Dexmedetomidine attenuates lipopolysaccharide-induced liver oxidative stress and cell apoptosis in rats by increasing GSK-3β/MKP-1/Nrf2 pathway activity via the α2 adrenergic receptor.

Dexmedetomidine (DEX) protects against liver damage caused by sepsis. The purpose of this study was to confirm the regulatory effects of DEX on glycogen synthase kinase 3 beta (GSK-3β) via the α2 adrenergic receptor (α2AR) and evaluate the role of GSK-3β in lipopolysaccharide (LPS)-induced liver injury. Sprague-Dawley (SD) rats were administered an intraperitoneal injection of DEX (30 μg/kg) 30 min before an intraperitoneal injection of LPS (10 mg/kg). HE staining and serum biochemical test results indicated that DEX significantly improved liver histopathological damage and liver function indices. Furthermore, DEX increased super oxide dismutase (SOD) activity and L-glutathione (GSH) levels, and inhibited malondialdehyde (MDA) production. Western blot (WB) analysis demonstrated that treatment with the GSK-3β inhibitor SB216763 increased antioxidant-related protein mitogen-activated protein kinase phosphatase 1 (MKP-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) expression. In addition, anti-apoptosis-related proteins were up-regulated and pro-apoptosis-related proteins were down-regulated by SB21676 administration. WB analysis also showed that DEX increased anti-apoptosis-related protein levels and decreased pro-apoptotic protein levels in LPS-induced liver injury. Nrf2, p53, and activated caspase-3 levels were further evaluated using immunohistochemistry (IHC), producing results consistent with WB results. The α2AR antagonist atipamezole (AT) significantly reversed the protective effects of DEX, as shown by WB analysis. Our data suggested that α2AR plays an important role in reversing the effects of liver oxidative stress and apoptosis via DEX, and that DEX exerts antioxidant and anti-apoptosis effects through regulation of the GSK-3β/MKP-1/Nrf2 pathway.

Sha J ，Zhang H ，Zhao Y ，Feng X ，Hu X ，Wang C ，Song M ，Fan H ... -  《-》

Dexmedetomidine ameliorates lipopolysaccharide-induced acute kidney injury in rats by inhibiting inflammation and oxidative stress via the GSK-3β/Nrf2 signaling pathway.

Acute kidney injury (AKI) is a frequent and serious complication of sepsis; however, there are currently no effective therapies. Inflammation and oxidative stress are the major mechanisms implicated in lipopolysaccharide (LPS)-induced AKI. Dexmedetomidine (DEX) has been reported to have remarkable anti-inflammatory and antioxidant effects. Here, we examined the renoprotective effects of DEX and potential underlying mechanisms in rats with LPS-induced AKI. We analyzed renal function and structure; serum inflammatory cytokine; renal oxidant and antioxidant levels; and renal expression of glycogen synthase kinase-3β (GSK-3β)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related proteins in rats 4 hr after administration of LPS. Pretreatment with DEX improved renal function and significantly reduced the levels of inflammatory cytokines and oxidative stress markers. Treatment with DEX and the GSK-3β inhibitor SB216367 promoted phosphorylation of GSK-3β, induced Nrf2 nuclear translocation, and increased transcription of the Nrf2 target genes heme oxygenase-1 and NAD(P)H quinone oxidoreductase-1, primarily in renal tubules. Alpha-2-adrenergic receptor (α2-AR) antagonist atipamezole and imidazoline I 2 receptor (I 2 R) antagonist idazoxan reversed the effects of DEX. These results suggest that the renoprotective effects of DEX are mediated via α2-AR and I 2 R-dependent pathways that reduce inflammation and oxidative stress through GSK-3β/Nrf2 signaling.

Feng X ，Guan W ，Zhao Y ，Wang C ，Song M ，Yao Y ，Yang T ，Fan H ... -  《-》

Activation of α2 adrenoceptor attenuates lipopolysaccharide-induced hepatic injury.

Chen JH ，Yu GF ，Jin SY ，Zhang WH ，Lei DX ，Zhou SL ，Song XR ... -  《International Journal of Clinical and Experimental Pathology》

Dexmedetomidine protects against lipopolysaccharide-induced early acute kidney injury by inhibiting the iNOS/NO signaling pathway in rats.

Increasing evidence has demonstrated that dexmedetomidine (DEX) possesses multiple pharmacological actions. Herein, we explored the protective effect and potential molecular mechanism of DEX on lipopolysaccharide (LPS)-induced early acute kidney injury (AKI) from the perspective of antioxidant stress. We found that DEX (30 μg/kg, i.p.) ameliorated the renal dysfunction and histopathological damage (tubular necrosis, vacuolar degeneration, infiltration of inflammatory cells and cast formation) induced by LPS (10 mg/kg). DEX also attenuated renal oxidative stress remarkably in LPS-induced early AKI, as evidenced by reduction in production of reactive nitrogen species, decreasing malondialdehyde levels, as well as increasing superoxide dismutase activity and glutathione content. DEX prevented activator protein-1 translocation, inhibited phosphorylation of I-kappa B (IκB) and activation of nuclear factor kappa B (NF-κB) in LPS-induced early AKI, as assessed by real-time quantitative polymerase chain reaction and protein levels of c-Jun, c-Fos, IκB and NF-κB. Notably, DEX pretreatment had the same effect as intraperitoneal injection of an inhibitor of inducible nitric oxide synthase inhibitor (1400W; 15 mg/kg), and inhibited the activity of renal inducible nitric oxide synthase (iNOS) and decreased the expression of iNOS mRNA and NO production. However, the protective effect of DEX on LPS-induced early AKI was reversed by the alpha 2 adrenal receptor (α2-AR) inhibitor atipamezole, whereas the imidazoline receptor inhibitor idazoxan did not. Taken together, DEX protects against LPS-induced early AKI in rats by inhibiting the iNOS/NO signaling pathway, mainly by acting on α2-ARs instead of IRs.

Chen Y ，Luan L ，Wang C ，Song M ，Zhao Y ，Yao Y ，Yang H ，Ma B ，Fan H ... -  《-》

Dexmedetomidine alleviates inflammatory response and oxidative stress injury of vascular smooth muscle cell via α2AR/GSK-3β/MKP-1/NRF2 axis in intracranial aneurysm.

Vascular smooth muscle cell (VSMC) phenotypic modulation regulates the initiation and progression of intracranial aneurysm (IA). Dexmedetomidine (DEX) is suggested to play neuroprotective roles in patients with craniocerebral injury. Therefore, we investigated the biological functions of DEX and its mechanisms against IA formation and progression in the current study. The rat primary VSMCs were isolated from Sprague-Dawley rats. IA and superficial temporal artery (STA) tissue samples were obtained from patients with IA. Flow cytometry was conducted to identify the characteristics of isolated VSMCs. Hydrogen peroxide (H2O2) was used to mimic IA-like conditions in vitro. Cell viability was detected using CCK-8 assays. Wound healing and Transwell assays were performed to detect cell motility. ROS production was determined by immunofluorescence using DCFH-DA probes. Western blotting and RT-qPCR were carried out to measure gene expression levels. Inflammation responses were determined by measuring inflammatory cytokines. Immunohistochemistry staining was conducted to measure α2-adrenergic receptor levels in tissue samples. DEX alleviated the H2O2-induced cytotoxicity, attenuated the promoting effects of H2O2 on cell malignancy, and protected VSMCs against H2O2-induced oxidative damage and inflammation response. DEX regulated the GSK-3β/MKP-1/NRF2 pathway via the α2AR. DEX alleviates the inflammatory responses and oxidative damage of VSMCs by regulating the GSK-3β/MKP-1/NRF2 pathway via the α2AR in IA.

Zhang Z ，Mu X ，Zhou X 《BMC Pharmacology & Toxicology》