Experimental striatal degeneration induced by kainic acid administration: relevance to morphological changes in Huntington's disease.

In an attempt to reproduce the characteristic neuronal degeneration pattern in the striatum of human patients with Huntington's disease, the histological and ultrastructural features of the degeneration of medium-sized nerve cells in the striatum and its processes are described in young rats induced by a direct injection of a small amount of kainic acid into the striatum. A light microscopic examination revealed initial edema and necrotic changes at the site of injection. The area surrounding the needle track showed neuronal and dendritic swelling and eosinophilic neurons without the apparent involvement of the passing axons. Later changes consisted of a marked neuronal loss particularly of the small cells with consequent severe astrocytosis. Electron microscopy showed specific neuronal alterations in the form of ballooned Golgi apparatuses, swelling of the endoplasmic reticulum, dendritic swelling, proliferated neurofilaments and aggregation of polysomes together with a marked disruption of neuropil. Neuronal debris and small dense bodies appeared. The majority of neuronal loss consisted of medium-sized nerve cells: Type I. Some spheroid bodies and lipid droplets were also observed.