Methotrexate improves left ventricle systolic and diastolic function in induced Takotsubo myocardiopathy rats.

Takotsubo syndrome (TTS) is a stress-induced cardiomyopathy which is associated with important morbidity and in-hospital mortality. Microvascular dysfunction, inflammation and fibrosis may play crucial roles in TTS pathophysiology. Here we investigated the effect of methotrexate (MTX), an antiproliferative and immunosuppressive drug, on ventricular function in a rat model of Takotsubo syndrome. TTS induction was performed in Wistar male rats with 2 subcutaneous injections of isoproterenol (ISO, 85mg/Kg), with a 24-hour interval. Twenty-seven animals were allocated to 3 groups: Sham: controls treated with saline solution; ISO: TTS-induced with ISO, treated with saline solution; MTX: TTS-induced with ISO, treated with MTX (1mg/Kg i.p.). Animals were treated once a week, for 4 weeks. After treatments, animals underwent an echocardiographic exam. Histology and protein expression of markers of apoptosis, angiogenesis, and fibrosis were performed. Linear correlation was used to test echocardiographic variables versus protein expression. MTX treatment improved LV the systolic and diastolic functions in TTS rats, shown by higher ejection fraction (66% vs. 44%, p<0.05) and normalized E/A ratio (1.6±0.3 vs. 3.4±0.7, p<0.05). MTX reduced myocardial fibrosis in subendocardium and interstitium and decreased expression of pro-apoptotic markers (caspase 3 and BAX/Bcl-2 ratio). Additionally, MTX-treated rats exhibited reduced hypoxia, as indicated by lower HIF-2α expression, and increased angiogenesis, evidenced by elevated VEGF. In conclusion, MTX treatment enhances cardiac function and decreases adverse remodeling in this TTS rat model, conceivably through anti-fibrotic and pro-angiogenic mechanisms. These findings suggest that MTX may be a promising therapeutic option for TTS, warranting further investigation.