Relationship between the preovulatory luteinizing hormone (LH) surge and androstenedione synthesis of preantral follicles in the cyclic hamster: detection by in vitro responses to LH.
Preantral follicles of cyclic hamsters were isolated on proestrus, estrus and diestrus I, incubated for 3 h in 1 ml TC-199 containing 1 microgram ovine luteinizing hormone (LH) (NIH-S22), and the concentrations of progesterone (P), androstenedione (A) and estradiol (E2) determined by radioimmunoassay. At 0900-1000 h on proestrus (pre-LH surge) preantral follicles produced 2.4 +/- 0.3 ng A/follicle per 3 h, less than 100 pg E2/follicle and less than 250 pg P/follicle. At the peak of the LH surge (1500-1600 h) preantral follicles produced 1.8 +/- 0.2 ng P and 1.9 +/- 0.1 A and less than 100 pg E2/follicle. After the LH surge (1900-2000 h proestrus and 0900-1000 h estrus) preantral follicles were unable to produce A and E2 but produced 4.0 +/- 1.0 and 5.0 +/- 1.1 ng P/follicle, respectively. By 1500-1600 h estrus, the follicles produced 8.1 +/- 3.1 ng P/follicle but synthesized A (1.6 +/- 0.2 ng/follicle) and E2 (362 +/- 98 pg/follicle). On diestrus 1 (0900-1000 h), the large preantral-early antral follicles produced 1.9 +/- 0.3 ng A, 2.4 +/- 0.4 ng E2 and 0.7 +/- 0.2 ng P/follicle. Thus, there was a shift in steroidogenesis by preantral follicles from A to P coincident with the LH surge; then, a shift from P to A to E2 after the LH surge. The LH/follicle-stimulating hormone (FSH) surges were blocked by administration of 6.5 mg phenobarbital (PB)/100 g BW at 1300 h proestrus. On Day 1 of delay (0900-1000 h) these follicles produced large quantities of A (2.2 +/- 0.2 ng/follicle) and small amounts of E2 (273 +/- 27 pg/follicle) but not P (less than 250 pg/follicle).(ABSTRACT TRUNCATED AT 250 WORDS)
D000735:Androstenedione / Q000096:biosynthesis*; D000818:Animals; D006224:Cricetinae; D004958:Estradiol / Q000096:biosynthesis; D004971:Estrus; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000097:blood* / Q000494:pharmacology; D006080:Ovarian Follicle / Q000378:metabolism*; D010060:Ovulation; D010634:Phenobarbital / Q000494:pharmacology; D011247:Pregnancy; D011374:Progesterone / Q000096:biosynthesis
D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D010634:Phenobarbital