Inhibitory Amino Acid Research Articles

Effect of Silkworm Pupae Peptide on the Fermentation and Quality of Yogurt

In the present study, the effect of silkworm pupae peptide on acidification, water-holding capacity (WHC), textural properties, sensory characteristics, angiotensin I-converting enzyme (ACE) inhibitory activity, and the amino acid composition of fermented milk products was studied. The addition of peptide enhanced acidification, thus reducing the fermentation time. Furthermore, addition of > 0.7% peptide significantly (P 0.3%. Therefore, further studies are necessary to optimize the flavor of yogurt containing silkworm pupae peptide. Practical Applications The demand for dairy products containing bioactive peptides is high because their intake can fulfill the nutritional requirement. In this study, the effect of silkworm pupae peptide on the qualities of dairy products was studied. Addition silkworm pupae peptide could enhance acidification and reduce the fermentation time. Addition of 0.5% silkworm pupae peptide could enhanced ACE inhibitory activity and amino acid content. Although addition of silkworm pupae peptide had beneficial effects on the firmness, consistency, and cohesiveness of yogurt, it reduced the overall flavor. The results are useful for the yogurt industry in improving production efficiency and product quality.

The Influence of Manganese and Glutamine Intake on Antioxidants and Neurotransmitter Amino Acids Levels in Rats' Brain.

Depending on the concentration, Mn can exert protective or toxic effect. Potential mechanism for manganese neurotoxicity is manganese-induced oxidative stress. Glutamine supplementation could reduce manganese-induced neurotoxicity and is able to influence the neurotransmission processes. The aim of this study was to investigate whether the long term administration of manganese (alone or in combination with glutamine) in dose and time dependent manner could affect the selected parameters of oxidative-antioxidative status (superoxide dismutase and glutathione peroxidase activities, concentrations of vitamin C and malonic dialdehyde) and concentrations of excitatory (Asp, Glu) and inhibitory amino acids (GABA, Gly) in the brain of rats. The experiments were carried out on 2-months-old albino male rats randomly divided into 6 group: Mn300 and Mn500—received solution of MnCl2 to drink (dose 300 and 500 mg/L, respectively), Gln group—solution of glutamine (4 g/L), Mn300-Gln and Mn500-Gln groups—solution of Mn at 300 and 500 mg/L and Gln at 4 g/L dose. The control group (C) received deionized water. Half of the animals were euthanized after three and the other half—after 6 weeks of experiment. The exposure of rats to Mn in drinking water contributes to diminishing of the antioxidant enzymes activity and the increase in level of lipid peroxidation. Glutamine in the diet admittedly increases SOD and GPx activity, but it is unable to restore the intracellular redox balance. The most significant differences in the examined amino acids levels in comparison to both control and Gln group were observed in the group of rats receiving Mn at 500 mg/L dose alone or with Gln. It seems that Gln is amino acid which could improve antioxidant status and affect the concentrations of the neurotransmitters.

GABA System in Schizophrenia and Mood Disorders: A Mini Review on Third-Generation Imaging Studies.

Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional–biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA MRS unimodal-descriptive to causal level, and for integrating GABA results into a more comprehensive interpretation of mental disorder pathophysiology.

Effects of Shaoyao Gancao decoction on contents of amino acids and expressions of receptors in brains of spastic paralysis rats

To explore the effects of Shaoyao Gancao decoction on contents of amino acids and expressions of receptors in the brains of spastic paralysis rats, the spastic paralysis rat models of stroke convalescence were made by line tethering method. Baclofen was used as the control group, and the experiment group received Shaoyao Gancao decoction at 3∶1 proportions. After 3 weeks, the neurobehavioral scores, muscular tension and pain threshold were measured and compared. High performance liquid chromatography (HPLC) was used to detect the contents of GABA, Gly, Glu, Asp in cerebral cortex. The protein expressions of GABA receptors Aα1, B； NMDA receptor NR1, NR2A and NR2B in cerebral cortex were determined by immunohistochemistry assay. The results showed that the Shaoyao Gancao decoction at 3∶1 proportion could improve the spastic paralysis state after stroke, significantly improve neurological symptoms (P<0.01), decrease muscular tension (P<0.01) and improve pain threshold (P<0.05) as compared with model group. Simultaneously, the contents of inhibitory amino acids GABA and Gly were increased significantly (P<0.01), while with a decrease tendency in excitatory amino acids Glu and Asp (with no statistical significance). In addition, it could significantly increase the protein expressions of neurotransmitter GABA receptors Aα1, and B (P<0.05); reduce the expressions of neurotransmitter NMDA receptors NR1, NR2A and NR2B (P<0.05). These results suggested that the Shaoyao Gancao decoction at 3：1 proportion could effectively relieve spasm and pain. The mechanism might be associated with increasing the contents of inhibitory amino acids and increasing the expressions of their receptors in spastic paralysis rats after stroke, which would consequently enhance the signal transduction of inhibitory amino acids. Meanwhile, there was a decrease tendency in excitatory amino acids, although no significant effect was observed, and it could suppress the expressions of excitatory amino acids receptors, thus weaken the excitatory signal transduction. Thereby the neurotoxicity was relieved eventually. These findings indicated that Shaoyao Gancao decoction could regulate the balance of neurotransmitter system to relieve the spasticity, and eventually achieve tendon tonifying and spasm relieving effect.

Influence of ketamine on amino acid neurotransmitters secretion by nerve cells in vitro

In order to study the influence of amino acid neurotransmitters secreted by the nerve cells after ketamine treatment, the nerve cells were cultured in vitro to exclude the interference of other factors in vivo and treated with three different doses of ketamine (1, 3 and 5 µg/mL). Then, the concentration of neuronal amino acid neurotransmitters was examined at 0, 15, 30, 45, 60, 90, 120 min after treatment. The trends of each amino acid concentration after ketamine treatment were nearly the same among the different treatment doses. After 15 min of adapting time, ketamine decreased the excitatory amino acid glutamic acid and aspartic acid concentration, and increased the concentration of the inhibitory amino acid glycine. Their concentrations showed a tendency to return approximately to the original level after 120 min.

Co-existence of Functionally Different Vesicular Neurotransmitter Transporters.

The vesicular transmitter transporters VGLUT, VGAT, VMAT2 and VAChT, define phenotype and physiological properties of neuronal subtypes. VGLUTs concentrate the excitatory amino acid glutamate, VGAT the inhibitory amino acid GABA, VMAT2 monoamines, and VAChT acetylcholine (ACh) into synaptic vesicle (SV). Following membrane depolarization SV release their content into the synaptic cleft. A strict segregation of vesicular transporters is mandatory for the precise functioning of synaptic communication and of neuronal circuits. In the last years, evidence accumulates that subsets of neurons express more than one of these transporters leading to synaptic co-release of different and functionally opposing transmitters and modulation of synaptic plasticity. Synaptic co-existence of transporters may change during pathological scenarios in order to ameliorate misbalances in neuronal activity. In addition, evidence increases that transporters also co-exist on the same vesicle providing another layer of regulation. Generally, vesicular transmitter loading relies on an electrochemical gradient ΔμH+ driven by the proton ATPase rendering the lumen of the vesicle with respect to the cytosol positive (Δψ) and acidic (ΔpH). While the activity of VGLUT mainly depends on the Δψ component, VMAT, VGAT and VAChT work best at a high ΔpH. Thus, a vesicular synergy of transporters depending on the combination may increase or decrease the filling of SV with the principal transmitter. We provide an overview on synaptic co-existence of vesicular transmitter transporters including changes in the excitatory/inhibitory balance under pathological conditions. Additionally, we discuss functional aspects of vesicular synergy of transmitter transporters.

Differential modulation of GABAA and NMDA receptors by α7-nicotinic receptor desensitization in cultured rat hippocampal neurons.

To explore the modulatory effect of desensitized α7-containing nicotinic receptors (α7-nAChRs) on excitatory and inhibitory amino acid receptors in cultured hippocampal neurons and to identify the mechanism underlying this effect. Whole-cell patch-clamp recordings were performed on cultured rat hippocampal neurons to measure α7-nAChR currents and to determine the role of desensitized α7-nAChRs on brain amino acid receptor activity. Pulse and perfusion applications of the α7-nAChR agonist choline were applied to induce different types of α7-nAChR desensitization in cultured hippocampal neurons. After a brief choline pulse, α7-nAChR was desensitized as a result of receptor activation, which reduced the response of the A type γ-aminobutyric acid (GABAA) receptor to its agonist, muscimol, and enhanced the response of the NMDA receptor to its agonist NMDA. By contrast, the responses of glycine or AMPA receptors to their agonists, glycine or AMPA, respectively, were not affected. Pretreatment with the α7-nAChR antagonist methyllycaconitine (MLA, 10 nmol/L) blocked the choline-induced negative modulation of the GABAA receptor and the positive modulation of the NMDA receptor. The regulation of the GABAA and NMDA receptors was confirmed using another type of α7-nAChR desensitization, which was produced by a low concentration of choline perfusion. The negative modulation of the GABAA receptor was characterized by choline-duration dependency and intracellular calcium dependency, but the positive modulation of the NMDA receptor was not associated with cytoplasmic calcium. Brain GABAA and NMDA receptors are modulated negatively and positively, respectively, by desensitized α7-nAChR as a result of choline pretreatment in cultured hippocampal neurons.

Selective expression of a constitutively active erythropoietin receptor in GABAergic neurons alters hippocampal network properties without affecting cognition.

We have previously shown that treatment with erythropoietin (EPO) improves cognition in patients with neuropsychiatric disorders as well as in healthy mice, and that transgenic expression of a constitutively active form of the EPO receptor (cEPOR) in glutamatergic neurons boosts higher cognitive functions in mice. In the present work, we examined whether selective activation of EPOR signaling in GABAergic neurons would also modulate cognitive performance. We generated transgenic mice that express cEPOR under the control of the vesicular inhibitory amino acid transporter (Viaat) promoter and subjected them to comprehensive behavioral, cognitive, and electrophysiological analyses. We demonstrate that transgenic expression of cEPOR in GABAergic neurons alters hippocampal gamma-oscillations and enhances long-term potentiation but neither impairs nor improves cognition. To conclude, constitutively active EPOR in GABAergic neurons changes hippocampal network properties without affecting cognition, which suggests that the effect of EPO on cognition is dominated by its effect on the glutamatergic system. Treatment with EPO improves cognitive performance. We previously demonstrated that this effect is replicated by constitutive autoactivation of cEPOR in glutamatergic neurons. By contrast, cEPOR in GABAergic neurons changes hippocampal network properties but neither impairs nor enhances cognition. Thus, EPO modulates neuronal plasticity, and the cognitive benefits may be mainly attributable to its effect on the glutamatergic system.

Microconnectomics of the pretectum and ventral thalamus in the chicken (Gallus gallus).

The avian pretectal and ventrothalamic nuclei, encompassing the griseum tectale (GT), n. lentiformis mesencephali (LM), and n. geniculatus lateralis pars ventralis (GLv), are prominent retinorecipient structures related to optic flow operations and visuomotor control. Hence, a close coordination of these neural circuits is to be expected. Yet the connectivity among these nuclei is poorly known. Here, using intracellular labeling and in situ hybridization, we investigated the detailed morphology, connectivity, and neurochemical identity of neurons in these nuclei. Two different cell types exist in the GT: one that generates an axonal projection to the optic tectum (TeO), LM, GLv, and n. intercalatus thalami (ICT), and a second population that only projects to the LM and GLv. In situ hybridization revealed that most neurons in the GT express the vesicular glutamate transporter (VGluT2) mRNA, indicating a glutamatergic identity. In the LM, three morphological cell types were defined, two of which project axons towards dorsal targets. The LM neurons showed strong VGluT2 expression. Finally, the cells located in the GLv project to the TeO, LM, GT, n. principalis precommisuralis (PPC), and ICT. All neurons in the GLv showed strong expression of the vesicular inhibitory amino acid transporter (VIAAT) mRNA, suggesting a GABAergic identity. Our results show that the pretectal and ventrothalamic nuclei are highly interconnected, especially by glutamatergic and GABAergic neurons from the GT and GLv, respectively. This complex morphology and connectivity might be required to organize orienting visuomotor behaviors and coordinate the specific optic flow patterns that they induce. J. Comp. Neurol. 524:2208-2229, 2016. © 2015 Wiley Periodicals, Inc.

Effects of Propofol on Excitatory and Inhibitory Amino Acid Neurotransmitter Balance in Rats with Neurogenic Pulmonary Edema Induced by Subarachnoid Hemorrhage

Propofol exhibits neuroprotective effects mediated by the inhibition of excitatory amino acid (EAA) neurotransmitter release and potentiation of inhibitory amino acid (IAA) neurotransmitters. To our knowledge, this is the first study to investigate the effects of propofol on the EAA and IAA balance in neurogenic pulmonary edema (NPE). Sixty male Wistar rats were randomized to Sham, NPE, Low-dose propofol, and High-dose propofol groups. NPE was induced via rapid injection of autologous blood (0.5ml) into the cisterna magna. The Low- and High-dose propofol groups were pretreated with boluses of 2 and 5mgkg(-1), respectively, prior to blood injection, followed by continuous propofol infusion at 6 and 15mgkg(-1)h(-1), respectively. The mean arterial pressure (MAP), heart rate, intracranial pressure (ICP), peak inspiratory pressure (PIP), and arterial blood gases were continuously recorded. After 2h, the lung wet-to-dry weight ratio, total protein concentration in the bronchoalveolar lavage fluid (BALF), brain water content, cortical EAA and IAA levels, chest X-ray, and histological staining of lung sections were evaluated. Blood injections into the cisterna magna induced NPE and hemodynamic changes. Propofol alleviated the increases in the MAP, ICP, and PIP, improved oxygenation and histopathological changes, ameliorated pulmonary and cerebral edema, increased the IAA brain levels, and decreased the ratio of Glu to γ-aminobutyric acid. The current findings suggest that propofol improves NPE likely via IAA accumulation and the regulation of EAA and IAA balance, which may represent an effective treatment for NPE.

Perturbed Hippocampal Synaptic Inhibition and γ-Oscillations in a Neuroligin-4 Knockout Mouse Model of Autism.

SummaryLoss-of-function mutations in the synaptic adhesion protein Neuroligin-4 are among the most common genetic abnormalities associated with autism spectrum disorders, but little is known about the function of Neuroligin-4 and the consequences of its loss. We assessed synaptic and network characteristics in Neuroligin-4 knockout mice, focusing on the hippocampus as a model brain region with a critical role in cognition and memory, and found that Neuroligin-4 deletion causes subtle defects of the protein composition and function of GABAergic synapses in the hippocampal CA3 region. Interestingly, these subtle synaptic changes are accompanied by pronounced perturbations of γ-oscillatory network activity, which has been implicated in cognitive function and is altered in multiple psychiatric and neurodevelopmental disorders. Our data provide important insights into the mechanisms by which Neuroligin-4-dependent GABAergic synapses may contribute to autism phenotypes and indicate new strategies for therapeutic approaches.

Changes in intracellular potentials and ionic currents of the mollusk and activity of Cl--channels under exposure to some inhibitory amino acids and new litium-containing compounds of them

The Changes of membrane rest potential (RP), action potential (AP), impulse activity (IA) as well as sodium, calcium and potassium ionic currents in neurons of isolated central nervous system of the Planorbarius corneus mollusk (pedal ganglia) under the extracellular action of inhibitory amino acids GABA, glycine and β-alanine and their litium-containing derivatives (LCD) in 0.1, 1 and 5 mM concentrations have been studied using a microelectrode technique. They induced the same dose-dependent and irreversible depolarization of neurons on 2-10 mV accompanied by increase of AP frequency, prolongation of their duration and decrease of summmerized ionic currents (dV/dt). According to degree of depolarization, the drugs were placed in the following range in decreasing activity: compound 3 &gt; compound 2 &gt; compound 1. In identified pedal ganglion neurons (PPed1), compound 3 in contrast to other compounds induced hyperpolarization by 2-10 mV and blocked impulse activity. The amplitude of sodium and calcium channels was decreased by 7-15 %, in the same degree after application of all compounds exposed in concentration of 5 mM. Efflux potassium ionic currents were increased in dose-dependent manner and irreversibly about by 3-7 % assessed on amplitude indexes without changes in kinetic parameters after application of LCD. Therefore, the decrease of ionic current amplitudes was due to both depolarization of neurons and direct action of LCD on ionic channels. Thus, LCD possess membranotropic activity and can modulate functional state of neurons. In the study of chloride channels in cells culture of rat glioma C6 in vitro by patch-clamp method, GABA, glycine, β-alanine and their LCD 10 µM/l activated chloride channels, shifting equiliblium membrane potential of glioma cells from -90… -70 mV to -55... -60 mV. All compounds (transmitters and LCD) were placed in the following range: glycine &gt; GABA &gt; β-alanine and compound 1 &gt; compound 3 &gt; compound 2 according to descending activity. Therefore, the most active compounds activating Cl--channels were glycine and compound 1 (LCD). Glycine was shown to be coagonist GABA receptors and its litium salt possessed significant membranotropic activity.

Propofol differentially inhibits the release of glutamate, γ-aminobutyric acid and glycine in the spinal dorsal horn of rats.

Propofol (2, 6-diisopropylphenol) is an intravenous anesthetic that is commonly used for the general anesthesia. It is well known that the spinal cord is one of the working targets of general anesthesia including propofol. However, there is a lack of investigation of the effects of propofol on spinal dorsal horn which is important for the sensory transmission of nociceptive signals. The objective of this study was to investigate the effects of increasing dosage of propofol on the release of glutamate (Glu), γ-aminobutyric acid (GABA) and glycine (Gly) in the spinal dorsal horn. The efflux of Glu, GABA or Gly in the spinal dorsal horn of rats was detected using transverse spinal microdialysis under an awake condition and various depths of propofol anesthesia. The infusion rates of propofol were, in order, 400 µg/(kg·min), 600 µg/(kg·min) and 800 µg/(kg·min), with a 20 min infusion period being maintained at each infusion rate. Propofol decreased the glutamate efflux within spinal dorsal horn in a dose-dependent manner, and the maximum decrease was 56.8 ± 6.0% at high-dose propofol infusion producing immobility. The inhibitory GABA and Gly efflux was also decreased about 15-20% at low-dose propofol infusion only producing sedation, but did not continue to drop with higher doses of propofol. Propofol decreased both excitatory and inhibitory amino acids efflux in spinal dorsal horn, and the preferential suppression of the excitatory amino acid might be associated with the analgesic effect of propofol.

Effect of Baicalin-loaded PEGylated cationic solid lipid nanoparticles modified by OX26 antibody on regulating the levels of baicalin and amino acids during cerebral ischemia–reperfusion in rats

Baicalin has many pharmacological activities, including neuroprotective function against ischemia and neurodegeneration. In our previous study, we found that Baicalin-loaded PEGylated cationic solid lipid nanoparticles modified by OX26 antibody (OX26-PEG-CSLN) might be a promising carrier to deliver drugs across the blood–brain barrier for the treatment of brain diseases. So, the aim of this present study was to further elucidate the mechanisms of OX26-PEG-CSLN cerebral ischemia protection by monitoring the changes of extracellular amino acids. In addition, we investigated the effect of OX26-PEG-CSLN on the excitotoxic neuronal injury as well as the pharmacokinetic profiles of baicalin in cerebrospinal fluid during ischemia–reperfusion period. The cerebrospinal fluid was collected by a microdialysis technique and divided into two parts – one part for pharmacokinetic study of baicalin using LC–MS/MS method and the other for pharmacodynamic study which was done by pre- column derivatization of the amino acids and analysis using a high-performance liquid chromatography with fluorescence detector (HPLC-FLD). The pharmacokinetic study showed that the AUC value of OX26-PEG-CSLN was 5.69-fold higher than that of the baicalin solution (Sol) (P<0.05) and the Cmax value of OX26-PEG-CSLN was 6.84-fold higher than that of the Sol (P<0.05). Moreover, the extracellular levels of glutamate (Glu), aspartic acid (Asp), glycine (Gly), taurine (Tau) and γ-aminobutyric acid (GABA) were measured for monitoring the imbalance of amino acids caused by ischemia and reperfusion. The excitotoxic index (EI) was also calculated for evaluating the imbalance between excitatory amino acid and inhibitory amino acid. The pharmacodynamic study showed that OX26-PEG-CSLN had stronger effect than Sol in reducing the content of aspartic, glutamic acid and increasing the concentrations of glycine, taurine and γ-aminobutyric acid during ischemia–reperfusion period. In conclusion, OX26-PEG-CSLN improved uptake of baicalin across the BBB into the brain, and elevated bioavailability of baicalin in cerebral spinal fluid of rats under the cerebral ischemia–reperfusion injury. OX26-PEG-CSLN had much higher protection effect against cerebral ischemia injury than Sol by relieving the excitotoxic neuronal injury via regulating amino acid levels in cerebral spinal fluid.

Conditional targeting of medium spiny neurons in the striatal matrix

The striatum serves as the main input to the basal ganglia, and is key for the regulation of motor behaviors, compulsion, addiction, and various cognitive and emotional states. Its deterioration is associated with degenerative disorders such as Huntington's disease. Despite its apparent anatomical uniformity, it consists of intermingled cell populations, which have precluded straightforward anatomical sub-classifications adhering to functional dissections. Approximately 95% of the striatal neurons are inhibitory projection neurons termed medium spiny neurons (MSNs). They are commonly classified according to their expression of either dopamine receptor D1 or D2, which also determines their axonal projection patterns constituting the direct and indirect pathway in the basal ganglia. Immunohistochemical patterns have further indicated compartmentalization of the striatum to the striosomes and the surrounding matrix, which integrate MSNs of both the D1 and D2 type. Here, we present a transgenic mouse line, Gpr101-Cre, with Cre recombinase activity localized to matrix D1 and D2 MSNs. Using two Gpr101-Cre founder lines with different degrees of expression in the striatum, we conditionally deleted the vesicular inhibitory amino acid transporter (VIAAT), responsible for storage of GABA and glycine in synaptic vesicles. Partial ablation of VIAAT (in ~36% of MSNs) resulted in elevated locomotor activity compared to control mice, when provoked with the monoamine reuptake inhibitor cocaine. Near complete targeting of matrix MSNs led to profoundly changed motor behaviors, which increased in severity as the mice aged. Moreover, these mice had exaggerated muscle rigidity, retarded growth, increased rate of spontaneous deaths, and defective memory. Therefore, our data provide a link between dysfunctional GABA signaling of matrix MSNs to specific behavioral alterations, which are similar to the symptoms of Huntington's disease.

Gestational and early postnatal hypothyroidism alters VGluT1 and VGAT bouton distribution in the neocortex and hippocampus, and behavior in rats.

Thyroid hormones are fundamental for the expression of genes involved in the development of the CNS and their deficiency is associated with a wide spectrum of neurological diseases including mental retardation, attention deficit-hyperactivity disorder and autism spectrum disorders. We examined in rat whether developmental and early postnatal hypothyroidism affects the distribution of vesicular glutamate transporter-1 (VGluT1; glutamatergic) and vesicular inhibitory amino acid transporter (VGAT; GABAergic) immunoreactive (ir) boutons in the hippocampus and somatosensory cortex, and the behavior of the pups. Hypothyroidism was induced by adding 0.02% methimazole (MMI) and 1% KClO4 to the drinking water starting at embryonic day 10 (E10; developmental hypothyroidism) and E21 (early postnatal hypothyroidism) until day of sacrifice at postnatal day 50. Behavior was studied using the acoustic prepulse inhibition (somatosensory attention) and the elevated plus-maze (anxiety-like assessment) tests. The distribution, density and size of VGluT1-ir and VGAT-ir boutons in the hippocampus and somatosensory cortex was abnormal in MMI pups and these changes correlate with behavioral changes, as prepulse inhibition of the startle response amplitude was reduced, and the percentage of time spent in open arms increased. In conclusion, both developmental and early postnatal hypothyroidism significantly decreases the ratio of GABAergic to glutamatergic boutons in dentate gyrus leading to an abnormal flow of information to the hippocampus and infragranular layers of the somatosensory cortex, and alter behavior in rats. Our data show cytoarchitectonic alterations in the basic excitatory hippocampal loop, and in local inhibitory circuits of the somatosensory cortex and hippocampus that might contribute to the delayed neurocognitive outcome observed in thyroid hormone deficient children born in iodine deficient areas, or suffering from congenital hypothyroidism.

Expressions of retinal γ-aminobutyric acid and its receptors in retina of guinea pig eyes after lens induction

Background Researches showed that gamma aminobutyric acid (GABA),an inhibitory amino acid neurotransmitter,plays a critical role in myopia refractive development.The inhibitory roles of GABA and its receptors antagonists have been confirmed.However,the study on whether GABA participates in the mechanisms of lens-induced myopia (LIM) in guinea pigs is rare. Objective The aim of this study was to explore the alteration of expression of GABA and its three receptor subtypes in the retinas of guinea pigs with LIM. Methods Three-week-old healthy guinea pigs were randomized into the normal control group and the model group.The right eyes of the guinea pigs in the normal control group served as the normal control eyes,and the right eyes of the guinea pigs in the model group monocularly fitted with -10 D lens as the experimental eyes,and the fellow eyes of the model group were used as the self-control eyes.The refraction and axial length of eyes were measured by A-sonography and streak retinoscopy before and 4 weeks after modeling.The guinea pigs were sacrificed at the fourth week after modeling,and the retinas were isolated.GABA content in the retinas was assayed by high performance liquid chromatography (HPLC) and the relative expression levels of subtypes of GABA receptors were detected by real-time PCR.All the results were compared among the groups.All experimental protocols and animal handling procedures were approved by the Animal Care and Use Committee of Shandong University of Traditional Chinese Medicine,and were in accordance with the statement of the Association for Research in Vision and Ophthalmology for the use of animals. Results At the fourth week after modeling,the mean diopter of the model eyes was (-3.39±0.70)D,which was significantly higher than (1.03±0.68)D of the normal control eyes and (0.77±0.64)D of the self-control eyes in the model group (t=-16.382,-17.113,both at P 0.05). Conclusions The expressions of GABA as well as the mRNA of GABAA and GABAC receptor up-regulate, but there is no obvious alteration in the expression of mRNA of GABAB receptor in the LIM eyes. Key words: Myopia/lens-induced; Gamma aminobutyric acid; Gamma aminobutyric acid receptor; Retina

Studies on the Protective Effects of Scutellarein against Neuronal Injury by Ischemia through the Analysis of Endogenous Amino Acids and Ca2+Concentration Together with Ca2+-ATPase Activity

Scutellarin, which is extracted from the dried plant ofErigeron breviscapus, has been reported to protect the neural injury against excitotoxicity induced by ischemia. However, there are a few studies on the protective effects of scutellarein, which is the main metabolite of scutellarin in vivo. Thus, this study investigated the neuroprotective effects of scutellarein on cerebral ischemia/reperfusion in rats by bilateral common carotid artery occlusion (BCCAO) model, through the analysis of endogenous amino acids using HILIC-MS/MS, and evaluation of Ca2+concentration together with Ca2+-ATPase activity. The results showed that scutellarein having good protective effects on cerebral ischemia/reperfusion might by decreasing the excitatory amino acids, increasing the inhibitory amino acids, lowing intracellular Ca2+level, and improving Ca2+-ATPase activity, which suggested that scutellarein might be a promising potent agent for the therapy of ischemic cerebrovascular disease.

The potential role of Morus alba leaves extract on the brain of mice infected with Schistosoma mansoni.

Schistosomiasis is a neglected tropical disease which is associated with neuropsychiatric and neuropathological disorders. Herein, the main goal of the presented work is to investigate the effect of Morus alba leaves extract in mice brain infected with Schistosoma mansoni. Since, the resistance of Schistosomes to antischistosomal drug (praziquantel) has been examined, schistosomiasis induced brain oxidative stress as evidenced by the decrease of glutathione level, total antioxidant capacity and the activity of catalase significantly, while a significant elevation in the levels of nitrite/nitrate and malondialdhyde. In addition, the infection resulted in neurochemical disturbances, the main inhibitory amino acid, γ- aminobutyric acid level was decreased. In contrast, the level of chloride ions and acetylcholine esterase activity were significantly increased. Moreover, the histopathological section showed some impairments in the brain. The treatment with Morus alba leaves extract ameliorated the induced disturbances in schistosome-infected mice where the levels of non-enzymatic and enzymatic antioxidants were elevated. On the other hand, the levels of nitrite/nitrate and malondialdhyde were significantly reduced. Likewise, treatment of mice with Morus alba leaves extract improved the altered levels of γ- aminobutyric acid level and chloride ion. Also, it improved the recorded impairments of the histopathological section in the brain of schistosome infected mice.

Cerebellin 4, a synaptic protein, enhances inhibitory activity and resistance of neurons to amyloid-β toxicity

Imbalances between excitatory and inhibitory transmissions in the brain anticipate the neuronal damage and death that occur in the neurodegenerative diseases like Alzheimer's disease (AD). We previously showed that amyloid-β (Aß), a natural peptide involved in the onset and development of AD, counteracts the neurotrophic activity of the nerve growth factor (NGF) by dampening the γ-aminobutyric acid (GABA)ergic connectivity of cultured hippocampal neurons. Neuronal plasticity is partly controlled by the NGF-promoted expression of the homologue of enhancer-of-split 1 (Hes1), a transcription factor that regulates the formation of GABAergic synapses. We now show that Hes1 controls the expression of cerebellin 4 (Cbln4), a member of a small family of secreted synaptic proteins, and we present the evidence that Cbln4 plays an essential role in the formation and maintenance of inhibitory GABAergic connections. Cbln4 immunoreactivity was found in the hippocampus, mostly in the dendrites and somata of pyramidal neurons. In the CA1, the hippocampal region where the first neurons degenerate in AD, Cbln4 immunoreactivity was associated with GABAergic synapses (detected by vesicular inhibitory amino acid transporter [VGAT] immunostaining), which appear to surround and embrace the somata of CA1 pyramidal neurons (basket cells). Moreover, significant decreases of Hes1, Cbln4, and VGAT immunoreactivities and messenger RNA expression were found in the hippocampus of a mouse model of AD. We also found that either the overexpression of Cbln4 in cultured hippocampal neurons or the application of recombinant Cbln4 to the cultures increased the number of GABAergic varicosities, rescuing neurons from Aß-induced death. In contrast, knockdown of Cbln4 gene in cultured neurons was followed by a large reduction of GABAergic connections. Such an effect was reverted by exogenously added Cbln4. These findings suggest a therapeutic potential for Cbln4 in the treatment of AD.