Oroxin B Resembles Bisoprolol in Attenuating Beta1-Adrenergic Receptor Autoantibody-Induced Atrial Remodelling via the PTEN/AKT/mTOR Signalling Pathway

Beta1-adrenergic receptor autoantibodies (beta 1-AAbs) promote atrial remodelling and ultimately lead to the development of atrial fibrillation (AF). Oroxin B is a natural flavonoid glycoside with a variety of biological activities, including anti-inflammatory and autophagy-promoting effects, and has therapeutic benefits for a variety of diseases. The aim of this study was to investigate the potential therapeutic role of Oroxin B in the development of beta 1-AAb-induced atrial fibrillation and to elucidate the underlying mechanisms involved. We established a rat model of beta 1-AAb-induced atrial fibrillation via active immunisation. The first stage was divided into three groups: the control group, the beta 1-AAb group and the beta 1-AAb + bisoprolol group. The second stage was divided into three groups: the control group, the beta 1-AAb group and the beta 1-AAb + Oroxin B group. Serum levels of beta 1-AAbs, atrial tissue levels of cyclic monophosphate (cAMP), atrial electrophysiological parameters, cardiac structure and function, mitochondrial structure, autophagy levels, cardiomyocyte apoptosis and myocardial fibrosis were examined. The results showed that bisoprolol, a beta 1-blocker, improved beta 1-AAb-induced atrial electrical remodelling, reduced atrial collagen deposition, ameliorated the increase in LAD and regulated the balance of autophagy and apoptosis in atrial myocytes through the PTEN/AKT/mTOR signalling pathway. Oroxin B, a PTEN agonist, can improve the impairment of autophagy homeostasis and apoptosis in atrial tissue by activating the PTEN/AKT/mTOR signalling pathway, thereby improving atrial structure and electrical remodelling. Moreover, Oroxin B may play a therapeutic role in beta 1AAb-induced atrial fibrillation. In conclusion, our results demonstrate the potential therapeutic role of Oroxin B in beta 1AAb-induced atrial fibrillation and the underlying mechanisms, suggesting that Oroxin B may be an effective antiarrhythmic medication.