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.
Thomas
G B
GB
Medical Research Centre, Prince Henry's Hospital, Melbourne, Vic., Australia.
Cummins
J T
JT
Clarke
I J
IJ
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