ABSTRACT
Objective To investigate the effect of interleukin-1β (IL-1β) on the expression of synaptic protein SNAP-25 in the hippocampus in septic neonatal rat induced by systemic lipopolysaceharide (LPS) injection.Methods Sprague-Dawley (SD) rats were randomly divided into two groups:control group and sepsis group.The rat model of sepsis was produced by intraperitoneal injection of 1 mg/kg LPS,and rats in the control group were injected with an equal volume of 0.01 mol/L phosphate buffered saline (PBS).The expression levels of IL-1β and IL-1R1 in the hippocampus at 1,2 and 3 d,and synaptosomal-associated protein 25 (SNAP-25) at 7,14 and 24 d after LPS intraperitoneal injection were detected by Western blot.After cultured for 24 h,primary hippocampal neurons were divided into four groups including the control group,IL-1β (40 ng/mL) treatment group,IL-1β (40 ng/mL) + IL-1Ra (40 ng/mL) treatment group,and IL-1Ra (40 ng/mL) treatment group.The effect of IL-1β on SNAP-25 expression in primary hippocampal neuron was determined by Western blot and real-time PCR.The purity of hippocampal neurons were identified by NeuN immunofluorescence staining and the activity of neurons were detected by CCK-8 assay.All data were analyzed by SPSS version 22.0.The data were analyzed by student-t test and Dunnett-t test.The interaction effects were analyzed by factorial ANOVA.Differences were considered to be statistically significant if P＜ 0.05.Results Compared with the control group,the expressions of IL-1β and IL-1R1 were significantly increased in the hippocampus at 1,2 and 3 d after intraperitoneal injection of LPS (P＜0.05).The expression of SNAP-25 protein was decreased at 7,14,and 28 d after intraperitoneal injection of LPS (P＜0.05).The purity of primary neurons was about up to 92％.The activity of primary neurons was not relatively changed after treated with IL-1β at a dose less than 40 ng/mL.The level of SNAP-25 protein was obviously decreased in primary neurons at 24 h after IL-1β treatment (P＜0.05).IL-1Ra treatment might reverse the effect of IL-1β on primary neurons (P＜0.05).While,the expression of SNAP-25 mRNA was not statistically different in each group (P＞0.05).Conclusions IL-1β may possibly inhibit the expression level of SNAP-25 protein in the hippocampus in the septic rats through its receptor IL-1R1,which would contribute to cognitive dysfunction of septic neonatal rats in later life.