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Journal ArticleDOI

Effect of short-and long-term exposure to low environmental temperature on brain regional GABA metabolism

01 Aug 1990-Neurochemical Research (Kluwer Academic Publishers-Plenum Publishers)-Vol. 15, Iss: 8, pp 815-820
TL;DR: It is suggested that the hypothalamic and striatal GABA system may play a characteristic role in response to short-and long-term exposure to LET, and repeated exposure to Let for 15 or 30 consecutive days enhances GABAergic activity with the stimulation of GABA utilization only in CS without affecting its synthesizing process.
Abstract: Single exposure of adult male rats to low environmental temperature (LET, 12 +/- 0.5 degrees C) for 2 h significantly increased the hypothalamic and striatal GABA levels without affecting those in other regions of brain. The activity of glutamate decarboxylase (GAD) was elevated in hypothalamus (H) and corpus striatum (CS) under these conditions. GABA accumulation rate (measured with ethanolamine-O-sulfate, an inhibitor of GABA-transaminase) was also increased in both H and CS of rats exposed to LET for 2 h. Unlike after a single exposure, the repeated exposure (2 h/day) for 7, 15, and 30 consecutive days did not change the hypothalamic GABA metabolism. No change in GABA metabolism was observed in CS when rats were repeatedly exposed to LET for 7 consecutive days. Prolongation of repeated exposure to LET (2 h/day) for 15 and 30 consecutive days decreased the striatal GABA level and increased the activity of GABA-transaminase, although GAD activity was not altered under these conditions. These results suggest that single exposure to LET accelerates GABA synthesis and may reduce the GABAergic activity in both H and CS; whereas repeated exposure to LET for 15 or 30 consecutive days enhances GABAergic activity with the stimulation of GABA utilization only in CS without affecting its synthesizing process. Thus, it may be suggested that the hypothalamic and striatal GABA system may play a characteristic role in response to short- and long-term exposure to LET.
Citations
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TL;DR: It is suggested that the remission of parkinsonian symptoms by treatment with high-frequency electrical stimulation of theSubthalamic nucleus in humans may primarily reside on its capacity to suppress the action potential activity of subthalamic neurons.

156 citations

Journal ArticleDOI
TL;DR: A significant transient increase in GAD mRNA level in the ipsilateral cortex was observed 4 days after the lesion, which may be part of a long term adaptive functional alteration and changes in the gene expression of the cerebral cortex following focal cortical injury.
Abstract: In situ hybridization histochemistry (ISHH) was used to study the expression of glutamic acid decarboxylase (GAD) mRNA changes in the rat cerebral cortex following unilateral frontal and somatosensory cortical lesion by devascularisation. 4 days after the lesion, a significant transient increase in GAD mRNA level in the ipsilateral cortex was observed when compared with contralateral, ipsi-sham operated and ipsi-normal control cortices. The change occurred throughout the ipsilateral neocortex, with no significant difference between the magnitude of increase in frontal, parieto-occipital, parieto-temporal, cingulate or retrosplenial areas; no obvious change was seen in pyriform, entorhinal or hippocampal cortices. This unexpected GAD mRNA increase in neocortex may be part of a long term adaptive functional alteration and changes in the gene expression of the cerebral cortex following focal cortical injury.

22 citations


Cites background from "Effect of short-and long-term expos..."

  • ...1989) and short and long term low enviromental temperature (Biswas and Poddar 1990)....

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Journal ArticleDOI
TL;DR: It is suggested that the previously known types of interhemispheric asymmetry—biochemical, neurophysiological, and organoelement—are based on differences in the intensity of energy-consuming processes in the cerebral hemispheres.
Abstract: The field potential and temperature of the cerebral cortex were studied in right-handed, left-handed, and ambidextrous rats. Temperature asymmetry of the cerebral hemispheres was revealed, which proved to differ in rats with different types of interhemispheric asymmetry: the interhemispheric temperature gradient was maximal in left-handed rats, minimal in right-handed rats, and intermediate in ambidextrous rats. Both parameters of energy metabolism (field potential and temperature of the cerebral cortex) correlated with one another, and the structure of these statistically significant correlations was different in right-handed, left-handed, and ambidextrous rats. It is suggested that the previously known types of interhemispheric asymmetry—biochemical, neurophysiological, and organoelement—are based on differences in the intensity of energy-consuming processes in the cerebral hemispheres.
References
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Journal Article
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.

289,852 citations

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TL;DR: Changes in NE turnover regulation induced by electric foot shocks were studied in various conditions and there was an enhanced turnover of NE in the brainstem-mesencephalon when higher intensities of stimulation were used; this was associated with an increased accumulation of H 3 -normetanephrine.
Abstract: The effect of stress on the metabolism of norepinephrine (NE), dopamine and serotonin (5-hydroxytryptamine; 5HT) in the central nervous system of the rat has been examined. Estimations of turnover of NE have been made by following the changes in NE specific activity after labeling the endogenous stores of NE by intracisternal injection of H 3 -NE. Stress induced by mild electric shocks to the feet did not significantly affect the endogenous content of NE but did markedly increase the turnover of this amine in central NE-containing neurons, mainly in the brainstem-mesencephalon and in the spinal cord. The disappearance of H 3 -dopamine in the striatum and brainstem-mesencephalon was not affected under these conditions. This stress increased the synthesis of 5HT in the brainstem-mesencephalon as seen by the greater increase of endogenous 5HT after monoamine oxidase inhibition but did not affect the disappearance of intracisternally administered H 3 -5HT. Changes in NE turnover regulation induced by electric foot shocks were studied in various conditions. There was an enhanced turnover of NE in the brainstem-mesencephalon when higher intensities of stimulation were used; this was associated with an increased accumulation of H 3 -normetanephrine; no modification was seen when the frequency of stimulation was increased. NE turnover during an acute stress session was enhanced to a greater degree when rats were previously subjected to many stress sessions. The initial accumulation of H 3 -NE in the brainstem-mesencephalon was decreased just after an acute stress and increased 24 hr after the last electric shock stress session of a chronic stress treatment.

408 citations

Journal Article
TL;DR: Findings indicate that the increased sympathetic stimulation, presumably associated with such stressful conditions, induces increased synthesis of norepinephrine and epinephrine and the regulatory mechanism most likely operates at the tyrosine hydroxylase step, which is ratelimiting.
Abstract: When rats were exercised or exposed to cold, the levels of norepinephrine in heart, spleen and brain showed little change. Appreciable decreases were observed in adrenal epinephrine following severe exercise. However, when the tyrosine hydroxylase inhibitor, α-methyl-tyrosine, was administered prior to the exercise or exposure to cold, norepinephrine and epinephrine levels fell markedly in most tissues. Furthermore, incorporation of radioactivity from administered tyrosine-C14 into norepinephrine and epinephrine was increased 2-to 3-fold as a result of exercise. These findings indicate that the increased sympathetic stimulation, presumably associated with such stressful conditions, induces increased synthesis of norepinephrine and epinephrine. The regulatory mechanism most likely operates at the tyrosine hydroxylase step, which is ratelimiting.

338 citations

Journal ArticleDOI
TL;DR: It has been found that certain amino acids and indole derivatives, when allowed to react with ninhydrin at an alkaline pHS, form highly fluorescent products that can be measured in as little as 3 ,ug dry weight of brain tissue.
Abstract: THE uniquely high activity of glutamic decarboxylase (GDC)? in brain has been reported (ROBERTS, 1950; WINGO and AWAPARA, 1950). ROBERTS (1956), using pooled tissues, has shown that there is a fiveto six-fold greater activity of GDC in grey matter than in white matter of the cat brain. Because of the limitations of the manometric methods used, further resolution of the cytoarchitectonic distribution of GDC has awaited the development of more sensitive analytical methods for measuring the activity of this enzyme. It has been found that certain amino acids and indole derivatives, when allowed to react with ninhydrin at an alkaline pHS, form highly fluorescent products. Of the substances tested, under the conditions to be described, y-aminobutyric acid (yAB) has given the greatest amount of fluorescence and can be measured at a concentration of lo-' M. A fluorescence method has been developed to measure the activity of GDC in as little as 3 ,ug dry weight of brain tissue. The activity of this enzyme has been measured in various areas of the monkey and rabbit brain as well as in the whole brain of mouse and rat. The histochemical distribution of GDC in the layers of the monkey cerebellar cortex and selected white tracts of the rabbit and rat has also been determined. White matter has been shown to be extremely poor in GDC.

311 citations


"Effect of short-and long-term expos..." refers methods in this paper

  • ...GABA was measured from the deproteinized supernatant spectroflnorometrically at an excitation and emission wavelength of 377 and 451 nm respectively, by the method of Lowe et al [29]....

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Journal Article
TL;DR: By various techniques it could be demonstrated that the stress of foot shock accelerates the metabolism of dopamine and serotonin to the same degree as norepinephrine; the only difference being that serotonin and dopamine are rapidly resynthesized, whereas nore Alpinephrine in the brain cannot be regenerated at the same rate.
Abstract: The stress of foot shock in rats induces large decreases in the level of brain norepinephrine but does not greatly alter the concentration of serotonin or dopamine in brain. These decrements in norepinephrine are not limited to any region and occur uniformly throughout the brain. However, absolute levels of these amines are not a true indicator of their dynamic state. By various techniques it could be demonstrated that the stress of foot shock accelerates the metabolism of dopamine and serotonin to the same degree as norepinephrine; the only difference being that dopamine and serotonin are rapidly resynthesized, whereas norepinephrine in the brain cannot be regenerated at the same rate. Furthermore, the increased catabolism of brain norepinephrine with stress is blocked by monoamine oxidase inhibitors, whereas catechol-O-methyltransferase inhibitors do not impede accelerated degradation.

291 citations