Dietary Gamma-aminobutyric Acid Research Articles

Effect of milling and temperature of germination on nutrients, bioactive compounds and pasting properties of FARO 44, FARO 57 and NERICA-8 brown rice cultivars

Germinated brown rice (GBR) was produced from FARO 44, FARO 57 and NERICA-8 cultivars by de-husking the paddies and germinating them at 30°C and 40°C for 24 h. Bioactive compounds, nutritional composition and pasting properties were analysed and compared to that of non-germinated parboiled milled rice (MR) and non-germinated brown rice (BR) from the same cultivars. The results showed that germination improved the bioactive compounds and nutrients. Protein, ash, total dietary fibre, calcium, iron, zinc, selenium, vitamins B2 and E, DPPH and gamma amino butyric acid (GABA) contents of BR increased significantly (p<0.05) in GBR but decreased significantly in MR. Total carbohydrates and total starch contents of BR decreased significantly in GBR. The increase in protein, total dietary fibre, vitamin E, DPPH and GABA contents of GBR were by 6.28-45.31%, 3.09-15.80%, 113.68-153.85%, 38.00-410.00% and 159.46-288.11%, respectively depending on the cultivar and the germination temperature. Increase in germination temperature from 30°C to 40°C resulted in significant increase in iron, zinc, GABA, total phelolic, total flavonoid contents, and all the pasting viscosities but it decreased the magnesium, protein and amino acid contents significantly. FARO 57 possessed improved bioactive compounds and nutrients than the other rice cultivars.

Effects of dietary supplementation of different levels of gamma-aminobutyric acid on reproductive performance, glucose intolerance, and placental development of gilts.

This study aimed to investigate the effects of dietary gamma-aminobutyric acid (GABA) supplementation on reproductive performance, glucose intolerance, and placental development of gilts during mid-late gestation. Based on the principle of backfat thickness consistency, 124 gilts at 65 d of gestation were assigned to three dietary groups: CON (basic diet, n = 41), LGABA (basic diet supplemented with 0.03% GABA, n = 42), and HGABA (basic diet supplemented with 0.06% GABA, n = 41). The litter performance, glucose tolerance, placental angiogenesis, and nutrients transporters were assessed. The LGABA group improved piglet vitality and placental efficiency and decreased area under the curve of glucose tolerance test compared to the CON group (P < 0.05). Meanwhile, the LGABA group enhanced placental vessel density, platelet endothelial cell adhesion molecule-1 levels and gene expression of fibroblast growth factor 18 (P < 0.05). Furthermore, LGABA showed an uptrend in glucose transporter type 1 mRNA level (P = 0.09). Taken together, this study revealed that the dietary supplementation of 0.03% GABA can improve piglet vitality, glucose intolerance, and placental development of gilts.

Effect of dietary gamma aminobutyric acid (GABA) modulated the growth performance, immune and antioxidant capacity, digestive enzymes, intestinal histology and gene expression of Nile tilapia (Oreochromisniloticus)

Dietary GABA plays an important role in a variety of physiological functions in animals, but this has been rarely reported in fish. This study investigated the effects of dietary supplementation with GABA on growth, serum antioxidant indicators, digestive enzyme activities, intestinal morphology, and the gene expression of Nile tilapia. Diets containing three different GABA concentrations, 0 (control), 200 mg/kg (GABA200), and 500 mg/kg (GABA500), were fed to Nile tilapia (6.97 ± 0.34 g) for 56 days. The present study found that increasing dietary GABA content could increase the fish growth performance including final body weight, weight gain, specific growth rate, average daily gain, protein efficiency ratio, and feed efficiency compared to the control diet. Interestingly, the feed conversion ratio was improved by dietary GABA supplementation. The antioxidant enzyme activities against ammonia stress of fish fed the GABA diets were significantly higher than the corresponding control group throughout the 96-h ammonia exposure. Moreover, significant increases in digestive enzyme activities including protease, amylase and lipase were found in fish fed the GABA diets. Intestinal morphology analysis revealed increased heights and widths of intestinal villi as well as thickness of the intestinal muscularis in fish fed the GABA diets compared to the control diet. The supplementation of diets with GABA significantly increased the expression level of immune- and growth-related genes. The above results indicate that dietary GABA can modulate the growth, improve their immune response and antioxidant status, gut health and morphology and gene expression of Nile tilapia. Therefore, GABA is a promising feed additive for Nile tilapia aquaculture.

Interactive Effect of Dietary Gamma-Aminobutyric Acid (GABA) and Water Temperature on Growth Performance, Blood Plasma Indices, Heat Shock Proteins and GABAergic Gene Expression in Juvenile Olive Flounder Paralichthys olivaceus.

Gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the central nervous system of living organisms and has the ability to reduce the magnitude of stress in humans and animals. In this study, we evaluated the supplemental effects of GABA on normal and high water temperature based on growth, blood plasma composition as well as heat shock proteins and GABA-related gene expression in juvenile olive flounder. For this, a 2 × 2 factorial design of experiment was employed to investigate the dietary effects of GABA at 0 mg/kg of diet (GABA0 diet) and 200 mg/kg of diet (GABA200 diet) in water temperatures of 20 ± 1 °C (normal temperature) and 27 ± 1 °C (high temperature) for 28 days. A total of 180 fish with an average initial weight of 40.1 ± 0.4 g (mean ± SD) were distributed into 12 tanks, of which, each tank contained 15 fish based on the 4 dietary treatment groups in triplicate. At the end of the feeding trial, the results demonstrated that both temperature and GABA had significant effects on the growth performance of the fish. However, fish fed the GABA200 diet had a significantly higher final body weight, weight gain and specific growth rate as well as a significantly lower feed conversion ratio than the fish fed the GABA0 diet at the high water temperature. A significant interactive effect of water temperature and GABA was observed on the growth performance of olive flounder based on the two-way analysis of variance. The plasma GABA levels in fish were increased in a dose-dependent manner at normal or high water temperatures, whereas cortisol and glucose levels were decreased in fish fed GABA-supplemented diets under temperature stress. The GABA-related mRNA expression in the brains of the fish such as GABA type A receptor-associated protein (Gabarap), GABA type B receptor 1 (Gabbr1) and glutamate decarboxylase 1 (Gad1) were not significantly affected by GABA-supplemented diets under normal or temperature stressed conditions. On the other hand, the mRNA expression of heat shock proteins (hsp) in the livers of the fish, such as hsp70 and hsp90, were unchanged in fish fed the GABA diets compared to the control diet at the high water temperature. Collectively, the present study showed that dietary supplementation with GABA could enhance growth performance, and improve the feed utilization, plasma biochemical parameters and heat shock proteins and GABA-related gene expression under the stress of high water temperatures in juvenile olive flounder.

Comprehensive transcriptional and metabolomic analysis reveals the neuroprotective mechanism of dietary gamma-aminobutyric acid response to hypoxic stress in the Chinese mitten crab (Eriocheir sinensis)

Hypoxia is one of the serious stress challenges that aquatic animals face throughout their life. Our previous study found that hypoxia stress could induce neural excitotoxicity and neuronal apoptosis in Eriocheir sinensis, and observed that gamma-aminobutyric acid (GABA) has a positive neuroprotective effect on juvenile crabs under hypoxia. To reveal the neuroprotective pathway and metabolic regulatory mechanism of GABA in E. sinensis exposed to hypoxia stress, an 8-week feeding trial and acute hypoxia challenge were performed. Subsequently, we performed a comprehensive transcriptomic and metabolomic analysis of the thoracic ganglia of juvenile crabs. Differential genes and differential metabolites were co-annotated to 11 KEGG pathways, and further significant analysis showed that only the sphingolipid signaling pathway and the arachidonic acid metabolism pathway were significantly enriched. In the sphingolipid signaling pathway, GABA treatment significantly increased long-chain ceramide content in thoracic ganglia, which exerted neuroprotective effects by activating downstream signals to inhibit hypoxia-induced apoptosis. Moreover, in the arachidonic acid metabolism pathway, GABA could increase the content of neuroprotective active substances and reduce the content of harmful metabolites by regulating the metabolism of arachidonic acid for inflammatory regulation and neuroprotection. Furthermore, the decrease of glucose and lactate levels in the hemolymph suggests the positive role of GABA in metabolic regulation. This study reveals the neuroprotective pathways and possible mechanisms of GABA in juvenile E. sinensis exposed to hypoxia stress and inspires the discovery of new targets for improving hypoxia tolerance in aquatic animals.

Gamma-amino butyric acid (GABA) supplementation alleviates dexamethasone treatment-induced oxidative stress and inflammation response in broiler chickens

This experiment was conducted to investigate the effect of Gamma-amino butyric acid (GABA) on growth performance, serum and liver antioxidant status, inflammation response and hematological changes, in male broiler chickens under experimentally induced stress via in-feed dexamethasone (DEX). A total of 300 male chicks (Ross 308) on day 7 after hatching, were randomly selected into four groups which were positive control group (PC, without any treatment), negative control (NC, with 1 mg/kg DEX), a third group received 1 mg/kg DEX and 100 mg/kg GABA (DG +) and the last one was (DG ++) which received 1 mg/kg DEX and 200 mg/kg GABA. Each group has five replicates (15 birds/replicate). Dietary GABA modulated DEX-induced adverse effects on body weight, feed intake, and feed conversion ratio. The DEX-induced effect of serum levels of IL-6 and IL-10 was reduced by dietary GABA supplementation. The activity of serum and liver superoxide dismutase, catalase, glutathione peroxidase were enhanced and malondialdehyde was reduced by GABA supplementation. The serum levels of total cholesterol & triglyceride were higher while low-density lipoprotein & high-density lipoprotein were lower in GABA groups than NC group. GABA supplementation also significantly decreased the heterophil, heterophil/lymphocyte ratio and elevated the activities of aspartate aminotransferase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) than NC group. In conclusion, dietary GABA supplementation can alleviate DEX stress-induced oxidative stress and inflammation response.

Effect of dietary gamma-aminobutyric acid on growth performance, haemato-immunological responses, antioxidant enzymes activity, ghrelin and IGF-I expression of Labeo rohita (Hamilton, 1822) fingerlings

Effect of dietary gamma-aminobutyric acid on growth performance, haemato-immunological responses, antioxidant enzymes activity, ghrelin and IGF-I expression of Labeo rohita (Hamilton, 1822) fingerlings

Gamma-aminobutyric acid enhances hypoxia tolerance of juvenile Chinese mitten crab (Eriocheir sinensis) by regulating respiratory metabolism and alleviating neural excitotoxicity

With climate change and intensive aquaculture development, environmental hypoxia in aquaculture water has become a common challenge for many aquatic species. Therefore, it is crucial to improve the hypoxic tolerance of animals through nutritional strategies. This study explored the positive role of dietary gamma-aminobutyric acid (GABA) supplementation in enhancing hypoxia tolerance of juvenile Eriocheir sinensis through respiratory regulation and alleviation of hypoxia-induced neural excitotoxicity. Acute hypoxia stress significantly up-regulated the mRNA expression level of hypoxia-inducible factor 1α, oxygen consumption rate and anaerobic respiratory metabolism-related enzyme activities. On the other hand, aerobic respiratory metabolism-related enzyme activities were significantly decreased. However, dietary GABA supplementation remodeled the respiratory metabolism pattern of juvenile crabs exposed to hypoxia stress. In addition, acute hypoxic stress significantly increased the contents of free glutamate and GABA in the nervous tissue. The expression levels of N-Methyl-d-aspartate-related receptor genes and calcium-dependent degradation enzyme-related genes were significantly up-regulated. Similarly, neuronal apoptosis rates, expression levels of apoptosis-related genes, and vesicular glutamate transporter genes were also significantly increased. The high-affinity neuronal glutamate transporter decreased significantly in the crabs exposed to hypoxia stress. However, dietary GABA supplementation could effectively prevent acute hypoxia stress-induced neural excitotoxicity. Furthermore, dietary GABA could significantly improve the redox status in vivo exposed to hypoxia stress. In conclusion, acute hypoxia stress can affect respiratory metabolism and redox state and induce neural excitotoxicity in juvenile E. sinensis. GABA supplementation could improve hypoxia tolerance through multiple physiological regulation pathways.

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.

Dietary gamma-aminobutyric acid (GABA) improves non-specific immunity and alleviates lipopolysaccharide (LPS)-induced immune overresponse in juvenile Chinese mitten crab (Eriocheir sinensis)

Inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is an immunomodulator to inhibit immune-mediated pro-inflammatory response and has been used to treat various immune-related diseases in mammals. However, the immunoregulatory effect of GABA in crustaceans has not been reported. This study evaluates the regulatory effect of dietary GABA supplementation on the innate immune status and immunoregulatory potential in lipopolysaccharide (LPS)-induced immune response in juvenile Eriocheir sinensis. Juvenile crabs were fed with six diets supplemented with graded GABA levels (0, 40, 80, 160, 320 and 640 mg/kg dry matter) for 8 weeks and then 24 h LPS challenge test was carried out. The results showed that dietary GABA supplementation significantly decreased mortality at 4 and 8 weeks. Moreover, the hemocyanin content, acid phosphatase, and alkaline phosphatase activities significantly increased in the crabs fed GABA supplementation compared with the control. On the contrary, the alanine aminotransferase and alanine aminotransferase activities in serum decreased significantly in the GABA supplementation groups compared with the control. Similarly, superoxide dismutase activity, glutathione content, and the transcriptional expression of the antioxidant-related genes and immune-related genes were significantly higher in the GABA supplementation groups than in the control. In addition, the mRNA expressions of anti-lipopolysaccharide factors (ALF 1, ALF 2, ALF 3) and inflammatory signaling pathways related genes (TLR, Myd88, Relish, LITAF, P38-MAPK, ADAM17) were significantly up-regulated in LPS stimulation groups compared with PBS treatment. Meanwhile, pro-apoptosis-related genes' mRNA expressions were significantly up-regulated, and anti-apoptosis-related genes were significantly down-regulated under LPS stimulation compared with PBS treatment. However, GABA pretreatment effectively alleviated LPS-induced immune overresponse and apoptosis. Therefore, this study demonstrates that dietary GABA supplementation could be used as an immunomodulator to improve the non-specific immunity and antioxidant capacity and alleviate the immune-mediated immune overresponse of juvenile E. sinensis.

Dietary gamma-aminobutyric acid supplementation does not mitigate stress responses in weaner pigs given adrenocorticotropic hormone and experimentally infected with enterotoxigenic Escherichia coli

Gamma-aminobutyric acid (GABA) is a non-protein amino acid, a major inhibitory neurotransmitter in the central nervous system that stimulates feed intake and inhibits the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesised that: (1) GABA supplementation in the diet would reduce markers of the stress response in weaned pigs injected with adrenocorticotropic hormone (ACTH) and inoculated with enterotoxigenic Escherichia coli (ETEC); and (2) this reduction in stress responses would improve performance after weaning. A total of 96 newly-weaned male pigs (Large White x Landrace) were stratified into a two by four factorial arrangement with respective factors being (i) with/without ACTH injection and ETEC infection (challenge versus non-challenge) and (ii) four dietary GABA levels (0, 60, 80, 100 mg/kg). On days 8 and 9 after weaning, piglets were orally inoculated with ETEC (0.8 ml via two gelatinized capsules; serotype O149; F4) as well as being given 5 IU ACTH intramuscularly (IM), which occurred an hour before ETEC inoculation. Pigs in the non-challenged group were given IM 0.2 mL of sterile saline and sham infected with two capsules of PBS. Faecal consistency scores were recorded daily, pigs and feed were weighed weekly to determine performance and blood samples were collected at days 6, 9 and 14. GABA supplementation did not reduce plasma cortisol. However challenged pigs had higher levels compared to the non-challenge group at day 9 (P = 0.001). Performance was not influenced by GABA supplementation (P > 0.05). Between days 8–14, 54.3% of pigs in the challenge group developed diarrhoea compared to 5.6% in the non-challenged group (P = 0.001). These data indicate that eliciting both an ETEC infection challenge and an acute stress response after weaning initiated an endocrine stress response. The use of GABA in feed did not reduce this stress response, reduce diarrhoea or improve production performance.

Dietary gamma-aminobutyric acid (GABA) supplementation increases food intake, influences the expression of feeding-related genes and improves digestion and growth of Chinese mitten crab (Eriocheir sinensis)

Animal growth performance is determined by food intake, digestion and nutrient absorption and the complex central and peripheral nerves may regulate the quantity of food intake. This study evaluates the effects of gamma-aminobutyric acid (GABA) supplements in purified diets on the growth performance, food intake and digestive ability of juvenile Chinese mitten crab Eriocheir sinensis, and the possible mechanism of neuromodulation. A total of 1200 juvenile crabs (0.77 ± 0.02 g) were fed with six diets supplemented with graded GABA levels (0, 40, 80, 160, 320 and 640 mg/kg dry matter) for 8 weeks. Each diet group had five replicates, and each replicate had 40 crabs in a tank (100 × 80 × 60 cm). The weight gain, specific growth rate, molting frequency, and the activities of digestion (α-amylase, trypsin and lipase) and absorption (Na+-K+-ATPase and γ- glutamyl transferase) enzymes were significantly increased by moderate dietary GABA supplementation compared with the 0 mg/kg GABA supplementation group. Furthermore, the food intake of juvenile E. sinensis was significantly increased with moderate dietary GABA supplementation compared with the 0 mg/kg GABA supplementation group. The qRT-PCR results showed that the expression of the orexigenic neural signal-related genes was significantly up-regulated, and the anorexigenic neural signal-related genes were significantly down-regulated in the cranial ganglia, thoracic ganglia and intestine tissues. Meanwhile, the expressions of the main genes involved in taste modulation and reward regulation were significantly up-regulated, whereas the expression of genes related to punishment regulation was significantly down-regulated in cranial ganglia and thoracic ganglia. Two-slope broken-line regression analysis of specific growth rate and weight gain against the dietary GABA levels showed that dietary GABA at the optimal dietary level was 84–89 mg/kg, and this level can improve growth performance, food intake, digestion and absorption in juvenile E. sinensis. GABA might act as an orexigenic neural signal or work with other appetite-related nerve signals to promote food intake by participating in regulating the satiety circuit and the reward circuit.

Role of dietary gamma-aminobutyric acid in broiler chickens raised under high stocking density.

The present study was conducted to evaluate the effects of dietary gamma-aminobutyric acid (GABA) in broiler chickens raised in high stocking density (HSD) on performance and physiological responses. A total of 900 male broiler chicks (Ross 308) at 1 d old were assigned in a 2 × 2 factorial arrangement to 4 treatments (10 replicates per treatment) with stocking density, 7.5 birds/m2 (low stocking density; LSD) or 15 birds/m2 (HSD), and dietary GABA, 0 or 100 mg/kg. Chickens raised in HSD exhibited a decrease in body weight gain in all phases (P < 0.05) and feed intake in starter and whole phases (P < 0.01), and an increase in feed conversion ratio in the finisher phase (P < 0.01) compared with LSD-raised chickens. However, dietary GABA did not affect growth performance nor interacted with stocking density on production variables. The HSD vs. LSD increased relative liver weight on d 35 whereas dietary GABA increased relative liver weight and decreased relative bursa weight on d 21. Both stocking density and dietary GABA affected yield and quality of breast and leg muscles. Dietary GABA increased (P < 0.05) width of tibia on d 35 and interacted (P = 0.054) with stocking density on breaking stocking density on d 35. The HSD vs. LSD group lowered (P < 0.05) feather coverage scores. Significant interaction between stocking density and GABA on surface temperature of shank on d 21 was noted (P = 0.024). Dietary GABA exhibited an opposite effect on the concentrations of cecal short-chain fatty acids depending on stocking density leading to a moderate to significant interaction. Stocking density decreased alpha-1-acid glycoprotein whereas dietary GABA decreased heterophil-to-lymphocyte ratio and corticosterone in blood or serum samples. Serum biochemical parameters were altered by stocking density or dietary GABA. It is concluded that dietary GABA alleviated stress indices including corticosterone and heterophil-to-lymphocyte ratio, but failed to reverse stocking density-induced growth depression.

Effects of dietary gamma-aminobutyric acid supplementation on amino acid profile, intestinal immunity, and microbiota in ETEC-challenged piglets.

Enterotoxigenic Escherichia coli (ETEC) infection is the most common cause of diarrhea in piglets, and ETEC could increase intestinal gamma-aminobutyric acid (GABA)-producing bacteria to affectintestinal immunity. However, the effect of GABA on ETEC-infected piglets is still unclear. This study aims at investigating the impact of dietary GABA supplementation on the growth performance, diarrhea, intestinal morphology, serum amino acid profile, intestinal immunity, and microbiota in the ETEC-infected piglet model. Eighteen piglets were randomly divided into two groups, in which the piglets were fed with a basal diet with 20 mg kg-1 GABA supplementation or not. The experiment lasted for three weeks, and the piglets were challenged with ETEC K88 on the fifteenth day. The results showed that dietary GABA reduced the feed conversion ratio, promoted the kidney organ index but did not affect the diarrheal score and small intestinal morphology in ETEC-challenged piglets. Ileal mucosal amino acids (such as carnosine and anserine) and serum amino acids (including threonine and GABA) were increased upon GABA supplementation. GABA enhanced ileal gene expression of TNF-α, IFN-γ, pIgR, and MUC2, while inhibited the ileal expression of IL-18 in ETEC-challenged piglets. GABA supplementation also highly regulated the intestinal microbiota by promoting community richness and diversity and reducing the abundance of the dominant microbial population of the ileal microbiota. Collectively, GABA improves growth performance, regulates the serum amino acid profile, intestinal immunity, and gut microbiota in ETEC-challenged piglets. This study is a fine attempt to reveal the function of GABA in ETEC-infected piglets. It would contribute to the understanding of the roles of exogenous nutrition on the host response to ETEC infection.

Dietary GABA enhances hypoxia tolerance of a bottom-dwelling carp, Cirrhinus mrigala by modulating HIF-1α, thyroid hormones and metabolic responses.

The Indian major carp, mrigal (Cirrhinus mrigala), is a bottom-dwelling fish that can survive hypoxic episodes in its natural environment. We hypothesise that it can better survive hypoxic conditions by altering metabolic responses through GABA (Gamma-aminobutyric acid) supplementation. In the first experiment, the hypoxia tolerance time of the fishes was evaluated under extreme anoxic conditions after feeding with GABA, which showed that GABA had improved survival time under hypoxia. To study the response of dietary GABA in hypoxia-exposed fish, the branchial HIF-1α expression levels, serum thyroid hormone levels and hepatic metabolic responses were assessed in the subsequent experiment. The treatment groups were fed for 60 days with experimental diets containing 4 levels of GABA (0.00% G, 0.50% G, 0.75% G and 1.0%G) and were subjected to 72-h hypoxia exposure (0.5 ± 0.02 mg L-1 dissolved oxygen (DO)) whereas a control group was maintained under normoxic conditions (6.0 ± 0.21 mg L-1 DO). The five treatment groups with three replicates were C0 (0% G + normoxia), H0 (0% G + hypoxia), H0.5 (0.50% G + hypoxia), H0.75 (0.75% G + hypoxia) and H1.0 (1.00% G + hypoxia). The results indicated that GABA supplementation triggered downregulation of HIF 1 alpha expression. When compared with the control group, decreased thyroxine (T4) and triiodothyronine (T3) levels were observed in the GABA-fed hypoxic groups. However, TSH (thyroid stimulating hormone) level remained unchanged in all the treatments. The LDH (lactate dehydrogenase) level in hypoxia-exposed groups was decreased by GABA supplementation. Our study demonstrated that GABA supplementation restores acute hypoxia-induced HIF-1α expression, thyroid hormone levels and LDH activities. On the other hand, it enhanced the citrate synthase (CS) activities at 0.5-1.00%, which showed a sharp decline in hypoxia. Hypoxia caused increase in the serum metabolites such as glucose, lactate, cholesterol and triglycerides. However, GABA supplementation was partially effective in reducing glucose and lactate level while triglycerides and cholesterol values remained unchanged. Overall, our results suggested a potential role of GABA in suppressing metabolism during hypoxia exposure, which can increase the chances of survival of the species Cirrhinus mrigala during hypoxia.

Effects of dietary gamma-aminobutyric acid in juvenile Nile tilapia, Orechromis niloticus

Abstracts The present study was conducted to evaluate the effects of different dietary gamma-aminobutyric acid (GABA) levels in Nile tilapia, Orechromis niloticus. Six groups of fish averaging 3.03 ± 0.07 g (mean ± SD) were randomly distributed in 18 rectangular tanks in triplicates. A basal diet without GABA supplementation was used as a control (CON), and the other five diets were prepared by adding 75 mg GABA (GABA144), 75 mg GABA +50 mg heat-killed Lactobacillus paracasei (GABA189L), 150 mg GABA (GABA197), 150 mg GABA +50 mg heat-killed Lactobacillus paracasei (GABA242L), and 600 mg GABA (GABA507) per kg of diet. Actual GABA compositions for CON, GABA144, GABA189L, GABA197, GABA242L and GABA507 diets were 96, 144, 189, 197, 242 and 507 mg kg−1, respectively. After 8 weeks of experiment, weight gain, specific growth rate, feed efficiency and protein efficiency ratio of fish fed GABA189L were significantly higher than those of fish fed CON and GABA5.7 diets (P

Effects of dietary gamma-aminobutyric acid supplementation on the intestinal functions in weaning piglets.

This study aims to investigate the effects of dietary gamma-aminobutyric acid (GABA) supplementation on the growth performance, intestinal immunity, intestinal GABAergic system, amino acid profiles and gut microflora of the weaned piglets. Totally sixteen healthy piglets were randomly assigned into two groups to be fed with the basal diet (Con group) or the basal diet with GABA (20 mg kg-1) supplementation. Body weights and feed intakes were monitored weekly. Piglets were sacrificed after 3 weeks of GABA supplementation to collect the blood, ileum, ileal mucosa and luminal content. Immune-associated factors, GABAergic system, amino acid profiles, and microbiota in the ileum and serum amino acid profiles were explored. The results showed that GABA supplementation improved the growth performance and modulated the intestinal immunity with inhibiting the gene expressions of IL-22, proinflammatory cytokines (IL-1 and IL-18), and Muc1, but promoted the expressions of anti-inflammatory cytokines (IFN-γ, IL-4, and IL-10), TLR6 and MyD88. GABA regulated a few components of the intestinal GABAergic system, increased the levels of most amino acids in the ileal mucosa but reduced the serum amino acid profiles. GABA regulated the population and diversity of intestinal microbiota, such as the abundances of the dominant microbial populations, the community richness, and diversity of the ileal microbiota. In conclusion, GABA supplementation modulated the intestinal functions, including intestinal immunity, intestinal amino acid profiles and gut microbiota, and the results can be helpful for understanding the functions of GABA in the intestine.

Effects of dietary gamma-aminobutyric acid on egg production, egg quality, and blood profiles in layer hens

Hy-line brown commercial layers (32 weeks old) were used to investigate the effects of GABA (gamma-aminobutyric acid) derived from E. coli strains on productivity, egg quality, and blood profile. In total, 288 birds (1946 ± 0.5 g) were fed four different levels of GABA (0, 25, 50, and 100 ppm), in a basal diet based on corn-soybean meal, for five weeks. Egg production, egg weight, and egg mass during weeks 32 to 36 showed sig - nificant improvement, as dietary GABA was increased from 0 to 100 ppm (linear, P < 0.05). Additionally, GABA supplementation was associated with increased eggshell breaking strength and albumen height (quadratic and linear, P < 0.05). Blood variables, such as white blood cells, red blood cells, lymphocyte, cortisol, epinephrine, and norepinephrine concentrations, were not influenced by addition of GABA to the diet; however, the haptoglobin concentration decreased significantly (linearly) and the IgG concentration increased (quadratically) in the GABA- fed groups (P < 0.05). These results suggest that diets containing GABA may beneficially affect productivity, egg quality, serum haptoglobin, and IgG concentrations in layers.

Effect of GABA Tea on Quality Characteristics of Chiffon Cake

ABSTRACTThe effects of gamma aminobutyric acid (GABA) tea on the quality characteristics of chiffon cakes were studied. The viscosity and specific gravity in cake batter, and total dietary fiber, GABA, catechin, epicatechin, gallocatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate contents, hardness, and crumb a value of baked cakes increased with increasing GABA tea level; whereas, the pH and moisture in cake batter, and the moisture, water activity, cake volume, crust L, a, b and crumb L, b values of baked cakes showed a reverse trend. As derived from descriptive analysis, the crust and crumb of cakes became darker, drier, and had a tougher texture as GABA tea level increased and cake flour decreased, but the GABA cake had a pleasant tea flavor. The degree of overall liking of cakes decreased with increasing GABA tea level. However, chiffon cake formulated with partial replacement of cake flour with GABA tea and water had better results in the degree of overall liking compared with cake prepared with 100% cake flour, and the moistness and tenderness improved. In the storage tests for GABA cake samples stored at 25°C for three days, the total plate counts (TPC) of GABA cake were fewer than those of the control. For samples stored at 5°C for seven days, TPC were &lt; 2 × 102 CFU/g. All samples exhibited negative coliforms. The hardness of samples significantly increased during storage. The changes in the moisture content, water activity, Hunter L, a, b values, total dietary fiber, GABA, and six catechins contents of the samples were not significantly different during storage. Tenderness of samples significantly decreased, while the other sensory characteristics showed no difference during storage. Degree of overall liking of the samples decreased significantly during storage.

Antihypertensive effect of γ‐amino butyric acid enriched soy products in spontaneously hypertensive rats

The effect of gamma-amino butyric acid (GABA)-enriched soybean on blood pressure was investigated in male spontaneously hypertensive rats. Ten-week-old rats were given diets containing graded levels of GABA-enriched soybean powder for 8 weeks. The systolic blood pressure in rats fed 0.15% GABA diet was significantly lower at 1st week and maintained lower values for 4 weeks as compared with 0% GABA controls. No effect on blood pressure was found in those of 0.03 and 0.3% GABA. The results suggest that there exist appropriate dietary GABA level to get the blood pressure lowering effect.