Changes In GABA Content Research Articles

Optimization of Solid-Phase Lactobacillus Fermentation Conditions to Increase γ-Aminobutyric Acid (GABA) Content in Selected Substrates

The purpose of this study was to optimize conditions of solid-phase fermentation of lactic acid bacteria to enhance GABA contents in grains. Optimal solid-phase fermentation conditions that could enhance the GABA content after fermenting Oryza sativa (brown rice) were investigated by changing the Lactobacillus strain, fermentation temperature, fermentation time, and inoculated bacteria number. Avena sativa, Cicer arietinum, and red and brown Lens culinaris were then fermented using the optimal solid-phase fermentation conditions to measure changes in GABA content and antioxidant activity. As a result of the experiment, the optimal solid-phase fermentation conditions to enhance the GABA contents in grains were: fermentation time, 48 h; amounts of bacteria, inoculating 5% of 1 × 107 CFU/mL of lactic acid bacteria; and fermentation temperature, 36 °C. When fermented under this condition, the GABA content increased from 4.64 mg/g to 6.93 mg/g (49.0%) compared to unfermented raw material. The results of the DPPH and ABTS radical scavenging activity assays confirmed that both the GABA content and radical scavenging activity were increased after fermentation. Such solid fermentation conditions developed in this study can be used to support the development of health functional food materials with enhanced GABA content and antioxidant activity.

Transcriptome Analysis Reveals the Molecular Mechanism of GABA Accumulation during Quinoa (Chenopodium quinoa Willd.) Germination.

Quinoa (Chenopodium quinoa Willd.) with a history of 5000 years as food is extremely rich in nutrients and bioactive compounds, including γ-aminobutyric acid (GABA), a natural four-carbon non-protein amino acid with great benefits to human health. In quinoa, GABA generally increases with the germination time, but the underlying molecular mechanism is unclear. Here, we found that the GABA content in quinoa varied significantly among 25 varieties using an automatic amino acid analyzer. Next, six varieties (three low-GABA and three high-GABA varieties) were used for further analyses. The content of GABA in six varieties all showed an increasing trend after germination. In addition, Pearson's correlation analysis showed that the changes in GABA content were closely related to the transcript level or enzyme activity of three key enzymes including glutamate decarboxylase (GAD), GABA transaminase (GABA-T), and succinate-semialdehyde dehydrogenase (SSADH) in the GABA shunt, especially GAD. Based on RNA-sequencing analysis, eight GAD genes, two GABA-T genes, one SSADH gene, nine polyamine oxidase (PAO) genes, five diamine oxidase (DAO) genes, four 4-aminobutyraldehyde dehydrogenase (BADH) genes, and three thermospermine synthase ACAULIS5 (ACL5) genes were identified. Among these, CqGAD8 and CqGABA-T2 may make a greater contribution to GABA accumulation during quinoa germination.

Modulation of Spinal GABAergic Inhibition and Mechanical Hypersensitivity following Chronic Compression of Dorsal Root Ganglion in the Rat.

Chronic compression of dorsal root ganglion (CCD) results in neuropathic pain. We investigated the role of spinal GABA in CCD-induced pain using rats with unilateral CCD. A stereological analysis revealed that the proportion of GABA-immunoreactive neurons to total neurons at L4/5 laminae I–III on the injured side decreased in the early phase of CCD (post-CCD week 1) and then returned to the sham-control level in the late phase (post-CCD week 18). In the early phase, the rats showed an increase in both mechanical sensitivity of the hind paw and spinal WDR neuronal excitability on the injured side, and such increase was suppressed by spinally applied muscimol (GABA-A agonist, 5 nmol) and baclofen (GABA-B agonist, 25 nmol), indicating the reduced spinal GABAergic inhibition involved. In the late phase, the CCD-induced increase in mechanical sensitivity and neuronal excitability returned to pre-CCD levels, and such recovered responses were enhanced by spinally applied bicuculline (GABA-A antagonist, 15 nmol) and CGP52432 (GABA-B antagonist, 15 nmol), indicating the regained spinal GABAergic inhibition involved. In conclusion, the alteration of spinal GABAergic inhibition following CCD and leading to a gradual reduction over time of CCD-induced mechanical hypersensitivity is most likely due to changes in GABA content in spinal GABA neurons.

Reduced GABA Content in the Motor Thalamus during Effective Deep Brain Stimulation of the Subthalamic Nucleus

Deep brain stimulation (DBS) of the subthalamic nucleus (STN), in Parkinson's disease (PD) patients, is a well established therapeutic option, but its mechanisms of action are only partially known. In our previous study, the clinical transitions from OFF- to ON-state were not correlated with significant changes of GABA content inside GPi or substantia nigra reticulata. Here, biochemical effects of STN-DBS have been assessed in putamen (PUT), internal pallidus (GPi), and inside the antero-ventral thalamus (VA), the key station receiving pallidothalamic fibers. In 10 advanced PD patients undergoing surgery, microdialysis samples were collected before and during STN-DBS. cGMP, an index of glutamatergic transmission, was measured in GPi and PUT by radioimmunoassay, whereas GABA from VA was measured by HPLC. During clinically effective STN-DBS, we found a significant decrease in GABA extracellular concentrations in VA (−30%). Simultaneously, cGMP extracellular concentrations were enhanced in PUT (+200%) and GPi (+481%). These findings support a thalamic dis-inhibition, in turn re-establishing a more physiological corticostriatal transmission, as the source of motor improvement. They indirectly confirm the relevance of patterning (instead of mere changes of excitability) and suggest that a rigid interpretation of the standard model, at least when it indicates the hyperactive indirect pathway as key feature of hypokinetic signs, is unlikely to be correct. Finally, given the demonstration of a key role of VA in inducing clinical relief, locally administration of drugs modulating GABA transmission in thalamic nuclei could become an innovative therapeutic strategy.

발아에 따른 일부 특수미의 GABA 함량 변화

The purposes of this work were to investigate the changes in GABA content of six different rice cultivars along with viatmin E content and antioxidant activity after germination. Brown rice was soaked for 24 hr at 25°C and then germinated at 37°C for 48 hr. The content of GABA and vitamin E in the rice samples was measured by using spectrophotometeric and HPLC methods, respectively. Antioxidant activity was measured by ABTS (2,2’-azino-bis- (3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging methods. GABA and vitamin E contents were significantly increased after germination while no significant change in the antioxidant activity was observed. Among the samples tested, Geunnun cultivar contained the highest GABA content before and after germination. On the other hand, Sinmyungheugchal cultivar showed the highest content of vitamin E and antioxidant activity compared to other rice cultivars. In conclusion, the germinated rice with high GABA content can be used for a functional ingredient in rice processing industry.

P.5.031 Changes of GABA content in different rat brain regions under the conditions of experimental hypokinesia

Suppression subtractive hybridization (SSH) was used to identify alterations in gene transcription of the manila clam Ruditapes philippinarum after exposure to 5 μg/L 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) for 15 days. The ability to accumulate BDE-47 in digestive gland and gill was also evaluated in order to provide information for food safety. Analysis of tissue extracts indicated that digestive gland had the higher BDE-47 levels (12,463.1 ± 1334.8 ng/g d.w.) compared to gill (6368.6 ± 738.7ng/g d.w.) after a 15-day exposure period. Forward and reverse SSH libraries were made from pooled digestive glands of R. philippinarum, from which 75 high quality sequences were obtained by BLAST analysis. The expression of 39 genes with significant homology (E-value < 10− 5) out of the 75 sequences was investigated by quantitative RT-PCR. Among the 39 genes, 27 genes were found up-regulated while 12 genes were found down-regulated after the BDE-47 exposure. The 39 genes were involved in cellular cycle, cytoskeleton, substance and energy metabolism, stress response, innate immunity and cell signaling and transport which were extensively discussed. This study provides a preliminary basis for studying the response of marine bivalves upon exposure to PBDEs in terms of regulated gene expression.

Perinatal Δ9-Tetrahydrocannabinol Exposure Augmented the Magnitude of Motor Inhibition Caused by GABAB, but not GABAA, Receptor Agonists in Adult Rats

GARCIA-GIL, L., R. DE MIGUEL, J. ROMERO, A. PEREZ, J. A. RAMOS AND J. J. FERNÁNDEZ-RUIZ. Perinatal Δ9-tetrahydrocannabinol exposure augmented the magnitude of motor inhibition caused by GABAB, but not GABAA, receptor agonists in adult rats. NEUROTOXICOL TERATOL. 21(3) 277–283, 1999.—We have extensively reported that Δ9-tetrahydrocannabinol (Δ9-THC) exposure results in changes in the adult functionality of dopaminergic neurons, in particular, mesotelencephalic pathways, although some changes are evident only after pharmacological challenges. In the present study, we have examined whether similar changes might be observed in γ-aminobutyric acid (GABA) activity, in particular, in those regions where cannabinoid receptors have been reported to be located in GABA-containing neurons. To this end, we first examined GABA content and glutamic acid decarboxylase (GAD) activity in several brain regions of adult male and female rats that had been perinatally exposed to Δ9-THC or oil. Δ9-THC exposure did not modify either GAD activity or GABA content in the ventral-tegmental area, nucleus accumbens, substantia nigra, caudate-putamen, and globus pallidus, thus suggesting no changes in the basal presynaptic activity of GABA-containing neurons. Second, we tested the motor response in the open-field test of these animals after a single injection of muscimol, a GABAA receptor agonist, baclofen, a GABAB receptor agonist, or vehicle. We observed that the motor inhibition caused by baclofen, in terms of decreased ambulation and stereotypy and increased inactivity, was more marked in magnitude in Δ9-THC–exposed males and females. This was not observed for the GABAA receptor agonist, muscimol, indicating a receptor specificity. To extend this observation, we also examined whether the potential differences in the behavioral response found in the above experiment might be due to changes at the level of the efficiency of the activation of these receptors by measuring basal and baclofen-stimulated [35S]-guanylyl-5′-O-(γ-thio)-triphosphate ([35S]-GTPγS) binding in adult male and female rats that had been perinatally exposed to Δ9-THC or oil. However, our results were negative, because perinatal Δ9-THC exposure did not increase baclofen-stimulated [35S]-GTPγS binding in the areas studied; in particular, in the substantia nigra, an area of interest for the interactions GABAB receptor/cannabinoid receptor. Collectively, the present results indicate that although perinatal Δ9-THC did not produce any changes in GABA content and GAD activity in limbic and motor areas in adulthood, it did increase the behavioral response to GABAB receptor agonists. However, this increase was not due to changes in GABAB receptor activation of signal transduction mechanisms, as revealed the analysis of the percentage of stimulation by baclofen of [35S]-GTPγS binding in the substantia nigra and other structures of males and females perinatally exposed to Δ9-THC.

Changes in GABA content and turnover in discrete regions of rat brain after systemic administration of caerulein

The effects of systemically injected caerulein, a cholecystokinin octapeptide analogue, on GABA content and turnover have been studied in various regions of rat brain. Caerulein decreased GABA levels in the nucleus accumbens, tuberculum olfactorium and substantia nigra and diminished GABA turnover rates in the striatum, nucleus accumbens and substantia nigra, as estimated from the rate of GABA accumulation after inhibition of GABA transaminase by aminooxyacetic acid (AOAA). These results indicate the effect of caerulein on the utilization of GABA in specific cerebral regions and suggest that the GABAergic system is involved in the mechanism of action of peripherally administered caerulein.

Changes inγ-aminobutyric acid during different stages of picrotoxin-induced seizure, and the effect of pretreatment withγ-acetylenic GABA and phenobarbital

Changes in GABA content of various brain areas during different stages of picrotoxin-induced seizures and following pretreatment with the anti-convulsants phenobarbital andγ-acetylenic GABA were studied. Picrotoxin (6mg/kg) produced clonic/tonic convulsions associated with a 34% reduction in GABA content of the sensory motor cortex. A reduction of 24% was observed 1 min before the onset of seizure and the reduction in GABA content was reversible 20 min after the convulsion. No significant changes were observed in the cerebellum or spinal cord/medulla oblongata. Pretreatment with phenobarbital (100mg/kg) delayed the onset of convulsion and decreased the mortality rate without causing any change in GABA content at the pre-convulsive, convulsive or post-convulsive stages.γ-Acetylenic GABA (100mg/kg) has elevated GABA levels in different areas of the brain by 2–3-fold after 60 min treatment. This increase was reduced by 44% during the onset of picrotoxin-induced seizures. Picrotoxin convulsion can occur in the presence of normal, reduced or even elevated brain GABA content. The only consistent factor is a one-third reduction in GABA content before the onset of seizure.

Lack of changes of GABA content in plasma and cerebrospi nal fluid in hepatic encephalopathy

Lack of changes of GABA content in plasma and cerebrospi nal fluid in hepatic encephalopathy

Drug-induced changes in GABA content of nerve endings in 11 rat brain regions. Correlation to pharmacological effects

For determination of in vivo drug effects on nerve terminal GABA, a procedure was used which allowed the simultaneous measurement of GABA in nerve endings (synaptosomes) from 11 regions of one rat brain. Synaptosomal fractions were prepared by conventional subcellular fractionation procedures and characterized by electron microscopy. Postmortem increases of GABA during removal and dissection of brain tissue, homogenization and fractionation procedures could be sufficiently minimized by rapid processing of the tissue at low temperatures and inclusion of 3-mercaptopropionic acid (1 mM) in the homogenizing medium. In vivo experiments with the GABA-elevating drugs aminooxyacetic acid (30 mg/kg i.p.) and valproic acid (200 mg/kg i.p.) showed that both drugs caused differential effects on synaptosomal GABA levels in different brain regions. A comparison of these biochemical effects with anticonvulsant effects of both drugs in different seizure models supports the concept that GABA synapses in midbrain areas are critically involved in the control of seizure propagation.