The deficit in long-term potentiation induced by chronic administration of amyloid-β is attenuated by treatment of rats with a novel phospholipid-based drug formulation, VP025

Abstract

Amyloid-β (Aβ) peptides, the primary component of the amyloid plaques in Alzheimer’s disease (AD), exert profound effects on neurons in vitro and negatively impact on neuronal function in vivo. One of the consequences of increased Aβ in the brain, either as a result of overexpression of the precursor amyloid precursor protein in transgenic mice, or injection into the brain is a decrease in one form of synaptic plasticity, long-term potentiation (LTP) in the hippocampus. Here we investigated the effect of infusion of Aβ for 28 days on LTP in dentate gyrus of rats and demonstrate that it was profoundly decreased compared with control-treated rats. We show that this effect is accompanied by increased activity of caspase 3, which is an indicator of cell stress. Significantly these changes were attenuated in animals which were pretreated with particles incorporating phosphatidylglycerol (VP025) and the evidence indicated that even when treatment was given 2 weeks after the start of the Aβ infusion, VP025 was capable of attenuating Aβ-induced changes. The evidence suggests that activation of caspase 3 was mediated by an Aβ-induced increase in sphingomyelinase, with the subsequent production of ceramide which is known to have a detrimental effect on neuronal function.