Memory loss caused by beta-amyloid protein is rescued by a beta(3)-adrenoceptor agonist.

Accumulation of the neurotoxic beta-amyloid protein (Abeta) in the brain is a key step in the pathogenesis of Alzheimer's disease (AD). Although transgenic mouse models of AD have been developed, there is a clear need for a validated animal model of Abeta-induced amnesia which can be used for toxicity testing and drug development. Intracranial injections of Abeta(1-42) impaired memory in a single trial discriminative avoidance learning task in chicks. Memory inhibition was closely associated with the state of aggregation of the Abeta peptide, and a scrambled-sequence of Abeta(1-42) peptide failed to impair memory. Abeta had little effect on labile (short-term and intermediate) memory, but blocked consolidation of memory into long-term storage mimicking the type of anterograde amnesia that occurs in early AD. Since noradrenaline exerts a modulatory influence on labile memory in the chick, we examined the effects of two beta-adrenoceptor (AR) agonists on Abeta-induced amnesia. A beta(3)-AR agonist (CL316243), but not a beta(2)-AR agonist, rescued Abeta-induced memory loss, suggesting the need for further studies on the role of beta(3)-ARs in AD.