Secretion of prolactin in response to serotonin requires an intact hypothalamo-pituitary axis in the ewe.
The effects on prolactin secretion and the subsequent site of action of serotonin (5-HT) were examined in ovariectomized hypothalamo-pituitary intact (HP-intact) and ovariectomized hypothalamo-pituitary disconnected (HPD) ewes. The administration of 5 mg per animal of 5-HT increased plasma prolactin concentrations within 20 min by two-three fold in HP-intact ewes, but had no effect in HPD ewes. Injection of vehicle (saline) did not alter plasma prolactin concentrations in either group. These data indicate that 5-HT is involved in the control of prolactin secretion in sheep and that this action is exerted at the level of the hypothalamus and not directly at the pituitary gland.
Medical Research Centre, Prince Henry's Hospital, Melbourne, Vic., Australia.
G B
GB
Thomas
J T
JT
Cummins
I J
IJ
Clarke
D000818:Animals; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism*; D007275:Injections, Intravenous; D011388:Prolactin / Q000378:metabolism*; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D012756:Sheep
D012701:Serotonin; D011388:Prolactin