Abstract: Objective To investigate the effect of overexpression of miRNA-320 on ovarian function in cisplatin induced premature ovarian failure rats. Method Thirty two SD female rats were randomly divided into 4 groups: normal control group, model group, negative control group and miRNA-320 overexpression group. During the experiment, the differences of diet, activity and body hair were observed every day. The contents of E2, FSH and LH in serum of each group were detected by ELISA. HE staining was used to observe the histological changes of ovaries. The expression levels of miRNA-320, PGRMC1 and BMP15 in ovaries of rats in each group were detected by qRT-PCR. Western blot was used to detect the protein expression of PGRMC1 and BMP15 in ovarian tissue of each group. Result Compared with the normal control group, the rats in the model group were slow in activity and in response, loss of appetite and weight, dull and lusterless body hair; histomorphological analysis showed that the ovarian tissue was obviously atrophic, the cortex became thinner, the number of atretic follicles was more, the interstitial fibrous tissue was more; the serum FSH and LH were significantly increased, while the protein and mRNA levels of PGRMC1 and BMP15 were decreased in serum E2 and ovarian tissues ( P<0. 05) . Compared with the negative control group, the activity of overexpression group was increased, the response was more agile, the food intake was increased, the body hair was gradually glossy; interstitial fibrosis was significantly reduced, the

number of mature follicles was significantly increased, the number of corpus luteum was increased; the content of serum E2, the protein and mRNA expression level of PGRMC1 and BMP-15 in ovarian tissue were increased, while the content of FSH and LH were decreased ( P<0. 05) . Conclusion Cisplatin induces ovarian dysfunction in rats with premature ovarian failure; overexpression miRNA-320 improves ovarian function in cisplatin-induced premature ovarian failure rats.