Effects And Mechanisms Of Exercise Intervention On Polycystic Ovary Syndrome In Rats

ObjectiveIn order to proclaim the possible mechanism(s) of exercise intervention for PCOS prevention and to provide scientific basis for the prevention and control of PCOS, we studied the changes of leptin, its receptor OB-Rb, and Suppressor of Cytokine Signaling 3(SOCS3) before and after exercise intervention by observing the effects of exercise intervention on preventing PCOS. MethodsThis experiment adopted completely random design, the control group, model group and intervention group were set up. The exercise intervention is taking three different intensity of swimming exercise, high(2h/d), moderate(1h/d) and low(0.5h/d), respectively. Radioimmunoassay measured serum sex hormones, insulin and leptin levels in rats; histologic changes in ovaries were observed by HE staining; Determination of ovarian leptin and OB-Rb and SOCS3 mRNA levels were measured by real-time fluorescent quantitative PCR; Western blot was used to detect the rat ovary OB-Rb and SOCS3 protein level; Immunohistochemical method was used to detect the expression site and strength of OB-Rb, SOCS3 protein in ovarian tissue of rats. ResultsRats general informationThe model rats successfully constructed PCOS, as they presented obesity, leptin resistance, sex hormone disorder, no ovulation and large cystic follicles, together with the increasing fasting insulin(FINS) and leptin level.Rats of the 0.5h group had no statistical difference in body weight, serum sex hormone and leptin level when compared with the model group(P>0.05) and they were similar in the status of estrous cycle. A large quantity of cystic follicles within the ovaries, barely could find normal follicles and corpus lutea. FINS level were slightly decreased comparing to the models, but still higher in number than the controls, all with statistical significance(P<0.05).The 1h group rats lost some weight due to the exercise, which made them not statistically different with control(P>0.05). It also helped rat retain the ability of ovulation. Normal follicles and corpus lutea can be seen in ovaries, together with some cystic follicles; Progesterone(P) level was lifted but still lower than control, showing statistical difference(P<0.05). Follicle stimulating hormone(FSH) level were markedly increased while FINS and leptin levels were substantially decreased, showing statistical significance(P<0.05) in comparison with model group. But no statistical difference were found when compared with control(P>0.05).Except lower in estradiol(E2) concentration, rats of the 2h group performed well in body weight, estrous cycle and ovarian morphology: the 2h exercise reduced testosterone(T), luteinizing hormone(LH), FINS and leptin level, also improved FSH and P level of PCOS rats, having statistical significant differences with the model group(P<0.05).Transcription of leptin, OB-Rb and SOCS3 genes in ovarian tissueOvarian leptin mRNA and OB-Rb mRNA level of model rats were higher than those in control rats, statistical significance exists(P<0.05). Leptin mRNA didn’t change in 0.5h group, showing no difference with model group(P>0.05). While OB-Rb m RNA of this group was enhanced and SOCS3 mRNA decreased. All the differences were statistical significance(P<0.05). Leptin mRNA expression in 1h group were less than that in the 0.5h group, the difference was statistically significant(P<0.05). But, the OB-Rb mRNA and SOCS3 mRNA were not differ from those in the 0.5h group(P>0.05). Leptin mRNA level in 2h intervention group had no statistical difference with control(P>0.05), while OB-Rb and SOCS3 mRNA were higher than those in control, having statistical significance(P<0.05).Translation and expression of SOCS3 and OB-Rb genes in ovarian tissueOB-Rb was expressed in both granulosa cells of different stage of growing follicles and oocytes. With developing of follicles, expression of OB-Rb increased gradually. Model group and 0.5h group were weaker in expression of OB-Rb than control group, showing statistically significant difference(P<0.05). 1h and 2h per day exercise improved OB-Rb protein expression compared with moel group with significant difference(P<0.05). expression of OB-Rb was not different among the three intervention group, of which had no statistical significance((P>0.05)) but all higher than in model group(P>0.05).SOCS3 was expressed in the same place as OB-Rb. Expression trend of SOCS3 were opposite to OB-Rb in granulosa cells of growing follicles but not differed in oocytes. Both 0.5h and 1h exercise revealed reduction in expression of SOCS3 but the 2h exercise group showed a sharp increase in SOCS3. All differences were statistical significant(P<0.05). It may be attributed to the upgrading OB-Rb expression in ovarian tissue. ConclusionsLeptin resistance is one of the causes of PCOS. Feasible form and intensity of exercise can ameliorate leptin resistance by reducing adiposity composition and improving the expression of OB-Rb gene in ovary, thus effectively prevent the occurrence of PCOS.