The direction of apomorphine-induced rotation behavior is dependent on the location of excitotoxin lesions in the rat basal ganglia.

Adult rats received unilateral kainic acid (KA) lesions of the striatum with the anterior/posterior coordinates of the lesion at either 1.5 mm or 0.3 mm anterior to bregma. Four to six weeks after the lesion rats were placed in an open field environment and injected with apomorphine (1 mg/kg, s.c.). Rats receiving the more posterior lesion (0.3 mm) rotated ipsilateral to the lesioned side of the brain. In contrast, the majority of rats receiving the more anterior (1.5 mm) placement of the lesion rotated contralateral to the lesioned side of the brain. Histological analysis of several animals receiving posterior lesions revealed damage to the hippocampus and thalamus that was not seen in the animals receiving anterior lesions. Our results are consistent with the hypothesis that the direction of apomorphine-induced rotation after excitotoxin injection into the rat basal ganglia is dependent on the location of the lesion.