Microinjection of a glutamate antagonist into the nucleus accumbens reduces psychostimulant locomotion in rats

In order to study a possible modulatory effect of glutamatergic afferents to the nucleus accumbens (NAC) on psychostimulant-induced locomotion, L-glutamic acid diethyl ester (GDEE), a glutamate antagonist, was injected in the NAC of rats acutely treated with cocaine, amphetamine or caffeine. GDEE at the doses of 5, 10, and 20 micrograms/side significantly reduced locomotion induced by cocaine (20 mg/kg, i.p.). Amphetamine-induced hyperactivity was also reduced by GDEE, whereas caffeine-induced hyperactivity was not significantly decreased by GDEE. This suggests that glutamatergic afferents to the NAC modulate the effects of psychostimulants and also dopamine function in the mesolimbic system.