IBOTENIC ACID LESION OF THE VENTRAL HIPPOCAMPUS DIFFERENTIALLY AFFECTS DOPAMINE AND ITS METABOLITES IN THE NUCLEUS-ACCUMBENS AND PREFRONTAL CORTEX IN THE RAT

To determine the influence of neurons of the ventral hippocampus on dopamine (DA) turnover in other limbic areas, spontaneous and amphetamine-induced locomotion as well as DA and its metabolites were assayed in nucleus accumbens, medial prefrontal cortex and anteromedial striatum, 14 and 28 days after bilateral ibotenic acid (IA) or sham lesions of the ventral hippocampus in the rat. Spontaneous locomotion was increased 28 days postoperatively, while D-amphetamine induced locomotion was augmented both 14 and 28 days postoperatively in IA lesioned animals. DA levels in the nucleus accumbens were decreased on the 14th, but increased on the 28th day after the lesion. Dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and the DOPAC/DA ratio in the medial prefrontal cortex (MPFC) were reduced 28 days postoperatively. Moreover, there was a significant negative correlation between the DOPAC/DA ratio in the MPFC and DA levels in the nucleus accumbens at this time point. These data indicate that a lesion of the ventral hippocampus can produce differential changes in cortical and limbic DA activity. Implications for an animal model of schizophrenia are considered.