Showing papers by "Richard P. Metz published in 2002"
TL;DR: It is demonstrated that vitamin A intake during adolescence alters mammary gland differentiation and indicate that a narrow range of vitamin A consumption during adolescence protects against carcinogenesis.
Abstract: We tested the hypothesis that adolescent dietary vitamin A intake impacts mammary gland development and subsequent sensitivity to carcinogenesis Sprague-Dawley rats were fed a purified diet that was vitamin A deficient, adequate (22 mg retinyl palmitate/kg diet), or supranutritional (16 mg retinyl palmitate/kg diet) from 21 to 63 days of age, the period of adolescent mammary gland development At 73 days of age, rats were given 1-methyl-1-nitrosourea (25 mg/kg body wt ip) and monitored for mammary tumors Tumors appeared earlier and more frequently in rats fed vitamin A-deficient or -supplemented diets Vitamin A deficiency during adolescence was associated with alveolar mammary gland development and precocious milk protein expression, while supplementation was associated with ductal gland development and suppression of milk protein expression Differences in circulating estradiol and mammary gland estrogen receptor-α, and estrogen-responsive progesterone receptor mRNA were not observed, suggesting that
16 citations