Bimodal effects of luteinizing hormone and role of androgens in modifying superovulatory responses of rats to infusion with purified porcine follicle-stimulating hormone.
Prepubertal (28-30 days old) female rats were infused s.c. over a 60-h period with a purified porcine pituitary follicle-stimulating hormone (FSH) preparation having FSH specific activity 8.4 times that of NIH-FSH-S1 and luteinizing hormone (LH) specific activity less than 0.005 times that of NIH-LH-S1, based on radioreceptor assays. When the FSH infusion rate of this preparation was increased over the range of 0.5-2 units/day (mg NIH-FSH-S1 equivalent), an all-or-none response was observed, with the threshold dose for superovulation being between 1 and 2 units/day. Eleven of twelve rats receiving the 2 units/day dose ovulated a mean +/- SEM of 67 +/- 8 oocytes on the morning of the third day after the beginning of FSH infusion. Addition of human chorionic gonadotrophin (hCG), as a source of LH activity, to a subthreshold (1 U/day) FSH infusion rate resulted in 20% of rats ovulating at an hCG dosage of 50 mIU/day; increasing the hCG infusion to 200 mIU/day concomitant with the subthreshold FSH infusion rate increased ovulation rate to a mean of 69 +/- 8/rat, with 100% of rats ovulating. To determine the effect of varying both FSH infusion rates and LH:FSH ratios, FSH was infused at several rates, with hCG added to give varying hCG:FSH ratios for each FSH infusion rate. Administration of hCG alone was ineffective in causing ovulation except at the highest infusion rates. Adding hCG to FSH to reach a ratio of 0.2 IU hCG/U FSH significantly increased the superovulatory response to an intermediate, 1 U/day FSH dose, but not to the low, 0.5 U/day dose.(ABSTRACT TRUNCATED AT 250 WORDS)
Armstrong
D T
DT
MRC Group in Reproductive Biology, University of Western Ontario, London, Canada.
Siuda
A
A
Opavsky
M A
MA
Chandrasekhar
Y
Y
D000728:Androgens / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005485:Flutamide / Q000494:pharmacology / Q000031:analogs & derivatives; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D010053:Ovary / Q000187:drug effects / Q000502:physiology; D010060:Ovulation / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013480:Superovulation / Q000187:drug effects*; D013997:Time Factors
D000728:Androgens; D006063:Chorionic Gonadotropin; C014290:hydroxyflutamide; D005485:Flutamide; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone