| Obesity is a major factor for inducing type 2 diabetes(diabetes mellitus,DM).Body mass index value is positively correlated with women's infertility incidence.Additionally,increasing prevalence of type 2 diabetes in women of childbearing age has led to higher incidence of diabetes-associated birth defects,such as neural tube defects(NTDs)and cardiac malformations.Our present study armed to create an effective type 2 diabetes mouse model and embryopathy model to study the effect of type 2 diabetes on ovarian follicular development and embryonic development,and explore the relevant intracellular molecular mechanisms.The results are as follows:1.4 weeks old C57BL/6J female mice were used to build type 2 diabetes mouse model by feeding with high fat diet(HFD,60%fat).After 15 weeks,the mice exhibited-the characteristic of type 2 diabetes,such as insulin resistance,moderately high blood glucose and hyperinsulinemia.2.During studying the effect of DM on ovarian follicular development,we found that DM has adverse effect on ovarian follicular development with time dependent manner.After 20 weeks fed with different diet,most of follicles in DM group mice arrested at early stages or completely atresiaed.Then,we explored the molecular mechanisms under the effect of DM on ovarian follicular development and found that DM improved the activity of Fox03a by reducing the expression level of p-Fox03a,and the activity of Smadl/5/8(downstream signaling molecules of Fox03a)and Akt(upstream signaling molecule of Fox03a)were also significantly affected by DM.In addition,the proliferation and apoptosis level of ovarian granulosa cells(GCs)were also affected by DM,which may explain why many follicles in DM group were atresiaed.3.We created maternal type 2 diabetic embryopathy mouse model by DM female mice mating with normal C57BL/6J male mice.After pregnancy,control dams fed with a normal diet(10%fat)were maintained on either normal diet or on HFD,serving as a control group with elevated free fatty acids.We found that DM dams produced offspring with a rate of NTDs of 11.3%,whereas no embryos in the control groups developed NTDs.Elevated markers of oxidative stress,endoplasmic reticulum stress,caspase activation and neuroepithelial cell apoptosis were observed in embryos from DM dams when comparing with the levels in embryos from control dams.To explore whether treatment of metformin had catabatic effect on maternal type 2 diabetes-induced birth defect,the dams were treated with 200 mg/kg metformin in drinking water,which alleviated type 2 diabetic metabolic phenotype,like hyperglycemia,hyperinsulinemia,glucose intolerance,and insulin resistance,and embryonic cellular stress,apoptosis and NTDs formation.4.During studying the effect of maternal type 2 diabetes on embryonic heart development,we had observed heart defects,like ventricular septal defects(VSDs,9.1%)and persistent truncus arteriosus(PTA)in the embryonic heart from DM dams,while there was no heart defects in embryos from control dams.During studying the molecular mechanisms under maternal type 2 diabetes induced embryonic heart defects,we found that the levels of oxidative stress,endoplasmic reticulum stress and apoptosis in the embryonic hearts from DM dams were significantly up-regulared than those in embryonic hearts from control dams.The results of this study reveal that Akt/FoxO/Smad signaling pathway and abnormal proliferation and apoptosis of GCs are the important molecular mechanisms under the effect of type 2 diabetes on ovarian follicular development.At the same time,it also shows that maternal type 2 diabetes significantly induces NTDs formation and heart defects,and cellular stress and excessive cell apoptosis are the important mechanisms of them.These findings may provide part of theoretical basis for clinical prevention and treatment of type 2 diabetes caused-women infertility and fetal malformation. |
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