent cells (G0 phase, which correlated with a decrease in cyclin E, pEGFR and pERK1/2 protein levels. Importantly, both drug concentrations (1 or 10 nM did not induce cell death. In accordance with the impairment of self-renewal capacity, METH (10 nM decreased Sox2+/Sox2+ while increased Sox2−/Sox2− pairs of daughter cells. This effect relied on N-methyl-d-aspartate (NMDA signaling, which was prevented by the NMDA receptor antagonist, MK-801 (10 μM. Moreover, METH (10 nM increased doublecortin (DCX protein levels consistent with neuronal differentiation. In conclusion, METH alters DG stem cell properties by delaying cell cycle and decreasing self-renewal capacities, mechanisms that may contribute to DG neurogenesis impairment followed by cognitive deficits verified in METH consumers.

Effect of sodium butyrate treatment on the granule morphology, histamine level and elemental content of the bone marrow-derived mast cell

Energy Technology Data Exchange (ETDEWEB)

Rydzynski, K. [Inst. of Occupational Medicine, Lodz (Poland); Dalen, H. [Bergen Univ. (Norway)

1994-12-31

Mast cells derived from the bone marrow of BALB/c mice (BMMC) were cultures and their growth ceased with sodium butyrate. Sodium butyrate treatment (1 mM, 4 days) caused maturation of the granules, and increased histamine content from approx. 1 pg/cell to 4 pg/cell. X-ray microanalysis revealed that maturation of the granules was accompanied by the increase in relative weight percent of sodium, phosphorus and sulphur, with concomitant decrease in chloride. The sulphur to potassium ratio increased three-fold in butyrate-treated mast cells. The existence of a different elemental composition during mast cell maturation may provide additional parameter for rapid discrimination of mast cell subpopulations. (author). 28 refs, 6 figs.

Who Regulates Whom? An Overview of RNA Granules and Viral Infections

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Natalia Poblete-Durán

2016-06-01

Full Text Available After viral infection, host cells respond by mounting an anti-viral stress response in order to create a hostile atmosphere for viral replication, leading to the shut-off of mRNA translation (protein synthesis and the assembly of RNA granules. Two of these RNA granules have been well characterized in yeast and mammalian cells, stress granules (SGs, which are translationally silent sites of RNA triage and processing bodies (PBs, which are involved in mRNA degradation. This review discusses the role of these RNA granules in the evasion of anti-viral stress responses through virus-induced remodeling of cellular ribonucleoproteins (RNPs.

Somatostatin receptors in rat hippocampus: localization to intrinsic neurons

International Nuclear Information System (INIS)

Palacios, J.M.; Reubi, J.C.; Maurer, R.

1986-01-01

The effect of neurotoxic chemical and electrolytical lesions on somatostatin (SS) receptor binding in the septo-hippocampal afferents, pyramidal and granule cells of the rat hippocampus was examined by autoradiography using the stable SS analogue 125 I-204-090 as radioligand. Electrolytical lesions of the septum did not result in modification of SS binding in the hippocampus. In contrast, both granule cell lesion with colchicine and pyramidal or pyramidal and granule cell lesions with increasing kainic acid doses did result in a specific decrease of binding in the dentate gyrus and hippocampus (CA 1 and CA 3 ). These results suggest that SS receptors in the hippocampus are probably associated with elements from intrinsic neurons. (Author)

Somato-synaptic variation of GABA(A) receptors in cultured murine cerebellar granule cells: investigation of the role of the alpha6 subunit.

Science.gov (United States)

Mellor, J R; Wisden, W; Randall, A D

2000-07-10

Electrophysiological investigation of cultured cerebellar murine granule cells revealed differences between the GABA(A) receptors at inhibitory synapses and those on the cell body. Specifically, mIPSCs decayed more rapidly than cell body receptors deactivated, the mean single channel conductance at the synapse (32 pS) was greater than that at cell body (21 pS) and only cell body receptors were sensitive to Zn(2+) (150 microM), which depressed response amplitude by 82+/-5% and almost doubled the rate of channel deactivation. The GABA(A) receptor alpha6 subunit is selectively expressed in cerebellar granule cells. Although concentrated at synapses, it is also found on extrasynaptic membranes. Using a mouse line (Deltaalpha6lacZ) lacking this subunit, we investigated its role in the somato-synaptic differences in GABA(A) receptor function. All differences between cell body and synaptic GABA(A) receptors observed in wild-type (WT) granule cells persisted in Deltaalpha6lacZ cells, thus demonstrating that they are not specifically due to the cellular distribution of the alpha6 subunit. However, mIPSCs from WT and Deltaalpha6lacZ cells differed in both their kinetics (faster decay in WT cells) and underlying single channel conductance (32 pS WT, 25 pS Deltaalpha6lacZ). This provides good evidence for a functional contribution of the alpha6 subunit to postsynaptic GABA(A) receptors in these cells. Despite this, deactivation kinetics of mIPSCs in WT and Deltaalpha6lacZ granule cells exhibited similar benzodiazepene (BDZ) sensitivity. This suggests that the enhanced BDZ-induced ataxia seen in Deltaalpha6lacZ mice may reflect physiological activity at extrasynaptic receptors which, unlike those at synapses, display differential BDZ-sensitivity in WT and Deltaalpha6lacZ granule cells (Jones, A.M., Korpi, E.R., McKernan, R.M., Nusser, Z., Pelz, R., Makela, R., Mellor, J.R., Pollard, S., Bahn, S., Stephenson, F.A., Randall, A.D., Sieghart, W., Somogyi, P., Smith, A.J.H., Wisden

Endothelin-1 stimulates the release of preloaded ( sup 3 H)D-aspartate from cultured cerebellar granule cells

Energy Technology Data Exchange (ETDEWEB)

Lin, W.W.; Lee, C.Y.; Chuang, D.M. (NIMH Neuroscience Center, Washington, DC (USA))

1990-03-16

We have recently reported that endothelin-1 (ET) induces phosphoinositide hydrolysis in primary cultures of rat cerebellar granule cells. Here we found that ET in a dose-dependent manner (1-30 nM) stimulated the release of preloaded ({sup 3}H)D-aspartate from granule cells. The ET-induced aspartate release was completely blocked in the absence of extracellular Ca{sup 2+}, but was unaffected by 1 mM Co{sup 2+} or 1 microM dihydropyridine derivatives (nisoldipine and nimodipine). At higher concentration (10 microM) of nisoldipine and nimodipine, the release was partially inhibited. Short-term pretreatment of cells with phorbol 12,13-dibutyrate (PDBu) potentiated the ET-induced aspartate release, while long-term pretreatment with PDBu attenuated the release. Long-term exposure of cells to pertussis toxin (PTX), on the other hand, potentiated the ET-induced effects. Our results suggest that ET has a neuromodulatory function in the central nervous system.

Adipose derived mesenchymal stem cells – Their osteogenicity and osteoblast in vitro mineralization on titanium granule carriers

DEFF Research Database (Denmark)

Dahl, Morten; Syberg, Susanne; Jørgensen, Niklas Rye

2013-01-01

Adipose derived mesenchymal stem cells (ADMSCs) may be osteogenic, may generate neoangiogenisis and may be progenitors for differentiated osteoblast mineralization. Titanium granules may be suitable as carriers for these cells. The aim was to demonstrate the osteogenic potential of ADMSCs...

Synaptic pathology in the cerebellar dentate nucleus in chronic multiple sclerosis.

Science.gov (United States)

Albert, Monika; Barrantes-Freer, Alonso; Lohrberg, Melanie; Antel, Jack P; Prineas, John W; Palkovits, Miklós; Wolff, Joachim R; Brück, Wolfgang; Stadelmann, Christine

2017-11-01

In multiple sclerosis, cerebellar symptoms are associated with clinical impairment and an increased likelihood of progressive course. Cortical atrophy and synaptic dysfunction play a prominent role in cerebellar pathology and although the dentate nucleus is a predilection site for lesion development, structural synaptic changes in this region remain largely unexplored. Moreover, the mechanisms leading to synaptic dysfunction have not yet been investigated at an ultrastructural level in multiple sclerosis. Here, we report on synaptic changes of dentate nuclei in post-mortem cerebella of 16 multiple sclerosis patients and eight controls at the histological level as well as an electron microscopy evaluation of afferent synapses of the cerebellar dentate and pontine nuclei of one multiple sclerosis patient and one control. We found a significant reduction of afferent dentate synapses in multiple sclerosis, irrespective of the presence of demyelination, and a close relationship between glial processes and dentate synapses. Ultrastructurally, we show autophagosomes containing degradation products of synaptic vesicles within dendrites, residual bodies within intact-appearing axons and free postsynaptic densities opposed to astrocytic appendages. Our study demonstrates loss of dentate afferent synapses and provides, for the first time, ultrastructural evidence pointing towards neuron-autonomous and neuroglia-mediated mechanisms of synaptic degradation in chronic multiple sclerosis. © 2016 International Society of Neuropathology.

Low-Dose Sevoflurane Promotes Hippocampal Neurogenesis and Facilitates the Development of Dentate Gyrus-Dependent Learning in Neonatal Rats

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Chong Chen

2015-04-01

Full Text Available Huge body of evidences demonstrated that volatile anesthetics affect the hippocampal neurogenesis and neurocognitive functions, and most of them showed impairment at anesthetic dose. Here, we investigated the effect of low dose (1.8% sevoflurane on hippocampal neurogenesis and dentate gyrus-dependent learning. Neonatal rats at postnatal day 4 to 6 (P4–6 were treated with 1.8% sevoflurane for 6 hours. Neurogenesis was quantified by bromodeoxyuridine labeling and electrophysiology recording. Four and seven weeks after treatment, the Morris water maze and contextual-fear discrimination learning tests were performed to determine the influence on spatial learning and pattern separation. A 6-hour treatment with 1.8% sevoflurane promoted hippocampal neurogenesis and increased the survival of newborn cells and the proportion of immature granular cells in the dentate gyrus of neonatal rats. Sevoflurane-treated rats performed better during the training days of the Morris water maze test and in contextual-fear discrimination learning test. These results suggest that a subanesthetic dose of sevoflurane promotes hippocampal neurogenesis in neonatal rats and facilitates their performance in dentate gyrus-dependent learning tasks.

Cell labelling. Granule and platelet kinetics. Recent concepts

International Nuclear Information System (INIS)

Najean, Y.; Dresch, C.; Dassin, E.

Some unsolved problems are reviewed concerning the lifetime of blood platelets, with special reference to excessive platelet consumption and its possible correction by anti-aggregation agents, in many vascular diseases. Regarding the production of platelets it is considered that the 75 Se-methionine labelling method alone offers a quantitative approach to the process and could be used for the physiological study of thrombopoietic factors. A short chapter is devoted to a survey of the points of agreement and disagreement regarding the lifetime of polynuclear cells and a tentative analysis of the reasons explaining the quite different results obtained with DFP and radiochromium labelling. Finally the methods used to study granule formation are criticized, though it is acknowledged that certain ideas useful in physiopathology have emerged from these different procedures [fr

Spontaneous perseverative turning in rats with radiation-induced hippocampal damage

International Nuclear Information System (INIS)

Mickley, G.A.; Ferguson, J.L.; Nemeth, T.J.; Mulvihill, M.A.; Alderks, C.E.

1989-01-01

This study found a new behavioral correlate of lesions specific to the dentate granule cell layer of the hippocampus: spontaneous perseverative turning. Irradiation of a portion of the neonatal rat cerebral hemispheres produced hypoplasia of the granule cell layer of the hippocampal dentate gyrus while sparing the rest of the brain. Radiation-induced damage to the hippocampal formation caused rats placed in bowls to spontaneously turn in long, slow bouts without reversals. Irradiated subjects also exhibited other behaviors characteristic of hippocampal damage (e.g., perseveration in spontaneous exploration of the arms of a T-maze, retarded acquisition of a passive avoidance task, and increased horizontal locomotion). These data extend previously reported behavioral correlates of fascia dentata lesions and suggest the usefulness of a bout analysis of spontaneous bowl turning as a measure of nondiscrete-trial spontaneous alternation and a sensitive additional indicator of radiation-induced hippocampal damage

Reward memory relieves anxiety-related behavior through synaptic strengthening and protein kinase C in dentate gyrus.

Science.gov (United States)

Lei, Zhuofan; Liu, Bei; Wang, Jin-Hui

2016-04-01

Anxiety disorders are presumably associated with negative memory. Psychological therapies are widely used to treat this mental deficit in human beings based on the view that positive memory competes with negative memory and relieves anxiety status. Cellular and molecular processes underlying psychological therapies remain elusive. Therefore, we have investigated its mechanisms based on a mouse model in which food reward at one open-arm of the elevated plus-maze was used for training mice to form reward memory and challenge the open arms. Mice with the reward training showed increased entries and stay time in reward open-arm versus neutral open-arm as well as in open-arms versus closed-arms. Accompanying with reward memory formation and anxiety relief, glutamatergic synaptic transmission in dentate gyrus in vivo and dendritic spines in granule cells became upregulated. This synaptic up-regulation was accompanied by the expression of more protein kinase C (PKC) in the dendritic spines. The inhibition of PKC by chelerythrine impaired the formation of reward memory, the relief of anxiety-related behavior and the up-regulation of glutamate synapses. Our results suggest that reward-induced positive memory relieves mouse anxiety-related behavior by strengthening synaptic efficacy and PKC in the hippocampus, which imply the underlying cellular and molecular processes involved in the beneficial effects of psychological therapies treating anxiety disorders. © 2015 Wiley Periodicals, Inc.

Iron and cell death in Parkinson's disease: a nuclear microscopic study into iron-rich granules in the parkinsonian substantia nigra of primate models

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Thong, P.S.P.; Watt, F. E-mail: phywattf@nus.edu.sg; Ponraj, D.; Leong, S.K.; He, Y.; Lee, T.K.Y

1999-09-02

Parkinson's disease is a degenerative brain disease characterised by a loss of cells in the substantia nigra (SN) region of the brain and accompanying biochemical changes such as inhibition of mitochondrial function, increased iron concentrations and decreased glutathione levels in the parkinsonian SN. Though the aetiology of the disease is still unknown, the observed biochemical changes point to the involvement of oxidative stress. In particular, iron is suspected to play a role by promoting free radical production, leading to oxidative stress and cell death. The increase in iron in the parkinsonian SN has been confirmed by several research groups, both in human post-mortem brains and in brain tissue from parkinsonian animal models. However, the question remains as to whether the observed increase in iron is a cause or a consequence of the SN cell death process. Our previous study using unilaterally 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)-lesioned monkeys in a time sequence experiment has shown that the increase in bulk iron concentrations follow rather than precede dopaminergic cell death. However, changes in the localised iron concentrations, which may play a more direct role in SN cell death, may not be reflected at the bulk level. Indeed, we have observed iron-rich granules in parkinsonian SNs. From this time sequence study into the iron content of iron-rich granules in the SNs of an untreated control and unilaterally MPTP-lesioned parkinsonian models, we present the following observations: (1) Iron-rich granules are found in both control and parkinsonian SNs and are variable in size and iron content in any one model. (2) These iron-rich granules may be associated with neuromelanin granules found in the SN and are known to accumulate transition metal ions such as iron. (3) The early onset of bulk SN cell loss (35%) was accompanied by a significant elevation of iron in granules found in the MPTP-injected SN compared to the contra-lateral SN

Accumulation of PHA granules in Cupriavidus necator as seen by confocal fluorescence microscopy.

Science.gov (United States)

Mravec, Filip; Obruca, Stanislav; Krzyzanek, Vladislav; Sedlacek, Petr; Hrubanova, Kamila; Samek, Ota; Kucera, Dan; Benesova, Pavla; Nebesarova, Jana

2016-05-01

Many bacteria are capable of accumulating intracellular granules of polyhydroxyalkanoates (PHA). In this work, we developed confocal microscopy analysis of bacterial cells to study changes in the diameters of cells as well as PHA granules during growth and PHA accumulation in the bacterium Cupriavidus necator H16 (formerly Ralstonia eutropha). The cell envelope was stained by DiD(®) fluorescent probe and PHA granules by Nile Red. Signals from both probes were separated based on their spectral and fluorescence life-time properties. During growth and PHA accumulation, bacterial cells increased their length but the width of the cells remained constant. The volume fraction of PHA granules in cells increased during PHA accumulation, nevertheless, its value did not exceed 40 vol. % regardless of the PHA weight content. It seems that bacterial cultures lengthen the cells in order to control the PHA volume portion. However, since similar changes in cell length were also observed in a PHA non-accumulating mutant, it seems that there is no direct control mechanism, which regulates the prolongation of the cells with respect to PHA granules volume. It is more likely that PHA biosynthesis and the length of cells are influenced by the same external stimuli such as nutrient limitation. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Interaction between granulation and small-scale magnetic flux observed by Hinode

International Nuclear Information System (INIS)

Zhang Jun; Yang Shuhong; Jin Chunlan

2009-01-01

With the polarimetric observations obtained by the Spectro-Polarimeter on board Hinode, we study the relationship between granular development and magnetic field evolution in the quiet Sun. Six typical cases are displayed to exhibit interaction between granules and magnetic elements, and we have obtained the following results. (1) A granule develops centrosymmetrically when no magnetic flux emerges within the granular cell. (2) A granule develops and splits noncentrosymmetrically while flux emerges at an outer part of the granular cell. (3) Magnetic flux emergence in a cluster of mixed polarities is detected at the position of a granule as soon as the granule breaks up. (4) A dipole emerges accompanied by the development of a granule, and the two elements of the dipole are rooted in the adjacent intergranular lanes and face each other across the granule. Advected by the horizontal granular motion, the positive element of the dipole then cancels with the pre-existing negative flux. (5) Flux cancellation also takes place between a positive element, which is advected by granular flow, and its surrounding negative flux. (6) While magnetic flux cancellation takes place in a granular cell, the granule shrinks and then disappears. (7) Horizontal magnetic fields are enhanced at the places where dipoles emerge and where opposite polarities cancel each other, but only the horizontal fields between the dipolar elements point in an orderly way from the positive elements to the negative ones. Our results reveal that granules and small-scale magnetic fluxes influence each other. Granular flow advects magnetic flux, and magnetic flux evolution suppresses granular development. There exist extremely large Doppler blue-shifts at the site of one canceling magnetic element. This phenomenon may be caused by the upward flow produced by magnetic reconnection below the photosphere. (research papers)

Mechanism of the formation of hollow spherical granules using a high shear granulator.

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Asada, Takumi; Nishikawa, Mitsunori; Ochiai, Yasushi; Noguchi, Shuji; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

2018-05-30

Recently, we have developed a novel granulation technology to manufacture hollow spherical granules (HSGs) for controlled-release formulations; however, the mechanism of the granulation is still unclear. The aim of this study is to determine the mechanism of the formation of the HSGs using a high shear granulator. Samples of granulated material were collected at various times during granulation and were investigated using scanning electron microscope and X-ray computed tomography. It was observed that the granulation proceeded by drug layering to the polymer, followed by formation of a hollow in the granule. In addition, it was also found that generation of a crack in the adhered drug layer and air flow into the granules might be involved in forming the hollow in the structure. Observation of the granulation of formulations with different types of drugs and polymers indicated that negative pressure in the granules occurred and the granules caved in when the hollow was formed. The hollow-forming speed and the shell density of the hollow granules depended on the particular drug and polymer. Taken together, the granulation mechanism of HSGs was determined and this information will be valuable for HSGs technology development. Copyright © 2018 Elsevier B.V. All rights reserved.

Statistical properties of solar granulation from the SOUP instrument on Spacelab 2

International Nuclear Information System (INIS)

Topka, K.; Title, A.; Tarbell, T.; Ferguson, S.; Shine, R.

1988-01-01

The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected movies of solar granulation completely free from atmospheric blurring, and are not degraded by pointint jitter (the pointing stability was 0.003 sec root mean square). The movies illustrate that the solar five minute oscillation has a major role in the appearance of solar granulation and that exploding granules are a common feature of the granule evolution. Using 3-D Fourier filtering techniques the oscillations were removed and it was demonstrated that the autocorrelation lifetime of granulation is a factor of two greater in magnetic field regions than in field-free quiet sun. Horizontal velocities were measured and flow patterns were observed on the scale of meso- and super granulation. In quiet regions the mean flow velocity is 370 m/s while in the magnetic regions it is about 125 m/s. It was also found that the root mean square (RMS) fluctuating horizonal velocity field is substantially greater in quiet sun than in strong magnetic field regions. By superimposing the location of exploding granules on the average flow maps it was found that they appear almost exclusively in the center of mesogranulation size flow cells. Because of the nonuniformity of the distribution of exploding granules, the evolution of the granulation pattern in mesogranule cell centers and boundaries differs fundamentally. It is clear from this study there is neither a typical granule nor a typical granule evolution

Statistical properties of solar granulation from the SOUP instrument on Spacelab 2

Science.gov (United States)

Topka, K.; Title, A.; Tarbell, T.; Ferguson, S.; Shine, R.

1988-11-01

The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected movies of solar granulation completely free from atmospheric blurring, and are not degraded by pointint jitter (the pointing stability was 0.003 sec root mean square). The movies illustrate that the solar five minute oscillation has a major role in the appearance of solar granulation and that exploding granules are a common feature of the granule evolution. Using 3-D Fourier filtering techniques the oscillations were removed and it was demonstrated that the autocorrelation lifetime of granulation is a factor of two greater in magnetic field regions than in field-free quiet sun. Horizontal velocities were measured and flow patterns were observed on the scale of meso- and super granulation. In quiet regions the mean flow velocity is 370 m/s while in the magnetic regions it is about 125 m/s. It was also found that the root mean square (RMS) fluctuating horizonal velocity field is substantially greater in quiet sun than in strong magnetic field regions. By superimposing the location of exploding granules on the average flow maps it was found that they appear almost exclusively in the center of mesogranulation size flow cells. Because of the nonuniformity of the distribution of exploding granules, the evolution of the granulation pattern in mesogranule cell centers and boundaries differs fundamentally. It is clear from this study there is neither a typical granule nor a typical granule evolution.

Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation

DEFF Research Database (Denmark)

Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie

2016-01-01

Twin-screw granulation is a promising wet granulation technique for the continuous manufacturing of pharmaceutical solid dosage forms. A twin screw granulator displays a short residence time. Thus, the solid-liquid mixing must be achieved quickly by appropriate arrangement of transport and kneading...

The biology and dynamics of mammalian cortical granules

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Liu Min

2011-11-01

Full Text Available Abstract Cortical granules are membrane bound organelles located in the cortex of unfertilized oocytes. Following fertilization, cortical granules undergo exocytosis to release their contents into the perivitelline space. This secretory process, which is calcium dependent and SNARE protein-mediated pathway, is known as the cortical reaction. After exocytosis, the released cortical granule proteins are responsible for blocking polyspermy by modifying the oocytes' extracellular matrices, such as the zona pellucida in mammals. Mammalian cortical granules range in size from 0.2 um to 0.6 um in diameter and different from most other regulatory secretory organelles in that they are not renewed once released. These granules are only synthesized in female germ cells and transform an egg upon sperm entry; therefore, this unique cellular structure has inherent interest for our understanding of the biology of fertilization. Cortical granules are long thought to be static and awaiting in the cortex of unfertilized oocytes to be stimulated undergoing exocytosis upon gamete fusion. Not till recently, the dynamic nature of cortical granules is appreciated and understood. The latest studies of mammalian cortical granules document that this organelle is not only biochemically heterogeneous, but also displays complex distribution during oocyte development. Interestingly, some cortical granules undergo exocytosis prior to fertilization; and a number of granule components function beyond the time of fertilization in regulating embryonic cleavage and preimplantation development, demonstrating their functional significance in fertilization as well as early embryonic development. The following review will present studies that investigate the biology of cortical granules and will also discuss new findings that uncover the dynamic aspect of this organelle in mammals.

GABAA Receptor-Mediated Activity in a Model of Cortical Dysplasia

Science.gov (United States)

2012-06-29

LiCl/pilocarpine- induced status epilepticus on brain mu and benzodiazepine receptor binding: regional and ontogenetic studies. Brain Res 1181:104-17...Z, Nadler V (2009) Enhanced tonic GABA current in normotopic and hilar ctopic dentate granule cells after pilocarpine-induced status epilepticus . J

Overlapping but distinct TDP-43 and tau pathologic patterns in aged hippocampi.

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Smith, Vanessa D; Bachstetter, Adam D; Ighodaro, Eseosa; Roberts, Kelly; Abner, Erin L; Fardo, David W; Nelson, Peter T

2018-03-01

Intracellular proteinaceous aggregates (inclusion bodies) are almost always detectable at autopsy in brains of elderly individuals. Inclusion bodies composed of TDP-43 and tau proteins often coexist in the same brain, and each of these pathologic biomarkers is associated independently with cognitive impairment. However, uncertainties remain about how the presence and neuroanatomical distribution of inclusion bodies correlate with underlying diseases including Alzheimer's disease (AD). To address this knowledge gap, we analyzed data from the University of Kentucky AD Center autopsy series (n = 247); none of the brains had frontotemporal lobar degeneration. A specific question for this study was whether neurofibrillary tangle (NFT) pathology outside of the Braak NFT staging scheme is characteristic of brains with TDP-43 pathology but lacking AD, that is those with cerebral age-related TDP-43 with sclerosis (CARTS). We also tested whether TDP-43 pathology is associated with comorbid AD pathology, and whether argyrophilic grains are relatively likely to be present in cases with, vs. without, TDP-43 pathology. Consistent with prior studies, hippocampal TDP-43 pathology was associated with advanced AD - Braak NFT stages V/VI. However, argyrophilic grain pathology was not more common in cases with TDP-43 pathology in this data set. In brains with CARTS (TDP-43[+]/AD[-] cases), there were more NFTs in dentate granule neurons than were seen in TDP-43[-]/AD[-] cases. These dentate granule cell NFTs could provide a proxy indicator of CARTS pathology in cases lacking substantial AD pathology. Immunofluorescent experiments in a subsample of cases found that, in both advanced AD and CARTS, approximately 1% of dentate granule neurons were PHF-1 immunopositive, whereas ∼25% of TDP-43 positive cells showed colocalized PHF-1 immunoreactivity. We conclude that NFTs in hippocampal dentate granule neurons are often present in CARTS, and TDP-43 pathology may be secondary to or

Analysis of carbohydrate storage granules in the diazotrophic cyanobacterium Cyanothece sp. PCC 7822

Energy Technology Data Exchange (ETDEWEB)

Welkie, David G. [Purdue Univ., West Lafayette, IN (United States); Sherman, Debra M. [Purdue Univ., West Lafayette, IN (United States); Chrisler, William B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Orr, Galya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sherman, Louis A. [Purdue Univ., West Lafayette, IN (United States)

2013-10-19

The unicellular diazotrophic cyanobacteria of the genus Cyanothece demonstrate oscillations in nitrogenase activity and H₂ production when grown under 12h light-12h dark cycles. We established that Cyanothece sp. PCC 7822 allows for the construction of knock-out mutants and our objective was to improve the growth characteristics of this strain and to identify the nature of the intracellular storage granules. We report the physiological and morphological effects of reduction in nitrate and phosphate concentrations in BG-11 media on this strain. We developed a series of BG-11-derived growth media and monitored batch culture growth, nitrogenase activity and nitrogenase-mediated hydrogen production, culture synchronicity, and intracellular storage content. Reduction in NaNO3 and K₂HPO₄ concentrations from 17.6 and 0.23 mM to 4.41 and 0.06 mM, respectively, improved growth characteristics such as cell size and uniformity, and enhanced the rate of cell division. Cells grown in this low NP BG-11 were less complex, a parameter that related to the composition of the intracellular storage granules. Cells grown in low NP BG-11 had less polyphosphate, fewer polyhydroxybutyrate granules and many smaller granules became evident. Biochemical analysis and transmission electron microscopy using the histocytochemical PATO technique demonstrated that these small granules contained glycogen. The glycogen levels and the number of granules per cell correlated nicely with a 2.3 to 3.3-fold change from the minimum at L0 to the maximum at D0. The differences in granule morphology and enzymes between Cyanothece ATCC 51142 and Cyanothece PCC 7822 provide insights into the formation of large starch-like granules in some cyanobacteria.

Naringenin ameliorates kainic acid-induced morphological alterations in the dentate gyrus in a mouse model of temporal lobe epilepsy.

Science.gov (United States)

Park, Jungha; Jeong, Kyoung Hoon; Shin, Won-Ho; Bae, Young-Seuk; Jung, Un Ju; Kim, Sang Ryong

2016-10-19

Granule cell dispersion (GCD) in the dentate gyrus (DG) of the hippocampus is a morphological alteration characteristic of temporal lobe epilepsy. Recently, we reported that treatment with naringin, a flavonoid found in grapefruit and citrus fruits, reduced spontaneous recurrent seizures by inhibiting kainic acid (KA)-induced GCD and neuronal cell death in mouse hippocampus, suggesting that naringin might have beneficial effects for preventing epileptic events in the adult brain. However, it is still unclear whether the beneficial effects of naringin treatment are mediated by the metabolism of naringin into naringenin in the KA-treated hippocampus. To investigate this possibility, we evaluated whether intraperitoneal injections of naringenin could mimic naringin-induced effects against GCD caused by intrahippocampal KA injections in mice. Our results showed that treatment with naringenin delayed the onset of KA-induced seizures and attenuated KA-induced GCD by inhibiting activation of the mammalian target of rapamycin complex 1 in both neurons and reactive astrocytes in the DG. In addition, its administration attenuated the production of proinflammatory cytokines such as tumor necrosis tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β) from microglial activation in the DG following KA treatment. These results suggest that naringenin may be an active metabolite of naringin and help prevent the progression of epileptic insults in the hippocampus in vivo; therefore, naringenin may be a beneficial metabolite of naringin for the treatment of epilepsy.

Low-dose sevoflurane promotes hippocampal neurogenesis and facilitates the development of dentate gyrus-dependent learning in neonatal rats.

Science.gov (United States)

Chen, Chong; Shen, Feng-Yan; Zhao, Xuan; Zhou, Tao; Xu, Dao-Jie; Wang, Zhi-Ru; Wang, Ying-Wei

2015-01-01

Huge body of evidences demonstrated that volatile anesthetics affect the hippocampal neurogenesis and neurocognitive functions, and most of them showed impairment at anesthetic dose. Here, we investigated the effect of low dose (1.8%) sevoflurane on hippocampal neurogenesis and dentate gyrus-dependent learning. Neonatal rats at postnatal day 4 to 6 (P4-6) were treated with 1.8% sevoflurane for 6 hours. Neurogenesis was quantified by bromodeoxyuridine labeling and electrophysiology recording. Four and seven weeks after treatment, the Morris water maze and contextual-fear discrimination learning tests were performed to determine the influence on spatial learning and pattern separation. A 6-hour treatment with 1.8% sevoflurane promoted hippocampal neurogenesis and increased the survival of newborn cells and the proportion of immature granular cells in the dentate gyrus of neonatal rats. Sevoflurane-treated rats performed better during the training days of the Morris water maze test and in contextual-fear discrimination learning test. These results suggest that a subanesthetic dose of sevoflurane promotes hippocampal neurogenesis in neonatal rats and facilitates their performance in dentate gyrus-dependent learning tasks. © The Author(s) 2015.

The life cycle of platelet granules [version 1; referees: 2 approved

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Anish Sharda

2018-02-01

Full Text Available Platelet granules are unique among secretory vesicles in both their content and their life cycle. Platelets contain three major granule types—dense granules, α-granules, and lysosomes—although other granule types have been reported. Dense granules and α-granules are the most well-studied and the most physiologically important. Platelet granules are formed in large, multilobulated cells, termed megakaryocytes, prior to transport into platelets. The biogenesis of dense granules and α-granules involves common but also distinct pathways. Both are formed from the trans-Golgi network and early endosomes and mature in multivesicular bodies, but the formation of dense granules requires trafficking machinery different from that of α-granules. Following formation in the megakaryocyte body, both granule types are transported through and mature in long proplatelet extensions prior to the release of nascent platelets into the bloodstream. Granules remain stored in circulating platelets until platelet activation triggers the exocytosis of their contents. Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE proteins, located on both the granules and target membranes, provide the mechanical energy that enables membrane fusion during both granulogenesis and exocytosis. The function of these core fusion engines is controlled by SNARE regulators, which direct the site, timing, and extent to which these SNAREs interact and consequently the resulting membrane fusion. In this review, we assess new developments in the study of platelet granules, from their generation to their exocytosis.

MDMA Increases Excitability in the Dentate Gyrus: Role of 5HT2A Receptor Induced PGE2 Signaling

Science.gov (United States)

Collins, Stuart A.; Huff, Courtney; Chiaia, Nicolas; Gudelsky, Gary A.; Yamamoto, Bryan K.

2015-01-01

MDMA is a widely abused psychostimulant which causes release of serotonin in various forebrain regions. Recently, we reported that MDMA increases extracellular glutamate concentrations in the dentate gyrus, via activation of 5HT2A receptors. We examined the role of prostaglandin signaling in mediating the effects of 5HT2A receptor activation on the increases in extracellular glutamate and the subsequent long-term loss of parvalbumin interneurons in the dentate gyrus caused by MDMA. Administration of MDMA into the dentate gyrus of rats increased PGE2 concentrations which was prevented by coadministration of MDL100907, a 5HT2A receptor antagonist. MDMA-induced increases in extracellular glutamate were inhibited by local administration of SC-51089, an inhibitor of the EP1 prostaglandin receptor. Systemic administration of SC-51089 during injections of MDMA prevented the decreases in parvalbumin interneurons observed 10 days later. The loss of parvalbumin immunoreactivity after MDMA exposure coincided with a decrease in paired-pulse inhibition and afterdischarge threshold in the dentate gyrus. These changes were prevented by inhibition of EP1 and 5HT2A receptors during MDMA. Additional experiments revealed an increased susceptibility to kainic acid-induced seizures in MDMA treated rats which could be prevented with SC51089 treatments during MDMA exposure. Overall, these findings suggest that 5HT2A receptors mediate MDMA-induced PGE2 signaling and subsequent increases in glutamate. This signaling mediates parvalbumin cell losses as well as physiologic changes in the dentate gyrus, suggesting that the lack of the inhibition provided by these neurons increases the excitability within the dentate gyrus of MDMA treated rats. PMID:26670377

Colchicine induces apoptosis in organotypic hippocampal slice cultures

DEFF Research Database (Denmark)

Kristensen, Bjarne W; Noer, Helle; Gramsbergen, Jan Bert

2003-01-01

The microtubule-disrupting agent colchicine is known to be particular toxic for certain types of neurons, including the granule cells of the dentate gyrus. In this study we investigated whether colchicine could induce such neuron-specific degeneration in developing (1 week in vitro) and mature (3...

Proteome profiling of human neutrophil granule subsets, secretory vesicles, and cell membrane

DEFF Research Database (Denmark)

Rørvig, Sara; Østergaard, Ole; Heegaard, Niels Henrik Helweg

2013-01-01

granules, SVs, and plasma membrane has been performed before. Here, we performed subcellular fractionation on freshly isolated human neutrophils by nitrogen cavitation and density centrifugation on a four-layer Percoll gradient. Granule subsets were pooled and subjected to SDS-PAGE, and gel pieces were in...... subcellular proteome profiles presented here may be used as a database in combination with the mRNA array database to predict and test the presence and localization of proteins in neutrophil granules and membranes....

Serglycin proteoglycan is not implicated in localizing exocrine pancreas enzymes to zymogen granules

DEFF Research Database (Denmark)

Niemann, Carsten U; Cowland, Jack B; Ralfkiaer, Elisabeth

2009-01-01

Storage and release of proteins from granules forms the basis of cellular functions as diverse as cell mediated cytotoxicity, neuronal communication, activation of muscle fibres, and release of hormones or digestive enzymes from endocrine and exocrine glands, such as the pancreas. Serglycin...... is the major intracellular proteoglycan of haematopoietic cells. Serglycin is important for localization of proteins in granules of different haematopoietic cell types. Previous reports have indicated a role for serglycin in granule formation and localization of zymogens in granules of the exocrine pancreas...... in rat. We here present data showing that serglycin is not present at the protein level in human or murine pancreas. Furthermore, the amount and localization of three exocrine pancreas zymogens (amylase, trypsinogen, and carboxypeptidase A) is not affected by the absence of serglycin in a serglycin knock...

Granule size control and targeting in pulsed spray fluid bed granulation.

Science.gov (United States)

Ehlers, Henrik; Liu, Anchang; Räikkönen, Heikki; Hatara, Juha; Antikainen, Osmo; Airaksinen, Sari; Heinämäki, Jyrki; Lou, Honxiang; Yliruusi, Jouko

2009-07-30

The primary aim of the study was to investigate the effects of pulsed liquid feed on granule size. The secondary aim was to increase knowledge of this technique in granule size targeting. Pulsed liquid feed refers to the pump changing between on- and off-positions in sequences, called duty cycles. One duty cycle consists of one on- and off-period. The study was performed with a laboratory-scale top-spray fluid bed granulator with duty cycle length and atomization pressure as studied variables. The liquid feed rate, amount and inlet air temperature were constant. The granules were small, indicating that the powder has only undergone ordered mixing, nucleation and early growth. The effect of atomizing pressure on granule size depends on inlet air relative humidity, with premature binder evaporation as a reason. The duty cycle length was of critical importance to the end product attributes, by defining the extent of intermittent drying and rewetting. By varying only the duty cycle length, it was possible to control granule nucleation and growth, with a wider granule size target range in increased relative humidity. The present study confirms that pulsed liquid feed in fluid bed granulation is a useful tool in end product particle size targeting.

Hippocampal dentation: Structural variation and its association with episodic memory in healthy adults.

Science.gov (United States)

Fleming Beattie, Julia; Martin, Roy C; Kana, Rajesh K; Deshpande, Hrishikesh; Lee, Seongtaek; Curé, Joel; Ver Hoef, Lawrence

2017-07-01

While the hippocampus has long been identified as a structure integral to memory, the relationship between morphology and function has yet to be fully explained. We present an analysis of hippocampal dentation, a morphological feature previously unexplored in regard to its relationship with episodic memory. "Hippocampal dentation" in this case refers to surface convolutions, primarily present in the CA1/subiculum on the inferior aspect of the hippocampus. Hippocampal dentation was visualized using ultra-high resolution structural MRI and evaluated using a novel visual rating scale. The degree of hippocampal dentation was found to vary considerably across individuals, and was positively associated with verbal memory recall and visual memory recognition in a sample of 22 healthy adults. This study is the first to characterize the variation in hippocampal dentation in a healthy cohort and to demonstrate its association with aspects of episodic memory. Copyright © 2017 Elsevier Ltd. All rights reserved.

Doublecortin (DCX is not essential for survival and differentiation of newborn neurons in the adult mouse dentate gyrus

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Jagroop eDhaliwal

2016-01-01

Full Text Available In the adult brain, expression of the microtubule-associated protein Doublecortin (DCX is associated with neural progenitor cells (NPCs that give rise to new neurons in the dentate gyrus. Many studies quantify the number of DCX-expressing cells as a proxy for the level of adult neurogenesis, yet no study has determined the effect of removing DCX from adult hippocampal NPCs. Here, we use a retroviral and inducible mouse transgenic approach to either knockdown or knockout DCX from adult NPCs in the dentate gyrus and examine how this affects cell survival and neuronal maturation. Our results demonstrate that shRNA-mediated knockdown of DCX or Cre-mediated recombination in floxed DCX mice does not alter hippocampal neurogenesis and does not change the neuronal fate of the NPCs. Together these findings show that the survival and maturation of adult-generated hippocampal neurons does not require DCX.

Incorporation of a circulating protein into megakaryocyte and platelet granules

Science.gov (United States)

Handagama, P. J.; George, J. N.; Shuman, M. A.; McEver, R. P.; Bainton, D. F.

1987-01-01

To determine whether or not proteins circulating in plasma can be incorporated into megakaryocytes and platelets, horseradish peroxidase (HRP) was injected intravenously into guinea pigs and these cells were examined for its uptake by electron microscopy and cytochemistry. Enriched samples of megakaryocytes enabled ultrastructural analysis of large numbers of these rare cells. In megakaryocytes, 50% of alpha granules contained HRP between 75 min and 7 hr after injection. At 24 hr, 25% of the megakaryocyte granules were peroxidase-positive, less were positive by 48 hr, and there were none at 4 days. Thus, the findings demonstrate that a circulating protein can be endocytosed by megakaryocytes and rapidly packaged into alpha granules. Platelet granules also contain HRP by 7 hr after injection, and they can secrete it in response to thrombin. Unfortunately, our present studies do not allow us to distinguish between direct endocytosis by the platelet and/or shedding of new platelets from recently labeled megakaryocytes. It is concluded that while some alpha granule proteins are synthesized by megakaryocytes, others may be acquired from plasma by endocytosis. In addition to providing evidence that some of the proteins of alpha granules may be of exogenous origin, this study has allowed the definition of a pathway whereby plasma proteins may be temporarily sequestered in megakaryocytes before reentering the circulation in platelets.

Granules Harboring Translationally Active mRNAs Provide a Platform for P-Body Formation following Stress

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Jennifer Lui

2014-11-01

Full Text Available The localization of mRNA to defined cytoplasmic sites in eukaryotic cells not only allows localized protein production but also determines the fate of mRNAs. For instance, translationally repressed mRNAs localize to P-bodies and stress granules where their decay and storage, respectively, are directed. Here, we find that several mRNAs are localized to granules in unstressed, actively growing cells. These granules play a key role in the stress-dependent formation of P-bodies. Specific glycolytic mRNAs are colocalized in multiple granules per cell, which aggregate during P-body formation. Such aggregation is still observed under conditions or in mutants where P-bodies do not form. In unstressed cells, the mRNA granules appear associated with active translation; this might enable a coregulation of protein expression from the same pathways or complexes. Parallels can be drawn between this coregulation and the advantage of operons in prokaryotic systems.

Phleum pratense pollen starch granules induce humoral and cell-mediated immune responses in a rat model of allergy.

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Motta, A; Peltre, G; Dormans, J A M A; Withagen, C E T; Lacroix, G; Bois, F; Steerenberg, P A

2004-02-01

Timothy grass (Phleum pratense) pollen allergens are an important cause of allergic symptoms. However, pollen grains are too large to penetrate the deeper airways. Grass pollen is known to release allergen-bearing starch granules (SG) upon contact with water. These granules can create an inhalable allergenic aerosol capable of triggering an early asthmatic response and are implicated in thunderstorm-associated asthma. We studied the humoral (IgE) and bronchial lymph node cells reactivities to SG from timothy grass pollen in pollen-sensitized rats. Brown-Norway rats were sensitized (day 0) and challenged (day 21) intratracheally with intact pollen and kept immunized by pollen intranasal instillation by 4 weeks intervals during 3 months. Blood and bronchial lymph nodes were collected 7 days after the last intranasal challenge. SG were purified from fresh timothy grass pollen using 5 microm mesh filters. To determine the humoral response (IgE) to SG, we developed an original ELISA inhibition test, based on competition between pollen allergens and purified SG. The cell-mediated response to SG in the bronchial lymph node cells was determined by measuring the uptake of [3H]thymidine in a proliferation assay. An antibody response to SG was induced, and purified SG were able to inhibit the IgE ELISA absorbance by 45%. Pollen extract and intact pollen gave inhibitions of 55% and 52%, respectively. A cell-mediated response was also found, as pollen extract, intact pollen and SG triggered proliferation of bronchial lymph node cells. It was confirmed that timothy grass pollen contains allergen-loaded SG, which are released upon contact with water. These granules were shown to be recognized by pollen-sensitized rats sera and to trigger lymph node cell proliferation in these rats. These data provide new arguments supporting the implication of grass pollen SG in allergic asthma.

Synthetic mast-cell granules as adjuvants to promote and polarize immunity in lymph nodes

Science.gov (United States)

St. John, Ashley L.; Chan, Cheryl Y.; Staats, Herman F.; Leong, Kam W.; Abraham, Soman N.

2012-03-01

Granules of mast cells (MCs) enhance adaptive immunity when, on activation, they are released as stable particles. Here we show that submicrometre particles modelled after MC granules augment immunity when used as adjuvants in vaccines. The synthetic particles, which consist of a carbohydrate backbone with encapsulated inflammatory mediators such as tumour necrosis factor, replicate attributes of MCs in vivo including the targeting of draining lymph nodes and the timed release of the encapsulated mediators. When used as an adjuvant during vaccination of mice with haemagglutinin from the influenza virus, the particles enhanced adaptive immune responses and increased survival of mice on lethal challenge. Furthermore, differential loading of the particles with the cytokine IL-12 directed the character of the response towards Th1 lymphocytes. The synthetic MC adjuvants replicate and enhance the functions of MCs during vaccination, and can be extended to polarize the resulting immunity.

Fluoxetine induces input-specific hippocampal dendritic spine remodeling along the septo-temporal axis in adulthood and middle age

Science.gov (United States)

McAvoy, Kathleen; Russo, Craig; Kim, Shannen; Rankin, Genelle; Sahay, Amar

2015-01-01

Fluoxetine, a selective serotonin-reuptake inhibitor (SSRI), is known to induce structural rearrangements and changes in synaptic transmission in hippocampal circuitry. In the adult hippocampus, structural changes include neurogenesis, dendritic and axonal plasticity of pyramidal and dentate granule neurons, and dedifferentiation of dentate granule neurons. However, much less is known about how chronic fluoxetine affects these processes along the septo-temporal axis and during the aging process. Importantly, studies documenting the effects of fluoxetine on density and distribution of spines along different dendritic segments of dentate granule neurons and CA1 pyramidal neurons along the septo-temporal axis of hippocampus in adulthood and during aging are conspicuously absent. Here, we use a transgenic mouse line in which mature dentate granule neurons and CA1 pyramidal neurons are genetically labeled with green fluorescent protein (GFP) to investigate the effects of chronic fluoxetine treatment (18mg/kg/day) on input-specific spine remodeling and mossy fiber structural plasticity in the dorsal and ventral hippocampus in adulthood and middle age. In addition, we examine levels of adult hippocampal neurogenesis, maturation state of dentate granule neurons, neuronal activity and glutamic acid decarboxylase-67 expression in response to chronic fluoxetine in adulthood and middle age. Our studies reveal that while chronic fluoxetine fails to augment adult hippocampal neurogenesis in middle age, the middle-aged hippocampus retains high sensitivity to changes in the dentate gyrus (DG) such as dematuration, hypoactivation, and increased glutamic acid decarboxylase 67 (GAD67) expression. Interestingly, the middle-aged hippocampus shows greater sensitivity to fluoxetine-induced input-specific synaptic remodeling than the hippocampus in adulthood with the stratum-oriens of CA1 exhibiting heightened structural plasticity. The input-specific changes and circuit

Fluoxetine induces input-specific hippocampal dendritic spine remodeling along the septotemporal axis in adulthood and middle age.

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McAvoy, Kathleen; Russo, Craig; Kim, Shannen; Rankin, Genelle; Sahay, Amar

2015-11-01

Fluoxetine, a selective serotonin-reuptake inhibitor (SSRI), is known to induce structural rearrangements and changes in synaptic transmission in hippocampal circuitry. In the adult hippocampus, structural changes include neurogenesis, dendritic, and axonal plasticity of pyramidal and dentate granule neurons, and dedifferentiation of dentate granule neurons. However, much less is known about how chronic fluoxetine affects these processes along the septotemporal axis and during the aging process. Importantly, studies documenting the effects of fluoxetine on density and distribution of spines along different dendritic segments of dentate granule neurons and CA1 pyramidal neurons along the septotemporal axis of hippocampus in adulthood and during aging are conspicuously absent. Here, we use a transgenic mouse line in which mature dentate granule neurons and CA1 pyramidal neurons are genetically labeled with green fluorescent protein (GFP) to investigate the effects of chronic fluoxetine treatment (18 mg/kg/day) on input-specific spine remodeling and mossy fiber structural plasticity in the dorsal and ventral hippocampus in adulthood and middle age. In addition, we examine levels of adult hippocampal neurogenesis, maturation state of dentate granule neurons, neuronal activity, and glutamic acid decarboxylase-67 expression in response to chronic fluoxetine in adulthood and middle age. Our studies reveal that while chronic fluoxetine fails to augment adult hippocampal neurogenesis in middle age, the middle-aged hippocampus retains high sensitivity to changes in the dentate gyrus (DG) such as dematuration, hypoactivation, and increased glutamic acid decarboxylase 67 (GAD67) expression. Interestingly, the middle-aged hippocampus shows greater sensitivity to fluoxetine-induced input-specific synaptic remodeling than the hippocampus in adulthood with the stratum-oriens of CA1 exhibiting heightened structural plasticity. The input-specific changes and circuit

Soft x-ray imaging of intracellular granules of filamentous cyanobacterium generating musty smell in Lake Biwa

International Nuclear Information System (INIS)

Takemoto, K; Mizuta, G; Namba, H; Yamamoto, A; Kihara, H; Yoshimura, M; Ichise, S

2013-01-01

A planktonic blue-green algae, which are currently identified as Phormidium tenue, was observed by a soft x-ray microscopy (XM) for comparing a musty smell generating green strain (PTG) and a non-smell brown strain (PTB). By XM, cells were clearly imaged, and several intracellular granules which could not be observed under a light microscope were visualized. The diameter of granules was about 0.5–1 μm, and one or a few granules were seen in a cell. XM analyses showed that width of cells and sizes of intracellular granules were quite different between PTG and PTB strains. To study the granules observed by XM, transmission in more detail, transmission electron microscopy (TEM) and indirect fluorescent-antibody technique (IFA) were applied. By TEM, carboxysomes, thylakoids and polyphosphate granules were observed. IFA showed the presence of carboxysomes. Results lead to the conclusion that intracellular granules observed under XM are carboxysomes or polyphosphate granules. These results demonstrate that soft XM is effective for analyzing fine structures of small organisms such as cyanobacterium, and for discriminating the strains which generates musty smells from others

Regularities of formation of granules at granulation of powdered materials in drum devices

International Nuclear Information System (INIS)

Kelbaliyev, G.I; Samedli, V.M.

2008-01-01

Full text:Granulation of powdered materials in the presence of binding agent is widely used in the most multi-tankage productions of chemical, food, pharmaceutical, metallurgical and agrarian technology. Granulation of powdered materials with participation of liquid phase is carried out in screw, disk, plase-shaped and drum devices and also in devices with mixers. In all cases a formation and growth of granules takes place owing to wetting of separate particles of powder leading to agglomeration and coagulation of particles in their contact with each other. It is apparent that in early stage of granule formation a growth and formation of granules takes place owing to adherence of small particles and agglomerates to larger granules. The content of liquid phase owing to which are appeared adhesive, capillary and surface forces, keeping particles on surface of granule exerts an essential influence on process of granule formation. Besides composition of mixture, its moisture and physical-chemical properties of initial components a mixing frequency degree of filling and angle of inclination of the device, ratio of liquid and hard phases which defines finally qualitative characteristics of the process exert an essential influence on formation of granules as a result of agglomeration of particles of powder. Powder lamination on granule surface is as consequence of its consolidation whereas as a result of consolidation and compression, a binding agent containing in pores squeezed out to a surface, which increases a possibility and probability of further sticking of dry particles of powder. In all cases the further growth and completeness of form of granule is determined by distribution of concentration of binding agent in volume of granule, i.e. moisture content or moisture of granule surface

Amylolytic hydrolysis of native starch granules affected by granule surface area.

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Kim, J C; Kong, B W; Kim, M J; Lee, S H

2008-11-01

Initial stage of hydrolysis of native starch granules with various amylolytic enzymes, alpha-amylase from Bacillus subtilis, glucoamylase I (GA-I) and II (GA-II) from Aspergillus niger, and beta-amylase from sweet potato showed that the reaction was apparently affected by a specific surface area of the starch granules. The ratios of the reciprocal of initial velocity of each amylolytic hydrolysis for native potato and maize starch to that for rice with the amylolytic enzymes were nearly equivalent to the ratio of surface area per mass of the 2 starch granules to that of rice, that is, 6.94 and 2.25, respectively. Thus, the reciprocal of initial velocity of each enzymatic hydrolysis as expressed in a Lineweaver-Burk plot was a linear function of the reciprocal of surface area for each starch granule. As a result, it is concluded that amylolytic hydrolysis of native starch granules is governed by the specific surface area, not by the mass concentration, of each granule.

Localization of SERBP1 in stress granules and nucleoli.

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Lee, Yu-Jen; Wei, Hung-Ming; Chen, Ling-Yun; Li, Chuan

2014-01-01

SERPINE1 mRNA-binding protein 1 (SERBP1) is an arginine-methylated RNA-binding protein whose modification affects protein interaction and intracellular localization. In the present study, we show that, under normal growth conditions without stress, SERBP1 interacts with arginine-methylated and stress granule-associated proteins such as heterogeneous nuclear ribonucleoprotein A1, fragile X mental retardation protein and fragile X mental retardation syndrome-related protein 1 in an RNA-dependent manner. We also show that, after arsenite treatment, a proportion of full-length SERBP1 protein co-localizes with the typical stress granule marker T-cell intracellular antigen-1 in the cytoplasmic stress granules. Truncated SERBP1 with an N-terminal, central RG or C-terminal deletion, or single-domain segments comprising the N-terminal, central or C-terminal region, were recruited to stress granules upon arsenite treatment but with reduced efficiency. In addition, upon arsenite treatment, the localization of SERBP1 changed from a diffuse cytoplasmic localization to nuclear-dominant (concentrated in the nucleolus) A similar distribution was observed when cells were treated with the methylation inhibitor adenosine periodate, and was also detected for N- or C-terminal domain deletions and all three single-domain fragments even without stress induction. We further demonstrate that adenosine periodate treatment delays the association/dissociation of SERBP1 with stress granules. Hypomethylation retains SERBP1 in the nucleus/nucleolus regardless of arsenite treatment. Our study indicates that arginine methylation is correlated with recruitment of SERBP to stress granules and nucleoli and its retention therein. To our knowledge, this is the first report of an RNA-binding protein that is shifted simultaneously to cytoplasmic stress granules and nucleoli, two ribonucleoprotein-enriched subcellular compartments, upon stress. © 2013 FEBS.

CSR-1 and P granules suppress sperm-specific transcription in the C. elegans germline.

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Campbell, Anne C; Updike, Dustin L

2015-05-15

Germ granules (P granules) in C. elegans are required for fertility and function to maintain germ cell identity and pluripotency. Sterility in the absence of P granules is often accompanied by the misexpression of soma-specific proteins and the initiation of somatic differentiation in germ cells. To investigate whether this is caused by the accumulation of somatic transcripts, we performed mRNA-seq on dissected germlines with and without P granules. Strikingly, we found that somatic transcripts do not increase in the young adult germline when P granules are impaired. Instead, we found that impairing P granules causes sperm-specific mRNAs to become highly overexpressed. This includes the accumulation of major sperm protein (MSP) transcripts in germ cells, a phenotype that is suppressed by feminization of the germline. A core component of P granules, the endo-siRNA-binding Argonaute protein CSR-1, has recently been ascribed with the ability to license transcripts for germline expression. However, impairing CSR-1 has very little effect on the accumulation of its mRNA targets. Instead, we found that CSR-1 functions with P granules to prevent MSP and sperm-specific mRNAs from being transcribed in the hermaphrodite germline. These findings suggest that P granules protect germline integrity through two different mechanisms, by (1) preventing the inappropriate expression of somatic proteins at the level of translational regulation, and by (2) functioning with CSR-1 to limit the domain of sperm-specific expression at the level of transcription. © 2015. Published by The Company of Biologists Ltd.

MDMA-induced loss of parvalbumin interneurons within the dentate gyrus is mediated by 5HT2A and NMDA receptors.

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Collins, Stuart A; Gudelsky, Gary A; Yamamoto, Bryan K

2015-08-15

MDMA is a widely abused psychostimulant which causes a rapid and robust release of the monoaminergic neurotransmitters dopamine and serotonin. Recently, it was shown that MDMA increases extracellular glutamate concentrations in the dorsal hippocampus, which is dependent on serotonin release and 5HT2A/2C receptor activation. The increased extracellular glutamate concentration coincides with a loss of parvalbumin-immunoreactive (PV-IR) interneurons of the dentate gyrus region. Given the known susceptibility of PV interneurons to excitotoxicity, we examined whether MDMA-induced increases in extracellular glutamate in the dentate gyrus are necessary for the loss of PV cells in rats. Extracellular glutamate concentrations increased in the dentate gyrus during systemic and local administration of MDMA. Administration of the NMDA receptor antagonist, MK-801, during systemic injections of MDMA, prevented the loss of PV-IR interneurons seen 10 days after MDMA exposure. Local administration of MDL100907, a selective 5HT2A receptor antagonist, prevented the increases in glutamate caused by reverse dialysis of MDMA directly into the dentate gyrus and prevented the reduction of PV-IR. These findings provide evidence that MDMA causes decreases in PV within the dentate gyrus through a 5HT2A receptor-mediated increase in glutamate and subsequent NMDA receptor activation. Copyright © 2015 Elsevier B.V. All rights reserved.

Trim9 Deletion Alters the Morphogenesis of Developing and Adult-Born Hippocampal Neurons and Impairs Spatial Learning and Memory.

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Winkle, Cortney C; Olsen, Reid H J; Kim, Hyojin; Moy, Sheryl S; Song, Juan; Gupton, Stephanie L

2016-05-04

During hippocampal development, newly born neurons migrate to appropriate destinations, extend axons, and ramify dendritic arbors to establish functional circuitry. These developmental stages are recapitulated in the dentate gyrus of the adult hippocampus, where neurons are continuously generated and subsequently incorporate into existing, local circuitry. Here we demonstrate that the E3 ubiquitin ligase TRIM9 regulates these developmental stages in embryonic and adult-born mouse hippocampal neurons in vitro and in vivo Embryonic hippocampal and adult-born dentate granule neurons lacking Trim9 exhibit several morphological defects, including excessive dendritic arborization. Although gross anatomy of the hippocampus was not detectably altered by Trim9 deletion, a significant number of Trim9(-/-) adult-born dentate neurons localized inappropriately. These morphological and localization defects of hippocampal neurons in Trim9(-/-) mice were associated with extreme deficits in spatial learning and memory, suggesting that TRIM9-directed neuronal morphogenesis may be involved in hippocampal-dependent behaviors. Appropriate generation and incorporation of adult-born neurons in the dentate gyrus are critical for spatial learning and memory and other hippocampal functions. Here we identify the brain-enriched E3 ubiquitin ligase TRIM9 as a novel regulator of embryonic and adult hippocampal neuron shape acquisition and hippocampal-dependent behaviors. Genetic deletion of Trim9 elevated dendritic arborization of hippocampal neurons in vitro and in vivo Adult-born dentate granule cells lacking Trim9 similarly exhibited excessive dendritic arborization and mislocalization of cell bodies in vivo These cellular defects were associated with severe deficits in spatial learning and memory. Copyright © 2016 the authors 0270-6474/16/364940-19$15.00/0.

Postnatal development of the hippocampal dentate gyrus under normal and experimental conditions

International Nuclear Information System (INIS)

Altman, J.; Bayer, S.

Studies on postnatal maturation of the dentate gyrus are reviewed. Some topics discussed are: normal development of the dentate gyrus, cytogenesis, morphogenesis, synaptogenesis, gleogenesis, myelogenesis, development of the gyrus under experimental conditions, and effects of x radiation on cytogenesis and morphogenesis

3-nitropropionic acid neurotoxicity in hippocampal slice cultures

DEFF Research Database (Denmark)

Noer, Helle; Kristensen, Bjarne W; Noraberg, Jens

2002-01-01

: CA1 > CA3 > fascia dentata. In low glucose much lower concentrations of 3-NP (25 microM) triggered neurotoxicity. One-week-old cultures were less susceptible to 3-NP toxicity than 3-week-old cultures, but the dentate granule cells were relatively more affected in the immature cultures. We found...

Stress-induced gene expression and behavior are controlled by DNA methylation and methyl donor availability in the dentate gyrus

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Saunderson, Emily A.; Spiers, Helen; Gutierrez-Mecinas, Maria; Trollope, Alexandra F.; Shaikh, Abeera; Mill, Jonathan; Reul, Johannes M. H. M.

2016-01-01

Stressful events evoke long-term changes in behavioral responses; however, the underlying mechanisms in the brain are not well understood. Previous work has shown that epigenetic changes and immediate-early gene (IEG) induction in stress-activated dentate gyrus (DG) granule neurons play a crucial role in these behavioral responses. Here, we show that an acute stressful challenge [i.e., forced swimming (FS)] results in DNA demethylation at specific CpG (5′-cytosine–phosphate–guanine-3′) sites close to the c-Fos (FBJ murine osteosarcoma viral oncogene homolog) transcriptional start site and within the gene promoter region of Egr-1 (early growth response protein 1) specifically in the DG. Administration of the (endogenous) methyl donor S-adenosyl methionine (SAM) did not affect CpG methylation and IEG gene expression at baseline. However, administration of SAM before the FS challenge resulted in an enhanced CpG methylation at the IEG loci and suppression of IEG induction specifically in the DG and an impaired behavioral immobility response 24 h later. The stressor also specifically increased the expression of the de novo DNA methyltransferase Dnmt3a [DNA (cytosine-5-)-methyltransferase 3 alpha] in this hippocampus region. Moreover, stress resulted in an increased association of Dnmt3a enzyme with the affected CpG loci within the IEG genes. No effects of SAM were observed on stress-evoked histone modifications, including H3S10p-K14ac (histone H3, phosphorylated serine 10 and acetylated lysine-14), H3K4me3 (histone H3, trimethylated lysine-4), H3K9me3 (histone H3, trimethylated lysine-9), and H3K27me3 (histone H3, trimethylated lysine-27). We conclude that the DNA methylation status of IEGs plays a crucial role in FS-induced IEG induction in DG granule neurons and associated behavioral responses. In addition, the concentration of available methyl donor, possibly in conjunction with Dnmt3a, is critical for the responsiveness of dentate neurons to environmental

Moderate traumatic brain injury causes acute dendritic and synaptic degeneration in the hippocampal dentate gyrus.

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Xiang Gao

Full Text Available Hippocampal injury-associated learning and memory deficits are frequent hallmarks of brain trauma and are the most enduring and devastating consequences following traumatic brain injury (TBI. Several reports, including our recent paper, showed that TBI brought on by a moderate level of controlled cortical impact (CCI induces immature newborn neuron death in the hippocampal dentate gyrus. In contrast, the majority of mature neurons are spared. Less research has been focused on these spared neurons, which may also be injured or compromised by TBI. Here we examined the dendrite morphologies, dendritic spines, and synaptic structures using a genetic approach in combination with immunohistochemistry and Golgi staining. We found that although most of the mature granular neurons were spared following TBI at a moderate level of impact, they exhibited dramatic dendritic beading and fragmentation, decreased number of dendritic branches, and a lower density of dendritic spines, particularly the mushroom-shaped mature spines. Further studies showed that the density of synapses in the molecular layer of the hippocampal dentate gyrus was significantly reduced. The electrophysiological activity of neurons was impaired as well. These results indicate that TBI not only induces cell death in immature granular neurons, it also causes significant dendritic and synaptic degeneration in pathohistology. TBI also impairs the function of the spared mature granular neurons in the hippocampal dentate gyrus. These observations point to a potential anatomic substrate to explain, in part, the development of posttraumatic memory deficits. They also indicate that dendritic damage in the hippocampal dentate gyrus may serve as a therapeutic target following TBI.

How informative are spatial CA3 representations established by the dentate gyrus?

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Erika Cerasti

2010-04-01

Full Text Available In the mammalian hippocampus, the dentate gyrus (DG is characterized by sparse and powerful unidirectional projections to CA3 pyramidal cells, the so-called mossy fibers. Mossy fiber synapses appear to duplicate, in terms of the information they convey, what CA3 cells already receive from entorhinal cortex layer II cells, which project both to the dentate gyrus and to CA3. Computational models of episodic memory have hypothesized that the function of the mossy fibers is to enforce a new, well-separated pattern of activity onto CA3 cells, to represent a new memory, prevailing over the interference produced by the traces of older memories already stored on CA3 recurrent collateral connections. Can this hypothesis apply also to spatial representations, as described by recent neurophysiological recordings in rats? To address this issue quantitatively, we estimate the amount of information DG can impart on a new CA3 pattern of spatial activity, using both mathematical analysis and computer simulations of a simplified model. We confirm that, also in the spatial case, the observed sparse connectivity and level of activity are most appropriate for driving memory storage-and not to initiate retrieval. Surprisingly, the model also indicates that even when DG codes just for space, much of the information it passes on to CA3 acquires a non-spatial and episodic character, akin to that of a random number generator. It is suggested that further hippocampal processing is required to make full spatial use of DG inputs.

Mast cell granules modulate alveolar macrophage respiratory-burst activity and eicosanoid metabolism.

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Rock, M J; Despot, J; Lemanske, R F

1990-10-01

Alveolar macrophages (AMs) and mast cells reside in the airway, and both have been demonstrated to contribute independently to allergic inflammatory responses through the generation of respiratory-burst metabolites and the release of biologically active mediators, respectively. Since mast cell granules (MCGs) contain mediators that could potentially interact with the AM respiratory burst, we investigated the effects of isolated MCGs on this important inflammatory pathway of the AM. MCGs and AMs were obtained by peritoneal and tracheoalveolar lavage, respectively, of Sprague-Dawley rats. First, the overall respiratory-burst activity was measured by luminal-enhanced chemiluminescence (CL), and second, the individual oxygen species contributing to CL (superoxide anion [O2-], hydrogen peroxide [H2O2], and hypochlorous acid) were measured. MCGs alone enhanced AM CL responses to an equivalent degree compared to zymosan-stimulated AMs. However, AMs preincubated with MCGs followed by zymosan stimulation significantly and synergistically enhanced the CL responses. This enhanced CL was not due to an increased production of O2-, H2O2, or hypochlorous acid; in fact, there were decreased measured amounts of O2- and H2O2 from zymosan-stimulated AMs in the presence of MCGs, most likely caused by the content of granules of superoxide dismutase and peroxidase, respectively. The lipoxygenase inhibitor, nordihydroguaiaretic acid, completely abolished the enhanced CL of AM preincubated with MCGs and subsequently stimulated by zymosan, but O2- production was not affected by nordihydroguaiaretic acid. Taken together, these results suggest that derivatives of arachidonic acid metabolism, most likely those of the lipoxygenase pathway, are responsible for the enhanced AM CL response observed in the presence of MCGs. Thus, mast cell-macrophage interactions may be important within the airway in enhancing the generation of mediators that contribute to tissue inflammation and bronchospasm.

Aspergillus oryzae AoSO is a novel component of stress granules upon heat stress in filamentous fungi.

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Hsiang-Ting Huang

Full Text Available Stress granules are a type of cytoplasmic messenger ribonucleoprotein (mRNP granule formed in response to the inhibition of translation initiation, which typically occurs when cells are exposed to stress. Stress granules are conserved in eukaryotes; however, in filamentous fungi, including Aspergillus oryzae, stress granules have not yet been defined. For this reason, here we investigated the formation and localization of stress granules in A. oryzae cells exposed to various stresses using an EGFP fusion protein of AoPab1, a homolog of Saccharomyces cerevisiae Pab1p, as a stress granule marker. Localization analysis showed that AoPab1 was evenly distributed throughout the cytoplasm under normal growth conditions, and accumulated as cytoplasmic foci mainly at the hyphal tip in response to stress. AoSO, a homolog of Neurospora crassa SO, which is necessary for hyphal fusion, colocalized with stress granules in cells exposed to heat stress. The formation of cytoplasmic foci of AoSO was blocked by treatment with cycloheximide, a known inhibitor of stress granule formation. Deletion of the Aoso gene had effects on the formation and localization of stress granules in response to heat stress. Our results suggest that AoSO is a novel component of stress granules specific to filamentous fungi. The authors would specially like to thank Hiroyuki Nakano and Kei Saeki for generously providing experimental and insightful opinions.

On the so-called membrane coating granules in keratinized lichen planus lesions of the buccal mucosa.

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El-Labban, N G; Wood, R D

1982-11-01

Serial sections of the so-called membrane-coating granules have been examined in keratinized oral epithelium of lichen planus lesions. As with 'granules' apparent in non-keratinized epithelium, it is found they do not represent specialized intra-cytoplasmic organelles, but are the result of sectioning at different areas, levels and planes through the plasma membrane of interdigitating cell processes. Such 'granules' appear mostly in the superficial, but not deep, part of the cytoplasm of the upper prickle cells. This is considered to be due to topographic differences between the upper and under surfaces of these cells and the presence of narrower intercellular spaces than those between deeper epithelial cells. Such arrangement often results in cell processes in sections appearing free in the superficial part of the cell below. The appearance of 'granules' arises when the plane of section is not at right angles to the two plasma membranes surrounding these processes.

THE STUDY OF THE KINETIC OF NATURAL ZEOLITE GRANULES GROWTH AT DIFFERENT WAYS OF GRANULATION

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Rybachuk VD

2016-12-01

Full Text Available Introduction. Active substances and excipients used in the manufacture of medicines in tablet form, in most cases, have poor technological properties. This fact determines the need for prior granulation of mass before compression. Granulators of various sizes and designs, running on different modes, made the formation, growth and consolidation of the powder particles that lead to obtain pellets of different shapes and sizes. From the literature it is known that granulation leads to two forms of granules: isodiametric and nonisodiametric. The first group of particles forms has globular shape with a smooth surface and the proportion in which the length, thickness and height are about the same. They are usually made by fluidized bed granulation, spray drying, pelletizing and granulation in dragee pan. Granules of nonisodiametric form in which length is several times the width and height are made mostly by extrusion and compacting. The geometrical parameters of obtained granules are affected by the properties of raw materials, the granulation modes, type and amount of added humidifier and so on. The shape and size of granules, from a technological point of view, are the key factors that contribute, except organoleptic characteristics of the product, its technological properties such as particle size distribution, bulk volume, the ability of the material to shrinkage, porosity, fluidity, mechanical strength and so on. Properly selected for specific conditions granulation method is able to provide the finished product with the specified technological parameters depending on the needs. The aim of this work was to study the effect of granulation method and its conditions on the kinetics of growth of the natural zeolite granules and some quality characteristics of obtained granules. Material & methods. As objects of study served the natural zeolite pellets produced using 3%, 5%, 7% and 10% potato starch paste and solution of polyvinylpyrrolidone (PVP

TIA-1 Self-Multimerization, Phase Separation, and Recruitment into Stress Granules Are Dynamically Regulated by Zn2.

Science.gov (United States)

Rayman, Joseph B; Karl, Kevin A; Kandel, Eric R

2018-01-02

Stress granules are non-membranous structures that transiently form in the cytoplasm during cellular stress, where they promote translational repression of non-essential RNAs and modulate cell signaling by sequestering key signal transduction proteins. These and other functions of stress granules facilitate an adaptive cellular response to environmental adversity. A key component of stress granules is the prion-related RNA-binding protein, T cell intracellular antigen-1 (TIA-1). Here, we report that recombinant TIA-1 undergoes rapid multimerization and phase separation in the presence of divalent zinc, which can be reversed by the zinc chelator, TPEN. Similarly, the formation and maintenance of TIA-1-positive stress granules in arsenite-treated cells are inhibited by TPEN. In addition, Zn 2+ is released in cells treated with arsenite, before stress granule formation. These findings suggest that Zn 2+ is a physiological ligand of TIA-1, acting as a stress-inducible second messenger to promote multimerization of TIA-1 and subsequent localization into stress granules. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Effects of adult dysthyroidism on the morphology of hippocampal granular cells in rats.

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Martí-Carbonell, Maria Assumpció; Garau, Adriana; Sala-Roca, Josefina; Balada, Ferran

2012-01-01

Thyroid hormones are essential for normal brain development and very important in the normal functioning of the brain. Thyroid hormones action in the adult brain has not been widely studied. The effects of adult hyperthyroidism are not as well understood as adult hypothyroidism, mainly in hippocampal granular cells. The purpose of the present study is to assess the consequences of adult hormone dysthyroidism (excess/deficiency of TH) on the morphology of dentate granule cells in the hippocampus by performing a quantitative study of dendritic arborizations and dendritic spines using Golgi impregnated material. Hypo-and hyperthyroidism were induced in rats by adding 0.02 percent methimazole and 1 percent L-thyroxine, respectively, to drinking water from 40 days of age. At 89 days, the animals' brains were removed and stained by a modified Golgi method and blood samples were collected in order to measure T4 serum levels. Neurons were selected and drawn using a camera lucida. Our results show that both methimazole and thyroxine treatment affect granule cell morphology. Treatments provoke alterations in the same direction, namely, reduction of certain dendritic-branching parameters that are more evident in the methimazole than in the thyroxine group. We also observe a decrease in spine density in both the methimazole and thyroxine groups.

Identification of a multifunctional protein, PhaM, that determines number, surface to volume ratio, subcellular localization and distribution to daughter cells of poly(3-hydroxybutyrate), PHB, granules in Ralstonia eutropha H16.

Science.gov (United States)

Pfeiffer, Daniel; Wahl, Andreas; Jendrossek, Dieter

2011-11-01

A two-hybrid approach was applied to screen for proteins with the ability to interact with PHB synthase (PhaC1) of Ralstonia eutropha. The H16_A0141 gene (phaM) was identified in the majority of positive clones. PhaM (26.6 kDa) strongly interacted with PhaC1 and with phasin PhaP5 but not with PhaP1 or other PHB granule-associated proteins. A ΔphaM mutant accumulated only one or two large PHB granules instead of three to six medium-sized PHB granules of the wild type, and distribution of granules to daughter cells was disordered. All three phenotypes (number, size and distribution of PHB granules) were reversed by reintroduction of phaM. Purified PhaM revealed DNA-binding properties in gel mobility shift experiments. Expression of a fusion of the yellow fluorescent protein (eYfp) with PhaM resulted in formation of many small fluorescent granules that were bound to the nucleoid region. Remarkably, an eYfp-PhaP5 fusion localized at the cell poles in a PHB-negative background and overexpression of eYfp-PhaP5 in the wild type conferred binding of PHB granules to the cell poles. In conclusion, subcellular localization of PHB granules in R. eutropha depends on a concerted expression of at least three PHB granule-associated proteins, namely PhaM, PhaP5 and PHB synthase PhaC1. © 2011 Blackwell Publishing Ltd.

Basic fibroblast growth factor enhances cell proliferation in the dentate gyrus of neonatal rats following hypoxic-ischemic brain damage.

Science.gov (United States)

Zhu, Huan; Qiao, Lixing; Sun, Yao; Yin, Liping; Huang, Li; Jiang, Li; Li, Jiaqing

2018-04-23

Perinatal hypoxic-ischemic insult is considered a major contributor to child mortality and morbidity and leads to neurological deficits in newborn infants. There has been a lack of promising neurotherapeutic interventions for hypoxic-ischemic brain damage (HIBD) for clinical application in infants. The present study aimed to investigate the correlation between neurogenesis and basic fibroblast growth factor (bFGF) in the hippocampal dentate gyrus (DG) region in neonatal rats following HIBD. Cell proliferation was examined by detecting BrdU signals, and the role of bFGF in cell proliferation in the DG region following neonatal HIBD was investigated. Cell proliferation was induced by HIBD in the hippocampal DG of neonatal rats. Furthermore, bFGF gene expression was upregulated in the hippocampus in neonatal rats, particularly between 7 and 14 days after HIBD. Moreover, intraperitoneal injection of exogenous bFGF enhanced cell proliferation in the hippocampal DG following neonatal HIBD. Taken together, these data indicate that cell proliferation in the DG could be induced by neonatal HIBD, and bFGF promotes proliferation following neonatal HIBD. Copyright © 2018 Elsevier B.V. All rights reserved.

Stimulation of the N-methyl-D-aspartate receptor has a trophic effect on differentiating cerebellar granule cells

DEFF Research Database (Denmark)

Balázs, R; Hack, N; Jørgensen, Ole Steen

1988-01-01

N-methyl-D-aspartate (NMDA) supplementation of cerebellar cultures enriched in granule neurones (about 90%) prevented the extensive cell loss which occurs when cultivation takes place, in serum containing media, in the presence of 'low' K+ (5-15 mM). Estimation of tetanus toxin receptors and N-CA...

Difference in distribution of membrane proteins between low- and high-density secretory granules in parotid acinar cells

International Nuclear Information System (INIS)

Fujita-Yoshigaki, Junko; Katsumata, Osamu; Matsuki, Miwako; Yoshigaki, Tomoyoshi; Furuyama, Shunsuke; Sugiya, Hiroshi

2006-01-01

Secretory granules (SGs) are considered to be generated as immature granules and to mature by condensation of their contents. In this study, SGs of parotid gland were separated into low-, medium-, and high-density granule fractions by Percoll-density gradient centrifugation, since it was proposed that the density corresponds to the degree of maturation. The observation with electron microscopy showed that granules in the three fractions were very similar. The average diameter of high-density granules was a little but significantly larger than that of low-density granules. Although the three fractions contained amylase, suggesting that they are all SGs, distribution of membrane proteins was markedly different. Syntaxin6 and VAMP4 were localized in the low-density granule fraction, while VAMP2 was concentrated in the high-density granule fraction. Immunoprecipitation with anti-syntaxin6 antibody caused coprecipitation of VAMP2 from the medium-density granule fraction without solubilization, but not from Triton X-100-solubilized fraction, while VAMP4 was coprecipitated from both fractions. Therefore, VAMP2 is present on the same granules, but is separated from syntaxin6 and VAMP4, which are expected to be removed from immature granules. These results suggest that the medium-density granules are intermediates from low- to high-density granules, and that the membrane components of SGs dynamically change by budding and fusion during maturation

TIA-1 Self-Multimerization, Phase Separation, and Recruitment into Stress Granules Are Dynamically Regulated by Zn2+

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Joseph B. Rayman

2018-01-01

Full Text Available Summary: Stress granules are non-membranous structures that transiently form in the cytoplasm during cellular stress, where they promote translational repression of non-essential RNAs and modulate cell signaling by sequestering key signal transduction proteins. These and other functions of stress granules facilitate an adaptive cellular response to environmental adversity. A key component of stress granules is the prion-related RNA-binding protein, T cell intracellular antigen-1 (TIA-1. Here, we report that recombinant TIA-1 undergoes rapid multimerization and phase separation in the presence of divalent zinc, which can be reversed by the zinc chelator, TPEN. Similarly, the formation and maintenance of TIA-1-positive stress granules in arsenite-treated cells are inhibited by TPEN. In addition, Zn2+ is released in cells treated with arsenite, before stress granule formation. These findings suggest that Zn2+ is a physiological ligand of TIA-1, acting as a stress-inducible second messenger to promote multimerization of TIA-1 and subsequent localization into stress granules. : Rayman et al. show that Zn2+ is a stress-inducible second messenger that triggers self-multimerization and phase separation of TIA-1 and regulates dynamic recruitment of TIA-1 into stress granules. This mechanism is part of an adaptive cellular response to environmental adversity. Keywords: TIA-1, TIA1, stress granules, cellular stress, functional prion, phase separation, zinc regulation

Expression of glutamic acid decarboxylase and identification of GABAergic cells in the ischemic rat dentate gyrus

DEFF Research Database (Denmark)

Müller, Georg Johannes; Dogonowski, Anne-Marie; Finsen, Bente

2006-01-01

We have investigated the glutamic acid dexcarboxylase (GAD) mRNA and protein isoforms as markers for ischemic loss of GABAergic neurons in the dentate hilus. Stereological counts of these neurons were performed in rats surviving 8 days after 10 min of transient forebrain ischemia, and in control...

The functional morphology of color changing in a spider: development of ommochrome pigment granules.

Science.gov (United States)

Insausti, Teresita C; Casas, Jérôme

2008-03-01

Studies on the formation of ommochrome pigment granules are very few, despite their generalized occurrence as screening pigments in insect eyes. This is particularly true for ommochrome granules responsible for epidermal coloration. The aims of this study were to characterize the localization of major body pigments in a color changing mimetic spider, Misumena vatia (Thomisidae), and to describe the formation and location of ommochrome pigment granules responsible for the spider's color change from white to yellow. The unpigmented cuticula of this spider is transparent. Both the guanine localized in guanine cells in the opisthosoma and the uric acid localized in epidermis cells in the prosoma are responsible for the white coloration. The bright yellow color is due to the combination of ommochrome pigment granules and the white reflectance from coincident guanine and/or uric acid. The formation of ommochrome pigment granules in epidermis cells proceeds via three distinctive steps. Translucent, UV fluorescent, progranules (type I) are produced by a dense network of endoplasmic reticulum associated with numerous mitochondria and glycogen rosettes. These progranules are present in white spiders only, and regularly distributed in the cytoplasm. The merging of several progranules of type I into a transient state (progranule type II) leads to the formation of granules (type III) characterized by their lack of fluorescence, their spherical sections and their osmophilic-electron-dense contents. They are found in yellow spiders and in the red stripes on the body sides. Their color varies from yellow to red. Thus, white spiders contain only type I granules, yellow tinted spiders contain type II and III granules and bright yellow spiders contain only type III granules. We present a synthetic view of the ontogeny of ommochrome granules. We discuss the physiology of color changing and the nature of the chemical compounds in the different types of granules. Extended studies on the

Distribution of binder in granules produced by means of twin screw granulation

DEFF Research Database (Denmark)

Fonteyne, Margot; Fussell, Andrew Luke; Vercruysse, Jurgen

2014-01-01

According to the quality by design principle processes may not remain black-boxes and full process understanding is required. The granule size distribution of granules produced via twin screw granulation is often found to be bimodal. The aim of this study was to gain a better understanding...

In vivo Anomalous Diffusion and Weak Ergodicity Breaking of Lipid Granules

DEFF Research Database (Denmark)

Jeon, J.-H.; Tejedor, V.; Burov, S.

2011-01-01

Combining extensive single particle tracking microscopy data of endogenous lipid granules in living fission yeast cells with analytical results we show evidence for anomalous diffusion and weak ergodicity breaking. Namely we demonstrate that at short times the granules perform subdiffusion...... according to the laws of continuous time random walk theory. The associated violation of ergodicity leads to a characteristic turnover between two scaling regimes of the time averaged mean squared displacement. At longer times the granule motion is consistent with fractional Brownian motion....

Synaptic Homeostasis and Allostasis in the Dentate Gyrus Caused by Inflammatory and Neuropathic Pain Conditions

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Rui-Rui Wang

2018-01-01

Full Text Available It has been generally accepted that pain can cause imbalance between excitation and inhibition (homeostasis at the synaptic level. However, it remains poorly understood how this imbalance (allostasis develops in the CNS under different pain conditions. Here, we analyzed the changes in both excitatory and inhibitory synaptic transmission and modulation of the dentate gyrus (DG under two pain conditions with different etiology and duration. First, it was revealed that the functions of the input-output (I/O curves for evoked excitatory postsynaptic currents (eEPSCs following the perforant path (PP stimulation were gained under both acute inflammatory and chronic neuropathic pain conditions relative to the controls. However, the functions of I/O curves for the PP-evoked inhibitory postsynaptic currents (eIPSCs differed between the two conditions, namely it was greatly gained under inflammatory condition, but was reduced under neuropathic condition in reverse. Second, both the frequency and amplitude of miniature IPSCs (mIPSCs were increased under inflammatory condition, however a decrease in frequency of mIPSCs was observed under neuropathic condition. Finally, the spike discharge of the DG granule cells in response to current injection was significantly increased by neuropathic pain condition, however, no different change was found between inflammatory pain condition and the control. These results provide another line of evidence showing homeostatic and allostatic modulation of excitatory synaptic transmission by inhibitory controls under different pathological pain conditions, hence implicating use of different therapeutic approaches to maintain the homeostasis between excitation and inhibition while treating different conditions of pathological pain.

The paradox of high shear granulation : the formation of non-homogeneous granules

NARCIS (Netherlands)

Dries, Kaspar van den

2004-01-01

Wet granulation is a process used for the particle size enlargement of primary powders. The mixing of a liquid with the powder glues the primary particles together, which results in the formation of the granules. The mixing action can be performed in many ways, like tumbling (drum granulation),

Lipopolysaccharide-binding protein: localization in secretory granules of Paneth cells in the mouse small intestine

DEFF Research Database (Denmark)

Hansen, Gert H; Rasmussen, Karina; Niels-Christiansen, Lise-Lotte

2009-01-01

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase protein involved in the host's response to endotoxin and mainly synthesized and secreted to the blood by the liver. But in addition, LBP is also made by extrahepatic cells, including the enterocyte-like cell line Caco-2. To study...... in closer detail the synthesis and storage of LBP in the intestinal mucosal epithelium, we performed an immunolocalization of LBP in mouse small intestine. By immunofluorescence microscopy, an antibody recognizing the 58-60 kDa protein of LBP distinctly labeled a small population of cells located deep...... into the crypts. This cell population was also positive for lysozyme and alpha-defensin 4, identifying Paneth cells as the main intestinal LBP-producing cells. By immunogold electron microscopy, intense labeling was observed in the secretory granules of these cells. We conclude that Paneth cells express LBP...

Mandibular thickness measurements in young dentate adults.

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Beaty, Narlin B; Le, Thomas T

2009-09-01

To measure thicknesses in clinical landmark areas of the dentate mandibles of young men and women. Using standard radiologic software, we obtained mean (SD) thickness measurements at the inferior or posterior borders of the mandible at the following 7 surgically useful sites: (1) the symphysis, (2) a point halfway between the symphysis and the mental nerve, (3) the mental nerve, (4) a point halfway between the mental nerve and the facial artery notch, (5) the facial artery notch, (6) the angle vertex, and (7) the ramus-condylar neck border. University hospital. A total of 150 dentate men and 75 dentate women aged 18 to 30 years who had undergone computed tomography of the head and neck region during the period of December 20, 2006 to February 20, 2007. Thicknesses of 7 mandibular sites. Mean (SD) thicknesses at the 7 mandibular sites were as follows: symphysis, 14.03 (1.53) mm for men and 13.21 (1.46) mm for women; halfway between the symphysis and the mental nerve, 11.17 (1.37) mm for men and 10.00 (1.08) mm for women; mental nerve, 9.48 (1.28) mm for men and 8.72 (1.00) mm for women; halfway between the mental nerve and the facial artery notch, 10.33 (1.24) mm for men and 9.45 (0.92) mm for women; facial artery notch, 7.27 (0.82) mm for men and 7.10 (0.88) mm for women; angle vertex, 5.42 (0.90) mm for men and 5.39 (0.66) mm for women; and ramus-condylar neck border, 5.90 (0.86) mm for men and 5.85 (0.71) mm for women. Clinical landmark areas in young dentate mandibles have mean thicknesses with limited SDs. The thickness measurements obtained at the sites in this study provide practical reference information for mandibular reconstruction and bicortical screw length estimation.

GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

International Nuclear Information System (INIS)

Boku, Shuken; Nakagawa, Shin; Takamura, Naoki; Kato, Akiko; Takebayashi, Minoru; Hisaoka-Nakashima, Kazue; Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro

2013-01-01

Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis

GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

Energy Technology Data Exchange (ETDEWEB)

Boku, Shuken, E-mail: shuboku@med.hokudai.ac.jp [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Nakagawa, Shin [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takamura, Naoki [Pharmaceutical Laboratories, Dainippon Sumitomo Pharma Co. Ltd., Osaka (Japan); Kato, Akiko [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takebayashi, Minoru [Department of Psychiatry, National Hospital Organization Kure Medical Center, Kure (Japan); Hisaoka-Nakashima, Kazue [Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima (Japan); Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)

2013-05-17

Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis.

Dannelse af nye nerveceller i den voksne hjerne

DEFF Research Database (Denmark)

Poulsen, Frantz Rom; Meyer, Morten; Rasmussen, Jens Zimmer

2003-01-01

neurogenesis in the adult human brain. In particular two brain regions show continuous division of neural stem and progenitor cells generating neurons and glial cells, namely the subgranular zone of the dentate gyrus and the subventricular zones of the lateral ventricles. From the latter region newly generated......Generation of new nerve cells (neurogenesis) is normally considered to be limited to the fetal and early postnatal period. Thus, damaged nerve cells are not expected to be replaced by generation of new cells. The brain is, however, more plastic than previously assumed. This also includes...... neuroblasts (immature nerve cells) migrate toward the olfactory bulb where they differentiate into neurons. In the dentate gyrus the newly generated neurons become functionally integrated in the granule cell layer, where they are believed to be of importance to learning and memory. It is at present not known...

Postischemic Anhedonia Associated with Neurodegenerative Changes in the Hippocampal Dentate Gyrus of Rats

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Jiro Kasahara

2016-01-01

Full Text Available Poststroke depression is one of the major symptoms observed in the chronic stage of brain stroke such as cerebral ischemia. Its pathophysiological mechanisms, however, are not well understood. Using the transient right middle cerebral artery occlusion- (MCAO-, 90 min operated rats as an ischemia model in this study, we first observed that aggravation of anhedonia spontaneously occurred especially after 20 weeks of MCAO, and it was prevented by chronic antidepressants treatment (imipramine or fluvoxamine. The anhedonia specifically associated with loss of the granular neurons in the ipsilateral side of hippocampal dentate gyrus and was also prevented by an antidepressant imipramine. Immunohistochemical analysis showed increased apoptosis inside the granular cell layer prior to and associated with the neuronal loss, and imipramine seemed to recover the survival signal rather than suppressing the death signal to prevent neurons from apoptosis. Proliferation and development of the neural stem cells were increased transiently in the subgranular zone of both ipsi- and contralateral hippocampus within one week after MCAO and then decreased and almost ceased after 6 weeks of MCAO, while chronic imipramine treatment prevented them partially. Overall, our study suggests new insights for the mechanistic correlation between poststroke depression and the delayed neurodegenerative changes in the hippocampal dentate gyrus with effective use of antidepressants on them.

Ethanol induces MAP2 changes in organotypic hippocampal slice cultures

DEFF Research Database (Denmark)

Noraberg, J; Zimmer, J

1998-01-01

loss of CA3 pyramidal cells and moderate loss of dentate granule cells, as seen in vivo. The results indicate that brain slice cultures combined with immunostaining for cytoskeleton and neuronal markers can be used for studies of ethanol and organic solvent neurotoxicity.......Microtubule-associated protein 2 (MAP2) and neuron-specific protein (NeuN) immunostains were used to demonstrate neurotoxic effects in mature hippocampal slice cultures exposed to ethanol (50, 100, 200 mM) for 4 weeks. At the low dose the density of MAP2 immunostaining in the dentate molecular...... layer was 118% of the control cultures, with no detectable changes in CA1 and CA3. At 100 mM no changes were detected, while 200 mM ethanol significantly reduced the MAP2 density in both dentate (19%) and hippocampal dendritic fields (CA3, 52%; CA1, 55%). At this dose NeuN staining showed considerable...

Blockade of intracellular Zn2+ signaling in the basolateral amygdala affects object recognition memory via attenuation of dentate gyrus LTP.

Science.gov (United States)

Fujise, Yuki; Kubota, Mitsuyasu; Suzuki, Miki; Tamano, Haruna; Takeda, Atsushi

2017-09-01

Hippocampus-dependent memory is modulated by the amygdala. However, it is unknown whether intracellular Zn 2+ signaling in the amygdala is involved in hippocampus-dependent memory. On the basis of the evidence that intracellular Zn 2+ signaling in dentate granule cells (DGC) is necessary for object recognition memory via LTP at medial perforant pathway (PP)-DGC synapses, the present study examined whether intracellular Zn 2+ signaling in the amygdala influences object recognition memory via modulation of LTP at medial PP-DGC synapses. When ZnAF-2DA (100 μM, 2 μl) was injected into the basolateral amygdala (BLA), intracellular ZnAF-2 locally chelated intracellular Zn 2+ in the amygdala. Recognition memory was affected when training of object recognition test was performed 20 min after ZnAF-2DA injection into the BLA. Twenty minutes after injection of ZnAF-2DA into the BLA, LTP induction at medial PP-DGC synapses was attenuated, while LTP induction at PP-BLA synapses was potentiated and LTP induction at BLA-DGC synapses was attenuated. These results suggest that intracellular Zn 2+ signaling in the BLA is involved in BLA-associated LTP and modulates LTP at medial PP-DGC synapses, followed by modulation of object recognition memory. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application of tumbling melt granulation (TMG) method to prepare controlled-release fine granules.

Science.gov (United States)

Maejima, T; Kubo, M; Osawa, T; Nakajima, K; Kobayashi, M

1998-03-01

The tumbling melt granulation (TMG) method was applied to prepare controlled-release fine granules of diltiazem hydrochloride (DH). The entire process, from the preparation of the cores by the adherence of DH to the sucrose crystal to the subsequent coating of the controlled-release layer, was performed without using any solvent. A mixture of meltable material, talc, and ethylcellulose was used for the controlled-release layer and controlled-release fine granules approximately 400 microns in diameter were obtained with excellent producibility. The dissolution rate of DH from these fine granules was similar to that of a once-a-day dosage form obtained in the market; further, the dependency of the dissolution profile on pH of the media was less. Thus, it was concluded that this TMG method was very useful for preparing not only controlled-release beads of granule size (usually 500 to 1400 microns) but also fine granules.

The selective antagonism of P2X7 and P2Y1 receptors prevents synaptic failure and affects cell proliferation induced by oxygen and glucose deprivation in rat dentate gyrus.

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Giovanna Maraula

Full Text Available Purinergic P2X and P2Y receptors are broadly expressed on both neurons and glial cells in the central nervous system (CNS, including dentate gyrus (DG. The aim of this research was to determine the synaptic and proliferative response of the DG to severe oxygen and glucose deprivation (OGD in acute rat hippocampal slices and to investigate the contribution of P2X7 and P2Y1 receptor antagonism to recovery of synaptic activity after OGD. Extracellular field excitatory post-synaptic potentials (fEPSPs in granule cells of the DG were recorded from rat hippocampal slices. Nine-min OGD elicited an irreversible loss of fEPSP and was invariably followed by the appearance of anoxic depolarization (AD. Application of MRS2179 (selective antagonist of P2Y1 receptor and BBG (selective antagonist of P2X7 receptor, before and during OGD, prevented AD appearance and allowed a significant recovery of neurotransmission after 9-min OGD. The effects of 9-min OGD on proliferation and maturation of cells localized in the subgranular zone (SGZ of slices prepared from rats treated with 5-Bromo-2'-deoxyuridine (BrdU were investigated. Slices were further incubated with an immature neuron marker, doublecortin (DCX. The number of BrdU+ cells in the SGZ was significantly decreased 6 hours after OGD. This effect was antagonized by BBG, but not by MRS2179. Twenty-four hours after 9-min OGD, the number of BrdU+ cells returned to control values and a significant increase of DCX immunofluorescence was observed. This phenomenon was still evident when BBG, but not MRS2179, was applied during OGD. Furthermore, the P2Y1 antagonist reduced the number of BrdU+ cells at this time. The data demonstrate that P2X7 and P2Y1 activation contributes to early damage induced by OGD in the DG. At later stages after the insult, P2Y1 receptors might play an additional and different role in promoting cell proliferation and maturation in the DG.

Effects of x-irradiation induced loss of cerebellar granule cells on the synaptosomal levels and the high affinity uptake of amino acids

International Nuclear Information System (INIS)

Rohde, B.H.; Rea, M.A.; Simon, J.R.; McBride, W.J.

1979-01-01

Crude synaptosomal (P 2 ) preparations were obtained from the cerebella of rats in which the granule cell population had been selectively reduced by X-irradiation treatment and from the cerebella of control animals. In the P 2 fraction form control cerebella, the level of glutamate was greater than any other of the 5 amino acids measured and was 2-fold higher than taurine. The content of taurine, GABA, glycine, and alanine were not changed by the X-irradiation treatment. The uptake of 1.0 micrometers-L-[ 3 H]glutamate and L-[ 3 H]aspartate was reduced approx 20% by X-irradiation treatment, whereas the uptake of 1.0 micrometers-[ 3 H]GABA and [ 3 H]taurine was unchanged. In a second study, the uptake of L-[ 3 H]glutamate, L-[ 3 H]aspartate and [ 3 H]GABA was measured using P 2 fractions obtained from the cerebella of rats in which the population of granule, stellate and basket cells had been reduced by X-irradiation treatment. The uptake of 1.0 micrometers-L-[ 3 H]glutamate, L-[ 3 H]aspartate and [ 3 H]GABA was significantly (P < 0.05) reduced to 57.68 and 59% respectively, of control values. The data are discussed in terms of glutamate being the excitatory neurotransmitter released from granule cells and GABA being the inhibitory neurotransmitter released from basket cells. (author)

Glomerular and Mitral-Granule Cell Microcircuits Coordinate Temporal and Spatial Information Processing in the Olfactory Bulb.

Science.gov (United States)

Cavarretta, Francesco; Marasco, Addolorata; Hines, Michael L; Shepherd, Gordon M; Migliore, Michele

2016-01-01

The olfactory bulb processes inputs from olfactory receptor neurons (ORNs) through two levels: the glomerular layer at the site of input, and the granule cell level at the site of output to the olfactory cortex. The sequence of action of these two levels has not yet been examined. We analyze this issue using a novel computational framework that is scaled up, in three-dimensions (3D), with realistic representations of the interactions between layers, activated by simulated natural odors, and constrained by experimental and theoretical analyses. We suggest that the postulated functions of glomerular circuits have as their primary role transforming a complex and disorganized input into a contrast-enhanced and normalized representation, but cannot provide for synchronization of the distributed glomerular outputs. By contrast, at the granule cell layer, the dendrodendritic interactions mediate temporal decorrelation, which we show is dependent on the preceding contrast enhancement by the glomerular layer. The results provide the first insights into the successive operations in the olfactory bulb, and demonstrate the significance of the modular organization around glomeruli. This layered organization is especially important for natural odor inputs, because they activate many overlapping glomeruli.

Glomerular and mitral-granule cell microcircuits coordinate temporal and spatial information processing in the olfactory bulb

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Francesco Cavarretta

2016-07-01

Full Text Available The olfactory bulb processes inputs from olfactory receptor neurons (ORNs through two levels: the glomerular layer at the site of input, and the granule cell level at the site of output to the olfactory cortex. The sequence of action of these two levels has not yet been examined. We analyze this issue using a novel computational framework that is scaled up, in three-dimensions (3D, with realistic representations of the interactions between layers, activated by simulated natural odors, and constrained by experimental and theoretical analyses. We suggest that the postulated functions of glomerular circuits have as their primary role transforming a complex and disorganized input into a contrast-enhanced and normalized representation, but cannot provide for synchronization of the distributed glomerular outputs. By contrast, at the granule cell layer, the dendrodendritic interactions mediate temporal decorrelation, which we show is dependent on the preceding contrast enhancement by the glomerular layer. The results provide the first insights into the successive operations in the olfactory bulb, and demonstrate the significance of the modular organization around glomeruli. This layered organization is especially important for natural odor inputs, because they activate many overlapping glomeruli.

Neutrophil glycoprotein Mo1 is an integral membrane protein of plasma membranes and specific granules

International Nuclear Information System (INIS)

Stevenson, K.B.; Nauseef, W.M.; Clark, R.A.

1987-01-01

The glucoprotein Mo1 has previously been demonstrated to be on the cell surface and in the specific granule fraction of neutrophils and to be translocated to the cell surface during degranulation. It is not known, however, whether Mo1 is an integral membrane protein or a soluble, intragranular constituent loosely associated with the specific granule membrane. Purified neutrophils were disrupted by nitrogen cavitation and separated on Percoll density gradients into four fractions enriched for azurophilic granules, specific granules, plasma membrane, and cytosol, respectively. The glycoproteins in these fractions were labeled with 3 H-borohydride reduction, extracted with Triton X-114, and immunoprecipitated with 60.3, an anti-Mo1 monoclonal antibody. Mo1 was detected only in the specific granule and plasma membrane fractions and partitioned exclusively into the detergent-rich fraction consistent with Mo1 being an integral membrane protein. In addition, treatment of specific granule membranes with a high salt, high urea buffer to remove adsorbed or peripheral proteins failed to dissociate Mo1. These data support the hypothesis that Mo1 is an integral membrane protein of plasma and specific granule membranes in human neutrophils

Stability and Function of Hippocampal Mossy Fiber Synapses Depend on Bcl11b/Ctip2

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Elodie De Bruyckere

2018-04-01

Full Text Available Structural and functional plasticity of synapses are critical neuronal mechanisms underlying learning and memory. While activity-dependent regulation of synaptic strength has been extensively studied, much less is known about the transcriptional control of synapse maintenance and plasticity. Hippocampal mossy fiber (MF synapses connect dentate granule cells to CA3 pyramidal neurons and are important for spatial memory formation and consolidation. The transcription factor Bcl11b/Ctip2 is expressed in dentate granule cells and required for postnatal hippocampal development. Ablation of Bcl11b/Ctip2 in the adult hippocampus results in impaired adult neurogenesis and spatial memory. The molecular mechanisms underlying the behavioral impairment remained unclear. Here we show that selective deletion of Bcl11b/Ctip2 in the adult mouse hippocampus leads to a rapid loss of excitatory synapses in CA3 as well as reduced ultrastructural complexity of remaining mossy fiber boutons (MFBs. Moreover, a dramatic decline of long-term potentiation (LTP of the dentate gyrus-CA3 (DG-CA3 projection is caused by adult loss of Bcl11b/Ctip2. Differential transcriptomics revealed the deregulation of genes associated with synaptic transmission in mutants. Together, our data suggest Bcl11b/Ctip2 to regulate maintenance and function of MF synapses in the adult hippocampus.

Anti-virus effect of traditional Chinese medicine Yi-Fu-Qing granule on acute respiratory tract infections.

Science.gov (United States)

Li, Anyuan; Xie, Yanying; Qi, Fanghua; Li, Jie; Wang, Peng; Xu, Shulan; Zhao, Lin

2009-08-01

Yi-Fu-Qing granule is a traditional Chinese medicine for the treatment of acute respiratory tract infections. The present study sought to investigate the anti-virus effects of Yi-Fu-Qing granule on acute respiratory infections with respiratory syncytial virus (RSV) and human adenoviruses type 3 (Ad3). The cytotoxicity of Yi-Fu-Qing granule was evaluated by the neutral red assay on HeLa cells. The antiviral effect of Yi-Fu-Qing granule was tested by observing the cytopathogenic effect (CPE) with a compound mixture of Isatis leaf as the positive control drug. The results indicated that the highest non-toxicity concentration of Yi-Fu-Qing granule on Hela cells was 1:100. The CPE reduction assay showed that Yi-Fu-Qing granule inhibited RSV and Ad3 replication at a concentration of 1:100. Thus, Yi-Fu-Qing granule may have a significant antivirus effect on acute respiratory tract infections with RSV and Ad3 infections and this could prove useful for further antivirus research on acute respiratory tract infections.

Effervescent Granules Prepared Using Eucommia ulmoides Oliv. and Moso Bamboo Leaves: Hypoglycemic Activity in HepG2 Cells

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Xiang-Zhou Li

2016-01-01

Full Text Available Eucommia ulmoides Oliv. (E. ulmoides Oliv. and moso bamboo (Phyllostachys pubescens leaves are used as folk medicines in central-western China to treat diabetes. To investigate the hypoglycemic activity of the effervescent granules prepared using E. ulmoides Oliv. and moso bamboo leaves (EBEG in HepG2 cells, EBEG were prepared with 5% of each of polysaccharides and chlorogenic acids from moso bamboo and E. ulmoides Oliv. leaves, respectively. HepG2 cells cultured in a high-glucose medium were classified into different groups. The results displayed EBEG-treated cells showed better glucose utilization than the negative controls; thus, the hypoglycemic effect of EBEG was much greater than that of granules prepared using either component alone, thereby indicating that this effect was due to a synergistic action of the components. Further, glucose consumption levels in the cells treated with EBEG (156.35% at 200 μg/mL and the positive controls (metformin, 162.29%; insulin, 161.52% were similar. Thus, EBEG exhibited good potential for use as a natural antidiabetic agent. The hypoglycemic effect of EBEG could be due to the synergistic action of polysaccharides from the moso bamboo leaves and chlorogenic acids from E. ulmoides Oliv. leaves via the inhibition of alpha-glucosidase and glucose-6-phosphate displacement enzyme.

Expression of the GABA(A) receptor alpha6 subunit in cultured cerebellar granule cells is developmentally regulated by activation of GABA(A) receptors

DEFF Research Database (Denmark)

Carlson, B X; Belhage, B; Hansen, Gert Helge

1997-01-01

Da (alpha6 subunit) radioactive peaks in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In contrast, THIP-treated granule cells at 8 DIV demonstrated a small but significant decrease from control cultures in the photoincorporation of [3H]Ro15-4513 in the 51-kDa peak; however...... that the major effect of THIP was to increase alpha6 subunit clustering on granule cell bodies as well as neurites, 15-fold and sixfold, respectively. Using in situ hybridization, a small THIP-induced increase in alpha6 mRNA was detected at 4 DIV; however, no effect was apparent at 8 DIV. These data suggest...

Impaired neuronal maturation of hippocampal neural progenitor cells in mice lacking CRAF.

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Pfeiffer, Verena; Götz, Rudolf; Camarero, Guadelupe; Heinsen, Helmut; Blum, Robert; Rapp, Ulf Rüdiger

2018-01-01

RAF kinases are major constituents of the mitogen activated signaling pathway, regulating cell proliferation, differentiation and cell survival of many cell types, including neurons. In mammals, the family of RAF proteins consists of three members, ARAF, BRAF, and CRAF. Ablation of CRAF kinase in inbred mouse strains causes major developmental defects during fetal growth and embryonic or perinatal lethality. Heterozygous germline mutations in CRAF result in Noonan syndrome, which is characterized by neurocognitive impairment that may involve hippocampal physiology. The role of CRAF signaling during hippocampal development and generation of new postnatal hippocampal granule neurons has not been examined and may provide novel insight into the cause of hippocampal dysfunction in Noonan syndrome. In this study, by crossing CRAF-deficiency to CD-1 outbred mice, a CRAF mouse model was established which enabled us to investigate the interplay of neural progenitor proliferation and postmitotic differentiation during adult neurogenesis in the hippocampus. Albeit the general morphology of the hippocampus was unchanged, CRAF-deficient mice displayed smaller granule cell layer (GCL) volume at postnatal day 30 (P30). In CRAF-deficient mice a substantial number of abnormal, chromophilic, fast dividing cells were found in the subgranular zone (SGZ) and hilus of the dentate gyrus (DG), indicating that CRAF signaling contributes to hippocampal neural progenitor proliferation. CRAF-deficient neural progenitor cells showed an increased cell death rate and reduced neuronal maturation. These results indicate that CRAF function affects postmitotic neural cell differentiation and points to a critical role of CRAF-dependent growth factor signaling pathway in the postmitotic development of adult-born neurons.

The F-actin modifier villin regulates insulin granule dynamics and exocytosis downstream of islet cell autoantigen 512

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Hassan Mziaut

2016-08-01

Full Text Available Objective: Insulin release from pancreatic islet β cells should be tightly controlled to avoid hypoglycemia and insulin resistance. The cortical actin cytoskeleton is a gate for regulated exocytosis of insulin secretory granules (SGs by restricting their mobility and access to the plasma membrane. Prior studies suggest that SGs interact with F-actin through their transmembrane cargo islet cell autoantigen 512 (Ica512 (also known as islet antigen 2/Ptprn. Here we investigated how Ica512 modulates SG trafficking and exocytosis. Methods: Transcriptomic changes in Ica512−/− mouse islets were analyzed. Imaging as well as biophysical and biochemical methods were used to validate if and how the Ica512-regulated gene villin modulates insulin secretion in mouse islets and insulinoma cells. Results: The F-actin modifier villin was consistently downregulated in Ica512−/− mouse islets and in Ica512-depleted insulinoma cells. Villin was enriched at the cell cortex of β cells and dispersed villin−/− islet cells were less round and less deformable. Basal mobility of SGs in villin-depleted cells was enhanced. Moreover, in cells depleted either of villin or Ica512 F-actin cages restraining cortical SGs were enlarged, basal secretion was increased while glucose-stimulated insulin release was blunted. The latter changes were reverted by overexpressing villin in Ica512-depleted cells, but not vice versa. Conclusion: Our findings show that villin controls the size of the F-actin cages restricting SGs and, thus, regulates their dynamics and availability for exocytosis. Evidence that villin acts downstream of Ica512 also indicates that SGs directly influence the remodeling properties of the cortical actin cytoskeleton for tight control of insulin secretion. Keywords: F-actin, Granules, Ica512, Insulin, Secretion, Villin