RÉSUMÉ
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, all 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 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)%, 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)%, P < 0.05]. 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.
RÉSUMÉ
This paper is to explore changes of intestinal mucosal barrier, intestinal flora, and bacterial translocation in rats with severe acute pancreatitis (SAP). Twenty four male SD rats were randomly divided into the control group (n = 10) and the experimental group (n = 14). The model of severe acute pancreatitis of rats was induced by the method of injecting adversely 5% sodium taurocholate into the common biliary-pancreatic duct. All of the rats were killed after 24 hours and the level of the serum amylase and the plasma endotoxin was determined after that. The pathological changes of pancreas and small intestine were observed through hematoxylin-eosin staining (HE staining) and the abdominal viscera bacterial translocation rates were tested. With the method of real-time polymerase chain reaction (RT-PCR) the quantity of the intestinal flora was analyzed. In the control group, the level of Escherichia coli, Lactobacillus and Bifidobacterium were 2.08 ± 1.29, 11.04 ± 7.55 and 12.21 ± 4.95, respectively. On the contrast, the level of Escherichia coli in the cecum contents was much higher (9.72 ± 3.58, P < 0.01), while the Lactobacillus number was decreased significantly (0.67 ± 0.34, P < 0.01), and the Bifidobacterium number was also decreased (4.59 ± 3.42, P < 0.05) in the experimental group, so the ratio of Bifidobacterium/Escherichia coli was reversed. Besides, in the experimental group, the plasma endotoxin positive rates and the bacterial translocation rates were much higher (P < 0.01 or P < 0.05) and the pathology scores of pancreas and small intestines were also significantly higher (P < 0.01) than those in the control group. These results indicated that in severe acute pancreatitis rats, the intestinal mucosal barrier was severely damaged and the dysbacteriosis occurs in the intestinal canal. And these might relate to the occurrence and development of multiple organ infection.