title: Requirement for ascorbic acid in a rat mutant unable to synthesize ascorbic acid.
abstract: The activities of several enzymes involved in hepatic ascorbic acid synthesis and the requirement of dietary ascorbic acid were investigated in the OD (osteogenic disorder) rat, which has a hereditary defect in ascorbic acid-synthesizing ability. No activity of hepatic L-gulonolactone oxidase was detected in OD rats. However, OD rats maintained the normal activities of hepatic UDPglucose dehydrogenase, UDPglucuronyl transferase and beta-glucuronidase. Hemorrhage in muscle and leg joints, lower hepatic content of cytochrome P-450 and lower activities of hepatic drug-metabolizing enzymes, higher serum and adrenal levels of corticosterone and lower urinary excretion of hydroxyproline were observed in ascorbic acid-deficient OD rats than in OD rats fed 300 mg ascorbic acid/kilogram diet. Consequently, we conclude that OD rats cannot synthesize ascorbic acid because of the lack of activity of hepatic L-gulonolactone oxidase and that the dietary addition of about 300 mg ascorbic acid (per kilogram diet) is enough to prevent signs of vitamin C deficiency and to achieve maximum growth, and that more than 300 mg ascorbic acid per kilogram diet may be required for the maximum activity of hepatic drug-metabolizing enzymes.
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000096:biosynthesis / Q000502:physiology*; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004032:Diet; D006909:Hydroxyproline / Q000652:urine; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D009751:Nutritional Requirements; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011922:Rats, Mutant Strains; D013154:Spleen / Q000378:metabolism
chemical_list: D003577:Cytochrome P-450 Enzyme System; D001205:Ascorbic Acid; D006909:Hydroxyproline; D003345:Corticosterone