Aloe-Emodin Improves Mitophagy in Alzheimer's Disease via Activating the AMPK/PGC-1α/SIRT3 Signaling Pathway.

BACKGROUND: Impaired mitophagy results in the accumulation of defective mitochondria that are unable to be cleared effectively in Alzheimer's disease (AD). Aloe-emodin (AE), a key component of the traditional Chinese medicine Rhubarb, exhibits neuroprotective effects against Alzheimer's disease, though the underlying mechanism remains unclear. Studying aloe-emodin's role in enhancing mitophagy is vital for improving cognitive function and reducing neuronal damage in Alzheimer's disease. METHODS: The APP/PS1 double transgenic mice were adopted as models for AD to assess the effects of aloe-emodin upon cognitive function and its neuroprotective impact on hippocampal neurons. Additionally, we investigated the regulatory mechanisms of proteins within the aforementioned pathway, and the morphological characteristics of mitophagy-related proteins. An AD hippocampal neuron model was developed using Aβ25-35 to evaluate the mitochondrial function, the protein expression of such a pathway and the mitophagy. This approach aims to elucidate the effects and underlying mechanisms of aloe-emodin in relation to AD. RESULTS: AE activates mitophagy in neurons, improves cognitive dysfunction, reduces hippocampal damage, and alleviates AD symptoms in model mice. AE activates the expression of AMPK, PGC-1α and SIRT3. Increased expression of SIRT3 in mitochondria promotes mitophagy and regulates the function of mitochondrial proteins. When mitochondrial autophagy is enhanced, the expression of Beclin1, LC3, P62, Parkin, and PINK1-related proteins changes. Further in vitro experiments showed that AE can enhance mitochondrial function in Alzheimer's disease cell models. The mitochondrial membrane potential, GSH, ROS and Ca2+ levels gradually recover, alleviating the pathological manifestations of AD. Knocking down SIRT3 leads to increased mitochondrial damage and a reduction in mitophagy in HT22 cells. CONCLUSION: Experimental results show that AE can activate mitophagy through AMPK/PGC-1α/SIRT3 pathway, alleviate cognitive dysfunction in AD, and reduce damage to hippocampal neurons.