Low Dose of Folic Acid Can Ameliorate Hyperhomocysteinemia-Induced Cardiac Fibrosis and Diastolic Dysfunction in Spontaneously Hypertensive Rats

To evaluate whether lowering plasma homocysteine (Hcy) levels at different doses of folic acid (FA) could reduce cardiac fibrosis and diastolic dysfunction in spontaneously hypertensive rats (SHRs) with hyperhomocys-teinemia (Hhcy) and investigate the possible mechanism of action. We randomly divided 32 male SHRs into control, Hhcy, Hhcy + low-dose FA (LFA), and Hhcy + high-dose FA (HFA) groups. Echocardiography and Masson staining of cardiac tissue were used to assess diastolic function and cardiac fibrosis. Blood pressure (BP) and Hcy levels were measured during the experiment. We also measured the indicators of oxidative stress (OS) and examined the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) genes and proteins using real-time polymerase chain reaction (PCR), immunohistochemistry, and western blotting to explore the possible mechanism of action. FA treatment reversed SHR cardiomyocyte interstitial and perivascular collagen deposition and diastolic dysfunction exacerbated by Hhcy. These effects were associated with promoting the translocation of Nrf2 from the cytoplasm to the nucleus, activating HO-1 expression and inhibiting OS. However, HFA did not show any additional benefit from LFA in reducing cardiac injury. Even at a low dose, FA can ameliorate Hhcy-induced cardiac fibrosis and diastolic dysfunction in SHRs by activating Nrf2/HO-1 pathway and inhibiting OS, independent of BP, providing evidence for the efficacy of LFA in the treatment of hypertension associated with Hhcy.