The Influence Of Androgen On The Expression Of Aquaporin-8 In Rat Ovaries

OBJECTIVE:To observe the expressions of aquaporin-8 in the ovaries in androgen-induced polycystic ovary rat models.METHODS:32 SD female rats 9 days old were randomly divided into normal control group (n= 12) and the androgen-induced sterile rat model group (N= 20). The rat model group was injected subcutaneously with testosterone propionate (1.25 mg), and the control group was injected equal amount of tea oil. Vaginal smears were examined daily for 10 consecutive from 70 days of age. At 80 days of age, rats were killed and their ovaries were taken out following formalin fixing. Then the sections were taken for HE staining for tissue morphology observation, and for immunohistochemistry for investigating the position and altered expression of aquaporin-8.RESULTS:In control rats, the gross appearance of ovarian surface was uneven, and the follicles developing at all levels and the corpora lutea were seen under the microscope (the total corpus luteum number of every couple ovaries was 14-51). In model rats, the ovary size was about half of the normal's, and the surface was smooth. And under the microscope, we observed the cystic dilatation of follicles (the total cystic follicle number of every couple ovaries was 11-37). We also observed the significant reduction of granulosa cells, appeared with fewer cell layers. Also the corpus luteum formation reduced in 17 model rats, there are five model rats showed the formation of corpus lutea (the total corpus luteum number of every couple ovaries was 7-15) and the remaining 12 model rats were observed no corpus luteum formation. Immunohistochemistry showed the expression of aquaporin-8 in both model group and control group in granulosa cells, theca cells, luteal cells and interstitial cells. The location of aquaporin-8 was mainly intracellular. The immunohistochemistry score of aquaporin-8 in the granulosa cells of model rats was significantly higher than that in normal rats (P<0.001).CONCLUSION:Aquaporin-8 is widely expressed in rat ovary, mainly intracellular. Androgen can induce polycystic ovary-like change in rats and can increase the expression of aquaporin-8 in granulosa cells, which indicates that aquaporin-8 participates in the influence of androgen on follicle development.