Mechanism of mitogen-activated protein kinase kinase/extracellular signal regulated kinases/nuclear factor erythroid 2-relat-ed factor 2 signaling pathway involved in myocardial oxidative stress injury caused by hypothermia in mice

YOU Ping-fei; YU Xin-hui; DAI Jing; CAO Bin-yan; HU An; SHAO Bing; JIN Hong-xu; LIU Ying

doi:10.16048/j.issn.2095-5561.2024.05.04

Abstract：Objective To explore the effects of severe accidental hypothermia on mouse myocardium and to further clarify the possible mechanisms of mitogen-activated protein kinase kinase/extracellular signal regulated kinases/nuclear factor erythroid 2-related factor 2(MEK/ERK/NRF2)pathway involved in myocardial oxidative stress injury.Methods Twenty male C57BL/6 healthy mice were randomly divided into control groups(n=10)and model groups(n=10).The mice in the control group were routinely reared,and the mice in the model group were reared in a low-temperature environment to cause myocardial injury.The success of the model was verified by monitoring the changes in core body temperature,detecting the markers of myocardial injury,observing the changes in the cardiac macrostructure and of the two groups of mice;and the success of the model was verified by the detection of cardiac reactive oxygen species level by the kit,and by the detection of the expression of MEK1,ERK1/2,NRF2,superoxide dismutase2(SOD2),and malondialdehyde-5(MDA-5)proteins in myocardial tissues by Western blot,and the verification of the immunohistochemistry.MEK1,ERK1/2 protein expression and immunohistochemical verification.Results The levels of creatine kinase(CK),creatine kinase myocardial band(CK-MB)and lactatedehydrogenase(LDH)in model groups were higher than those of the control group,with statistically significant differences(P<0.05).Compared with the control group,hemorrhagic spots and edema were seen in the macroscopic specimens of the heart of the mice in the model group,whose surfaces were dull and deepened in color,and some of the edges were uneven;some of the myocardium appeared to be infiltrated with inflammatory cells,and the myocardial fibers appeared to be irregularly and staggeredly arranged.In the model group,the ROS level was higher than that of the control group,the MDA-5 protein expression was higher than that of the control group,the SOD2 protein expression was lower than that of the control group,the MEK1 protein expression was higher than that of the control group,the ERK1/2 protein expression was higher than that of the control group,and the proportion of the area area of positive areas for MEK1 and ERK1/2 was higher than that of the control group,with the difference being statistically significant(P<0.05).Conclusion Severe accidental hypothermia causes oxidative stress injury in mouse myocardium,and the mechanism of this oxidative stress injury may be related to the MEK/ERK/NRF2 signaling pathway.