You are here:
NEONATAL LOW- AND HIGH-DOSE EXPOSURE TO ESTRADIOL BENZOATE IN THE MALE RAT: II. EFFECTS ON THE MALE PUBERTY AND THE REPRODUCTIVE TRACT
Citation:
Putz, O., C. B. Schwartz, G. A. LaBlanc, R L. Cooper, AND G. Prins. NEONATAL LOW- AND HIGH-DOSE EXPOSURE TO ESTRADIOL BENZOATE IN THE MALE RAT: II. EFFECTS ON THE MALE PUBERTY AND THE REPRODUCTIVE TRACT. BIOLOGY OF REPRODUCTION 65(5):1506-1517, (2001).
Description:
NEONATAL LOW- AND HIGH-DOSE EXPOSURE TO ESTRADIOL BENZOATE IN THE MALE RAT: II. EFFECTS ON MALE PUBERTY AND THE REPRODUCTIVE TRACT. Oliver Putz, Christian B. Schwartz, Gerald A. LeBlanc, Ralph L. Cooper, Gail S. Prins
ABSTRACT
Environmental contaminants with estrogenic properties have been cause for heightened concern about their possible role in inducing adverse health effects. Brief exposure of rodents to high doses of natural estrogens early in life results in permanent alterations of the male reproductive tissues, but it remains controversial if environmental relevant doses can cause the same effects. The current project was designed to determine the dose-response relationship between neonatal estradiol exposure and the development of the male reproductive tract in the rat. Neonatal male Sprague-Dawley (SD) and Fisher 344 (F344) rats were exposed to -estradiol-3-benzoate (EB) at concentrations ranging from 0.015 g/kg to 15.0 mg/kg. Results showed an inverted-u dose-response profile for testis and epididymis weights in 35-day old SD rats with increased organ sizes at the low-dose end of the treatment. This effect was transient and not sustained into adulthood. Increased hepatical testosterone hydroxylase activities in low-dosed animals suggest an advancement of puberty as the cause for increased reproductive organ weights. On postnatal day (PND) 90, a stimulatory low-dose response to EB was present in SD testicular and epididymal weights, however at one order of magnitude lower dose than that seen on PND 35 suggesting that it manifested a separate effect. All SD male reproductive tract organs and serum hormones showed a permanent inhibitory response to high doses of neonatal EB. F344 exhibited greater estrogen sensitivity on PND 90. Despite his heightened responsiveness, F344 rats did not exhibit a low-dose effect for any endpoint. Our data demonstrate that low-dose responses to estradiol are organ and strain specific.