Multigenerational exposure to ethinyl estradiol affects bone geometry, but not bone mineral density in rats.

Estrogenic compounds are known to prevent bone loss in ovariectomized adult rats; however, their effects on bone in developing and reproductively-intact rats are less well-understood. In a large multigenerational experiment 0, 2, 10, or 50 ppb ethinyl estradiol (EE) in the diet was fed to intact male and female rats from conception until either weaning, postnatal day 140, or continuously for 2 years. Vertebrae (lumbar and caudal) and femurs were collected from subsets of these animals at necropsy at 48 days, 70 days, 140 days, or 2 years of age and subjected to dual-energy X-ray absorptiometry (DXA) scanning to measure bone mineral density (BMD), bone mineral content (BMC), and bone area.

Multigenerational exposure to genistein does not increase bone mineral density in rats.

Genistein has been shown to prevent bone loss in ovariectomized adult rats. However, the effects of genistein on bone in developing and reproductively-intact rats have not been examined. A large multigenerational experiment involved feeding 0, 5, 100, or 500 ppm genistein in the diet to intact male and female rats from conception until either weaning, postnatal day 140, or continuously for 2 years.

Dietary modulation of 7,12-dimethylbenz[a]anthracene (DMBA)-induced adrenal toxicity in female Sprague-Dawley rats.

In this study, dietary modulation of 7,12-dimethylbenz[a]anthracene (DMBA)-induced adrenal toxicity in rats was investigated. Beginning at postnatal day (PND) 21, female Sprague-Dawley rats were fed either soy-containing NIH-31 diet or soy- and alfalfa-free 5K96 diet. On the first day of diestrus when the animals were PND 50 +/- 5, rats received either an oral dose of 80 mg/kg DMBA or sesame oil, the vehicle, and were sacrificed at 24, 36, or 48 h after treatment.

Effects of dietary soy and estrous cycle on adrenal cytochrome p450 1B1 expression and DMBA metabolism in adrenal glands and livers in female Sprague-Dawley rats.

Cytochrome p450 1B1 (CYP1B1) has been shown to be important in the bioactivation of 7,12-dimethylbenz[a]anthracene (DMBA) to an adrenal toxin in rats. We investigated the effects of diet and stage of estrous cycle on CYP1B1 expression in rat adrenal glands and on DMBA metabolism by rat adrenal and hepatic microsomes. Female Sprague-Dawley (SD) rats were placed on either standard soy-containing NIH-31 rat chow or soy- and alfalfa-free 5K96 diet from postnatal day (PND) 21 until sacrifice at PND50+/-5.

Estrogen receptor expression in the prostate of rats treated with dietary genistein.

Steroid hormones and their receptors play critical roles in the growth, development, and maintenance of the male reproductive tract. Genistein, a naturally occurring isoflavonoid primarily found in soybeans, interacts with estrogen receptors alpha and beta (ER alpha and beta), with preferential affinity for ER beta. This is one mechanism whereby genistein may affect growth and development and potentially alter susceptibility to carcinogenesis.

Effect of nonylphenol on serum testosterone levels and testicular steroidogenic enzyme activity in neonatal, pubertal, and adult rats.

Previous dose range-finding studies with nonylphenol (NP) administered to rats in a soy- and alfalfa-free diet showed apparent feminization of several endpoints in male rats at doses of 25 ppm and above. One possible mechanism contributing to these effects is a reduction of testosterone at critical developmental periods. The present study was conducted as an adjunct to a multigeneration study and was designed to examine the effect of NP on testosterone production.