Area ventralis tegmenti
Tyrosine hydroxylase inhibition
Dopamine Β-hydroxylase inhibition
Springer Online Journal Archives 1860-2000
Abstract The behavioral effects of low doses of the catecholamine (CA) synthesis inhibitor, α-methyl-p-tyrosine (α-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 α-MPT in reserpine-pretreated rats inhibited SS (85% decrease 3 h after administration either in AVT or LH rats), whereas dopamine Β-hydroxylase inhibition had no great effect on SS. The administration of very low doses of α-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.
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