The results demonstrated that exogenous melatonin administration significantly improved PCOS symptoms in rats, including reduced body weight gain, changes in organ weight/body weight index, blood glucose level, percentage diestrus phase, testosterone, estradiol, progesterone, and LH/FSH ratio, as well as 3β-HSD and 17β-HSD enzyme activity. The gene discussed is PLOD1; the disease is polycystic ovary syndrome.