Anti-estrogenic suppression of the lordosis response in female rats
Powers, J.B.
Hormones and Behavior 6(4): 379-392
1975
ISSN/ISBN: 0018-506X PMID: 1222939 DOI: 10.1016/0018-506x(75)90005-7Document Number: 505920
The anti-estrogen, Ci 628, was used to suppress the lordosis response induced by sequential injections of estrogen and progesterone in ovariectomized (OVX) female rats. Appropriate doses of Ci 628 completely abolished sexual receptivity in females administered estradiol benzoate (EB) in sesame oil. This behavioral effect could be attenuated by providing increased quantities of Eb or decreased quantities of Ci 628. Anti-estrogenic effects on lordosis induced by free estradiol in saline (E) were assessed after first establishing behaviorally equivalent doses of Eb and E. This was accomplished by determining thresholds for E-induced lordosis. Ovx females were approximately seven times less sensitive to E than to EB. Ci 628 had no significant effects on E-induced lordosis, in contrast to the complete abolition of lordosis in females treated with behaviorally equivalent Eb doses. A possible mechanism to explain this differential responsiveness of EB- and E-treated females is discussed.