Effects of neonatal administration of diethylstilbestrol on aberrant crypt foci induced by 7,12-dimethylbenz[alpha] anthracene in rats.

Gastrointestinal carcinoma is affected environmental factors, however, it remains to be determined whether neonatal administration of an estrogenic endocrine disruptor, such as diethylstilbestrol (DES), affects gastrointestinal carcinogenesis. The effects of neonatally administered DES on gastrointestinal tumorigenesis induced by 7,12-dimethylbenz[a]anthracene (DMBA) were investigated in male and female rats. Male and female rats in group I were daily administered oil alone from 0-14 days after birth.

Effects of neonatally administered low-dose diethylstilbestrol on the induction of mammary carcinomas and dysplasias induced by 7,12-dimethylbenz [a] anthracene in female rats.

The aim of this study was to investigate the effects of neonatal administration of diethylstilbestrol (DES) on the induction of mammary carcinomas (MCs) and dysplasias (MDs) induced by 7,12-dimethylbenz[a]anthracene (DMBA) in female rats. Three different methods of continuous administration of DES (1 microg) were used: 0-14, 0-5 and 6-14 days after birth, and all rats were given DMBA (10 mg) at 50 days after birth. All rats administered DES showed persistent estrus and anovulatory ovaries.

Increased bone mineral density in aged rats with spontaneous mammary dysplasia.

Spontaneous mammary tumors were seen in seven of the 12 breeding female rats aged 2 years. All mammary tumors were diagnosed as mammary dysplasia (MD). Bone mineral contents (BMC) and bone mineral density (BMD) of their lumbar vertebrae and femur were determined using dual energy X-ray absorptiometry (DXA).

Expression of estrogen receptor-alpha protein in the rat digestive tract.

The current study evaluates the expression of estrogen receptor-alpha (ER-alpha) protein in the digestive tract and other organs using immunohistochemistry in male and female intact rats. As a result, the expression of ER-alpha protein was intensively immunoreactive in the nuclei of squamous epithelium of the forestomach connected to the limiting ridge and the anus connected to the anorectal junction. Rat ER-alpha mRNA signals were also detected in the epithelium of the limiting ridge using in situ hybridization.

Effects of neonatally-administered 17beta-estradiol on induction of mammary carcinomas by 7, 12-dimethylbenz[a]anthracene in female rats.

Various doses of 17beta-estradiol (E2) were administered subcutaneously to inbred female Sprague-Dawley (SD) rats once at birth. At 50 days after birth, rats in all the groups were given 10 mg of 7, 12-dimethylbenz[a]anthracene (DMBA). In the 1000 microg group, the incidence and number of mammary carcinomas were markedly low, while in the 10 microg group, a large number of mammary carcinomas was noted.