ABSTRACT
Considerable studies indicate huperzine A is a promising natural product to suppress neuronal damages induced by ß-amyloid (Aß), a key pathogenic event in the Alzheimer's disease (AD). As an extension, the present study for the first time explored whether the beneficial profiles of huperzine A against oligomeric Aß(42) induced neurotoxicity are associated with the accumulation and detrimental function of intraneuronal/mitochondrial Aß, on the basis of the emerging evidence that intracellular Aß is more relevant to AD progression as compared with extracellular Aß. Huperzine A treatment was shown to significantly attenuate the neurotoxicity of oligomeric Aß(42), as demonstrated by increased neuronal viability. Interestingly, our results proved that exogenous Aß(42) could accumulate intraneuronally in a dose- and time-dependent manner, while huperzine A treatment markedly reduced the level of intracellular Aß(42). Moreover, huperzine A treatment rescued mitochondrial dysfunction induced by oligomeric Aß(42), including adenosine triphosphate (ATP) reduction, reactive oxygen species (ROS) overproduction and membrane potential depolarization. Further study demonstrated that huperzine A also significantly reduced the level of Aß(42) in the mitochondria-enriched subcellular fractions, as well as the Aß(42) fluorescent signals colocalized with mitochondrial marker. This study indicates that interfering intracellular Aß especially mitochondrial Aß accumulation, together with ameliorating Aß-associated mitochondrial dysfunction, may contribute to the protective effects of huperzine A against Aß neurotoxicity. Above results may shed more light on the pharmacological mechanisms of huperzine A and provide important clues for discovering novel therapeutic strategies for AD.
