Effects of amphetamine on the release of excitatory amino acid neurotransmitters in the basal ganglia of the conscious rat

Abstract

The effects of systemic injections of amphetamine sulfate on the release of aspartic acid, glutamic acid, and glutamine were studied using a push–pull perfusion system in the conscious rat. Amphetamine produced a dose-related increase of the extracellular levels of aspartic acid and glutamic acid. The mean time effect of amphetamine was 40 min, followed by a recovery to baseline levels. The mean percentage increase in amino acids released by the highest dose of amphetamine (5 mg/kg) was as follows: Asp, 334.6%; Glu, 224.5%; and Gln, 317.6%. All these effects were blocked by the dopamine D1–D2 receptor blocker haloperidol. It is suggested that dopamine, released by amphetamine, induces the release of amino acid neurotransmitters in the neostriatum. In addition, it is proposed that dopamine could mediate the neurotoxic effects produced by amphetamines through their secondary action on the release of excitatory amino acids.Key words: amphetamine, dopamine, excitatory amino acids, neostriatum, conscious rat.