Athetoid and Choreiform Hyperkinesias Produced by Gaudate Application of Dopamine in Cats

Behavioral changes resembling human athetoid and choreiform hyperkinesias were produced b y unilateral injections of L-3,4-dihydroxyphenylalanine (l-D O P A ), dopamine, 3-m ethoxy-tyram ine and dexamphetamine into the rostromedial part of the caput caudati o f ca ts; saline, noradrenaline and 3,4 -dihydroxyphenylacetio acid were ineffective. Pretreatment with the tyrosine hydroxylase inhibitor, oc-methyl-para-tyrosine, blocked the effects induced b y l-D O P A , dopamine and dexamphetamine in a competitive w ay; the 3-methoxy-tyramine effect was blocked in a non-competitive w ay. Applications o f the active compounds into the anteroventral paft o f the caput caudati were ineffective. The hypothesis is put forward th a t normally dopamine-sensitive sites are involved in the manifestation o f choreo-athetoid movements. The implications of these findings are oonsidered in view o f the efficacy of l -D O P A and a-m ethyl-D O PA in Parkinson’a disease and Huntington’s chorea, respectively. In addition, our data are discussed in the light o f the recent finding th at lesions restricted to the anteroventral part of the caput caudati also résult in these hyperkinesias.