Effects Of Substance P And Neurogenic Inflammation In Heptic Immuine Injury Induced By Con A In Mice

Objective T o set up the mouse model of hepatic immune injury induced by concanavalin A (Con A) and investigate the role of substance P and neurogenic inflammation mediated by SP in this hepatitis model. Meanwhile, we also evaluate the protective effects of NK1-receptor antagonist L-703,606 on hepatic immune injury with assessment of serological, histological and expression of several cytokines. We hope to reveal the mechanism of SP in the induction and maintenance of inflammation and to provide the experimental basis for the clinical treatment or reversion of liver injury .Methods sixty female mice were divided into three groups randomizedly: saline control group (group 1),Con A model group (group 2) and L-703,606 pretreated group (group 3). Mice in group 1 and group 2 were injected with saline only and Con A 20 mg/kg via the tail vein. Mice in group 3 were administrated with L-703,606 in dose of 10 mg/kg before Con A challenge. 6 hours later all mice were anesthetized to gain blood from eye sockets and then killed for liver. SP contents in liver homogenates of group 1 and 2 were detected by enzyme-linktimmunosorbent assay (ELISA), Neurokinin-1 receptor expression was examined by reverse transcription and PCR(RT-PCR) ; Meantime, Liver damage was assessed by serum transaminase ALT,AST measurement,histological evaluation. C ytokine TNF-αand IFN-γmRNA expression were examined by reverse transcription and real-time PCR. Results (1) SP contents in liver homogenates were significantly increased in model group ; Moreover, the expression of NK-1R mRNA in model group was obviously higher than those in control group (P<0.05); (2) There are edema formation, hepatocellular apoptosis and granulocyte infiltration in livers of model group, and L-703,606 can significantly reduce these signs; (3) ALT,AST activity were all increased in model and L-703,606 pretreated group, but the later group is dramatically reduced(P< 0.01). (4)The expression of proinflammatory mediators TNF-αand IFN-γmRNA were also significantly reduced in L-703,606 pretreated group campared to model group (P < 0.05) .Conclusion1. We established hepatic immune injury in mice successfully in this study. Histological observing show that there are edema formation, hepatocellular apoptosis and granulocyte infiltration in livers of model group.2. SP contents in liver homogenates and the expression of NK-1R mRNA in model group were obviously higher than those in control group. These findings suggest that neurogenic inflammation induced by SP may play an important role in this hepatitis model.3. Neurokinin-1 receptor antagonist L-703,606 can significantly alleviate concanavalin A-induced liver injury by the detection of serum transaminase,histological observing and proinflammatory mediators. It demonstrated that intervention of SP and its receptor had certain therapeutic effect on liver inflammation.