Study On Atrial Structural Remodeling In Chronic Intermittent Hypoxia Rats

Objective:The rat model of chronic intermittent hypoxia was established to observe the general pathological changes and fibrosis of atrial tissue,and the protein expression of extracellular signal-regulated kinase 1/2,the phosphorylated extracellular signal-regulated kinase 1/2 and nuclear transcription factor kappa B.The study was conducted to discuss the effects of chronic intermittent hypoxia on atrial structural remodeling in SD rats and related signal transduction pathway of fibrosis.Methods:12 Sprague-Dawley(SD)healthy male rats(250-300g)were randomly divided into two groups in one week of acclimation,one is control group(CTL group)and the other is chronic intermittent hypoxia group(CIH group),4 rats in CTL group,and 8rats in CIH group.Normal feeding was given in CTL group and 5 hours intermittent hypoxia per day for 3 weeks was prepared to establish chronic intermittent hypoxia rats model in CIH group.All the left and right atrial tissue of all rats were extracted under anaesthesia in the end of the experiment and fixed in 4% formaldehyde solution to make paraffin sections.The morphology of atrial tissue was observed by HE staining;the features of atrial fibrosis,collagan volume fraction(CVF)was evaluated by Masson staining;the protein expression levels of extracellular signal-regulated kinase 1/2(ERK1/2),phosphorylated extracellular signal-regulated kinase 1/2(p-ERK1/2)and nuclear transcription factor kappa B(NF-?B)was determined by immunohistochemical staining for semi quantitative analysis to observe the changes of ERK and NF-?B signal transduction pathway.Results:1.Compared with the CTL group,heterogeneity in the size and arrangement of atrial myocytes was found in the CIH group by HE staining.2.Compared with the CTL group,myocardial tissue space was increased,obvious atrial interstitial fibrosis and higher degree of atrial fibrosis(CVF)wereobserved in CIH group by Masson staining.3.The protein expression of ERK1/2?p-ERK1/2 and NF-?B was positive in the atrial tissue in both CTL group and CIH group by immunohistochemistry staining.However,compared with the CTL group,the protein expression level of ERK1/2,p-ERK1/2,NF-?B was elevated and the ratio of p-ERK1/2/ERK1/2 was increased in CIH group.Conclusion:1.The structural disorder of atrial muscle cells and fibrosis of atrial interstitial tissue in rats induced by chronic intermittent hypoxia could cause atrial structural remodeling.2.ERK and NF-?B signaling transduction pathway was activated by chronic intermittent hypoxia and then participated in the occurrence of atrial fibrosis,but the specific mechanism needed to be further investigated.