Lewis J W, Cannon J T, Liebeskind J C
Brain Res. 1983 Jul 4;270(2):289-93. doi: 10.1016/0006-8993(83)90603-0.
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.
