论文部分内容阅读
目的:探讨低剂量氢化可的松对脓毒性休克早期大鼠心肌损伤的作用及机制。方法:健康雄性SD大鼠72只，按随机数字表法分为假手术组（Sham组）、脂多糖（LPS）致脓毒性休克模型组（LPS组）、低剂量氢化可的松干预组（LD组）3组，每组24只。经股静脉注射LPS 20 mg/kg制备脓毒性休克大鼠模型；Sham组注射等量生理盐水。LD组于制模成功后经右股静脉注射氢化可的松5 mg/kg；Sham组和LPS组注射等量生理盐水。连续监测各组大鼠血压和心率（HR）；分别于制模后0、3、6 h各取8只大鼠进行动脉血气分析，用酶联免疫吸附试验（ELISA）检测血浆N末端B型脑钠肽前体（NT-proBNP）水平，用蛋白质免疫印迹试验（Western Blot）检测活化天冬氨酸特异性半胱氨酸蛋白酶3（caspase-3）及核转录因子- κB p65（NF-κB p65）表达；制模后6 h时取心肌组织，经苏木素-伊红（HE）染色后观察组织病理学改变，用原位末端缺刻标记试验（TUNEL）检测细胞凋亡率。结果:注射LPS后1 h大鼠平均动脉压（MAP）明显下降，之后逐渐升高，6 h时显著高于Sham组；而HR无明显改变，与Sham组比较差异无统计学意义；血乳酸（Lac）、剩余碱（BE）、血浆NT-proBNP水平及心肌组织caspase-3和NF-κB p65表达随时间延长逐渐升高，均于6 h达峰值，且明显高于Sham组。脓毒性休克早期予以低剂量氢化可的松干预后，大鼠MAP呈上升趋势，Lac、BE则缓慢下降，6 h时MAP、Lac、BE均显著低于LPS组〔MAP（mmHg，1 mmHg＝0.133 kPa）：98.6±7.5比106.1±8.5，Lac（mmol/L）：1.29±0.08比2.42±0.37，BE（mmol/L）：4.45±0.57比8.18±1.03，均n P<0.05〕。低剂量氢化可的松干预后3 h和6 h血浆NT-proBNP水平及心肌组织caspase-3、NF-κB p65表达均明显低于LPS组〔血浆NT-proBNP（ng/L）：3 h为2 740.56±97.31比4 425.60±743.32，6 h为2 638.81±205.12比4 993.01±373.78；心肌caspase-3/GAPDH：3 h为0.567±0.045比0.841±0.162，6 h为0.496±0.071比1.116±0.172；心肌NF-κB p65/GAPDH：3 h为0.852±0.734比1.232±0.115，6 h为0.783±0.047比1.383±0.215，均n P<0.05〕。HE染色显示，LPS组心肌细胞发生断裂，炎性细胞浸润；而LD组心肌组织病理学改变较LPS组明显减轻。TUNEL染色显示，LPS组心肌细胞凋亡增加，细胞凋亡率明显高于Sham组〔（82.41±1.57）%比（5.77±0.69）%，n P<0.05〕；而LD组心肌细胞凋亡率明显低于LPS组〔（27.82±1.77）%比（82.41±1.57）%，n P<0.05〕。n 结论:低剂量氢化可的松对脓毒性休克早期心肌组织具有保护作用，其机制可能与抑制心肌组织caspase-3及NF-κB p65的表达、减少细胞凋亡、减轻心肌抑制有关。“,”Objective:To investigate the effects and mechanisms of low-dose hydrocortisone on myocardial injury in early septic shock rats.Methods:Seventy-two healthy male Sprague-Dawley (SD) rats were divided into Sham group, lipopolysaccharide (LPS) model group (LPS group) and low dose hydrocortisone intervention group (LD group) according to the random number table method, with 24 rats in each group. The rat model of septic shock was produced by intravenous injection of LPS at 20 mg/kg. Sham group was injected with an equal amount of physiological saline. The LD group was injected 5 mg/kg of hydrocortisone via right femoral vein after model establishment. Sham group and LPS group were injected with an equal amount of physiological saline. Blood pressure and heart rate (HR) of rats in each group were continuously monitored. In each group, 8 rats were sacrificed for arterial blood gas analysis at 0, 3 and 6 hours after model establishment, and the level of plasma N-terminal B-type brain natriuretic peptide precursor (NT-proBNP) was detected by enzyme linked immunosorbent assay (ELISA). The expressions of cleaved-caspase-3 and nuclear factor-κB p65 (NF-κB p65) were detected by Western Blot. Myocardial tissue was harvested 6 hours after model establishment, the histopathological changes were observed by hematoxylin eosin (HE) staining, and the apoptosis rate of myocardial cells was detected by terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL).Results:After LPS injection, mean arterial pressure (MAP) decreased significantly at 1 hour, then gradually increased, and was significantly higher than Sham group at 6 hours. There was no significant change in HR, and the difference was not statistically significant compared with Sham group. Blood lactic acid (Lac), base excess (BE), plasma NT-proBNP level, myocardial tissue caspase-3 and NF-κB p65 expression increased with the extension of time, all reach the peak in 6 hours, and significantly higher than Sham group. After early treatment with low-dose hydrocortisone in septic shock, MAP showed an increasing trend and Lac, BE decreased slowly. At 6 hours, MAP, Lac and BE were significantly lower than those in the LPS group [MAP (mmHg, 1 mmHg = 0.133 kPa): 98.6±7.5 vs. 106.1±8.5, Lac (mmol/L): 1.29±0.08 vs. 2.42±0.37, BE (mmol/L): 4.45±0.57 vs. 8.18±1.03, alln P < 0.05]. The level of plasma NT-proBNP, and the expressions of caspase-3 and NF-κB p65 in myocardial tissue were significantly lower than those in LPS group at 3 hours and 6 hours after low-dose hydrocortisol treatment [NT-proBNP (ng/L): 2 740.56±97.31 vs. 4 425.60±743.32 at 3 hours, 2 638.81±205.12 vs. 4 993.01±373.78 at 6 hours; caspase-3/GAPDH: 0.567±0.045 vs. 0.841±0.162 at 3 hours, 0.496±0.071 vs. 1.116±0.172 at 6 hours; NF-κB p65/GAPDH: 0.852±0.734 vs. 1.232±0.115 at 3 hours, 0.783±0.047 vs. 1.383±0.215 at 6 hours, all n P < 0.05]. HE staining results showed that myocardial cells in the LPS group were broken and inflammatory cells infiltrated. The myocardial histopathological changes in LD group were significantly less than those in LPS group. TUNEL staining showed that the apoptosis of myocardial cells in LPS group increased, and the apoptosis rate was significantly higher than that in Sham group [(82.41±1.57)% vs. (5.77±0.69)%, n P < 0.05]. The apoptosis rate in LD group was significantly lower than that in LPS group [(27.82±1.77)% vs. (82.41±1.57)%, n P < 0.05].n Conclusion:Low-dose hydrocortisone plays a protective role in the myocardial injury of early septic shock, and its mechanism may be related to the inhibition of caspase-3 and NF-κB p65 expression, the reduction of apoptosis rate and myocardial inhibition.