Effects of various inhibitors of tyrosine hydroxylase and dopamine beta-hydroxylase on rat self-stimulation after reserpine treatment.
The behavioral effects of low doses of the catecholamine (CA) synthesis inhibitor, alpha-methyl-p-tyrosine (alpha-MPT, 50 mg/kg i.p.), or the norepinephrine (NE) synthesis inhibitors (FLA-63, 15 mg/kg i.p., U-14624, 50 mg/kg i.p., or disulfiram 150 mg/kg i.p.) were studied in rats pretreated with reserpine (1 mg/kg i.p.) 24 h before. Rats were implanted either in the area ventralis tegmenti (AVT) or in the lateral hypothalamus (LH). The modifications of CA synthesis and endogenous CA levels were estimated in a parallel experiment. Reserpine treatment produced a slow decrease in self-stimulation (SS) rates during the first 12 h; SS rates were 85% of control values 24 h after reserpine treatment. Injection of alpha-MPT in reserpine-pretreated rats inhibited SS (85% decrease 3 h after administration either in AVT or LH rats), whereas dopamine beta-hydroxylase inhibition had no great effect on SS. The administration of very low doses of alpha-MPT (20 mg/kg i.p.) to rats treated with reserpine (24 h before) plus FLA-63 (1 h before) induced an important decrease in SS rates in AVT-implanted rats only. The major conclusion is that dopaminergic neurons seem to be involved in AVT and LH SS. The last experiment suggests the involvement of a balance between dopaminergic and noradrenergic neurons in AVT SS.
D000818:Animals; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide / Q000494:pharmacology; D001923:Brain Chemistry / Q000187:drug effects; D004221:Disulfiram / Q000494:pharmacology; D004298:Dopamine / Q000032:analysis / Q000096:biosynthesis; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors*; D004558:Electric Stimulation; D007031:Hypothalamus / Q000502:physiology; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D009638:Norepinephrine / Q000032:analysis / Q000096:biosynthesis; D010668:Phenylthiazolylthiourea / Q000494:pharmacology; D051381:Rats; D012110:Reserpine / Q000494:pharmacology; D012653:Self Stimulation / Q000187:drug effects*; D012701:Serotonin / Q000032:analysis; D013681:Tegmentum Mesencephali / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors*
D008781:Methyltyrosines; D010668:Phenylthiazolylthiourea; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide; D012701:Serotonin; D012110:Reserpine; D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase; D004221:Disulfiram; D004298:Dopamine; D009638:Norepinephrine