Gallic acid improves glucose tolerance and triglyceride concentration in diet-induced obesity mice

The potential harmful effects of cancer treatments on reproductive function have now been clearly recognized. Exposure to chemotherapy is considered a risk factor for premature ovarian failure and causes infertility. This study investigated the prophylactic effects of gallic acid (GA) against cyclophosphamide (CP)-induced ovarian damage in rats. Thirty-two adult female Sprague Dawley rats were randomly assigned into four groups (control, CP, GA, and CP + GA). No procedure was applied to the control group. The CP group received 150mg/kg CP via the intraperitoneal (i.p.) route on day 7 of the experiment. The GA group received 20mg/kg GA daily for seven days from day 1 of the experiment via oral gavage. The CP + GA received 20mg/kg GA daily for seven days from day 1 of the experiment via oral gavage and 150mg/kg i.p. CA on day 7 of the experiment. All rats were sacrificed on day 8. Sections taken from the ovaries were stained using hematoxylin-eosin, Masson's trichrome, Periodic Acid-Schiff, and the TUNEL method. Histopathological examination of ovarian tissues and follicle counting were performed. Glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), tissue anti-müllerian hormone (AMH), and serum AMH levels were examined during biochemical investigation. Follicular cell degeneration increased significantly in the CP group compared to the control and GA groups (p < 0.001 for both). Follicular cell degeneration in the CP + GA group was significantly lower than in the CP group (p = 0.003), but higher than in the control and GA groups (p = 0.005, p = 0.015 and p = 0.029, respectively). The GA and control groups exhibited similar morphologies. The apoptotic index was higher in the CP group than in the control and CP + GA groups (p = 0.032 and p = 0.032, respectively). Primordial follıcle cell numbers decreased significantly in the CP group compared to the control and CP + GA groups (p = 0.015 and p = 0.029, respectively). Unilaminar primary follicle cell numbers were lower and atretic cell numbers were higher in the CP group than in the control and GA groups (p < 0.001 and p = 0.008, respectively). The numbers of unilaminar primary follicles were lower in the CP + GA group than in the control group (p = 0.009), while atretic follicle numbers were higher than in the control and GA groups (p < 0.001 for both). Atretic follicle numbers were also higher in the CP + GA group than in the control and GA (p = 0.009 and p = 0.008, respectively). MDA levels were higher in the CP than in the control and GA groups (p = 0,003 and p = 0.001, respectively). MDA levels in the CP + GA decreased compared to the CP group (p = 0.002). SOD activity decreased in the CP group compared to the control, CP + GA, and GA groups (p = 0.003, p = 0.006 and p = 0.038, respectively). Tissue CAT activity was lower in the CP group than in the control group (p = 0.038). Tissue CAT activity increased in the CP + GA group compared to the control and CP groups (p < 0.001 for both). Tissue CAT activity also increased in the GA group compared to the control and CP groups (p = 0.001 for both). Tissue AMH was lower in the CP group compared to the control group (p = 0.015), while serum AMH was higher in the GA group than in the other groups (p = 0.003, p = 0.003, and p = 0.022, respectively). No intergroup difference was observed in GPX levels. GA can be effective in preventing follicle cell damage caused by CP in the ovary.

Macrophage lipid metabolism and inflammatory responses are both regulated by the nuclear receptors PPAR and LXR. Emerging links between inflammation and metabolic disease progression suggest that PPAR and LXR signaling may alter macrophage function and thereby impact systemic metabolism. In this study, the function of macrophage PPAR and LXR in Th1-biased C57BL/6 mice was tested using a bone marrow transplantation approach with PPARγ−/−, PPARδ−/−, PPARγδ−/−, and LXRαβ−/− cells. Despite their inhibitory effects on inflammatory gene expression, loss of PPARs or LXRs in macrophages did not exert major effects on obesity or glucose tolerance induced by a high-fat diet. Treatment with rosiglitazone effectively improved glucose tolerance in mice lacking macrophage PPARγ, suggesting that cell types other than macrophages are the primary mediators of the anti-diabetic effects of PPARγ agonists in our model system. C57BL/6 macrophages lacking PPARs or LXRs exhibited normal expression of most alternative activation gene markers, indicating that macrophage alternative activation is not absolutely dependent on these receptors in the C57BL/6 background under the conditions used here. These studies suggest that genetic background may be an important modifier of nuclear receptor effects in macrophages. Our results do not exclude a contribution of macrophage PPAR and LXR expression to systemic metabolism in certain contexts, but these factors do not appear to be dominant contributors to glucose tolerance in a high-fat-fed Th1-biased bone marrow transplant model.

Maresin 1 (MaR1) is a DHA-derived pro-resolving lipid mediator. The present study aimed to characterize the ability of MaR1 to prevent the alterations induced by TNF-α on insulin actions in glucose uptake and Akt phosphorylation in cultured human adipocytes from overweight/obese subjects, as well as to investigate the effects of MaR1 acute and chronic administration on Akt phosphorylation in absence/presence of insulin in white adipose tissue (WAT) and skeletal muscle from lean and diet-induced obese (DIO) mice. MaR1 (0.1nM) prevented the inhibitory effect of TNF-α on insulin-stimulated 2-Deoxy-D-glucose uptake and Akt phosphorylation in human adipocytes. Acute treatment with MaR1 (50μg/kg, 3h, i.p.) induced Akt phosphorylation in WAT and skeletal muscle of lean mice. However, MaR1 did not further increase the stimulatory effect of insulin on Akt activation. Interestingly, intragastric chronic treatment with MaR1 (50μg/kg, 10days) in DIO mice reduced the hyperglycemia induced by the high fat diet (HFD) and improved systemic insulin sensitivity. In parallel, MaR1 partially restored the impaired insulin response in skeletal muscle of DIO mice and reversed HFD-induced lower Akt phosphorylation in WAT in non-insulin-stimulated DIO mice while did not restore the defective Akt activation in response to acute insulin observed in DIO mice. Our results suggest that MaR1 attenuates the impaired insulin signaling and glucose uptake induced by proinflammatory cytokines. Moreover, the current data support that MaR1 treatment could be useful to reduce the hyperglycemia and the insulin resistance associated to obesity, at least in part by improving Akt signaling.

Adipose tissue inflammation induced by macrophage infiltration through the MCP-1/CCR2 pathway is considered to play a pivotal role in the development of visceral obesity and insulin resistance. In the present study, therefore, we examined whether pharmacological inhibition of CCR2 is effective against the development of diet-induced metabolic disorders. C57BL/6 mice were fed a high fat and sucrose diet with or without propagermanium (CCR2 inhibitor, 5 or 50 mg/kg BW/day) for 12 weeks from 6 weeks of age. Then we analyzed lipid and glucose metabolism and tissue inflammation in the liver and adipose tissues along with serum markers in those mice. Propagermanium treatment slightly decreased body weight gain and visceral fat accumulation in diet-induced obese (DIO) mice. Further, propagermanium suppressed macrophage accumulation and shifted adipose tissue macrophage polarization from the pro-inflammatory (M1) state to anti-inflammatory (M2) state in DIO mice. Expressions of TNF-alpha and MCP-1 mRNA in adipose tissue were reduced by propagermanium treatment, indicating that propagermanim suppressed inflammation in adipose tissue. Propagermanium treatment also ameliorated glucose tolerance, insulin sensitivity, and decreased hepatic triglyceride in DIO mice. Thus, propagermanium improved diet-induced obesity and related metabolic disorders, such as insulin resistance and hepatic steatosis by suppressing inflammation in adipose tissue. Our data indicate that inhibition of CCR2 could improve diet-induced metabolic disorders, and that propagermanium may be a beneficial drug for the treatment of metabolic syndrome.

Current anti-obesity monotherapies have proven only marginally effective and are often accompanied by adverse side effects. The cannabinoid 1 (CB1) receptor antagonist rimonabant, while effective at producing weight loss, has been discontinued from clinical use owing to increased incidence of depression. This study investigates the interaction between the cannabinoid and melanin-concentrating hormone (MCH) systems in food intake, body weight control, and mood. Lean male C57BL/6 mice were injected i.p. with rimonabant (0.0, 0.03, 0.3 and 3.0 mg kg(-1)) or the MCH1-R antagonist SNAP-94847 (0.0, 1.0, 5.0 and 10.0 mg kg(-1)) to establish dose response parameters for each drug. Diet-induced obese (DIO) mice were given either vehicle, sub-threshold dose of rimonabant and SNAP-94847 alone or in combination. Impact on behavioral outcomes, food intake, body weight, plasma metabolites and expression of key metabolic proteins in the brown adipose tissue (BAT) and white adipose tissue (WAT) were measured. The high doses of rimonabant and SNAP-94847 produced a reduction in food intake after 2 and 24 h. Combining sub-threshold doses of rimonabant and SNAP-94847 produced a significantly greater loss of body weight in DIO mice compared with vehicle and monotherapies. In addition, combining sub effective doses of these drugs led to a shift in markers of thermogenesis in BAT and lipid metabolism in WAT consistent with increased energy expenditure and lipolysis. Furthermore, co-administration of rimonabant and SNAP-94847 produced a transient reduction in food intake, and significantly reduced fat mass and adipocyte size. Importantly, SNAP-94847 significantly attenuated the ability of rimonabant to reduced immobility time in the forced swim test. These results provide proof of principle that combination of rimonabant and a MCH1 receptor antagonist is highly effective in reducing body weight below that achieved by rimonabant and SNAP-94847 monotherapies. In addition, the combination therapy normalizes the rimonabant-induced behavioral changes seen in the forced swim test.

Fecal microbiota and metabolomics revealed the effect of long-term consumption of gallic acid on canine lipid metabolism and gut health.

Obesity is associated with chronic low-grade inflammation, and metabolic regulators linking obesity to inflammation have therefore received much attention. Secreted C1q/TNF-related proteins (CTRPs) are one such group of regulators that regulate glucose and fat metabolism in peripheral tissues and modulate inflammation in adipose tissue. We have previously shown that expression of CTRP6 is up-regulated in leptin-deficient mice and, conversely, down-regulated by the anti-diabetic drug rosiglitazone. Here, we provide evidence for a novel role of CTRP6 in modulating both inflammation and insulin sensitivity. We found that in obese and diabetic humans and mouse models, CTRP6 expression was markedly up-regulated in adipose tissue and that stromal vascular cells, such as macrophages, are a major CTRP6 source. Overexpressing mouse or human CTRP6 impaired glucose disposal in peripheral tissues in response to glucose and insulin challenge in wild-type mice. Conversely, Ctrp6 gene deletion improved insulin action and increased metabolic rate and energy expenditure in diet-induced obese mice. Mechanistically, CTRP6 regulates local inflammation and glucose metabolism by targeting macrophages and adipocytes, respectively. In cultured macrophages, recombinant CTRP6 dose-dependently up-regulated the expression and production of TNF-α. Conversely, CTRP6 deficiency reduced circulating inflammatory cytokines and pro-inflammatory macrophages in adipose tissue. CTRP6-overexpressing mice or CTRP6-treated adipocytes had reduced insulin-stimulated Akt phosphorylation and glucose uptake. In contrast, loss of CTRP6 enhanced insulin-stimulated Akt activation in adipose tissue. Together, these results establish CTRP6 as a novel metabolic/immune regulator linking obesity to adipose tissue inflammation and insulin resistance.

Osteocytes have been shown to play critical roles in the regulation of a wide range of metabolic processes. However, their role in the regulation of glucose metabolism remains to be determined despite accumulating evidence of the integral role of osteoblasts in this regulation, in which osteoblast-derived lipocalin-2 (LCN2) has been shown to regulate glucose metabolism. Additionally, Lcn2 expression is induced by AKT activation. These results led us to hypothesize that AKT activation in osteocytes regulates glucose metabolism by modulating Lcn2 expression. Therefore, in this study, the Pten gene was deleted in osteocytes to activate AKT signaling by crossing Pten-flox mice with Dmp1-Cre mice (PtenOcy-/- mice). Deleting Pten expression in osteocytes resulted in osteocytic AKT activation, which was associated with decreased adipose tissue mass and enhanced insulin sensitivity. Expression of Pparg2 and lipogenesis-associated genes were decreased in the adipose tissue of PtenOcy-/- mice. Mechanistically, the lack of Phosphatase and Tensin Homolog Deleted from Chromosome 10 (PTEN) in osteocytes increased Lcn2 expression in the femur, which was associated with increased serum and urine LCN2 levels. The urinary LCN2 level was negatively associated with white adipose tissue mass. Additionally, the treatment of primary white adipocytes with recombinant LCN2 reduced the expression of Pparg2 and lipogenesis-related genes. These results suggest that the absence of PTEN in osteocytes increases the expression of Lcn2, which acts in the adipose tissue to suppress lipogenesis, resulting in enhanced insulin sensitivity in these mice. This study provides novel insights into the critical role of AKT activation in osteocytes in regulating glucose metabolism by increasing Lcn2 expression.

Gallic acid regulates adipocyte hypertrophy and suppresses inflammatory gene expression induced by the paracrine interaction between adipocytes and macrophages in vitro and in vivo

Flavonoid-rich Chardonnay grape seed flour supplementation ameliorates diet-induced visceral adiposity, insulin resistance, and glucose intolerance via altered adipose tissue gene expression

Objective To investigate the protective effect of n-3 polyunsaturated fatty acids(n-3 PUFAs) on non-alcoholic fatty liver disease caused by high fat diet-induced obese(DIO) mice. Methods Three to four-week-old male C57BL/6J mice were randomly divided into 3 groups with 15 cases in each group.These mice were fed with 2 types of high-fat diet(34.9% fat providing 60% of total energy) with n-6 PUFAs(sunflower oil) and n-3 PUFAs(fish oil) respectively to induce obesity for 20 weeks, with a normal-fat diet(4.3% fat providing 10% of total energy) as lean control group.After being fasted for 12 hours, blood samples were drawn, and livers were collected.Plasma markers, insulin, glucose, lipids, alanine aminotransferase(ALT), aspartate aminotransferase(AST), and the lipids of liver were measured by biochemical methods.The mRNA expressions of hepatic genes associated with lipid metabolism, oxidative stress, inflammation and fibrosis were examined by real-time PCR. Results As compared to the control lean mice, the plasma glucose, insulin, total cholesterol(TCH), low density lipoprotein cholesterol(LDL-C) and ALT in the DIO mice with the n-6 PUFA diet were all increased(P<0.05), and also the mRNA expressions of the hepatic genes reflecting hepatic damage, oxidative stress, inflammation and fibrosis were higher(P<0.05). As compared to the DIO mice with the n-6 PUFA diet, the above markers in the plasma and the related genes' expressions in the liver were reduced in DIO mice with the n-3 PUFA diet(P<0.05). Conclusions Dietary fish oil n-3 PUFAs may play some positive roles by antagonizing the abnormal expression of the genes associated with hepatic lipid metabolism, oxidative stress, inflammation and fibrosis in the DIO mice. Key words: N-3 polyunsaturated fatty acids; Non-alcoholic fatty liver disease; Obesity; Mouse

Obesity increases the risk of several solid tumors. Obesity-induced impairments in immunity may contribute to this relationship. We have previously shown that numerous innate and adaptive immune responses, including NK cell cytotoxicity, antigen-specific CD4+ T cell proliferation, and CD8+ T cell cytotoxicity, are impaired in diet-induced obese (DIO) mice. PURPOSE: The current study was designed to determine if the obesity-induced decrements in immunity were reversible with weight loss achieved via the most common obesity interventions used in humans: exercise (EX), energy restriction (ER), or a combination of EX+ER. METHODS: Female C57BL/6 mice consumed a 60 kcal% fat diet, with 20 kcal% protein & carbohydrate, ad libitum for 15 weeks to induce obesity. After achieving a mean (± SD) body weight of 48.3 ± 1.9 grams, DIO mice were randomized to one of the following intervention groups (n=7-9/group): 1) DIO controls, which continued on 60 kcal% fat diet ad libitum; 2) DIO mice with access to running wheels (DIO+EX); 3) DIO mice placed on an energy-restricted diet consisting of a 30% reduction in kcal from fat (DIO+ER); or 4) DIO mice placed on an ER diet with access to running wheels (DIO+ER+EX). Mice were on one of the four interventions for 8 weeks prior to receiving a primary vaccination followed by 2 booster vaccinations 2 weeks apart. Animals were sacrificed 3 weeks following the last boost, and spleens were collected for assessment of immune function. RESULTS: Only mice on the ER diets (DIO+ER and DIO+ER+EX mice) weighed significantly less than the DIO control mice (P<0.05). Despite the lack of significant change in body weight with the exercise intervention alone, EX (either alone or in combination with ER) significantly (P <0.05) enhanced NK cell cytotoxicity, antigen-specific CD4+ T cell proliferation, and CD8+ T cell cytotoxicity in DIO mice, whereas ER alone did not. These findings demonstrate that obesity-induced immune impairments in NK cell and T cell function can be reversed by EX or a combination of ER plus EX, but not ER alone. CONCLUSION: These results suggest that in obese mice exercise enhances immune function independently of changes in body weight, and that in humans exercise may be an important intervention to couple with energy restriction to reduce body weight and enhance immune responsiveness in obese patients.

Obesity is associated with a variety of disorders and is a significant health problem in developed countries. One factor controlling the level of adiposity is the differentiation of cells into adipocytes. Adipocyte differentiation requires expression of peroxisome proliferator-activated receptor γ (PPARγ), which is activated by ligands to regulate expression of genes involved in adipocyte differentiation. Although 15-deoxy-Δ(12,14)-prostaglandin (PG) J(2) (15d-PGJ(2)) has long been known to be a potent activator of PPARγ, the importance of its synthesis in adipose tissue in vivo is not clear. The current study utilized mice deficient in cyclooxygenase-2 (COX-2) to examine the role of COX-2-derived PGs as in vivo modulators of adiposity. As compared with strain- and age-matched wild-type controls, the genetic deficiency of COX-2 resulted in a significant reduction in total body weight and percent body fat. Although there were no significant differences in food consumption between groups, COX-2-deficient mice showed increased metabolic activity. Epididymal adipose tissue from wild-type mice produced a significantly greater level of 15d-PGJ(2), as compared with adipose tissue isolated from mice deficient in COX-2. Furthermore, production of the precursor required for 15d-PGJ(2) formation, PGD(2), was also significantly reduced in COX-2-deficient adipose tissue. The expression of markers for differentiated adipocytes was significantly reduced in adipose tissue from COX-2-deficient mice, whereas preadipocyte marker expression was increased. Macrophage-dependent inflammation was also significantly reduced in adipose tissue of COX-2-deficient mice. These findings suggest that reduced adiposity in COX-2-deficient mice results from attenuated PPARγ ligand production and adipocyte differentiation.

Aim: To investigate the hepatoprotective, anti-inflammatory and antioxidant effects of gallic acid (GA) against obstructive cholestasis (OC) -induced liver damage in rats.Methods: Thirty female Sprague-Dawley rats were divided into three groups.Group 1 (n=10) was the shamoperated group.In group 2 and group 3, hepatoduodenal ligament dissection was performed after laparotomy.Once the common bile duct was made apparent, it was ligated with 4/0 silk surgical suture and cut between both sutures.Group 2 (n=10) was the control group.Group 3 (n=10) was the GA group.GA (50 mg/kg) was administered by oral gavage daily for 10 days.At the end of the experiment on day 10, the rats were anesthetized.Fibrosis, inflammation, ductal proliferation and necrosis were evaluated histopathologically.Serum levels of AST, ALT, TBIL, DBIL, LDH and GGT levels were determined.In the serum and liver, TAS, TOS, MDA, TNF-α, IL-1, IL-6, and IL 10 levels were evaluated.Results: When group 2 and group 3 were compared histopathologically, fibrosis and inflammation were significantly lower in group 3.In group 3, all LFTs (except DBIL), liver and serum IL-6, IL-1, TOS, MDA, and TNF-α levels were significantly lower than group 2, whereas IL-10 and TAS values were increased.Conclusion: Findings of this research indicate that GA may be effective against OC-induced liver damage in a rat model.We presume that the beneficial effects of GA are closely associated with its antioxidant and antiinflammatory activities.Therefore, we think that using GA can save us time before resorting to the surgical method.

Background. Gallic acid (GA) has been shown to inhibit demineralization and enhance remineralization of enamel; however, GA solution is highly acidic. This study was to investigate the stability of GA solutions at various pH and to examine the resultant effects on enamel demineralization. Methods. The stability of GA in H2O or in phosphate buffer at pH 5.5, pH 7.0 and pH 10.0 was evaluated qualitatively by ultraviolet absorption spectra and quantified by high performance liquid chromatography with diode array detection (HPLC-DAD). Then, bovine enamel blocks were subjected to a pH-cycling regime of 12 cycles. Each cycle included 5 min applications with one of the following treatments: 1 g/L NaF (positive control), 4 g/L GA in H2O or buffered at pH 5.5, pH 7.0 and pH 10.0 and buffers without GA at the same pH (negative control), followed by a 60 min application with pH 5.0 acidic buffers and a 5 min application with neutral buffers. The acidic buffers were analysed for dissolved calcium. Results. GA was stable in pure water and acidic condition, but was unstable in neutral and alkaline conditions, in which ultraviolet spectra changed and HPLC-DAD analysis revealed that most of the GA was degraded. All the GA groups significantly inhibited demineralization (p < 0.05) and there was no significant difference of the inhibition efficacy among different GA groups (p > 0.05). Conclusions. GA could inhibit enamel demineralization and the inhibition effect is not influenced by pH. GA could be a useful source as an anti-cariogenic agent for broad practical application.