Increases in glutamate release in the nucleus accumbens in rats with lesions to the hippocampal formation during an emotional conditioned response.

Intracerebral dialysis was used in living animals, along with high-performance liquid chromatography with electrochemical detection, to study glutamate release into the intercellular space of the nucleus accumbens during an emotional conditioned response in rats with lesions to the hippocampal glutamatergic input to this structure. Bilateral lesioning of the hippocampal formation with ibotenic acid worsened the emotional conditioned response during its acquisition and performance, and led to increases in glutamate release into the intercellular space of the nucleus accumbens. This is the first report to demonstrate that lesions to synaptic glutamatergic transmission in the nucleus accumbens lead to compensatory increases in volume glutamatergic transmission in this area of the brain.