Tanshinone IIA improves hypoxic ischemic encephalopathy through TLR-4-mediated NF-κB signal pathway

Hypoxic ischemic encephalopathy (HIE) is the most common brain injury following hypoxia and/or ischemia caused by various factors during the perinatal period, resulting in detrimental neurological deficits in the nervous system. Tanshinone IIA (Tan-IIA) is a potential agent for the treatment of cardiovascular and cerebrovascular diseases. In this study, the efficacy of Tan-IIA was investigated in a newborn mouse model of HIE. The dynamic mechanism of Tan-IIA was also investigated in the central nervous system of neonate mice. Intravenous injection of Tan-IIA (5 mg/kg) was administered and changes in oxidative stress, inflammation and apoptosis-associated proteins in neurons. Histology and immunohistochemistry was used to determine infarct volume and the number of damaged neurons by Fluoro-Jade C staining. The effects of Tan-IIA on mice with HIE were evaluated by body weight, brain water content, neurobehavioral tests and blood-brain barrier permeability. The results demonstrated that the apoptosis rate was decreased following Tan-IIA administration. Expression levels of pro-apoptotic proteins, caspase-3 and caspase-9 and P53 were downregulated. Expression of Bcl-2 anti-apoptotic proteins was upregulated by Tan-IIA treatment in neuro. Results also found that Tan-IIA treatment decreased production of inflammatory cytokines such as interleukin-1, tumor necrosis factor-α, C-X-C motif chemokine 10, and chemokine (C-C motif) ligand 12. Oxidative stress was also reduced by Tan-IIA in neurons, as determined by the expression levels of superoxide dismutase, glutathione and catalase, and the production of reactive oxygen species. The results demonstrated that Tan-IIA treatment reduced the infarct volume and the number of damaged neurons. Furthermore, body weight, brain water content and blood-brain barrier permeability were markedly improved by Tan-IIA treatment of newborn mice following HIE. Furthermore, the results indicated that Tan-IIA decreased Toll-like receptor-4 (TLR-4) and nuclear factor-κB (NF-κB) expression in neurons. TLR-4 treatment of neuronal cell in vitro addition stimulated NF-κB activity, and further enhanced the production of inflammatory cytokines and oxidative stress levels in neurons. In conclusion, these results suggest that Tan-IIA treatment is beneficial for improvement of HIE through TLR-4-mediated NF-κB signaling.