Impaired Voluntary Wheel Running Behavior in the Unilateral 6-Hydroxydopamine Rat Model of Parkinson's Disease

OBJECTIVE The aim of this study was to investigate voluntary wheel running behavior in the unilateral 6-hydroxydopamine (6-OHDA) rat model. METHODS Male Sprague-Dawley rats were assigned to 2 groups : 6-OHDA group (n=17) and control group (n=8). The unilateral 6-OHDA rat model was induced by injection of 6-OHDA into unilateral medial forebrain bundle using a stereotaxic instrument. Voluntary wheel running activity was assessed per day in successfully lesioned rats (n=10) and control rats. Each behavioral test lasted an hour. The following parameters were investigated during behavioral tests : the number of running bouts, the distance moved in the wheel, average peak speed in running bouts and average duration from the running start to the peak speed. RESULTS The number of running bouts and the distance moved in the wheel were significantly decreased in successfully lesioned rats compared with control rats. In addition, average peak speed in running bouts was decreased, and average duration from the running start to the peak speed was increased in lesioned animals, which might indicate motor deficits in these rats. These behavioral changes were still observed 42 days after lesion. CONCLUSION Voluntary wheel running behavior is impaired in the unilateral 6-OHDA rat model and may represent a useful tool to quantify motor deficits in this model.