This study was supported in part by United States Public Health Service Research Grant DE-02600-04 from the National Institutes of Health, Bethesda, MD.
ALTERATIONS IN NINHYDRIN-POSITIVE SUBSTANCES AND CYTOPLASMIC PROTEIN SYNTHESIS IN THE BRAINS OF ASCORBIC ACID-DEFICIENT GUINEA PIGS1
Version of Record online: 4 OCT 2006
Journal of Neurochemistry
Volume 21, Issue 1, pages 69–78, July 1973
How to Cite
Enwonwu, C. O. (1973), ALTERATIONS IN NINHYDRIN-POSITIVE SUBSTANCES AND CYTOPLASMIC PROTEIN SYNTHESIS IN THE BRAINS OF ASCORBIC ACID-DEFICIENT GUINEA PIGS. Journal of Neurochemistry, 21: 69–78. doi: 10.1111/j.1471-4159.1973.tb04226.x
- Issue online: 4 OCT 2006
- Version of Record online: 4 OCT 2006
- (Received 11 December 1972. Accepted 10 February 1973)
Newly-weaned male guinea pigs were fed an ascorbic acid-deficient diet ad libitum and compared with control animals pair-fed an adequate diet for a similar duration. The ascorbic acid-deficient animals demonstrated prominent elevations in serum concentrations of tyrosine (+427%), phenylalanine (+36%) and arginine (+21 %) with concomitant depressions in levels of glycine (–57 %), histidine (–39 %), ethanolamine (–38%) and glutamic acid (–22 %). With few exceptions, the alterations in the liver amino acid profiles were in the same directions as those observed in the serum. The scorbutic brains showed 28–36 per cent of the retention of total ascorbic acid found in control animals and were characterized by marked elevation (+83%) in tyrosine content, hardly any alteration in phenylalanine (–9%), and depressed levels of histidine (–33 %), arginine (–25%), phosphoserine (–50%) and GABA (–12%). The implications of such abnormal changes in free amino acid patterns were evaluated in the light of the role of some of these amino acids as precursors for the synthesis of neuroregulatory substances. No difference was observed in the brain polysomal profiles as isolated from the two groups of animals. Incubation of polysomes from ascorbic acid-deficient brains with autologous pH 5 enzyme derived from cell sap not passed through Sephadex G-25 revealed low uptake of [14C]phenylalanine in comparison to that for a similar system from control animals. Use of pH 5 enzymes prepared from Sephadex-treated and dialysed cell saps eliminated the difference in specific activities of the two groups of ribosomes, an observation suggesting that ascorbic acid deficiency either intensified the activity of the inhibitory components or reduced the low molecular weight stimulatory substances present under normal conditions in the brain postmicrosomal fraction.