'Choreic' movement induced by unilateral kainate lesion of the striatum and L-DOPA administration in monkey

A monkey whose unilateral striatum was extensively destroyed exhibited no choreic movement after administering L-DOPA, whereas another monkey whose unilateral striatum was partially (especially the dorsolateral part) destroyed showed 'choreic' movements exclusively on the contralateral extremities after the L-DOPA doses. Biochemical analysis disclosed a markedly increased activity of tyrosine hydroxylase in the unaffected (ventromedial) striatal area on the lesioned side when compared to the intact side of the choreic monkey, but not in the non-choreic monkey. Therefore, choreic movements in a monkey were suggested to be generated by the hyperfunction of the nigrostriatal dopaminergic neurons that innervate the unaffected part of the striatum.