Amino Acid Neurotransmitters In Brain Research Articles

A transcriptomics-based analysis of mechanisms involved in the sex-dependent effects of diazepam on zebrafish

Diazepam (DZP) is a universally detected emerging pollutant in aquatic ecosystems. Although the sex-dependent effects of DZP on fish have been properly established, the underlying mechanisms remain unclear. In this study, zebrafish of both sexes were separately exposed to DZP (8 μg/L) for 21 days, and the alteration of the behaviors, brain amino acid neurotransmitter contents, and transcriptomic profiles were investigated. Although DZP exposure showed a sedative effect on both sexes, significantly reduced cumulative duration of high mobility and willingness to encounter the opposite sex were only observed in females. However, DZP significantly enhanced the brain levels of glutamate and glutamine in males but not in females. Transcriptome analysis identified more different expression genes (DEGs) in females (322 up-regulated and 311 down-regulated) than in males (138 up-regulated genes and 38 down-regulated). The DEGs in both sexes were significantly enriched in the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway of the synaptic vesicle cycle, indicating a possible pathway for the sedative effects of DZP on zebrafish. DZP exhibited different or even opposing regulatory patterns on gene expression in the brains of females and males, providing some insights into its sex-dependent impacts on the behaviors and brain neurotransmitter contents in zebrafish. Moreover, enrichment analysis also suggested that DZP exposure may affect the oocyte maturation in female zebrafish, which highlights the need to study its reproductive and transgenerational toxicity to fish species.

The effects of hypothermia on glutamate and γ-aminobutyric acid metabolism during ischemia in monkeys: a repeated-measures ANOVA study

During an ischemic stroke, the brain releases various factors, including glutamate and γ-aminobutyric acid. Glutamate can cause neurotoxic effects through certain receptors and exacerbate neurological damage, while γ-aminobutyric acid as an inhibitory neurotransmitter can antagonize the excitotoxic effects of glutamate and enhance the tolerance of neurons to ischemia. Therefore, in this study, the content of amino acid neurotransmitters in brain tissue before ischemia, after 10 min of ischemia, hypothermic perfusion, and rewarming were analyzed by high-performance liquid chromatography-UV in an animal model of ischemic stroke generated by blocking the bilateral common carotid arteries of rhesus monkeys. The changes in amino acid neurotransmitters in the rhesus monkey brain during post-ischemia hypothermic perfusion and rewarming were investigated by statistical methods of repeated measures ANOVA, showing that the concentration change of glutamate had not only a temporal factor but also was influenced by temperature, and there was an interaction effect between the two. Time but not temperature affected the change in γ-aminobutyric acid concentration, and there was an interaction effect between the two. Accordingly, hypoperfusion exerts a protective effect during ischemia by inhibiting the release of excitatory amino acid neurotransmitters, while the antagonistic effect of GABA on Glu is not significant.

Optimization of Ultra-High-Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry Detection of Glutamine-FMOC Ad-Hoc Derivative by Central Composite Design

Glutamine (Gln) is converted to excitatory (glutamate, aspartate) and inhibitory (γ-amino butyric acid) amino acid neurotransmitters in brain, and is a source of energy during glucose deprivation. Current research utilized an Analytical Quality by Design approach to optimize levels and combinations of critical gas pressure (sheath, auxiliary, sweep) and temperature (ion transfer tube, vaporizer) parameters for high-sensitivity mass spectrometric quantification of brain tissue glutamine. A Design of Experiments (DOE) matrix for evaluation of relationships between these multiple independent variables and a singular response variable, e.g. glutamine chromatogram area, was developed by statistical response surface methodology using central composite design. A second-order polynomial equation was generated to identify and predict singular versus combinatory effects of synergistic and antagonistic factors on chromatograph area. Predicted versus found outcomes overlapped, with enhanced area associated with the latter. DOE methodology was subsequently used to evaluate liquid chromatographic variable effects, e.g. flow rate, column temperature, and mobile phase composition on the response variable. Results demonstrate that combinatory AQbD-guided mass spectrometric/liquid chromatographic optimization significantly enhanced analytical sensitivity for Gln, thus enabling down-sized brain tissue sample volume procurement for quantification of this critical amino acid.

NEUROGENOTOXICITY EFFECT OF DELTAMETHRIN AND AMELIORATIVE EFFECT OF VITAMIN E & GREEN TEA ON FEMALE RATS

several studies have been implicated oxidative stress and genotoxicity as important mechanisms of toxic effects of pyrethriods in the present study. The beneficial effects of vitamin E and green tea extract were tested in protecting the deltamethrin (DM) induced oxidative stress, genotoxicity and alterations in some amino acid neurotransmitters in brain of adult female rats .Rats were exposed to 1mg/Kg b.wt .deltamethrin (1/10 LD50 ) alone or in combination with vitamin E and/or green tea extract .The antioxidant such as catalse enzyme, reduced glutathione content, lipid peroxidation content and ChE activity were analyzed in cerebrum and cerebellum of brain excised at the end of experiment (30 days). Results showed that genotoxic effect of deltamethrin was proved by SSCP of HRas and P53 genes .Amino acids transmitters were estimated in brain of exposed DM rats . Exposure to deltamethrin resulted in a significant decrease in the activities of catalase, ChE and concentration of reduced glutathione, while the LPO levels were significantly increased in different brain regions .Also, DM exposure increases significant changes in brain amino acids. It is Interestingly that the supplementation with vitamin E or green tea extract or both resulted reversed in the deltamethrin induced antioxidant enzymes and effect on genotoxicity .Combination of both green tea and vit. E appeared to be more effective in protection than each one alone .

The Impairment of Trans Fatty Acids on Learning, Memory and Brain Amino Acid Neurotransmitters in Mice.

The aim of the study was to demonstrate the impairment of trans fatty acids (TFAs) in neurological disorders in mice. Forty-eight male Kunming mice were randomly divided into four groups with twelve in each group, namely a control group (corn oil group), and TFA groups with low, middle and high dosages. The tested chemicals were given by gavage, once a day, for 12 wk in total, with the volume of the intragastric liquid as 0.1 mL/10 g of body weight. The mice in the control group were given corn oil only. The mice in the TFA groups were given TFA solution (doses were 25, 50 and 100 mg/kg of body weight, respectively). The Morris circle water maze was used to test learning and memory of mice. The activity of acetylcholinesterase (AChE), nitric oxide synthase (NOS) and the level of brain amino acid neurotransmitters were tested. In the Morris water maze task, and compared to the control group, TFAs showed no obvious effect on learning or memory. TFA intake led to a significant decrease of AChE in all TFA groups, and the increase in levels of NOS in the high-dose group. Meanwhile, intake of TFAs increased the levels of Asp, Glu, Gly, and Tau in all TFA groups. The results suggest that long-term intake of TFAs probably impairs learning, memory and brain neurotransmitters in mice.

実験的歯の移動が Streptozotocin 糖尿病マウスのMHPG, 血糖値, および脳内アミノ酸系神経伝達物質に及ぼす影響について

実験的歯の移動が Streptozotocin 糖尿病マウスのMHPG, 血糖値, および脳内アミノ酸系神経伝達物質に及ぼす影響について

Review Of The Main Welfare Risks Related To Electrical Stunning Of Small Ruminants (Ovine And Caprine Species)

EFSA commissioned a comprehensive review of the welfare aspects of electrical stunning methods for small ruminants with an emphasize on low ampere stunning to establish the state of the art in the field and to assess whether scientific studies would address criteria outlined in an EFSA guidance on the assessment criteria for studies evaluating the effectiveness of stunning interventions regarding animal protection at the time of killing (EFSA Journal 2013;11(12):3486). The review was not formulated as a systematic review with a focused question instead the review followed the approach to assessing the literature described by the EFSA guidance. The key databases searched were: Science Citation Index (1900-2014), CAB Abstracts (1910-2014) and Medline (1990-2014). Key conferences proceedings and the bibliographies of review articles were manually searched. The search yielded 1599 records. 706 duplicate records were removed and 894 records assessed for relevance. Relevant studies reported electronic stunning of small ruminants and outcomes associated with onset and duration of unconsciousness. Eighteen papers reported electrical approaches to stunning in sheep. No goats were studied. None of the papers reported all of the parameters detailed in the EFSA guidance (EFSA, 2013) and a risk of bias assessment was not conducted. No studies reported the appearance of the electrodes. When the frequency (Hz) applied to the animal was reported, it was not specified whether this represented a minimum or maximum frequency. Only one study explicitly reported an effect size for amperes. The study suggested that the odds of a poor stun were higher for amperes of 0.6 (odds ratio (OD) of 6.27 with 95% confidence interval (CI) of 1.98-20.7) and 0.8 (OR of 24.4 with 95% CI of 6.98-85.2) when compared to a poor stun at 1.25 ampere. © European Food Safety Authority, 2015

The Activation of Excitatory Amino Acid Receptors Is Involved in tau Phosphorylation Induced by Cold Water Stress*

In order to investigate whether excitatory neurotransmission system takes roles in tau phosphorylation caused by cold water stress, mice were treated with cold water stress (CWS), which were forced to swim at 4℃ for 5 min. The tau phosphorylation in mice brains was analyzed by immunobloting and immunohistochemistry with c-fos and phosphorylation-dependent tau antibodies. To evaluate the imbalance of excitatory or inhibitory neurotransmitters system, HPLC was used to detect amino acid neurotransmitters in brain after CWS. And the phosphorylated tau in brains of CWS mice, which were pre-treated with different antagonists for excitatory amino acid receptors and L-type calcium channel, was analyzed. The phosphorylated tau in hippocampus was significantly increased accompanied by an increase of c-fos expression at 1 h after CWS. HPLC showed that the content of all detected excitatory and inhibitory amino acid neurotransmitters appeared an acute increase then decrease pattern. At 15 min after CWS, aspartate and glycine appeared a significant increase, and aspartate, glutamate, taurine and GABA significantly decreased at 1 h. When the animals were pre-treated with NMDA receptor antagonist MK-801 (5 mg/kg) and AMPA receptor antagonist DNQX (0.5, 5 mg/kg), tau phosphorylation caused by CWS were significantly suppressed. Whereas, metabolic glutamate receptor antagonist, MAP-4, had no significant effect on tau phosphorylation. In addition, L-type calcium channel blocker, nimodipine (0.05, 0.5 mg/kg), also could inhibit CWS caused tau phosphorylation. These results indicated that CWS affects tau phosphorylation by mediating excitatory neurotransmission system through ionic excitatory amino acid receptors. The activation of excitatory neurotransmission system takes roles in CWS induced tau phosphorylation in hippocampus.

The effects of ear-point stimulation on the contents of somatostatin and Amino acid neurotransmitters in brain of rat with experimental seizure.

The goal of this study was to elucidate the anti-convulsion mechanisms of ear-point stimulation in rat with experimental seizure. We prepared the epilepsy rats by intrahippocampal injection of penicillin. One hour later the lower 1/2 auricular lobules of seizure rats, containing ear-points Pizhixia and Shenmen etc., was electrically stimulated, which was imitated as ear-point electrical acupuncture in humans. Radioimmunoassay and biochemical techniques were used to determine the contents of somatostatin and amino acid neurotransmitters in hippocampus of rats. The outcomes revealed epileptiform behaviors of rat were appeared after penicillin-injected. The contents of somatostatin, aspartic acid, glutamine and GABA were increased. When these rats were subsequently given the ear-point electrical stimulation, the convulsion behaviors were definitely improved. At the same time the contents of the somatostatin, aspartic acid and glutamine in hippocampus of seizure rat were significantly decreased correspondingly. The contents of glycine, taurine and GABA had increased. Based on the results above, it was suggestive that ear-point electrical stimulation had anti-epilepsy effects, which might be involved in the decreases of the contents of the somatostatin, aspartic acid and glutamine, and increases of the contents of glycine, taurine and GABA in hippocampus of seizure rat.

Evaluation of anticonvulsant activity of N-(p-aminobenzoyl)-1,2,3,4-tetrahydro-4-methylquinoline

Anticonvulsant activity of N-(p-aminobenzoyl)-1,2,3,4-tetrahydro-4-methylquinoline (NMQ), a newly synthesized ameltolide analogue, was investigated with regards to efficacy, lethality and neurotoxicity in mice. In vivo microdialysis experiments on freely moving rats were also performed in search for the possible effect of NMQ on cortical amino acid neurotransmitters. Similar to ameltolide, intraperitoneally given NMQ exerted it protective effect exclusively in maximal electroshock seizure (MES), but not in pentylenetetrazole test. However, in comparison with ameltolide which exhibited the median effective dose (ED50) of 1.08 mg/kg body weight (B.W.), NMQ was less effective (ED50 = 77.62 mg/kg B.W.). Based on the finding that no lethality was observed in mice being given NMQ up to 1000 mg/kg B.W. while the median lethality dose (LD50) of ameltolide was observed at 63 mg/kg B.W., NMQ appeared to be superior to ameltolide with regards to safety. The median neurotoxic dose (TD50) from the rotarod test was found to be 320 and 9 mg/kg B.W. for NMQ and ameltolide respectively, resulting in lower protective index (PI=TD50/ED50) of NMQ (4.12) than that of ameltolide (8.33). Thus, it could be anticipated that therapeutic dose of NMQ which seemed to be safe would produce more pronounced motor impairment than that of ameltolide. In microdialysis study on freely moving rats, it was found out that neither NMQ nor ameltolide was able to exert significant changes on the level of cortical brain amino acid neurotransmitters, namely, aspartate, glutamate, glycine and GABA. Therefore, some mechanisms other than alteration in brain amino acid neurotransmitters should underlie anticonvulsant activity exhibited by these two compounds in MES test. Furthermore, based on similarity in pharmacological screening profile of NMQ and ameltolide observed in the present study, it is suggestive that these two compounds may possess rather similar mechanism of action.

Selective increase of brain lactate synthesis in experimental acute liver failure: Results of a [ 1H- 13C] nuclear magnetic resonance study

Acute liver failure (ALF) results in alterations of energy metabolites and of glucose-derived amino acid neurotransmitters in brain. However, the dynamics of changes in glucose metabolism remain unclear. The present study was undertaken using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy to determine the rates of incorporation of glucose into amino acids and lactate via cell-specific pathways in relation to the severity of encephalopathy and brain edema in rats with ALF because of hepatic devascularization. Early (precoma) stages of encephalopathy were accompanied by significant 2- to 4.5-fold ( P < .001) increases of total brain glutamine and lactate concentrations. More severe (coma) stages of encephalopathy and brain edema led to a further significant increase in brain lactate but no such increase in glutamine. Furthermore, 13C isotopomer analysis showed a selective increase of de novo synthesis of lactate from [1- 13C]glucose resulting in 2.5-fold increased fractional 13C enrichments in lactate at coma stages. [2- 13C]glutamine, synthesized through the astrocytic enzyme pyruvate carboxylase, increased 10-fold at precoma stages but showed no further increase at coma stages of encephalopathy. 13C-label incorporation into [4- 13C]glutamate, synthesized mainly through neuronal pyruvate dehydrogenase, was selectively reduced at coma stages, whereas brain GABA synthesis was unchanged at all time points. In conclusion, increased brain lactate synthesis and impaired glucose oxidative pathways rather than intracellular glutamine accumulation are the major cause of brain edema in ALF. Future NMR spectroscopic studies using stable isotopes and real-time measurements of metabolic rates could be valuable in the elucidation of the cerebral metabolic consequences of ALF in humans. (H EPATOLOGY 2003;37:420-428.)

Brainstem amino acid neurotransmitters and hypoxic ventilatory response

The ventilatory response to acute hypoxia in mammalian species is biphasic, an initial hyperventilatory response is followed by a reduction in ventilation within 2–3 min below the peak level (roll-off). Brain amino acid neurotransmitters also change during hypoxia. This study explores the role of neurotransmitters in anesthetized adult Sprague–Dawley rats mechanically ventilated during 20 min of 10% O 2 breathing. Phrenic nerve activity was recorded, and microdialysate concentrations of selected amino acids were determined at 3- to 5-min intervals in respiratory chemosensitive areas of the ventrolateral medulla (VMS) 1.25–2.00 mm below the surface. Phrenic nerve output was biphasic during hypoxia, concurrent with a rapid glutamate and gradual GABA increase. Taurine first decreased, then increased. In both intact and chemodenervated animals, time-dependent change in phrenic nerve activity during hypoxia was associated with corresponding changes in glutamate, GABA, and taurine concentrations, suggesting that cumulative effects of changes in the concentration of these three amino acids could account for response of the phrenic nerve to hypoxia.

The effect of electrical head-only stun duration on electroencephalographic-measured seizure and brain amino acid neurotransmitter release

Effective electrical head-only stunning produces a seizure-like state followed by a period of analgesia seen in animals allowed to recover. Passing of a 1·0 A current (50 Hz, 500 V) for less than 0·2 s, through the head of a sheep does not produce a seizure-like state as evidenced by recorded electroencephalogram. Corresponding to this lack of seizure-like state, the release of the neurotransmitters glutamate and aspartate, in the brain, occurs to levels associated with arousal rather than seizure. At a duration of 0·2 s, the same stun parameters as above produce a seizure-like state and the release of glutamate and aspartate rises dramatically. The length of the seizure-like state, and the levels of release of glutamate, aspartate and a third neurotransmitter gamma amino-4-butyric acid (GABA), increased with stun duration until 4·0 s duration, where a peak in these parameters was seen. Stun durations of 2·0, 4·0, 8·0 and 12·0 s all produce similar effects. At a duration of 20 s, however, the length of the seizure-like state and the release of neurotransmitters is less than at shorter stun durations. For welfare purposes a head-only electrical stun, of 1·0 A, at a duration as low as 0·2 s produces unconsciousness and analgesia to subsequent slaughter procedures. However, maximum welfare benefits appear attainable at durations between 2·0 and 20·0 s.

Electrochemical detection of human brain transmitter amino acids by high-performance liquid chromatography of stable O-phthalaldehyde-sulphite derivatives

A simple, sensitive, reliable and reproducible isocratic HPLC technique for the measurement of OPA/sulphite derivatives of human brain amino acid neurotransmitters is described. This employs a sample preparation that is also compatible with the concurrent determination of monoamines and their metabolites on a separate HPLC system. The method has been applied to the determination of GABA and glutamate in brain tissue taken post-mortem from patients with Huntington's disease and control subjects.

A high performance liquid chromatography/electrochemical assay for glutamatergic neurotransmitters in the rat brain.

The release and content of the excitatory amino acid neurotransmitters glutamate and aspartate in rat striatum were determined by liquid chromatography/electrochemistry. This determination was based on precolumn off-line derivatization of the amino acids with o-phthaldialdehyde and 2-mercaptoethanol (OPT/2-MCE), and the adducts formed were separated under isocratic conditions and oxidized on a glassy carbon electrode at moderate potential (+0.6 V). The standard and the extracted glutamate when derivatized with OPT/2-MCE produced similar electrochemical and chromatographic characteristics. The detection limit of glutamate was 0.5 pmol. Depolarization induced by the high potassium medium (40 mmol/L) enhanced the release of glutamate and aspartate from superfused rat striatum, whereas the efflux of glutamine remained unchanged. Perfusion (for 60-70 min) removed 50-80% of the free amino acid content of striatal tissue. The method described here is useful in neurochemical investigations of the brain amino acid neurotransmitters.

Changes in glutamate-cycle enzyme mRNA levels in a rat model of hepatic encephalopathy.

To detect possible changes in the regulation of glutamate/gamma-aminobutyric acid (GABA) enzymes at the level of gene expression in a thioacetamide-induced rat model of acute hepatic encephalopathy, we have examined changes in the mRNAs of four glutamate/GABA enzymes by quantitative RNA blot hybridization analysis. Such changes could reflect cell adaptation to excess ammonia or some other associated metabolic stress. The mRNA levels of glutamate dehydrogenase (GDH) decreased similarly in three different brain regions, whereas those of glutamine synthetase (GS) and glutaminase (GA) increased. The mRNA levels of glutamate decarboxylase (GAD) were unchanged. The results indicate that some effect of liver damage, presumably hyperammonemia, affected the expression of some, but not all, genes associated with ammonia and glutamate metabolism in the brain. This adaptation of gene expression to secondary effects of ammonia on brain amino acid neurotransmitter metabolism or brain energy metabolism could play a role in the physiological changes observed in hepatic encephalopathy.

Brain amino acid concentrations during diving and acid-base stress in turtles.

To assess the role of brain amino acid neurotransmitters in the breath hold of diving animals, concentrations of free amino acids present in the brains of turtles immediately after 2 h of apneic diving (at 20 degrees C) were measured. Additionally, the same measurements were performed on four other groups of animals subjected to 2 h of hypercapnia (8% CO2 in air), anoxia (N2 breathing), anoxia plus hypercapnia (8% CO2-92% N2), or air breathing (control). Significant changes in the concentrations of the inhibitory amino acid neurotransmitters known to affect respiration [gamma-aminobutyric acid (GABA) and taurine] were seen. GABA increased significantly in those animals subjected to anoxia, whereas taurine decreased significantly in the diving animals and increased significantly in those subjected to anoxia plus hypercapnia. These results suggest that the attenuated central ventilatory drive during diving in these animals may be related to alterations in brain concentrations of GABA and taurine.

Changes in Regional Brain Levels of Amino Acid Putative Neurotransmitters After Prolonged Treatment with t he Anticonvulsant Drugs Diphenylhydantoin, Phenobarbitone, Sodium Valproate, Ethosuximide, and Sulthiame in the Rat

The effect of prolonged treatment (10 days) with the anticonvulsant drugs diphenylhydantoin (DPH), phenobarbitone, sodium valproate, ethosuximide and sulthiame, both singly and in combination, on regional rat brain amino acid neurotransmitter concentrations (GABA, glutamate, aspartate and taurine) were assessed. DPH had a major effect in the cerebellum and hypothalamus in that it significantly reduced cerebellar GABA, taurine and aspartate and hypothalamic GABA and aspartate. Sodium valproate significantly elevated GABA and taurine in most regions. Aspartate and glutamate were less affected. Phenobarbitone significantly elevated GABA concentrations in all brain regions, while taurine concentration was only elevated in the cerebral cortex. Ethosuximide induced changes were small compared to the other anticonvulsants while sulthiame produced complex changes. Anticonvulsant drugs administered in combination resulted in complex changes, suggesting that their mode of action is different.