On the Functional Site of Vitamin A

Abstract

The functional site of vitamin A was chemically and morphorogically studied in term of codeine demethylation by liver microsomes of vitamin A-deficient rats and in the level observed with electron microscope in liver tissues. Vitamin A deficiency resulted in a depression in the level of codeine demethylase, and in a proliferation of the smooth-surfaced endoplasmic reticulum or vesicles and a declaration of the ergastoplasm or ribosomes in hepatic parenchymal cells. Even if the vitamin A-deficient rat was previously injected with codeine, the restorating induction of codeine demethylase no longer took plase. Vitamin A-deficient rats restored the demethylating activity of the liver microsome in 24-48 hours by means of the three day-administration of vitamin A, 100μg per day. Actinomycin D completly prevented the restoration of codeine demethylase to normal, by the experimental design providing vitamin A one hour after each treatment with actinomycin D. The abovementioned data indicate that the effect of vitamin A is to increase the synthesis of enzyme protein and further that the site of action of vitamin A was at the transcription level from DNA to RNA.