革兰氏阳性菌和阴性菌诱导脓毒症大鼠器官功能障碍的差异

Differences in organ dysfunction between gram-positive and gram-negative bacteria-induced sepsis in rats

目的评价革兰氏阳性(G^(+))菌和阴性(G^(-))菌诱导脓毒症大鼠器官功能障碍的差异。方法成年雄性SD大鼠52只,体重340~380 g,15~18周龄,按照随机数字表法分为3组:对照组(C组,n=12)、G^(-)菌组(n=20)和G^(+)菌组(n=20)。G^(+)菌组和G^(-)菌组分别腹腔注射灭活金黄色葡萄球菌、大肠埃希菌悬液法建立G^(+)菌、G^(-)菌脓毒症模型。记录注射灭活细菌后36 h内生存情况。于注射灭活细菌后6、12、24、36 h测定MAP、血小板计数(Plt)、氧合指数(OI)、血清TNF-α、cTnT、TBIL、Cr、NSE和乳酸(Lac)浓度。于注射灭活细菌后12、36 h行条件性恐惧实验和旷场实验,TUNEL法测定海马CA1区神经元凋亡率,伊文思蓝法测定血脑屏障通透性。于注射灭活细菌注射后36 h进行心、肺、肾和脑组织病理学观察。结果与C组相比,G^(-)菌组和G^(+)菌组穿越格数减少,僵直时间百分比降低,神经元凋亡率和血脑屏障通透性升高,生存率降低(P<0.05);注射灭活细菌后6 h时G^(+)菌组血清TNF-α浓度升高,G^(-)菌组OI降低,血清cTnT、Cr、TNF-α和Lac浓度升高(P<0.05);注射灭活细菌后12 h时G^(+)菌组血清cTnT、Cr、NSE、TNF-α和Lac浓度及G^(-)菌组血清cTnT、Cr、TNF-α和Lac浓度升高,2组OI、MAP和Plt降低(P<0.05);注射灭活细菌后24、36 h时G^(+)菌组和G^(-)菌组血清cTnT、TBIL、Cr、NSE、TNF-α和Lac浓度升高,OI、MAP和Plt降低(P<0.05)。与G^(+)菌组相比,G^(-)菌组注射灭活细菌后12 h时血清TNF-α和cTnT浓度、神经元凋亡率降低(P<0.05);注射灭活细菌后24 h时血清TNF-α、Lac浓度升高,血清cTnT浓度、OI、MAP和Plt降低(P<0.05);注射灭活细菌后36 h时血清Cr、NSE、TNF-α、Lac浓度升高,OI、MAP和Plt降低,僵直时间百分比、神经元凋亡率及血脑屏障通透性升高(P<0.05)。结论大鼠G^(-)菌脓毒症多出现早期呼吸功能障碍和多器官功能衰竭,G^(+)菌脓毒症更易导致早期循环和神经功能障碍,随着病情进展,G^(-)脓毒症表现为更为严重的器官功能障碍和高病死率。

Objective To evaluate the differences in organ dysfunction between gram-positive and gram-negative bacteria-induced sepsis in rats.Methods Fifty-two adult male Sprague-Dawley rats,weighing 340-380 g,aged 15-18 weeks,were divided into 3 groups using a random number table method:control group(C group,n=12),G^(-)bacteria group(n=20),and G^(+)bacteria group(n=20).The G^(+)and G^(-)septic models were developed by intraperitoneal injection of inactivated Staphylococcus aureus and Escherichia coli suspension in G^(+)and G^(-)bacteria groups,respectively.The survival status within 36 h after injection of inactivated bacteria was recorded.Mean arterial pressure(MAP),platelet count(Plt),oxygenation index(OI)and serum concentrations of tumor necrosis factorα(TNF-α),cardiac troponin T(cTnT),total bilirubin(TBIL),creatinine(Cr),neuron-specific enolase(NSE)and lactic acid(Lac)were measured at 6,12,24 and 36 h after injection of inactivated bacteria.Fear conditioning test and open field test were performed at 12 and 36 h after injection of inactivated bacteria.The apoptosis rate of neurons in hippocampal CA1 area was measured by TUNEL,and the permeability of blood-brain barrier was measured by Evans blue method.The histopathological changes of lung,heart,kidney and brain tissues were examined at 36 h after injection of inactivated bacteria.Results Compared with C group,the number of crossing grids and percentage of time spent freezing were significantly decreased,the apoptosis rate of neurons and permeability of blood-brain barrier were increased,and the survival rate was decreased in G^(-)bacteria group and G^(+)bacteria group(P<0.05);the serum TNF-αconcentration was significantly increased in G^(+)bacteria group,and the serum cocentration of OI was significantly decreased,and the serum concentrations of cTnT,Cr,TNF-αand Lac were increased in G^(-)bacteria group at 6 h after injection of inactivated bacteria(P<0.05);the serum concentrations of cTnT,Cr,NSE,TNF-αand Lac in G^(+)bacteria group and serum concentrations of cTnT,Cr,TNF-αand Lac in G^(-)bacteria group were increased,and the OI,MAP and Plt were decreased at 12 h after injection of inactivated bacteria in both groups(P<0.05);the serum concentrations of cTnT,TBIL,Cr,NSE,TNF-αand Lac were increased,and OI,MAP and Plt were decreased at 24 and 36 h after injection of inactivated bacteria in G^(+)bacteria group and G^(-)bacteria group(P<0.05).Compared with G^(+)bacteria group,the serum concentrations of TNF-αand cTnT and apoptosis rate of neurons were significantly decreased at 12 h after injection(P<0.05);the serum concentrations of TNF-αand Lac were significantly increased,the serum concentrations of cTnT,OI,MAP and Plt were decreased at 24 h after injection of inactivated bacteria(P<0.05);the serum concentrations of Cr,NSE,TNF-αand Lac were significantly increased,OI,MAP and Plt were decreased,and the percentage of time spent freezing,apoptosis rate of neurons and permeability of blood-brain barrier were increased at 36 h after injection of inactivated bacteria in G^(-)bacteria group(P<0.05).Conclusions Early respiratory dysfunction and multiple organ failure often occur in G^(-)bacteria sepsis,while G^(+)bacteria sepsis is more likely to cause early circulatory and neurological dysfunction,and G^(-)sepsis presents with more serious organ damage and high fatality rate as the disease progresses.