Effects of an Intermittent Grape-Seed Proanthocyanidin (GSPE) Treatment on a Cafeteria Diet Obesogenic Challenge in Rats

Effects of grape seed proanthocyanidin extract on cholesterol metabolism and antioxidant status in finishing pigs

Grape seed proanthocyanidin extract (GSPE) is a natural polyphenolic compound, which plays an important role in anti-inflammatory and antioxidant. The present study aimed to investigate the effects of GSPE supplementation on the cholesterol metabolism and antioxidant status of finishing pigs. In longissimus dorse (LD) muscle, the data showed that GSPE significantly decreased the contents of total cholesterol (T-CHO) and triglyceride (TG), and decreased the mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR) and Fatty acid synthase (FAS), while increased the mRNA expression of carnitine palmitoyl transferase-1b (CPT1b), peroxisome proliferator-activated receptors (PPARα) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). GSPE also reduced the enzyme activities of HMG-CoAR and FAS, and meanwhile amplified the activity of CPT1b in LD muscle of finishing pigs. Furthermore, dietary GSPE supplementation increased the serum catalase (CAT) and total antioxidant capacity (T-AOC), serum and liver total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) levels, while reduced serum and liver malondialdehyde (MDA) level in finishing pigs. In the liver, Superoxide Dismutase 1 (SOD1), catalase (CAT), glutathione peroxidase 1 (GPX1), Nuclear Factor erythroid 2-Related Factor 2 (NRF2) mRNA levels were increased by GSPE. In conclusion, this study showed that GSPE might be an effective dietary supplement for improving cholesterol metabolism and antioxidant status in finishing pigs.

GSPE Pre-Treatment Exerts Long-Lasting Preventive Effects against Aging-Induced Changes in the Colonic Enterohormone Profile of Female Rats

The impact that healthy aging can have on society has raised great interest in understanding aging mechanisms. However, the effects this biological process may have on the gastrointestinal tract (GIT) have not yet been fully described. Results in relation to changes observed in the enteroendocrine system along the GIT are controversial. Grape seed proanthocyanidin extracts (GSPE) have been shown to protect against several pathologies associated with aging. Based on previous results, we hypothesized that a GSPE pre-treatment could prevent the aging processes that affect the enteroendocrine system. To test this hypothesis, we treated 21-month-old female rats with GSPE for 10 days. Eleven weeks after the treatment, we analyzed the effects of GSPE by comparing these aged animals with young animals. Aging induced a greater endocrine response to stimulation in the upper GIT segments (cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1)), a decrease in the mRNA abundance of GLP-1, peptide YY (PYY) and chromogranin A (ChgA) in the colon, and an increase in colonic butyrate. GSPE-treated rats were protected against a decrease in enterohormone expression in the colon. This effect is not directly related to the abundance of microbiome or short-chain fatty acids (SCFA) at this location. GSPE may therefore be effective in preventing a decrease in the colonic abundance of enterohormone expression induced by aging.

Intestinal Morphometric Changes Induced by a Western-Style Diet in Wistar Rats and GSPE Counter-Regulatory Effect

Western-style diet is an obesogenic diet for rodents and humans due to its content of saturated fat and refined sugars, mainly sucrose and, in consequence, sucrose-derived fructose. This type of diets relates with intestinal disturbances when consumed regularly. The aim of this work was to analyse the adaptive morphologic and functional changes at intestinal level derived from the unhealthy components of a Cafeteria diet in rats. The effect of grape seed proanthocyanidin extract (GSPE) in the prevention of diet-induced intestinal dysfunction was also analysed. Rats were fed a 17-week cafeteria diet (CAF) without or with oral-GSPE supplementation, either intermittent GSPE administration (SIT-CAF); last 10-day GSPE supplementation at doses of 100 mg/kg and 500 mg/kg day (CORR-100) and (CORR-500) or pre-supplementation with 500 mg/kg GSPE (PRE-CAF). GSPE-CAF supplemented groups showed similar results to CAF diet group regarding morphology and inflammatory score in the duodenum. As an adaptive response to diet, CAF increased intestinal absorptive surface (1.24-fold) all along the intestinal tract and specifically in the small intestine, duodenum, due to increase villus height and a higher villus/crypt ratio, in addition to increase in Goblet cell percentage and inflammatory index. Animals fed GSPE at the current doses and times had higher villus heights and absorptive surface similar to Cafeteria diet group. In the duodenum, villus height correlated with body weight at 17 week and negatively with MLCK gene expression. In the colon, villus height correlated with the percentage of goblet cells. In conclusion, the CAF diet produced adaptive modifications of the intestine by increasing the absorptive area of the small intestine, the percentage of goblet cells and the inflammatory index at the duodenal level. GSPE supplementation can partially reverse the intestinal morphological changes induced by the high fat/sucrose diet when administered intermittently.

Grape-Seed Proanthocyanidin Extract Reverts Obesity-Related Metabolic Derangements in Aged Female Rats

Obesity and ageing are current issues of global concern. Adaptive homeostasis is compromised in the elderly, who are more likely to suffer age-related health issues, such as obesity, metabolic syndrome, and cardiovascular disease. The current worldwide prevalence of obesity and higher life expectancy call for new strategies for treating metabolic disorders. Grape-seed proanthocyanidin extract (GSPE) is reported to be effective in ameliorating these pathologies, especially in young animal models. In this study, we aimed to test the effectiveness of GSPE in modulating obesity-related pathologies in aged rats fed an obesogenic diet. To do so, 21-month-old rats were fed a high-fat/high-sucrose diet (cafeteria diet) for 11 weeks. Two time points for GSPE administration (500 mg/kg body weight), i.e., a 10-day preventive GSPE treatment prior to cafeteria diet intervention and a simultaneous GSPE treatment with the cafeteria diet, were assayed. Body weight, metabolic parameters, liver steatosis, and systemic inflammation were analysed. GSPE administered simultaneously with the cafeteria diet was effective in reducing body weight, total adiposity, and liver steatosis. However, the preventive treatment was effective in reducing only mesenteric adiposity in these obese, aged rats. Our results confirm that the simultaneous administration of GSPE improves metabolic disruptions caused by the cafeteria diet also in aged rats.

Glucagon Shows Higher Sensitivity than Insulin to Grapeseed Proanthocyanidin Extract (GSPE) Treatment in Cafeteria-Fed Rats

The endocrine pancreas plays a key role in metabolism. Procyanidins (GSPE) targets β-cells and glucagon-like peptide-1 (GLP-1)-producing cells; however, there is no information on the effects of GSPE on glucagon. We performed GSPE preventive treatments administered to Wistar rats before or at the same time as they were fed a cafeteria diet during 12 or 17 weeks. We then measured the pancreatic function and GLP-1 production. We found that glucagonemia remains modified by GSPE pre-treatment several weeks after the treatment has finished. The animals showed a higher GLP-1 response to glucose stimulation, together with a trend towards a higher GLP-1 receptor expression in the pancreas. When the GSPE treatment was administered every second week, the endocrine pancreas behaved differently. We show here that glucagon is a more sensitive parameter than insulin to GSPE treatments, with a secretion that is highly linked to GLP-1 ileal functionality and dependent on the type of treatment.

A Ten-Day Grape Seed Procyanidin Treatment Prevents Certain Ageing Processes in Female Rats over the Long Term

Adaptive homeostasis declines with age and this leads to, among other things, the appearance of chronic age-related pathologies such as cancer, neurodegeneration, osteoporosis, sarcopenia, cardiovascular disease and diabetes. Grape seed-derived procyanidins (GSPE) have been shown to be effective against several of these pathologies, mainly in young animal models. Here we test their effectiveness in aged animals: 21-month-old female rats were treated with 500 mg GSPE/kg of body weight for ten days. Afterwards they were kept on a chow diet for eleven weeks. Food intake, body weight, metabolic plasma parameters and tumor incidence were measured. The GSPE administered to aged rats had an effect on food intake during the treatment and after eleven weeks continued to have an effect on visceral adiposity. It prevented pancreas dysfunction induced by ageing and maintained a higher glucagon/insulin ratio together with a lower decrease in ketonemia. It was very effective in preventing age-related tumor development. All in all, this study supports the positive effect of GSPE on preventing some age-related pathologies.

(-)-Epicatechin and the comorbidities of obesity

Obesity has major adverse consequences on human health contributing to the development of, among others, insulin resistance and type 2 diabetes, cardiovascular disease, non-alcoholic fatty liver disease, altered behavior and cognition, and cancer. Changes in dietary habits and lifestyle could contribute to mitigate the development and/or progression of these pathologies. This review will discuss current evidence on the beneficial actions of the flavan-3-ol (-)-epicatechin (EC) on obesity-associated comorbidities. These benefits can be in part explained through EC's capacity to mitigate several common events underlying the development of these pathologies, including: i) high circulating levels of glucose, lipids and endotoxins; ii) chronic systemic inflammation; iii) tissue endoplasmic reticulum and oxidative stress; iv) insulin resistance; v) mitochondria dysfunction and vi) dysbiosis. The currently known underlying mechanisms and cellular targets of EC's beneficial effects are discussed. While, there is limited evidence from human studies supplementing with pure EC, other studies involving cocoa supplementation in humans, pure EC in rodents and in vitro studies, support a potential beneficial action of EC on obesity-associated comorbidities. This evidence also stresses the need of further research in the field, which would contribute to the development of human dietary strategies to mitigate the adverse consequences of obesity.

Protective properties of grape-seed proanthocyanidins in human ex vivo acute colonic dysfunction induced by dextran sodium sulfate

PURPOSE

Anti-inflammatory and barrier-protective properties have been attributed to proanthocyanidins in the context of intestinal dysfunction, however little information is available about the impact of these phytochemicals on intestinal barrier integrity and immune response in the human. Here we assessed the putative protective properties of a grape-seed proanthocyanidin extract (GSPE) against dextran sodium sulfate (DSS)-induced acute dysfunction of the human colon in an Ussing chamber system.

METHODS

Human proximal and distal colon tissues from colectomized patients were submitted ex vivo for a 30-min preventive GSPE treatment (50 or 200 µg mL^-1) followed by 1-h incubation with DSS (12% w v^-1). Transepithelial electrical resistance (TEER), permeation of a fluorescently-labeled dextran (FD4) and proinflammatory cytokine release [tumor necrosis factor (TNF)-α and interleukin (IL)-1β] of colonic tissues were determined.

RESULTS

DSS reduced TEER (45-52%) in both the proximal and distal colon; however, significant increments in FD4 permeation (fourfold) and TNF-α release (61%) were observed only in the proximal colon. The preventive GSPE treatment decreased DSS-induced TEER loss (20-32%), FD4 permeation (66-73%) and TNF-α release (22-33%) of the proximal colon dose-dependently. The distal colon was not responsive to the preventive treatment but showed a reduction in IL-1β release below basal levels with the highest GSPE concentration.

CONCLUSIONS

Our results demonstrate potential preventive effects of GSPE on human colon dysfunction. Further studies are required to test whether administering GSPE could be a complementary therapeutic approach in colonic dysfunction associated with metabolic disorders and inflammatory bowel disease.

Effects of Grape Seed Proanthocyanidin Extract on Obesity

Obesity is a chronic metabolic disease resulting from excessive fat accumulation and/or abnormal distribution caused by multiple factors. As a major component of metabolic syndrome, obesity is closely related to many diseases such as type 2 diabetes mellitus, hyperlipidemia, hypertension, coronary heart disease, stroke and cancer. Hence, the problem of obesity cannot be ignored, and recent studies have shown that grape seed proanthocyanidin extract (GSPE) has an antiobesity effect. This paper systematically reviews the research progress and potential mechanism of GSPE emphasizing on obesity prevention and treatment.

Antihyperglycemic effect of a chicken feet hydrolysate via the incretin system: DPP-IV-inhibitory activity and GLP-1 release stimulation

Herein, the potential of hydrolysates of chicken feet proteins as natural dipeptidyl-peptidase IV (DPP-IV) inhibitors was investigated; moreover, three hydrolysates were selected due to their high DPP-IV inhibitory capacity (>80% inhibition), showing the IC50 values of around 300 μg estimated protein per mL; one of them (named p4H) was selected for the posterior analysis. In addition, its effect on glucose tolerance was investigated in two rat models (diet and age-induced) of glucose-intolerance and healthy animals; the amount of 300 mg estimated peptide per kg body weight improved the plasma glucose profile in both glucose-intolerance models. Moreover, it stimulated active GLP-1 release in the enteroendocrine STC-1 cells and rat ileum tissue. In conclusion, our results indicate that chicken feet proteins are a good source of bioactive peptides as DPP-IV inhibitors. Moreover, our results highlight the potential of the selected hydrolysate p4H in the management of type 2 diabetes due to its dual function of inhibition of the DPP-IV activity and induction of the GLP-1 release.

Health-Promoting Properties of Proanthocyanidins for Intestinal Dysfunction

The intestinal barrier is constantly exposed to potentially harmful environmental factors, including food components and bacterial endotoxins. When intestinal barrier function and immune homeostasis are compromised (intestinal dysfunction), inflammatory conditions may develop and impact overall health. Evidence from experimental animal and cell culture studies suggests that exposure of intestinal mucosa to proanthocyanidin (PAC)-rich plant products, such as grape seeds, may contribute to maintaining the barrier function and to ameliorating the pathological inflammation present in diet-induced obesity and inflammatory bowel disease. In this review, we aim to update the current knowledge on the bioactivity of PACs in experimental models of intestinal dysfunction and in humans, and to provide insights into the underlying biochemical and molecular mechanisms.

Long-Lasting Effects of GSPE on Ileal GLP-1R Gene Expression Are Associated with a Hypomethylation of the GLP-1R Promoter in Female Wistar Rats

Flavonoids have been shown to modulate GLP-1 in obesity. GLP-1 induces some of its effects through the intestinal GLP-1 receptor (GLP-1R), though no data exist on how flavonoids affect this receptor. Here, we examine how a dose of grape seed proanthocyanidin extract (GSPE) with anti-obesity activity affects intestinal GLP-1R and analyze whether epigenetics play a role in the long-lasting effects of GSPE. We found that 10-day GSPE administration prior to the cafeteria diet upregulated GLP-1R mRNA in the ileum 17 weeks after the GSPE treatment. This was associated with a hypomethylation of the GLP-1R promoter near the region where the SP1 transcription factor binds. In the colon, the cafeteria diet upregulated GLP-1R without showing any GSPE effect. In conclusion, we have identified long-lasting GSPE effects on GLP-1R gene expression in the ileum that are partly mediated by hypomethylation at the gene promoter and may affect the SP1 binding factor.

Grape Seeds Proanthocyanidins: An Overview of In Vivo Bioactivity in Animal Models

Over the last decade, proanthocyanidins (PACs) are attracting attention not only from the food industry but also from public health organizations due to their health benefits. It is well-known that grapes are a good source of PACs and for that reason, the industry is also focused on grape by-products identification and bioactivity evaluation. Grape seeds extract (GSPE) is a rich source of PACs, mainly composed of monomeric catechin and epicatechin, gallic acid and polymeric and oligomeric proanthocyanidins. Thus, this review encompasses the state-of-art structure and the most recent evidence about the impact of GSPE on chronic diseases, with a focus on oxidative stress, inflammation and metabolic syndrome (MeS)-related disorders such as obesity, diabetes and cardiovascular risk disease in vivo to offer new perspectives in the field that allow further research. Despite the controversial results, is undeniable that PACs from grape seeds are highly antioxidants, thus, the capacity of GSPE to improve oxidative stress might mediate the inflammation process and the progress of MeS-related pathologies. However, further well-design animal studies with standardized dosages and GSPE composition are necessary to shed light into the cause-effect relationship in a more accurate way to later allow a deeper study of the effect of GSPE in humans.

Proanthocyanidins Limit Adipose Accrual Induced by a Cafeteria Diet, Several Weeks after the End of the Treatment

A dose of proanthocyanidins with satiating properties proved to be able to limit body weight increase several weeks after administration under exposure to a cafeteria diet. Here we describe some of the molecular targets and the duration of the effects. We treated rats with 500 mg grape seed proanthocyanidin extract (GSPE)/kg BW for ten days. Seven or seventeen weeks after the last GSPE dose, while animals were on a cafeteria diet, we used reverse transcriptase-polymerase chain reaction (RT-PCR) to measure the mRNA of the key energy metabolism enzymes from the liver, adipose depots and muscle. We found that a reduction in the expression of adipose Lpl might explain the lower amount of adipose tissue in rats seven weeks after the last GSPE dose. The liver showed increased expression of Cpt1a and Hmgs2 together with a reduction in Fasn and Dgat2. In addition, muscle showed a higher fatty oxidation (Oxct1 and Cpt1b mRNA). However, after seventeen weeks, there was a completely different gene expression pattern. At the conclusion of the study, seven weeks after the last GSPE administration there was a limitation in adipose accrual that might be mediated by an inhibition of the gene expression of the adipose tissue Lpl. Concomitantly there was an increase in fatty acid oxidation in liver and muscle.

Grape-Seed Proanthocyanidins are Able to Reverse Intestinal Dysfunction and Metabolic Endotoxemia Induced by a Cafeteria Diet in Wistar Rats

We evaluated the effectiveness of pharmacological doses of grape-seed proanthocyanidin extract (GSPE) in reversing intestinal barrier alterations and local inflammation in female Wistar rats fed a long-term obesogenic diet. Animals were fed a 17-week cafeteria diet (CAF diet), supplemented with daily GSPE doses (100 or 500 mg kg⁻¹ body weight) during the final two weeks. CAF diet enhanced the intestinal permeation of an orally administered marker (ovalbumin, OVA) and increased the plasma levels of tumor necrosis factor-α (TNF-α) and lipopolysaccharides (LPS) in 2–3-fold. Ex vivo Ussing chamber assays showed a 55–70% reduction in transepithelial electrical resistance (TEER) and increased the TNF-α secretions in both small and large intestinal sections with a 25-fold increment in the ileum. Ileal tissues also presented a 4-fold increase of myeloperoxidase (MPO) activity. Both GSPE-treatments were able to restitute TEER values in the ileum and colon and to reduce plasma LPS to basal levels without a dose-dependent effect. However, effects on the OVA permeation and TNF-α secretion were dose and section-specific. GSPE also reduced ileal MPO activity and upregulated claudin 1 gene expression. This study provides evidence of the efficacy of GSPE-supplementation ameliorating diet-induced intestinal dysfunction and metabolic endotoxemia when administered at the end of a long-term obesogenic diet.

Grape Seed Proanthocyanidins Target the Enteroendocrine System in Cafeteria-Diet-Fed Rats

SCOPE

The effects on the enteroendocrine system of three different grape seed proanthocyanidin extract (GSPE) treatments are analyzed in rats on a cafeteria diet for 17 weeks.

METHODS AND RESULTS

GSPE is administered in a corrective manner (15 last days of the cafeteria diet) at two doses, 100 and 500 mg GSPE per kg bw. A third, longer treatment in which GSPE (500 mg kg^-1 bw) is administered daily every other week during the 17 weeks of the cafeteria diet is also tested. Most GSPE treatments lead to ghrelin accumulation in the stomach, limited CCK secretion in the duodenum, and increased GLP-1 and PYY mRNA in colon. GSPE also increases cecal hypertrophy and reduces butyrate content. When the treatment is administered daily every other week during 17 weeks, there is also an increase in colon size. These effects are accompanied by a reduced food intake at the end of the experiment when GSPE is administered at 500 mg GSPE kg^-1 during the last 15 days, but not on the other treatments, despite an observed reduction in body weight in the longer treatment.

CONCLUSION

GSPE modulates the enteroendocrine system in models in which it also reduces food intake or body weight.

Achacha (Garcinia humilis) Rind Improves Cardiovascular Function in Rats with Diet-Induced Metabolic Syndrome

Garcinia humilis is a fruit known as achachairú. It is native to South American countries such as Bolivia, Peru, and Brazil, but it is also cultivated as achacha in northern Australia. The aim of this study was to determine the phytochemicals in achacha rind and pulp and to investigate these components as potential treatments for the symptoms of metabolic syndrome. Both rind and pulp contain procyanidins and citric acid rather than hydroxycitric acid. Male Wistar rats (8⁻9 weeks old) were fed with either high-carbohydrate, high-fat, or corn starch diets for 16 weeks. Intervention groups were fed with either diet supplemented with 1.5% G. humilis rind powder or 2.0% G. humilis pulp for the last 8 weeks of the protocol. Rats fed a high-carbohydrate, high-fat diet exhibited hypertension, dyslipidemia, central obesity, impaired glucose tolerance, and non-alcoholic fatty liver disease. G. humilis rind decreased systolic blood pressure, diastolic stiffness, left ventricular inflammatory cell infiltration, and collagen deposition in high-carbohydrate, high-fat diet-fed rats. However, there was no change in glucose tolerance, body weight, or body composition. Therefore, G. humilis rind, usually a food by-product, but not the edible pulp, showed potential cardioprotection with minimal metabolic changes in a rat model of diet-induced metabolic syndrome.

The co-administration of proanthocyanidins and an obesogenic diet prevents the increase in intestinal permeability and metabolic endotoxemia derived to the diet

The consumption of Westernized diets leads to hyperphagia and obesity, as well as intestinal alterations. In the present study, we evaluated the effect of the administration of a grape seed proanthocyanidin extract (GSPE) at different time points on the modulation of intestinal barrier function (intestinal permeability and metabolic endotoxemia), in rats with high-fat/high-carbohydrate diet-induced obesity. Animals were fed a cafeteria diet (CAF) supplemented with a preventive (PRE-CAF) or simultaneously intermittent (SIT-CAF) GSPE treatment (500 mg/kg bw). Changes in the plasma levels of an orally administered marker of intestinal permeability (ovalbumin, OVA), lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) were analyzed after animals were fed the obesogenic diet for 8, 12 and 17 weeks. In addition, ex vivo variations in transepithelial electrical resistance (TEER), the expression of tight junction (TJ) genes and the activity of myeloperoxidase (MPO) in the small and large intestines were monitored at the end of the experiment. The CAF diet increased OVA, LPS, MPO and TNF-α levels, accompanied by decreased TEER values in the small and large intestines. Interestingly, both GSPE treatments prevented these detrimental effects of the CAF diet, being the SIT-CAF group the most effective after 17 weeks of diet intervention. For the first time, this study provides evidence of the ameliorative effect of a proanthocyanidin extract, administered before or together with an obesogenic diet, on barrier dysfunction, as measured by intestinal permeability and metabolic endotoxemia.