title: Changes in plasma steroid levels during oocyte development in Indian shad, Tenualosa ilisha (Hamilton, 1822): role of gonadotropins on in vitro steroid production and development of oocyte maturational competence.
abstract: Circanual variations in plasma testosterone (T), 17-estradiol (E2), and 17,20-dihydroxy-4-pregnen-3-one (17,20-P) levels and ovarian steroid synthetic potential of Tenualosa ilisha of river Hooghly, West Bengal, India were examined. This fish exhibited bi-annual spawning; one during April-May and another during August-September. Coinciding with the GSI values, present study recorded a decline in plasma T and E2 levels from October, reaching their lowest values in January followed by a rapid rise in March when the ovary contained mostly vitellogenic follicles and remained high up to April (postvitellogenic stage). Plasma 17,20β-P level was detected in March and reached peak value in April during oocyte maturation. After spawning, all the steroid levels declined to reach lowest values in June. From June onwards, T and E2 levels again increased for the next cycle and peaked at the end of vitellogenesis. Plasma 17,20β-P was reappeared in August and reached maximum in September during oocyte maturation and spawning. Of the two gonadotropins tested, in vitro production of both T and E2 by the vitellogenic and postvitellogenic follicles was regulated by FSH and LH respectively. Production of 17,20-P by the post-vitellogenic follicles was regulated by LH only. Acquisition of in vitro oocyte maturational competence (OMC) was developed by the addition of HCG in culture medium. Treatment of a 3β-HSD inhibitor blocked LH-induced steroid production, but not development of OMC. Both Cycloheximide and actinomycin D inhibited LH-induced development of OMC, indicating the requirement of de novo protein synthesis for this process.
authors.affiliation: Department of Zoology, Presidency University, 86/1 College Street, Kolkata 73, India. Electronic address: kousikzoology@presiuniv.ac.in.
authors.forename: Kousik
authors.initials: K
authors.lastname: Pramanick
authors.forename: Sourav
authors.initials: S
authors.lastname: Kundu
authors.forename: Sudipta
authors.initials: S
authors.lastname: Paul
authors.forename: Buddhadev
authors.initials: B
authors.lastname: Mallick
authors.forename: Sujata Roy
authors.initials: SR
authors.lastname: Moulik
authors.forename: Puja
authors.initials: P
authors.lastname: Pal
authors.forename: Dilip
authors.initials: D
authors.lastname: Mukherjee
mesh_terms: D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005399:Fishes / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D009865:Oocytes / Q000502:physiology*; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012621:Seasons; D013256:Steroids / Q000096:biosynthesis*; D013997:Time Factors
chemical_list: D011500:Protein Synthesis Inhibitors; D013256:Steroids; D003609:Dactinomycin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D003513:Cycloheximide
keywords: Gonadotropins; Oocyte maturation; Ovarian steroidogenesis; Plasma steroids; Tenualosa ilisha