Tremor: role of striatal cholinergic neurons and the effect of intrastriatal kainic acid.

Rats injected intrastriatally with kainic acid (KA) showed increased tremor responses to arecoline and tremorine, but not to harmaline. Since KA significantly reduced both pre- and postsynaptic measurements of cholinergic function in the striatum, the results indicate that integrity of the striatal cholinergic system is not essential to tremor response. Further investigations of cholinergic function in the brains of rats injected with KA did not reveal evidence of cholinergic supersensitivity; thus, the altered responses to cholinergic agents may reflect KA-associated destruction of some pathway normally opposing the behavioral output of cholinergic stimulation. If, as recently proposed, intrastriatal injection of KA produces an animal model of Huntington's disease (HD), then these results may also be relevant to experimental therapeutics of this disorder.