Athetoid and choreiform hyperkinesias produced by caudate application of dopamine in cats

Behavioral changes resembling human athetoid and choreiform hyperkinesias were produced by unilateral injections of l-3,4-dihydroxyphenylalanine (l-DOPA), dopamine, 3-methoxy-tyramine and dexamphetamine into the rostromedial part of the caput caudati of cats; saline, noradrenaline and 3,4-dihydroxyphenylacetic acid were ineffective. Pretreatment with the tyrosine hydroxylase inhibitor, -methyl-para-tyrosine, blocked the effects induced by l-DOPA, dopamine and dexamphetamine in a competitive way; the 3-methoxy-tyramine effect was blocked in a non-competitive way. Applications of the active compounds into the anteroventral part of the caput caudati were ineffective.The hypothesis is put forward that normally dopamine-sensitive sites are involved in the manifestation of choreo-athetoid movements. The implications of these findings are considered in view of the efficacy of l-DOPA and -methyl-DOPA in Parkinson's disease and Huntington's chorea, respectively. In addition, our data are discussed in the light of the recent finding that lesions restricted to the anteroventral part of the caput caudati also result in these hyperkinesias.