The effects of serotonin (5-hydroxytryptamine; 5-HT) on vasopressin (VP) and oxytocin
(OT) secretion were studied in 13-14-day cultures of isolated rat neurohypophyseal
(NH) tissue. The VP and OT contents of the supernatant were determined by radioimmunassay
after a 1 or 2 h incubation. Significantly increased levels of VP and OT production
were detected in the tissue culture media following 5-HT administration, depending
on the 5-HT dose. The elevation of NTH hormone secretion could be partially blocked
by previous administration of the 5-HT antagonist ketanserin or metergoline. WAY-100635
did not influence the increased VP secretion induced by 5-HT, but the elevated OT
production was prevented by WAY-100635 before 5-HT administration. The application
of WAY-100635, ketanserin or metergoline, after 5-HT administration proved ineffective.
The results indicate that NH hormone release is influenced directly by the serotonergic
system. The serotonergic control of VP and OT secretion from the NH tissue in rats
can occur at the level of the posterior pituitary. (C) 2004 Elsevier B.V. All rights
reserved.
