Investigating the effects of melatonin on structural and vascular changes in an experimentally induced ovarian hyperstimulation syndrome model : Effects of melatonin on experimentally induced ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is a serious complication commonly encountered in patients with infertility undergoing ovulation induction therapy. This study investigates histomorphological and biochemical effects of melatonin in an experimental OHSS model. Rats were divided into four groups: control group, controlled ovarian stimulation group (COS), ovarian hyperstimulation syndrome group (OHSS), and ovarian hyperstimulation syndrome + melatonin group (OHSS + melatonin). OHSS was induced in the OHSS and OHSS + melatonin groups by pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) injections, followed by melatonin treatment administered intraperitoneally at a dose of 50 mg/kg only in the OHSS + melatonin group. In the OHSS group, ovarian weight increased and the number of atretic follicles also rose, while melatonin treatment improved these conditions. Histological analysis showed that melatonin preserved ovarian structure and supported follicular development. Serum estradiol levels were significantly higher in the OHSS group compared with the control group, but melatonin treatment reduced these levels significantly. Peritoneal fluid levels of vascular endothelial growth factor (VEGF) and interleukin (IL)-6 were elevated in the OHSS group, but melatonin treatment decreased these levels. Additionally, melatonin reduced follicular atresia and increased the number of Graafian follicles. In conclusion, melatonin improved the biochemical and histological markers of OHSS, providing protective effects on ovarian function. These findings suggest that melatonin could be a potential therapeutic agent for the treatment of OHSS. However, further clinical and experimental studies are needed to investigate its effects.