ENHANCEMENT OF AMPHETAMINE-INDUCED LOCOMOTOR-ACTIVITY AND DOPAMINE RELEASE IN NUCLEUS-ACCUMBENS FOLLOWING EXCITOTOXIC LESIONS OF THE HIPPOCAMPUS

This study tested the hypothesis that the hippocampus modulates dopami ne-dependent function of the nucleus accumbens using behavioural and n eurochemical evidence. Rats with bilateral lesions of the hippocampus induced by colchicine and kainic acid exhibited equivalent levels of s pontaneous locomotor activity but a potentiation of the hyperactivity produced, dose-dependently, by D-amphetamine measured in photo-cell ac tivity cages. The same rats subsequently received unilateral implantat ions of a microdialysis probe aimed at the nucleus accumbens and showe d elevated levels of extracellular dopamine in response to D-amphetami ne but no significant difference in basal values in comparison with sh am-operated controls. The results are discussed in terms of functional interactions between the hippocampus and nucleus accumbens involving the control of mesolimbic dopamine release.