Effect of a long-acting estrogen on the pituitary response to LH-releasing hormone (38582)

The effect of Quinestrol, an estrogenic substance of long-lasting activity, on the pituitary responsiveness to LH-RH was studied in ovariectomized rats. Quinestrol administered as a single 200 pg-dose significantly augmented the pituitary response to LH-RH 36 hr, 9 days, and although not significantly, also at 24 days after its oral administration. No effect could be detected 36 days after its administration. At a 20 pg-dose Quinestrol significantly augmented the pituitary response to LH-RH only at the 36 hr-period studied, this effect not being apparent in later time periods.