Anterograde and transsynaptic degeneration 'en cascade' in basal ganglia induced by intrastriatal injection of kainic acid: an animal analogue of Huntington's disease.

Damage of striatal neurons by kainic acid (KA) induces an anterograde and transsynaptic degeneration 'en cascade' in the globus pallidus (GP) and substantia nigra (SN). By causing only degeneration of projections arising from KA-sensitive striatal neurons while sparing the connections of KA-resistant striatal neurons, the lesion-induced alterations of the basal ganglia show a characteristic pattern which bears a close resemblance with the neuropathological changes occurring in Huntington's disease: (1) severe degeneration of small and medium-sized striatal neurons, of pallidal neurons and the neurons of the pars reticulata of the SN, and (2) sparing of large striatal neurons, 'peripallidal' (nucleus basalis) neurons and neurons of the pars compacta of the SN. The probable interconnections of both the degenerated and the spared neuronal groups are discussed with respect to the present concept of the neuronal organization and biochemical neuroanatomy of the basal ganglia.