Cognitive impairments and circadian rhythm disorders are the main clinical manifestations of Alzheimer's disease (AD). Orexin has been reported as abnormally elevated in the cerebrospinal fluid of AD patients, accompanied with cognitive impairments. Our recent research revealed that suvorexant, a dual orexin receptor antagonist, could improve behavioral circadian rhythm disorders in 9-month-old APP/PS1 mice. Here we further observed whether suvorexant could ameliorate the cognitive decline in APP/PS1 mice by using behavioral tests, and investigated the possible mechanisms by in vivo electrophysiological recording, western blot, and immunochemistry. The results showed that suvorexant treatment effectively ameliorated the cognitive impairments, alleviated in vivo hippocampal long-term potentiation suppression, restored the circadian phosphorylated CREB expression in the hippocampus, and reduced amyloid-β protein deposition in the hippocampus and cortex in APP/PS1 mice. These results indicate that the neuroprotective effects of suvorexant against AD are involved in the reduction of amyloid-β plaques, improvement of synaptic plasticity, and circadian expression of phosphorylated CREB, suggesting that suvorexant could be beneficial to the prevention and treatment of AD.
Keywords: APP/PS1 transgenic mice; Amyloid-β protein; Learning and memory; Long-term potentiation; Suvorexant; pCREB.
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