Acute hyperkinesia after hypothalamic lesions: A comparison of the time course, level, and type of hyperkinesia induced by ventromedial and lateral hypothalamic lesions in rats

Abstract

Postoperative hyperkinesia induced by ventromedial (VMH) and lateral hypothalamic (LH) lesions was compared in two experiments. In the first experiment overall motility of the animals was monitored continuously for 20 h after the lesions. Both LH and VMH lesions were found to cause comparably high levels of activity in the first 10 h after the lesion. In the next 10 h VMH rats were more active than LH rats. In a second experiment a detailed analysis of the behaviors displayed by rats with VMH or LH lesions at 4, 8, and 24 h after the lesions revealed that different behavioral components contributed to the overall hyperactivity in the two cases, with a predominance of locomotion, rearing, jumping, and gnawing for VMH lesion rats, and rearing, rotations, and forelimb movements for LH lesion rats during the acute hyperactivity stage. These results indicated that acute motor effects of hypothalamic lesions are specific to lesion placement. Relations to other types of hyperkinesia and possible mechanisms involved are discussed.