视黄醇或维生素A醇是维生素A的主要循环形式。它不具有生物活性并可作为活性类视黄醇的一种前体。视黄醇可转化为视黄醛,然后再转化为视黄酸。All-trans及9-cis-视黄酸是核受体、视黄酸受体(RAR)和类视黄醇X受体(RXR)的配体。这些受体是多种基因的转录调控因子。视黄酸受体(the retinoic acid receptor,RAR) 和类视黄醇受体(the retinoid X receptor,RXR)的配体,作为其转导因子,调控正常和恶性细胞的生长和分化。
体内研究:
The results show that compare with control (CON) rats, high-fat diet (HFD) significantly lowers basal level of Vitamin Al in plasma, but markedly elevates basal levels of Retinol in kidney, adipose tissue and liver. The results show that Vitamin Al absorption in HFD rats is faster than that in CON rats, evidenced by significantly shorter Tmax (3.0±0.0 h for HFD rats vs 5.8±1.1 h for CON rats, p<0.05). The plasma Vitamin A levels in methionine-choline deficient diet (MCD) rats are significantly lower than in the controls while the hepatic Vitamin A levels in MCD rats are markedly higher. The hepatic expression of Retinol-metabolizing enzymes and binding proteins (GRBP-I, ALDH1A1, and ALDH1A2) in MCD rats is significantly higher than that in control rats.