Effect of GABA on oxidative stress in the skeletal muscles and plasma free amino acids in mice fed high-fat diet.
Xie Z X,Xia S F,Qiao Y,Shi Y H,Le G W
Journal of animal physiology and animal nutrition
Increased levels of plasma free amino acids (pFAAs) can disturb the blood glucose levels in patients with obesity, diabetes mellitus and metabolic syndrome (MS) and are associated with enhanced protein oxidation. Oxidation of proteins, especially in the muscles, can promote protein degradation and elevate the levels of pFAAs. Gamma-aminobutyric acid (GABA), a food additive, can reduce high-fat diet (HFD)-induced hyperglycaemia; however, the mechanisms remain unclear. The aim of this study was to evaluate the effects of GABA on protein oxidation and pFAAs changes. One hundred male C57BL/6 mice were randomly divided into five groups that were fed with control diet, HFD and HFD supplied with 0.2%, 0.12% and 0.06% GABA in drinking water for 20 weeks respectively. HFD feeding led to muscular oxidative stress, protein oxidation, pFAA disorders, hyperglycaemia and augmented plasma GABA levels. Treatment with GABA restored normally fasting blood glucose level and dose-dependently inhibited body weight gains, muscular oxidation and protein degradation. While medium and low doses of GABA mitigated HFD-induced pFAA disorders, the high dose of GABA deteriorated the pFAA disorders. Medium dose of GABA increased the levels of GABA, but high dose of GABA reduced the levels of plasma GABA and increased the activity of succinic semialdehyde dehydrogenase in the liver. Therefore, treatment with GABA mitigated HFD-induced hyperglycaemia probably by repairing HFD-induced muscular oxidative stress and pFAA disorders in mice. Our data also suggest that an optimal dose of GABA is crucial for the prevention of excess GABA-related decrease in the levels of pFAA and GABA as well as obesity.
10.1111/jpn.12254
GABA and Fermented L. Extract Enriched with GABA Ameliorate Obesity through Nox4-IRE1α Sulfonation-RIDD-SIRT1 Decay Axis in High-Fat Diet-Induced Obese Mice.
Nutrients
- (GABA) is a natural amino acid with antioxidant activity and is often considered to have therapeutic potential against obesity. Obesity has long been linked to ROS and ER stress, but the effect of GABA on the ROS-associated ER stress axis has not been thoroughly explored. Thus, in this study, the effect of GABA and fermented L. extract enriched with GABA (FCLL-GABA) on the ROS-related ER stress axis and inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α) sulfonation were examined with the HFD model to determine the underlying anti-obesity mechanism. Here, GABA and FCLL-GABA supplementations significantly inhibited the weight gain in HFD fed mice. The GABA and FCLL-GABA supplementation lowered the expressions of adipogenic transcription factors such as PPAR-γ, C/EBPα, FAS, and SREBP-1c in white adipose tissue (WAT) and liver from HFD-fed mice. The enhanced hyper-nutrient dysmetabolism-based NADPH oxidase (Nox) 4 and the resultant IRE1α sulfonation-RIDD-SIRT1 decay under HFD conditions were controlled with GABA and FCLL-GABA. Notably, GABA and FCLL-GABA administration significantly increased AMPK and sirtuin 1 (SIRT1) levels in WAT of HFD-fed mice. These significant observations indicate that ER-localized Nox4-induced IRE1α sulfonation results in the decay of SIRT1 as a novel mechanism behind the positive implications of GABA on obesity. Moreover, the investigation lays a firm foundation for the development of FCLL-GABA as a functional ingredient.
10.3390/nu14081680
MCH Regulates SIRT1/FoxO1 and Reduces POMC Neuronal Activity to Induce Hyperphagia, Adiposity, and Glucose Intolerance.
Al-Massadi Omar,Quiñones Mar,Clasadonte Jerome,Hernandez-Bautista René,Romero-Picó Amparo,Folgueira Cintia,Morgan Donald A,Kalló Imre,Heras Violeta,Senra Ana,Funderburk Samuel C,Krashes Michael J,Souto Yara,Fidalgo Miguel,Luquet Serge,Chee Melissa J,Imbernon Monica,Beiroa Daniel,García-Caballero Lucía,Gallego Rosalia,Lam Brian Y H,Yeo Giles,Lopez Miguel,Liposits Zsolt,Rahmouni Kamal,Prevot Vincent,Dieguez Carlos,Nogueiras Ruben
Diabetes
Melanin-concentrating hormone (MCH) is an important regulator of food intake, glucose metabolism, and adiposity. However, the mechanisms mediating these actions remain largely unknown. We used pharmacological and genetic approaches to show that the sirtuin 1 (SIRT1)/FoxO1 signaling pathway in the hypothalamic arcuate nucleus (ARC) mediates MCH-induced feeding, adiposity, and glucose intolerance. MCH reduces proopiomelanocortin (POMC) neuronal activity, and the SIRT1/FoxO1 pathway regulates the inhibitory effect of MCH on POMC expression. Remarkably, the metabolic actions of MCH are compromised in mice lacking SIRT1 specifically in POMC neurons. Of note, the actions of MCH are independent of agouti-related peptide (AgRP) neurons because inhibition of γ-aminobutyric acid receptor in the ARC did not prevent the orexigenic action of MCH, and the hypophagic effect of MCH silencing was maintained after chemogenetic stimulation of AgRP neurons. Central SIRT1 is required for MCH-induced weight gain through its actions on the sympathetic nervous system. The central MCH knockdown causes hypophagia and weight loss in diet-induced obese wild-type mice; however, these effects were abolished in mice overexpressing SIRT1 fed a high-fat diet. These data reveal the neuronal basis for the effects of MCH on food intake, body weight, and glucose metabolism and highlight the relevance of SIRT1/FoxO1 pathway in obesity.
10.2337/db19-0029
Rapid binge-like eating and body weight gain driven by zona incerta GABA neuron activation.
Science (New York, N.Y.)
The neuronal substrate for binge eating, which can at times lead to obesity, is not clear. We find that optogenetic stimulation of mouse zona incerta (ZI) γ-aminobutyric acid (GABA) neurons or their axonal projections to paraventricular thalamus (PVT) excitatory neurons immediately (in 2 to 3 seconds) evoked binge-like eating. Minimal intermittent stimulation led to body weight gain; ZI GABA neuron ablation reduced weight. ZI stimulation generated 35% of normal 24-hour food intake in just 10 minutes. The ZI cells were excited by food deprivation and the gut hunger signal ghrelin. In contrast, stimulation of excitatory axons from the parasubthalamic nucleus to PVT or direct stimulation of PVT glutamate neurons reduced food intake. These data suggest an unexpected robust orexigenic potential for the ZI GABA neurons.
10.1126/science.aam7100
The hepatoprotective effects of n3-polyunsaturated fatty acids against non-alcoholic fatty liver disease in diabetic rats through the FOXO1/PPARα/GABARAPL1 signalling pathway.
Life sciences
AIM:We compared the efficacy of n3-polyunsaturated fatty acids (n3-PUFAs) and metformin in halting the progression of non-alcoholic fatty liver disease (NAFLD) developed in the milieu of insulin deficiency. MAIN METHODS:NAFLD was induced by a chronic high-fat diet (HFD) in male Sprague Dawley rats, rendered diabetic by a low dose streptozotocin (STZ). Diabetic rats were treated with n3-PUFAs (300 mg/kg/d) or metformin (150 mg/kg/d) for 8 weeks. Improvements in the NAFLD score and hepatic insulin resistance (IR) were addressed and correlated to changes in the hepatic expression of Forkhead box protein O1 (FOXO-1), microtubule-associated proteins 1A/1B light chain 3B (MAP1LC3B) and gamma-aminobutyric acid receptor-associated protein-like 1 (GABARAPL1) genes. Hepatic peroxisome proliferator-activated receptor alpha (PPAR-α), and B-cell lymphoma 2 (Bcl-2) protein expression was also assessed. KEY FINDINGS:Driven by insulin deficiency and HFD, the FOXO-1 gene along with its downstream targets, MAP1LC3B and GABARAPL1, were highly expressed in the liver tissue of the HFD/STZ group. Meanwhile, hepatic expression of PPAR-α and Bcl-2 was markedly decreased. These abnormalities coincided with a marked increase in the hepatic IR and NAFLD activity. Comparable to metformin, n3-PUFAs were able to rearrange hepatic PPAR-α and FOXO-1 expression in HFD/STZ rats, resulting in improved diabetic/steatotic liver phenotype. SIGNIFICANCE:Along with the enhancement of PPAR-α expression, inhibition of FoxO1/GABARAPL1/MAP1LC3B transcription is suggested as a core mechanism for the protective effects of n3-PUFAs on hepatic IR and NAFLD. Under conditions of insulin deficiency, n3-PUFAs retain their potential as a safe and promising approach for the control of NAFLD.
10.1016/j.lfs.2022.121145
Gamma-Aminobutyric Acid Promotes Beige Adipocyte Reconstruction by Modulating the Gut Microbiota in Obese Mice.
Nutrients
Given the increasing prevalence of obesity, the white-to-beige adipocyte conversion has attracted interest as a target for obesity treatment. Gamma-aminobutyric acid (GABA) treatment can reduce obesity, but the underlying mechanism remains unclear. Here, we aimed to investigate the mechanism by which GABA triggers weight loss by improving the beiging of inguinal white adipose tissue (iWAT) and the role of gut microbiota in this process. The results showed that GABA reduced body weight and adipose inflammation and promoted the expression of thermogenic genes in the iWAT. The 16S rRNA sequence analysis of gut microbiota showed that GABA treatment increased the relative abundance of Bacteroidetes, Akkermansia, and Romboutsia and reduced that of Firmicutes and Erysipelatoclostridium in obese mice. Additionally, serum metabolomic analysis revealed that GABA treatment increased 3-hydroxybutyrate and reduced oxidized lipid levels in obese mice. Spearman's correlation analysis showed that Akkermansia and Romboutsia were negatively associated with the levels of oxidized lipids. Fecal microbiota transplantation analysis confirmed that the gut microbiota was involved in the white-to-beige adipocyte reconstruction by GABA. Overall, our findings suggest that GABA treatment may promote iWAT beiging through the gut microbiota in obese mice. GABA may be utilized to protect obese people against metabolic abnormalities brought on by obesity and gut dysbiosis.
10.3390/nu15020456
Gamma-aminobutyric acid attenuates insulin resistance in type 2 diabetic patients and reduces the risk of insulin resistance in their offspring.
Rezazadeh Hossein,Sharifi Mohammad Reza,Sharifi Mohmmadreza,Soltani Nepton
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie
The role of gamma-aminobutyric acid (GABA) in attenuates insulin resistance (IR) in type 2 diabetic (T2D) patients and the reduction of the risk of IR in their offspring, and the function of GLUT4, IRS1 and Akt2 genes expression were investigated. T2D was induced by high fat diet and 35 mg/kg of streptozotocin. The male and female diabetic rats were then divided into three groups: CD, GABA, and insulin. NDC group received a normal diet. All the animals were studied for a six-month. Their offspring were just fed with normal diet for four months. Blood glucose was measured weekly in patients and their offspring. Intraperitoneal glucose tolerance test (IPGTT), urine volume, and water consumption in both patients and their offspring were performed monthly. The hyperinsulinemic euglycemic clamp in both patients and their offspring was done and blood sample collected to measure Hemoglobin A1c (HbA1c). IRS1, Akt and GLUT4 gene expressions in muscle were evaluated in all the groups. GABA or insulin therapy decreased blood glucose, IPGTT, and HbA1c in patients and their offspring compared to DC group. They also increased GIR in patients and their offspring. IRS1, Akt and GLUT4 gene expressions improved in both patients in comparison with DC group. GABA exerts beneficial effects on IRS1 and Akt gene expressions in GABA treated offspring. GABA therapy improved insulin resistance in diabetic patients by increasing the expression of GLUT4. It is also indirectly able to reduce insulin resistance in their offspring possibly through the increased gene expressions of IRS1 and Akt.
10.1016/j.biopha.2021.111440
High-Caloric Diets in Adolescence Impair Specific GABAergic Subpopulations, Neurogenesis, and Alter Astrocyte Morphology.
International journal of molecular sciences
We compared the effects of two different high-caloric diets administered to 4-week-old rats for 12 weeks: a diet rich in sugar (30% sucrose) and a cafeteria diet rich in sugar and high-fat foods. We focused on the hippocampus, particularly on the gamma-aminobutyric acid (GABA)ergic system, including the Ca-binding proteins parvalbumin (PV), calretinin (CR), calbindin (CB), and the neuropeptides somatostatin (SST) and neuropeptide Y (NPY). We also analyzed the density of cholinergic varicosities, brain-derived neurotrophic factor (), reelin (), and cyclin-dependent kinase-5 () mRNA levels, and glial fibrillary acidic protein (GFAP) expression. The cafeteria diet reduced PV-positive neurons in the granular layer, hilus, and CA1, as well as NPY-positive neurons in the hilus, without altering other GABAergic populations or overall GABA levels. The high-sugar diet induced a decrease in the number of PV-positive cells in CA3 and an increase in CB-positive cells in the hilus and CA1. No alterations were observed in the cholinergic varicosities. The cafeteria diet also reduced the relative mRNA expression of RELN without significant changes in BDNF and CDK5 levels. The cafeteria diet increased the number but reduced the length of the astrocyte processes. These data highlight the significance of determining the mechanisms mediating the observed effects of these diets and imply that the cognitive impairments previously found might be related to both the neuroinflammation process and the reduction in PV, NPY, and RELN expression in the hippocampal formation.
10.3390/ijms25105524
Oral treatment with γ-aminobutyric acid improves glucose tolerance and insulin sensitivity by inhibiting inflammation in high fat diet-fed mice.
Tian Jide,Dang Hoa N,Yong Jing,Chui Wing-Sheung,Dizon Matthew P G,Yaw Catherine K Y,Kaufman Daniel L
PloS one
Adipocyte and β-cell dysfunction and macrophage-related chronic inflammation are critical for the development of obesity-related insulin resistance and type 2 diabetes mellitus (T2DM), which can be negatively regulated by Tregs. Our previous studies and those of others have shown that activation of γ-aminobutyric acid (GABA) receptors inhibits inflammation in mice. However, whether GABA could modulate high fat diet (HFD)-induced obesity, glucose intolerance and insulin resistance has not been explored. Here, we show that although oral treatment with GABA does not affect water and food consumption it inhibits the HFD-induced gain in body weights in C57BL/6 mice. Furthermore, oral treatment with GABA significantly reduced the concentrations of fasting blood glucose, and improved glucose tolerance and insulin sensitivity in the HFD-fed mice. More importantly, after the onset of obesity and T2DM, oral treatment with GABA inhibited the continual HFD-induced gain in body weights, reduced the concentrations of fasting blood glucose and improved glucose tolerance and insulin sensitivity in mice. In addition, oral treatment with GABA reduced the epididymal fat mass, adipocyte size, and the frequency of macrophage infiltrates in the adipose tissues of HFD-fed mice. Notably, oral treatment with GABA significantly increased the frequency of CD4(+)Foxp3(+) Tregs in mice. Collectively, our data indicated that activation of peripheral GABA receptors inhibited the HFD-induced glucose intolerance, insulin resistance, and obesity by inhibiting obesity-related inflammation and up-regulating Treg responses in vivo. Given that GABA is safe for human consumption, activators of GABA receptors may be valuable for the prevention of obesity and intervention of T2DM in the clinic.
10.1371/journal.pone.0025338
Ketone Administration for Seizure Disorders: History and Rationale for Ketone Esters and Metabolic Alternatives.
Poff Angela M,Rho Jong M,D'Agostino Dominic P
Frontiers in neuroscience
The ketogenic diet (KD) is a high-fat, low-carbohydrate treatment for medically intractable epilepsy. One of the hallmark features of the KD is the production of ketone bodies which have long been believed, but not yet proven, to exert direct anti-seizure effects. The prevailing view has been that ketosis is an epiphenomenon during KD treatment, mostly due to clinical observations that blood ketone levels do not correlate well with seizure control. Nevertheless, there is increasing experimental evidence that ketone bodies alone can exert anti-seizure properties through a multiplicity of mechanisms, including but not limited to: (1) activation of inhibitory adenosine and ATP-sensitive potassium channels; (2) enhancement of mitochondrial function and reduction in oxidative stress; (3) attenuation of excitatory neurotransmission; and (4) enhancement of central γ-aminobutyric acid (GABA) synthesis. Other novel actions more recently reported include inhibition of inflammasome assembly and activation of peripheral immune cells, and epigenetic effects by decreasing the activity of histone deacetylases (HDACs). Collectively, the preclinical evidence to date suggests that ketone administration alone might afford anti-seizure benefits for patients with epilepsy. There are, however, pragmatic challenges in administering ketone bodies in humans, but prior concerns may largely be mitigated through the use of ketone esters or balanced ketone electrolyte formulations that can be given orally and induce elevated and sustained hyperketonemia to achieve therapeutic effects.
10.3389/fnins.2019.01041
A critical role of hepatic GABA in the metabolic dysfunction and hyperphagia of obesity.
Cell reports
Hepatic lipid accumulation is a hallmark of type II diabetes (T2D) associated with hyperinsulinemia, insulin resistance, and hyperphagia. Hepatic synthesis of GABA, catalyzed by GABA-transaminase (GABA-T), is upregulated in obese mice. To assess the role of hepatic GABA production in obesity-induced metabolic and energy dysregulation, we treated mice with two pharmacologic GABA-T inhibitors and knocked down hepatic GABA-T expression using an antisense oligonucleotide. Hepatic GABA-T inhibition and knockdown decreased basal hyperinsulinemia and hyperglycemia and improved glucose intolerance. GABA-T knockdown improved insulin sensitivity assessed by hyperinsulinemic-euglycemic clamps in obese mice. Hepatic GABA-T knockdown also decreased food intake and induced weight loss without altering energy expenditure in obese mice. Data from people with obesity support the notion that hepatic GABA production and transport are associated with serum insulin, homeostatic model assessment for insulin resistance (HOMA-IR), T2D, and BMI. These results support a key role for hepatocyte GABA production in the dysfunctional glucoregulation and feeding behavior associated with obesity.
10.1016/j.celrep.2021.109301
GABA type B receptor signaling in proopiomelanocortin neurons protects against obesity, insulin resistance, and hypothalamic inflammation in male mice on a high-fat diet.
Ito Yoshihiro,Banno Ryoichi,Shibata Miyuki,Adachi Koichi,Hagimoto Shigeru,Hagiwara Daisuke,Ozawa Yoshiharu,Goto Motomitsu,Suga Hidetaka,Sugimura Yoshihisa,Bettler Bernhard,Oiso Yutaka,Arima Hiroshi
The Journal of neuroscience : the official journal of the Society for Neuroscience
There is evidence suggesting that the GABA system in the arcuate nucleus, where orexigenic neuropeptide Y and agouti-related peptide as well as anorexigenic proopiomelanocortin (POMC) are expressed, plays an important role in energy balance. In this study, we generated POMC-specific GABAB receptor-deficient [knock-out (KO)] mice. Male KO mice on a high-fat diet (HFD) showed mild increases in body weight (BW) at the age of 9 weeks compared to wild-type (WT) mice, and the differences remained significant until 16 weeks old. However, there was no difference in BW in females between genotypes. While food intake was similar between genotypes, oxygen consumption was significantly decreased in the male KO mice. The insulin tolerance test revealed that the male KO mice were less insulin sensitive compared to WT mice at the age of 8 weeks, when there was no significant difference in BW between genotypes. Despite increased BW, POMC mRNA expression in the arcuate nucleus was significantly decreased in the KO mice compared to WT mice at the age of 16 weeks. Furthermore, the expression of TNFα as well as IL-6, proinflammatory markers in the hypothalamus, was significantly increased in the KO mice on a HFD compared to WT mice. This demonstrates that the deletion of GABAB receptors in POMC neurons in the male mice on a HFD results in obesity, insulin resistance, and hypothalamic inflammation. Furthermore, the decreased POMC expression in the obese KO mice suggests that the regulation of POMC expression through GABAB receptors is essential for proper energy balance.
10.1523/JNEUROSCI.0897-13.2013
Sleep loss impairs intestinal stem cell function and gut homeostasis through the modulation of the GABA signalling pathway in Drosophila.
Cell proliferation
Sleep is essential for maintaining health. Indeed, sleep loss is closely associated with multiple health problems, including gastrointestinal disorders. However, it is not yet clear whether sleep loss affects the function of intestinal stem cells (ISCs). Mechanical sleep deprivation and sss mutant flies were used to generate the sleep loss model. qRT-PCR was used to measure the relative mRNA expression. Gene knock-in flies were used to observe protein localization and expression patterns. Immunofluorescence staining was used to determine the intestinal phenotype. The shift in gut microbiota was observed using 16S rRNA sequencing and analysis. Sleep loss caused by mechanical sleep deprivation and sss mutants disturbs ISC proliferation and intestinal epithelial repair through the brain-gut axis. In addition, disruption of SSS causes gut microbiota dysbiosis in Drosophila. As regards the mechanism, gut microbiota and the GABA signalling pathway both partially played a role in the sss regulation of ISC proliferation and gut function. The research shows that sleep loss disturbed ISC proliferation, gut microbiota, and gut function. Therefore, our results offer a stem cell perspective on brain-gut communication, with details on the effect of the environment on ISCs.
10.1111/cpr.13437
Fly into tranquility: GABA's role in Drosophila sleep.
Current opinion in insect science
Sleep is conserved across the animal kingdom, and Drosophila melanogaster is a prime model to understand its intricate circadian and homeostatic control. GABA (gamma-aminobutyric acid), the brain's main inhibitory neurotransmitter, plays a central role in sleep. This review delves into GABA's complex mechanisms of actions within Drosophila's sleep-regulating neural networks. We discuss how GABA promotes sleep, both by inhibiting circadian arousal neurons and by being a key neurotransmitter in sleep homeostatic circuits. GABA's impact on sleep is modulated by glia through astrocytic GABA recapture and metabolism. Interestingly, GABA can be coexpressed with other neurotransmitters in sleep-regulating neurons, which likely contributes to context-based sleep plasticity.
10.1016/j.cois.2024.101219
GABA Prevents Age-Related Sarcopenic Obesity in Mice with High-Fat-Diet-Induced Obesity.
Cells
Sarcopenic obesity is characterized by concurrent obesity and muscle wasting (sarcopenia) and is common in the elderly. Sarcopenic obesity has steadily increased as the aging population has grown and is an increasing public health burden. Both obesity and sarcopenia independently increase health risks of the elderly, but sarcopenic obesity has a greater effect on metabolic disease than either obesity or sarcopenia alone. The metabolic mechanisms of obesity and sarcopenia are strongly interconnected, and obesity and sarcopenia form a vicious cycle, with each pathology exacerbating the other. The pathogenesis of sarcopenic obesity is more complex than either disease alone and remains incompletely understood, underscoring the significant unmet clinical need for effective sarcopenic obesity treatments. We aimed to determine the efficacy and underlying regulatory mechanisms of Gamma-aminobutyric acid (GABA) in sarcopenic obesity in high-fat-diet-fed obese aged mice and alterations in related mechanisms to determine the potential of GABA as a therapeutic modality for sarcopenic obesity. In this study, we used young (3 months) and aged (20 months) mice to evaluate age-related sarcopenic obesity. The daily administration of GABA for 8 weeks resulted in decreased fat mass and increased muscle mass and strength in aged mice. GABA also enhanced energy expenditure in both adipose tissue and skeletal muscle. In addition, GABA promoted muscle synthesis and decreased muscle degradation by activating the phosphatidylinositol-3-kinase (PI3K)/Akt pathway. These findings demonstrate that GABA has potential uses in preventing age-related sarcopenic obesity and related metabolic diseases.
10.3390/cells12172146