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UPTAKE AND METABOLISM OF 5‐METHYL‐TETRAHYDROFOLIC ACID BY RAT BRAIN SLICES
Author(s) -
Schnell Mercedes,
Ordóñez Luis A.
Publication year - 1977
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1977.tb03933.x
Subject(s) - incubation , metabolism , chemistry , biochemistry , cerebrum , methionine , in vitro , cerebellum , metabolite , sephadex , choline , endocrinology , biology , central nervous system , amino acid , enzyme
— The uptake and metabolism of CH 3 ‐[ 14 C]tetrahydrofolic acid (MTHF) by rat brain was studied in vitro. At physiological concentrations, (10 −10 m ), a small net uptake of the labeled compound was observed in whole brain, as well as in the cerebrum, cerebellum and brain stem slices. The passive diffusion observed in the presence of KCN proceeded slowly, equilibrium being achieved after 120 min. DEAE–Sephadex chromatography of the radioactive labeled material present in the tissue showed that a pseudo‐uptake mechanism was operative. Eighteen percent of the label was found in methionine, and after pre‐incubation with KCN this was reduced to approx 9%. Neither dietary folate deficiency, nor the availability of a methyl group acceptor ( l ‐DOPA), were able to increase the observed pseudo‐uptake. Nevertheless, l ‐DOPA reduced the proportion of label found as unmetabolized MTHF in the slices at the end of the incubation (47% vs 59%) while increasing other (methylated ?) metabolites. The pseudo‐uptake process was not detected in newborn animals; it increased linearly with age, reaching adult levels at 10 days of age. It is suggested that uptake mechanisms are not responsible for maintaining brain folate levels during folate deficiencies in the adult animal.