Comparing trophic position estimates using bulk and compound specific stable isotope analyses: applying new approaches to mackerel icefish Champsocephalus gunnari.

Quantifying the tropic position (TP) of an animal species is key to understanding its ecosystem function. While both bulk and compound-specific analyses of stable isotopes are widely used for this purpose, few studies have assessed the consistency between and within such approaches. Champsocephalus gunnari is a specialist teleost that predates almost exclusively on Antarctic krill Euphausia superba. This well-known and nearly constant trophic relationship makes C. gunnari particularly suitable for assessing consistency between TP methods under field conditions. In the present work, we produced and compared TP estimates for C. gunnari and its main prey using a standard bulk and two amino acid-specific stable isotope approaches (CSI-AA). One based on the difference between glutamate and phenylalanine (TPGlx-Phe), and the other on the proline-phenylalanine difference (TPPro-Phe). To do that, samples from C. gunnari, E. superba and four other pelagic invertebrate and fish species, all potential prey for C.gunnari, were collected off the South Orkney Islands between January and March 2019, analyzed using standard isotopic ratio mass spectrometry methods and interpreted following a Bayesian approach. Median estimates (CI95%) for C. gunnari were similar between TPbulk (3.6; CI95%: 3.0-4.8) and TPGlx-Phe(3.4; CI95%:3.2-3.6), and lower for TPPro-Phe (3.1; CI95%:3.0-3.3). TP differences between C. gunnari and E. superba were 1.4, 1.1 and 1.2, all compatible with expectations from the monospecific diet of this predator (ΔTP=1). While these results suggest greater accuracy for Glx-Phe and Pro-Phe, differences observed between both CSI-AA approaches suggests these methods may require further validation before becoming a standard tool for trophic ecology.

Biotin-tagged fluorescent probe for in situ visualization of γ-glutamyl transpeptidase in cancerous cells and tissues.

γ-Glutamyl transpeptidase (GGT), a cell-surface enzyme, is strongly implicated in mammalian malignancy growth and migration processes including human hepatocarcinogens. However, simply and conveniently detect of GGT on the cell membrane remains highly challenging. In this study, a biotin-tagged fluorescent probe Nap-biotin-glu was developed using glutamic acid, naphthalimide, and biotin as the reaction site, fluorescent reporter, and membrane-targeting group, which required only three steps. Colocalization fluorescence imaging and immunofluorescence analysis indicated that probe Nap-biotin-glu was successfully realized in situ visualizing of GGT on the cell membrane.Owing to the significant over-expressed GGT level in tumor, the probe was successfully applied to distinguish cancer tissues from adjacent normal tissues.

Prunella vulgaris-phytosynthesized platinum nanoparticles: Insights into nanozymatic activity for H2O2 and glutamate detection and antioxidant capacity.

Artificial nanozymes (enzyme-mimics), specifically metallic nanomaterials, have garnered significant attention recently due to their reduced preparation cost and enhanced stability in a wide range of environments. The present investigation highlights, for the first time, a straightforward green synthesis of biogenic platinum nanoparticles (PtNPs) from a natural resource, namely Prunella vulgaris (Pr). To demonstrate the effectiveness of the phytochemical extract as an effective reducing agent, the PtNPs were characterized by various techniques such as UV-vis spectroscopy, High-resolution Transmission electron microscopy (HR-TEM), zeta-potential analysis, Fourier-transform infrared spectroscopy (FTIR), and Energy dispersive spectroscopy (EDS). The formation of PtNPs with narrow size distribution was verified. Surface decoration of PtNPs was demonstrated with multitudinous functional groups springing from the herbal extract. To demonstrate their use as viable nanozymes, the peroxidase-like activity of Pr/PtNPs was evaluated through a colorimetric assay. Highly sensitive visual detection of H2O2 with discrete linear ranges and a low detection limit of 3.43 µM was demonstrated. Additionally, peroxidase-like catalytic activity was leveraged to develop a colorimetric platform to quantify glutamate biomarker levels with a high degree of selectivity, the limit of detection (LOD) being 7.00 µM. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) test was used to explore the scavenging nature of the PtNPs via the degradation of DPPH. Overall, the colorimetric assay developed using the Pr/PtNP nanozymes in this work could be used in a broad spectrum of applications, ranging from biomedicine and food science to environmental monitoring.

Glutamic Acid Modified Gold Nanorod Sensor for the Detection of Calcium ions in Neuronal Cells.

Calcium (Ca2+) ions play a crucial role in the functioning of neurons, governing various aspects of neuronal activity such as rapid modulation and alterations in gene expression. Ca2+ signaling has a significant impact on the development of diseases and the impairment of neuronal functions. Herein, the study reports a Ca2+ ion sensor in neuronal cells using a gold nanorod. The gold nanorod (GA-GNR) conjugated glutamic acid developed in the study was used as a nano-bio probe for the experimental and in vitro detection of calcium. The nanosensor is colloidally stable, preserves plasmonic properties, and shows good viability in neuronal cells, as well as promoting neuron cell line growth. The cytotoxicity and cell penetration of the nanosensor are studied using Raman spectroscopy, brightfield and darkfield microscopy imaging, and MTT assays. The quantification of Ca2+ ions in neuronal cells is determined by monitoring the surface plasmon resonance (SPR) of the GA-GNR. The change in the intensity profile in the presence of Ca2+ incubated neurons was effectively used to develop a portable prototype of an optical Ca2+ sensor, proposing it as a tool for neurodegenerative disease diagnosis and neuromodulation evaluation.

Non-targeted metabolomics identifies biomarkers in milk with high and low milk fat percentage.

Milk is widely recognized as an important food source with health benefits. Different consumer groups have different requirements for the content and proportion of milk fat; therefore, it is necessary to investigate the differential metabolites and their regulatory mechanisms in milk with high and low milk fat percentages (MFP). In this study, untargeted metabolomics was performed on milk samples from 13 cows with high milk fat percentage (HF) and 13 cows with low milk fat percentage (LF) using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS). Forty-eight potential differentially labeled compounds were screened using the orthogonal partial least squares-discriminant analysis (OPLS-DA) combined with the weighted gene co-expression network analysis (WGCNA) method. Amino acid metabolism was the key metabolic pathway with significant enrichment of L-histidine, 5-oxoproline, L-aspartic acid, and L-glutamic acid. The negative correlation with MFP differentiated the HF and LF groups. To further determine the potential regulatory role of these amino acids on milk fat metabolism, the expression levels of marker genes in the milk fat synthesis pathway were explored. It was noticed that L-histidine reduced milk fat concentration primarily by inhibiting the triglycerides (TAG) synthesis pathway. L-aspartic acid and L-glutamic acid inhibited milk fat synthesis through the fatty acid de novo and TAG synthesis pathways. This study provides new insights into the mechanism underlying milk fat synthesis and milk quality improvement.

Role of short germination and milling on physical properties, amino acid and metabolomic profiles of high amylose rice fractions.

Short germination is a process that can improve bioactive compounds in rice. This work aimed investigate the physical properties, phenolic compounds (PC), antioxidant activity and amino acids composition of husk + bran, brown and milled rice with high amylose content after short germination (16 h). α-amylase activity (Falling Number, FN) and enthalpy (ΔH) were unchanged (p < 0.05). RVA curve profiles were similar, even though after short germination and milling. Globally, metabolomics analysis identified 117 PC, in which 111 (bound), 104 (free) and 21 revealed in both extracts. p-Coumaric, trans-ferulic and ferulic acids were the most abundant PC revealed in all fractions. The portion husk + bran showed the highest level of total antioxidant activity (709.90 µmol TE) in both free and bound fractions. In terms of total amino acids, there was no statistical difference (p < 0.05) among non-germinated and germinated samples, contrary to free amino acids content. Glutamic acid (Glu) presented the highest values combining short germination and milling (1725-1900 mg/100 g) consequently, leads to higher value of GABA (12.21 mg/100 g). The combination of short germination and milling demonstrated a good strategy to improve the nutritional quality of rice, unless the thermal and pasting properties have been altered, contribute to potential health benefits on human nutrition.

Prefrontal GABA and glutamate-glutamine levels affect sustained attention.

Attention levels fluctuate during the course of daily activities. However, factors underlying sustained attention are still unknown. We investigated mechanisms of sustained attention using psychological, neuroimaging, and neurochemical approaches. Participants were scanned with functional magnetic resonance imaging (fMRI) while performing gradual-onset, continuous performance tasks (gradCPTs). In gradCPTs, narrations or visual scenes gradually changed from one to the next. Participants pressed a button for frequent Go trials as quickly as possible and withheld responses to infrequent No-go trials. Performance was better for the visual gradCPT than for the auditory gradCPT, but the 2 were correlated. The dorsal attention network was activated during intermittent responses, regardless of sensory modality. Reaction-time variability of gradCPTs was correlated with signal changes (SCs) in the left fronto-parietal regions. We also used magnetic resonance spectroscopy (MRS) to measure levels of glutamate-glutamine (Glx) and γ-aminobutyric acid (GABA) in the left prefrontal cortex (PFC). Glx levels were associated with performance under undemanding situations, whereas GABA levels were related to performance under demanding situations. Combined fMRI-MRS results demonstrated that SCs of the left PFC were positively correlated with neurometabolite levels. These findings suggest that a neural balance between excitation and inhibition is involved in attentional fluctuations and brain dynamics.

Orally Administered Bifidobacterium adolescentis Diminishes Serum Glutamate Concentration in Mice.

Several studies have described the contribution of glutamate-transforming microbiota to the development of chronic ailments. For instance, the blood concentration of glutamate is higher in some patients with fibromyalgia, chronic fatigue, and pain. Taking advantage of a naturally occurring strain of Bifidobacterium that is able to transform glutamate in γ-aminobutyric caid (GABA), B. adolescentis IPLA60004, we designed a placebo-controlled intervention to test if the presence of this GABA-producing bifidobacteria in mice was able to impact the concentration of glutamate in the blood in comparison with the administration of other strain of the same species lacking the genes of the glutamate decarboxylase (gad) cluster. Animals were fed every day with 8 log CFU of bacteria in a sterilized milk vehicle for 14 days. Samples from feces and blood were collected during this period, and afterwards animals were sacrificed, tissues were taken from different organs, and the levels of different metabolites were analyzed by ultrahigh-performance liquid chromatography coupled to mass spectrometry. The results showed that both bacterial strains orally administered survived in the fecal content, and animals fed B. adolescentis IPLA60004 showed a significant reduction of their glutamate serum concentration, while a nonsignificant decrease was observed for animals fed a reference strain, B. adolescentis LGM10502. The variations observed in GABA were influenced by the gender of the animals, and no significant changes were observed in different tissues of the brain. These results suggest that orally administered GABA-producing probiotics could reduce the glutamate concentration in blood, opening a case for a clinical trial study in chronic disease patients. IMPORTANCE This work presents the results of a trial using mice as a model that were fed with a bacterial strain of the species B. adolescentis, which possesses different active genes capable of degrading glutamate and converting it into GABA. Indeed, the bacterium is able to survive the passage through the gastric tract and, more importantly, the animals reduce over time the concentration of glutamate in their blood. The importance of this result lies in the fact that several chronic ailments, such as fibromyalgia, are characterized by an increase in glutamate. Our results indicate that an oral diet with this probiotic-type bacteria could reduce the concentration of glutamate and, therefore, reduce the symptoms associated with the excess of this neurotransmitter.

Event-related functional magnetic resonance spectroscopy.

Proton-Magnetic Resonance Spectroscopy (MRS) is a non-invasive brain imaging technique used to measure the concentration of different neurochemicals. "Single-voxel" MRS data is typically acquired across several minutes, before individual transients are averaged through time to give a measurement of neurochemical concentrations. However, this approach is not sensitive to more rapid temporal dynamics of neurochemicals, including those that reflect functional changes in neural computation relevant to perception, cognition, motor control and ultimately behaviour. In this review we discuss recent advances in functional MRS (fMRS) that now allow us to obtain event-related measures of neurochemicals. Event-related fMRS involves presenting different experimental conditions as a series of trials that are intermixed. Critically, this approach allows spectra to be acquired at a time resolution in the order of seconds. Here we provide a comprehensive user guide for event-related task designs, choice of MRS sequence, analysis pipelines, and appropriate interpretation of event-related fMRS data. We raise various technical considerations by examining protocols used to quantify dynamic changes in GABA, the primary inhibitory neurotransmitter in the brain. Overall, we propose that although more data is needed, event-related fMRS can be used to measure dynamic changes in neurochemicals at a temporal resolution relevant to computations that support human cognition and behaviour.

Study on Chemical Constituents of Panax notoginseng Leaves.

Panax notoginseng (Burk.) F. H. is a genuine medicinal material in Yunnan Province. As accessories, P. notoginseng leaves mainly contain protopanaxadiol saponins. The preliminary findings have indicated that P. notoginseng leaves contribute to its significant pharmacological effects and have been administrated to tranquilize and treat cancer and nerve injury. Saponins from P. notoginseng leaves were isolated and purified by different chromatographic methods, and the structures of 1-22 were elucidated mainly through comprehensive analyses of spectroscopic data. Moreover, the SH-SY5Y cells protection bioactivities of all isolated compounds were tested by establishing L-glutamate models for nerve cell injury. As a result, twenty-two saponins, including eight dammarane saponins, namely notoginsenosides SL1-SL8 (1-8), were identified as new compounds, together with fourteen known compounds, namely notoginsenoside NL-A3 (9), ginsenoside Rc (10), gypenoside IX (11), gypenoside XVII (12), notoginsenoside Fc (13), quinquenoside L3 (14), notoginsenoside NL-B1 (15), notoginsenoside NL-C2 (16), notoginsenoside NL-H2 (17), notoginsenoside NL-H1 (18), vina-ginsenoside R13 (19), ginsenoside II (20), majoroside F4 (21), and notoginsenoside LK4 (22). Among them, notoginsenoside SL1 (1), notoginsenoside SL3 (3), notoginsenoside NL-A3 (9), and ginsenoside Rc (10) showed slight protective effects against L-glutamate-induced nerve cell injury (30 µM).

Associations Between Habitual Dietary Behaviors and Glutamic Acid Levels in Human Milk.

BACKGROUND: Glutamic acid, an amino acid that exhibits umami taste, is utilized in Japanese food and is abundant in human milk. We examined the influence of maternal habitual eating behavior on glutamic acid concentration in human milk. RESEARCH AIM: To determine the association between maternal dietary behaviors at the end of pregnancy and the 1st month postpartum and glutamic acid concentration in colostrum and mature milk. METHOD: This was a prospective, correlational, one-group longitudinal study. Women aged 20-30 years during the third trimester of pregnancy (N = 30) consented to participate and completed the data collection. Dietary history questionnaires were used to measure food intake. Glutamic acid levels in whey from colostrum and mature milk and in plasma during late pregnancy and the first month postpartum were measured. Data were considered significant at p < .05. Basic statistics, correlation coefficients analysis, unpaired t test, and one-way analysis of variance were performed. RESULTS: Glutamic acid concentrations in human milk and plasma were found to be significantly associated with the consumption of several different foods. There was no association between glutamic acid concentrations in human milk and plasma or between glutamic acid concentrations in colostrum and mature milk. The glutamic acid content of mature milk differed by physical activity level (mild and moderate) during the first month postpartum (t [46] = 2.87, p < .01). CONCLUSION: There was no clear association between habitual dietary behavior and glutamic acid concentration in human milk. However, maternal factors other than diet may be important and require additional research.

Rapid and sensitive HPLC-MS/MS method for the quantification of dopamine, GABA, serotonin, glutamine and glutamate in rat brain regions after exposure to tobacco cigarettes.

Tobacco smoking is a preventable main cause of fatal diseases. Accurate measurements of the effects it has on neurotransmitters are essential in developing new strategies for smoking cessation. Moreover, measurements of neurotransmitter levels can aid in developing drugs that counteract the effects of smoking. The aim of this study is to develop and validate a fast, simultaneous and sensitive method for measuring the levels of neurotransmitters in rat brain after the exposure of tobacco cigarettes. The selected neurotransmitters include dopamine, GABA, serotonin, glutamine and glutamate. The method is based on high-performance liquid chromatography-tandem mass spectrometry. Chromatographic separation was achieved within 3 min using a Zorbax SB C18 column (3.0 × 100 mm, 1.8 µm particle size). The mobile phase consisted of HPLC-grade water and acetonitrile each containing 0.3% heptafluorobutyric acid and 0.5% formic acid at gradient conditions. The linear range was 0.015-0.07, 825-7,218, 140-520, 63.42-160.75 and 38.25 × 103 to 110.35 × 103  ng/ml for dopamine, GABA, serotonin, glutamine and glutamate, respectively. Inter- and intra-run accuracy were in the range 97.82-103.37% with a precision (CV%) of ≤0.90%. The results revealed that 4 weeks of cigarette exposure significantly increased neurotransmitter levels after exposure to tobacco cigarettes in various brain regions, including the hippocampus and the amygdala. This increase in neurotransmitters levels may in turn activate the nicotine dependence pathway.

Endogenous benzoic acid interferes with the signatures of amino acids and thiol compounds through perturbing N-methyltransferase, glutamate-cysteine ligase, and glutathione S-transferase activity in dairy products.

Endogenous benzoic acid causes adverse effects on individual health, but the potential mechanisms often remain elusive. The positive rate of benzoic acid in seventy-two goat milk samples in triplicate was 93.6 %, verifying the presence of endogenous benzoic acid. In this study, we investigated the differences in protein expression and metabolites among goat milk with different final concentrations of benzoic acid via combined proteomics and metabolomics (LOQ 3.25 to 56.63 µg L-1) analysis based on UHPLC-Q-Orbitrap HRMS. Integrated analysis showed that benzoic acid reduced the content of l-histidine (from 1.27 to 0.49 mg/L) and 1-methylhistidine (from 1.40 to 0.68 mg/L), due to the increase of benzoic acid (0-30 mg/L) concentration significantly reduced the level and activity of N-methyltransferase. Protein-metabolite interactions suggested that benzoic acid enhanced glutamate-cysteine ligase and glutathione S-transferase expression and affected l-glutamate (from 1.22 to 0.49 mg/L) and glutathione contents, eventually leading to the formation of off-flavors and oxidation of goat milk. Meanwhile, the level of l-phenylalanine (from 4.17 to 1.94 mg/L) and l-tyrosine (from 1.05 to 0.26 mg/L) progressively decreased with the increase of benzoic acid concentration, which had a deleterious effect on the nutritional value and flavor formation of goat milk. These findings clarified the mechanism by which low-dose benzoic acid negatively affects the nutritional quality and flavor formation of goat milk.

Microwave Irradiation and Glutamic Acid-Assisted Phytotreatment of Tannery and Surgical Industrial Wastewater by Sorghum.

We investigated how different doses of microwave irradiation (MR) affect seed germination in Sorghum, including the level of remediation against textile and surgical wastewater (WW) by modulating biochemical and morpho-physiological mechanisms under glutamic acid (GA) application. The experiment was conducted to determine the impact of foliar-applied GA on Sorghum under wastewater conditions. Plants were treated with or without microwave irradiation (30 s, 2.45 GHz), GA (5 and 10 mM), and wastewater (0, 25, 50, and 100). Growth and photosynthetic pigments were significantly decreased in plants only treated with various concentrations of WW. GA significantly improved the plant growth characteristics both in MR-treated and -untreated plants compared with respective controls. HMs stress increased electrolyte leakage (EL), hydrogen peroxide (H2O2), and malondialdehyde (MDA) content; however, the GA chelation significantly improved the antioxidant enzymes activities such as ascorbate oxidase (APX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) both in MR-treated and -untreated plants under WW stress compared with respective controls. The results suggested that the MR-treated plants accumulate higher levels of HMs under GA addition in comparison to the WW-only-treated and MR-untreated plants. The maximum increase in Cd accumulation was observed in the range of 14-629% in the roots, 15-2964% in the stems, and 26-4020% in the leaves; the accumulation of Cu was 18-2757% in the roots, 15-4506% in the stems, and 23-4605% in the leaves; and the accumulation of Pb was 13-4122% in the roots, 21-3588% in the stems, and 21-4990% in the leaves under 10 mM GA and MR-treated plants. These findings confirmed that MR-treated sorghum plants had a higher capacity for HMs uptake under GA and could be used as a potential candidate for wastewater treatment.

Breeding for improved protein fractions and free amino acids concentration in bovine milk.

Considerable resources are required to routinely measure detailed milk compositional traits. Hence, an insufficient volume of phenotypic data can hinder genetic progress in these traits within dairy cow breeding programmes. The objective of the present study was to quantify the opportunities for breeding for improved milk protein and free amino acid (FAA) composition by exploiting mid-infrared spectroscopy (MIRS) predictions routinely recorded from milk samples. Genetic parameters for protein fractions and FAA composition were estimated using 134,546 test-day records from 16,166 lactations on 9,572 cows using linear mixed models. Heritability of MIRS-predicted protein fractions ranged from 0.19 (α-lactalbumin) to 0.55 (ß-lactoglobulin A), while heritability of MIRS-predicted FAA ranged from 0.08 for glycine to 0.29 for glutamic acid. Genetic correlations among the MIRS-predicted FAA were moderate to strong ranging from -0.44 (aspartic acid and lysine) to 0.97 (glutamic acid and total FAA). Adjustment of the genetic correlations for the genetic merit of 24-h milk yield did not greatly affect the correlations. Results from the current study highlight the presence of exploitable genetic variation for both protein fractions and FAA in dairy cow milk. Besides, the direction of genetic correlations reveals that breeding programmes directly selecting for greater milk protein concentration carry with them favourable improvement in casein and whey fractions.

Protective effects of remote ischemic preconditioning against spinal cord ischemia-reperfusion injury in rats.

OBJECTIVES: We aimed to investigate the protective effect of remote ischemic preconditioning against spinal cord ischemia and find a clue to its mechanism by measuring glutamate concentrations in the spinal ventral horn. METHODS: Male Sprague-Dawley rats were divided into 5 groups (n = 6 in each group) as follows: sham; SCI (only spinal cord ischemia); RIPC/SCI (perform remote ischemic preconditioning before spinal cord ischemia); MK-801/RIPC/SCI (administer MK-801, N-methyl-D-aspartate receptor antagonist, before remote ischemic preconditioning); and MK-801/SCI (administer MK-801 without remote ischemic preconditioning). Remote ischemic preconditioning was achieved by brief limb ischemia 80 minutes before spinal cord ischemia. MK-801 (1 mg/kg, intravenous) was administered 60 minutes before remote ischemic preconditioning. The glutamate concentration in the ventral horn was measured by microdialysis for 130 minutes after spinal cord ischemia. Immunofluorescence was also performed to evaluate the expression of N-methyl-D-aspartate receptor 2B subunit in the ventral horn 130 minutes after spinal cord ischemia. RESULTS: The glutamate concentrations in the spinal cord ischemia group were significantly higher than in the sham group at all time points (P < .01). Remote ischemic preconditioning attenuated the spinal cord ischemia-induced glutamate increase. When MK-801 was preadministered before remote ischemic preconditioning, glutamate concentration was increased after spinal cord ischemia (P < .01). Immunofluorescence showed that remote ischemic preconditioning prevented the increase in the expression of N-methyl-D-aspartate receptor 2B subunit on the surface of motor neurons (P = .047). CONCLUSIONS: Our results showed that remote ischemic preconditioning prevented spinal cord ischemia-induced extracellular glutamate increase in ventral horn and suppressed N-methyl-D-aspartate receptor 2B subunit expression.

Highly selective and sensitive detection of glutamate by an electrochemical aptasensor.

An electrochemical aptamer-based sensor was developed for glutamate, the major excitatory neurotransmitter in the central nervous system. Determining glutamic acid release and glutamic acid levels is crucial for studying signal transmission and for diagnosing pathological conditions in the brain. Glutamic acid-selective oligonucleotides were isolated from an ssDNA library using the Capture-SELEX protocol in complex medium. The selection permitted the isolation of an aptamer 1d04 with a dissociation constant of 12 µM. The aptamer sequence was further used in the development of an electrochemical aptamer sensor. For this purpose, a truncated aptamer sequence named glu1 was labelled with a ferrocene redox tag at the 3'-end and immobilized on a gold electrode surface via Au-thiol bonds. Using 6-mercapto-1-hexanol as the backfill, the sensor performance was characterized by alternating current voltammetry. The glu1 aptasensor showed a limit of detection of 0.0013 pM, a wide detection range between 0.01 pM and 1 nM, and good selectivity for glutamate in tenfold diluted human serum. With this enzyme-free aptasensor, the highly selective and sensitive detection of glutamate was demonstrated, which possesses great potential for implementation in microelectrodes and for in vitro as well as in vivo monitoring of neurotransmitter release.

The role of neuronal excitation and inhibition in the pre-Bötzinger complex on the cough reflex in the cat.

Brainstem respiratory neuronal network significantly contributes to cough motor pattern generation. Neuronal populations in the pre-Bötzinger complex (PreBötC) represent a substantial component for respiratory rhythmogenesis. We studied the role of PreBötC neuronal excitation and inhibition on mechanically induced tracheobronchial cough in 15 spontaneously breathing, pentobarbital anesthetized adult cats (35 mg/kg, iv initially). Neuronal excitation by unilateral microinjection of glutamate analog d,l-homocysteic acid resulted in mild reduction of cough abdominal electromyogram (EMG) amplitudes and very limited temporal changes of cough compared with effects on breathing (very high respiratory rate, high amplitude inspiratory bursts with a short inspiratory phase, and tonic inspiratory motor component). Mean arterial blood pressure temporarily decreased. Blocking glutamate-related neuronal excitation by bilateral microinjections of nonspecific glutamate receptor antagonist kynurenic acid reduced cough inspiratory and expiratory EMG amplitude and shortened most cough temporal characteristics similarly to breathing temporal characteristics. Respiratory rate decreased and blood pressure temporarily increased. Limiting active neuronal inhibition by unilateral and bilateral microinjections of GABAA receptor antagonist gabazine resulted in lower cough number, reduced expiratory cough efforts, and prolongation of cough temporal features and breathing phases (with lower respiratory rate). The PreBötC is important for cough motor pattern generation. Excitatory glutamatergic neurotransmission in the PreBötC is involved in control of cough intensity and patterning. GABAA receptor-related inhibition in the PreBötC strongly affects breathing and coughing phase durations in the same manner, as well as cough expiratory efforts. In conclusion, differences in effects on cough and breathing are consistent with separate control of these behaviors.NEW & NOTEWORTHY This study is the first to explore the role of the inspiratory rhythm and pattern generator, the pre-Bötzinger complex (PreBötC), in cough motor pattern formation. In the PreBötC, excitatory glutamatergic neurotransmission affects cough intensity and patterning but not rhythm, and GABAA receptor-related inhibition affects coughing and breathing phase durations similarly to each other. Our data show that the PreBötC is important for cough motor pattern generation, but cough rhythmogenesis appears to be controlled elsewhere.

Pretreatment with Methylene Blue Protects Against Acute Seizure and Oxidative Stress in a Kainic Acid-Induced Status Epilepticus Model.

BACKGROUND The aim of the present study was to investigate the potential anticonvulsant effect of methylene blue (MB) in a kainic acid (KA)-induced status epilepticus (SE) model. The effects of MB on levels of oxidative stress and glutamate (Glu) also were explored. MATERIAL AND METHODS Sixty C57BL/6 mice were randomly divided into 5 equal-sized groups: (1) controls; (2) KA; (3) MB 0.5 mg/kg+KA; (4) MB 1 mg/kg+KA; and (5) vehicle+KA. The SE model was established by intra-amygdala microinjection of KA. Behavioral observations and simultaneous electroencephalographic records of the seizures in different groups were analyzed to determine the potential anticonvulsant effect of MB. The influences of MB on oxidative stress markers and glutamate were also detected to explore the possible mechanism. RESULTS MB afforded clear protection against KA-induced acute seizure, as measured by the delayed latency of onset of generalized seizures and SE, decreased percentage of SE, and increased survival rate in mice with acute epilepsy. MB markedly increased the latency to first onset of epileptiform activity and decreased the average duration of epileptiform events, as well as the percentage of time during which the epileptiform activity occurred. Administration of MB prevented KA-induced deterioration of oxidative stress markers and Glu. CONCLUSIONS MB is protective against acute seizure in SE. This beneficial effect may be at least partially related to its potent antioxidant ability and influence on Glu level.

The effects of low pH on the taste and amino acid composition of tiger shrimp.

Recent research has revealed that shrimp sensory quality may be affected by ocean acidification but we do not exactly know why. Here we conducted controlled pH exposure experiments on adult tiger shrimp, which were kept in 1000-L tanks continuously supplied with coastal seawater. We compared survival rate, carapace properties and flesh sensory properties and amino acid composition of shrimp exposed to pH 7.5 and pH 8.0 treatments for 28 days. Shrimp reared at pH 7.5 had a lower amino acid content (17.6% w/w) than those reared at pH 8.0 (19.5% w/w). Interestingly, the amino acids responsible for the umami taste, i.e. glutamate and aspartic acid, were present at significantly lower levels in the pH 7.5 than the pH 8.0 shrimp, and the pH 7.5 shrimp were also rated as less desirable in a blind quality test by 40 volunteer assessors. These results indicate that tiger shrimp may become less palatable in the future due to a lower production of some amino acids. Finally, tiger shrimp also had a lower survival rate over 28 days at pH 7.5 than at pH 8.0 (73% vs. 81%) suggesting that ocean acidification may affect both the quality and quantity of future shrimp resources.