Muscarinic M5 Receptors

The muscarinic M5 receptor is the only muscarinic subtype expressed by the dopamine-containing neurons of the substantia nigra pars compacta, a structure that provides the principal dopamine innervation to the striatum (Felder et al. 2000). Activation of muscarinic M5 receptors thus facilitates striatal dopamine release -although it is likely that other muscarinic receptors, including the M4 receptor, are involved (Vilaro et al. 1990). The muscarinic M5 receptor is also the predominant subtype...

References

Ahuja S, Hornak V, Yan EC, Syrett N, Goncalves JA, Hirshfeld A, Ziliox M, Sakmar TP, Sheves M, Reeves PJ, Smith SO, Eilers M (2009) Helix movement is coupled to displacement of the second extracellular loop in rhodopsin activation. Nat Struct Mol Biol 16 168-175 Antony J, Kellershohn K, Mohr-Andra M, Kebig A, Prilla S, Muth M, Heller E, Disingrini T, Dallanoce C, Bertoni S, Schrobang J, Trankle C, Kostenis E, Christopoulos A, Holtje HD, Barocelli E, De Amici M, Holzgrabe U, Mohr K (2009)...

Muscarinic M3 Receptors

The muscarinic M3 receptor is widely distributed in the CNS, albeit at lower levels than other muscarinic receptor subtypes (Levey 1993). Muscarinic M3-deficient mice are hypophagic and lean, suggesting a central role for this subtype in regulating food intake. Although this may involve modulation of hypothalamic melanin-concentrating hormone levels, deficits in salivary flow could also contribute to the hypophagic phenotype (Gautam et al. 2008). The M3 receptor is expressed at relatively high...

M5 Receptors

The human M5 receptor gene (CHRM5) is located on chromosome 15q26 and consists of a single coding exon and three alternatively spliced 5'-UTRs (Anney et al. 2007). The NCBI database contains > 200 SNPs of this gene. We have identified only a single study linking a polymorphism of the M5 gene to phenotype (Anney et al. 2007). In that study, a non-coding C > T SNP (rs7162140) was reported to have a prevalence of 19 and to be associated with the number of cigarettes smoked and cannabis...

Neuronal M3 mAChRs Promote the Accrual of Bone Mass

Shi et al. 2010 recently reported that whole-body M3 receptor KO mice show a decrease in bone mass, due to decreased bone formation and increased bone resorption. This phenotype was not observed with M1, M2, or M4 receptor-deficient mice. Gene expression studies showed that M3 mAChR expression in osteoblasts is barely above the detection limit of qRT-PCR. Moreover, mutant mice in which the M3 mAChR gene had been deleted selectively in osteoblasts did not display any changes in bone mass, bone...