title: Effects of metformin on bovine granulosa cells steroidogenesis: possible involvement of adenosine 5' monophosphate-activated protein kinase (AMPK).
abstract: In mammals, IGFs are important for the proliferation and steroidogenesis of ovarian cells. Metformin is an insulin sensitizer molecule used for the treatment of the infertility of women with polycystic ovary syndrome. It is, however, unclear whether metformin acts on ovarian cells. Adenosine 5' monophosphate-activated protein kinase (AMPK) is involved in metformin action in various cell types. We investigated the effects of metformin on bovine granulosa cell steroidogenesis in response to IGF1 and FSH, and studied AMPK in bovine ovaries. In granulosa cells from small follicles, metformin (10 mM) reduced production of both progesterone and estradiol and decreased the abundance of HSD3B, CYP11A1, and STAR proteins in presence or absence of FSH (10(-8) M) and IGF1 (10(-8) M). In cows, the different subunits of AMPK are expressed in various ovarian cells including granulosa and theca cells, corpus luteum, and oocytes. In bovine granulosa cells from small follicles, metformin, like AICAR (1 mM) a pharmaceutical activator of AMPK, increased phosphorylation of both Thr172 of AMPK alpha and Ser 79 of ACACA (Acetyl-CoA Carboxylase). Both metformin and AICAR treatment reduced progesterone and estradiol secretion in presence or absence of FSH and IGF1. Metformin decreased phosphorylation levels of MAPK3/MAPK1 and MAPK14 in a dose- and time-dependent manner. The adenovirus-mediated production of dominant negative AMPK abolished the effects of metformin on secretion of progesterone and estradiol and on MAPK3/MAPK1 phosphorylation but not on MAPK14 phosphorylation. Thus, in bovine granulosa cells, metformin decreases steroidogenesis and MAPK3/MAPK1 phosphorylation through AMPK activation.
authors.affiliation: Unité de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, 37380 Nouzilly, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Tosca
authors.forename: Christine
authors.initials: C
authors.lastname: Chabrolle
authors.forename: Svetlana
authors.initials: S
authors.lastname: Uzbekova
authors.forename: Joëlle
authors.initials: J
authors.lastname: Dupont
mesh_terms: D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase / Q000187:drug effects / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008687:Metformin / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006080:Ovarian Follicle / Q000187:drug effects; D010053:Ovary / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011374:Progesterone / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012265:Ribonucleotides / Q000494:pharmacology; D015398:Signal Transduction; D013256:Steroids / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D012265:Ribonucleotides; D013256:Steroids; D000620:Aminoimidazole Carboxamide; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D008687:Metformin; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; C031143:AICA ribonucleotide