Nitric oxide (NO) stimulates steroidogenesis and folliculogenesis in fish.
The present study was undertaken to understand the physiological significance of the existence of nitric oxide synthase (NOS)/nitric oxide (NO) system in fish ovary. For this, two doses of NO donor, sodium nitroprusside (SNP, 25 µg and 50 µg) and NOS inhibitor, N-nitro-l-arginine methyl ester (l-NAME, 50 µg and 100 µg)/100 g body weight were administered during the two reproductive phases of reproductive cycle of the Clarias batrachus During the late-quiescence phase, high dose of l-NAME decreased the NO, testosterone, 17β-estradiol, vitellogenin contents in serum and ovary and activities of 5-ene-3β-hydroxysteroid dehydrogenases (3β-HSD) and 17β-hydroxysteroid dehydrogenases (17β-HSD) in ovary, whereas higher dose of SNP increased these parameters. l-NAME also reduced oocytes-I but increased perinucleolar oocytes in the ovary, whereas SNP treatment increased the number of advanced oocytes (oocytes-I and II) than the perinucleolar oocytes when compared with control ovary. During the mid-recrudescence phase, both doses of SNP increased NO, testosterone, 17β-estradiol and vitellogenin in serum and ovary; however, l-NAME treatment lowered their levels. The activities of ovarian 3β-HSD and 17β-HSD were also stimulated by SNP, but l-NAME suppressed their activities compared to the control. The SNP-treated ovaries were dominated by oocyte-II and III stages, whereas l-NAME-treated ovary revealed more perinucleolar oocytes and oocytes-I and practically no advanced oocytes. Expression of endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS) was augmented by the SNP and declined by l-NAME treatments as compared to the control. This study, thus, provides distinct evidence of NO-stimulated steroidogenesis, vitellogenesis and folliculogenesis in fish.
Department of ZoologyFish Endocrinology Laboratory, Institute of Science, Banaras Hindu University, Varanasi, India.
Vinay Kumar
VK
Singh
Department of ZoologyFish Endocrinology Laboratory, Institute of Science, Banaras Hindu University, Varanasi, India lalbhu@yahoo.co.in.
Bechan
B
Lal
D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D000818:Animals; D004791:Enzyme Inhibitors; D004958:Estradiol / Q000032:analysis / Q000097:blood; D005260:Female; D005399:Fishes / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology; D009599:Nitroprusside / Q000494:pharmacology; D009865:Oocytes / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D006080:Ovarian Follicle / Q000254:growth & development*; D010053:Ovary / Q000201:enzymology / Q000502:physiology; D013256:Steroids / Q000096:biosynthesis*; D013739:Testosterone / Q000032:analysis / Q000097:blood; D014819:Vitellogenins / Q000032:analysis / Q000097:blood
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D013256:Steroids; D014819:Vitellogenins; D009599:Nitroprusside; D009569:Nitric Oxide; D013739:Testosterone; D004958:Estradiol; D015067:17-Hydroxysteroid Dehydrogenases; D015096:3-Hydroxysteroid Dehydrogenases; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester