Effects of cyclic steroid hormone replacement on prolactin and luteinizing hormone surges in female rats.
The ability of steroid hormones to produce an LH or prolactin (PRL) surge was determined in rats ovariectomized at 6, 9 or 13 weeks of age and subjected to one, three or six cycles of estrogen and progesterone replacement. Sensitivity to steroid replacement was dependent on the age of the animal at the time of ovariectomy. Repeated cyclic steroid hormone replacement significantly increased the magnitude of the PRL response, but not the LH response, in animals ovariectomized at 6 weeks. The LH response was significantly altered by cyclic steroid replacement only in animals ovariectomized at 13 weeks. These results indicate that the mechanisms involved in the regulation of PRL secretion are influenced by steroid hormone replacement and that cyclic steroid hormone exposure increases the magnitude of the PRL secretory response.
Brown
A M
AM
Center for Neuroscience, Department of Zoology, Miami University, Oxford, OH 45056, USA.
Janik
J M
JM
Murphree
E S
ES
King
R
R
Callahan
P
P
D000367:Age Factors; D000818:Animals; D004334:Drug Administration Schedule; D015914:Estrogen Replacement Therapy; D005260:Female; D020249:Hormone Replacement Therapy; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D011374:Progesterone / Q000008:administration & dosage; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D014599:Uterus / Q000033:anatomy & histology
D011374:Progesterone; D011388:Prolactin; D007986:Luteinizing Hormone