Administration Of Gamma-aminobutyric Acid Research Articles

Alleviating effect of vagus nerve cutting in Salmonella-induced gut infections and anxiety-like behavior via enhancing microbiota-derived GABA

The vagus nerve, a pivotal link within the gut-brain axis, plays a critical role in maintaining homeostasis and mediating communication between the gastrointestinal tract and the brain. It has been reported that gastrointestinal infection by Salmonella typhimurium (S. typhimurium) triggers gut inflammation and manifests as anxiety-like behaviors, yet the mechanistic involvement of the vagus nerve remains to be elucidated. In this study, we demonstrated that unilateral cervical vagotomy markedly attenuated anxiety-like behaviors induced by S. typhimurium SL1344 infection in C57BL/6 mice, as evidenced by the open field test and marble burying experiment. Furthermore, vagotomy significantly diminished neuronal activation within the nucleus of the solitary tract and amygdala, alongside mitigating aberrant glial cell activation in the hippocampus and amygdala. Additionally, vagotomy notably decreases serum endotoxin levels, counters the increase in splenic Salmonella concentration, and modulates the expression of inflammatory cytokines—including IL-6, IL-1β, and TNF-α—in both the gastrointestinal tract and brain, with a concurrent reduction in IL-22 and CXCL1 expression. This intervention also fostered the enrichment of beneficial gut microbiota, including Alistipes and Lactobacillus species, and augmented the production of gamma-aminobutyric acid (GABA) in the gut. Administration of GABA replicated the vagotomy’s beneficial effects on reducing gut inflammation and anxiety-like behavior in infected mice. However, blockade of GABA receptors with picrotoxin abrogated the vagotomy’s protective effects against gut inflammation, without influencing its impact on anxiety-like behaviors. Collectively, these findings suggest that vagotomy exerts a protective effect against infection by promoting GABA synthesis in the colon and alleviating anxiety-like behavior. This study underscores the critical role of the vagus nerve in relaying signals of gut infection to the brain and posits that targeting the gut-brain axis may offer a novel and efficacious approach to preventing gastrointestinal infections and associated behavioral abnormalities.

GABA Prevents Age-Related Sarcopenic Obesity in Mice with High-Fat-Diet-Induced Obesity.

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.

GABA treatment does not induce neogenesis of new endocrine cells from pancreatic ductal cells

ABSTRACT Previous studies indicated that ductal cells can contribute to endocrine neogenesis in adult rodents after alpha cells convert into beta cells. This can occur through Pax4 mis-expression in alpha cells or through long-term administration of gamma-aminobutyric acid (GABA) to healthy mice. GABA has also been reported to increase the number of beta cells through direct effects on their proliferation, but only in specific genetic mouse backgrounds. To test whether GABA induces neogenesis of beta cells from ductal cells or affects pancreatic cell proliferation, we administered GABA or saline over 2 or 6 months to Sox9CreER;R26RYFP mice in which 60–80% of large or small ducts were efficiently lineage labeled. We did not observe any increases in islet neogenesis from ductal cells between 1 and 2 months of age in saline treated mice, nor between 2 and 6 months of saline treatment, supporting previous studies indicating that adult ductal cells do not give rise to new endocrine cells during homeostasis. Unlike previous reports, we did not observe an increase in beta cell neogenesis after 2 or 6 months of GABA administration. Nor did we observe a significant increase in the pancreatic islet area, the number of insulin and glucagon double positive cells, or cell proliferation in the pancreas. This indicates that the effect of long term GABA administration on the pancreas is minimal or highly context dependent.

GABA Administration Ameliorates the Toxicity of Doxorubicin on CSF and the Brain of Albino Rats.

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the mammalian brain and is a non-proteinogenic amino acid. Doxorubcin (DOX) or adriamycin is one of the most potent chemotherapy drugs for breast cancer. This study focused on diminishing the brain injury and neurotoxicity of doxorubicin (DOX) by GABA administration. Rats were randomly divided into four groups (8 rats each), which were the control group, DOX group (3 mg/kg for 4 weeks, then 2 mg/kg for 2 weeks), GABA group (2 mg/kg for 21 days), and DOX + GABA group (treated as the second and third groups). Neurotoxicity and brain injury were assessed by determining CSF biomarkers, serum inflammatory markers, and histopathological evaluation of the cerebral cortex. DOX treatment significantly increased the levels of all CSF biomarkers (S100B, IL-1β, ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), glial fibrillary acidic protein (GFAP), spectrin breakdown products (SBDP145), and C-C motif chemokine ligand 2 (CCL2) and all inflammatory markers (IL-6, TNF-α, and IFN-γ), causing extensive neutrophilic infiltration and great alteration in the cerebral cortex architecture as evidence of neurotoxicity. The oral administration of GABA significantly reduced the levels of all CSF biomarkers and inflammatory markers and restored the normal architecture of the cerebral cortex, with observed ameliorations in neutrophilic infiltration. GABA administration can ameliorate neurotoxicity and protect the brain against the negative effects of DOX treatment.

Morphological changes in the myocardium of rats with chronic alcohol intoxication after treatment with new GABAand glutamic acid derivatives

Aim. To study pathohistological changes in the myocardium of rats with chronic alcohol intoxication (CAI) after treatment with a new glutamic acid derivative glufimet (compound RSPU-238) and a new gamma-aminobutyric acid (GABA) derivative (compound RSPU-260).Materials and methods. Experiments were performed on female Wistar rats aged 10 months. The rats were divided into the following groups: group 1 – intact females; group 2 – a control group which included animals after CAI simulated by replacing drinking water with 10% ethanol solution for 24 weeks; groups 3 and 4 – experimental groups, in which females were intraperitoneally administered with glufimet at a dose of 28.7 mg / kg and RSPU260 at a dose of 25 mg / kg once a day for 14 days after cessation of alcohol solution consumption; group 5 – a group of animals receiving a reference listed drug mildronate at a dose of 50 mg / kg according to a regimen similar to that of the studied compounds. Changes in microstructural and morphometric parameters of the left ventricular myocardium were assessed using light microscopy.Results. In animals after CAI, the cardiomyocyte volume fraction decreased, while the interstitial and vascular volume fractions increased. Degeneration of cardiomyocytes, such as their wave-like deformation, loss of transverse striation, foci of plasmolysis, and fragmentation of muscle fibers were revealed. In rats treated with glufimet, the structural changes in cardiomyocytes were minimal. Lower vascular plethora was observed; blood vessels were characterized by single stasis and sludge. The cardiomyocyte volume fraction was 9.7% greater than in control animals, while the interstitial and vascular volume fractions were 66.0 and 70.0% smaller, respectively. The animals treated with the RSPU-260 compound had no significant degenerative changes in cardiomyocytes and small vessels similar to the experimental animals injected with glufimet. Mildronate had a less pronounced cardioprotective effect.Conclusion. Administration of new GABA and glutamic acid derivatives to animals with simulated chronic alcohol intoxication leads to improvement of the microstructure in cardiomyocytes compared with control rats. This indicates pronounced cardioprotective effects of the studied neuroactive amino acid derivatives.

The Effect of GABA on the Gut Microbiota During Metabolic Stress

The effect of gamma-aminobutyric acid (GABA) on the gut microbiota was evaluated in experiments on 47 rats with metabolic stress (MS) induced by food deprivation. MS was found to be associated with changes in the qualitative and quantitative composition of the caecum microbiota, including the redistribution of opportunistic flora, the growth of pathogenic microorganisms, as well as a decreased number of lactobacilli and bifidobacteria. Daily administration of GABA at a dose of 70 mg/kg during MS led to a decrease in the number of pathogens, thus leading to the restoration of normal eubionts in the cecum.

Dietary Gamma-Aminobutyric Acid (GABA) Induces Satiation by Enhancing the Postprandial Activation of Vagal Afferent Nerves.

Gamma-aminobutyric acid (GABA) is present in the mammalian brain as the main inhibitory neurotransmitter and in foods. It is widely used as a supplement that regulates brain function through stress-reducing and sleep-enhancing effects. However, its underlying mechanisms remain poorly understood, as it is reportedly unable to cross the blood–brain barrier. Here, we explored whether a single peroral administration of GABA affects feeding behavior as an evaluation of brain function and the involvement of vagal afferent nerves. Peroral GABA at 20 and 200 mg/kg immediately before refeeding suppressed short-term food intake without aversive behaviors in mice. However, GABA administration 30 min before refeeding demonstrated no effects. A rise in circulating GABA concentrations by the peroral administration of 200 mg/kg GABA was similar to that by the intraperitoneal injection of 20 mg/kg GABA, which did not alter feeding. The feeding suppression by peroral GABA was blunted by the denervation of vagal afferents. Unexpectedly, peroral GABA alone did not alter vagal afferent activities histologically. The coadministration of a liquid diet and GABA potentiated the postprandial activation of vagal afferents, thereby enhancing postprandial satiation. In conclusion, dietary GABA activates vagal afferents in collaboration with meals or meal-evoked factors and regulates brain function including feeding behavior.

Synergistic effect of Korean red ginseng extract and GABA mixture on the IgE production in mice via Th1/Th2 cell balance.

It has been recently reported that the immune system has been linked to the nervous system. This study was conducted to investigate the effect of administration of two components, gamma-aminobutyric acid (GABA) and Panax ginseng Meyer (GIN), on the production of IgE and Th1-Th2 dominant cytokines. Antibody and inflammatory mediator levels in serum, and the cytokines secreted to spleen cells of ovalbumin (OVA) immunized mice were analyzed. The group of GABA and GIN mixture significantly reduced IgE level and dramatically increased OVA-IgG2a antibody production. In addition, rising effect on IFN-gamma and GM-CSF levels related to Th1 cytokine was observed only in the group of GABA + GIN. The mixture alleviated allergic symptoms by reducing the level of histamine and prostaglandin. These studies suggest that GIN + GABA administration in the allergen-induced mouse model may regulate the Th1-Th2 balance by strongly acting on the immune response associated with Th1.

United States Pharmacopeia (USP) Safety Review of Gamma-Aminobutyric Acid (GABA).

Gamma-amino butyric acid (GABA) is marketed in the U.S. as a dietary supplement. USP conducted a comprehensive safety evaluation of GABA by assessing clinical studies, adverse event information, and toxicology data. Clinical studies investigated the effect of pure GABA as a dietary supplement or as a natural constituent of fermented milk or soy matrices. Data showed no serious adverse events associated with GABA at intakes up to 18 g/d for 4 days and in longer studies at intakes of 120 mg/d for 12 weeks. Some studies showed that GABA was associated with a transient and moderate drop in blood pressure (<10% change). No studies were available on effects of GABA during pregnancy and lactation, and no case reports or spontaneous adverse events associated with GABA were found. Chronic administration of GABA to rats and dogs at doses up to 1 g/kg/day showed no signs of toxicity. Because some studies showed that GABA was associated with decreases in blood pressure, it is conceivable that concurrent use of GABA with anti-hypertensive medications could increase risk of hypotension. Caution is advised for pregnant and lactating women since GABA can affect neurotransmitters and the endocrine system, i.e., increases in growth hormone and prolactin levels.

Effects of sustained GABA releasing implants on pancreatic islets in mice.

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that is strongly and selectively synthesized in and secreted from pancreatic beta cells. Exogenously delivered GABA has been proposed to induce beta cell regeneration in type 1 diabetes, but these results have been difficult to replicate and may depend on the specifics of the animal model and drug delivery method used. Here, we developed a GABA-releasing ethylene-vinyl acetate polymer implant for sustained GABA delivery to the intraperitoneal space as an alternative to injected or oral GABA. We explored the effect of the GABA-releasing polymer implantscompared to implanted osmotic pumps loaded with GABA on islet size in non-diabetic, outbred mice. We also attempted to monitor in vivo GABA release using HPLC on blood samples, but these measurements were confounded by high variability within treatment groups and unexpectedly high serum GABA levels in mice receiving GABA-negative implants. The ethylene-vinyl acetate polymer implants became heavily fibrosed with abdominal adhesion tissue, while the osmotic pumps had no macroscopic fibrosis. Histological analysis showed no significant effect of the sustained GABA delivery polymer or osmotic pumps on islet size, alpha cell to beta cell ratio, or the number of Ki67-positive islet cells. The GABA treatment time course was limited to two weeks due to the drug-release window of the polymer, while others reported islet-trophic effects of GABA after 10 to 12 weeks of treatment. In summary, our study is consistent with the concept that exogenous GABA administration does not significantly alter islet cell mass in non-diabetic CD-1 mice in the short-term. However, more data are needed including higher GABA doses and more prolonged treatment regimens for a better comparison with contrasting reports.

Gamma Aminobutyric Acid Increases Absorption of Glycine-Bound Iron in Mice with Iron Deficiency Anemia.

Iron deficiency is a leading cause of anemia. Amino acids are known to promote the absorption of both soluble and insoluble iron. The bioavailability of organic iron is higher than that of inorganic iron. Therefore, the aim of this study was to evaluate the iron absorption of glycine-bound iron (an organic iron) and a combination of glycine-bound iron and gamma aminobutyric acid (GABA) in mice with iron deficiency anemia (IDA). Mice were fed an iron-deficient diet for 3weeks, followed by oral administration of GABA, inorganic iron, glycine-bound iron, or GABA plus glycine-bound iron for 5weeks. Ferritin storage in the spleen was measure by immunohistochemistry (IHC). Iron deposition in the liver and spleen tissues was analyzed using atomic absorption spectrometry. Expression levels of iron absorption-related genes were measured by quantitative real-time polymerase chain reaction (qPCR). Iron absorption was enhanced in the glycine-bound iron-treated group compared with the inorganic iron-treated group. Hemoglobin, serum Fe, ferritin, and liver iron levels did not increase in mice treated with GABA alone. However, mice administered GABA in combination with glycine-bound iron showed higher iron absorption than those administered organic iron alone. Our results indicate that glycine-bound iron in combination with GABA might exert a synergistic effect on iron absorption and bioavailability, suggesting that the addition of GABA to existing iron supplements might increase their effectiveness for treating IDA.

The therapeutic potential of GABA in neuron-glia interactions of cancer-induced bone pain

The development of effective therapeutics for cancer-induced bone pain (CIBP) remains a tremendous challenge owing to its unclear mechanisms. Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). Emerging studies have shown that disinhibition in the spinal cord dorsal horn may account for the development of chronic pain. However, the role of GABA in the development of CIBP remains elusive. In addition, accumulating evidence has shown that neuroglial cells in the peripheral nervous system, especially astrocytes and microglial cells, played an important role in the maintenance of CIBP. In this study, we investigated the expression of GABA and Gamma-aminobutyric acid transporter-1 (GAT-1), a transporter of GABA. Our results demonstrate that GABA was decreased in CIBP rats as expected. However, the expression of glutamic acid decarboxylase (GAD) 65 was up-regulated on day 21 after surgery, while the expression of GAD 67 remained unchanged after surgery. We also found that the expression of GAT-1 was up-regulated mainly in the astrocytes of the spinal cord. Moreover, we evaluated the analgesic effect of exogenous GABA and the GAT-1 inhibitor. Intrathecal administration of exogenous GABA and NO-711 (a GAT-1 selective inhibitor) significantly reversed CIBP-induced mechanical allodynia in a dose-dependent manner. These results firstly show that neuron-glia interactions, especially on the GABAergic pathway, contribute to the development of CIBP. In conclusion, exogenous GABA and GAT-1 inhibitor might be alternative therapeutic strategies for the treatment of CIBP.

337-LB: Combined Oral Administration of GABA and GLP-1 Promotes Human ß-Cell Proliferation and Reduces Apoptosis

Gamma-aminobutyric acid (GABA) and glucagon-like peptide-1 (GLP-1) improve rodent β cell survival and function. In human β cells, GABA exerts stimulatory effects on proliferation and anti-apoptotic effects, whereas GLP-1-based drugs have only limited effects on proliferation. We previously demonstrated that GABA and sitagliptin, a dipeptidyl peptidase-4 inhibitor which increases endogenous GLP-1 levels, mediated a synergistic β cell protective effect in mice islets. However, it remains unclear whether this combination has similar effects on human β cells. To address this question, we transplanted a suboptimal mass of human islets into immunodeficient NOD-scid-gamma mice with streptozotocin-induced diabetes, and then treated them with GABA, sitagliptin, or both. The oral administration of either GABA or sitagliptin ameliorated blood glucose levels, increased transplanted human β cell mass and plasma human insulin levels. However, combined administration of the drugs generated significantly superior results in all these responses, as compared to monotherapy. Proliferation and/or regeneration, improved by the combination, were demonstrated by increased Ki67+, pancreatic and duodenal homeobox-1 (PDX-1+), or Nkx6.1+ β cell numbers. Protection against apoptosis was also significantly improved by the combined therapy. GABA and GLP-1 in combination notably increased Akt phosphorylation and insulin secretion, as well as the expression of sirtuin-1 and α-Klotho, both of which have been reported to have protective effects on β-cells. Our study indicates that combined use of GABA and sitagliptin produced greater therapeutic benefits, which was likely due to an enhancement of β cell proliferation and a decrease of apoptosis. Disclosure W. Liu: None. T. Jin: None. Q. Wang: None. Funding National Natural Science Foundation of China (81570518, 81630020); JDRF (2-SRA-2017-64-G-R to Q.W., T.J.), (2-SRA-2015-64 to Q.W., T.J.); Canadian Diabetes Association (OG-3-13-4066 to Q.W.)

Intervention mechanism of repeated oral GABA administration on anxiety-like behaviors induced by emotional stress in rats

The purpose of this study was to investigate the effects and mechanism of repeated oral administration of gamma-aminobutyric acid (GABA) on anxiety-like behaviors induced by emotional stress. Male Sprague-Dawley rats were randomly divided into five groups (8 rats each): control, emotional stress model, three emotional stress + GABA-treated groups (0.5, 1, 2 mg/kg). The rats were given empty water bottles after the training of drinking water to induce emotional stress. Each group was treated with saline or different doses of GABA respectively for 21 consecutive days. Then open field and elevated plus maze were used to assess anxiety-like behaviors. Both frontal cortex and plasma NO metabolites nitrate and nitrite (NOx) levels were determined spectrophotometrically. Results showed that oral administration of GABA significantly reversed the stress-induced anxiety-like negative responses dose-dependently. The frontal cortex NOx levels were lower in stressed rats than in control group (P < 0.05), but higher in 2 mg/kg GABA-treated group than stress model group (P < 0.05). On the other hand, NOx levels in plasma showed a gradual decline trend. Collectively, these results suggest that short repeated oral administration of GABA has an anxiolytic-like effect possibly via preventing NO reduction caused by stress and improving availability of NO in the frontal cortex.

Gamma-Aminobutyric Acid (GABA) Attenuates Ischemia Reperfusion-Induced Alterations in Intestinal Immunity.

The aims of this study were to determine the effects of gamma-aminobutyric acid (GABA) on immunoglobulin A (IgA) secretion from Peyer's patch (PP) cells; to assess rat alpha-defensin-5 (RD-5) expression in the rat small intestine; and to determine the effect of GABA on intestinal ischemia reperfusion (I/R) injury-induced intestinal innate immunity. We found that GABA caused an increase in IgA secretion in the presence and absence of lipopolysaccharide (LPS). Moreover, GABA also significantly increased the mRNA levels of RD-5 and superoxide dismutase (Sod) 1, 3. Intestinal I/R was induced by a 30-min occlusion of the superior mesenteric artery followed by a reperfusion for 60-min. This led to a significant decrease in IgA secretion, and mRNA levels of RD-5 and Sod 1-3 in the ileum. On the other hand, administration of GABA before I/R induction had a significant protective effect against oxidative injury and attenuated the effects on intestinal immunity.

Gamma-aminobutyric acid ameliorates gamma rays-induced oxidative stress in the small intestine of rats

BackgroundThe current study aimed to evaluate the role of gamma-amino butyric acid (GABA) in modulating histopathological and biochemical disturbances in the rat’s small intestine following gamma radiation exposure.ResultsThe results showed that whole body gamma irradiation (6 Gy) of rats induced mucosal damage, hemorrhage, increased cellularity of the lamina propria layer with areas of complete ulcerations. Histopathological changes were associated with a significant increase in malondialdehyde (MDA) and advanced oxidation protein products (AOPPs). In parallel, a significant decrease in catalase (CAT) and glutathione peroxidase (GSH-Px) activities was demonstrated. Administration of GABA (200 mg/kg body weight GABA daily via gastric gavage for three consecutive weeks) after irradiation of rats has significantly improved the oxidant/antioxidant status which was associated with regeneration of the small intestinal cell structure.ConclusionGastric administration of GABA was found to offer an advantageous treatment against gamma irradiation-induced small intestine oxidative stress in rats, probably by utilizing ameliorative effects via its antioxidant and free radical-scavenging activities. Its mechanisms need to be further investigated.

Acute inflammation reveals GABAA receptor-mediated nociception in mouse dorsal root ganglion neurons via PGE2 receptor 4 signaling.

Gamma‐aminobutyric acid (GABA) depolarizes dorsal root ganglia (DRG) primary afferent neurons through activation of Cl− permeable GABAA receptors but the physiologic role of GABAA receptors in the peripheral terminals of DRG neurons remains unclear. In this study, we investigated the role of peripheral GABAA receptors in nociception using a mouse model of acute inflammation. In vivo, peripheral administration of the selective GABAA receptor agonist muscimol evoked spontaneous licking behavior, as well as spinal wide dynamic range (WDR) neuron firing, after pre‐conditioning with formalin but had no effect in saline‐treated mice. GABAA receptor‐mediated pain behavior after acute formalin treatment was abolished by the GABAA receptor blocker picrotoxin and cyclooxygenase inhibitor indomethacin. In addition, treatment with prostaglandin E2 (PGE 2) was sufficient to reveal muscimol‐induced licking behavior. In vitro, GABA induced sub‐threshold depolarization in DRG neurons through GABAA receptor activation. Both formalin and PGE 2 potentiated GABA‐induced Ca2+ transients and membrane depolarization in capsaicin‐sensitive nociceptive DRG neurons; these effects were blocked by the prostaglandin E2 receptor 4 (EP4) antagonist AH23848 (10 μmol/L). Furthermore, potentiation of GABA responses by PGE 2 was prevented by the selective Nav1.8 antagonist A887826 (100 nmol/L). Although the function of the Na+‐K+‐2Cl‐ co‐transporter NKCC1 was required to maintain the Cl‐ ion gradient in isolated DRG neurons, NKCC1 was not required for GABAA receptor‐mediated nociceptive behavior after acute inflammation. Taken together, these results demonstrate that GABAA receptors may contribute to the excitation of peripheral sensory neurons in inflammation through a combined effect involving PGE 2‐EP4 signaling and Na+ channel sensitization.

Sedative-like effect of intraperitoneal GABA administration in the open field test

Gamma-Amino Butyric Acid (GABA) is the main inhibitor neurotransmitter of the Central Nervous System (CNS). Its peripheral administration has been matter of discussion. On the one hand, it has been reported that it does not cross the Blood-Brain Barrier (BBB), and, on the other hand, it has been associated with multiple therapeutic regimens and supplements by peripheral administration. The aim of the present study is to elucidate the possibility of a central sedative effect when administered peripherally. An experimental cohort of 90-day-old Holtzman male rats weighing 240-270 g was used. It was divided into 2 groups: saline-controls (n = 9) and GABA treated rats (12.5 mg/kg, n = 9). Both groups were intraperitoneally injected. The motor behavioral patterns displayed in the Opto Varimex (OVM) were studied. Vertical, horizontal, ambulatory and non-ambulatory movements and the number of movements were recorded in an automated way. Horizontal movements constitute the integration of ambulatory and non-ambulatory movements. Student t test was used comparing groups. In this experiment, there were non-significant downward trends in vertical, ambulatory, non-ambulatory and number of movements. Ambulatory and non-ambulatory tendencies acquired significance when treated together as horizontal movements (p &lt; 0.05). We may conclude that peripheral administration of GABA produced a decrease of the horizontal movements in the open field test. It may be interpreted as a sedative effect, suggesting a passage of GABA through BBB, with central effects. However, there are several alternative possibilities to explain present findings. Other experiments will elucidate the implications or scope of the present findings.

Neurotransmitters as food supplements: the effects of GABA on brain and behavior.

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood–brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA.

γ-Aminobutyric acid (GABA) administration improves action selection processes: a randomised controlled trial.

In order to accomplish a task goal, real-life environments require us to develop different action control strategies in order to rapidly react to fast-moving visual and auditory stimuli. When engaging in complex scenarios, it is essential to prioritise and cascade different actions. Recent studies have pointed to an important role of the gamma-aminobutyric acid (GABA)-ergic system in the neuromodulation of action cascading. In this study we assessed the specific causal role of the GABA-ergic system in modulating the efficiency of action cascading by administering 800 mg of synthetic GABA or 800 mg oral of microcrystalline cellulose (placebo). In a double-blind, randomised, between-group design, 30 healthy adults performed a stop-change paradigm. Results showed that the administration of GABA, compared to placebo, increased action selection when an interruption (stop) and a change towards an alternative response were required simultaneously, and when such a change had to occur after the completion of the stop process. These findings, involving the systemic administration of synthetic GABA, provide the first evidence for a possible causal role of the GABA-ergic system in modulating performance in action cascading.