Folic acid alleviates lead acetate-mediated cardiotoxicity by down-regulating the expression levels of Nrf2, HO-1, GRP78, and CHOP proteins

The purpose of this study was to explore the interventional effects of folic acid on the heart damage caused by lead acetate exposure. Twenty-four 60-day-old male Sprague-Dawley (SD) rats were randomly divided into 4 groups with 6 rats in each group. The control group (C group) was normal rats; the lead exposure group (L group) rats drank 0.2% lead acetate solution freely for 14 days. The rats in the intervention group (T group) were given 0.2% lead acetate solution for 14 days, respectively, and 0.4 mg/kg BW folic acid solution was given to the rats by gavage on the 7th day of lead administration. The rats in the folic acid group (group E) were given 0.4 mg/kg BW folic acid solution by gavage. To weigh rat body weight and heart weight, calculate heart index, and observe the expression level of nuclear factor erythroid 2-related factor 2(Nrf2), heme oxygenase 1(HO-1), glucose-regulated protein 78/binding immunoglobulin protein (GRP78), and C/EBP-homologous protein (CHOP) by immunofluorescence method. The results showed that compared with group C, serum lead levels in group L and T were significantly increased (P < 0.05); superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-PX) levels in group L were significantly decreased (P < 0.05), and malondialdehyde (MDA) content was significantly higher increased (P < 0.05), and the GSH-PX content in group T were significantly increased in group L (P < 0.05), and the MDA content in group T was significantly lower than that in group L (P < 0.05). Compared with group C, the expression of Nrf2, HO-1, GRP78, and CHOP in group L increased significantly, and the difference was statistically significant (P < 0.05). Compared with the L group, the expression of Nrf2, HO-1, GRP78, and CHOP in the T group was reduced. Therefore, folic acid has a certain protective effect on the oxidative damage of lead-exposed rat heart tissue. Lead exposure will increase ROS, NO, MDA, and other oxidizing substances and reduce the level of GSH, SOD, CAT, GPx, and other antioxidant factors, which will lead to cardiac hypertrophy, cardiac index increase, oxidative stress, Nrf2, and HO-1. The expression of stress-related proteins such as GRP78 and CHOP also increased, leading to cardiomyocyte apoptosis. After a folic acid intervention, these changes can be significantly reversed.