Dexmedetomidine Provides Protection to Neurons Against OGD/R-Induced Oxidative Stress and Neuronal Apoptosis

Background: Dexmedetomidine, a potent α2-adrenoceptor (α2-AR) agonist, is extensively used in the operating room (OR) and intensive care unit (ICU) and has applied in several diseases. However, the precise role of dexmedetomidine in oxygen and glucose deprivation/reoxygenation (OGD/R)-treated neurons, and the mechanisms underlying its effect, has yet to be elucidated. Methods: : OGD/R-treated neurons served as a cellular model in our study. Western blotting was used to investigate the protein levels of α-adrenergic receptor (α-AR) in OGD/R-treated neurons, apoptosis related proteins (Bcl-2, Bax and Cleaved Caspase 3) and a range of proteins associated with the Nrf2/ARE pathway (Nrf2, HO-1, NQO-1, SOD). The CCK-8 assay was used to determine cell survival rates while Co-IP was used to determine the interactions between α2-AR and Nrf2. The TUNEL assay was used to detect the levels of apoptosis in neurons. Results: : OGD/R treatment reduced the level of α2-AR protein in neurons and reduced neuronal survival in a time-dependent manner. However, treatment with dexmedetomidine led to an elevation of α2-AR protein expression in OGD/R-treated neurons and the survival rate of OGD/R-treated neurons. These results indicated that dexmedetomidine treatment promoted the viability of OGD/R-treated neurons but inhibited OGD/R-mediated oxidative stress and neuronal apoptosis. From a mechanistic point-of-view, Nrf2 can bind effectively with α2-AR. We believe that dexmedetomidine exerted effect on the Nrf2/ARE pathway in OGD/R-treated neurons. Silencing the expression of Nrf2 reversed the effects of dexmedetomidine on cell viability, oxidative stress, and neuronal apoptosis in OGD/R-treated neurons. Conclusion: Collectively, our data indicate that elucidated that the activation of α2-AR by dexmedetomidine had a protective effect in neurons against OGD/R-triggered oxidative stress and neuronal apoptosis by modulating the Nrf2/ARE pathway, thus providing a novel way forward to develop clinical therapies to reduce oxidative stress induced by neuronal injury.