Retinol Research Today is a free monthly online journal that collates and summarizes the latest research about Retinol, including details on vitamin a, uses, wrinkle treatment, anti-aging.

Antiestrogenic activity of vitamin A in in vivo uterotrophic assay.

Koda T, Imai H, Morita M

Division of Environmental Health Sciences, Department of Social Medicine, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Japan. tk760131@med.miyazaki-u.ac.jp

All-trans-retinoic acid (ATRA), the primary active metabolite of vitamin A, was examined for its antiestrogenic activity in rats using an in vivo uterotrophic assay. All rats were ovariectomized 2 weeks prior to receiving 5 mg/kg/day ATRA or 0.3 micro g/kg/day ethynyl estradiol (EE) subcutaneously once a day for 3 consecutive days. Rats were sacrificed 1, 3, 6, 12 or 24 h after the last treatment. EE increased uterine weight and the coinjection of ATRA with EE significantly suppressed this effect 3 and 24 h after treatment. mRNA expression was examined during this 24-h period and the mRNA expression levels of estrogen receptor alpha (ER alpha), retinoic acid receptor beta (RAR beta), retinoid X receptor gamma (RXR gamma) and cellular retinol-binding protein I (CRBP I) were found to have significantly increased in the ATRA+EE group compared with those in the EE group. This is the first report on the antiestrogenic activity of ATRA determined using an in vivo adult rat uterotrophic assay. The up-regulation of RAR or RXR mRNA expression level was probably responsible for the antiestrogenic activity of ATRA.

Published 6 February 2007 in Life Sci, 80(10): 945-9.
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