51
|
Pittel Z, Barak D, Segall Y. Function-specific blockage of M(1) and M(3) muscarinic acetylcholine receptors by VX and echothiophate. Brain Res 2006; 1085:102-10. [PMID: 16580648 DOI: 10.1016/j.brainres.2006.02.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 02/14/2006] [Accepted: 02/19/2006] [Indexed: 11/23/2022]
Abstract
Certain organophosphate (OP) cholinesterase inhibitors (ChEIs) are also known to bind to the muscarinic acetylcholine receptor (mAChR). The functional consequences of such binding were investigated here using the following OP compounds: VX, echothiophate, sarin, and soman. VX (charged at physiological pH) and echothiophate (formally charged) inhibited a specific signal transduction pathway in CHO cells expressing either the M(1) or M(3) mAChR. Hence, they blocked carbamylcholine (CCh)-induced cyclic adenosine monophosphate (cAMP) synthesis (muM) and had almost no effect on CCh-induced phosphoinositide (PI) hydrolysis. These substances were inactive on forskolin-induced cAMP inhibition signaling in CHO cells expressing M(2) mAChR. In binding studies, using [(3)H]-N-methyl scopolamine ([(3)H]NMS) as the competitor ligand, the ChEIs, VX and echothiophate exhibited binding to rat cortical mAChR with K(i) values in the muM range. The non-charged compounds, sarin and soman, were inert in modulating both cAMP metabolism and PI hydrolysis in CHO cells expressing M(1), M(2), and M(3) mAChRs, and no binding was observed in presence of [(3)H]NMS. These data suggest that VX and echothiophate act as function-specific blockers via a non-classical path of antagonistic activity, implying the involvement of allosteric/ectopic-binding site in M(1) and M(3) mAChRs. The functionally selective antagonistic behavior of echothiophate and VX makes them potential tools for dissecting the interactions of the mAChR with different G proteins.
Collapse
Affiliation(s)
- Zipora Pittel
- Department of Medicinal Chemistry, Israel Institute for Biological Research, P.O. Box 19, Ness-Ziona, Israel 74100.
| | | | | |
Collapse
|
52
|
Tobin G, Ryberg AT, Gentle S, Edwards AV. Distribution and function of muscarinic receptor subtypes in the ovine submandibular gland. J Appl Physiol (1985) 2006; 100:1215-23. [PMID: 16322368 DOI: 10.1152/japplphysiol.00779.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of muscarinic receptor antagonists on responses to electrical stimulation of the chorda-lingual nerve were determined in pentobarbitone-anesthetized sheep and correlated to the morphology of tissue specimens. Stimulation at 2 Hz continuously, or in bursts of 1 s at 20 Hz every 10 s, for 10 min induced similar submandibular fluid responses (19 ± 3 vs. 21 ± 3 μl·min−1·g gland−1), whereas vasodilatation was greater during stimulation in bursts (−52 ± 4 vs. −43 ± 5%; P < 0.01). Continuous stimulation at 8 Hz induced substantially greater responses (66 ± 9 μl·min−1·g gland−1 and −77 ± 3%). While atropine (0.5 mg/kg iv) abolished the secretory response at 2 and 20 Hz (1:10 s), a small response persisted at 8 Hz (<5%). The “M1-selective” antagonist pirenzepine (40 μg/kg iv) reduced the fluid response at all frequencies tested ( P < 0.05–0.01), most conspicuously at 2 Hz (reduced by 69%). Methoctramine (“M2/M4-selective”; 100 μg/kg iv; n = 5) had no effect on fluid or the vascular responses but increased the protein output at 2 (+90%, P < 0.05) and 8 Hz (+45%, P < 0.05). The immunoblotting showed distinct bands for muscarinic M1, M3, M4, and M5 receptors, and immunohistochemistry showed muscarinic M1 and M3 receptors to occur in the parenchyma. Thus muscarinic M1 receptors contribute to the secretory response to parasympathetic stimulation but have little effect on the vasodilatation in the ovine submandibular gland. Increased transmitter release caused by blockade of neuronal inhibitory receptors of the M4 subtype would explain the increase in protein output.
Collapse
Affiliation(s)
- G Tobin
- Department of Pharmacology, Sahlgrenska Academy at Göteborg University, Medicinaregatan 15D, Göteborg 413 90, Sweden.
| | | | | | | |
Collapse
|
53
|
Hamamura M, Maróstica E, de Avellar MCW, Porto CS. Muscarinic acetylcholine receptor subtypes in the rat seminal vesicle. Mol Cell Endocrinol 2006; 247:192-8. [PMID: 16481100 DOI: 10.1016/j.mce.2006.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 12/19/2005] [Accepted: 01/05/2006] [Indexed: 11/21/2022]
Abstract
The aim of the present study was to identify the muscarinic acetylcholine receptor (mAChR) mRNA subtypes in the rat seminal vesicle. Furthermore, the mAChR subtypes involved in the contraction of the seminal vesicle were also explored. Reverse transcriptase-polymerase chain reaction (PCR) was performed and five PCR products corresponding to M1-M5 mAChR mRNA subtypes were detected in this tissue. Functional pharmacological studies indicated that the rank order of mAChR antagonists in blocking the contractile effects of carbachol was p-fluoro-hexahydro-sila-difenidol (pF-HHSiD) >> tropicamide > methoctramine = pirenzepine. This antagonist profile indicates that M3 mAChR subtype is predominantly involved in the seminal vesicle contraction. Furthermore, immunohistochemical studies confirmed the presence of the M3 mAChR subtype in the smooth muscle layers. M2 mAChR subtype was also immunolocalized in smooth muscle cells and may be involved in the contraction of this tissue. The presence of M2 and M3 mAChR subtypes in the epithelial cells suggests that these receptors could be involved in the protein secretion. Taken together, the cholinergic neurotransmitter may be a factor controlling contractility and protein secretion in this tissue.
Collapse
Affiliation(s)
- Margarete Hamamura
- Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo, Escola Paulista de Medicina, Rua Três de maio 100, INFAR, Vila Clementino, São Paulo, SP 04044-020, Brazil
| | | | | | | |
Collapse
|
54
|
Tayebati SK, Di Tullio MA, Amenta F. Muscarinic cholinergic receptor subtypes in cerebral cortex of Fisher 344 rats: a light microscope autoradiography study of age-related changes. Mech Ageing Dev 2005; 127:115-22. [PMID: 16293294 DOI: 10.1016/j.mad.2005.09.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 04/05/2005] [Accepted: 09/15/2005] [Indexed: 11/16/2022]
Abstract
The density and localization of muscarinic cholinergic M1-M5 receptor subtypes was investigated in frontal and occipital cortex of male Fisher 344 rats aged 6 months (young-adult), 15 months (mature) and 22 months (senescent) by combined kinetic and equilibrium binding and light microscope autoradiography. In 6-month-old rats, the rank order density of muscarinic cholinergic receptor subtypes was M1>M2>M4>M3>M5 both in frontal and occipital cortex. A not homogeneous distribution of different receptor subtypes throughout cerebrocortical layers of frontal or occipital cortex was found. In frontal cortex silver grains corresponding to the M1 and M2 receptor subtypes were decreased in 15- and 22-month-old groups. The M3 receptor density was remarkably and moderately decreased in layers II/III and V, respectively, of rats aged 15 and 22 months. A reduced M4 receptor density was observed in layer I and to a lesser extent in layer V of mature and senescent rats, whereas no age-related changes of M5 receptor were found. In occipital cortex a diminution of M1 receptor was observed in layers II/III and V of mature and senescent rats. The M2 receptor expression decreased in layer I of 15- and 22-month-old senescent rats, whereas M3-M5 receptors were unchanged with exception of a slight decrease of the M4 receptor in layer IV and of M5 receptor in layers II/III. These findings indicate a different sensitivity to aging of muscarinic receptor subtypes located in various cerebrocortical layers. This may account for the difficulty in obtaining relevant results in manipulating cholinoceptors to counter age-related impairment of cholinergic system.
Collapse
Affiliation(s)
- Seyed Khosrow Tayebati
- Sezione di Anatomia Umana, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università di Camerino, Via Scalzino, 3, 62032 Camerino, Italy.
| | | | | |
Collapse
|
55
|
Phatarpekar PV, Durdan SF, Copeland CM, Crittenden EL, Neece JD, García DM. Molecular and pharmacological characterization of muscarinic receptors in retinal pigment epithelium: role in light-adaptive pigment movements. J Neurochem 2005; 95:1504-20. [PMID: 16269010 DOI: 10.1111/j.1471-4159.2005.03512.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Muscarinic receptors are the predominant cholinergic receptors in the central and peripheral nervous systems. Recently, activation of muscarinic receptors was found to elicit pigment granule dispersion in retinal pigment epithelium isolated from bluegill fish. Pigment granule movement in retinal pigment epithelium is a light-adaptive mechanism in fish. In the present study, we used pharmacological and molecular approaches to identify the muscarinic receptor subtype and the intracellular signaling pathway involved in the pigment granule dispersion in retinal pigment epithelium. Of the muscarinic receptor subtype-specific antagonists used, only antagonists specific for M1 and M3 muscarinic receptors were found to block carbamyl choline (carbachol)-induced pigment granule dispersion. A phospholipase C inhibitor also blocked carbachol-induced pigment granule dispersion, and a similar result was obtained when retinal pigment epithelium was incubated with an inositol trisphosphate receptor inhibitor. We isolated M2 and M5 receptor genes from bluegill and studied their expression. Only M5 was found to be expressed in retinal pigment epithelium. Taken together, pharmacological and molecular evidence suggest that activation of an odd subtype of muscarinic receptor, possibly M5, on fish retinal pigment epithelium induces pigment granule dispersion.
Collapse
MESH Headings
- Acetylcholine/pharmacology
- Adaptation, Ocular
- Alkaloids
- Animals
- Behavior, Animal
- Carbachol/pharmacology
- Cholinergic Agonists/pharmacology
- Cholinesterase Inhibitors/pharmacology
- Cloning, Molecular/methods
- Colforsin/pharmacology
- Dose-Response Relationship, Drug
- Drug Interactions
- Enzyme Inhibitors/pharmacology
- Perciformes
- Phylogeny
- Pigment Epithelium of Eye/drug effects
- Pigment Epithelium of Eye/metabolism
- Pigment Epithelium of Eye/radiation effects
- Pigments, Biological/physiology
- RNA, Messenger/biosynthesis
- Receptors, Muscarinic/classification
- Receptors, Muscarinic/genetics
- Receptors, Muscarinic/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Sequence Analysis, DNA/methods
- Sequence Analysis, Protein/methods
- Sesquiterpenes/pharmacology
Collapse
Affiliation(s)
- Prasad V Phatarpekar
- Department of Biology, Texas State University-San Marcos, San Marcos, Texas 78666, USA
| | | | | | | | | | | |
Collapse
|
56
|
Siu ER, Yasuhara F, Maróstica E, Avellar MCW, Porto CS. Expression and localization of muscarinic acetylcholine receptor subtypes in rat efferent ductules and epididymis. Cell Tissue Res 2005; 323:157-66. [PMID: 16160857 DOI: 10.1007/s00441-005-0054-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Accepted: 07/18/2005] [Indexed: 11/27/2022]
Abstract
The expression of muscarinic acetylcholine receptor (mAChR) subtypes (M(1)-M(5)) was studied in the rat efferent ductules and epididymis at the mRNA and protein levels. The relative abundance of each mAChR transcript subtype differed depending on the tissue and the epididymal region analyzed. The M(1) mAChR mRNA level was more abundant in the efferent ductules than in the caput and cauda of the epididymis. The M(2) mAChR mRNA level was similar between the efferent ductules and caput of the epididymis and higher in the cauda region. The M(3) mAChR mRNA level was low in the efferent ductules and caput of the epididymis, but high levels were detected in the cauda region. mRNAs for M(4) and M(5) mAChRs were not detected in these tissues. Our studies indicated a variable degree of immunostaining for each mAChR subtype in a cell-type and tissue-specific pattern. M(1) mAChR was detected over the efferent ductule epithelium. M(2) and M(3) mAChRs were observed in the apical region of the ciliated cells. Apical and narrow cells of the initial segment showed distinct staining by M(1) antibody, whereas a supranuclear reaction was noted in the principal cells of the caput of the epididymis. In addition, staining for M(1) and M(2) mAChRs was visible in the apical membrane of some epithelial cells of the cauda region. M(3) mAChR was detected in the peritubular smooth muscle of the efferent ductules and epididymis. Functional studies suggested the involvement of this subtype in epididymal tubule contraction. Thus, the cell-specific expression of the various mAChR subtypes in the efferent ductules and epididymis suggests that these receptors play a role in the modulation of luminal fluid composition and smooth muscle contraction.
Collapse
Affiliation(s)
- Erica R Siu
- Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo-Escola Paulista de Medicina, Rua Três de maio 100, INFAR, Vila Clementino, 04044-020 São Paulo, Brazil
| | | | | | | | | |
Collapse
|
57
|
Mansfield KJ, Liu L, Mitchelson FJ, Moore KH, Millard RJ, Burcher E. Muscarinic receptor subtypes in human bladder detrusor and mucosa, studied by radioligand binding and quantitative competitive RT-PCR: changes in ageing. Br J Pharmacol 2005; 144:1089-99. [PMID: 15723094 PMCID: PMC1576093 DOI: 10.1038/sj.bjp.0706147] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. We investigated muscarinic receptors in the detrusor and mucosa of the human bladder body. Radioligand-binding studies with [(3)H]QNB were conducted using specimens collected from patients (36-77 years) with normal bladder function, undergoing surgery. For RT-PCR, biopsies of normal bladder were obtained from patients (30-88 years) undergoing check cystoscopy. 2. Binding of [(3)H]QNB in detrusor (n=20) was of high affinity (K(D) 77.1 (55.2-99.0) pM) and capacity (B(max) 181+/-7 fmol mg protein(-1)). Similar values were obtained in mucosa (n=6) (K(D) 100.5 (41.2-159.9) pM; B(max) 145+/-9 fmol mg protein(-1)). 3. Competition-binding experiments in detrusor membranes with muscarinic receptor antagonists including trospium, darifenacin, 4-DAMP, methoctramine, AQ-RA 741, AF-DX 116 and pirenzepine indicated a receptor population of 71% M(2), 22% M(3) and 7% M(1). In the mucosa, 75% of sites were M(2) receptors, with 25% M(3)/M(5). 4. Using RT-PCR, expression of M(1), M(2), M(3) and M(5) mRNA was demonstrated in both detrusor and mucosa. 5. The presence of a high density of mainly M(2) muscarinic receptors in the mucosa appears to be a novel finding and raises the question of their physiological significance and the source of their endogenous ligand. 6. There was a negative correlation of receptor number (B(max)) with age in detrusor muscle from male patients (P=0.02). Quantitative competitive RT-PCR demonstrated a selective age-related decrease in mRNA for muscarinic M(3) but not M(2) receptors, in both male (P<0.0001) and female (P=0.019) detrusor. These findings correspond with reports of decreased detrusor contractility with ageing.
Collapse
Affiliation(s)
- Kylie J Mansfield
- Department of Physiology and Pharmacology, University of New South Wales, Sydney, NSW 2052, Australia
| | - Lu Liu
- Department of Physiology and Pharmacology, University of New South Wales, Sydney, NSW 2052, Australia
| | - Frederick J Mitchelson
- Department of Pharmacology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Kate H Moore
- Detrusor Muscle Laboratory, St George Hospital, University of New South Wales, NSW 2052, Australia
| | - Richard J Millard
- Department of Urology, Prince of Wales Hospital, University of New South Wales, NSW 2052, Australia
| | - Elizabeth Burcher
- Department of Physiology and Pharmacology, University of New South Wales, Sydney, NSW 2052, Australia
- Author for correspondence:
| |
Collapse
|
58
|
Miller AD, Blaha CD. Midbrain muscarinic receptor mechanisms underlying regulation of mesoaccumbens and nigrostriatal dopaminergic transmission in the rat. Eur J Neurosci 2005; 21:1837-46. [PMID: 15869479 DOI: 10.1111/j.1460-9568.2005.04017.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Laterodorsal (LDT) and pedunculopontine (PPT) tegmental nuclei in the mesopontine project cholinergic inputs to the midbrain ventral tegmental area (VTA) and substantia nigra pars compacta (SNc), respectively, to directly and indirectly influence the activity of dopamine neuronal cells via actions on muscarinic and nicotinic receptors. The present study investigated the role of midbrain muscarinic receptors in the functional modulation of VTA and SNc dopamine cell activity as reflected by alterations in, respectively, nucleus accumbens (NAc) and striataldopamine efflux. In vivo chronoamperometry was used to measure changes in basal dopamine efflux via stearate-graphite paste electrodes implanted unilaterally in the NAc or striatum of urethane-anaesthetized rats, following blockade or activation of, respectively, VTA or SNc muscarinic receptors. Intra-VTA or -SNc infusion of the muscarinic antagonist scopolamine (200 microg/microL) reduced, respectively, NAc and striatal dopamine efflux while infusion of the muscarinic and nicotinic agonist carbachol (0.5 microg/microL) or the prototypical muscarinic agonist muscarine (0.5 microg/microL) increased NAc and striatal dopamine efflux. Transient decreases in dopamine efflux preceded these increases selectively in the striatum, suggesting a reduction in excitatory or increase in inhibitory drive to the SNc by preferential activation of M3 muscarinic receptors on GABA interneurons and glutamatergic inputs. This was confirmed by showing that selective blockade of M3 receptors with p-F-HHSiD (0.5 microg/microL) increased striatal, but not NAc, dopamine efflux. Together, these findings suggest that midbrain muscarinic receptors, probably M5 subtypes on VTA and SNc dopamine neurons, contribute to the tonic excitatory regulation of forebrain basal dopamine transmission whereas presynaptic M3 receptors serve to counter excessive excitation of nigral dopamine cell activity.
Collapse
Affiliation(s)
- Anthony D Miller
- Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia
| | | |
Collapse
|
59
|
Aihara T, Nakamura Y, Taketo MM, Matsui M, Okabe S. Cholinergically stimulated gastric acid secretion is mediated by M(3) and M(5) but not M(1) muscarinic acetylcholine receptors in mice. Am J Physiol Gastrointest Liver Physiol 2005; 288:G1199-207. [PMID: 15691866 DOI: 10.1152/ajpgi.00514.2004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Muscarinic acetylcholine receptors play an important role in the regulation of gastric acid secretion stimulated by acetylcholine; nonetheless, the precise role of each receptor subtype (M(1)-M(5)) remains unclear. This study examined the involvement of M(1), M(3), and M(5) receptors in cholinergic regulation of acid secretion using muscarinic receptor knockout (KO) mice. Gastric acid secretion was measured in both mice subjected to acute gastric fistula production under urethane anesthesia and conscious mice that had previously undergone pylorus ligation. M(3) KO mice exhibited impaired gastric acid secretion in response to carbachol. Unexpectedly, M(1) KO mice exhibited normal intragastric pH, serum gastrin and mucosal histamine levels, and gastric acid secretion stimulated by carbachol, histamine, and gastrin. Pirenzepine, known as an M(1)-receptor antagonist, inhibited carbachol-stimulated gastric acid secretion in a dose-dependent manner in M(1) KO mice as well as in wild-type (WT) mice, suggesting that the inhibitory effect of pirenzepine on gastric acid secretion is independent of M(1)-receptor antagonism. Notably, M(5) KO mice exhibited both significantly lower carbachol-stimulated gastric acid secretion and histamine-secretory responses to carbachol compared with WT mice. RT-PCR analysis revealed M(5)-mRNA expression in the stomach, but not in either the fundic or antral mucosa. Consequently, cholinergic stimulation of gastric acid secretion is clearly mediated by M(3) (on parietal cells) and M(5) receptors (conceivably in the submucosal plexus), but not M(1) receptors.
Collapse
MESH Headings
- Animals
- Carbachol/pharmacology
- Cholinergic Agonists/pharmacology
- Female
- Gastric Acid/metabolism
- Male
- Mice
- Mice, Knockout
- Muscarinic Antagonists/pharmacology
- Pirenzepine/pharmacology
- RNA, Messenger/biosynthesis
- Receptor, Muscarinic M1/biosynthesis
- Receptor, Muscarinic M1/genetics
- Receptor, Muscarinic M1/physiology
- Receptor, Muscarinic M3/biosynthesis
- Receptor, Muscarinic M3/genetics
- Receptor, Muscarinic M3/physiology
- Receptor, Muscarinic M5/biosynthesis
- Receptor, Muscarinic M5/genetics
- Receptor, Muscarinic M5/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Stomach/physiology
Collapse
Affiliation(s)
- Takeshi Aihara
- Dept. of Applied Pharmacology, Kyoto Pharmaceutical Univ., Misasagi, Yamashina, Kyoto 607-8414 Japan
| | | | | | | | | |
Collapse
|
60
|
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
| |
Collapse
|
61
|
Miller AD, Forster GL, Yeomans JS, Blaha CD. Midbrain muscarinic receptors modulate morphine-induced accumbal and striatal dopamine efflux in the rat. Neuroscience 2005; 136:531-8. [PMID: 16216430 DOI: 10.1016/j.neuroscience.2005.08.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 07/20/2005] [Accepted: 08/15/2005] [Indexed: 10/25/2022]
Abstract
Midbrain dopamine neurons are critical in mediating the rewarding effects of opiates in dependent rats, as well as modulating some manifestations of opiate withdrawal. Morphine is known to excite dopamine neurons and thereby facilitate forebrain dopamine transmission through inhibition of GABA neurons. Cholinergic neurons in the mesopontine laterodorsal and pedunculopontine tegmental nuclei provide the principal source of excitatory cholinergic input to ventral tegmental area and substantia nigra pars compacta dopamine-containing neurons, via actions on midbrain muscarinic and nicotinic acetylcholine receptors. The present study hypothesized that a reduction in tonic cholinergic input via blockade of midbrain muscarinic receptors would reduce the pharmacological effects of morphine on forebrain dopamine release. Using in vivo chronoamperometry, alterations in morphine-evoked dopamine efflux were monitored at stearate-graphite paste electrodes implanted unilaterally in the nucleus accumbens and striatum of urethane (1.5 g/kg) anesthetized rats, following the pharmacological inhibition of ventral tegmental area/substantia nigra pars compacta muscarinic receptors. The facilitatory effects of morphine (2.0 mg/kg, i.v.) on accumbens and striatal dopamine efflux were markedly reduced by prior infusion of the non-selective muscarinic receptor antagonist scopolamine (200 microg/microl) into the ventral tegmental area or substantia nigra pars compacta, respectively. These findings demonstrate that decreased activation of midbrain muscarinic receptors attenuates the excitatory effects of morphine on mesoaccumbens and nigrostriatal dopaminergic transmission.
Collapse
Affiliation(s)
- A D Miller
- Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia
| | | | | | | |
Collapse
|
62
|
Larsen R, Hansen MB, Bindslev N, Mertz-Nielsen A. Functional characterization of muscarinic receptor subtypes in human duodenal secretion. ACTA ACUST UNITED AC 2004; 182:63-8. [PMID: 15329058 DOI: 10.1111/j.1365-201x.2004.01301.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM Acetylcholine (ACh) stimulates ion secretion in the small intestine and colon. The purpose of the present study was to characterize the ACh-induced electrogenic ion transport in human duodenum and determine the muscarinic receptor subtypes functionally involved. METHODS Biopsies from the second part of duodenum were obtained from 28 patients during endoscopy. Biopsies were mounted in modified Ussing chambers with air-suction for measurements of short-circuit current by a previously validated technique. Short-circuit current was measured after application of chloride/bicarbonate transport inhibitors bumetanide, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS), diphenylamine-2-carboxylate (DPC), and acetazolamide. 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) and two mamba toxins MT3 and MT7 were used to characterize the mAChR receptor subtypes involved. The effects of transport inhibitors and receptor antagonists were measured by comparing two consecutive responses of ACh on short-circuit current in the same biopsy specimen. RESULTS Bumetanide and 4-DAMP significantly inhibited ACh-induced short-circuit current, whereas SITS, DPC, acetazolamide, mamba toxin MT3, and mamba toxin MT7 all failed to show any significant effect. CONCLUSION In conclusion, our results indicate that muscarinic receptor subtype M3 acts as the main mediator of bumetanide-sensitive ACh-induced secretion in human duodenum.
Collapse
Affiliation(s)
- R Larsen
- Department of Medicine M, Division of Gastroenterology, University Hospital of Glostrup, Glostrup, Denmark
| | | | | | | |
Collapse
|
63
|
Wang Z, Shi H, Wang H. Functional M3 muscarinic acetylcholine receptors in mammalian hearts. Br J Pharmacol 2004; 142:395-408. [PMID: 15148264 PMCID: PMC1574958 DOI: 10.1038/sj.bjp.0705787] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2004] [Revised: 03/08/2004] [Accepted: 03/10/2004] [Indexed: 11/08/2022] Open
Abstract
In contrast to most peripheral tissues where multiple subtypes of muscarinic acetylcholine receptor (mAChR) coexist, with each of them playing its part in the orchestra of parasympathetic innervation, the myocardium has been traditionally considered to possess a single mAChR subtype. Although there is much evidence to support the notion that one receptor subtype (M2) orchestrates myocardial muscarinic transduction, there is emerging evidence that M1 and M3 receptors are also expressed and are of potential physiological, pathophysiological and pharmacological relevance. Clarifying this issue has a profound impact on our thinking about the cholinergic control of the heart function and disease and approaches to new drug development for the treatment of heart disease associated with parasympathetic dysfunction. This review article presents evidence for the presence of the M3 receptor subtype in the heart, and analyzes the controversial data from published pharmacological, functional and molecular studies. The potential roles of the M3 receptors, in parasympathetic control of heart function under normal physiological conditions and in heart failure, myocardial ischemia and arrhythmias, are discussed. On the basis of these considerations, we have made some proposals concerning the future of myocardial M3 receptor research.
Collapse
Affiliation(s)
- Zhiguo Wang
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, Quebec, Canada.
| | | | | |
Collapse
|
64
|
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.
Collapse
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.
| |
Collapse
|
65
|
Tayebati SK, Di Tullio MA, Amenta F. Age-related changes of muscarinic cholinergic receptor subtypes in the striatum of Fisher 344 rats. Exp Gerontol 2004; 39:217-23. [PMID: 15036415 DOI: 10.1016/j.exger.2003.10.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Revised: 09/18/2003] [Accepted: 10/15/2003] [Indexed: 10/26/2022]
Abstract
Striatum expresses a cholinergic system involved in the regulation of its activity and changes in striatal cholinergic receptors may be related to cognitive impairment. This study has investigated muscarinic cholinergic M1-M5 receptor subtype expression in striatum of Fischer 344 rats aged 6 (young), 15 (adult) and 22 months (senescent) to assess the contribution of different muscarinic cholinergic receptor subtypes in age-related changes of striatal cholinergic neurotransmission. Western blot analysis revealed the expression of the M1-M5 muscarinic receptor subtytpes in the striatum of rats of the three age groups investigated. Both radioligand binding assay and light microscope autoradiography showed in young rats a M4>M1>M2>M3>M5 rank order of receptor density. With the exception of M1 receptor, the density of which is similar in the dorsal (motor) and ventral (limbic) striatum, other receptor subtypes were more abundant in ventral than in dorsal striatum. M1 receptor expression was unchanged between young and adult rats and decreased in senescent animals both in dorsal and ventral striatum. In dorsal striatum M2 and M5 receptor expression did not show age-related changes, whereas in ventral striatum it was slightly decreased in adult rats compared to young or senescent cohorts. M3 receptor expression did not show age-related modifications, whereas a progressive age-related decrease of M4 receptor was found, both in dorsal and ventral striatum. These data indicate a heterogeneous response to age of different muscarinic receptor subtypes. Striatal cholinergic markers are thought to correlate with cognitive impairment in aged rats. In view of this, the identification of age-related changes of striatal muscarinic receptor subtypes may contribute to develop cholinergic strategies to counter cholinergic neurotransmission changes occurring with aging.
Collapse
Affiliation(s)
- Seyed Khosrow Tayebati
- Sezione di Anatomia Umana, Dipartimento di Scienze Farmacologiche e Medicina Sperimentale, Università di Camerino, 62032 Camerino, Italy.
| | | | | |
Collapse
|
66
|
Yamada M, Basile AS, Fedorova I, Zhang W, Duttaroy A, Cui Y, Lamping KG, Faraci FM, Deng CX, Wess J. Novel insights into M5 muscarinic acetylcholine receptor function by the use of gene targeting technology. Life Sci 2004; 74:345-53. [PMID: 14607263 DOI: 10.1016/j.lfs.2003.09.022] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Until recently, little was known about the possible physiological functions of the M(5) muscarinic acetylcholine receptor subtype, the last member of the muscarinic receptor family (M(1)-M(5)) to be cloned. To learn more about the potential physiological roles of this receptor subtype, we generated and analyzed M(5) receptor-deficient mice (M5 -/- mice). Strikingly, acetylcholine, a potent dilator of most vascular beds, virtually lost the ability to dilate cerebral arteries and arterioles in M5 -/- mice, suggesting that endothelial M(5) receptors mediate this activity in wild-type mice. This effect was specific for cerebral blood vessels, since acetylcholine-mediated dilation of extra-cerebral arteries remained fully intact in M5 -/- mice. In addition, in vitro neurotransmitter release experiments indicated that M(5) receptors located on dopaminergic nerve terminals play a role in facilitating muscarinic agonist-induced dopamine release in the striatum, consistent with the observation that the dopaminergic neurons innervating the striatum almost exclusively express the M(5) receptor subtype. We also found that the rewarding effects of morphine, the prototypical opiate analgesic, were substantially reduced in M5 -/- mice, as measured in the conditioned place preference paradigm. Furthermore, both the somatic and affective components of naloxone-induced morphine withdrawal symptoms were significantly attenuated in M5 -/- mice. It is likely that these behavioral deficits are caused by the lack of mesolimbic M(5) receptors, activation of which is known to stimulate dopamine release in the nucleus accumbens. These results convincingly demonstrate that the M(5) muscarinic receptor is involved in modulating several important pharmacological and behavioral functions. These findings may lead to novel therapeutic strategies for the treatment of drug addiction and certain cerebrovascular disorders.
Collapse
Affiliation(s)
- Masahisa Yamada
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bldg. 8A, Room B1A-05, 8 Center Drive MSC 0810, Bethesda, MD 20892-0810, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
67
|
Tayebati SK, Di Tullio MA, Tomassoni D, Amenta F. Localization of the m5 muscarinic cholinergic receptor in rat circle of Willis and pial arteries. Neuroscience 2003; 122:205-11. [PMID: 14596861 DOI: 10.1016/s0306-4522(03)00513-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The expression and microanatomical localization of the muscarinic cholinergic m5 receptor subtype was investigated in rat circle of Willis and pial arteries by in situ hybridization, immunoblotting and immunohistochemistry. In situ hybridization histochemistry revealed a strong signal in the endothelium of circle of Willis and pial arteries and a moderate signal in the tunica media of the same arteries, within smooth muscle. Exposure of membranes of arteries to anti-m5 receptor protein antibodies caused the development of a band of approximately 81 kDa. Immunohistochemistry revealed the accumulation of m5 receptor protein immunoreactivity primarily within endothelium of circle of Willis and cerebral arteries and to a lesser extent in the tunica media, within smooth muscle. Medium (external diameter 200-100 microm) and small-sized (external diameter smaller than 100 microm) pial arteries displayed a significantly higher immune staining than large-sized pial arteries or circle of Willis arteries. The above data that are consistent with recent functional studies reporting cholinergic dilation of cerebral blood vessels mediated via a m5 receptor, have shown that both endothelial and muscular components of cerebral arteries synthesize and express a muscarinic m5 receptor. In view of the peculiar localization in cerebral vessels, handling of the muscarinic m5 receptor may be considered as an approach in the treatment of cerebrovascular disease.
Collapse
Affiliation(s)
- S K Tayebati
- Sezione di Anatomia Umana, Dipartimento di Scienze Farmacologiche e Medicina Sperimentale, Università di Camerino, Via Scalzino 3, 62032 Camerino, Italy.
| | | | | | | |
Collapse
|
68
|
Abstract
An understanding of muscarinic receptors is tantamount to an understanding of overactive bladder. The M(3) muscarinic receptor subtype is responsible for detrusor smooth muscle contraction and it exerts an exocrine function in the salivary glands. Alterations in the receptor's response to acetylcholine as a result of injury may lead to hypersensitivity and overactivity. The M(2) receptor subtype, which is mainly responsible for cardiac function, is the muscarinic receptor of highest proportion in the detrusor. M(2) also may play a role in detrusor contraction in injury and pathologic states. Muscarinic antagonists are the mainstay of pharmacotherapy for overactive bladder, but those that are available are not tissue specific. Growing knowledge of the nuances of receptor-ligand behavior and interaction between muscarinic receptors subtypes may provide novel targets for future drug development, improve efficacy, and reduce bothersome side effects.
Collapse
Affiliation(s)
- Harriette M Scarpero
- Department of Urologic Surgery, Vanderbilt University Medical Center, A-1302 Medical Center North, Nashville, TN 37232-2765, USA.
| | | |
Collapse
|
69
|
De Amici M, Conti P, Fasoli E, Barocelli E, Ballabeni V, Bertoni S, Impicciatore M, Roth BL, Ernsberger P, De Micheli C. Synthesis and in vitro pharmacology of novel heterocyclic muscarinic ligands. ACTA ACUST UNITED AC 2003; 58:739-48. [PMID: 13679167 DOI: 10.1016/s0014-827x(03)00113-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A set of novel heterocyclic ligands (7a-9a, 7b-9b, and 9c) structurally related to oxotremorine 2 was designed, synthesized, and tested at muscarinic receptor subtypes. In the binding experiments at cloned hm1-5, the presence of the 2-methylimidazole/2-methyl-3-alkylimidazolium moiety in place of the pyrrolidine ring revealed, in derivatives 8a, 8b, and 9c, a moderate selectivity for some receptor subtypes. The functional in vitro assays yielded results that correlated closely to binding data. In general, on passing from agonists bearing the pyrrolidine moiety to their analogues carrying the 2-methylimidazole function, the overall pharmacological efficacy profile is shifted from agonism toward partial agonism. The insertion of the 2-methyl-3-alkylimidazolium moiety advances the effect such that the compounds are pure antagonists. Quite similarly, chiral 3-oxo-Delta(2)-isoxazoline (+/-)-10 behaved as a weak antagonist unable to discriminate the different muscarinic receptor subtypes.
Collapse
Affiliation(s)
- Marco De Amici
- Istituto di Chimica Farmaceutica e Tossicologica, Università di Milano, Viale Abruzzi 42, Milan 20131, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
70
|
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.
Collapse
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.
| |
Collapse
|
71
|
Guo J, Schofield GG. Activation of muscarinic m5 receptors inhibits recombinant KCNQ2/KCNQ3 K+ channels expressed in HEK293T cells. Eur J Pharmacol 2003; 462:25-32. [PMID: 12591092 DOI: 10.1016/s0014-2999(03)01323-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A variety of G-protein-coupled receptors regulate membrane excitability via M-type K(+) current (M-current) modulation. Muscarinic m1 and m3 acetylcholine receptors have both been implicated in the modulation of M-current. The muscarinic m5 receptor, like muscarinic m1 and m3 receptors, couples to phospholipase C via a pertussis toxin-insensitive G protein. Since a number of other receptors which activate phospholipase C also modulate M-current, we investigated if muscarinic m5 receptors could modulate recombinant M-type (KCNQ2/KCNQ3) K(+) channels after heterologous expression in human embryonic kidney (HEK) 293T cells. Application of Oxo-tremorine M to HEK293T cells expressing muscarinic m1, m3, or m5 receptors produced a similar robust inhibition of M-current, whereas muscarinic m2 and m4 receptor stimulation was without effect. Muscarinic m1, m3, or m5 receptor stimulation decreased the deactivation time constants of M-current at -50 mV. The inhibition of M-current by stimulation of muscarinic m1, m3, or m5 receptors was insensitive to overnight treatment with pertussis toxin or cholera toxin, which interfere with G(i/o) and G(s) G-protein signaling. These data suggest that muscarinic m1, m3, and m5 receptors inhibit M-channels via the activation of a common G protein.
Collapse
Affiliation(s)
- Juan Guo
- Department of Physiology SL-39, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | | |
Collapse
|
72
|
Tobin G. Presynaptic muscarinic receptor mechanisms and submandibular responses to stimulation of the parasympathetic innervation in bursts in rats. Auton Neurosci 2003; 99:111-8. [PMID: 12241085 DOI: 10.1016/s1566-0702(02)00094-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Submandibular secretory responses to electrical stimulation of the parasympathetic innervation at variable frequencies were measured in anaesthetized rats. Selective blockade by pirenzepine and by methoctramine occurred at doses (50 and of 300 nmol kg (-1), i.v., respectively) that did not inhibit the responses to exogenous acetylcholine. In the presence of methoctramine, the nerve-evoked fluid responses were increased by 100% at 1 Hz independently of the total number of impulses (10-300), suggesting that M2 receptor activation inhibits transmitter release. The magnitude of the increase was inversely related to frequency of stimulation. The protein concentrations in the fluid responses were not significantly affected by methoctramine. Pirenzepine had an inhibitory effect on the fluid secretory responses, which was dependent of frequency, as well as of number of impulses, suggesting that M1 receptor activation facilitates transmitter release. At 10 Hz given intermittently (for 1 s at 10-s intervals), pirenzepine reduced the fluid response by 25%. The protein release was substantially and significantly reduced by pirenzepine independent of frequency but only during long periods of stimulation (300 impulses). It is concluded that muscarinic M1 receptor activation normally has a facilitatory effect on transmitter release, and that the facilitation occurs during short, intense stimulation. Muscarinic M1 receptors are, however, likely to regulate protein secretion by other mechanisms. Muscarinic M2 receptors, on the other hand, normally inhibit cholinergic transmission at low frequencies. Similar to findings in the alimentary tract of several species, stimulation in bursts at high frequencies is a more efficient stimulation pattern than continuous low frequency stimulation. This pattern of stimulation thus takes advantage of transient facilitation and avoids the inhibition at less intense neuronal activity.
Collapse
Affiliation(s)
- Gunnar Tobin
- Department of Pharmacology, Göteborg University, Sweden.
| |
Collapse
|
73
|
Sagara Y, Kimura T, Fujikawa T, Noguchi K, Ohtake N. Identification of novel muscarinic M(3) selective antagonists with a conformationally restricted Hyp-Pro spacer. Bioorg Med Chem Lett 2003; 13:57-60. [PMID: 12467616 DOI: 10.1016/s0960-894x(02)00843-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The identification of potent and selective muscarinic M(3) antagonists that are based on the recently discovered triphenylpropioamide derivative, 1, and have a unique amino acid spacer group is described. The introduction of a hydroxyproline-proline group to the spacer site and the use of a propyl or cyclopropylmethyl group as the piperidine N-substituent led to the discovery of the novel M(3) selective antagonists [8c, 8g; K(i)<2 nM (M(3)), M(1)/M(3)>700-fold, M(2)/M(3)>180-fold], which have a more rigid structure than 1.
Collapse
Affiliation(s)
- Yufu Sagara
- Banyu Tsukuba Research Institute in collaboration with Merck Research Laboratories, Okubo-3, Ibaraki, Japan.
| | | | | | | | | |
Collapse
|
74
|
Mayerhofer A, Fritz S. Ovarian acetylcholine and muscarinic receptors: hints of a novel intrinsic ovarian regulatory system. Microsc Res Tech 2002; 59:503-8. [PMID: 12467026 DOI: 10.1002/jemt.10228] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
More than two decades ago, the degrading enzyme of the neurotransmitter acetylcholine (ACH) was reported in nerve fibers of the rat ovary. Subsequently, it was assumed that ACH is a neurotransmitter of ovarian nerves, although the sole presence of the degrading enzyme, ACH-esterase, does not allow such a conclusion. That ACH may be involved in the complex regulation of ovarian functions, including hormone production, was indicated by studies using, for example, granulosa cells (GCs). The lack of detailed information about both source(s) and functions of ACH in the ovary prompted us to examine sites of ovarian ACH-synthesis and ACH-receptor-bearing target cells. We also started to identify functions of ACH in cultured human GCs. While ovarian innervation and recently described neuron-like cells of the ovary were not immunoreactive for the ACH-synthesizing enzyme, choline-acetyl transferase (CHAT), we found immunoreactivity in GCs of rodents and primates. Isolated human and rat GCs produced ACH and contained the vesicular ACH transporter (VACHT). These results indicate that endocrine GCs are an unexpected non-neuronal source of ACH in the ovary. Moreover, these cells and GCs in vivo contain ACH-receptors of the muscarinic subtype (MR), namely M1R and M5R. In contrast, oocytes express M3R. MR of human GCs are functional and cholinergic stimulation is linked to rapid increases in intracellular Ca(++) levels. M1/5R activation also led to increased cell proliferation of human GCs in vitro and this stimulatory effect was found to be associated with rapid disruption of gap junction communication. Ongoing studies begin to identify regulation of ion channels and altered gene expression as consequences of MR stimulation. Thus, our results outline first details of an unexpected intraovarian, non-neuronal cholinergic system, and suggest that it may be involved in the regulation of cell proliferation in the ovary.
Collapse
Affiliation(s)
- Artur Mayerhofer
- Anatomisches Institut der Universität München, D-80802 München, Germany.
| | | |
Collapse
|
75
|
Hsieh DJY, Liao CF. Zebrafish M2 muscarinic acetylcholine receptor: cloning, pharmacological characterization, expression patterns and roles in embryonic bradycardia. Br J Pharmacol 2002; 137:782-92. [PMID: 12411408 PMCID: PMC1573553 DOI: 10.1038/sj.bjp.0704930] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. A zebrafish M2 muscarinic acetylcholine receptor (mAChR) gene was cloned. It encodes 495 amino acids in a single exon. The derived amino acid sequence is 73.5% identical to its human homologue. 2. Competitive binding studies of the zebrafish M2 receptor and [(3)H]-NMS gave negative log dissociation constants (pK(i)) for each antagonist as follows: atropine (9.16)>himbacine (8.05)>/=4-DAMP (7.83)>AF-DX 116 (7.26)>/=pirenzepine (7.18)>/=tropicamide (6.97)>/=methoctramine (6.82)>/=p-F-HHSiD (6.67)>carbachol (5.20). The antagonist affinity profile correlated with the profile of the human M2 receptor, except for pirenzepine. 3. Reverse transcription polymerase chain reaction and Southern blotting analysis demonstrated that the M2 mAChR mRNA levels increased during the segmentation period (12 h post-fertilization; h.p.f.) in zebrafish. By whole-mount in situ hybridization, the M2 mAChR was first detectable in the heart, vagus motor ganglion, and vagus sensory ganglion at 30, 48 and 60 h.p.f., respectively. 4. The muscarinic receptor that mediates carbachol (CCh)-induced bradycardia was functionally mature at 72 h.p.f. The effect of CCh-induced bradycardia was antagonized by several muscarinic receptor antagonists with the order of potency (pIC(50) values): atropine (6.76)>methoctramine (6.47)>himbacine (6.10)>4-DAMP (5.72)>AF-DX 116 (4.77), however, not by pirenzepine, p-F-HHSiD, or tropicamide (<10 micro M). 5. The effect of CCh-induced bradycardia was abolished completely before 56 h.p.f. by M2 RNA interference, and the bradycardia effect gradually recovered after 72 h.p.f. The basal heart rate was increased in embryos injected with M2 mAChR morpholino antisense oligonucleotide (M2 MO) and the effect of CCh-induced bradycardia was abolished by M2 MO in a dose-dependent manner. In conclusion, the results suggest that the M2 mAChR inhibit basal heart rate in zebrafish embryo and the M2 mAChR mediates the CCh-induced bradycardia.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Binding, Competitive
- Bradycardia/chemically induced
- Bradycardia/physiopathology
- Carbachol
- Cloning, Molecular
- DNA/chemistry
- DNA/genetics
- Dose-Response Relationship, Drug
- Embryo, Nonmammalian/drug effects
- Embryo, Nonmammalian/metabolism
- Embryo, Nonmammalian/physiopathology
- Gene Expression Regulation, Developmental/drug effects
- Heart Rate/drug effects
- Heart Rate/physiology
- L Cells
- Mice
- Microinjections
- Molecular Sequence Data
- Muscarinic Antagonists/metabolism
- Muscarinic Antagonists/pharmacology
- Oligonucleotides, Antisense/pharmacology
- RNA, Double-Stranded/administration & dosage
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/physiology
- Receptor, Muscarinic M2
- Receptors, Muscarinic/drug effects
- Receptors, Muscarinic/genetics
- Receptors, Muscarinic/physiology
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Zebrafish/embryology
- Zebrafish/genetics
- Zebrafish/physiology
Collapse
Affiliation(s)
- Dennis Jine-Yuan Hsieh
- Graduate Institue of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Cell Signaling Laboratory, Institute of Zoology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Ching-Fong Liao
- Graduate Institue of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Cell Signaling Laboratory, Institute of Zoology, Academia Sinica, Taipei, Taiwan, Republic of China
- Institute of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Author for correspondence:
| |
Collapse
|
76
|
Choppin A. Muscarinic receptors in isolated urinary bladder smooth muscle from different mouse strains. Br J Pharmacol 2002; 137:522-8. [PMID: 12359634 PMCID: PMC1573519 DOI: 10.1038/sj.bjp.0704897] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
1. The pharmacological characteristics of muscarinic receptors in male and female mouse urinary bladder smooth muscle from different strains (C57Bl/6, 129/SvJ and hybrid backcross N1F2) were studied. 2. (+)-Cis-dioxolane, oxotremorine-M, acetylcholine, carbachol and pilocarpine induced concentration-dependent contractions of the urinary bladder smooth muscle (range for pEC(50)=6.4-6.6, 6.2-6.7, 6.2-6.4, 5.4-6.0 and 0.0-5.1, T(max)=1.9-4.7 g, 1.3-3.4 g, 1.0-3.0 g, 1.4-2.4 and 0.0-0.3 g, respectively, n=4-6 depending on the gender and the strain). In females, these contractions were competitively antagonized by a range of muscarinic receptor antagonists (pK(B) value range, depending on the strain): atropine (8.0-8.9), pirenzepine (6.1-6.4), 4-DAMP (7.6-8.4), methoctramine (5.6-6.1), p-F-HHSiD (7.5-7.7), zamifenacin (7.7-8.4) and darifenacin (8.2-8.7). 3. In recontraction studies, in which the muscarinic M(3) receptor population was decreased, and conditions optimized to study M(2) receptor activation, methoctramine exhibited an affinity estimate consistent with muscarinic M(3) receptors (pK(B)=6.26+/-0.08, pA(2)=6.31+/-0.07; pK(B)=6.09+/-0.22, pA(2)=6.08+/-0.01 for female inbred strain 129/SvJ and hybrid backcross N1F2, respectively) or intermediate between the one expected for this compound at M(2) and M(3) receptors, (pK(B)=6.66+/-0.08, pA(2)=7.00+/-0.27 for female inbred strain C57BL/6). 4. These data study suggest that muscarinic M(3) receptors are the predominant, if not the exclusive, subtype mediating contractile responses to muscarinic agonists in female mouse urinary bladder smooth muscle, with strain differences.
Collapse
Affiliation(s)
- A Choppin
- Genitourinary-Pharmacology, Deltagen, Inc., Menlo Park, California, CA 94025, USA.
| |
Collapse
|
77
|
Tobin G, Giglio D, Götrick B. Studies of muscarinic receptor subtypes in salivary gland function in anaesthetized rats. Auton Neurosci 2002; 100:1-9. [PMID: 12422954 DOI: 10.1016/s1566-0702(02)00139-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The in vivo study aimed to examine whether muscarinic receptor subtypes other than muscarinic M3 receptors exert exocrine functional roles in the rat salivary glands. The effects of pirenzepine, methoctramine and 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) were examined on secretion from the major salivary glands evoked by acetylcholine (0.001-10 micromol kg(-1) i.v.) in pentobarbitone-anaesthetized rats. Observations were occasionally made on glandular blood flow. 4-DAMP (0.1-100 nmol kg(-1) i.v.) markedly and equipotently inhibited the acetylcholine-evoked fluid responses in all glands. Pirenzepine (0.1 micromol kg(-1) i.v.-10 mmol kg(-1) i.v.) showed significantly lower inhibitory potency than 4-DAMP, most conspicuously in the parotid, while methoctramine (0.1 micromol kg(-1) i.v.-10 mmol kg(-1) i.v.) exerted an even lesser inhibitory effect. Also against acetylcholine-evoked blood flow increases, 4-DAMP showed a conspicuous potency. At 1 and 10 micromol kg(-1) i.v. of pirenzepine, the antagonist reduced the protein concentration in the submandibular saliva, but not in the parotid saliva. While 4-DAMP (1 and 10 nmol kg(-1) i.v.) significantly inhibited acetylcholine-evoked protein secretory responses in the submandibular glands, methoctramine (below 10 micromol kg(-1) i.v.) affected the responses in neither gland. The reduction of the protein concentration in submandibular saliva caused by 4-DAMP and pirenzepine was inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME; 30 mg kg(-1) i.p.), while L-NAME had no or only minute effects on the parotid protein secretion. Thus, in addition to muscarinic M3 receptors, other muscarinic receptors contribute to in vivo functional responses in rat submandibular and sublingual glands. While these other receptors are muscarinic M1 receptors in the sublingual gland, they may be a different subtype, possibly muscarinic M5 receptors, in the submandibular gland. However, muscarinic M1 receptors may induce indirect effects via nitric oxide in the submandibular gland.
Collapse
Affiliation(s)
- Gunnar Tobin
- Department of Pharmacology, Göteborg University, Sweden.
| | | | | |
Collapse
|
78
|
Basile AS, Fedorova I, Zapata A, Liu X, Shippenberg T, Duttaroy A, Yamada M, Wess J. Deletion of the M5 muscarinic acetylcholine receptor attenuates morphine reinforcement and withdrawal but not morphine analgesia. Proc Natl Acad Sci U S A 2002; 99:11452-7. [PMID: 12154229 PMCID: PMC123277 DOI: 10.1073/pnas.162371899] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2002] [Accepted: 06/21/2002] [Indexed: 11/18/2022] Open
Abstract
Little is known about the physiological roles of the M5 muscarinic receptor, the last member of the muscarinic receptor family (M1-M5) to be cloned. In the brain, the M5 receptor subtype is preferentially expressed by dopaminergic neurons of the substantia nigra and the ventral tegmental area. Dopaminergic neurons located in the ventral tegmental area are known to play important roles in mediating both the rewarding effects of opiates and other drugs of abuse and the manifestations of opiate/drug withdrawal symptoms. We therefore speculated that acetylcholine-dependent activation of M5 receptors might modulate the manifestations of opiate reward and withdrawal. This hypothesis was tested in a series of behavioral, biochemical, and neurochemical studies using M5 receptor-deficient mice (M5-/- mice) as novel experimental tools. We found that the rewarding effects of morphine, as measured in the conditioned place preference paradigm, were substantially reduced in M5-/- mice. Furthermore, both the somatic and affective components of naloxone-induced morphine withdrawal symptoms were significantly attenuated in M5-/- mice. In contrast, the analgesic efficacy of morphine and the development of tolerance to the analgesic effects of morphine remained unaltered by the lack of M5 receptors. The finding that M5 receptor activity modulates both morphine reward and withdrawal processes suggests that M5 receptors may represent a novel target for the treatment of opiate addiction.
Collapse
Affiliation(s)
- Anthony S Basile
- Neuroscience Group, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA.
| | | | | | | | | | | | | | | |
Collapse
|
79
|
Morita H, Abe K, Ito Y, Inoue R. Possible involvement of M5 muscarinic receptor in the enhancing actions of the novel gastroprokinetic agent Z-338 on nifedipine-sensitive voltage-dependent Ca2+ currents in guinea pig stomach. JAPANESE JOURNAL OF PHARMACOLOGY 2002; 89:356-65. [PMID: 12233813 DOI: 10.1254/jjp.89.356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We investigated the effects of the novel gastroprokinetic agent Z-338 (N-(N-N'-diisopropylaminoethyl)-[2-(2-hydroxy-4,5-dimethoxybenzoylamino)-1,3-thiazole-4-yl] carboxyamide monohydrochloride trihydrate) on L-type voltage-dependent Ca2+ currents (ICa) in guinea pig gastric myocytes by using the whole-cell patch clamp technique. Bath-applied acetylcholine (ACh) produced biphasic effects on ICa, i.e., enhancement (1-100 nM) and inhibition (1-100 microM), both of which were abolished by pretreatment with atropine (10 microM) or intracellular perfusion of GDPbetaS (500 microM). Z-338 (> or = 1 nM, ED50: 120 nM) mimicked the enhancing effects of ACh, but did not inhibit ICa. The effects of Z-338 and ACh were non-additive and blocked by atropine and GDPbetaS, but not by pertussis toxin (PTX) pretreatment (500 ng/ml). ACh (> or = 1 microM) induced slow inward currents via activation of the muscarinic receptor/PTX-sensitive G-protein pathway, but Z-338 was devoid of these effects. Neither pirenzepine (1 microM), AF-DX116 (1 microM), nor oxybutynin (100 nM) could prevent Z-338 (1 microM) and ACh (10 nM) from enhancing ICa, whilst 4-DAMP (100 nM) blocked the effects of Z-338 and ACh. Bath-application of protein kinase C (PKC) activator PDBu (phorbol-12,13-dibutyrate) (250 nM) enhanced ICa, and conversely, pipette inclusion of PKC inhibitor peptide (150 microM) abolished the effects of ACh and Z-338 on ICa. These results collectively suggest that although contribution of the M3 receptor is not excluded, the major actions of Z-338 on gastric myocytes are potentiation of ICa through activation of M5-like receptor.
Collapse
Affiliation(s)
- Hiromitsu Morita
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | | | | |
Collapse
|
80
|
The Role of M2 Muscarinic Receptor Subtypes Mediating Contraction of the Circular and Longitudinal Smooth Muscle of the Pig Proximal Urethra. J Urol 2002. [DOI: 10.1016/s0022-5347(05)64913-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
81
|
The Role of M2 Muscarinic Receptor Subtypes Mediating Contraction of the Circular and Longitudinal Smooth Muscle of the Pig Proximal Urethra. J Urol 2002. [DOI: 10.1097/00005392-200207000-00097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
82
|
Gharagozloo P, Lazareno S, Miyauchi M, Popham A, Birdsall NJM. Substituted pentacyclic carbazolones as novel muscarinic allosteric agents: synthesis and structure-affinity and cooperativity relationships. J Med Chem 2002; 45:1259-74. [PMID: 11881995 DOI: 10.1021/jm010946z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two series of pentacyclic carbazolones, 22 and 23, have been synthesized utilizing a facile intramolecular Dielsminus signAlder reaction and are allosteric modulators at muscarinic acetylcholine receptors. Their affinities and cooperativities with acetylcholine and the antagonist N-methylscopolamine (NMS) at M(1)minus signM(4) receptors have been analyzed and compared. All of the synthesized compounds are negatively cooperative with acetylcholine. In contrast, the majority of the compounds exhibit positive cooperativity with NMS, particularly at M(2) and M(4) receptors. The subtype selectivity, in terms of affinity, was in general M(2) > M(1) > M(4) > M(3). The largest increases in affinity produced by a single substitution of the core structure were given by the 1-OMe (22b) and 1-Cl (22d) derivatives. The position of the N in the ring did not appear to be important for binding affinity or cooperativity. Two compounds 22y and 23i, both trisubstituted analogues, were the most potent compounds synthesized, with dissociation constants of 30minus sign100 nM for the M(2) NMS-liganded and unliganded receptor, respectively. The results indicate that the allosteric site, like the primary binding site, is capable of high-affinity interactions with molecules of relatively low molecular weight.
Collapse
Affiliation(s)
- Parviz Gharagozloo
- MRC Technology Research Division, 1-3 Burtonhole Lane, Mill Hill, London, NW7 1AD, UK.
| | | | | | | | | |
Collapse
|
83
|
Kennedy JS, Bymaster FP, Schuh L, Calligaro DO, Nomikos G, Felder CC, Bernauer M, Kinon BJ, Baker RW, Hay D, Roth HJ, Dossenbach M, Kaiser C, Beasley CM, Holcombe JH, Effron MB, Breier A. A current review of olanzapine's safety in the geriatric patient: from pre-clinical pharmacology to clinical data. Int J Geriatr Psychiatry 2001; 16 Suppl 1:S33-61. [PMID: 11748788 DOI: 10.1002/1099-1166(200112)16:1+<::aid-gps571>3.0.co;2-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Olanzapine (OLZ) is unique among currently available antipsychotic medications in its antagonism of a range of receptor systems including dopamine, norepinephrine, serotonin, acetylcholine, and histamine. Olanzapine's mechanistic complexity provides a broad efficacy profile in patients with schizophrenia and acute, pure or mixed mania. Patients experience symptomatic relief of mania, anxiety, hallucinations, delusions, and agitation/aggression and reduced depressive, negative, and some cognitive symptoms. This paper will review the safety profile of OLZ, focusing on the elderly, where data are available. METHOD Preclinical and clinical studies of OLZ are reviewed, with emphasis on its possible effects on the cholinergic system and the histamine H(1) receptor. Weight change and related metabolic considerations, cardiac and cardiovascular safety, and motor function during treatment with OLZ are also reviewed. RESULTS AND CONCLUSION In vitro receptor characterization methods, when done using physiologically relevant conditions allow accurate prediction of the relatively low rate of anticholinergic-like adverse events, extrapyramidal symptoms, and cardiovascular adverse events during treatment with OLZ. Currently available clinical data suggest olanzapine is predictably safe in treating adult patients of any age with schizophrenia and acute bipolar mania, as well as in treatment of patients with some types of neurodegenerative disorders.
Collapse
Affiliation(s)
- J S Kennedy
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
84
|
Yamada M, Lamping KG, Duttaroy A, Zhang W, Cui Y, Bymaster FP, McKinzie DL, Felder CC, Deng CX, Faraci FM, Wess J. Cholinergic dilation of cerebral blood vessels is abolished in M(5) muscarinic acetylcholine receptor knockout mice. Proc Natl Acad Sci U S A 2001; 98:14096-101. [PMID: 11707605 PMCID: PMC61174 DOI: 10.1073/pnas.251542998] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The M(5) muscarinic receptor is the most recent member of the muscarinic acetylcholine receptor family (M(1)-M(5)) to be cloned. At present, the physiological relevance of this receptor subtype remains unknown, primarily because of its low expression levels and the lack of M(5) receptor-selective ligands. To circumvent these difficulties, we used gene targeting technology to generate M(5) receptor-deficient mice (M5R(-/-) mice). M5R(-/-) mice did not differ from their wild-type littermates in various behavioral and pharmacologic tests. However, in vitro neurotransmitter release experiments showed that M(5) receptors play a role in facilitating muscarinic agonist-induced dopamine release in the striatum. Because M(5) receptor mRNA has been detected in several blood vessels, we also investigated whether the lack of M(5) receptors led to changes in vascular tone by using several in vivo and in vitro vascular preparations. Strikingly, acetylcholine, a powerful dilator of most vascular beds, virtually lost the ability to dilate cerebral arteries and arterioles in M5R(-/-) mice. This effect was specific for cerebral blood vessels, because acetylcholine-mediated dilation of extra-cerebral arteries remained fully intact in M5R(-/-) mice. Our findings provide direct evidence that M(5) muscarinic receptors are physiologically relevant. Because it has been suggested that impaired cholinergic dilation of cerebral blood vessels may play a role in the pathophysiology of Alzheimer's disease and focal cerebral ischemia, cerebrovascular M(5) receptors may represent an attractive therapeutic target.
Collapse
Affiliation(s)
- M Yamada
- Laboratory of Bioorganic Chemistry National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
85
|
Abstract
In the mammalian heart, cardiac function is under the control of the sympathetic and parasympathetic nervous system. All regions of the mammalian heart are innervated by parasympathetic (vagal) nerves, although the supraventricular tissues are more densely innervated than the ventricles. Vagal activation causes stimulation of cardiac muscarinic acetylcholine receptors (M-ChR) that modulate pacemaker activity via I(f) and I(K.ACh), atrioventricular conduction, and directly (in atrium) or indirectly (in ventricles) force of contraction. However, the functional response elicited by M-ChR-activation depends on species, age, anatomic structure investigated, and M-ChR-agonist concentration used. Among the five M-ChR-subtypes M(2)-ChR is the predominant isoform present in the mammalian heart, while in the coronary circulation M(3)-ChR have been identified. In addition, evidence for a possible existence of an additional, not M(2)-ChR in the heart has been presented. M-ChR are subject to regulation by G-protein-coupled-receptor kinase. Alterations of cardiac M(2)-ChR in age and various kinds of disease are discussed.
Collapse
Affiliation(s)
- S Dhein
- Institute of Pharmacology, University of Halle-Wittenberg, Germany.
| | | | | |
Collapse
|
86
|
Choppin A, Eglen RM. Pharmacological characterization of muscarinic receptors in mouse isolated urinary bladder smooth muscle. Br J Pharmacol 2001; 133:1035-40. [PMID: 11487513 PMCID: PMC1572871 DOI: 10.1038/sj.bjp.0704165] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2001] [Revised: 05/11/2001] [Accepted: 05/11/2001] [Indexed: 11/08/2022] Open
Abstract
The pharmacological characteristics of muscarinic receptors in the male mice urinary bladder smooth muscle were studied. (+)-Cis-dioxolane, oxotremorine-M, acetylcholine, carbachol and pilocarpine induced concentration-dependent contractions of the urinary bladder smooth muscle (pEC(50)=6.6+/-0.1, 6.9+/-0.1, 6.7+/-0.1, 5.8+/-0.1 and 5.8+/-0.1, E(Max)=3.2+/-0.8 g, 2.7+/-0.4 g, 1.0+/-0.1 g, 2.7+/-0.3 and 0.9+/-0.2 g, respectively, n=4). These contractions were competitively antagonized by a range of muscarinic receptor antagonists (pK(B) values): atropine (9.22+/-0.09), pirenzepine (6.85+/-0.08), 4-DAMP (8.42+/-0.14), methoctramine (5.96+/-0.05), p-F-HHSiD (7.48+/-0.09), tolterodine (8.89+/-0.13), AQ-RA 741 (7.04+/-0.12), s-secoverine (8.21+/-0.09), zamifenacin (8.30+/-0.17) and darifenacin (8.70+/-0.09). In this tissue, the pK(B) values correlated most favourably with pK(i) values for these compounds at human recombinant muscarinic M(3) receptors. A significant correlation was also noted at human recombinant muscarinic m5 receptors given the poor discriminative ability of ligands between M(3) and m5 receptors. In recontraction studies, in which the muscarinic M(3) receptor population was decreased, and conditions optimized to study M(2) receptor activation, methoctramine exhibited an affinity estimate consistent with muscarinic M(3) receptors (pK(B)=6.23+/-0.14; pA(2)=6.16+/-0.03). Overall, these data study suggest that muscarinic M(3) receptors are the predominant, if not the exclusive, subtype mediating contractile responses to muscarinic agonists in male mouse urinary bladder smooth muscle.
Collapse
Affiliation(s)
- A Choppin
- Genitourinary-Pharmacology, Neurobiology Unit, Roche Bioscience, Palo Alto, California, CA 94304, U.S.A.
| | | |
Collapse
|
87
|
Abstract
Muscarinic acetylcholine receptor subtypes have been the subjects of research for at least a quarter of a century. Nonetheless, there are few selective muscarinic receptor ligands presently used as therapeutics. The extensive development of muscarinic M(1) receptor agonists for the treatment of cognitive dysfunction has culminated in a series of unsuccessful drug candidates, which reflects a lack of understanding of the disease and the role played by muscarinic cholinergic transmission. Paradoxically, the most successful antagonist approved for use in urinary incontinence is the nonselective muscarinic receptor antagonist tolterodine. This deficit in subtype-selective ligands could be circumvented by the development of transgenic mice, each lacking functional M(1), M(2), M(3), M(4) or M(5) receptors. In this article, the current status of muscarinic receptor research is critically assessed.
Collapse
Affiliation(s)
- R M Eglen
- DiscoveRx Corp, Fremont, CA 94538, USA.
| | | | | |
Collapse
|
88
|
Meloy TD, Daniels DV, Hegde SS, Eglen RM, Ford AP. Functional characterization of rat submaxillary gland muscarinic receptors using microphysiometry. Br J Pharmacol 2001; 132:1606-14. [PMID: 11264256 PMCID: PMC1572705 DOI: 10.1038/sj.bjp.0703971] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2000] [Revised: 01/22/2001] [Accepted: 01/22/2001] [Indexed: 11/09/2022] Open
Abstract
1. Muscarinic cholinoceptors (MChR) in freshly dispersed rat salivary gland (RSG) cells were characterized using microphysiometry to measure changes in acidification rates. Several non-selective and selective muscarinic antagonists were used to elucidate the nature of the subtypes mediating the response to carbachol. 2. The effects of carbachol (pEC(50) = 5.74 +/- 0.02 s.e.mean; n = 53) were highly reproducible and most antagonists acted in a surmountable, reversible fashion. The following antagonist rank order, with apparent affinity constants in parentheses, was noted: 4-DAMP (8.9)= atropine (8.9) > tolterodine (8.5) > oxybutynin (7.9) > S-secoverine (7.2) > pirenzepine (6.9) > himbacine (6.8) > AQ-RA 741 (6.6) > methoctramine (5.9). 3. These studies validate the use of primary isolated RSG cells in microphysiometry for pharmacological analysis. These data are consistent with, and extend, previous studies using alternative functional methods, which reported a lack of differential receptor pharmacology between bladder and salivary gland tissue. 4. The antagonist affinity profile significantly correlated with the profile at human recombinant muscarinic M(3) and M(5) receptors. Given a lack of antagonists that discriminate between M(3) and M(5), definitive conclusion of which subtype(s) is present within RSG cells cannot be determined.
Collapse
Affiliation(s)
- T D Meloy
- Neurobiology Unit, Roche Bioscience, 3401 Hillview Avenue, Palo Alto, California, CA 94304, USA.
| | | | | | | | | |
Collapse
|
89
|
Teraoka H, Maruyama Y, Takehana K, Iwanaga T, Hiraga T, Fujita S, Ohta T. Ca(2+) signaling in porcine duodenal glands by muscarinic receptor activation. Am J Physiol Gastrointest Liver Physiol 2001; 280:G729-37. [PMID: 11254500 DOI: 10.1152/ajpgi.2001.280.4.g729] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The duodenal glands have been thought to play an important role in defense against proximal duodenal ulcer; however, the secretory mechanisms of these glands remain to be determined. In isolated duodenal acinar cells of the pig, we investigated the effects of ACh on intracellular Ca(2+) concentration ([Ca(2+)](i)) and on membrane currents with fura 2 fluorometry and the patch clamp technique. ACh caused a transient increase in [Ca(2+)](i), and the increase was markedly inhibited by atropine or 4-diphenylacetoxy-N-methylpiperidine methiodide but not by hexamethonium, pirenzepine, or methoctramine. The expression of mRNA for the M(3) subtype far exceeded that for either M(1) or M(2) as revealed by real-time quantitative PCR and in situ hybridization. The rise in [Ca(2+)](i) evoked by ACh was largely inhibited by thapsigargin but slightly affected by extracellular Ca(2+) deprivation. Caffeine had no effect on [Ca(2+)](i). ACh elicited Ca(2+)-dependent K(+) currents, a finding similar to the response to inositol 1,4,5,-trisphosphate applied intracellularly. These results suggest the presence of M(3) receptors linked to Ca(2+) release in porcine duodenal glands.
Collapse
Affiliation(s)
- H Teraoka
- Department of Toxicology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan.
| | | | | | | | | | | | | |
Collapse
|
90
|
Nitschke R, Henger A, Ricken S, Müller V, Köttgen M, Bek M, Pavenstädt H. Acetylcholine increases the free intracellular calcium concentration in podocytes in intact rat glomeruli via muscarinic M(5) receptors. J Am Soc Nephrol 2001; 12:678-687. [PMID: 11274228 DOI: 10.1681/asn.v124678] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The effects of acetylcholine (ACh) on the free intracellular calcium concentration ([Ca2+](i)) of microdissected glomeruli were investigated using fura-2 fluorescence digital imaging and two-photon confocal microscopy. ACh caused a concentration-dependent [Ca2+](i) increases with an initial peak followed by a sustained plateau, which was suppressed by reduced extracellular Ca2+ concentrations. The [Ca2+](i) plateau was not affected by the L-type Ca2+ channel blocker nicardipine, whereas gadolinium and lanthanum (both at 1 microM) blocked the plateau. Diphenylacetoxy-N:-methylpiperidine methiodide (100 nM), an M(3)/M(5) receptor antagonist, and pirenzepine (1 microM), an M(1) receptor antagonist, completely inhibited the effect of ACh. [Ca2+](i) measurements using two-photon excitation of fluo-3 and staining of the cells with calcein/acetoxymethyl ester, for observation of the capillary network together with the glomerular cells, showed that [Ca2+](i) was increased in single podocytes. Immunohistochemical studies did not demonstrate M(3) receptor expression in glomerular cells. M(1) receptors could be detected only in the parietal sheet of Bowman's capsule, whereas M(5) receptors were found only in podocytes. The data show that ACh increases [Ca2+](i) in podocytes of intact glomeruli, most likely via muscarinic M(5) receptors.
Collapse
Affiliation(s)
- Roland Nitschke
- Institute of Physiology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Anna Henger
- Department of Medicine, Division of Nephrology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Sigrid Ricken
- Institute of Physiology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Victoria Müller
- Institute of Physiology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Michael Köttgen
- Institute of Physiology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Martin Bek
- Department of Medicine, Division of Nephrology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Hermann Pavenstädt
- Department of Medicine, Division of Nephrology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| |
Collapse
|
91
|
Choppin A, Eglen RM. Pharmacological characterization of muscarinic receptors in dog isolated ciliary and urinary bladder smooth muscle. Br J Pharmacol 2001; 132:835-42. [PMID: 11181424 PMCID: PMC1572633 DOI: 10.1038/sj.bjp.0703901] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2000] [Revised: 11/11/2000] [Accepted: 12/11/2000] [Indexed: 01/02/2023] Open
Abstract
1. The pharmacological characteristics of muscarinic receptors mediating contraction of dog isolated ciliary muscle were determined and compared to those mediating contraction of dog urinary bladder smooth muscle. 2. (+)-Cis-dioxolane induced concentration-dependent contractions of ciliary muscle (pEC50=7.18+/-0.07, Emax=453+/-64 mg, n=19) and urinary bladder isolated smooth muscle (pEC50=6.55+/-0.07, Emax=11+/-1 g, n=19). These responses were antagonized by several muscarinic receptor antagonists (pKb values for the ciliary muscle and the bladder smooth muscle, respectively): atropine (8.25+/-0.14 and 9.21+/-0.09), pirenzepine (6.31+/-0.13 and 6.70+/-0.25), tolterodine (7.97+/-0.14 and 8.68+/-0.12), oxybutynin (7.40+/-0.08 and 7.88+/-0.12), zamifenacin (6.46+/-0.19 and 7.69+/-0.11), S-secoverine (6.66+/-0.14 and 8.13+/-0.07), AQ-RA 741 (6.16+/-0.15 and 7.08+/-0.23), p-F-HHSiD (7.10+/-0.27 and 7.35+/-0.07) and responses were not antagonized by PD 102807 (up to 100 nM). 3. In urinary bladder smooth muscle, the profile of antagonist pKB values correlated significantly with pK(i) values at human recombinant m3 muscarinic receptors, suggesting that M3 muscarinic receptors mediated the response. In the ciliary muscle, a significant (P<0.01) correlation was obtained with human recombinant m3 and m5 receptors. 4. Darifenacin displayed insurmountable antagonism at receptors in the bladder. At receptors in the ciliary muscle, it exhibited two phases of antagonism, comprising an initial low affinity (pKB<6) component and a high affinity phase (pKB>8). 5. The role of pigmentation in the atypical behaviour of darifenacin was examined. In blue coloured eyes, darifenacin produced apparent surmountable, competitive antagonism of the responses to (+)-cis-dioxolane (pKB=8.76+/-0.07). The antagonist profile obtained in this tissue suggested the involvement of a site which has the pharmacological attributes of the M5 receptor. 6. We suggest that the dog urinary bladder contracts in response to M3 muscarinic receptor activation. Contraction of the brown-eyed dog ciliary muscle is more complex and may include involvement of at least two receptors, possibly the M5 and M3 receptor, whereas blue-eyed dog ciliary muscle may involve a single population of M5 muscarinic receptors.
Collapse
Affiliation(s)
- A Choppin
- Genitourinary-Pharmacology, Neurobiology Unit, Roche Bioscience, Palo Alto, California, CA 94304, USA.
| | | |
Collapse
|