Studies of molecular Nutrition on Retinoid absorption and metabolism

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1. Our investigations revealed that gene expression levels of cellular retinol-binding protein type II (CRBPII) is modulated through postnatal development of PPAR subtypes and endogenous transcriptional activator p300. This p300 coactivator is interacted with PPARa or PPAR6 in the presence of their specific ligands such as unsaturated fatty acids. During the weaning period (17day -25day ages) the PPARa/b ratio increased and CRBPII mRNA strongly expressed.2. Developmental expression pattern, of frcarotene cleavage enzyme (BCCE) activities are increased during the postnal development of small intestine of rats as well as chicks. The BCCE activity in rat jejunum was elevated during the weaning period. In chick case, duodenal BCCE activity was induced after their birth with its peak activity at 5 days after their hatching. The BCCE activity in rat jejunum was elevated by hormones of hydrocortisone (glucocorticoid) as well as thyroid hormone T3. The weaning diets containing high or low diet … More ary fat affected its activity showing that the high fat-feeding induced low BCCE activity and the low fat-feeding induced high BCCE activity in weaning rats. This results may explain why mother milk feeding during suckring period induce lower activity of BCCE in rat jejunum and why higher activity after weaning during rat development.3. After hatching, chick duodenum expressed highly BCCE mRNA, which levels increased developmentally and its peak expression occurred at 5 days after thir birth. The administration of hydrocortisone to chick embryo on day 14 and 17 of incubation, developmental profile of BCCE mRNA level changed to early its induction. The results suggested that endogeneous hormone level might involed to in the developmental induction of intestinal BCCE gene expression.4. It is clalified that dietary high fat induced CRBPII gene expression are accompanied with increases in intestinal retinol absorption and liver uptake of retinol delivered from intestine as well as chromicrone synthesis by using a indicator of microsomal transfer protein mRNA expression. Less