Locomotor hypokinesia in the reserpine-treated rat: drug effects from the corpus striatum and nucleus accumbens.

A mechanographic method was used to assess the locomotor performance induced by apomorphine or other dopaminergic drugs in reserpine-treated rats. Reserpine was found to induce locomotor hypokinesia. The hypokinesia was dose-dependently reversed by apomorphine (APO), bromocriptine and pergolide. Locomotion was induced by microinjection of APO into the nucleus accumbens. No locomotor effect was found after injection into corpus striatum. Injection into both nuclei was not superior to accumbens only. Intra-striatal or intraaccumbens injections of trifluoperazine blocked the effect on locomotion by systematic apomorphine. The results confirmed that reserpine-induced locomotor hypokinesia is reversed by dopaminergic stimulation in the nucleus accumbens. There were indications that blockade of striatal or accumbens' dopamine receptors counteracts apomorphine-induced locomotion presumably by interaction with postural motor control. Evidence was found for separate dopaminergic control of locomotion and muscletone. This may be of importance for the development of new antiparkinson drugs.