Paradoxical kinesia in parkinsonism is not caused by dopamine release. Studies in an animal model.
Rats become akinetic after large dopamine-depleting brain lesions, yet they show an activation-induced restoration of motor function. In this study, rats were given intraventricular injections of the neurotoxin 6-hydroxydopamine to permanently reduce the dopamine content of the corpus striatum by 98%. Although the rats were akinetic in their home cages, they swam effectively when placed in deep water and escaped from a shallow floating ice bath. These behaviors were not abolished by pretreating the animals with the dopamine antagonists haloperidol and SCH-23390. In contrast, haloperidol completely blocked the brain-damaged animals' behavioral responses to amphetamine. These results suggest that the paradoxical kinesia of dopamine-depleted rats is not a consequence of dopamine release from residual dopaminergic fibers.
Keefe
K A
KA
Department of Behavioral Neuroscience, University of Pittsburgh, PA 15260.
Salamone
J D
JD
Zigmond
M J
MJ
Stricker
E M
EM
D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists; D006892:Hydroxydopamines / Q000633:toxicity; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D016627:Oxidopamine; D010300:Parkinson Disease / Q000503:physiopathology*; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D013550:Swimming
D018492:Dopamine Antagonists; D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D016627:Oxidopamine; D004298:Dopamine