3ubtypes of muscarmic receptors, first hypothesized by Birdsall et al. ~ to explain the anomalous binding of cholinergic agonists to brain receptors~ were later demonstrated with the seEective muscarinic antagonist, pirenzepine 2. Interestingly, the search for selective antagonists, which usually follows the acceptance of a concept, antedated by many years the notion of heterogeneity of rmecari...

Acetylcholine acting on muscarinic M(3) receptors on the detrusor muscle is the principal stimulus for inducing the contractile response for urinary bladder voiding. The urinary bladder expresses, however, all cloned muscarinic receptor subtypes (M(1)-M(5)). In terms of quantity, the M(2) subtype dominates over the M(3) subtype in the detrusor, and its role in contraction seems to be primarily ...

Cholinergic modification of neuronal responsiveness in auditory cortex includes alteration of spontaneous and tone-evoked neuronal discharge. Previously it was suggested that the effects of acetylcholine (ACh) and muscarinic agonists on neuronal discharge resembled those due to increases in the intensity of acoustic stimuli (Ashe et al. 1989). To determine the relationship between neuronal modi...

The hippocampal slice preparation was used to classify cholinergic effects in terms of muscarinic receptor subtypes (M1 or M2) and biochemical effector systems linked to these effects in CA1 pyramidal cells. Based on the action of the M1 antagonist pirenzepine and the M2 antagonist gallamine, the muscarinic-induced membrane depolarization and blockade of the afterhyperpolarization appear to res...

The effects of the muscarinic receptor agonist 6beta-acetoxy nortropane on amyloid precursor protein (APP) processing were studied in both transfected Chinese hamster ovary cells stably expressing muscarinic M(1) receptors (denoted as CHOm(1) cell line) and in cerebral cortical and hippocampal slices. Exposure of CHOm(1) cells to 6beta-acetoxy nortropane for 1 h significantly increased the secr...

Acute exposure to low concentrations of methylmercury (MeHg) causes a severe loss of intracellular calcium (Ca2+(i)) homeostasis, which apparently contributes to neuronal death of cerebellar granule cells in culture. We examined the role of muscarinic receptors in MeHg-induced Ca2+ dysregulation and cell death in rat cerebellar granule cells in vitro using fura-2 single-cell microfluorimetry an...

M3 subtype muscarinic receptors (CHRM3) are over-expressed in colon cancer. In this study, we used Apc(min/+) mice to identify the role of Chrm3 expression in a genetic model of intestinal neoplasia, explored the role of Chrm3 in intestinal mucosal development and determined the translational potential of inhibiting muscarinic receptor activation. We generated Chrm3-deficient Apc(min/+) mice an...

In the eye, it has been previously reported that exposure to a cholinesterase inhibitor results in a reduced miotic response following prolonged exposure and a decreased miotic response to the cholinergic agonists. However, no studies exist that characterize the effect of a single low-level vapor exposure to a nerve agent on parasympathetic function in the eye or determine the threshold dose fo...

Steele SL, Lo KH, Li VW, Cheng SH, Ekker M, Perry SF. Loss of M2 muscarinic receptor function inhibits development of hypoxic bradycardia and alters cardiac -adrenergic sensitivity in larval zebrafish (Danio rerio). Am J Physiol Regul Integr Comp Physiol 297: R412–R420, 2009. First published June 10, 2009; doi:10.1152/ajpregu.00036.2009.—Fish exposed to hypoxia develop decreased heart rate, or ...

Background and Aims: The object of this study was the investigation central antinociceptive effects naringin as well association stimulation opioidergic, serotonergic, adrenergic, cholinergic (muscarinic nicotinic) receptors to analgesia mice due naringin. Methods: Several intraperitoneal doses (20, 40, 80 mg/kg) were injected into models analyzed via hot-plate (integrated supraspinal response)...