Estrogenic effects of genistein in ovariectomized gilts.

摘要

Genistein, has a range of estrogenic actions, however only limited research has been done to investigate its effects in swine. The objective was to characterize the effects of administration of a graded dose of genistein on tissues known to be estrogen sensitive. Thirty-four post-pubertal gilts were ovariectomized, and randomly assigned to one of six-treatment groups 15 days post-ovariectomy. Treatment groups received vehicle, estradiol (2 mg/day), or genistein (50, 100, 200 or 400 mg/day). Treatments were administered by intramuscular injection at 12-hour intervals for 10 days. Gilts were slaughtered after the treatment period. Reproductive tissues (cervix, uterus, and mammary glands) were collected, trimmed of extraneous tissue, and processed for chemical or histological analysis. Uterine and cervical tissue mass, as indicated by wet, dry, and protein weights and total DNA content (g or mg/100 kg bw) increased as the dosage of genistein increased (P 0.01). The proportion of tissue components in uterus and cervix was not affected by genistein dose (P > 0.05), except for cervical protein percentage (P 0.01). Height of epithelial cells lining the uterine glands and the lumens of the uterus and cervix was increased when treated with 400-mg/day genistein or estradiol (P 0.01). Immunohistochemical staining was positive in all tissues stained for proliferating cell nuclear antigen (PCNA) and progesterone receptor (PR). Treatment with 400-mg/day genistein increased the percentage of cells stained positive for PR in the uterine glands and the cervical lumens (P 0.05), while the percentage of cells stained positive for PCNA was increased in the uterine glands and lumen (P 0.05). In the mammary gland treatment with 400-mg/day genistein caused slight development of the mammary gland, as duct length was increased, and some lobular development was present, while gilts treated with estrogen had substantial growth of mammary gland ducts, and more defined lobular development. Tissue development was stimulated by genistein in a dose-dependent manner, although no genistein dose tested induced a response as great as estradiol. Estrogen target tissues such as the cervix, uterus, and mammary gland are affected by exposure to high doses of the soybean phytoestrogen genistein.