title: Metabolism of all-trans-retinoic acid and all-trans-retinyl acetate. Demonstration of common physiological metabolites in rat small intestinal mucosa and circulation.
abstract: The kinetics and metabolism of physiological doses of all-trans-retinoic acid were examined in blood and small intestinal mucosa of vitamin A-depleted rats. A major portion of intrajugularly injected retinoic acid is rapidly (within 2 min) sequestered by tissues; subsequently 13-cis-retinoic acid and polar metabolites are released into circulation. All-trans-retinoic acid appears in small intestinal epithelium within 2 min after dosing and is the major radioactive compound there for at least 2 h. Retinoyl glucuronide and 13-cis-retinoic acid are early metabolites of all-trans-retinoic acid in the small intestine of bile duct-cannulated rats. Retinoyl glucuronide, the major metabolite of retinoic acid intestinal epithelium, in contrast to other polar metabolites, was not detected in circulation. An examination of [3H]retinyl acetate metabolites under steady state conditions in vitamin A-repleted rats demonstrates the occurrence of all-trans-retinoic acid and 13-cis-retinoic acid in circulation and in intestinal epithelium, in a pattern similar to that found after injection of retinoic acid into vitamin A-depleted rats. Our data establish that all-trans-retinoic acid, 13-cis-retinoic acid, and retinoyl glucuronide are physiological metabolites of vitamin A in target tissues, and therefore are important candidates as mediators of the biological effect of the vitamin.
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004224:Diterpenes; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D007536:Isomerism; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012176:Retinoids / Q000302:isolation & purification; D000084562:Retinyl Esters; D013329:Structure-Activity Relationship; D014212:Tretinoin / Q000378:metabolism*; D014316:Tritium; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000378:metabolism; D014802:Vitamin A Deficiency / Q000378:metabolism
chemical_list: D004224:Diterpenes; D012176:Retinoids; D000084562:Retinyl Esters; D014316:Tritium; D014801:Vitamin A; C009166:retinol acetate; D014212:Tretinoin