Expression and significance of serum ghrelin level and ovarian tissue growth substance in a rat model of polycystic ovary syndrome / 解放军医学杂志

ABSTRACT

Objectives To investigate the relationship between ghrelin and estrous cycle and the expression and significance of ghrelin in the ovary and endometrium of rat models of polycystic ovary syndrome (PCOS). Methods A total of 44 eight-week-old SD rats were selected for the present study. Insulin and human chorionic gonadotrophin (HCG) were used in 24 rats to reproduce PCOS model, whereas the remaining 20 were given similar amount of normal saline as the control group. The immunohistochemical method was used to detect the ghrelin expression in the ovary and endometrium of these two groups, whereas ELISA was adopted to determine serum ghrelin levels during different estrous cycles, and also before and after fasting. Results Significant differences in the serum ghrelin levels were observed between before and after fasting in the PCOS rat models (P=0.004). The serum ghrelin levels during different estrous cycles showed periodic variations in the control rats, but without significant difference (P=0.084). The serum ghrelin level of the PCOS model group was lower than that in the control group, but without significant statistical difference (P=0.067). Ghrelin expression could be seen in the ovarian tissue during the whole estrous cycle of rats in the control group. In particular, the expression was significantly elevated at metestrus. The ghrelin expression in the model group was significantly reduced compared with the control group during different estrous cycles (P=0.031). No ghrelin expression was found in the endometrium of rats in the two groups. Conclusions Ghrelin expression may fluctuate periodically during the estrous cycle, and its highest level occurs at the metestrus. Ghrelin may be related to the corpus luteum function, and has no evident relation with the endometrial function.