Establishment of a rat model of sepsis induced by muramyl dipeptide after scald burn / 中华麻醉学杂志

ABSTRACT

Objective To establish a rat model of sepsis induced by muramyl dipeptide (MDP) after scald burn.Methods Fifty SPF male Sprague-Dawley rats,aged 2-3 months,weighing 200-250 g,were randomly divided into 3 groupscontrol group (group C,n =10),scald group (group S,n =10) and MDP group (n =30).The rats were subjected to a third-degree scald burn covering 20% of total body surface area in groups S and MDP.The rats were only exposed to 20 ℃ water in group C.MDP 5 mg/kg was injected via the femoral vein at 24 h after scald bum in group MDP.Arterial blood samples were collected at 1,6 and 24 h after MDP injection in group MDP,at 24 h after scald burn in group S,or at 24 h after exposure to 20 ℃ water in group C for blood gas analysis and for measurement of white blood cell (WBC) and platelet (Plt) counts,serum aminotransferase (ALT),aspartate transferase (AST),total bilirubin (TB),creatinine (Cr) and blood urea nitrogen (BUN) levels,creatine kinase isoenzyme-MB (CK-MB) activity,and plasma tumor necrosis factor-α (TNF-α),interferon-γ(IFN-γ),interleukin-6 (IL-6),IL-10 and high mobility group box 1 protein (HMGB-1) levels.The rats were sacrificed after collecting blood samples,and heart,liver,lung,and kidney specimens were obtained for microscopic examination of pathologic changes.The activity of myeloperoxidase (MPO) in lung tissues was measured.Another 90 male Sprague-Dawley rats were randomly divided into 3 groups and treated as the method previously described for record of the survival rate within 72 h.Results Compared with C group,the plasma IL-6,IL-10,IFN-γ and HMGB1 levels,WBC count,serum ALT,AST,and BUN levels and MPO activity were significantly increased,and the survival rate within 72 h was decreased in S group,and the plasma TNF-α,IL-6,IL-10,IFN-γand HMGB-1 levels,serum ALT,AST,TB,BUN,Cr and CK-MB levels,MPO activity,PaCO2 and BE value were significantly increased,and WBC and PLT counts,pH value,PaO2 and survival rate within 72 h were decreased in MDP group (P ＜ 0.05).Compared with S group,the plasma TNF-α,IL-6,IFN-γ and HMGB-1 levels,serum ALT,AST,TB,BUN,Cr and CK-MB levels,MPO activity,PaCO2 and BE value were significantly increased,and WBC and Plt counts,pH value,PaO2 and survival rate within 72 h were decreased in MDP group (P ＜ 0.05).The pathologic changes of heart,liver,lung and kidney were obvious in S and MDP groups and severer in MDP group.Conclusion After a third-degree 20% total body surface area scald burn,MDP induces excessive production of inflammatory cytokines accompanying with multiple organ damage ; thus the model of sepsis is successfully established after scald burn in rats.