Amphetamine increases the extracellular concentration of glutamate in striatum of the awake rat: involvement of high affinity transporter mechanisms

Using microdialysis it was found that intracerebral infusions of amphetamin e increase the extracellular concentration of glutamate, and also of dopami ne, aspartate, GABA, and taurine. The increases in glutamate produced by am phetamine was independent of calcium in the perfusion medium but was signif icantly attenuated by specific blockers of the high affinity transporters o f this neurotransmitter. Amphetamine infusions also produced a decrease in the extracellular concentration of Na+ an increase in the extracellular con centration of lactate, and a decrease in haemoglobin in the area of perfusi on. All these data suggest that amphetamine increases the extracellular con centration of glutamate and other neurotransmitters through a hypoxic media ted process. This study also shows that an alpha-noradrenergic receptor ant agonist is able to attenuate the effects of amphetamine on the release of g lutamate, dopamine, GABA and taurine, which further suggests a vasoconstric tor effect of amphetamine as a result of which hypoxia could develop. (C) 1 999 Elsevier Science Ltd. All rights reserved.