Résumé
Objective To preliminarily investigate the role of Vitamin C in cecal ligation and puncture-induced septic brain injury.Methods Male specific pathogen free (SPF) Sprague-Dawley male rats were randomly assigned into control group,sham operation group,sepsis group and sepsis therapy group.The rats in sepsis group were prepared by cecal ligation and puncture.The rats in sepsis therapy group were injected sodium ascorbate through the tail vein 3 h after the cecal ligation and punature procedure.The animals in other groups were subjected only to subcutaneous bolus injection of 9 g/L saline only.Animals were evaluated by neurologic reflex scores before sacrifice and brain tissues were quickly removed at the indicated time points.Reactive oxygen species (ROS),superoxide dismutase (SOD),malondialdehyde (MDA),nitric oxide (NO),inducible nitric oxide synthase (iNOS) and catalase (CAT) were determined by using enzyme assay kits.Hematoxylin-eosin (HE) staining was used to observe morphological changes in brain tissues.Results The survival rate of the sepsis group (30％ at 7th day) was significantly lower than that of the control group (100％ at 7th day)and sham operation group(100％ at 7th day).The survival rate of the sepsis therapy group (45％ at 7th day)was significantly higher than that of the sepsis group(P ＜ O.05).The neurological reflex assessment began to decrease at 6 h in sepsis group and reached the lowest at 24 h (6.00 ± 0.53).The sepsis therapy group (7.62 ± 0.52) was significantly higher (P ＜ 0.05) than the sepsis group and began to recover at 72 h (8.63 ±0.52).ROS,SOD,MDA,NO and iNOS in the sepsis group and the sepsis therapy group reached a peak at 24 h,which decreased at 72 h.The value in sepsis therapy group was significantly decreased than that in the sepsis group,and the difference was statistically significant(P ＜0.05).CAT changed in the opposition.The SOD/CAT in sepsis group was the highest 24 h after the operation,while the ratio in sepsis therapy group was significantly improved.SOD/CAT and MDA were positively correlated(r =0.968,P ＜ 0.05).HE staining showed significant damage to the brain tissue structure in the sepsis group,however some improvement was observed in the sepsis therapy group.Conclusion Vitamin C can significantly improve the survival rate and encephalopathy prognosis in the cecal ligation and puncture SD rat models.The mechanism may be related to the reduction of oxidative stress.
Résumé
Objective To investigate the protective effects and mechanism of insulin(INS) on brain in septic rats,and explore the possible role of uncoupling protein 2 (UCP2) in these effects.Methods Fifty male specific pathogen free(SPF) Sprague-Dawley rats were randomly divided into normal control (CN) group(n=10),lipopolysaccharide(LPS) group(n=20) and INS group (n=20) according to random number table.The septic rat model was established through an intraperitoneal injection of 15 mg/kg LPS of gram-negative bacteria.The rats in the INS group received a 1 U/kg INS injection subcutaneously 30 minutes before the injection of LPS,and the rats in the CN group were given equivalent 9 g/L saline in the same way.Eight rats in each group were killed,and their cerebral cortex were collected after the injection of LPS for 24 h.Pathological change of cerebral cortex was detected by Hematoxylin-Eosin(HE) staining.The cerebral cortex mitochondia were extracted for detecting the levels of reactive oxygen species(ROS),malondialdehyde (MDA) and the activity of superoxide dismutase(SOD).Neuronal apoptosis was detected by terminal dexynucleotidyl transferase(TdT)-mediated dUTP nick end labeling staining.UCP2 mRNA expression was detected by quantitative real-time(RT)-PCR.Apoptosis-associated protein B lymphocyte tumor-2(Bcl-2),Bcl-2 associated X protein(Bax),cleaved cysteinyl aspartate specific protease(cleaved Caspase-9) and UCP2 protein expression were determined by Western blot.Results (1)Compared with the CN group,obvious abnormal pathological change was revealed by HE staining in cerebral cortex of rats in the LPS group and the INS group,but the pathological change was attenuated in the INS group compared with the LPS group.(2)Compared with the CN group,the levels of mitochondrial ROS[(210.01±14.09) RFU vs.(49.06±7.28) RFU] and MDA[(2.19±0.18) nmol/mg pro vs.(1.25±0.11)nmol/mg pro]in the LPS group significantly increased,whereas SOD activity significantly decreased [(238.49±35.60) U/g pro vs.(446.66±24.90)U/g pro],and the differences were significant(all P<0.05).Compared with the LPS group,the levels of ROS [(152.69±15.83) RFU vs.(210.01±14.09) RFU] and MDA[(1.55±0.14) nmol/mg pro vs.(2.19±0.18) nmol/mg pro] in the INS group decreased,while SOD activity increased[(327.8±23.26) U/g pro vs.(238.49± 35.60) U/g pro],and the differences were significant(all P<0.05).(3)Compared with the CN group,the neuronal apoptosis index of cortex in the LPS group was elevated[(54.16±6.84)% vs.(5.45±1.43)%],while the expression of Bcl-2 decreased (627±0.018 vs.0.739±0.020),but the expressions of Bax(0.768±0.019 vs.0.520±0.010) and cleaved Caspase-9(0.739±0.016 vs.0.467±0.030) increased,and the differences were significant(all P<0.05).Compared with the LPS group,the neuronal apoptosis index of cortex in the INS group decreased [(33.30±3.07)% vs.(54.16±6.84)%],but the Bcl-2 expression increased (0.743±0.022 vs.0.627±0.018),and Bax (0.687±0.034 vs.0.768±0.019) and cleaved Caspase-9(0.551±0.013 vs.0.739±0.016) were reduced,and the differences were significant (all P<0.05).(4)Compared with the CN group,the mRNA (2.248±0.155 vs.1.000±0.100) and protein expression of UCP2 (0.659±0.016 vs.0.599±0.018) were elevated in the LPS group.Compared with the LPS group,the UCP2 mRNA (2.944±0.117 vs.2.248±0.155) and UCP2 protein (0.719±0.018 vs.0.659±0.016) increased,and the differences were significant(all P<0.05).Conclusions INS can protect the brain of septic rats through alleviating mitochondrial oxidative stress and inhibiting the mitochondrial-initiated apoptotic pathway to reduce neuronal apoptosis.INS upregulates UCP2 expression in the brain of septic rats,which may play a role in the protective effects mentioned above.