Regulation of inducible nitric oxide synthase expression in bovine ovarian granulosa cells.
Nitric oxide (NO) is a potential regulator of ovarian follicle growth, and ovarian granulosa cells reportedly generate NO in response to gonadotrophins, suggesting that the regulated form of nitric oxide synthase (iNOS) is present. The objectives of the present study were to gain insight into the expression and role of iNOS in the follicle. Messenger RNA encoding iNOS was detected in granulosa cells, and abundance was higher in growing dominant follicles compared to subordinate follicles (P<0.01). FSH (P<0.05) and IGF1 (P<0.01) stimulated oestradiol secretion and iNOS mRNA abundance in granulosa cells in vitro, whereas FGF2 (P<0.05) and EGF (P<0.01) decreased oestradiol secretion and iNOS expression. The addition of an anti-oestrogen prevented FSH-induced iNOS mRNA accumulation. Inhibition of endogenous NO production did not affect steroidogenesis in granulosa cells, but increased FasL mRNA abundance, caspase-3 activation and the incidence of apoptotic cell death (P<0.05). These results demonstrate that iNOS is expressed in ruminant granulosa cells and is regulated by gonadotrophins and oestradiol. Physiological levels of NO may contribute to the survival of granulosa cells.
Laboratório de Biotecnologia e Reprodução Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
Gustavo
G
Zamberlam
Valério
V
Portela
João Francisco C
JF
de Oliveira
Paulo B D
PB
Gonçalves
Christopher A
CA
Price
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001141:Aromatase / Q000235:genetics; D053148:Caspase 3 / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D004789:Enzyme Activation; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology; D053222:Fas Ligand Protein / Q000235:genetics; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D006107:Granulosa Cells / Q000378:metabolism*; D006146:Guanidines / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D006080:Ovarian Follicle / Q000254:growth & development; D014158:Transcription, Genetic
D053222:Fas Ligand Protein; D006146:Guanidines; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D052247:Nitric Oxide Synthase Type II; D001141:Aromatase; D053148:Caspase 3; C004479:pimagedine