Effects of irisin on obesity-dependent changes in functions of reproduction at male and female rats

Exercise has positive effects on sexual dysfunctions and sperm disorders that occur as a result of obesity in men. Also, it is known that exercise has positive effects on sexual dysfunctions associated with obesity in women. However, the effects of irisin, which is an adipomyokine secreted into the systemic circulation during exercise, on male and female sexual dysfunction in obesity are not yet known. The main purpose of this thesis study is to investigate the possible effects of irisin on male and female neuroendocrine systems in high-fat diet-induced sexual dysfunction models. Initially, male and female animals were divided into four groups as control, obese, irisin, and obese+irisin (n = 10 for each group). Adult male and female rats in the obese and obese+irisin group were fed a high-fat diet of 60% kcal for an average of 22 weeks and 14 weeks, respectively. Then an obesity-induced sexual dysfunction model was established. Afterward, perfusion of the subcutaneous irisin (100 ng/kg/day) was performed for 4 weeks by a mini-osmotic pump to male and female rats in the irisin and obese+irisin groups. In male rats, high-fat diet-induced obesity was shown to reduce sexual performance and sexual motivation, erection, libido, and potency. The irisin was found to ameliorate all these disruptions in sexual performance in male rats. However, the irisin perfusion did not directly affect the LH, FSH, and inhibin-B hormone balance, which were impaired in obesity. However, it was found that it improved obesity-induced histopathological damages in testicular tissue and reduces serum leptin levels, which were increased in obesity. The perfusion of the irisin was also found to improve decreased sperm motility and sperm anomalies (head and total anomalies) originating from obesity in male rats. It was found that obesity did not alter female sexual motivation, but caused serious histopathological changes in the ovary, significantly increased serum leptin levels, and significantly decreased estradiol levels. However, it was observed that testosterone, progesterone, and FSH levels did not change in female rats due to obesity. The perfusion of the irisin significantly decreased FSH levels in the irisin group compared to the control group, while it increased the progesterone levels significantly in the obese+irisin group compared to the obese and control group, and in the irisin group compared to only control group. However, it did not change serum testosterone, LH, and estradiol levels. On the other hand, after perfusion of the irisin, it was found that the deterioration in ovarian histopathology resulted from obesity improved, and increased serum leptin levels decreased significantly. In conclusion, within the scope of this thesis study, it is suggested that irisin, an exercise hormone, may play an ameliorative role in reproductive system disorders that develop due to obesity, and therefore irisin can be proposed as a therapeutic protein at this point.