In this study, we investigated the effect of nicotinic receptor agonists and antagonists on the analgesic response to morphine in the formalin test. In experiments conducted in mice, nicotine produced an early dose-dependent analgesic effect. At a dose of 0.5 mg/kg, mecamylamine, a nicotinic receptor inhibitor, suppressed the analgesic effect induced by 0.1 mg/kg nicotine in both stages of th...

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 li...

The purpose of our studies was to determine the effects of muscarinic receptor agonists on conditioned avoidance responding in the rat. Rats were trained to avoid or escape an electric shock delivered to the feet in a discrete trial procedure. The muscarinic receptor agonists pilocarpine and [2-ethyl-8-methyl-2,8-diazaspiro(4. 5)decane-1,3-dione] hydrochloride (RS86) and the cholinesterase inhi...

Receptors for many neurotransmitters including catecholamines and acetylcholine (ACh) have been detected on the cell surface of lymphocytes. It has been demonstrated that a human T cell line synthesizes ACh and suggested that ACh may be an autacoid modulating T cell-dependent immune responses. However, the biochemical interactions of the ACh system with the immune system have not been elucidate...

Three metabolites of N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-2-nitroaniline fumarate (SK-946), a novel central muscarinic cholinergic receptor agonist, were prepared to confirm their proposed structures, and tested for muscarinic receptor affinity in vitro.

The molecular mechanisms through which muscarinic receptors are activated upon binding of the neurotransmitter acetylcholine (ACh) are still poorly understood. Classical structure-function relationship studies have previously established that the ACh ester moiety plays a key role in muscarinic receptor recognition and activation. Consistent with this notion, all recently proposed three-dimensio...

By means of the expression of two chimeric receptors, alpha(2)/M(3) and M(3)/alpha(2), in which the carboxy-terminal receptor portions, containing transmembrane domains VI and VII, were exchanged between the alpha(2C)-adrenergic and the M(3) muscarinic receptor, it has been shown that G protein-coupled receptors are able to interact functionally with each other at the molecular level to form (h...

OBJECTIVE In chronic atrial fibrillation (cAF) the potassium current IK,ACh develops agonist-independent constitutive activity. We hypothesized that abnormal phosphorylation-dependent regulation underlies the constitutive IK,ACh activity. METHODS We used voltage-clamp technique and biochemical assays to study IK,ACh regulation in atrial appendages from 61 sinus rhythm (SR), 11 paroxysmal AF (...

Muscarinic cholinergic receptors modulate dopaminergic function in brain pathways thought to mediate cocaine's abuse-related effects. Here, we sought to confirm and extend in the mouse species findings that nonselective muscarinic receptor antagonists can enhance cocaine's discriminative stimulus. More importantly, we tested the hypothesis that muscarinic receptor agonists with varied receptor ...

Muscarinic cholinergic receptors modulate dopaminergic function in brain pathways thought to mediate cocaine’s abuse-related effects. Here we sought to confirm and extend in the mouse species findings that nonselective muscarinic receptor antagonists can enhance cocaine’s discriminative stimulus. More importantly, we tested the hypothesis that muscarinic receptor agonists with varied receptor s...