Modification of hepatic folate metabolism in rats fed excess retinol.
Feeding rats a diet containing 1000 IU of retinol/g diet enhances the folate-dependent oxidation to CO2 of formate and histidine. The activity of hepatic methylenetetrahydrofolate reductase, which plays a critical role in the regulation of liver folate metabolism, is suppressed in these animals, resulting in decreased 5-methyltetrahydrofolate synthesis. This ensures a greater concentration of hepatic tetrahydrofolate, the coenzyme on which formate and histidine oxidation depend, but also compromises the level of S-adenosylmethionine in the liver.
D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D005492:Folic Acid / Q000378:metabolism*; D005561:Formates / Q000378:metabolism; D006639:Histidine / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012435:S-Adenosylhomocysteine / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism; D013763:Tetrahydrofolates / Q000096:biosynthesis / Q000378:metabolism; D014801:Vitamin A / Q000008:administration & dosage / Q000494:pharmacology*; D000099295:Formyltetrahydrofolate Dehydrogenase
D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D002245:Carbon Dioxide; D005492:Folic Acid; D005561:Formates; D006639:Histidine; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D000587:Oxidoreductases Acting on CH-NH Group Donors; D012435:S-Adenosylhomocysteine; D012436:S-Adenosylmethionine; D013763:Tetrahydrofolates; D014801:Vitamin A; D000099295:Formyltetrahydrofolate Dehydrogenase; C030544:formic acid; C030371:5,6,7,8-tetrahydrofolic acid; C005984:5-methyltetrahydrofolate