Role Of Gamma-aminobutyric Acid Research Articles

GABA-immunoreactive neurons in the Central Nervous System of the viviparous teleost Poecilia sphenops

Gamma-aminobutyric acid (GABA) functions as the primary inhibitory neurotransmitter within the central nervous system (CNS) of vertebrates. In this study, we examined the distribution pattern of GABA-immunoreactive (GABA-ir) cells and fibres in the CNS of the viviparous teleost Poecilia sphenops using immunofluorescence method. GABA immunoreactivity was seen in the glomerular, mitral, and granular layers of the olfactory bulbs, as well as in most parts of the dorsal and ventral telencephalon. The preoptic area consisted of a small cluster of GABA-ir cells, whereas extensively labelled GABA-ir neurons were observed in the hypothalamic areas, including the paraventricular organ, tuberal hypothalamus, nucleus recessus lateralis, nucleus recessus posterioris, and inferior lobes. In the thalamus, GABA-positive neurons were only found in the ventral thalamic and central posterior thalamic nuclei, whereas the dorsal part of the nucleus pretectalis periventricularis consisted of a few GABA-ir cells. GABA-immunoreactivity was extensively seen in the alar and basal subdivisions of the midbrain, whereas in the rhombencephalon, GABA-ir cells and fibres were found in the cerebellum, motor nucleus of glossopharyngeal and vagal nerves, nucleus commissuralis of Cajal, and reticular formation. In the spinal cord, GABA-ir cells and fibres were observed in the dorsal horn, ventral horn, and around the central canal. Overall, the extensive distribution of GABA-ir cells and fibres throughout the CNS suggests several roles for GABA, including the neuroendocrine, viscerosensory, and somatosensory functions, for the first time in a viviparous teleost.

Role of Gamma-Aminobutyric Acid in Plant Defense Response.

Gamma-aminobutyric acid (GABA) is a four-carbon non-protein amino acid that acts as a defense substance and a signaling molecule in various physiological processes, and which helps plants respond to biotic and abiotic stresses. This review focuses on the role of GABA's synthetic and metabolic pathways in regulating primary plant metabolism, redistributing carbon and nitrogen resources, reducing the accumulation of reactive oxygen species, and improving plants' tolerance of oxidative stress. This review also highlights the way in which GABA maintains intracellular pH homeostasis by acting as a buffer and activating H+-ATPase. In addition, calcium signals participate in the accumulation process of GABA under stress. Moreover, GABA also transmits calcium signals through receptors to trigger downstream signaling cascades. In conclusion, understanding the role of GABA in this defense response provides a theoretical basis for applying GABA in agriculture and forestry and feasible coping strategies for plants in complex and changeable environments.

γ Aminobutyric Acid (GABA): A Key Player in Alleviating Abiotic Stress Resistance in Horticultural Crops: Current Insights and Future Directions

Gamma-aminobutyric acid (GABA) is a non-protein amino acid known for its role in the nervous system of animals. However, research has also revealed its presence and function in plants recently. In plants, GABA is a signal molecule involved in multiple physiological processes, including stress response, growth, and development. This review aims to present a thorough summary of the current knowledge regarding the role of GABA in plants. We begin by discussing the biosynthesis and transport of GABA in plants, followed by a detailed examination of its signaling mechanisms. Additionally, we explore GABA's potential roles in various plant physiological processes, such as abiotic stress response, and its potential application in horticultural plants. Finally, we highlight current challenges and future directions for research in this area. Overall, this review offers a comprehensive understanding of the significance of GABA in plants and its potential implications for plant physiology and crop improvement.

The role of gamma-aminobutyric acid in female depression

The role of gamma-aminobutyric acid in female depression

Differentiation of myoblasts in culture: focus on serum and GABA.

There are many facts about the possible role of gamma-aminobutyric acid (GABA) in the development and differentiation of cells not only in nervous but also in muscle tissue. In the present study a primary culture of rat skeletal muscle myocytes was used to evaluate the correlation between the content of GABA in the cytoplasm and the processes of myocyte division and their fusion into myotubes.The effect of exogenous GABA on the processes of culture development was also estimated. Since the classical protocol for working with myocyte cultures involves the use of fetal bovine serum (FBS) to stimulate cell division (growth medium) and horse serum (HS) to activate the differentiation process (differentiation medium), the studies were carried out both in the medium with FBS and with HS. It was found that cells grown in medium supplemented withFBS contain more GABA compared to cultures growing in medium supplemented with HS. Addition of exogeneous GABA leads to a decrease in the number of myotubes formed in both media, while the addition of an amino acid to the medium supplemented with HS had a more pronounced inhibitory effect. Thus, we have obtained data indicating that GABA is able to participate in the early stages of skeletal muscle myogenesis by modulating the fusion process.

The Role of Gamma-Amino Butyric Acid in Short-Term High Temperature Acclimation in Lichen Pseudevernia furfuracea

Objective: Global warming causes many different stresses for plants. High-temperature stress is one of the important problems caused by global warming. Plants develop various tolerance mechanisms to protect themselves against these stresses. γ-Aminobutyric acid (GABA) metabolism has a critical role in various biological processes in plants. GABA plays a critical role in the acclimation to different stress conditions in plants. Lichens can grow in environments exposed to severe abiotic stresses such as drought and extreme heat. The major aim of this study was to identify whether GABA accumulation could improve short-term, high-temperature tolerance in lichen Pseudevernia furfuracea. Materials and Methods: For this aim, P. furfuracea samples were kept in petri dishes in an incubator at 45 ± 2°C for 24 and 48 h. We analyzed the chlorophyll a/b ratio, GABA content, glutamate decarboxylase (GAD) and glutamate dehydrogenase (GDH) activities, which are important enzymes involved in the GABA shunt, and also peroxidase (POD) and catalase (CAT) activities of the antioxidant metabolism. Results: Our study indicated that the chlorophyll a/b ratio was not changed significantly under 45°C within 48 h. POD and CAT activities were significantly decreased in lichen thalli under 45°C, however; GABA accumulation was approximately enhanced by 1.5-fold depending on the time exposure. GAD and GDH activities were significantly increased under high temperature conditions. Conclusions: The acclimilation of P. furfuracea to high temperatures may be related to the increase in GAD and GDH activities. Our findings provided evidence that the GABA shunt could help lichen P. furfuracea to acclimate to high temperatures.

Physiological and proteomic analyses of γ-aminobutyric acid (GABA)-treated tubers reveals that StPOD42 promotes sprouting in potato

Gamma-aminobutyric acid (GABA) is a nonproteinogenic amino acid that plays vital roles in plant growth and developmental processes. However, its role in regulating potato sprouting is unknown. Therefore, the physiological and molecular mechanisms underlying the sprouting process were assessed, and we found that GABA promoted sprouting after treatment for 50 d. In addition, the GABA and soluble sugar contents increased while the starch content decreased. To study the molecular mechanism by which exogenous GABA accelerates tuber sprouting, comparative proteomic analysis of tuber bud eyes was performed after GABA treatment for 48 h. Further analysis revealed 316 differentially abundant proteins (DAPs) that are mainly involved in fatty acid and sugar metabolism and cutin, suberin and wax biosyntheses. The qRT‒PCR results suggested that the GABA transaminase 2 (GABA-T2) and GABA-T3 expression levels showed the greatest decrease at 30 d of storage. Peroxidase 42 (StPOD42) expression showed the greatest increase at 30 d. Overexpression of StPOD42 in potato was found to promote tuber sprouting. Our results provide new insights into the role of GABA in regulating the sprouting process and indicate that StPOD42 is a target gene for molecular breeding to modulate potato sprouting.

Metabolomic profiling relates tianeptine effectiveness with hippocampal GABA, myo-inositol, cholesterol, and fatty acid metabolism restoration in socially isolated rats.

Discovering biomarkers of major depressive disorder (MDD) can give a deeper understanding of this mood disorder and improve the ability to screen for, diagnose, and treat MDD. In this study, metabolomics was used in unraveling metabolite fluctuations of MDD and drug outcome by creating specific metabolomic fingerprints. We report metabolomic patterns of change of the hippocampus of adult male Wistar rats following chronic social isolation (CSIS) (6weeks), an animal model of depression, and/or chronic tianeptine (Tian) treatment (10mgkg-1 per day) (lasting 3weeks of 6-week CSIS), monitored by using comprehensive GC × GC-MS. The comparative metabolomic analysis highlighted the role of gamma aminobutyric acid (GABA), iso-allocholate, and unsaturated fatty acid metabolism alterations following the CSIS, which was corroborated with moderate to strong negative Pearson's correlation of GABA, docosahexaenoic, 9-hexadecenoic acid, 5,8,11,14-eicosatetraynoic, and arachidonic acids with immobility behavior in the forced swim test. The antidepressant effect of Tian restored GABA levels, which was absent in Tian resilient rats. Tian decreased myo-inositol and increased TCA cycle intermediates, amino acids, and cholesterol and its metabolite. As key molecules of divergence between Tian effectiveness and resilience, metabolomics revealed myo-inositol, GABA, cholesterol, and its metabolite. A significant moderate positive correlation between myo-inositol and immobility was revealed. Tian probably acted by upregulating NMDAR's and α2 adrenergic receptors (AR) or norepinephrine transporter in both control and stressed animals. Metabolomics revealed several dysregulations underlying CSIS-induced depressive-like behavior and responsiveness to Tian, predominantly converging into NMDAR-mediated glutamate and myo-inositol signalization and GABA inhibitory pathways.

Screening of Lactobacillus rhamnosus-producing gamma aminobutyric acid (GABA) isolated from Sumbawa mare milk and its potential application to increase GABA content in fermented milk

The broad role of gamma aminobutyric acid (GABA) in human health has triggered various efforts to increase its concentration in foodstuffs. The use of microorganisms to increase the GABA content in food is a rational choice. The objective of this study was to identify the GABA-producing Lactobacillus rhamnosus strain isolated from Sumbawa mare milk and its potential application as a starter to increase GABA content in fermented milk. A total of 34 L. rhamnosus strains were screened for their ability to produce GABA in MRS medium containing 2% monosodium glutamate (MSG). GABA presence in the culture broth was analysed qualitatively by using TLC, whereas GABA concentration was determined using UPLC. The results showed that 17 out of 34 L. rhamnosus strains produced GABA at varying concentrations from 0.047 to 0.384 mg/mL. Six selected strains were determined for their capacity in GABA production in skim milk without MSG addition. The results showed that GABA was produced by L. rhamnosus strains on skim milk ranging from 0.07 to 2.01 mg/mL L. rhamnosus SMM37 possessed the highest GABA production capability, which produced 2.01 mg/mL in skim milk after fermentation for 72 hrs at 37oC. These results indicated that L. rhamnosus strains isolated from Sumbawa mare milk have the potential to be developed as a starter culture to increase GABA content in fermented milk. Nevertheless, further studies are needed in optimizing fermentation conditions to improve GABA production from the L. rhamnosus strains isolated from Sumbawa mare milk.

A role for GABA in the modulation of striatal and hippocampal systems under stress

Previous research has demonstrated that stress modulates the competitive interaction between the hippocampus and striatum, two structures known to be critically involved in motor sequence learning. These earlier investigations, however, have largely focused on blood oxygen-level dependent (BOLD) responses. No study to date has examined the link between stress, motor learning and levels of striatal and hippocampal gamma-aminobutyric acid (GABA). This knowledge gap is surprising given the known role of GABA in neuroplasticity subserving learning and memory. The current study thus examined: a) the effects of motor learning and stress on striatal and hippocampal GABA levels; and b) how learning- and stress-induced changes in GABA relate to the neural correlates of learning. To do so, fifty-three healthy young adults were exposed to a stressful or non-stressful control intervention before motor sequence learning. Striatal and hippocampal GABA levels were assessed at baseline and post-intervention/learning using magnetic resonance spectroscopy. Regression analyses indicated that stress modulated the link between striatal GABA levels and functional plasticity in both the hippocampus and striatum during learning as measured with fMRI. This study provides evidence for a role of GABA in the stress-induced modulation of striatal and hippocampal systems.

Role of Gamma-Aminobutyric Acid in the Antiepileptic Activity of Garcinia Mangostana Standardized Extract

Epilepsy is a neurodegenerative disorder characterized by recurrent seizure activity, accompanied by convulsions and loss of consciousness. The aim of the present study was to investigate the antiepileptic activity of GML in mice using MES- and INH-induced models. Estimation of brain GABA levels and in vitro antioxidant potential was also evaluated. Treatment of mice with GML significantly reversed the MES-induced convulsions, which was reflected by the decrease in the duration (in seconds) of all the phases, with an increment in the GABA levels. In the INH model, animals treated with test drug exhibited a significant delay in the onset (in minutes) of clonic convulsions, and a decrease in the duration (in minutes) of clonic convulsions. GML had a dose dependent positive effect on GABAergic neurotransmission that was evident by a significant increase in the brain GABA levels. GML also exhibited significant free radical scavenging (DPPH•), reducing power, and hydroxyl radical scavenging activity. Put together, the data from the current study suggests that GML has significant antiepileptic potential, modulated through positive GABAergic neurotransmission and antioxidant properties.

Intact procedural learning and motor intracortical inhibition in adult neurofibromatosis type 1 gene carriers

ObjectiveNeurofibromatosis type 1 (NF1)1NF1 Neurofibromatosis type 11 is known to cause learning deficits in affected individuals. There has been evidence linking altered gamma-aminobutyric acid (GABA)2GABA Gamma-aminobutyric acid2 mediated inhibition to learning impairments in rodent models and humans with NF1. Still, evidence on the role of GABA in learning deficits associated with NF1 is inconclusive. MethodsWe examined procedural learning and motor cortex excitability through intracortical facilitation and short interval intracortical inhibition and its activity dependent modulation while performing a procedural sequence learning task in 16 asymptomatic NF1 gene carriers. We aimed to analyze potential brain-behavior correlations in a carefully selected sample of gene carriers in order to minimize confounding factors. ResultsGene carriers did not differ from healthy controls when learning the task with their non-dominant hand over three days of training. Electrophysiological data did not reveal alterations in patients’ inhibitory function of the motor cortex. ConclusionsIn contrast with previous publications reporting various cognitive deficits in clinically asymptomatic individuals with NF1, here asymptomatic gene carriers did not show major neuropsychological or behavioral abnormalities. SignificanceOur results support the concept that gene carriers may not always be impaired by the condition and the population of individuals with NF1 most likely comprises different subgroups according to patients’ phenotype severity.

Exercise Ameliorates Fluoride-induced Anxiety- and Depression-like Behavior in Mice: Role of GABA

Fluoride exposure caused anxiety- and depression-like behavior in mice. Meanwhile, exercise contributes to relieve anxiety and depression. However, the effects of exercise on anxiety- and depression-like behavior in fluorosis mice remain unclear. In the current study, thirty-six Institute of Cancer Research (ICR) female mice were randomly assigned to four groups: control group (C, gavage with distilled water); exercise group (E, gavage with distilled water and treadmill exercise (speed, 10 m/min; time, 30 min/day)); fluoride group (F, gavage with 24 mg/kg sodium fluoride (NaF)); and exercise plus fluoride group (EF, gavage with 24 mg/kg NaF and treadmill exercise). All treatments lasted for 8 weeks. A number of entries into and time spent in the open zone in the elevated zero maze (EZM), resting time in the tail suspension test (TST) and levels of serotonin (5-HT) and gamma-aminobutyric acid (GABA), were significantly altered in F when compared to C. Meanwhile, the anxiety-like behavior in the EZM and the depression-like behavior in the TST were significantly improved in EF when compared to group F. Exercise significantly enhanced fluoride-induced low GABA level, with less effect on the concentration of 5-HT. Moreover, the mRNA and protein expressions of GABA synthesis and transport-related proteins of glutamic acid decarboxylase (GAD) 65 and GAD67 and vesicular GABA transporter (VGAT) were all strikingly decreased in F, while those in EF were increased. In conclusion, exercise ameliorates anxiety- and depression-like behavior in fluorosis mice through increasing the expressions of GABA synthesis and transport-related proteins, rather than 5-HT system.

Патофізіологічні механізми розвитку епілепсії та особливості епілептогенезу в незрілому мозку

The article is devoted to the urgent problem of neonatology and pediatric neurology — seizures in newborns and young children. The work analyzes the scientific literature on the pathogenetic mechanisms of the development of the epileptic process, which is based on the anatomical and physiological mechanisms of the functioning of brain cells, in particular, in newborns and young children. New pathophysiological data on the increased excitability of the developing brain are described. It has been shown that the implementation of the mechanism of increased excitability of the fetal brain may be due to the peculiarities of the functioning of NMDA, AMPA, kainate receptors, and the peculiarities of the localization of ion channels in different brain structures. The paradoxical (exciting, depolarizing) role of gamma-aminobutyric acid, which is due to the peculiarities of the activation of chlorine co-transporters, is emphasized. The features of the epileptic process in newborns and young children have been determined. The reasons for the development of seizures in newborns are emphasized. The classification and clinical phenotypes of neonatal seizures are considered. It is emphasized that the convulsions in newborns rarely have a deployed clinical picture and are often represented by abortive or focal seizures, which is associated with the ontogenetic features of the fetal brain, namely: incomplete by the time of the birth of a cortical-neural organization, synaptogenesis and myelination of its structures, insufficiency of the development of commulectral intermetrous bonds , uneven representation in the cortex of ion channels with a relatively well-formed limbico-reticular system and its bond with a brain barrel. It was noted that despite various clinical manifestations, the newborn has four main types of seizures: subtitle (erased, abortive, fragmentary), tonic, clonic and myocloniс. No conflict of interest was declared by the authors. Key words: newborn, brain, pathophysiology, seizures, epilepsy, review.

Gamma-aminobutyric acid attenuates insulin resistance in type 2 diabetic patients and reduces the risk of insulin resistance in their offspring

The role of gamma-aminobutyric acid (GABA) in attenuates insulin resistance (IR) in type 2 diabetic (T2D) patients and the reduction of the risk of IR in their offspring, and the function of GLUT4, IRS1 and Akt2 genes expression were investigated. T2D was induced by high fat diet and 35 mg/kg of streptozotocin. The male and female diabetic rats were then divided into three groups: CD, GABA, and insulin. NDC group received a normal diet. All the animals were studied for a six-month. Their offspring were just fed with normal diet for four months. Blood glucose was measured weekly in patients and their offspring. Intraperitoneal glucose tolerance test (IPGTT), urine volume, and water consumption in both patients and their offspring were performed monthly. The hyperinsulinemic euglycemic clamp in both patients and their offspring was done and blood sample collected to measure Hemoglobin A1c (HbA1c). IRS1, Akt and GLUT4 gene expressions in muscle were evaluated in all the groups. GABA or insulin therapy decreased blood glucose, IPGTT, and HbA1c in patients and their offspring compared to DC group. They also increased GIR in patients and their offspring. IRS1, Akt and GLUT4 gene expressions improved in both patients in comparison with DC group. GABA exerts beneficial effects on IRS1 and Akt gene expressions in GABA treated offspring. GABA therapy improved insulin resistance in diabetic patients by increasing the expression of GLUT4. It is also indirectly able to reduce insulin resistance in their offspring possibly through the increased gene expressions of IRS1 and Akt.

Insulin resistance and the role of gamma-aminobutyric acid.

Insulin resistance (IR) is mentioned to be a disorder in insulin ability in insulin-target tissues. Skeletal muscle (SkM) and liver function are more affected by IR than other insulin target cells. SkM is the main site for the consumption of ingested glucose. An effective treatment for IR has two properties: An inhibition of β-cell death and a promotion of β-cell replication. Gamma-aminobutyric acid (GABA) can improve beta-cell mass and function. Multiple studies have shown that GABA decreases IR probably via increase in glucose transporter 4 (GLUT4) gene expression and prevention of gluconeogenesis pathway in the liver. This review focused on the general aspects of IR in skeletal muscle (SkM), liver; the cellular mechanism(s) lead to the development of IR in these organs, and the role of GABA to reduce insulin resistance.

A motogenic GABAergic system of mononuclear phagocytes facilitates dissemination of coccidian parasites.

Gamma-aminobutyric acid (GABA) serves diverse biological functions in prokaryotes and eukaryotes, including neurotransmission in vertebrates. Yet, the role of GABA in the immune system has remained elusive. Here, a comprehensive characterization of human and murine myeloid mononuclear phagocytes revealed the presence of a conserved and tightly regulated GABAergic machinery with expression of GABA metabolic enzymes and transporters, GABA-A receptors and regulators, and voltage-dependent calcium channels. Infection challenge with the common coccidian parasites Toxoplasma gondii and Neospora caninum activated GABAergic signaling in phagocytes. Using gene silencing and pharmacological modulators in vitro and in vivo in mice, we identify the functional determinants of GABAergic signaling in parasitized phagocytes and demonstrate a link to calcium responses and migratory activation. The findings reveal a regulatory role for a GABAergic signaling machinery in the host-pathogen interplay between phagocytes and invasive coccidian parasites. The co-option of GABA underlies colonization of the host by a Trojan horse mechanism.

The influence of laser beam and high light intensity on lentil (Lens culinaris) and wheat (Triticum aestivum) seedlings growth and metabolism

Light is considered as an environmental signal that controls plants growth and development. Sufficient duration, quality and wavelength are mainly responsible for switching on/off many physiological processes. The aim of this study was to examine the role of gamma aminobutyric acid (GABA) shunt pathway specific response in wheat (Triticum aestivum) and lentil (Lens culinaris) seedlings to blue LED laser (intensity= 1.48 W/cm2) and high intensity invisible ultraviolet light (intensity= 3.99 W/cm2) treatments separately, with respect to: seed germination, seedling growth, oxidative damage in term of reactive oxygen substances accumulation, GABA accumulation level, total proteins and total carbohydrates level and glutamate decarboxylase gene (GAD) expression. Data showed a remarkable changes in proteins content, carbohydrates content, chlorophyll level, dry and fresh weight, GABA accumulation, MDA level, and GAD m-RNA level under blue LED laser and high intensity invisible ultraviolet light treatments; separately in the both wheat and lentil cultivars. There were no significant differences of root emergence in all cultivars under all treatments. The concentrations of MDA increased in all cultivars under blue LED laser and high intensity invisible ultraviolet light treatments with increasing exposure durations. GABA levels increased and correlated significantly in all cultivars as the exposure duration of blue LED laser and high light intensity increased. Significant decrease in chlorophyll a and b contents in Um Qayes, Jordan1 and Jordan2 cultivars under all laser and high intensity invisible ultraviolet light treatments. A significant difference was found in proteins content in all cultivars in response to laser and high intensity invisible ultraviolet light treatments. Carbohydrates content in all cultivars used in this study were significantly decreased under laser treatments. The transcription level of GAD increased significantly under blue LED laser and high intensity invisible ultraviolet light in all cultivars used in this study. GAD expression was high in Hurani75 cultivar in agreement with the low level of GABA accumulation under high intensity invisible ultraviolet light at 60 min which strongly suggested that GABA was catabolized to enter another pathways (C:N balance) that was confirmed by increase in higher level of carbohydrates and proteins beside reduction in MDA content at the same exposure duration. On other hand, GAD expression in Jordan 2 was lower in response to laser treatment under the same exposure duration. The high increase of GAD gene expression explains the high accumulation of GABA level under both treatments. Results indicated that GABA shunt is a key metabolic pathway that allows wheat and lentil to adapt blue LED laser and high intensity invisible ultraviolet light stressful treatments.

Induction of γ-aminobutyric acid plays a positive role to Arabidopsis resistance against Pseudomonas syringae.

Gamma‐aminobutyric acid (GABA) is an important metabolite which functions in plant growth, development, and stress responses. However, its role in plant defense and how it is regulated are largely unknown. Here, we report a detailed analysis of GABA induction during the resistance response to Pseudomonas syringae in Arabidopsis thaliana. While searching for the mechanism underlying the pathogen‐responsive mitogen‐activated protein kinase (MPK)3/MPK6 signaling cascade in plant immunity, we found that activation of MPK3/MPK6 greatly induced GABA biosynthesis, which is dependent on the glutamate decarboxylase genes GAD1 and GAD4. Inoculation with Pseudomonas syringae pv tomato DC3000 (Pst) and Pst‐avrRpt2 expressing the avrRpt2 effector gene induced GAD1 and GAD4 gene expression and increased the levels of GABA. Genetic evidence revealed that GAD1, GAD2, and GAD4 play important roles in both GABA biosynthesis and plant resistance in response to Pst‐avrRpt2 infection. The gad1/2/4 triple and gad1/2/4/5 quadruple mutants, in which the GABA levels were extremely low, were more susceptible to both Pst and Pst‐avrRpt2. Functional loss of MPK3/MPK6, or their upstream MKK4/MKK5, or their downstream substrate WRKY33 suppressed the induction of GAD1 and GAD4 expression after Pst‐avrRpt2 treatment. Our findings shed light on both the regulation and role of GABA in the plant immunity to a bacterial pathogen.

Baseline sensorimotor GABA levels shape neuroplastic processes induced by motor learning in older adults.

Previous research in young adults has demonstrated that both motor learning and transcranial direct current stimulation (tDCS) trigger decreases in the levels of gamma‐aminobutyric acid (GABA) in the sensorimotor cortex, and these decreases are linked to greater learning. Less is known about the role of GABA in motor learning in healthy older adults, a knowledge gap that is surprising given the established aging‐related reductions in sensorimotor GABA. Here, we examined the effects of motor learning and subsequent tDCS on sensorimotor GABA levels and resting‐state functional connectivity in the brains of healthy older participants. Thirty‐six older men and women completed a motor sequence learning task before receiving anodal or sham tDCS to the sensorimotor cortex. GABA‐edited magnetic resonance spectroscopy of the sensorimotor cortex and resting‐state (RS) functional magnetic resonance imaging data were acquired before and after learning/stimulation. At the group level, neither learning nor anodal tDCS significantly modulated GABA levels or RS connectivity among task‐relevant regions. However, changes in GABA levels from the baseline to post‐learning session were significantly related to motor learning magnitude, age, and baseline GABA. Moreover, the change in functional connectivity between task‐relevant regions, including bilateral motor cortices, was correlated with baseline GABA levels. These data collectively indicate that motor learning‐related decreases in sensorimotor GABA levels and increases in functional connectivity are limited to those older adults with higher baseline GABA levels and who learn the most. Post‐learning tDCS exerted no influence on GABA levels, functional connectivity or the relationships among these variables in older adults.