Gonadotrophin-induced oocyte maturation in the catfish, Heteropneustes fossilis (Bloch), requires steroidogenesis in both interrenal and ovary.
Intact or hypophysectomized catfish, Heteropneustes fossilis, were administered a single injection of ovulating doses of ovine luteinizing hormone (LH: 200 micrograms/100 g body wt) or partially-purified salmon gonadotrophin (SG-G100: 100 micrograms/100 g body wt). Identical groups of catfish were injected with a suboptimal dose of LH (20 micrograms/100 g body wt) or with porcine adrenocorticotrophin (ACTH: 0.25 IU/100 g body wt). At short intervals after hormone administration, plasma and/or ovarian tissue were analyzed for cortisol (F), testosterone (T), and estradiol-17 beta (E2) by radioimmunoassay. Following administration of ovulatory doses of gonadotrophins, plasma levels of the three steroids increased in a sequential manner; high levels were recorded between 15 and 45 min for F and between 45 and 90 min for T and E2. In gonadotrophin-injected catfish, the ovarian content of T and E2 increased during the first 45 min and then declined up to 90 min even as their titers in the plasma were still increasing. When ovarian pieces containing yolky oocytes were incubated in vitro with LH (50 micrograms/ml), levels of T and E2 in the culture medium increased in a sequential manner similar to that observed following in vivo administration of gonadotrophin. No significant change was observed in the levels of any of the three steroids in catfish injected with a suboptimal dose of LH. In catfish treated with ACTH, plasma F levels increased 40-fold, whereas T and E2 levels did not change; ACTH administration had no effect on oocyte maturation. These results suggest that gonadotrophin, at doses sufficient to evoke oocyte maturation, acts at two loci, the interrenal and the ovary. The results also suggest that the failure of ACTH to induce oocyte maturation is due to its inability to act on the ovary.
Goswami
S V
SV
Lamba
V J
VJ
Sundararaj
B I
BI
D000311:Adrenal Glands / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D005399:Fishes / Q000502:physiology*; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis*; D006062:Gonadotropins / Q000494:pharmacology*; D006854:Hydrocortisone / Q000096:biosynthesis; D007016:Hypophysectomy; D007401:Interrenal Gland / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000254:growth & development*; D010053:Ovary / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis
D012739:Gonadal Steroid Hormones; D006062:Gonadotropins; C016844:salmon gonadotropin; D013739:Testosterone; D004958:Estradiol; D000324:Adrenocorticotropic Hormone; D007986:Luteinizing Hormone; D006854:Hydrocortisone