title: [Repeated gonadotropin stimulations lower the developmental potential of mouse oocytes].
abstract: OBJECTIVE
  To assess the effect of repeated gonadotropic stimulations on the developmental potential and growth differentiation factor-9 (GDF-9) expression of mouse oocytes.
  
  
  METHODS
  Female Kunming mice were treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) for 3 times, and the control mice were treated with normal saline. The two groups of mice were both stimulated subsequently to obtain the mature oocytes. Immunocytochemical staining was employed to evaluate GDF-9 expression in the oocytes. The oocytes were then inseminated and cultured till the formation of blastocysts to compare the cleavage rate and blastocyst formation rate between the groups.
  
  
  RESULTS
  A total of 253 mature oocytes were obtained in the repeated stimulation group, with a mean of 11.5 oocytes from each mouse; 521 mature oocytes were obtained in the control group with a significantly greater mean number of 32.6 from each mouse (P<0.05). The average optical density and integrated optical density for GDF-9 expression were significantly lower in the oocytes in repeated stimulation group than in the control group (P<0.05 and 0.01, respectively). After insemination, the cleavage rate were comparable between repeated stimulation group and the control group (85.6% vs 88.8%), but the blastocyst formation rate was significantly lower in repeated stimulation group (20.8% vs 35.2%, P<0.01).
  
  
  CONCLUSIONS
  Repeated gonadal stimulation decreases the developmental potential of mouse oocytes possibly due to reduced GDF-9 expression.
authors.affiliation: Department of Gynecology and Obstetrics, Wuhan General Hospital of Guangzhou Command, Wuhan, China. pyhlucy@yahoo.com.cn
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Peng
authors.forename: Shou-Zhen
authors.initials: SZ
authors.lastname: Xie
authors.forename: Xiao-Kun
authors.initials: XK
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Diao
authors.forename: Meng-Lin
authors.initials: ML
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D006062:Gonadotropins / Q000494:pharmacology*; D055429:Growth Differentiation Factor 9 / Q000378:metabolism*; D051379:Mice; D009865:Oocytes / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D010062:Ovulation Induction / Q000009:adverse effects / Q000379:methods*
chemical_list: C525898:Gdf9 protein, mouse; D006062:Gonadotropins; D055429:Growth Differentiation Factor 9