An animal model for Huntington's disease.

In review is concerned with research done on an animal model for the hereditary neuropsychiatric disorder, Huntington's disease (HD). The neuropathology of HD involves primarily a selective degeneration of neurons with cell bodies in the striatum. Injection of kainic acid, a potent neuroexcitant structurally related to glutamic acid, into the rat striatum causes a selective neuronal degeneration resembling that of HD. Striatal cholinergic and GABAergic neurons, including their terminal projections in the substantia nigra, are affected by kainate; dopaminergic axons innervating the striatum as well as corticofugal fibers passing through the region are spared. The striatal kainate lesion has aided in the characterization of the neuronal circuitry in the nigrostriatal axis including the neuronal localization of dopamine-sensitive adenylate cyclase, neuroleptic binding sites, and GABA receptors. Studies in vivo and in vitro with kainate and its analogues suggest that the potent neurotoxicity of kainate involves a cooperative interaction between synaptically released glutamate and injected kainate on vulnerable neurons; prior destruction of cortico-striatal glutamatergic afferents attenuates kainate's neurotoxicity. The kainate model has been used to test drugs that may be of therapeutic benefit for HD. A better understanding of the mechanism of neurotoxicity of kainate may shed light on the cause of neuronal degeneration in HD.