Conditioned reflex release of dopamine in the nucleus accumbens after disruption of the hippocampal formation in rats.

Vital intracerebral microdialysis combined with HPLC with electrochemical detection was used to study changes in dopamine release in the nucleus accumbens during the development and realization of an emotional conditioned response in hooded rats with lesions to the hippocampal formation. These studies showed that one month after bilateral administration of ibotenic acid into the hippocampal formation, rats had weakened emotional responses to contextual stimuli. The process of development of the conditioned reflex was accompanied by higher-level and longer-lasting release of dopamine in the nucleus accumbens than in sham-operated rats. Dopamine release levels in the nucleus accumbens during realization of the conditioned reflex to contextual stimuli in rats with hippocampal lesions and sham-operated rats were identical.