Protection effect of gastrodin on learning and memory ability in vascular dementia by promoting autophagy flux via Ca2+/CaMKII signal pathway

Abstract Background: Vascular dementia is a common and frequently-occurring disease in the process of human aging. Although the current treatment can delay the deterioration of the disease, it has not a great breakthrough in improving cognitive impairment. Therefore, exploring the potential key molecular targets of VD provide promising strategy for prevention and treatment. Methods: vascular dementia rats were reproduced by permanent middle cerebral artery occlusion (pMCAO) and anoxic injury of HT22 cells were induced by Cobalt Chloride (CoCl 2 , 200μM). The ability of spatial learning and memory was assessed by morris water maze (MWM) test. Histological analysis was performed by HE staining and immunohistochemical staining. The effects of gastrodin on autophagy flux and calcium signal in vascular dementia rats and HT22 cells during hypoxia injury were detected by Western blotting and immunofluorescence. Furthermore, intracellular Ca 2+ levels were quantified using a Ca 2+ quantification kit and were also measured by flow cytometric estimation of Fluo-4 AM. Results: Gastrodin significantly reversed cognitive deficits in vascular dementia rats. The results of immunohistochemical analysis and western blot confirmed that gastrodin could attenuate the levels of LC3, p62 and phosphorylated CaMKII in hippocampus of VD rats. In addition, gastrodin was similar to the early autophagic inhibitor (3-BDO) ameliorating CoCl 2 -induced autophagic flux dysfunction and p62 knockdown by siRNA also promoting autophagic flux patency, but the late autophagy inhibitor (CQ) weakened the improvement effect of gastrodin. Furthermore, gastrodin markedly inhibited CoCl 2 -induced autophagic flux dysfunction by inhibiting [Ca 2+ ] i -dependent CaMKII. Conclusion: Gastrodin is a potential promising candidate for VD by improving autophagy flux dysfunction via increasing lysosome acidification and autophagosome-lysosome fusion mediated by CaMKII-regulated suppression of p62 signaling. Keywords: Gastrodin, Vascular dementia, Neuron injury, Autophagic flux, Ca 2+ , CaMKII