Effects of Deficiencies of Folic Acid and Vitamin B12 on Central Nervous System Function and Development

Herbert, Victor; Tisman, Glenn

doi:10.1007/978-1-4684-2667-0_10

Cited by 8 publications

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“…52, 377-380 (1989). opment (McClain and Bridgers, 1970;Herbert and Tisman, 1973) and the identification of a specific transport system for 5-methyltetrahydrofolate at the choroid plexus (Levitt et al, 1971;Chen and Wagner, 1975;Spector and Lorenzo, 1975) has led to the assumption by many that the uptake of 5-methyltetrahydrofolate is an important process in brain and nerve tissue. This would certainly help to explain the devastating effects on such tissues of impaired methionine synthase due either to vitamin Biz deficiency in man or to its inactivation by nitrous oxide in monkeys (Scott et al, 1981).…”

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Source of Methyl Groups in Brain and Nerve Tissue in the Rat

Long

Weir

Scott

1989

Journal of Neurochemistry

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Previous studies that demonstrated that mouse brain accumulated significantly more radioactivity from subcutaneously administered 5-methyltetrahydrofolate labelled in the methyl group compared to the label in the folate moiety are open to two interpretations. The methyl group could have been transferred to another compound (probably methionine) prior to its transport into the brain. Alternatively, if plasma 5-methyltetrahydrofolate per se is significantly involved in the provision of methyl groups to brain and nerve tissue it would be expected that the folate moiety would be returned to the plasma to complete the cycle and thus would appear not to have been taken up. In this article, using competition experiments that exploit the differences in the mechanism of transport of methionine and 5-methyltetrahydrofolate into brain and nerve, evidence is presented that in the rat the methyl group of 5-methyltetrahydrofolate is transported after its conversion to methionine.

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confidence: 99%