Impaired learning in a spatial working memory version and in a cued version of the water maze in rats with MPTP-induced mesencephalic dopaminergic lesions

A lesion in the substantia nigra pars compacta (SNc) of rats induced by intra-nigral administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) caused specific loss of dopamine and its nonconjugated metabolites in the dorsal striatum and in the prefrontal cortex (PFC), but not in the hippocampus or the ventral striatum (nucleus accumbens). This lesion did not alter the motor performance of the rats or learning of a spatial reference memory task in the water maze but impaired learning of a spatial working memory task and also of a cued version of the water maze. The results are discussed by relating the selective memory deficits observed in these water maze tasks to the PFC, dorsal striatum, and hippocampus. Some parallels between the memory deficits in these SNc-lesioned rats and Parkinson’s disease patients are also discussed.