Abstract
A number of recent discoveries indicate that huperzine A, an active herbal medicine employed for the treatment of Alzheimer's disease (AD) in China, can afford neuroprotection on in vitro and in vivo models related to mitochondrial dysfunction. However, it is an intricate and highly debated research topic about whether another pharmacological mechanism is involved in the beneficial profiles of huperzine A, independent of its well-recognized potent acetycholinesterase (AChE) inhibitory effect. As an extension, this study for the first time verified the co-occurrence of the beneficial effects of huperzine A on mitochondrial dysfunction and memory deficits in AβPP/PS1 double transgenic mice, at a time point that AChE was not inhibited. Moreover, using isolated brain cortical mitochondria, we confirmed the ameliorating effect of huperzine A on oligomeric Aβ1-42-induced ATP reduction and mitochondrial swelling, as well as a decrease in the enzymatic activities of respiratory chain complexes, especially complex II-III and complex IV, which may be attributed to the blockage of oligomeric Aβ1-42 from penetrating into mitochondria. These results shed more light on a potential direct target of huperzine A on isolated mitochondria, which may be largely different from its specific inhibition on AChE. This work describes a novel mechanism of neuroprotection by huperzine A and provides important clues for discovering novel therapeutic strategy for AD.