Publications (12)118.01 Total impact
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Article: M1-M3 muscarinic acetylcholine receptor-deficient mice: novel phenotypes.
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ABSTRACT: The five muscarinic acetylcholine receptors (M1-M5 mAChRs) mediate a very large number of important physiological functions (Caulfield, 1993; Caulfield and Birdsall, 1998; Wess, 2004). Because of the lack of small molecule 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 proved to be a challenging task. To overcome these difficulties, we recently generated mutant mouse lines deficient in each of the five mAChR genes (M1R-/- mice, M2R-/- mice, M3R-/- mice, etc. [Wess, 2004]). Phenotyping studies showed that each of the five mutant mouse lines displayed characteristic physiological, pharmacological, behavioral, biochemical, or neurochemical deficits (Wess, 2004). This chapter summarizes recent findings dealing with the importance of the M2mAChR for cognitive processes and the roles of the M1 and M3 mAChRs in mediating stimulation of glandular secretion.Journal of Molecular Neuroscience 02/2006; 30(1-2):157-60. · 2.50 Impact Factor -
Article: M1–M3 muscarinic acetylcholine receptor-deficient mice
Journal of Molecular Neuroscience 01/2006; 30(1):157-160. · 2.50 Impact Factor -
Article: Development of a long-acting insulin analog using albumin fusion technology.
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ABSTRACT: The primary therapeutic goal for the treatment of diabetes is maintenance of a long-term, near-normoglycemic condition and prevention of the onset or progression of the complications associated with the disease. Although several analogs of human insulin have been developed, the currently prescribed long-acting insulin analogs do not provide a stable basal glycemia for more than a few hours. Here, we report the development of Albulin, a long-acting insulin analog obtained by direct gene fusion of a single-chain human insulin to human serum albumin. Albulin showed an elimination t(1/2) of approximately 7 h in normoglycemic mice. In vitro pharmacodynamic profiles for Albulin characterized by receptor binding, inhibition of gluconeogenesis, induction of glucose uptake, and global regulation of gene expression in relevant cell types showed that Albulin produced similar activity profiles compared with that of recombinant human insulin. A single Albulin administration in vivo normalized blood glucose level in diabetic mice in a relatively peakless and sustained (24-h) fashion. A further reduction in glucose levels was achieved by administering a recombinant human insulin a few hours after Albulin injection in mice, indicating the potential for Albulin therapy in combination with available fast-acting insulin derivatives. In summary, Albulin displays characteristics of a potent long-acting insulin analog that can be evaluated for use as a novel insulin therapy for patients with insulin-dependent diabetes.Diabetes 02/2005; 54(1):251-8. · 8.29 Impact Factor -
Article: Muscarinic stimulation of pancreatic insulin and glucagon release is abolished in m3 muscarinic acetylcholine receptor-deficient mice.
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ABSTRACT: Pancreatic muscarinic acetylcholine receptors play an important role in stimulating insulin and glucagon secretion from islet cells. To study the potential role of the M(3) muscarinic receptor subtype in cholinergic stimulation of insulin release, we initially examined the effect of the muscarinic agonist, oxotremorine-M (Oxo-M), on insulin secretion from isolated pancreatic islets prepared from wild-type (WT) and M(3) receptor-deficient mice (M3(+/-) and M3(-/-) mice). At a stimulatory glucose level (16.7 mmol/l), Oxo-M strongly potentiated insulin output from islets of WT mice. Strikingly, this effect was completely abolished in islets from M3(-/-) mice and significantly reduced in islets from M3(+/-) mice. Additional in vitro studies showed that Oxo-M-mediated glucagon release was also virtually abolished in islets from M3(-/-) mice. Consistent with the in vitro data, in vivo studies showed that M3(-/-) mice displayed reduced serum insulin and plasma glucagon levels and a significantly blunted increase in serum insulin after an oral glucose load. Despite the observed impairments in insulin release, M3(-/-) mice showed significantly reduced blood glucose levels and even improved glucose tolerance, probably due to the reduction in plasma glucagon levels and the fact that M3(-/-) mice are hypophagic and lean. These findings provide important new insights into the metabolic roles of the M(3) muscarinic receptor subtype.Diabetes 08/2004; 53(7):1714-20. · 8.29 Impact Factor -
Article: Novel insights into M5 muscarinic acetylcholine receptor function by the use of gene targeting technology.
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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.Life Sciences 01/2004; 74(2-3):345-53. · 2.53 Impact Factor -
Article: An integrated functional genomics screening program reveals a role for BMP-9 in glucose homeostasis.
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ABSTRACT: A coordinated functional genomics program was implemented to identify secreted polypeptides with therapeutic applications in the treatment of diabetes. Secreted factors were predicted from a diverse expressed-sequence tags (EST) database, representing >1,000 cDNA libraries, using a combination of bioinformatic algorithms. Subsequently, approximately 8,000 human proteins were screened in high-throughput cell-based assays designed to monitor key physiological transitions known to be centrally involved in the physiology of type 2 diabetes. Bone morphogenetic protein-9 (BMP-9) gave a positive response in two independent assays: reducing phosphoenolpyruvate carboxykinase (PEPCK) expression in hepatocytes and activating Akt kinase in differentiated myotubes. Purified recombinant BMP-9 potently inhibited hepatic glucose production and activated expression of key enzymes of lipid metabolism. In freely fed diabetic mice, a single subcutaneous injection of BMP-9 reduced glycemia to near-normal levels, with maximal reduction observed 30 hours after treatment. BMP-9 represents the first hepatic factor shown to regulate blood glucose concentration. Using a combination of bioinformatic and high-throughput functional analyses, we have identified a factor that may be exploited for the treatment of diabetes.Nature Biotechnology 04/2003; 21(3):294-301. · 23.27 Impact Factor -
Article: Muscarinic receptor subtypes mediating central and peripheral antinociception studied with muscarinic receptor knockout mice: a review.
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ABSTRACT: To gain new insight into the physiological and pathophysiological roles of the muscarinic cholinergic system, we generated mutant mouse strains deficient in each of the five muscarinic acetylcholine receptor subtypes (M(1)-M(5)). In this chapter, we review a set of recent studies dealing with the identification of the muscarinic receptor subtypes mediating muscarinic agonist-dependent analgesic effects by central and peripheral mechanisms. Most of these studies were carried out with mutant mouse strains lacking M(2) or/and M(4) muscarinic receptors. It is well known that administration of centrally active muscarinic agonists induces pronounced analgesic effects. To identify the muscarinic receptors mediating this activity, wild-type and muscarinic receptor mutant mice were injected with the non-subtype-selective muscarinic agonist, oxotremorine (s.c., i.t., and i.c.v.), and analgesic effects were assessed in the tail-flick and hot-plate tests. These studies showed that M(2) receptors play a key role in mediating the analgesic effects of oxotremorine, both at the spinal and supraspinal level. However, studies with M(2)/M(4) receptor double KO mice indicated that M(4) receptors also contribute to this activity. Recent evidence suggests that activation of muscarinic receptors located in the skin can reduce the sensitivity of peripheral nociceptors. Electrophysiological and neurochemical studies with skin preparations from muscarinic receptor mutant mice indicated that muscarine-induced peripheral antinociception is mediated by M(2) receptors. Since acetylcholine is synthesized and released by different cell types of the skin, it is possible that non-neuronally released acetylcholine plays a role in modulating peripheral nociception. Our results highlight the usefulness of muscarinic receptor mutant mice to shed light on the functional roles of acetylcholine released from both neuronal and non-neuronal cells.Life Sciences 04/2003; 72(18-19):2047-54. · 2.53 Impact Factor -
Article: Evaluation of muscarinic agonist-induced analgesia in muscarinic acetylcholine receptor knockout mice.
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ABSTRACT: Centrally active muscarinic agonists display pronounced analgesic effects. Identification of the specific muscarinic acetylcholine receptor (mAChR) subtype(s) mediating this activity is of considerable therapeutic interest. To examine the roles of the M(2) and M(4) receptor subtypes, the two G(i)/G(o)-coupled mAChRs, in mediating agonist-dependent antinociception, we generated a mutant mouse line deficient in both M(2) and M(4) mAChRs [M(2)/M(4) double-knockout (KO) mice]. In wild-type mice, systemic, intrathecal, or intracerebroventricular administration of centrally active muscarinic agonists resulted in robust analgesic effects, indicating that muscarinic analgesia can be mediated by both spinal and supraspinal mechanisms. Strikingly, muscarinic agonist-induced antinociception was totally abolished in M(2)/M(4) double-KO mice, independent of the route of application. The nonselective muscarinic agonist oxotremorine showed reduced analgesic potency in M(2) receptor single-KO mice, but retained full analgesic activity in M(4) receptor single-KO mice. In contrast, two novel muscarinic agonists chemically derived from epibatidine, CMI-936 and CMI-1145, displayed reduced analgesic activity in both M(2) and M(4) receptor single-KO mice, independent of the route of application. Radioligand binding studies indicated that the two CMI compounds, in contrast to oxotremorine, showed >6-fold higher affinity for M(4) than for M(2) receptors, providing a molecular basis for the observed differences in agonist activity profiles. These data provide unambiguous evidence that muscarinic analgesia is exclusively mediated by a combination of M(2) and M(4) mAChRs at both spinal and supraspinal sites. These findings should be of considerable relevance for the development of receptor subtype-selective muscarinic agonists as novel analgesic drugs.Molecular Pharmacology 11/2002; 62(5):1084-93. · 4.88 Impact Factor -
Article: Deletion of the M5 muscarinic acetylcholine receptor attenuates morphine reinforcement and withdrawal but not morphine analgesia.
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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.Proceedings of the National Academy of Sciences 09/2002; 99(17):11452-7. · 9.68 Impact Factor -
Article: Muscarinic induction of hippocampal gamma oscillations requires coupling of the M1 receptor to two mixed cation currents.
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ABSTRACT: Oscillatory network activity at gamma frequencies is assumed to be of major importance in cortical information processing. Whereas the synaptic mechanisms of gamma oscillations have been studied in detail, the ionic currents involved at the cellular level remain to be elucidated. Here we show that in vitro gamma oscillations induced by muscarine require activation of M1 receptors on hippocampal CA3 pyramidal neurons and are absent in M1 receptor-deficient mice. M1 receptor activation depolarizes pyramidal neurons by increasing the mixed Na(+)/K(+) current I(h) and the Ca(2+)-dependent nonspecific cation current I(cat), but not by modulation of I(M). Our data provide important insight into the molecular basis of gamma oscillations by unequivocally establishing a novel role for muscarinic modulation of I(h) and I(cat) in rhythmic network activity.Neuron 03/2002; 33(4):615-24. · 14.74 Impact Factor -
Article: Generation and pharmacological analysis of M2 and M4 muscarinic receptor knockout mice
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ABSTRACT: Muscarinic acetylcholine receptors (M1–M5) play important roles in the modulation of many key functions of the central and peripheral nervous system. To explore the physiological roles of the two Gi-coupled muscarinic receptors, we disrupted the M2 and M4 receptor genes in mice by using a gene targeting strategy. Pharmacological and behavioral analysis of the resulting mutant mice showed that the M2 receptor subtype is critically involved in mediating three of the most striking central muscarinic effects, tremor, hypothermia, and analgesia. These studies also indicated that M4 receptors are not critically involved in these central muscarinic responses. However, M4 receptor-deficient mice showed an increase in basal locomotor activity and greatly enhanced locomotor responses following drug-induced activation of D1 dopamine receptors. This observation is consistent with the concept that M4 receptors exert inhibitory control over D1 receptor-mediated locomotor stimulation, probably at the level of striatal projection neurons where the two receptors are known to be coexpressed. These findings emphasize the usefulness of gene targeting approaches to shed light on the physiological and pathophysiological roles of the individual muscarinic receptor subtypes.Life Sciences 05/2001; 68:2457-2466. · 2.53 Impact Factor -
Article: Mice lacking the M3 muscarinic acetylcholine receptor are hypophagic and lean
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ABSTRACT: Members of the muscarinic acetylcholine receptor family (M1–M5) have central roles in the regulation of many fundamental physiological functionsNature 03/2001; 410(6825):207-212. · 36.28 Impact Factor
Top co-authors
Top Journals
Institutions
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2004–2006
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National Institutes of Health
- Laboratory of Bioorganic Chemistry (LBC)
Bethesda, MD, USA
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2001–2004
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The National Institute of Diabetes and Digestive and Kidney Diseases
Bethesda, MD, USA
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2002
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Eunice Kennedy Shriver National Institute of Child Health and Human Development
Rockville, MD, USA
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