Resveratrol alleviates ethanol-induced hormonal and metabolic disturbances in the rat

Leaky Gut and the Ingredients That Help Treat It: A Review

The human body is in daily contact with potentially toxic and infectious substances in the gastrointestinal tract (GIT). The GIT has the most significant load of antigens. The GIT can protect the intestinal integrity by allowing the passage of beneficial agents and blocking the path of harmful substances. Under normal conditions, a healthy intestinal barrier prevents toxic elements from entering the blood stream. However, factors such as stress, an unhealthy diet, excessive alcohol, antibiotics, and drug consumption can compromise the composition of the intestinal microbiota and the homeostasis of the intestinal barrier function of the intestine, leading to increased intestinal permeability. Intestinal hyperpermeability can allow the entry of harmful agents through the junctions of the intestinal epithelium, which pass into the bloodstream and affect various organs and systems. Thus, leaky gut syndrome and intestinal barrier dysfunction are associated with intestinal diseases, such as inflammatory bowel disease and irritable bowel syndrome, as well as extra-intestinal diseases, including heart diseases, obesity, type 1 diabetes mellitus, and celiac disease. Given the relationship between intestinal permeability and numerous conditions, it is convenient to seek an excellent strategy to avoid or reduce the increase in intestinal permeability. The impact of dietary nutrients on barrier function can be crucial for designing new strategies for patients with the pathogenesis of leaky gut-related diseases associated with epithelial barrier dysfunctions. In this review article, the role of functional ingredients is suggested as mediators of leaky gut-related disorders.

Resveratrol attenuates excessive ethanol exposure-induced β-cell senescence in rats: A critical role for the NAD+/SIRT1-p38MAPK/p16 pathway

Resveratrol has been found to improve ethanol-induced diabetes. Although pancreatic β-cell senescence-induced β-cell mass loss plays a critical role in the progression of diabetes, the exact mechanism by which resveratrol improves ethanol-triggered β-cell senescence and its role in ethanol-induced diabetes remains unknown. Male Sprague-Dawley rats were fed either control or ethanol liquid diets containing 2.4 g/kg·bw ethanol with or without 100 mg/kg·bw resveratrol for 22 weeks. Resveratrol decreased the ethanol-induced augmentation in senescence-associated β-galactosidase (SA-β-gal)-positive area and attenuated reduction in β-cell mass, which were based on elevated levels of SIRT1 and proliferation marker Ki67 and reduced levels of senescence-associated markers (p-p38MAPK and p16^INK4a). Similarly, resveratrol rescued the reduction in NAD⁺/NADH ratio and SIRT1 and inhibited the upregulation of p-p38MAPK and p16^INK4a in ethanol-treated INS-1 cells. Furthermore, supplementation with NAD⁺ inducer nicotinamide mononucleotide, SIRT1 activator SRT1720 or p38MAPK inhibitor SB203580 effectively reversed ethanol-induced β-cell senescence, while supplementation with SIRT1 inhibitor Ex527 or NAD⁺ inhibitor FK866 abrogated resveratrol-mediated antisenescence effects in INS-1 cells. Together, our results indicate that resveratrol improves ethanol-triggered β-cell senescence and consequently recovers β-cell mass loss by inhibiting p38MAPK/p16 pathway through an NAD⁺/SIRT1 dependent pathway.

Resveratrol protects against ethanol-induced impairment of insulin secretion in INS-1 cells through SIRT1-UCP2 axis

SIRT1 has been proposed to enhance insulin secretion in β-cell through repressing the expression of uncoupling protein2 (UCP2), but whether ethanol-induced β-cell dysfunction is mediated by the disrupted SIRT1-UCP2 axis remains unknown. This study was conducted to explore the underlying mechanisms by which ethanol resulted in β-cell dysfunction and the potential protective effects of resveratrol in this process. INS-1 cells (rat pancreatic β-cell line) were cultured with ethanol in the presence or absence of resveratrol (2.5, 12.5 μmol/L). The results showed that ethanol exposure reduced glucose-stimulated insulin secretion, ATP production and SIRT1 expression but increased UCP2 expression, while supplementation with resveratrol restored the function of INS-1 cell by upregulating SIRT1 and inhibiting UCP2. Moreover, the critical role of SIRT1-UCP2 axis was further supported by the results that SIRT1 activator SRT1720 reversed ethanol-induced impairment of glucose-stimulated insulin secretion by decreasing UCP2, while SIRT1 inhibitor Ex527 abolished the beneficial effects of resveratrol. Meanwhile, NAD⁺ booster nicotinamide mononucleotide also counteracted the deleterious effects of ethanol by increasing SIRT1, suggesting the regulation of SIRT1-UCP2 axis may be associated with cellular NAD⁺/NADH ratio. In conclusion, our observations imply that ethanol induces impaired insulin secretion from INS-1 cell through disrupting SIRT1-UCP2 axis, while resveratrol may reverse this process by augmenting SIRT1 and inhibiting UCP2.

Effects of Resveratrol in Goto-Kakizaki Rat, a Model of Type 2 Diabetes

Resveratrol exhibits a pleiotropic, favorable action under various pathological conditions, including type 2 diabetes. However, its anti-diabetic effects in animal models and human trials have not been fully elucidated. The aim of the present study was to determine whether resveratrol is capable of inducing beneficial changes in the Goto-Kakizaki rat, a spontaneous model of diabetes, which in several aspects is similar to type 2 diabetes in humans. Goto-Kakizaki (GK) rats and control Sprague–Dawley (SD) rats were treated intragastrically with resveratrol (20 mg/kg b.w./day) for 10 weeks. Then, a glucose tolerance test was performed and levels of some adipokines in blood were measured. Moreover, lipid contents in skeletal muscle and liver tissues, along with the expression and phosphorylation of pivotal enzymes (AMP—activated protein kinase—AMPK, acetyl-CoA carboxylase—ACC, protein kinase B—Akt) in these tissues were determined. Histology of pancreatic islets was also compared. GK rats non-treated with resveratrol displayed a marked glucose intolerance and had increased lipid accumulation in the skeletal muscle. Moreover, upregulation of the expression and phosphorylation of AMPK, ACC and Akt was shown in the muscle tissue of GK rats. Those rats also had an abnormal structure of pancreatic islets compared with control animals. However, treatment with resveratrol improved glucose tolerance and prevented lipid accumulation in the skeletal muscle of GK rats. This effect was associated with a substantial normalization of expression and phosphorylation of ACC and Akt. In GK rats subjected to resveratrol therapy, the structure of pancreatic islets was also clearly improved. Moreover, blood adiponectin and leptin levels were partially normalized by resveratrol in GK rats. It was revealed that resveratrol ameliorates key symptoms of diabetes in GK rats. This compound improved glucose tolerance, which was largely linked to beneficial changes in skeletal muscle. Resveratrol also positively affected pancreatic islets. Our new findings show that resveratrol has therapeutic potential in GK rats.

Potential of resveratrol in mitigating metabolic disturbances induced by ethanol

Alcohol abuse is associated with numerous health problems, including metabolic disturbances and liver damage. Therefore, different compounds are continuously being tested to evaluate their potential effectiveness in reducing these harmful changes. Animal studies clearly show that resveratrol is capable of ameliorating some consequences of ethanol ingestion. Resveratrol is a naturally occurring diphenolic compound having pleiotropic, health-promoting properties. Its beneficial action have been also demonstrated in animal models with ethanol-induced metabolic disturbances and liver injury. In ethanol treated animals, resveratrol effectively reduced liver lipid accumulation. Moreover, this compound diminished necrosis of hepatocytes, and also reduced liver fibrosis. The hepatoprotective action of resveratrol is largely associated with its ant-oxidant and anti-inflammatory properties, and also covers changes in activities of some enzymes. It is known that this compound upregulates the adiponectin-SIRT1-AMPK signaling pathway in the liver. Resveratrol was also found to positively affect blood lipids in animals exposed to ethanol. Moreover, administration of resveratrol to animals with ethanol-induced hypoinsulinemia and insulin resistance was shown to alleviate these disturbances. These outcomes clearly indicate that resveratrol holds great potential to reduce some consequences of ethanol ingestion. However, human studies are required to fully assess its therapeutic value.

Resveratrol attenuates excessive ethanol exposure induced insulin resistance in rats via improving NAD+ /NADH ratio

SCOPE

Resveratrol has been shown to improve insulin resistance via activating the NAD⁺ -dependent deacetylase SIRT1, but the effects of resveratrol on ethanol-induced insulin resistance remain unclear. This study was designed to explore the potential mechanism by which resveratrol ameliorated ethanol-induced insulin resistance, focusing on its regulations on the ratio of NAD⁺ /NADH and SIRT1 expression.

METHODS AND RESULTS

Male Sprague-Dawley rats were fed either control or ethanol liquid diets containing 0.8, 1.6 and 2.4 g/kg·bw ethanol with or without 100 mg/kg·bw resveratrol for 22 weeks. Resveratrol improved ethanol (2.4 g/kg·bw) induced reductions in insulin sensitivity, SIRT1 expression (51%, P < 0.05), NAD⁺ /NADH ratio (196%, P < 0.01) as well as the expression and activity of ALDH2 while decreased the augmentations in the expression and activity of ADH and CYP2E1. In primary rat hepatocytes, ethanol exposure (25 mmol/L, 24 h) similarly decreased SIRT1 expression and NAD⁺ /NADH ratio (33%, P < 0.05; 32%, P < 0.01), and 0.1 μmol/L resveratrol treatment reversed these decreases and inhibited the expressions of ADH and CYP2E1.

CONCLUSION

Resveratrol exhibits benefits against ethanol-induced insulin resistance via improving the ratio of NAD⁺ /NADH to regulate SIRT1, which is associated with the modulation of ethanol metabolism enzymes.

Emerging roles of SIRT1 in fatty liver diseases

Fatty liver diseases, which are commonly associated with high-fat/calorie diet, heavy alcohol consumption and/or other metabolic disorder causes, lead to serious medical concerns worldwide in recent years. It has been demonstrated that metabolic homeostasis disruption is most likely to be responsible for this global epidemic. Sirtuins are a group of conserved nicotinamide adenine dinucleotide (NAD⁺) dependent histone and/or protein deacetylases belonging to the silent information regulator 2 (Sir2) family. Among seven mammalian sirtuins, sirtuin 1 (SIRT 1) is the most extensively studied one and is involved in both alcoholic and nonalcoholic fatty liver diseases. SIRT1 plays beneficial roles in regulating hepatic lipid metabolism, controlling hepatic oxidative stress and mediating hepatic inflammation through deacetylating some transcriptional regulators against the progression of fatty liver diseases. Here we summarize the latest advances of the biological roles of SIRT1 in regulating lipid metabolism, oxidative stress and inflammation in the liver, and discuss the potential of SIRT1 as a therapeutic target for treating alcoholic and nonalcoholic fatty liver diseases.