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ENHANCED CEREBRAL PROTEIN SYNTHESIS IN DEVELOPING HYPOTHYROID RATS: EVIDENCE FOR DELAYED MATURATION
Author(s) -
Gonzales Linda W.,
Geel Stanley E.
Publication year - 1978
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.1471-4159.1978.tb06248.x
Subject(s) - leucine , medicine , endocrinology , euthyroid , amino acid , thyroid , metabolism , protein biosynthesis , hormone , protein metabolism , biology , chemistry , biochemistry
(1) Neonatal hypothyroidism resulted in a 40% increase in the incorporation of [ 14 C]leucine into protein by cerebral cortical slices from 25‐day‐old rats. The uptake of the [ 14 C]‐labelled amino acid into the acid‐soluble free amino acid pool was similar in hypothyroid and control groups which excluded the possibility that transport differences contributed to the observed differences in incorporation. (2) The conversion of [ 14 C]leucine in the free amino acid pool to other metabolites was substantially greater in the hypothyroid state compared to euthyroid controls. (3) The correction of the incorporation data for radioactivity associated with [ 14 C]leucine in the precursor pool, provided an estimate of cerebral protein synthetic rate which was markedly higher in thyroid hormone‐deficient‐rats compared to litter mate controls. (4) The administration of L‐thyroxine to hypothyroid animals for two successive days essentially returned the accelerated metabolism of the precursor pool leucine to normal but failed to ameliorate the increased incorporation into protein. (5) Incubations conducted in the presence of high exogenous leucine levels, to eliminate possible differences in intracellular free amino acid pool size, provided additional evidence for an increased rate of cerebral protein synthesis in 25‐day‐old hypothyroid rats compared to controls. (6) The results are compatible with a retardation in the normal developmental decline in the rate of cerebral protein synthesis associated with hypothyroidism.