Brazilian Journal of Anesthesiology
Brazilian Journal of Anesthesiology
Experimental Trials

The antioxidant effect of preischemic dexmedetomidine in a rat model: increased expression of Nrf2/HO-1 via the PKC pathway

Yong-Hee Park, Hee-Pyoung Park, Eugene Kim, Hannah Lee, Jung-Won Hwang, Young-Tae Jeon, Young-Jin Lim

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The precise underlying mechanism of antioxidant effects of dexmedetomidine-induced neuroprotection against cerebral ischemia has not yet been fully elucidated. Activation of Nuclear factor erythroid 2-related factor (Nrf2) and Heme Oxygenase-1 (HO-1) represents a major antioxidant-defense mechanism. Therefore, we determined whether dexmedetomidine increases Nrf2/HO-1 expression after global transient cerebral ischemia and assessed the involvement of Protein Kinase C (PKC) in the dexmedetomidine-related antioxidant mechanism.

Thirty-eight rats were randomly assigned to five groups: sham (n = 6), ischemic (n = 8), chelerythrine (a PKC inhibitor; 5 IV administered 30 min before cerebral ischemia) (n = 8), dexmedetomidine (100 µ IP administered 30 min before cerebral ischemia (n = 8), and dexmedetomidine + chelerythrine (n = 8). Global transient cerebral ischemia (10 min) was applied in all groups, except the sham group; histopathologic changes and levels of nuclear Nrf2 and cytoplasmic HO-1 were examined 24 hours after ischemia insult.

We found fewer necrotic and apoptotic cells in the dexmedetomidine group relative to the ischemic group (p < 0.01) and significantly higher Nrf2 and HO-1 levels in the dexmedetomidine group than in the ischemic group (p < 0.01). Additionally, chelerythrine co-administration with dexmedetomidine attenuated the dexmedetomidine-induced increases in Nrf2 and HO-1 levels (p < 0.05 and p < 0.01, respectively) and diminished its beneficial neuroprotective effects.

Preischemic dexmedetomidine administration elicited neuroprotection against global transient cerebral ischemia in rats by increasing Nrf2/HO-1 expression partly via PKC signaling, suggesting that this is the antioxidant mechanism underlying dexmedetomidine-mediated neuroprotection.


Antioxidant;  Cerebral ischemia;  Dexmedetomidine;  Nuclear factor erythroid 2-related factor;  Protein kinase C


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