Hyperthermia influences excitatory and inhibitory amino acid neurotransmitters in the central nervous system. An experimental study in the rat using behavioural, biochemical, pharmacological, and morphological approaches |
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Authors: | H S Sharma |
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Institution: | (1) Laboratory of Cerebrovascular Research, Department of Surgical Sciences, Anaesthesiology and Intensive Care Medicine, University Hospital, Uppsala University, Uppsala, Sweden |
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Abstract: | Summary. Role of excitatory amino acids, glutamate, aspartate, and inhibitory amino acids, gamma aminobutyric acid (GABA) and glycine
in brain damage caused by heat stress was examined in a rat model. Subjection of rats to 4 h heat stress at 38°C in a biological
oxygen demand (BOD) incubator resulted in a marked increase in glutamate and aspartate in some brain regions, whereas a significant
decline in GABA and glycine was observed in several brain areas. Profound behavioural alterations and impairment of motor
and cognitive functions were seen at this time. Breakdown of the blood–brain barrier (BBB), reduction in regional cerebral
blood flow (CBF), edema formation and cell injuries are prominent in several parts of the brain. Pretreatment with multiple
opioid receptor antagonist, naloxone (10 mg/kg, i.p.) significantly restored the heat stress induced decline in GABA and glycine
and thwarted the elevation of glutamate and aspartate in various brain areas. The motor or cognitive deficits were also attenuated.
A significant reduction in BBB permeability, cerebral blood flow abnormalities, edema formation and cell injuries was evident.
These novel observations suggest that (i) glutamate, aspartate, GABA and glycine are involved in the pathophysiology of heat
stress, and (ii) a balance between excitatory and inhibitory amino acids in brain is crucial in hyperthermia induced brain
injuries or repair. |
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Keywords: | : Hyperthermia brain injury naloxone blood– brain barrier permeability brain edema formation cell injury glutamate GABA glycine aspartate amino acids neurotransmitters Evans blue lanthanum motor function foot print analysis rota-rod performances |
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