Effects of dopamine and dopamine-active compounds on oxytocin and vasopressin production in rat neurohypophyseal tissue cultures

The effects of dopamine (DA) or DA-active drugs on the synthesis of neurohy pophyseal (NH) hormones were studied in 13-14 day cultures of isolated NH t issue from rats. The following DA-active compounds were used (10(-6) M in e ach medium): DA, apomorphine (APM), Pro-Lys-Gly (PLG), butaclamol (B), halo peridol (HP), chlorpromazine (CPZ) and sulpiride (SP). The oxytocin (OT) an d vasopressin (VP) contents of the condensed media were determined by RIA a fter a 1 or 2 h incubation. Significantly increased contents of OT and VP w ere detected in the tissue culture media following DA, APM or PLG administr ation. This elevation of NH hormone production could be blocked by previous administration of B or the DA receptor antagonists HP, CPZ or SP. The appl ication of B after DA agonists proved ineffective. The results indicate tha t NH hormone production can be directly influenced by the DA-ergic system. The DA-ergic control of NH hormone secretion in rats can occur independentl y of the hypothalamus, at the level of the posterior pituitary. (C) 2001 El sevier Science B.V. All rights reserved.