ENDOMETRIAL RESPONSE TO HORMONE REPLACEMENT THERAPY AS ASSESSED BY EXPRESSION OF INSULIN-LIKE GROWTH FACTOR-BINDING PROTEIN-1 IN THE ENDOMETRIUM

Objective: To assess endometrial response to parenteral levonorgestrel in hormone replacement therapy by means of morphological criteria and immunohistochemical staining of insulin-like growth factor-binding pr otein-1 (IGFBP-1). Design: Endometrial samples were collected from 35 postmenopausal women after 12 to 22 months of continuous combined estr ogen-progestin therapy. AU subjects were treated with parenteral proge stin. A group of 8 women was treated with a subdermal levonorgestrel-r eleasing implant, and 27 women had a levonorgestrel-releasing intraute rine device (IUD). Sections of formalin-fixed paraffin-embedded biopsi es were used for immunohistochemistry and after hematoxylin-eosin stai ning for routine histologic examination. Results: Atrophic epithelium with pronounced decidual reaction in the stroma was detected by histol ogic examination in all endometrial samples obtained from 27 women tre ated with the levonorgestrel-releasing IUD. In contrast, the endometri um was proliferative in seven of eight (87.5%) biopsies obtained from women treated with the levonorgestrel-releasing implant. Immunoreactiv e IGFBP-1 was detected in decidualized stromal cells in all endometria l samples obtained during intrauterine levonorgestrel therapy, whereas only one of eight samples obtained from women treated with subdermal levonorgestrel exhibited weak staining for IGFBP-1. Conclusions: Our d ata show that both the morphological and biochemical response of post- menopausal endometrium to parenteral levonorgestrel was strikingly dif ferent, depending on the route of progestin administration, and that t he decidual reaction and epithelial atrophy induced by intrauterine le vonorgestrel were associated with expression IGFBP-1 in decidualized s tromal cells.