Stimulation of rat prolactin secretion in vivo by arginine vasotocin: influence of age of solution, nighttime administration, and dose.
In male rats pretreated for 3 days with 50 microgram of estradiol benzoate (E) and 25 mg of progesterone (P), the i.v. administration of 1 microgram of arginine vasotocin (AVT) from solutions that were 0, 6, 24 or 48 h old caused a significant rise in plasma prolactin (Prl) 10 min after injection. In the 2nd experiment, the i.v. injection of 1 microgram AVT into EP-primed adult male rats at either 01:00 (during darkness) or 13:00 h (during light) resulted in a significant and similar elevation in plasma Prl levels. In the 3rd experiment, normal adult male rats under urethane anaesthesia were given an i.v. injection of diluent or of 100 ng, 1 microgram or 10 microgram AVT. A significant rise in plasma Prl was observed at 10 and 20 min following injection only in the group treated with 1 microgram AVT. In none of these experiments did AVT alter the content of pituitary Prl.
D000818:Animals; D002940:Circadian Rhythm; D004958:Estradiol / Q000494:pharmacology; D007275:Injections, Intravenous; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D051381:Rats; D013268:Stimulation, Chemical; D014668:Vasotocin / Q000008:administration & dosage / Q000494:pharmacology*
D011374:Progesterone; D004958:Estradiol; D011388:Prolactin; D014668:Vasotocin