Dexmedetomidine Attenuated Neuron Death, Cognitive Decline, and Anxiety-Like Behavior by Inhibiting CXCL2 in CA1 Region of AD Mice.

PURPOSE: β-amyloid overload-induced neuroinflammation and neuronal loss are key pathological changes that occur during the progression of Alzheimer's disease (AD). Dexmedetomidine (Dex) exhibits neuroprotective and anti-inflammatory effects on the nervous system. However, the effect of Dex in AD mice remains unclear, and its neuroprotective regulatory mechanism requires further investigation. This study aimed to reveal how Dex protects against Aβ induced neuropathological changes and behavior dysfunction in AD mice.

METHODS

An AD mouse model was established by the injection of Aβ into the brains of mice, followed by intraperitoneal injection with Dex. CXCL2 overexpression and Yohimbine, a Dex inhibitor, were used to investigate the role of Dex and CXCL2 in the regulation of neuronal loss, cognitive decline, and anxiety-like behavior in AD mice. Behavioral tests were performed to evaluate the cognitive and anxiety status of the mice. Nissl staining and immunofluorescence experiments were conducted to evaluate the status of the hippocampal neurons and astrocytes. qRT-PCR was performed to detect the expression of CXCL2, IL-1β, INOS, SPHK1, Bcl2, IFN-γ, and Caspase 1. The malondialdehyde (MDA) level was detected using an ELISA kit. Terminal TUNEL and Fluoro-Jade C (FJC) staining were used to measure the cell apoptosis rate.

RESULTS

In AD mice, cognitive decline and anxiety-like behaviors were significantly improved by the Dex treatment. The number of neurons was increased in mice in the Dex + AD group compared to those in the AD group, and the number of astrocytes was not significantly different between the two groups. CXCL2, IL-1β, iNOS, and SPHK1 levels were significantly lower in Dex-treated AD mice than those in AD mice. Overloading of CXCL2 or Yohimbine reversed the protective effect of Dex on neuron number and cognitive and anxiety symptoms in AD mice.

CONCLUSION

Our results suggest that Dex exerts neuroprotective effects by downregulating CXCL2. Dex shows potential as a therapeutic drug for AD.