Therapeutic effect of letrozole in rats with endometriosis

The aim of this study was to investigate the effect of an aromatase inhibitor (letrozole) on endometriosis in female Sprague Dawley rats. Endometriosis was induced by surgical implantation of 5×5mm endometrium to rat peritoneum. One third of the rats were ovarietomized. The remainder were started on therapy with vehicle or Letrozole (1mg/kg/day). After 14 days of treatment, the rats were sacrificed and samples were collecting for measurement of serum estradiol level (A), weight of endometrial explant (B), height of ectopic endometrial glandular epithelium (C), glandular epithelial cell nuclear area of endometrial explant (D), weight of one uterine cornu (E), weight of one ovary (F) and body weight (G). The results are shown in the following table: Relative to vehicle treated groups, letrozole produced a significant atrophy of ectopic endometrial implants which was equivalent to that in ovariectomized rats. We conclude that letrozole suppresses the growth of endometrial tissues. These data support further investigation of aromatase inhibition as a novel therapeutic modality for endometriosis.