Delta-9-tetrahydrocannabinol and lysergic acid diethylamide: comparative changes in the supraoptic and paraventricular neurosecretory activities in rat hypothalamus.

Acute delta-9-tetrahydrocannabinol (Delta-9-THC) administration (50 mg/kg, i.p.) produced accumulation of stainable neurosecretory materials (NSM) in the neural lobe (NL) region with a concomitant dispersion of stainable NSM in the neuronal perikarya of hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) regions. Chronic treatment with delta-9-THC (10 mg/kg, 15 days) produced marked accumulation of NSM in the NL with more prominent degranulation of the neuronal perikarya of SON and PVN. Acute LSD treatment (50 mug/kg) caused accumulation of stainable NSM in the NL region, with unaltered perikaryal distribution pattern of both SON and PVN; chronic LSD treatment (10 mug/kg, 15 days), on the other hand, caused marked increase of NSM in the neuronal perikarya of SON and PVN with no prominent accumulation in the NL. Results indicated that chronic exposure of delta-9-THC lowered the functional activity of SON and PVN neurons while chronic LSD treatment stimulated the hypothalamo-neurohypophyseal neurosecretory system of rats.