ObjectiveTo investigate the protective effect and the regulation mechanism of oxaloacetate (OAA) on myocardial ischemia reperfusion injury in rats. MethodsSixty rats, weight ranged from 200 to 250 grams, were randomly divided into 6 groups:a negative control group, a sham operation control group, a model control group, an OAA pretreatment myocardial ischemia-reperfusion model group (three subgroups:15 mg/kg, 60 mg/kg, 240 mg/kg). We established the model of myocardial ischemia reperfusion of rats and recorded the internal pressure of left ventricle (LVSP), the maximal rate of left ventricular pressure change (±dp/dtmax) and left ventricular end diastolic pressure (LVEDP). We restored reperfusion 180 minutes after ligating the left anterior descending coronary artery 30 minutes and determinated cardiac troponin Ⅰ (cTn-I), lactate dehydrogenase (LDH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px). We took out heart tissues, stained it and calculated the infarcted size. We used the Western blot to detect the expression of NF-E2 related factor 2 (Nrf2), Kelch-like ECH-associated protein-1 (Keap1) and heme oxygenase-1 (HO-1). ResultsCompared with the sham operation group, heart function indexes in the negative control group had no significant difference (P>0.05). But in the model control group there was a decrease (P<0.05) And the serum levels of LDH, cTn-I, and myocardial infarcted size were significantly increased (P<0.01). Compared with the model control group, heart function indexes in the OAA pretreatment groups improved, the serum LDH, cTn-I activity, and infarct size decreased (P<0.05), SOD and GSH-Px activity increased (P<0.05). And these results were statistically different (P<0.01) in the high dose OAA pretreatment groups. Compared with the model control group, the expression of Keap1 in the OAA pretreatment group was down-regulated (P<0.001) while total Nrf2, nucleus Nrf2 and its downstream HO-1 was up-regulated (P<0.001), which suggested that OAA enhanced antioxidant capacity by (at least in part) Keap1-Nrf2 pathway, resulting in reducing myocardial damage and protecting myocardium after acute myocardial ischemia reperfusion injury. ConclusionOxaloacetate can provide protective effects on myocardial ischemia reperfusion injury through down-regulating the expression of Keap1 and up-regulating the expression of Nrf2 and its downstream peroxiredoxins to improve antioxidant capacity.
Objective To investigate the expression of transcriptional factors zinc finger Krüppel like transcription factor 2 ( Klf2) and NF-E2 related factor 2 ( Nrf2) /BTB CNC homology 1 ( Bach1) in rat bronchial epithelial cells stimulated by cigarette smoke extract ( CSE) , and explore the regulatingmechanism of γ-glutamylcysteine synthetase ( γ-GCS) expression in the oxidative condition. Methods Rat bronchial epithelial cells were harvested using enzyme digestion method, and intervened by 10% CSE for 6 hours. Then γ-GCS activity was detected by two enzymes method, and the nuclear transfer of Nrf2 /Bach1 in cells was detected by immunohistochemistry. Western blot and reverse transcription-polymerase chain reaction ( RT-PCR) techniques were used for detecting the protein and mRNA expressions of Klf2, Nrf2, Bach1, and γ-GCS in the cells. Results The γ-GCS activity was elevated in the CSE group. Immunohistochemical results showed that Nrf2 translocated from cytoplasm to nucleus in response to stimulation by CSE. On the contrary, Bach1 translocated from nucleus to cytoplasm in the same condition. Western blot results showed that protein levels of Klf2, Nrf2, Bach1, and γ-GCS were higher in the CSE group than those in the control group ( Plt;0.05) . RT-PCR results were the same as the Western blot results ( Plt;0.05) . Linear correlation analysis showed that γ-GCS expression was positively correlated with Klf2, Nrf2, and Bach1 ( Plt;0. 05) . Conclusion CSE might regulate the expression of γ-GCS through the transcription factors of Klf2, Nrf2, and Bach1.