ANALYSIS OF GALANIN AND THE GALANIN ANTAGONIST M40 ON DELAYED NON-MATCHING-TO-POSITION PERFORMANCE IN RATS LESIONED WITH THE CHOLINERGIC IMMUNOTOXIN (192)IGG-SAPORIN

Galanin is a 29-amino-acid neuropeptide that is overexpressed in Alzhe imer's disease (AD) and impairs performance on rodent learning and mem ory tasks. M40, a peptidergic galanin receptor ligand, blocks galanin- induced impairments on delayed non-matching-to-position (DNMTP). The p resent experiments used the (192)IgG-saporin lesion model of AD to eva luate the actions of galanin and M40 on DNMTP when cholinergic transmi ssion was reduced. Hippocampal choline acetyltransferase levels were c orrelated with DNMTP choice accuracy in lesioned rats. Intracerebroven tricular (icy) galanin reduced choice accuracy in both the lesioned an d sham groups. M40 alone, either icy or intrahippocampal, did not affe ct-choice accuracy in either group. These results suggest that excess galanin can produce further deficits in DNMTP performance in a lesion model of AD, but blocking endogenous galanin is not sufficient alone t o improve performance in lesioned rats.