Glutamic Decarboxylase Research Articles

Controlled atmosphere storage alleviates the browning of walnut (Juglans regia L.) fruit through enhancing GABA-mediated energy metabolism

Browning is the primary physiological damage that shortens the postharvest life and deteriorates the quality of stored fruits. Controlled atmosphere (CA) storage has been shown to be effective in alleviating the browning of ‘Xifu 1′ in-hull walnut; however, its alleviation mechanism is less understood. To further explore the effect and regulatory mechanism of CA on the browning of fresh in-hull walnut, we stored four varieties of in-hull walnuts under CA-treated (5% O2 + 7.5% CO2) and untreated conditions at 0 ± 0.5 °C with 70–80% relative humidity for 70 d. The indicators related to browning and γ-aminobutyric acid (GABA) metabolism were measured until 56 d of storage. The results showed that the CA significantly increased GABA levels by maintaining higher activities of glutamate decarboxylase (GAD), GABA transaminase (GABAT) and succinate dehydrogenase (SDH). This reduced the changes in the browning index (BI), color values, and respiration rate (RR) of the four walnut fruit varieties compared with controls during storage. Consistent with the active GABA metabolism, higher energy charge (EC) and adenosine triphosphate (ATP), succinic acid (SA), malic acid (MLA), fumaric acid (FA), and citric acid (CTA) contents were also observed in the CA-treated walnut hull compared to the controls. The epicarp degradation of the CA-treated ‘Xifu 1′ walnut fruit occurred later, and their mitochondria and cells maintained better integrity compared to the controls. Among the differentially expressed genes (DEGs) screened via RNA-Sequencing (RNA-Seq), 32 were annotated as part of the citrate cycle (TCA cycle) pathway, and 27 were annotated in the GABA metabolism pathway. Real-time quantitative PCR (RT-qPCR) analysis showed that eight candidate genes were closely related to the effect of CA on the synthesis, transport, and transformation of GABA. In conclusion, CA effectively controlled the browning of different varieties of fresh in-hull walnuts by enhancing GABA metabolism and maintaining energy balance.

Genetic Circuits for Feedback Control of Gamma-Aminobutyric Acid Biosynthesis in Probiotic Escherichia coli Nissle 1917.

Engineered microorganisms such as the probiotic strain Escherichia coli Nissle 1917 (EcN) offer a strategy to sense and modulate the concentration of metabolites or therapeutics in the gastrointestinal tract. Here, we present an approach to regulate the production of the depression-associated metabolite gamma-aminobutyric acid (GABA) in EcN using genetic circuits that implement negative feedback. We engineered EcN to produce GABA by overexpressing glutamate decarboxylase and applied an intracellular GABA biosensor to identify growth conditions that improve GABA biosynthesis. We next employed characterized genetically encoded NOT gates to construct genetic circuits with layered feedback to control the rate of GABA biosynthesis and the concentration of GABA produced. Looking ahead, this approach may be utilized to design feedback control of microbial metabolite biosynthesis to achieve designable smart microbes that act as living therapeutics.

Selenium treatment alters the accumulation of osmolytes in arsenic-stressed rice (Oryza sativa L.).

Arsenic (As), one of the major pollutants in the soil, is an important environmental concern as its consumption can cause adverse health symptoms in living organisms. Its contamination of rice grown over As-contaminated areas is a serious concern in South Asian countries. Selenium (Se) has been reported to influence various osmolytes under metal stress in plants. The present study reports the role of Se in mitigating As stress in rice by modulating osmolyte metabolism. Rice plants grown in As-amended soil (2.5-10mgkg-1) in pots were treated with sodium selenate (0.5-1.0mg Se kg-1 soil) in glass house conditions and leaf samples were collected at 60 and 90days after sowing (DAS). As-treated rice leaves displayed a reduction in relative water content (RWC) and dry weight than control with a maximum reduction of 1.68- and 2.47-fold in RWC and 1.95- and 1.69-fold in dry weight in As10 treatment at 60 and 90 DAS, respectively. Free amino acids (1.38-2.26-fold), proline (3.88-3.93-fold), glycine betaine (GB) (1.27-1.72-fold), choline (1.67-3.1-fold), total soluble sugars (1.29-1.61-fold), and reducing sugars (1.67-2.19-fold) increased in As-treated rice leaves as compared to control at both stages. As stress increased the γ-aminobutyric acid (GABA), putrescine content, and glutamate decarboxylase activity whereas diamine oxidase and polyamine oxidase activities declined by 1.69-1.88-fold and 1.52-1.86-fold, respectively. Se alone or in combination with As improved plant growth, RWC, GB, choline, putrescine, and sugars; lowered proline and GABA; and showed a reverse trend of enzyme activities related to their metabolism than respective As treatments. As stress resulted in a higher accumulation of osmolytes to combat its stress which was further modulated by the Se application. Hence, the current investigation suggested the role of osmoprotectants in Se-induced amelioration of As toxicity in rice plants.

Management of autoimmune temporal lobe epilepsy with GAD65 antibody: four case reports.

Glutamate decarboxylase (GAD) enzyme can be a target intracellular antigen in autoimmune focal epilepsy. GAD65 antibody is in found patients diagnosed with drug-refractory temporal lobe epilepsy (TLE). We explore the clinical features of the disease and therapeutic options. We present the cases of four TLE patients, two of them with type 1 diabetes. All of them were drug-resistant and therefore underwent presurgical evaluation, which revealed GAD65 antibody positivity. We discuss the four GAD65 antibody positive temporal lobe epilepsy patients' electroclinical data, the treatments, and their effectiveness. One of them became seizure-free after right anterior temporal lobe resection, two of them did not show significant improvement with immunmodulatory agents, and the fourth patient with the shortest duration of disease had significant improvement in seizure status and normalisation of cognitive status with IVIg therapy. Our cases show that the earlier a GAD65 antibody is detected, the greater the chance of achieving seizure freedom or improvements in both seizure and cognitive status with immunomodulatory agents. However, in some cases, surgery may also bring seizure freedom, but with a risk of cognitive deterioration.

Dorsomedial Ventromedial Hypothalamic Nucleus Growth Hormone-Releasing Hormone Neuron Steroidogenic Factor-1 Gene Targets in Female Rat.

The prospect that the ventromedial hypothalamic nucleus (VMN) transcription factor steroidogenic factor-1/NR5A1 (SF-1) may exert sex-dimorphic control of glucose counterregulation is unresolved. Recent studies in male rats show that SF-1 regulates transcription of co-expressed hypoglycemia-sensitive neurochemicals in dorsomedial VMN growth hormone-releasing hormone (Ghrh) neurons. Gene knockdown and laser-catapult-microdissection/single-cell multiplex qPCR techniques were used here in a female rat model to determine if SF-1 control of Ghrh neuron transmitter marker, energy sensor, and estrogen receptor (ER) variant mRNAs varies according to sex. Data show that in females, hypoglycemia elicits a gain of SF-1 inhibitory control of VMNdm Ghrh neuron Ghrh and Ghrh-receptor gene profiles and loss of augmentation of glutaminase transcription; SF-1 gene silencing diminished eu- and hypoglycemic patterns of neuronal nitric oxide gene transcription. SF-1 imposes divergent control of baseline and hypoglycemic glutamate decarboxylase65 (GAD)-1 (stimulatory) versus GAD2 (inhibitory) mRNAs in that sex. SF-1 stimulates baseline VMNdm Ghrh neuron PRKAA1/AMPKα1 and PRKAA2/AMPKα2 gene expression, yet causes opposite changes in these gene profiles during hypoglycemia. SF-1 exerts glucose-dependent control of ER-alpha and G-protein-coupled ER-1 transcription, but blunts ER-beta gene profiles during eu- and hypoglycemia. In females, SF-1 knockdown did not affect hypercorticosteronemia or hyperglucagonemia, but blunted hypoglycemic suppression of growth hormone secretion. Results show that SF-1 expression is critical for female rat VMNdm Ghrh neuron counterregulatory neurochemical, AMPK catalytic subunit, and ER gene transcription responses to hypoglycemia. Sex differences in direction of SF-1 control of distinctive gene profiles may result in observed disparities in SF-1 regulation of counterregulatory hormone secretion between sexes.

The metabolism of amino acids, AsA and abscisic acid induced by strigolactone participates in chilling tolerance in postharvest zucchini fruit.

Zucchini fruit are notably susceptible to chilling injury when stored at low temperatures. The purpose of this experimental investigation was to assess the influence of strigolactone (ST) (5 μmol L-1) on mitigating chilling injury and the metabolic changes in amino acids, ascorbic acid, and abscisic acid in zucchini fruit stored at 4°C. Research findings demonstrated that ST-treated zucchini fruit displayed a significantly higher tolerance to chilling stress compared to the control group. Postharvest ST treatment led to a decrease in weight loss, accompanied by reduced levels of malondialdehyde and relative ion leakage compared to the untreated group. ST immersion significantly boosted the metabolic pathways associated with proline and arginine, affecting both the enzymatic reactions and gene expressions, thus cumulatively increasing the internal concentrations of these amino acids in zucchini fruit. Zucchini treated with ST exhibited an increased concentration of γ-aminobutyric acid (GABA) as a result of augmented activities and elevated transcriptional levels of glutamate decarboxylase (GAD), GABA transaminase (GAT), and succinate semialdehyde dehydrogenase (SSD). In the ST-treated sample, the elevated enzymatic activities and enhanced gene expressions within the ascorbic acid (AsA) biosynthesis pathway worked together to sustain AsA accumulation. The application of ST resulted in a rise in abscisic acid (ABA) concentration, which correspondingly correlated with the induction of both activities and gene expression levels of crucial enzymes involved in ABA metabolism. Our findings revealed that submerging zucchini fruit in ST could be a highly effective strategy for boosting their chilling tolerance. The alleviation in chilling injury induced by ST may be attributed to the modulation of proline, arginine, GABA, AsA and ABA metabolism.

Stiff-person syndrome

Stiff-person syndrome is a rare autoimmune disorder manifested by stiffness in the trunk and proximal limb muscles and painful muscle spasms in them. The disease is associated with the production of glutamate decarboxylase autoantibodies, an enzyme converting glutamate into gamma-aminobutyric acid. An increase of anti-GAD antibody serum levels above 10.000 IU/mL is specific for stiff-person syndrome. Our own clinical observation of a patient diagnosed with stiff-person syndrome is presented.

Changes in Protein-Related Enzyme Activities, Concentrations of GABA and Nitrogen-Containing Constituents of Vigna Radiata L. Seeds Germinated under Different Circumstances

Germination is one of the most important techniques to enhance the nutrients and functionality of legume seeds. This academic work investigated the effects of pre-treatment with acidifying soaking water and germination time on changes in concentrations of gamma-aminobutyric acid (GABA) and nitrogenous constituents, and protein-related enzyme activities in mung bean seeds. Higher amounts of crude protein, non-protein nitrogenous, free amino acids, and enzyme activities, but lower protein nitrogenous concentrations were found when soaking in more acidic water and germinating at longer germination time. Steeping water of pH 5.5 and germination duration of 8 h induced mung bean seeds to manifest the highest activities of glutamate decarboxylase (GAD) (60.9 U/g powder, db) and protease (2.81 U/g powder, db), responsible for the highest values of GABA (1.60 g/kg, db), free amino acids (5.92 g/kg, db) and non-protein nitrogen (14.7 g/kg, db), and the lowest amount of protein nitrogen (30.8 g/kg, db). These findings indicate that pre-treatment with acidic soaking water before germinating was more likely to enrich the GABA and amino acid-containing compounds of the mung bean seeds.

Glycated haemoglobin, HOMA2-B, C-peptide to glucose ratio and type 2 diabetes clusters as predictors for therapy failure in individuals with type 2 diabetes without insulin therapy: A registry analysis.

Some people with type 2 diabetes mellitus (T2D) and declining β-cell function do require insulin over time. Various laboratory parameters, indices of glucose metabolism or phenotypes of T2D (clusters) have been suggested, which might predict future therapy failure (TF), indicating the need for insulin therapy initiation. This analysis evaluated glycated haemoglobin (HbA1c), homeostatic model assessment (HOMA)2-B, C-peptide to glucose ratio (CGR) and diabetes clusters as predictive parameters for the occurrence of glycaemic TF in individuals diagnosed with T2D without previous insulin therapy. In total, 159 individuals with T2D [41% female, median age 50 (IQR: 53-69) years, diabetes duration 9 (5-15) years], without insulin therapy were prospectively evaluated for the occurrence of a composite primary endpoint, including HbA1c increasing or remaining >8.0% (64 mmol/mol) 3 months after baseline on non-insulin glucose-lowering agents, insulin initiation or hospital admissions because of acute hyperglycaemic events. Diabetes clusters were formed according to previously described characteristics. Only severe autoimmune diabetes clusters were excluded because of a small amount of glutamate decarboxylase antibody-positive participants. The other clusters were distributed as mild age-related diabetes 33%; severe insulin-deficient diabetes 31%; mild obesity-related diabetes 20%; and severe insulin-resistant diabetes 15%. During a median observation of 57 months, higher tertiles of HbA1c at baseline, HOMA2-B, as well as a lower CGR were significantly predictive for the occurrence of the primary endpoint. The probability of meeting the primary endpoint was the highest for mild obesity-related diabetes [hazard ratio 3.28 (95% confidence interval 1.75-6.2)], followed by severe insulin-deficient diabetes [hazard ratio 2.03 (95% confidence interval 1.1-3.7)], mild age-related diabetes and the lowest for severe insulin-resistant diabetes. The best performance to predict TF with an area under the curve (AUC) of 0.77 was HbA1c at baseline, followed by HOMA2-B (AUC 0.69) and CGR (AUC 0.64). HbA1c, indices of insulin secretion capacity (HOMA2-B and CGR) and T2D clusters might be applicable tools to guide practitioners in the decision of whether insulin is required in people already diagnosed with T2D. These findings need to be validated in prospective studies.

Enhancement of γ-Aminobutyric Acid and the Characteristics of Nutrition and Function in White Quinoa through Ultrasound Stress at the Pre-Germination Stage.

The global production of quinoa has been increasing in recent years. In plant-based foods, ultrasound stress has received increasing attention, owing to its ability to enhance the production of primary and secondary metabolites. We studied the effects of ultrasonic stress at the pre-germination stage on the γ-aminobutyric acid (GABA) accumulation and characteristics of nutrition and function in quinoa. The results showed that ultrasonic conditions of 100 W for 4 min promoted an increase in GABA content by 9.15-fold, to 162.47 ± 6.69 mg/100 g·DW, compared to that of untreated quinoa, through promoting a 10.2% and 71.9% increase in the water absorption and glutamate decarboxylase activity of quinoa, respectively. Meanwhile, compared to untreated quinoa, ultrasonic stress at the pre-germination stage enhanced the total phenolic, total flavonoid, and total saponin contents of quinoa by 10.2%, 33.6%, and 90.7%, to 3.29 mg GA/g·DW, 104.0 mg RE/100 g·DW, and 7.13 mg/g, respectively, without decreasing its basic nutritional quality. Ultrasonic stress caused fissures on the surface of quinoa starch particles. Additionally, germination under ultrasonic stress increased the n3 polyunsaturated fatty acids by 14.4%. Furthermore, ultrasonic stress at the pre-germination stage promoted the scavenging of 2,2-diphenyl1-picrylhydrazyl radicals and inhibitions of α-amylase, α-glucosidase, and pancreatic lipase by 14.4%, 14.9%, 24.6%, and 20.0% in vitro, compared to untreated quinoa. The results indicated that the quinoa sprouted via ultrasonic stress could represent a promising method through which to develop nutritionally balanced whole grains rich in GABA, with hypoglycemic and hypolipidemic activities, which could provide theoretical support for the development of functional whole-grain foods based on quinoa.

Mepiquat chloride priming confers the ability of cotton seed to tolerate salt by promoting ABA-operated GABA signaling control of the ascorbate–glutathione cycle

BackgroundEnsuring that seeds germinate and emerge normally is a prerequisite for cotton production, esp. in areas with salinized soil. Priming with mepiquat chloride (MC) can promote seed germination and root growth under salt stress, but its mechanism has not been fully elucidated. In this study, physiological and biochemical experiments revealed that MC-priming promotes the tolerance of cotton seeds to salt stress by increasing the ability of antioxidant enzymes related to the ascorbate–glutathione (AsA-GSH) cycle to scavenge reactive oxygen species (ROS).ResultsResults revealed that treatment with inhibitors of abscisic acid (ABA) and γ-aminobutyric acid (GABA) biosynthesis reduced the positive effects of MC-priming. Similarly, MC-priming increased the contents of ABA and GABA under salt stress by stimulating the expression levels of GhNCED2 and GhGAD4 and the activity of calmodulin-binding (CML) glutamate decarboxylase (GAD). Further analysis showed that an inhibitor of ABA synthesis reduced the positive impacts of MC-priming on the content of GABA under salt stress, but the content of ABA was not affected by the GABA synthesis inhibitor. Furthermore, a multi-omics analysis revealed that MC-priming increased the abundance and phosphorylation levels of the proteins related to ABA signaling, CML, and Ca2+ channels/transporters in the MC-primed treatments, which resulted in increased oscillations in Ca2+ in the MC-primed cotton seeds under salt stress.ConclusionIn summary, these results demonstrate that MC-mediated ABA signaling operates upstream of the GABA synthesis generated by GAD by activating the oscillations of Ca2+ and then enhancing activity of the AsA-GSH cycle, which ensures that cotton seeds are tolerant to salt stress.

Evaluating the therapeutic potential of Indian traditional medicine against multidrug-resistant pathogens: a comprehensive approach with MALDI-TOF-MS and gc-MS analysis

Multidrug-resistant pathogens pose a significant and pressing global health threat. This study explores the therapeutic potential of Indian Traditional Medicine, particularly Yagya, as an innovative antimicrobial strategy rooted in the ancient Rig Veda traditions dating back to 7500 B.C. Our research uses advanced analytical techniques like GC-MS and MALDI-TOF to investigate Yagya’s antimicrobial properties against challenging Gram-positive and Gram-negative bacteria. Our study reveals proteomic insights into bacterial responses, including Glutamate Decarboxylase, EF-Tu, and Alpha-Hemolysin. Altered expression levels suggest significant impacts on bacterial survival, shedding light on the multifaceted mechanisms. By showcasing Yagya’s remarkable antimicrobial properties, it provides valuable proteomic insights into its mode of action. This study sets stage for future research to harness Indian Traditional Medicine in combatting microbial infections, especially those driven by multidrug-resistant pathogens. This research emphasises the importance of exploring alternative and complementary approaches in modern medicine to combat the global health crisis of antibiotic resistance.

Deletion of transcription factor Satb1 leads to disturbance in mice behavior through changes in the expression of genes-regulators of the excitive component of neurotransmission

The transcription factor Satb1 exhibits widespread expression in multiple tissues and different regions of the brain. Notable levels of expression are observed in the neocortex, the nucleus of the diagonal band, the amygdala, and the tegmental area. In the ventral midbrain, Satb1-positive neurons are only found in a small portion of the substantia nigra, the ventral tegmental area, and the retrorubral field, and none were detected in the inferior colliculus. The transcription factor Satb1 is highly expressed in interneurons labeled as SST+, CR+, and NPY+, but not VIP+ interneurons. In mice with the Satb1 mutation, incomplete eye opening and a constriction reflex were observed. Behavioral tests revealed that mice lacking Satb1 exhibited deficits in motor coordination, characterized by reduced mobility on flat bars and decreased grip strength on metal wires. In addition, these mice exhibited elevated levels of motor activity in novel environments and heightened anxiety in the light-dark test. Satb1-deficient males demonstrated proficiency in passive avoidance tests, while their female counterparts exhibited no significant difference in entrance time to the dark compartment between the reproduction and learning stages, indicating an impairment in the process of conditioned response formation. To investigate the expression patterns of genes encoding vital protein kinases and proteins associated with neurotransmission, we extracted total RNA from the cerebral cortex of adult males with an incomplete deletion of Satb1. Real-time PCR analysis was conducted, which revealed a higher expression level of the pik3ca, pik3cb, and pic3cg genes responsible for phosphoinositide-3-kinase isoforms in Satb1-deficient mice compared to wild-type mice. The expression levels of genes encoding protein kinase C (Prkce and Prkcg) as well as Ca2+/calmodulin-dependent protein kinase II (Camk2) were lower in comparison to wild-type mice. Satb1-deficient mice displayed notably higher expression levels of genes encoding NMDA receptor subunits (Grin1, Grin2a, and Grin2b), whereas the expression of Gria1 (encoding the Glua2 subunit of AMPA receptors responsible for Ca2+ receptor conductance) decreased. The influence on excitatory glutamate receptor expression can cause hyperexcitability in animals, particularly when inhibitory neurotransmission is suppressed due to decreased Gabra1 and Gad65/67 expression encoding the GABA(A) receptor and glutamate decarboxylase. In addition, the levels of expression for the Calb1, Calb2, and Pvalb genes responsible for encoding the calcium-binding proteins calbindin, calretinin, and parvalbumin decreased in comparison to the wild-type mice. Thus, a correlation was found between behavioral disturbances and expression of genes that encode proteins related to brain development and neurotransmission after deleting the Satb1 transcription factor. Satb1-deleted mice exhibited hyperexcitation and impaired motor activity due to impaired gene expression.

Physiology of γ-aminobutyric acid production by Akkermansia muciniphila.

Gut bacteria hold the potential to produce a broad range of metabolites that can modulate human functions, including molecules with neuroactive potential. One such molecule is γ-aminobutyric acid (GABA), the main inhibitory neurotransmitter of the central nervous system in animals. Metagenomic analyses suggest that the genomes of many gut bacteria encode glutamate decarboxylase (GAD), the enzyme that catalyzes GABA production. The genome of Akkermansia muciniphila, a mucin specialist and potential next-generation probiotic from the human gut, is predicted to encode GAD, suggesting a contributing role in GABA production in the human gut. In this study, A. muciniphila was grown in batch cultures with and without pH control. In both experiments, A. muciniphila was found to produce GABA as a response to acid (pH <5.5), although only when GABA precursors, either glutamate or glutamine, were present in the medium. Proteomic analysis comparing A. muciniphila grown with and without precursors at pH 4 did not show a difference in GAD expression, suggesting that it is expressed regardless of the presence of GABA precursors. To further investigate the function of A. muciniphila GAD, we heterologously expressed the gad gene (encoded by locus tag Amuc_0372) with a His tag in Escherichia coli and purified the GAD protein. Enzyme assays showed GAD activity in a pH range between 4 and 6, with the highest specific activity at pH 5 of 144 ± 16 µM GABA/min/mg. Overall, our results demonstrate the ability of A. muciniphila to produce GABA as an acid response and unravel the conditions under which GABA production in A. muciniphila occurs.IMPORTANCEAkkermansia muciniphila is considered to be a beneficial bacterium from the human gut, but the exact mechanisms by which A. muciniphila influences its host are not yet fully understood. To this end, it is important to identify which metabolites are produced and consumed by A. muciniphila that may contribute to a healthy gut. In the present study, we demonstrate the ability of A. muciniphila to produce γ-aminobutyric acid (GABA) when grown in an acidic environment, which often occurs in the gut. GABA is the major inhibitory neurotransmitter in the central nervous system and is present in the human gut. For this reason, it is considered an important bacterial metabolite. Our finding that A. muciniphila produces GABA in acidic environments adds to the growing body of understanding of its relationship with host health and provides an explanation on how it can survive acid stress in the human gut.

Transdermal Blood Sampling for C-Peptide Is a Minimally Invasive, Reliable Alternative to Venous Sampling in Children and Adults With Type 1 Diabetes.

C-peptide and islet autoantibodies are key type 1 diabetes biomarkers, typically requiring venous sampling, which limits their utility. We assessed transdermal capillary blood (TCB) collection as a practical alternative. Ninety-one individuals (71 with type 1 diabetes, 20 control; individuals with type 1 diabetes: aged median 14.8 years [interquartile range (IQR) 9.1-17.1], diabetes duration 4.0 years [1.5-7.7]; control individuals: 42.2 years [38.0-52.1]) underwent contemporaneous venous and TCB sampling for measurement of plasma C-peptide. Participants with type 1 diabetes also provided venous serum and plasma, and TCB plasma for measurement of autoantibodies to glutamate decarboxylase, islet antigen-2, and zinc transporter 8. The ability of TCB plasma to detect significant endogenous insulin secretion (venous C-peptide ≥200 pmol/L) was compared along with agreement in levels, using Bland-Altman. Venous serum was compared with venous and TCB plasma for detection of autoantibodies, using established thresholds. Acceptability was assessed by age-appropriate questionnaire. Transdermal sampling took a mean of 2.35 min (SD 1.49). Median sample volume was 50 µL (IQR 40-50) with 3 of 91 (3.3%) failures, and 13 of 88 (14.7%) <35 µL. TCB C-peptide showed good agreement with venous plasma (mean venous ln[C-peptide] - TCB ln[C-peptide] = 0.008, 95% CI [-0.23, 0.29], with 100% [36 of 36] sensitivity/100% [50 of 50] specificity to detect venous C-peptide ≥200 pmol/L). Where venous serum in multiple autoantibody positive TCB plasma agreed in 22 of 32 (sensitivity 69%), comparative specificity was 35 of 36 (97%). TCB was preferred to venous sampling (type 1 diabetes: 63% vs. 7%; 30% undecided). Transdermal capillary testing for C-peptide is a sensitive, specific, and acceptable alternative to venous sampling; TCB sampling for islet autoantibodies needs further assessment.

Efficient production of γ-aminobutyric acid using engineered Escherichia coli whole-cell catalyst

γ-Aminobutyric acid (GABA) has been widely used in the food, feed, pharmaceutical, and chemical industry fields. Previously, we developed a whole-cell catalyst capable of converting L-glutamate (L-Glu) into GABA by overexpressing the glutamate decarboxylase gene (gadz11) from Bacillus sp. Z11 in Escherichia coli BL21(DE3). However, to enhance cell permeability, a freeze-thaw treatment is required, and to enhance GADZ11 activity, pyridoxal 5′-phosphate (PLP) must be added to the reaction system. The aim of this study is to provide a more efficient approach for GABA production by engineering the recombinant E. coli above. First, the inducible expression conditions of the gadz11 in E. coli were optimized to 37 °C for 6 h. Next, an ideal engineered strain was produced via increasing cell permeability by overexpressing sulA and eliminating PLP dependence by constructing a self-sufficient system. Furthermore, an efficient whole-cell biocatalytic process was optimized. The optimal substrate concentration, cell density, and reaction temperature were 1.0 mol/L (the molecular ratio of L-Glu to L-monosodium glutamate (L-MSG) was 4:1), 15 and 37 °C, respectively. Finally, a whole-cell bioconversion procedure was performed in a 3-L bioreactor under optimal conditions. The strain could be reused for at least two cycles with GABA yield, productivity and conversion ratio of 206.2 g/L, 117.8 g/L/h and 100.0%, respectively. This is currently the highest GABA productivity from a mixture of L-Glu and L-MSG reported without the addition of cofactors or additional treatment of cells. This work demonstrates that the novel engineered E. coli strain has the potential for application in large-scale industrial GABA production.

Prolonged Zaleplon Treatment Increases the Expression of Proteins Involved in GABAergic and Glutamatergic Signaling in the Rat Hippocampus.

Zaleplon is a positive allosteric modulator of the γ-aminobutyric acid (GABA)A receptor approved for the short-term treatment of insomnia. Previous publications on zaleplon have not addressed the proteins involved in its mechanism of action but have mostly referred to behavioral or pharmacological studies. Since both GABAergic and glutamatergic signaling have been shown to regulate wakefulness and sleep, we examined the effects of prolonged zaleplon treatment (0.625 mg/kg for 5 days) on these systems in the hippocampus of male Wistar rats. Western blot and immunohistochemical analyses showed that the upregulated components of GABAergic signaling (glutamate decarboxylase, vesicular GABA transporter, GABA, and α1 subunit of the GABAA receptor) were accompanied by increased protein levels in the glutamatergic system (vesicular glutamate transporter 1 and NR1, NR2A, and NR2B subunits of N-methyl-d-aspartate receptor). Our results, showing that zaleplon enhances GABA neurotransmission in the hippocampus, were not surprising. However, we found that treatment also increased glutamatergic signaling. This could be the result of the downregulation of adenosine A1 receptors, important modulators of the glutamatergic system. Further studies are needed to investigate the effects of the zaleplon-induced increase in hippocampal glutamatergic neurotransmission and the possible involvement of the adenosine system in zaleplon's mechanism of action.

Spinal GABA transporter 1 contributes to evoked-pain related behavior but not resting pain after incision injury.

The inhibitory function of GABA at the spinal level and its central modulation in the brain are essential for pain perception. However, in post-surgical pain, the exact mechanism and modes of action of GABAergic transmission have been poorly studied. This work aimed to investigate GABA synthesis and uptake in the incisional pain model in a time-dependent manner. Here, we combined assays for mechanical and heat stimuli-induced withdrawal reflexes with video-based assessments and assays for non-evoked (NEP, guarding of affected hind paw) and movement-evoked (MEP, gait pattern) pain-related behaviors in a plantar incision model in male rats to phenotype the effects of the inhibition of the GABA transporter (GAT-1), using a specific antagonist (NO711). Further, we determined the expression profile of spinal dorsal horn GAT-1 and glutamate decarboxylase 65/67 (GAD65/67) by protein expression analyses at four time points post-incision. Four hours after incision, we detected an evoked pain phenotype (mechanical, heat and movement), which transiently ameliorated dose-dependently following spinal inhibition of GAT-1. However, the NEP-phenotype was not affected. Four hours after incision, GAT-1 expression was significantly increased, whereas GAD67 expression was significantly reduced. Our data suggest that GAT-1 plays a role in balancing spinal GABAergic signaling in the spinal dorsal horn shortly after incision, resulting in the evoked pain phenotype. Increased GAT-1 expression leads to increased GABA uptake from the synaptic cleft and reduces tonic GABAergic inhibition at the post-synapse. Inhibition of GAT-1 transiently reversed this imbalance and ameliorated the evoked pain phenotype.

Olanzapine Effects on Parvalbumin/GAD67 Cell Numbers in Layers/Subregions of Dorsal Hippocampus of Chronically Socially Isolated Rats.

Depression is linked to changes in GABAergic inhibitory neurons, especially parvalbumin (PV) interneurons, which are susceptible to redox dysregulation. Olanzapine (Olz) is an atypical antipsychotic whose mode of action remains unclear. We determined the effect of Olz on PV-positive (+) and glutamate decarboxylase 67 (GAD67) + cell numbers in the layers of dorsal hippocampus (dHIPP) cornu ammonis (CA1-CA3) and dentate gyrus (DG) subregions in rats exposed to chronic social isolation (CSIS), which is an animal model of depression. Antioxidative enzymes and proinflammatory cytokine levels were also examined. CSIS decreased the PV+ cell numbers in the Stratum Oriens (SO) and Stratum Pyramidale (SP) of dCA1 and dDG. It increased interleukin-6 (IL-6), suppressor of cytokine signaling 3 (SOCS3), and copper-zinc superoxide dismutase (CuZnSOD) levels, and it decreased catalase (CAT) protein levels. Olz in CSIS increased the number of GAD67+ cells in the SO and SP layers of dCA1 with no effect on PV+ cells. It reduced the PV+ and GAD67+ cell numbers in the Stratum Radiatum of dCA3 in CSIS. Olz antagonizes the CSIS-induced increase in CuZnSOD, CAT and SOCS3 protein levels with no effect on IL-6. Data suggest that the protective Olz effects in CSIS may be mediated by altering the number of PV+ and GAD67+ cells in dHIPP subregional layers.

Activation of dopamine 2 receptors modulates glutamate decarboxylases 65 and 67 during stroke recovery in mice

AbstractBackgroundsTreatment with levodopa enhances recovery of lost neurological functions in preclinical stroke models and patients. Here, we studied whether dopamine signaling modulates GABAergic neurotransmission in parvalbumin‐positive interneurons after experimental stroke.MethodsFollowing block randomization, mice were subjected to experimental stroke induced by photothrombosis (PT). Two days after the insult, mice were treated either with the D1 receptor antagonist by R(+)‐SCH‐23390 (0.1 mg/kg), the selective D1 receptor agonist (R)‐(+)‐SKF‐38393 hydrochloride (1 mg/kg), the D2 receptor agonist R(−)‐2,10,11‐trihydroxy‐N‐propyl‐noraporphine hydrobromide hydrate (TNPA) (1 mg/kg), the D2 receptor antagonist S‐(−)‐eticlopride hydrochloride (0.3 mg/kg), or vehicle (saline) by daily intraperitoneal injection for five consecutive days, respectively. Recovery of function was assessed by paw placement and foot fault test before and on Days 2 and 7 after surgery.ResultsMice treated with TNPA showed a statistically significant improvement of recovery compared to all other treatment conditions. Synthesis of gamma‐aminobutyric acid (GABA) was quantified by levels of full‐length and cleaved glutamate acid decarboxylase 67 and 65 (GAD65 and GAD67) in the peri‐infarct area and homotypic regions of the contralateral cortex. Compared to the other treatments, TNPA significantly reduced the level of the GAD67 isoform both in the ischemic and contralateral hemispheres. Levels of GAD65 were found significantly higher in the contralateral hemisphere in TNPA‐treated mice after PT accompanied by an increase in the 58 kDa‐truncated form.ConclusionOur results point toward reduced GABA synthesis in a D2 receptor‐mediated mechanism possibly contributing to counteract functional inhibition after stroke.