Wheel-running activity after kainic acid injection into lateral hypothalamus of rats

It has not been resolved whether the permanent decrease in wheel-running activity observed after the placement of bilateral electrolytic lesions in the ventrolateral hypothalamus of rats is due to local neuronal destruction or to disruption of fibers of passage within the lateral hypothalamus. To further explore this question, the changes in wheel-running activity following injections of a kainic acid (KA) solution into the ventrolateral hypothalamus of rats were studied. As was found with electrolytic lesions, KA induced lesions in the ventrolateral hypothalamus resulted in a permanent decrease in wheel-running activity. The uptake of 3H-dopamine (3H-DA) into crude synaptosomal preparations of striatal tissue was used as an index of the amount of damage done to fibers of passage by KA. 3H-DA uptake by striatal tissue from rats injected with KA did not significantly differ from that of control rats. These data support the hypothesis that the decrease in wheel-running activity following injection of KA into the ventrolateral hypothalamus is the result of damage to intrinsic neurons.