Involvement of central muscarinic cholinergic mechanisms in opioid stress analgesia.
Stress has been shown capable of differentially activating opioid- and non-opioid-mediated endogenous analgesia systems. In this study, the muscarinic cholinergic antagonist, scopolamine, but not the centrally inactive methylscopolamine, blocks opioid, but not non-opioid stress analgesia. Additionally, naltrexone, an opiate antagonist, attenuates analgesia induced by oxotremorine, a cholinergic agonist. These findings support the existence of a muscarinic cholinergic synapse in a central nervous system opioid pain-inhibitory pathway.
D000818:Animals; D004597:Electroshock; D004723:Endorphins / Q000502:physiology*; D008297:Male; D009020:Morphine; D009271:Naltrexone; D010095:Oxotremorine; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology*; D012601:Scopolamine; D013312:Stress, Physiological / Q000503:physiopathology*
D004723:Endorphins; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D010095:Oxotremorine; D009271:Naltrexone; D009020:Morphine; D012601:Scopolamine