Role of p38 MAPK/CREB signaling pathway in tetramethylpyrazine-induced reduction of hippocampal inflammatory responses in mice with sepsis-associated encephalopathy / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of p38 mitogen-activated protein kinase (MAPK)/cyclic adenosine monophosphate response element-binding protein (CREB) signaling pathway in tetramethylpyrazine-induced reduction of hippocampal inflammatory responses in mice with sepsis-associated encephalopathy (SAE).Methods:Sixty healthy male C57BL6 mice, weighing 24-27 g, were divided into 4 groups ( n=15 each) using a random number table method: sham operation group (group Sham), sepsis group (group Sep), tetramethylpyrazine group (group TMP) and p38 MAPK inhibitor SB203580 group (group SB). The model of SAE was established by cecal ligation and puncture in anesthetized mice.Tetramethylpyrazine 10 mg/kg was injected intraperitoneally once a day at 3 days before the establishment of the model in TMP group, and SB203580 2.0 mg/kg was intraperitoneally injected at 30 min after the establishment of the model in SB group.The equal volume of normal saline was given intraperitoneally in Sham and Sep groups.At 1 day after operation, cognitive function was assessed by Morris water maze, and the escape latency and ratio of time spent in the target quadrant were recorded.The animals were sacrificed after the test, and hippocampal tissues were taken for determination of the contents of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and IL-6 (by enzyme-linked immunosorbent assay) and for detection of the expression of phosphorylation of p38 MAPK, GSK3 and CREB and expression of brain-derived neurotrophic factor (BDNF) (by Western blot). Results:Compared with group Sham, the escape latency was significantly prolonged, the ratios of time spent in the target quadrant were decreased, the contents of IL-1β, TNF-α and IL-6 were increased, the phosphorylation of hippocampus p38 MAPK was increased, the phosphorylation of GSK3 and CREB were decreased, and the expression of BDNF was down-regulated in Sep, TMP and SB groups ( P<0.05). Compared with group Sep, the escape latency was significantly shortened, the ratios of time spent in the target quadrant were increased, the contents of IL-1β, TNF-α and IL-6 were decreased, the phosphorylation of hippocampus p38 MAPK was decreased, the phosphorylation of GSK3 and CREB were increased, and the expression of BDNF was up-regulated in TMP and SB groups ( P<0.05). Compared with group TMP, no significant change was found in the parameters mentioned above in group SB ( P>0.05). Conclusion:p38 MAPK/CREB signaling pathway is involved in the process of tetramethylpyrazine-induced reduction of hippocampal inflammatory responses in mice with SAE.