Effect of oxytocin treatment on explant size, plasma and peritoneal levels of MCP-1, VEGF, TNF-α and histopathological parameters in a rat endometriosis model

OBJECTIVE: To determine the effects of oxytocin (OT) on surgically induced endometriosis in a rat model. STUDY DESIGN: Twelve female Sprague-Dawley rats were included. After the implantation and establishment of autologous endometrium onto the abdominal wall peritoneum, the rats were randomly divided into two groups, treated with intramuscular oxytocin (OT group, 160μgkg/day, n=6) or isotonic NaCl solution (control group, 1mLkg/day, n=6) for 28 days. To evaluate the therapeutic effects of OT, the explant volumes were calculated and the levels of vascular endothelial growth factor (VEGF), monocyte chemotactic protein-1, and TNF-α were measured in plasma and peritoneal fluid. Endometriotic explants were examined histologically by semiquantitative analysis. RESULTS: After treatment, the mean endometriotic explant volume was decreased in the OT group (p=0.016). The histopathological score and VEGF immunoexpression of endometriotic explants were significantly lower in the OT group (p=0.007) than in controls (p=0.000). Inflammatory cytokine levels in plasma and peritoneal fluid were considerably decreased in the OT group. Moreover, TUNEL immunohistochemistry clearly demonstrated more apoptotic changes in the mononuclear cells of the OT group compared with controls. CONCLUSION: We suggest that oxytocin might be considered as a potential candidate therapeutic agent for endometriosis.