Hypokinesia, rigidity, and tremor induced by hypothalamic 6-OHDA lesions in the rat.

Bilateral administration of 6-hydroxydopamine in the medial fore-brain bundle at the level of the posterolateral hypothalamus in rats resulted in hypokinesia, muscular rigidity and tremor as determined by various behavioral assessment procedures. These neurological signs were accompanied by marked decreases in the concentrations of dopamine and its main metabolites dihydroxyphenylacetic acid and homovanillic acid in both striatum and nucleus accumbens. Administration of apomorphine (1 mg/kg) or L-Dopa (60 mg/kg) reversed or totally abolished the hypokinesia, rigidity and tremor in lesioned animals. Together, the present findings demonstrate that bilateral intrahypothalamic administration of 6-OHDA results in the appearance of the three cardinal symptoms of Parkinson's disease in rats. This model should prove to be valuable for both the study of the neuropathological processes underlying the neurological signs of this disease and the screening of potential antiparkinson agents.