Objective: To explore the direct contribution of dexamethasone (Dex) for insulin resistance inducing in thecal cells and effects of berberine (Ber) and puerarin (Pue).
Methods: Ovarian thecal cells from porcine follicles were isolated and cultured in vitro. Insulin resistance of thecal cells was induced by Dex treatment for 48 h. Then the glucose utilization ratio of thecal cells was detected. Meanwhile, the effects of Ber and Pue on insulin signal transmission and steroid hormones synthesis were determined by RT-PCR and Western blotting.
Results: (1) After being treated by Dex for 48 h, the [3-3H] -glucose uptake in cells was lowered by about half, and the glucose content in supernate increased for about 1/3. (2) The RT-PCR and Western blotting showed that levels of insulin receptor substrate-1 (IRS-1), mRNA and protein expression of glucose transporter 4 (GLUT4) lowered, peroxisome proliferator-activated receptor -gamma(PPARgamma) and cytochrome P450 17 hydroxylase (CYP17) mRNA or protein expression increased in the model cells. However, the changes of above insulin signal molecules and CYP17 expression were inversed significantly after treated with Ber and Pue for 48 h. (3) As compared with the control, in the model cells, levels of testosterone (T, microg/mL) was higher (0.82 +/- 0.20 vs 0.38 +/- 0.01, P < 0.05), while after Ber and Pue treatment it was 0.44 +/- 0.24 and 0.45 +/- 0.21 respectively, all lower than that in the model cells (P < 0.05). No significant change of serum progesterone was found in all groups (P > 0.05).
Conclusions: After insulin resistance has been induced, the androgen synthetic capacity of thecal cells enhanced significantly. Ber and Pue could lower the degree of insulin resistance and the androgen synthesis in the model cells, displaying the favorable prospect of the two insulin sensitizing agents for the treatment of polycystic syndrome.