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Szczurowska E, Szánti-Pintér E, Chetverikov N, Randáková A, Kudová E, Jakubík J. Modulation of Muscarinic Signalling in the Central Nervous System by Steroid Hormones and Neurosteroids. Int J Mol Sci 2022; 24:ijms24010507. [PMID: 36613951 PMCID: PMC9820491 DOI: 10.3390/ijms24010507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/29/2022] Open
Abstract
Muscarinic acetylcholine receptors expressed in the central nervous system mediate various functions, including cognition, memory, or reward. Therefore, muscarinic receptors represent potential pharmacological targets for various diseases and conditions, such as Alzheimer's disease, schizophrenia, addiction, epilepsy, or depression. Muscarinic receptors are allosterically modulated by neurosteroids and steroid hormones at physiologically relevant concentrations. In this review, we focus on the modulation of muscarinic receptors by neurosteroids and steroid hormones in the context of diseases and disorders of the central nervous system. Further, we propose the potential use of neuroactive steroids in the development of pharmacotherapeutics for these diseases and conditions.
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Affiliation(s)
- Ewa Szczurowska
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo Náměstí 2, Prague 6, 166 10 Prague, Czech Republic
| | - Eszter Szánti-Pintér
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo Náměstí 2, Prague 6, 166 10 Prague, Czech Republic
| | - Nikolai Chetverikov
- Institute of Physiology, Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Alena Randáková
- Institute of Physiology, Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Eva Kudová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo Náměstí 2, Prague 6, 166 10 Prague, Czech Republic
- Correspondence: (E.K.); (J.J.)
| | - Jan Jakubík
- Institute of Physiology, Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
- Correspondence: (E.K.); (J.J.)
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West EG, McDermott C, Chess-Williams R, Sellers DJ. Mirabegron and solifenacin are effective for the management of the increased urinary frequency induced by psychological stress in female mice. Sci Rep 2022; 12:12365. [PMID: 35858980 PMCID: PMC9300733 DOI: 10.1038/s41598-022-16487-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/11/2022] [Indexed: 11/09/2022] Open
Abstract
Evidence to support the effectiveness of β3-adrenoceptor agonist mirabegron and anti-muscarinic solifenacin in the management of bladder dysfunction caused by psychological stress is lacking. This study investigates whether mirabegron or solifenacin reduces the bladder overactivity caused by water avoidance stress (WAS) in mice. Female mice were exposed to WAS for 1 h/day for 10 days and received either placebo, solifenacin or mirabegron in drinking water. Controls were age-matched without stress exposure. Voiding behaviour and functional isolated whole bladder responses during distension and in response to pharmacological agents and electrical field stimulation was investigated. Urinary frequency was significantly increased following stress. Mice treated with mirabegron or solifenacin displayed significantly fewer voiding events compared to the stressed mice, and voiding frequency in drug-treated animals was comparable to unstressed controls. The maximal contractile responses of bladders to carbachol were significantly enhanced by stress and reduced by mirabegron but not solifenacin. The frequency of phasic bladder contractions following stimulation with carbachol was significantly enhanced following stress and remained elevated in the mirabegron treated group. However, treatment with solifenacin significantly reduced the frequency of phasic contractions to unstressed control levels. Solifenacin and mirabegron are beneficial in reducing the overall voiding dysfunction caused by WAS in mice.
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Affiliation(s)
- Eliza G West
- Centre for Urology Research, Faculty of Health Sciences and Medicine, Bond University, Robina, QLD, 4229, Australia
| | - Catherine McDermott
- Centre for Urology Research, Faculty of Health Sciences and Medicine, Bond University, Robina, QLD, 4229, Australia
| | - Russ Chess-Williams
- Centre for Urology Research, Faculty of Health Sciences and Medicine, Bond University, Robina, QLD, 4229, Australia
| | - Donna J Sellers
- Centre for Urology Research, Faculty of Health Sciences and Medicine, Bond University, Robina, QLD, 4229, Australia.
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Malaiyandi LM, Sharthiya H, Surachaicharn N, Shams Y, Arshad M, Schupbach C, Kopf PG, Dineley KE. M 3-subtype muscarinic receptor activation stimulates intracellular calcium oscillations and aldosterone production in human adrenocortical HAC15 cells. Mol Cell Endocrinol 2018; 478:1-9. [PMID: 29959979 PMCID: PMC6193837 DOI: 10.1016/j.mce.2018.06.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/26/2018] [Accepted: 06/26/2018] [Indexed: 11/25/2022]
Abstract
A previous body of work in bovine and rodent models shows that cholinergic agonists modulate the secretion of steroid hormones from the adrenal cortex. In this study we used live-cell Ca2+ imaging to investigate cholinergic activity in the HAC15 human adrenocortical carcinoma cell line. The cholinergic agonists carbachol and acetylcholine triggered heterogeneous Ca2+ oscillations that were strongly inhibited by antagonists with high affinity for the M3 muscarinic receptor subtype, while preferential block of M1 or M2 receptors was less effective. Acute exposure to carbachol and acetylcholine modestly elevated aldosterone secretion in HAC15 cells, and this effect was also diminished by M3 inhibition. HAC15 cells expressed relatively high levels of mRNA for M3 and M2 receptors, while M1 and M5 mRNA were much lower. In conclusion, our data extend previous findings in non-human systems to implicate the M3 receptor as the dominant muscarinic receptor in the human adrenal cortex.
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Affiliation(s)
- Latha M Malaiyandi
- Department of Anatomy, Midwestern University, Downers Grove, IL, 60515, USA.
| | - Harsh Sharthiya
- Department of Anatomy, Midwestern University, Downers Grove, IL, 60515, USA.
| | | | - Yara Shams
- Department of Pharmacology, Midwestern University, Downers Grove, IL, 60515, USA.
| | - Mohammad Arshad
- Department of Anatomy, Midwestern University, Downers Grove, IL, 60515, USA.
| | - Chad Schupbach
- Department of Pharmacology, Midwestern University, Downers Grove, IL, 60515, USA.
| | - Phillip G Kopf
- Department of Pharmacology, Midwestern University, Downers Grove, IL, 60515, USA.
| | - Kirk E Dineley
- Department of Pharmacology, Midwestern University, Downers Grove, IL, 60515, USA.
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Kankanamge D, Ratnayake K, Samaradivakara S, Karunarathne A. Melanopsin (Opn4) utilizes Gα i and Gβγ as major signal transducers. J Cell Sci 2018; 131:jcs.212910. [PMID: 29712722 DOI: 10.1242/jcs.212910] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/23/2018] [Indexed: 01/16/2023] Open
Abstract
Melanopsin (Opn4), a ubiquitously expressed photoreceptor in all classes of vertebrates, is crucial for both visual and non-visual signaling. Opn4 supports visual functions of the eye by sensing radiance levels and discriminating contrast and brightness. Non-image-forming functions of Opn4 not only regulate circadian behavior, but also control growth and development processes of the retina. It is unclear how a single photoreceptor could govern such a diverse range of physiological functions; a role in genetic hardwiring could be one explanation, but molecular and mechanistic evidence is lacking. In addition to its role in canonical Gq pathway activation, here we demonstrate that Opn4 efficiently activates Gi heterotrimers and signals through the G protein βγ. Compared with the low levels of Gi pathway activation observed for several Gq-coupled receptors, the robust Gαi and Gβγ signaling of Opn4 led to both generation of PIP3 and directional migration of RAW264.7 macrophages. We propose that the ability of Opn4 to signal through Gαi and Gβγ subunits is a major contributor to its functional diversity.
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Affiliation(s)
- Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Saroopa Samaradivakara
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
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Thomsen M, Sørensen G, Dencker D. Physiological roles of CNS muscarinic receptors gained from knockout mice. Neuropharmacology 2017; 136:411-420. [PMID: 28911965 DOI: 10.1016/j.neuropharm.2017.09.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 09/06/2017] [Accepted: 09/08/2017] [Indexed: 12/29/2022]
Abstract
Because the five muscarinic acetylcholine receptor subtypes have overlapping distributions in many CNS tissues, and because ligands with a high degree of selectivity for a given subtype long remained elusive, it has been difficult to determine the physiological functions of each receptor. Genetically engineered knockout mice, in which one or more muscarinic acetylcholine receptor subtype has been inactivated, have been instrumental in identifying muscarinic receptor functions in the CNS, at the neuronal, circuit, and behavioral level. These studies revealed important functions of muscarinic receptors modulating neuronal activity and neurotransmitter release in many brain regions, shaping neuronal plasticity, and affecting functions ranging from motor and sensory function to cognitive processes. As gene targeting technology evolves including the use of conditional, cell type specific strains, knockout mice are likely to continue to provide valuable insights into brain physiology and pathophysiology, and advance the development of new medications for a range of conditions such as Alzheimer's disease, Parkinson's disease, schizophrenia, and addictions, as well as non-opioid analgesics. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- Morgane Thomsen
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen and University of Copenhagen, Denmark; Alcohol and Drug Abuse Research Center, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA.
| | - Gunnar Sørensen
- Alcohol and Drug Abuse Research Center, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA
| | - Ditte Dencker
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen and University of Copenhagen, Denmark
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The role of glutamatergic, GABA-ergic, and cholinergic receptors in depression and antidepressant-like effect. Pharmacol Rep 2015; 68:443-50. [PMID: 26922551 DOI: 10.1016/j.pharep.2015.10.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 11/23/2022]
Abstract
Depression is one of the most common mental disorders and social issue worldwide. Although there are many antidepressants available, the effectiveness of the therapy is still a serious issue. Moreover, there are many limitations of currently used antidepressants, including slow onset of action, numerous side effects, or the fact that many patients do not respond adequately to the treatment. Therefore, scientists are searching for new compounds with different mechanisms of action. Numerous data indicate the important role of glutamatergic, GABA-ergic, and cholinergic receptors in the pathomechanism of major depressive disorder. This review presents the role of glutamatergic, GABA-ergic, and cholinergic receptors in depression and antidepressant-like effect.
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Abstract
The physiological role of muscarinic receptors is highly complex and, although not completely understood, has become clearer over the last decade. Recent pharmacological evidence with novel compounds, together with data from transgenic mice, suggests that all five subtypes have defined functions in the nervous system as well as mediating the non neuronal, hormonal actions of acetylcholine. Numerous novel agonists, allosteric regulators, and antagonists have now been identified with authentic subtype specificity in vitro and in vivo. These compounds provide additional pharmacological opportunities for selective subtype modulation as well as a new generation of muscarinic receptor-based therapeutics.
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Affiliation(s)
- Richard M Eglen
- Corning Life Sciences, 900 Chelmsford St., MA 01851, Lowell, USA.
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Fiorino DF, Garcia-Guzman M. Muscarinic pain pharmacology: realizing the promise of novel analgesics by overcoming old challenges. Handb Exp Pharmacol 2012:191-221. [PMID: 22222700 DOI: 10.1007/978-3-642-23274-9_9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The antinociceptive and analgesic effects of muscarinic receptor ligands in human and nonhuman species have been evident for more than half a century. In this review, we describe the current understanding of the roles of different muscarinic subtypes in pain modulation and their mechanism of action along the pain signaling pathway, including peripheral nociception, spinal cord pain processing, and supraspinal analgesia. Extensive preclinical and clinical validation of these mechanisms points to the development of selective muscarinic agonists as one of the most exciting and promising avenues toward novel pain medications.
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Affiliation(s)
- Dennis F Fiorino
- Vertex Pharmaceuticals Inc., 11010 Torreyana Road, San Diego, CA 92127, USA.
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Turner J, Hughes LF, Toth LA. Sleep, activity, temperature and arousal responses of mice deficient for muscarinic receptor M2 or M4. Life Sci 2009; 86:158-69. [PMID: 19958780 DOI: 10.1016/j.lfs.2009.11.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 11/18/2009] [Accepted: 11/23/2009] [Indexed: 01/14/2023]
Abstract
AIMS The type 2 muscarinic receptor (M2R) differs from the other G-protein-coupled muscarinic receptor (type 4, or M4R) in tissue distribution and physiologic effects. We studied the impact of these receptors on sleep and arousal by using M2R and M4R knock-out (KO) mice. MAIN METHODS M2R and M4R KO and genetically intact mice were compared in terms of normal patterns of sleep, responses to sleep loss, infectious challenge and acoustic startle, and acoustic prepulse inhibition of startle (PPI). KEY FINDINGS Under basal conditions, M2R and M4R KO mice do not differ from the background strain or each other in the amount or diurnal pattern of sleep, locomotor activity, and body temperature. After enforced sleep loss, M2R KO mice, in contrast to the other two strains, show no rebound in slow-wave sleep (SWS) time, although their SWS is consolidated, and they show a greater rebound in time spent in REMS (rapid-eye-movement sleep) and REMS consolidation. During influenza infection, M2R KO mice, as compared with the other strains, show marked hypothermia and a less robust increase in SWS. During Candida albicans infection, M2R KO mice show a greater increase in SWS and a greater inflammatory response than do the other strains. M2R KO mice also show greater acoustic startle amplitude than does the background strain, although PPI was not different across the 3 strains over a range of stimulus intensities. SIGNIFICANCE Taken together, these findings support different roles for M2R and M4R in the modulation of sleep and arousal during homeostatic challenge.
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Affiliation(s)
- Jeremy Turner
- Department of Psychology, Illinois College Jacksonville, IL 62650, USA
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10
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Cohen-Woods S, Gaysina D, Craddock N, Farmer A, Gray J, Gunasinghe C, Hoda F, Jones L, Knight J, Korszun A, Owen MJ, Sterne A, Craig IW, McGuffin P. Depression Case Control (DeCC) Study fails to support involvement of the muscarinic acetylcholine receptor M2 (CHRM2) gene in recurrent major depressive disorder. Hum Mol Genet 2009; 18:1504-9. [PMID: 19181679 DOI: 10.1093/hmg/ddp051] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sarah Cohen-Woods
- MRC SGDP Centre, Institute of Psychiatry, King's College London, London, UK.
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11
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Kiesewetter DO, Jagoda EM, Shimoji K, Ma Y, Eckelman WC. Evaluation of [18F]fluoroxanomeline {5-{4-[(6-[18F]fluorohexyl)oxy]-1,2,5-thiadiazol-3-yl}-1-methyl-1,2,3,6-tetrahydropyridine} in muscarinic knockout mice. Nucl Med Biol 2007; 34:141-52. [PMID: 17307122 DOI: 10.1016/j.nucmedbio.2006.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 11/17/2006] [Accepted: 11/25/2006] [Indexed: 11/25/2022]
Abstract
INTRODUCTION We set out to develop a muscarinic M1-selective agonist (based on the structure of the functionally M1-selective xanomeline) that could be radiolabeled with fluorine-18 for use as an imaging agent for positron emission tomography. METHODS The radiochemical synthesis was achieved, employing the arts of organic and radiochemical syntheses. Binding selectivity studies employed biodistribution studies, using autoradiography and/or tissue dissection, in wild-type or muscarinic receptor knockout mice. RESULTS [(18)F]Fluoroxanomeline shows rather uniform uptake in all mouse brain regions and high specific binding, with a brain-to-blood ratio of 32 at 60 min postinjection. In addition, the specific binding is demonstrated by a 58% to 75% decrease in brain uptake upon coinjection with 5 nmol of unlabeled fluoroxanomeline or xanomeline. Brain uptake studies with [(3)H]xanomeline in muscarinic knockout mice show decreased uptake in M1 (17-34%) and M2 (2-20%) knockout mice compared with control. However, statistical significance was observed in only a few regions. Comparison of [(18)F]fluoroxanomeline in knockout mice showed no difference in M1 or M4 knockout mice but a general decrease in M2 (2-24%) knockout mice. The decrease of [(18)F]fluoroxanomeline uptake in M2 knockout mice reached statistical significance in brain stem, cerebellum, frontal cortex, hippocampus, inferior colliculus and superior colliculus. CONCLUSION Although xanomeline displays highly selective M1 agonist activity in functional assays, little selectivity for muscarinic subtype binding was observed for xanomeline or its fluorine-containing analogue, fluoroxanomeline. This emphasizes the lack of correlation between functional selectivity and binding selectivity.
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Affiliation(s)
- Dale O Kiesewetter
- Positron Emission Tomography Radiochemistry Group, NIBIB, NIH, Bethesda, MD 20892, USA.
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Rhodes ME, Billings TE, Czambel RK, Rubin RT. Pituitary-adrenal responses to cholinergic stimulation and acute mild stress are differentially elevated in male and female M(2) muscarinic receptor knockout mice. J Neuroendocrinol 2005; 17:817-26. [PMID: 16280029 DOI: 10.1111/j.1365-2826.2005.01376.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Adrenocorticotrophic hormone (ACTH) and corticosterone responses to cholinergic stimulation are greater in male rats and mice than in females. To explore the role of M(2) muscarinic receptors in this sex difference, we administered the nonselective muscarinic agonist, oxotremorine, the acetylcholinesterase inhibitor, physostigmine, and saline (a mild stressor) to male and female M(2) receptor knockout (KO) and wild-type (WT) mice of the same genetic background. Because M(2) receptors function primarily as presynaptic autoreceptors, we hypothesized that their absence in M(2) KO mice would increase the sensitivity of hormone responses to cholinergic stimulation in these groups. Both male and female M(2) KO mice were significantly more responsive to the stress of saline injection than were their WT counterparts. Oxotremorine and physostigmine increased ACTH and corticosterone in all four groups, but to a significantly greater degree in KO males compared to WT males, KO females, and WT females. The increase in ACTH also was significantly greater in WT males compared to WT females. By contrast, the increase in corticosterone was significantly more in females compared to males, independent of genotype. Following pretreatment with the nonselective muscarinic antagonist, scopolamine, ACTH and corticosterone responses to oxotremorine and to saline in the M(2) KO mice were comparable with those of their WT counterparts. These findings suggest that the M(2) muscarinic receptor subtype influences male and female pituitary-adrenal responses following stimulation by both mild stress and cholinergic drugs. The M(2) receptor appears to regulate ACTH responses to cholinergic stimulation in males but not in females; however, other muscarinic receptors may be involved because corticosterone responses were higher in females compared to males. Because ACTH and corticosterone responses were greater in male and female M(2) KO mice, the M(2) receptor appears to dampen the stress response.
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Affiliation(s)
- M E Rhodes
- Center for Neurosciences Research, Allegheny-Singer Research Institute, Allegheny General Hospital, Pittsburgh, PA 15650-2690, USA.
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Eglen RM. Muscarinic Receptor Subtype Pharmacology and Physiology. PROGRESS IN MEDICINAL CHEMISTRY 2005; 43:105-36. [PMID: 15850824 DOI: 10.1016/s0079-6468(05)43004-0] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Richard M Eglen
- DiscoveRx Corporation, Albrae Street, Fremont, CA 94538, USA
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Abstract
Muscarinic acetylcholine receptors (mAChRs; M1-M5) play key roles in regulating the activity of many important functions of the central and peripheral nervous system. Because of the lack of ligands endowed with a high degree of receptor subtype selectivity and the fact that most tissues or cell types express two or more mAChR subtypes, identification of the physiological and pathophysiological roles of the individual mAChR subtypes has proven a difficult task. To circumvent these difficulties, several laboratories recently employed gene-targeting techniques to generate mutant mouse strains deficient in each of the five mAChR subtypes. Phenotyping studies showed that each mutant mouse line displayed characteristic physiological, pharmacological, behavioral, biochemical, or neurochemical deficits. The novel insights gained from these studies should prove instrumental for the development of novel classes of muscarinic drugs.
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Affiliation(s)
- Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, DHHS, Bethesda, Maryland 20892, USA.
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Gralewicz S, Lutz P, Wiaderna D, Tomas T. Alteration in behavioral sensitivity to amphetamine after treatment with oxotremorine. Behav Brain Res 2003; 147:163-73. [PMID: 14659582 DOI: 10.1016/s0166-4328(03)00152-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Our earlier experiment revealed that rats pretreated once with an anticholinesterase develop hyposensitivity to amphetamine (AMPH). One of the likely causes of this effect might be a transient hyperexcitation of the central muscarinic receptors. It has appeared, however, that rats pretreated with oxotremorine (OX), a muscarinic agonist, show an augmented behavioral response to AMPH weeks later. The present experiments were performed in order to obtain more information on the relationship between the OX-induced sensitization to AMPH and the OX dose and dosing regime (single or repeated), and to find out whether the environment associated with the acute effects of OX could affect the response to AMPH. In experiment 1, adult male rats were given a single i.p. injection of OX in home cages at a moderate (0.5 mg/kg) or high (1.0 mg/kg) dose. In experiment 2, the rats received eight 1.0 mg/kg doses of OX in the course of three days. After each injection, some animals returned to their home cages, and some were placed in the test cages for 30 min. In both experiments, the response to AMPH was assessed on day 21 after the treatment. The obtained results indicate that: (i) a single i.p. exposure to OX results in an increase of the rat's behavioral sensitivity to AMPH but the moderate dose is more effective in inducing this effect; (ii) repeated exposure to OX at high doses, in a regime enabling development of tolerance to the acute OX effects, does not alter the rat sensitivity to AMPH, and (iii) expression of the AMPH response is suppressed in environment which has been associated with acute effects of OX.
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Affiliation(s)
- Sławomir Gralewicz
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, 8 Teresy St., 90-950 Lodz, Poland.
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16
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Wess J. Novel insights into muscarinic acetylcholine receptor function using gene targeting technology. Trends Pharmacol Sci 2003; 24:414-20. [PMID: 12915051 DOI: 10.1016/s0165-6147(03)00195-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Muscarinic acetylcholine receptors (mAChRs) modulate the activity of an extraordinarily large number of physiological functions. Individual members of the mAChR family (M(1)-M(5)) are expressed in a complex, overlapping fashion in most tissues and cell types. However, the identification of the precise physiological roles of individual mAChR subtypes remains a challenging task because, with the exception of a few snake toxins, mAChR ligands that can activate or inhibit specific mAChR subtypes with a high degree of selectivity are not yet available. Knowledge of the specific roles of mAChR subtypes is of considerable interest for the development of novel, clinically useful mAChR ligands. In this article, recent studies of mutant mouse strains developed, using gene targeting techniques, to be deficient in one of the three G(q)-coupled mAChR subtypes (M(1), M(3) and M(5)) are discussed. These investigations have led to many important new insights into the physiological roles of these receptor subtypes.
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Affiliation(s)
- Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Department of Health and Human Services, Bethesda, MD 20892, USA.
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17
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Abstract
Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.
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Affiliation(s)
- Mark J Millan
- Psychopharmacology Department, Centre de Rescherches de Croissy, Institut de Recherches (IDR) Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, Paris, France.
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Bymaster FP, McKinzie DL, Felder CC, Wess J. Use of M1-M5 muscarinic receptor knockout mice as novel tools to delineate the physiological roles of the muscarinic cholinergic system. Neurochem Res 2003; 28:437-42. [PMID: 12675128 DOI: 10.1023/a:1022844517200] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this review we report recent findings on the physiological role of the five known muscarinic acetylcholine receptors (mAChRs) as shown by gene targeting technology. Using knockout mice for each mAChRs subtype, the role of mAChRs subtypes in a number of physiological functions was confirmed and new activities were discovered. The M1 mAChRs modulate neurotransmitter signaling in cortex and hippocampus. The M3 mAChRs are involved in exocrine gland secretion, smooth muscle contractility, pupil dilation, food intake, and weight gain. The role of the M5 mAChRs involves modulation of central dopamine function and the tone of cerebral blood vessels. mAChRs of the M2 subtype mediate muscarinic agonist-induced bradycardia, tremor, hypothermia, and autoinhibition of release in several brain regions. M4 mAChRs modulate dopamine activity in motor tracts and act as inhibitory autoreceptors in striatum. Thus, as elucidated by gene targeting technology, mAChRs have widespread and manifold functions in the periphery and brain.
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Affiliation(s)
- Frank P Bymaster
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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