Effects of right-unilateral 6-hydroxydopamine infusion-induced memory impairment and oxidative stress: relevance for Parkinson's disease

Male Wistar rats were subjected to right-unilateral 6-hydroxydopamine (6-OHDA) (2 mu g/mu l) lesions of the ventral tegmental area (VTA) or the substantia nigra (SN), or were sham-operated, and their ability to acquire the operant task was studied by means of Y-maze and shuttle-box tasks. Lesions of both the VTA and the SN resulted in an impairment of conditioned avoidance response and increase of crossing latency tested by means of shuttle-box task, suggesting significant effects of long-term memory. 6-OHDA significantly decreased spontaneous alternation in Y-maze task, suggesting effects on spatial memory, especially on short-term memory. In addition, 6-OHDA lesions of the VTA and the SN induced reductions in superoxide dismutase (SOD), glutathione peroxidase (GPX) activities and malondialdehyde (MDA) levels in the temporal lobe rather than in the frontal lobe homogenates. Our results provide further support for the toxic effects of 6-OHDA-induced memory impairment and oxidative stress with relevance for Parkinson's disease.