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

Comparison of the antihypertensive effects of folic acid and resveratrol in spontaneously hypertensive rats combined with hyperhomocysteinemia

Objectives

Studies have found that both folic acid and resveratrol have potential benefits in reducing complications of hypertension. The aim of this study was to compare the effects of resveratrol and folic acid on blood pressure in spontaneously hypertensive rats combined with hyperhomocystinemia, and to explore their potential mechanisms.

Methods

Twenty-four male specific pathogen free (SPF) SPF grade spontaneously hypertensive rats were randomly divided into four groups: the SHR group, the hypertension combined with hyperhomocystinemia group (SHR + HHcy), the folic acid intervention group (SHR + HHcy + FA), and the resveratrol intervention group (SHR + HHcy + Res). The rat model of hypertension combined with hyperhomocystinemia was constructed, and then folic acid or resveratrol were given by gavage. Rat tail artery blood pressure, serum homocysteine concentration, superoxide dismutase activity, malondialdehyde levels, and mRNA transcription and protein expression of endothelial nitric oxide synthase and angiotensin II were detected.

Result

Compared with the SHR group, the SHR + HHcy group significantly increased hyperhomocystinemia and malondialdehyde levels, and inhibited superoxide dismutase activity and endothelial nitric oxide synthase expression. Compared with the SHR + HHcy group, the SHR + HHcy + FA group significantly reduced hyperhomocystinemia and malondialdehyde levels, and significantly increased superoxide dismutase activity and endothelial nitric oxide synthase expression; the SHR + HHcy + Res group also inhibited malondialdehyde levels and promoted endothelial nitric oxide synthase expression, but did not reduce hyperhomocystinemia. When comparing between the SHR + HHcy + FA group and the SHR + HHcy + Res group, folic acid significantly decreased hyperhomocystinemia and increased superoxide dismutase activity, while resveratrol significantly decreased blood pressure and angiotensin II expression.

Conclusions

Both resveratrol and folic acid reduced the levels of oxidative stress and promoted the expression of endothelial nitric oxide synthase in SHRs combined with hyperhomocystinemia. Moreover, resveratrol exhibited superior antihypertensive efficacy compared to folic acid, potentially attributed to its ability to inhibit angiotensin II expression.

Plasma cystine/methionine ratio is associated with left ventricular diastolic function in patients with heart disease

Elevated circulating homocysteine (Hcy) is a well-known risk factor for cardiovascular diseases (CVDs), including coronary artery disease (CAD) and heart failure (HF). It remains unclear how Hcy and its derivatives relate to left ventricular (LV) diastolic function. The aim of the present study was to investigate the relationship between plasma Hcy-related metabolites and diastolic dysfunction (DD) in patients with heart disease (HD). A total of 62 HD patients with preserved LV ejection fraction (LVEF ≥ 50%) were enrolled. Plasma Hcy and its derivatives were measured by liquid chromatography‒mass spectrometry (LC-MS/MS). Spearman's correlation test and multiple linear regression models were used to analyze the associations between metabolite levels and LV diastolic function. The cystine/methionine (CySS/Met) ratio was positively correlated with LV diastolic function, which was defined from the ratio of mitral inflow E and mitral e' annular velocities (E/e') (Spearman's r = 0.43, p < 0.001). When the subjects were categorized into two groups by E/e', the high-E/e' group had a significantly higher CySS/Met ratio than the low-E/e' group (p = 0.002). Multiple linear regression models revealed that the CySS/Met ratio was independently associated with E/e' after adjustment for age, sex, body mass index (BMI), diabetes mellitus, hypertension, chronic kidney disease (CKD),　hemoglobin, and lipid peroxide (LPO) {standardized β (95% CI); 0.14 (0.04-0.23); p = 0.005}. Hcy, CySS, and Met did not show a significant association with E/e' in the same models. A high plasma CySS/Met ratio reflected DD in patients with HD.

Linagliptin and secoisolariciresinol diglucoside attenuate hyperlipidemia and cardiac hypertrophy induced by a high-methionine diet in rats via suppression of hyperhomocysteinemia-induced endoplasmic reticulum stress

Background: Cardiac hypertrophy (CH) is one of the contributing causes of morbidity and mortality. Hyperhomocysteinemia (HHcy) is one of the diseases which may predispose hyperlipidemia and CH. Linagliptin (Lina) and secoisolariciresinol diglucoside (SDG) are known to alleviate a variety of illnesses by reducing oxidative stress and inflammation. Aim: This study aimed to study the effect of HHcy on cardiac tissues, with a special focus on endoplasmic reticulum (ER) stress as a mainstay pathophysiological pathway. In addition, our study examined the protective effect of Lina, SDG, and their combination against HHcy-induced hyperlipidemia and CH in rats. Methods: Seventy-five male Sprague-Dawley rats were randomly divided into five groups, and for 60 days, the following regimen was administered: Group I: rats received distilled water; Group II: rats received methionine (MET) (2 g/kg/day, p.o.); groups III and IV: rats received Lina (3 mg/kg/day, p.o.) and SDG (20 mg/kg/day, p.o.), respectively, followed by MET (2 g/kg/day, p.o.); Group V: rats received Lina and SDG, followed by MET (2 g/kg/day, p.o.). Results: Pretreatment with Lina, SDG, and their combination showed a significant decrease in serum levels of HHcy and an improved lipid profile compared to the MET group. Moreover, both drugs improved cardiac injury, as evidenced by the substantial improvement in ECG parameters, morphological features of the cardiac muscle, and reduced serum levels of cardiac markers. Additionally, Lina and SDG significantly attenuated cardiac oxidative stress, inflammation, and apoptosis. Furthermore, Lina, SDG, and their combination remarkably downregulated the enhanced expression of endoplasmic reticulum (ER) stress markers, GRP78, PERK, ATF-4, CHOP, NF-κB, and SREBP1c compared to the MET-group. Conclusion: Lina and SDG showed cardioprotective effects against HHcy-induced heart hypertrophy and hyperlipidemia in rats.

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.

Folic Acid Preconditioning Alleviated Radiation-Induced Ovarian Dysfunction in Female Mice

Radiological therapy/examination is the primary source of artificial radiation exposure in humans. While its application has contributed to major advances in disease diagnosis and treatment, ionizing radiation exposure is associated with ovarian damage. The use of natural products, either alone or as an adjunct, has become increasingly common for reducing the side effects of radiological therapy during disease treatment. Herein, we explored the protective effect of folic acid (FA), a widely used B vitamin, against radiation-induced ovarian injury and its mechanism of action. Female mice with normal ovarian function were randomly divided into control, FA, radiation, and radiation + FA groups. The intervention strategy included daily intragastric administration of FA (5 mg/kg) for 3 weeks prior to radiation exposure. Mice in the radiation and radiation + FA groups received a single dose of 5 Gy X-ray irradiation. Changes in the estrous cycle were then recorded, and ovarian tissues were collected. Pathophysiological changes as well as reproductive and endocrine-related indexes were determined via H&E staining, immunohistochemistry, Western blot, and ELISA. The reproductive performance and emotional symptoms of animals were also monitored. Our results indicated that FA intervention effectively alleviated ovarian damage, leading to more regular estrous cycles, lesser impairment of follicular morphology and endocrine status, as well as greater germ cell preservation. Reduced levels of oxidative stress, inflammation, and enhanced DNA repair were associated these changes. FA pre-administration improved the reproductive performance, leading to higher pregnancy rates and greater litter sizes. Further, the anxiety levels of animals were significantly reduced. Our results indicate that FA pre-administration significantly alleviates radiation-induced ovarian damage in rodents, highlighting its potential as a protective strategy against radiation exposure in the female population.

5-Methyltetrahydrofolate Attenuates Oxidative Stress and Improves Kidney Function in Acute Kidney Injury through Activation of Nrf2 and Antioxidant Defense

Oxidative stress is a major mediator of adverse outcomes in acute kidney injury (AKI). Deficiency of micronutrients, such as folate, is common in AKI. Our previous study reported that AKI impaired kidney reabsorption of folate and decreased plasma folate level in rats. The present study investigated the effect of 5-methyltetrahydrofolate (5-MTHF), a biologically active form of folate/folic acid, on AKI-impaired kidney function and oxidative stress. Sprague-Dawley rats developed AKI after kidney ischemia (45 min) and reperfusion (24 h). Injection of 5-MTHF (3 µg/kg body weight) improved kidney function and attenuated oxidative stress with a restoration of glutathione and a reduction of lipid peroxidation in the kidney. Injection of 5-MTHF activated transcription factor Nrf2 and increased the expression of glutathione synthesizing enzymes, superoxide dismutase-1 and heme oxygenase-1 in the kidney. Simulated ischemia-reperfusion through hypoxia-reoxygenation increased oxidative stress in proximal tubular cells. Incubation of cells with 5-MTHF alleviated cell injury and increased antioxidant enzyme expression and intracellular glutathione levels. Inhibition of Nrf2 expression through siRNA transfection abolished the effect of 5-MTHF against oxidative stress. These results suggest that low-dose folic acid can improve kidney function through activation of Nrf2 and restoration of antioxidant defence. Micronutrient supplements may improve clinical outcomes in AKI.

Folic Acid Protects Melanocytes from Oxidative Stress via Activation of Nrf2 and Inhibition of HMGB1

Vitiligo is a cutaneous depigmentation disease due to loss of epidermal melanocytes. Accumulating evidence has indicated that oxidative stress plays a vital role in vitiligo via directly destructing melanocytes and triggering inflammatory response that ultimately undermines melanocytes. Folic acid (FA), an oxidized form of folate with high bioavailability, exhibits potent antioxidant properties and shows therapeutic potential in multiple oxidative stress-related diseases. However, whether FA safeguards melanocytes from oxidative damages remains unknown. In this study, we first found that FA relieved melanocytes from H₂O₂-induced abnormal growth and apoptosis. Furthermore, FA enhanced the activity of antioxidative enzymes and remarkably reduced intracellular ROS levels in melanocytes. Subsequently, FA effectively activated nuclear factor E2-related factor 2 (Nrf2) pathway, and Nrf2 knockdown blocked the protective effects of FA on H₂O₂-treated melanocytes. Additionally, FA inhibited the production of proinflammatory HMGB1 in melanocytes under oxidative stress. Taken together, our findings support the protective effects of FA on human melanocytes against oxidative injury via the activation of Nrf2 and the inhibition of HMGB1, thus indicating FA as a potential therapeutic agent for the treatment of vitiligo.

Effects of Inadequate Folate Intake on the Onset and Progression of Hypertensive Vascular Injury

We investigated the effects of inadequate folate intake on the onset and progression of hypertensive organ injury. In the present study, 5-wk-old male stroke-prone spontaneously hypertensive rats (SHRSP) were fed with a normal-folate (control; 160-170 μg of folate/100 g diet) or low-folate (8-10 μg of folate/100 g diet) diet until they reached 25 wk of age. After the animals reached 10 wk of age, the bodyweight of the rats in the low-folate group was lower than that of the rats in the control group. Regarding blood pressure, both groups had severe hypertension of ≥230 mmHg at 12 wk of age that was not significantly different between the groups. At 16 wk of age, the low-folate group had a low number of blood cell types. The folate levels in the serum, liver, and kidneys of these rats were significantly lower (p<0.01) and the serum homocysteine level in the low-folate group was significantly higher than in the controls. The low-folate group had a significantly lower testicular weight than the control group (p<0.05) and arterial hypertrophy, spermatogenesis arrest, and interstitial connective tissue hyperplasia were observed. However, there was no clear difference in lesions in other organs. These results indicated that under low folate status, SHRSP causes hematopoietic disorders and exacerbates hypertensive vascular injury at various degrees by organ type.