Thalidomide Reduces Cell Proliferation in Endometriosis Experimentally Induced in Rats

To analyze the effect of thalidomide on the progression of endometriotic lesions experimentally induced in rats and to characterize the pattern of cell proliferation by immunohistochemical Proliferating Cell Nuclear Antigen (PCNA) labeling of eutopic and ectopic endometrium. Fifteen female Wistar rats underwent laparotomy for endometriosis induction by resection of one uterine horn, isolation of the endometrium and fixation of a tissue segment to the pelvic peritoneum. Four weeks after, the animals were divided into 3 groups: control (I), 10mg/kg/day (II) and 1mg/kg/day (III) intraperitoneal thalidomide for 10 days. The lesion was excised together with the opposite uterine horn for endometrial gland and stroma analysis. Eutopic and ectopic endometrial tissue was submitted to immunohistochemistry for analysis of cell proliferation by PCNA labeling and the cell proliferation index (CPI) was calculated as the number of labeled cells per 1,000 cells. Group I showed a mean CPI of 0.248 ± 0.0513 in the gland and of 0.178 ± 0.046 in the stroma. In contrast, Groups II and III showed a significantly lower CPI, that is, 0.088 ± 0.009 and 0.080 ± 0.021 for the gland (