['The medullary hypoglossal nucleus (XII) innervates the genioglossal muscles of the tongue, and opioid-induced alterations in tongue muscle tone contribute to airway obstruction. Previous studies have shown that morphine causes a significant decrease in acetylcholine (ACh) release in some brain regions, but the effects of morphine on ACh release in XII have not been quantified.', "A within-subjects design was used to test the hypothesis that morphine alters ACh release in XII of anesthetized Wistar rat. ACh release during microdialysis with Ringer's solution (control) was compared to ACh release during dialysis delivery of opioids.", 'University of Michigan.', 'N/A.', 'Microdialysis delivery of opioids to XII.', 'Morphine caused a statistically significant, concentration-dependent increase in XII ACh release. The increase in XII ACh release caused by 10 microM morphine was blocked by the mu opioid antagonist naloxone and not blocked by the kappa opioid antagonist norbinaltorphimine.'] Does microdialysis delivery of morphine to the hypoglossal nucleus of Wistar rat increase hypoglossal acetylcholine release?