Enhancement of histidine and one-carbon metabolism in rats fed high levels of retinol.
Histidine metabolism was studied in rats fed 10% casein diets supplemented with 1000 IU of retinol/g concurrent with or previous to exposure to high levels of dietary histidine (1% or 2%). When a retinol-supplemented 10% casein + 1% histidine diet was fed ad libitum for 21 days, urinary excretion of formiminoglutamic acid (FIGLU) was decreased by 50-70% over the entire period and plasma histidine was reduced by 30-70% for 16 days compared to rats receiving 10% casein + 1% histidine with normal levels of retinol. Rats pretreated for 10 days with a 10% casein diet supplemented with high levels of retinol oxidized 30% more L-[ring-2-14C]histidine to 14CO2 and excreted 76% less of the administered dose as urinary FIGLU compared to control rats not pretreated with high levels of retinol. Depression in growth due to supplementation of a 10% casein diet with 1% histidine were also partially alleviated in rats that were first pretreated with retinol. Activities of histidase, urocanase, and formiminoglutamic acid formiminotransferase (FIGLU transferase) were unaffected by retinol supplementation. The results suggest that retinol supplementation enhances histidine catabolism by exerting a change on one-carbon metabolism.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002244:Carbon / Q000378:metabolism*; D005565:Formiminoglutamic Acid / Q000652:urine; D051042:Glutamate Formimidoyltransferase; D006639:Histidine / Q000378:metabolism*; D006638:Histidine Ammonia-Lyase / Q000378:metabolism; D019877:Hydroxymethyl and Formyl Transferases; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014166:Transferases / Q000378:metabolism; D014559:Urocanate Hydratase / Q000378:metabolism; D014801:Vitamin A / Q000494:pharmacology*
D014801:Vitamin A; D006639:Histidine; D002244:Carbon; D005565:Formiminoglutamic Acid; D014166:Transferases; D019877:Hydroxymethyl and Formyl Transferases; D051042:Glutamate Formimidoyltransferase; D014559:Urocanate Hydratase; D006638:Histidine Ammonia-Lyase