大鼠烧伤后早期心肌组织核因子κB活化对细胞因子表达及心肌功能的影响

Effect of NF-κB activation on the early expression of tumor necrosis factorαand myocardial dysfunction in burned rats

目的观察核因子(NF)κB活化在大鼠烧伤后早期心肌组织表达肿瘤坏死因子(TNF)α及心肌功能损害中的作用,进一步阐明烧伤后早期心肌功能损害的发生机制。方法将170只Wistar大鼠随机分为对照组(20只)、烧伤组(90只)、吡咯烷二硫代氨基甲酸盐(PDTC)组(60只)。后两组大鼠均于背部造成35％TBSAⅢ度烧伤后,立即腹腔注射等渗盐水,且PDTC组同时皮下注射PDTC 250 mg／kg。对照组除不烧伤外,其余处理同烧伤组。伤后3、6、12、24 h采用八导生理记录仪记录左心室收缩压(LVSP),左心室舒张末期压(LVEDP),室内压最大上升、下降速率(+dp／dtmax、-dp／dtmax);逆转录聚合酶链反应和原位杂交法观察心肌组织TNF-αmRNA的表达。伤后1、3、6、12、24 h采用凝胶电泳迁移率变动分析法检测心肌组织NF-κB活性,以积分吸光度(A)值表示。对照组作相同检测。结果伤后3～24 h烧伤组大鼠LVSP、±dp／dtmax低于对照组(P<0．01),而LVEDP高于对照组(P<0．01)。伤后3 h烧伤组大鼠心肌组织TNF-αmRNA表达明显高于对照组, 6 h达峰值(P<0．01),它在心肌细胞中表达尤为明显。伤后1 h烧伤组大鼠心肌组织NF-κB活性迅速升高[积分A值为(20．3±3．4)×104],明显高于对照组积分A值(2．2±0．4)×104,3 h时达峰值,24 h时仍高于对照组(P<0．01)。与烧伤组比较,PDTC组上述指标有较明显的改善(P< 0．01)。结论大鼠严重烧伤后心肌组织NF-κB被活化,使其表达和释放促炎细胞因子,在心肌功能损害发生过程中起重要作用。

Objective To investigate the effect of NF-κB activation on the early expression of proinflammatory cytokines in myocardium and early myocardial dysfunction in burn rats. Methods One hundred and seventy Wistar rats were enrolled in the study and randomly divided into three groups, i.e. control（C, n = 20, with isotonic saline solution） , burn （ B, n = 90, with isotonic solution after burns） and pyrrolidine dithioncarbamate （ PDTC,n = 60, with isotonic saline and 250 mg/kg PDTC after burns） groups. The rats in B and PDTC groups were inflicted with 35% TBSA full-thickness burns on the back. The activity of myocardial NF-κB was determined by electrophorctic mobility shift assay at 1 , 3, 6, 12,24 postburn hours （PBH） ,with expression of intergral absorbance（ A ） value . The expression of myocardial tumor necrosis factor α（ TNF- α） mRNA was assessed by reverse transcription polymerase chain reaction （RT-PCR） and in situ hybridization at 6, 12 PBH, with expression of A value. The left ventficular systolic pressure（LVSP） , the left ventricular end diastolic pressure （LVEDP） ,the maximum rate of rise of left ventficular pressure （ ＋ dp/dt max） were also observed at 3, 6, 12,24 PBH. Results The activity of myocardial NF-κB in B group was markedly increased at 1 PBH [ （20.3 ± 3.4） × 10^4A ] ,which was obviously higher than that in C group [ （2.2 ± 0. 4） × 10^4A , P 〈 0.01 ]. It peaked at 3 PBH, and was still evidently higher than that in C group at 24 PBH （ P 〈0.01）. The expression of TNF-α mRNA was obviously higher than that in C group at 3 PBH （ P 〈0.01 ） , peaking at 6 PBH, and it was mainly expressed in myocardium. The expression of LVSP and ＋ dp/dt max were lower, but LVEDP was higher than that in C group during 3 -24 PBH （ P 〈0.01 ）.Compared with that in B group,these indices were ameliorated in PDTC group. Conclusion The myocardial NF-κB might be activated after severe burns, which promotes the expression and release of proinflammatory cytokines in myocardium, and this may play a pivotal role in the myocardial dysfunction.