Social odor recognition: a novel behavioral model for cognitive dysfunction in Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative condition characterized by an increasing loss of dopaminergic neurons resulting in motor dysfunction. However, cognitive impairments in PD patients are a common clinical feature that has gained increased attention. The purpose of the current study was to evaluate the effects of an MPTP-induced dopaminergic lesion in mice on social odor recognition (SOR) memory. Mice were acutely treated with MPTP and evaluated for memory impairments in the SOR assay and characterized using biochemical and immunohistochemical methods approximately 2 weeks later. Here we demonstrate that SOR memory is sensitive to MPTP treatment and that it correlates with multiple measures of nigrostriatal integrity. MPTP treatment of C57BL/6N mice produced a profound decrease in dopamine levels, dopamine transporter binding and tyrosine hydroxylase immunoreactivity in the striatum. These impairments in stratial dopaminergic function were blocked by pretreatment with the MAO-B inhibitor deprenyl. Changes in the dopaminergic system parallel those observed in SOR with MPTP treatment impairing recognition memory in the absence of a deficit in odor discrimination during learning. Deprenyl pretreatment blocked the MPTP-induced impairment of SOR memory. The use of the SOR memory model may provide a preclinical method for evaluating cognitive therapies for PD.