| Objective: Under conditions of oxidative stress,hypoxia,and nutrient deficienc y,the endoplasmic reticulum is stressed.ERS restores cellular homeostasis by reduc ing protein synthesis inside the endoplasmic reticulum,accelerating the degradation of misfolded proteins,and selectively inducing the expression of protective proteins.PERK/eIF2α/ATF4 signaling pathway is one of the ERS pathways that can reduce t he number of target proteins crossing the endoplasmic reticulum by triggering the a ttenuation of protein synthesis and The ERS pathway is one of the ERS pathways t hat can promote normal endoplasmic reticulum function and maintain cellular home ostasis by triggering a reduction in protein synthesis and reducing the number of pr oteins crossing the endoplasmic reticulum.It has been found that exercise can caus e activation of endoplasmic reticulum stress in the myocardium,but there are still no studies on whether there are differences in different atrial endoplasmic reticulum stress signaling pathways.Since the activation levels of different atrial signaling pat hways are different,different activation levels may have different effects on the str uctural and metabolic functions of the cardiac atria.Therefore,in this experiment,we constructed a 4-week endurance exercise model to investigate whether 4-week e ndurance exercise can induce the generation of endoplasmic reticulum stress in the myocardium and whether there are differences in the activation levels of PERK/eIF2α/ATF4 signaling pathway in the myocardium of different atrial exercise,so as to provide a theoretical basis for reducing exercise injury in the myocardium.Methods: In this experiment,eight-week-old SPF-rated male SD rats were rand omly grouped into a quiet control group and an exercise group.The exercise group was subjected to a one-time exhaustive exercise with 4 weeks of endurance trainin g,and the training regimen was 5 days of training and 2 days of rest per week.I n the first week,the training speed was 15 m/min,15 min/d,and the slope of the running platform was 0°;in the second week,the training speed was 20 m/min,30min/d,and the slope of the running platform was 5°;in the third week,the trainin g speed was 26 m/min,60 min/d,and the slope of the running platform was 10°;in the fourth week,the training speed was kept at 26 m/min,the exercise time was kept at In the fourth week,the training speed was kept at 26 m/min,the exercise time was kept at 60 min/d,and the slope of the running platform was kept at 10°, and the last day of training was run to exhaustion.Blood sampling from the abdo minal aorta and different atrial chambers of the myocardium were performed 24 h af ter the last exhaustive exercise.CRP levels in serum were measured by enzyme-lin ked immunoassay;HE staining was performed to observe the basic morphology of different atrial myocardial cells;Western blot was performed to detect the activation levels of PERK and eIF2α and the protein expression of ATF4 in different atrial myocardium.The experimental data were statistically analyzed by SPSS.23 software, and data were considered significantly different at P<0.05.Results: The serum CRP results showed that no significant changes were obser ved in the serum CRP levels of rats in the exercise group compared to the quiet c ontrol group.The HE staining results showed that partial edema and mild faint stai ning occurred in the left and right atria and left and right ventricular myocytes in t he exercise group compared with the quiet control group,but there was no signific ant difference between the atria and ventricles.Compared with the quiet control gro up,the activation levels of PERK and eIF2α in the left atrium of rats in the exerci se group,and the protein expression of ATF4 did not change significantly(P>0.05);the activation levels of PERK and eIF2α in the left ventricle of rats in the exe rcise group,and the protein expression of ATF4 did not change significantly(P>0.05);the activation levels of PERK and eIF2α in the right atrium of rats in the exe rcise group,and the protein expression of ATF4 The activation levels of PERK an d eIF2α in the right atrium of rats in the exercise group,and the protein expressio n of ATF4 did not change significantly(P>0.05);the activation levels of PERK a nd eIF2α in the right ventricle of rats in the exercise group,and the protein expres sion of ATF4 did not change significantly(P>0.05).Conclusion: Four-week endurance-trained rats failed to induce activation of the PERK/eIF2α/ATF4 signaling pathway after a single exhaustive exercise;and no sign ificant changes were observed in the activation levels of the PERK/eIF2α/ATF4 sig naling pathway in different atrial compartments. |
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