Repeated Gonadotropin Administration Suppresses T Cell Development in the Mouse Thymus

Gonadotropins, such as follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG), are widely used to induce ovarian hyperovulation during in vitro fertilization and embryo transfer (IVF-ET) for the treatment of infertility. However, the effects of repeated administration of these gonadotropins on immune function, particularly on T cell development in the thymus, remain poorly understood. This study investigated the effects of repeated administration of pregnant mare serum gonadotropin (PMSG) and hCG on thymic T cell development in mice. Histological analysis revealed structural changes in the thymus, including a blurred boundary between the medulla and cortex and reduced vascularization after repeated administration of PMSG and hCG. Quantitative real-time PCR showed increased expression of adipogenesis-related genes [phosphoenolpyruvate carboxykinase (PEPCK), adipocyte fatty acid-binding protein 2 (aP2), peroxisome proliferator-activated receptor gamma (PPARγ)] but no significant changes in thymic epithelial cell-related genes [autoimmune regulator (AIRE), epithelial V-like antigen (EVA), interleukin 7 (IL-7)]. Flow cytometry revealed a decrease in CD4⁺CD8⁺ T cells and an increase in CD4-CD8-T cells with altered CD25/CD44 subsets. In addition, CD4⁺ and CD8⁺ T cells in the spleen were significantly reduced. These findings suggest that repeated gonadotropin exposure may disrupt thymic T cell development and peripheral T cell populations, potentially impairing immune function. Further research is needed to elucidate the underlying mechanisms and broader immunologic consequences of gonadotropin use in infertility treatment.