Catecholamine metabolism in the vas deferens and the adrenal gland with special reference to the central catecholamine-depleted state

Experiments were carried out to elucidate the role of central catecholamines in regulating catecholamine metabolism in the vas deferens and adrenal gland of the rat. Rats were injected intracerebroventricularly (i.c.v.) with either vehicle or 6-hydroxydopamine (6-OHDA). Groups of animals pretreated with vehicle or 6-OHDA (i.c.v.) were injected intraperitoneally (i.p.) with alpha-methyl-para-tyrosine (AMT), a tyrosine hydroxylase inhibitor. Catecholamine turnover rates were estimated by determining norepinephrine or epinephrine content after administrating AMT.Central norepinephrine and dopamine contents decreased significantly (p<0.05) after treatment with 6-OHDA and AMT. The norepinephrine content of the vas deferens of rats pretreated with 6-OHDA was markedly reduced (p<0.001) after administration of AMT, whereas that of the vehicle-treated rats remained unchanged. Administration of 6-OHDA had no effect on the norepinephrine or epinephrine content of the adrenal gland.The present results indicate that central monoaminergic neurons have an inhibitory effect on the adrenergic neurons of the vas deferens. In contrast, this inhibitory regulation does not appear to be exerted on the adrenal glands.