Differential effects of unilateral striatal and nigrostriatal lesions on grip strength, skilled paw reaching and drug-induced rotation in the rat.

Lateralised motor deficits associated with basal ganglia dysfunction were compared in separate groups of rats receiving unilateral 6-hydroxydopamine-induced lesions of the dopaminergic nigrostriatal pathway, quinolinic acid-induced lesions of the striatum, or sham control injections. Amphetamine induced ipsilateral rotation in both lesion groups, whereas a low ('supersensitive') dose of apomorphine induced rotation only in the nigrostriatal lesion group. Both lesions induced impairments in skilled paw reaching with the contralateral paw in the 'staircase' test; by contrast the striatal lesions also induced a marked impairment with the ipsilateral paw, which was unaffected by the nigrostriatal lesion. A previously reported increase in grip strength with the contralateral paw after nigrostriatal lesion was replicated, whereas striatal lesions induced only minor bilateral deficits in this test. The results are discussed in the context of the utility, reliability and validity of alternative tests of motor deficit in animal models of Parkinson's and Huntington's diseases.