| Abstract: | Changes in concentration of serum luteinizing hormone (LH) and follicle stimulating hormone (FSH) associated with estrogen-advanced ovulation in 4-day cyclic rats were determined. 50 mcg of estradiol benzoate was administered sc on the 1st day of diestrus and LH and FSH were determined by radioimmunoassay 24, 29, and 47 hours postinjection. 48 hours postinjection, ovulation was determined by the presence of ova in the oviduct. Estradiol benzoate caused a significant (p less than .01) increase in serum LH after 24 and 29 hours and a drastic decrease after 47 hours postinjection. FSH increased (p less than .05) after 29 hours postinjection. These results suggest that an ovulatory gonadotropin surge occurs 24 hours ahead of schedule in estradiol-benzoate-treated rats. |
