vitamin-a2 and retinol-acetate

Relationships between increased adiposity and fat-soluble vitamin storage and metabolism are poorly understood. To examine these associations, 6% or 21% dietary fat was fed to rats for 11 weeks and tissue vitamin A storage determined. Two levels of supplemental vitamin A were administered. At the end of the tenth week, 3,4-didehydroretinol (DR) was administered orally, and its kinetics were followed for 1 week in serum and tissues. Model-based compartmental analysis was applied to these data. Kidney total retinol (R) concentrations were elevated in rats fed 6% compared with 21% dietary fat (n = 24/group). The fractional transfer coefficient (FTC) describing the movement of tracer from plasma to extravascular stores was two times higher in the 6% compared with the 21% fat group. Consistent with the elevated renal R in 6% fat fed rats, there was a 2-fold increase in the FTC representing tracer distribution from plasma to kidney in the 6% compared with 21% fat group. Taken together with a fat main effect on renal vitamin A, our data support the evidence that faster turnover of kidney R may help set the mechanism governing vitamin A tissue distribution during deficiency. Rats fed 21% versus 6% dietary fat conserved hepatic R more efficiently.

Topics: Adipose Tissue; Adiposity; Animals; Body Weight; Dietary Fats; Diterpenes; Liver; Male; Models, Biological; Obesity; Rats; Rats, Sprague-Dawley; Retinoids; Retinyl Esters; Vitamin A; Vitamin A Deficiency

Vitamin A-deficient diet affected the body weight or growth of Heteropneustes fossilis, a freshwater siluroid rich in 3-4,dehydroretinol. The fish lost body weight after 20-30 days of administration of vitamin A-deficient diet. Cessation of growth occurred owing to vitamin A-deprivation, whereas control fish after supplementation of vitamin A continued their growth. Initial growth of the fish after administration of vitamin A-deficient diet is regulated by its initial vitamin A-reserve, whereas successive deficiency lead to the cessation of growth or weight loss. Supplementation of retinyl acetate to vitamin A-deficient fish compensate the loss of body weight.

Topics: Animals; Body Weight; Diet; Diterpenes; Fishes; Intestines; Liver; Retinyl Esters; Vitamin A

The acetate and palmitate esters of 3,4-didehydroretinol (DR; vitamin A2 alcohol) have been synthesized and characterized. When administered orally in corn oil to female rats, DR was present in the serum as the alcohol, but primarily as esters in the liver. As total stores of retinol (R; vitamin A1 alcohol) decrease, the ratio of DR to R in the serum markedly increases. The ratio of DR to R in serum was greater than 0.27 at liver vitamin A1 palmitate values of less than 3 micrograms/g, 0.05-0.14 at 3-19 micrograms/g, and less than 0.04 at greater than or equal to 20 micrograms/g. Thus, the ratio of DR to R in the serum at a suitable interval after the administration of dehydroretinyl acetate may aid in assessing marginal vitamin A status. DR was not demonstrably converted to R in these studies.

Topics: Animals; Diterpenes; Female; Liver; Rats; Rats, Inbred Strains; Retinyl Esters; Vitamin A; Vitamin A Deficiency