The MAP2K4/JNK/c-jun signaling pathway plays a key role in dexmedetomidine protection against acetaminophen-induced liver toxicity

Purpose: Dexmedetomidine [DEX; (S)-4-[1-(2,3-dimethylphenyl)ethyl]-3H-imidazole] is a selective α₂-adrenergic receptor (α₂-AR) agonist that attenuates the liver damage associated with local or systemic inflammation. However, it remains unclear whether DEX has protective effects against acetaminophen (Paracetamol, PARA)-induced liver toxicity (PILT). Methods: PILT mice were established by intraperitoneal administration of a hepatotoxic dose of acetaminophen (300 mg/kg). Thirty minutes later, the mice were treated with DEX at a concentration of 0, 5, 25, or 50 μg/kg. Blood and liver samples were obtained for further analysis. Results: DEX treatment significantly attenuated PILT in mice, with the strongest beneficial effects at a dose of 25 μg/kg. The levels of hepatic cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), in addition to myeloperoxidase (MPO) activity, were significantly decreased following DEX treatment. Moreover, DEX treatment reduced macro-phage recruitment around the area of hepatotoxicity and the expression levels of hepatic phosphorylated mitogen-activated protein kinase kinase 4 (MAP2K4), c-jun N-terminal kinase (JNK), and c-Jun expression induced by acetaminophen overdose. Conclusion: The data suggest that DEX likely downregulates the JNK signaling pathway and its downstream effectors to promote its hepatoprotective effect, providing a clinical application of DEX for the attenuation of PILT.