CHOLINE DEFICIENCY AND METHOTREXATE TREATMENT INDUCES MARKED BUT REVERSIBLE CHANGES IN HEPATIC FOLATE CONCENTRATIONS, SERUM HOMOCYSTEINE AND DNA METHYLATION RATES IN RATS

Objective: The study compared the effects of feeding rats a choline de ficient (CD) diet or injecting low doses of methotrexate (MTX) on hepa tic folate concentration and distribution, homocysteine (Hcy) concentr ation and DNA methylation. Methods: Thirty rats were divided into thre e groups and were fed either a choline sufficient (CS) or deficient di et (CD), or injected with low doses of MTX (0.1 mg/kg/day) for 2 weeks . Half the animals of each group were sacrificed and the remaining CD and MTX animals were fed repletion diets without methotrexate administ ration for two additional weeks. Results: CD or MTX resulted in a sign ificantly lower folate concentrations (25-50%) compared to the control group. Folate distribution in the treated animals was associated with elongation of the glutamate chains: higher proportion of hexa (from 1 4%, control, to 35%, choline, p < 0.05), hepta (from 5% to 16%, p < 0. 05), and appearance of octaglutamyl folates. MTX administration result ed in a similar pattern of hepatic folate distribution. Two weeks foll owing the MTX administration and the restoration of an adequate cholin e diet for 2 weeks restored the hepatic folate levels to the control a nimals. Conclusions: Results are discussed based on the possibility th at CD and MTX treatment appear to impair the capacity of tissues to in corporate folate in only 2 weeks and affect other biomarkers of one-ca rbon metabolism such as Hcy concentration and DNA methylation. This ad verse picture was partially reversed in a relative short time by simpl y feeding an adequate CS diet and discontinuing MTX injections.