Abstract
This study was designed to determine how the brain, in contrast to most other tissues, maintains an almost normal protein content during a period of dietary protein deficiency. Administration of leucine-3H to rats was started during a period of early development (6-18 days) which is characterized by disproportionately rapid brain growth; later (24-33 days) leucine-14C was administered, when brain growth diminishes but total body weight gain continues to be rapid. At 35 days of age the ratio of 3H:14C in cerebrum, cerebellum, and brain stem protein averaged between 1.63 and 1.82. In skeletal muscle, liver, myocardium, and intestinal mucosa the mean 3H:14C was 1.07 or less. Then, a diet containing either 26% or 3.4% protein was administered. In animals fed the 26% protein diet, 3H:14C in the three brain segments remained essentially unchanged over a 42 day period. In contrast, in the 3.4% protein group 3H:14C in brain decreased to values approaching those of other tissues in the body: cerebrum, 1.18; cerebellum, 1.20; and brain stem, 1.16. The results suggest that conservation of brain protein is not due entirely to the long life-span of its cellular components or to efficient reutilization of the products of protein catabolism but through utilization of amino acids from degradation of protein elsewhere in the body.
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Selected References
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- BALLOU J. E., THOMPSON R. C. Studies of metabolic turnover with tritium as a tracer. V. The predominantly non-dynamic state of body constituents in the rat. J Biol Chem. 1956 Dec;223(2):795–809. [PubMed] [Google Scholar]
- Benton J. W., Moser H. W., Dodge P. R., Carr S. Modification of the schedule of myelination in the rat by early nutritional deprivation. Pediatrics. 1966 Nov;38(5):801–807. [PubMed] [Google Scholar]
- DAVISON A. N. Metabolically inert proteins of the central and peripheral nervous system, muscle and tendon. Biochem J. 1961 Feb;78:272–282. doi: 10.1042/bj0780272. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dallman P. R., Schwartz H. C. Myoglobin and cytochrome response during repair of iron deficiency in the rat. J Clin Invest. 1965 Oct;44(10):1631–1638. doi: 10.1172/JCI105269. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gan J. C., Jeffay H. Origins and metabolism of the intracellular amino acid pools in rat liver and muscle. Biochim Biophys Acta. 1967 Nov 28;148(2):448–459. doi: 10.1016/0304-4165(67)90141-9. [DOI] [PubMed] [Google Scholar]
- Graystone J. E., Cheek D. B. The effects of reduced caloric intake and increased insulin-induced caloric intake on the cell growth of muscle, liver, and cerebrum and on skeletal collagen in the postweanling rat. Pediatr Res. 1969 Jan;3(1):66–76. doi: 10.1203/00006450-196901000-00009. [DOI] [PubMed] [Google Scholar]
- HINRICHS H. R., PETERSEN R. O., BASERGA R. INCORPORATION OF THYMIDINE INTO DNA OF MOUSE ORGANS. Arch Pathol. 1964 Sep;78:245–253. [PubMed] [Google Scholar]
- KERPEL-FRONIUS E., FRANK K. Einige Besonderheiten der Körperzusammensetzung und Wasserverteilung bei der Säuglingsatrophie. Ann Paediatr. 1949 Nov;173(5):321–330. [PubMed] [Google Scholar]
- Kosterlitz H. W. The effects of changes in dietary protein on the composition and structure of the liver cell. J Physiol. 1947 Jun 2;106(2):194–210.1. [PMC free article] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- MENDES C. B., WATERLOW J. C. The effect of a low-protein diet, and of refeeding, on the composition of liver and muscle in the weanling rat. Br J Nutr. 1958;12(1):74–88. doi: 10.1079/bjn19580011. [DOI] [PubMed] [Google Scholar]
- Schimke R. T., Ganschow R., Doyle D., Arias I. M. Regulation of protein turnover in mammalian tissues. Fed Proc. 1968 Sep-Oct;27(5):1223–1230. [PubMed] [Google Scholar]
- Waterlow J. C., Stephen J. M. The effect of low protein diets on the turn-over rates of serums, liver and muscle proteins in the rat, measured by continuous infusion of L-[14C]lysine. Clin Sci. 1968 Oct;35(2):287–305. [PubMed] [Google Scholar]
- Winick M., Noble A. Cellular response in rats during malnutrition at various ages. J Nutr. 1966 Jul;89(3):300–306. doi: 10.1093/jn/89.3.300. [DOI] [PubMed] [Google Scholar]
