DECREASED TURNOVER IN CENTRAL 5-HT NERVE TERMINALS INDUCED BY ANTIDEPRESSANT DRUGS OF IMIPRAMINE TYPE

High doses of chlorimipramine and amitriptyline, potent blockers of the membrane pump in the 5-HT neurons, were found to cause a small but significant retardation of the α-propyldopacetamide-induced amine depletion in the central 5-HT nerve terminals of rats. This decrease of amine turnover in the 5-HT nerve terminals indicates that there may be a decreased activity in the central 5-HT neurons after treatment with high doses of these drugs. It is proposed that this decreased activity is the result of a nervous feed-back onto the 5-HT cell bodies initiated by the increased 5-HT receptor activity caused by the increasing amounts of 5-HT leaking out over the cell membrane due to blockade of the membrane pump. Nortriptyline, however, which blocks predominantly the uptake of noradrenaline, did not show a similar accelerating effect on 5-HT depletion. © 1969.