Avoidance, operant and locomotor behavior in rats with neostriatal injections of kainic acid

Compared with saline injected controls, rats with bilateral injections of kainic acid (KA) in the dorsal neostriatum showed increased locomotor response to d-amphetamine, increased resistance to extinction and impaired acquisition and retention of passive avoidance. The KA injection resulted in loss of local neurons in the dorsal neostriatum, with no appreciable damage either to dopaminergic terminals or to extrinsic myelinated axons, thus supporting both the selective neurotoxic action of KA on neuronal perikarya and the proposed similarity of KA-induced neostriatal lesions with those found in the caudate-putamen of patients with Huntington's disease. Although loss of hippocampal neurons was occasionally observed, the behavioral results could not be wholly attributed to hippocampal damage, since rats with no demonstrable extrastriatal lesions were not less impaired than those with hippocampal damage. An altered arousal reaction to stressful situations might account for the learning and memory impairments of the KA neostriatal rats.