Further validation of the corridor task for assessing deficit and recovery in the hemi-Parkinsonian rat: Restoration of bilateral food retrieval by dopamine receptor agonism

The corridor test is a newly developed test of sensorimotor integration that depends on a rat's ability to retrieve food from either side of its body. Rats with unilateral dopamine-depleting lesions neglect food on the contralateral side of their bodies, and selectively retrieve from the ipsilateral side. In the present study, the time-course for development of this deficit after injection of 6-hydroxydopamine into the striatum is determined using the corridor test. The ability of the dopamine receptor agonist, apomorphine, to reverse this impairment is also assessed. Lesioned rats developed an impairment in contralateral retrieval that was evident within a day (and stable for up to 2 weeks) after lesion surgery. Systemic injection of apomorphine significantly ameliorated this deficit, and restored the rats’ ability to collect food from both sides of their bodies. This study confirms that the corridor test is highly sensitive to dysfunction of the nigrostriatal dopamine system, and suggests that it might be a useful tool for screening pharmacological approaches to the treatment of Parkinson's disease.