Oral administration of γ-aminobutyric acid and γ-oryzanol prevents stress-induced hypoadiponectinemia

The Synergistic Protective Effect of γ-Oryzanol (OZ) and N-Acetylcysteine (NAC) against Experimentally Induced NAFLD in Rats Entails Hypoglycemic, Antioxidant, and PPARα Stimulatory Effects

This study estimated that the combined effect of γ-Oryzanol and N-acetylcysteine (NAC) against high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in rats also estimated some of their mechanisms of action. Adult male rats were divided into seven groups (n = 8 each) as control, control + NAC, control + γ-Oryzanol, HFD, HFD + NAC, HFD + γ-Oryzanol, and HFD + NAC + γ-Oryzanol. NAC was administered orally at a final concentration of 200 mg/kg, whereas γ-Oryzanol was added to diets at a concentration of 0.16. All treatments were conducted for 17 weeks and daily. Both NAC and γ-Oryzanol were able to reduce final body weights, fat weights, fasting glucose, fasting insulin, serum, and serum levels of liver function enzymes as well as the inflammatory markers such as tumor necrosis factor-α (TNF-α), interleukine-6 (IL-6), and leptin in HFD-fed rats. They also improved hepatic structure and glucose tolerance, increased adiponectin levels, and reduced serum and hepatic levels of triglycerides (TGs) and cholesterol (CHOL) in these rats. These effects were concomitant with a reduction in the hepatic levels of lipid peroxides (MDA) and serum levels of LDL-C, but also with an increment in the hepatic levels of superoxide dismutase (SOD) and glutathione (GSH). Interestingly, only treatment with γ-Oryzanol stimulated the mRNA levels of proliferator-activated receptor alpha (PPARα) and carnitine palmitoyltransferase 1 (CPT1) in the liver and white adipose tissue (WAT) of rats. Of note, the combination therapy of both drugs resulted in maximum effects and restored almost normal liver structure and basal levels of all the above-mentioned metabolic parameters. In conclusion, a combination therapy of γ-Oryzanol and NAC is an effective therapy to treat NAFLD, which can act via several mechanisms on the liver and adipose tissue.

Long-term GABA administration improves FNDC5, TFAM, and UCP3 mRNA expressions in the skeletal muscle and serum irisin levels in chronic type 2 diabetic rats

In this study, we aimed to investigate whether the anti-diabetic effects of γ-aminobutyric acid (GABA) and insulin can be mediated through the regulation of gene expression related to irisin production and mitochondrial biogenesis in type 2 diabetic mellitus (T2DM) rats. Four groups (n = 6) were used in this study: control, T2DM, T2DM + insulin, and T2DM + GABA groups. After T2DM induction for 3 months (high-fat diet + 35 mg/kg streptozotocin) and treatment with GABA or insulin for 3 months, circulating levels of FBG, triglyceride, LDL, Ox-LDL, and insulin as well as hepatic and serum irisin levels were measured. The mRNA expressions of fibronectin type III domain-containing protein 5 (FNDC5), mitochondrial transcription factor A (TFAM), and mitochondrial uncoupling protein 3 (UCP3) were also evaluated in the skeletal muscle of all groups. GABA therapy improved the FBG and insulin levels in diabetic rats. Insulin treatment significantly reduced FBG and failed to maintain glucose close to the control level. Insulin or GABA therapy significantly decreased the levels of LDL, Ox-LDL, and HOMA-IR index. Circulating irisin levels were markedly decreased in insulin-treated group, while irisin levels did not show significant changes in GABA-treated group compared with control group. GABA or insulin therapy increased mRNA expressions of TFAM and UCP3 in diabetic rats. GABA therapy also led to a significant increase in FNDC5 mRNA. Our findings suggest that the anti-diabetic effect of GABA may be mediated, in part, by a decrease in Ox-LDL levels and an increase in the levels of irisin as well as FNDC5, TFAM, and UCP3 gene expression in T2DM rats.

Functional Profiling and Future Research Direction of Rice Bran Oil in Bangladesh

Rice bran oil (RBO) has been demonstrated to affect complex malfunctioned conditions such as oxidative stress, hyperlipidemia, hyperglycemia, hypertension, inflammation, abnormal cell growth (cancer), ulceration, immune and cognitive modulation. This unique effect of RBO is due to the presence of well-balanced fatty acid composition and several bioactive compounds, γ- oryzanol (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, campesterol ferulate, and β-sitosteryl ferulate), vitamin E (tocopherol and tocotrienol), phytosterols (β-sitosterol, campesterol and stigmasterol) and other nutrients. The RBO composition of bioactive compounds varied geographically, thus the clear-cut mechanisms of action on complex disease cascades are still required. This review article summarized the RBO compositional profiling and compared it with other edible oils. This article also summarized Bangladesh RBO profiling and their proposed mechanism of action as well as the first line of defense in the prevention, management, and control of complex disease conditions. This review indicates how Bangladesh RBO increase their opportunity to be functional food for 21st century's ailment.

ORY supplementation mitigates acetaminophen-induced acute liver failure in male mice: role of oxidative stress and apoptotic markers

The aim of the present study was to assess the possible protective effect of γ-oryzanol (ORY) supplementation in a model of acute liver failure (ALF) induced by acetaminophen (APAP) in mice. Male Swiss strain mice were supplemented with ORY (10 and 50 mg/kg, per oral route) daily for 7 days. One hour after the last supplementation, animals received APAP (300 mg/kg, intraperitoneal). Twenty-four hours after APAP administration, mice were euthanized, and biochemical and histopathological determinations were performed. Histopathological analysis revealed that APAP caused vascular congestion, loss of cellular structure, and cellular infiltration in hepatocytes. Moreover, it caused oxidative damage (enzymatic and non-enzymatic analysis of oxidative stress), with loss of hepatic function leading to cell apoptosis (apoptotic parameters). ORY supplementation (ORY-10 and ORY-50) protected against all changes in ALF model. Thus, the protective effect of ORY supplementation was due to modulation of antioxidant defenses avoiding the apoptotic process.

Phytochemical Profile of Brown Rice and Its Nutrigenomic Implications

Whole grain foods have been promoted to be included as one of the important components of a healthy diet because of the relationship between the regular consumption of whole-grain foods and reduced risk of chronic diseases. Rice is a staple food, which has been widely consumed for centuries by many Asian countries. Studies have suggested that brown rice is associated with a wide spectrum of nutrigenomic implications such as anti-diabetic, anti-cholesterol, cardioprotective and antioxidant. This is because of the presence of various phytochemicals that are mainly located in bran layers of brown rice. Therefore, this paper is a review of publications that focuses on the bioactive compounds and nutrigenomic implications of brown rice. Although current evidence supports the fact that the consumption of brown rice is beneficial for health, these studies are heterogeneous in terms of their brown rice samples used and population groups, which cause the evaluation to be difficult. Future clinical studies should focus on the screening of individual bioactive compounds in brown rice with reference to their nutrigenomic implications.

Presence of orally administered rice bran oil γ-oryzanol in its intact form in mouse plasma

Although the beneficial effects (e.g., lipid-lowering activity) of γ-oryzanol (OZ), a mixture of ferulic acid esters of plant sterols and triterpene alcohols, have been extensively investigated, few studies have evaluated the absorption and metabolism of OZ. Moreover, it is unclear whether OZ, once ingested, is directly absorbed by the intestine into the bloodstream at a sufficient level to exhibit activity. Here, we prepared OZ concentrate from purified rice bran oil (Rice Oil OZ), determined the concentration of OZ in the preparation (cycloartenyl ferulate equivalent concentration; 52.2%), and then carried out chromatography-mass spectrometry analysis of plasma samples from mice after oral administration of Rice Oil OZ. The OZ concentrations of plasma from the control (vehicle-treated) mice were low (trace levels); however, at 5 h after a single oral administration of the Rice Oil OZ (600 mg per kg body weight), the levels significantly increased, reaching 17.6 ng mL^-1 for cycloartenyl ferulate, 28.2 ng mL^-1 for 24-methylenecycloartanyl ferulate isomers, 15.6 ng mL^-1 for campesteryl ferulate, and 5.1 ng mL^-1 for β-sitosteryl ferulate, respectively, expressed in equivalence of cycloartenyl ferulate in plasma. These results provided the first mass spectrometric evidence suggesting that a portion of orally administered OZ is directly absorbed by the intestine and is present in the intact form in plasma. The presence of a significant amount of OZ in its intact form in plasma may explain the beneficial effects of OZ in vivo.

Antioxidant Activity of γ-Oryzanol: A Complex Network of Interactions

γ-oryzanol (Orz), a steryl ferulate extracted from rice bran layer, exerts a wide spectrum of biological activities. In addition to its antioxidant activity, Orz is often associated with cholesterol-lowering, anti-inflammatory, anti-cancer and anti-diabetic effects. In recent years, the usefulness of Orz has been studied for the treatment of metabolic diseases, as it acts to ameliorate insulin activity, cholesterol metabolism, and associated chronic inflammation. Previous studies have shown the direct action of Orz when downregulating the expression of genes that encode proteins related to adiposity (CCAAT/enhancer binding proteins (C/EBPs)), inflammatory responses (nuclear factor kappa-B (NF-κB)), and metabolic syndrome (peroxisome proliferator-activated receptors (PPARs)). It is likely that this wide range of beneficial activities results from a complex network of interactions and signals triggered, and/or inhibited by its antioxidant properties. This review focuses on the significance of Orz in metabolic disorders, which feature remarkable oxidative imbalance, such as impaired glucose metabolism, obesity, and inflammation.

An atlas of G-protein coupled receptor expression and function in human subcutaneous adipose tissue

G-protein coupled receptors (GPCRs) are involved in the regulation of adipose tissue function, but the total number of GPCRs expressed by human subcutaneous adipose tissue, as well as their function and interactions with drugs, is poorly understood. We have constructed an atlas of all GPCRs expressed by human subcutaneous adipose tissue: the 'adipose tissue GPCRome', to support the exploration of novel control nodes in metabolic and endocrine functions. This atlas describes how adipose tissue GPCRs regulate lipolysis, insulin resistance and adiponectin and leptin secretion. We also discuss how adipose tissue GPCRs interact with their endogenous ligands and with GPCR-targeting drugs, with a focus on how drug/receptor interactions may affect lipolysis, and present a model predicting how GPCRs with unknown effects on lipolysis might modulate cAMP-regulated lipolysis. Subcutaneous adipose tissue expresses 163 GPCRs, a majority of which have unknown effects on lipolysis, insulin resistance and adiponectin and leptin secretion. These GPCRs are activated by 180 different endogenous ligands, and are the targets of a large number of clinically used drugs. We identified 119 drugs, acting on 23 GPCRs, that are predicted to stimulate lipolysis and 173 drugs, acting on 25 GPCRs, that are predicted to inhibit lipolysis. This atlas highlights knowledge gaps in the current understanding of adipose tissue GPCR function, and identifies GPCR/ligand/drug interactions that might affect lipolysis, which is important for understanding and predicting metabolic side effects of drugs. This approach may aid in the design of new, safer therapeutic agents, with fewer undesired effects on lipid homeostasis.

Nutrigenomic effects of germinated brown rice and its bioactives on hepatic gluconeogenic genes in type 2 diabetic rats and HEPG2 cells

SCOPE

Chronic sustained hyperglycemia underlies the symptomatology and complications of type 2 diabetes mellitus, and dietary components contribute to it. Germinated brown rice (GBR) improves glycemic control but the mechanisms involved are still the subject of debate. We now show one mechanism by which GBR lowers blood glucose.

METHODS AND RESULTS

Effects of GBR, brown rice, and white rice (WR) on fasting plasma glucose and selected genes were studied in type 2 diabetic rats. GBR reduced plasma glucose and weight more than metformin, while WR worsened glycemia over 4 weeks of intervention. Through nutrigenomic suppression, GBR downregulated gluconeogenic genes (Fbp1 and Pck1) in a manner similar to, but more potently than, metformin, while WR upregulated the same genes. Bioactives (gamma-amino butyric acid, acylated steryl glycoside, oryzanol, and phenolics) were involved in GBR's downregulation of both genes. Plasma glucose, Fbp1 and Pck1 changes significantly affected the weight of rats (p = 0.0001).

CONCLUSION

The fact that GBR downregulates gluconeogenic genes similar to metformin, but produces better glycemic control in type 2 diabetic rats, suggests other mechanisms are involved in GBR's antihyperglycemic properties. GBR as a staple could potentially provide enhanced glycemic control in type 2 diabetes mellitus better than metformin.

Antidiabetic properties of germinated brown rice: a systematic review

Diet is an important variable in the course of type 2 diabetes, which has generated interest in dietary options like germinated brown rice (GBR) for effective management of the disease among rice-consuming populations. In vitro data and animal experiments show that GBR has potentials as a functional diet for managing this disease, and short-term clinical studies indicate encouraging results. Mechanisms for antidiabetic effects of GBR due to bioactive compounds like γ-aminobutyric acid (GABA), γ-oryzanol, dietary fibre, phenolics, vitamins, acylated steryl β-glucoside, and minerals include antihyperglycemia, low insulin index, antioxidative effect, antithrombosis, antihypertensive effect, hypocholesterolemia, and neuroprotective effects. The evidence so far suggests that there may be enormous benefits for diabetics in rice-consuming populations if white rice is replaced with GBR. However, long-term clinical studies are still needed to verify these findings on antidiabetic effects of GBR. Thus, we present a review on the antidiabetic properties of GBR from relevant preclinical and clinical studies, in order to provide detailed information on this subject for researchers to review the potential of GBR in combating this disease.