L-methionine uptake by human cerebral cortex: Maturation from infancy to old age

L. A. O'Tuama, P. C. Phillips, Q. R. Smith, Y. Uno, R. F. Dannals, A. A. Wilson, H. T. Ravert, S. Loats, H. A. Loats, H. N. Wagner

Research output: Contribution to journalArticlepeer-review

Abstract

Age-associated changes in amino acid transport from blood to normal frontal cortex were studied using positron emission tomography (PET). Seventeen patients, 1.8-71 yr, were injected intravenously with tracer doses of [11C]L-methionine and a baseline PET scan was obtained. To assess competitive inhibition of [11C]L-methionine uptake, patients received either oral L-phenylalanine or an i.v. infusion of amino acids 1 hr before a second PET study. Uptake of [11C]L-methionine by frontal cortex decreased seven-fold between 1.8 and 71 yr (r = -0.71; p < 0.05). Blood-to-brain transfer of [11C]L-methionine, at 4.5 yr, exceeded mean adult values by more than five-fold. Competitive inhibition reduced L-methionine uptake in all patients older than 4.6 yr. These developmental changes parallel findings in animals. The neutral amino acid transport system may modulate human brain amino acid levels to meet changing developmental metabolic needs.

Original languageEnglish (US)
Pages (from-to)16-22
Number of pages7
JournalJournal of Nuclear Medicine
Volume32
Issue number1
StatePublished - 1991

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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