IMMUNOHISTOCHEMICAL STUDY OF MELATONIN RECEPTOR 1A IN VARIOUS TISSUES IN ENDOMETRIOSIS

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone synthesized in the pineal gland that regulates circadian rhythms, has antioxidant properties, enhances antitumor immunity, inhibits tumor growth, and slows aging processes. The positive effects of melatonin can be characterized by its antioxidant effect, steroid hormone production, anti-cell proliferation, pro-apoptotic action, anti-cell adhesion, anti-invasion, and immune system regulation. Endometriosis is the presence of tissue similar to the endometrium outside the uterus, with its pathogenesis not yet fully understood. Key manifestations of endometriosis include infertility, dysmenorrhea, and chronic pelvic pain. The primary goal of endometriosis treatment is to alleviate its symptoms and improve reproductive function in women. Hormonal medications and symptomatic therapy are the main treatments for endometriosis. Since most medications have side effects, such as suppressing ovarian function, they cannot be recommended for women who wish to become pregnant. Consequently, it is crucial to develop alternative treatments that do not adversely affect pregnancy. Given that the pathophysiology of endometriosis cannot be fully explained, treatments should be multifunctional. In this regard, melatonin could become an ideal treatment for endometriosis symptoms and infertility. Objective: To determine the qualitative and quantitative characteristics of melatonin receptor 1A expression in different cells of ectopic endometrium, peritoneum, and ovaries in endometriosis and without endometriosis using immunohistochemical methods. Tissue samples (superficial endometriosis, deep endometriosis, fragments of healthy peritoneum, fragments of endometriotic cyst capsules, and fragments of ovaries) were obtained through laparoscopy. A total of 24 samples underwent immunohistochemical analysis. The highest expression of melatonin receptor 1A is observed on average in the endometrial epithelial cells in superficial endometriosis. However, in the case of deep infiltration, these same cells show significantly lower melatonin receptor 1A expression compared to superficial endometriosis observations. The same pattern is observed for stromal cells of ectopic endometrium. In ovarian theca cells with endometriosis, melatonin receptor 1A expression varies significantly between observations. Regarding blood vessel cells (endothelial cells and leiomyocytes), regardless of localization (peritoneum, ovary), a relatively stable pattern and quantitative parameters of melatonin receptor 1A expression are noted.