Morphine differentially alters synthesis and turnover of dopamine in central neuronal systems.
On the basis of biochemical indices of dopamine (DA) nerve activity (decline of DA after inhibition of tyrosine hydroxylase, accumulation of DOPA after inhibition of DOPA decarboxylase) it was revealed that morphine increases the activity of nigrostriatal and mesolimbic DA nerves which terminate in the striatum, nucleus accumbens and olfactory tubercle, but reduce the activity of tuberoinfundibular DA nerves which terminate in the median eminence. Morphine had no effect on tuberohypophyseal DA nerves which project to the posterior pituitary. Naloxone was without effect per se, but blocked the effects of morphine on DOPA accumulation. Thus, morphine differentially alters the diverse DA neuronal systems in the rat brain.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004298:Dopamine / Q000096:biosynthesis*; D008032:Limbic System / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008473:Median Eminence / Q000187:drug effects / Q000378:metabolism; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D010904:Pituitary Gland, Posterior / Q000187:drug effects / Q000378:metabolism; D051381:Rats
D015102:3,4-Dihydroxyphenylacetic Acid; D009270:Naloxone; D004295:Dihydroxyphenylalanine; D009020:Morphine; D004298:Dopamine