We have reported that the continuous infusion of β-amyloid protein-(1-40) into the rat cerebral ventricle produces learning and memory deficits accompanied by dysfunction in the cholinergic and dopaminergic systems. l-Pyroglutamyl-l-asparaginyl-l-seryl-l-prolyl-l-arginylglycinamide (NC-1900), an active fragment analog of arginine vasopressin in the rat brain, is a stable peptide with a five-fold longer half-life than that of arginine vasopressin-(4-9). In the present study, we examined the effects of NC-1900 on learning and memory deficits in β-amyloid protein-(1-40)-infused rats. The rats were injected subcutaneously with NC-1900 (0.1 and 1 ng kg-1) once a day throughout the period of behavioral examination. In the β-amyloid protein-infused rats, learning and memory in water maze and passive avoidance tasks were impaired compared with these in the control rats. NC-1900 prevented the learning and memory deficits in β-amyloid protein-infused rats. Moreover, NC-1900 tended to increase the choline acetyltransferase activity in the frontal cortex of the β-amyloid protein-infused rats. These results suggested that NC-1900 could be useful for the treatment of patients with Alzheimer's disease. Copyright (C) 1998 Elsevier Science B.V.
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