Central galanin stimulates pituitary prolactin secretion in rats: possible involvement of hypothalamic vasoactive intestinal polypeptide.
The effect of galanin, a newly identified neuropeptide, on pituitary prolactin (PRL) secretion was examined in the rat. Intracerebroventricular (i.c.v.) injection of all 5 doses of galanin (0.4, 1, 2, 5 and 10 micrograms/rat) raised plasma PRL levels in urethane-anesthetized rats. Galanin injection (2 micrograms/rat, i.c.v.) also increased plasma PRL levels in conscious rats. The intermediate dose of galanin (2 micrograms/rat, i.c.v.) produced a greater response in plasma PRL levels than either smaller or larger doses of galanin. Intravenous injection of galanin did not affect plasma PRL levels. Passive immunization with specific anti-vasoactive intestinal polypeptide (VIP) rabbit serum suppressed plasma PRL response to galanin (2 micrograms/rat, i.c.v.) in anesthetized rats. These findings indicate that central galanin has a stimulatory role in pituitary PRL secretion via the hypothalamus in the rat and that VIP may be involved in rat PRL release induced by galanin.
D000818:Animals; D019004:Galanin; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology; D007276:Injections, Intraventricular; D008297:Male; D010455:Peptides / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014660:Vasoactive Intestinal Peptide / Q000502:physiology*
D010455:Peptides; D014660:Vasoactive Intestinal Peptide; D019004:Galanin; D011388:Prolactin