Effect of morphine on catecholamine - stimulated cyclic AMP production in cortex slices from rats and mice.
Morphine (10 micro M) blocked noradrenaline-stimulated cyclic AMP production in slices of cerebral cortex from normal rats but not in slices from rats pretreated with 6-hydroxydopamine (6-OHDA). In contrast, morphine failed to prevent noradrenaline-stimulated cyclic AMP production in mouse cortex slices. Levorphanol weakly antagonized the rise in cyclic AMP produced by noradrenaline in both normal and 6-OHDA-treated mouse cortex. Morphine had no effect on the adrenaline-stimulated cyclic AMP accumulation in mouse cortex but it entirely prevented the rise in cyclic AMP produced by isoprenaline. This effect was no observed in brain slices from 6-OHDA-treated mice. It is concluded that in slices of rat cortex, morphine stimulates postulated presynaptic, 6-OHDA-sensitive, opiate receptors associated with noradrenergic nerve terminals. These opiate receptors alter postsynaptic alpha - and beta - adrenoceptor activity. In the mouse, morphine appears to stimulate presynaptic opiate receptors that modify exclusively beta - adrenoceptor-mediated cyclic AMP production.
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis*; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology; D007981:Levorphanol / Q000494:pharmacology; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009638:Norepinephrine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains
D006892:Hydroxydopamines; D007981:Levorphanol; D009270:Naloxone; D009020:Morphine; D016627:Oxidopamine; D000242:Cyclic AMP; D009638:Norepinephrine