The effect of opioid drugs on the release of dopamine and 5-hydroxytryptamine from rat striatum following activation of nicotinic-cholinergic receptors.
The effect of (Met5)enkephalin, (D-Ala2,D-Met5)enkephalin, (Leu5)enkephalin, (D-Ala2,D-Met5)enkephalin and morphine on the release of [3H]dopamine, endogenous dopamine and [3H]5-hydroxytryptamine produced by the nicotinic-cholinergic agonist, dimethylphenyl piperazinium iodide (DMPP), was examined in rat striatal slices. The DMPP-induced release of [3H]dopamine and endogenous dopamine was reduced by the presence of (Met5)enkephalin, (D-Ala2,D-Met5)enkephalin (1-10 microM) or morphine (10 microM) but not by (Leu5)enkephalin or (D-Ala2,D-Leu5)enkephalin. The DMPP-induced release of [3H]5-hydroxytryptamine was reduced by (Leu5)enkephalin, (D-Ala2,D-Leu5)enkephalin, (Met5)enkephalin, (D-Ala2,D-Leu5)enkephalin (1-10 microM), and morphine (10 microM). All three opioids failed to alter the release of [3H]dopamine induced by field stimulation or potassium depolarization (30 microM). The inhibitory effects of opioid peptides and morphine demonstrated in the present study appear to be due to an initial interaction with nicotinic-cholinergic receptors in the striatum.
D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004745:Enkephalins / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011978:Receptors, Nicotinic / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism*
D004745:Enkephalins; D011978:Receptors, Nicotinic; D012701:Serotonin; D004246:Dimethylphenylpiperazinium Iodide; D009020:Morphine; D011188:Potassium; D004298:Dopamine