title: Seasonal plasma and intraovarian sex steroid profiles, and influence of temperature on gonadotropin stimulation of in vitro estradiol-17 beta and progesterone production, in Rana esculenta (Amphibia: Anura).
abstract: Seasonal plasma and intraovarian estradiol-17 beta (E) and progesterone (P) fluctuations were studied by specific radioimmunoassay in the frog, Rana esculenta. Moreover, incubations of ovine-luteinizing hormone (oLH)-stimulated ovarian pieces at two different temperatures (15 and 24 degrees) have been carried out in order to evaluate the dependence of E and P output on this exogenous factor. Estradiol showed similar changes in plasma and ovaries, while P profile was better evidenced in the gonads since this hormone fluctuated in plasma, giving pulses of difficult interpretation. A shift from E to P production by the ovary near the ovulatory period (February-March) was noted. In vitro experiments were carried out using approximately equal-sized ovarian fragments containing follicles ranging from 0.7 to 1 mm and classified as early vitellogenic. High temperature induced oLH-stimulated P production within 6 h, while E increased after 24 h concomitantly with a P decline. At 15 degrees the stimulatory effect of oLH was achieved only on E output in the incubation medium after 24 h. In conclusion, our results in the frog, R. esculenta, show that E and P intervene at peak values separately during the annual cycle and that the temperature has an important role in the regulation of the steroid hormone-releasing activity.
mesh_terms: D000818:Animals; D004958:Estradiol / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000494:pharmacology*; D010053:Ovary / Q000378:metabolism*; D011374:Progesterone / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D011863:Radioimmunoassay; D011893:Rana esculenta / Q000378:metabolism*; D012621:Seasons; D013696:Temperature
chemical_list: D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone