Neuroprotective effect of ketamine and sevoflurane against TNF-α induced cognitive impairment

In the present study, neuroprotective effect of sevoflurane in combination with ketamine was investigated on TNF-α induced necroptosis of neurons and cognitive impairment in the rat model. The results demonstrated that exposure to TNF-α/z-VAD led to a significant decrease in viability of HT-22 neuronal cells. However, incubation of HT-22 cells with ketamine plus sevoflurane inhibited decrease in viability induced by TNF-α/z-VAD exposure. The increase in production of ROS by TNF-α/z-VAD exposure in HT-22 cells was effectively suppressed on pre-treatment with ketamine plus sevoflurane. Moreover, suppression of TNF-α/z-VAD induced ROS production in HT-22 cells by ketamine plus sevoflurane pretreatment was higher in comparison to ketamine or sevoflurane treatment alone. Treatment of HT-22 cells with ketamine plus sevoflurane suppressed TNF-α/z-VAD induced increase in RIP1 and p-MLKL protein expression. Ketamine plus sevoflurane treatment effectively reversed decrease in movement speed as well as total distance traveled in TNF-α injected rats. The number of neurons in rat hippocampus injected with TNF-α showed a significant decrease more specifically in carbonic anhydrase-3 region. However, no significant change in the density of neurons was observed in the hippocampus of rats pretreated with ketamine plus sevoflurane by TNF-α injection. The increase in expression of p-MLKL and p-RIP3 by TNF-α injection was effectively reversed in rats on treatment with ketamine plus sevoflurane. In silico studies revealed that ketamine interacts with p-MLKL protein in different confirmations with the binding affinities ranging from -9.7 to -8.4 kcal/mol. It was found that ketamine binds to p-MLKL protein by interacting with alanine (ALA A:295), proline (PRO A:306), glutamine (GLN A: 307) and isoleucine (ILE A:293) amino acid residues. In summary, ketamine plus sevoflurane combination alleviates TNF-α/z-VAD induced decrease in viability of HT-22 cells in vitro and rat hippocampus neurons in vivo. Moreover, ketamine plus sevoflurane combination prevented TNF-α injection induced cognitive impairment in rats. Therefore, sevoflurane plus ketamine combination can be developed as a potential therapeutic regimen for treatment of isoflurone induced cognitive impairment.