Application Of GABA Research Articles

Axonal mechanisms mediating γ-aminobutyric acid receptor type A (GABA-A) inhibition of striatal dopamine release.

Axons of dopaminergic neurons innervate the striatum where they contribute to movement and reinforcement learning. Past work has shown that striatal GABA tonically inhibits dopamine release, but whether GABA-A receptors directly modulate transmission or act indirectly through circuit elements is unresolved. Here, we use whole-cell and perforated-patch recordings to test for GABA-A receptors on the main dopaminergic neuron axons and branching processes within the striatum of adult mice. Application of GABA depolarized axons, but also decreased the amplitude of axonal spikes, limited propagation and reduced striatal dopamine release. The mechanism of inhibition involved sodium channel inactivation and shunting. Lastly, we show the positive allosteric modulator diazepam enhanced GABA-A currents on dopaminergic axons and directly inhibited release, but also likely acts by reducing excitation from cholinergic interneurons. Thus, we reveal the mechanisms of GABA-A receptor modulation of dopamine release and provide new insights into the actions of benzodiazepines within the striatum.

Exogenous GABA promotes adaptation and growth by altering the carbon and nitrogen metabolic flux in poplar seedlings under low nitrogen conditions.

Nitrogen (N) deficiency adversely affects tree growth. Additionally, γ-aminobutyric acid (GABA) is closely associated with growth and stress responses because of its effects on carbon (C) and N metabolism. However, little is known about its roles related to plant adaptations to N-deficient conditions. In this study, we analyzed the effects of GABA (0, 2 and 10mM) applications on the growth traits and physiological responses of poplar (Populus alba×P. glandulosa '84K') seedlings under high N (HN) and low N (LN) conditions. We found that the added GABA interacted with N to affect more than half of the studied parameters, with greater effects in LN plants than in HN plants. Under LN conditions, the GABA application tended to increase poplar growth, accompanied by increased xylem fiber cell length and xylem width. In stems, exogenous GABA increased the abundance of non-structural carbohydrates (starch and sugars) and tricarboxylic acid cycle intermediates (succinate, malate and citrate), but had the opposite effect on the structural C contents (hemicellulose and lignin). Meanwhile, exogenous GABA increased the total soluble protein contents in leaves and stems, accompanied by significant increases in nitrate reductase, nitrite reductase and glutamine synthetase activities in leaves, but significant decreases in those (except for the increased glutamate synthetase activity) in stems. A multiple factorial analysis indicated that the nitrate assimilation pathway substantially influences poplar survival and growth in the presence of GABA under LN conditions. Interestingly, GABA applications also considerably attenuated the LN-induced increase in the activities of leaf antioxidant enzymes, including peroxidase and catalase, implying that GABA may regulate the relative allocation of C and N for growth activities by decreasing the energy cost associated with stress defense. Our results suggest that GABA enhances poplar growth and adaptation by regulating the C and N metabolic flux under N-deficient conditions.

Drought-induced stress in leaves of Coix lacryma-jobi L. under exogenous application of proline and GABA amino acids

Coix lacryma-jobi L. is an Asian plant widely used in traditional medicine. Drought conditions can lead to an impairment of photosynthesis which can be softened by the exogenous application of proline and γ-aminobutyric acid (GABA) to maintain the electron transport chain (ETC) and avoid reactive oxygen species-induced oxidative damage by inducing antioxidative enzymes. The aim of this study was to evaluate the effects of water deficit on C. lacryma-jobi leaves under the application of proline and GABA. Chlorophyll (Chl) a fluorescence emission, antioxidative enzyme activity (catalase, superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase) and proline and GABA contents in leaf tissues were performed in plants subjected to 12 days of drought. Chl a fluorescence indicated impairments on photosynthetic apparatus due to water deficit that resulted into increased activity of antioxidant enzymes. The application of proline but not GABA was more efficient in alleviating the effects of water deficit, as evidenced by the maintenance of the dynamic dissipation of the photosynthetic energy, besides the greater accumulation of proline under these conditions. Water deficit induces alterations in the ETC, which is softened by the application of proline to cope with the deleterious effects of drought in C. lacryma-jobi plant leaves.

Extending the shelf life of pomegranate (Punica granatum L.) by GABA coating application

The decrease in fruit quality between harvest and consumption is an important area in agriculture. Edible coatings are harmless compounds used for covering the crops after harvest to reduce the metabolism intensity. γ-aminobutyric acid (GABA) is a good candidate because it is a natural substance produced by plants at stress conditions. Pomegranate (Punica granatum L.) is a perishable fruit because it has a high content of water and nutritional compounds and also relatively soft texture. In this study the effect of GABA on extending the pomegranate shelf life at 4 ± 1 °C was studied. The treatments included control (distilled water), GABA (5, 10 and 15 mM) and the storage periods (45 and 90 days) with four replications. The results showed that GABA treatments had some positive effects on improving peel (skin) and aril (edible part of seeds) firmness, antioxidant activity, phenolic compounds content, scent and taste, freshness of texture and aril color indicators and they reduced ion leakage, chilling injury signs and malondialdehyde formation. However, GABA did not have a positive effect on weight loss. Total acidity in control and treated samples was reduced until 45 days but increased at day 90. GABA had the ability to maintain the fruit pH stable. Total soluble solids and vitamin C content were not affected by storage and GABA, and the effects on anthocyanin content were varied among treatments. Totally, the results suggested that postharvest application of GABA has the potential to extend the storage life of pomegranate fruits by maintaining some fruit qualities.

Suppression of heat-induced leaf senescence by γ-aminobutyric acid, proline, and ammonium nitrate through regulation of chlorophyll degradation in creeping bentgrass

Heat-induced leaf senescence may be regulated by nitrogen or nitrogen-enriched amino acids. The objectives of the current study were to examine whether exogenous application of у-aminobutyric acid (GABA), proline, and ammonium nitrate (N) could alleviate heat-induced leaf senescence in creeping bentgrass (Agrostis stolonifera L.) and to determine whether the effects of GABA, proline, and N on heat-induced leaf senescence were associated with the alteration of chlorophyll (Chl) metabolism. Plants were exposed to heat stress (35/30 °C, day/night) or non-stress (22/18 °C, day/night) temperature conditions for 35 d in controlled-environment growth chambers. Turf quality, Chl content, and photochemical efficiency declined whereas the activities of Chl-degrading enzymes (chlorophyllase and pheophytinase) increased in response to heat stress. Application of GABA, proline, or N significantly enhanced turf quality, Chl content, and photochemical efficiency, and suppressed Chl-degrading enzyme activities under heat stress. The activity of a Chl-synthesizing enzyme (porphobilinogen deaminase) was not affected by GABA, proline, or N application. These results indicate that heat-induced leaf senescence could be mainly due to heat-accelerated Chl degradation, and GABA, proline, or N could suppress Chl degradation, alleviating heat-induced leaf senescence in creeping bentgrass.

Modulation of Human Stem Cell Derived Neuron Activity through Addition of an External Conductance using Dynamic Clamp

Human stem-cell derived (hiPSC) neurons are a model system for studying the electrophysiological properties of neurons. HiPSC neurons, however, display depolarized resting membrane potentials (RMPs) due to insufficient expression of background K+ currents. Using a real-time dynamic clamp system, we have previously demonstrated with iCell hiPSC GABA neurons that electronic expression of K+ currents allows RMP tuning to physiological levels (−55 to −65 mV) and recording of stable action potentials (APs). In the present studies, neurons had depolarized RMPs (−34±2 mV, n = 21) and evoked APs displayed non-physiological characteristics (Amp. = 60±5 mV, after-hyperpolarization (AHP) = −40±2 mV, n=21). Tuning the RMP via electronic expression of a delayed rectifier K+ current resulted in stable RMP (‑64±1 mV, n=7) and evoked APs (Amp. = 87±11 mV, AHP at ‑72±2 mV, n = 7). We further developed the use of dynamic clamp to modulate neuronal activity through the addition of a current response inputted as a conductance. The conductance is given by k∗(V - Vrev)∗(t) where k is a scale factor for controlling the magnitude of the conductance, V is the voltage, Vrev is the reversal potential for the current response and (t) is the current response. We simulated application of GABA by inputting as a conductance a recorded inward GABA current response (−10 pA at ‑80 mV). In neurons tuned to an RMP of −65 mV, addition of the GABA conductance at Vrev = ‑30 mV resulted in depolarization and AP firing while setting Vrev = −80 mV resulted in hyperpolarization. Taken together, the addition of a tunable second conductance (magnitude, Vrev) via dynamic clamp can be used to simulate the effects of neurotransmitters and modulators of ion channel currents on neuronal function.

Effect of Protons on GABAA Receptors in Central Neurons of Various Types.

Whole-cell patch-clamp technique was employed to record chloride ionic current IGABA evoked by fast (600 msec) application of GABA to hippocampal pyramidal neurons and cerebellar Purkinje cells isolated from rat brain. GABA solution in the application pipette was either neutral (pH 7.4) or acidic (pH 7.0 or 6.0). Application of protons to neurons causes a rapid, reversible, and dose-dependent decrease in the amplitude of IGABA; the effect was more pronounced on hippocampal neurons (carrying both synaptic and extrasynaptic GABAA receptors) than in cerebellar Purkinje cells (predominantly equipped with synaptic GABAA receptors). In hippocampal neurons, pharmacological isolation of extrasynaptic component from total IGABA was performed with GABAA receptor antagonist gabazine (50 nM). The extrasynaptic component of IGABA was stronger blocked by protons than total IGABA. It was concluded that acidic medium produced more potent blocking effect on extrasynaptic GABAA receptors than on synaptic ones.

Molecular and Regulatory Mechanisms of Desensitization and Resensitization of GABAA Receptors with a Special Reference to Propofol/Barbiturate.

It is known that desensitization of GABAA receptor (GABAAR)-mediated currents is paradoxically correlated with the slowdown of their deactivation, i.e., resensitization. It has been shown that an upregulation of calcineurin enhances the desensitization of GABAAR-mediated currents but paradoxically prolongs the decay phase of inhibitory postsynaptic currents/potentials without appreciable diminution of their amplitudes. The paradoxical correlation between desensitization and resensitization of GABAAR-mediated currents can be more clearly seen in response to a prolonged application of GABA to allow more desensitization, instead of brief pulse used in previous studies. Indeed, hump-like GABAAR currents were produced after a strong desensitization at the offset of a prolonged puff application of GABA in pyramidal cells of the barrel cortex, in which calcineurin activity was enhanced by deleting phospholipase C-related catalytically inactive proteins to enhance the desensitization/resensitization of GABAAR-mediated currents. Hump-like GABAAR currents were also evoked at the offset of propofol or barbiturate applications in hippocampal or sensory neurons, but not GABA applications. Propofol and barbiturate are useful to treat benzodiazepine/alcohol withdrawal syndrome, suggesting that regulatory mechanisms of desensitization/resensitization of GABAAR-mediated currents are important in understanding benzodiazepine/alcohol withdrawal syndrome. In this review, we will discuss the molecular and regulatory mechanisms underlying the desensitization and resensitization of GABAAR-mediated currents and their functional significances.

Proteomic and Metabolomic Profilings Reveal Crucial Functions of γ-Aminobutyric Acid in Regulating Ionic, Water, and Metabolic Homeostasis in Creeping Bentgrass under Salt Stress.

The global emergence of soil salinization poses a serious challenge to many countries and regions. γ-Aminobutyric acid (GABA) is involved in systemic regulation of plant adaptation to salt stress but the underlying molecular and metabolic mechanism still remains largely unknown. The elevated endogenous GABA level by the application of exogenous GABA improved salt tolerance associated with the enhancement of antioxidant capacity, photosynthetic characteristics, osmotic adjustment (OA), and water use efficiency in creeping bentgrass. GABA strongly upregulated transcript levels of AsPPa2, AsATPaB2, AsNHX2/4/6, and AsSOS1/20 in roots involved in enhanced capacity of Na+ compartmentalization and mitigation of Na+ toxicity in the cytosol. Significant downregulation of AsHKT1/4 expression could be induced by GABA in leaves in relation to maintenance of the significantly lower Na+ content and higher K+/Na+ ratio. GABA-depressed aquaporin expression and accumulation induced declines in stomatal conductance and transpiration, thereby reducing water loss in leaves during salt stress. For metabolic regulation, GABA primarily enhanced sugar and amino acid accumulation and metabolism, largely contributing to improved salt tolerance through maintaining OA and metabolic homeostasis. Other major pathways could be related to GABA-induced salt tolerance including increases in antioxidant defense, heat shock proteins, and myo-inositol accumulation in leaves. Integrative analyses of molecular, protein, metabolic, and physiological changes reveal systemic functions of GABA in regulating ionic, water, and metabolic homeostasis in nonhalophytic creeping bentgrass under salt stress.

Exogenous γ-aminobutyric acid (GABA) application at different growth stages regulates 2-acetyl-1-pyrroline, yield, quality and antioxidant attributes in fragrant rice

ABSTRACT The aim of this study was to investigate the optimum time for γ-aminobutyric acid (GABA) application to improve the yield and quality in fragrant rice. Pot and field experiments were conducted during 2016–17 with two fragrant rice cultivars (for pot experiment), and five fragrant rice cultivars (for field experiment) which were applied with five GABA levels i.e. no GABA application (CK), application of GABA at 250 mg l−1 with 25 ml pot−1 at tillering stage (S1), panicle initiation stage (S2), heading stage (S3), and at tillering, panicle initiation and heading stages (S4) in the pot experiment. Similarly, the same treatments with 100 ml m−2 were applied to all rice cultivars in the field experiment. The S3 treatment significantly increased the 2-acetyl-1-pyrroline (2AP) contents in Meixiangzhan2 (14.76%) and Yuxiangyouzhan (20.19%) in pot experiment, Meixiangzhan2 (27.27%), Yuxiangyouzhan (40.24%), Basmati (43.07%) and Yungengyou14 (13.66%) in field experiment owing to regulations in the contents of proline, Δ1-pyrroline-5-carboxylic acid (P5C), GABA and the activities of enzymes involved in 2AP formation. The GABA treatments improved yield and modulated the antioxidant enzyme activities. This study provides a reference for the GABA application to improve yield and quality in fragrant rice.

Serotonergic control of GABAergic inhibition in the lateral amygdala.

Much evidence implicates the serotonergic regulation of the amygdala in anxiety. Thus the present study was undertaken to characterize the influence of serotonin (5-HT) on principal neurons (PNs) of the rat lateral amygdala (LA), using whole cell recordings in vitro. Because inhibition is a major determinant of PN activity, we focused on the control of GABAergic transmission by 5-HT. IPSCs were elicited by local electrical stimulation of LA in the presence of glutamate receptor antagonists. We found that 5-HT reduces GABAA inhibitory postsynaptic currents (IPSCs) via presynaptic 5-HT1B receptors. While the presynaptic inhibition of GABA release also attenuated GABAB currents, this effect was less pronounced than for GABAA currents because 5-HT also induced a competing postsynaptic enhancement of GABAB currents. That is, GABAB currents elicited by pressure application of GABA or baclofen were enhanced by 5-HT. In addition, we obtained evidence suggesting that 5-HT differentially regulates distinct subsets of GABAergic synapses. Indeed, GABAA IPSCs were comprised of two components: a relatively 5-HT-insensitive IPSC that had a fast time course and a 5-HT-sensitive component that had a slower time course. Because the relative contribution of these two components varied depending on whether neurons were recorded at proximity versus at a distance from the stimulating electrodes, we speculate that distinct subtypes of local-circuit cells contribute the two contingents of GABAergic synapses. Overall, our results indicate that 5-HT is a potent regulator of synaptic inhibition in LA.NEW & NOTEWORTHY We report that 5-HT, acting via presynaptic 5-HT1B receptors, attenuates GABAA IPSCs by reducing GABA release in the lateral amygdala (LA). In parallel, 5-HT enhances GABAB currents postsynaptically, such that GABAB inhibitory postsynaptic currents (IPSCs) are relatively preserved from the presynaptic inhibition of GABA release. We also found that the time course of 5-HT-sensitive and -insensitive GABAA IPSCs differ. Together, these results indicate that 5-HT is a potent regulator of synaptic inhibition in LA.

Enhancement of 2-acetyl-1-pyrroline (2AP) concentration, total yield, and quality in fragrant rice through exogenous γ-aminobutyric acid (GABA) application

The effects of exogenous application of γ-aminobutyric acid (GABA) on yield and quality characteristics, especially 2-acetyl-1-pyrroline (2AP) biosynthesis, are rarely investigated. Two field experiments, i.e., experiment 1 (EXP.1) and experiment 2 (EXP.2), were conducted, and four GABA levels, i.e., 0, 50, 500, 1000 mg l−1, classified as CK, T1, T2, and T3, respectively, were sprayed at the initial heading stage of a fragrant rice cultivar, Yuxiangyouzhan. The results showed that exogenous GABA application increased the 2AP content in grains 8.58%–19.44% in EXP.1 and 0.01%–6.22% in EXP.2. Exogenous GABA treatments also increased the GABA concentration in the grains and proline content in fragrant rice. Significant correlations between the grain 2AP content and proline content in leaves at 5 days after spraying were also detected in EXP.1, whereas GABA application did not significantly affect leaf dry weight, total dry weight, or grain yield. Moreover, gas exchange parameters, soil-plant analyses development values, and antioxidant activities were improved under GABA treatments. Additionally, the GABA applications substantially improved the grain quality characteristics, including milled rice percentage, head rice percentage, and protein content. Overall, exogenous GABA application was effective in the improvement of quality characteristics in fragrant rice, especially that of grain 2AP contents.

γ-Aminobutyric acid (GABA) regulates lipid production and cadmium uptake by Monoraphidium sp. QLY-1 under cadmium stress

This study explored the effects of γ-aminobutyric acid (GABA) on the production of biomass and lipids and on the uptake of Cd2+ by microalgae under cadmium (Cd) stress. Compared with the control and Cd stress alone, 2.5 mM GABA increased the maximum lipid content (55.37%) by 49.37% and 9.42%, respectively. GABA application resulted in increased contents of protein and glutathione (GSH) and in upregulated activity of α-amylase but decreased contents of starch, reactive oxygen species (ROS) and Cd2+, with no effect on subsequent biodiesel quality. Additional analysis of GABA further indicated that increased cellular GABA contents could promote lipid synthesis and reduce Cd accumulation by regulating the expression levels of lipogenesis genes, ROS signalling and mineral nutrient uptake under Cd stress. Collectively, these findings show that GABA not only increases lipid production in microalgae but also is involved in the mechanisms by which microalgae respond to Cd stress.

Exogenous GABA alleviates alkaline stress in Malus hupehensis by regulating the accumulation of organic acids

Alkaline stress affects the apple production in northwestern China. Here, Malus hupehensis was used as a material to study the influence of exogenous γ-aminobutyric acid (GABA) application on seedlings under alkaline stress in hydroponics. 0.5 mM GABA was identified as the most suitable concentration to alleviate alkaline stress. Compared with the control, exogenous GABA significantly increased biomass, root growth, and scavenging activities of reactive oxygen species in apple seedlings under alkaline stress. In addition, the photosynthetic characteristics and total chlorophyll concentration increased remarkably in response to GABA application. Exogenous GABA also significantly increased the contents of malate, citric acid, and succinate by promoting the GABA shunt. Furthermore, the activities of malate dehydrogenase, citrate synthase, isocitrate dehydrogenase, and aconitase increased in response to GABA application. These results are important to indicate the use of exogenous substances to improve the resistance of apples to alkaline stress.

Changes in Calcium Levels in Motor Nerve Endings in Mice on Activation of Metabotropic Cholinoreceptors and GABA Receptors

Previous studies of neuromuscular synapses in mammals have detected metabotropic cholinoreceptors (mChR) and GABA receptors. Activation of both types of receptor leads to changes in the intensity of calcium-dependent quantum release of acetylcholine (ACh). We report here studies using recording of calcium signals (Ca2+ transients) to assess changes in calcium levels in motor nerve endings on application of the ligands of various receptors. Muscarine (an mChR agonist) was found to decrease the amplitude of the calcium transient, while atropine (an mChR blocker), conversely, led to an increase in the signal. Application of GABA had no effect on the parameters of the transient. Thus, the mechanism of regulation of mChR-triggered ACh neurosecretion may be mediated by changes in the calcium level in nerve terminals, while the effect of GABA on the process of ACh neurosecretion is mediated by molecular mechanisms not linked directly with calcium metabolism in the motor terminal.

ITRAQ-based proteomics reveals key role of γ-aminobutyric acid (GABA) in regulating drought tolerance in perennial creeping bentgrass (Agrostis stolonifera)

γ-Aminobutyric acid (GABA), a non-proteinaceous amino acid, modulates plant growth and stress tolerance. However, the potential role of GABA in regulating key metabolic pathways and stress-defensive proteins against drought in plants has never been explored. Creeping bentgrass (Agrostis stolonifera) plants were pretreated with or without GABA and then subjected to water stress for 8 days in controlled growth chambers (23/19 °C, day/night). Physiological analysis showed that elevated endogenous GABA level via exogenous GABA application significantly mitigated water stress damage to creeping bentgrass, as manifested by increased leaf relative water content, water use efficiency, osmotic adjustment (OA), photochemical efficiency (Fv/Fm), net photosynthetic rate, and reduced oxidative damage. iTRAQ-based proteomics found that enhanced chaperones accumulation, carbohydrates, amino acids, and energy metabolism played important roles in protein protection, OA, energy maintenance, and metabolic balance, which is important adaptive response to drought stress in creeping bentgrass. The GABA further promoted energy production and conversion, antioxidant defense, and DHN3 accumulation that were essential for energy requirement, ROS-scavenging, and the prevention of cell dehydration in leaf during drought stress. In addition, GABA-treated plants maintained significantly higher abundance of dicarboxylate transporter 2.1, ATP-dependent zinc metalloprotease, receptor-like protein kinase HERK1, o-acyltransferase WSD1, omega-6 fatty acid desaturase, and two-component response regulator ORR21 than untreated plants under drought stress. The result provides new evidences that GABA-induced drought tolerance is possibly involved in the improvement of nitrogen recycling, protection of photosystem II, mitigation of drought-depressed cell elongation, wax biosynthesis, fatty acid desaturase, and delaying leaf senescence in creeping bentgrass.

Regulation of Heat Shock Factor Pathways by γ-aminobutyric Acid (GABA) Associated with Thermotolerance of Creeping Bentgrass.

Activation and enhancement of heat shock factor (HSF) pathways are important adaptive responses to heat stress in plants. The γ-aminobutyric acid (GABA) plays an important role in regulating heat tolerance, but it is unclear whether GABA-induced thermotolerance is associated with activation of HSF pathways in plants. In this study, the changes of endogenous GABA level affecting physiological responses and genes involved in HSF pathways were investigated in creeping bentgrass during heat stress. The increase in endogenous GABA content induced by exogenous application of GABA effectively alleviated heat damage, as reflected by higher leaf relative water content, cell membrane stability, photosynthesis, and lower oxidative damage. Contrarily, the inhibition of GABA accumulation by the application of GABA biosynthesis inhibitor further aggravated heat damage. Transcriptional analyses showed that exogenous GABA could significantly upregulate transcript levels of genes encoding heat shock factor HSFs (HSFA-6a, HSFA-2c, and HSFB-2b), heat shock proteins (HSP17.8, HSP26.7, HSP70, and HSP90.1-b1), and ascorbate peroxidase 3 (APX3), whereas the inhibition of GABA biosynthesis depressed these genes expression under heat stress. Our results indicate GABA regulates thermotolerance associated with activation and enhancement of HSF pathways in creeping bentgrass.

Etomidate Modulates the Tactile Stimulation-Evoked Field Potential Responses in Cerebellar Granule Cell Layer in vivo in Mice

Etomidate (ET) produces sedation by binding on the γ-aminobutyric acid type A (GABAA) receptors. We previously found that ET inhibited cerebellar Purkinje cells activity via both GABAA and glycine receptors in vivo in mice, suggesting that ET modulated sensory information synaptic transmission in cerebellar cortex. In this study, we investigated the effect of ET on the sensory stimulation-evoked responses in the cerebellar granule layer (GL) in urethane-anesthetized mice, using electrophysiological and pharmacological methods. Our results showed that cerebellar surface perfusion of ET (100 μmol/L) significantly decreased amplitude and area under the curve (AUC) of the sensory stimulation-evoked excitatory component (N1) in the cerebellar GL. Application of GABAA receptor antagonist, SR95531 (20 μmol/L) significantly attenuated, but not abolished the ET-induced decrease in amplitude and AUC of facial stimulation-evoked responses. However, application of a mixture of SR95531 (20 μmol/L) and cannabinoid 1 receptor (CB1) antagonist, AM-251 (5 μmol/L), completely blocked the ET-induced decrease in amplitude and AUC of facial stimulation-evoked responses. Furthermore, application of the CB1 receptor agonist, WIN55212-2, induced a decrease in amplitude and AUC of N1 in the absence of GABAA receptors activity, as well occluded the ET-induced depression of N1. Moreover, the ET-induced changes in amplitude and AUC of N1 in absence of GABAA receptors activity were abolished by a specific protein kinase A (PKA) inhibitor, KT5720. These results indicate that ET facilitates CB1 receptors in the absence of GABAA receptors activity, resulting in a depression of the sensory stimulation-evoked synaptic transmission via PKA signaling pathway in mouse cerebellar GL.

γ-Aminobutyric Acid Regulates Grain Yield Formation in Different Fragrant Rice Genotypes Under Different Nitrogen Levels

The influences of γ-aminobutyric acid (GABA) and nitrogen on grain yield, yield-related traits, plant growth, grain–leaf ratio and NSC contents in different fragrant rice genotypes are not fully understood. A pot experiment was conducted with four nitrogen rates, i.e. 0, 0.87, 1.75, and 2.61 g pot−1, two GABA levels, i.e. 0 and 250 mg L−1, and three fragrant rice cultivars, i.e. Yuxiangyouzhan, Yungengyou 14 and Basmati. Results depicted that GABA treatment significantly increased the mean grain yield by 11.84% as a consequence of the increment of grain weight, spikelet per pot, grain weight per leaf area, stem sheath dry weight at HS, panicle dry weight at HS, panicle dry weight at MS and total dry weight at MS. Besides, significant effects of nitrogen and cultivar on yield and yield-related traits and some rice growth parameters were observed. Moreover, significant positive correlation relationships between yield and panicle number per pot, leaf area and dry weight for all the cultivars were observed. GABA application could alleviate the effects of nitrogen on grain yield in fragrant rice. These results suggest that GABA is feasible to increase grain yield and improve rice plant growth for fragrant rice varieties grown under different nitrogen conditions.

GABA application improves the mitochondrial antioxidant system and reduces peel browning in ‘Nanguo’ pears after removal from cold storage

Although refrigeration is commonly used in the storage of ‘Nanguo’ pears (Pyrus ussuriensis Maxim.), long-term refrigeration can result in browning of the pericarp. In this study, we aimed to determine how γ-aminobutyrate (GABA) affects the mitochondrial oxidation defense system in ‘Nanguo’ pears and how it might be used to prevent post-refrigeration peel browning. We found that fruit treated with GABA browned slower, and had lower browning indices and reactive oxygen and malondialdehyde content; increased peroxidase, superoxide dismutase, alternating oxidase, and catalase enzyme activities; and heightened enzyme-related gene expression. The mitochondria of GABA-treated fruit also showed less damage following cold storage, and there were decreases in mitochondrial membrane permeability transition pore concentrations. Furthermore, we detected an increase in the endogenous GABA content of fruits following GABA treatment. These observations indicate that, by regulating the mitochondrial oxidative defense system and maintaining mitochondrial structure, GABA is effective in terms of reducing peel browning.