| Objective: Cardiovascular diseases,such as myocardial hypertrophy,heart failure,myocardial infarction,atrial fibrillation,and hypertension,pose a significant threat to human health and are a leading cause of death globally.Heart failure is the final outcome of various cardiovascular conditions,and despite the availability of clinical drugs,instrument therapy,and adjuvant therapy,the prognosis for patients with heart failure remains poor.Atrial fibrillation,the most common type of arrhythmia,is on the rise and is expected to affect over 16 million people globally by 2050,with a current estimate of around 8 million patients in China alone.As the population ages,the incidence of atrial fibrillation continues to increase.Studies have shown that hypertension plays a critical role in the development of heart failure and atrial fibrillation.Hypertension triggers inflammation,fibrosis,and oxidative stress in the heart,primarily through the renin-angiotensin-aldosterone system,leading to heart remodeling and ultimately to heart failure or atrial fibrillation.Farrerol,a flavonoid extracted from plants,has numerous biological functions such as scavenging free radicals,regulating enzyme activity,inhibiting cell proliferation,and reducing inflammation.In the context of cardiovascular diseases,Farrerol has been shown to prevent the activation of NLRP3 inflammatory bodies in macrophages and the release of inflammatory cytokines,thus preventing the onset and progression of cardiac ischemia-reperfusion in mice.However,it is not known whether Farrerol can prevent hypertension-induced myocardial hypertrophy and atrial fibrillation.In this study,the researchers aim to investigate the effects of Farrerol on myocardial hypertrophy and atrial fibrillation induced by angiotensin Ⅱ in mice.They want to determine if Farrerol can prevent angiotensin Ⅱ-induced heart remodeling by impacting cardiac inflammation,fibrosis,oxidative stress,and other remodeling responses,and ultimately prevent the onset and progression of heart failure or atrial fibrillation.Methods: Part Ⅰ: Animal Experiment: In this study,C57BL/6J mice were divided into four groups: control,Farrerol,Ang Ⅱ,and Ang Ⅱ+Farrerol groups.The mice in the Ang Ⅱ group were given Angiotensin Ⅱ injections(1000ng/kg/min)for 2 weeks,while the mice in the Farrerol group were given Farrerol injections(10mg/kg).The mice in the Ang Ⅱ+Farrerol group were given both Angiotensin Ⅱ and Farrerol injections.Blood pressure was measured every three days,and the heart function was evaluated using echocardiography.To evaluate myocardial remodeling,wheat germ agglutinin staining was used to observe myocyte hypertrophy,Masson and Collagen Ⅲ staining were used to observe cardiac fibrosis,and H&E and CD68 staining were used to observe inflammatory cell infiltration.The level of oxidative stress in the heart tissue was evaluated using DHE and nitrotyrosine staining.The expression of genes and proteins related to inflammation,fibrosis,and oxidative stress was evaluated using qPCR(Cloa1 and cybb)and Western Blot(p-ERK 1/2,NOX2,andα-SMA).Part Ⅱ: In the second part of the study,C57BL/6J mice were divided into three groups:control,Ang Ⅱ,and Ang Ⅱ+Farrerol groups.The mice in the Ang Ⅱ group were given Angiotensin Ⅱ injections(2000ng/kg/min)for 3 weeks,while the mice in the Ang Ⅱ+Farrerol group were given both Angiotensin Ⅱ and Farrerol injections(10mg/kg).The left atrial diameter was evaluated using echocardiography,and the incidence and duration of atrial fibrillation were measured through electrical stimulation.The degree of atrial fibrosis was evaluated using Masson,Collagen Ⅲ(IHC)staining,and qPCR(Collagen Ⅰ,Collagen Ⅲ,and α-SMA).The level of oxidative stress in the atrial tissue and serum was evaluated using DHE staining,qPCR(NOX2 and NOX4),MDA,and GPX kit.The infiltration of inflammatory cells in the atrial tissue was evaluated using qPCR(TNF-α and IL-6).Results: The first part of the findings showed that by measuring blood pressure,it was observed that Angiotensin Ⅱ(Ang Ⅱ)could increase blood pressure in mice,while Farrerol was able to inhibit the increase in blood pressure induced by Ang Ⅱ.Ultrasound revealed that Ang Ⅱ could increase the ejection fraction and short axis shortening rate in mice,but Farrerol was able to mitigate these increases.The LDH test showed that Farrerol had no effect on myocardial injury.WGA staining showed that Ang Ⅱ could cause myocardial cell hypertrophy in mice,while Farrerol could inhibit this hypertrophy.Masson and IF(Collagen Ⅲ)staining indicated that Ang Ⅱ could worsen the degree of fibrosis in mouse heart tissue,but Farrerol could reduce this fibrosis.H&E and IHC(CD68)staining revealed that Ang Ⅱ could promote the infiltration of inflammatory cells in the mouse heart,while Farrerol could inhibit this infiltration.Nitrotyrosine(DHE)and Nitrotyrosine(IHC)staining showed that Ang Ⅱ could cause oxidative stress in mice,while Farrerol could reduce this stress.qPCR and Western Blot analysis indicated that Ang Ⅱ could increase the expression of genes and proteins related to inflammation,fibrosis,and oxidative stress in mouse heart tissue,but Farrerol could reduce this expression.In the second part,by measuring blood pressure,it was found that Farrerol group could inhibit the blood pressure increase induced by high concentration Ang Ⅱ.Farrerol was found to alleviate Ang Ⅱ-induced atrial diameter increase in mice by ultrasound.Masson,IHC(Collagen Ⅲ)and qPCR showed that Ang Ⅱ could promote the level of atrial fibrosis in mice.Farrerol could inhibit the degree of atrial fibrosis induced by Ang Ⅱ.Through DHE staining,qPCR,MDA and GPX kits,Ang Ⅱ was found to promote the level of oxidative stress in mouse atrial tissue and serum,while Farrerol could inhibit the level of oxidative stress in mouse atrial tissue and serum.qPCR showed that Ang Ⅱ could promote the level of atrial tissue inflammation in mice,while Farrerol could inhibit the level of atrial tissue inflammation induced by Ang Ⅱ.Conclusion: the findings from this study suggest that Farrerol may have a protective effect on the heart by inhibiting the harmful effects of Ang Ⅱ,such as increased blood pressure,myocardial hypertrophy,fibrosis,inflammation,and oxidative stress.Farrerol appears to achieve this effect by inhibiting the AT1 R signaling pathway and promoting the expression of antioxidant genes.However,these results are based on a mouse model and further studies in human subjects are needed to confirm these effects and to evaluate the safety and efficacy of Farrerol for the treatment of cardiovascular diseases. |
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