Abstract

LSD-25 in doses of 130 to 1300 µg/kg induced a small and significant rise in levels of rat brain serotonin within 10 to 120 minutes following administration. A single dose was as effective as several daily doses. In reserpine treated animals, LSD-25 induced a 2-fold elevation in brain serotonin, and effects were found 96 hours following a single dose of LSD-25. A dose-effect interaction of LSD-25 and reserpine was evident. Peripheral antiserotonin potency does not correlate with the effect on brain serotonin since the order of potency in elevating brain serotonin following reserpine induced depletion was: LSD-25, ALD-52, and BOL-148.

With high-speed centrifugation the effects of LSD-25 on brain serotonin are largely in the particulate fraction. LSD-25 in vivo or in vitro did not increase the destruction of serotonin or change the net synthesis of serotonin from 2 X 10^-4 M 5-hydroxytryptophan. These findings are interpreted as an effect of LSD-25 on inducing binding of brain serotonin and stimulating the binding of serotonin following reserpine induced depletion.