Physiological studies on the effects of nutritional imbalance on the central nervous system. II. Effects of thiamine deficiency on oxidative enzymes in the brain of chicken,Gallus domesticus

Summary The activity levels of succinate dehydrogenase, glutamate dehydrogenase and pyruvate dehydrogenase in the fore, mid and hind brain regions of the thiamine deficient chicken,Gallus domesticus were determined. The activity levels of scccinate dehydrogenase and glutamate dehydrogenase in all the 3 regions of brain showed augmentation on inducing thiamine deficiency. In contrast the activity levels of pyruvate dehydrogenase decreased in the brain of thiamine deficient animals. It is suggested that these changes in the oxidative enzymes indicate disturbance caused in the operation of the tricarboxylic acid cycle in thiamine deficiency.     

Pharmakologische Untersuchungen bei Thiaminmangel I. Änderungen des Katecholamingehalts im Gewebe

Summary (1) The increased tissue catecholamine level of the thiamine deficient rat was shown in the atrium, the ventricle, the brain cortex and in the spleen but not in the brain stem and the adrenal gland. (2) The increased response to tyramine of the thiamine deficient heart is most probably due to the high catecholamine level caused by thiamine deficiency. (3) The increased catecholamine content in the thiamine deficient rat does not result from the increased pyruvic acid.

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Herrn Professor Dr.F. Th. von Brücke zum 60. Geburtstag im Januar 1968 gewidmet.     

Effect of tea consumption on the levels ofα-ketoglutarate and pyruvate dehydrogenase in rat brain

Summary Administration of tea to rats fed on a normal diet results in a marked drop in brain levels of total thiamine as well as of -ketoglutarate and pyruvate dehydrogenase activities. The patterns of decrease in both enzyme activities are similar to that of total thiamine content; they drop to about 65% of the control at 14–20 weeks after continuous consumption of tea.Supported by a grant from the International Foundation for Science (IFS), Sweden.     

Assimilation of ammonia and growth of biotin deficient Aspergillus nidulans.

Biotin deficiency in Aspergillus nidulans has been found to increase the uptake of ammonium ions, associated with a marked increase in the activity of NADP-linked glutamate dehydrogenase, which is found to be the major route of ammonia assimilation in this culture. The results obtained are discussed with respect to the growth of Aspergillus nidulans during biotin deficiency.     

Lactate dehydrogenase and glutamate dehydrogenase activities in the circumventricular organs of rat brain following neonatal monosodium glutamate

Glutamate (glu) an excitatory neurotransmitter amino acid, is present in high concentrations in the mammalian central nervous system and is the most abundant amino acid in our daily diet. In the present study the activities of lactate dehydrogenase (LDH) and glutamate dehydrogenase (GDH) were evaluated in the circumventricular organs (CVO) of the brain in 25-day-old rats following MSG administration at a dose of 4 mg/g b.wt during the first ten days of life. The results show the LDH activity increased to 265% of that in the control (p<0.001), whereas GDH activity was significantly decreased (p<0.05), The great elevation in LDH, a cytoplasmic marker enzyme, is apparently due to cytoskeletal changes brought about as a consequence of glu toxicity, whereas lowered GDH activity indicates altered glu homostasis in the blood-brain-barrier deficient areas following neonatal exposure to glu.     

Mitochondrial abnormalities in fibroblast line GM3093 defective in oxidative metabolism

Fibroblast line GM3093 deficient in the activity of the pyruvate dehydrogenase complex, was derived from a patient reported to have an inherited defect affecting the tricarboxylic acid cycle. Our results suggest a generalized defect consisting of few and abnormal mitochondria and low activities of all mitochondrial enzymes examined.     

In vivo effects of Sumithion on tissue respiration and enzyme activity in the fish,Etroplus maculatus

Summary LD₅₀ exposure of a teleost fish.Etroplus maculatus, to Sumithion depressed the rate of oxygen consumption, concomitantly with an inhibition in succinate dehydrogenase activity in the tissues, in the order gill>brain>liver>muscle. The effect of the same pesticide on the activity of acetylcholinesterase was quite interesting, with a maximal inhibitory effect on the brain followed by liver, muscle and gill, suggesting a tissue specificity, and a differential sensitivity of the enzyme towards the pesticide.I wish to express may gratitude to Dr K. Sasira Babu and Dr J. Hemalatha for their valuable discussions and encouragement.     

Toxic effects of methylmercury on spermatozoa in vitro

In an in vitro investigation, methylmercury (MeHg) reduced the motility of rat spermatozoa probably by the inhibition of succinate dehydrogenase and ATPase activities. Concomitant morphological changes observed in the spermatozoa were coiled tails and kinks in midpiece and tail regions.     

Toxic effects of methylmercury on spermatozoa in vitro

Summary In an in vitro investigation, methylmercury (MeHg) reduced the motility of rat spermatozoa probably by the inhibition of succinate dehydrogenase and ATPase activities. Concomitant morphological changes observed in the spermatozoa were coiled tails and kinks in midpiece and tail regions.     

Assimilation of ammonia and growth of biotin deficientAspergillus nidulans

Summary Biotin deficiency inAspergillus nidulans has been found to increase the uptake of ammonium ions, associated with a marked increase in the activity of NADP-linked glutamate dehydrogenase, which is found to be the major route of ammonia assimilation in this culture. The results obtained are discussed with respect to the growth ofAspergillus nidulans during biotin deficiency. J. D. Desai gratefully acknowledges the receipt of a research fellowship from the Government of India, Department of Atomic Energy, Bombay.     

Thiamine pyrophosphate: An essential cofactor for the α-oxidation in mammals – implications for thiamine deficiencies?

The identification of 2-hydroxyphytanoyl-CoA lyase (2-HPCL), a thiamine pyrophosphate (TPP)-dependent peroxisomal enzyme involved in the α-oxidation of phytanic acid and of 2-hydroxy straight chain fatty acids, pointed towards a role of TPP in these processes. Until then, TPP had not been implicated in mammalian peroxisomal metabolism. The effect of thiamine deficiency on 2-HPCL and α-oxidation has not been studied, nor have possible adverse effects of deficient α-oxidation been considered in the pathogenesis of diseases associated with thiamine shortage, such as thiamine-responsive megaloblastic anemia (TRMA). Experiments with cultured cells and animal models showed that α-oxidation is controlled by the thiamine status of the cell/tissue/organism, and suggested that some pathological consequences of thiamine starvation could be related to impaired α-oxidation. Whereas accumulation of phytanic acid and/or 2-hydroxyfatty acids or their α-oxidation intermediates in TRMA patients given a normal supply of thiamine is unlikely, this may not be true when malnourished. Received 23 December 2005; received after revision 10 April 2006; accepted 28 April 2006     

Effect of 3,5,3′-tri-iodothyronine on cellular growth and oxygen consumption in neonatal rat brain

Summary The effect of thyroid deficiency and treatment with tri-iodothyronine (T₃) on oxygen consumption by neonatal (6-day-old and 15-day-old) rat brain was examined using glutamate, -hydroxybutyrate, succinate and ascorbate+TMPD as substrates. The respiration rates decreased significantly in 15-day-old hypothyroid pups. Treatment of normal and of hypothyroid pups with T₃ resulted in a significant increase in the respiration rate at both ages. Respiration rates with glucose as the substrate were not affected under these conditions.     

Utilization of ascorbic acid during post-embryonic development of chick skeletal muscle.

Ascorbic acid is utilized during the post-embryonic differentiation of skeletal muscle fibres in chick. While the fibres lose their heterogeneity with regard to ascorbic acid, they continue to exhibit differences in their metabolic rates in terms of the succinate dehydrogenase activity throughout life.     

Mitochondrial abnormalities in fibroblast line GM3093 defective in oxidative metabolism

Summary Fibroblast line GM3093 deficient in the activity of the pyruvate dehydrogenase complex, was derived from a patient reported to have an inherited defect affecting the tricarboxylic acid cycle. Our results suggest a generalized defect consisting of few and abnormal mitochondria and low activities of all mitochondrial enzymes examined.Preliminary reports of aspects of this work appeared as abstracts in Trans. Am. Soc. Neurochem.15 (1984) 178, and Soc. Neurosci.10 (1984) 996.Developmental and Metabolic Neurology Branch.Surgical Neurology Branch.     

Glutamine synthetase activity in subdivisions of brain of the shark, Squalus acanthias

Specific activity of glutamine synthetase in Squalus acanthias (spiny dogfish) central nervous system regions was highest in the cerebellum and lowest in the spinal cord. The levels of activity may relate to the excitability of each region by regulating the glutamate pool.     

The adequacy of thiamine in liquid diets used in animal models of alcoholism

Summary The effects of chronic administration of 2 types of liquid diets on brain thiamine pyrophosphate (TPP) levels have been investigated. With the Lieber-DeCarli diet, rats in the control group had significantly lower TPP levels compared with those of the ethanol group. The Nutrament diet used in mice was apparently adequate in the thiamine supply.Acknowledgment. The authors are thankful to Dr Hebe Greizerstein for her review and comments on this mansucript.     

Possible role of intestinal alkaline phosphatase activity in thiamine transport.

Thiamine deficiency caused a marked decrease of intestinal alkaline phosphatase (al-Pase) activity, but had no effect on the Ca++-ATPase activity and Ca++-absorption in rats. The al-Pase activity was significantly decreased 1 h after oral administration of ethanol at 0.5 and 2.5 g/kg. In contrast, Mg++-, Ca++-and (Na+ + K+)-ATPase activities did not change after the administration of ethanol. These findings show that the al-Pase activity, unlike the Ca++-ATPase activity, is not related to Ca++-absorption. A possible role of al-Pase activity in the active transport of thiamine in the intestine was discussed.     

Folding and assembly defects of pyruvate dehydrogenase deficiency-related variants in the E1α subunit of the pyruvate dehydrogenase complex

The pyruvate dehydrogenase complex (PDC) bridges glycolysis and the citric acid cycle. In human, PDC deficiency leads to severe neurodevelopmental delay and progressive neurodegeneration. The majority of cases are caused by variants in the gene encoding the PDC subunit E1α. The molecular effects of the variants, however, remain poorly understood. Using yeast as a eukaryotic model system, we have studied the substitutions A189V, M230V, and R322C in yeast E1α (corresponding to the pathogenic variants A169V, M210V, and R302C in human E1α) and evaluated how substitutions of single amino acid residues within different functional E1α regions affect PDC structure and activity. The E1α A189V substitution located in the heterodimer interface showed a more compact conformation with significant underrepresentation of E1 in PDC and impaired overall PDC activity. The E1α M230V substitution located in the tetramer and heterodimer interface showed a relatively more open conformation and was particularly affected by low thiamin pyrophosphate concentrations. The E1α R322C substitution located in the phosphorylation loop of E1α resulted in PDC lacking E3 subunits and abolished overall functional activity. Furthermore, we show for the E1α variant A189V that variant E1α accumulates in the Hsp60 chaperonin, but can be released upon ATP supplementation. Our studies suggest that pathogenic E1α variants may be associated with structural changes of PDC and impaired folding of E1α.     

Enzyme activities of a cold-resistant L cell variant

Summary Resistance of mouse L cells to cold increased the activity of nonspecific esterase, acid phosphatase and adenosine triphosphatase, but did not influence the activity of succinate dehydrogenase.