The effects of intracarotid (i.a.) administration of the histamine (HA) H3-receptor agonist (R)-α-methyl-histamine (αMeHA) and of the H3-antagonist thioperamide, (THIO) on basal or morphine (M)-induced prolactin (PRL) and growth hormone (GH) secretion were studied in male rats. M was administered 3 h after the H3-drugs. Neither THIO (2.5 mg/kg) nor αMeHA (10 mg/kg) changed basal PRL levels and only THIO enhanced the PRL-releasing effect of M (6 mg/kg). Basal GH secretion was not modified by THIO. αMeHA slightly increased GH secretion. THIO significantly decreased M-stimulated GH secretion (1 mg/kg, i.a.) and αMeHA slightly increased it. These results, in agreement with previous evidence obtained after central HA administration, indicate that endogenous brain HA facilitates PRL and inhibits GH secretion.
ASJC Scopus subject areas
- Pharmacology (medical)