Expression of PGC-1ɑ in Ovarian Tissue of PCOS Rat Model

  Objective  To investigate the expression of peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) in the ovarian tissue of polycystic ovary syndrome (PCOS) rat model and obese PCOS rat model, and the possible mechanism of PCOS.

  Methods  Thirty SD rats were randomly divided into control group, PCOS rat model group and obese PCOS rat model group. DHEA dissolved in 0.2 mL soybean oil was injected daily into the rats of two PCOS groups for 21 d. Rats in obese PCOS model group were added with high-fat diet based on DHEA modeling, and each group had 10 rats. Body mass were measured before and on the 22^nd day after modeling. The serum testosterone (T) levels were measured by abdominal aortic blood, and the ovarian tissues of rats were taken for histological changes were observed by HE staining, immunohistochemical staining and Western blot to detect PGC-1ɑ protein expression.

  Results  The body mass of rats in each group increased after modeling, and the body mass of rats in PCOS group and obese PCOS group increased significantly (P<0.05). The serum T concentration of two PCOS model groups was higher than that of control group (P<0.01). The serum T concentration in obese PCOS model group was higher than that in the PCOS group (P<0.05). The results of HE staining of rat ovarian tissue showed that there were follicles and a small amount of corpus luteum at different developmental stages in the control group, and the granulosa cells were arranged in 4-6 layers. The number of immature small follicles in the two PCOS groups was significantly increased. The granulosa cells were arranged in 1-3 layers, relatively looser, and some follicles were atresia. In the obese PCOS group, the diameter of ovarian atretic follicles increased, the number of granulocyte layers decreased, and oocytes disappeared more obviously. Immunohistochemical staining showed that the PGC-1ɑ protein was mainly expressed in the cumulus and granulosa cells of ovarian tissue in the control group. The mean gray level of PGC-1ɑ protein expression in PCOS group (0.53±0.06) and obese PCOS group (0.36±0.03) was lower than that of the control group (0.75±0.03), with the statistical difference (P<0.05). PGC-1ɑ expression in the obese PCOS group was lower than that in the PCOS group (P<0.01). The results of Western blot were consistent with those of immunohistochemical staining.

  Conclusion  PGC-1ɑ is associated with damage of ovarian granulosa cells in high-fat environment. The decrease of PGC-1ɑ expression in granulosa cells of ovarian follicles may be an important cause of PCOS development.