Effects of unilateral striatal dopamine depletion on tongue force and rhythm during licking in rats

To quantitatively assess the orolingual dysfunctions produced by unilateral striatal dopamine depletions, rats first received 6-hydroxydopamine inject ions into the nigrostriatal bundle and were then trained to lap water from a force- sensing disk in 2-min sessions. Compared with controls and rats wi th moderate (<75%) dopamine depletions, subjects with substantial (>75%) do pamine depletions showed decreases in number of licks, lick rhythm, and lic k peak force. Rats with substantial lesions were also impaired in making in itial, within-session adjustments in lick peak force but not in lick rhythm . The results confirm the presence of Parkinson-like deficits in tongue dyn amics during consummatory licking behavior in rats. The methods used here s hould prove useful in providing quantitative measures of the efficacy of ex perimental therapies in this rodent model of Parkinson's disease.