Effect of TAK-242 on learning and memory dysfunction in mice with lipopolysaccharide-induced sepsis-associated encephalopathy

AIM:To explore the effect of TAK-242 on the learning and memory ability of C57BL/6 mice with sepsis-associated encephalopathy induced by lipopolysaccharide (LPS), to observe the pathological and morphological changes of the mouse brain, and to explore the mechanism of protein pathway associated with the effect of TAK-242. METHODS:Healthy female C57BL/6 mice (n=80), aged 10~12 months, weighing 20~30 g, were randomly divided into 4 groups (n=20):blank control (CON) group, TAK-242 control (TAK) group, sepsis encephalopathy model (LPS) group and TAK-242 pretreatment (T+L) group. Peripheral inflammation in the mice was detected by testing the arterial blood and lung tissues. The behavioral changes of the mice were observed by the open-field test, elevated plus-maze test (EPMT) and Morris water maze test. Immunohistochemistry was performed to observe the changes of microglia-specific marker, ionized calcium-binding adapter molecule-1 (Iba-1), in the hippocampus. Finally, the protein expression levels of NF-κB p65, TLR4, Aβ1-42 and p-tau (S396) were determined by Western blot. RESULTS:Compared with CON group, the mice in other groups didn't showed significant difference in the arterial blood gas analysis and lung tissue HE staining. In the anxiety and fear behavior tests, central active duration and times of crossing central field of the mice in LPS group were significantly decreased compared with CON group (P<0.01). The times of open arm entry and the times of head area entry in the EPMT were significantly less than those in CON group (P<0.05). The escape latency of spatial probe experiments was significantly extended (P<0.05). Microglial activation in the hippocampus was significantly increased (P<0.05) and the protein expression levels of NF-κB p65, TLR4, Aβ1-42 and p-tau (S396) were significantly increased (P<0.01). Conversely, compared with LPS group, the central active duration and times of crossing central field in T+L group were significantly increased (P<0.01). The times of open arm entry and the times of head area entry in the EPMT were significantly increased (P<0.05). The escape latency of spatial probe experiments was significantly shortened (P<0.05). Microglial activation in the hippocampus was significantly decreased and the protein expression levels of NF-κB p65, TLR4, Aβ1-42 and p-tau (S396) were down-regulated (P<0.05). CONCLUSION:TAK-242 obviously improves the ability of learning and memory, and the mechanism may be related to the inhibition of the central microglia activation and down-regulation of protein expression levels of NF-κB p65, TLR4, Aβ1-42 and p-tau (S396).