Selective Androgen Receptor Modulators (SARMs) as Function Promoting Therapies

Science.gov (United States)

Bhasin, Shalender; Jasuja, Ravi

2010-01-01

Purpose of review The last decade has witnessed unprecedented discovery effort to develop selective androgen receptor modulators (SARMs) that improve physical function and bone health without adversely affecting the prostate and cardiovascular outcomes. This review describes the historical evolution, the rationale for SARM development, and the mechanisms of testosterone action and SARM selectivity. Recent Findings While steroidal SARMs have been around since the 1940s, a number of nonsteroidal SARMs that do not serve as substrates for CYP19 aromatase or 5α-reductase, act as full agonists in muscle and bone and as partial agonists in prostate are in development. The differing interactions of steroidal and nonsteroidal compounds with AR contribute to their unique pharmacologic actions. Ligand binding induces specific conformational changes in the ligand binding domain, which could modulate surface topology and protein-protein interactions between AR and coregulators, resulting in tissue-specific gene regulation. Preclinical studies have demonstrated the ability of SARMs to increase muscle and bone mass in preclinical rodent models with varying degree of prostate sparing. Phase I trials of SARMs in humans have reported modest increments in fat-free mass. Summary SARMs hold promise as a new class of function promoting anabolic therapies for a number of clinical indications, including functional limitations associated with aging and chronic disease, frailty, cancer cachexia, and osteoporosis. PMID:19357508

Mass spectrometry of selective androgen receptor modulators.

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Thevis, Mario; Schänzer, Wilhelm

2008-07-01

Nonsteroidal selective androgen receptor modulators (SARMs) are an emerging class of drugs for treatment of various diseases including osteoporosis and muscle wasting as well as the correction of age-related functional decline such as muscle strength and power. Several SARMs, which have advanced to preclinical and clinical trials, are composed of diverse chemical structures including arylpropionamide-, bicyclic hydantoin-, quinoline-, and tetrahydroquinoline-derived nuclei. Since January 2008, SARMs have been categorized as anabolic agents and prohibited by the World Anti-Doping Agency (WADA). Suitable detection methods for these low-molecular weight drugs were based on mass spectrometric approaches, which necessitated the elucidation of dissociation pathways in order to characterize and identify the target analytes in doping control samples as well as potential metabolic products and synthetic analogs. Fragmentation patterns of representatives of each category of SARMs after electrospray ionization (ESI) and collision-induced dissociation (CID) as well as electron ionization (EI) are summarized. The complexity and structural heterogeneity of these drugs is a daunting challenge for detection methods. Copyright 2008 John Wiley & Sons, Ltd.

Antiandrogens act as selective androgen receptor modulators at the proteome level in prostate cancer cells.

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Brooke, Greg N; Gamble, Simon C; Hough, Michael A; Begum, Shajna; Dart, D Alwyn; Odontiadis, Michael; Powell, Sue M; Fioretti, Flavia M; Bryan, Rosie A; Waxman, Jonathan; Wait, Robin; Bevan, Charlotte L

2015-05-01

Current therapies for prostate cancer include antiandrogens, inhibitory ligands of the androgen receptor, which repress androgen-stimulated growth. These include the selective androgen receptor modulators cyproterone acetate and hydroxyflutamide and the complete antagonist bicalutamide. Their activity is partly dictated by the presence of androgen receptor mutations, which are commonly detected in patients who relapse while receiving antiandrogens, i.e. in castrate-resistant prostate cancer. To characterize the early proteomic response to these antiandrogens we used the LNCaP prostate cancer cell line, which harbors the androgen receptor mutation most commonly detected in castrate-resistant tumors (T877A), analyzing alterations in the proteome, and comparing these to the effect of these therapeutics upon androgen receptor activity and cell proliferation. The majority are regulated post-transcriptionally, possibly via nongenomic androgen receptor signaling. Differences detected between the exposure groups demonstrate subtle changes in the biological response to each specific ligand, suggesting a spectrum of agonistic and antagonistic effects dependent on the ligand used. Analysis of the crystal structures of the AR in the presence of cyproterone acetate, hydroxyflutamide, and DHT identified important differences in the orientation of key residues located in the AF-2 and BF-3 protein interaction surfaces. This further implies that although there is commonality in the growth responses between androgens and those antiandrogens that stimulate growth in the presence of a mutation, there may also be influential differences in the growth pathways stimulated by the different ligands. This therefore has implications for prostate cancer treatment because tumors may respond differently dependent upon which mutation is present and which ligand is activating growth, also for the design of selective androgen receptor modulators, which aim to elicit differential proteomic

Design, synthesis, and biological characterization of metabolically stable selective androgen receptor modulators.

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Marhefka, Craig A; Gao, Wenqing; Chung, Kiwon; Kim, Juhyun; He, Yali; Yin, Donghua; Bohl, Casey; Dalton, James T; Miller, Duane D

2004-02-12

A series of nonsteroidal ligands were synthesized as second-generation agonists for the androgen receptor (AR). These ligands were designed to eliminate metabolic sites identified in one of our first-generation AR agonists, which was inactive in vivo due to its rapid metabolism to inactive constituents. The binding affinity of these compounds was evaluated using AR isolated from rat ventral prostate. These second-generation compounds bound the AR in a high affinity and stereoselective manner, with K(i) values ranging from about 4 to 130 nM. The ability of these ligands to stimulate AR-mediated transcriptional activation was examined in cells transfected with the human AR and a hormone-dependent luciferase reporter gene. Although some compounds were unable to stimulate AR-mediated transcription, several demonstrated activity similar to that of dihydrotestosterone (DHT, an endogenous steroidal ligand for the AR). We also evaluated the in vivo pharmacologic activity of selected compounds in castrated male rats. Three compounds were identified as selective androgen receptor modulators (SARMs), exhibiting significant anabolic activity while having only moderate to minimal androgenic activity in vivo.

Nonsteroidal selective androgen receptor modulators enhance female sexual motivation.

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Jones, Amanda; Hwang, Dong Jin; Duke, Charles B; He, Yali; Siddam, Anjaiah; Miller, Duane D; Dalton, James T

2010-08-01

Women experience a decline in estrogen and androgen levels after natural or surgically induced menopause, effects that are associated with a loss of sexual desire and bone mineral density. Studies in our laboratories have shown the beneficial effects of selective androgen receptor modulators (SARMs) in the treatment of osteoporosis and muscle wasting in animal models. A series of S-3-(phenoxy)-2-hydroxy-2-methyl-N-(4-cyano-3-trifluoromethyl-phenyl)-propionamide analogs was synthesized to evaluate the effects of B-ring substitutions on in vitro and in vivo pharmacologic activity, especially female sexual motivation. The androgen receptor (AR) relative binding affinities ranged from 0.1 to 26.5% (relative to dihydrotestosterone) and demonstrated a range of agonist activity at 100 nM. In vivo pharmacologic activity was first assessed by using male rats. Structural modifications to the B-ring significantly affected the selectivity of the SARMs, demonstrating that single-atom substitutions can dramatically and unexpectedly influence activity in androgenic (i.e., prostate) and anabolic (i.e., muscle) tissues. (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro,4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide (S-23) displayed full agonist activity in androgenic and anabolic tissues; however, the remaining SARMs were more prostate-sparing, selectively maintaining the size of the levator ani muscle in castrated rats. The partner-preference paradigm was used to evaluate the effects of SARMs on female sexual motivation. With the exception of two four-halo substituted analogs, the SARMs increased sexual motivation in ovariectomized rats, with potency and efficacy comparable with testosterone propionate. These results indicate that the AR is important in regulating female libido given the nonaromatizable nature of SARMs and it could be a superior alternative to steroidal testosterone preparations in the treatment of hypoactive sexual desire disorder.

A selective androgen receptor modulator for hormonal male contraception.

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Chen, Jiyun; Hwang, Dong Jin; Bohl, Casey E; Miller, Duane D; Dalton, James T

2005-02-01

The recent discovery of nonsteroidal selective androgen receptor modulators (SARMs) provides a promising alternative for testosterone replacement therapies, including hormonal male contraception. The identification of an orally bioavailable SARM with the ability to mimic the central and peripheral androgenic and anabolic effects of testosterone would represent an important step toward the "male pill". We characterized the in vitro and in vivo pharmacologic activity of (S)-3-(4-chloro-3-fluorophenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethylphenyl)propionamide (C-6), a novel SARM developed in our laboratories. C-6 was identified as an androgen receptor (AR) agonist with high AR binding affinity (K(i) = 4.9 nM). C-6 showed tissue-selective pharmacologic activity with higher anabolic activity than androgenic activity in male rats. The doses required to maintain the weight of the prostate, seminal vesicles, and levator ani muscle to half the size of the maximum effects (i.e., ED(50)) were 0.78 +/- 0.06, 0.88 +/- 0.1, and 0.17 +/- 0.04 mg/day, respectively. As opposed to other SARMs, gonadotropin levels in C-6-treated groups were significantly lower than control values. C-6 also significantly decreased serum testosterone concentration in intact rats after 2 weeks of treatment. Marked suppression of spermatogenesis was observed after 10 weeks of treatment with C-6 in intact male rats. Pharmacokinetic studies of C-6 in male rats revealed that C-6 was well absorbed after oral administration (bioavailability 76%), with a long (6.3 h) half-life at a dose of 10 mg/kg. These studies show that C-6 mimicked the in vivo pharmacologic and endocrine effects of testosterone while maintaining the oral bioavailability and tissue-selective actions of nonsteroidal SARMs.

Endometrial changes from short-term therapy with CDB-4124, a selective progesterone receptor modulator.

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Ioffe, Olga B; Zaino, Richard J; Mutter, George L

2009-03-01

Selective progesterone receptor modulators are a class of drugs with progesterone antagonist activity that may confer therapeutic benefit for reproductive disorders in premenopausal women. Endometrial structure, which is dynamically controlled by circulating sex hormones, is likely to be perturbed by progesterone receptor modulators through their progesterone antagonist properties. We examined endometrial histology in 58 premenopausal women treated with the progesterone receptor modulator CDB-4124 (also known as Proellex) for endometriosis or uterine leiomyomata in two clinical trials. Endometrial biopsies obtained after 3 or 6 months with doses of 12.5, 25, or 50 mg daily oral CDB-4124 were reviewed independently by three pathologists. Consensus diagnoses using the World Health Organization hyperplasia scoring system, comments on specific histologic features, and clinical annotation were collected and analyzed. The majority of the endometrial biopsies (103 of 174 biopsies) contained histologic changes that are not seen during normal menstrual cycles. The histology of CDB-4124-treated patients was generally inactive or atrophic, and less frequently, proliferative or secretory, superimposed upon which were novel changes including formation of cystically dilated glands, and secretory changes coexisting with mitoses and apoptotic bodies. With increasing treatment dose and duration, the cysts became predominant and their lining inactive or atrophic. Cystic glands in the CDB-4124-treated subjects correlated with increased endometrial thickness by ultrasound. None of the CDB-4124-treated patients developed endometrial carcinoma or hyperplasia while on therapy. CDB-4124 therapy for 3-6 months produces histologic changes that are sufficiently novel that they might easily be misinterpreted by pathologists, particularly as disordered proliferative or hyperplastic endometrium. Knowledge of the constellation of endometrial changes associated with this agent and other

Nootropic α7 nicotinic receptor allosteric modulator derived from GABAA receptor modulators

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Ng, Herman J.; Whittemore, Edward R.; Tran, Minhtam B.; Hogenkamp, Derk J.; Broide, Ron S.; Johnstone, Timothy B.; Zheng, Lijun; Stevens, Karen E.; Gee, Kelvin W.

2007-01-01

Activation of brain α7 nicotinic acetylcholine receptors (α7 nAChRs) has broad therapeutic potential in CNS diseases related to cognitive dysfunction, including Alzheimer's disease and schizophrenia. In contrast to direct agonist activation, positive allosteric modulation of α7 nAChRs would deliver the clinically validated benefits of allosterism to these indications. We have generated a selective α7 nAChR-positive allosteric modulator (PAM) from a library of GABAA receptor PAMs. Compound 6 (N-(4-chlorophenyl)-α-[[(4-chloro-phenyl)amino]methylene]-3-methyl-5-isoxazoleacet-amide) evokes robust positive modulation of agonist-induced currents at α7 nAChRs, while preserving the rapid native characteristics of desensitization, and has little to no efficacy at other ligand-gated ion channels. In rodent models, it corrects sensory-gating deficits and improves working memory, effects consistent with cognitive enhancement. Compound 6 represents a chemotype for allosteric activation of α7 nAChRs, with therapeutic potential in CNS diseases with cognitive dysfunction. PMID:17470817

Design and synthesis of tricyclic tetrahydroquinolines as a new series of nonsteroidal selective androgen receptor modulators (SARMs).

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Nagata, Naoya; Miyakawa, Motonori; Amano, Seiji; Furuya, Kazuyuki; Yamamoto, Noriko; Inoguchi, Kiyoshi

2011-03-15

Some tricyclic tetrahydroquinolines (THQs) were found to have the potential of a new series of nonsteroidal selective androgen receptor modulators (SARMs). Compound 5b was first designed and synthesized under our hypothesis based on a four-point pharmacophoric requirement of the 3-carbonyl, 18-methyl, 17-hydroxyl, and 13-quaternary carbon groups of dihydrotestosterone (DHT). It was revealed that this compound exhibits not only a strong androgen receptor (AR) agonistic activity (EC(50)=9.2 nM) but also the highest selectivity in binding affinity to AR among the steroid hormone receptors. Furthermore, this compound showed a weak virilizing effect with retention of the desired anabolic effect as compared with DHT in vivo. Copyright © 2011 Elsevier Ltd. All rights reserved.

Design, synthesis, and in vivo SAR of a novel series of pyrazolines as potent selective androgen receptor modulators.

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Zhang, Xuqing; Li, Xiaojie; Allan, George F; Sbriscia, Tifanie; Linton, Olivia; Lundeen, Scott G; Sui, Zhihua

2007-08-09

A novel series of pyrazolines 2 have been designed, synthesized, and evaluated by in vivo screening as tissue-selective androgen receptor modulators (SARMs). Structure-activity relationships (SAR) were investigated at the R1 to R6 positions as well as the core pyrazoline ring and the anilide linker. Overall, strong electron-withdrawing groups at the R1 and R2 positions and a small group at the R5 and R6 position are optimal for AR agonist activity. The (S)-isomer of 7c exhibits more potent AR agonist activity than the corresponding (R)-isomer. (S)-7c exhibited an overall partial androgenic effect but full anabolic effect via oral administration in castrated rats. It demonstrated a noticeable antiandrogenic effect on prostate in intact rats with endogenous testosterone. Thus, (S)-7c is a tissue-selective nonsteroidal androgen receptor modulator with agonist activity on muscle and mixed agonist and antagonist activity on prostate.

Effect of B-ring substitution pattern on binding mode of propionamide selective androgen receptor modulators.

Science.gov (United States)

Bohl, Casey E; Wu, Zengru; Chen, Jiyun; Mohler, Michael L; Yang, Jun; Hwang, Dong Jin; Mustafa, Suni; Miller, Duane D; Bell, Charles E; Dalton, James T

2008-10-15

Selective androgen receptor modulators (SARMs) are essentially prostate sparing androgens, which provide therapeutic potential in osteoporosis, male hormone replacement, and muscle wasting. Herein we report crystal structures of the androgen receptor (AR) ligand-binding domain (LBD) complexed to a series of potent synthetic nonsteroidal SARMs with a substituted pendant arene referred to as the B-ring. We found that hydrophilic B-ring para-substituted analogs exhibit an additional region of hydrogen bonding not seen with steroidal compounds and that multiple halogen substitutions affect the B-ring conformation and aromatic interactions with Trp741. This information elucidates interactions important for high AR binding affinity and provides new insight for structure-based drug design.

Steroidal androgens and nonsteroidal, tissue-selective androgen receptor modulator, S-22, regulate androgen receptor function through distinct genomic and nongenomic signaling pathways.

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Narayanan, Ramesh; Coss, Christopher C; Yepuru, Muralimohan; Kearbey, Jeffrey D; Miller, Duane D; Dalton, James T

2008-11-01

Androgen receptor (AR) ligands are important for the development and function of several tissues and organs. However, the poor oral bioavailability, pharmacokinetic properties, and receptor cross-reactivity of testosterone, coupled with side effects, place limits on its clinical use. Selective AR modulators (SARMs) elicit anabolic effects in muscle and bone, sparing reproductive organs like the prostate. However, molecular mechanisms underlying the tissue selectivity remain ambiguous. We performed a variety of in vitro studies to compare and define the molecular mechanisms of an aryl propionamide SARM, S-22, as compared with dihydrotestosterone (DHT). Studies indicated that S-22 increased levator ani muscle weight but decreased the size of prostate in rats. Analysis of the upstream intracellular signaling events indicated that S-22 and DHT mediated their actions through distinct pathways. Modulation of these pathways altered the recruitment of AR and its cofactors to the PSA enhancer in a ligand-dependent fashion. In addition, S-22 induced Xenopus laevis oocyte maturation and rapid phosphorylation of several kinases, through pathways distinct from steroids. These studies reveal novel differences in the molecular mechanisms by which S-22, a nonsteroidal SARM, and DHT mediate their pharmacological effects.

Pharmacological characterization of an imidazolopyrazole as novel selective androgen receptor modulator.

Science.gov (United States)

Zhang, Xuqing; Allan, George F; Tannenbaum, Pamela; Sbriscia, Tifanie; Linton, Olivia; Lai, Muh-Tsann; Haynes-Johnson, Donna; Bhattacharjee, Sheela; Lundeen, Scott G; Sui, Zhihua

2013-03-01

Selective androgen receptor modulators (SARMs) are androgens with tissue-selective activity. SARMs that have anabolic activity on muscle while having minimal stimulatory activity on prostate are classified as SARM agonists. They can be used to prevent the loss of lean body mass that is associated with cancer, immunodeficiency, renal disease and aging. They may also have anabolic activity on bone; thus, unlike estrogens, they may reverse the loss of bone strength associated with aging or hypogonadism. Our in-house effort on SARM program discovers a nonsteroidal androgen receptor ligand with a unique imidazolopyrazole moiety in its structure. In vitro, this compound is a weak androgen receptor binder and a weak androgen agonist. Despite this, in orchidectomized mature rats it is an effective SARM agonist, with an ED(50) on levator ani muscle of 3.3mg/kg and an ED(50) on ventral prostate of >30mg/kg. It has its maximal effect on muscle at the dose of 10mg/kg. In addition, this compound has mixed agonistic and antagonistic activities on prostate, reducing the weight of that tissue in intact rats by 22% at 10mg/kg. The compound does not have significant effect on gonadotropin levels or testosterone levels in both orchidectomized and intact male rats. It does not have notable progestin, estrogen or glucocorticoid agonistic or antagonistic activity in rats. In a female sexual behavior model, it improves the sexual desire of ovariectomized female rats for sexually mature intact males over nonsexually ovariectomized females. Overall, the imidazolopyrazole is a potent prostate-sparing candidate for development as a SARM agonist with an appropriate pharmacological profile for clinical benefit in muscle-wasting conditions and female sexual function disorders. Copyright © 2012 Elsevier Ltd. All rights reserved.

Modeling Tolerance Development for the Effect on Heart Rate of the Selective S1P1 Receptor Modulator Ponesimod.

Science.gov (United States)

Lott, Dominik; Lehr, Thorsten; Dingemanse, Jasper; Krause, Andreas

2017-09-15

Ponesimod is a selective sphingosine-1-phosphate-1 (S1P 1 ) receptor modulator currently under investigation for the treatment of multiple sclerosis. S1P receptor modulators reduce heart rate following treatment initiation. This effect disappears with repeated dosing, enabling development of innovative uptitration regimens to optimize patient safety. There are currently no published pharmacokinetic/pharmacodynamic models describing the heart rate reduction of S1P receptor modulators in humans. The model developed here provides quantification of this effect for ponesimod. A direct-effect I max model with estimated maximum reduction of 45%, tolerance development, and circadian variation best described this effect. The pooled data from nine clinical studies enabled characterization of interindividual variability. The model was used to simulate different treatment regimens to compare the effect of high initial doses vs. gradual uptitration with respect to the occurrence of bradycardia. The results indicate a better safety profile when using gradual uptitration. The model allows studying dosing regimens not clinically tested in silico. © 2017 American Society for Clinical Pharmacology and Therapeutics.

Selective estrogen receptor modulators and risk for coronary heart disease.

Science.gov (United States)

Cano, A; Hermenegildo, C; Oviedo, P; Tarín, J J

2007-04-01

Coronary heart disease (CHD) is the leading cause of death in women in most countries. Atherosclerosis is the main biological process determining CHD. Clinical data support the notion that CHD is sensitive to estrogens, but debate exists concerning the effects of the hormone on atherosclerosis and its complications. Selective estrogen receptor modulators (SERMs) are compounds capable of binding the estrogen receptor to induce a functional profile distinct from estrogens. The possibility that SERMs may shift the estrogenic balance on cardiovascular risk towards a more beneficial profile has generated interest in recent years. There is considerable information on the effects of SERMs on distinct areas that are crucial in atherogenesis. The complexity derived from the diversity of variables affecting their mechanism of action plus the differences between compounds make it difficult to delineate one uniform trend for SERMs. The present picture, nonetheless, is one where SERMs seem less powerful than estrogens in atherosclerosis protection, but more gentle with advanced forms of the disease. The recent publication of the Raloxifene Use for The Heart (RUTH) study has confirmed a neutral effect for raloxifene. Prothrombotic states may favor occlusive thrombi at sites occupied by atheromatous plaques. Platelet activation has received attention as an important determinant of arterial thrombogenesis. Although still sparse, available evidence globally suggests neutral or beneficial effects for SERMs.

The selective estrogen receptor modulators in breast cancer prevention.

Science.gov (United States)

Li, Fangxuan; Dou, Jinli; Wei, Lijuan; Li, Shixia; Liu, Juntian

2016-05-01

Persistently increased blood levels of estrogens are associated with an increased risk of breast cancer. Selective estrogen receptor modulators (SERMs) are a class of compounds that act on the estrogen receptor (ER). Several clinical trials have demonstrated the effectiveness of its prophylactic administration. Incidence of invasive ER-positive breast cancer was reduced by SERMs treatment, especially for those women with high risk of developing breast cancer. In this study, we reviewed the clinical application of SERMs in breast cancer prevention. To date, four prospective randomized clinical trials had been performed to test the efficacy of tamoxifen for this purpose. Concerning on the benefit and cost of tamoxifen, various studies from different countries demonstrated that chemoprevention with tamoxifen seemed to be cost-effective for women with a high risk of invasive breast cancer. Based above, tamoxifen was approved for breast cancer prevention by the US Food and Drug Administration in 1998. Raloxifene was also approved for postmenopausal women in 2007 for breast cancer prevention which reduces the risk of invasive breast cancer with a lower risk of unwanted stimulation of endometrium. Thus, raloxifene is considered to have a better clinical possesses as prophylactic agent. Several other agents, such as arzoxifene and lasofoxifene, are currently being investigated in clinic. The American Society of Clinical Oncology and National Comprehensive Cancer Network had published guidelines on breast cancer chemoprevention by SERMs. However, use of tamoxifen and raloxifene for primary breast cancer prevention was still low. A broader educational effort is needed to alert women and primary care physicians that SERMs are available to reduce breast cancer risk.

N-Aryl-oxazolidin-2-imine Muscle Selective Androgen Receptor Modulators Enhance Potency through Pharmacophore Reorientation

Energy Technology Data Exchange (ETDEWEB)

Nirschl, Alexandra A.; Zou, Yan; Krystek, Jr., Stanley R.; Sutton, James C.; Simpkins, Ligaya M.; Lupisella, John A.; Kuhns, Joyce E.; Seethala, Ramakrishna; Golla, Rajasree; Sleph, Paul G.; Beehler, Blake C.; Grover, Gary J.; Egan, Donald; Fura, Aberra; Vyas, Viral P.; Li, Yi-Xin; Sack, John S.; Kish, Kevin F.; An, Yongmi; Bryson, James A.; Gougoutas, Jack Z.; DiMarco, John; Zahler, Robert; Ostrowski, Jacek; Hamann, Lawrence G.; (BMS)

2010-11-09

A novel selective androgen receptor modulator (SARM) scaffold was discovered as a byproduct obtained during synthesis of our earlier series of imidazolidin-2-ones. The resulting oxazolidin-2-imines are among the most potent SARMs known, with many analogues exhibiting sub-nM in vitro potency in binding and functional assays. Despite the potential for hydrolytic instability at gut pH, compounds of the present class showed good oral bioavailability and were highly active in a standard rodent pharmacological model.

Structure of the ligand-binding domain (LBD) of human androgen receptor in complex with a selective modulator LGD2226

International Nuclear Information System (INIS)

Wang, Feng; Liu, Xiao-qin; Li, He; Liang, Kai-ni; Miner, Jeffrey N.; Hong, Mei; Kallel, E. Adam; Oeveren, Arjan van; Zhi, Lin; Jiang, Tao

2006-01-01

Crystal structure of the ligand-binding domain of androgen receptor in complex with LGD2226. The androgen receptor (AR) is a ligand-inducible steroid hormone receptor that mediates androgen action, determining male sexual phenotypes and promoting spermatogenesis. As the androgens play a dominant role in male sexual development and function, steroidal androgen agonists have been used clinically for some years. However, there is a risk of potential side effects and most steroidal androgens cannot be dosed orally, which limits the use of these substances. 1,2-Dihydro-6-N,N-bis(2,2,2-trifluoroethyl) amino-4-trifluoromethyl-2-quinolinone (LGD2226) is a synthetic nonsteroidal ligand and a novel selective AR modulator. The crystal structure of the complex of LGD2226 with the androgen receptor ligand-binding domain (AR LBD) at 2.1 Å was solved and compared with the structure of the AR LBD–R1881 complex. It is hoped that this will aid in further explaining the selectivity of LGD2226 observed in in vitro and in vivo assays and in developing more selective and effective therapeutic agents

Electrochemical oxidation of selective estrogen receptor modulator raloxifene

International Nuclear Information System (INIS)

Li, Xi-Qian; He, Jian-Bo; Liu, Lu; Cui, Ting

2013-01-01

Highlights: ► Application and analysis of in situ thin-layer spectroelectrochemistry. ► Cyclic voltabsorptometry used for a drug study. ► Highly pH-dependent oxidative metabolism of raloxifene. ► A complex parallel-consecutive mechanism proposed for oxidation of raloxifene. -- Abstract: Raloxifene is a selective estrogen receptor modulator that may produce toxic oxidative species in metabolism. The oxidation mechanism of raloxifene with different pH values was studied by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), in situ UV–vis spectral analysis and cyclic voltabsorptometry based on a long optical-path thin-layer electrochemical cell. Time-derivative cyclic voltabsorptograms were obtained for comparative discussion with the corresponding cyclic voltammograms. Raloxifene was initially oxidized to reactive phenoxyl radicals, followed by a series of transformation steps leading to different final products in different pH media. A parallel-consecutive reaction mechanism was proposed for the pH-dependent formation of 7-hydroxyraloxifene, raloxifene 6,7-o-quinone and two raloxifene dimers, each pathway following a complex electrochemical-chemical mechanism. Both raloxifene diquinone methide and its N-oxides were not detected by in situ UV–vis spectroscopy and XPS analysis. This work provides an electrochemical viewpoint and comparable information for better understanding of the oxidative metabolism and chemical toxicology of raloxifene under physiological conditions in vivo or in vitro

Population pharmacokinetics and pharmacodynamics of ponesimod, a selective S1P1 receptor modulator.

Science.gov (United States)

Krause, Andreas; Brossard, Patrick; D'Ambrosio, Daniele; Dingemanse, Jasper

2014-06-01

Ponesimod (ACT-128800), a reversible, orally active, selective S1P1 receptor modulator, prevents the egress of lymphocytes from the lymph node into the systemic circulation. It is currently in clinical development for the treatment of relapsing multiple sclerosis. Modulation of circulating lymphocytes serves as biomarker of efficacy and safety, such that the quantitative characterization of the pharmacokinetic/pharmacodynamic (PK/PD) relationship guides the clinical development of the compound. The availability of a variety of doses, dosing regimens, and treatment durations permitted estimation of the pharmacokinetics characterized by an absorption lag time followed by a sequential zero/first-order absorption and two compartments with first-order elimination. The PD are modeled as an indirect-effect model with rates of appearance and disappearance of lymphocytes in blood with a circadian rhythm and a drug effect on the rate of appearance. The model suggests a circadian variation of 9% and a maximum inhibition of 86% of total lymphocyte count with high doses at steady state. It was instrumental for the selection of doses for subsequent studies that confirmed the effect plateau in total lymphocyte count at approximately 0.5 × 10(9) counts/L.

Structural Insights into Selective Ligand-Receptor Interactions Leading to Receptor Inactivation Utilizing Selective Melanocortin 3 Receptor Antagonists.

Science.gov (United States)

Cai, Minying; Marelli, Udaya Kiran; Mertz, Blake; Beck, Johannes G; Opperer, Florian; Rechenmacher, Florian; Kessler, Horst; Hruby, Victor J

2017-08-15

Systematic N-methylated derivatives of the melanocortin receptor ligand, SHU9119, lead to multiple binding and functional selectivity toward melanocortin receptors. However, the relationship between N-methylation-induced conformational changes in the peptide backbone and side chains and melanocortin receptor selectivity is still unknown. We conducted comprehensive conformational studies in solution of two selective antagonists of the third isoform of the melanocortin receptor (hMC3R), namely, Ac-Nle-c[Asp-NMe-His 6 -d-Nal(2') 7 -NMe-Arg 8 -Trp 9 -Lys]-NH 2 (15) and Ac-Nle-c[Asp-His 6 -d-Nal(2') 7 -NMe-Arg 8 -NMe-Trp 9 -NMe-Lys]-NH 2 (17). It is known that the pharmacophore (His 6 -DNal 7 -Arg 8 -Trp 9 ) of the SHU-9119 peptides occupies a β II-turn-like region with the turn centered about DNal 7 -Arg 8 . The analogues with hMC3R selectivity showed distinct differences in the spatial arrangement of the Trp 9 side chains. In addition to our NMR studies, we also carried out molecular-level interaction studies of these two peptides at the homology model of hMC3R. Earlier chimeric human melanocortin 3 receptor studies revealed insights regarding the binding and functional sites of hMC3R selectivity. Upon docking of peptides 15 and 17 to the binding pocket of hMC3R, it was revealed that Arg 8 and Trp 9 side chains are involved in a majority of the interactions with the receptor. While Arg 8 forms polar contacts with D154 and D158 of hMC3R, Trp 9 utilizes π-π stacking interactions with F295 and F298, located on the transmembrane domain of hMC3R. It is hypothesized that as the frequency of Trp 9 -hMC3R interactions decrease, antagonistic activity increases. The absence of any interactions of the N-methyl groups with hMC3R suggests that their primary function is to modulate backbone conformations of the ligands.

Toxicological characterisation of two novel selective aryl hydrocarbon receptor modulators in Sprague-Dawley rats

Energy Technology Data Exchange (ETDEWEB)

Mahiout, Selma, E-mail: selma.mahiout@helsinki.fi [Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki (Finland); Lindén, Jere [Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki (Finland); Esteban, Javier; Sánchez-Pérez, Ismael [Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche, Alicante (Spain); Sankari, Satu [Central Laboratory of the Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki (Finland); Pettersson, Lars [Immunahr AB, Lund (Sweden); Håkansson, Helen [Institute of Environmental Medicine (IMM), Karolinska Institutet, Stockholm (Sweden); Pohjanvirta, Raimo [Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki (Finland)

2017-07-01

The aryl hydrocarbon receptor (AHR) mediates the toxicity of dioxins, but also plays important physiological roles. Selective AHR modulators, which elicit some effects imparted by this receptor without causing the marked toxicity of dioxins, are presently under intense scrutiny. Two novel such compounds are IMA-08401 (N-acetyl-N-phenyl-4-acetoxy-5-chloro-1, 2-dihydro-1-methyl-2-oxo-quinoline-3-carboxamide) and IMA-07101 (N-acetyl-N-(4-trifluoromethylphenyl)-4-acetoxy-1, 2-dihydro-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide). They represent, as diacetyl prodrugs, AHR-active metabolites of the drug compounds laquinimod and tasquinimod, respectively, which are intended for the treatment of autoimmune diseases and cancer. Here, we toxicologically assessed the novel compounds in Sprague-Dawley rats, after a single dose (8.75–92.5 mg/kg) and 5-day repeated dosing at the highest doses achievable (IMA-08401: 100 mg/kg/day; and IMA-07101: 75 mg/kg/day). There were no overt clinical signs of toxicity, but body weight gain was marginally retarded, and the treatments induced minimal hepatic extramedullary haematopoiesis. Further, both the absolute and relative weights of the thymus were significantly decreased. Cyp1a1 gene expression was substantially increased in all tissues examined. The hepatic induction profile of other AHR battery genes was distinct from that caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The only marked alterations in serum clinical chemistry variables were a reduction in triglycerides and an increase in 3-hydroxybutyrate. Liver and kidney retinol and retinyl palmitate concentrations were affected largely in the same manner as reported for TCDD. In vitro, the novel compounds activated CYP1A1 effectively in H4IIE cells. Altogether, these novel compounds appear to act as potent activators of the AHR, but lack some major characteristic toxicities of dioxins. They therefore represent promising new selective AHR modulators. - Highlights: • IMA

Selective androgen receptor modulators for the treatment of late onset male hypogonadism.

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Coss, Christopher C; Jones, Amanda; Hancock, Michael L; Steiner, Mitchell S; Dalton, James T

2014-01-01

Several testosterone preparations are used in the treatment of hypogonadism in the ageing male. These therapies differ in their convenience, flexibility, regional availability and expense but share their pharmacokinetic basis of approval and dearth of long-term safety data. The brevity and relatively reduced cost of pharmacokinetic based registration trials provides little commercial incentive to develop improved novel therapies for the treatment of late onset male hypogonadism. Selective androgen receptor modulators (SARMs) have been shown to provide anabolic benefit in the absence of androgenic effects on prostate, hair and skin. Current clinical development for SARMs is focused on acute muscle wasting conditions with defi ned clinical endpoints of physical function and lean body mass. Similar regulatory clarity concerning clinical deficits in men with hypogonadism is required before the beneficial pharmacology and desirable pharmacokinetics of SARMs can be employed in the treatment of late onset male hypogonadism.

Selective androgen receptor modulators for the treatment of late onset male hypogonadism

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Christopher C Coss

2014-04-01

Full Text Available Several testosterone preparations are used in the treatment of hypogonadism in the ageing male. These therapies differ in their convenience, flexibility, regional availability and expense but share their pharmacokinetic basis of approval and dearth of long-term safety data. The brevity and relatively reduced cost of pharmacokinetic based registration trials provides little commercial incentive to develop improved novel therapies for the treatment of late onset male hypogonadism. Selective androgen receptor modulators (SARMs have been shown to provide anabolic benefit in the absence of androgenic effects on prostate, hair and skin. Current clinical development for SARMs is focused on acute muscle wasting conditions with defi ned clinical endpoints of physical function and lean body mass. Similar regulatory clarity concerning clinical deficits in men with hypogonadism is required before the beneficial pharmacology and desirable pharmacokinetics of SARMs can be employed in the treatment of late onset male hypogonadism.

Selective androgen receptor modulators for the treatment of late onset male hypogonadism

Science.gov (United States)

Coss, Christopher C; Jones, Amanda; Hancock, Michael L; Steiner, Mitchell S; Dalton, James T

2014-01-01

Several testosterone preparations are used in the treatment of hypogonadism in the ageing male. These therapies differ in their convenience, flexibility, regional availability and expense but share their pharmacokinetic basis of approval and dearth of long-term safety data. The brevity and relatively reduced cost of pharmacokinetic based registration trials provides little commercial incentive to develop improved novel therapies for the treatment of late onset male hypogonadism. Selective androgen receptor modulators (SARMs) have been shown to provide anabolic benefit in the absence of androgenic effects on prostate, hair and skin. Current clinical development for SARMs is focused on acute muscle wasting conditions with defined clinical endpoints of physical function and lean body mass. Similar regulatory clarity concerning clinical deficits in men with hypogonadism is required before the beneficial pharmacology and desirable pharmacokinetics of SARMs can be employed in the treatment of late onset male hypogonadism. PMID:24407183

The Safety, Pharmacokinetics, and Effects of LGD-4033, a Novel Nonsteroidal Oral, Selective Androgen Receptor Modulator, in Healthy Young Men

Science.gov (United States)

Basaria, Shehzad; Collins, Lauren; Dillon, E. Lichar; Orwoll, Katie; Storer, Thomas W.; Miciek, Renee; Ulloor, Jagadish; Zhang, Anqi; Eder, Richard; Zientek, Heather; Gordon, Gilad; Kazmi, Syed; Sheffield-Moore, Melinda

2013-01-01

Background. Concerns about potential adverse effects of testosterone on prostate have motivated the development of selective androgen receptor modulators that display tissue-selective activation of androgenic signaling. LGD-4033, a novel nonsteroidal, oral selective androgen receptor modulator, binds androgen receptor with high affinity and selectivity. Objectives. To evaluate the safety, tolerability, pharmacokinetics, and effects of ascending doses of LGD-4033 administered daily for 21 days on lean body mass, muscle strength, stair-climbing power, and sex hormones. Methods. In this placebo-controlled study, 76 healthy men (21–50 years) were randomized to placebo or 0.1, 0.3, or 1.0 mg LGD-4033 daily for 21 days. Blood counts, chemistries, lipids, prostate-specific antigen, electrocardiogram, hormones, lean and fat mass, and muscle strength were measured during and for 5 weeks after intervention. Results. LGD-4033 was well tolerated. There were no drug-related serious adverse events. Frequency of adverse events was similar between active and placebo groups. Hemoglobin, prostate-specific antigen, aspartate aminotransferase, alanine aminotransferase, or QT intervals did not change significantly at any dose. LGD-4033 had a long elimination half-life and dose-proportional accumulation upon multiple dosing. LGD-4033 administration was associated with dose-dependent suppression of total testosterone, sex hormone–binding globulin, high density lipoprotein cholesterol, and triglyceride levels. follicle-stimulating hormone and free testosterone showed significant suppression at 1.0-mg dose only. Lean body mass increased dose dependently, but fat mass did not change significantly. Hormone levels and lipids returned to baseline after treatment discontinuation. Conclusions. LGD-4033 was safe, had favorable pharmacokinetic profile, and increased lean body mass even during this short period without change in prostate-specific antigen. Longer randomized trials should

Allosteric modulation of G-protein coupled receptors

DEFF Research Database (Denmark)

Jensen, Anders A.; Spalding, Tracy A

2004-01-01

are believed to activate (agonists) or inhibit (competitive antagonists) receptor signalling by binding the receptor at the same site as the endogenous agonist, the orthosteric site. In contrast, allosteric ligands modulate receptor function by binding to different regions in the receptor, allosteric sites....... In recent years, combinatorial chemistry and high throughput screening have helped identify several allosteric GPCR modulators with novel structures, several of which already have become valuable pharmacological tools and may be candidates for clinical testing in the near future. This mini review outlines...... the current status and perspectives of allosteric modulation of GPCR function with emphasis on the pharmacology of endogenous and synthesised modulators, their receptor interactions and the therapeutic prospects of allosteric ligands compared to orthosteric ligands....

Novel series of potent, nonsteroidal, selective androgen receptor modulators based on 7H-[1,4]oxazino[3,2-g]quinolin-7-ones.

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Higuchi, Robert I; Arienti, Kristen L; López, Francisco J; Mani, Neelakhanda S; Mais, Dale E; Caferro, Thomas R; Long, Yun Oliver; Jones, Todd K; Edwards, James P; Zhi, Lin; Schrader, William T; Negro-Vilar, Andrés; Marschke, Keith B

2007-05-17

Recent interest in orally available androgens has fueled the search for new androgens for use in hormone replacement therapy and as anabolic agents. In pursuit of this, we have discovered a series of novel androgen receptor modulators derived from 7H-[1,4]oxazino[3,2-g]quinolin-7-ones. These compounds were synthesized and evaluated in competitive binding assays and an androgen receptor transcriptional activation assay. A number of compounds from the series demonstrated single-digit nanomolar agonist activity in vitro. In addition, lead compound (R)-16e was orally active in established rodent models that measure androgenic and anabolic properties of these agents. In this assay, (R)-16e demonstrated full efficacy in muscle and only partially stimulated the prostate at 100 mg/kg. These data suggest that these compounds may be utilized as selective androgen receptor modulators or SARMs. This series represents a novel class of compounds for use in androgen replacement therapy.

Adenosine receptors and muscarinic receptors cooperate in acetylcholine release modulation in the neuromuscular synapse.

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Santafe, M M; Priego, M; Obis, T; Garcia, N; Tomàs, M; Lanuza, M A; Tomàs, J

2015-07-01

Adenosine receptors (ARs) are present in the motor terminals at the mouse neuromuscular junction. ARs and the presynaptic muscarinic acetylcholine receptors (mAChRs) share the functional control of the neuromuscular junction. We analysed their mutual interaction in transmitter release modulation. In electrophysiological experiments with unaltered synaptic transmission (muscles paralysed by blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB), we found that: (i) a collaborative action between different AR subtypes reduced synaptic depression at a moderate activity level (40 Hz); (ii) at high activity levels (100 Hz), endogenous adenosine production in the synaptic cleft was sufficient to reduce depression through A1 -type receptors (A1 Rs) and A2 A-type receptors (A2 A Rs); (iii) when the non-metabolizable 2-chloroadenosine (CADO) agonist was used, both the quantal content and depression were reduced; (iv) the protective effect of CADO on depression was mediated by A1 Rs, whereas A2 A Rs seemed to modulate A1 Rs; (v) ARs and mAChRs absolutely depended upon each other for the modulation of evoked and spontaneous acetylcholine release in basal conditions and in experimental conditions with CADO stimulation; (vi) the purinergic and muscarinic mechanisms cooperated in the control of depression by sharing a common pathway although the purinergic control was more powerful than the muscarinic control; and (vii) the imbalance of the ARs created by using subtype-selective and non-selective inhibitory and stimulatory agents uncoupled protein kinase C from evoked transmitter release. In summary, ARs (A1 Rs, A2 A Rs) and mAChRs (M1 , M2 ) cooperated in the control of activity-dependent synaptic depression and may share a common protein kinase C pathway. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Synthesis of Triphenylethylene Bisphenols as Aromatase Inhibitors That Also Modulate Estrogen Receptors.

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Lv, Wei; Liu, Jinzhong; Skaar, Todd C; O'Neill, Elizaveta; Yu, Ge; Flockhart, David A; Cushman, Mark

2016-01-14

A series of triphenylethylene bisphenol analogues of the selective estrogen receptor modulator (SERM) tamoxifen were synthesized and evaluated for their abilities to inhibit aromatase, bind to estrogen receptor α (ER-α) and estrogen receptor β (ER-β), and antagonize the activity of β-estradiol in MCF-7 human breast cancer cells. The long-range goal has been to create dual aromatase inhibitor (AI)/selective estrogen receptor modulators (SERMs). The hypothesis is that in normal tissue the estrogenic SERM activity of a dual AI/SERM could attenuate the undesired effects stemming from global estrogen depletion caused by the AI activity of a dual AI/SERM, while in breast cancer tissue the antiestrogenic SERM activity of a dual AI/SERM could act synergistically with AI activity to enhance the antiproliferative effect. The potent aromatase inhibitory activities and high ER-α and ER-β binding affinities of several of the resulting analogues, together with the facts that they antagonize β-estradiol in a functional assay in MCF-7 human breast cancer cells and they have no E/Z isomers, support their further development in order to obtain dual AI/SERM agents for breast cancer treatment.

Implications of astrocytes in mediating the protective effects of Selective Estrogen Receptor Modulators upon brain damage

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George E. Barreto

2015-04-01

Full Text Available Selective Estrogen Receptor Modulators (SERMs are steroidal or non-steroidal compounds that are already used in clinical practice for the treatment of breast cancer, osteoporosis and menopausal symptoms. While SERMs actions in the breast, bone, and uterus have been well characterized, their actions in the brain are less well understood. Previous works have demonstrated the beneficial effects of SERMs in different chronic neurodegenerative diseases like Alzheimer, Parkinson’s disease and Multiple sclerosis, as well as acute degeneration as stroke and traumatic brain injury. Moreover, these compounds exhibit similar protective actions as those of estradiol in the Central Nervous System, overt any secondary effect. For these reasons, in the past few years, there has been a growing interest in the neuroprotective effects exerted directly or indirectly by SERMs in the SNC. In this context, astrocytes play an important role in the maintenance of brain metabolism, and antioxidant support to neurons, thus indicating that better protection of astrocytes are an important asset targeting neuronal protection. Moreover, various clinical and experimental studies have reported that astrocytes are essential for the neuroprotective effects of SERMs during neuronal injuries, as these cells express different estrogen receptors in cell membrane, demonstrating that part of SERMs effects upon injury may be mediated by astrocytes. The present work highlights the current evidence on the protective mechanisms of SERMs, such as tamoxifen and raloxifene, in the SNC, and their modulation of astrocytic properties as promising therapeutic targets during brain damage.

Selective thyroid hormone receptor modulators

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Girish Raparti

2013-01-01

Full Text Available Thyroid hormone (TH is known to have many beneficial effects on vital organs, but its extrapolation to be used therapeutically has been restricted by the fact that it does have concurrent adverse effects. Recent finding of various thyroid hormone receptors (TR isoforms and their differential pattern of tissue distribution has regained interest in possible use of TH analogues in therapeutics. These findings were followed by search of compounds with isoform-specific or tissue-specific action on TR. Studying the structure-activity relationship of TR led to the development of compounds like GC1 and KB141, which preferentially act on the β1 isoform of TR. More recently, eprotirome was developed and has been studied in humans. It has shown to be effective in dyslipidemia by the lipid-lowering action of TH in the liver and also in obesity. Another compound, 3,5-diiodothyropropionic acid (DITPA, binds to both α- and β-type TRs with relatively low affinity and has been shown to be effective in heart failure (HF. In postinfarction models of HF and in a pilot clinical study, DITPA increased cardiac performance without affecting the heart rate. TR antagonists like NH3 can be used in thyrotoxicosis and cardiac arrhythmias. However, further larger clinical trials on some of these promising compounds and development of newer compounds with increased selectivity is required to achieve higher precision of action and avoid adverse effects seen with TH.

Selective modulation of Wnt ligands and their receptors in adipose tissue by chronic hyperadiponectinemia.

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Nobuhiko Wada

Full Text Available BACKGROUND: Adiponectin-transgenic mice had many small adipocytes in both subcutaneous and visceral adipose tissues, and showed higher sensitivity to insulin, longer life span, and reduced chronic inflammation. We hypothesized that adiponectin regulates Wnt signaling in adipocytes and thereby modulates adipocyte proliferation and chronic inflammation in adipose tissue. MATERIALS AND METHODS: We examined the expression of all Wnt ligands and their receptors and the activity of Wnt signaling pathways in visceral adipose tissue from wild-type mice and two lines of adiponectin-transgenic mice. The effects of adiponectin were also investigated in cultured 3T3-L1 cells. RESULTS: The Wnt5b, Wnt6, Frizzled 6 (Fzd6, and Fzd9 genes were up-regulated in both lines of transgenic mice, whereas Wnt1, Wnt2, Wnt5a, Wnt9b, Wnt10b, Wnt11, Fzd1, Fzd2, Fzd4, Fzd7, and the Fzd coreceptor low-density-lipoprotein receptor-related protein 6 (Lrp6 were reduced. There was no difference in total β-catenin levels in whole-cell extracts, non-phospho-β-catenin levels in nuclear extracts, or mRNA levels of β-catenin target genes, indicating that hyperadiponectinemia did not affect canonical Wnt signaling. In contrast, phosphorylated calcium/calmodulin-dependent kinase II (p-CaMKII and phosphorylated Jun N-terminal kinase (p-JNK were markedly reduced in adipose tissue from the transgenic mice. The adipose tissue of the transgenic mice consisted of many small cells and had increased expression of adiponectin, whereas cyclooxygenase-2 expression was reduced. Wnt5b expression was elevated in preadipocytes of the transgenic mice and decreased in diet-induced obese mice, suggesting a role in adipocyte differentiation. Some Wnt genes, Fzd genes, and p-CaMKII protein were down-regulated in 3T3-L1 cells cultured with a high concentration of adiponectin. CONCLUSION: Chronic hyperadiponectinemia selectively modulated the expression of Wnt ligands, Fzd receptors and LRP coreceptors

Agonistic activity of tamoxifen, a selective estrogen-receptor modulator (SERM), on arthritic ovariectomized mice

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Silva, L.A.S.; Felix, F.B.; Araujo, J.M.D.; Souza, E.V.; Camargo, E.A.; Grespan, R.

2017-01-01

Arthritis is positively associated with the decline of sex hormones, especially estrogen. Tamoxifen (TMX) is a selective estrogen receptor modulator, possessing agonist or antagonistic activity in different tissues. Thus, the objective of this study was to investigate the effect of TMX on the zymosan-induced arthritis model. Female Swiss normal and ovariectomized (OVX) mice were divided into groups and treated for five days with TMX (0.3, 0.9 or 2.7 mg/kg) or 17-β-estradiol (E2, 50 µg/kg). On the fifth day, arthritis was induced and 4 h later, leukocyte migration into joint cavities was evaluated. The neutrophil migration in OVX animals, but not in normal mice, treated with TMX (all tested doses) was significantly decreased compared with mice that received the vehicle (P≤0.05). Similarly, this effect was also demonstrated in the E2-treated group. Therefore, the present study demonstrates that TMX presented agonist effects in inhibiting neutrophil migration and preventing arthritis progression in OVX mice. PMID:29160416

A selective androgen receptor modulator with minimal prostate hypertrophic activity restores lean body mass in aged orchidectomized male rats.

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Allan, George; Sbriscia, Tifanie; Linton, Olivia; Lai, Muh-Tsann; Haynes-Johnson, Donna; Bhattacharjee, Sheela; Ng, Raymond; Sui, Zhihua; Lundeen, Scott

2008-06-01

Androgens are required for the maintenance of normal sexual activity in adulthood and for enhancing muscle growth and lean body mass in adolescents and adults. Androgen receptor (AR) ligands with tissue selectivity (selective androgen receptor modulators, or SARMs) have potential for treating muscle wasting, hypogonadism of aging, osteoporosis, female sexual dysfunction, and other indications. JNJ-37654032 is a nonsteroidal AR ligand with mixed agonist and antagonist activity in androgen-responsive cell-based assays. It is an orally active SARM with muscle selectivity in orchidectomized rat models. It stimulated growth of the levator ani muscle with ED(50) 0.8 mg/kg, stimulating maximal growth at a dose of 3mg/kg. In contrast, it stimulated ventral prostate growth to 21% of its full size at 3mg/kg. At the same time, JNJ-37654032 reduced prostate weight in intact rats by 47% at 3mg/kg, while having no inhibitory effect on muscle. Using magnetic resonance imaging to monitor body composition, JNJ-37654032 restored about 20% of the lean body mass lost following orchidectomy in aged rats. JNJ-37654032 reduced follicle-stimulating hormone levels in orchidectomized rats and reduced testis size in intact rats. JNJ-37654032 is a potent prostate-sparing SARM with the potential for clinical benefit in muscle-wasting diseases.

PAM-1616, a selective peroxisome proliferator-activated receptor γ modulator with preserved anti-diabetic efficacy and reduced adverse effects.

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Kim, Mi-Kyung; Chae, Yu Na; Choi, Song-hyen; Moon, Ho Sang; Son, Moon-Ho; Bae, Myung-Ho; Choi, Hyun-ho; Hur, Youn; Kim, Eunkyung; Park, Yoo Hoi; Park, Chan Sun; Kim, Jae Gyu; Lim, Joong In; Shin, Chang Yell

2011-01-15

Peroxisome proliferator-activated receptor (PPAR) γ is known to be a key regulator of insulin resistance. PAM-1616 is a novel, non-thiazolidinedione small molecule compound synthesized in Dong-A Research Center. In this study, we characterized the pharmacological and safety profiles of PAM-1616 as a selective PPARγ modulator. PAM-1616 selectively binds to human PPARγ (IC(50), 24.1±5.6 nM) and is a partial agonist for human PPARγ with an EC(50) of 83.6±43.7 nM and a maximal response of 24.9±7.1% relative to the full agonist, rosiglitazone. PAM-1616 was selective for human PPARγ than for human PPARα (EC(50), 2658±828 nM) without activating human PPARδ, which makes it a selective modulator of PPARγ. Treatment of high fat diet-induced obese C57BL/6J mice with PAM-1616 for 21 days improved HOMA-IR. Furthermore, PAM-1616 significantly improved hyperglycemia in db/db mice with little side effect when orally administered at a dose of 1 mg/kg/day for 28 days. Intriguingly, PAM-1616 was seen to increase the gene expression of inducible glucose transporter (GLUT4), while it partially induced that of a fatty acid carrier, aP2 in 3T3-L1 adipocytes, and it also showed partial recruitment of an adipogenic cofactor, TRAP220 as compared to rosiglitazone. PAM-1616 did not cause a significant increase in plasma volume of ICR mice when orally administered at a dose of 10 mg/kg/day for 9 days. PAM-1616 increased the expression of fluid retention-inducing genes such as serum/glucocorticoid-regulated kinase (SGK)-1 to a lesser extent as compared to rosiglitazone in human renal epithelial cells. These results suggest that PAM-1616 acts as a selective modulator of PPARγ with excellent antihyperglycemic property. The differential modulation of target gene by PAM-1616 might contribute to the improved side effect profiles. Copyright © 2010 Elsevier B.V. All rights reserved.

Selective and interactive effects of D2 receptor antagonism and positive allosteric mGluR4 modulation on waiting impulsivity.

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Isherwood, Sarah N; Robbins, Trevor W; Nicholson, Janet R; Dalley, Jeffrey W; Pekcec, Anton

2017-09-01

Metabotropic glutamate receptor 4 (mGluR4) and dopamine D 2 receptors are specifically expressed within the indirect pathway neurons of the striato-pallidal-subthalamic pathway. This unique expression profile suggests that mGluR4 and D 2 receptors may play a cooperative role in the regulation and inhibitory control of behaviour. We investigated this possibility by testing the effects of a functionally-characterised positive allosteric mGluR4 modulator, 4-((E)-styryl)-pyrimidin-2-ylamine (Cpd11), both alone and in combination with the D 2 receptor antagonist eticlopride, on two distinct forms of impulsivity. Rats were trained on the five-choice serial reaction time task (5-CSRTT) of sustained visual attention and segregated according to low, mid, and high levels of motor impulsivity (LI, MI and HI, respectively), with unscreened rats used as an additional control group. A separate group of rats was trained on a delay discounting task (DDT) to assess choice impulsivity. Systemic administration of Cpd11 dose-dependently increased motor impulsivity and impaired attentional accuracy on the 5-CSRTT in all groups tested. Eticlopride selectively attenuated the increase in impulsivity induced by Cpd11, but not the accompanying attentional impairment, at doses that had no significant effect on behavioural performance when administered alone. Cpd11 also decreased choice impulsivity on the DDT (i.e. increased preference for the large, delayed reward) and decreased locomotor activity. These findings demonstrate that mGluR4s, in conjunction with D 2 receptors, affect motor- and choice-based measures of impulsivity, and therefore may be novel targets to modulate impulsive behaviour associated with a number of neuropsychiatric syndromes. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Desensitization by progressive up-titration prevents first-dose effects on the heart: guinea pig study with ponesimod, a selective S1P1 receptor modulator.

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Markus Rey

Full Text Available Ponesimod, a selective S1P1 receptor modulator, reduces the blood lymphocyte count in all tested species by preventing egress of T and B cells from thymus and peripheral lymphoid organs. In addition, ponesimod transiently affects heart rate and atrioventricular (AV conduction in humans, effects not observed in mice, rats, and dogs with selective S1P1 receptor modulators, suggesting that the regulation of heart rate and rhythm is species dependent. In the present study, we used conscious guinea pigs implanted with a telemetry device to investigate the effects of single and multiple oral doses of ponesimod on ECG variables, heart rate, and blood pressure. Oral administration of ponesimod did not affect the sinus rate (P rate but dose-dependently induced AV block type I to III. A single oral dose of 0.1 mg/kg had no effect on ECG variables, while a dose of 3 mg/kg induced AV block type III in all treated guinea pigs. Repeated oral dosing of 1 or 3 mg/kg ponesimod resulted in rapid desensitization, so that the second dose had no or a clearly reduced effect on ECG variables as compared with the first dose. Resensitization of the S1P1 receptor in the heart was concentration dependent. After desensitization had been induced by the first dose of ponesimod, the cardiac system remained desensitized as long as the plasma concentration was ≥75 ng/ml. By using a progressive up-titration regimen, the first-dose effect of ponesimod on heart rate and AV conduction was significantly reduced due to desensitization of the S1P1 receptor. In summary, conscious guinea pigs implanted with a telemetry device represent a useful model to study first-dose effects of S1P1 receptor modulators on heart rate and rhythm. This knowledge was translated to a dosing regimen of ponesimod to be tested in humans to avoid or significantly reduce the first-dose effects.

Modulating Estrogen Receptor-related Receptor-α Activity Inhibits Cell Proliferation*

OpenAIRE

Bianco, Stéphanie; Lanvin, Olivia; Tribollet, Violaine; Macari, Claire; North, Sophie; Vanacker, Jean-Marc

2009-01-01

High expression of the estrogen receptor-related receptor (ERR)-α in human tumors is correlated to a poor prognosis, suggesting an involvement of the receptor in cell proliferation. In this study, we show that a synthetic compound (XCT790) that modulates the activity of ERRα reduces the proliferation of various cell lines and blocks the G1/S transition of the cell cycle in an ERR...

Pharmacological benefits of selective modulation of cannabinoid receptor type 2 (CB2) in experimental Alzheimer's disease.

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Jayant, Shalini; Sharma, Brij Mohan; Bansal, Rani; Sharma, Bhupesh

2016-01-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that pervasively affects the population across the world. Currently, there is no effective treatment available for this and existing drugs merely slow the progression of cognitive function decline. Thus, massive effort is required to find an intended therapeutic target to overcome this condition. The present study has been framed to investigate the ameliorative role of selective modulator of cannabinoid receptor type 2 (CB2), 1-phenylisatin in experimental AD condition. We have induced experimental AD in mice by using two induction models viz., intracerebroventricular (i.c.v.) administration of streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose. Morris water maze (MWM) and attentional set shifting test (ASST) were used to assess learning and memory. Hematoxylin-eosin and Congo red staining were used to examine the structural variation in brain. Brain oxidative stress (thiobarbituric acid reactive substance and glutathione), nitric oxide levels (nitrites/nitrates), acetyl cholinesterase activity, myeloperoxidase and calcium levels were also estimated. i.c.v. STZ as well as AlCl3+d-galactose have impaired spatial and reversal learning with executive functioning, increased brain oxidative and nitrosative stress, cholinergic activity, inflammation and calcium levels. Furthermore, these agents have also enhanced the burden of Aβ plaque in the brain. Treatment with 1-phenylisatin and donepezil attenuated i.c.v. STZ as well as AlCl3+d-galactose induced impairment of learning-memory, brain biochemistry and brain damage. Hence, this study concludes that CB2 receptor modulation can be a potential therapeutic target for the management of AD. Copyright © 2015 Elsevier Inc. All rights reserved.

Selective androgen receptor modulators for the prevention and treatment of muscle wasting associated with cancer.

Science.gov (United States)

Dalton, James T; Taylor, Ryan P; Mohler, Michael L; Steiner, Mitchell S

2013-12-01

This review highlights selective androgen receptor modulators (SARMs) as emerging agents in late-stage clinical development for the prevention and treatment of muscle wasting associated with cancer. Muscle wasting, including a loss of skeletal muscle, is a cancer-related symptom that begins early in the progression of cancer and affects a patient's quality of life, ability to tolerate chemotherapy, and survival. SARMs increase muscle mass and improve physical function in healthy and diseased individuals, and potentially may provide a new therapy for muscle wasting and cancer cachexia. SARMs modulate the same anabolic pathways targeted with classical steroidal androgens, but within the dose range in which expected effects on muscle mass and function are seen androgenic side-effects on prostate, skin, and hair have not been observed. Unlike testosterone, SARMs are orally active, nonaromatizable, nonvirilizing, and tissue-selective anabolic agents. Recent clinical efficacy data for LGD-4033, MK-0773, MK-3984, and enobosarm (GTx-024, ostarine, and S-22) are reviewed. Enobosarm, a nonsteroidal SARM, is the most well characterized clinically, and has consistently demonstrated increases in lean body mass and better physical function across several populations along with a lower hazard ratio for survival in cancer patients. Completed in May 2013, results for the Phase III clinical trials entitled Prevention and treatment Of muscle Wasting in patiEnts with Cancer1 (POWER1) and POWER2 evaluating enobosarm for the prevention and treatment of muscle wasting in patients with nonsmall cell lung cancer will be available soon, and will potentially establish a SARM, enobosarm, as the first drug for the prevention and treatment of muscle wasting in cancer patients.

Muscarinic receptor M₄ positive allosteric modulators attenuate central effects of cocaine

DEFF Research Database (Denmark)

Dall, Camilla; Weikop, Pia; Dencker, Ditte

2017-01-01

BACKGROUND: Cocaine addiction is a chronic brain disease affecting neurotransmission. Muscarinic cholinergic receptors modulate dopaminergic signaling in the reward system, and muscarinic receptor stimulation can block direct reinforcing effects of cocaine. Here, we tested the hypothesis...... that specific muscarinic M4receptor stimulation can attenuate the discriminative stimulus effects and conditioned rewarding effects of cocaine, measures believed to predict the ability of cocaine and cocaine-associated cues to elicit relapse to drug taking. METHODS: We tested the M4-selective positive...

TAAR1 Modulates Cortical Glutamate NMDA Receptor Function

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Espinoza, Stefano; Lignani, Gabriele; Caffino, Lucia; Maggi, Silvia; Sukhanov, Ilya; Leo, Damiana; Mus, Liudmila; Emanuele, Marco; Ronzitti, Giuseppe; Harmeier, Anja; Medrihan, Lucian; Sotnikova, Tatyana D; Chieregatti, Evelina; Hoener, Marius C; Benfenati, Fabio; Tucci, Valter; Fumagalli, Fabio; Gainetdinov, Raul R

2015-01-01

Trace Amine-Associated Receptor 1 (TAAR1) is a G protein-coupled receptor expressed in the mammalian brain and known to influence subcortical monoaminergic transmission. Monoamines, such as dopamine, also play an important role within the prefrontal cortex (PFC) circuitry, which is critically involved in high-o5rder cognitive processes. TAAR1-selective ligands have shown potential antipsychotic, antidepressant, and pro-cognitive effects in experimental animal models; however, it remains unclear whether TAAR1 can affect PFC-related processes and functions. In this study, we document a distinct pattern of expression of TAAR1 in the PFC, as well as altered subunit composition and deficient functionality of the glutamate N-methyl-D-aspartate (NMDA) receptors in the pyramidal neurons of layer V of PFC in mice lacking TAAR1. The dysregulated cortical glutamate transmission in TAAR1-KO mice was associated with aberrant behaviors in several tests, indicating a perseverative and impulsive phenotype of mutants. Conversely, pharmacological activation of TAAR1 with selective agonists reduced premature impulsive responses observed in the fixed-interval conditioning schedule in normal mice. Our study indicates that TAAR1 plays an important role in the modulation of NMDA receptor-mediated glutamate transmission in the PFC and related functions. Furthermore, these data suggest that the development of TAAR1-based drugs could provide a novel therapeutic approach for the treatment of disorders related to aberrant cortical functions. PMID:25749299

Ivy and neurogliaform interneurons are a major target of μ opioid receptor modulation

OpenAIRE

Krook-Magnuson, Esther; Luu, Lillian; Lee, Sang-Hun; Varga, Csaba; Soltesz, Ivan

2011-01-01

Mu opioid receptors (μORs) are selectively expressed on interneurons in area CA1 of the hippocampus. Fast-spiking, parvalbumin expressing, basket cells express μORs, but circumstantial evidence suggests that another major, unidentified, GABAergic cell class must also be modulated by μORs. Here we report that the abundant, dendritically targeting, neurogliaform family of cells (Ivy and neurogliaform cells) is a previously unrecognized target of direct modulation by μORs. Ivy and neurogliaform ...

Evidence for a role of NTS2 receptors in the modulation of tonic pain sensitivity

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Martinez Jean

2009-07-01

Full Text Available Abstract Background Central neurotensin (NT administration results in a naloxone-insensitive antinociceptive response in animal models of acute and persistent pain. Both NTS1 and NTS2 receptors were shown to be required for different aspects of NT-induced analgesia. We recently demonstrated that NTS2 receptors were extensively associated with ascending nociceptive pathways, both at the level of the dorsal root ganglia and of the spinal dorsal horn. Then, we found that spinally administered NTS2-selective agonists induced dose-dependent antinociceptive responses in the acute tail-flick test. In the present study, we therefore investigated whether activation of spinal NTS2 receptors suppressed the persistent inflammatory pain symptoms observed after intraplantar injection of formalin. Results We first demonstrated that spinally administered NT and NT69L agonists, which bind to both NTS1 and NTS2 receptors, significantly reduced pain-evoked responses during the inflammatory phase of the formalin test. Accordingly, pretreatment with the NTS2-selective analogs JMV-431 and levocabastine was effective in inhibiting the aversive behaviors induced by formalin. With resolution at the single-cell level, we also found that activation of spinal NTS2 receptors reduced formalin-induced c-fos expression in dorsal horn neurons. However, our results also suggest that NTS2-selective agonists and NTS1/NTS2 mixed compounds differently modulated the early (21–39 min and late (40–60 min tonic phase 2 and recruited endogenous pain inhibitory mechanisms integrated at different levels of the central nervous system. Indeed, while non-selective drugs suppressed pain-related behaviors activity in both part of phase 2, intrathecal injection of NTS2-selective agonists was only efficient in reducing pain during the late phase 2. Furthermore, assessment of the stereotypic pain behaviors of lifting, shaking, licking and biting to formalin also revealed that unlike non

Tissue Selective Androgen Receptor Modulators (SARMs) Increase Pelvic Floor Muscle Mass in Ovariectomized Mice.

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Ponnusamy, Suriyan; Sullivan, Ryan D; Thiyagarajan, Thirumagal; Tillmann, Heather; Getzenberg, Robert H; Narayanan, Ramesh

2017-03-01

Stress urinary incontinence (SUI), a prevalent condition, is represented by an involuntary leakage of urine that results, at least in part, from weakened or damaged pelvic floor muscles and is triggered by physical stress. Current treatment options are limited with no oral therapies available. The pelvic floor is rich in androgen receptor and molecules with anabolic activity including selective androgen receptor modulators (SARMs) may serve as therapeutic options for individuals with SUI. In this study, two SARMs (GTx-024 and GTx-027) were evaluated in a post-menopausal animal model in order to determine their effect on pelvic floor muscles. Female C57BL/6 mice were ovariectomized and their pelvic muscles allowed to regress. The animals were then treated with vehicle or doses of GTx-024 or GTx-027. Animal total body weight, lean body mass, and pelvic floor muscle weights were measured along with the expression of genes associated with muscle catabolism. Treatment with the SARMs resulted in a restoration of the pelvic muscles to the sham-operated weight. Coordinately, the induction of genes associated with muscle catabolism was inhibited. Although a trend was observed towards an increase in total lean body mass in the SARM-treated groups, no significant differences were detected. Treatment of an ovariectomized mouse model with SARMs resulted in an increase in pelvic floor muscles, which may translate to an improvement of symptoms associated with SUI and serves as the basis for evaluating their clinical use. J. Cell. Biochem. 118: 640-646, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Probe-Dependent Negative Allosteric Modulators of the Long-Chain Free Fatty Acid Receptor FFA4

DEFF Research Database (Denmark)

Watterson, Kenneth R; Hansen, Steffen V F; Hudson, Brian D

2017-01-01

High-affinity and selective antagonists that are able to block the actions of both endogenous and synthetic agonists of G protein-coupled receptors are integral to analysis of receptor function and to support suggestions of therapeutic potential. Although there is great interest in the potential...... of endogenous and synthetic agonists, clear agonist probe dependence in the nature of allosteric modulation was apparent. Although AH-7614 did not antagonize the second long-chain free fatty acid receptor, free fatty acid receptor 1, the simple chemical structure of AH-7614 containing features found in many...

Melatonin modulates rat myotube-acetylcholine receptors by inhibiting calmodulin.

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de Almeida-Paula, Lidiana Duarte; Costa-Lotufo, Leticia V; Silva Ferreira, Zulma; Monteiro, Amanda Elisa G; Isoldi, Mauro Cesar; Godinho, Rosely O; Markus, Regina P

2005-11-21

Melatonin, the pineal gland hormone, modulates alpha-bungarotoxin sensitive nicotinic acetylcholine receptors in sympathetic nerve terminals, cerebellum and chick retina imposing a diurnal variation in functional responses [Markus, R.P., Zago, W.M., Carneiro, R.C., 1996. Melatonin modulation of presynaptic nicotinic acetylcholine receptors in the rat vas deferens. J. Pharmacol. Exp. Ther. 279, 18-22; Markus, R.P., Santos, J.M., Zago, W., Reno, L.A., 2003. Melatonin nocturnal surge modulates nicotinic receptors and nicotine-induced [3HI] glutamate release in rat cerebellum slices. J. Pharmacol. Exp. Ther. 305, 525-530; Sampaio, L.F.S., Hamassaki-Britto, D.E., Markus, R.P., 2005. Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells. Braz. J. Med. Biol. Res. 38, 603-613]. Here we show that in rat myotubes forskolin and melatonin reduced the number of nicotinic acetylcholine receptors expressed in plasma membrane. In addition, these cells expressed melatonin MT1 receptors, which are known to be coupled to G(i)-protein. However, the pharmacological profile of melatonin analogs regarding the reduction in cyclic AMP accumulation and number of nicotinic acetylcholine receptors did not point to a mechanism mediated by activation of G(i)-protein coupled receptors. On the other hand, calmidazolium, a classical inhibitor of calmodulin, reduced in a similar manner both effects. Considering that one isoform of adenylyl cyclase present in rat myotubes is regulated by Ca2+/calmodulin, we propose that melatonin modulates the number of nicotinic acetylcholine receptors via reduction in cyclic AMP accumulation.

Stargazin Modulation of AMPA Receptors

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Sana A. Shaikh

2016-10-01

Full Text Available Fast excitatory synaptic signaling in the mammalian brain is mediated by AMPA-type ionotropic glutamate receptors. In neurons, AMPA receptors co-assemble with auxiliary proteins, such as stargazin, which can markedly alter receptor trafficking and gating. Here, we used luminescence resonance energy transfer measurements to map distances between the full-length, functional AMPA receptor and stargazin expressed in HEK293 cells and to determine the ensemble structural changes in the receptor due to stargazin. In addition, we used single-molecule fluorescence resonance energy transfer to study the structural and conformational distribution of the receptor and how this distribution is affected by stargazin. Our nanopositioning data place stargazin below the AMPA receptor ligand-binding domain, where it is well poised to act as a scaffold to facilitate the long-range conformational selection observations seen in single-molecule experiments. These data support a model of stargazin acting to stabilize or select conformational states that favor activation.

Selective Estrogen Receptor Modulators regulate reactive microglia after penetrating brain injury

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George E. Barreto

2014-06-01

Full Text Available Following brain injury, microglia assume a reactive-like state and secrete pro-inflammatory molecules that can potentiate damage. A therapeutic strategy that may limit microgliosis is of potential interest. In this context, selective estrogen receptor modulators, such as raloxifene and tamoxifen, are known to reduce microglia activation induced by neuroinflammatory stimuli in young animals. In the present study, we have assessed whether raloxifene and tamoxifen are able to affect microglia activation after brain injury in young and aged animals in time points relevant to clinics, which is hours after brain trauma. Volume fraction of MHC-II+ microglia was estimated according to the point-counting method of Weibel within a distance of 350 μm from the lateral border of the wound, and cellular morphology was measured by fractal analysis. Two groups of animals were studied: 1 young rats, ovariectomized at 2 months of age; and 2 aged rats, ovariectomized at 18 months of age. Fifteen days after ovariectomy animals received a stab wound brain injury and the treatment with estrogenic compounds. Our findings indicate that raloxifene and tamoxifen reduced microglia activation in both young and aged animals. Although the volume fraction of reactive microglia was found lower in aged animals, this was accompanied by important changes in cell morphology, where aged microglia assume a bushier and hyperplasic aspect when compared to young microglia. These data suggest that early regulation of microglia activation provides a mechanism by which SERMs may exert a neuroprotective effect in the setting of a brain trauma.

Nucleus Accumbens Acetylcholine Receptors Modulate Dopamine and Motivation.

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Collins, Anne L; Aitken, Tara J; Greenfield, Venuz Y; Ostlund, Sean B; Wassum, Kate M

2016-11-01

Environmental reward-predictive cues can motivate reward-seeking behaviors. Although this influence is normally adaptive, it can become maladaptive in disordered states, such as addiction. Dopamine release in the nucleus accumbens core (NAc) is known to mediate the motivational impact of reward-predictive cues, but little is known about how other neuromodulatory systems contribute to cue-motivated behavior. Here, we examined the role of the NAc cholinergic receptor system in cue-motivated behavior using a Pavlovian-to-instrumental transfer task designed to assess the motivating influence of a reward-predictive cue over an independently-trained instrumental action. Disruption of NAc muscarinic acetylcholine receptor activity attenuated, whereas blockade of nicotinic receptors augmented cue-induced invigoration of reward seeking. We next examined a potential dopaminergic mechanism for this behavioral effect by combining fast-scan cyclic voltammetry with local pharmacological acetylcholine receptor manipulation. The data show evidence of opposing modulation of cue-evoked dopamine release, with muscarinic and nicotinic receptor antagonists causing suppression and augmentation, respectively, consistent with the behavioral effects of these manipulations. In addition to demonstrating cholinergic modulation of naturally-evoked and behaviorally-relevant dopamine signaling, these data suggest that NAc cholinergic receptors may gate the expression of cue-motivated behavior through modulation of phasic dopamine release.

[The molecular mechanisms and morphological manifestations of leiomyoma reduction induced by selective progesterone receptor modulators].

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Demura, T A; Revazova, Z V; Kogan, E A; Adamyan, L V

to investigate the molecular mechanisms and morphological substrate of reduced uterine leiomyoma in patients receiving the selective progesterone receptor modulator (SPRM) ulipristal acetate for 3 months, by estimating the immunohistochemical expression of the markers steroid receptor coactivator 1 (SRC-1), nuclear receptor corepressor 1 (NCoR-1), ER, PgR, Ki-67, p16, TGF-β, and VEGF in tumor tissue. The investigation enrolled 75 women with uterine leiomyoma, menorrhagias, and anemia. Group 1 included 40 patients who were treated with ulipristal for 3 months, followed by laparoscopic myomectomy. Group 2 consisted of 35 patients who underwent surgery without previous preparation. The intra- and postoperative parameters and molecular and morphological changes in the myomatous nodules were comparatively analyzed in both groups. After 3 months of therapy initiation, menorrhagia completely ceased, myomatous nodules decreased in size (pleiomyoma reduction was leiomyocyte apoptosis and dystrophy, tumor stroma sclerosis and hyalinosis with diminished Ki-67 expression and elevated p16 in the smooth muscle cells, trophic nodular tissue disorders exhibited by vascular wall sclerosis and lower VEGF and TGF-β expression, and leiomyocyte hormonal reception dysregulation that made itself evident through the reduced expression of SRC-1 with the unchanged expression of PR and ER and the maintained level of NCoR-1. The molecular mechanisms of tumor reduction involved the reduced Ki-67 expression and elevated p16, lower VEGF and TGF-β, diminished SRC-1 expression with the maintained level of PR, ER, and NCoR-1. Overall, this is suggestive of enhanced apoptosis and reduced leiomyoma proliferation and angiogenesis induced by SPRM and indicative of the expediency of using ulipristal acetate as a preoperative agent for organ-sparing surgery in reproductive-aged patients with uterine myoma, menorrhagias, and anemia.

Discovery of dual-action membrane-anchored modulators of incretin receptors.

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Jean-Philippe Fortin

Full Text Available The glucose-dependent insulinotropic polypeptide (GIP and the glucagon-like peptide-1 (GLP-1 receptors are considered complementary therapeutic targets for type 2 diabetes. Using recombinant membrane-tethered ligand (MTL technology, the present study focused on defining optimized modulators of these receptors, as well as exploring how local anchoring influences soluble peptide function.Serial substitution of residue 7 in membrane-tethered GIP (tGIP led to a wide range of activities at the GIP receptor, with [G(7]tGIP showing enhanced efficacy compared to the wild type construct. In contrast, introduction of G(7 into the related ligands, tGLP-1 and tethered exendin-4 (tEXE4, did not affect signaling at the cognate GLP-1 receptor. Both soluble and tethered GIP and GLP-1 were selective activators of their respective receptors. Although soluble EXE4 is highly selective for the GLP-1 receptor, unexpectedly, tethered EXE4 was found to be a potent activator of both the GLP-1 and GIP receptors. Diverging from the pharmacological properties of soluble and tethered GIP, the newly identified GIP-R agonists, (i.e. [G(7]tGIP and tEXE4 failed to trigger cognate receptor endocytosis. In an attempt to recapitulate the dual agonism observed with tEXE4, we conjugated soluble EXE4 to a lipid moiety. Not only did this soluble peptide activate both the GLP-1 and GIP receptors but, when added to receptor expressing cells, the activity persists despite serial washes.These findings suggest that conversion of a recombinant MTL to a soluble membrane anchored equivalent offers a means to prolong ligand function, as well as to design agonists that can simultaneously act on more than one therapeutic target.

Investigational hormone receptor agonists as ongoing female contraception: a focus on selective progesterone receptor modulators in early clinical development.

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Nelson, Anita L

2015-01-01

As efforts are made to continue to increase the safety of contraceptive methods, those without estrogen have attracted new attention. Progestin-only options are available in many delivery systems, but most cause disturbed bleeding patterns. For gynecologic patients, selective progesterone receptor modulators (SPRMs) have been approved for medical abortion, for ovulation suppression in emergency contraception, and for the treatment of heavy menstrual bleeding due to leiomyoma. This article discusses the role of SPRMs in controlling fertility on an ongoing basis with particular emphasis on mifepristone and ulipristal acetate (UPA), since none of the other compounds has progressed out of early Phase I - II testing. It also discusses important information about the mechanisms of action and safety of these two SPRMs. Of all the investigational hormone agonist/antagonists, SPRMs have demonstrated the greatest potential as ongoing female contraceptives. They have the ability to suppress ovulation after initiation of the luteinizing hormone (LH) surge without affecting ovarian production of estrogen or inducing any significant metabolic changes. SPRMs may well be able to provide longer term contraception as oral agents, vaginal rings, and perhaps even intrauterine devices. UPA has the greatest promise. Current research needs to be expanded.

NCS-1 associates with adenosine A2A receptors and modulates receptor function

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Gemma eNavarro

2012-04-01

Full Text Available Modulation of G protein-coupled receptor (GPCR signalling by local changes in intracellular calcium concentration is an established function of Calmodulin which is known to interact with many GPCRs. Less is known about the functional role of the closely related neuronal EF-hand Ca2+-sensor proteins that frequently associate with calmodulin targets with different functional outcome. In the present study we aimed to investigate if a target of calmodulin – the A2A adenosine receptor, is able to associate with two other neuronal calcium binding proteins, namely NCS-1 and caldendrin. Using bioluminescence resonance energy transfer and co-immunoprecipitation experiments we show the existence of A2A - NCS-1 complexes in living cells whereas caldendrin did not associate with A2A receptors under the conditions tested. Interestingly, NCS-1 binding modulated downstream A2A receptor intracellular signalling in a Ca2+-dependent manner. Taken together this study provides further evidence that neuronal Ca2+-sensor proteins play an important role in modulation of GPCR signalling.

Enhancing NMDA Receptor Function: Recent Progress on Allosteric Modulators

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Lulu Yao

2017-01-01

Full Text Available The N-methyl-D-aspartate receptors (NMDARs are subtype glutamate receptors that play important roles in excitatory neurotransmission and synaptic plasticity. Their hypo- or hyperactivation are proposed to contribute to the genesis or progression of various brain diseases, including stroke, schizophrenia, depression, and Alzheimer’s disease. Past efforts in targeting NMDARs for therapeutic intervention have largely been on inhibitors of NMDARs. In light of the discovery of NMDAR hypofunction in psychiatric disorders and perhaps Alzheimer’s disease, efforts in boosting NMDAR activity/functions have surged in recent years. In this review, we will focus on enhancing NMDAR functions, especially on the recent progress in the generation of subunit-selective, allosteric positive modulators (PAMs of NMDARs. We shall also discuss the usefulness of these newly developed NMDAR-PAMs.

Context-dependent modulation of alphabetagamma and alphabetadelta GABA A receptors by penicillin: implications for phasic and tonic inhibition.

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Feng, Hua-Jun; Botzolakis, Emmanuel J; Macdonald, Robert L

2009-01-01

Penicillin, an open-channel blocker of GABA(A) receptors, was recently reported to inhibit phasic, but not tonic, currents in hippocampal neurons. To distinguish between isoform-specific and context-dependent modulation as possible explanations for this selectivity, the effects of penicillin were evaluated on recombinant GABA(A) receptors expressed in HEK293T cells. When co-applied with saturating GABA, penicillin decreased peak amplitude, induced rebound, and prolonged deactivation of currents evoked from both synaptic and extrasynaptic receptor isoforms. However, penicillin had isoform-specific effects on the extent of desensitization, reflecting its ability to differentially modulate peak (non-equilibrium) and residual (near-equilibrium) currents. This suggested that the context of activation could determine the apparent sensitivity of a given receptor isoform to penicillin. To test this hypothesis, we explored the ability of penicillin to modulate synaptic and extrasynaptic isoform currents that were activated under more physiologically relevant conditions. Interestingly, while currents evoked from synaptic isoforms under phasic conditions (transient activation by a saturating concentration of GABA) were substantially inhibited by penicillin, currents evoked from extrasynaptic isoforms under tonic conditions (prolonged application by a sub-saturating concentration of GABA) were minimally affected. We therefore concluded that the reported inability of penicillin to modulate tonic currents could not simply be attributed to insensitivity of extrasynaptic receptors, but rather, reflected an inability to modulate these receptors in their native context of activation.

Bone anabolic effects of S-40503, a novel nonsteroidal selective androgen receptor modulator (SARM), in rat models of osteoporosis.

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Hanada, Keigo; Furuya, Kazuyuki; Yamamoto, Noriko; Nejishima, Hiroaki; Ichikawa, Kiyonoshin; Nakamura, Tsutomu; Miyakawa, Motonori; Amano, Seiji; Sumita, Yuji; Oguro, Nao

2003-11-01

A novel nonsteroidal androgen receptor (AR) binder, S-40503, was successfully generated in order to develop selective androgen receptor modulators (SARMs). We evaluated the binding specificity for nuclear receptors (NRs) and osteoanabolic activities of S-40503 in comparison with a natural nonaromatizable steroid, 5alpha-dihydrotestosterone (DHT). The compound preferentially bound to AR with nanomolar affinity among NRs. When S-40503 was administrated into orchiectomized (ORX) rats for 4 weeks, bone mineral density (BMD) of femur and muscle weight of levator ani were increased as markedly as DHT, but prostate weight was not elevated over the normal at any doses tested. In contrast, DHT administration caused about 1.5-fold increase in prostate weight. The reduced virilizing activity was clearly evident from the result that 4-week treatment of normal rats with S-40503 showed no enlargement of prostate. To confirm the bone anabolic effect, S-40503 was given to ovariectomized (OVX) rats for 2 months. The compound significantly increased the BMD and biomechanical strength of femoral cortical bone, whereas estrogen, anti-bone resorptive hormone, did not. The increase in periosteal mineral apposition rate (MAR) of the femur revealed direct bone formation activity of S-40503. It was unlikely that the osteoanabolic effect of the compound was attribute to the enhancement of muscle mass, because immobilized ORX rats treated with S-40503 showed a marked increase in BMD of tibial cortical bone without any actions on the surrounding muscle tissue. Collectively, our novel compound served as a prototype for SARMs, which had unique tissue selectivity with high potency for bone formation and lower impact upon sex accessory tissues.

Do serotonin(1-7) receptors modulate short and long-term memory?

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Meneses, A

2007-05-01

Evidence from invertebrates to human studies indicates that serotonin (5-hydroxytryptamine; 5-HT) system modulates short- (STM) and long-term memory (LTM). This work is primarily focused on analyzing the contribution of 5-HT, cholinergic and glutamatergic receptors as well as protein synthesis to STM and LTM of an autoshaping learning task. It was observed that the inhibition of hippocampal protein synthesis or new mRNA did not produce a significant effect on autoshaping STM performance but it did impair LTM. Both non-contingent protein inhibition and 5-HT depletion showed no effects. It was basically the non-selective 5-HT receptor antagonist cyproheptadine, which facilitated STM. However, the blockade of glutamatergic and cholinergic transmission impaired STM. In contrast, the selective 5-HT(1B) receptor antagonist SB-224289 facilitated both STM and LTM. Selective receptor antagonists for the 5-HT(1A) (WAY100635), 5-HT(1D) (GR127935), 5-HT(2A) (MDL100907), 5-HT(2C/2B) (SB-200646), 5-HT(3) (ondansetron) or 5-HT(4) (GR125487), 5-HT(6) (Ro 04-6790, SB-399885 and SB-35713) or 5-HT(7) (SB-269970) did not impact STM. Nevertheless, WAY100635, MDL100907, SB-200646, GR125487, Ro 04-6790, SB-399885 or SB-357134 facilitated LTM. Notably, some of these changes shown to be independent of food-intake. Concomitantly, these data indicate that '5-HT tone via 5-HT(1B) receptors' might function in a serial manner from STM to LTM, whereas working in parallel using 5-HT(1A), 5-HT(2A), 5-HT(2B/2C), 5-HT(4), or 5-HT(6) receptors.

Selective androgen receptor modulators (SARMs) negatively regulate triple-negative breast cancer growth and epithelial:mesenchymal stem cell signaling.

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Narayanan, Ramesh; Ahn, Sunjoo; Cheney, Misty D; Yepuru, Muralimohan; Miller, Duane D; Steiner, Mitchell S; Dalton, James T

2014-01-01

The androgen receptor (AR) is the most highly expressed steroid receptor in breast cancer with 75-95% of estrogen receptor (ER)-positive and 40-70% of ER-negative breast cancers expressing AR. Though historically breast cancers were treated with steroidal androgens, their use fell from favor because of their virilizing side effects and the emergence of tamoxifen. Nonsteroidal, tissue selective androgen receptor modulators (SARMs) may provide a novel targeted approach to exploit the therapeutic benefits of androgen therapy in breast cancer. Since MDA-MB-453 triple-negative breast cancer cells express mutated AR, PTEN, and p53, MDA-MB-231 triple-negative breast cancer cells stably expressing wildtype AR (MDA-MB-231-AR) were used to evaluate the in vitro and in vivo anti-proliferative effects of SARMs. Microarray analysis and epithelial:mesenchymal stem cell (MSC) co-culture signaling studies were performed to understand the mechanisms of action. Dihydrotestosterone and SARMs, but not bicalutamide, inhibited the proliferation of MDA-MB-231-AR. The SARMs reduced the MDA-MB-231-AR tumor growth and tumor weight by greater than 90%, compared to vehicle-treated tumors. SARM treatment inhibited the intratumoral expression of genes and pathways that promote breast cancer development through its actions on the AR. SARM treatment also inhibited the metastasis-promoting paracrine factors, IL6 and MMP13, and subsequent migration and invasion of epithelial:MSC co-cultures. 1. AR stimulation inhibits paracrine factors that are important for MSC interactions and breast cancer invasion and metastasis. 2. SARMs may provide promise as novel targeted therapies to treat AR-positive triple-negative breast cancer.

Selective androgen receptor modulators (SARMs negatively regulate triple-negative breast cancer growth and epithelial:mesenchymal stem cell signaling.

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Ramesh Narayanan

Full Text Available The androgen receptor (AR is the most highly expressed steroid receptor in breast cancer with 75-95% of estrogen receptor (ER-positive and 40-70% of ER-negative breast cancers expressing AR. Though historically breast cancers were treated with steroidal androgens, their use fell from favor because of their virilizing side effects and the emergence of tamoxifen. Nonsteroidal, tissue selective androgen receptor modulators (SARMs may provide a novel targeted approach to exploit the therapeutic benefits of androgen therapy in breast cancer.Since MDA-MB-453 triple-negative breast cancer cells express mutated AR, PTEN, and p53, MDA-MB-231 triple-negative breast cancer cells stably expressing wildtype AR (MDA-MB-231-AR were used to evaluate the in vitro and in vivo anti-proliferative effects of SARMs. Microarray analysis and epithelial:mesenchymal stem cell (MSC co-culture signaling studies were performed to understand the mechanisms of action.Dihydrotestosterone and SARMs, but not bicalutamide, inhibited the proliferation of MDA-MB-231-AR. The SARMs reduced the MDA-MB-231-AR tumor growth and tumor weight by greater than 90%, compared to vehicle-treated tumors. SARM treatment inhibited the intratumoral expression of genes and pathways that promote breast cancer development through its actions on the AR. SARM treatment also inhibited the metastasis-promoting paracrine factors, IL6 and MMP13, and subsequent migration and invasion of epithelial:MSC co-cultures.1. AR stimulation inhibits paracrine factors that are important for MSC interactions and breast cancer invasion and metastasis. 2. SARMs may provide promise as novel targeted therapies to treat AR-positive triple-negative breast cancer.

NMDA Receptor Modulators in the Treatment of Drug Addiction.

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Tomek, Seven E; Lacrosse, Amber L; Nemirovsky, Natali E; Olive, M Foster

2013-02-06

Glutamate plays a pivotal role in drug addiction, and the N-methyl-D-aspartate (NMDA) glutamate receptor subtype serves as a molecular target for several drugs of abuse. In this review, we will provide an overview of NMDA receptor structure and function, followed by a review of the mechanism of action, clinical efficacy, and side effect profile of NMDA receptor ligands that are currently in use or being explored for the treatment of drug addiction. These ligands include the NMDA receptor modulators memantine and acamprosate, as well as the partial NMDA agonist D-cycloserine. Data collected to date suggest that direct NMDA receptor modulators have relatively limited efficacy in the treatment of drug addiction, and that partial agonism of NMDA receptors may have some efficacy with regards to extinction learning during cue exposure therapy. However, the lack of consistency in results to date clearly indicates that additional studies are needed, as are studies examining novel ligands with indirect mechanisms for altering NMDA receptor function.

NMDA Receptor Modulators in the Treatment of Drug Addiction

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M. Foster Olive

2013-02-01

Full Text Available Glutamate plays a pivotal role in drug addiction, and the N-methyl-D-aspartate (NMDA glutamate receptor subtype serves as a molecular target for several drugs of abuse. In this review, we will provide an overview of NMDA receptor structure and function, followed by a review of the mechanism of action, clinical efficacy, and side effect profile of NMDA receptor ligands that are currently in use or being explored for the treatment of drug addiction. These ligands include the NMDA receptor modulators memantine and acamprosate, as well as the partial NMDA agonist D-cycloserine. Data collected to date suggest that direct NMDA receptor modulators have relatively limited efficacy in the treatment of drug addiction, and that partial agonism of NMDA receptors may have some efficacy with regards to extinction learning during cue exposure therapy. However, the lack of consistency in results to date clearly indicates that additional studies are needed, as are studies examining novel ligands with indirect mechanisms for altering NMDA receptor function.

Beta receptor-mediated modulation of the late positive potential in humans.

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de Rover, Mischa; Brown, Stephen B R E; Boot, Nathalie; Hajcak, Greg; van Noorden, Martijn S; van der Wee, Nic J A; Nieuwenhuis, Sander

2012-02-01

Electrophysiological studies have identified a scalp potential, the late positive potential (LPP), which is modulated by the emotional intensity of observed stimuli. Previous work has shown that the LPP reflects the modulation of activity in extrastriate visual cortical structures, but little is known about the source of that modulation. The present study investigated whether beta-adrenergic receptors are involved in the generation of the LPP. We used a genetic individual differences approach (experiment 1) and a pharmacological manipulation (experiment 2) to test the hypothesis that the LPP is modulated by the activation of β-adrenergic receptors. In experiment 1, we found that LPP amplitude depends on allelic variation in the β1-receptor gene polymorphism. In experiment 2, we found that LPP amplitude was modulated by the β-blocker propranolol in a direction dependent on subjects' level of trait anxiety: In participants with lower trait anxiety, propranolol led to a (nonsignificant) decrease in the LPP modulation; in participants with higher trait anxiety, propranolol increased the emotion-related LPP modulation. These results provide initial support for the hypothesis that the LPP reflects the downstream effects, in visual cortical areas, of β-receptor-mediated activation of the amygdala.

Selective estrogen receptor modulators (SERM: A new choice for postmenopausal women and physicians who worry on cancer

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Ali Baziad

2001-09-01

Full Text Available The postmenopausal state is characterized by the cessation of menstruation, loss of ovarian function, and a dramatic decrease in the level of circulating estrogen. This state of estrogen deficiency contributes to the acceleration of several age-related health problems in women, including cardiovascular disease, osteoporosis, and dementia. Estrogen replacement is clearly effective in the short-term and long-term treatment and prevention of postmenopausal symptoms. However, until now, the amount of HRT user is still very low. Fear of breast cancer and endometrial cancer are the most common concern in using hormone replacement therapy (HRT, although the relationship between long-term HRT and breast cancer remains controversial. For physicians or patients, who worry on cancer, the ideal drug is now available i.e. the selective estrogen receptor modulators (SERM, with the generic name raloxifine. (Med J Indones 2001; 10: 187-90Keywords: HRT, raloxifine, osteoporosis, CVD, tamoxifen

Translational PK-PD modelling of molecular target modulation for the AMPA receptor positive allosteric modulator Org 26576.

Science.gov (United States)

Bursi, Roberta; Erdemli, Gul; Campbell, Robert; Hutmacher, Matthew M; Kerbusch, Thomas; Spanswick, David; Jeggo, Ross; Nations, Kari R; Dogterom, Peter; Schipper, Jacques; Shahid, Mohammed

2011-12-01

The α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor potentiator Org 26576 represents an interesting pharmacological tool to evaluate the utility of glutamatergic enhancement towards the treatment of psychiatric disorders. In this study, a rat-human translational pharmacokinetic-pharmacodynamic (PK-PD) model of AMPA receptor modulation was used to predict human target engagement and inform dose selection in efficacy clinical trials. Modelling and simulation was applied to rat plasma and cerebrospinal fluid (CSF) pharmacokinetic and pharmacodynamic measurements to identify a target concentration (EC(80)) for AMPA receptor modulation. Human plasma pharmacokinetics was determined from 33 healthy volunteers and eight major depressive disorder patients. From four out of these eight patients, CSF PK was also determined. Simulations of human CSF levels were performed for several doses of Org 26576. Org 26576 (0.1-10 mg/kg, i.v.) potentiated rat hippocampal AMPA receptor responses in an exposure-dependant manner. The rat plasma and CSF PK data were fitted by one-compartment model each. The rat CSF PK-PD model yielded an EC(80) value of 593 ng/ml (90% confidence interval 406.8, 1,264.1). The human plasma and CSF PK data were simultaneously well described by a two-compartment model. Simulations showed that in humans at 100 mg QD, CSF levels of Org 26576 would exceed the EC(80) target concentration for about 2 h and that 400 mg BID would engage AMPA receptors for 24 h. The modelling approach provided useful insight on the likely human dose-molecular target engagement relationship for Org 26576. Based on the current analysis, 100 and 400 mg BID would be suitable to provide 'phasic' and 'continuous' AMPA receptor engagement, respectively.

Nonsteroidal Selective Androgen Receptor Modulators and Selective Estrogen Receptor β Agonists Moderate Cognitive Deficits and Amyloid-β Levels in a Mouse Model of Alzheimer’s Disease

Science.gov (United States)

2013-01-01

Decreases of the sex steroids, testosterone and estrogen, are associated with increased risk of Alzheimer’s disease. Testosterone and estrogen supplementation improves cognitive deficits in animal models of Alzheimer’s disease. Sex hormones play a role in the regulation of amyloid-β via induction of the amyloid-β degrading enzymes neprilysin and insulin-degrading enzyme. To mimic the effect of dihydrotestosterone (DHT), we administered a selective androgen receptor agonist, ACP-105, alone and in combination with the selective estrogen receptor β (ERβ) agonist AC-186 to male gonadectomized triple transgenic mice. We assessed long-term spatial memory in the Morris water maze, spontaneous locomotion, and anxiety-like behavior in the open field and in the elevated plus maze. We found that ACP-105 given alone decreases anxiety-like behavior. Furthermore, when ACP-105 is administered in combination with AC-186, they increase the amyloid-β degrading enzymes neprilysin and insulin-degrading enzyme and decrease amyloid-β levels in the brain as well as improve cognition. Interestingly, the androgen receptor level in the brain was increased by chronic treatment with the same combination treatment, ACP-105 and AC-186, not seen with DHT or ACP-105 alone. Based on these results, the beneficial effect of the selective ERβ agonist as a potential therapeutic for Alzheimer’s disease warrants further investigation. PMID:24020966

Modulating Estrogen Receptor-related Receptor-α Activity Inhibits Cell Proliferation*

Science.gov (United States)

Bianco, Stéphanie; Lanvin, Olivia; Tribollet, Violaine; Macari, Claire; North, Sophie; Vanacker, Jean-Marc

2009-01-01

High expression of the estrogen receptor-related receptor (ERR)-α in human tumors is correlated to a poor prognosis, suggesting an involvement of the receptor in cell proliferation. In this study, we show that a synthetic compound (XCT790) that modulates the activity of ERRα reduces the proliferation of various cell lines and blocks the G1/S transition of the cell cycle in an ERRα-dependent manner. XCT790 induces, in a p53-independent manner, the expression of the cell cycle inhibitor p21waf/cip1 at the protein, mRNA, and promoter level, leading to an accumulation of hypophosphorylated Rb. Finally, XCT790 reduces cell tumorigenicity in Nude mice. PMID:19546226

Effects of selective activation of M1 and M4 muscarinic receptors on object recognition memory performance in rats.

Science.gov (United States)

Galloway, Claire R; Lebois, Evan P; Shagarabi, Shezza L; Hernandez, Norma A; Manns, Joseph R

2014-01-01

Acetylcholine signaling through muscarinic receptors has been shown to benefit memory performance in some conditions, but pan-muscarinic activation also frequently leads to peripheral side effects. Drug therapies that selectively target M1 or M4 muscarinic receptors could potentially improve memory while minimizing side effects mediated by the other muscarinic receptor subtypes. The ability of three recently developed drugs that selectively activate M1 or M4 receptors to improve recognition memory was tested by giving Long-Evans rats subcutaneous injections of three different doses of the M1 agonist VU0364572, the M1 positive allosteric modulator BQCA or the M4 positive allosteric modulator VU0152100 before performing an object recognition memory task. VU0364572 at 0.1 mg/kg, BQCA at 1.0 mg/kg and VU0152100 at 3.0 and 30.0 mg/kg improved the memory performance of rats that performed poorly at baseline, yet the improvements in memory performance were the most statistically robust for VU0152100 at 3.0 mg/kg. The results suggested that selective M1 and M4 receptor activation each improved memory but that the likelihood of obtaining behavioral efficacy at a given dose might vary between subjects even in healthy groups depending on baseline performance. These results also highlighted the potential of drug therapies that selectively target M1 or M4 receptors to improve memory performance in individuals with impaired memory.

BA321, a novel carborane analog that binds to androgen and estrogen receptors, acts as a new selective androgen receptor modulator of bone in male mice

International Nuclear Information System (INIS)

Watanabe, Kenta; Hirata, Michiko; Tominari, Tsukasa; Matsumoto, Chiho; Endo, Yasuyuki; Murphy, Gillian; Nagase, Hideaki

2016-01-01

Carboranes are a class of carbon-containing polyhedral boron cluster compounds with globular geometry and hydrophobic surface that interact with hormone receptors such as estrogen receptor (ER) and androgen receptor (AR). We have synthesized BA321, a novel carborane compound, which binds to AR. We found here that it also binds to ERs, ERα and ERβ. In orchidectomized (ORX) mice, femoral bone mass was markedly reduced due to androgen deficiency and BA321 restored bone loss in the male, whilst the decreased weight of seminal vesicle in ORX mice was not recovered by administration of BA321. In female mice, BA321 acts as a pure estrogen agonist, and restored both the loss of bone mass and uterine atrophy due to estrogen deficiency in ovariectomized (OVX) mice. In bone tissues, the trabecular bone loss occurred in both ORX and OVX mice, and BA321 completely restored the trabecular bone loss in both sexes. Cortical bone loss occurred in ORX mice but not in OVX mice, and BA321 clearly restored cortical bone loss due to androgen deficiency in ORX mice. Therefore, BA321 is a novel selective androgen receptor modulator (SARM) that may offer a new therapy option for osteoporosis in the male. - Highlights: • A novel carborane compound BA321 binds to both AR and ERs, ERα and ERβ. • BA321 restores bone loss in orchidectomized mice without effects on sex organ. • BA321 acts as an estrogen agonist in bone and uterus in ovariectomized mice. • BA321 may be a new SARM to prevent the loss of musculoskeletal mass in elder men.

BA321, a novel carborane analog that binds to androgen and estrogen receptors, acts as a new selective androgen receptor modulator of bone in male mice

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Kenta [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Cooperative Major in Advanced Health Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Hirata, Michiko [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Tominari, Tsukasa [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Matsumoto, Chiho [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Endo, Yasuyuki [Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, 4-4-1, Komatsushima, Aoba-ku, Sendai, 981-8558 (Japan); Murphy, Gillian [Department of Oncology, University of Cambridge, Cancer Research UK, Cambridge Institute, Li Ka Shing Centre, Cambridge, CB2 0RE (United Kingdom); Nagase, Hideaki [Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan); Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, OX3 7FY (United Kingdom); and others

2016-09-09

Carboranes are a class of carbon-containing polyhedral boron cluster compounds with globular geometry and hydrophobic surface that interact with hormone receptors such as estrogen receptor (ER) and androgen receptor (AR). We have synthesized BA321, a novel carborane compound, which binds to AR. We found here that it also binds to ERs, ERα and ERβ. In orchidectomized (ORX) mice, femoral bone mass was markedly reduced due to androgen deficiency and BA321 restored bone loss in the male, whilst the decreased weight of seminal vesicle in ORX mice was not recovered by administration of BA321. In female mice, BA321 acts as a pure estrogen agonist, and restored both the loss of bone mass and uterine atrophy due to estrogen deficiency in ovariectomized (OVX) mice. In bone tissues, the trabecular bone loss occurred in both ORX and OVX mice, and BA321 completely restored the trabecular bone loss in both sexes. Cortical bone loss occurred in ORX mice but not in OVX mice, and BA321 clearly restored cortical bone loss due to androgen deficiency in ORX mice. Therefore, BA321 is a novel selective androgen receptor modulator (SARM) that may offer a new therapy option for osteoporosis in the male. - Highlights: • A novel carborane compound BA321 binds to both AR and ERs, ERα and ERβ. • BA321 restores bone loss in orchidectomized mice without effects on sex organ. • BA321 acts as an estrogen agonist in bone and uterus in ovariectomized mice. • BA321 may be a new SARM to prevent the loss of musculoskeletal mass in elder men.

DMPD: Modulation of Toll-interleukin 1 receptor mediated signaling. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 15662540 Modulation of Toll-interleukin 1 receptor mediated signaling. Li X, Qin J.... J Mol Med. 2005 Apr;83(4):258-66. Epub 2005 Jan 21. (.png) (.svg) (.html) (.csml) Show Modulation of Toll-i...nterleukin 1 receptor mediated signaling. PubmedID 15662540 Title Modulation of Toll-interleukin 1 receptor

A selective androgen receptor modulator with minimal prostate hypertrophic activity enhances lean body mass in male rats and stimulates sexual behavior in female rats.

Science.gov (United States)

Allan, George F; Tannenbaum, Pamela; Sbriscia, Tifanie; Linton, Olivia; Lai, Muh-Tsann; Haynes-Johnson, Donna; Bhattacharjee, Sheela; Zhang, Xuqing; Sui, Zhihua; Lundeen, Scott G

2007-08-01

Androgen receptor (AR) ligands with tissue selectivity (selective androgen receptor modulators, or SARMs) have potential for treating muscle wasting, hypogonadism of aging, osteoporosis, female sexual dysfunction, and other indications. JNJ-28330835 is a nonsteroidal AR ligand with mixed agonist and antagonist activity in androgen-responsive cell-based assays. It is an orally active SARM with muscle selectivity in orchidectomized rat models. It stimulated growth of the levator ani muscle, stimulating maximal growth at a dose of 10 mg/kg. At the same time, JNJ-28330835 reduced prostate weight in intact rats by a mean of 30% at 10 mg/kg, while having no inhibitory effect on muscle. Using magnetic resonance imaging (MRI) to monitor body composition, it prevented half of the loss of lean body mass associated with orchidectomy, and restored about 30% of lost lean mass to aged orchidectomized rats. It had agonist effects on markers of both osteoclast and osteoblast activity, suggesting that it reduces bone turnover. In a model of sexual behavior, JNJ-28330835 enhanced the preference of ovariectomized female rats for sexually intact male rats over nonsexual orchidectomized males. JNJ-28330835 is a prostate-sparing SARM with the potential for clinically beneficial effects in muscle-wasting diseases and sexual function disorders.

Allosteric Modulation of Muscarinic Acetylcholine Receptors

Czech Academy of Sciences Publication Activity Database

Jakubík, Jan; El-Fakahany, E. E.

2010-01-01

Roč. 3, č. 9 (2010), s. 2838-2860 ISSN 1424-8247 R&D Projects: GA ČR GA305/09/0681 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic acetylcholine receptors * allosteric modulation * Alzheimer´s disease Subject RIV: CE - Biochemistry

Context-Dependent Modulation of αβγ and αβγ GABAA Receptors by Penicillin: Implications for Phasic and Tonic Inhibition

Science.gov (United States)

Feng, Hua-Jun; Botzolakis, Emmanuel J.; Macdonald, Robert L.

2009-01-01

Summary Penicillin, an open-channel blocker of GABAA receptors, was recently reported to inhibit phasic, but not tonic, currents in hippocampal neurons. To distinguish between isoform-specific and context-dependent modulation as possible explanations for this selectivity, the effects of penicillin were evaluated on recombinant GABAA receptors expressed in HEK293T cells. When co-applied with saturating GABA, penicillin decreased peak amplitude, induced rebound, and prolonged deactivation of currents evoked from both synaptic and extrasynaptic receptor isoforms. However, penicillin had isoform-specific effects on the extent of desensitization, reflecting its ability to differentially modulate peak (non-equilibrium) and residual (near-equilibrium) currents. This suggested that the context of activation could determine the apparent sensitivity of a given receptor isoform to penicillin. To test this hypothesis, we explored the ability of penicillin to modulate synaptic and extrasynaptic isoforms that were activated under more physiologically relevant conditions. Interestingly, while currents evoked from synaptic isoforms under phasic conditions (transient activation by a saturating concentration of GABA) were substantially inhibited by penicillin, currents evoked from extrasynaptic isoforms under tonic conditions (prolonged application by a sub-saturating concentration of GABA) were minimally affected. We therefore concluded that the reported inability of penicillin to modulate tonic currents could not simply be attributed to insensitivity of extrasynaptic receptors, but rather, reflected an inability to modulate these receptors in their native context of activation. PMID:18775733

Novel, non-steroidal, selective androgen receptor modulators (SARMs) with anabolic activity in bone and muscle and improved safety profile.

Science.gov (United States)

Rosen, J; Negro-Vilar, A

2002-03-01

A novel approach to the treatment of osteoporosis in men, and possibly women, is the development of selective androgen receptor modulators (SARMs) that can stimulate formation of new bone with substantially diminished proliferative activity in the prostate, as well as reduced virilizing activity in women. Over the last several years, we have developed a program to discover and develop novel, non-steroidal, orally-active selective androgen receptor modulators (SARMs) that provide improved therapeutic benefits and reduce risk and side effects. In recent studies, we have used a skeletally mature orchiectomized (ORX) male rat as an animal model of male hypogonadism for assessing the efficacy of LGD2226, a nonsteroidal, non-aromatizable, and non-5alpha-reducible SARM. We assessed the activity of LGD2226 on bone turnover, bone mass and bone strength, and also evaluated the effects exerted on classic androgen-dependent targets, such as prostate, seminal vesicles and muscle. A substantial loss of bone density was observed in ORX animals, and this loss was prevented by SARMs, as well as standard androgens. Biochemical markers of bone turnover revealed an early increase of bone resorption in androgen-deficient rats that was repressed in ORX animals treated with the oral SARM, LGD2226, during a 4-month treatment period. Differences in architectural properties and bone strength were detected by histomorphometric and mechanical analyses, demonstrating beneficial effects of LGD2226 on bone quality in androgen-deficient rats. Histomorphometric analysis of cortical bone revealed distinct anabolic activity of LGD2226 in periosteal bone. LGD2226 was able to prevent bone loss and maintain bone quality in ORX rats by stimulating bone formation, while also inhibiting bone turnover. LGD2226 also exerted anabolic activity on the levator ani muscle. Taken together, these results suggest that orally-active, non-steroidal SARMs may be useful therapeutics for both muscle and bone in elderly

Implementation of a fluorescence-based screening assay identifies histamine H3 receptor antagonists clobenpropit and iodophenpropit as subunit-selective N-methyl-D-aspartate receptor antagonists

DEFF Research Database (Denmark)

Hansen, Kasper Bø; Mullasseril, Praseeda; Dawit, Sara

2010-01-01

N-Methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca(2+)-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe...... a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal...

The effects of 17β-estradiol and a selective estrogen receptor modulator, bazedoxifene, on ovarian carcinogenesis.

Science.gov (United States)

Romero, Iris L; Lee, WooSeok; Mitra, Anirban K; Gordon, Ilyssa O; Zhao, Yan; Leonhardt, Payton; Penicka, Carla V; Mui, Keeley L; Krausz, Thomas N; Greene, Geoffrey L; Lengyel, Ernst

2012-01-01

To test if estrogen promotes carcinogenesis in vitro and in a genetic mouse model of ovarian cancer and whether its effects can be inhibited by a novel selective estrogen receptor modulator (SERM), bazedoxifene. Bazedoxifene was synthesized and it was confirmed that the drug abrogated the uterine stimulatory effect of 17β-estradiol in mice. To determine if hormones alter tumorigenesis in vivo LSL-K-ras(G12D/+)Pten(loxP/loxP) mice were treated with vehicle control, 17β-estradiol or bazedoxifene. Hormone receptor status of a cell line established from LSL-K-ras(G12D/+)Pten(loxP/loxP) mouse ovarian tumors was characterized using Western blotting and immunohistochemistry. The cell line was treated with hormones and invasion assays were performed using Boyden chambers and proliferation was assessed using MTT assays. In vitro 17β-estradiol increased both the invasion and proliferation of ovarian cancer cells and bazedoxifene reversed these effects. However, in the genetic mouse model neither treatment with 17β-estradiol nor bazedoxifene changed mean tumor burden when compared to treatment with placebo. The mice in all treatment groups had similar tumor incidence, metastatic nodules and ascites. While 17β-estradiol increases the invasion and proliferation of ovarian cancer cells, these effects do not translate into increased tumor burden in a genetic mouse model of endometrioid ovarian cancer. Likewise, while the SERM reversed the detrimental effects of estrogen in vitro, there was no change in tumor burden in mice treated with bazedoxifene. These findings demonstrate the complex interplay between hormones and ovarian carcinogenesis. Copyright © 2011 Elsevier Inc. All rights reserved.

Dopamine Receptor Genes Modulate Associative Memory in Old Age.

Science.gov (United States)

Papenberg, Goran; Becker, Nina; Ferencz, Beata; Naveh-Benjamin, Moshe; Laukka, Erika J; Bäckman, Lars; Brehmer, Yvonne

2017-02-01

Previous research shows that associative memory declines more than item memory in aging. Although the underlying mechanisms of this selective impairment remain poorly understood, animal and human data suggest that dopaminergic modulation may be particularly relevant for associative binding. We investigated the influence of dopamine (DA) receptor genes on item and associative memory in a population-based sample of older adults (n = 525, aged 60 years), assessed with a face-scene item associative memory task. The effects of single-nucleotide polymorphisms of DA D1 (DRD1; rs4532), D2 (DRD2/ANKK1/Taq1A; rs1800497), and D3 (DRD3/Ser9Gly; rs6280) receptor genes were examined and combined into a single genetic score. Individuals carrying more beneficial alleles, presumably associated with higher DA receptor efficacy (DRD1 C allele; DRD2 A2 allele; DRD3 T allele), performed better on associative memory than persons with less beneficial genotypes. There were no effects of these genes on item memory or other cognitive measures, such as working memory, executive functioning, fluency, and perceptual speed, indicating a selective association between DA genes and associative memory. By contrast, genetic risk for Alzheimer disease (AD) was associated with worse item and associative memory, indicating adverse effects of APOE ε4 and a genetic risk score for AD (PICALM, BIN1, CLU) on episodic memory in general. Taken together, our results suggest that DA may be particularly important for associative memory, whereas AD-related genetic variations may influence overall episodic memory in older adults without dementia.

Modulation in selectivity and allosteric properties of small-molecule ligands for CC-chemokine receptors

DEFF Research Database (Denmark)

Thiele, Stefanie; Malmgaard-Clausen, Mikkel; Engel-Andreasen, Jens

2012-01-01

Among 18 human chemokine receptors, CCR1, CCR4, CCR5, and CCR8 were activated by metal ion Zn(II) or Cu(II) in complex with 2,2'-bipyridine or 1,10-phenanthroline with similar potencies (EC(50) from 3.9 to 172 μM). Besides being agonists, they acted as selective allosteric enhancers of CCL3. Thes...

Potent, nonsteroidal selective androgen receptor modulators (SARMs) based on 8H-[1,4]oxazino[2,3-f]quinolin-8-ones.

Science.gov (United States)

Higuchi, Robert I; Thompson, Anthony W; Chen, Jyun-Hung; Caferro, Thomas R; Cummings, Marquis L; Deckhut, Charlotte P; Adams, Mark E; Tegley, Christopher M; Edwards, James P; López, Francisco J; Kallel, E Adam; Karanewsky, Donald S; Schrader, William T; Marschke, Keith B; Zhi, Lin

2007-10-01

A series of androgen receptor modulators based on 8H-[1,4]oxazino[2,3-f]quinolin-8-ones was synthesized and evaluated in an androgen receptor transcriptional activation assay. The most potent analogues from the series exhibited single-digit nanomolar potency in vitro. Compound 18h demonstrated full efficacy in the maintenance of muscle weight, at 10 mg/kg, with reduced activity in prostate weight in an in vivo model of androgen action.

Enhanced A3 adenosine receptor selectivity of multivalent nucleoside-dendrimer conjugates

Directory of Open Access Journals (Sweden)

Shainberg Asher

2008-10-01

Full Text Available Abstract Background An approach to use multivalent dendrimer carriers for delivery of nucleoside signaling molecules to their cell surface G protein-coupled receptors (GPCRs was recently introduced. Results A known adenosine receptor (AR agonist was conjugated to polyamidoamine (PAMAM dendrimer carriers for delivery of the intact covalent conjugate to on the cell surface. Depending on the linking moiety, multivalent conjugates of the N6-chain elongated functionalized congener ADAC (N6-[4-[[[4-[[[(2-aminoethylamino]carbonyl]methyl]anilino]carbonyl]methyl]phenyl]-adenosine achieved unanticipated high selectivity in binding to the cytoprotective human A3 AR, a class A GPCR. The key to this selectivity of > 100-fold in both radioreceptor binding (Ki app = 2.4 nM and functional assays (EC50 = 1.6 nM in inhibition of adenylate cyclase was maintaining a free amino group (secondary in an amide-linked chain. Attachment of neutral amide-linked chains or thiourea-containing chains preserved the moderate affinity and efficacy at the A1 AR subtype, but there was no selectivity for the A3 AR. Since residual amino groups on dendrimers are associated with cytotoxicity, the unreacted terminal positions of this A3 AR-selective G2.5 dendrimer were present as carboxylate groups, which had the further benefit of increasing water-solubility. The A3 AR selective G2.5 dendrimer was also visualized binding the membrane of cells expressing the A3 receptor but did not bind cells that did not express the receptor. Conclusion This is the first example showing that it is feasible to modulate and even enhance the pharmacological profile of a ligand of a GPCR based on conjugation to a nanocarrier and the precise structure of the linking group, which was designed to interact with distal extracellular regions of the 7 transmembrane-spanning receptor. This ligand tool can now be used in pharmacological models of tissue rescue from ischemia and to probe the existence of A3 AR

Org 214007-0: a novel non-steroidal selective glucocorticoid receptor modulator with full anti-inflammatory properties and improved therapeutic index.

Science.gov (United States)

van Lierop, Marie-José C; Alkema, Wynand; Laskewitz, Anke J; Dijkema, Rein; van der Maaden, Hans M; Smit, Martin J; Plate, Ralf; Conti, Paolo G M; Jans, Christan G J M; Timmers, C Marco; van Boeckel, Constant A A; Lusher, Scott J; McGuire, Ross; van Schaik, Rene C; de Vlieg, Jacob; Smeets, Ruben L; Hofstra, Claudia L; Boots, Annemieke M H; van Duin, Marcel; Ingelse, Benno A; Schoonen, Willem G E J; Grefhorst, Aldo; van Dijk, Theo H; Kuipers, Folkert; Dokter, Wim H A

2012-01-01

Glucocorticoids (GCs) such as prednisolone are potent immunosuppressive drugs but suffer from severe adverse effects, including the induction of insulin resistance. Therefore, development of so-called Selective Glucocorticoid Receptor Modulators (SGRM) is highly desirable. Here we describe a non-steroidal Glucocorticoid Receptor (GR)-selective compound (Org 214007-0) with a binding affinity to GR similar to that of prednisolone. Structural modelling of the GR-Org 214007-0 binding site shows disturbance of the loop between helix 11 and helix 12 of GR, confirmed by partial recruitment of the TIF2-3 peptide. Using various cell lines and primary human cells, we show here that Org 214007-0 acts as a partial GC agonist, since it repressed inflammatory genes and was less effective in induction of metabolic genes. More importantly, in vivo studies in mice indicated that Org 214007-0 retained full efficacy in acute inflammation models as well as in a chronic collagen-induced arthritis (CIA) model. Gene expression profiling of muscle tissue derived from arthritic mice showed a partial activity of Org 214007-0 at an equi-efficacious dosage of prednisolone, with an increased ratio in repression versus induction of genes. Finally, in mice Org 214007-0 did not induce elevated fasting glucose nor the shift in glucose/glycogen balance in the liver seen with an equi-efficacious dose of prednisolone. All together, our data demonstrate that Org 214007-0 is a novel SGRMs with an improved therapeutic index compared to prednisolone. This class of SGRMs can contribute to effective anti-inflammatory therapy with a lower risk for metabolic side effects.

Peroxisome Proliferators-Activated Receptor (PPAR Modulators and Metabolic Disorders

Directory of Open Access Journals (Sweden)

Min-Chul Cho

2008-01-01

Full Text Available Overweight and obesity lead to an increased risk for metabolic disorders such as impaired glucose regulation/insulin resistance, dyslipidemia, and hypertension. Several molecular drug targets with potential to prevent or treat metabolic disorders have been revealed. Interestingly, the activation of peroxisome proliferator-activated receptor (PPAR, which belongs to the nuclear receptor superfamily, has many beneficial clinical effects. PPAR directly modulates gene expression by binding to a specific ligand. All PPAR subtypes (α,γ, and σ are involved in glucose metabolism, lipid metabolism, and energy balance. PPAR agonists play an important role in therapeutic aspects of metabolic disorders. However, undesired effects of the existing PPAR agonists have been reported. A great deal of recent research has focused on the discovery of new PPAR modulators with more beneficial effects and more safety without producing undesired side effects. Herein, we briefly review the roles of PPAR in metabolic disorders, the effects of PPAR modulators in metabolic disorders, and the technologies with which to discover new PPAR modulators.

Selective estrogen receptor modulator promotes weight loss in ovariectomized female rhesus monkeys (Macaca mulatta) by decreasing food intake and increasing activity.

Science.gov (United States)

Sullivan, Elinor L; Shearin, Jean; Koegler, Frank H; Cameron, Judy L

2012-04-01

The effect of hormone replacement therapy (HRT) on body weight in postmenopausal women is controversial, with studies reporting an increase, a decrease, and no change in body weight. To examine estrogen receptor actions on body weight, we investigated the effects of treatment with a selective estrogen receptor modulator (SERM) on body weight, food intake, and activity and metabolic rate in a nonhuman primate model. Eighteen ovariectomized female rhesus monkeys were treated with a nonsteroidal SERM (GSK232802A, 5 mg/kg po) for 3 mo. GSK232802A decreased lutenizing hormone (P Physical activity increased during the 3rd mo of treatment (P = 0.04). Baseline activity level and the change in activity due to treatment were correlated, with the most sedentary individuals exhibiting increased physical activity during the 1st mo of treatment (P = 0.02). Metabolic rate did not change (P = 0.58). These results indicate that GSK232802A treatment reduces body weight and adiposity in ovariectomized nonhuman primates by suppressing food intake and increasing activity, particularly in the most sedentary individuals. These findings suggest that SERM treatment may counteract weight gain in postmenopausal women.

Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins

Science.gov (United States)

Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

2016-01-01

Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel’s ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

Molecular sites for the positive allosteric modulation of glycine receptors by endocannabinoids.

Directory of Open Access Journals (Sweden)

Gonzalo E Yévenes

Full Text Available Glycine receptors (GlyRs are transmitter-gated anion channels of the Cys-loop superfamily which mediate synaptic inhibition at spinal and selected supraspinal sites. Although they serve pivotal functions in motor control and sensory processing, they have yet to be exploited as drug targets partly because of hitherto limited possibilities for allosteric control. Endocannabinoids (ECs have recently been characterized as direct allosteric GlyR modulators, but the underlying molecular sites have remained unknown. Here, we show that chemically neutral ECs (e.g. anandamide, AEA are positive modulators of α(1, α(2 and α(3 GlyRs, whereas acidic ECs (e.g. N-arachidonoyl-glycine; NA-Gly potentiate α(1 GlyRs but inhibit α(2 and α(3. This subunit-specificity allowed us to identify the underlying molecular sites through analysis of chimeric and mutant receptors. We found that alanine 52 in extracellular loop 2, glycine 254 in transmembrane (TM region 2 and intracellular lysine 385 determine the positive modulation of α(1 GlyRs by NA-Gly. Successive substitution of non-conserved extracellular and TM residues in α(2 converted NA-Gly-mediated inhibition into potentiation. Conversely, mutation of the conserved lysine within the intracellular loop between TM3 and TM4 attenuated NA-Gly-mediated potentiation of α(1 GlyRs, without affecting inhibition of α(2 and α(3. Notably, this mutation reduced modulation by AEA of all three GlyRs. These results define molecular sites for allosteric control of GlyRs by ECs and reveal an unrecognized function for the TM3-4 intracellular loop in the allosteric modulation of Cys-loop ion channels. The identification of these sites may help to understand the physiological role of this modulation and facilitate the development of novel therapeutic approaches to diseases such as spasticity, startle disease and possibly chronic pain.

Caffeine and Selective Adenosine Receptor Antagonists as New Therapeutic Tools for the Motivational Symptoms of Depression

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Laura López-Cruz

2018-06-01

Full Text Available Major depressive disorder is one of the most common and debilitating psychiatric disorders. Some of the motivational symptoms of depression, such anergia (lack of self-reported energy and fatigue are relatively resistant to traditional treatments such as serotonin uptake inhibitors. Thus, new pharmacological targets are being investigated. Epidemiological data suggest that caffeine consumption can have an impact on aspects of depressive symptomatology. Caffeine is a non-selective adenosine antagonist for A1/A2A receptors, and has been demonstrated to modulate behavior in classical animal models of depression. Moreover, selective adenosine receptor antagonists are being assessed for their antidepressant effects in animal studies. This review focuses on how caffeine and selective adenosine antagonists can improve different aspects of depression in humans, as well as in animal models. The effects on motivational symptoms of depression such as anergia, fatigue, and psychomotor slowing receive particular attention. Thus, the ability of adenosine receptor antagonists to reverse the anergia induced by dopamine antagonism or depletion is of special interest. In conclusion, although further studies are needed, it appears that caffeine and selective adenosine receptor antagonists could be therapeutic agents for the treatment of motivational dysfunction in depression.

Modulation of inhibitory activity markers by intermittent theta-burst stimulation in rat cortex is NMDA-receptor dependent.

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Labedi, Adnan; Benali, Alia; Mix, Annika; Neubacher, Ute; Funke, Klaus

2014-01-01

Intermittent theta-burst stimulation (iTBS) applied via transcranial magnetic stimulation has been shown to increase cortical excitability in humans. In the rat brain it strongly reduced the number of neurons expressing the 67-kD isoform of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD67) and those expressing the calcium-binding proteins parvalbumin (PV) and calbindin (CB), specific markers of fast-spiking (FS) and non-FS inhibitory interneurons, respectively, an indication of modified cortical inhibition. Since iTBS effects in humans have been shown to be NMDA receptor sensitive, we wondered whether the iTBS-induced changes in the molecular phenotype of interneurons may be also sensitive to glutamatergic synaptic transmission mediated by NMDA receptors. In a sham-controlled fashion, five iTBS-blocks of 600 stimuli were applied to rats either lightly anesthetized by only urethane or by an additional low (subnarcotic) or high dose of the NMDA receptor antagonist ketamine before immunohistochemical analysis. iTBS reduced the number of neurons expressing GAD67, PV and CB. Except for CB, a low dose of ketamine partially prevented these effects while a higher dose almost completely abolished the iTBS effects. Our findings indicate that iTBS modulates the molecular, and likely also the electric, activity of cortical inhibitory interneurons and that the modulation of FS-type but less that of non-FS-type neurons is mediated by NMDA receptors. A combination of iTBS with pharmacological interventions affecting distinct receptor subtypes may thus offer options to enhance its selectivity in modulating the activity of distinct cell types and preventing others from being modulated. Copyright © 2014 Elsevier Inc. All rights reserved.

Differential Modulation of GABAA and NMDA Receptors by an α7-nicotinic Acetylcholine Receptor Agonist in Chronic Glaucoma

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Xujiao Zhou

2017-12-01

Full Text Available Presynaptic modulation of γ-aminobutyric acid (GABA release by an alpha7 nicotinic acetylcholine receptor (α7-nAChR agonist promotes retinal ganglion cell (RGC survival and function, as suggested by a previous study on a chronic glaucomatous model from our laboratory. However, the role of excitatory and inhibitory amino acid receptors and their interaction with α7-nAChR in physiological and glaucomatous events remains unknown. In this study, we investigated GABAA and N-methyl-D-aspartate (NMDA receptor activity in control and glaucomatous retinal slices and the regulation of amino acid receptor expression and function by α7-nAChR. Whole-cell patch-clamp recordings from RGCs revealed that the α7-nAChR specific agonist PNU-282987 enhanced the amplitude of currents elicited by GABA and reduced the amplitude of currents elicited by NMDA. The positive modulation of GABAA receptor and the negative modulation of NMDA receptor (NMDAR by PNU-282987-evoked were prevented by pre-administration of the α7-nAChR antagonist methyllycaconitine (MLA. The frequency and the amplitude of glutamate receptor-mediated miniature glutamatergic excitatory postsynaptic currents (mEPSCs were not significantly different between the control and glaucomatous RGCs. Additionally, PNU-282987-treated slices showed no alteration in the frequency or amplitude of mEPSCs relative to control RGCs. Moreover, we showed that expression of the α1 subunit of the GABAA receptor was downregulated and the expression of the NMDAR NR2B subunit was upregulated by intraocular pressure (IOP elevation, and the changes of high IOP were blocked by PNU-282987. In conclusion, retina GABAA and NMDARs are modulated positively and negatively, respectively, by activation of α7-nAChR in in vivo chronic glaucomatous models.

Structural and functional studies of the modulator NS9283 reveal agonist-like mechanism of action at α4β2 nicotinic acetylcholine receptors

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Olsen, Jeppe A; Ahring, Philip K; Kastrup, Jette Sandholm Jensen

2014-01-01

Modulation of Cys loop receptor ion channels is a proven drug discovery strategy, but many underlying mechanisms of the mode of action are poorly understood. We report the x-ray structure of the acetylcholine-binding protein from Lymnaea stagnalis with NS9283, a stoichiometry selective positive...... on efficacy. The shared modulatory profile along with a binding site located in an extracellular subunit interface suggest that modulation via an agonist-like mechanism may be a common mechanism of action that potentially could apply to Cys loop receptors beyond the α4β2 nAChRs....... modulator that targets the α4-α4 interface of α4β2 nicotinic acetylcholine receptors (nAChRs). Together with homology modeling, mutational data, quantum mechanical calculations, and pharmacological studies on α4β2 nAChRs, the structure reveals a modulator binding mode that overlaps the α4-α4 interface...

Identifying the receptor subtype selectivity of retinoid X and retinoic acid receptors via quantum mechanics.

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Tsuji, Motonori; Shudo, Koichi; Kagechika, Hiroyuki

2017-03-01

Understanding and identifying the receptor subtype selectivity of a ligand is an important issue in the field of drug discovery. Using a combination of classical molecular mechanics and quantum mechanical calculations, this report assesses the receptor subtype selectivity for the human retinoid X receptor (hRXR) and retinoic acid receptor (hRAR) ligand-binding domains (LBDs) complexed with retinoid ligands. The calculated energies show good correlation with the experimentally reported binding affinities. The technique proposed here is a promising method as it reveals the origin of the receptor subtype selectivity of selective ligands.

Overlapping binding site for the endogenous agonist, small-molecule agonists, and ago-allosteric modulators on the ghrelin receptor

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Holst, Birgitte; Frimurer, Thomas M; Mokrosinski, Jacek

2008-01-01

A library of robust ghrelin receptor mutants with single substitutions at 22 positions in the main ligand-binding pocket was employed to map binding sites for six different agonists: two peptides (the 28-amino-acid octanoylated endogenous ligand ghrelin and the hexapeptide growth hormone......, and PheVI:23 on the opposing face of transmembrane domain (TM) VI. Each of the agonists was also affected selectively by specific mutations. The mutational map of the ability of L-692,429 and GHRP-6 to act as allosteric modulators by increasing ghrelin's maximal efficacy overlapped with the common....... It is concluded that although each of the ligands in addition exploits other parts of the receptor, a large, common binding site for both small-molecule agonists--including ago-allosteric modulators--and the endogenous agonist is found on the opposing faces of TM-III and -VI of the ghrelin receptor....

Discovery, synthesis, selectivity modulation and DMPK characterization of 5-azaspiro[2.4]heptanes as potent orexin receptor antagonists.

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Stasi, Luigi Piero; Artusi, Roberto; Bovino, Clara; Buzzi, Benedetta; Canciani, Luca; Caselli, Gianfranco; Colace, Fabrizio; Garofalo, Paolo; Giambuzzi, Silvia; Larger, Patrice; Letari, Ornella; Mandelli, Stefano; Perugini, Lorenzo; Pucci, Sabrina; Salvi, Matteo; Toro, PierLuigi

2013-05-01

Starting from a orexin 1 receptor selective antagonist 4,4-disubstituted piperidine series a novel potent 5-azaspiro[2.4]heptane dual orexin 1 and orexin 2 receptor antagonist class has been discovered. SAR and Pharmacokinetic optimization of this series is herein disclosed. Lead compound 15 exhibits potent activity against orexin 1 and orexin 2 receptors along with low cytochrome P450 inhibition potential, good brain penetration and oral bioavailability in rats. Copyright © 2013 Elsevier Ltd. All rights reserved.

Muscarinic receptors modulate dendrodendritic inhibitory synapses to sculpt glomerular output.

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Liu, Shaolin; Shao, Zuoyi; Puche, Adam; Wachowiak, Matt; Rothermel, Markus; Shipley, Michael T

2015-04-08

Cholinergic [acetylcholine (ACh)] axons from the basal forebrain innervate olfactory bulb glomeruli, the initial site of synaptic integration in the olfactory system. Both nicotinic acetylcholine receptors (nAChRs) and muscarinic acetylcholine receptors (mAChRs) are expressed in glomeruli. The activation of nAChRs directly excites both mitral/tufted cells (MTCs) and external tufted cells (ETCs), the two major excitatory neurons that transmit glomerular output. The functional roles of mAChRs in glomerular circuits are unknown. We show that the restricted glomerular application of ACh causes rapid, brief nAChR-mediated excitation of both MTCs and ETCs in the mouse olfactory bulb. This excitation is followed by mAChR-mediated inhibition, which is blocked by GABAA receptor antagonists, indicating the engagement of periglomerular cells (PGCs) and/or short axon cells (SACs), the two major glomerular inhibitory neurons. Indeed, selective activation of glomerular mAChRs, with ionotropic GluRs and nAChRs blocked, increased IPSCs in MTCs and ETCs, indicating that mAChRs recruit glomerular inhibitory circuits. Selective activation of glomerular mAChRs in the presence of tetrodotoxin increased IPSCs in all glomerular neurons, indicating action potential-independent enhancement of GABA release from PGC and/or SAC dendrodendritic synapses. mAChR-mediated enhancement of GABA release also presynaptically suppressed the first synapse of the olfactory system via GABAB receptors on sensory terminals. Together, these results indicate that cholinergic modulation of glomerular circuits is biphasic, involving an initial excitation of MTC/ETCs mediated by nAChRs followed by inhibition mediated directly by mAChRs on PGCs/SACs. This may phasically enhance the sensitivity of glomerular outputs to odorants, an action that is consistent with recent in vivo findings. Copyright © 2015 the authors 0270-6474/15/355680-13$15.00/0.

[Pharmacological characteristics of drugs targeted on calcium-sensing receptor.-properties of cinacalcet hydrochloride as allosteric modulator].

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Nagano, Nobuo; Tsutsui, Takaaki

2016-06-01

Calcimimetics act as positive allosteric modulators of the calcium-sensing receptor (CaSR), thereby decreasing parathyroid hormone (PTH) secretion from the parathyroid glands. On the other hand, negative allosteric modulators of the CaSR with stimulatory effect on PTH secretion are termed calcilytics. The calcimimetic cinacalcet hydrochloride (cinacalcet) is the world's first allosteric modulator of G protein-coupled receptor to enter the clinical market. Cinacalcet just tunes the physiological effects of Ca(2+), an endogenous ligand, therefore, shows high selectivity and low side effects. Calcimimetics also increase cell surface CaSR expression by acting as pharmacological chaperones (pharmacoperones). It is considered that the cinacalcet-induced upper gastrointestinal problems are resulted from enhanced physiological responses to Ca(2+) and amino acids via increased sensitivity of digestive tract CaSR by cinacalcet. While clinical developments of calcilytics for osteoporosis were unfortunately halted or terminated due to paucity of efficacy, it is expected that calcilytics may be useful for the treatment of patients with activating CaSR mutations, asthma, and idiopathic pulmonary artery hypertension.

Discovery of estrogen receptor α modulators from natural compounds in Si-Wu-Tang series decoctions using estrogen-responsive MCF-7 breast cancer cells.

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Liu, Li; Ma, Hongyue; Tang, Yuping; Chen, Wenxing; Lu, Yin; Guo, Jianming; Duan, Jin-Ao

2012-01-01

The binding between the estrogen receptor α (ER-α) and a variety of compounds in traditional Chinese formulae, Si-Wu-Tang (SWT) series decoctions, was studied using a stably-transfected human breast cancer cell line (MVLN). In 38 compounds tested from SWT series decoctions, the estrogen-like activity of 22 compounds was above 60% in 20 μg mL(-1). Furthermore, theoretical affinity of these compounds was certificated using the functional virtual screen of ER-α modulators by FlexX-Pharm. The accuracy of functional virtual screening of ER-α modulators could reach to 77.27%. The results showed that some compounds, such as organic acids and flavones in SWT series decoctions could be used as selective estrogen receptor modulators (SERMs) and could be selected for further development as potential agents for estrogen related diseases. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

OpenAIRE

Connor, Mark

2012-01-01

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

Intracellular calcium levels determine differential modulation of allosteric interactions within G protein-coupled receptor heteromers.

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Navarro, Gemma; Aguinaga, David; Moreno, Estefania; Hradsky, Johannes; Reddy, Pasham P; Cortés, Antoni; Mallol, Josefa; Casadó, Vicent; Mikhaylova, Marina; Kreutz, Michael R; Lluís, Carme; Canela, Enric I; McCormick, Peter J; Ferré, Sergi

2014-11-20

The pharmacological significance of the adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromer is well established and it is being considered as an important target for the treatment of Parkinson’s disease and other neuropsychiatric disorders. However, the physiological factors that control its distinctive biochemical properties are still unknown. We demonstrate that different intracellular Ca2+ levels exert a differential modulation of A2AR-D2R heteromer-mediated adenylyl-cyclase and MAPK signaling in striatal cells. This depends on the ability of low and high Ca2+ levels to promote a selective interaction of the heteromer with the neuronal Ca2+-binding proteins NCS-1 and calneuron-1, respectively. These Ca2+-binding proteins differentially modulate allosteric interactions within the A2AR-D2R heteromer, which constitutes a unique cellular device that integrates extracellular (adenosine and dopamine) and intracellular (Ca+2) signals to produce a specific functional response.

Medium chain fatty acids are selective peroxisome proliferator activated receptor (PPAR) γ activators and pan-PPAR partial agonists

NARCIS (Netherlands)

Liberato, Marcelo Vizoná; Nascimento, Alessandro S; Ayers, Steven D; Lin, Jean Z; Cvoro, Aleksandra; Silveira, Rodrigo L; Martínez, Leandro; Souza, Paulo C T; Saidemberg, Daniel; Deng, Tuo; Amato, Angela Angelica; Togashi, Marie; Hsueh, Willa A; Phillips, Kevin; Palma, Mário Sérgio; Neves, Francisco A R; Skaf, Munir S; Webb, Paul; Polikarpov, Igor

2012-01-01

Thiazolidinediones (TZDs) act through peroxisome proliferator activated receptor (PPAR) γ to increase insulin sensitivity in type 2 diabetes (T2DM), but deleterious effects of these ligands mean that selective modulators with improved clinical profiles are needed. We obtained a crystal structure of

Abnormal excessive per vagina (PV) bleeding on Esmya-selective progesterone receptor modulator (SPRM) in a symptomatic patient with uterine fibroid.

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Matytsina-Quinlan, Lyubov; Matytsina, Laura

2015-05-14

A woman in her late 40s presented with excessive per vagina (PV) bleeding and uterine fibroid. She reported excessive PV bleeding after starting Esmya; she was brought in by ambulance to the emergency department with profuse bleeding. Abnormal uterine bleeding (AUB) developed after selective progesterone receptor modulator (SPRM) administration in this symptomatic patient with uterine fibroid. The drug was withheld and surgical treatment considered. Progressive deterioration of PV bleeding after receiving SPRM led to an urgent laparoscopic total hysterectomy, which had to be postponed due to severe anaemia. Surgery took place regardless because the excessive bleeding continued. Histology revealed a 6 cm submucosal uterine fibroid (SMUF) and adenomyosis. Physicians prescribing SPRMs to stop PV bleeding should be aware of potential AUB, which could lead to urgent hysterectomy. The mechanism of action of SPRMs is not clearly understood. Awareness of the side effects of Esmya, such as AUB, must be kept in mind when administering SPRMs. 2015 BMJ Publishing Group Ltd.

Selective Vitamin D Receptor Activation as Anti-Inflammatory Target in Chronic Kidney Disease

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J. Donate-Correa

2014-01-01

Full Text Available Paricalcitol, a selective vitamin D receptor (VDR activator used for treatment of secondary hyperparathyroidism in chronic kidney disease (CKD, has been associated with survival advantages, suggesting that this drug, beyond its ability to suppress parathyroid hormone, may have additional beneficial actions. In this prospective, nonrandomised, open-label, proof-of-concept study, we evaluated the hypothesis that selective vitamin D receptor activation with paricalcitol is an effective target to modulate inflammation in CKD patients. Eight patients with an estimated glomerular filtration rate between 15 and 44 mL/min/1.73 m2 and an intact parathyroid hormone (PTH level higher than 110 pg/mL received oral paricalcitol (1 μg/48 hours as therapy for secondary hyperparathyroidism. Nine patients matched by age, sex, and stage of CKD, but a PTH level <110 pg/mL, were enrolled as a control group. Our results show that five months of paricalcitol administration were associated with a reduction in serum concentrations of hs-CRP (13.9%, P<0.01, TNF-α (11.9%, P=0.01, and IL-6 (7%, P<0.05, with a nonsignificant increase of IL-10 by 16%. In addition, mRNA expression levels of the TNFα and IL-6 genes in peripheral blood mononuclear cells decreased significantly by 30.8% (P=0.01 and 35.4% (P=0.01, respectively. In conclusion, selective VDR activation is an effective target to modulate inflammation in CKD.

How nonuniform contact profiles of T cell receptors modulate thymic selection outcomes

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Chen, Hanrong; Chakraborty, Arup K.; Kardar, Mehran

2018-03-01

T cell receptors (TCRs) bind foreign or self-peptides attached to major histocompatibility complex (MHC) molecules, and the strength of this interaction determines T cell activation. Optimizing the ability of T cells to recognize a diversity of foreign peptides yet be tolerant of self-peptides is crucial for the adaptive immune system to properly function. This is achieved by selection of T cells in the thymus, where immature T cells expressing unique, stochastically generated TCRs interact with a large number of self-peptide-MHC; if a TCR does not bind strongly enough to any self-peptide-MHC, or too strongly with at least one self-peptide-MHC, the T cell dies. Past theoretical work cast thymic selection as an extreme value problem and characterized the statistical enrichment or depletion of amino acids in the postselection TCR repertoire, showing how T cells are selected to be able to specifically recognize peptides derived from diverse pathogens yet have limited self-reactivity. Here, we investigate how the diversity of the postselection TCR repertoire is modified when TCRs make nonuniform contacts with peptide-MHC. Specifically, we were motivated by recent experiments showing that amino acids at certain positions of a TCR sequence have large effects on thymic selection outcomes, and crystal structure data that reveal a nonuniform contact profile between a TCR and its peptide-MHC ligand. Using a representative TCR contact profile as an illustration, we show via simulations that the statistical enrichment or depletion of amino acids now varies by position according to the contact profile, and, importantly, it depends on the implementation of nonuniform contacts during thymic selection. We explain these nontrivial results analytically. Our study has implications for understanding the selection forces that shape the functionality of the postselection TCR repertoire.

QSAR of estrogen receptor modulators: exploring selectivity requirements for ER(alpha) versus ER(beta) binding of tetrahydroisoquinoline derivatives using E-state and physicochemical parameters.

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Mukherjee, Subhendu; Saha, Achintya; Roy, Kunal

2005-02-15

Considering importance of developing selective estrogen receptor modulators (SERMs), the present paper explores selectivity requirements of tetrahydroisoquinoline derivatives for binding with ER(alpha) versus ER(beta) receptors using E-state index and physicochemical parameters. The best model [n=21, Q(2)=0.512, R(a)(2)=0.613, R=0.819, F=11.6 (df 3,17)] for ER(alpha) binding data obtained from radioligand binding assay showed importance of C(1), C(15) and lipophilicity (logP) while the best model [n=21, Q(2)=0.768, R(a)(2)=0.796, R=0.904, F=40.1 (df 2,18)] for ER(beta) binding data showed importance of C(1) and molar refractivity (MR). While modeling ER(alpha)/ER(beta) selectivity [n=21, Q(2)=0.695, R(a)(2)=0.739, R=0.882, F=19.8 (df 3,17)], C(1), C(15) and molar refractivity were found to be significant contributors. The data obtained from cellular transcription assay were also modeled. In case of ER(alpha), the best equation involving E-state values of C(1) and C(14) and logP explained 62.1% of the variance while the best equation for ER(beta) involving E-state values of C(1) and C(15) and MR explained 64.6% of the variance of the response variable. In case of ER(alpha)/ER(beta) selectivity, the best equation involving E-state values of O(8), C(14) and N(27) showed 48.3% explained variance, which increased to 63.5% on deletion of single outlier. From the analysis it appears that the nitrogen atom of the aminoethoxyphenyl substituent and 6-hydroxy substituent of the tetrahydroisoquinoline nucleus play important roles for ER(alpha)/ER(beta) selectivity in addition to R(1) and R(2) substituents.

Dopamine receptors modulate cytotoxicity of natural killer cells via cAMP-PKA-CREB signaling pathway.

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Wei Zhao

Full Text Available Dopamine (DA, a neurotransmitter in the nervous system, has been shown to modulate immune function. We have previously reported that five subtypes of DA receptors, including D1R, D2R, D3R, D4R and D5R, are expressed in T lymphocytes and they are involved in regulation of T cells. However, roles of these DA receptor subtypes and their coupled signal-transduction pathway in modulation of natural killer (NK cells still remain to be clarified. The spleen of mice was harvested and NK cells were isolated and purified by negative selection using magnetic activated cell sorting. After NK cells were incubated with various drugs for 4 h, flow cytometry measured cytotoxicity of NK cells against YAC-1 lymphoma cells. NK cells expressed the five subtypes of DA receptors at mRNA and protein levels. Activation of D1-like receptors (including D1R and D5R with agonist SKF38393 enhanced NK cell cytotoxicity, but activation of D2-like receptors (including D2R, D3R and D4R with agonist quinpirole attenuated NK cells. Simultaneously, SKF38393 elevated D1R and D5R expression, cAMP content, and phosphorylated cAMP-response element-binding (CREB level in NK cells, while quinpirole reduced D3R and D4R expression, cAMP content, and phosphorylated CREB level in NK cells. These effects of SKF38393 were blocked by SCH23390, an antagonist of D1-like receptors, and quinpirole effects were abolished by haloperidol, an antagonist of D2-like receptors. In support these results, H89, an inhibitor of phosphokinase A (PKA, prevented the SKF38393-dependent enhancement of NK cells and forskolin, an activator of adenylyl cyclase (AC, counteracted the quinpirole-dependent suppression of NK cells. These findings show that DA receptor subtypes are involved in modulation of NK cells and suggest that D1-like receptors facilitate NK cells by stimulating D1R/D5R-cAMP-PKA-CREB signaling pathway and D2-like receptors suppress NK cells by inhibiting D3R/D4R-cAMP-PKA-CREB signaling pathway. The

Context-Dependent Modulation of αβγ and αβγ GABAA Receptors by Penicillin: Implications for Phasic and Tonic Inhibition

OpenAIRE

Feng, Hua-Jun; Botzolakis, Emmanuel J.; Macdonald, Robert L.

2008-01-01

Penicillin, an open-channel blocker of GABAA receptors, was recently reported to inhibit phasic, but not tonic, currents in hippocampal neurons. To distinguish between isoform-specific and context-dependent modulation as possible explanations for this selectivity, the effects of penicillin were evaluated on recombinant GABAA receptors expressed in HEK293T cells. When co-applied with saturating GABA, penicillin decreased peak amplitude, induced rebound, and prolonged deactivation of currents e...

Evaluation of the Biological Activity of Opuntia ficus indica as a Tissue- and Estrogen Receptor Subtype-Selective Modulator.

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An, Byoung Ha; Jeong, Hyesoo; Zhou, Wenmei; Liu, Xiyuan; Kim, Soolin; Jang, Chang Young; Kim, Hyun-Sook; Sohn, Johann; Park, Hye-Jin; Sung, Na-Hye; Hong, Cheol Yi; Chang, Minsun

2016-06-01

Phytoestrogens are selective estrogen receptor modulators (SERMs) with potential for use in hormone replacement therapy (HRT) to relieve peri/postmenopausal symptoms. This study was aimed at elucidating the molecular mechanisms underlying the SERM properties of the extract of Korean-grown Opuntia ficus-indica (KOFI). The KOFI extract induced estrogen response element (ERE)-driven transcription in breast and endometrial cancer cell lines and the expression of endogenous estrogen-responsive genes in breast cancer cells. The flavonoid content of different KOFI preparations affected ERE-luciferase activities, implying that the flavonoid composition likely mediated the estrogenic activities in cells. Oral administration of KOFI decreased the weight gain and levels of both serum glucose and triglyceride in ovariectomized (OVX) rats. Finally, KOFI had an inhibitory effect on the 17β-estradiol-induced proliferation of the endometrial epithelium in OVX rats. Our data demonstrate that KOFI exhibited SERM activity with no uterotrophic side effects. Therefore, KOFI alone or in combination with other botanical supplements, vitamins, or minerals may be an effective and safe alternative active ingredient to HRTs, for the management of postmenopausal symptoms. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

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de Fiebre, Nancyellen C; de Fiebre, Christopher M

2005-01-03

The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

Structure-Function Evaluation of Imidazopyridine Derivatives Selective for δ-Subunit-Containing γ-Aminobutyric Acid Type A (GABAA) Receptors.

Science.gov (United States)

Yakoub, Kirsten; Jung, Sascha; Sattler, Christian; Damerow, Helen; Weber, Judith; Kretzschmann, Annika; Cankaya, Aylin S; Piel, Markus; Rösch, Frank; Haugaard, Anne S; Frølund, Bente; Schirmeister, Tanja; Lüddens, Hartmut

2018-03-08

δ-Selective compounds 1 and 2 (DS1, compound 22; DS2, compound 16) were introduced as functionally selective modulators of δ-containing GABA type A receptors (GABA A R). In our hands, [ 3 H]EBOB-binding experiments with recombinant GABA A R and compound 22 showed no proof of δ-selectivity, although there was a minimally higher preference for the α4β3δ and α6β2/3δ receptors with respect to potency. In order to delineate the structural determinants of δ preferences, we synthesized 25 derivatives of DS1 and DS2, and investigated their structure-activity relationships (SAR). Four of our derivatives showed selectivity for α6β3δ receptors (29, 38, 39, and 41). For all of them, the major factors that distinguished them from compound 22 were variations at the para-positions of their benzamide groups. However, two compounds (29 and 39), when tested in the presence of GABA, revealed effects at several additional GABA A R. The newly synthesized compounds will still serve as useful tools to investigate α6β3δ receptors.

Dopamine receptors on adrenal chromaffin cells modulate calcium uptake and catecholamine release

Energy Technology Data Exchange (ETDEWEB)

Bigornia, L; Suozzo, M; Ryan, K A; Napp, D; Schneider, A S

1988-10-01

The presence of dopamine-containing cells in sympathetic ganglia, i.e., small, intensely fluorescent cells, has been known for some time. However, the role of dopamine as a peripheral neurotransmitter and its mechanism of action are not well understood. Previous studies have demonstrated the presence of D2 dopamine receptors on the surface of bovine adrenal chromaffin cells using radioligand binding methods and dopamine receptor inhibition of catecholamine release from perfused adrenal glands. In the present study, we provide evidence confirming a role of dopamine receptors as inhibitory modulators of adrenal catecholamine release from bovine chromaffin cell cultures and further show that the mechanism of modulation involves inhibition of stimulated calcium uptake. Apomorphine gave a dose-dependent inhibition (IC50 = 1 microM) of 45Ca2+ uptake stimulated by either nicotine (10 microM) or membrane depolarization with an elevated K+ level (60 mM). This inhibition was reversed by a series of specific (including stereospecific) dopamine receptor antagonists: haloperidol, spiperone, sulpiride, and (+)-butaclamol, but not (-)-butaclamol. In addition, the calcium channel agonist Bay K 8644 was used to stimulate uptake of 45Ca2+ into chromaffin cells, and this uptake was also inhibited by the dopamine receptor agonist apomorphine. The combined results suggest that dopamine receptors on adrenal chromaffin cells alter Ca2+ channel conductance, which, in turn, modulates catecholamine release.

Adenosine A₁ and A₂A receptor-mediated modulation of acetylcholine release in the mice neuromuscular junction.

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Garcia, Neus; Priego, Mercedes; Obis, Teresa; Santafe, Manel M; Tomàs, Marta; Besalduch, Nuria; Lanuza, M Angel; Tomàs, Josep

2013-07-01

Immunocytochemistry shows that purinergic receptors (P1Rs) type A1 and A2A (A1 R and A2 A R, respectively) are present in the nerve endings at the P6 and P30 Levator auris longus (LAL) mouse neuromuscular junctions (NMJs). As described elsewhere, 25 μm adenosine reduces (50%) acetylcholine release in high Mg(2+) or d-tubocurarine paralysed muscle. We hypothesize that in more preserved neurotransmission machinery conditions (blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB) the physiological role of the P1Rs in the NMJ must be better observed. We found that the presence of a non-selective P1R agonist (adenosine) or antagonist (8-SPT) or selective modulators of A1 R or A2 A R subtypes (CCPA and DPCPX, or CGS-21680 and SCH-58261, respectively) does not result in any changes in the evoked release. However, P1Rs seem to be involved in spontaneous release (miniature endplate potentials MEPPs) because MEPP frequency is increased by non-selective block but decreased by non-selective stimulation, with A1 Rs playing the main role. We assayed the role of P1Rs in presynaptic short-term plasticity during imposed synaptic activity (40 Hz for 2 min of supramaximal stimuli). Depression is reduced by micromolar adenosine but increased by blocking P1Rs with 8-SPT. Synaptic depression is not affected by the presence of selective A1 R and A2 A R modulators, which suggests that both receptors need to collaborate. Thus, A1 R and A2 A R might have no real effect on neuromuscular transmission in resting conditions. However, these receptors can conserve resources by limiting spontaneous quantal leak of acetylcholine and may protect synaptic function by reducing the magnitude of depression during repetitive activity. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Resveratrol modulates the inflammatory response via an estrogen receptor-signal integration network

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Nwachukwu, Jerome C; Srinivasan, Sathish; Bruno, Nelson E; Parent, Alexander A; Hughes, Travis S; Pollock, Julie A; Gjyshi, Olsi; Cavett, Valerie; Nowak, Jason; Garcia-Ordonez, Ruben D; Houtman, René; Griffin, Patrick R; Kojetin, Douglas J; Katzenellenbogen, John A; Conkright, Michael D; Nettles, Kendall W

2014-01-01

Resveratrol has beneficial effects on aging, inflammation and metabolism, which are thought to result from activation of the lysine deacetylase, sirtuin 1 (SIRT1), the cAMP pathway, or AMP-activated protein kinase. In this study, we report that resveratrol acts as a pathway-selective estrogen receptor-α (ERα) ligand to modulate the inflammatory response but not cell proliferation. A crystal structure of the ERα ligand-binding domain (LBD) as a complex with resveratrol revealed a unique perturbation of the coactivator-binding surface, consistent with an altered coregulator recruitment profile. Gene expression analyses revealed significant overlap of TNFα genes modulated by resveratrol and estradiol. Furthermore, the ability of resveratrol to suppress interleukin-6 transcription was shown to require ERα and several ERα coregulators, suggesting that ERα functions as a primary conduit for resveratrol activity. DOI: http://dx.doi.org/10.7554/eLife.02057.001 PMID:24771768

NPY2-receptor variation modulates iconic memory processes.

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Arning, Larissa; Stock, Ann-Kathrin; Kloster, Eugen; Epplen, Jörg T; Beste, Christian

2014-08-01

Sensory memory systems are modality-specific buffers that comprise information about external stimuli, which represent the earliest stage of information processing. While these systems have been the subject of cognitive neuroscience research for decades, little is known about the neurobiological basis of sensory memory. However, accumulating evidence suggests that the glutamatergic system and systems influencing glutamatergic neural transmission are important. In the current study we examine if functional promoter variations in neuropeptide Y (NPY) and its receptor gene NPY2R affect iconic memory processes using a partial report paradigm. We found that iconic memory decayed much faster in individuals carrying the rare promoter NPY2R G allele which is associated with increased expression of the Y2 receptor. Possibly this effect is due to altered presynaptic inhibition of glutamate release, known to be modulated by Y2 receptors. Altogether, our results provide evidence that the functionally relevant single nucleotide polymorphism (SNP) in the NPY2R promoter gene affect circumscribed processes of early sensory processing, i.e. only the stability of information in sensory memory buffers. This leads us to suggest that especially the stability of information in sensory memory buffers depends on glutamatergic neural transmission and factors modulating glutamatergic turnover. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

Efficient modulation of γ-aminobutyric acid type A receptors by piperine derivatives.

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Schöffmann, Angela; Wimmer, Laurin; Goldmann, Daria; Khom, Sophia; Hintersteiner, Juliane; Baburin, Igor; Schwarz, Thomas; Hintersteininger, Michael; Pakfeifer, Peter; Oufir, Mouhssin; Hamburger, Matthias; Erker, Thomas; Ecker, Gerhard F; Mihovilovic, Marko D; Hering, Steffen

2014-07-10

Piperine activates TRPV1 (transient receptor potential vanilloid type 1 receptor) receptors and modulates γ-aminobutyric acid type A receptors (GABAAR). We have synthesized a library of 76 piperine analogues and analyzed their effects on GABAAR by means of a two-microelectrode voltage-clamp technique. GABAAR were expressed in Xenopus laevis oocytes. Structure-activity relationships (SARs) were established to identify structural elements essential for efficiency and potency. Efficiency of piperine derivatives was significantly increased by exchanging the piperidine moiety with either N,N-dipropyl, N,N-diisopropyl, N,N-dibutyl, p-methylpiperidine, or N,N-bis(trifluoroethyl) groups. Potency was enhanced by replacing the piperidine moiety by N,N-dibutyl, N,N-diisobutyl, or N,N-bistrifluoroethyl groups. Linker modifications did not substantially enhance the effect on GABAAR. Compound 23 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dipropyl-2,4-pentadienamide] induced the strongest modulation of GABAA (maximal GABA-induced chloride current modulation (IGABA-max = 1673% ± 146%, EC50 = 51.7 ± 9.5 μM), while 25 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dibutyl-2,4-pentadienamide] displayed the highest potency (EC50 = 13.8 ± 1.8 μM, IGABA-max = 760% ± 47%). Compound 23 induced significantly stronger anxiolysis in mice than piperine and thus may serve as a starting point for developing novel GABAAR modulators.

Dose-dependent EEG effects of zolpidem provide evidence for GABA(A) receptor subtype selectivity in vivo.

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Visser, S A G; Wolters, F L C; van der Graaf, P H; Peletier, L A; Danhof, M

2003-03-01

Zolpidem is a nonbenzodiazepine GABA(A) receptor modulator that binds in vitro with high affinity to GABA(A) receptors expressing alpha(1) subunits but with relatively low affinity to receptors expressing alpha(2), alpha(3), and alpha(5) subunits. In the present study, it was investigated whether this subtype selectivity could be detected and quantified in vivo. Three doses (1.25, 5, and 25 mg) of zolpidem were administered to rats in an intravenous infusion over 5 min. The time course of the plasma concentrations was determined in conjunction with the change in the beta-frequency range of the EEG as pharmacodynamic endpoint. The concentration-effect relationship of the three doses showed a dose-dependent maximum effect and a dose-dependent potency. The data were analyzed for one- or two-site binding using two pharmacodynamic models based on 1) the descriptive model and 2) a novel mechanism-based pharmacokinetic/pharmacodynamic (PK/PD) model for GABA(A) receptor modulators that aims to separates drug- and system-specific properties, thereby allowing the estimation of in vivo affinity and efficacy. The application of two-site models significantly improved the fits compared with one-site models. Furthermore, in contrast to the descriptive model, the mechanism-based PK/PD model yielded dose-independent estimates for affinity (97 +/- 40 and 33,100 +/- 14,800 ng x ml(-1)). In conclusion, the mechanism-based PK/PD model is able to describe and explain the observed dose-dependent EEG effects of zolpidem and suggests the subtype selectivity of zolpidem in vivo.

The selective positive allosteric M1 muscarinic receptor modulator PQCA attenuates learning and memory deficits in the Tg2576 Alzheimer's disease mouse model.

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Puri, Vanita; Wang, Xiaohai; Vardigan, Joshua D; Kuduk, Scott D; Uslaner, Jason M

2015-01-01

We have recently shown that the M1 muscarinic receptor positive allosteric modulator, PQCA, improves cognitive performance in rodents and non-human primates administered the muscarinic receptor antagonist scopolamine. The purpose of the present experiments was to characterize the effects of PQCA in a model more relevant to the disease pathology of Alzheimer's disease. Tg2576 transgenic mice that have elevated Aβ were tested in the novel object recognition task to characterize recognition memory as a function of age and treatment with the PQCA. The effects of PQCA were compared to the acetylcholinesterase inhibitor donepezil, the standard of care for Alzheimer's disease. In addition, the effect of co-administering PQCA and donepezil was evaluated. Aged Tg2576 mice demonstrated a deficit in recognition memory that was significantly attenuated by PQCA. The positive control donepezil also reversed the deficit. Furthermore, doses of PQCA and donepezil that were inactive on their own were found to improve recognition memory when given together. These studies suggest that M1 muscarinic receptor positive allosteric modulation can ameliorate memory deficits in disease relevant models of Alzheimer's disease. These data, combined with our previous findings demonstrating PQCA improves scopolamine-induced cognitive deficits in both rodents and non-human primates, suggest that M1 positive allosteric modulators have therapeutic potential for the treatment of Alzheimer's disease. Copyright © 2015 Elsevier B.V. All rights reserved.

Modulation of BCR Signaling by the Induced Dimerization of Receptor-Associated SYK

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Mark L. Westbroek

2017-12-01

Full Text Available Clustering of the B cell antigen receptor (BCR by polyvalent antigens is transmitted through the SYK tyrosine kinase to the activation of multiple intracellular pathways that determine the physiological consequences of receptor engagement. To explore factors that modulate the quantity and quality of signals sent by the crosslinked BCR, we developed a novel chemical mediator of dimerization to induce clustering of receptor-associated SYK. To accomplish this, we fused SYK with E. coli dihydrofolate reductase (eDHFR, which binds the small molecule trimethoprim (TMP with high affinity and selectivity and synthesized a dimer of TMP with a flexible linker. The TMP dimer is able to induce the aggregation of eDHFR-linked SYK in live cells. The induced dimerization of SYK bound to the BCR differentially regulates the activation of downstream transcription factors, promoting the activation of Nuclear Factor of Activated T cells (NFAT without affecting the activation of NFκB. The dimerization of SYK enhances the duration but not the amplitude of calcium mobilization by enhancing the extent and duration of its interaction with the crosslinked BCR at the plasma membrane.

Characteristics of spectro-temporal modulation frequency selectivity in humans.

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Oetjen, Arne; Verhey, Jesko L

2017-03-01

There is increasing evidence that the auditory system shows frequency selectivity for spectro-temporal modulations. A recent study of the authors has shown spectro-temporal modulation masking patterns that were in agreement with the hypothesis of spectro-temporal modulation filters in the human auditory system [Oetjen and Verhey (2015). J. Acoust. Soc. Am. 137(2), 714-723]. In the present study, that experimental data and additional data were used to model this spectro-temporal frequency selectivity. The additional data were collected to investigate to what extent the spectro-temporal modulation-frequency selectivity results from a combination of a purely temporal amplitude-modulation filter and a purely spectral amplitude-modulation filter. In contrast to the previous study, thresholds were measured for masker and target modulations with opposite directions, i.e., an upward pointing target modulation and a downward pointing masker modulation. The comparison of this data set with previous corresponding data with the same direction from target and masker modulations indicate that a specific spectro-temporal modulation filter is required to simulate all aspects of spectro-temporal modulation frequency selectivity. A model using a modified Gabor filter with a purely temporal and a purely spectral filter predicts the spectro-temporal modulation masking data.

β adrenergic receptor modulation of neurotransmission to cardiac vagal neurons in the nucleus ambiguus.

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Bateman, R J; Boychuk, C R; Philbin, K E; Mendelowitz, D

2012-05-17

β-adrenergic receptors are a class of G protein-coupled receptors that have essential roles in regulating heart rate, blood pressure, and other cardiorespiratory functions. Although the role of β adrenergic receptors in the peripheral nervous system is well characterized, very little is known about their role in the central nervous system despite being localized in many brain regions involved in autonomic activity and regulation. Since parasympathetic activity to the heart is dominated by cardiac vagal neurons (CVNs) originating in the nucleus ambiguus (NA), β adrenergic receptors localized in the NA represent a potential target for modulating cardiac vagal activity and heart rate. This study tests the hypothesis that activation of β adrenergic receptors alters the membrane properties and synaptic neurotransmission to CVNs. CVNs were identified in brainstem slices, and membrane properties and synaptic events were recorded using the whole-cell voltage-clamp technique. The nonselective β agonist isoproterenol significantly decreased inhibitory GABAergic and glycinergic as well as excitatory glutamatergic neurotransmission to CVNs. In addition, the β(1)-selective receptor agonist dobutamine, but not β(2) or β(3) receptor agonists, significantly decreased inhibitory GABAergic and glycinergic and excitatory glutamatergic neurotransmission to CVNs. These decreases in neurotransmission to CVNs persisted in the presence of tetrodotoxin (TTX). These results provide a mechanism by which activation of adrenergic receptors in the brainstem can alter parasympathetic activity to the heart. Likely physiological roles for this adrenergic receptor activation are coordination of parasympathetic-sympathetic activity and β receptor-mediated increases in heart rate upon arousal. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

A study of time- and sex-dependent effects of vortioxetine on rat sexual behavior: Possible roles of direct receptor modulation.

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Li, Yan; Pehrson, Alan L; Oosting, Ronald S; Gulinello, Maria; Olivier, Berend; Sanchez, Connie

2017-07-15

Treatment-related sexual dysfunction is a common side effect of antidepressants and contributes to patient non-compliance or treatment cessation. However, the multimodal antidepressant, vortioxetine, demonstrates low sexual side effects in depressed patients. To investigate the mechanisms involved, sexual behavior was assessed in male and female rats after acute, and repeated (7 and 14 days) treatment with vortioxetine, flesinoxan (a 5-HT 1A receptor agonist), CP-94253 (a 5-HT 1B receptor agonist), or ondansetron (a 5-HT 3 receptor antagonist). These selective ligands were chosen to simulate vortioxetine's direct modulation of these receptors. Paroxetine was also included in the male study. Acute and repeated treatment with vortioxetine at doses corresponding to clinical levels (based on serotonin transporter occupancy) had minimal effects on sexual behavior in male and female rats. High dose vortioxetine plus flesinoxan (to mimic predicted clinical levels of 5-HT 1A receptor occupancy by vortioxetine) facilitated male rat sexual behavior (acutely) while inhibiting female rat proceptive behavior (both acutely and after 14 days treatment). The selective serotonin reuptake inhibitor, paroxetine, inhibited male sexual behavior after repeated administration (7 and 14 days). Flesinoxan alone facilitated male sexual behavior acutely while inhibiting female rat proceptive behavior after repeated administration (7 and 14 days). CP-94253 inhibited sexual behavior in both male and female rats after repeated administration. Ondansetron had no effect on sexual behavior. These findings underline the complex serotonergic regulation of sexual behavior and indicate that the low sexual side effects of vortioxetine found in clinical studies are likely associated with its direct modulation of serotonin receptors. Copyright © 2017. Published by Elsevier Ltd.

A selective androgen receptor modulator that reduces prostate tumor size and prevents orchidectomy-induced bone loss in rats.

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Allan, George; Lai, Muh-Tsann; Sbriscia, Tifanie; Linton, Olivia; Haynes-Johnson, Donna; Bhattacharjee, Sheela; Dodds, Robert; Fiordeliso, James; Lanter, James; Sui, Zhihua; Lundeen, Scott

2007-01-01

The pharmacological activity of JNJ-26146900 is described. JNJ-26146900 is a nonsteroidal androgen receptor (AR) ligand with tissue-selective activity in rats. The compound was evaluated in in vitro and in vivo models of AR activity. It binds to the rat AR with a K(i) of 400nM and acts as a pure androgen antagonist in an in vitro cell-based assay. Its in vitro profile is similar to the androgen antagonist bicalutamide (Casodex). In intact rats, JNJ-26146900 reduces ventral prostate weight with an oral potency (ED(50)) of 20-30mg/kg, again comparable to that of bicalutamide. JNJ-26146900 prevented prostate tumor growth in the Dunning rat model, maximally inhibiting growth at a dose of 10mg/kg. It slowed tumor growth significantly in a CWR22-LD1 mouse xenograft model of human prostate cancer. It was tested in aged male rats for its ability to prevent bone loss and loss of lean body mass following orchidectomy. After 6 weeks of dosing, bone volume decreased by 33% in orchidectomized versus intact vehicle-treated rats with a probability (P) of less than 0.05, as measured by micro-computerized tomography analysis. At a dose of 30mg/kg, JNJ-26146900 significantly reduced castration-induced tibial bone loss as indicated by the following parameters: bone volume, trabecular connectivity, trabecular number and spacing between trabeculae. Bone mineral density decreased from 229+/-34mg/cm(3) of hydroxyapatite to 166+/-26mg/cm(3) following orchidectomy, and was maintained at 194+/-20mg/cm(3) with JNJ-26146900 treatment (Pselective androgen receptor modulators (SARMs) have the potential for anabolic effects on bone and muscle while maintaining therapeutic efficacy in prostate cancer.

Identification of selected in vitro generated phase-I metabolites of the steroidal selective androgen receptor modulator MK-0773 for doping control purposes.

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Lagojda, Andreas; Kuehne, Dirk; Krug, Oliver; Thomas, Andreas; Wigger, Tina; Karst, Uwe; Schänzer, Wilhelm; Thevis, Mario

2016-01-01

Research into developing anabolic agents for various therapeutic purposes has been pursued for decades. As the clinical utility of anabolic-androgenic steroids has been found to be limited because of their lack of tissue selectivity and associated off-target effects, alternative drug entities have been designed and are commonly referred to as selective androgen receptor modulators (SARMs). While most of these SARMs are of nonsteroidal structure, the drug candidate MK-0773 comprises a 4-aza-steroidal nucleus. Besides the intended therapeutic use, SARMs have been found to be illicitly distributed and misused as doping agents in sport, necessitating frequently updated doping control analytical assays. As steroidal compounds reportedly undergo considerable metabolic transformations, the phase-I metabolism of MK-0773 was simulated using human liver microsomal (HLM) preparations and electrochemical conversion. Subsequently, major metabolic products were identified and characterized employing liquid chromatography-high-resolution/high- accuracy tandem mass spectrometry with electrospray (ESI) and atmospheric pressure chemical ionization (APCI) as well as nuclear magnetic resonance (NMR) spectroscopy. MK-0773 produced numerous phase-I metabolites under the chosen in vitro incubation reactions, mostly resulting from mono- and bisoxygenation of the steroid. HLM yielded at least 10 monooxygenated species, while electrochemistry-based experiments resulted predominantly in three monohydroxylated metabolites. Elemental composition data and product ion mass spectra were generated for these analytes, ESI/APCI measurements corroborated the formation of at least two N-oxygenated metabolites, and NMR data obtained from electrochemistry-derived products supported structures suggested for three monohydroxylated compounds. Hereby, the hydroxylation of the A-ring located N- bound methyl group was found to be of particular intensity. In the absence of controlled elimination studies, the

Corticotropin-Releasing Factor Receptors Modulate Oxytocin Release in the Dorsolateral Bed Nucleus of the Stria Terminalis (BNST in Male Rats

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Daisy Martinon

2018-03-01

Full Text Available The neuropeptide oxytocin (OT plays an important role in the regulation of social and anxiety-like behavior. Our previous studies have shown that OT neurons send projections from the hypothalamus to the dorsolateral bed nucleus of the stria terminalis (BNSTdl, a forebrain region critically involved in the modulation of anxiety-like behavior. Importantly, these OT terminals in the BNSTdl express presynaptic corticotropin releasing factor (CRF receptor type 2 (CRFR2. This suggests that CRFR2 might be involved in the modulation of OT release. To test this hypothesis, we measured OT content in microdialysates collected from the BNSTdl of freely-moving male Sprague-Dawley rats following the administration of a selective CRFR2 agonist (Urocortin 3 or antagonist (Astressin 2B, As2B. To determine if type 1 CRF receptors (CRFR1 are also involved, we used selective CRFR1 antagonist (NBI35965 as well as CRF, a putative ligand of both CRFR1 and CRFR2. All compounds were delivered directly into the BNSTdl via reverse dialysis. OT content in the microdialysates was measured with highly sensitive and selective radioimmunoassay. Blocking CRFR2 with As2B caused an increase in OT content in BNSTdl microdialysates, whereas CRFR2 activation by Urocortin 3 did not have an effect. The As2B-induced increase in OT release was blocked by application of the CRFR1 antagonist demonstrating that the effect was dependent on CRFR1 transmission. Interestingly, CRF alone caused a delayed increase in OT content in BNSTdl microdialysates, which was dependent on CRF2 but not CRF1 receptors. Our results suggest that members of the CRF peptide family modulate OT release in the BNSTdl via a fine-tuned mechanism that involves both CRFR1 and CRFR2. Further exploration of mechanisms by which endogenous OT system is modulated by CRF peptide family is needed to better understand the role of these neuropeptides in the regulation of anxiety and the stress response.

Modeling the Effect of the Selective S1P1 Receptor Modulator Ponesimod on Subsets of Blood Lymphocytes.

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Lott, Dominik; Krause, Andreas; Seemayer, Christian A; Strasser, Daniel S; Dingemanse, Jasper; Lehr, Thorsten

2017-03-01

This analysis aimed at describing the effect of the selective sphingosine-1-phosphate receptor 1 modulator ponesimod on lymphocyte subsets in peripheral blood. As the involvement of different lymphocyte subsets varies among different autoimmune diseases, characterizing the effect of ponesimod on these may be beneficial in better understanding treatment effects. Three phase 1 clinical studies in healthy human subjects were pooled. Non-linear mixed-effects modeling techniques were used to study the effect of ponesimod on lymphocyte subsets such as B cells, T helper cells, T cytotoxic cells, and natural killer cells in a qualitative and quantitative manner. Indirect-response I max models including circadian variation best described the effect of ponesimod on lymphocyte subsets. B cells and T helper cells were shown to be more affected compared to T cytotoxic cells with respect to the maximum possible reduction (100% for B and T helper cells, 95% for T cytotoxic cells) and the concentration required to reach half the maximum effect. Inter-individual variability was found to be larger for T cytotoxic compared to T helper, and B cells. These first models for ponesimod on the level of lymphocyte subsets offer a valuable tool for the analysis and interpretation of results from ponesimod trials in autoimmune diseases.

Identification of novel selective V2 receptor non-peptide agonists.

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Del Tredici, Andria L; Vanover, Kim E; Knapp, Anne E; Bertozzi, Sine M; Nash, Norman R; Burstein, Ethan S; Lameh, Jelveh; Currier, Erika A; Davis, Robert E; Brann, Mark R; Mohell, Nina; Olsson, Roger; Piu, Fabrice

2008-10-30

Peptides with agonist activity at the vasopressin V(2) receptor are used clinically to treat fluid homeostasis disorders such as polyuria and central diabetes insipidus. Of these peptides, the most commonly used is desmopressin, which displays poor bioavailability as well as potent activity at the V(1b) receptor, with possible stress-related adverse effects. Thus, there is a strong need for the development of small molecule chemistries with selective V(2) receptor agonist activity. Using the functional cell-based assay Receptor Selection and Amplification Technology (R-SAT((R))), a screening effort identified three small molecule chemotypes (AC-94544, AC-88324, and AC-110484) with selective agonist activity at the V(2) receptor. One of these compounds, AC-94544, displayed over 180-fold selectivity at the V(2) receptor compared to related vasopressin and oxytocin receptors and no activity at 28 other G protein-coupled receptors (GPCRs). All three compounds also showed partial agonist activity at the V(2) receptor in a cAMP accumulation assay. In addition, in a rat model of central diabetes insipidus, AC-94544 was able to significantly reduce urine output in a dose-dependent manner. Thus, AC-94544, AC-88324, and AC-110484 represent novel opportunities for the treatment of disorders associated with V(2) receptor agonist deficiency.

The Role of Cannabinoid Receptors in the Descending Modulation of Pain

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Francesco Rossi

2010-08-01

Full Text Available The endogenous antinociceptive descending pathway represents a circuitry of the supraspinal central nervous system whose task is to counteract pain. It includes the periaqueductal grey (PAG-rostral ventromedial medulla (RVM-dorsal horn (DH axis, which is the best characterized pain modulation system through which pain is endogenously inhibited. Thus, an alternative rational strategy for silencing pain is the activation of this anatomical substrate. Evidence of the involvement of cannabinoid receptors (CB in the supraspinal modulation of pain can be found in several studies in which intra-cerebral microinjections of cannabinoid ligands or positive modulators have proved to be analgesic in different pain models, whereas cannabinoid receptor antagonists or antisense nucleotides towards CB1 receptors have facilitated pain. Like opioids, cannabinoids produce centrally-mediated analgesia by activating a descending pathway which includes PAG and its projection to downstream RVM neurons, which in turn send inhibitory projections to the dorsal horn of the spinal cord. Indeed, several studies underline a supraspinal regulation of cannabinoids on g-aminobutyric acid (GABA and glutamate release which inhibit and enhance the antinociceptive descending pathway, respectively. Cannabinoid receptor activation expressed on presynaptic GABAergic terminals reduces the probability of neurotransmitter release thus dis-inhibiting the PAG-RVM-dorsal horn antinociceptive pathway. Cannabinoids seem to increase glutamate release (maybe as consequence of GABA decrease and to require glutamate receptor activation to induce antinociception. The consequent outcome is behavioral analgesia, which is reproduced in several pain conditions, from acute to chronic pain models such as inflammatory and neuropathic pain. Taken together these findings would suggest that supraspinal cannabinoid receptors have broad applications, from pain control to closely related central nervous system

The cognition-enhancing activity of E1R, a novel positive allosteric modulator of sigma-1 receptors

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Zvejniece, L; Vavers, E; Svalbe, B; Vilskersts, R; Domracheva, I; Vorona, M; Veinberg, G; Misane, I; Stonans, I; Kalvinsh, I; Dambrova, M

2014-01-01

Background and Purpose Here, we describe the in vitro and in vivo effects of (4R,5S)-2-(5-methyl-2-oxo-4-phenyl-pyrrolidin-1-yl)-acetamide (E1R), a novel positive allosteric modulator of sigma-1 receptors. Experimental Approach E1R was tested for sigma receptor binding activity in a [3H](+)-pentazocine assay, in bradykinin (BK)-induced intracellular Ca2+ concentration ([Ca2+]i) assays and in an electrically stimulated rat vas deferens model. E1R's effects on cognitive function were tested using passive avoidance (PA) and Y-maze tests in mice. A selective sigma-1 receptor antagonist (NE-100), was used to study the involvement of the sigma-1 receptor in the effects of E1R. The open-field test was used to detect the effects of E1R on locomotion. Key Results Pretreatment with E1R enhanced the selective sigma-1 receptor agonist PRE-084's stimulating effect during a model study employing electrically stimulated rat vasa deferentia and an assay measuring the BK-induced [Ca2+]i increase. Pretreatment with E1R facilitated PA retention in a dose-related manner. Furthermore, E1R alleviated the scopolamine-induced cognitive impairment during the PA and Y-maze tests in mice. The in vivo and in vitro effects of E1R were blocked by treatment with the selective sigma-1 receptor antagonist NE-100. E1R did not affect locomotor activity. Conclusion and Implications E1R is a novel 4,5-disubstituted derivative of piracetam that enhances cognition and demonstrates efficacy against scopolamine-induced cholinergic dysfunction in mice. These effects are attributed to its positive modulatory action on the sigma-1 receptor and this activity may be relevant when developing new drugs for treating cognitive symptoms related to neurodegenerative diseases. PMID:24490863

MicroRNA-219 modulates NMDA receptor-mediated neurobehavioral dysfunction

DEFF Research Database (Denmark)

Kocerha, Jannet; Faghihi, Mohammad Ali; Lopez-Toledano, Miguel A

2009-01-01

significantly modulated behavioral responses associated with disrupted NMDA receptor transmission. Furthermore, pretreatment with the antipsychotic drugs haloperidol and clozapine prevented dizocilpine-induced effects on miR-219. Taken together, these data support an integral role for miR-219 in the expression...

Structure of the Human Dopamine D3 Receptor in Complex with a D2/D3 Selective Antagonist

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Chien, Ellen Y.T.; Liu, Wei; Zhao, Qiang; Katritch, Vsevolod; Han, Gye Won; Hanson, Michael A.; Shi, Lei; Newman, Amy Hauck; Javitch, Jonathan A.; Cherezov, Vadim; Stevens, Raymond C. (Cornell); (Scripps); (NIDA); (Columbia); (UCSD); (Receptos)

2010-11-30

Dopamine modulates movement, cognition, and emotion through activation of dopamine G protein-coupled receptors in the brain. The crystal structure of the human dopamine D3 receptor (D3R) in complex with the small molecule D2R/D3R-specific antagonist eticlopride reveals important features of the ligand binding pocket and extracellular loops. On the intracellular side of the receptor, a locked conformation of the ionic lock and two distinctly different conformations of intracellular loop 2 are observed. Docking of R-22, a D3R-selective antagonist, reveals an extracellular extension of the eticlopride binding site that comprises a second binding pocket for the aryl amide of R-22, which differs between the highly homologous D2R and D3R. This difference provides direction to the design of D3R-selective agents for treating drug abuse and other neuropsychiatric indications.

Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism

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2015-10-01

AWARD NUMBER: W81XWH-13-1-0144 TITLE: Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism PRINCIPAL INVESTIGATOR...SUBTITLE 5a. CONTRACT NUMBER Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism 5b. GRANT NUMBER W81XWH-13-1-0144 5c...ABSTRACT Autism spectrum disorder (ASD) is a polygenic signaling disorder that may result, in part, from an imbalance in excitatory and inhibitory

Studying cerebellar circuits by remote control of selected neuronal types with GABA-A receptors

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William Wisden

2009-12-01

Full Text Available Although GABA-A receptor-mediated inhibition of cerebellar Purkinje cells by molecular layer interneurons (MLIs has been studied intensely on the cellular level, it has remained unclear how this inhibition regulates cerebellum-dependent behaviour. We have implemented two complementary approaches to investigate the function of the MLI-Purkinje cell synapse on the behavioral level. In the first approach we permanently disrupted inhibitory fast synaptic transmission at the synapse by genetically removing the postsynaptic GABA-A receptors from Purkinje cells (PC-Δγ2 mice. We found that chronic disruption of the MLI-Purkinje cell synapse strongly impaired cerebellar learning of the vestibular occular reflex (VOR, presumably by disrupting the temporal patterns of Purkinje cell activity. However, in PC-Δγ2 mice the baseline VOR reflex was only mildly affected; indeed PC-Δγ2 mice showed no ataxia or gait abnormalities suggesting that MLI control of Purkinje cell activity is either not involved in ongoing motor tasks or that the system has found a way to compensate for its loss. To investigate the latter possibility we have developed an alternative genetic technique; we made the MLI-Purkinje cell synapse selectively sensitive to rapid manipulation with the GABAA receptor modulator zolpidem (PC-γ2-swap mice. Minutes after intraperitoneal zolpidem injection, these PC-γ2-swap mice developed severe motor abnormalities, revealing a substantial contribution of the MLI-Purkinje cell synapse to real time motor control. The cell-type selective permanent knockout of synaptic GABAergic input, and the fast reversible modulation of GABAergic input at the same synapse illustrate how pursuing both strategies gives a fuller view.

Adenosine A2A Receptor Modulates the Activity of Globus Pallidus Neurons in Rats

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Hui-Ling Diao

2017-11-01

Full Text Available The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.

Positive modulation of delta-subunit containing GABAA receptors in mouse neurons

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Vardya, Irina; Hoestgaard-Jensen, Kirsten; Nieto-Gonzalez, Jose Luis

2012-01-01

δ-subunit containing extrasynaptic GABA(A) receptors are potential targets for modifying neuronal activity in a range of brain disorders. With the aim of gaining more insight in synaptic and extrasynaptic inhibition, we used a new positive modulator, AA29504, of δ-subunit containing GABA(A) recep......δ-subunit containing extrasynaptic GABA(A) receptors are potential targets for modifying neuronal activity in a range of brain disorders. With the aim of gaining more insight in synaptic and extrasynaptic inhibition, we used a new positive modulator, AA29504, of δ-subunit containing GABA......(A) receptors in mouse neurons in vitro and in vivo. Whole-cell patch-clamp recordings were carried out in the dentate gyrus in mouse brain slices. In granule cells, AA29504 (1 μM) caused a 4.2-fold potentiation of a tonic current induced by THIP (1 μM), while interneurons showed a potentiation of 2.6-fold......-free environment using Ca²⁺ imaging in cultured neurons, AA29504 showed GABA(A) receptor agonism in the absence of agonist. Finally, AA29504 exerted dose-dependent stress-reducing and anxiolytic effects in mice in vivo. We propose that AA29504 potentiates δ-containing GABA(A) receptors to enhance tonic inhibition...

Amelioration of sexual behavior and motor activity deficits in a castrated rodent model with a selective androgen receptor modulator SARM-2f.

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Megumi Morimoto

Full Text Available Sarcopenia and cachexia present characteristic features of a decrease in skeletal muscle mass and strength, anorexia, and lack of motivation. Treatments for these diseases have not yet been established, although selective androgen receptor modulators (SARMs are considered as therapeutic targets. We previously reported that a novel SARM compound, SARM-2f, exhibits anabolic effect on muscles, with less stimulatory effect on prostate weight compared with testosterone, in rat Hershberger assays and cancer cachexia models. In this study, we studied the mechanism of action for SARM-2f selectivity and also assessed whether the muscle increase by this compound might lead to improvement of muscle function and physical activity. First, we examined the tissue distribution of SARM-2f. Tissue concentration was 1.2-, 1.6-, and 1.9-fold as high as the plasma concentration in the levator ani muscle, brain, and prostate, respectively. This result showed that the tissue-selective pharmacological effect did not depend on SARM-2f concentration in the tissues. The ability of SARM-2f to influence androgen receptor (AR-mediated transcriptional activation was examined by reporter assays using human normal prostate epithelial cells (PrEC and skeletal muscle cells (SKMC. SARM-2f exerted higher activity against AR in SKMC than in PrEC. Mammalian two hybrid assays showed different co-factor recruitment patterns between SARM-2f and dihydrotestosterone. Next, we studied the effect of SARM-2f on motivation and physical functions such as sexual behavior and motor activities in castrated rat or mouse models. SARM-2f restored the sexual behavior that was lost by castration in male rats. SARM-2f also increased voluntary running distance and locomotor activities. These results suggest that tissue-specific AR regulation by SARM-2f, but not tissue distribution, might account for its tissue specific androgenic effect, and that the muscle mass increase by SARM-2f leads to improvement

Design and optimization of selective azaindole amide M1 positive allosteric modulators.

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Davoren, Jennifer E; O'Neil, Steven V; Anderson, Dennis P; Brodney, Michael A; Chenard, Lois; Dlugolenski, Keith; Edgerton, Jeremy R; Green, Michael; Garnsey, Michelle; Grimwood, Sarah; Harris, Anthony R; Kauffman, Gregory W; LaChapelle, Erik; Lazzaro, John T; Lee, Che-Wah; Lotarski, Susan M; Nason, Deane M; Obach, R Scott; Reinhart, Veronica; Salomon-Ferrer, Romelia; Steyn, Stefanus J; Webb, Damien; Yan, Jiangli; Zhang, Lei

2016-01-15

Selective activation of the M1 receptor via a positive allosteric modulator (PAM) is a new approach for the treatment of the cognitive impairments associated with schizophrenia and Alzheimer's disease. A novel series of azaindole amides and their key pharmacophore elements are described. The nitrogen of the azaindole core is a key design element as it forms an intramolecular hydrogen bond with the amide N-H thus reinforcing the bioactive conformation predicted by published SAR and our homology model. Representative compound 25 is a potent and selective M1 PAM that has well aligned physicochemical properties, adequate brain penetration and pharmacokinetic (PK) properties, and is active in vivo. These favorable properties indicate that this series possesses suitable qualities for further development and studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Imidazoline2 (I2) receptor- and alpha2-adrenoceptor-mediated modulation of hypothalamic-pituitary-adrenal axis activity in control and acute restraint stressed rats.

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Finn, David P; Hudson, Alan L; Kinoshita, Hiroshi; Coventry, Toni L; Jessop, David S; Nutt, David J; Harbuz, Michael S

2004-03-01

Central noradrenaline regulates the activity of the hypothalamic-pituitary-adrenal (HPA) axis and the neuroendocrine response to stress. alpha2-adrenoceptors and imidazoline2 (I2) receptors modulate the activity of the central noradrenergic system. The present set of experiments investigated the role of alpha2-adrenoceptors and I2 receptors in the regulation of HPA axis activity under basal conditions and during exposure to the acute psychological stress of restraint. Three separate experiments were carried out in which rats were given an i.p. injection of either saline vehicle, the combined alpha2-adrenoceptor antagonist and I2 receptor ligand idazoxan (10 mg/kg), the selective I2 receptor ligand BU224 (2.5 or 10 mg/kg) or the selective alpha2-adrenoceptor antagonist RX821002 (2.5 mg/kg) with or without restraint stress. Drugs were administered immediately prior to restraint of 60 min duration. Blood was sampled pre-injection, 30, 60 and 240 min post-injection and plasma corticosterone was measured by radioimmunoassay. In experiment 1, idazoxan increased plasma corticosterone levels in naive animals and potentiated the corticosterone response to acute restraint stress. In experiment 2, BU224 administration increased plasma corticosterone levels in a dose-related manner in naive rats. The results of experiment 3 indicated that RX821002 also elevated plasma corticosterone levels in naive rats, however, only BU224 potentiated the corticosterone response to restraint stress. These studies suggest that both alpha2-adrenoceptors and I2 receptors play a role in modulating basal HPA axis activity and that I2 receptors may play a more important role than alpha2-adrenoceptors in modulating the HPA axis response to the acute psychological stress of restraint.

Functional characterization of GABAA receptor-mediated modulation of cortical neuron network activity in microelectrode array recordings

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Bader, Benjamin M; Steder, Anne; Klein, Anders Bue

2017-01-01

The numerous γ-aminobutyric acid type A receptor (GABAAR) subtypes are differentially expressed and mediate distinct functions at neuronal level. In this study we have investigated GABAAR-mediated modulation of the spontaneous activity patterns of primary neuronal networks from murine frontal...... of the information extractable from the MEA recordings offers interesting insights into the contributions of various GABAAR subtypes/subgroups to cortical network activity and the putative functional interplay between these receptors in these neurons....... cortex by characterizing the effects induced by a wide selection of pharmacological tools at a plethora of activity parameters in microelectrode array (MEA) recordings. The basic characteristics of the primary cortical neurons used in the recordings were studied in some detail, and the expression levels...

Dual orexin receptor antagonists show distinct effects on locomotor performance, ethanol interaction and sleep architecture relative to gamma-aminobutyric acid-A receptor modulators

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Andres D. Ramirez

2013-12-01

Full Text Available Dual orexin receptor antagonists (DORAs are a potential treatment for insomnia that function by blocking both the orexin 1 and orexin 2 receptors. The objective of the current study was to further confirm the impact of therapeutic mechanisms targeting insomnia on locomotor coordination and ethanol interaction using DORAs and gamma-aminobutyric acid (GABA-A receptor modulators of distinct chemical structure and pharmacologic properties in the context of sleep-promoting potential. The current study compared rat motor co-ordination after administration of DORAs, DORA-12 and almorexant, and GABA-A receptor modulators, zolpidem, eszopiclone and diazepam, alone or each in combination with ethanol. Motor performance was assessed by measuring time spent walking on a rotarod apparatus. Zolpidem, eszopiclone and diazepam (0.3–30 mg/kg administered orally [PO] impaired rotarod performance in a dose-dependent manner. Furthermore, all three GABA-A receptor modulators potentiated ethanol- (0.25–1.25 g/kg induced impairment on the rotarod. By contrast, neither DORA-12 (10–100 mg/kg, PO nor almorexant (30–300 mg/kg, PO impaired motor performance alone or in combination with ethanol. In addition, distinct differences in sleep architecture were observed between ethanol, GABA-A receptor modulators (zolpidem, eszopiclone and diazepam and DORA-12 in electroencephalogram studies in rats. These findings provide further evidence that orexin receptor antagonists have an improved motor side-effect profile compared with currently available sleep-promoting agents based on preclinical data and strengthen the rationale for further evaluation of these agents in clinical development.

Integrating medicinal chemistry, organic/combinatorial chemistry, and computational chemistry for the discovery of selective estrogen receptor modulators with Forecaster, a novel platform for drug discovery.

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Therrien, Eric; Englebienne, Pablo; Arrowsmith, Andrew G; Mendoza-Sanchez, Rodrigo; Corbeil, Christopher R; Weill, Nathanael; Campagna-Slater, Valérie; Moitessier, Nicolas

2012-01-23

As part of a large medicinal chemistry program, we wish to develop novel selective estrogen receptor modulators (SERMs) as potential breast cancer treatments using a combination of experimental and computational approaches. However, one of the remaining difficulties nowadays is to fully integrate computational (i.e., virtual, theoretical) and medicinal (i.e., experimental, intuitive) chemistry to take advantage of the full potential of both. For this purpose, we have developed a Web-based platform, Forecaster, and a number of programs (e.g., Prepare, React, Select) with the aim of combining computational chemistry and medicinal chemistry expertise to facilitate drug discovery and development and more specifically to integrate synthesis into computer-aided drug design. In our quest for potent SERMs, this platform was used to build virtual combinatorial libraries, filter and extract a highly diverse library from the NCI database, and dock them to the estrogen receptor (ER), with all of these steps being fully automated by computational chemists for use by medicinal chemists. As a result, virtual screening of a diverse library seeded with active compounds followed by a search for analogs yielded an enrichment factor of 129, with 98% of the seeded active compounds recovered, while the screening of a designed virtual combinatorial library including known actives yielded an area under the receiver operating characteristic (AU-ROC) of 0.78. The lead optimization proved less successful, further demonstrating the challenge to simulate structure activity relationship studies.

Endocrine therapy use among elderly hormone receptor-pos...

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U.S. Department of Health & Human Services — Clinical guidelines recommend that women with hormone-receptor positive breast cancer receive endocrine therapy (selective estrogen receptor modulators or aromatase...

Lipid raft integrity affects GABAA receptor, but not NMDA receptor modulation by psychopharmacological compounds.

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Nothdurfter, Caroline; Tanasic, Sascha; Di Benedetto, Barbara; Uhr, Manfred; Wagner, Eva-Maria; Gilling, Kate E; Parsons, Chris G; Rein, Theo; Holsboer, Florian; Rupprecht, Rainer; Rammes, Gerhard

2013-07-01

Lipid rafts have been shown to play an important role for G-protein mediated signal transduction and the function of ligand-gated ion channels including their modulation by psychopharmacological compounds. In this study, we investigated the functional significance of the membrane distribution of NMDA and GABAA receptor subunits in relation to the accumulation of the tricyclic antidepressant desipramine (DMI) and the benzodiazepine diazepam (Diaz). In the presence of Triton X-100, which allowed proper separation of the lipid raft marker proteins caveolin-1 and flotillin-1 from the transferrin receptor, all receptor subunits were shifted to the non-raft fractions. In contrast, under detergent-free conditions, NMDA and GABAA receptor subunits were detected both in raft and non-raft fractions. Diaz was enriched in non-raft fractions without Triton X-100 in contrast to DMI, which preferentially accumulated in lipid rafts. Impairment of lipid raft integrity by methyl-β-cyclodextrine (MβCD)-induced cholesterol depletion did not change the inhibitory effect of DMI at the NMDA receptor, whereas it enhanced the potentiating effect of Diaz at the GABAA receptor at non-saturating concentrations of GABA. These results support the hypothesis that the interaction of benzodiazepines with the GABAA receptor likely occurs outside of lipid rafts while the antidepressant DMI acts on ionotropic receptors both within and outside these membrane microdomains.

Targeting CB2-GPR55 Receptor Heteromers Modulates Cancer Cell Signaling*

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Moreno, Estefanía; Andradas, Clara; Medrano, Mireia; Caffarel, María M.; Pérez-Gómez, Eduardo; Blasco-Benito, Sandra; Gómez-Cañas, María; Pazos, M. Ruth; Irving, Andrew J.; Lluís, Carme; Canela, Enric I.; Fernández-Ruiz, Javier; Guzmán, Manuel; McCormick, Peter J.; Sánchez, Cristina

2014-01-01

The G protein-coupled receptors CB2 (CB2R) and GPR55 are overexpressed in cancer cells and human tumors. Because a modulation of GPR55 activity by cannabinoids has been suggested, we analyzed whether this receptor participates in cannabinoid effects on cancer cells. Here we show that CB2R and GPR55 form heteromers in cancer cells, that these structures possess unique signaling properties, and that modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo. These findings unveil the existence of previously unknown signaling platforms that help explain the complex behavior of cannabinoids and may constitute new targets for therapeutic intervention in oncology. PMID:24942731

Spectro-temporal modulation masking patterns reveal frequency selectivity.

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Oetjen, Arne; Verhey, Jesko L

2015-02-01

The present study investigated the possibility that the human auditory system demonstrates frequency selectivity to spectro-temporal amplitude modulations. Threshold modulation depth for detecting sinusoidal spectro-temporal modulations was measured using a generalized masked threshold pattern paradigm with narrowband masker modulations. Four target spectro-temporal modulations were examined, differing in their temporal and spectral modulation frequencies: a temporal modulation of -8, 8, or 16 Hz combined with a spectral modulation of 1 cycle/octave and a temporal modulation of 4 Hz combined with a spectral modulation of 0.5 cycles/octave. The temporal center frequencies of the masker modulation ranged from 0.25 to 4 times the target temporal modulation. The spectral masker-modulation center-frequencies were 0, 0.5, 1, 1.5, and 2 times the target spectral modulation. For all target modulations, the pattern of average thresholds for the eight normal-hearing listeners was consistent with the hypothesis of a spectro-temporal modulation filter. Such a pattern of modulation-frequency sensitivity was predicted on the basis of psychoacoustical data for purely temporal amplitude modulations and purely spectral amplitude modulations. An analysis of separability indicates that, for the present data set, selectivity in the spectro-temporal modulation domain can be described by a combination of a purely spectral and a purely temporal modulation filter function.

Contextual modulation and stimulus selectivity in extrastriate cortex.

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Krause, Matthew R; Pack, Christopher C

2014-11-01

Contextual modulation is observed throughout the visual system, using techniques ranging from single-neuron recordings to behavioral experiments. Its role in generating feature selectivity within the retina and primary visual cortex has been extensively described in the literature. Here, we describe how similar computations can also elaborate feature selectivity in the extrastriate areas of both the dorsal and ventral streams of the primate visual system. We discuss recent work that makes use of normalization models to test specific roles for contextual modulation in visual cortex function. We suggest that contextual modulation renders neuronal populations more selective for naturalistic stimuli. Specifically, we discuss contextual modulation's role in processing optic flow in areas MT and MST and for representing naturally occurring curvature and contours in areas V4 and IT. We also describe how the circuitry that supports contextual modulation is robust to variations in overall input levels. Finally, we describe how this theory relates to other hypothesized roles for contextual modulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modulation of short-term social memory in rats by adenosine A1 and A(2A) receptors.

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Prediger, Rui D S; Takahashi, Reinaldo N

2005-03-16

The recognition of an unfamiliar juvenile rat by an adult rat has been shown to imply short-term memory processes. The present study was designed to examine the role of adenosine receptors in the short-term social memory of rats using the social recognition paradigm. Adenosine (5.0-10.0 mg/kg), the selective adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA, 0.025-0.05 mg/kg) and the selective adenosine A(2A) receptor agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA, 1.0-5.0 mg/kg), given by i.p. route 30 min before the test, disrupted the juvenile recognition ability of adult rats. This negative effect of adenosine (5.0 mg/kg, i.p.) on social memory was prevented by pretreatment with the non-selective adenosine receptor antagonist caffeine (10.0 mg/kg, i.p.), the adenosine A1 antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 1.0 mg/kg, i.p.) and the adenosine A(2A) antagonist 4-(2-[7-amino-2-{2-furyl}{1,2,4}triazolo-{2,3-a}{1,3,5}triazin-5-yl-amino]ethyl)phenol (ZM241385, 1.0 mg/kg, i.p.). Furthermore, acute administration of caffeine (10.0-30.0 mg/kg, i.p.), DPCPX (1.0-3.0 mg/kg, i.p.) or ZM241385 (0.5-1.0 mg/kg, i.p.) improved the short-term social memory in a specific manner. These results indicate that adenosine modulates the short-term social memory in rats by acting on both A1 and A(2A) receptors, with adenosine receptor agonists and antagonists, respectively, disrupting and enhancing the social memory.

Adjunctive selective estrogen receptor modulator increases neural activity in the hippocampus and inferior frontal gyrus during emotional face recognition in schizophrenia.

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Ji, E; Weickert, C S; Lenroot, R; Kindler, J; Skilleter, A J; Vercammen, A; White, C; Gur, R E; Weickert, T W

2016-05-03

Estrogen has been implicated in the development and course of schizophrenia with most evidence suggesting a neuroprotective effect. Treatment with raloxifene, a selective estrogen receptor modulator, can reduce symptom severity, improve cognition and normalize brain activity during learning in schizophrenia. People with schizophrenia are especially impaired in the identification of negative facial emotions. The present study was designed to determine the extent to which adjunctive raloxifene treatment would alter abnormal neural activity during angry facial emotion recognition in schizophrenia. Twenty people with schizophrenia (12 men, 8 women) participated in a 13-week, randomized, double-blind, placebo-controlled, crossover trial of adjunctive raloxifene treatment (120 mg per day orally) and performed a facial emotion recognition task during functional magnetic resonance imaging after each treatment phase. Two-sample t-tests in regions of interest selected a priori were performed to assess activation differences between raloxifene and placebo conditions during the recognition of angry faces. Adjunctive raloxifene significantly increased activation in the right hippocampus and left inferior frontal gyrus compared with the placebo condition (family-wise error, Precognition in schizophrenia. These findings support the hypothesis that estrogen plays a modifying role in schizophrenia and shows that adjunctive raloxifene treatment may reverse abnormal neural activity during facial emotion recognition, which is relevant to impaired social functioning in men and women with schizophrenia.

Liver X Receptor Genes Variants Modulate ALS Phenotype.

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Mouzat, Kevin; Molinari, Nicolas; Kantar, Jovana; Polge, Anne; Corcia, Philippe; Couratier, Philippe; Clavelou, Pierre; Juntas-Morales, Raul; Pageot, Nicolas; Lobaccaro, Jean -Marc A; Raoul, Cedric; Lumbroso, Serge; Camu, William

2018-03-01

Amyotrophic lateral sclerosis (ALS) is one of the most severe motor neuron (MN) disorders in adults. Phenotype of ALS patients is highly variable and may be influenced by modulators of energy metabolism. Recent works have implicated the liver X receptors α and β (LXRs), either in the propagation process of ALS or in the maintenance of MN survival. LXRs are nuclear receptors activated by oxysterols, modulating cholesterol levels, a suspected modulator of ALS severity. In a cohort of 438 ALS patients and 330 healthy controls, the influence of LXR genes on ALS risk and phenotype was studied using single nucleotide polymorphisms (SNPs). The two LXRα SNPs rs2279238 and rs7120118 were shown to be associated with age at onset in ALS patients. Consistently, homozygotes were twice more correlated than were heterozygotes to delayed onset. The onset was thus delayed by 3.9 years for rs2279238 C/T carriers and 7.8 years for T/T carriers. Similar results were obtained for rs7120118 (+2.1 years and +6.7 years for T/C and C/C genotypes, respectively). The LXRβ SNP rs2695121 was also shown to be associated with a 30% increase of ALS duration (p = 0.0055, FDR = 0.044). The tested genotypes were not associated with ALS risk. These findings add further evidence to the suspected implication of LXR genes in the disease process of ALS and might open new perspectives in ALS therapeutics.

GABAA receptor positive allosteric modulators modify the abuse-related behavioral and neurochemical effects of methamphetamine in rhesus monkeys.

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Berro, Laís F; Andersen, Monica L; Tufik, Sergio; Howell, Leonard L

2017-09-01

GABA A receptor positive allosteric modulators (GABA A receptor modulators) are commonly used for the treatment of insomnia. Nevertheless, the effects of these compounds on psychostimulant-induced sleep impairment are poorly understood. Because GABA A receptor modulators have been shown to decrease the abuse-related effects of psychostimulants, the aim of the present study was to evaluate the effects of temazepam (0.3, 1.0 or 3.0 mg/kg) and eszopiclone (0.3, 1.0 or 3.0 mg/kg), two GABA A receptor modulators, on the behavioral neuropharmacology of methamphetamine in adult rhesus macaques (n = 5). Sleep-like measures and general daytime activity were evaluated with Actiwatch monitors. Methamphetamine self-administration (0.03 mg/kg/inf) was evaluated during morning sessions. Methamphetamine-induced dopamine overflow was assessed through in vivo microdialysis targeting the nucleus accumbens. Nighttime treatment with either temazepam or eszopiclone was ineffective in improving sleep-like measures disrupted by methamphetamine self-administration. Acute pretreatment with a low dose of temazepam before self-administration sessions increased methamphetamine self-administration without affecting normal daytime home-cage activity. At a high dose, acute temazepam pretreatment decreased methamphetamine self-administration and attenuated methamphetamine-induced increases in dopamine in the nucleus accumbens, without decreasing general daytime activity. Acute eszopiclone treatment exerted no effects on methamphetamine intake or drug-induced increases in dopamine. Our study suggests that treatments based on GABA A receptor modulators are not effective for the treatment of sleep disruption in the context of psychostimulant use. In addition, distinct GABA A receptor modulators differentially modulated the abuse-related effects of methamphetamine, with acute treatment with the high efficacy GABA A receptor modulator temazepam decreasing the behavioral and neurochemical effects

Structural insights into human peroxisome proliferator activated receptor delta (PPAR-delta selective ligand binding.

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Fernanda A H Batista

Full Text Available Peroxisome proliferator activated receptors (PPARs δ, α and γ are closely related transcription factors that exert distinct effects on fatty acid and glucose metabolism, cardiac disease, inflammatory response and other processes. Several groups developed PPAR subtype specific modulators to trigger desirable effects of particular PPARs without harmful side effects associated with activation of other subtypes. Presently, however, many compounds that bind to one of the PPARs cross-react with others and rational strategies to obtain highly selective PPAR modulators are far from clear. GW0742 is a synthetic ligand that binds PPARδ more than 300-fold more tightly than PPARα or PPARγ but the structural basis of PPARδ:GW0742 interactions and reasons for strong selectivity are not clear. Here we report the crystal structure of the PPARδ:GW0742 complex. Comparisons of the PPARδ:GW0742 complex with published structures of PPARs in complex with α and γ selective agonists and pan agonists suggests that two residues (Val312 and Ile328 in the buried hormone binding pocket play special roles in PPARδ selective binding and experimental and computational analysis of effects of mutations in these residues confirms this and suggests that bulky substituents that line the PPARα and γ ligand binding pockets as structural barriers for GW0742 binding. This analysis suggests general strategies for selective PPARδ ligand design.

Discovery of a novel allosteric modulator of 5-HT3 receptor

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Trattnig, Sarah M; Harpsøe, Kasper; Thygesen, Sarah B

2012-01-01

The ligand-gated ion channels in the Cysloop receptor superfamily mediate the effects of neurotransmitters acetylcholine, serotonin, GABA and glycine. Cysloop receptor signaling is susceptible to modulation by ligands acting through numerous allosteric sites. Here we report the discovery of a novel...... receptor guided by a homology model, PU02 is demonstrated to act through a transmembrane intersubunit site situated in the upper three helical turns of TM2 and TM3 in the (+)subunit and TM1 and TM2 in the (minus)subunit. The Ser248, Leu288, Ile290, Thr294 and Gly306 residues are identified as important...

Development of allosteric modulators of GPCRs for treatment of CNS disorders.

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Nickols, Hilary Highfield; Conn, P Jeffrey

2014-01-01

The discovery of allosteric modulators of G protein-coupled receptors (GPCRs) provides a promising new strategy with potential for developing novel treatments for a variety of central nervous system (CNS) disorders. Traditional drug discovery efforts targeting GPCRs have focused on developing ligands for orthosteric sites which bind endogenous ligands. Allosteric modulators target a site separate from the orthosteric site to modulate receptor function. These allosteric agents can either potentiate (positive allosteric modulator, PAM) or inhibit (negative allosteric modulator, NAM) the receptor response and often provide much greater subtype selectivity than orthosteric ligands for the same receptors. Experimental evidence has revealed more nuanced pharmacological modes of action of allosteric modulators, with some PAMs showing allosteric agonism in combination with positive allosteric modulation in response to endogenous ligand (ago-potentiators) as well as "bitopic" ligands that interact with both the allosteric and orthosteric sites. Drugs targeting the allosteric site allow for increased drug selectivity and potentially decreased adverse side effects. Promising evidence has demonstrated potential utility of a number of allosteric modulators of GPCRs in multiple CNS disorders, including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, as well as psychiatric or neurobehavioral diseases such as anxiety, schizophrenia, and addiction. © 2013.

Cancer cell-selective promoter recognition accompanies antitumor effect by glucocorticoid receptor-targeted gold nanoparticle

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Sau, Samaresh; Agarwalla, Pritha; Mukherjee, Sudip; Bag, Indira; Sreedhar, Bojja; Pal-Bhadra, Manika; Patra, Chitta Ranjan; Banerjee, Rajkumar

2014-05-01

Nanoparticles, such as gold nanoparticles (GNP), upon convenient modifications perform multi tasks catering to many biomedical applications. However, GNP or any other type of nanoparticles is yet to achieve the feat of intracellular regulation of endogenous genes of choice such as through manipulation of a gene-promoter in a chromosome. As for gene modulation and delivery, GNP (or other nanoparticles) showed only limited gene therapy potential, which relied on the delivery of `exogenous' genes invoking gene knockdown or replacement. Practically, there are no instances for the nanoparticle-mediated promoter regulation of `endogenous' genes, more so, as a cancer selective phenomenon. In this regard, we report the development of a simple, easily modifiable GNP-formulation, which promoted/up-regulated the expression of a specific category of `endogenous' genes, the glucocorticoid responsive genes. This genetic up-regulation was induced in only cancer cells by modified GNP-mediated transcriptional activation of its cytoplasmic receptor, glucocorticoid receptor (GR). Normal cells and their GR remained primarily unperturbed by this GNP-formulation. The most potent gene up-regulating GNP-formulation down-regulated a cancer-specific proliferative signal, phospho-Akt in cancer cells, which accompanied retardation of tumor growth in the murine melanoma model. We show that GR-targeted GNPs may find potential use in the targeting and modulation of genetic information in cancer towards developing novel anticancer therapeutics.Nanoparticles, such as gold nanoparticles (GNP), upon convenient modifications perform multi tasks catering to many biomedical applications. However, GNP or any other type of nanoparticles is yet to achieve the feat of intracellular regulation of endogenous genes of choice such as through manipulation of a gene-promoter in a chromosome. As for gene modulation and delivery, GNP (or other nanoparticles) showed only limited gene therapy potential, which relied

Sniffer patch laser uncaging response (SPLURgE): an assay of regional differences in allosteric receptor modulation and neurotransmitter clearance.

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Christian, Catherine A; Huguenard, John R

2013-10-01

Allosteric modulators exert actions on neurotransmitter receptors by positively or negatively altering the effective response of these receptors to their respective neurotransmitter. γ-Aminobutyric acid (GABA) type A ionotropic receptors (GABAARs) are major targets for allosteric modulators such as benzodiazepines, neurosteroids, and barbiturates. Analysis of substances that produce similar effects has been hampered by the lack of techniques to assess the localization and function of such agents in brain slices. Here we describe measurement of the sniffer patch laser uncaging response (SPLURgE), which combines the sniffer patch recording configuration with laser photolysis of caged GABA. This methodology enables the detection of allosteric GABAAR modulators endogenously present in discrete areas of the brain slice and allows for the application of exogenous GABA with spatiotemporal control without altering the release and localization of endogenous modulators within the slice. Here we demonstrate the development and use of this technique for the measurement of allosteric modulation in different areas of the thalamus. Application of this technique will be useful in determining whether a lack of modulatory effect on a particular category of neurons or receptors is due to insensitivity to allosteric modulation or a lack of local release of endogenous ligand. We also demonstrate that this technique can be used to investigate GABA diffusion and uptake. This method thus provides a biosensor assay for rapid detection of endogenous GABAAR modulators and has the potential to aid studies of allosteric modulators that exert effects on other classes of neurotransmitter receptors, such as glutamate, acetylcholine, or glycine receptors.

D1 dopamine receptor signaling is modulated by the R7 RGS protein EAT-16 and the R7 binding protein RSBP-1 in Caenoerhabditis elegans motor neurons.

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Khursheed A Wani

Full Text Available Dopamine signaling modulates voluntary movement and reward-driven behaviors by acting through G protein-coupled receptors in striatal neurons, and defects in dopamine signaling underlie Parkinson's disease and drug addiction. Despite the importance of understanding how dopamine modifies the activity of striatal neurons to control basal ganglia output, the molecular mechanisms that control dopamine signaling remain largely unclear. Dopamine signaling also controls locomotion behavior in Caenorhabditis elegans. To better understand how dopamine acts in the brain we performed a large-scale dsRNA interference screen in C. elegans for genes required for endogenous dopamine signaling and identified six genes (eat-16, rsbp-1, unc-43, flp-1, grk-1, and cat-1 required for dopamine-mediated behavior. We then used a combination of mutant analysis and cell-specific transgenic rescue experiments to investigate the functional interaction between the proteins encoded by two of these genes, eat-16 and rsbp-1, within single cell types and to examine their role in the modulation of dopamine receptor signaling. We found that EAT-16 and RSBP-1 act together to modulate dopamine signaling and that while they are coexpressed with both D1-like and D2-like dopamine receptors, they do not modulate D2 receptor signaling. Instead, EAT-16 and RSBP-1 act together to selectively inhibit D1 dopamine receptor signaling in cholinergic motor neurons to modulate locomotion behavior.

Central vasopressin V1a receptors modulate neural processing in mothers facing intruder threat to pups

OpenAIRE

Caffrey, Martha K.; Nephew, Benjamin C.; Febo, Marcelo

2009-01-01

Vasopressin V1a receptors in the rat brain have been studied for their role in modulating aggression and anxiety. In the current study blood-oxygen-level-dependent (BOLD) functional MRI was used to test whether V1a receptors modulate neural processing in the maternal brain when dams are exposed to a male intruder. Primiparous females were given an intracerebroventricular (ICV) injection of vehicle or V1a receptor antagonist ([deamino-Pen1, O-Me-Try, Arg8]-Vasopressin, 125 ng/10 μL) 90-120 min...

The metabotropic glutamate receptors: structure, activation mechanism and pharmacology.

Science.gov (United States)

Pin, Jean-Philippe; Acher, Francine

2002-06-01

The metabotropic glutamate receptors are G-protein coupled receptors (GPCR) involved in the regulation of many synapses, including most glutamatergic fast excitatory synapses. Eight subtypes have been identified that can be classified into three groups. The molecular characterization of these receptors revealed proteins much more complex than any other GPCRs. They are composed of a Venus Flytrap (VFT) module where glutamate binds, connected to a heptahelical domain responsible for G-protein coupling. Recent data including the structure of the VFT module determined with and without glutamate, indicate that these receptors function as dimers. Moreover a number of intracellular proteins can regulate their targeting and transduction mechanism. Such structural features of mGlu receptors offer multiple possibilities for synthetic compounds to modulate their activity. In addition to agonists and competitive antagonists acting at the glutamate binding site, a number of non-competitive antagonists with inverse agonist activity, and positive allosteric modulators have been discovered. These later compounds share specific properties that make them good candidates for therapeutic applications. First, their non-amino acid structure makes them pass more easily the blood brain barrier. Second, they are much more selective than any other compound identified so far, being the first subtype selective molecules. Third, for the negative modulators, their non competitive mechanism of action makes them relatively unaffected by high concentrations of glutamate that may be present in disease states (e.g. stroke, epilepsy, neuropathic pain, etc.). Fourth, like the benzodiazepines acting at the GABA(A) receptors, the positive modulators offer a new way to increase the activity of these receptors in vivo, with a low risk of inducing their desensitization. The present review article focuses on the specific structural features of these receptors and highlights the various possibilities these

Assessment of the potential activity of major dietary compounds as selective estrogen receptor modulators in two distinct cell models for proliferation and differentiation

Energy Technology Data Exchange (ETDEWEB)

Lecomte, Sylvain; Lelong, Marie; Bourgine, Gaëlle [Institut de Recherche en Santé-Environnement-Travail (IRSET), Inserm UMR 1085, Team Transcription, Environment and Cancer, University of Rennes 1, 9 Avenue du Pr Léon Bernard, 35000 Rennes (France); Efstathiou, Theo [Laboratoire Nutrinov, Technopole Atalante Champeaux, 8 rue Jules Maillard de la Gournerie, 35012 Rennes Cedex (France); Saligaut, Christian [Institut de Recherche en Santé-Environnement-Travail (IRSET), Inserm UMR 1085, Team Transcription, Environment and Cancer, University of Rennes 1, 9 Avenue du Pr Léon Bernard, 35000 Rennes (France); Pakdel, Farzad, E-mail: farzad.pakdel@univ-rennes1.fr [Institut de Recherche en Santé-Environnement-Travail (IRSET), Inserm UMR 1085, Team Transcription, Environment and Cancer, University of Rennes 1, 9 Avenue du Pr Léon Bernard, 35000 Rennes (France)

2017-06-15

Estrogen receptors (ERs) α and β are distributed in most tissues of women and men. ERs are bound by estradiol (E2), a natural hormone, and mediate the pleiotropic and tissue-specific effects of E2, such as proliferation of breast epithelial cells or protection and differentiation of neuronal cells. Numerous environmental molecules, called endocrine disrupting compounds, also interact with ERs. Phytoestrogens belong to this large family and are considered potent therapeutic molecules that act through their selective estrogen receptor modulator (SERM) activity. Using breast cancer cell lines as a model of estrogen-dependent proliferation and a stably ER-expressing PC12 cell line as a model of neuronal differentiating cells, we studied the SERM activity of major dietary compounds, such as apigenin, liquiritigenin, daidzein, genistein, coumestrol, resveratrol and zearalenone. The ability of these compounds to induce ER-transactivation and breast cancer cell proliferation and enhance Nerve Growth Factor (NGF) -induced neuritogenesis was assessed. Surprisingly, although all compounds were able to activate the ER through an estrogen responsive element reporter gene, they showed differential activity toward proliferation or differentiation. Apigenin and resveratrol showed a partial or no proliferative effect on breast cancer cells but fully contributed to the neuritogenesis effect of NGF. However, daidzein and zearalenone showed full effects on cellular proliferation but did not induce cellular differentiation. In summary, our results suggest that the therapeutic potential of phytoestrogens can diverge depending on the molecule and the phenotype considered. Hence, apigenin and resveratrol might be used in the development of therapeutics for breast cancer and brain diseases. - Highlights: • SERM activity of dietary compounds on proliferation and differentiation is studied. • All the dietary compounds tested transactivate estrogen receptors. • Apigenin and

The modulation of radiosensitivity by combined treatment of selective COX-2 inhibitor, NS 398 and EGF receptor blocker AG 1478 in HeLa cell line

International Nuclear Information System (INIS)

Youn, Seon Min; Oh, Young Kee; Kim, Joo Heon; Park, Mi Ja; Seong, In Ock; Kang, Ki Mun; Chai, Gyu Yong

2005-01-01

Selective inhibition of multiple molecular targets may improve the antitumor activity of radiation. Two specific inhibitors of selective cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) were combined with radiation on the HeLa cell line. To investigate cooperative mechanism with selective COX-2 inhibitor and EGFR blocker, in vitro experiments were done. Antitumor effect was obtained by growth inhibition and apoptosis analysis by annexin V-Flous method. Radiation modulation effects were determined by the clonogenic cell survival assay. Surviving fractions at 2 Gy (SF 2 ) and dose enhancement radio at a surviving fraction of 0.25 were evaluated. To investigate the mechanism of the modulation of radiosensitivity, the cell cycle analyses were done by flow cytometry. The bcl-2 and bax expressions were analyzed by western blot. A cooperative effect were observed on the apoptosis of the HeLa cell line when combination of the two drugs, AG 1478 and NS 398 with radiation at the lowest doses, apoptosis of 22.70% compare with combination of the one drug with radiation, apoptosis of 8.49%. In cell cycle analysis, accumulation of cell on G 0 /G 1 phase and decrement of S phase fraction was observed from 24 hours to 72 hours after treatment with radiation, AG 1478 and NS 398. The combination of NS 398 and AG 1478 enhanced radiosensitivity in a concentration-dependent manner in HeLa cells with dose enhancement ratios of 3.00 and SF 2 of 0.12 but the combination of one drug with radiation was not enhanced radiosensitivity with dose enhancement ratios of 1.12 and SF2 of 0.68 (ρ = 0.005). The expression levels of bcl-2 and bax were reduced when combined with AG 1478 and NS 398. Our results indicate that the selective COX-2 inhibitor and EGFR blocker combined with radiation have potential additive or cooperative effects on radiation treatment and may act through various mechanisms including direct inhibition of tumor cell proliferation, suppression of tumor cell

Post-translational regulation of P2X receptor channels: modulation by phospholipids

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Louis-Philippe eBernier

2013-11-01

Full Text Available P2X receptor channels mediate fast excitatory signaling by ATP and play major roles in sensory transduction, neuro-immune communication and inflammatory response. P2X receptors constitute a gene family of calcium-permeable ATP-gated cation channels therefore the regulation of P2X signaling is critical for both membrane potential and intracellular calcium homeostasis. Phosphoinositides (PIPn are anionic signaling phospholipids that act as functional regulators of many types of ion channels. Direct PIPn binding was demonstrated for several ligand- or voltage-gated ion channels, however no generic motif emerged to accurately predict lipid-protein binding sites. This review presents what is currently known about the modulation of the different P2X subtypes by phospholipids and about critical determinants underlying their sensitivity to PIPn levels in the plasma membrane.All functional mammalian P2X subtypes tested, with the notable exception of P2X5, have been shown to be positively modulated by PIPn, i.e. homomeric P2X1, P2X2, P2X3, P2X4, and P2X7, as well as heteromeric P2X1/5 and P2X2/3 receptors. Based on various results reported on the aforementioned subtypes including mutagenesis of the prototypical PIPn-sensitive P2X4 and PIPn-insensitive P2X5 receptor subtypes, an increasing amount of functional, biochemical and structural evidence converges on the modulatory role of a short polybasic domain located in the proximal C-terminus of P2X subunits. This linear motif, semi-conserved in the P2X family, seems necessary and sufficient for encoding direct modulation of ATP-gated channels by PIPn. Furthermore, the physiological impact of the regulation of ionotropic purinergic responses by phospholipids on pain pathways was recently revealed in the context of native crosstalks between phospholipase C-linked metabotropic receptors and P2X receptor channels in DRG sensory neurons and microglia.

Promiscuity and selectivity of bitter molecules and their receptors.

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Di Pizio, Antonella; Niv, Masha Y

2015-07-15

Bitter taste is essential for survival, as it protects against consuming poisonous compounds, which are often bitter. Bitter taste perception is mediated by bitter taste receptors (TAS2Rs), a subfamily of G-protein coupled receptors (GPCRs). The number of TAS2R subtypes is species-dependent, and varies from 3 in chicken to 50 in frog. TAS2Rs present an intriguing case for studying promiscuity: some of the receptors are still orphan, or have few known agonists, while others can be activated by numerous, structurally dissimilar compounds. The ligands also vary in the repertoire of TAS2Rs that they activate: some bitter compounds are selective toward a single TAS2R, while others activate multiple TAS2Rs. Selectivity/promiscuity profile of bitter taste receptors and their compounds was explored by a chemoinformatic approach. TAS2R-promiscuous and TAS2R-selective bitter molecules were found to differ in chemical features, such as AlogP, E-state, total charge, number of rings, globularity, and heavy atom count. This allowed the prediction of bitter ligand selectivity toward TAS2Rs. Interestingly, while promiscuous TAS2Rs are activated by both TAS2R-promiscuous and TAS2R-selective compounds, almost all selective TAS2Rs in human are activated by promiscuous compounds, which are recognized by other TAS2Rs anyway. Thus, unique ligands, that may have been the evolutionary driving force for development of selective TAS2Rs, still need to be unraveled. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synapse geometry and receptor dynamics modulate synaptic strength.

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Dominik Freche

Full Text Available Synaptic transmission relies on several processes, such as the location of a released vesicle, the number and type of receptors, trafficking between the postsynaptic density (PSD and extrasynaptic compartment, as well as the synapse organization. To study the impact of these parameters on excitatory synaptic transmission, we present a computational model for the fast AMPA-receptor mediated synaptic current. We show that in addition to the vesicular release probability, due to variations in their release locations and the AMPAR distribution, the postsynaptic current amplitude has a large variance, making a synapse an intrinsic unreliable device. We use our model to examine our experimental data recorded from CA1 mice hippocampal slices to study the differences between mEPSC and evoked EPSC variance. The synaptic current but not the coefficient of variation is maximal when the active zone where vesicles are released is apposed to the PSD. Moreover, we find that for certain type of synapses, receptor trafficking can affect the magnitude of synaptic depression. Finally, we demonstrate that perisynaptic microdomains located outside the PSD impacts synaptic transmission by regulating the number of desensitized receptors and their trafficking to the PSD. We conclude that geometrical modifications, reorganization of the PSD or perisynaptic microdomains modulate synaptic strength, as the mechanisms underlying long-term plasticity.

Selective ligand activity at Nur/retinoid X receptor complexes revealed by dimer-specific bioluminescence resonance energy transfer-based sensors

Science.gov (United States)

Giner, Xavier C; Cotnoir-White, David; Mader, Sylvie; Lévesque, Daniel

2017-01-01

Retinoid X receptors (RXR) play a role as master regulators due to their capacity to form heterodimers with other nuclear receptors. Accordingly, retinoid signaling is involved in multiple biological processes, including development, cell differentiation, metabolism and cell death. However, the role and functions of RXR in different heterodimer complexes remain unsolved, mainly because most RXR drugs (called rexinoids) are not selective to specific heterodimer complexes. This also strongly limits the use of rexinoids for specific therapeutic approaches. In order to better characterize rexinoids at specific nuclear receptor complexes, we have developed and optimized luciferase protein complementation-based Bioluminescence Resonance Energy Transfer (BRET) assays, which can directly measure recruitment of a co-activator motif fused to yellow fluorescent protein (YFP) by specific nuclear receptor dimers. To validate the assays, we compared rexinoid modulation of co-activator recruitment by RXR homodimer, and heterodimers Nur77/RXR and Nurr1/RXR. Results reveal that some rexinoids display selective co-activator recruitment activities with homo- or hetero-dimer complexes. In particular, SR11237 (BMS649) has increased potency for recruitment of co-activator motif and transcriptional activity with the Nur77/RXR heterodimer compared to other complexes. This technology should prove useful to identify new compounds with specificity for individual dimeric species formed by nuclear receptors. PMID:26148973

5-HT7 Receptor Antagonists with an Unprecedented Selectivity Profile.

Science.gov (United States)

Ates, Ali; Burssens, Pierre; Lorthioir, Olivier; Lo Brutto, Patrick; Dehon, Gwenael; Keyaerts, Jean; Coloretti, Francis; Lallemand, Bénédicte; Verbois, Valérie; Gillard, Michel; Vermeiren, Céline

2018-04-23

Selective leads: In this study, we generated a new series of serotonin 5-HT 7 receptor antagonists. Their synthesis, structure-activity relationships, and selectivity profiles are reported. This series includes 5-HT 7 antagonists with unprecedented high selectivity for the 5-HT 7 receptor, setting the stage for lead optimization of drugs acting on a range of neurological targets. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Getting a Handle on Neuropharmacology by Targeting Receptor-Associated Proteins.

Science.gov (United States)

Maher, Michael P; Matta, Jose A; Gu, Shenyan; Seierstad, Mark; Bredt, David S

2017-12-06

Targeted therapy for neuropsychiatric disorders requires selective modulation of dysfunctional neuronal pathways. Receptors relevant to CNS disorders typically have associated proteins discretely expressed in specific neuronal pathways; these accessory proteins provide a new dimension for drug discovery. Recent studies show that targeting a TARP auxiliary subunit of AMPA receptors selectively modulates neuronal excitability in specific forebrain pathways relevant to epilepsy. Other medicinally important ion channels, gated by glutamate, γ-aminobutyric acid (GABA), and acetylcholine, also have associated proteins, which may be druggable. This emerging pharmacology of receptor-associated proteins provides a new approach for improving drug efficacy while mitigating side effects. Copyright © 2017 Elsevier Inc. All rights reserved.

Bitropic D3 Dopamine Receptor Selective Compounds as Potential Antipsychotics.

Science.gov (United States)

Luedtke, Robert R; Rangel-Barajas, Claudia; Malik, Mahinder; Reichert, David E; Mach, R H

2015-01-01

Neuropsychiatric disorders represent a substantial social and health care issue. The National Institutes of Health estimates that greater than 2 million adults suffer from neuropsychiatric disorders in the USA. These individuals experience symptoms that can include auditory hallucinations, delusions, unrealistic beliefs and cognitive dysfunction. Although antipsychotic medications are available, suboptimal therapeutic responses are observed for approximately one-third of patients. Therefore, there is still a need to explore new pharmacotherapeutic strategies for the treatment of neuropsychiatric disorders. Many of the medications that are used clinically to treat neuropsychiatric disorders have a pharmacological profile that includes being an antagonist at D2-like (D2, D3 and D4) dopamine receptor subtypes. However, dopamine receptor subtypes are involved in a variety of neuronal circuits that include movement coordination, cognition, emotion, affect, memory and the regulation of prolactin. Consequently, antagonism at D2-like receptors can also contribute to some of the adverse side effects associated with the long-term use of antipsychotics including the a) adverse extrapyramidal symptoms associated with the use of typical antipsychotics and b) metabolic side effects (weight gain, hyperglycemia, increased risk of diabetes mellitus, dyslipidemia and gynecomastia) associated with atypical antipsychotic use. Preclinical studies suggest that D3 versus D2 dopamine receptor selective compounds might represent an alternative strategy for the treatment of the symptoms of schizophrenia. In this review we discuss a) how bitropic Nphenylpiperazine D3 dopamine receptor selective compounds have been developed by modification of the primary (orthosteric) and secondary (allosteric or modulatory) pharmacophores to optimize D3 receptor affinity and D2/D3 binding selectivity ratios and b) the functional selectivity of these compounds. Examples of how these compounds might be

Differential Potency of 2,6-Dimethylcyclohexanol Isomers for Positive Modulation of GABAA Receptor Currents.

Science.gov (United States)

Chowdhury, Luvana; Croft, Celine J; Goel, Shikha; Zaman, Naina; Tai, Angela C-S; Walch, Erin M; Smith, Kelly; Page, Alexandra; Shea, Kevin M; Hall, C Dennis; Jishkariani, D; Pillai, Girinath G; Hall, Adam C

2016-06-01

GABAA receptors meet all of the pharmacological requirements necessary to be considered important targets for the action of general anesthetic agents in the mammalian brain. In the following patch-clamp study, the relative modulatory effects of 2,6-dimethylcyclohexanol diastereomers were investigated on human GABAA (α1β3γ2s) receptor currents stably expressed in human embryonic kidney cells. Cis,cis-, trans,trans-, and cis,trans-isomers were isolated from commercially available 2,6-dimethylcyclohexanol and were tested for positive modulation of submaximal GABA responses. For example, the addition of 30 μM cis,cis-isomer resulted in an approximately 2- to 3-fold enhancement of the EC20 GABA current. Coapplications of 30 μM 2,6-dimethylcyclohexanol isomers produced a range of positive enhancements of control GABA responses with a rank order for positive modulation: cis,cis > trans,trans ≥ mixture of isomers > > cis,trans-isomer. In molecular modeling studies, the three cyclohexanol isomers bound with the highest binding energies to a pocket within transmembrane helices M1 and M2 of the β3 subunit through hydrogen-bonding interactions with a glutamine at the 224 position and a tyrosine at the 220 position. The energies for binding to and hydrogen-bond lengths within this pocket corresponded with the relative potencies of the agents for positive modulation of GABAA receptor currents (cis,cis > trans,trans > cis,trans-2,6-dimethylcyclohexanol). In conclusion, the stereochemical configuration within the dimethylcyclohexanols is an important molecular feature in conferring positive modulation of GABAA receptor activity and for binding to the receptor, a consideration that needs to be taken into account when designing novel anesthetics with enhanced therapeutic indices. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Chimeric RXFP1 and RXFP2 receptors highlight the similar mechanism of activation utilizing their N-terminal low density lipoprotein class A modules

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Shoni eBruell

2013-11-01

Full Text Available Relaxin family peptide (RXFP receptors 1 and 2 are unique G-protein coupled receptors in that they contain an N-terminal low density lipoprotein type A (LDLa module which is necessary for receptor activation. The current hypothesis suggests that upon ligand binding the LDLa module interacts with the transmembrane (TM domain of a homodimer partner receptor to induce the active receptor conformations. We recently demonstrated that three residues in the N-terminus of the RXFP1 LDLa module are potentially involved in hydrophobic interactions with the receptor to drive activation. RXFP2 shares two out of three of the residues implicated, suggesting that the two LDLa modules could be interchanged without adversely affecting activity. However, in 2007 it was shown that a chimera consisting of the RXFP1 receptor with its LDLa swapped for that of RXFP2 did not signal. We noticed this construct also contained the RXFP2 region linking the LDLa to the leucine-rich repeats. We therefore constructed chimeric RXFP1 and RXFP2 receptors with their LDLa modules swapped immediately C-terminally to the final cysteine residue of the module, retaining the native linker. In addition, we exchanged the TM domains of the chimeras to explore if matching the LDLa module with the TM domain of its native receptor altered activity. All of the chimeras were expressed at the surface of HEK293T cells with ligand binding profiles similar to the wild-type receptors. Importantly, as predicted, ligand binding was able to induce cAMP based signalling. Chimeras of RXFP1 with the LDLa of RXFP2 demonstrated reduced H2 relaxin potency with the pairing of the RXFP2 TM with the RXFP2 LDLa necessary for full ligand efficacy. In contrast the ligand mediated potencies and efficacies on the RXFP2 chimeras were similar suggesting the RXFP1 LDLa module has similar efficacy on the RXFP2 TM domain. Our studies demonstrate the LDLa modules of RXFP1 and RXFP2 modulate receptor activation via a

Determination and confirmation of selective estrogen receptor modulators (SERMs), anti-estrogens and aromatase inhibitors in bovine and porcine urine using UHPLC-MS/MS.

Science.gov (United States)

Meijer, Thijs; Essers, Martien L; Kaklamanos, George; Sterk, Saskia S; van Ginkel, Leendert A

2017-04-01

Selective estrogen receptor modulators (SERMs), anti-estrogens and aromatase inhibitors are prohibited in human sports doping. However, they also present a risk of being used illegally in animal husbandry for fattening purposes. A method was developed and validated using UHPLC-MS/MS for the determination and confirmation of SERMs, anti-estrogens and aromatase inhibiters in bovine and porcine urine. This method was used in a survey of more than 200 bovine and porcine urine samples from Dutch farms. In 18 out of 103 porcine urine samples (17%) and two out of 114 bovine samples (2%) formestane, an aromatase inhibitor, was detected. None of the other compounds was detected. From human doping control it is known that formestane can, in some cases, be of natural origin. Analyses of reference samples from untreated bovine and porcine animals demonstrated the presence of formestane in bovine animals, but not yet in porcine animals. Future research will focus on whether the detected formestane in porcine and bovine urine is from endogenous or exogenous origin, using GC-c-IRMS.

Single channel speech enhancement in the modulation domain: New insights in the modulation channel selection framework

DEFF Research Database (Denmark)

Boldt, Jesper B.; Bertelsen, Andreas Thelander; Gran, Fredrik

2015-01-01

Recently, the ideal binary mask has been introduced in the modulation domain by extending the ideal channel selection method to modulation channel selection [1]. This new method shows substantial improvement in speech intelligibility but less than its predecessor despite the higher complexity. Here......, we extend the previous finding from [1] and provide a more direct comparison of binary masking in the modulation domain with binary masking in the time-frequency domain. Subjective and objective evaluations are performed and provide additional insight into modulation domain processing....

Contraceptive applications of progesterone receptor modulators.

Science.gov (United States)

Chabbert-Buffet, Nathalie; Ouzounian, Sophie; Kairis, Axelle Pintiaux; Bouchard, Philippe

2008-09-01

Currently developed progesterone receptor modulators (PRMs) are steroid-derived compounds with mild or potent antiprogestin activity. PRMs may exert a contraceptive activity by different mechanisms such as blockade of ovulation and endometrial desynchronization. Their potential clinical applications are manifold and are very promising in major public health areas, including emergency contraception, long term oestrogen-free contraception (administered alone, or in association with a progestin-only pill to improve bleeding patterns), endometriosis and myoma treatment. The mechanisms of their anti-ovulatory effects and of the endometrial modifications elicited during long term PRM treatment are still not fully elucidated. In future clinical applications, PRMs will be administered orally, via intrauterine systems or vaginal rings.

The association of metabotropic glutamate receptor type 5 with the neuronal Ca2+-binding protein 2 modulates receptor function.

Science.gov (United States)

Canela, Laia; Fernández-Dueñas, Víctor; Albergaria, Catarina; Watanabe, Masahiko; Lluís, Carme; Mallol, Josefa; Canela, Enric I; Franco, Rafael; Luján, Rafael; Ciruela, Francisco

2009-10-01

Metabotropic glutamate (mGlu) receptors mediate in part the CNS effects of glutamate. These receptors interact with a large array of intracellular proteins in which the final role is to regulate receptor function. Here, using co-immunoprecipitation and pull-down experiments we showed a close and specific interaction between mGlu(5) receptor and NECAB2 in both transfected human embryonic kidney cells and rat hippocampus. Interestingly, in pull-down experiments increasing concentrations of calcium drastically reduced the ability of these two proteins to interact, suggesting that NECAB2 binds to mGlu(5) receptor in a calcium-regulated manner. Immunoelectron microscopy detection of NECAB2 and mGlu(5) receptor in the rat hippocampal formation indicated that both proteins are codistributed in the same subcellular compartment of pyramidal cells. In addition, the NECAB2/mGlu(5) receptor interaction regulated mGlu(5b)-mediated activation of both inositol phosphate accumulation and the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway. Overall, these findings indicate that NECAB2 by its physical interaction with mGlu(5b) receptor modulates receptor function.

NMDA receptor modulation by dextromethorphan and acute stress selectively alters electroencephalographic indicators of partial report processing.

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Weckesser, Lisa J; Enge, Sören; Riedel, Philipp; Kirschbaum, Clemens; Miller, Robert

2017-10-01

Proceeding from a biophysical network model, the present study hypothesized that glutamatergic neurotransmission across the NMDA receptor (NMDAR) plays a key role in visual perception and its modulation by acute stress. To investigate these hypotheses, behavioral and electroencephalographic (EEG) indicators of partial report task processing were assessed in twenty-four healthy young men who randomly received a non-competitive NMDAR antagonist (0.8 mg/kg dextromethorphan, DXM) or a placebo, and concurrently accomplished a stress-induction (MAST) or control protocol in three consecutive sessions. Saliva samples served to quantify cortisol responses to the MAST, whereas a passive auditory oddball paradigm was implemented to verify the impact of DXM on the EEG-derived mismatch negativity component (MMN). DXM administration significantly increased MMN amplitudes but not salivary cortisol concentrations. By contrast, concurrent MAST exposure significantly reduced MMN latencies but also increased cortisol concentrations. With regard to EEG indicators, DXM administration reduced visually "evoked" (30Hz to 50Hz) and "induced" occipital gamma-band activity (70Hz to 100Hz), which was partly compensated by additional MAST exposure. However, neither the interventions nor EEG activity were significantly associated with behavioral partial report sensitivities. In summary, the present data suggest that glutamatergic neurotransmission across the NMDAR is only one among many determinants of intact visual perception. Accordingly, therapeutic doses of DXM and their inhibitory modulation by stress probably yield more pronounced electroencephalographic as compared with behavioural effects. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

Differential modulation of Beta-adrenergic receptor signaling by trace amine-associated receptor 1 agonists.

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Gunnar Kleinau

Full Text Available Trace amine-associated receptors (TAAR are rhodopsin-like G-protein-coupled receptors (GPCR. TAAR are involved in modulation of neuronal, cardiac and vascular functions and they are potentially linked with neurological disorders like schizophrenia and Parkinson's disease. Subtype TAAR1, the best characterized TAAR so far, is promiscuous for a wide set of ligands and is activated by trace amines tyramine (TYR, phenylethylamine (PEA, octopamine (OA, but also by thyronamines, dopamine, and psycho-active drugs. Unfortunately, effects of trace amines on signaling of the two homologous β-adrenergic receptors 1 (ADRB1 and 2 (ADRB2 have not been clarified yet in detail. We, therefore, tested TAAR1 agonists TYR, PEA and OA regarding their effects on ADRB1/2 signaling by co-stimulation studies. Surprisingly, trace amines TYR and PEA are partial allosteric antagonists at ADRB1/2, whereas OA is a partial orthosteric ADRB2-antagonist and ADRB1-agonist. To specify molecular reasons for TAAR1 ligand promiscuity and for observed differences in signaling effects on particular aminergic receptors we compared TAAR, tyramine (TAR octopamine (OAR, ADRB1/2 and dopamine receptors at the structural level. We found especially for TAAR1 that the remarkable ligand promiscuity is likely based on high amino acid similarity in the ligand-binding region compared with further aminergic receptors. On the other hand few TAAR specific properties in the ligand-binding site might determine differences in ligand-induced effects compared to ADRB1/2. Taken together, this study points to molecular details of TAAR1-ligand promiscuity and identified specific trace amines as allosteric or orthosteric ligands of particular β-adrenergic receptor subtypes.

Increased excitability of spinal pain reflexes and altered frequency-dependent modulation in the dopamine D3-receptor knockout mouse.

Science.gov (United States)

Keeler, Benjamin E; Baran, Christine A; Brewer, Kori L; Clemens, Stefan

2012-12-01

Frequency-dependent modulation and dopamine (DA) receptors strongly modulate neural circuits in the spinal cord. Of the five known DA receptor subtypes, the D3 receptor has the highest affinity to DA, and D3-mediated actions are mainly inhibitory. Using an animal model of spinal sensorimotor dysfunction, the D3 receptor knockout mouse (D3KO), we investigated the physiological consequences of D3 receptor dysfunction on pain-associated signaling pathways in the spinal cord, the initial integration site for the processing of pain signaling. In the D3KO spinal cord, inhibitory actions of DA on the proprioceptive monosynaptic stretch reflex are converted from depression to facilitation, but its effects on longer-latency and pain-associated reflex responses and the effects of FM have not been studied. Using behavioral approaches in vivo, we found that D3KO animals exhibit reduced paw withdrawal latencies to thermal pain stimulation (Hargreaves' test) over wild type (WT) controls. Electrophysiological and pharmacological approaches in the isolated spinal cord in vitro showed that constant current stimulation of dorsal roots at a pain-associated frequency was associated with a significant reduction in the frequency-dependent modulation of longer-latency reflex (LLRs) responses but not monosynaptic stretch reflexes (MSRs) in D3KO. Application of the D1 and D2 receptor agonists and the voltage-gated calcium-channel ligand, pregabalin, but not DA, was able to restore the frequency-dependent modulation of the LLR in D3KO to WT levels. Thus we demonstrate that nociception-associated LLRs and proprioceptive MSRs are differentially modulated by frequency, dopaminergics and the Ca(2+) channel ligand, pregabalin. Our data suggest a role for the DA D3 receptor in pain modulation and identify the D3KO as a possible model for increased nociception. Copyright © 2012 Elsevier Inc. All rights reserved.

Detection of the arylpropionamide-derived selective androgen receptor modulator (SARM) S-4 (Andarine) in a black-market product.

Science.gov (United States)

Thevis, Mario; Geyer, Hans; Kamber, Matthias; Schänzer, Wilhelm

2009-08-01

Non-steroidal and tissue-selective anabolic agents such as selective androgen receptor modulators (SARMs) represent a promising class of therapeutics for the treatment of various diseases such as sarcopenia or cancer cachexia. Advanced compounds of SARMs are based on an arylpropionamide-derived structure and leading drug candidates have successfully completed phase-II-clinical trials. Although none of these therapeutics have been approved, their performance-enhancing qualities and the black-market availability of these products makes them a viable target for misuse in the athletic community. In 2008, SARMs were added to the Prohibited List established by the World Anti-Doping Agency (WADA). That SARMs are the subject of misuse even without clinical approval was proved for the first time by the detection of the drug candidate Andarine (also referred to as S-4, S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide), advertised, sold and supplied via the Internet. The oily liquids, declared as green tea extracts and face moisturizer, were assayed using state-of-the-art analytical procedures and S-4 was found at concentrations of approximately 150 mg/mL. The authenticity of the product was demonstrated in comparison to reference material by liquid chromatography, high resolution/high accuracy (tandem) mass spectrometry using positive and negative electrospray ionization, and comparison to reference material. Moreover, an impurity resulting from poor product purification was detected, accounting for approximately 10% of S-4. This consisted of 2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-3-(4-nitro-3-trifluoromethyl-phenylamino)-propionamide. The ease of purchasing non-approved drug candidates that could potentially increase athletic performance demonstrates the need to operate proactively in the continued fight against doping. The early inclusion of emerging drugs into routine sports drug testing procedures is a key

[On the role of selective silencer Freud-1 in the regulation of the brain 5-HT(1A) receptor gene expression].

Science.gov (United States)

Naumenko, V S; Osipova, D V; Tsybko, A S

2010-01-01

Selective 5-HT(1A) receptor silencer (Freud-1) is known to be one of the main factors for transcriptional regulation of brain serotonin 5-HT(1A) receptor. However, there is a lack of data on implication of Freud-1 in the mechanisms underlying genetically determined and experimentally altered 5-HT(1A) receptor system state in vivo. In the present study we have found a difference in the 5-HT(1A) gene expression in the midbrain of AKR and CBA inbred mouse strains. At the same time no distinction in Freud-1 expression was observed. We have revealed 90.3% of homology between mouse and rat 5-HT(1A) receptor DRE-element, whereas there was no difference in DRE-element sequence between AKR and CBA mice. This indicates the absence of differences in Freud-1 binding site in these mouse strains. In the model of 5-HT(1A) receptor desensitization produced by chronic 5-HT(1A) receptor agonist administration, a significant reduction of 5-HT(1A) receptor gene expression together with considerable increase of Freud-1 expression were found. These data allow us to conclude that the selective silencer of 5-HT(1A) receptor, Freud-1, is involved in the compensatory mechanisms that modulate the functional state of brain serotonin system, although it is not the only factor for 5-HT(1A) receptor transcriptional regulation.

Modifications and additions to selected TOUGH2 modules

International Nuclear Information System (INIS)

Wu, Y.S.; Mishra, A.K.

1998-01-01

The purpose of this report is to provide all software baseline documents necessary for the software qualification of the revised versions of the selected TOUGH2 modules, which include single-phase gas (EOS1G), effective continuum method (EOS3/ECM), saturated/unsaturated flow (EOS9), and radionuclide transport (T2R3D) modules of the TOUGH2 code. TOUGH2 is a numerical simulation code for multi-dimensional, coupled fluid and heat flow of multiphase, multicomponent fluid mixtures in porous and fractured media. This report augments the document Software Qualification of Selected TOUGH2 modules. This report contains the following sections: (1) requirement specifications and code development and (2) software validation test plan and results. These sections comprise sequential parts of Software Lifecycle, and should be used in conjunction with the TOUGH User's Guide, TOUGH2 documentation, TOUGH2 Software Qualification, and Software Qualification of Selected TOUGH2 modules. The version of TOUGH2 used with the software being qualified herein is the October 1996 Standard Version 1.2, as qualified in Wu et al. (1996) and housed at the Department of Energy's Energy Science and Technology Software Center (ESTSC) in Oak Ridge, Tennessee

The AMPA receptor potentiator Org 26576 modulates stress-induced transcription of BDNF isoforms in rat hippocampus.

Science.gov (United States)

Fumagalli, Fabio; Calabrese, Francesca; Luoni, Alessia; Shahid, Mohammed; Racagni, Giorgio; Riva, Marco A

2012-02-01

Brain derived neurotrophic factor (BDNF) is a key mediator of brain plasticity. The modulation of its expression and function is important for cognition and represents a key strategy to enhance neuronal resilience. Within this context, there exists a close interaction between glutamatergic neurotransmission and BDNF activity towards regulating cellular homeostasis and plasticity. The aim of the current study was to investigate the ability of the AMPA receptor potentiator Org 26576 to modulate BDNF expression in selected brain regions under basal conditions or in response to an acute swim stress. Rats subjected to a single intraperitoneal injection with Org 26576 (10mg/kg) or saline were exposed to a swim stress session (5 min) and sacrificed 15 min after the end of stress. Real-time PCR assay was used to determine changes in BDNF transcription in different brain regions. Total BDNF mRNA levels were significantly increased in the hippocampus of animals exposed to the combination of Org 26576 and stress whereas, in prefrontal and frontal cortices, BDNF mRNA levels were modulated by the acute stress, independently from drug treatment. The analysis of BDNF transcripts in the hippocampus revealed a major contribution of exons I and IV. Our results suggest that AMPA receptor potentiation by Org 26576 exerts a positive modulatory influence on BDNF expression during ongoing neuronal activity. Given that these mechanisms are critical for neuronal plasticity, we hypothesized that such changes may facilitate learning/coping mechanisms associated with a mild stressful experience. Copyright © 2011 Elsevier Ltd. All rights reserved.

Transmembrane potential polarization, calcium influx, and receptor conformational state modulate the sensitivity of the imidacloprid-insensitive neuronal insect nicotinic acetylcholine receptor to neonicotinoid insecticides.

Science.gov (United States)

Bodereau-Dubois, Béatrice; List, Olivier; Calas-List, Delphine; Marques, Olivier; Communal, Pierre-Yves; Thany, Steeve H; Lapied, Bruno

2012-05-01

Neonicotinoid insecticides act selectively on insect nicotinic acetylcholine receptors (nAChRs). Recent studies revealed that their efficiency was altered by the phosphorylation/dephosphorylation process and the intracellular signaling pathway involved in the regulation of nAChRs. Using whole-cell patch-clamp electrophysiology adapted for dissociated cockroach dorsal unpaired median (DUM) neurons, we demonstrated that intracellular factors involved in the regulation of nAChR function modulated neonicotinoid sensitivity. DUM neurons were known to express two α-bungarotoxin-insensitive nAChR subtypes: nAChR1 and nAChR2. Whereas nAChR1 was sensitive to imidacloprid, nAChR2 was insensitive to this insecticide. Here, we demonstrated that, like nicotine, acetamiprid and clothianidin, other types of neonicotinoid insecticides, acted as agonists on the nAChR2 subtype. Using acetamiprid, we revealed that both steady-state depolarization and hyperpolarization affected nAChR2 sensitivity. The measurement of the input membrane resistance indicated that change in the acetamiprid-induced agonist activity was related to the receptor conformational state. Using cadmium chloride, ω-conotoxin GVIA, and (R,S)-(3,4-dihydro-6,7-dimethoxy-isoquinoline-1-yl)-2-phenyl-N,N-di-acetamide (LOE 908), we found that inhibition of calcium influx through high voltage-activated calcium channels and transient receptor potential γ (TRPγ) activated by both depolarization and hyperpolarization increased nAChR2 sensitivity to acetamiprid. Finally, using N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W7), forskolin, and cAMP, we demonstrated that adenylyl cyclase sensitive to the calcium/calmodulin complex regulated internal cAMP concentration, which in turn modulated TRPγ function and nAChR2 sensitivity to acetamiprid. Similar TRPγ-induced modulatory effects were also obtained when clothianidin was tested. These findings bring insights into the signaling pathway modulating

Partial agonists and subunit selectivity at NMDA receptors

DEFF Research Database (Denmark)

Risgaard, Rune; Hansen, Kasper Bø; Clausen, Rasmus Prætorius

2010-01-01

Subunit-selective ligands for glutamate receptors remains an area of interest as glutamate is the major excitatory neurotransmitter in the brain and involved in a number of diseased states in the central nervous system (CNS). Few subtype-selective ligands are known, especially among the N...

Levamisole: A Positive Allosteric Modulator for the α3β4 Nicotinic Acetylcholine Receptors Prevents Weight Gain in the CD-1 Mice on a High Fat Diet.

Science.gov (United States)

Lewis, Jeanne A; Yakel, Jerrel L; Pandya, Anshul A

2017-01-01

Neuronal nicotinic acetylcholine receptors (nAChRs) regulate the function of multiple neurotransmitter pathways throughout the central nervous system. This includes nAChRs found on the proopiomelanocortin neurons in the hypothalamus. Activation of these nAChRs by nicotine causes a decrease in the consumption of food in rodents. This study tested the effect of subtype selective allosteric modulators for nAChRs on the body weight of CD-1 mice. Levamisole, an allosteric modulator for the α3β4 subtype of nAChRs, prevented weight gain in mice that were fed a high fat diet. PNU-120596 and desformylflustrabromine were observed to be selective PAMs for the α7 and α4β2 nAChR, respectively. Both of these compounds failed to prevent weight gain in the CD-1 mice. These results suggest that the modulation of hypothalamic α3β4 nAChRs is an important factor in regulating food intake, and the PAMs for these receptors need further investigation as potential therapeutic agents for controlling weight gain. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Ketamine and other glutamate receptor modulators for depression in adults.

Science.gov (United States)

Caddy, Caroline; Amit, Ben H; McCloud, Tayla L; Rendell, Jennifer M; Furukawa, Toshi A; McShane, Rupert; Hawton, Keith; Cipriani, Andrea

2015-09-23

, mild-moderate depression. Nine studies recruited only treatment-resistant patients.We rated the risk of bias as low or unclear for most domains, though lack of detail regarding masking of treatment in the studies reduced our certainty in the effect for all outcomes. We rated three studies as having high risk for selective outcome reporting. Many trials did not provide information on all the prespecified outcomes and we found no data, or very limited data, on very important issues like suicidality, cognition, quality of life, costs to healthcare services and dropouts due to lack of efficacy.Among all glutamate receptor modulators, only ketamine (administered intravenously) proved to be more efficacious than placebo, though the quality of evidence was limited by risk of bias and small sample sizes. There was low quality evidence that treatment with ketamine increased the likelihood of response after 24 hours (odds ratio (OR) 10.77, 95% confidence interval (CI) 2.00 to 58.00; 3 RCTs, 56 participants), 72 hours (OR 12.59, 95% CI 2.38 to 66.73; 3 RCTs, 56 participants), and one week (OR 2.58, 95% CI 1.08 to 6.16; 4 RCTs, 131 participants). The effect of ketamine was even less certain at two weeks, as data were available from only one trial (OR 0.93, 95% CI 0.31 to 2.83; 51 participants, low quality evidence). This was consistent across all efficacy outcomes. Ketamine caused more confusion and emotional blunting compared to placebo. There was insufficient evidence to determine if this increased the likelihood of leaving the study early (OR 1.90, 95% CI 0.43 to 8.47; 5 RCTs, 139 participants, low quality evidence).One RCT with 72 participants reported higher numbers of responders on ketamine than midazolam at 24 hours (OR 0.36, 95% CI 0.14 to 0.58), 72 hours (OR 0.37, 95% CI 0.16 to 0.59), and one week (OR 0.29, 95% CI 0.08 to 0.49). However, midazolam was better tolerated than ketamine in terms of blurred vision, dizziness, general malaise and nausea/vomiting at 24 hours

Prenylated isoflavonoids from plants as selective estrogen receptor modulators (phytoSERMs)

NARCIS (Netherlands)

Simons, R.; Gruppen, H.; Bovee, T.F.H.; Verbruggen, M.A.; Vincken, J.P.

2012-01-01

Isoflavonoids are a class of secondary metabolites, which comprise amongst others the subclasses of isoflavones, isoflavans, pterocarpans and coumestans. Isoflavonoids are abundant in Leguminosae, and many of them can bind to the human estrogen receptor (hER) with affinities similar to or lower than

Negative modulation of the GABAA ρ1 receptor function by l-cysteine.

Science.gov (United States)

Beltrán González, Andrea N; Vicentini, Florencia; Calvo, Daniel J

2018-01-01

l-Cysteine is an endogenous sulfur-containing amino acid with multiple and varied roles in the central nervous system, including neuroprotection and the maintenance of the redox balance. However, it was also suggested as an excitotoxic agent implicated in the pathogenesis of neurological disorders such as Parkinson's and Alzheimer's disease. l-Cysteine can modulate the activity of ionic channels, including voltage-gated calcium channels and glutamatergic NMDA receptors, whereas its effects on GABAergic neurotransmission had not been studied before. In the present work, we analyzed the effects of l-cysteine on responses mediated by homomeric GABA A ρ1 receptors, which are known for mediating tonic γ-aminobutyric acid (GABA) responses in retinal neurons. GABA A ρ1 receptors were expressed in Xenopus laevis oocytes and GABA-evoked chloride currents recorded by two-electrode voltage-clamp in the presence or absence of l-cysteine. l-Cysteine antagonized GABA A ρ1 receptor-mediated responses; inhibition was dose-dependent, reversible, voltage independent, and susceptible to GABA concentration. Concentration-response curves for GABA were shifted to the right in the presence of l-cysteine without a substantial change in the maximal response. l-Cysteine inhibition was insensitive to chemical protection of the sulfhydryl groups of the ρ1 subunits by the irreversible alkylating agent N-ethyl maleimide. Our results suggest that redox modulation is not involved during l-cysteine actions and that l-cysteine might be acting as a competitive antagonist of the GABA A ρ1 receptors. © 2017 International Society for Neurochemistry.

Cyclic cholecystokinin analogues with high selectivity for central receptors

International Nuclear Information System (INIS)

Charpentier, B.; Pelaprat, D.; Durieux, C.; Dor, A.; Roques, B.P.; Reibaud, M.; Blanchard, J.C.

1988-01-01

Taking as a model the N-terminal folding of the cholecystokinin tyrosine-sulfated octapeptide deduced from conformational studies, two cyclic cholecystokinin (CCK) analogues were synthesized by conventional peptide synthesis. The binding characteristics of these peptides were investigated on brain cortex membranes and pancreatic acini of guinea pig. Compounds I and II were competitive inhibitors of [ 3 H]Boc[Ahx 28,31 ]CCK-(27-33) binding to central CCK receptors and showed a high degree of selectivity for these binding sites. This high selectivity was associated with a high affinity for central CCK receptors. Similar affinities and selectivities were found when 125 I Bolton-Hunter-labeled CCK-8 was used as a ligand. Moreover, these compounds were only weakly active in the stimulation of amylase release from guinea pig pancreatic acini and were unable to induce contractions in the guinea pig ileum. The two cyclic CCK analogues, therefore, appear to be synthetic ligands exhibiting both high affinity and high selectivity for central CCK binding sites. These compounds could help clarify the respective role of central and peripheral receptors for various CCK-8-induced pharmacological effects

The modulation of radiosensitivity by combined treatment of selective COX-2 inhibitor, NS 398 and EGF receptor blocker AG 1478 in HeLa cell line

Energy Technology Data Exchange (ETDEWEB)

Youn, Seon Min; Oh, Young Kee; Kim, Joo Heon; Park, Mi Ja; Seong, In Ock [Eulji University School of Medicine, Daejeon (Korea, Republic of); Kang, Ki Mun; Chai, Gyu Yong [Gyeongsang National University College of Medicine, Jinju (Korea, Republic of)

2005-03-15

Selective inhibition of multiple molecular targets may improve the antitumor activity of radiation. Two specific inhibitors of selective cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) were combined with radiation on the HeLa cell line. To investigate cooperative mechanism with selective COX-2 inhibitor and EGFR blocker, in vitro experiments were done. Antitumor effect was obtained by growth inhibition and apoptosis analysis by annexin V-Flous method. Radiation modulation effects were determined by the clonogenic cell survival assay. Surviving fractions at 2 Gy (SF{sub 2}) and dose enhancement radio at a surviving fraction of 0.25 were evaluated. To investigate the mechanism of the modulation of radiosensitivity, the cell cycle analyses were done by flow cytometry. The bcl-2 and bax expressions were analyzed by western blot. A cooperative effect were observed on the apoptosis of the HeLa cell line when combination of the two drugs, AG 1478 and NS 398 with radiation at the lowest doses, apoptosis of 22.70% compare with combination of the one drug with radiation, apoptosis of 8.49%. In cell cycle analysis, accumulation of cell on G{sub 0}/G{sub 1} phase and decrement of S phase fraction was observed from 24 hours to 72 hours after treatment with radiation, AG 1478 and NS 398. The combination of NS 398 and AG 1478 enhanced radiosensitivity in a concentration-dependent manner in HeLa cells with dose enhancement ratios of 3.00 and SF{sub 2} of 0.12 but the combination of one drug with radiation was not enhanced radiosensitivity with dose enhancement ratios of 1.12 and SF2 of 0.68 ({rho} = 0.005). The expression levels of bcl-2 and bax were reduced when combined with AG 1478 and NS 398. Our results indicate that the selective COX-2 inhibitor and EGFR blocker combined with radiation have potential additive or cooperative effects on radiation treatment and may act through various mechanisms including direct inhibition of tumor cell proliferation

Monovalent cation and amiloride analog modulation of adrenergic ligand binding to the unglycosylated alpha 2B-adrenergic receptor subtype

International Nuclear Information System (INIS)

Wilson, A.L.; Seibert, K.; Brandon, S.; Cragoe, E.J. Jr.; Limbird, L.E.

1991-01-01

The unglycosylated alpha 2B subtype of the alpha 2-adrenergic receptor found in NG-108-15 cells possesses allosteric regulation of adrenergic ligand binding by monovalent cations and 5-amino-substituted amiloride analogs. These findings demonstrate that allosteric modulation of adrenergic ligand binding is not a property unique to the alpha 2A subtype. The observation that amiloride analogs as well as monovalent cations can modulate adrenergic ligand binding to the nonglycosylated alpha 2B subtype indicates that charge shielding due to carbohydrate moieties does not play a role in this allosteric modulation but, rather, these regulatory effects result from interactions of cations and amiloride analogs with the protein moiety of the receptor. Furthermore, the observation that both alpha 2A and alpha 2B receptor subtypes are modulated by amiloride analogs suggests that structural domains that are conserved between the two are likely to be involved in this allosteric modulation

Nociceptive transmission and modulation via P2X receptors in central pain syndrome.

Science.gov (United States)

Kuan, Yung-Hui; Shyu, Bai-Chuang

2016-05-26

Painful sensations are some of the most frequent complaints of patients who are admitted to local medical clinics. Persistent pain varies according to its causes, often resulting from local tissue damage or inflammation. Central somatosensory pathway lesions that are not adequately relieved can consequently cause central pain syndrome or central neuropathic pain. Research on the molecular mechanisms that underlie this pathogenesis is important for treating such pain. To date, evidence suggests the involvement of ion channels, including adenosine triphosphate (ATP)-gated cation channel P2X receptors, in central nervous system pain transmission and persistent modulation upon and following the occurrence of neuropathic pain. Several P2X receptor subtypes, including P2X2, P2X3, P2X4, and P2X7, have been shown to play diverse roles in the pathogenesis of central pain including the mediation of fast transmission in the peripheral nervous system and modulation of neuronal activity in the central nervous system. This review article highlights the role of the P2X family of ATP receptors in the pathogenesis of central neuropathic pain and pain transmission. We discuss basic research that may be translated to clinical application, suggesting that P2X receptors may be treatment targets for central pain syndrome.

Molecular Features Underlying Selectivity in Chicken Bitter Taste Receptors

Directory of Open Access Journals (Sweden)

Antonella Di Pizio

2018-01-01

Full Text Available Chickens sense the bitter taste of structurally different molecules with merely three bitter taste receptors (Gallus gallus taste 2 receptors, ggTas2rs, representing a minimal case of bitter perception. Some bitter compounds like quinine, diphenidol and chlorpheniramine, activate all three ggTas2rs, while others selectively activate one or two of the receptors. We focus on bitter compounds with different selectivity profiles toward the three receptors, to shed light on the molecular recognition complexity in bitter taste. Using homology modeling and induced-fit docking simulations, we investigated the binding modes of ggTas2r agonists. Interestingly, promiscuous compounds are predicted to establish polar interactions with position 6.51 and hydrophobic interactions with positions 3.32 and 5.42 in all ggTas2rs; whereas certain residues are responsible for receptor selectivity. Lys3.29 and Asn3.36 are suggested as ggTas2r1-specificity-conferring residues; Gln6.55 as ggTas2r2-specificity-conferring residue; Ser5.38 and Gln7.42 as ggTas2r7-specificity conferring residues. The selectivity profile of quinine analogs, quinidine, epiquinidine and ethylhydrocupreine, was then characterized by combining calcium-imaging experiments and in silico approaches. ggTas2r models were used to virtually screen BitterDB compounds. ~50% of compounds known to be bitter to human are likely to be bitter to chicken, with 25, 20, 37% predicted to be ggTas2r1, ggTas2r2, ggTas2r7 agonists, respectively. Predicted ggTas2rs agonists can be tested with in vitro and in vivo experiments, contributing to our understanding of bitter taste in chicken and, consequently, to the improvement of chicken feed.

Calcium pathways such as cAMP modulate clothianidin action through activation of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors.

Science.gov (United States)

Calas-List, Delphine; List, Olivier; Quinchard, Sophie; Thany, Steeve H

2013-07-01

Clothianidin is a neonicotinoid insecticide developed in the early 2000s. We have recently demonstrated that it was a full agonist of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors expressed in the cockroach dorsal unpaired median neurons. Clothianidin was able to act as an agonist of imidacloprid-insensitive nAChR2 receptor and internal regulation of cAMP concentration modulated nAChR2 sensitivity to clothianidin. In the present study, we demonstrated that cAMP modulated the agonist action of clothianidin via α-bungarotoxin-sensitive and insensitive receptors. Clothianidin-induced current-voltage curves were dependent to clothianidin concentrations. At 10 μM clothianidin, increasing cAMP concentration induced a linear current-voltage curve. Clothianidin effects were blocked by 0.5 μM α-bungarotoxin suggesting that cAMP modulation occurred through α-bungarotoxin-sensitive receptors. At 1 mM clothianidin, cAMP effects were associated to α-bungarotoxin-insensitive receptors because clothianidin-induced currents were blocked by 5 μM mecamylamine and 20 μM d-tubocurarine. In addition, we found that application of 1mM clothianidin induced a strong increase of intracellular calcium concentration. These data reinforced the finding that calcium pathways including cAMP modulated clothianidin action on insect nicotinic acetylcholine receptors. We proposed that intracellular calcium pathways such as cAMP could be a target to modulate the mode of action of neonicotinoid insecticides. Copyright © 2013 Elsevier Inc. All rights reserved.

Dopamine modulation of avoidance behavior in Caenorhabditis elegans requires the NMDA receptor NMR-1.

Directory of Open Access Journals (Sweden)

Melvin Baidya

Full Text Available The nematode C. elegans utilizes a relatively simple neural circuit to mediate avoidance responses to noxious stimuli such as the volatile odorant octanol. This avoidance behavior is modulated by dopamine. cat-2 mutant animals that are deficient in dopamine biosynthesis have an increased response latency to octanol compared to wild type animals, and this defect can be fully restored with the application of exogenous dopamine. Because this avoidance behavior is mediated by glutamatergic signaling between sensory neurons and premotor interneurons, we investigated the genetic interactions between dopaminergic signaling and ionotropic glutamate receptors. cat-2 mutant animals lacking either the GLR-1 or GLR-2 AMPA/kainate receptors displayed an increased response latency to octanol, which could be restored via exogenous dopamine. However, whereas cat-2 mutant animals lacking the NMR-1 NMDA receptor had increased response latency to octanol they were insensitive to exogenous dopamine. Mutants that lacked both AMPA/kainate and NMDA receptors were also insensitive to exogenous dopamine. Our results indicate that dopamine modulation of octanol avoidance requires NMR-1, consistent with NMR-1 as a potential downstream signaling target for dopamine.

Pharmacokinetics and pharmacodynamics of LGD-3303 [9-chloro-2-ethyl-1-methyl-3-(2,2,2-trifluoroethyl)-3H-pyrrolo-[3,2-f]quinolin-7(6H)-one], an orally available nonsteroidal-selective androgen receptor modulator.

Science.gov (United States)

Vajda, Eric G; López, Francisco J; Rix, Peter; Hill, Robert; Chen, Yanling; Lee, Kyoung-Jin; O'Brien, Z; Chang, William Y; Meglasson, Martin D; Lee, Yong-Hee

2009-02-01

Selective androgen receptor modulators (SARMs) are a new class of molecules in development to treat a variety of diseases. SARMs maintain the beneficial effects of androgens, including increased muscle mass and bone density, while having reduced activity on unwanted side effects. The mechanisms responsible for the tissue-selective activity of SARMs are not fully understood, and the pharmacokinetic (PK)/pharmacodynamic (PD) relationships are poorly described. Tissue-specific compound distribution potentially could be a mechanism responsible for apparent tissue selectivity. We examined the PK/PD relationship of a novel SARM, LGD-3303 [9-chloro-2-ethyl-1-methyl-3-(2,2,2-trifluoroethyl)-3H-pyrrolo[3,2-f]quinolin-7(6H)-one], in a castrated rat model of androgen deficiency. LGD-3303 has potent activity on levator ani muscle but is a partial agonist on the preputial gland and ventral prostate. LGD-3303 never stimulated ventral prostate above intact levels despite increasing plasma concentrations of compound. Tissue-selective activity was maintained when LGD-3303 was dosed orally or by continuous infusion, two routes of administration with markedly different time versus exposure profiles. Despite the greater muscle activity relative to prostate activity, local tissue concentrations of LGD-3303 were higher in the prostate than in the levator ani muscle. LGD-3303 has SARM properties that are independent of its pharmacokinetic profile, suggesting that the principle mechanism for tissue-selective activity is the result of altered molecular interactions at the level of the androgen receptor.

Oleocanthal Modulates Estradiol-Induced Gene Expression Involving Estrogen Receptor α.

Science.gov (United States)

Keiler, Annekathrin Martina; Djiogue, Sefirin; Ehrhardt, Tino; Zierau, Oliver; Skaltsounis, Leandros; Halabalaki, Maria; Vollmer, Günter

2015-09-01

Oleocanthal is a bioactive compound from olive oil. It has attracted considerable attention as it is anti-inflammatory, antiproliferative, and has been shown to possess neuroprotective properties in vitro and in vivo. Delineated from its polyphenolic structure, the aim of this study was to characterize oleocanthal towards estrogenic properties. This might contribute to partly explain the beneficial effects described for the Mediterranean diet. Estrogenic properties of oleocanthal were assessed by different methods: a) stimulation of reporter gene activity in MVLN or RNDA cells either expressing estrogen receptor α or β, b) stimulation of luciferase reporter gene activity in U2OS osteosarcoma cells expressing estrogen receptor α or β, and c) elucidation of the impact on estradiol-induced gene expression in U2OS cells transduced with both estrogen receptors. Depending on the cell line origin, oleocanthal inhibited luciferase activity (MVLN, U2OS-estrogen receptor β) or weakly induced reporter gene activity at 10 µM in U2OS-estrogen receptor α cells. However, oleocanthal inhibited stimulation of luciferase activity by estradiol from both estrogen receptors. Oleocanthal, if given alone, did not stimulate gene expression in U2OS cells, but it significantly modulated the response of estradiol. Oleocanthal enhanced the effect of estradiol on the regulation of those genes, which are believed to be regulated through heterodimeric estrogen receptors. As the estrogenic response pattern of oleocanthal is rather unique, we compared the results obtained with oleacein. Oleocanthal binds to both estrogen receptors inducing estradiol-agonistic or antiagonistic effects depending on the cell line. Regarding regulation of gene expression in U2OS-estrogen receptor α/β cells, oleocanthal and oleacein enhanced estradiol-mediated regulation of heterodimer-regulated genes. Georg Thieme Verlag KG Stuttgart · New York.

Presynaptic Ionotropic Receptors Controlling and Modulating the Rules for Spike Timing-Dependent Plasticity

Directory of Open Access Journals (Sweden)

Matthijs B. Verhoog

2011-01-01

Full Text Available Throughout life, activity-dependent changes in neuronal connection strength enable the brain to refine neural circuits and learn based on experience. In line with predictions made by Hebb, synapse strength can be modified depending on the millisecond timing of action potential firing (STDP. The sign of synaptic plasticity depends on the spike order of presynaptic and postsynaptic neurons. Ionotropic neurotransmitter receptors, such as NMDA receptors and nicotinic acetylcholine receptors, are intimately involved in setting the rules for synaptic strengthening and weakening. In addition, timing rules for STDP within synapses are not fixed. They can be altered by activation of ionotropic receptors located at, or close to, synapses. Here, we will highlight studies that uncovered how network actions control and modulate timing rules for STDP by activating presynaptic ionotropic receptors. Furthermore, we will discuss how interaction between different types of ionotropic receptors may create “timing” windows during which particular timing rules lead to synaptic changes.

Glutamate requires NMDA receptors to modulate alpha2 adrenoceptor in medulla oblongata cultured cells of newborn rats.

Science.gov (United States)

Marinho da Silva, Sergio; Carrettiero, Daniel C; Chadi, Débora R F

2014-04-03

α2 Adrenoceptors (α2-ARs) are important in regulating the central control of blood pressure in medulla oblongata. However, it is unclear how this receptor is modulated by different receptors, especially the glutamatergic. In the present study, we studied the influence of ionotropic glutamatergic receptors over the α2-ARs in cultured cells of the medulla oblongata of newborn rats. For this purpose, the protein level of the α2-ARs was assessed after administration to the cultured cells of glutamate (glu), the agonists NMDA and kainate (KA), the NMDA receptor antagonist MK801 and the KA receptor antagonist DNQX. Results indicate that the α2-AR protein levels were increased after the treatments with glu and NMDA, and the addition of MK801 to this treatment thwarted this increase. Notwithstanding the fact that KA did not alter the receptor protein level, the combined treatment of DNQX with glu prevented the α2-AR protein modulation. In conclusion, the present study suggests that ionotropic glutamatergic receptors could be related to the α2-AR protein regulation in the medulla oblongata. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The medicinal chemistry of liver X receptor (LXR) modulators.

Science.gov (United States)

Tice, Colin M; Noto, Paul B; Fan, Kristi Yi; Zhuang, Linghang; Lala, Deepak S; Singh, Suresh B

2014-09-11

LXRs have been of interest as targets for the treatment of atherosclerosis for over a decade. In recent years, LXR modulators have also garnered interest for potential use in the treatment of inflammation, Alzheimer's disease (AD), dermatological conditions, hepatic steatosis, and oncology. To date, no LXR modulator has successfully progressed beyond phase I clinical trials. In this Perspective, we summarize published medicinal chemistry efforts in the context of the available crystallographic data, druglikeness, and isoform selectivity. In addition, we discuss the challenges that need to be overcome before an LXR modulator can reach clinical use.

Thermodynamics and structural analysis of positive allosteric modulation of the ionotropic glutamate receptor GluA2

DEFF Research Database (Denmark)

Krintel, Christian; Frydenvang, Karla; Olsen, Lars

2012-01-01

Positive allosteric modulators of the ionotropic glutamate receptor-2 (GluA2) are promising compounds for the treatment of cognitive disorders, e.g. Alzheimer's disease. These modulators bind within the dimer interface of the ligand-binding domain and stabilize the agonist-bound conformation slow...

Ivy and neurogliaform interneurons are a major target of μ opioid receptor modulation

Science.gov (United States)

Krook-Magnuson, Esther; Luu, Lillian; Lee, Sang-Hun; Varga, Csaba; Soltesz, Ivan

2011-01-01

Mu opioid receptors (μORs) are selectively expressed on interneurons in area CA1 of the hippocampus. Fast-spiking, parvalbumin expressing, basket cells express μORs, but circumstantial evidence suggests that another major, unidentified, GABAergic cell class must also be modulated by μORs. Here we report that the abundant, dendritically targeting, neurogliaform family of cells (Ivy and neurogliaform cells) is a previously unrecognized target of direct modulation by μORs. Ivy and neurogliaform cells are not only numerous, but also have unique properties, including promiscuous gap junctions formed with various interneuronal subtypes, volume transmission, and the ability to produce a postsynaptic GABAB response after a single presynaptic spike. Using a mouse line expressing green fluorescent protein under the neuropeptide Y promoter, we find that across all layers of CA1, activation of μORs hyperpolarizes Ivy and neurogliaform cells. Further, paired recordings between synaptically coupled Ivy and pyramidal cells show that Ivy cell terminals are dramatically inhibited by μOR-activation. Effects in Ivy and neurogliaform cells are seen at similar concentrations of agonist as those producing inhibition in fast-spiking PV basket cells. We also report that Ivy cells display the recently described phenomenon of persistent firing, a state of continued firing in the absence of continued input, and that induction of persistent firing is inhibited by μOR-activation. Together these findings identify a major, previously unrecognized, target of μOR-modulation. Given the prominence of this cell type in and beyond CA1, as well as its unique role in microcircuitry, opioid modulation of neurogliaform cells has wide implications. PMID:22016519

Ivy and neurogliaform interneurons are a major target of μ-opioid receptor modulation.

Science.gov (United States)

Krook-Magnuson, Esther; Luu, Lillian; Lee, Sang-Hun; Varga, Csaba; Soltesz, Ivan

2011-10-19

μ-Opioid receptors (μORs) are selectively expressed on interneurons in area CA1 of the hippocampus. Fast-spiking, parvalbumin-expressing, basket cells express μORs, but circumstantial evidence suggests that another major, unidentified, GABAergic cell class must also be modulated by μORs. Here we report that the abundant, dendritically targeting, neurogliaform family of cells (Ivy and neurogliaform cells) is a previously unrecognized target of direct modulation by μORs. Ivy and neurogliaform cells are not only numerous but also have unique properties, including promiscuous gap junctions formed with various interneuronal subtypes, volume transmission, and the ability to produce a postsynaptic GABA(B) response after a single presynaptic spike. Using a mouse line expressing green fluorescent protein under the neuropeptide Y promoter, we find that, across all layers of CA1, activation of μORs hyperpolarizes Ivy and neurogliaform cells. Furthermore, paired recordings between synaptically coupled Ivy and pyramidal cells show that Ivy cell terminals are dramatically inhibited by μOR activation. Effects in Ivy and neurogliaform cells are seen at similar concentrations of agonist as those producing inhibition in fast-spiking parvalbumin basket cells. We also report that Ivy cells display the recently described phenomenon of persistent firing, a state of continued firing in the absence of continued input, and that induction of persistent firing is inhibited by μOR activation. Together, these findings identify a major, previously unrecognized, target of μOR modulation. Given the prominence of this cell type in and beyond CA1, as well as its unique role in microcircuitry, opioid modulation of neurogliaform cells has wide implications.

Semiotic Selection of Mutated or Misfolded Receptor Proteins

DEFF Research Database (Denmark)

Giorgi, Franco; Bruni, Luis Emilio; Maggio, Roberto

2013-01-01

contention that the plasma membrane acts as the locus where several contextual cues may be integrated. As such it allows the semiotic selection of those receptor configurations that provide cells with the minimum essential requirements for agency. The occurrence of protein misfolding makes it impossible...... focused on the significance and semiotic nature of the interplay between membrane receptors and the epigenetic control of gene expression, as mediated by the control of mismatched repairing and protein folding mechanisms....

Photovoltaic module encapsulation design and materials selection, volume 1

Science.gov (United States)

Cuddihy, E.; Carroll, W.; Coulbert, C.; Gupta, A.; Liang, R. H.

1982-01-01

Encapsulation material system requirements, material selection criteria, and the status and properties of encapsulation materials and processes available are presented. Technical and economic goals established for photovoltaic modules and encapsulation systems and their status are described. Available encapsulation technology and data are presented to facilitate design and material selection for silicon flat plate photovoltaic modules, using the best materials available and processes optimized for specific power applications and geographic sites. The operational and environmental loads that encapsulation system functional requirements and candidate design concepts and materials that are identified to have the best potential to meet the cost and performance goals for the flat plate solar array project are described. Available data on encapsulant material properties, fabrication processing, and module life and durability characteristics are presented.

Positive allosteric modulation of GABA-A receptors reduces capsaicin-induced primary and secondary hypersensitivity in rats

DEFF Research Database (Denmark)

Hansen, Rikke Rie; Erichsen, Helle K; Brown, David T

2012-01-01

GABA-A receptor positive allosteric modulators (PAMs) mediate robust analgesia in animal models of pathological pain, in part via enhancing injury-induced loss of GABA-A-α2 and -α3 receptor function within the spinal cord. As yet, a lack of clinically suitable tool compounds has prevented this co...

Ghrelin and Ghrelin Receptor Modulation of Psychostimulant Action

Directory of Open Access Journals (Sweden)

Paul Jeff Wellman

2013-09-01

Full Text Available Ghrelin (GHR is an orexigenic gut peptide that modulates multiple homeostatic functions including gastric emptying, anxiety, stress, memory, feeding and reinforcement. GHR is known to bind and activate growth-hormone secretagogue receptors (termed GHR-Rs. Of interest to our laboratory has been the assessment of the impact of GHR modulation of the locomotor activation and reward/reinforcement properties of psychostimulants such as cocaine and nicotine. Systemic GHR infusions augment cocaine stimulated locomotion and conditioned place preference (CPP in rats, as does food restriction which elevates plasma ghrelin levels. Ghrelin enhancement of psychostimulant function may occur owing to a direct action on mesolimbic dopamine function or may reflect an indirect action of ghrelin on glucocorticoid pathways. Genomic or pharmacological ablation of GHR-Rs attenuates the acute locomotor-enhancing effects of nicotine, cocaine, amphetamine and alcohol and blunts the CPP induced by food, alcohol, amphetamine and cocaine in mice. The stimulant nicotine can induce CPP and like amphetamine and cocaine, repeated administration of nicotine induces locomotor sensitization in rats. Inactivation of ghrelin circuit function in rats by injection of a ghrelin receptor antagonist (e.g. JMV 2959 diminishes the development of nicotine-induced locomotor sensitization. These results suggest a key permissive role for GHR-R activity for the induction of locomotor sensitization to nicotine. Our finding that GHR-R null rats exhibit diminished patterns of responding for intracranial self-stimulation complements an emerging literature implicating central GHR circuits in drug reward/reinforcement. Finally, antagonism of GHR-Rs may represent a smoking cessation modality that not only blocks nicotine-induced reward but that also may limit weight gain after smoking cessation.

Differential targeting of brain stress circuits with a selective glucocorticoid receptor modulator

NARCIS (Netherlands)

Zalachoras, I.; Houtman, R.; Atucha, E.; Devos, R.; Tijssen, A.M.I.; Hu, P.; Lockey, P.M.; Datson, N.A.; Belanoff, J.K.; Lucassen, P.J.; Joëls, M.; de Kloet, E.R.; Roozendaal, B.; Hunt, H.; Meijer, O.C.

2013-01-01

Glucocorticoid receptor (GR) antagonism may be of considerable therapeutic value in stress-related psychopathology such as depression. However, blockade of all GR-dependent processes in the brain will lead to unnecessary and even counteractive effects, such as elevated endogenous cortisol levels.

Dopamine D1 receptor stimulation modulates the formation and retrieval of novel object recognition memory: Role of the prelimbic cortex.

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Pezze, Marie A; Marshall, Hayley J; Fone, Kevin C F; Cassaday, Helen J

2015-11-01

Previous studies have shown that dopamine D1 receptor antagonists impair novel object recognition memory but the effects of dopamine D1 receptor stimulation remain to be determined. This study investigated the effects of the selective dopamine D1 receptor agonist SKF81297 on acquisition and retrieval in the novel object recognition task in male Wistar rats. SKF81297 (0.4 and 0.8 mg/kg s.c.) given 15 min before the sampling phase impaired novel object recognition evaluated 10 min or 24 h later. The same treatments also reduced novel object recognition memory tested 24 h after the sampling phase and when given 15 min before the choice session. These data indicate that D1 receptor stimulation modulates both the encoding and retrieval of object recognition memory. Microinfusion of SKF81297 (0.025 or 0.05 μg/side) into the prelimbic sub-region of the medial prefrontal cortex (mPFC) in this case 10 min before the sampling phase also impaired novel object recognition memory, suggesting that the mPFC is one important site mediating the effects of D1 receptor stimulation on visual recognition memory. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Quantitative structure-activity relationships of selective antagonists of glucagon receptor using QuaSAR descriptors.

Science.gov (United States)

Manoj Kumar, Palanivelu; Karthikeyan, Chandrabose; Hari Narayana Moorthy, Narayana Subbiah; Trivedi, Piyush

2006-11-01

In the present paper, quantitative structure activity relationship (QSAR) approach was applied to understand the affinity and selectivity of a novel series of triaryl imidazole derivatives towards glucagon receptor. Statistically significant and highly predictive QSARs were derived for glucagon receptor inhibition by triaryl imidazoles using QuaSAR descriptors of molecular operating environment (MOE) employing computer-assisted multiple regression procedure. The generated QSAR models revealed that factors related to hydrophobicity, molecular shape and geometry predominantly influences glucagon receptor binding affinity of the triaryl imidazoles indicating the relevance of shape specific steric interactions between the molecule and the receptor. Further, QSAR models formulated for selective inhibition of glucagon receptor over p38 mitogen activated protein (MAP) kinase of the compounds in the series highlights that the same structural features, which influence the glucagon receptor affinity, also contribute to their selective inhibition.

Arctigenin induced gallbladder cancer senescence through modulating epidermal growth factor receptor pathway.

Science.gov (United States)

Zhang, Mingdi; Cai, Shizhong; Zuo, Bin; Gong, Wei; Tang, Zhaohui; Zhou, Di; Weng, Mingzhe; Qin, Yiyu; Wang, Shouhua; Liu, Jun; Ma, Fei; Quan, Zhiwei

2017-05-01

Gallbladder cancer has poor prognosis and limited therapeutic options. Arctigenin, a representative dibenzylbutyrolactone lignan, occurs in a variety of plants. However, the molecular mechanisms involved in the antitumor effect of arctigenin on gallbladder cancer have not been fully elucidated. The expression levels of epidermal growth factor receptor were examined in 100 matched pairs of gallbladder cancer tissues. A positive correlation between high epidermal growth factor receptor expression levels and poor prognosis was observed in gallbladder cancer tissues. Pharmacological inhibition or inhibition via RNA interference of epidermal growth factor receptor induced cellular senescence in gallbladder cancer cells. The antitumor effect of arctigenin on gallbladder cancer cells was primarily achieved by inducing cellular senescence. In gallbladder cancer cells treated with arctigenin, the expression level of epidermal growth factor receptor significantly decreased. The analysis of the activity of the kinases downstream of epidermal growth factor receptor revealed that the RAF-MEK-ERK signaling pathway was significantly inhibited. Furthermore, the cellular senescence induced by arctigenin could be reverted by pcDNA-epidermal growth factor receptor. Arctigenin also potently inhibited the growth of tumor xenografts, which was accompanied by the downregulation of epidermal growth factor receptor and induction of senescence. This study demonstrates arctigenin could induce cellular senescence in gallbladder cancer through the modulation of epidermal growth factor receptor pathway. These data identify epidermal growth factor receptor as a key regulator in arctigenin-induced gallbladder cancer senescence.

Modulation of acetylcholine release from rat striatal slices by the GABA/benzodiazepine receptor complex

Energy Technology Data Exchange (ETDEWEB)

Supavilai, P.; Karobath, M.

1985-02-04

GABA, THIP and muscimol enhance spontaneous and inhibit electrically induced release of tritium labelled compounds from rat striatal slices which have been pre-labelled with /sup 3/H-choline. Baclofen is inactive in this model. Muscimol can inhibit electrically induced release of tritiated material by approximately 75% with half maximal effects at 2 ..mu..M. The response to muscimol can be blocked by the GABA antagonists bicuculline methobromide, picrotoxin, anisatin, R 5135 and CPTBO (cyclopentylbicyclophosphate). Drugs which act on the benzodiazepine receptor (BR) require the presence of muscimol to be effective and they modulate the effects of muscimol in a bidirectional manner. Thus BR agonists enhance and inverse BR agonists attenuate the inhibitory effects of muscimol on electrically induced release. Ro15-1788, a BR antagonist, does not modulate the inhibitory effects of muscimol but antagonizes the actions of clonazepam, a BR agonist, and of DMCM, an inverse BR agonist. These results demonstrate that a GABA/benzodiazepine receptor complex can modulate acetylcholine release from rat striatal slices in vitro. 24 references, 3 figures, 5 table.

Category-selective attention modulates unconscious processes in the middle occipital gyrus.

Science.gov (United States)

Tu, Shen; Qiu, Jiang; Martens, Ulla; Zhang, Qinglin

2013-06-01

Many studies have revealed the top-down modulation (spatial attention, attentional load, etc.) on unconscious processing. However, there is little research about how category-selective attention could modulate the unconscious processing. In the present study, using functional magnetic resonance imaging (fMRI), the results showed that category-selective attention modulated unconscious face/tool processing in the middle occipital gyrus (MOG). Interestingly, MOG effects were of opposed direction for face and tool processes. During unconscious face processing, activation in MOG decreased under the face-selective attention compared with tool-selective attention. This result was in line with the predictive coding theory. During unconscious tool processing, however, activation in MOG increased under the tool-selective attention compared with face-selective attention. The different effects might be ascribed to an interaction between top-down category-selective processes and bottom-up processes in the partial awareness level as proposed by Kouider, De Gardelle, Sackur, and Dupoux (2010). Specifically, we suppose an "excessive activation" hypothesis. Copyright © 2013 Elsevier Inc. All rights reserved.

Functional selectivity of allosteric interactions within G protein-coupled receptor oligomers: the dopamine D1-D3 receptor heterotetramer.

Science.gov (United States)

Guitart, Xavier; Navarro, Gemma; Moreno, Estefania; Yano, Hideaki; Cai, Ning-Sheng; Sánchez-Soto, Marta; Kumar-Barodia, Sandeep; Naidu, Yamini T; Mallol, Josefa; Cortés, Antoni; Lluís, Carme; Canela, Enric I; Casadó, Vicent; McCormick, Peter J; Ferré, Sergi

2014-10-01

The dopamine D1 receptor-D3 receptor (D1R-D3R) heteromer is being considered as a potential therapeutic target for neuropsychiatric disorders. Previous studies suggested that this heteromer could be involved in the ability of D3R agonists to potentiate locomotor activation induced by D1R agonists. It has also been postulated that its overexpression plays a role in L-dopa-induced dyskinesia and in drug addiction. However, little is known about its biochemical properties. By combining bioluminescence resonance energy transfer, bimolecular complementation techniques, and cell-signaling experiments in transfected cells, evidence was obtained for a tetrameric stoichiometry of the D1R-D3R heteromer, constituted by two interacting D1R and D3R homodimers coupled to Gs and Gi proteins, respectively. Coactivation of both receptors led to the canonical negative interaction at the level of adenylyl cyclase signaling, to a strong recruitment of β-arrestin-1, and to a positive cross talk of D1R and D3R agonists at the level of mitogen-activated protein kinase (MAPK) signaling. Furthermore, D1R or D3R antagonists counteracted β-arrestin-1 recruitment and MAPK activation induced by D3R and D1R agonists, respectively (cross-antagonism). Positive cross talk and cross-antagonism at the MAPK level were counteracted by specific synthetic peptides with amino acid sequences corresponding to D1R transmembrane (TM) domains TM5 and TM6, which also selectively modified the quaternary structure of the D1R-D3R heteromer, as demonstrated by complementation of hemiproteins of yellow fluorescence protein fused to D1R and D3R. These results demonstrate functional selectivity of allosteric modulations within the D1R-D3R heteromer, which can be involved with the reported behavioral synergism of D1R and D3R agonists. U.S. Government work not protected by U.S. copyright.

Genistein modulates the estrogen receptor and suppresses angiogenesis and inflammation in the murine model of peritoneal endometriosis

Directory of Open Access Journals (Sweden)

Sutrisno Sutrisno

2018-04-01

Full Text Available The purpose of this study was to investigate the effect of genistein administration on the modulation of the estrogen receptor, inhibition of inflammation and angiogenesis in the murine model of peritoneal endometriosis. A total of thirty-six mice (Mus musculus were divided into six groups (n = 6, including the control group, endometriosis group, endometriosis group treated with various doses of genistein (0.78; 1.04; 1.3 mg/day, and endometriosis group treated with leuprolide acetate (0.00975 mg/day every 5 days for 15 days. Analysis of estrogen receptor-α, estrogen receptor-β, TNF-α, IL-6, VEGF, and HIF-1α were performed immunohistochemically. Expression of estrogen receptor-α, estrogen receptor-β, TNF-α, IL-6, VEGF and HIF-1α increased significantly compared with the control group (p  0.05. Genistein also decreased the expression of TNF-α and IL-6 (1.04 and 1.3 mg/day compared with the endometriosis group, reaching level comparable to that of the control group (p > 0.05. It was concluded that genistein is able to modulate estrogen receptor-α and estrogen receptor-β and inhibit the development of inflammation and angiogenesis in the murine model of peritoneal endometriosis. Thus, genistein can be a candidate in the treatment of endometriosis. Keywords: Estrogen receptor, Growth factor, Inflammation, Angiogenesis, Peritoneum

Selective Attention to Visual Stimuli Using Auditory Distractors Is Altered in Alpha-9 Nicotinic Receptor Subunit Knock-Out Mice.

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Terreros, Gonzalo; Jorratt, Pascal; Aedo, Cristian; Elgoyhen, Ana Belén; Delano, Paul H

2016-07-06

During selective attention, subjects voluntarily focus their cognitive resources on a specific stimulus while ignoring others. Top-down filtering of peripheral sensory responses by higher structures of the brain has been proposed as one of the mechanisms responsible for selective attention. A prerequisite to accomplish top-down modulation of the activity of peripheral structures is the presence of corticofugal pathways. The mammalian auditory efferent system is a unique neural network that originates in the auditory cortex and projects to the cochlear receptor through the olivocochlear bundle, and it has been proposed to function as a top-down filter of peripheral auditory responses during attention to cross-modal stimuli. However, to date, there is no conclusive evidence of the involvement of olivocochlear neurons in selective attention paradigms. Here, we trained wild-type and α-9 nicotinic receptor subunit knock-out (KO) mice, which lack cholinergic transmission between medial olivocochlear neurons and outer hair cells, in a two-choice visual discrimination task and studied the behavioral consequences of adding different types of auditory distractors. In addition, we evaluated the effects of contralateral noise on auditory nerve responses as a measure of the individual strength of the olivocochlear reflex. We demonstrate that KO mice have a reduced olivocochlear reflex strength and perform poorly in a visual selective attention paradigm. These results confirm that an intact medial olivocochlear transmission aids in ignoring auditory distraction during selective attention to visual stimuli. The auditory efferent system is a neural network that originates in the auditory cortex and projects to the cochlear receptor through the olivocochlear system. It has been proposed to function as a top-down filter of peripheral auditory responses during attention to cross-modal stimuli. However, to date, there is no conclusive evidence of the involvement of olivocochlear

Ligand recognition by RAR and RXR receptors: binding and selectivity.

Science.gov (United States)

Sussman, Fredy; de Lera, Angel R

2005-10-06

Fundamental biological functions, most notably embriogenesis, cell growth, cell differentiation, and cell apoptosis, are in part regulated by a complex genomic network that starts with the binding (and activation) of retinoids to their cognate receptors, members of the superfamily of nuclear receptors. We have studied ligand recognition of retinoic receptors (RXRalpha and RARgamma) using a molecular-mechanics-based docking method. The protocol used in this work is able to rank the affinity of pairs of ligands for a single retinoid receptor, the highest values corresponding to those that adapt better to the shape of the binding site and generate the optimal set of electrostatic and apolar interactions with the receptor. Moreover, our studies shed light onto some of the energetic contributions to retinoid receptor ligand selectivity. In this regard we show that there is a difference in polarity between the binding site regions that anchor the carboxylate in RAR and RXR, which translates itself into large differences in the energy of interaction of both receptors with the same ligand. We observe that the latter energy change is canceled off by the solvation energy penalty upon binding. This energy compensation is borne out as well by experiments that address the effect of site-directed mutagenesis on ligand binding to RARgamma. The hypothesis that the difference in binding site polarity might be exploited to build RXR-selective ligands is tested with some compounds having a thiazolidinedione anchoring group.

Directed selective-tunneling of bosons with periodically modulated interaction

International Nuclear Information System (INIS)

Lu, Gengbiao; Fu, Li-Bin; Hai, Wenhua; Zou, Mingliang; Guo, Yu

2015-01-01

We study the tunneling dynamics of bosons with periodically modulated interaction held in a triple-well potential. In high-frequency approximation, we derive a set of reduced coupled equations and the corresponding Floquet solutions are obtained. Based on the analytical results and their numerical correspondence, the directed selective-tunneling effect of a single atom is demonstrated when all bosons are prepared in middle well initially. A scheme for separating a single atom from N bosons is presented, in which the atom can be trapped in right or left well by adjusting the modulation strength. - Highlights: • The Floquet solutions in a modulating triple-well are obtained analytically. • The directed selective-tunneling effect of a single atom is demonstrated. • We present a manipulation scheme for separating a single atom from N bosons

Receptor binding of somatostatin-14 and somatostatin-28 in rat brain: differential modulation by nucleotides and ions.

Science.gov (United States)

Srikant, C B; Dahan, A; Craig, C

1990-02-04

The tissue-selective binding of the two principal bioactive forms of somatostatin, somatostatin-14 (SS-14) and somatostatin-28 (SS-28), their ability to modulate cAMP-dependent and -independent regulation of post-receptor events to different degrees and the documentation of specific labelling of SS receptor subtypes with SS-28 but not SS-14 in discrete regions of rat brain suggest the existence of distinct SS-14 and SS-28 binding sites. Receptor binding of SS-14 ligands has been shown to be modulated by nucleotides and ions, but the effect of these agents on SS-28 binding has not been studied. In the present study we investigated the effects of adenine and guanine nucleotides as well as monovalent and divalent cations on rat brain SS receptors quantitated with radioiodinated analogs of SS-14 ([125I-Tyr11]SS14, referred to in this paper as SS-14) and SS-28 ([Leu8, D-Trp22, 125I-Tyr25] SS-28, referred to as LTT* SS-28) in order to determine if distinct receptor sites for SS-14 and SS-28 could be distinguished on the basis of their modulation by nucleotides and ions. GTP as well as ATP exerted a dose-dependent inhibition (over a concentration range of 10(-7)-10(-3) M) of the binding of the two radioligands. The nucleotide inhibition of binding resulted in a decrease the Bmax of the SS receptors, the binding affinity remaining unaltered. GTP (10(-4) M) decreased the Bmax of LTT* SS-28 binding sites to a greater extent than ATP (145 +/- 10 and 228 +/- 16 respectively, compared to control value of 320 +/- 20 pmol mg-1). Under identical conditions GTP was less effective than ATP in reducing the number of T* SS-14 binding sites (Bmax = 227 +/- 8 and 182 +/- 15, respectively, compared to 340 +/- 15 pmol mg-1 in the absence of nucleotides). Monovalent cations inhibited the binding of both radioligands, Li+ and Na+ inhibited the binding of T* SS-14 to a greater extent than K+. The effect of divalent cations on the other hand was varied. At low concentration (2 mM) Mg2+, Ba2

Spatiotemporal brain dynamics of emotional face processing modulations induced by the serotonin 1A/2A receptor agonist psilocybin.

Science.gov (United States)

Bernasconi, Fosco; Schmidt, André; Pokorny, Thomas; Kometer, Michael; Seifritz, Erich; Vollenweider, Franz X

2014-12-01

Emotional face processing is critically modulated by the serotonergic system. For instance, emotional face processing is impaired by acute psilocybin administration, a serotonin (5-HT) 1A and 2A receptor agonist. However, the spatiotemporal brain mechanisms underlying these modulations are poorly understood. Here, we investigated the spatiotemporal brain dynamics underlying psilocybin-induced modulations during emotional face processing. Electrical neuroimaging analyses were applied to visual evoked potentials in response to emotional faces, following psilocybin and placebo administration. Our results indicate a first time period of strength (i.e., Global Field Power) modulation over the 168-189 ms poststimulus interval, induced by psilocybin. A second time period of strength modulation was identified over the 211-242 ms poststimulus interval. Source estimations over these 2 time periods further revealed decreased activity in response to both neutral and fearful faces within limbic areas, including amygdala and parahippocampal gyrus, and the right temporal cortex over the 168-189 ms interval, and reduced activity in response to happy faces within limbic and right temporo-occipital brain areas over the 211-242 ms interval. Our results indicate a selective and temporally dissociable effect of psilocybin on the neuronal correlates of emotional face processing, consistent with a modulation of the top-down control. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Behind the curtain: cellular mechanisms for allosteric modulation of calcium-sensing receptors

Science.gov (United States)

Cavanaugh, Alice; Huang, Ying; Breitwieser, Gerda E

2012-01-01

Calcium-sensing receptors (CaSR) are integral to regulation of systemic Ca2+ homeostasis. Altered expression levels or mutations in CaSR cause Ca2+ handling diseases. CaSR is regulated by both endogenous allosteric modulators and allosteric drugs, including the first Food and Drug Administration-approved allosteric agonist, Cinacalcet HCl (Sensipar®). Recent studies suggest that allosteric modulators not only alter function of plasma membrane-localized CaSR, but regulate CaSR stability at the endoplasmic reticulum. This brief review summarizes our current understanding of the role of membrane-permeant allosteric agonists in cotranslational stabilization of CaSR, and highlights additional, indirect, signalling-dependent role(s) for membrane-impermeant allosteric drugs. Overall, these studies suggest that allosteric drugs act at multiple cellular organelles to control receptor abundance and hence function, and that drug hydrophobicity can bias the relative contributions of plasma membrane and intracellular organelles to CaSR abundance and signalling. LINKED ARTICLES This article is part of a themed section on the Molecular Pharmacology of G Protein-Coupled Receptors (GPCRs). To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-6. To view the 2010 themed section on the same topic visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2010.159.issue-5/issuetoc PMID:21470201

Effects of Chronic Alcohol Exposure on the Modulation of Ischemia-Induced Glutamate Release via Cannabinoid Receptors in the Dorsal Hippocampus.

Science.gov (United States)

Zheng, Lei; Wu, Xiaoda; Dong, Xiao; Ding, Xinli; Song, Cunfeng

2015-10-01

Chronic alcohol consumption is a critical contributing factor to ischemic stroke, as it enhances ischemia-induced glutamate release, leading to more severe excitotoxicity and brain damage. But the neural mechanisms underlying this phenomenon are poorly understood. We evaluated the effects of chronic alcohol exposure on the modulation of ischemia-induced glutamate release via CB1 and CB2 cannabinoid receptors during middle cerebral artery occlusion, using in vivo microdialysis coupled with high-performance liquid chromatography, in alcohol-naïve rats or rats after 1 or 30 days of withdrawal from chronic ethanol intake (6% v/v for 14 days). Intra-dorsal hippocampus (DH) infusions of ACEA or JWH133, selective CB1 or CB2 receptor agonists, respectively, decreased glutamate release in the DH in alcohol-naïve rats in a dose-dependent manner. Such an effect was reversed by co-infusions of SR141716A or AM630, selective CB1 or CB2 receptor antagonists, respectively. After 30 days, but not 1 day of withdrawal, ischemia induced an enhancement in glutamate release in the DH, as compared with non-alcohol-treated control group. Intra-DH infusions of JWH133, but not ACEA, inhibited ischemia-induced glutamate release in the DH after 30 days of withdrawal. Finally, 1 day of withdrawal did not alter the protein level of CB1 or CB2 receptors in the DH, as compared to non-alcohol-treated control rats. Whereas 30 days of withdrawal robustly decreased the protein level of CB1 receptors, but failed to alter the protein level of CB2 receptors, in the DH, as compared to non-alcohol-treated control rats. Together, these findings suggest that loss of expression/function of CB1 receptors, but not CB2 receptors in the DH, is correlated with the enhancement of ischemia-induced glutamate release after prolonged alcohol withdrawal. Copyright © 2015 by the Research Society on Alcoholism.

5-HT1A receptors modulate small-conductance Ca2+-activated K+ channels

DEFF Research Database (Denmark)

Grunnet, Morten; Jespersen, Thomas; Perrier, Jean-François

2004-01-01

Small-conductance calcium-activated potassium channels (SK) are responsible for the medium afterhyperpolarisation (mAHP) following action potentials in neurons. Here we tested the ability of serotonin (5-HT) to modulate the activity of SK channels by coexpressing 5-HT1A receptors with different...

Rac1 modulates G-protein-coupled receptor-induced bronchial smooth muscle contraction.

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Sakai, Hiroyasu; Kai, Yuki; Sato, Ken; Ikebe, Mitsuo; Chiba, Yohihiko

2018-01-05

Increasing evidence suggests a functional role of RhoA/Rho-kinase signalling as a mechanism for smooth muscle contraction; however, little is known regarding the roles of Rac1 and other members of the Rho protein family. This study aimed to examine whether Rac1 modulates bronchial smooth muscle contraction. Ring preparations of bronchi isolated from rats were suspended in an organ bath, and isometric contraction of circular smooth muscle was measured. Immunoblotting was used to examine myosin light chain phosphorylation in bronchial smooth muscle. Our results demonstrated that muscle contractions induced by carbachol (CCh) and endothelin-1 (ET-1) were inhibited by EHT1864, a selective Rac1 inhibitor, and NSC23766, a selective inhibitor of Rac1-specific guanine nucleotide exchange factors. Similarly, myosin light chain and myosin phosphatase target subunit 1 (MYPT1) at Thr853 phosphorylation induced by contractile agonist were inhibited with Rac1 inhibition. However, contractions induced by high K + , calyculin A (a potent protein phosphatase inhibitor) and K + /PDBu were not inhibited by these Rac1 inhibitors. Interestingly, NaF (a G-protein activator)-induced contractions were inhibited by EHT1864 but not by NSC23766. We next examined the effects of a trans-acting activator of transcription protein transduction domain (PTD) fusion protein with Rac1 (PTD-Rac1) on muscle contraction. The constitutively active form of PTD-Rac1 directly induced force development and contractions were abolished by EHT1864. These results suggest that Rac1, activated by G protein-coupled receptor agonists, such as CCh and ET-1, may induce myosin light chain and MYPT phosphorylation and modulate the contraction of bronchial smooth muscle. Copyright © 2017 Elsevier B.V. All rights reserved.

Modulation of orientation-selective neurons by motion: when additive, when multiplicative?

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Torsten eLüdge

2014-06-01

Full Text Available The recurrent interaction among orientation-selective neurons in the primary visual cortex (V1 is suited to enhance contours in a noisy visual scene. Motion is known to have a strong pop-up effect in perceiving contours, but how motion-sensitive neurons in V1 support contour detection remains vastly elusive. Here we suggest how the various types of motion-sensitive neurons observed in V1 should be wired together in a micro-circuitry to optimally extract contours in the visual scene. Motion-sensitive neurons can be selective about the direction of motion occurring at some spot or respond equally to all directions (pandirectional. We show that, in the light of figure-ground segregation, direction-selective motion neurons should additively modulate the corresponding orientation-selective neurons with preferred orientation orthogonal to the motion direction. In turn, to maximally enhance contours, pandirectional motion neurons should multiplicatively modulate all orientation-selective neurons with co-localized receptive fields. This multiplicative modulation amplifies the local V1-circuitry among co-aligned orientation-selective neurons for detecting elongated contours. We suggest that the additive modulation by direction- specific motion neurons is achieved through synaptic projections to the somatic region, and the multiplicative modulation by pandirectional motion neurons through projections to the apical region of orientation-specific pyramidal neurons. For the purpose of contour detection, the V1- intrinsic integration of motion information is advantageous over a downstream integration as it exploits the recurrent V1-circuitry designed for that task.

Distinct roles of presynaptic dopamine receptors in the differential modulation of the intrinsic synapses of medium-spiny neurons in the nucleus accumbens

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Schmauss Claudia

2007-01-01

Full Text Available Abstract Background In both schizophrenia and addiction, pathological changes in dopamine release appear to induce alterations in the circuitry of the nucleus accumbens that affect coordinated thought and motivation. Dopamine acts principally on medium-spiny GABA neurons, which comprise 95% of accumbens neurons and give rise to the majority of inhibitory synapses in the nucleus. To examine dopamine action at single medium-spiny neuron synapses, we imaged Ca2+ levels in their presynaptic varicosities in the acute brain slice using two-photon microscopy. Results Presynaptic Ca2+ rises were differentially modulated by dopamine. The D1/D5 selective agonist SKF81297 was exclusively facilitatory. The D2/D3 selective agonist quinpirole was predominantly inhibitory, but in some instances it was facilitatory. Studies using D2 and D3 receptor knockout mice revealed that quinpirole inhibition was either D2 or D3 receptor-mediated, while facilitation was mainly D3 receptor-mediated. Subsets of varicosities responded to both D1 and D2 agonists, showing that there was significant co-expression of these receptor families in single medium-spiny neurons. Neighboring presynaptic varicosities showed strikingly heterogeneous responses to DA agonists, suggesting that DA receptors may be differentially trafficked to individual varicosities on the same medium-spiny neuron axon. Conclusion Dopamine receptors are present on the presynaptic varicosities of medium-spiny neurons, where they potently control GABAergic synaptic transmission. While there is significant coexpression of D1 and D2 family dopamine receptors in individual neurons, at the subcellular level, these receptors appear to be heterogeneously distributed, potentially explaining the considerable controversy regarding dopamine action in the striatum, and in particular the degree of dopamine receptor segregation on these neurons. Assuming that post-receptor signaling is restricted to the microdomains of

5-HT4-receptors modulate induction of long-term depression but not potentiation at hippocampal output synapses in acute rat brain slices.

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Matthias Wawra

Full Text Available The subiculum is the principal target of CA1 pyramidal cells and mediates hippocampal output to various cortical and subcortical regions of the brain. The majority of subicular pyramidal cells are burst-spiking neurons. Previous studies indicated that high frequency stimulation in subicular burst-spiking cells causes presynaptic NMDA-receptor dependent long-term potentiation (LTP whereas low frequency stimulation induces postsynaptic NMDA-receptor-dependent long-term depression (LTD. In the present study, we investigate the effect of 5-hydroxytryptamine type 4 (5-HT4 receptor activation and blockade on both forms of synaptic plasticity in burst-spiking cells. We demonstrate that neither activation nor block of 5-HT4 receptors modulate the induction or expression of LTP. In contrast, activation of 5-HT4 receptors facilitates expression of LTD, and block of the 5-HT4 receptor prevents induction of short-term depression and LTD. As 5-HT4 receptors are positively coupled to adenylate cyclase 1 (AC1, 5-HT4 receptors might modulate PKA activity through AC1. Since LTD is blocked in the presence of 5-HT4 receptor antagonists, our data are consistent with 5-HT4 receptor activation by ambient serotonin or intrinsically active 5-HT4 receptors. Our findings provide new insight into aminergic modulation of hippocampal output.

A pp32-retinoblastoma protein complex modulates androgen receptor-mediated transcription and associates with components of the splicing machinery

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Adegbola, Onikepe; Pasternack, Gary R.

2005-01-01

We have previously shown pp32 and the retinoblastoma protein interact. pp32 and the retinoblastoma protein are nuclear receptor transcriptional coregulators: the retinoblastoma protein is a coactivator for androgen receptor, the major regulator of prostate cancer growth, while pp32, which is highly expressed in prostate cancer, is a corepressor of the estrogen receptor. We now show pp32 increases androgen receptor-mediated transcription and the retinoblastoma protein modulates this activity. Using affinity purification and mass spectrometry, we identify members of the pp32-retinoblastoma protein complex as PSF and nonO/p54nrb, proteins implicated in coordinate regulation of nuclear receptor-mediated transcription and splicing. We show that the pp32-retinoblastoma protein complex is modulated during TPA-induced K562 differentiation. Present evidence suggests that nuclear receptors assemble multiprotein complexes to coordinately regulate transcription and mRNA processing. Our results suggest that pp32 and the retinoblastoma protein may be part of a multiprotein complex that coordinately regulates nuclear receptor-mediated transcription and mRNA processing

Effect of GABA agonists and GABA-A receptor modulators on cocaine- and food-maintained responding and cocaine discrimination in rats.

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Barrett, Andrew C; Negus, S Stevens; Mello, Nancy K; Caine, S Barak

2005-11-01

Recent studies indicate that GABAergic ligands modulate abuse-related effects of cocaine. The goal of this study was to evaluate the effects of a mechanistically diverse group of GABAergic ligands on the discriminative stimulus and reinforcing effects of cocaine in rats. One group of rats was trained to discriminate 5.6 mg/kg cocaine from saline in a two-lever, food-reinforced, drug discrimination procedure. In two other groups, responding was maintained by cocaine (0-3.2 mg/kg/injection) or liquid food (0-100%) under a fixed ratio 5 schedule. Six GABA agonists were tested: the GABA-A receptor agonist muscimol, the GABA-B receptor agonist baclofen, the GABA transaminase inhibitor gamma-vinyl-GABA (GVG), and three GABA-A receptor modulators (the barbiturate pentobarbital, the high-efficacy benzodiazepine midazolam, and the low-efficacy benzodiazepine enazenil). When tested alone, none of the compounds substituted fully for the discriminative stimulus effects of cocaine. As acute pretreatments, select doses of midazolam and pentobarbital produced 2.2- to 3.6-fold rightward shifts in the cocaine dose-effect function. In contrast, muscimol, baclofen, GVG, and enazenil failed to alter the discriminative stimulus effects of cocaine. In assays of cocaine- and food-maintained responding, midazolam and pentobarbital decreased cocaine self-administration at doses 9.6- and 3.3-fold lower, respectively, than those that decreased food-maintained responding. In contrast, muscimol, baclofen, and GVG decreased cocaine self-administration at doses that also decreased food-maintained responding. Enazenil failed to alter cocaine self-administration. Together with previous studies, these data suggest that among mechanistically diverse GABA agonists, high-efficacy GABA-A modulators may be the most effective for modifying the abuse-related effects of cocaine.

Distinctive Modulation of Dopamine Release in the Nucleus Accumbens Shell Mediated by Dopamine and Acetylcholine Receptors.

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Shin, Jung Hoon; Adrover, Martin F; Alvarez, Veronica A

2017-11-15

Nucleus accumbens (NAc) shell shows unique dopamine (DA) signals in vivo and plays a unique role in DA-dependent behaviors such as reward-motivated learning and the response to drugs of abuse. A disynaptic mechanism for DA release was reported and shown to require synchronized firing of cholinergic interneurons (CINs) and activation of nicotinic acetylcholine (ACh) receptors (nAChRs) in DA neuron (DAN) axons. The properties of this disynaptic mechanism of DA transmission are not well understood in the NAc shell. In this study, in vitro fast-scan cyclic voltammetry was used to examine the modulation of DA transmission evoked by CINs firing in the shell of mice and compared with other striatal regions. We found that DA signals in the shell displayed significant degree of summation in response to train stimulation of CINs, contrary to core and dorsal striatum. The summation was amplified by a D2-like receptor antagonist and experiments with mice with targeted deletion of D2 receptors to DANs or CINs revealed that D2 receptors in CINs mediate a fast inhibition observed within 100 ms of the first pulse, whereas D2 autoreceptors in DAN terminals are engaged in a slower inhibition that peaks at ∼500 ms. ACh also contributes to the use-dependent inhibition of DA release through muscarinic receptors only in the shell, where higher activity of acetylcholinesterase minimizes nAChR desensitization and promotes summation. These findings show that DA signals are modulated differentially by endogenous DA and ACh in the shell, which may underlie the unique features of shell DA signals in vivo SIGNIFICANCE STATEMENT The present study reports that dopamine (DA) release evoked by activation of cholinergic interneurons displays a high degree of summation in the shell and shows unique modulation by endogenous DA and acetylcholine. Desensitization of nicotinic receptors, which is a prevailing mechanism for use-dependent inhibition in the nucleus accumbens core and dorsal striatum, is

Ligand Modulation of the Epstein-Barr Virus-induced Seven-transmembrane Receptor EBI2

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Benned-Jensen, Tau; Smethurst, Christopher; Holst, Peter Johannes

2011-01-01

The Epstein-Barr virus-induced receptor 2 (EBI2) is a constitutively active seven-transmembrane receptor, which was recently shown to orchestrate the positioning of B cells in the follicle. To date, no ligands, endogenously or synthetic, have been identified that modulate EBI2 activity. Here we...... with similar potency. Overexpression of EBI2 profoundly potentiated antibody-stimulated ex vivo proliferation of murine B cells compared with WT cells, whereas this was equivalently reduced for EBI2-deficient B cells. Inhibition of EBI2 constitutive activity suppressed the proliferation in all cases...

GABAA receptor activity modulating piperine analogs: In vitro metabolic stability, metabolite identification, CYP450 reaction phenotyping, and protein binding.

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Zabela, Volha; Hettich, Timm; Schlotterbeck, Götz; Wimmer, Laurin; Mihovilovic, Marko D; Guillet, Fabrice; Bouaita, Belkacem; Shevchenko, Bénédicte; Hamburger, Matthias; Oufir, Mouhssin

2018-01-01

In a screening of natural products for allosteric modulators of GABA A receptors (γ-aminobutyric acid type A receptor), piperine was identified as a compound targeting a benzodiazepine-independent binding site. Given that piperine is also an activator of TRPV1 (transient receptor potential vanilloid type 1) receptors involved in pain signaling and thermoregulation, a series of piperine analogs were prepared in several cycles of structural optimization, with the aim of separating GABA A and TRPV1 activating properties. We here investigated the metabolism of piperine and selected analogs in view of further cycles of lead optimization. Metabolic stability of the compounds was evaluated by incubation with pooled human liver microsomes, and metabolites were analyzed by UHPLC-Q-TOF-MS. CYP450 isoenzymes involved in metabolism of compounds were identified by reaction phenotyping with Silensomes™. Unbound fraction in whole blood was determined by rapid equilibrium dialysis. Piperine was the metabolically most stable compound. Aliphatic hydroxylation, and N- and O-dealkylation were the major routes of oxidative metabolism. Piperine was exclusively metabolized by CYP1A2, whereas CYP2C9 contributed significantly in the oxidative metabolism of all analogs. Extensive binding to blood constituents was observed for all compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

GABA regulates the rat hypothalamic-pituitary-adrenocortical axis via different GABA-A receptor alpha-subtypes

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Mikkelsen, Jens D; Bundzikova, Jana; Larsen, Marianne Hald

2008-01-01

dependent on the composition of the GABA-A receptor subunits through which they act. We show here that positive modulators of alpha(1)-subtype containing GABA-A receptors with zolpidem (10 mg/kg) increase HPA activity in terms of increase in plasma corticosterone and induction of Fos in the PVN, whereas...... after positive modulation of GABA-A receptors composed of alpha(1)-subunit(s) affects a selective afferent system than the PVN, which is distinct from another afferent system(s) activated by non alpha(1)-containing GABA-A receptors....

In vitro blood-brain barrier permeability predictions for GABAA receptor modulating piperine analogs

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Eigenmann, Daniela Elisabeth; Dürig, Carmen; Jähne, Evelyn Andrea

2016-01-01

The alkaloid piperine from black pepper (Piper nigrum L.) and several synthetic piperine analogs were recently identified as positive allosteric modulators of γ-aminobutyric acid type A (GABAA) receptors. In order to reach their target sites of action, these compounds need to enter the brain by c...

Characterization of Angiotensin II Molecular Determinants Involved in AT1 Receptor Functional Selectivity.

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Domazet, Ivana; Holleran, Brian J; Richard, Alexandra; Vandenberghe, Camille; Lavigne, Pierre; Escher, Emanuel; Leduc, Richard; Guillemette, Gaétan

2015-06-01

The octapeptide angiotensin II (AngII) exerts a variety of cardiovascular effects through the activation of the AngII type 1 receptor (AT1), a G protein-coupled receptor. The AT1 receptor engages and activates several signaling pathways, including heterotrimeric G proteins Gq and G12, as well as the extracellular signal-regulated kinases (ERK) 1/2 pathway. Additionally, following stimulation, βarrestin is recruited to the AT1 receptor, leading to receptor desensitization. It is increasingly recognized that specific ligands selectively bind and favor the activation of some signaling pathways over others, a concept termed ligand bias or functional selectivity. A better understanding of the molecular basis of functional selectivity may lead to the development of better therapeutics with fewer adverse effects. In the present study, we developed assays allowing the measurement of six different signaling modalities of the AT1 receptor. Using a series of AngII peptide analogs that were modified in positions 1, 4, and 8, we sought to better characterize the molecular determinants of AngII that underlie functional selectivity of the AT1 receptor in human embryonic kidney 293 cells. The results reveal that position 1 of AngII does not confer functional selectivity, whereas position 4 confers a bias toward ERK signaling over Gq signaling, and position 8 confers a bias toward βarrestin recruitment over ERK activation and Gq signaling. Interestingly, the analogs modified in position 8 were also partial agonists of the protein kinase C (PKC)-dependent ERK pathway via atypical PKC isoforms PKCζ and PKCι. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Does protein binding modulate the effect of angiotensin II receptor antagonists?

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Marc P Maillard

2001-03-01

Full Text Available IntroductionAngiotensin II AT 1-receptor antagonists are highly bound to plasma proteins (≥ 99%. With some antagonists, such as DuP-532, the protein binding was such that no efficacy of the drug could be demonstrated clinically. Whether protein binding interferes with the efficacy of other antagonists is not known. We have therefore investigated in vitro how plasma proteins may affect the antagonistic effect of different AT1-receptor antagonists.MethodsA radio-receptor binding assay was used to analyse the interaction between proteins and the ability of various angiotensin II (Ang II antagonists to block AT1-receptors. In addition, the Biacore technology, a new technique which enables the real-time monitoring of binding events between two molecules, was used to evaluate the dissociation rate constants of five AT1-receptor antagonists from human serum albumin.ResultsThe in vitro AT 1-antagonistic effects of different Ang II receptor antagonists were differentially affected by the presence of human plasma, with rightward shifts of the IC50 ranging from one to several orders of magnitude. The importance of the shift correlates with the dissociation rate constants of these drugs from albumin. Our experiments also show that the way that AT1-receptor antagonists bind to proteins differs from one compound to another. These results suggest that the interaction with plasma proteins appears to modulate the efficacy of some Ang II antagonists.ConclusionAlthough the high binding level of Ang II receptor antagonist to plasma proteins appears to be a feature common to this class of compounds, the kinetics and characteristics of this binding is of great importance. With some antagonists, protein binding interferes markedly with their efficacy to block AT1-receptors.

3-Iodothyronamine, a Novel Endogenous Modulator of Transient Receptor Potential Melastatin 8?

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Noushafarin Khajavi

2017-08-01

Full Text Available The decarboxylated and deiodinated thyroid hormone (TH derivative, 3-iodothyronamine (3-T1AM, is suggested to be involved in energy metabolism and thermoregulation. G protein-coupled receptors (GPCRs are known as the main targets for 3-T1AM; however, transient receptor potential channels (TRPs were also recently identified as new targets of 3-T1AM. This article reviews the current knowledge of a putative novel role of 3-T1AM in the modulation of TRPs. Specifically, the TRP melastatin 8 (TRPM8 was identified as a target of 3-T1AM in different cell types including neoplastic cells, whereby 3-T1AM significantly increased cytosolic Ca2+ through TRPM8 activation. Similarly, the β-adrenergic receptor is involved in 3-T1AM-induced Ca2+ influx. Therefore, it has been suggested that 3-T1AM-induced Ca2+ mobilization might be due to β-adrenergic receptor/TRPM8 channel interaction, which adds to the complexity of GPCR regulation by TRPs. It has been revealed that TRPM8 activation leads to a decline in TRPV1 activity, which may be of therapeutic benefit in clinical circumstances such as treatment of TRPV1-mediated inflammatory hyperalgesia, colitis, and dry eye syndrome. This review also summarizes the inverse association between changes in TRPM8 and TRPV1 activity after 3-T1AM stimulation. This finding prompted further detailed investigations of the interplay between 3-T1AM and the GPCR/TRPM8 axis and indicated the probability of additional GPCR/TRP constellations that are modulated by this TH derivative.

Progesterone modulates the LPS-induced nitric oxide production by a progesterone-receptor independent mechanism.

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Wolfson, Manuel Luis; Schander, Julieta Aylen; Bariani, María Victoria; Correa, Fernando; Franchi, Ana María

2015-12-15

Genital tract infections caused by Gram-negative bacteria induce miscarriage and are one of the most common complications of human pregnancy. LPS administration to 7-day pregnant mice induces embryo resorption after 24h, with nitric oxide playing a fundamental role in this process. We have previously shown that progesterone exerts protective effects on the embryo by modulating the inflammatory reaction triggered by LPS. Here we sought to investigate whether the in vivo administration of progesterone modulated the LPS-induced nitric oxide production from peripheral blood mononuclear cells from pregnant and non-pregnant mice. We found that progesterone downregulated LPS-induced nitric oxide production by a progesterone receptor-independent mechanism. Moreover, our results suggest a possible participation of glucocorticoid receptors in at least some of the anti-inflammatory effects of progesterone. Copyright © 2015 Elsevier B.V. All rights reserved.

Devil's Claw to suppress appetite--ghrelin receptor modulation potential of a Harpagophytum procumbens root extract.

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Cristina Torres-Fuentes

Full Text Available Ghrelin is a stomach-derived peptide that has been identified as the only circulating hunger hormone that exerts a potent orexigenic effect via activation of its receptor, the growth hormone secretagogue receptor (GHS-R1a. Hence, the ghrelinergic system represents a promising target to treat obesity and obesity-related diseases. In this study we analysed the GHS-R1a receptor activating potential of Harpagophytum procumbens, popularly known as Devil's Claw, and its effect on food intake in vivo. H. procumbens is an important traditional medicinal plant from Southern Africa with potent anti-inflammatory and analgesic effects. This plant has been also used as an appetite modulator but most evidences are anecdotal and to our knowledge, no clear scientific studies relating to appetite modulation have been done to this date. The ghrelin receptor activation potential of an extract derived from the dried tuberous roots of H. procumbens was analysed by calcium mobilization and receptor internalization assays in human embryonic kidney cells (Hek stably expressing the GHS-R1a receptor. Food intake was investigated in male C57BL/6 mice following intraperitoneal administration of H. procumbens root extract in ad libitum and food restricted conditions. Exposure to H. procumbens extract demonstrated a significant increased cellular calcium influx but did not induce subsequent GHS-R1a receptor internalization, which is a characteristic for full receptor activation. A significant anorexigenic effect was observed in male C57BL/6 mice following peripheral administration of H. procumbens extract. We conclude that H. procumbens root extract is a potential novel source for potent anti-obesity bioactives. These results reinforce the promising potential of natural bioactives to be developed into functional foods with weight-loss and weight maintenance benefits.

Structural determinants for selective recognition of peptide ligands for endothelin receptor subtypes ETA and ETB.

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Lättig, Jens; Oksche, Alexander; Beyermann, Michael; Rosenthal, Walter; Krause, Gerd

2009-07-01

The molecular basis for recognition of peptide ligands endothelin-1, -2 and -3 in endothelin receptors is poorly understood. Especially the origin of ligand selectivity for ET(A) or ET(B) is not clearly resolved. We derived sequence-structure-function relationships of peptides and receptors from mutational data and homology modeling. Our major findings are the dissection of peptide ligands into four epitopes and the delineation of four complementary structural portions on receptor side explaining ligand recognition in both endothelin receptor subtypes. In addition, structural determinants for ligand selectivity could be described. As a result, we could improve the selectivity of BQ3020 about 10-fold by a single amino acid substitution, validating our hypothesis for ligand selectivity caused by different entrances to the receptors' transmembrane binding sites. A narrow tunnel shape in ET(A) is restrictive for a selected group of peptide ligands' N-termini, whereas a broad funnel-shaped entrance in ET(B) accepts a variety of different shapes and properties of ligands.

Opiates Modulate Thermosensation by Internalizing Cold Receptor TRPM8

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George Shapovalov

2013-08-01

Full Text Available Stimulation of μ-opioid receptors (OPRMs brings powerful pain relief, but it also leads to the development of tolerance and addiction. Ensuing withdrawal in abstinent patients manifests itself with severe symptoms, including cold hyperalgesia, often preventing addicted patients from successfully completing the rehabilitation. Unsurprisingly, OPRMs have been a central point of many studies. Nonetheless, a satisfactory understanding of the pathways leading to distorted sensory responses during opiate administration and abstinence is far from complete. Here, we present a mechanism that leads to modulation by OPRMs of one of the sensory responses, thermosensation. Activation of OPRM1 leads to internalization of a cold-sensor TRPM8, which can be reversed by a follow-up treatment with the inverse OPRM agonist naloxone. Knockout of TRPM8 protein leads to a decrease in morphine-induced cold analgesia. The proposed pathway represents a universal mechanism that is probably shared by regulatory pathways modulating general pain sensation in response to opioid treatment.

High motivation for exercise is associated with altered chromatin regulators of monoamine receptor gene expression in the striatum of selectively bred mice.

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Saul, M C; Majdak, P; Perez, S; Reilly, M; Garland, T; Rhodes, J S

2017-03-01

Although exercise is critical for health, many lack the motivation to exercise, and it is unclear how motivation might be increased. To uncover the molecular underpinnings of increased motivation for exercise, we analyzed the transcriptome of the striatum in four mouse lines selectively bred for high voluntary wheel running and four non-selected control lines. The striatum was dissected and RNA was extracted and sequenced from four individuals of each line. We found multiple genes and gene systems with strong relationships to both selection and running history over the previous 6 days. Among these genes were Htr1b, a serotonin receptor subunit and Slc38a2, a marker for both glutamatergic and γ-aminobutyric acid (GABA)-ergic signaling. System analysis of the raw results found enrichment of transcriptional regulation and kinase genes. Further, we identified a splice variant affecting the Wnt-related Golgi signaling gene Tmed5. Using coexpression network analysis, we found a cluster of interrelated coexpression modules with relationships to running behavior. From these modules, we built a network correlated with running that predicts a mechanistic relationship between transcriptional regulation by nucleosome structure and Htr1b expression. The Library of Integrated Network-Based Cellular Signatures identified the protein kinase C δ inhibitor, rottlerin, the tyrosine kinase inhibitor, Linifanib and the delta-opioid receptor antagonist 7-benzylidenenaltrexone as potential compounds for increasing the motivation to run. Taken together, our findings support a neurobiological framework of exercise motivation where chromatin state leads to differences in dopamine signaling through modulation of both the primary neurotransmitters glutamate and GABA, and by neuromodulators such as serotonin. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

The Sigma-1 Receptor as a Pluripotent Modulator in Living Systems.

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Su, Tsung-Ping; Su, Tzu-Chieh; Nakamura, Yoki; Tsai, Shang-Yi

2016-04-01

The sigma-1 receptor (Sig-1R) is an endoplasmic reticulum (ER) protein that resides specifically in the mitochondria-associated endoplasmic reticulum (ER) membrane (MAM), an interface between ER and mitochondria. In addition to being able to translocate to the plasma membrane (PM) to interact with ion channels and other receptors, Sig-1R also occurs at the nuclear envelope, where it recruits chromatin-remodeling factors to affect the transcription of genes. Sig-1Rs have also been reported to interact with other membranous or soluble proteins at other loci, including the cytosol, and to be involved in several central nervous system (CNS) diseases. Here, we propose that Sig-1R is a pluripotent modulator with resultant multiple functional manifestations in living systems. Published by Elsevier Ltd.

Selective pharmacological blockade of the 5-HT7 receptor attenuates light and 8-OH-DPAT induced phase shifts of mouse circadian wheel running activity

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Jonathan eShelton

2015-01-01

Full Text Available Recent reports have illustrated a reciprocal relationship between circadian rhythm disruption and mood disorders. The 5-HT7 receptor may provide a crucial link between the two sides of this equation since the receptor plays a critical role in sleep, depression, and circadian rhythm regulation. To further define the role of the 5-HT7 receptor as a potential pharmacotherapy to correct circadian rhythm disruptions, the current study utilized the selective 5-HT7 antagonist JNJ-18038683 (10 mg/kg in three different circadian paradigms. While JNJ-18038683 was ineffective at phase shifting the onset of wheel running activity in mice when administered at different circadian time (CT points across the circadian cycle, pretreatment with JNJ-18038683 blocked non-photic phase advance (CT6 induced by the 5-HT1A/7 receptor agonist 8-OH-DPAT (3 mg/kg. Since light induced phase shifts in mammals are partially mediated via the modulation of the serotonergic system, we determined if JNJ-18038683 altered phase shifts induced by a light pulse at times known to phase delay (CT15 or advance (CT22 wheel running activity in free running mice. Light exposure resulted in a robust shift in the onset of activity in vehicle treated animals at both times tested. Administration of JNJ-18038683 significantly attenuated the light-induced phase delay and completely blocked the phase advance. The current study demonstrates that pharmacological blockade of the 5-HT7 receptor by JNJ-18038683 blunts both non-photic and photic phase shifts of circadian wheel running activity in mice. These findings highlight the importance of the 5-HT7 receptor in modulating circadian rhythms. Due to the opposite modulating effects of light resetting between diurnal and nocturnal species, pharmacotherapy targeting the 5-HT7 receptor in conjunction with bright light therapy may prove therapeutically beneficial by correcting the desynchronization of internal rhythms observed in depressed individuals.

Transmembrane α-Helix 2 and 7 Are Important for Small Molecule-Mediated Activation of the GLP-1 Receptor

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Underwood, Christina Rye; Møller Knudsen, Sanne; Schjellerup Wulff, Birgitte

2011-01-01

Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study, the structur......Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study......, the structurally related small molecule, compound 3, stimulated cAMP production from GLP-1R, but not from the homologous glucagon receptor (GluR). The receptor selectivity encouraged a chimeric receptor approach to identify domains important for compound 3-mediated activation of GLP-1R. A subsegment of the GLP-1R...... transmembrane domain containing TM2 to TM5 was sufficient to transfer compound 3 responsiveness to GluR. Therefore, divergent residues in this subsegment of GLP-1R and GluR are responsible for the receptor selectivity of compound 3. Functional analyses of other chimeric receptors suggested that the existence...

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

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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.

Discovery of an Oxybenzylglycine Based Peroxisome Proliferator Activated Receptor Alpha Selective

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Li, J.; Kennedy, L; Shi, Y; Tao, S; Ye, X; Chen, S; Wang, Y; Hernandez, A; Wang, W; et al.

2010-01-01

An 1,3-oxybenzylglycine based compound 2 (BMS-687453) was discovered to be a potent and selective peroxisome proliferator activated receptor (PPAR) {alpha} agonist, with an EC{sub 50} of 10 nM for human PPAR{alpha} and {approx}410-fold selectivity vs human PPAR{gamma} in PPAR-GAL4 transactivation assays. Similar potencies and selectivity were also observed in the full length receptor co-transfection assays. Compound 2 has negligible cross-reactivity against a panel of human nuclear hormone receptors including PPAR{delta}. Compound 2 demonstrated an excellent pharmacological and safety profile in preclinical studies and thus was chosen as a development candidate for the treatment of atherosclerosis and dyslipidemia. The X-ray cocrystal structures of the early lead compound 12 and compound 2 in complex with PPAR{alpha} ligand binding domain (LBD) were determined. The role of the crystal structure of compound 12 with PPAR{alpha} in the development of the SAR that ultimately resulted in the discovery of compound 2 is discussed.

Selectivity and specificity of sphingosine-1-phosphate receptor ligands: caveats and critical thinking in characterizing receptor-mediated effects.

Science.gov (United States)

Salomone, Salvatore; Waeber, Christian

2011-01-01

Receptors for sphingosine-1-phosphate (S1P) have been identified only recently. Their medicinal chemistry is therefore still in its infancy, and few selective agonists or antagonists are available. Furthermore, the selectivity of S1P receptor agonists or antagonists is not well established. JTE-013 and BML-241 (also known as CAY10444), used extensively as specific S1P(2) and S1P(3) receptors antagonists respectively, are cases in point. When analyzing S1P-induced vasoconstriction in mouse basilar artery, we observed that JTE-013 inhibited not only the effect of S1P, but also the effect of U46619, endothelin-1 or high KCl; JTE-013 strongly inhibited responses to S1P in S1P(2) receptor knockout mice. Similarly, BML-241 has been shown to inhibit increases in intracellular Ca(2+) concentration via P(2) receptor or α(1A)-adrenoceptor stimulation and α(1A)-adrenoceptor-mediated contraction of rat mesenteric artery, while it did not affect S1P(3)-mediated decrease of forskolin-induced cyclic AMP accumulation. Another putative S1P(1/3) receptor antagonist, VPC23019, does not inhibit S1P(3)-mediated vasoconstriction. With these examples in mind, we discuss caveats about relying on available pharmacological tools to characterize receptor subtypes.

Selectivity and specificity of sphingosine-1-phosphate receptor ligands: caveats and critical thinking in characterizing receptor-mediated effects

Directory of Open Access Journals (Sweden)

Christian eWaeber

2011-02-01

Full Text Available Receptors for sphingosine-1-phosphate (S1P have been identified only recently. Their medicinal chemistry is therefore still in its infancy, and few selective agonists or antagonists are available. Furthermore, the selectivity of S1P receptor agonists or antagonists is not well established. JTE-013 and BML-241 (also known as CAY10444, used extensively as specific S1P2 and S1P3 receptors antagonists respectively, are cases in point. When analyzing S1P-induced vasoconstriction in mouse basilar artery, we observed that JTE-013 inhibited not only the effect of S1P, but also the effect of U46619, endothelin-1 or high KCl; JTE-013 strongly inhibited responses to S1P in S1P2 receptor knockout mice. Similarly, BML-241 has been shown to inhibit increases in intracellular Ca2+ concentration via P2 receptor or α1A-adrenoceptor stimulation and α1A-adrenoceptor-mediated contraction of rat mesenteric artery, while it did not affect S1P3-mediated decrease of forskolin-induced cyclic AMP accumulation. Another putative S1P1/3 receptor antagonist, VPC23019, does not inhibit S1P3-mediated vasoconstriction. With these examples in mind, we discuss caveats about relying on available pharmacological tools to characterize receptor subtypes.

Adrenergic receptor-mediated modulation of striatal firing patterns.

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Ohta, Hiroyuki; Kohno, Yu; Arake, Masashi; Tamura, Risa; Yukawa, Suguru; Sato, Yoshiaki; Morimoto, Yuji; Nishida, Yasuhiro; Yawo, Hiromu

2016-11-01

Although noradrenaline and adrenaline are some of the most important neurotransmitters in the central nervous system, the effects of noradrenergic/adrenergic modulation on the striatum have not been determined. In order to explore the effects of adrenergic receptor (AR) agonists on the striatal firing patterns, we used optogenetic methods which can induce continuous firings. We employed transgenic rats expressing channelrhodopsin-2 (ChR2) in neurons. The medium spiny neuron showed a slow rising depolarization during the 1-s long optogenetic striatal photostimulation and a residual potential with 8.6-s half-life decay after the photostimulation. As a result of the residual potential, five repetitive 1-sec long photostimulations with 20-s onset intervals cumulatively increased the number of spikes. This 'firing increment', possibly relating to the timing control function of the striatum, was used to evaluate the AR modulation. The β-AR agonist isoproterenol decreased the firing increment between the 1st and 5th stimulation cycles, while the α 1 -AR agonist phenylephrine enhanced the firing increment. Isoproterenol and adrenaline increased the early phase (0-0.5s of the photostimulation) firing response. This adrenergic modulation was inhibited by the β-antagonist propranolol. Conversely, phenylephrine and noradrenaline reduced the early phase response. β-ARs and α 1 -ARs work in opposition controlling the striatal firing initiation and the firing increment. Copyright © 2016 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

Modulation of cannabinoid receptor activation as a neuroprotective strategy for EAE and stroke.

Science.gov (United States)

Zhang, Ming; Martin, Billy R; Adler, Martin W; Razdan, Raj J; Kong, Weimin; Ganea, Doina; Tuma, Ronald F

2009-06-01

Recognition of the importance of the endocannabinoid system in both homeostasis and pathologic responses raised interest recently in the development of therapeutic agents based on this system. The CB(2) receptor, a component of the endocannabinoid system, has significant influence on immune function and inflammatory responses. Inflammatory responses are major contributors to central nervous system (CNS) injury in a variety of diseases. In this report, we present evidence that activation of CB(2) receptors, by selective CB(2) agonists, reduces inflammatory responses that contribute to CNS injury. The studies demonstrate neuroprotective effects in experimental autoimmune encephalomyelitis, a model of multiple sclerosis, and in a murine model of cerebral ischemia/reperfusion injury. In both cases, CB(2) receptor activation results in reduced white cell rolling and adhesion to cerebral microvessels, a reduction in immune cell invasion, and improved neurologic function after insult. In addition, administration of the CB(1) antagonist SR141716A reduces infarct size following ischemia/reperfusion injury. Administration of both a selective CB(2) agonist and a CB(1) antagonist has the unique property of increasing blood flow to the brain during the occlusion period, suggesting an effect on collateral blood flow. In summary, selective CB(2) receptor agonists and CB(1) receptor antagonists have significant potential for neuroprotection in animal models of two devastating diseases that currently lack effective treatment options.

Receptor activity modifying proteins (RAMPs) interact with the VPAC1 receptor: evidence for differential RAMP modulation of multiple signalling pathways

International Nuclear Information System (INIS)

Christopoulos, G.; Morfis, M.; Sexton, P.M.; Christopoulos, A.; Laburthe, M.; Couvineau, A.

2001-01-01

Full text: Receptor activity modifying proteins (RAMP) constitute a family of three accessory proteins that affect the expression and/or phenotype of the calcitonin receptor (CTR) or CTR-like receptor (CRLR). In this study we screened a range of class II G protein-coupled receptors (PTH1, PTH2, GHRH, VPAC1, VPAC2 receptors) for possible RAMP interactions by measurement of receptor-induced translocation of c-myc tagged RAMP1 or HA tagged RAMP3. Of these, only the VPAC1 receptor caused significant translocation of c-myc-RAMP1 or HA-RAMP3 to the cell surface. Co-transfection of VPAC1 and RAMPs did not alter 125 I-VIP binding and specificity. VPAC1 receptor function was subsequently analyzed through parallel determinations of cAMP accumulation and phosphoinositide (PI) hydrolysis in the presence and absence of each of the three RAMPs. In contrast to CTR-RAMP interaction, where there was an increase in cAMP Pharmacologisand a decrease in PI hydrolysis, VPAC1-RAMP interaction was characterized by a specific increase in agonist-mediated PI hydrolysis when co-transfected with RAMP2. This change was due to an enhancement of Emax with no change in EC 50 value for VIP. No significant change in cAMP accumulation was observed. This is the first demonstration of an interaction of RAMPs with a G protein-coupled receptor outside the CTR family and may suggest a more generalized role for RAMPs in modulating G protein-coupled receptor signaling. Copyright (2001) Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists

Modulation of β-adrenergic receptors in the pituitary gland following adrenalectomy in rats

International Nuclear Information System (INIS)

Souza, E.B. de

1987-01-01

The effects of adrenalectomy on β-adrenergic receptors in the rat pituitary were examined using quantitative in vitro autoradiography with 125 I-iodocyanopindolol( 125 ICYP). 125 ICYP binding in the anterior, intermediate and posterior lobes of the pituitary gland was significantly increased in chronically adrenalectomized rats. The increase in 125 ICYP binding sites in the rat pituitary following adrenalectomy was not reversed by glucocorticoid replacement with dexamethasone. These data indicate that catecholamines of adrenomedullary origin are capable of modulating β-adrenergic receptors in the pituitary gland and suggest that peripheral epinephrine may be important in regulating pituitary hormone secretion. (author)

Design and Discovery of Functionally Selective Serotonin 2C (5-HT2C) Receptor Agonists.

Science.gov (United States)

Cheng, Jianjun; McCorvy, John D; Giguere, Patrick M; Zhu, Hu; Kenakin, Terry; Roth, Bryan L; Kozikowski, Alan P

2016-11-10

On the basis of the structural similarity of our previous 5-HT 2C agonists with the melatonin receptor agonist tasimelteon and the putative biological cross-talk between serotonergic and melatonergic systems, a series of new (2,3-dihydro)benzofuran-based compounds were designed and synthesized. The compounds were evaluated for their selectivity toward 5-HT 2A , 5-HT 2B , and 5-HT 2C receptors in the calcium flux assay with the ultimate goal to generate selective 5-HT 2C agonists. Selected compounds were studied for their functional selectivity by comparing their transduction efficiency at the G protein signaling pathway versus β-arrestin recruitment. The most functionally selective compound (+)-7e produced weak β-arrestin recruitment and also demonstrated less receptor desensitization compared to serotonin in both calcium flux and phosphoinositide (PI) hydrolysis assays. We report for the first time that selective 5-HT 2C agonists possessing weak β-arrestin recruitment can produce distinct receptor desensitization properties.

Differential modulation of FXR activity by chlorophacinone and ivermectin analogs

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Hsu, Chia-Wen [NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD (United States); Hsieh, Jui-Hua [National Toxicology Program, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC (United States); Huang, Ruili [NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD (United States); Pijnenburg, Dirk [PamGene International B.V., Wolvenhoek 10, 5211 HH ' s-Hertogenbosch (Netherlands); Khuc, Thai [NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD (United States); Hamm, Jon [Integrated Laboratory System, Inc., Morrisville, NC (United States); Zhao, Jinghua; Lynch, Caitlin [NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD (United States); Beuningen, Rinie van [PamGene International B.V., Wolvenhoek 10, 5211 HH ' s-Hertogenbosch (Netherlands); Chang, Xiaoqing [Integrated Laboratory System, Inc., Morrisville, NC (United States); Houtman, René [PamGene International B.V., Wolvenhoek 10, 5211 HH ' s-Hertogenbosch (Netherlands); Xia, Menghang, E-mail: mxia@mail.nih.gov [NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD (United States)

2016-12-15

Chemicals that alter normal function of farnesoid X receptor (FXR) have been shown to affect the homeostasis of bile acids, glucose, and lipids. Several structural classes of environmental chemicals and drugs that modulated FXR transactivation were previously identified by quantitative high-throughput screening (qHTS) of the Tox21 10 K chemical collection. In the present study, we validated the FXR antagonist activity of selected structural classes, including avermectin anthelmintics, dihydropyridine calcium channel blockers, 1,3-indandione rodenticides, and pyrethroid pesticides, using in vitro assay and quantitative structural-activity relationship (QSAR) analysis approaches. (Z)-Guggulsterone, chlorophacinone, ivermectin, and their analogs were profiled for their ability to alter CDCA-mediated FXR binding using a panel of 154 coregulator motifs and to induce or inhibit transactivation and coactivator recruitment activities of constitutive androstane receptor (CAR), liver X receptor alpha (LXRα), or pregnane X receptor (PXR). Our results showed that chlorophacinone and ivermectin had distinct modes of action (MOA) in modulating FXR-coregulator interactions and compound selectivity against the four aforementioned functionally-relevant nuclear receptors. These findings collectively provide mechanistic insights regarding compound activities against FXR and possible explanations for in vivo toxicological observations of chlorophacinone, ivermectin, and their analogs. - Highlights: • A subset of Tox21 chemicals was investigated for FXR antagonism. • In vitro and computational approaches were used to evaluate FXR antagonists. • Chlorophacinone and ivermectin had distinct patterns in modulating FXR activity.

Sigma-1 Receptor as a Pluripotent Modulator in the Living System

Science.gov (United States)

Su, Tsung-Ping; Su, Tzu-Chieh; Nakamura, Yoki; Tsai, Shang-Yi

2016-01-01

The sigma-1 receptor (Sig-1R) is an endoplasmic reticulum (ER) protein resides specifically at the interface between ER and mitochondria, called the MAM, where the Sig-1R is recently reported to be involved in certain CNS diseases. In addition to being able to translocate to the plasma membrane to interact with ion channels and other receptors, the Sig-1R is found to exist at the nuclear envelope where it recruits chromatin-remodeling factors to affect the transcription of genes. As well, thorough experimental and bioinformatic means, Sig-1Rs are reported to interact with other membranous or soluble proteins at other loci, including the cytosol. We propose that the Sig-1R is a pluripotent modulator with resultant multiple functional manifestations in the living system. PMID:26869505

GABA receptor imaging

Energy Technology Data Exchange (ETDEWEB)

Lee, Jong Doo [Yonsei University College of Medicine, Seoul (Korea, Republic of)

2007-04-15

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA{sub A}-receptor that allows chloride to pass through a ligand gated ion channel and GABA{sub B}-receptor that uses G-proteins for signaling. The GABA{sub A}-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA{sub A}-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with {sup 11}C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, {sup 18}F-fluoroflumazenil (FFMZ) has been developed to overcome {sup 11}C's short half-life. {sup 18}F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1{sup 1}C-FMZ PET instead of {sup 18}F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA{sub A} receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.

GABA receptor imaging

International Nuclear Information System (INIS)

Lee, Jong Doo

2007-01-01

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA A -receptor that allows chloride to pass through a ligand gated ion channel and GABA B -receptor that uses G-proteins for signaling. The GABA A -receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA A -receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with 11 C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, 18 F-fluoroflumazenil (FFMZ) has been developed to overcome 11 C's short half-life. 18 F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1 1 C-FMZ PET instead of 18 F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA A receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas

Design and cellular kinetics of dansyl-labeled CADA derivatives with anti-HIV and CD4 receptor down-modulating activity.

Science.gov (United States)

Vermeire, Kurt; Lisco, Andrea; Grivel, Jean-Charles; Scarbrough, Emily; Dey, Kaka; Duffy, Noah; Margolis, Leonid; Bell, Thomas W; Schols, Dominique

2007-08-15

A new class of anti-retrovirals, cyclotriazadisulfonamide (CADA) and its derivatives, specifically down-regulate CD4, the main receptor of HIV, and prevent HIV infection in vitro. In this work, several CADA derivatives, chemically labeled with a fluorescent dansyl group, were evaluated for their biological features and cellular uptake kinetics. We identified a derivative KKD-016 with antiviral and CD4 down-modulating capabilities similar to those of the parental compound CADA. By using flow cytometry, we demonstrated that the dose-dependent cellular uptake of this derivative correlated with CD4 down-modulation. The uptake and activity of the dansyl-labeled compounds were not dependent on the level of expression of CD4 at the cell surface. Removal of the CADA compounds from the cell culture medium resulted in their release from the cells followed by a complete restoration of CD4 expression. The inability of several fluorescent CADA derivatives to down-modulate CD4 was not associated with their lower cellular uptake and was not reversed by facilitating their cell penetration by a surfactant. These results prove the successful integration of the dansyl fluorophore into the chemical structure of a CD4 down-modulating anti-HIV compound, and show the feasibility of tracking a receptor and its down-modulator simultaneously. These fluorescent CADA analogs with reversible CD4 down-regulating potency can now be applied in further studies on receptor modulation, and in the exploration of their potentials as preventive and therapeutic anti-HIV drugs.

Bidirectional modulation of hippocampal gamma (20-80 Hz) frequency activity in vitro via alpha(α)- and beta(β)-adrenergic receptors (AR).

Science.gov (United States)

Haggerty, D C; Glykos, V; Adams, N E; Lebeau, F E N

2013-12-03

Noradrenaline (NA) in the hippocampus plays an important role in memory function and has been shown to modulate different forms of synaptic plasticity. Oscillations in the gamma frequency (20-80 Hz) band in the hippocampus have also been proposed to play an important role in memory functions and, evidence from both in vitro and in vivo studies, has suggested this activity can be modulated by NA. However, the role of different NA receptor subtypes in the modulation of gamma frequency activity has not been fully elucidated. We have found that NA (30 μM) exerts a bidirectional control on the magnitude of kainate-evoked (50-200 nM) gamma frequency oscillations in the cornu Ammonis (CA3) region of the rat hippocampus in vitro via activation of different receptor subtypes. Activation of alpha-adrenergic receptors (α-AR) reduced the power of the gamma frequency oscillation. In contrast, activation of beta-adrenergic receptors (β-AR) caused an increase in the power of the gamma frequency oscillations. Using specific agonists and antagonists of AR receptor subtypes we demonstrated that these effects are mediated specifically via α1A-AR and β1-AR subtypes. NA activated both receptor subtypes, but the α1A-AR-mediated effect predominated, resulting in a reversible suppression of gamma frequency activity. These results suggest that NA is able to differentially modulate on-going gamma frequency oscillatory activity that could result in either increased or decreased information flow through the hippocampus. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Selective mode of action of guanidine-containing non-peptides at human NPFF receptors.

Science.gov (United States)

Findeisen, Maria; Würker, Cäcilia; Rathmann, Daniel; Meier, René; Meiler, Jens; Olsson, Roger; Beck-Sickinger, Annette G

2012-07-12

The binding pocket of both NPFF receptors was investigated, focusing on subtype-selective behavior. By use of four nonpeptidic compounds and the peptide mimetics RF9 and BIBP3226, agonistic and antagonistic properties were characterized. A set of Ala receptor mutants was generated. The binding pocket was narrowed down to the upper part of transmembrane helices V, VI, VII and the extracellular loop 2. Positions 5.27 and 6.59 have been shown to have a strong impact on receptor activation and were suggested to form an acidic, negatively charged binding pocket in both NPFF receptor subtypes. Additionally, position 7.35 was identified to play an important role in functional selectivity. According to docking experiments, the aryl group of AC-216 interacts with position 7.35 in the NPFF(1) but not in the NPFF(2) receptor. These results provide distinct insights into the receptor specific binding pockets, which is necessary for the development of drugs to address the NPFF system.

δ-opioid receptor and somatostatin receptor-4 heterodimerization: possible implications in modulation of pain associated signaling.

Directory of Open Access Journals (Sweden)

Rishi K Somvanshi

Full Text Available Pain relief is the principal action of opioids. Somatostatin (SST, a growth hormone inhibitory peptide is also known to alleviate pain even in cases when opioids fail. Recent studies have shown that mice are prone to sustained pain and devoid of analgesic effect in the absence of somatostatin receptor 4 (SSTR4. In the present study, using brain slices, cultured neurons and HEK-293 cells, we showed that SSTR4 and δ-Opioid receptor (δOR exist in a heteromeric complex and function in synergistic manner. SSTR4 and δOR co-expressed in cortical/striatal brain regions and spinal cord. Using cultured neuronal cells, we describe the heterogeneous complex formation of SSTR4 and δOR at neuronal cell body and processes. Cotransfected cells display inhibition of cAMP/PKA and co-activation of SSTR4 and δOR oppose receptor trafficking induced by individual receptor activation. Furthermore, downstream signaling pathways either associated with withdrawal or pain relief are modulated synergistically with a predominant role of SSTR4. Inhibition of cAMP/PKA and activation of ERK1/2 are the possible cellular adaptations to prevent withdrawal induced by chronic morphine use. Our results reveal direct intra-membrane interaction between SSTR4 and δOR and provide insights for the molecular mechanism for the anti-nociceptive property of SST in combination with opioids as a potential therapeutic approach to avoid undesirable withdrawal symptoms.

Characterization and selection of CZT detector modules for HEX experiment onboard Chandrayaan-1

International Nuclear Information System (INIS)

Vadawale, S.V.; Purohit, S.; Shanmugam, M.; Acharya, Y.B.; Goswami, J.N.; Sudhakar, M.; Sreekumar, P.

2009-01-01

We present the results of characterization of a large sample of Cadmium Zinc Telluride (CZT) detector modules planned to be used for the HEX (High Energy X-ray spectrometer) experiment onboard India's first mission to the Moon, Chandrayaan-1. We procured forty modules from Orbotech Medical Solutions Ltd. and carried out a detailed characterization of each module at various temperatures and selected final nine detector modules for the flight model of HEX. Here we present the results of the characterization of all modules and the selection procedure for the HEX flight detector modules. These modules show 5-6% energy resolution (at 122 keV, for best 90% of pixels) at room temperature which is improved to ∼4% when these modules are cooled to sub-0 deg. C temperature. The gain and energy resolution were stable during the long duration tests.

Modulation of Central Synapses by Astrocyte-Released ATP and Postsynaptic P2X Receptors

Science.gov (United States)

Pankratov, Yuriy

2017-01-01

Communication between neuronal and glial cells is important for neural plasticity. P2X receptors are ATP-gated cation channels widely expressed in the brain where they mediate action of extracellular ATP released by neurons and/or glia. Recent data show that postsynaptic P2X receptors underlie slow neuromodulatory actions rather than fast synaptic transmission at brain synapses. Here, we review these findings with a particular focus on the release of ATP by astrocytes and the diversity of postsynaptic P2X-mediated modulation of synaptic strength and plasticity in the CNS. PMID:28845311

Inhibition of cisplatin-induced vomiting by selective 5-hydroxytryptamine M-receptor antagonism.

OpenAIRE

Miner, W. D.; Sanger, G. J.

1986-01-01

MDL 72222, the selective 5-hydroxytryptamine (5-HT) M-receptor antagonist, prevented or reduced cisplatin-induced emesis in ferrets. It is suggested that cisplatin-induced, and possibly other cytotoxic drug-induced vomiting may involve a 5-HT M-receptor mechanism.

Sigma-1 Receptor Plays a Negative Modulation on N-type Calcium Channel

Directory of Open Access Journals (Sweden)

Kang Zhang

2017-05-01

Full Text Available The sigma-1 receptor is a 223 amino acids molecular chaperone with a single transmembrane domain. It is resident to eukaryotic mitochondrial-associated endoplasmic reticulum and plasma membranes. By chaperone-mediated interactions with ion channels, G-protein coupled receptors and cell-signaling molecules, the sigma-1 receptor performs broad physiological and pharmacological functions. Despite sigma-1 receptors have been confirmed to regulate various types of ion channels, the relationship between the sigma-1 receptor and N-type Ca2+ channel is still unclear. Considering both sigma-1 receptors and N-type Ca2+ channels are involved in intracellular calcium homeostasis and neurotransmission, we undertake studies to explore the possible interaction between these two proteins. In the experiment, we confirmed the expression of the sigma-1 receptors and the N-type calcium channels in the cholinergic interneurons (ChIs in rat striatum by using single-cell reverse transcription-polymerase chain reaction (scRT-PCR and immunofluorescence staining. N-type Ca2+ currents recorded from ChIs in the brain slice of rat striatum was depressed when sigma-1 receptor agonists (SKF-10047 and Pre-084 were administrated. The inhibition was completely abolished by sigma-1 receptor antagonist (BD-1063. Co-expression of the sigma-1 receptors and the N-type calcium channels in Xenopus oocytes presented a decrease of N-type Ca2+ current amplitude with an increase of sigma-1 receptor expression. SKF-10047 could further depress N-type Ca2+ currents recorded from oocytes. The fluorescence resonance energy transfer (FRET assays and co-immunoprecipitation (Co-IP demonstrated that sigma-1 receptors and N-type Ca2+ channels formed a protein complex when they were co-expressed in HEK-293T (Human Embryonic Kidney -293T cells. Our results revealed that the sigma-1 receptors played a negative modulation on N-type Ca2+ channels. The mechanism for the inhibition of sigma-1 receptors on

Identification of novel β-lactams and pyrrolidinone derivatives as selective Histamine-3 receptor (H3R) modulators as possible anti-obesity agents.

Science.gov (United States)

Ghoshal, Anirban; Kumar, Ajeet; Yugandhar, Doddapaneni; Sona, Chandan; Kuriakose, Sunu; Nagesh, Kommu; Rashid, Mamunur; Singh, Sandeep K; Wahajuddin, Muhammad; Yadav, Prem N; Srivastava, Ajay K

2018-05-25

Four series of structurally related β-lactams, 2,5-pyrrolidinediones, azaspirodecatrienediones (ASDT) and dihydropyrroloquinoxalinetriones (DPQT) were synthesized by utilizing post-Ugi modifications in one-pot, and their activity towards human histamine-3 receptor (H3R) was evaluated. Out of 94 compounds, screened against histamine-3 receptor (H3R), 21 compounds showed high H3R selective agonist property with EC 50 values ranging from 187 nM to 0.1 nM, whereas none of the compound was found to have the affinity towards other receptors of histamine family such as histamine H1, H2, and H4 receptor. All active compounds have no assay interference activity as determined by in-silico analysis and receptor independent luciferase assay and cell cytotoxicity assay. Given the important role of H3R in hypophagia, we also evaluated the in vivo effect of the representative compound 6k on the cumulative food intake in diet induce obese C57BL6/J mice. Interestingly, we observed that single dose administration (20 mg/kg, intraperitoneal injection) of 6k significantly suppressed cumulative food intake, while no significant effect was observed at 10 mg/kg. These results suggest that β-lactams, 2,5-pyrrolidinediones, azaspirodecatrienediones (ASDT) and dihydropyrroloquinoxalinetriones (DPQT) could be useful for the development of anti-obesity candidate drugs. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Selective solid-liquid extraction of lithium halide salts using a ditopic macrobicyclic receptor.

Science.gov (United States)

Mahoney, Joseph M; Beatty, Alicia M; Smith, Bradley D

2004-11-29

A ditopic salt receptor that is known to bind and extract solid NaCl, KCl, NaBr, and KBr into organic solution as their contact ion pairs is now shown by NMR and X-ray crystallography to bind and extract solid LiCl and LiBr as water-separated ion pairs. The receptor can transport these salts from an aqueous phase through a liquid organic membrane with a cation selectivity of K+ > Na+ > Li+. However, the selectivity order is strongly reversed when the receptor extracts solid alkali metal chlorides and bromides into organic solution. For a three-component mixture of solid LiCl, NaCl, and KCl, the ratio of salts extracted and complexed to the receptor in CDCl3 was 94:4:2, respectively. The same strong lithium selectivity was also observed in the case of a three-component mixture of solid LiBr, NaBr, and KBr where the ratio of extracted salts was 92:5:3. This observation is attributed to the unusually high solubility of lithium salts in organic solvents. The study suggests that ditopic receptors with an ability to extract solid salts as associated ion pairs may have application in separation processes.

Modulation of the constitutive activity of the ghrelin receptor by use of pharmacological tools and mutagenesis.

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Mokrosiński, Jacek; Holst, Birgitte

2010-01-01

Ghrelin and its receptor are important regulators of metabolic functions, including appetite, energy expenditure, fat accumulation, and growth hormone (GH) secretion. The ghrelin receptor is characterized by an ability to signal even without any ligand present with approximately 50% of the maximally ghrelin-induced efficacy-a feature that may have important physiological implications. The high basal signaling can be modulated either by administration of specific ligands or by engineering of mutations in the receptor structure. [D-Arg(1), D-Phe(5), D-Trp(7,9), Leu(11)]-substance P was the first inverse agonist to be identified for the ghrelin receptor, and this peptide has been used as a starting point for identification of the structural requirements for inverse agonist properties in the ligand. The receptor binding core motif was identified as D-Trp-Phe-D-Trp-Leu-Leu, and elongation of this peptide in the amino-terminal end determined the efficacy. Attachment of a positively charged amino acid was responsible for full inverse agonism, whereas an alanin converted the peptide into a partial agonist. Importantly, by use of mutational mapping of the residues critical for the modified D-Trp-Phe-D-Trp-Leu-Leu peptides, it was found that space-generating mutations in the deeper part of the receptor improved inverse agonism, whereas similar mutations located in the more extracellular part improved agonism. Modulation of the basal signaling by mutations in the receptor structure is primarily obtained by substitutions in an aromatic cluster that keep TMs VI and VII in close proximity to TM III and thus stabilize the active conformation. Also, substitution of a Phe in TM V is crucial for the high basal activity of the receptor as this residue serves as a partner for Trp VI:13 in the active conformation. It is suggested that inverse agonist and antagonist against the ghrelin receptor provide an interesting possibility in the development of drugs for treatment of obesity and

Increased vascular sympathetic modulation in mice with Mas receptor deficiency

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Rabello Casali, Karina; Ravizzoni Dartora, Daniela; Moura, Marina; Bertagnolli, Mariane; Bader, Michael; Haibara, Andrea; Alenina, Natalia; Irigoyen, Maria Claudia; Santos, Robson A

2016-01-01

Introduction: The angiotensin-converting enzyme 2 (ACE2)/angiotensin (Ang)-(1–7)/Mas axis could modulate the heart rate (HR) and blood pressure variabilities (BPV) which are important predictors of cardiovascular risk and provide information about the autonomic modulation of the cardiovascular system. Therefore we investigated the effect of Mas deficiency on autonomic modulation in wild type and Mas-knockout (KO) mice. Methods: Blood pressure was recorded at high sample rate (4000 Hz). Stationary sequences of 200–250 beats were randomly chosen. Frequency domain analysis of HR and BPV was performed with an autoregressive algorithm on the pulse interval sequences and on respective systolic sequences. Results: The KO group presented an increase of systolic arterial pressure (SAP; 127.26±11.20 vs 135.07±6.98 mmHg), BPV (3.54±1.54 vs 5.87±2.12 mmHg2), and low-frequency component of systolic BPV (0.12±0.11 vs 0.47±0.34 mmHg2). Conclusions: The deletion of Mas receptor is associated with an increase of SAP and with an increased BPV, indicating alterations in autonomic control. Increase of sympathetic vascular modulation in absence of Mas evidences the important role of Ang-(1–7)/Mas on cardiovascular regulation. Moreover, the absence of significant changes in HR and HRV can indicate an adaptation of autonomic cardiac balance. Our results suggest that the Ang-(1–7)/Mas axis seems more important in autonomic modulation of arterial pressure than HR. PMID:27080540

Diagnostic and Therapeutic Radiopharmaceutical Agents for Selective Discrimination of Prostate Cancer

Science.gov (United States)

2009-10-01

selective androgen receptor modulators ( SARMs ). Abstr. Pap. Am... nonsteroidal ligands for binding and activation of the androgen receptor . Mol. Pharmacol. 63, 211–223. (10) Bohl, C. E., Chang, C., Mohler, M. L., Chen, J...Lehtovuori, P. T., and Nyronen, T. H. (2005) Three-dimensional structure-activity relationships of nonsteroidal ligands in complex with androgen receptor

Common angiotensin receptor blockers may directly modulate the immune system via VDR, PPAR and CCR2b

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Lee Robert E

2006-01-01

Full Text Available Abstract Background There have been indications that common Angiotensin Receptor Blockers (ARBs may be exerting anti-inflammatory actions by directly modulating the immune system. We decided to use molecular modelling to rapidly assess which of the potential targets might justify the expense of detailed laboratory validation. We first studied the VDR nuclear receptor, which is activated by the secosteroid hormone 1,25-dihydroxyvitamin-D. This receptor mediates the expression of regulators as ubiquitous as GnRH (Gonadatrophin hormone releasing hormone and the Parathyroid Hormone (PTH. Additionally we examined Peroxisome Proliferator-Activated Receptor Gamma (PPARgamma, which affects the function of phagocytic cells, and the C-CChemokine Receptor, type 2b, (CCR2b, which recruits monocytes to the site of inflammatory immune challenge. Results Telmisartan was predicted to strongly antagonize (Ki≈0.04nmol the VDR. The ARBs Olmesartan, Irbesartan and Valsartan (Ki≈10 nmol are likely to be useful VDR antagonists at typical in-vivo concentrations. Candesartan (Ki≈30 nmol and Losartan (Ki≈70 nmol may also usefully inhibit the VDR. Telmisartan is a strong modulator of PPARgamma (Ki≈0.3 nmol, while Losartan (Ki≈3 nmol, Irbesartan (Ki≈6 nmol, Olmesartan and Valsartan (Ki≈12 nmol also seem likely to have significant PPAR modulatory activity. Olmesartan andIrbesartan (Ki≈9 nmol additionally act as antagonists of a theoretical modelof CCR2b. Initial validation of this CCR2b model was performed, and a proposed model for the AngiotensinII Type1 receptor (AT2R1 has been presented. Conclusion Molecular modeling has proven valuable to generate testable hypotheses concerning receptor/ligand binding and is an important tool in drug design. ARBs were designed to act as antagonists for AT2R1, and it was not surprising to discover their affinity for the structurally similar CCR2b. However, this study also found evidence that ARBs modulate the

HCN Channels Modulators: The Need for Selectivity

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Romanelli, Maria Novella; Sartiani, Laura; Masi, Alessio; Mannaioni, Guido; Manetti, Dina; Mugelli, Alessandro; Cerbai, Elisabetta

2016-01-01

Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators. PMID:26975509

Selective estrogen receptor modulators and betulinic acid act synergistically to target ERα and SP1 transcription factor dependent Pygopus expression in breast cancer.

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Tzenov, Youlian R; Andrews, Phillip; Voisey, Kim; Gai, Luis; Carter, Beverley; Whelan, Kathryn; Popadiuk, Catherine; Kao, Kenneth R

2016-06-01

Estrogen and progesterone hormone receptor (ER and PR) expression in invasive breast cancer predicts response to hormone disruptive therapy. Pygopus2 (hPYGO2) encodes a chromatin remodelling protein important for breast cancer growth and cell cycle progression. The aims of this study were to determine the mechanism of expression of hPYGO2 in breast cancer and to examine how this expression is affected therapeutically. hPYGO2 and ER protein expression was examined in a breast tumour microarray by immunohistochemistry. hPYGO2 RNA and protein expression was examined in ER+ and ER- breast cancer cell lines in the presence of selective estrogen hormone receptor modulator drugs and the specificity protein-1 (SP1) inhibitor, betulinic acid (BA). The effects of these drugs on the ability for ER and SP1 to bind the hPYGO2 promoter and affect cell cycle progression were studied using chromatin immunoprecipitation assays. hPYGO2 was expressed in seven of eight lines and in nuclei of 98% of 65 breast tumours, including 3 Ductal carcinoma in situ and 62 invasive specimens representing ER-negative (22%) and ER-positive (78%) cases. Treatment with either 4-Hydroxytamoxifen (OHT) or fulvestrant reduced hPYGO2 mRNA 10-fold and protein 5-10-fold within 4 h. Promoter analysis indicated an ER/SP1 binding site at nt -225 to -531 of hPYGO2. SP1 RNA interference and BA reduced hPYGO2 protein and RNA expression by fivefold in both ER- and ER+ cells. Further attenuation was achieved by combining BA and 4-OHT resulting in eightfold reduction in cell growth. Our findings reveal a mechanistic link between hormone signalling and the growth transcriptional programme. The activation of its expression by ERα and/or SP1 suggests hPYGO2 as a theranostic target for hormone therapy responsive and refractory breast cancer. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Peroxisome proliferator-activated receptor α ligands and modulators from dietary compounds: Types, screening methods and functions.

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Yang, Haixia; Xiao, Lei; Wang, Nanping

2017-04-01

Peroxisome proliferator-activated receptor α (PPARα) plays a key role in lipid metabolism and glucose homeostasis and a crucial role in the prevention and treatment of metabolic diseases. Natural dietary compounds, including nutrients and phytochemicals, are PPARα ligands or modulators. High-throughput screening assays have been developed to screen for PPARα ligands and modulators in our diet. In the present review, we discuss recent advances in our knowledge of PPARα, including its structure, function, and ligand and modulator screening assays, and summarize the different types of dietary PPARα ligands and modulators. © 2016 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

Selective Cannabinoid 2 Receptor Stimulation Reduces Tubular Epithelial Cell Damage after Renal Ischemia-Reperfusion Injury.

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Pressly, Jeffrey D; Mustafa, Suni M; Adibi, Ammaar H; Alghamdi, Sahar; Pandey, Pankaj; Roy, Kuldeep K; Doerksen, Robert J; Moore, Bob M; Park, Frank

2018-02-01

Ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI), which is an increasing problem in the clinic and has been associated with elevated rates of mortality. Therapies to treat AKI are currently not available, so identification of new targets that can be modulated to ameliorate renal damage upon diagnosis of AKI is essential. In this study, a novel cannabinoid receptor 2 (CB2) agonist, SMM-295 [3'-methyl-4-(2-(thiophen-2-yl)propan-2-yl)biphenyl-2,6-diol], was designed, synthesized, and tested in vitro and in silico. Molecular docking of SMM-295 into a CB2 active-state homology model showed that SMM-295 interacts well with key amino acids to stabilize the active state. In human embryonic kidney 293 cells, SMM-295 was capable of reducing cAMP production with 66-fold selectivity for CB2 versus cannabinoid receptor 1 and dose-dependently increased mitogen-activated protein kinase and Akt phosphorylation. In vivo testing of the CB2 agonist was performed using a mouse model of bilateral IRI, which is a common model to mimic human AKI, where SMM-295 was immediately administered upon reperfusion of the kidneys after the ischemia episode. Histologic damage assessment 48 hours after reperfusion demonstrated reduced tubular damage in the presence of SMM-295. This was consistent with reduced plasma markers of renal dysfunction (i.e., creatinine and neutrophil gelatinase-associated lipocalin) in SMM-295-treated mice. Mechanistically, kidneys treated with SMM-295 were shown to have elevated activation of Akt with reduced terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine nick-end labeling (TUNEL)-positive cells compared with vehicle-treated kidneys after IRI. These data suggest that selective CB2 receptor activation could be a potential therapeutic target in the treatment of AKI. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

Localisation of selected Ca2+-transport systems in rat's heart and kidney and their modulation by stress

International Nuclear Information System (INIS)

Zacikova, L.

2000-01-01

This thesis deals with the identification of selected calcium transport systems and their modulation by immobilization stress in rat heart and kidney. In our experiments we used normotensive (Sprague-Dawley, Wistar-Kyoto) and hypertensive (SHR) strains. We compared mRNA levels, protein expression and activity of the Na + /Ca 2+ exchanger from hearts of control animals, animals subjected to a single (once) or repeated (seven times) immobilization stress and from animals treated continually with cortisol. We have observed that immobilization stress increased both, gene expression and protein message of the Na + /Ca 2 + exchanger in rat cardiac left, but not right ventricle. This effect is not mediated through the glucocorticoid responsive element. We have found that cortisol decreased activity of the N a +/Ca 2+ exchanger without changing expression and protein amount of this transport system. IP3 receptor of type I and 2 was detected on mRNA levels in rat cardiac atria. Very small amounts of these receptors were observed in rat cardiac ventricles. Since it was difficult to detect these amounts in ventricles, we used 'seminested' PCR to verify expression of IP 3 R1 and 2 in cardiac ventricles. The highest levels of IP 3 R1 and 2 were expressed in left atria. Immobilization stress significantly increased mRNA IP 3 R1 and 2 in rat cardiac atria. We observed both, mRNA and type 1 IP 3 receptor's protein in renal medulla, but not in renal cortex. We have found that this receptor was approximately twice as abundant in normotensive as in genetically hypertensive rat kidney. Immobilization stress significantly down-regulated IP 3 R1 in renal medulla, but not in renal cortex. To investigate the role of NAADP in signaling we measured 45 Ca 2+ release from rat cardiac microsomes. We examined concentration and time dependence of 45 Ca 2+ release from rat cardiac microsomes. All these results could contribute to the understanding of Ca 2+ modulation in cardiac and kidney under

Estrogen effects on angiotensin receptors are modulated by pituitary in female rats

International Nuclear Information System (INIS)

Douglas, J.G.

1987-01-01

The present studies were designed to test the hypothesis that changes in angiotensin II (ANG II) receptors might modulate the layered target tissue responsiveness accompanying estradiol administration. Estradiol was infused continuously in oophorectomized female rats. Aldosterone was also infused in control and experimental animals to avoid estrogen-induced changes in renin and ANG II. ANG II binding constants were determined in radioreceptor assays. Estradiol increased binding site concentration in adrenal glomerulosa by 76% and decreased binding sites of uterine myometrium and glomeruli by 45 and 24%, respectively. There was an accompanying increase in the affinity of ANG II binding to adrenal glomerulosa and uterine myometrium. Because estrogen is a potent stimulus of prolactin release from the pituitary of rodents, studies were also designed to test the hypothesis that prolactin may mediate some or all of the estrogen-induced effects observed. Hypophysectomy abolished estradiol stimulation of prolactin release and most ANG II receptor changes. Prolactin administration to pituitary intact rats was associated with a 50% increase in receptor density of adrenal glomerulosa simulating estradiol administration. However, the changes in glomeruli and uterine myometrium were opposite in that both tissues also increased receptor density, suggesting that prolactin was not the sole mediator of the estrogen-induced receptor changes. In conclusion, regulation of ANG II receptors in a number of diverse target tissues by estradiol is complex with contributions from estrogens and pituitary factors, which include but do not exclusively involve prolactin

Interleukin-1 interaction with neuroregulatory systems: selective enhancement by recombinant human and mouse interleukin-1 of in vitro opioid peptide receptor binding in rat brain

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Wiedermann, C.J.

1989-02-01

Interleukin-1 (IL-1) exerts a wide variety of biological effects on various cell types and may be regarded as a pleiotropic peptide hormone. Biological evidence suggests that IL-1 participates in the modulation of central nervous system physiology and behavior in a fashion characteristic of neuroendocrine hormones. In this investigation, recombinant (r) human (h) IL-1 and r mouse (m) IL-1 were examined for their modulation of opioid peptide receptor binding in vitro. Experiments were performed on frozen sections of rat brain. Receptor binding of radiolabeled substance P and of radiolabeled neurotensin were not significantly affected by the presence of rIL-1s. Recombinant IL-1s, however, significantly enhanced specific binding of 125I-beta-endorphin (125I-beta-END) and of D-ala2-(tyrosyl-3,5-3H)enkephalin-(5-D-leucine) (3H-D-ALA), equipotently and in a concentration-dependent manner with maximal activity occurring at a concentration of 10 LAF units/ml. The increased binding of 125I-beta-END and 3H-D-ALA was blocked steroselectively by (-)-naloxone and by etorphine, suggesting detection of opiate receptors. In addition, brain distribution patterns of receptors labeled in the presence of rIL-1s corresponded to patterns previously published for opiate receptors. Autoradiographic visualization of receptors revealed that rIL-1s in the different areas of the brain exert their effect on opioid binding with comparable potencies. The data suggest that certain central nervous system effects of IL-1s may be mediated by their selective interaction with opiatergic systems at the receptor level.

Honey Bee Allatostatins Target Galanin/Somatostatin-Like Receptors and Modulate Learning: A Conserved Function?

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Elodie Urlacher

Full Text Available Sequencing of the honeybee genome revealed many neuropeptides and putative neuropeptide receptors, yet functional characterization of these peptidic systems is scarce. In this study, we focus on allatostatins, which were first identified as inhibitors of juvenile hormone synthesis, but whose role in the adult honey bee (Apis mellifera brain remains to be determined. We characterize the bee allatostatin system, represented by two families: allatostatin A (Apime-ASTA and its receptor (Apime-ASTA-R; and C-type allatostatins (Apime-ASTC and Apime-ASTCC and their common receptor (Apime-ASTC-R. Apime-ASTA-R and Apime-ASTC-R are the receptors in bees most closely related to vertebrate galanin and somatostatin receptors, respectively. We examine the functional properties of the two honeybee receptors and show that they are transcriptionally expressed in the adult brain, including in brain centers known to be important for learning and memory processes. Thus we investigated the effects of exogenously applied allatostatins on appetitive olfactory learning in the bee. Our results show that allatostatins modulate learning in this insect, and provide important insights into the evolution of somatostatin/allatostatin signaling.

Comparison of P2X and TRPV1 receptors in ganglia or primary culture of trigeminal neurons and their modulation by NGF or serotonin

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Giniatullin Rashid

2006-03-01

Full Text Available Abstract Background Cultured sensory neurons are a common experimental model to elucidate the molecular mechanisms of pain transduction typically involving activation of ATP-sensitive P2X or capsaicin-sensitive TRPV1 receptors. This applies also to trigeminal ganglion neurons that convey pain inputs from head tissues. Little is, however, known about the plasticity of these receptors on trigeminal neurons in culture, grown without adding the neurotrophin NGF which per se is a powerful algogen. The characteristics of such receptors after short-term culture were compared with those of ganglia. Furthermore, their modulation by chronically-applied serotonin or NGF was investigated. Results Rat or mouse neurons in culture mainly belonged to small and medium diameter neurons as observed in sections of trigeminal ganglia. Real time RT-PCR, Western blot analysis and immunocytochemistry showed upregulation of P2X3 and TRPV1 receptors after 1–4 days in culture (together with their more frequent co-localization, while P2X2 ones were unchanged. TRPV1 immunoreactivity was, however, lower in mouse ganglia and cultures. Intracellular Ca2+ imaging and whole-cell patch clamping showed functional P2X and TRPV1 receptors. Neurons exhibited a range of responses to the P2X agonist α, β-methylene-adenosine-5'-triphosphate indicating the presence of homomeric P2X3 receptors (selectively antagonized by A-317491 and heteromeric P2X2/3 receptors. The latter were observed in 16 % mouse neurons only. Despite upregulation of receptors in culture, neurons retained the potential for further enhancement of P2X3 receptors by 24 h NGF treatment. At this time point TRPV1 receptors had lost the facilitation observed after acute NGF application. Conversely, chronically-applied serotonin selectively upregulated TRPV1 receptors rather than P2X3 receptors. Conclusion Comparing ganglia and cultures offered the advantage of understanding early adaptive changes of nociception

Activation of adenosine receptors and inhibition of cyclooxygenases: two recent pharmacological approaches to modulation of radiation suppressed hematopoiesis

International Nuclear Information System (INIS)

Hofer, M.; Pospisil, M.; Vacek, A.; Hola, J.; Weiterova, L.; Streitova, D.; Znojil, V.

2008-01-01

Searching for drugs conforming to requirements for protection and/or treatment of radiation-induced damage belongs to the most important tasks of current radiobiology. In the Laboratory of Experimental Hematology, Institute of Biophysics, v.v.i., Academy of Sciences of the Czech Republic, Brno, Czech Republic, two original approaches for stimulation of radiation-suppressed hematopoiesis have been tested in recent years, namely activation of adenosine receptors and inhibition of cyclooxygenases. Non-selective activation of adenosine receptors, induced by combined administration of dipyridamole, a drug preventing adenosine uptake and supporting thus its extracellular receptor-mediated action, and adenosine monophosphate, an adenosine prodrug, has been found to stimulate hematopoiesis when the drugs were given either pre- or post-irradiation. When synthetic adenosine receptor agonists selective for individual adenosine receptor subtypes were tested, stimulatory effects in myelosuppressed mice have been found after administration of IB-MECA, a selective adenosine A3 receptor agonist. Non-selective cyclooxygenase inhibitors, inhibiting both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), indomethacin, diclofenac, or flurbiprofen, have been observed to act positively on radiation-perturbed hematopoiesis in sublethally irradiated mice. However, their undesirable gastrointestinal side effects have been found to negatively influence survival of lethally irradiated animals. Recently tested selective COX-2 inhibitor meloxicam, preserving protective action of COX-1-synthesized prostaglandins in the gastrointestinal tissues, has been observed to retain the hematopoiesis-stimulating effects of non-selective cyclooxygenase inhibitors and to improve the survival of animals exposed to lethal radiation doses. These findings bear evidence for the possibility to use selective adenosine A3 receptor agonists and selective COX-2 inhibitors in human practice for treatment of

Prediction of selective estrogen receptor beta agonist using open data and machine learning approach

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Niu AQ

2016-07-01

for the classification of selective ER-β agonists. Chemistry Development Kit extended fingerprints and MACCS fingerprint performed better in structural representation between active and inactive agonists. Conclusion: These results demonstrate that combining the fingerprint and ML approaches leads to robust ER-β agonist prediction models, which are potentially applicable to the identification of selective ER-β agonists. Keywords: estrogen receptor subtype β, selective estrogen receptor modulators, quantitative structure-activity relationship models, machine learning approach

GLPG0492, a novel selective androgen receptor modulator, improves muscle performance in the exercised-mdx mouse model of muscular dystrophy.

Science.gov (United States)

Cozzoli, Anna; Capogrosso, Roberta Francesca; Sblendorio, Valeriana Teresa; Dinardo, Maria Maddalena; Jagerschmidt, Catherine; Namour, Florence; Camerino, Giulia Maria; De Luca, Annamaria

2013-06-01

Anabolic drugs may counteract muscle wasting and dysfunction in Duchenne muscular dystrophy (DMD); however, steroids have unwanted side effects. We focused on GLPG0492, a new non-steroidal selective androgen receptor modulator that is currently under development for musculo-skeletal diseases such as sarcopenia and cachexia. GLPG0492 was tested in the exercised mdx mouse model of DMD in a 4-week trial at a single high dose (30 mg/kg, 6 day/week s.c.), and the results were compared with those from the administration of α-methylprednisolone (PDN; 1 mg/kg, i.p.) and nandrolone (NAND, 5 mg/kg, s.c.). This assessment was followed by a 12-week dose-dependence study (0.3-30 mg/kg s.c.). The outcomes were evaluated in vivo and ex vivo on functional, histological and biochemical parameters. Similar to PDN and NAND, GLPG0492 significantly increased mouse strength. In acute exhaustion tests, a surrogate of the 6-min walking test used in DMD patients, GLPG0492 preserved running performance, whereas vehicle- or comparator-treated animals showed a significant increase in fatigue (30-50%). Ex vivo, all drugs resulted in a modest but significant increase of diaphragm force. In parallel, a decrease in the non-muscle area and markers of fibrosis was observed in GLPG0492- and NAND-treated mice. The drugs exerted minor effects on limb muscles; however, electrophysiological biomarkers were ameliorated in extensor digitorum longus muscle. The longer dose-dependence study confirmed the effect on mdx mouse strength and resistance to fatigue and demonstrated the efficacy of lower drug doses on in vivo and ex vivo functional parameters. These results support the interest of further studies of GLPG0492 as a potential treatment for DMD. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chronic effects of fluoxetine, a selective inhibitor of serotonin uptake, on neurotransmitter receptors

International Nuclear Information System (INIS)

Wong, D.T.; Reid, L.R.; Bymaster, F.P.; Threlkeld, P.G.

1985-01-01

Fluoxetine administration to rats dose of 10mg/kg i.p. daily up to 12 or 24 days failed to change the concentration-dependent binding of [ 3 H]WB4101, [ 3 H]clonidine and [ 3 H]dihydroalprenolol to α 1 -, α 2 - and β-adrenergic receptors, respectively; [ 3 H]quinuclidinyl benzilate to muscarinic receptors; [ 3 H]pyrilamine to histamine H 1 receptors and [ 3 H]naloxone to opiate receptors. Persistent and significant decreases in receptor number (Bsub(max) value) without changes in the dissociation constant (Ksub(D) value) of [ 3 H]5-HT binding in cortical membranes were observed upon chronic treatment with fluoxetine administered either by intraperitoneal injection or incorporation in the diet. A detectable reduction of 5-HT 1 receptor number occured after once-daily injections of fluoxetine at 10mg/kg i.p. within 49 hours. After pretreatment for 3 days with p-chlorophenylalanine, an inhibitor of 5-HT synthesis, followed by repeated administration of fluoxetine, 5-HT 1 receptor numbers were higher than those of normal rats, suggesting a dependence on synaptic concentration of 5-HT for fluoxetine to affect a receptor down-regulation. These studies provide further evidence for the selectivity of fluoxetine as an inhibitor of 5-HT reuptake, resulting in a selective down-regulation of 5-HT 1 receptors in the cerebal cortex of rat brain. (Author)

Site-directed alkylation of multiple opioid receptors. I. Binding selectivity

International Nuclear Information System (INIS)

James, I.F.; Goldstein, A.

1984-01-01

A method for measuring and expressing the binding selectivity of ligands for mu, delta, and kappa opioid binding sites is reported. Radioligands are used that are partially selective for these sites in combination with membrane preparations enriched in each site. Enrichment was obtained by treatment of membranes with the alkylating agent beta-chlornaltrexamine in the presence of appropriate protecting ligands. After enrichment for mu receptors, [ 3 H] dihydromorphine bound to a single type of site as judged by the slope of competition binding curves. After enrichment for delta or kappa receptors, binding sites for [ 3 H] [D-Ala2, D-Leu5]enkephalin and [3H]ethylketocyclazocine, respectively, were still not homogeneous. There were residual mu sites in delta-enriched membranes but no evidence for residual mu or delta sites in kappa-enriched membranes were found. This method was used to identify ligands that are highly selective for each of the three types of sites

Modulation of Central Synapses by Astrocyte-Released ATP and Postsynaptic P2X Receptors

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Eric Boué-Grabot

2017-01-01

Full Text Available Communication between neuronal and glial cells is important for neural plasticity. P2X receptors are ATP-gated cation channels widely expressed in the brain where they mediate action of extracellular ATP released by neurons and/or glia. Recent data show that postsynaptic P2X receptors underlie slow neuromodulatory actions rather than fast synaptic transmission at brain synapses. Here, we review these findings with a particular focus on the release of ATP by astrocytes and the diversity of postsynaptic P2X-mediated modulation of synaptic strength and plasticity in the CNS.

GABAA receptor: Positive and negative allosteric modulators.

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Olsen, Richard W

2018-01-31

gamma-Aminobutyric acid (GABA)-mediated inhibitory neurotransmission and the gene products involved were discovered during the mid-twentieth century. Historically, myriad existing nervous system drugs act as positive and negative allosteric modulators of these proteins, making GABA a major component of modern neuropharmacology, and suggesting that many potential drugs will be found that share these targets. Although some of these drugs act on proteins involved in synthesis, degradation, and membrane transport of GABA, the GABA receptors Type A (GABA A R) and Type B (GABA B R) are the targets of the great majority of GABAergic drugs. This discovery is due in no small part to Professor Norman Bowery. Whereas the topic of GABA B R is appropriately emphasized in this special issue, Norman Bowery also made many insights into GABA A R pharmacology, the topic of this article. GABA A R are members of the ligand-gated ion channel receptor superfamily, a chloride channel family of a dozen or more heteropentameric subtypes containing 19 possible different subunits. These subtypes show different brain regional and subcellular localization, age-dependent expression, and potential for plastic changes with experience including drug exposure. Not only are GABA A R the targets of agonist depressants and antagonist convulsants, but most GABA A R drugs act at other (allosteric) binding sites on the GABA A R proteins. Some anxiolytic and sedative drugs, like benzodiazepine and related drugs, act on GABA A R subtype-dependent extracellular domain sites. General anesthetics including alcohols and neurosteroids act at GABA A R subunit-interface trans-membrane sites. Ethanol at high anesthetic doses acts on GABA A R subtype-dependent trans-membrane domain sites. Ethanol at low intoxicating doses acts at GABA A R subtype-dependent extracellular domain sites. Thus GABA A R subtypes possess pharmacologically specific receptor binding sites for a large group of different chemical classes of

Modulation of the constitutive activity of the ghrelin receptor by use of pharmacological tools and mutagenesis

DEFF Research Database (Denmark)

Mokrosinski, Jacek; Holst, Birgitte

2010-01-01

Ghrelin and its receptor are important regulators of metabolic functions, including appetite, energy expenditure, fat accumulation, and growth hormone (GH) secretion. The ghrelin receptor is characterized by an ability to signal even without any ligand present with approximately 50......% of the maximally ghrelin-induced efficacy-a feature that may have important physiological implications. The high basal signaling can be modulated either by administration of specific ligands or by engineering of mutations in the receptor structure. [D-Arg(1), D-Phe(5), D-Trp(7,9), Leu(11)]-substance P...... was the first inverse agonist to be identified for the ghrelin receptor, and this peptide has been used as a starting point for identification of the structural requirements for inverse agonist properties in the ligand. The receptor binding core motif was identified as D-Trp-Phe-D-Trp-Leu-Leu, and elongation...

Proteome-wide muscle protein fractional synthesis rates predict muscle mass gain in response to a selective androgen receptor modulator in rats.

Science.gov (United States)

Shankaran, Mahalakshmi; Shearer, Todd W; Stimpson, Stephen A; Turner, Scott M; King, Chelsea; Wong, Po-Yin Anne; Shen, Ying; Turnbull, Philip S; Kramer, Fritz; Clifton, Lisa; Russell, Alan; Hellerstein, Marc K; Evans, William J

2016-03-15

Biomarkers of muscle protein synthesis rate could provide early data demonstrating anabolic efficacy for treating muscle-wasting conditions. Androgenic therapies have been shown to increase muscle mass primarily by increasing the rate of muscle protein synthesis. We hypothesized that the synthesis rate of large numbers of individual muscle proteins could serve as early response biomarkers and potentially treatment-specific signaling for predicting the effect of anabolic treatments on muscle mass. Utilizing selective androgen receptor modulator (SARM) treatment in the ovariectomized (OVX) rat, we applied an unbiased, dynamic proteomics approach to measure the fractional synthesis rates (FSR) of 167-201 individual skeletal muscle proteins in triceps, EDL, and soleus. OVX rats treated with a SARM molecule (GSK212A at 0.1, 0.3, or 1 mg/kg) for 10 or 28 days showed significant, dose-related increases in body weight, lean body mass, and individual triceps but not EDL or soleus weights. Thirty-four out of the 94 proteins measured from the triceps of all rats exhibited a significant, dose-related increase in FSR after 10 days of SARM treatment. For several cytoplasmic proteins, including carbonic anhydrase 3, creatine kinase M-type (CK-M), pyruvate kinase, and aldolase-A, a change in 10-day FSR was strongly correlated (r(2) = 0.90-0.99) to the 28-day change in lean body mass and triceps weight gains, suggesting a noninvasive measurement of SARM effects. In summary, FSR of multiple muscle proteins measured by dynamics of moderate- to high-abundance proteins provides early biomarkers of the anabolic response of skeletal muscle to SARM. Copyright © 2016 the American Physiological Society.

Decision framework of photovoltaic module selection under interval-valued intuitionistic fuzzy environment

International Nuclear Information System (INIS)

Long, Shengping; Geng, Shuai

2015-01-01

Highlights: • The evaluation index system is set by the engineering and supply chain perspectives. • The interval-valued intuitionistic fuzzy set (IVIFS) to express the performances. • The IVIFS entropy weight method is applied to improve the objectivity of weights. - Abstract: The selection of appropriate photovoltaic module is of extremely high importance for the solar power station project; however the comprehensive problem of evaluation index system, the information loss problem and the lack-objectivity problem in the selection process will decrease the reasonability of the selection result. The innovation points of this paper are as follows: first, the comprehensive evaluation index system of photovoltaic module is established from the engineering management and supply chain management perspectives to solve the comprehensive problem; second, the interval-valued intuitionistic fuzzy set (IVIFS) are introduced into the photovoltaic modules selection process to express the alternatives’ performances to solve the information loss problem; third, the IVIFS entropy weight method is applied to improve the objectivity of the criteria’s weights. According to the aforementioned solutions, the decision framework of photovoltaic module selection under interval-valued intuitionistic fuzzy environment are established and used in a case study to demonstrate its effectiveness. Therefore, from the theoretical modeling and empirical demonstration, the decision framework proposed in this paper can effectively handle such a complicated problem and lead to an outstanding result.

Triton X-100 inhibits agonist-induced currents and suppresses benzodiazepine modulation of GABA(A) receptors in Xenopus oocytes

DEFF Research Database (Denmark)

Søgaard, Rikke; Ebert, Bjarke; Klaerke, Dan

2009-01-01

Changes in lipid bilayer elastic properties have been proposed to underlie the modulation of voltage-gated Na(+) and L-type Ca(2+) channels and GABA(A) receptors by amphiphiles. The amphiphile Triton X-100 increases the elasticity of lipid bilayers at micromolar concentrations, assessed from its...... by flunitrazepam at alpha(1)beta(3)gamma(2S) receptors. All effects were independent of the presence of a gamma(2S) subunit in the GABA(A) receptor complex. The present study suggests that Triton X-100 may stabilize open and desensitized states of the GABA(A) receptor through changes in lipid bilayer elasticity....

CITED2 modulates estrogen receptor transcriptional activity in breast cancer cells

International Nuclear Information System (INIS)

Lau, Wen Min; Doucet, Michele; Huang, David; Weber, Kristy L.; Kominsky, Scott L.

2013-01-01

Highlights: •The effects of elevated CITED2 on ER function in breast cancer cells are examined. •CITED2 enhances cell growth in the absence of estrogen and presence of tamoxifen. •CITED2 functions as a transcriptional co-activator of ER in breast cancer cells. -- Abstract: Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (CITED2) is a member of the CITED family of non-DNA binding transcriptional co-activators of the p300/CBP-mediated transcription complex. Previously, we identified CITED2 as being overexpressed in human breast tumors relative to normal mammary epithelium. Upon further investigation within the estrogen receptor (ER)-positive subset of these breast tumor samples, we found that CITED2 mRNA expression was elevated in those associated with poor survival. In light of this observation, we investigated the effect of elevated CITED2 levels on ER function. While ectopic overexpression of CITED2 in three ER-positive breast cancer cell lines (MCF-7, T47D, and CAMA-1) did not alter cell proliferation in complete media, growth was markedly enhanced in the absence of exogenous estrogen. Correspondingly, cells overexpressing CITED2 demonstrated reduced sensitivity to the growth inhibitory effects of the selective estrogen receptor modulator, 4-hydroxytamoxifen. Subsequent studies revealed that basal ER transcriptional activity was elevated in CITED2-overexpressing cells and was further increased upon the addition of estrogen. Similarly, basal and estrogen-induced expression of the ER-regulated genes trefoil factor 1 (TFF1) and progesterone receptor (PGR) was higher in cells overexpressing CITED2. Concordant with this observation, ChIP analysis revealed higher basal levels of CITED2 localized to the TFF-1 and PGR promoters in cells with ectopic overexpression of CITED2, and these levels were elevated further in response to estrogen stimulation. Taken together, these data indicate that CITED2 functions as a transcriptional co

Cannabinoids Modulate Neuronal Activity and Cancer by CB1 and CB2 Receptor-Independent Mechanisms

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Ken Soderstrom

2017-10-01

Full Text Available Cannabinoids include the active constituents of Cannabis or are molecules that mimic the structure and/or function of these Cannabis-derived molecules. Cannabinoids produce many of their cellular and organ system effects by interacting with the well-characterized CB1 and CB2 receptors. However, it has become clear that not all effects of cannabinoid drugs are attributable to their interaction with CB1 and CB2 receptors. Evidence now demonstrates that cannabinoid agents produce effects by modulating activity of the entire array of cellular macromolecules targeted by other drug classes, including: other receptor types; ion channels; transporters; enzymes, and protein- and non-protein cellular structures. This review summarizes evidence for these interactions in the CNS and in cancer, and is organized according to the cellular targets involved. The CNS represents a well-studied area and cancer is emerging in terms of understanding mechanisms by which cannabinoids modulate their activity. Considering the CNS and cancer together allow identification of non-cannabinoid receptor targets that are shared and divergent in both systems. This comparative approach allows the identified targets to be compared and contrasted, suggesting potential new areas of investigation. It also provides insight into the diverse sources of efficacy employed by this interesting class of drugs. Obtaining a comprehensive understanding of the diverse mechanisms of cannabinoid action may lead to the design and development of therapeutic agents with greater efficacy and specificity for their cellular targets.

Possible role of IGF2 receptors in regulating selection of 2 dominant follicles in cattle selected for twin ovulations and births

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Abundance of IGF-2 receptor (IGF2R), FSH receptor (FSHR), and LH receptor (LHCGR) mRNA in granulosa cells (GCs) or theca cells (TCs) or both cells as well as estradiol (E2), progesterone (P4), and androstenedione concentrations in follicular fluid were compared in cows genetically selected (Twinner)...

Deprivation selectively modulates brain potentials to food pictures.

Science.gov (United States)

Stockburger, Jessica; Weike, Almut I; Hamm, Alfons O; Schupp, Harald T

2008-08-01

Event-related brain potentials (ERPs) were used to examine whether the processing of food pictures is selectively modulated by changes in the motivational state of the observer. Sixteen healthy male volunteers were tested twice 1 week apart, either after 24 hr of food deprivation or after normal food intake. ERPs were measured while participants viewed appetitive food pictures as well as standard emotional and neutral control pictures. Results show that the ERPs to food pictures in a hungry, rather than satiated, state were associated with enlarged positive potentials over posterior sensor sites in a time window of 170-310 ms poststimulus. Minimum-norm analysis suggests the enhanced processing of food cues primarily in occipito-temporo-parietal regions. In contrast, processing of standard emotional and neutral pictures was not modulated by food deprivation. Considered from the perspective of motivated attention, the selective change of food cue processing may reflect a state-dependent change in stimulus salience.

A SELECTIVE ANTAGONIST OF MINERALOCORTICOID RECEPTOR EPLERENONE IN CARDIOLOGY PRACTICE

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B. B. Gegenava

2015-01-01

Full Text Available The role of aldosterone in pathophysiological processes is considered. The effects of the selective antagonist of mineralocorticoid receptor eplerenone are analyzed. The advantages of eplerenone compared with spironolactone are discussed.

Protein kinase A mediates adenosine A2a receptor modulation of neurotransmitter release via synapsin I phosphorylation in cultured cells from medulla oblongata.

Science.gov (United States)

Matsumoto, Joao Paulo Pontes; Almeida, Marina Gomes; Castilho-Martins, Emerson Augusto; Costa, Maisa Aparecida; Fior-Chadi, Debora Rejane

2014-08-01

Synaptic transmission is an essential process for neuron physiology. Such process is enabled in part due to modulation of neurotransmitter release. Adenosine is a synaptic modulator of neurotransmitter release in the Central Nervous System, including neurons of medulla oblongata, where several nuclei are involved with neurovegetative reflexes. Adenosine modulates different neurotransmitter systems in medulla oblongata, specially glutamate and noradrenaline in the nucleus tractussolitarii, which are involved in hypotensive responses. However, the intracellular mechanisms involved in this modulation remain unknown. The adenosine A2a receptor modulates neurotransmitter release by activating two cAMP protein effectors, the protein kinase A and the exchange protein activated by cAMP. Therefore, an in vitro approach (cultured cells) was carried out to evaluate modulation of neurotransmission by adenosine A2a receptor and the signaling intracellular pathway involved. Results show that the adenosine A2a receptor agonist, CGS 21680, increases neurotransmitter release, in particular, glutamate and noradrenaline and such response is mediated by protein kinase A activation, which in turn increased synapsin I phosphorylation. This suggests a mechanism of A2aR modulation of neurotransmitter release in cultured cells from medulla oblongata of Wistar rats and suggest that protein kinase A mediates this modulation of neurotransmitter release via synapsin I phosphorylation. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

A New Selective Harmonic Elimination Pulse- Width and Amplitude Modulation (SHEPWAM) for Drive Applications

DEFF Research Database (Denmark)

Ghoreishy, Hoda; Varjani, Ali Yazdian; Mohamadian, Mustafa

2013-01-01

Compared to the conventional selective harmonic elimination-pulse width modulation (SHE-PWM), the selective harmonic elimination-pulse width and amplitude modulation (SHE-PWAM) control strategy results in significant improvements in the performance of CHB inverters. This fact is due to considerin...

Subregion-specific modulation of excitatory input and dopaminergic output in the striatum by tonically activated glycine and GABAA receptors

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Louise eAdermark

2011-10-01

Full Text Available The flow of cortical information through the basal ganglia is a complex spatiotemporal pattern of increased and decreased firing. The striatum is the biggest input nucleus to the basal ganglia and the aim of this study was to assess the role of inhibitory GABAA and glycine receptors in regulating synaptic activity in the dorsolateral (DLS and ventral striatum (nucleus accumbens, nAc. Local field potential recordings from coronal brain slices of juvenile and adult Wistar rats showed that GABAA receptors and strychnine-sensitive glycine receptors are tonically activated and inhibit excitatory input to the DLS and to the nAc. Strychnine-induced disinhibition of glutamatergic transmission was insensitive to the muscarinic receptor inhibitor scopolamine (10 µM, inhibited by the nicotinic acetylcholine receptor antagonist mecamylamine (10 µM and blocked by GABAA receptor inhibitors, suggesting that tonically activated glycine receptors depress excitatory input to the striatum through modulation of cholinergic and GABAergic neurotransmission. As an end-product example of striatal GABAergic output in vivo we measured dopamine release in the DLS and nAc by microdialysis in the awake and freely moving rat. Reversed dialysis of bicuculline (50 μM in perfusate only increased extrasynaptic dopamine levels in the nAc, while strychnine administered locally (200 μM in perfusate decreased dopamine output by 60% in both the DLS and nAc. Our data suggest that GABAA and glycine receptors are tonically activated and modulate striatal transmission in a partially sub-region specific manner.

GABAA receptor partial agonists and antagonists

DEFF Research Database (Denmark)

Krall, Jacob; Balle, Thomas; Krogsgaard-Larsen, Niels

2015-01-01

to the local temporal pattern of GABA impact, enabling phasic or tonic inhibition. Specific GABAAR antagonists are essential tools for physiological and pharmacological elucidation of the different type of GABAAR inhibition. However, distinct selectivity among the receptor subtypes (populations) has been shown...... antagonists have been essential in defining the tonic current but both remaining issues concerning the GABAARs involved and the therapeutic possibilities of modulating tonic inhibition underline the need for GABAAR antagonists with improved selectivity....

Selective autophagy of non-ubiquitylated targets in plants: looking for cognate receptor/adaptor proteins

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Vasko eVeljanovski

2014-06-01

Full Text Available Cellular homeostasis is essential for the physiology of eukaryotic cells. Eukaryotic cells, including plant cells, utilize two main pathways to adjust the level of cytoplasmic components, namely the proteasomal and the lysosomal/vacuolar pathways. Macroautophagy is a lysosomal/vacuolar pathway which, until recently, was thought to be non-specific and a bulk degradation process. However, selective autophagy which can be activated in the cell under various physiological conditions, involves the specific degradation of defined macromolecules or organelles by a conserved molecular mechanism. For this process to be efficient, the mechanisms underlying the recognition and selection of the cargo to be engulfed by the double-membrane autophagosome are critical, and not yet well understood. Ubiquitin (poly-ubiquitin conjugation to the target appears to be a conserved ligand mechanism in many types of selective autophagy, and defined receptors/adaptors recognizing and regulating the autophagosomal capture of the ubiquitylated target have been characterized. However, non-proteinaceous and non-ubiquitylated cargoes are also selectively degraded by this pathway. This ubiquitin-independent selective autophagic pathway also involves receptor and/or adaptor proteins linking the cargo to the autophagic machinery. Some of these receptor/adaptor proteins including accessory autophagy-related (Atg and non-Atg proteins have been described in yeast and animal cells but not yet in plants. In this review we discuss the ubiquitin-independent cargo selection mechanisms in selective autophagy degradation of organelles and macromolecules and speculate on potential plant receptor/adaptor proteins.

Development of a human vasopressin V1a-receptor antagonist from an evolutionary-related insect neuropeptide

DEFF Research Database (Denmark)

Di Giglio, Maria Giulia; Muttenthaler, Markus; Harpsøe, Kasper

2017-01-01

Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary...

A peptide targeting an interaction interface disrupts the dopamine D1-D2 receptor heteromer to block signaling and function in vitro and in vivo: effective selective antagonism

Science.gov (United States)

Hasbi, Ahmed; Perreault, Melissa L.; Shen, Maurice Y. F.; Zhang, Lucia; To, Ryan; Fan, Theresa; Nguyen, Tuan; Ji, Xiaodong; O'Dowd, Brian F.; George, Susan R.

2014-01-01

Although the dopamine D1-D2 receptor heteromer has emerging physiological relevance and a postulated role in different neuropsychiatric disorders, such as drug addiction, depression, and schizophrenia, there is a need for pharmacological tools that selectively target such receptor complexes in order to analyze their biological and pathophysiological functions. Since no selective antagonists for the D1-D2 heteromer are available, serial deletions and point mutations were used to precisely identify the amino acids involved in an interaction interface between the receptors, residing within the carboxyl tail of the D1 receptor that interacted with the D2 receptor to form the D1-D2 receptor heteromer. It was determined that D1 receptor carboxyl tail residues 404Glu and 405Glu were critical in mediating the interaction with the D2 receptor. Isolated mutation of these residues in the D1 receptor resulted in the loss of agonist activation of the calcium signaling pathway mediated through the D1-D2 receptor heteromer. The physical interaction between the D1 and D2 receptor could be disrupted, as shown by coimmunoprecipitation and BRET analysis, by a small peptide generated from the D1 receptor sequence that contained these amino acids, leading to a switch in G-protein affinities and loss of calcium signaling, resulting in the inhibition of D1-D2 heteromer function. The use of the D1-D2 heteromer-disrupting peptide in vivo revealed a pathophysiological role for the D1-D2 heteromer in the modulation of behavioral despair. This peptide may represent a novel pharmacological tool with potential therapeutic benefits in depression treatment.—Hasbi, A., Perreault, M. L., Shen, M. Y. F., Zhang, L., To, R., Fan, T., Nguyen, T., Ji, X., O'Dowd, B. F., George, S. R. A peptide targeting an interaction interface disrupts the dopamine D1-D2 receptor heteromer to block signaling and function in vitro and in vivo: effective selective antagonism. PMID:25063849

Gs protein peptidomimetics as allosteric modulators of the β2-adrenergic receptor

DEFF Research Database (Denmark)

Boyhus, Lotte Emilie; Danielsen, Mia; Bengtson, Nina Smidt

2018-01-01

A series of Gs protein peptidomimetics were designed and synthesised based on the published X-ray crystal structure of the active state β2-Adrenergic receptor (β2AR) in complex with the Gs protein (PDB 3SN6). We hypothesised that such peptidomimetics may function as allosteric modulators...... that target the intracellular Gs protein binding site of the β2AR. Peptidomimetics were designed to mimic the 15 residue C-Terminal α-helix of the Gs protein and were pre-organised in a helical conformation by (i, i + 4)-stapling using copper catalysed azide alkyne cycloaddition. Linear and stapled...... be able to compete with the native Gs protein for the intracellular binding site to block ISO-induced cAMP formation, but are unable to stabilise an active-like receptor conformation....

1H-cyclopentapyrimidine-2,4(1H,3H)-dione-related ionotropic glutamate receptors ligands. Structure-activity relationships and identification of potent and selective iGluR5 modulators

DEFF Research Database (Denmark)

Butini, Stefania; Pickering, Darryl S; Morelli, Elena

2008-01-01

(S)-CPW399 ((S)-1) is a potent and excitotoxic AMPA receptor partial agonist. Modifying the cyclopentane ring of (S)-1, we developed two of the most potent and selective functional antagonists (5 and 7) for kainate receptor (KA-R) subunit iGluR5. Derivatives 5 and 7, with their unique pharmacolog...

Piracetam defines a new binding site for allosteric modulators of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors.

Science.gov (United States)

Ahmed, Ahmed H; Oswald, Robert E

2010-03-11

Glutamate receptors are the most prevalent excitatory neurotransmitter receptors in the vertebrate central nervous system and are important potential drug targets for cognitive enhancement and the treatment of schizophrenia. Allosteric modulators of AMPA receptors promote dimerization by binding to a dimer interface and reducing desensitization and deactivation. The pyrrolidine allosteric modulators, piracetam and aniracetam, were among the first of this class of drugs to be discovered. We have determined the structure of the ligand binding domain of the AMPA receptor subtypes GluA2 and GluA3 with piracetam and a corresponding structure of GluA3 with aniracetam. Both drugs bind to GluA2 and GluA3 in a very similar manner, suggesting little subunit specificity. However, the binding sites for piracetam and aniracetam differ considerably. Aniracetam binds to a symmetrical site at the center of the dimer interface. Piracetam binds to multiple sites along the dimer interface with low occupation, one of which is a unique binding site for potential allosteric modulators. This new site may be of importance in the design of new allosteric regulators.

Effects of the dopamine D2 allosteric modulator, PAOPA, on the expression of GRK2, arrestin-3, ERK1/2, and on receptor internalization.

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Dipannita Basu

Full Text Available The activity of G protein-coupled receptors (GPCRs is intricately regulated by a range of intracellular proteins, including G protein-coupled kinases (GRKs and arrestins. Understanding the effects of ligands on these signaling pathways could provide insights into disease pathophysiologies and treatment. The dopamine D2 receptor is a GPCR strongly implicated in the pathophysiology of a range of neurological and neuropsychiatric disorders, particularly schizophrenia. Previous studies from our lab have shown the preclinical efficacy of a novel allosteric drug, 3(R-[(2(S-pyrrolidinylcarbonylamino]-2-oxo-1-pyrrolidineacetamide (PAOPA, in attenuating schizophrenia-like behavioural abnormalities in rodent models of the disease. As an allosteric modulator, PAOPA binds to a site on the D2 receptor, which is distinct from the endogenous ligand-binding site, in order to modulate the binding of the D2 receptor ligand, dopamine. The exact signaling pathways affected by this allosteric modulator are currently unknown. The objectives of this study were to decipher the in vivo effects, in rats, of chronic PAOPA administration on D2 receptor regulatory and downstream molecules, including GRK2, arrestin-3 and extracellular receptor kinase (ERK 1/2. Additionally, an in vitro cellular model was also used to study PAOPA's effects on D2 receptor internalization. Results from western immunoblots showed that chronic PAOPA treatment increased the striatal expression of GRK2 by 41%, arrestin-3 by 34%, phospho-ERK1 by 51% and phospho-ERK2 by 36%. Results also showed that the addition of PAOPA to agonist treatment in cells increased D2 receptor internalization by 33%. This study provides the foundational evidence of putative signaling pathways, and changes in receptor localization, affected by treatment with PAOPA. It improves our understanding on the diverse mechanisms of action of allosteric modulators, while advancing PAOPA's development into a novel drug for the

Role of Killer Immunoglobulin-Like Receptor and Ligand Matching in Donor Selection

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Meral Beksaç

2012-01-01

Full Text Available Despite all efforts to improve HLA typing and immunosuppression, it is still impossible to prevent severe graft versus host disease (GVHD which can be fatal. GVHD is not always associated with graft versus malignancy and can prevent stem cell transplantation from reaching its goals. Overall T-cell alloreactivity is not the sole mechanism modulating the immune defense. Innate immune system has its own antigens, ligands, and mediators. The bridge between HLA and natural killer (NK cell-mediated reactions is becoming better understood in the context of stem cell transplantation. Killer immunoglobulin-like receptors (KIRs constitute a wide range of alleles/antigens segregated independently from the HLA alleles and classified into two major haplotypes which imprints the person's ability to suppress or to amplify T-cell alloreactivity. This paper will summarize the impact of both activating and inhibitory KIRs and their ligands on stem cell transplantation outcome. The ultimate goal is to develop algorithms based on KIR profiles to select donors with maximum antileukemic and minimum antihost effects.

The folate receptor as a molecular target for tumor-selective radionuclide delivery

International Nuclear Information System (INIS)

Ke, C.-Y.; Mathias, Carla J.; Green, Mark A.

2003-01-01

The cell-membrane folate receptor is a potential molecular target for tumor-selective drug delivery, including radiolabeled folate-chelate conjugates for diagnostic imaging. We review here some background on the folate receptor as tumor-associated molecular target for drug delivery, and briefly survey the literature on tumor-targeting with radiolabeled folate-chelate conjugates

Selection History Modulates Working Memory Capacity

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Bo-Cheng Kuo

2016-10-01

Full Text Available Recent studies have shown that past selection history affects the allocation of attention on target selection. However, it is unclear whether context-driven selection history can modulate the efficacy of attention allocation on working memory (WM representations. This study tests the influences of selection history on WM capacity. A display of one item (low load or three/four items (high load was shown for the participants to hold in WM in a delayed response task. Participants then judged whether a probe item was in the memory display or not. Selection history was defined as the number of items attended across trials in the task context within a block, manipulated by the stimulus set-size in the contexts with fewer possible stimuli (4-item or 5-item context or more possible stimuli (8-item or 9-item context from which the memorized content was selected. The capacity measure (i.e. the K parameter was estimated to reflect the number of items that can be held in WM. Across four behavioral experiments, the results revealed that the capacity was significantly reduced in the context with more possible stimuli relative to the context with fewer possible stimuli. Moreover, the reduction in capacity was significant for high WM load and not observed when the focus was on only a single item. Together, these findings indicate that context-driven selection history and focused attention influence WM capacity.

Selectivity of natural, synthetic and environmental estrogens for zebrafish estrogen receptors

Energy Technology Data Exchange (ETDEWEB)

Pinto, Caroline [Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5056 (United States); Grimaldi, Marina; Boulahtouf, Abdelhay [Institut de Recherche en Cancérologie de Montpellier, Institut National de la Santé de la Recherche Médicale U896, Institut Régional de Cancérologie de Montpellier, Université Montpellier 1, 34298 Montpellier (France); Pakdel, Farzad [Institut de Recherche sur la Santé, Environnement et Travail (IRSET), INSERM U1085, Université de Rennes 1, Rennes (France); Brion, François; Aït-Aïssa, Sélim [Unité Écotoxicologie In Vitro et In Vivo, INERIS, Parc ALATA, 60550 Verneuil-en-Halatte (France); Cavaillès, Vincent [Institut de Recherche en Cancérologie de Montpellier, Institut National de la Santé de la Recherche Médicale U896, Institut Régional de Cancérologie de Montpellier, Université Montpellier 1, 34298 Montpellier (France); Bourguet, William [U1054, Centre de Biochimie Structurale, CNRS UMR5048, Université Montpellier 1 et 2, 34290 Montpellier (France); Gustafsson, Jan-Ake [Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5056 (United States); Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge (Sweden); and others

2014-10-01

Zebrafish, Danio rerio, is increasingly used as an animal model to study the effects of pharmaceuticals and environmental estrogens. As most of these estrogens have only been tested on human estrogen receptors (ERs), it is necessary to measure their effects on zebrafish ERs. In humans there are two distinct nuclear ERs (hERα and hERβ), whereas the zebrafish genome encodes three ERs, zfERα and two zfERβs (zfERβ1 and zfERβ2). In this study, we established HeLa-based reporter cell lines stably expressing each of the three zfERs. We first reported that estrogens more efficiently activate the zfERs at 28 °C as compared to 37 °C, thus reflecting the physiological temperature of zebrafish in wildlife. We then showed significant differences in the ability of agonist and antagonist estrogens to modulate activation of the three zfER isotypes in comparison to hERs. Environmental compounds (bisphenol A, alkylphenols, mycoestrogens) which are hER panagonists and hERβ selective agonists displayed greater potency for zfERα as compared to zfERβs. Among hERα selective synthetic agonists, PPT did not activate zfERα while 16α-LE2 was the most zfERα selective compound. Altogether, these results confirm that all hER ligands control in a similar manner the transcriptional activity of zfERs although significant differences in selectivity were observed among subtypes. The zfER subtype selective ligands that we identified thus represent new valuable tools to dissect the physiological roles of the different zfERs. Finally, our work also points out that care has to be taken in transposing the results obtained using the zebrafish as a model for human physiopathology. - Highlights: • Zebrafish is increasingly used to study the effects of estrogens. • We assessed the activity of pharmaceutical and environmental estrogens on zfERs. • Environmental estrogens displayed greater potency for zfERα compared to zfERβs. • hERβ selective agonists displayed greater potency for zf

Modulation of Rhamm (CD168) for selective adipose tissue development

Science.gov (United States)

Turley, Eva A; Bissell, Mina J

2014-05-06

Herein is described the methods and compositions for modulation of Rhamm, also known as CD 186, and its effects on wound repair, muscle differentiation, bone density and adipogeneisis through its ability to regulate mesenchymal stem cell differentiation. Compositions and methods are provided for blocking Rhamm function for selectively increasing subcutaneous, but not, visceral fat. Compositions and methods for modulating Rhamm in wound repair are also described.

Sex-dependent anti-stress effect of an α5 subunit containing GABAA receptor positive allosteric modulator

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Sean C. Piantadosi

2016-11-01

Full Text Available Rationale: Current first-line treatments for stress-related disorders such as Major Depressive Disorder (MDD act on monoaminergic systems and take weeks to achieve a therapeutic effect with poor response and low remission rates. Recent research has implicated the GABAergic system in the pathophysiology of depression, including deficits in interneurons targeting the dendritic compartment of cortical pyramidal cells. Objectives: The present study evaluates whether SH-053-2'F-R-CH3 (denoted α5-PAM, a positive allosteric modulator selective for α5-subunit containing GABAA receptors found predominantly on cortical pyramidal cell dendrites has anti-stress effects. Methods: Female and male C57BL6/J mice were exposed to unpredictable chronic mild stress (UCMS and treated with α5-PAM acutely (30 minutes prior to assessing behavior or chronically before being assessed behaviorally. Results: Acute and chronic α5-PAM treatments produce a pattern of decreased stress-induced behaviors (denoted as behavioral emotionality across various tests in female, but not in male mice. Behavioral Z-scores calculated across a panel of tests designed to best model the range and heterogeneity of human symptomatology confirmed that acute and chronic α5-PAM treatments consistently produce significant decreases in behavioral emotionality in several independent cohorts of females. The behavioral responses to α5-PAM could not be completely accounted for by differences in drug brain disposition between female and male mice. In mice exposed to UCMS, expression of the Gabra5 gene was increased in the frontal cortex after acute treatment and in hippocampus after chronic treatment with α5-PAM in females only, and these expression changes correlated with behavioral emotionality. Conclusions: We showed that acute and chronic positive modulation of α5 subunit-containing GABAA receptors elicit anti-stress effects in a sex-dependent manner, suggesting novel therapeutic modalities.

Synergistic Action of Presynaptic Muscarinic Acetylcholine Receptors and Adenosine Receptors in Developmental Axonal Competition at the Neuromuscular Junction.

Science.gov (United States)

Nadal, Laura; Garcia, Neus; Hurtado, Erica; Simó, Anna; Tomàs, Marta; Lanuza, Maria Angel; Cilleros, Victor; Tomàs, Josep Maria

2016-01-01

The development of the nervous system involves the initial overproduction of synapses, which promotes connectivity. Hebbian competition between axons with different activities leads to the loss of roughly half of the overproduced elements and this refines connectivity. We used quantitative immunohistochemistry to investigate, in the postnatal day 7 (P7) to P9 neuromuscular junctions, the involvement of muscarinic receptors (muscarinic acetylcholine autoreceptors and the M1, M2, and M4 subtypes) and adenosine receptors (A1 and A2A subtypes) in the control of axonal elimination after the mouse levator auris longus muscle had been exposed to selective antagonists in vivo. In a previous study we analyzed the role of each of the individual receptors. Here we investigate the additive or occlusive effects of their inhibitors and thus the existence of synergistic activity between the receptors. The main results show that the A2A, M1, M4, and A1 receptors (in this order of ability) delayed axonal elimination at P7. M4 produces some occlusion of the M1 pathway and some addition to the A1 pathway, which suggests that they cooperate. M2 receptors may modulate (by allowing a permissive action) the other receptors, mainly M4 and A1. The continued action of these receptors (now including M2 but not M4) finally promotes axonal loss at P9. All 4 receptors (M2, M1, A1, and A2A, in this order of ability) are necessary. The M4 receptor (which in itself does not affect axon loss) seems to modulate the other receptors. We found a synergistic action between the M1, A1, and A2A receptors, which show an additive effect, whereas the potent M2 effect is largely independent of the other receptors (though can be modulated by M4). At P9, there is a full mutual dependence between the A1 and A2A receptors in regulating axon loss. In summary, postnatal axonal elimination is a regulated multireceptor mechanism that involves the cooperation of several muscarinic and adenosine receptor subtypes. �

Human-derived gut microbiota modulates colonic secretion in mice by regulating 5-HT3 receptor expression via acetate production.

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Bhattarai, Yogesh; Schmidt, Bradley A; Linden, David R; Larson, Eric D; Grover, Madhusudan; Beyder, Arthur; Farrugia, Gianrico; Kashyap, Purna C

2017-07-01

Serotonin [5-hydroxytryptamine (5-HT)], an important neurotransmitter and a paracrine messenger in the gastrointestinal tract, regulates intestinal secretion by its action primarily on 5-HT 3 and 5-HT 4 receptors. Recent studies highlight the role of gut microbiota in 5-HT biosynthesis. In this study, we determine whether human-derived gut microbiota affects host secretory response to 5-HT and 5-HT receptor expression. We used proximal colonic mucosa-submucosa preparation from age-matched Swiss Webster germ-free (GF) and humanized (HM; ex-GF colonized with human gut microbiota) mice. 5-HT evoked a significantly greater increase in short-circuit current (Δ I sc ) in GF compared with HM mice. Additionally, 5-HT 3 receptor mRNA and protein expression was significantly higher in GF compared with HM mice. Ondansetron, a 5-HT 3 receptor antagonist, inhibited 5-HT-evoked Δ I sc in GF mice but not in HM mice. Furthermore, a 5-HT 3 receptor-selective agonist, 2-methyl-5-hydroxytryptamine hydrochloride, evoked a significantly higher Δ I sc in GF compared with HM mice. Immunohistochemistry in 5-HT 3A -green fluorescent protein mice localized 5-HT 3 receptor expression to enterochromaffin cells in addition to nerve fibers. The significant difference in 5-HT-evoked Δ I sc between GF and HM mice persisted in the presence of tetrodotoxin (TTX) but was lost after ondansetron application in the presence of TTX. Application of acetate (10 mM) significantly lowered 5-HT 3 receptor mRNA in GF mouse colonoids. We conclude that host secretory response to 5-HT may be modulated by gut microbiota regulation of 5-HT 3 receptor expression via acetate production. Epithelial 5-HT 3 receptor may function as a mediator of gut microbiota-driven change in intestinal secretion. NEW & NOTEWORTHY We found that gut microbiota alters serotonin (5-HT)-evoked intestinal secretion in a 5-HT 3 receptor-dependent mechanism and gut microbiota metabolite acetate alters 5-HT 3 receptor expression in

Highly selective and sensitive detection of neurotransmitters using receptor-modified single-walled carbon nanotube sensors

Science.gov (United States)

Kim, Byeongju; Song, Hyun Seok; Jin, Hye Jun; Park, Eun Jin; Lee, Sang Hun; Lee, Byung Yang; Park, Tai Hyun; Hong, Seunghun

2013-07-01

We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening.

Highly selective and sensitive detection of neurotransmitters using receptor-modified single-walled carbon nanotube sensors

International Nuclear Information System (INIS)

Kim, Byeongju; Jin, Hye Jun; Park, Eun Jin; Hong, Seunghun; Song, Hyun Seok; Lee, Sang Hun; Park, Tai Hyun; Lee, Byung Yang

2013-01-01

We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening. (paper)

Modulation of voltage-gated Ca2+ channels by G protein-coupled receptors in celiac-mesenteric ganglion neurons of septic rats.

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Mohamed Farrag

Full Text Available Septic shock, the most severe complication associated with sepsis, is manifested by tissue hypoperfusion due, in part, to cardiovascular and autonomic dysfunction. In many cases, the splanchnic circulation becomes vasoplegic. The celiac-superior mesenteric ganglion (CSMG sympathetic neurons provide the main autonomic input to these vessels. We used the cecal ligation puncture (CLP model, which closely mimics the hemodynamic and metabolic disturbances observed in septic patients, to examine the properties and modulation of Ca2+ channels by G protein-coupled receptors in acutely dissociated rat CSMG neurons. Voltage-clamp studies 48 hr post-sepsis revealed that the Ca2+ current density in CMSG neurons from septic rats was significantly lower than those isolated from sham control rats. This reduction coincided with a significant increase in membrane surface area and a negligible increase in Ca2+ current amplitude. Possible explanations for these findings include either cell swelling or neurite outgrowth enhancement of CSMG neurons from septic rats. Additionally, a significant rightward shift of the concentration-response relationship for the norepinephrine (NE-mediated Ca2+ current inhibition was observed in CSMG neurons from septic rats. Testing for the presence of opioid receptor subtypes in CSMG neurons, showed that mu opioid receptors were present in ~70% of CSMG, while NOP opioid receptors were found in all CSMG neurons tested. The pharmacological profile for both opioid receptor subtypes was not significantly affected by sepsis. Further, the Ca2+ current modulation by propionate, an agonist for the free fatty acid receptors GPR41 and GPR43, was not altered by sepsis. Overall, our findings suggest that CSMG function is affected by sepsis via changes in cell size and α2-adrenergic receptor-mediated Ca2+ channel modulation.

Development of a human vasopressin V1a-receptor antagonist from an evolutionary-related insect neuropeptide

Science.gov (United States)

di Giglio, Maria Giulia; Muttenthaler, Markus; Harpsøe, Kasper; Liutkeviciute, Zita; Keov, Peter; Eder, Thomas; Rattei, Thomas; Arrowsmith, Sarah; Wray, Susan; Marek, Ales; Elbert, Tomas; Alewood, Paul F.; Gloriam, David E.; Gruber, Christian W.

2017-02-01

Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary conservation of the 600-million-year-old oxytocin/vasopressin signalling system. We isolated the insect oxytocin/vasopressin orthologue inotocin from the black garden ant (Lasius niger), identified and cloned its cognate receptor and determined its pharmacological properties on the insect and human oxytocin/vasopressin receptors. Subsequently, we identified a functional dichotomy: inotocin activated the insect inotocin and the human vasopressin V1b receptors, but inhibited the human V1aR. Replacement of Arg8 of inotocin by D-Arg8 led to a potent, stable and competitive V1aR-antagonist ([D-Arg8]-inotocin) with a 3,000-fold binding selectivity for the human V1aR over the other three subtypes, OTR, V1bR and V2R. The Arg8/D-Arg8 ligand-pair was further investigated to gain novel insights into the oxytocin/vasopressin peptide-receptor interaction, which led to the identification of key residues of the receptors that are important for ligand functionality and selectivity. These observations could play an important role for development of oxytocin/vasopressin receptor modulators that would enable clear distinction of the physiological and pathological responses of the individual receptor subtypes.

Stress-induced changes of hippocampal NMDA receptors: modulation by duloxetine treatment.

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Francesca Calabrese

Full Text Available It is now well established that the glutamatergic system contributes to the pathophysiology of depression. Exposure to stress, a major precipitating factor for depression, enhances glutamate release that can contribute to structural abnormalities observed in the brain of depressed subjects. On the other hand, it has been demonstrated that NMDA antagonists, like ketamine, exert an antidepressant effect at preclinical and clinical levels. On these bases, the purpose of our study was to investigate whether chronic mild stress is associated with specific alterations of the NMDA receptor complex, in adult rats, and to establish whether concomitant antidepressant treatment could normalize such deficits. We found that chronic stress increases the expression of the obligatory GluN1 subunit, as well as of the accessory subunits GluN2A and GluN2B at transcriptional and translational levels, particularly in the ventral hippocampus. Concomitant treatment with the antidepressant duloxetine was able to normalize the increase of glutamatergic receptor subunit expression, and correct the changes in receptor phosphorylation produced by stress exposure. Our data suggest that prolonged stress, a condition that has etiologic relevance for depression, may enhance glutamate activity through post-synaptic mechanisms, by regulating NMDA receptors, and that antidepressants may in part normalize such changes. Our results provide support to the notion that antidepressants may exert their activity in the long-term also via modulation of the glutamatergic synapse.

alpha-Adrenoceptor and opioid receptor modulation of clonidine-induced antinociception.

Science.gov (United States)

Sierralta, F; Naquira, D; Pinardi, G; Miranda, H F

1996-10-01

1. The antinociceptive action of clonidine (Clon) and the interactions with alpha 1, alpha 2 adrenoceptor and opioid receptor antagonists was evaluated in mice by use of chemical algesiometric test (acetic acid writhing test). 2. Clon produced a dose-dependent antinociceptive action and the ED50 for intracerebroventricular (i.c.v.) was lower than for intraperitoneal (i.p.) administration (1 ng kg-1 vs 300 ng kg-1). The parallelism of the dose-response curves indicates activation of a common receptor subtype. 3. Systemic administration of prazosin and terazosin displayed antinociceptive activity. Pretreatment with prazosin produced a dual action: i.c.v. Clon effect did not change, and i.p. Clon effect was enhanced. Yohimbine i.c.v. or i.p. did not induce antinonciception, but antagonized Clon-induced activity. These results suggest that alpha 1- and alpha 2-adrenoceptors, either located at the pre- and/or post-synaptic level, are involved in the control of spinal antinociception. 4. Naloxone (NX) and naltrexone (NTX) induced antinociceptive effects at low doses (microgram kg-1 range) and a lower antinociceptive effect at higher doses (mg kg-1 range). Low doses of NX or NTX antagonized Clon antinociception, possibly in relation to a preferential mu opioid receptor antagonism. In contrast, high doses of NX or NTX increased the antinociceptive activity of Clon, which could be due to an enhanced inhibition of the release of substance P. 5. The results obtained in the present work suggest the involvement of alpha 1-, alpha 2-adrenoceptor and opioid receptors in the modulation of the antinociceptive activity of clonidine, which seems to be exerted either at spinal and/or supraspinal level.

Sexual behavior modulates contextual fear memory through dopamine D1/D5 receptors.

Science.gov (United States)

Bai, Hua-Yi; Cao, Jun; Liu, Na; Xu, Lin; Luo, Jian-Hong

2009-03-01

Traumatic events always lead to aversive emotional memory, i.e., fear memory. In contrast, positive events in daily life such as sex experiences seem to reduce aversive memory after aversive events. Thus, we hypothesized that post-traumatic pleasurable experiences, especially instinctive behaviors such as sex, might modulate traumatic memory through a memory competition mechanism. Here, we first report that male rats persistently expressed much lower fear responses when exposed to females, but not when exposed to males, for 24 h immediately after contextual fear conditioning. Remarkably, this effect of sexual behavior was blocked by either systemic or intrahippocampal injection of the dopamine D1/D5 receptor antagonist R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390) and was mimicked by systemic but not intrahippocampal injection of the D1/D5 receptor agonist R(+)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol hydrochloride (SKF39393). Furthermore, as a candidate mechanism underlying contextual fear memory, the impaired induction of hippocampal long-term potentiation (LTP) elicited by conditioned fear was rescued in male rats immediately exposed to female but not male rats for 24 h. Systemic injection of the dopamine D1/D5 receptor antagonist SCH23390 or agonist SKF38393 prevented or mimicked the effect of sexual behavior on the impaired induction of hippocampal LTP. Thus, our finding suggests that dopaminergic functions may, at least partially, govern competition between contextual fear and enjoyable memories through the modulation of hippocampal LTP.

Integrated regulation of AMPA glutamate receptor phosphorylation in the striatum by dopamine and acetylcholine.

Science.gov (United States)

Xue, Bing; Chen, Elton C; He, Nan; Jin, Dao-Zhong; Mao, Li-Min; Wang, John Q

2017-01-01

Dopamine (DA) and acetylcholine (ACh) signals converge onto protein kinase A (PKA) in medium spiny neurons of the striatum to control cellular and synaptic activities of these neurons, although underlying molecular mechanisms are less clear. Here we measured phosphorylation of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) at a PKA site (S845) as an indicator of AMPAR responses in adult rat brains in vivo to explore how DA and ACh interact to modulate AMPARs. We found that subtype-selective activation of DA D1 receptors (D1Rs), D2 receptors (D2Rs), or muscarinic M4 receptors (M4Rs) induced specific patterns of GluA1 S845 responses in the striatum. These defined patterns support a local multitransmitter interaction model in which D2Rs inhibited an intrinsic inhibitory element mediated by M4Rs to enhance the D1R efficacy in modulating AMPARs. Consistent with this, selective enhancement of M4R activity by a positive allosteric modulator resumed the cholinergic inhibition of D1Rs. In addition, D1R and D2R coactivation recruited GluA1 and PKA preferentially to extrasynaptic sites. In sum, our in vivo data support an existence of a dynamic DA-ACh balance in the striatum which actively modulates GluA1 AMPAR phosphorylation and trafficking. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'. Copyright © 2016 Elsevier Ltd. All rights reserved.

Endogenous opioid peptide-mediated neurotransmission in central and pericentral nuclei of the inferior colliculus recruits μ1-opioid receptor to modulate post-ictal antinociception.

Science.gov (United States)

Felippotti, Tatiana Tocchini; de Freitas, Renato Leonardo; Coimbra, Norberto Cysne

2012-02-01

The aim of the present work was to investigate the involvement of the μ1-endogenous opioid peptide receptor-mediated system in post-ictal antinociception. Antinociceptive responses were determined by the tail-flick test after pre-treatment with the selective μ1-opioid receptor antagonist naloxonazine, peripherally or centrally administered at different doses. Peripheral subchronic (24 h) pre-treatment with naloxonazine antagonised the antinociception elicited by tonic-clonic seizures. Acute (10 min) pre-treatment, however, did not have the same effect. In addition, microinjections of naloxonazine into the central, dorsal cortical and external cortical nuclei of the inferior colliculus antagonised tonic-clonic seizure-induced antinociception. Neither acute (10-min) peripheral pre-treatment with naloxonazine nor subchronic intramesencephalic blockade of μ1-opioid receptors resulted in consistent statistically significant differences in the severity of tonic-clonic seizures shown by Racine's index (1972), although the intracollicular specific antagonism of μ1-opioid receptor decreased the duration of seizures. μ1-Opioid receptors and the inferior colliculus have been implicated in several endogenous opioid peptide-mediated responses such as antinociception and convulsion. The present findings suggest the involvement of μ1-opiate receptors of central and pericentral nuclei of the inferior colliculus in the modulation of tonic-clonic seizures and in the organisation of post-ictal antinociception. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spatial Frequency Selectivity Is Impaired in Dopamine D2 Receptor Knockout Mice

Science.gov (United States)

Souza, Bruno Oliveira Ferreira; Abou Rjeili, Mira; Quintana, Clémentine; Beaulieu, Jean M.; Casanova, Christian

2018-01-01

Dopamine is a neurotransmitter implicated in several brain functions, including vision. In the present study, we investigated the impacts of the lack of D2 dopamine receptors on the structure and function of the primary visual cortex (V1) of D2-KO mice using optical imaging of intrinsic signals. Retinotopic maps were generated in order to measure anatomo-functional parameters such as V1 shape, cortical magnification factor, scatter, and ocular dominance. Contrast sensitivity and spatial frequency selectivity (SF) functions were computed from responses to drifting gratings. When compared to control mice, none of the parameters of the retinotopic maps were affected by D2 receptor loss of function. While the contrast sensitivity function of D2-KO mice did not differ from their wild-type counterparts, SF selectivity function was significantly affected as the optimal SF and the high cut-off frequency (p D2-KO than in WT mice. These findings show that the lack of function of D2 dopamine receptors had no influence on cortical structure whereas it had a significant impact on the spatial frequency selectivity and high cut-off. Taken together, our results suggest that D2 receptors play a specific role on the processing of spatial features in early visual cortex while they do not seem to participate in its development. PMID:29379422

Selective attention to emotional cues and emotion recognition in healthy subjects: the role of mineralocorticoid receptor stimulation.

Science.gov (United States)

Schultebraucks, Katharina; Deuter, Christian E; Duesenberg, Moritz; Schulze, Lars; Hellmann-Regen, Julian; Domke, Antonia; Lockenvitz, Lisa; Kuehl, Linn K; Otte, Christian; Wingenfeld, Katja

2016-09-01

Selective attention toward emotional cues and emotion recognition of facial expressions are important aspects of social cognition. Stress modulates social cognition through cortisol, which acts on glucocorticoid (GR) and mineralocorticoid receptors (MR) in the brain. We examined the role of MR activation on attentional bias toward emotional cues and on emotion recognition. We included 40 healthy young women and 40 healthy young men (mean age 23.9 ± 3.3), who either received 0.4 mg of the MR agonist fludrocortisone or placebo. A dot-probe paradigm was used to test for attentional biases toward emotional cues (happy and sad faces). Moreover, we used a facial emotion recognition task to investigate the ability to recognize emotional valence (anger and sadness) from facial expression in four graded categories of emotional intensity (20, 30, 40, and 80 %). In the emotional dot-probe task, we found a main effect of treatment and a treatment × valence interaction. Post hoc analyses revealed an attentional bias away from sad faces after placebo intake and a shift in selective attention toward sad faces compared to placebo. We found no attentional bias toward happy faces after fludrocortisone or placebo intake. In the facial emotion recognition task, there was no main effect of treatment. MR stimulation seems to be important in modulating quick, automatic emotional processing, i.e., a shift in selective attention toward negative emotional cues. Our results confirm and extend previous findings of MR function. However, we did not find an effect of MR stimulation on emotion recognition.

Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation

DEFF Research Database (Denmark)

Milanos, Sinem; Kuenzel, Katharina; Gilbert, Daniel F

2017-01-01

monoterpenes, e.g. myrtenol as positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in loss of modulatory activity. Two independent approaches, fluorescence-based compound analysis...

Orphan nuclear receptor TLX regulates astrogenesis by modulating BMP signaling

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Song eQin

2014-04-01

Full Text Available Neural stem cells (NSCs are self-renewing multipotent progenitors that generate both neurons and glia. The precise control of NSC behavior is fundamental to the architecture and function of the central nervous system. We previously demonstrated that the orphan nuclear receptor TLX is required for postnatal NSC activation and neurogenesis in the neurogenic niche. Here, we show that TLX modulates BMP-SMAD signaling to control the timing of postnatal astrogenesis. Genes involved in the BMP signaling pathway, such as Bmp4, Hes1, and Id3, are upregulated in postnatal brains lacking Tlx. Chromatin immunoprecipitation and electrophoretic mobility shift assays reveal that TLX can directly bind the enhancer region of Bmp4. In accordance with elevated BMP signaling, the downstream effectors SMAD1/5/8 are activated by phosphorylation in Tlx mutant mice. Consequently, Tlx mutant brains exhibit an early appearance and increased number of astrocytes with marker expression of glial fibrillary acidic protein (GFAP and S100B. Taken together, these results suggest that TLX tightly controls postnatal astrogenesis through the modulation of BMP-SMAD signaling pathway activity.

Orphan nuclear receptor TLX regulates astrogenesis by modulating BMP signaling.

Science.gov (United States)

Qin, Song; Niu, Wenze; Iqbal, Nida; Smith, Derek K; Zhang, Chun-Li

2014-01-01

Neural stem cells (NSCs) are self-renewing multipotent progenitors that generate both neurons and glia. The precise control of NSC behavior is fundamental to the architecture and function of the central nervous system. We previously demonstrated that the orphan nuclear receptor TLX is required for postnatal NSC activation and neurogenesis in the neurogenic niche. Here, we show that TLX modulates bone morphogenetic protein (BMP)-SMAD signaling to control the timing of postnatal astrogenesis. Genes involved in the BMP signaling pathway, such as Bmp4, Hes1, and Id3, are upregulated in postnatal brains lacking Tlx. Chromatin immunoprecipitation and electrophoretic mobility shift assays reveal that TLX can directly bind the enhancer region of Bmp4. In accordance with elevated BMP signaling, the downstream effectors SMAD1/5/8 are activated by phosphorylation in Tlx mutant mice. Consequently, Tlx mutant brains exhibit an early appearance and increased number of astrocytes with marker expression of glial fibrillary acidic protein (GFAP) and S100B. Taken together, these results suggest that TLX tightly controls postnatal astrogenesis through the modulation of BMP-SMAD signaling pathway activity.

Prolonging survival of corneal transplantation by selective sphingosine-1-phosphate receptor 1 agonist.

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Min Gao

Full Text Available Corneal transplantation is the most used therapy for eye disorders. Although the cornea is somewhat an immune privileged organ, immune rejection is still the major problem that reduces the success rate. Therefore, effective chemical drugs that regulate immunoreactions are needed to improve the outcome of corneal transplantations. Here, a sphingosine-1-phosphate receptor 1 (S1P1 selective agonist was systematically evaluated in mouse allogeneic corneal transplantation and compared with the commonly used immunosuppressive agents. Compared with CsA and the non-selective sphingosine 1-phosphate (S1P receptor agonist FTY720, the S1P1 selective agonist can prolong the survival corneal transplantation for more than 30 days with a low immune response. More importantly, the optimal dose of the S1P1 selective agonist was much less than non-selective S1P receptor agonist FTY720, which would reduce the dose-dependent toxicity in drug application. Then we analyzed the mechanisms of the selected S1P1 selective agonist on the immunosuppression. The results shown that the S1P1 selective agonist could regulate the distribution of the immune cells with less CD4+ T cells and enhanced Treg cells in the allograft, moreover the expression of anti-inflammatory cytokines TGF-β1 and IL-10 unregulated which can reduce the immunoreactions. These findings suggest that S1P1 selective agonist may be a more appropriate immunosuppressive compound to effectively prolong mouse allogeneic corneal grafts survival.

Hispolon inhibits the growth of estrogen receptor positive human breast cancer cells through modulation of estrogen receptor alpha

International Nuclear Information System (INIS)

Jang, Eun Hyang; Jang, Soon Young; Cho, In-Hye; Hong, Darong; Jung, Bom; Park, Min-Ju; Kim, Jong-Ho

2015-01-01

Human estrogen receptor α (ERα) is a nuclear transcription factor that is a major therapeutic target in breast cancer. The transcriptional activity of ERα is regulated by certain estrogen-receptor modulators. Hispolon, isolated from Phellinus linteus, a traditional medicinal mushroom called Sanghwang in Korea, has been used to treat various pathologies, such as inflammation, gastroenteric disorders, lymphatic diseases, and cancers. In this latter context, Hispolon has been reported to exhibit therapeutic efficacy against various cancer cells, including melanoma, leukemia, hepatocarcinoma, bladder cancer, and gastric cancer cells. However, ERα regulation by Hispolon has not been reported. In this study, we investigated the effects of Hispolon on the growth of breast cancer cells. We found that Hispolon decreased expression of ERα at both mRNA and the protein levels in MCF7 and T47D human breast cancer cells. Luciferase reporter assays showed that Hispolon decreased the transcriptional activity of ERα. Hispolon treatment also inhibited expression of the ERα target gene pS2. We propose that Hispolon, an anticancer drug extracted from natural sources, inhibits cell growth through modulation of ERα in estrogen-positive breast cancer cells and is a candidate for use in human breast cancer chemotherapy. - Highlights: • Hispolon decreased ERα expression at both mRNA and protein levels. • Hispolon decreased ERα transcriptional activity. • Hispolon treatment inhibited expression of ERα target gene pS2. • Shikonin is a candidate chemotherapeutic target in the treatment of human breast cancer

Hispolon inhibits the growth of estrogen receptor positive human breast cancer cells through modulation of estrogen receptor alpha

Energy Technology Data Exchange (ETDEWEB)

Jang, Eun Hyang; Jang, Soon Young; Cho, In-Hye [Department of Pharmacy, Graduate School, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Hong, Darong [Department of Life and Nanopharmaceutical Science, Graduate School, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Jung, Bom; Park, Min-Ju [Department of Pharmacy, Graduate School, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Kim, Jong-Ho, E-mail: jonghokim@khu.ac.kr [Department of Pharmacy, Graduate School, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of)

2015-08-07

Human estrogen receptor α (ERα) is a nuclear transcription factor that is a major therapeutic target in breast cancer. The transcriptional activity of ERα is regulated by certain estrogen-receptor modulators. Hispolon, isolated from Phellinus linteus, a traditional medicinal mushroom called Sanghwang in Korea, has been used to treat various pathologies, such as inflammation, gastroenteric disorders, lymphatic diseases, and cancers. In this latter context, Hispolon has been reported to exhibit therapeutic efficacy against various cancer cells, including melanoma, leukemia, hepatocarcinoma, bladder cancer, and gastric cancer cells. However, ERα regulation by Hispolon has not been reported. In this study, we investigated the effects of Hispolon on the growth of breast cancer cells. We found that Hispolon decreased expression of ERα at both mRNA and the protein levels in MCF7 and T47D human breast cancer cells. Luciferase reporter assays showed that Hispolon decreased the transcriptional activity of ERα. Hispolon treatment also inhibited expression of the ERα target gene pS2. We propose that Hispolon, an anticancer drug extracted from natural sources, inhibits cell growth through modulation of ERα in estrogen-positive breast cancer cells and is a candidate for use in human breast cancer chemotherapy. - Highlights: • Hispolon decreased ERα expression at both mRNA and protein levels. • Hispolon decreased ERα transcriptional activity. • Hispolon treatment inhibited expression of ERα target gene pS2. • Shikonin is a candidate chemotherapeutic target in the treatment of human breast cancer.

Optimizing Energy and Modulation Selection in Multi-Resolution Modulation For Wireless Video Broadcast/Multicast

KAUST Repository

She, James

2009-11-01

Emerging technologies in Broadband Wireless Access (BWA) networks and video coding have enabled high-quality wireless video broadcast/multicast services in metropolitan areas. Joint source-channel coded wireless transmission, especially using hierarchical/superposition coded modulation at the channel, is recognized as an effective and scalable approach to increase the system scalability while tackling the multi-user channel diversity problem. The power allocation and modulation selection problem, however, is subject to a high computational complexity due to the nonlinear formulation and huge solution space. This paper introduces a dynamic programming framework with conditioned parsing, which significantly reduces the search space. The optimized result is further verified with experiments using real video content. The proposed approach effectively serves as a generalized and practical optimization framework that can gauge and optimize a scalable wireless video broadcast/multicast based on multi-resolution modulation in any BWA network.

Optimizing Energy and Modulation Selection in Multi-Resolution Modulation For Wireless Video Broadcast/Multicast

KAUST Repository

She, James; Ho, Pin-Han; Shihada, Basem

2009-01-01

Emerging technologies in Broadband Wireless Access (BWA) networks and video coding have enabled high-quality wireless video broadcast/multicast services in metropolitan areas. Joint source-channel coded wireless transmission, especially using hierarchical/superposition coded modulation at the channel, is recognized as an effective and scalable approach to increase the system scalability while tackling the multi-user channel diversity problem. The power allocation and modulation selection problem, however, is subject to a high computational complexity due to the nonlinear formulation and huge solution space. This paper introduces a dynamic programming framework with conditioned parsing, which significantly reduces the search space. The optimized result is further verified with experiments using real video content. The proposed approach effectively serves as a generalized and practical optimization framework that can gauge and optimize a scalable wireless video broadcast/multicast based on multi-resolution modulation in any BWA network.

Functional Selectivity of Allosteric Interactions within G Protein–Coupled Receptor Oligomers: The Dopamine D1-D3 Receptor Heterotetramer

Science.gov (United States)

Guitart, Xavier; Navarro, Gemma; Moreno, Estefania; Yano, Hideaki; Cai, Ning-Sheng; Sánchez-Soto, Marta; Kumar-Barodia, Sandeep; Naidu, Yamini T.; Mallol, Josefa; Cortés, Antoni; Lluís, Carme; Canela, Enric I.; Casadó, Vicent; McCormick, Peter J.

2014-01-01

The dopamine D1 receptor–D3 receptor (D1R-D3R) heteromer is being considered as a potential therapeutic target for neuropsychiatric disorders. Previous studies suggested that this heteromer could be involved in the ability of D3R agonists to potentiate locomotor activation induced by D1R agonists. It has also been postulated that its overexpression plays a role in L-dopa–induced dyskinesia and in drug addiction. However, little is known about its biochemical properties. By combining bioluminescence resonance energy transfer, bimolecular complementation techniques, and cell-signaling experiments in transfected cells, evidence was obtained for a tetrameric stoichiometry of the D1R–D3R heteromer, constituted by two interacting D1R and D3R homodimers coupled to Gs and Gi proteins, respectively. Coactivation of both receptors led to the canonical negative interaction at the level of adenylyl cyclase signaling, to a strong recruitment of β-arrestin-1, and to a positive cross talk of D1R and D3R agonists at the level of mitogen-activated protein kinase (MAPK) signaling. Furthermore, D1R or D3R antagonists counteracted β-arrestin-1 recruitment and MAPK activation induced by D3R and D1R agonists, respectively (cross-antagonism). Positive cross talk and cross-antagonism at the MAPK level were counteracted by specific synthetic peptides with amino acid sequences corresponding to D1R transmembrane (TM) domains TM5 and TM6, which also selectively modified the quaternary structure of the D1R-D3R heteromer, as demonstrated by complementation of hemiproteins of yellow fluorescence protein fused to D1R and D3R. These results demonstrate functional selectivity of allosteric modulations within the D1R-D3R heteromer, which can be involved with the reported behavioral synergism of D1R and D3R agonists. PMID:25097189

Differential modulation of expression of nuclear receptor mediated genes by tris(2-butoxyethyl) phosphate (TBOEP) on early life stages of zebrafish (Danio rerio)

Energy Technology Data Exchange (ETDEWEB)

Ma, Zhiyuan, E-mail: zhiyuan_nju@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Yu, Yijun, E-mail: yjun.yu@gmail.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Tang, Song [School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Liu, Hongling, E-mail: hlliu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Su, Guanyong; Xie, Yuwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Giesy, John P. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Hecker, Markus [School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Yu, Hongxia [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China)

2015-12-15

Highlights: • Effects of TBOEP on expression of genes of several nuclear hormone receptors and their relationship with adverse effect pathways in zebrafish. • TBOEP was neither an agonist nor antagonist of AR or AhR as determined by use of in vitro mammalian cell-based receptor transactivation assays. • Modulation of ER- and MR-dependent pathways allowed for development of feasible receptor-mediated, critical mechanisms of toxic action. - Abstract: As one substitute for phased-out brominated flame retardants (BFRs), tris(2-butoxyethyl) phosphate (TBOEP) is frequently detected in aquatic organisms. However, knowledge about endocrine disrupting mechanisms associated with nuclear receptors caused by TBOEP remained restricted to results from in vitro studies with mammalian cells. In the study, results of which are presented here, embryos/larvae of zebrafish (Danio rerio) were exposed to 0.02, 0.1 or 0.5 μM TBOEP to investigate expression of genes under control of several nuclear hormone receptors (estrogen receptors (ERs), androgen receptor (AR), thyroid hormone receptor alpha (TRα), mineralocorticoid receptor (MR), glucocorticoid receptor (GR), aryl hydrocarbon (AhR), peroxisome proliferator-activated receptor alpha (PPARα), and pregnane × receptor (P × R)) pathways at 120 hpf. Exposure to 0.5 μM TBOEP significantly (p < 0.05, one-way analysis of variance) up-regulated expression of estrogen receptors (ERs, er1, er2a, and er2b) genes and ER-associated genes (vtg4, vtg5, pgr, ncor, and ncoa3), indicating TBOEP modulates the ER pathway. In contrast, expression of most genes (mr, 11βhsd, ube2i,and adrb2b) associated with the mineralocorticoid receptor (MR) pathway were significantly down-regulated. Furthermore, in vitro mammalian cell-based (MDA-kb2 and H4IIE-luc) receptor transactivation assays, were also conducted to investigate possible agonistic or antagonistic effects on AR- and AhR-mediated pathways. In mammalian cells, none of these pathways were

Receptor Oligomerization as a Process Modulating Cellular Semiotics

DEFF Research Database (Denmark)

Giorgi, Franco; Bruni, Luis Emilio; Maggio, Roberto

2010-01-01

be another level of quality control that may help maintaining GPCRs rather stable throughout evolution. We propose here receptor oligomerization to be a basic molecular mechanism controlling GPCRs redundancy in many different cell types, and the plasma membrane as the first hierarchical cell structure...... at which selective categorical sensing may occur. Categorical sensing can be seen as the cellular capacity for identifying and ordering complex patterns of mixed signals out of a contextual matrix, i.e., the recognition of meaningful patterns out of ubiquitous signals. In this context, redundancy...

Spatial learning in the 5-HT1B receptor knockout mouse: selective facilitation/impairment depending on the cognitive demand.

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Buhot, Marie-Christine; Wolff, Mathieu; Benhassine, Narimane; Costet, Pierre; Hen, René; Segu, Louis

2003-01-01

Age-related memory decline is associated with a combined dysfunction of the cholinergic and serotonergic systems in the hippocampus and frontal cortex, in particular. The 5-HT1B receptor occupies strategic cellular and subcellular locations in these structures, where it plays a role in the modulation of ACh release. In an attempt to characterize the contribution of this receptor to memory functions, 5-HT1B receptor knockout (KO) mice were submitted to various behavioral paradigms carried out in the same experimental context (water maze), which were aimed at exposing mice to various levels of memory demand. 5-HT1BKO mice exhibited a facilitation in the acquisition of a hippocampal-dependent spatial reference memory task in the Morris water maze. This facilitation was selective of task difficulty, showing thus that the genetic inactivation of the 5-HT1B receptor is associated with facilitation when the complexity of the task is increased, and reveals a protective effect on age-related hippocampal-dependent memory decline. Young-adult and aged KO and wild-type (WT) mice were equally able to learn a delayed spatial matching-to-sample working memory task in a radial-arm water maze with short (0 or 5 min) delays. However, 5-HT1BKO mice, only, exhibited a selective memory impairment at intermediate and long (15, 30, and 60 min) delays. Treatment by scopolamine induced the same pattern of performance in wild type as did the mutation for short (5 min, no impairment) and long (60 min, impairment) delays. Taken together, these studies revealed a beneficial effect of the mutation on the acquisition of a spatial reference memory task, but a deleterious effect on a working memory task for long delays. This 5-HT1BKO mouse story highlights the problem of the potential existence of "global memory enhancers."

Positive selection within the Schizophrenia-associated GABA(A receptor beta(2 gene.

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Wing-Sze Lo

Full Text Available The gamma-aminobutyric acid type-A (GABA(A receptor plays a major role in inhibitory neurotransmissions. Intronic SNPs and haplotypes in GABRB2, the gene for GABA(A receptor beta(2 subunit, are associated with schizophrenia and correlated with the expression of two alternatively spliced beta(2 isoforms. In the present study, using chimpanzee as an ancestral reference, high frequencies were observed for the derived (D alleles of the four SNPs rs6556547, rs187269, rs1816071 and rs1816072 in GABRB2, suggesting the occurrence of positive selection for these derived alleles. Coalescence-based simulation showed that the population frequency spectra and the frequencies of H56, the haplotype having all four D alleles, significantly deviated from neutral-evolution expectation in various demographic models. Haplotypes containing the derived allele of rs1816072 displayed significantly less diversity compared to haplotypes containing its ancestral allele, further supporting positive selection. The variations in DD-genotype frequencies in five human populations provided a snapshot of the evolutionary history, which suggested that the positive selections of the D alleles are recent and likely ongoing. The divergence between the DD-genotype profiles of schizophrenic and control samples pointed to the schizophrenia-relevance of positive selections, with the schizophrenic samples showing weakened selections compared to the controls. These DD-genotypes were previously found to increase the expression of beta(2, especially its long isoform. Electrophysiological analysis showed that this long beta(2 isoform favored by the positive selections is more sensitive than the short isoform to the inhibition of GABA(A receptor function by energy depletion. These findings represent the first demonstration of positive selection in a schizophrenia-associated gene.

Object width modulates object-based attentional selection.

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Nah, Joseph C; Neppi-Modona, Marco; Strother, Lars; Behrmann, Marlene; Shomstein, Sarah

2018-04-24

Visual input typically includes a myriad of objects, some of which are selected for further processing. While these objects vary in shape and size, most evidence supporting object-based guidance of attention is drawn from paradigms employing two identical objects. Importantly, object size is a readily perceived stimulus dimension, and whether it modulates the distribution of attention remains an open question. Across four experiments, the size of the objects in the display was manipulated in a modified version of the two-rectangle paradigm. In Experiment 1, two identical parallel rectangles of two sizes (thin or thick) were presented. Experiments 2-4 employed identical trapezoids (each having a thin and thick end), inverted in orientation. In the experiments, one end of an object was cued and participants performed either a T/L discrimination or a simple target-detection task. Combined results show that, in addition to the standard object-based attentional advantage, there was a further attentional benefit for processing information contained in the thick versus thin end of objects. Additionally, eye-tracking measures demonstrated increased saccade precision towards thick object ends, suggesting that Fitts's Law may play a role in object-based attentional shifts. Taken together, these results suggest that object-based attentional selection is modulated by object width.

Opposite modulation of brain stimulation reward by NMDA and AMPA receptors in the ventral tegmental area.

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Ducrot, Charles; Fortier, Emmanuel; Bouchard, Claude; Rompré, Pierre-Paul

2013-01-01

Previous studies have shown that blockade of ventral tegmental area (VTA) glutamate N-Methyl-D-Aspartate (NMDA) receptors induces reward, stimulates forward locomotion and enhances brain stimulation reward. Glutamate induces two types of excitatory response on VTA neurons, a fast and short lasting depolarization mediated by α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors and a longer lasting depolarization mediated by NMDA receptors. A role for the two glutamate receptors in modulation of VTA neuronal activity is evidenced by the functional change in AMPA and NMDA synaptic responses that result from repeated exposure to reward. Since both receptors contribute to the action of glutamate on VTA neuronal activity, we studied the effects of VTA AMPA and NMDA receptor blockade on reward induced by electrical brain stimulation. Experiments were performed on rats trained to self-administer electrical pulses in the medial posterior mesencephalon. Reward thresholds were measured with the curve-shift paradigm before and for 2 h after bilateral VTA microinjections of the AMPA antagonist, NBQX (2,3,-Dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(f)quinoxaline-7-sulfonamide, 0, 80, and 800 pmol/0.5 μl/side) and of a single dose (0.825 nmol/0.5 μl/side) of the NMDA antagonist, PPPA (2R,4S)-4-(3-Phosphonopropyl)-2-piperidinecarboxylic acid). NBQX produced a dose-dependent increase in reward threshold with no significant change in maximum rate of responding. Whereas PPPA injected at the same VTA sites produced a significant time dependent decrease in reward threshold and increase in maximum rate of responding. We found a negative correlation between the magnitude of the attenuation effect of NBQX and the enhancement effect of PPPA; moreover, NBQX and PPPA were most effective when injected, respectively, into the anterior and posterior VTA. These results suggest that glutamate acts on different receptor sub-types, most likely located on different VTA neurons, to

Opposite modulation of brain stimulation reward by NMDA and AMPA receptors in the ventral tegmental area.

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Charles eDucrot

2013-10-01

Full Text Available Previous studies have shown that blockade of ventral midbrain (VM glutamate N-Methyl-D-Aspartate (NMDA receptors induces reward, stimulates forward locomotion and enhances brain stimulation reward. Glutamate induces two types of excitatory response on VM neurons, a fast and short lasting depolarisation mediated by a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA receptors and a longer lasting depolarization mediated by NMDA receptors. A role for the two glutamate receptors in modulation of VM neuronal activity is evidenced by the functional change in AMPA and NMDA synaptic responses that result from repeated exposure to reward. Since both receptors contribute to the action of glutamate on VM neuronal activity, we studied the effects of VM AMPA and NMDA receptor blockade on reward induced by electrical brain stimulation. Experiments were performed on rats trained to self-administer electrical pulses in the medial posterior mesencephalon. Reward thresholds were measured with the curve-shift paradigm before and for two hours after bilateral VM microinjections of the AMPA antagonist, NBQX (2,3,-Dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(fquinoxaline-7-sulfonamide, 0, 80, and 800 pmol/0.5ul/side and of a single dose (0.825 nmol/0.5ul/side of the NMDA antagonist, PPPA (2R,4S-4-(3-Phosphonopropyl-2-piperidinecarboxylic acid. NBQX produced a dose-dependent increase in reward threshold with no significant change in maximum rate of responding. Whereas PPPA injected at the same VM sites produced a significant time dependent decrease in reward threshold and increase in maximum rate of responding. We found a negative correlation between the magnitude of the attenuation effect of NBQX and the enhancement effect of PPPA; moreover, NBQX and PPPA were most effective when injected respectively into the anterior and posterior VM. These results suggest that glutamate acts on different receptor sub-types, most likely located on different VM neurons, to modulate

Ligand-selective activation of heterologously-expressed mammalian olfactory receptor.

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Ukhanov, K; Bobkov, Y; Corey, E A; Ache, B W

2014-10-01

Mammalian olfactory receptors (ORs) appear to have the capacity to couple to multiple G protein-coupled signaling pathways in a ligand-dependent selective manner. To better understand the mechanisms and molecular range of such ligand selectivity, we expressed the mouse eugenol OR (mOR-EG) in HEK293T cells together with Gα15 to monitor activation of the phospholipase-C (PLC) signaling pathway and/or Gαolf to monitor activation of the adenylate cyclase (AC) signaling pathway, resulting in intracellular Ca(2+) release and/or Ca(2+) influx through a cyclic nucleotide-gated channel, respectively. PLC-dependent responses differed dynamically from AC-dependent responses, allowing them to be distinguished when Gα15 and Gαolf were co-expressed. The dynamic difference in readout was independent of the receptor, the heterologous expression system, and the ligand concentration. Of 17 reported mOR-EG ligands tested, including eugenol, its analogs, and structurally dissimilar compounds (mousse cristal, nootkatone, orivone), some equally activated both signaling pathways, some differentially activated both signaling pathways, and some had no noticeable effect even at 1-5mM. Our findings argue that mOR-EG, when heterologously expressed, can couple to two different signaling pathways in a ligand selective manner. The challenge now is to determine the potential of mOR-EG, and perhaps other ORs, to activate multiple signaling pathways in a ligand selective manner in native ORNs. Copyright © 2014 Elsevier Ltd. All rights reserved.

In-house validation of a liquid chromatography-tandem mass spectrometry method for the determination of selective androgen receptor modulators (SARMS) in bovine urine.

Science.gov (United States)

Schmidt, Kathrin S; Mankertz, Joachim

2018-06-01

A sensitive and robust LC-MS/MS method allowing the rapid screening and confirmation of selective androgen receptor modulators in bovine urine was developed and successfully validated according to Commission Decision 2002/657/EC, chapter 3.1.3 'alternative validation', by applying a matrix-comprehensive in-house validation concept. The confirmation of the analytes in the validation samples was achieved both on the basis of the MRM ion ratios as laid down in Commission Decision 2002/657/EC and by comparison of their enhanced product ion (EPI) spectra with a reference mass spectral library by making use of the QTRAP technology. Here, in addition to the MRM survey scan, EPI spectra were generated in a data-dependent way according to an information-dependent acquisition criterion. Moreover, stability studies of the analytes in solution and in matrix according to an isochronous approach proved the stability of the analytes in solution and in matrix for at least the duration of the validation study. To identify factors that have a significant influence on the test method in routine analysis, a factorial effect analysis was performed. To this end, factors considered to be relevant for the method in routine analysis (e.g. operator, storage duration of the extracts before measurement, different cartridge lots and different hydrolysis conditions) were systematically varied on two levels. The examination of the extent to which these factors influence the measurement results of the individual analytes showed that none of the validation factors exerts a significant influence on the measurement results.

LiCABEDS II. Modeling of ligand selectivity for G-protein-coupled cannabinoid receptors.

Science.gov (United States)

Ma, Chao; Wang, Lirong; Yang, Peng; Myint, Kyaw Z; Xie, Xiang-Qun

2013-01-28

The cannabinoid receptor subtype 2 (CB2) is a promising therapeutic target for blood cancer, pain relief, osteoporosis, and immune system disease. The recent withdrawal of Rimonabant, which targets another closely related cannabinoid receptor (CB1), accentuates the importance of selectivity for the development of CB2 ligands in order to minimize their effects on the CB1 receptor. In our previous study, LiCABEDS (Ligand Classifier of Adaptively Boosting Ensemble Decision Stumps) was reported as a generic ligand classification algorithm for the prediction of categorical molecular properties. Here, we report extension of the application of LiCABEDS to the modeling of cannabinoid ligand selectivity with molecular fingerprints as descriptors. The performance of LiCABEDS was systematically compared with another popular classification algorithm, support vector machine (SVM), according to prediction precision and recall rate. In addition, the examination of LiCABEDS models revealed the difference in structure diversity of CB1 and CB2 selective ligands. The structure determination from data mining could be useful for the design of novel cannabinoid lead compounds. More importantly, the potential of LiCABEDS was demonstrated through successful identification of newly synthesized CB2 selective compounds.

Three-Step Test System for the Identification of Novel GABAA Receptor Modulating Food Plants.

Science.gov (United States)

Sahin, Sümeyye; Eulenburg, Volker; Kreis, Wolfgang; Villmann, Carmen; Pischetsrieder, Monika

2016-12-01

Potentiation of γ-amino butyric acid (GABA)-induced GABA A receptor (GABA A R) activation is a common pathway to achieve sedative, sleep-enhancing, anxiolytic, and antidepressant effects. Presently, a three-component test system was established for the identification of novel GABA A R modulating food plants. In the first step, potentiation of GABA-induced response of the GABA A R was analysed by two-electrode voltage clamp (TEVC) for activity on human α1β2-GABA A R expressed in Xenopus laevis oocytes. Positively tested food plants were then subjected to quantification of GABA content by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) to exclude test foods, which evoke a TEVC-response by endogenous GABA. In the third step, specificity of GABA A -modulating activity was assessed by TEVC analysis of Xenopus laevis oocytes expressing the homologous glycine receptor (GlyR). The three-component test was then applied to screen 10 aqueous extracts of food plants for their GABA A R activity. Thus, hop cones (Humulus lupulus) and Sideritis sipylea were identified as the most potent specific GABA A R modulators eliciting significant potentiation of the current by 182 ± 27 and 172 ± 19 %, respectively, at the lowest concentration of 0.5 μg/mL. The extracts can now be further evaluated by in vivo studies and by structural evaluation of the active components.

Negative allosteric modulation of the mGlu7 receptor reduces visceral hypersensitivity in a stress-sensitive rat strain

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Rachel D. Moloney

2015-01-01

Full Text Available Glutamate, the main excitatory neurotransmitter in the central nervous system, exerts its effect through ionotropic and metabotropic receptors. Of these, group III mGlu receptors (mGlu 4, 6, 7, 8 are among the least studied due to a lack of pharmacological tools. mGlu7 receptors, the most highly conserved isoform, are abundantly distributed in the brain, especially in regions, such as the amygdala, known to be crucial for the emotional processing of painful stimuli. Visceral hypersensitivity is a poorly understood phenomenon manifesting as an increased sensitivity to visceral stimuli. Glutamate has long been associated with somatic pain processing leading us to postulate that crossover may exist between these two modalities. Moreover, stress has been shown to exacerbate visceral pain. ADX71743 is a novel, centrally penetrant, negative allosteric modulator of mGlu7 receptors. Thus, we used this tool to explore the possible involvement of this receptor in the mediation of visceral pain in a stress-sensitive model of visceral hypersensitivity, namely the Wistar Kyoto (WKY rat. ADX71743 reduced visceral hypersensitivity in the WKY rat as exhibited by increased visceral sensitivity threshold with concomitant reductions in total number of pain behaviours. Moreover, AD71743 increased total distance and distance travelled in the inner zone of the open field. These findings show, for what is to our knowledge, the first time, that mGlu7 receptor signalling plays a role in visceral pain processing. Thus, negative modulation of the mGlu7 receptor may be a plausible target for the amelioration of stress-induced visceral pain where there is a large unmet medical need.

MS-377, a selective sigma receptor ligand, indirectly blocks the action of PCP in the N-methyl-D-aspartate receptor ion-channel complex in primary cultured rat neuronal cells.

Science.gov (United States)

Karasawa, Jun-ichi; Yamamoto, Hideko; Yamamoto, Toshifumi; Sagi, Naoki; Horikomi, Kazutoshi; Sora, Ichiro

2002-02-22

MS-377 ((R)-(+)-1-(4-chlorophenyl)-3-[4-(2-methoxyethyl)piperazin-1-yl]methyl-2-pyrrolidinone L-tartrate) is a antipsychotic agent that binds to sigma-1 receptor. MS-377 showed anti-dopaminergic and anti-serotonergic activities and antagonistic action against phencyclidine (PCP)-induced behaviors in an animal model. These anti-psychotic activities of MS-377 are attributable to association with sigma-1 receptor. However, the mechanism by which the sigma-1 receptor ligands exact those numerous effects remains to be elucidated. In the present study, we evaluated the effect of MS-377 on N-methyl-D-aspartate (NMDA) receptor ion-channel complex in primary cultured rat neuronal cells. First, we examined the effect of MS-377 on NMDA-induced Ca2+ influx with fura-2/ AM loaded cells. MS-377 showed no effects on the basal Ca2+ concentration and NMDA-induced Ca2+ influx by itself PCP and SKF-10047 reduced the NMDA-induced increase in intracellular Ca2+ concentration. Pre-incubation of 1 microM MS-377 was found to significantly block the reduction by PCP or SKF-10047 of the NMDA-induced Ca2+ influx. Second, the effect of MS-377 on [3H]MK-801 intact cell binding was examined. PCP, haloperidol and (+)-pentazocine inhibited [3H]MK-801 binding, although MS-377 showed no effect by itself Pre-treatment of MS-377 markedly reversed the inhibition of [3H]MK-801 binding by PCP in a dose-dependent manner. These effects of MS-377 may depend on its affinity for the sigma-1 receptor, because MS-377 is a selective sigma-1 receptor ligand without any affinity for NMDA receptor ion-channel complex. These observations suggest that the MS-377 indirectly modulated the NMDA receptor ion-channel complex, and the anti-psychotic activities of MS-377, in part, are attributable to such on action via sigma-1 receptor.

Discovery of a potent and selective GPR120 agonist

DEFF Research Database (Denmark)

Shimpukade, Bharat; Hudson, Brian D; Hovgaard, Christine Kiel

2012-01-01

GPR120 is a receptor of unsaturated long-chain fatty acids reported to mediate GLP-1 secretion, insulin sensitization, anti-inflammatory, and anti-obesity effects and is therefore emerging as a new potential target for treatment of type 2 diabetes and metabolic diseases. Further investigation...... is however hindered by the lack of suitable receptor modulators. Screening of FFA1 ligands provided a lead with moderate activity on GPR120 and moderate selectivity over FFA1. Optimization led to the discovery of the first potent and selective GPR120 agonist....

Discovery of OSI-906: a selective and orally efficacious dual inhibitor of the IGF-1 receptor and insulin receptor.

Science.gov (United States)

Mulvihill, Mark J; Cooke, Andrew; Rosenfeld-Franklin, Maryland; Buck, Elizabeth; Foreman, Ken; Landfair, Darla; O'Connor, Matthew; Pirritt, Caroline; Sun, Yingchaun; Yao, Yan; Arnold, Lee D; Gibson, Neil W; Ji, Qun-Sheng

2009-09-01

The IGF-1 receptor (IGF-1R) has been implicated in the promotion of tumorigenesis, metastasis and resistance to cancer therapies. Therefore, this receptor has become a major focus for the development of anticancer agents. Our lead optimization efforts that blended structure-based design and empirical medicinal chemistry led to the discovery of OSI-906, a novel small-molecule dual IGF-1R/insulin receptor (IR) kinase inhibitor. OSI-906 potently and selectively inhibits autophosphorylation of both human IGF-1R and IR, displays in vitro antiproliferative effects in a variety of tumor cell lines and shows robust in vivo anti-tumor efficacy in an IGF-1R-driven xenograft model when administered orally once daily. OSI-906 is a novel, potent, selective and orally bioavailable dual IGF-1R/IR kinase inhibitor with favorable preclinical drug-like properties, which has demonstrated in vivo efficacy in tumor models and is currently in clinical testing.

Tumorigenesis induced by the HHV8-encoded chemokine receptor requires ligand modulation of high constitutive activity

DEFF Research Database (Denmark)

Holst, P J; Rosenkilde, M M; Manfra, D

2001-01-01

sarcoma (KS). Here we demonstrate that several lines of mice carrying mutated receptors deficient in either constitutive activity or chemokine regulation fail to develop KS-like disease. In addition, animals expressing a receptor that preserves chemokine binding and constitutive activity but that does...... not respond to agonist stimulation have a much lower incidence of angiogenic lesions and tumors. These results indicate that induction of the KS-like disease in transgenic mice by ORF74 requires not only high constitutive signaling activity but also modulation of this activity by endogenous chemokines....

Virtual Screening Approaches towards the Discovery of Toll-Like Receptor Modulators

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Lucía Pérez-Regidor

2016-09-01

Full Text Available This review aims to summarize the latest efforts performed in the search for novel chemical entities such as Toll-like receptor (TLR modulators by means of virtual screening techniques. This is an emergent research field with only very recent (and successful contributions. Identification of drug-like molecules with potential therapeutic applications for the treatment of a variety of TLR-regulated diseases has attracted considerable interest due to the clinical potential. Additionally, the virtual screening databases and computational tools employed have been overviewed in a descriptive way, widening the scope for researchers interested in the field.

GABA-A Receptor Modulation and Anticonvulsant, Anxiolytic, and Antidepressant Activities of Constituents from Artemisia indica Linn

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Imran Khan

2016-01-01

Full Text Available Artemisia indica, also known as “Mugwort,” has been widely used in traditional medicines. However, few studies have investigated the effects of nonvolatile components of Artemisia indica on central nervous system’s function. Fractionation of Artemisia indica led to the isolation of carnosol, ursolic acid, and oleanolic acid which were evaluated for their effects on GABA-A receptors in electrophysiological studies in Xenopus oocytes and were subsequently investigated in mouse models of acute toxicity, convulsions (pentylenetetrazole induced seizures, depression (tail suspension and forced swim tests, and anxiety (elevated plus maze and light/dark box paradigms. Carnosol, ursolic acid, and oleanolic acid were found to be positive modulators of α1β2γ2L GABA-A receptors and the modulation was antagonized by flumazenil. Carnosol, ursolic acid, and oleanolic acid were found to be devoid of any signs of acute toxicity (50–200 mg/kg but elicited anticonvulsant, antidepressant, and anxiolytic activities. Thus carnosol, ursolic acid, and oleanolic acid demonstrated CNS activity in mouse models of anticonvulsant, antidepressant, and anxiolysis. The anxiolytic activity of all three compounds was ameliorated by flumazenil suggesting a mode of action via the benzodiazepine binding site of GABA-A receptors.

Small-molecule modulators of PXR and CAR

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Chai, Sergio C.; Cherian, Milu T.; Wang, Yue-Ming; Chen, Taosheng

2016-01-01

Two nuclear receptors, the pregnane X receptor (PXR) and the constitutive androstane receptor (CAR), participate in the xenobiotic detoxification system by regulating the expression of drug-metabolizing enzymes and transporters in order to degrade and excrete foreign chemicals or endogenous metabolites. This review aims to expand the perceived relevance of PXR and CAR beyond their established role as master xenosensors to disease-oriented areas, emphasizing their modulation by small molecules. Structural studies of these receptors have provided much-needed insight into the nature of their binding promiscuity and the important elements that lead to ligand binding. Reports of species- and isoform-selective activation highlight the need for further scrutiny when extrapolating from animal data to humans, as animal models are at the forefront of early drug discovery. PMID:26921498

Selective spatial attention modulates bottom-up informational masking of speech.

Science.gov (United States)

Carlile, Simon; Corkhill, Caitlin

2015-03-02

To hear out a conversation against other talkers listeners overcome energetic and informational masking. Largely attributed to top-down processes, information masking has also been demonstrated using unintelligible speech and amplitude-modulated maskers suggesting bottom-up processes. We examined the role of speech-like amplitude modulations in information masking using a spatial masking release paradigm. Separating a target talker from two masker talkers produced a 20 dB improvement in speech reception threshold; 40% of which was attributed to a release from informational masking. When across frequency temporal modulations in the masker talkers are decorrelated the speech is unintelligible, although the within frequency modulation characteristics remains identical. Used as a masker as above, the information masking accounted for 37% of the spatial unmasking seen with this masker. This unintelligible and highly differentiable masker is unlikely to involve top-down processes. These data provides strong evidence of bottom-up masking involving speech-like, within-frequency modulations and that this, presumably low level process, can be modulated by selective spatial attention.

Endocannabinoid receptor 1 gene variations increase risk for obesity and modulate body mass index in European populations

DEFF Research Database (Denmark)

Benzinou, Michael; Chèvre, Jean-Claude; Ward, Kirsten J

2008-01-01

The therapeutic effects of cannabinoid receptor blockade on obesity-associated phenotypes underline the importance of the endocannabinoid pathway on the energy balance. Using a staged-approach, we examined the contribution of the endocannabinoid receptor 1 gene (CNR1) on obesity and body mass ind...... variations increase the risk for obesity and modulate BMI in our European population. As CB1 is a drug target for obesity, a pharmacogenetic analysis of the endocannabinoid blockade obesity treatment may be of interest to identify best responders....

Repeated administration of alpha7 nicotinic acetylcholine receptor (nAChR) agonists, but not positive allosteric modulators, increases alpha7 nAChR levels in the brain

DEFF Research Database (Denmark)

Christensen, Ditte Z; Mikkelsen, Jens D; Hansen, Henrik H

2010-01-01

AChR binding sites in several brain regions, particularly in the prefrontal cortex. The alpha7 nAChR agonists SSR180711 and PNU-282987 also increase [(125)I]-BTX binding, suggesting that this is a general consequence of alpha7 nAChR agonism. Interestingly, the alpha7 nAChR positive allosteric modulators PNU......The alpha7 nicotinic acetylcholine receptor (nAChR) is an important target for treatment of cognitive deficits in schizophrenia and Alzheimer's disease. However, the receptor desensitizes rapidly in vitro, which has led to concern regarding its applicability as a clinically relevant drug target....... Here we investigate the effects of repeated agonism on alpha7 nAChR receptor levels and responsiveness in vivo in rats. Using [(125)I]-alpha-bungarotoxin (BTX) autoradiography we show that acute or repeated administration with the selective alpha7 nAChR agonist A-582941 increases the number of alpha7 n...

Molecular Mechanism of Action for Allosteric Modulators and Agonists in CC-chemokine Receptor 5 (CCR5).

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Karlshøj, Stefanie; Amarandi, Roxana Maria; Larsen, Olav; Daugvilaite, Viktorija; Steen, Anne; Brvar, Matjaž; Pui, Aurel; Frimurer, Thomas Michael; Ulven, Trond; Rosenkilde, Mette Marie

2016-12-23

The small molecule metal ion chelators bipyridine and terpyridine complexed with Zn 2+ (ZnBip and ZnTerp) act as CCR5 agonists and strong positive allosteric modulators of CCL3 binding to CCR5, weak modulators of CCL4 binding, and competitors for CCL5 binding. Here we describe their binding site using computational modeling, binding, and functional studies on WT and mutated CCR5. The metal ion Zn 2+ is anchored to the chemokine receptor-conserved Glu-283 VII:06/7.39 Both chelators interact with aromatic residues in the transmembrane receptor domain. The additional pyridine ring of ZnTerp binds deeply in the major binding pocket and, in contrast to ZnBip, interacts directly with the Trp-248 VI:13/6.48 microswitch, contributing to its 8-fold higher potency. The impact of Trp-248 was further confirmed by ZnClTerp, a chloro-substituted version of ZnTerp that showed no inherent agonism but maintained positive allosteric modulation of CCL3 binding. Despite a similar overall binding mode of all three metal ion chelator complexes, the pyridine ring of ZnClTerp blocks the conformational switch of Trp-248 required for receptor activation, thereby explaining its lack of activity. Importantly, ZnClTerp becomes agonist to the same extent as ZnTerp upon Ala mutation of Ile-116 III:16/3.40 , a residue that constrains the Trp-248 microswitch in its inactive conformation. Binding studies with 125 I-CCL3 revealed an allosteric interface between the chemokine and the small molecule binding site, including residues Tyr-37 I:07/1.39 , Trp-86 II:20/2.60 , and Phe-109 III:09/3.33 The small molecules and CCL3 approach this interface from opposite directions, with some residues being mutually exploited. This study provides new insight into the molecular mechanism of CCR5 activation and paves the way for future allosteric drugs for chemokine receptors. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

GABA(A) receptor modulation during adolescence alters adult ethanol intake and preference in rats.

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Hulin, Mary W; Amato, Russell J; Winsauer, Peter J

2012-02-01

To address the hypothesis that GABA(A) receptor modulation during adolescence may alter the abuse liability of ethanol during adulthood, the effects of adolescent administration of both a positive and negative GABA(A) receptor modulator on adult alcohol intake and preference were assessed. Three groups of adolescent male rats received 12 injections of lorazepam (3.2 mg/kg), dehydroepiandrosterone (DHEA, 56 mg/kg), or vehicle on alternate days starting on postnatal day (PD) 35. After this time, the doses were increased to 5.6 and 100 mg/kg, respectively, for 3 more injections on alternate days. Subjects had access to 25 to 30 g of food daily, during the period of the first 6 injections, and 18 to 20 g thereafter. Food intake of each group was measured 60 minutes after food presentation, which occurred immediately after drug administration on injection days or at the same time of day on noninjection days. When subjects reached adulthood (PD 88), ethanol preference was determined on 2 separate occasions, an initial 3-day period and a 12-day period, in which increasing concentrations of ethanol were presented. During each preference test, intake of water, saccharin, and an ethanol/saccharin solution was measured after each 23-hour access period. During adolescence, lorazepam increased 60-minute food intake, and this effect was enhanced under the more restrictive feeding schedule. DHEA had the opposite effect on injection days, decreasing food intake compared with noninjection days. In adulthood, the lorazepam-treated group preferred the 2 lowest concentrations of ethanol/saccharin more than saccharin alone compared with vehicle-treated subjects, which showed no preference for any concentration of ethanol/saccharin over saccharin. DHEA-treated subjects showed no preference among the 3 solutions. These data demonstrate that GABA(A) receptor modulation during adolescence can alter intake and preference for ethanol in adulthood and highlights the importance of drug history

Novel 2-aminotetralin and 3-aminochroman derivatives as selective serotonin 5-HT7 receptor agonists and antagonists.

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Holmberg, Pär; Sohn, Daniel; Leideborg, Robert; Caldirola, Patrizia; Zlatoidsky, Pavel; Hanson, Sverker; Mohell, Nina; Rosqvist, Susanne; Nordvall, Gunnar; Johansson, Anette M; Johansson, Rolf

2004-07-29

The understanding of the physiological role of the G-protein coupled serotonin 5-HT(7) receptor is largely rudimentary. Therefore, selective and potent pharmacological tools will add to the understanding of serotonergic effects mediated through this receptor. In this report, we describe two compound classes, chromans and tetralins, encompassing compounds with nanomolar affinity for the 5-HT(7) receptor and with good selectivity. Within theses classes, we have discovered both agonists and antagonists that can be used for further understanding of the pharmacology of the 5-HT(7) receptor.

Determinants of positive cooperativity between strychnine-like allosteric modulators and N-methylscopolamine at muscarinic receptors

Czech Academy of Sciences Publication Activity Database

Jakubík, Jan; Doležal, Vladimír

2006-01-01

Roč. 30, č. 1-2 (2006), s. 111-112 ISSN 0895-8696 R&D Projects: GA ČR(CZ) GA305/05/0452; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic receptors * strychnine -like allosteric modulators * cooperativity Subject RIV: ED - Physiology Impact factor: 2.965, year: 2006

Modulation of cytokine and cytokine receptor/antagonist by treatment with doxycycline and tetracycline in patients with dengue fever.

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Castro, J E Z; Vado-Solis, I; Perez-Osorio, C; Fredeking, T M

2011-01-01

Dengue virus infection can lead to dengue fever (DF) or dengue hemorrhagic fever (DHF). Disease severity has been linked to an increase in various cytokine levels. In this study, we evaluated the effectiveness of doxycycline and tetracycline to modulate serum levels of IL-6, IL-1B, and TNF and cytokine receptor/receptor antagonist TNF-R1 and IL-1RA in patients with DF or DHF. Hospitalized patients were randomized to receive standard supportive care or supportive care combined with doxycycline or tetracycline therapy. Serum cytokine and cytokine receptor/antagonist levels were determined at the onset of therapy and after 3 and 7 days. Cytokine and cytokine receptor/antagonist levels were substantially elevated at day 0. IL-6, IL-1β, and TNF remained at or above day 0 levels throughout the study period in untreated patients. Treatment with tetracycline or doxycycline resulted in a significant decline in cytokine levels. Similarly, IL-1RA and TNF-R1 serum concentrations were elevated at baseline and showed a moderate increase among untreated patients. Both drugs resulted in a significant rise in IL-1Ra levels by day 3 in patients. In contrast, treatment did not affect a similar result for TNF-R1. When compared to the control group, however, a significant rise post-treatment was seen upon intragroup analysis. Further analysis demonstrated that doxycycline was significantly more effective at modulating cytokine and cytokine receptor/antagonist levels than tetracycline.

Understanding the Differential Selectivity of Arrestins toward the Phosphorylation State of the Receptor

NARCIS (Netherlands)

Sensoy, Ozge; de Sousa Moreira, Irina; Morra, Giulia

2016-01-01

Proteins in the arrestin family exhibit a conserved structural fold that nevertheless allows for significant differences in their selectivity for G-protein coupled receptors (GPCRs) and their phosphorylation states. To reveal the mechanism of activation that prepares arrestin for selective

Piracetam Defines a New Binding Site for Allosteric Modulators of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors§

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Ahmed, Ahmed H.; Oswald, Robert E.

2010-01-01

Glutamate receptors are the most prevalent excitatory neurotransmitter receptors in the vertebrate central nervous system and are important potential drug targets for cognitive enhancement and the treatment of schizophrenia. Allosteric modulators of AMPA receptors promote dimerization by binding to a dimer interface and reducing desensitization and deactivation. The pyrrolidine allosteric modulators, piracetam and aniracetam, were among the first of this class of drugs to be discovered. We have determined the structure of the ligand binding domain of the AMPA receptor subtypes GluA2 and GluA3 with piracetam and a corresponding structure of GluA3 with aniracetam. Both drugs bind to both GluA2 and GluA3 in a very similar manner, suggesting little subunit specificity. However, the binding sites for piracetam and aniracetam differ considerably. Aniracetam binds to a symmetrical site at the center of the dimer interface. Piracetam binds to multiple sites along the dimer interface with low occupation, one of which is a unique binding site for potential allosteric modulators. This new site may be of importance in the design of new allosteric regulators. PMID:20163115

Comparison of the effects of the GABAB receptor positive modulator BHF177 and the GABAB receptor agonist baclofen on anxiety-like behavior, learning, and memory in mice.

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Li, Xia; Risbrough, Victoria B; Cates-Gatto, Chelsea; Kaczanowska, Katarzyna; Finn, M G; Roberts, Amanda J; Markou, Athina

2013-07-01

γ-Aminobutyric acid B (GABAB) receptor activation is a potential therapeutic approach for the treatment of drug addiction, pain, anxiety, and depression. However, full agonists of this receptor induce side-effects, such as sedation, muscle relaxation, tolerance, and cognitive disruption. Positive allosteric modulators (PAMs) of the GABAB receptor may have similar therapeutic effects as agonists with superior side-effect profiles. The present study behaviorally characterized N-([1R,2R,4S]-bicyclo[2.2.1]hept-2-yl)-2-methyl-5-(4-[trifluoromethyl]phenyl)-4-pyrimidinamine (BHF177), a GABAB receptor PAM, in mouse models of anxiety-like behavior, learning and memory. In addition, the effects of BHF177 were compared with the agonist baclofen. Unlike the anxiolytic chlordiazepoxide, baclofen (0.5, 1.5, and 2.5 mg/kg, intraperitoneally) and BHF177 (10, 20, and 40 mg/kg, orally) had no effect on anxiety-like behavior in the elevated plus maze, light/dark box, or Vogel conflict test. Baclofen increased punished drinking in the Vogel conflict test, but this effect may be attributable to the analgesic actions of baclofen. At the highest dose tested (2.5 mg/kg), baclofen-treated mice exhibited sedation-like effects (i.e., reduced locomotor activity) across many of the tests, whereas BHF177-treated mice exhibited no sedation-like effects. BHF177 exhibited pro-convulsion properties only in mice, but not in rats, indicating that this effect may be species-specific. At doses that were not sedative or pro-convulsant, baclofen and BHF177 had no selective effects on fear memory retrieval in contextual and cued fear conditioning or spatial learning and memory in the Barnes maze. These data suggest that BHF177 has little sedative activity, no anxiolytic-like profile, and minimal impairment of learning and memory in mice. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in chronic daily cannabis smokers.

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Hirvonen, J; Goodwin, R S; Li, C-T; Terry, G E; Zoghbi, S S; Morse, C; Pike, V W; Volkow, N D; Huestis, M A; Innis, R B

2012-06-01

Chronic cannabis (marijuana, hashish) smoking can result in dependence. Rodent studies show reversible downregulation of brain cannabinoid CB(1) (cannabinoid receptor type 1) receptors after chronic exposure to cannabis. However, whether downregulation occurs in humans who chronically smoke cannabis is unknown. Here we show, using positron emission tomography imaging, reversible and regionally selective downregulation of brain cannabinoid CB(1) receptors in human subjects who chronically smoke cannabis. Downregulation correlated with years of cannabis smoking and was selective to cortical brain regions. After ∼4 weeks of continuously monitored abstinence from cannabis on a secure research unit, CB(1) receptor density returned to normal levels. This is the first direct demonstration of cortical cannabinoid CB(1) receptor downregulation as a neuroadaptation that may promote cannabis dependence in human brain.

Data for amino acid alignment of Japanese stingray melanocortin receptors with other gnathostome melanocortin receptor sequences, and the ligand selectivity of Japanese stingray melanocortin receptors

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Akiyoshi Takahashi

2016-06-01

Full Text Available This article contains structure and pharmacological characteristics of melanocortin receptors (MCRs related to research published in “Characterization of melanocortin receptors from stingray Dasyatis akajei, a cartilaginous fish” (Takahashi et al., 2016 [1]. The amino acid sequences of the stingray, D. akajei, MC1R, MC2R, MC3R, MC4R, and MC5R were aligned with the corresponding melanocortin receptor sequences from the elephant shark, Callorhinchus milii, the dogfish, Squalus acanthias, the goldfish, Carassius auratus, and the mouse, Mus musculus. These alignments provide the basis for phylogenetic analysis of these gnathostome melanocortin receptor sequences. In addition, the Japanese stingray melanocortin receptors were separately expressed in Chinese Hamster Ovary cells, and stimulated with stingray ACTH, α-MSH, β-MSH, γ-MSH, δ-MSH, and β-endorphin. The dose response curves reveal the order of ligand selectivity for each stingray MCR.

Novel, potent, and radio-iodinatable somatostatin receptor 1 (sst1) selective analogues.

Science.gov (United States)

Erchegyi, Judit; Cescato, Renzo; Grace, Christy Rani R; Waser, Beatrice; Piccand, Véronique; Hoyer, Daniel; Riek, Roland; Rivier, Jean E; Reubi, Jean Claude

2009-05-14

The proposed sst(1) pharmacophore (J. Med. Chem. 2005, 48, 523-533) derived from the NMR structures of a family of mono- and dicyclic undecamers was used to design octa-, hepta-, and hexamers with high affinity and selectivity for the somatostatin sst(1) receptor. These compounds were tested for their in vitro binding properties to all five somatostatin (SRIF) receptors using receptor autoradiography; those with high SRIF receptor subtype 1 (sst(1)) affinity and selectivity were shown to be agonists when tested functionally in a luciferase reporter gene assay. Des-AA(1,4-6,10,12,13)-[DTyr(2),DAgl(NMe,2naphthoyl)(8),IAmp(9)]-SRIF-Thr-NH(2) (25) was radio-iodinated ((125)I-25) and specifically labeled sst(1)-expressing cells and tissues. 3D NMR structures were calculated for des-AA(1,4-6,10,12,13)-[DPhe(2),DTrp(8),IAmp(9)]-SRIF-Thr-NH(2) (16), des-AA(1,2,4-6,10,12,13)-[DAgl(NMe,2naphthoyl)(8),IAmp(9)]-SRIF-Thr-NH(2) (23), and des-AA(1,2,4-6,10,12,13)-[DAgl(NMe,2naphthoyl)(8),IAmp(9),Tyr(11)]-SRIF-NH(2) (27) in DMSO. Though the analogues have the sst(1) pharmacophore residues at the previously determined distances from each other, the positioning of the aromatic residues in 16, 23, and 27 is different from that described earlier, suggesting an induced fit mechanism for sst(1) binding of these novel, less constrained sst(1)-selective family members.

Presynaptic membrane receptors in acetylcholine release modulation in the neuromuscular synapse.

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Tomàs, Josep; Santafé, Manel M; Garcia, Neus; Lanuza, Maria A; Tomàs, Marta; Besalduch, Núria; Obis, Teresa; Priego, Mercedes; Hurtado, Erica

2014-05-01

Over the past few years, we have studied, in the mammalian neuromuscular junction (NMJ), the local involvement in transmitter release of the presynaptic muscarinic ACh autoreceptors (mAChRs), purinergic adenosine autoreceptors (P1Rs), and trophic factor receptors (TFRs; for neurotrophins and trophic cytokines) during development and in the adult. At any given moment, the way in which a synapse works is largely the logical outcome of the confluence of these (and other) metabotropic signalling pathways on intracellular kinases, which phosphorylate protein targets and materialize adaptive changes. We propose an integrated interpretation of the complementary function of these receptors in the adult NMJ. The activity of a given receptor group can modulate a given combination of spontaneous, evoked, and activity-dependent release characteristics. For instance, P1Rs can conserve resources by limiting spontaneous quantal leak of ACh (an A1 R action) and protect synapse function, because stimulation with adenosine reduces the magnitude of depression during repetitive activity. The overall outcome of the mAChRs seems to contribute to upkeep of spontaneous quantal output of ACh, save synapse function by decreasing the extent of evoked release (mainly an M2 action), and reduce depression. We have also identified several links among P1Rs, mAChRs, and TFRs. We found a close dependence between mAChR and some TFRs and observed that the muscarinic group has to operate correctly if the tropomyosin-related kinase B receptor (trkB) is also to operate correctly, and vice versa. Likewise, the functional integrity of mAChRs depends on P1Rs operating normally. Copyright © 2014 Wiley Periodicals, Inc.

Stress-induced alterations in 5-HT1A receptor transcriptional modulators NUDR and Freud-1.

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Szewczyk, Bernadeta; Kotarska, Katarzyna; Daigle, Mireille; Misztak, Paulina; Sowa-Kucma, Magdalena; Rafalo, Anna; Curzytek, Katarzyna; Kubera, Marta; Basta-Kaim, Agnieszka; Nowak, Gabriel; Albert, Paul R

2014-11-01

The effect of stress on the mRNA and protein level of the 5-HT1A receptor and two of its key transcriptional modulators, NUDR and Freud-1, was examined in the prefrontal cortex (PFC) and hippocampus (Hp) using rodent models: olfactory bulbectomy (OB) and prenatal stress (PS) in male and female rats; chronic mild stress in male rats (CMS) and pregnancy stress. In PFC, CMS induced the most widespread changes, with significant reduction in both mRNA and protein levels of NUDR, 5-HT1A receptor and in Freud-1 mRNA; while in Hp 5-HT1A receptor and Freud-1 protein levels were also decreased. In male, but not female OB rats PFC Freud-1 and 5-HT1A receptor protein levels were reduced, while in Hp 5-HT1A receptor, Freud-1 and NUDR mRNA's but not protein were reduced. In PS rats PFC 5-HT1A receptor protein was reduced more in females than males; while in Hp Freud-1 protein was increased in females. In pregnancy stress, PFC NUDR, Freud-1 and 5-HT1A protein receptor levels were reduced, and in HP 5-HT1A receptor protein levels were also reduced; in HP only NUDR and Freud-1 mRNA levels were reduced. Overall, CMS and stress during pregnancy produced the most salient changes in 5-HT1A receptor and transcription factor expression, suggesting a primary role for altered transcription factor expression in chronic regulation of 5-HT1A receptor expression. By contrast, OB (in males) and PS (in females) produced gender-specific reductions in PFC 5-HT1A receptor protein levels, suggesting a role for post-transcriptional regulation. These and previous data suggest that chronic stress might be a key regulator of NUDR/Freud-1 gene expression.

Activation and modulation of human α4β2 nicotinic acetylcholine receptors by the neonicotinoids clothianidin and imidacloprid.

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Li, Ping; Ann, Jason; Akk, Gustav

2011-08-01

Neonicotinoids are synthetic, nicotine-derived insecticides used for agricultural and household pest control. Though highly effective at activating insect nicotinic receptors, many neonicotinoids are also capable of directly activating and/or modulating the activation of vertebrate nicotinic receptors. In this study, we have investigated the actions of the neonicotinoids clothianidin (CTD) and imidacloprid (IMI) on human neuronal α4β2 nicotinic acetylcholine receptors. The data demonstrate that the compounds are weak agonists of the human receptors with relative peak currents of 1-4% of the response to 1 mM acetylcholine (ACh). Coapplication of IMI strongly inhibited currents elicited by ACh. From Schild plot analysis, we estimate that the affinity of IMI for the human α4β2 receptor is 18 μM. The application of low concentrations of CTD potentiated responses to low concentrations of ACh, suggesting that receptors occupied by one ACh and one CTD molecule have a higher gating efficacy than receptors with one ACh bound. Interestingly, subunit stoichiometry affected inhibition by CTD, with (α4)(2) (β2)(3) receptors significantly more strongly inhibited than the (α4)(3) (β2)(2) receptors. Copyright © 2011 Wiley-Liss, Inc.

Current status of muscarinic M1 and M4 receptors as drug targets for neurodegenerative diseases.

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Felder, Christian C; Goldsmith, Paul J; Jackson, Kimberley; Sanger, Helen E; Evans, David A; Mogg, Adrian J; Broad, Lisa M

2018-01-25

The cholinergic signalling system has been an attractive pathway to seek targets for modulation of arousal, cognition, and attention which are compromised in neurodegenerative and neuropsychiatric diseases. The acetylcholine muscarinic receptor M1 and M4 subtypes which are highly expressed in the central nervous system, in cortex, hippocampus and striatum, key areas of cognitive and neuropsychiatric control, have received particular attention. Historical muscarinic drug development yielded first generation agonists with modest selectivity for these two receptor targets over M2 and M3 receptors, the major peripheral sub-types hypothesised to underlie the dose-limiting clinical side effects. More recent compound screening and medicinal chemistry optimization of orthosteric and allosteric agonists, and positive allosteric modulators binding to sites distinct from the highly homologous acetylcholine binding pocket have yielded a collection of highly selective tool compounds for preclinical validation studies. Several M1 selective ligands have progressed to early clinical development and in time will hopefully lead to useful therapeutics for treating symptoms of Alzheimer's disease and related disorders. Copyright © 2018. Published by Elsevier Ltd.

A dynamic view of molecular switch behavior at serotonin receptors: implications for functional selectivity.

Directory of Open Access Journals (Sweden)

Maria Martí-Solano

Full Text Available Functional selectivity is a property of G protein-coupled receptors that allows them to preferentially couple to particular signaling partners upon binding of biased agonists. Publication of the X-ray crystal structure of serotonergic 5-HT1B and 5-HT2B receptors in complex with ergotamine, a drug capable of activating G protein coupling and β-arrestin signaling at the 5-HT1B receptor but clearly favoring β-arrestin over G protein coupling at the 5-HT2B subtype, has recently provided structural insight into this phenomenon. In particular, these structures highlight the importance of specific residues, also called micro-switches, for differential receptor activation. In our work, we apply classical molecular dynamics simulations and enhanced sampling approaches to analyze the behavior of these micro-switches and their impact on the stabilization of particular receptor conformational states. Our analysis shows that differences in the conformational freedom of helix 6 between both receptors could explain their different G protein-coupling capacity. In particular, as compared to the 5-HT1B receptor, helix 6 movement in the 5-HT2B receptor can be constrained by two different mechanisms. On the one hand, an anchoring effect of ergotamine, which shows an increased capacity to interact with the extracellular part of helices 5 and 6 and stabilize them, hinders activation of a hydrophobic connector region at the center of the receptor. On the other hand, this connector region in an inactive conformation is further stabilized by unconserved contacts extending to the intracellular part of the 5-HT2B receptor, which hamper opening of the G protein binding site. This work highlights the importance of considering receptor capacity to adopt different conformational states from a dynamic perspective in order to underpin the structural basis of functional selectivity.

α2-Adrenergic modulation of the glutamate receptor and transporter function in a chronic ocular hypertension model.

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Jung, Kyoung In; Kim, Jie Hyun; Park, Chan Kee

2015-10-15

Excitotoxicity, glutamate-induced toxic effects to retinal ganglion cells (RGCs), is one of several mechanisms of RGC loss suggested in glaucoma. In this study, we focused on the role of glutamate transporter of glial cells as well as N-methyl-d-aspartate (NMDA) receptor with regard to glutamate toxicity in glaucoma. We also investigated whether α2-adrenoceptor activation could modulate glutamate transporters and NMDA receptors in a chronic ocular hypertension model. Brimonidine 0.15% was administered topically to the eyes of experimental glaucoma and control animals twice daily. After 8 weeks of intraocular pressure (IOP) elevation, staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) revealed an increase in the ganglion cell layer, and the number of TUNEL-positive cells was reduced by brimonidine treatment (P<0.05). Animals with experimentally induced glaucoma exhibited an increase in retinal stress marker glial fibrillary acidic protein (GFAP) immunoreactivity; brimonidine treatment reduced GFAP. Excitatory amino acid transporter 1(EAAT1) expression remained stable throughout the period of chronic ocular hypertension. α2-Adrenergic treatment upregulated EAAT1 protein levels (P<0.05). NMDA receptor (GluN1) expression was stimulated by chronic elevation of IOP, and GluN1-positive cells in ganglion cell layer were co-localized with TUNEL staining. Brimonidine administration suppressed GluN1 levels (P<0.05). These results indicate that brimonidine decreased RGC apoptosis, upregulating EAAT1 and downregulating NMDA receptors. We suggest that topical brimonidine treatment may decrease the glutamate excitotoxicity through modulation of glutamate transporter and NMDA receptor in glaucoma. Copyright © 2015 Elsevier B.V. All rights reserved.

Diversifying selection and functional analysis of interleukin-4 suggests antagonism-driven evolution at receptor-binding interfaces

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Brown Scott

2010-07-01

Full Text Available Abstract Background Interleukin-4 (IL4 is a secreted immunoregulatory cytokine critically involved in host protection from parasitic helminths 1. Reasoning that helminths may have evolved mechanisms to antagonize IL4 to maximize their dispersal, we explored mammalian IL4 evolution. Results This analysis revealed evidence of diversifying selection at 15 residues, clustered in epitopes responsible for IL4 binding to its Type I and Type II receptors. Such a striking signature of selective pressure suggested either recurrent episodes of pathogen antagonism or ligand/receptor co-evolution. To test the latter possibility, we performed detailed functional analysis of IL4 allotypes expressed by Mus musculus musculus and Mus musculus castaneus, which happen to differ at 5 residues (including three at positively selected sites in and adjacent to the site 1 epitope that binds the IL4Rα subunit shared by the Type I and Type II IL4 receptors. We show that this intra-species variation affects the ability of IL4 neither to bind IL4 receptor alpha (IL4Rα nor to signal biological responses through its Type I receptor. Conclusions Our results -- reminiscent of clustered positively selected sites revealing functionally important residues at host-virus interaction interfaces -- are consistent with IL4 having evolved to avoid recurrent pathogen antagonism, while maintaining the capacity to bind and signal through its cognate receptor. This work exposes what may be a general feature of evolutionary conflicts fought by pathogen antagonists at host protein-protein interaction interfaces involved in immune signaling: the emergence of receptor-binding ligand epitopes capable of buffering amino acid variation.

[Roles of protease-activated receptor-2 (PAR-2), a G protein-coupled receptor, in modulation of exocrine gland functions].

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