Objective To establish an animal model of PCOS and to detect the DNA methylation states of LHR, INSR and AR genes. Methods 24-days-old female Sprague-Dawley (SD) rats were randomly divided into two groups. The rats in the experimental group were given subcutaneous implanting of levonorgestrel silica gel staff and injected 1.5 IU hCG twice daily for 9 days from the 4th day. The rats in the control group were injected with normal saline at the same time. Ovarian morphologic changes, sex hormone levels, fasting serum insulin and glucose were detected. The LHR, INSR and AR genes' DNA methylation patterns were checked by methylation specific PCR in modeling group and control group. Results The ovarian weight and volume in modeling group were higher than those in control group. The ovaries in modeling group showed multiple follicular cysts, and the number of theca cells and interstitial cells increased. Less developed follicles and corpus lutea were seem. The serum level of progesterone, testosterone, luteinizing hormone, fasting insulin and glucose were significantly higher in experimental group than those in control group, so as the LH/FSH ratio and HOMA index. No methylation of LHR and AR genes were found in both groups. The methylation frequency of INSR gene (76.7%) was significantly higher in modeling group than that in control group (P<0. 001). Conclusion The depression of INSR gene's transcriptional induced by DNA methylation is important in the development of insulin resistance in PCOS.

Objective To establish an animal model of PCOS and to detect the DNA methylation states of LHR,INSR and AR genes. Methods 24-days-old female Sprague-Dawley (SD) rats were randomly divided into two groups. The rats in the experimental group were given subcutaneous implanting of levonorgestrel silica gel staff and injected 1.5 IU hCG twice daily for 9 days from the 4th day. The rats in the control group were injected with normal saline at the same time. Ovarian morphologic changes,sex hormone levels,fasting serum insulin and glucose were detected. The LHR,INSR and AR genes' DNA methylation patterns were checked by methylation specific PCR in modeling group and control group.Results The ovarian weight and volume in modeling group were higher than those in control group. The ovaries in modeling group showed multiple follicular cysts,and the number of theca cells and interstitial cells increased. Less developed follicles and corpus lutea were seem. The serum level of progesterone,testosterone,luteinizing hormone,fasting insulin and glucose were significantly higher in experimental group than those in control group,so as the LH/FSH ratio and HOMA index. No methylation of LHR and AR genes were found in both groups. The methylation frequency of INSR gene (76.7%) was significantly higher in modelinggroup than that in control group (P

Autophagy plays a crucial role in the maintenance of cellular nutrient balance and the function of organelles such as mitochondria or the endoplasmic reticulum, which are important in intracellular metabolism, insulin release, and insulin sensitivity. In the insulin-producing pancreatic beta-cells, autophagy is important in the maintenance of beta-cell mass, structure, and function. Mice with deficiencies in beta-cell-specific autophagy show reduced beta-cell mass and defects in insulin secretion that lead to hypoinsulinemia and hyperglycemia but not diabetes. However, these mice developed diabetes when bred with ob/ob mice, suggesting that autophagy-deficient beta-cells have defects in dealing with the increased metabolic stress imposed by obesity. These results also imply that autophagy deficiency in beta-cells could be a factor in the progression from obesity to diabetes. Another important function of autophagy is in hypothalamic neurons for the central control of energy expenditure, appetite, and body weight. In addition, mice with autophagy deficiencies in the target tissues of insulin have yielded diverse phenotypes. Taken together, these results suggest that autophagy is important in the control of whole body energy and nutrient homeostasis, and its dysregulation could play a role in the development of metabolic disorders and diabetes.
Animals ; Appetite ; Autophagy ; Body Weight ; Endoplasmic Reticulum ; Energy Metabolism ; Homeostasis ; Hyperglycemia ; Insulin ; Insulin Resistance ; Mice ; Mitochondria ; Neurons ; Obesity ; Organelles ; Phenotype ; Stress, Physiological

Type 2 diabetes mellitus is characterized by insulin resistance and failure of pancreatic beta-cells producing insulin. Autophagy plays a crucial role in cellular homeostasis through degradation and recycling of organelles such as mitochondria or endoplasmic reticulum (ER). Here we discussed the role of beta-cell autophagy in development of diabetes, based on our own studies using mice with beta-cell-specific deletion of Atg7 (autophagy-related 7), an important autophagy gene, and studies by others. beta-cell-specific Atg7-null mice showed reduction in beta-cell mass and pancreatic insulin content. Insulin secretory function ex vivo was also impaired, which might be related to organelle dysfunction associated with autophagy deficiency. As a result, beta-cell-specific Atg7-null mice showed hypoinsulinemia and hyperglycemia. However, diabetes never developed in those mice. Obesity and/or lipid are physiological ER stresses that can precipitate beta-cell dysfunction. Our recent studies showed that beta-cell-specific Atg7-null mice, when bred with ob/ob mice, indeed become diabetic. Thus, autophagy deficiency in beta-cells could be a precipitating factor in the progression from obesity to diabetes due to inappropriate response to obesity-induced ER stress.
Animals ; Autophagy/genetics/*physiology ; Diabetes Mellitus/genetics/*metabolism ; Endoplasmic Reticulum Stress/genetics/*physiology ; Humans ; Insulin-Secreting Cells/*metabolism