title: Folic acid facilitates in vitro maturation of mouse and Xenopus laevis oocytes.
abstract: The water-soluble B vitamins, folate and folic acid, play an important role in reproductive health, but little is known about the effects of folic acid on infertility. The present study tested the hypothesis that folic acid affects oocyte maturation, a possible cause of female infertility. We have studied the in vitro maturation of mouse and Xenopus oocytes. Hypoxanthine (Hx) was used as an inhibitor of mouse oocyte maturation to mimic in vivo conditions by maintaining high levels of cyclic-AMP. The frequency of first polar body (PB1) formation and germinal vesicle breakdown (GVBD) in mouse oocytes was decreased by Hx. This effect was counteracted by folic acid added to the medium. PB1 extrusion and GVBD percentages rose to 27·7 and 40·0% from 12·8 and 19·9%, respectively, by exposure to 500 μM-folic acid. Folic acid also restored the spindle configuration, which had been elongated by Hx, as well as normalising the distribution of cortical granules (CG). In folic acid-treated Xenopus eggs, extracellular signal-regulated kinase 1 was phosphorylated, cyclin B2 and Mos were up-regulated and the frequency of GVBD was accelerated. Taken together, the findings suggest that folic acid facilitates oocyte maturation by altering the expression and phosphorylation of proteins involved in M-phase-promoting factor and mitogen-activated protein kinase pathways, as well as causing changes in spindle configuration and CG migration.
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Shandong University, Jinan, People's Republic of China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Huang
authors.forename: Shu
authors.initials: S
authors.lastname: Gao
authors.forename: Wei
authors.initials: W
authors.lastname: Xia
authors.forename: Shaoying
authors.initials: S
authors.lastname: Hou
authors.forename: Kun
authors.initials: K
authors.lastname: Wu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D056765:Cyclin B2 / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005492:Folic Acid / Q000494:pharmacology*; D019271:Hypoxanthine / Q000494:pharmacology; D007247:Infertility, Female / Q000209:etiology / Q000378:metabolism; D016200:Maturation-Promoting Factor / Q000378:metabolism*; D008540:Meiosis / Q000187:drug effects*; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development; D029867:Xenopus Proteins / Q000187:drug effects / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D056765:Cyclin B2; D029867:Xenopus Proteins; D019271:Hypoxanthine; D005492:Folic Acid; D000242:Cyclic AMP; D016200:Maturation-Promoting Factor; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases