Role of 5-hydroxytryptamine type 3 receptors in the regulation of anxiety reactions / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

5-Hydroxytryptamine (5-HT) type 3 receptor (5-HT3R) is the only type of ligand-gated ion channel in the 5-HT receptor family. Through the high permeability of Na+, K+, and Ca2+ and activation of subsequent voltage-gated calcium channels (VGCCs), 5-HT3R induces a rapid increase of neuronal excitability or the release of neurotransmitters from axon terminals in the central nervous system (CNS). 5-HT3Rs are widely expressed in the medial prefrontal cortex (mPFC), amygdala (AMYG), hippocampus (HIP), periaqueductal gray (PAG), and other brain regions closely associated with anxiety reactions. They have a bidirectional regulatory effect on anxiety reactions by acting on different types of cells in different brain regions. 5-HT3Rs mediate the activation of the cholecystokinin (CCK) system in the AMYG, and the γ‍-aminobutyric acid (GABA) "disinhibition" mechanism in the prelimbic area of the mPFC promotes anxiety by the activation of GABAergic intermediate inhibitory neurons (IINs). In contrast, a 5-HT3R-induced GABA "disinhibition" mechanism in the infralimbic area of the mPFC and the ventral HIP produces anxiolytic effects. 5-HT2R-mediated regulation of anxiety reactions are also activated by 5-HT3R-activated 5-HT release in the HIP and PAG. This provides a theoretical basis for the treatment of anxiety disorders or the production of anxiolytic drugs by targeting 5-HT3Rs. However, given the circuit specific modulation of 5-HT3Rs on emotion, systemic use of 5-HT3R agonism or antagonism alone seems unlikely to remedy anxiety, which deeply hinders the current clinical application of 5-HT3R drugs. Therefore, the exploitation of circuit targeting methods or a combined drug strategy might be a useful developmental approach in the future.

"Component-target-efficacy" network analysis and experimental verification of Qingkailing Oral Preparation / 中国中药杂志

This study aims to explore the mechanism of Qingkailing(QKL) Oral Preparation's heat-clearing, detoxifying, mind-tranquilizing effects based on "component-target-efficacy" network. To be specific, the potential targets of the 23 major components in QKL Oral Preparation were predicted by the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP) and SwissTargetPrediction. The target genes were obtained based on UniProt. OmicsBean and STRING 10 were used for Gene Ontology(GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment of the targets. Cytoscape 3.8.2 was employed for visualization and construction of "component-target-pathway-pharmacological effect-efficacy" network, followed by molecular docking between the 23 main active components and 15 key targets. Finally, the lipopolysaccharide(LPS)-induced RAW264.7 cells were adopted to verify the anti-inflammatory effect of six monomer components in QKL Oral Preparation. It was found that the 23 compounds affected 33 key signaling pathways through 236 related targets, such as arachidonic acid metabolism, tumor necrosis factor α(TNF-α) signaling pathway, inflammatory mediator regulation of TRP channels, cAMP signaling pathway, cGMP-PKG signaling pathway, Th17 cell differentiation, interleukin-17(IL-17) signaling pathway, neuroactive ligand-receptor intera-ction, calcium signaling pathway, and GABAergic synapse. They were involved in the anti-inflammation, immune regulation, antipyretic effect, and anti-convulsion of the prescription. The "component-target-pathway-pharmacological effect-efficacy" network of QKL Oral Preparation was constructed. Molecular docking showed that the main active components had high binding affinity to the key targets. In vitro cell experiment indicated that the six components in the prescription(hyodeoxycholic acid, baicalin, chlorogenic acid, isochlorogenic acid C, epigoitrin, geniposide) can reduce the expression of nitric oxide(NO), TNF-α, and interleukin-6(IL-6) in cell supernatant(P<0.05). Thus, the above six components may be the key pharmacodynamic substances of QKL Oral Preparation. The major components in QKL Oral Prescription, including hyodeoxycholic acid, baicalin, chlorogenic acid, isochlorogenic acid C, epigoitrin, geniposide, cholic acid, isochlorogenic acid A, and γ-aminobutyric acid, may interfere with multiple biological processes related to inflammation, immune regulation, fever, and convulsion by acting on the key protein targets such as IL-6, TNF, prostaglandin-endoperoxide synthase 2(PTGS2), arachidonate 5-lipoxygenase(ALOX5), vascular cell adhesion molecule 1(VCAM1), nitric oxide synthase 2(NOS2), prostaglandin E2 receptor EP2 subtype(PTGER2), gamma-aminobutyric acid receptor subunit alpha(GABRA), gamma-aminobutyric acid type B receptor subunit 1(GABBR1), and 4-aminobutyrate aminotransferase(ABAT). This study reveals the effective components and mechanism of QKL Oral Prescription.

Anxiolytic and antidepressant effects of agarwood inhalation and its mechanism / 中国中药杂志

This study used m-chloropheniperazine(MCPP) and chronic unforeseeable mild stress(CUMS) to induce the rat models of anxiety and depression, respectively. The behaviors of rats were observed by the open field test(OFT), light-dark exploration test(LDE), tail suspension test(TST), and forced swimming test(FST), and the antidepressant and anxiolytic effects of agarwood essential oil(AEO), agarwood fragrant powder(AFP), and agarwood line incense(ALI) were explored. The enzyme-linked immunosorbent assay(ELISA) was used to determine the levels of 5-hydroxytryptamine(5-HT), glutamic acid(Glu), and γ-aminobutyric acid(GABA_A) in the hippocampal area. The Western blot assay was used to determine the protein expression levels of glutamate receptor 1(GluR1) and vesicular glutamate transporter type 1(VGluT1), exploring the anxiolytic and antidepressant mechanism of agarwood inhalation. The results showed that compared with the anxiety model group, the AEO, AFP, and ALI groups decreased the total distance(P<0.05), decreased the velocity of movements(P<0.05), prolonged the immobile time(P<0.05), and reduced the distance and velocity of the rat model of anxiety in the dark box(P<0.05). Compared with the depression model group, the AEO, AFP, and ALI groups increased the total distance and average velocity(P<0.05), reduced the immobile time(P<0.05), and reduced the forced swimming and tail suspension time(P<0.05). In terms of transmitter regulation, the AEO, AFP, and ALI groups decreased the level of Glu in the rat model of anxiety(P<0.05) and increased the levels of GABA_A and 5-HT(P<0.05), while the AEO, AFP, and ALI groups all increased the level of 5-HT in the rat model of depression(P<0.05) and decreased the levels of GABA_A and Glu(P<0.05). At the same time, the AEO, AFP, and ALI groups all increased the protein expression levels of GluR1 and VGluT1 in the hippocampus of the rat models of anxiety and depression(P<0.05). In conclusion, AEO, AFP, and ALI exert anxiolytic and antidepressant effects, and the mechanism might be related to the regulation of the neurotransmitter and the protein expression of GluR1 and VGluT1 in the hippocampus.

Effect of acupuncture combined with low frequency rTMS on comorbid mild-to-moderate depressive disorder and insomnia: a randomized controlled trial / 中国针灸

OBJECTIVE@#To observe the impacts of acupuncture on depressive mood and sleep quality in patients with comorbid mild-to-moderate depressive disorder and insomnia, and explore its effect mechanism.@*METHODS@#A total of 60 patients with comorbid mild-to-moderate depressive disorder and insomnia were randomly divided into an observation group (30 cases, 1 case dropped off) and a control group (30 cases, 2 cases dropped off). In the observation group, acupuncture and low frequency repeated transcranial magnetic stimulation (rTMS) were combined for the intervention. Acupuncture was applied to Baihui (GV 20), Yintang (GV 24+), Neiguan (PC 6) and Yanglingquan (GB 34), etc., the needles were retained for 30 min; and the intradermal needles were embedded at Xinshu (BL 15) and Danshu (BL 19) for 2 days. After acupuncture, the rTMS was delivered at the right dorsolateral prefrontal cortex (R-DLPFC), with 1 Hz and 80% of movement threshold, lasting 30 min in each treatment. In the control group, the sham-acupuncture was adopted, combined with low frequency rTMS. The acupoint selection and manipulation were the same as the observation group. In the two groups, acupuncture was given once every two days, 3 times weekly; while, rTMS was operated once daily, for consecutive 5 days a week. The duration of treatment consisted of 4 weeks. Hamilton depression scale-17 (HAMD-17) and Pittsburgh sleep quality index (PSQI) scores were observed before and after treatment, as well as 1 month after the treatment completion (follow-up period) separately. Besides, the levels of nerve growth factor (BDNF) and γ-aminobutyric acid (GABA) in the serum were detected before and after treatment in the two groups.@*RESULTS@#After treatment and in follow-up, the HAMD-17 scores were lower than those before treatment in the two groups (P<0.05), and the scores in the observation group were lower than the control group (P<0.05). After treatment, the total scores and the scores of each factor of PSQI were reduced in the two groups in comparison with those before treatment except for the score of sleep efficiency in the control group (P<0.05); the total PSQI score and the scores for sleep quality, sleep latency, sleep efficiency and daytime dysfunction in the observation group were all lower than those in the control group (P<0.05). In the follow-up, except for the scores of sleep duration and sleep efficiency in the control group, the total PSQI score and the scores of all the other factors were reduced compared with those before treatment in the two groups (P<0.05); the total PSQI score and the scores of sleep quality, sleep latency, sleep duration, sleep efficiency and daytime dysfunction in the observation group were lower than the control group (P<0.05). After treatment, the levels of serum BDNF and GABA were increased in comparison with those before treatment in the observation group (P<0.05), and the level of serum BDNF was higher than that in the control group (P<0.05).@*CONCLUSION@#Acupuncture relieves depressive mood and improves sleep quality in patients with comorbid mild-to-moderate depressive disorder and insomnia. The effect mechanism may be related to the regulation of BDNF and GABA levels and the promotion of brain neurological function recovery.

Efficient biosynthesis of γ-aminobutyric acid by rationally engineering the catalytic pH range of a glutamate decarboxylase from Lactobacillus plantarum / 生物工程学报

γ-aminobutyric acid can be produced by a one-step enzymatic reaction catalyzed by glutamic acid decarboxylase. The reaction system is simple and environmentally friendly. However, the majority of GAD enzymes catalyze the reaction under acidic pH at a relatively narrow range. Thus, inorganic salts are usually needed to maintain the optimal catalytic environment, which adds additional components to the reaction system. In addition, the pH of solution will gradually rise along with the production of γ-aminobutyric acid, which is not conducive for GAD to function continuously. In this study, we cloned the glutamate decarboxylase LpGAD from a Lactobacillus plantarum capable of efficiently producing γ-aminobutyric acid, and rationally engineered the catalytic pH range of LpGAD based on surface charge. A triple point mutant LpGADS24R/D88R/Y309K was obtained from different combinations of 9 point mutations. The enzyme activity at pH 6.0 was 1.68 times of that of the wild type, suggesting the catalytic pH range of the mutant was widened, and the possible mechanism underpinning this increase was discussed through kinetic simulation. Furthermore, we overexpressed the Lpgad and LpgadS24R/D88R/Y309K genes in Corynebacterium glutamicum E01 and optimized the transformation conditions. An optimized whole cell transformation process was conducted under 40 ℃, cell mass (OD600) 20, 100 g/L l-glutamic acid substrate and 100 μmol/L pyridoxal 5-phosphate. The γ-aminobutyric acid titer of the recombinant strain reached 402.8 g/L in a fed-batch reaction carried out in a 5 L fermenter without adjusting pH, which was 1.63 times higher than that of the control. This study expanded the catalytic pH range of and increased the enzyme activity of LpGAD. The improved production efficiency of γ-aminobutyric acid may facilitate its large-scale production.

Effect of electroacupuncture at the acupoints for Tiaozang Xingshen on cerebral metabolism in the patients with type 2 diabetes mellitus-associated cognitive dysfunction / 中国针灸

OBJECTIVES@#To investigate the cerebral metabolism in the patients with type 2 diabetes mellitus-associated cognitive dysfunction (T2DACD) and explore the mechanism of electroacupuncture (EA) at the acupoints for Tiaozang Xingshen (adjusting zangfu function and rescuing the spirit) in treatment of T2DACD, using magnetic resonance spectroscopy.@*METHODS@#Fifteen patients with T2DACD (observation group) and 22 healthy subjects (control group) were enrolled. In the observation group, the patients were treated with EA for Tiaozang Xingshen at Baihui (GV 20) and Shenting (GV 24), and bilateral Feishu (BL 13), Pishu (BL 20), Shenshu (BL 23), Zusanli (ST 36), Sanyinjiao (SP 6), Hegu (LI 4) and Taichong (LR 3). EA was operated with disperse-dense wave, 2 Hz/100 Hz in frequency and 0.1 mA to 1.0 mA in current intensity; 30 min each time, once daily. One course of EA consisted of 5 treatments, at the interval of 2 days and the intervention lasted 8 courses. Before treatment in the control group, before and after treatment in the observation group, the score of Montreal cognitive assessment scale (MoCA), the score of clinical dementia rating (CDR), Flanker paradigm, Stroop paradigm, Nback paradigm, the score of self-rating anxiety scale (SAS), the score of self-rating depression scale (SDS), and the score of Hamilton depression rating scale (HAMD) were evaluated separately; the glycolipid metabolic indexes (fasting plasma glucose [FPG], glycosylated hemoglobin type A1c [HbA1c], total cholesterol [TC], triacylglycerol [TG], high-density lipoprotein cholesterol [HDL-C] and low-density lipoprotein cholesterol [LDL-C]) were determined；with the magnetic resonance spectroscopy technique adopted, the metabolites in the basal ganglia area were detected. The correlation analysis was performed for the metabolite values with MoCA score, CDR score , Flanker paradigm, Stroop paradigm, and Nback paradigm.@*RESULTS@#Before treatment, compared with the control group, in the observation group, MoCA score was lower (P<0.001), CDR score and the levels of FPG and HbA1c were higher (P<0.001); the reaction times of Flanker non-conflict, Flanker conflict, Stroop neutrality, Stroop congruence, Stroop conflict, and 1-back were prolonged (P<0.05, P<0.001), and the accuracy of Flanker conflict, Stroop conflict, and 1-back decreased (P<0.05, P<0.01); the ratio of N-acetyl aspartate (NAA) to creatine (Cr) in the left basal ganglia area was dropped (P<0.001), and that of myo-inositol (MI) to Cr in the right side increased (P<0.05). In the observation group after treatment, compared with the levels before treatment, MoCA score was higher (P<0.001), the scores of CDR, SAS and HAMD were reduced (P<0.01, P<0.05), the reaction times of Flanker conflict and Stroop conflict shortened (P<0.001, P<0.05), and the accuracy of Flanker conflict and 1-back increased (P<0.001, P<0.05); the ratio of NAA to Cr in the left basal ganglia area and that of the gamma-aminobutyric acid (GABA) to Cr in the right increased (P<0.05), that of MI to Cr in the right decreased (P<0.05). Before treatment, in the observation group, the ratio of MI to Cr in the right basal ganglia area was positively correlated with the reaction time of Stroop congruence (r=0.671, P=0.012) and this ratio was positively correlated with the reaction time of Stroop conflict (r=0.576, P=0.039).@*CONCLUSIONS@#Electroacupuncture for "adjusting zangfu function and rescuing the mind" improves the cognitive function of T2DACD patients, which may be related to the regulation of NAA, MI and GABA levels in the basal ganglia.

Effect of Suanzaoren Decoction on expression of ionotropic glutamate receptors and synaptic plasticity in hippocampus of anxiety rats / 中国中药杂志

This study investigated the effect of Suanzaoren Decoction on the expression of N-methyl-D-aspartate receptors(NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors(AMPAR) in the hippocampus and synaptic plasticity in rats with conditioned fear-induced anxiety. The effect of Suanzaoren Decoction on rat behaviors were evaluated through open field experiment, elevated plus maze experiment, and light/dark box experiment. Enzyme-linked immunosorbent assay(ELISA) was used to measure the levels of glutamate(Glu) and γ-aminobutyric acid(GABA) in the rat hippocampus. Real-time fluorescence quantitative PCR(qRT-PCR) and Western blot were employed to assess the gene and protein expression of ionotropic glutamate receptors in the hippocampal region. Transmission electron microscopy was utilized to observe the changes in the ultrastructure of synaptic neurons in the hippocampal region. Long-term potentiation(LTP) detection technique was employed to record the changes in population spike(PS) amplitude in the hippocampal region of mice in each group. The behavioral results showed that compared with the model group, the Suanzaoren Decoction group effectively increased the number of entries into open arms, time spent in open arms, percentage of time spent in open arms out of total movement time, number of entries into open arms out of total entries into both arms(P<0.01), and significantly increased the time spent in the light box and the number of shuttle crossings(P<0.01). There was an increasing trend in the number of grid crossings, entries into the center grid, and time spent in the center grid, indicating a significant anxiolytic effect. ELISA results showed that compared with the model group, the Suanzaoren Decoction group exhibited significantly reduced levels of Glu, Glu/GABA ratio(P<0.01), and significantly increased levels of GABA(P<0.01) in the rat hippocampus. Furthermore, Suanzaoren Decoction significantly decreased the gene and protein expression of NMDAR(GluN2B and GluN2A) and AMPAR(GluA1 and GluA2) compared with the model group. Transmission electron microscopy results demonstrated improvements in synapses, neuronal cells, and organelles in the hippocampal region of the Suanzaoren Decoction group compared with the model group. LTP detection results showed a significant increase in the PS amplitude changes in the hippocampal region of Suanzaoren Decoction group from 5 to 35 min compared with the model group(P<0.05, P<0.01). In conclusion, Suanzaoren Decoction exhibits significant anxiolytic effects, which may be attributed to the reduction in NMDAR and AMPAR expression levels and the improvement of synaptic plasticity.

Avaliação in silico da atividade ansiolítica de compostos do extrato de camomila (Matricaria recutita) nos receptores GABAa humanos / In silico evaluation of the anxiolytic activity of compounds from chamomile (Matricaria recutita) extract in human GABAa receptors

Objetivo: Avaliar a possível atividade ansiolítica de compostos presentes no extrato padronizado de camomila por meio da interação com o receptor GABAa, como também analisar parâmetros farmacocinéticos das moléculas escolhidas por meio de ferramentas computacionais. Método: Simulação da interação proteína-ligante da apigenina, alfa-bisabolol e camazuleno, por meio de docagem molecular com o receptor GABAa, comparadas com diazepam. Por fim, os parâmetros farmacocinéticos dos três compostos foram calculados, usando a ferramenta on line SwissADME. Resultados: Alfa-bisabolol e camazuleno adequaram-se aos parâmetros farmacocinéticos favoráveis, enquanto a apigenina e o diazepam não atenderam ao perfil de ideal de biodisponibilidade. No estudo docking, as energias de ligação obtidas foram de -5-1 (a-bisabolol), -7,0 (camazuleno), -7,5 (diazepam), e -8.3 kcal/mol (apigenina); também foram observadas ligações do tipo hidrofóbicas, de Van der Waals e interações eletrostáticas. Conclusão: Os parâmetros analisados sugerem a atividade ansiolítica das moléculas estudas. Ademais, mais pesquisas in vivo devem ser realizadas a fim de elucidar os resultados e seus mecanismos e possíveis limitações em humanos.

Objective: To evaluate the possible anxiolytic activity of compounds present in standardized chamomile extract through interaction with the GABAa receptor and to analyze pharmacokinetic parameters of the chosen molecules through computational tools. Methods: Simulation of the protein-ligand interaction of apigenin, alpha-bisabolol, and camazulene by molecular docking with the GABAa receptor compared with diazepam. Finally, the pharmacokinetic parameters of the compounds were calculated using the SwissADME online tool. Results: Alpha-bisabolol and camazulene fit the favorable pharmacokinetic parameters, while apigenin and diazepam did not meet the ideal bioavailability profile. In the docking study. The binding energies obtained were -5-1 ( a-bisabolol), -7.0 (camazulene), -7.5 (diazepam), and -8.3 kcal/mol (apigenin). Hydrophobic bonds, Van der Waals and electrostatic interactions were observed. Conclusion: The parameters analyzed suggest an anxiolytic activity of the molecules studied. Also, more in vivo research to elucidate the results and their human and possible resources used in humans

Gamma-amino butyric acid immunoreactivity in the testis tissue of Wistar and genetic absence epilepsy rats / Inmunorreactividad del ácido gamma-amino butírico en el tejido testicular de ratas Wistar con epilepsia de ausencia genética

SUMMARY: Studies have shown the adverse effects of epileptic seizures on reproductive health. The aim of the present study was to investigate morphological changes, apoptosis and GABA localization in the testis tissue of genetic absence epilepsy rats. Testis tissues of GAERS and Wistar rats were processed for paraffin embedding and electron microscopy. Sections were stained with hematoxylin and eosin, Masson's trichrome and periodic acid-Schiff reaction. GABA immunohistochemistry was applied for determining the alterations in GABA levels. GABA immunoreactivity was observed in the seminiferous tubules and interstitial areas of both GAERS and Wistar rats. GABA immunoreactivity was found to be decreased in GAERS compared to Wistar group. Electron microscopic observations showed that GABA was present in manchette microtubules, sperm tail and neck at different phases of spermiogenesis. Qualitative observations revealed that testis tissues of GAERS showed reduced sperm in the seminiferous tubules compared to the Wistar controls. In conclusion, we demonstrated GABAergic system in the seminiferous tubules of control and GAERS rats, in parallel with the previous studies; and there were alterations in this system in GAERS. We suggest that these alterations in absence epilepsy may also affect the gonadal system, resulting in decreased sperm production.

RESUMEN: Los estudios han demostrado los efectos adversos de las convulsiones epilépticas sobre la salud reproductiva. El objetivo del presente estudio fue investigar los cambios morfológicos, la apoptosis y la localización de GABA en el tejido testicular de ratas con epilepsia de ausencia genética. Se procesaron tejidos testiculares de ratas GAERS y Wistar para inclusión en parafina y microscopía electrónica. Las secciones se tiñeron con hematoxilina y eosina, tricrómico de Masson y reacción de ácido peryódico de Schiff. Se aplicó inmunohistoquímica de GABA para determinar las alteraciones en los niveles de GABA. Se observó inmunorreactividad de GABA en los túbulos seminíferos y las áreas intersticiales de las ratas GAERS y Wistar. Se encontró que la inmunorreactividad de GABA estaba disminuida en GAERS en comparación con el grupo Wistar. Las observaciones microscópicas electrónicas mostraron que GABA estaba presente en los microtúbulos, la cola y el cuello del espermatozoide en diferentes fases de la espermiogénesis. Las observaciones cualitativas revelaron que los tejidos testiculares de GAERS mostraron una reducción de los espermatozoides en los túbulos seminíferos en comparación con los controles Wistar. En conclusión, demostramos el sistema GABAérgico en los túbulos seminíferos de ratas control y GAERS, en paralelo con estudios previos; y además se observaron alteraciones en este sistema en GAERS. Sugerimos que estas alteraciones en epilepisa de ausencia genética también pueden afectar el sistema gonadal, resultando en una disminución de la producción de semen.

Effects of exogenous γ-Aminobutyric acid on the regulation of respiration and protein expression in germinating seeds of mungbean (Vigna radiata) under salt conditions

BACKGROUND: γ-Aminobutyric acid (GABA) bypasses the TCA cycle via GABA shunt, suggesting a relationship with respiration. However, little is known about its role in seed germination under salt conditions. RESULTS: In this study, exogenous GABA was shown to have almost no influence on mungbean seed germination, except 0.1 mM at 10 h, while it completely alleviated the inhibition of germination by salt treatment. Seed respiration was significantly inhibited by 0.1 and 0.5 mM GABA, but was evidently enhanced under salt treatment, whereas both were promoted by 1 mM GABA alone or with salt treatment. Mitochondrial respiration also showed a similar trend at 0.1 mM GABA. Moreover, proteomic analysis further showed that 43 annotated proteins were affected by exogenous GABA, even 0.1 mM under salt treatment, including complexes of the mitochondrial respiratory chain. CONCLUSIONS: Our study provides new evidence that GABA may act as a signal molecule in regulating respiration of mungbean seed germination in response to salt stress.

Na-K-2Cl symporter contributes to γ-aminobutyric acid-evoked excitation in rat enteric neurons / 生理学报

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the adult central nervous system (CNS), however, it causes excitation in the immature CNS neurons. The shift from GABA-induced depolarization to hyperpolarization in postnatal brain is primarily due to progressive decrease in the expression of the Na-K-2Cl symporter 1 (NKCC1) and increased expression of the K-Cl cotransporter 2 (KCC2). Unlike CNS neurons, both immature and mature neurons in the enteric nervous system (ENS) are depolarized by GABA. Molecular mechanisms by which GABA excites ENS neurons are unclear. It is understood, however, that the excitatory action depends on elevated intraneuronal Cl. We aimed to test a hypothesis that high intracellular Cl in ENS neurons is maintained by activity of the NKCCs. We found that NKCC2 immunoreactivity (IR) was expressed in the ENS of the rat colon on postnatal day 1 (P1). The expression level of NKCC2 continuously increased and reached a steady high level on P14 and maintained at that level in adulthood. NKCC1 IR appeared in ENS on P14 and maintained through adulthood. KCC2 IR was not detectable in the ENS in any of the developmental stages. Both NKCC1 IR and NKCC2 IR were co-expressed with GABA receptors in ENS neurons. Exogenous GABA (1 mmol/L) caused membrane depolarization in the ENS neurons. The reversal potential of GABA-induced depolarization was about -16 mV. Blockade of NKCC by bumetanide (50 μmol/L) or furosemide (300 μmol/L) suppressed the depolarizing responses to GABA. Bumetanide (50 μmol/L) shifted the reversal potential of GABA-induced depolarization in the hyperpolarizing direction. Neither the KCC blocker DIOA (20 μmol/L) nor the Cl/HCO exchanger inhibitor DIDS (200 μmol/L) suppressed GABA-evoked depolarization. The results suggest that ENS neurons continuously express NKCC2 since P1 and NKCC1 since P14, which contribute to the accumulation of Cl in ENS neurons and GABA-evoked depolarization in neonate and adult ENS neurons. These results provide the first direct evidence for the contribution of both NKCC2 and NKCC1 to the GABA-mediated depolarization.

Calpain-2 as a Treatment Target in Prenatal Stress-induced Epileptic Spasms in Infant Rats

Stress can induce a serious epileptic encephalopathy that occurs during early infancy. Recent studies have revealed that prenatal stress exposure is a risk factor for the development of infantile spasms. Our previous work demonstrates that prenatal stress with betamethasone-induced alterations to the expression of the K⁺/Cl⁻ co-transporter (KCC2) in gamma-aminobutyric acid (GABA) interneurons lowers the seizure threshold in exposed animals. Here, we further investigated the mechanisms involved in this KCC2 dysfunction and explored possible treatment options. We stressed Sprague-Dawley rats prenatally and further treated dams with betamethasone on gestational day 15, which increases seizure susceptibility and NMDA (N-Methyl-D-aspartate)-triggered spasms on postnatal day 15. In this animal model, first, we evaluated baseline calpain activity. Second, we examined the cleavage and dephosphorylation of KCC2. Finally, we checked the effect of a calpain inhibitor on seizure occurrence. The phosphorylated-N-methyl-D-aspartate Receptor 2B (NR2B):non-phosphorylated NR2B ratio was found to be higher in the cortex of the prenatally stressed beta-methasone model. We further found that the betamethasone model exhibited increased phosphorylation of calpain-2 and decreased phosphorylation of KCC2 and Glutamic acid decarboxylase 67 (GAD67). After using a calpain inhibitor in prenatal-stress rats, the seizure frequency decreased, while latency increased. GABAergic depolarization was further normalized in prenatal-stress rats treated with the calpain inhibitor. Our study suggests that calpain-dependent cleavage and dephosphorylation of KCC2 decreased the seizure threshold of rats under prenatal stress. Calpain-2 functions might, thus, be targeted in the future for the development of treatments for epileptic spasms.

The Effect of Oral Administration of Black Sticky Rice with Giant Embryo on Brain GABA Concentrations

OBJECTIVE: Black sticky rice with giant embryo (BSRGE) contains high GABA content and affects alcohol-related indices among social drinkers, and alcohol intake and anxiety-related behavior of mice. However, it is unknown whether the intake of BSRGE affects GABAergic activity of brain directly. The purpose of this study is to elucidate the effect of oral administration of BSRGE on brain GABA concentrations compared with commercially available GABA compound and regular feeds. METHODS: Twenty-one male C57BL/6 mice were assigned to BSRGE, a regular feed (AIN-76) lacking GABA, and a regular feed containing GABA compound. After feeding freely for 48 h, the cortex and striatum were separated from the brain. An enzyme-linked immunosorbent assay was conducted to measure GABA and glutamate concentrations in mouse brain. RESULTS: The GABA concentration of the BSRGE group was higher than that of regular feed and GABA compound group (p<0.001). However, the GABA compound group showed no significant difference from the regular feed group (p=0.50). CONCLUSION: Intake of BSRGE containing high GABA content increased GABA concentrations in mouse brain compared with regular feed unlike GABA compound. The results of this study constitute an important basis for further investigations into the clinical applications of BSRGE.

Glial Cell Line-derived Neurotrophic Factor-overexpressing Human Neural Stem/Progenitor Cells Enhance Therapeutic Efficiency in Rat with Traumatic Spinal Cord Injury

Spinal cord injury (SCI) causes axonal damage and demyelination, neural cell death, and comprehensive tissue loss, resulting in devastating neurological dysfunction. Neural stem/progenitor cell (NSPCs) transplantation provides therapeutic benefits for neural repair in SCI, and glial cell line-derived neurotrophic factor (GDNF) has been uncovered to have capability of stimulating axonal regeneration and remyelination after SCI. In this study, to evaluate whether GDNF would augment therapeutic effects of NSPCs for SCI, GDNF-encoding or mock adenoviral vector-transduced human NSPCs (GDNF-or Mock-hNSPCs) were transplanted into the injured thoracic spinal cords of rats at 7 days after SCI. Grafted GDNF-hNSPCs showed robust engraftment, long-term survival, an extensive distribution, and increased differentiation into neurons and oligodendroglial cells. Compared with Mock-hNSPC- and vehicle-injected groups, transplantation of GDNF-hNSPCs significantly reduced lesion volume and glial scar formation, promoted neurite outgrowth, axonal regeneration and myelination, increased Schwann cell migration that contributed to the myelin repair, and improved locomotor recovery. In addition, tract tracing demonstrated that transplantation of GDNF-hNSPCs reduced significantly axonal dieback of the dorsal corticospinal tract (dCST), and increased the levels of dCST collaterals, propriospinal neurons (PSNs), and contacts between dCST collaterals and PSNs in the cervical enlargement over that of the controls. Finally grafted GDNF-hNSPCs substantially reversed the increased expression of voltage-gated sodium channels and neuropeptide Y, and elevated expression of GABA in the injured spinal cord, which are involved in the attenuation of neuropathic pain after SCI. These findings suggest that implantation of GDNF-hNSPCs enhances therapeutic efficiency of hNSPCs-based cell therapy for SCI.

Screening and identification of GABA-producing microbes in fermentation process of Sojae Semen Praeparatum / 中国中药杂志

A high-content GABA was found in Sojae Semen Praeparatum(SSP), which is a famous traditional Chinese medicine and officially listed in Chinese Pharmacopoeia. To screen out and identify GABA-producing microbes from samples at different time points during the fermenting process of SSP, traditional microbiological methods combined with molecular biological methods were used to study the predominant GABA-producing microorganisms existing in the fermenting process of SSP. This study would lay a foundation for further studying the processing mechanism of SSP. The fermenting process of SSP was based on Chinese Pharmacopoeia(2010 edition), and samples were taken at different time points during the fermenting process of SSP. The bacteria and fungi from samples at different time points in the fermenting process of SSP were cultured, isolated and purified by selective medium, and dominant strains were selected. The dominant bacteria were cultured in the designated liquid medium to prepare the fermentation broths, and GABA in the fermentation broth was qualitatively screened out by thin-layer chromatography. The microbial fermentation broth with GABA spots in the primary screening was quantitatively detected by online pre-column derivatization and high performance liquid chromatography established in our laboratory. GABA-producing microorganisms were screened out from predominant strains, and their GABA contents in fermentation broth were determined. The DNA sequences of GABA-producing bacteria and fungi were amplified using 16S rDNA and 18S rDNA sequences by PCR respectively. The amplified products were sequenced, and the sequencing results were identified through NCBI homology comparison. Molecular biological identification was made by phylogenetic tree constructed by MEGA 7.0 software. Through the homology comparison of NCBI and the construction of phylogenetic tree by MEGA 7.0 software, nine GABA-producing microorganisms were screened out and identified in this study. They were Bacillus subtilis, Enterococcus faecium, E. avium, Aspergillus tamarii, A. flavus, A. niger, Cladosporium tenuissimum, Penicillium citrinum and Phanerochaete sordida respectively. For the first time, nine GABA-producing microorganisms were screened out and identified in the samples at different time points during the fermenting process of SSP in this study. The results indicated that multiple predominant GABA-producing microorganisms exist in the fermenting process of SSP and may play an important role in the formation of GABA.

Dexmedetomidine and propofol sedation requirements in an autistic rat model / 대한마취과학회지

BACKGROUND: Autism is a challenging neurodevelopmental disorder. Previous clinical observations have suggested altered sedation requirements for children with autism. Our study aimed to test this observation experimentally in an animal model and to explore its possible mechanisms. METHODS: Eight adult pregnant female Sprague-Dawley rats were randomly divided into two groups. Four were injected with intraperitoneal sodium valproate on gestational day 12 and four were injected with normal saline. On postnatal day 28, the newborn male rats were subjected to the open-field test to confirm autistic features. Each rat was injected intraperitoneally with a single dose of propofol (50 mg/kg) or dexmedetomidine (0.2 mg/kg). The times to loss of righting reflex (LORR) and to return of righting reflex (RORR) were recorded. On the following day, all rats were re-sedated and underwent electroencephalography (EEG). Thereafter, the rats were euthanized and their hippocampal gamma-aminobutyric acid type A (GABA(A)) and glutamate N-methyl-D-aspartate (NMDA) receptor gene expressions were assessed. RESULTS: Autistic rats showed significantly longer LORR times and shorter RORR times than did the controls (median LORR times: 12.0 versus 5.0 min for dexmedetomidine and 22.0 versus 8.0 min for propofol; P < 0.05). EEG showed a low-frequency, high-amplitude wave pattern 2 min after LORR in the control rats. Autistic rats showed a high-frequency, low-amplitude awake pattern. Hippocampal GABA(A) receptor gene expression was significantly lower and NMDA gene expression was greater in autistic rats. CONCLUSIONS: This study supports the clinical observations of increased anesthetic sedative requirements in children with autism and our biochemical analyses using and glutamate receptor gene expression highlight possible underlying mechanisms.

The antinociceptive effect of artemisinin on the inflammatory pain and role of GABAergic and opioidergic systems

BACKGROUND: Pain is a complex mechanism which involves different systems, including the opioidergic and GABAergic systems. Due to the side effects of chemical analgesic agents, attention toward natural agents have been increased. Artemisinin is an herbal compound with widespread modern and traditional therapeutic indications, which its interaction with the GABAergic system and antinoniceptive effects on neuropathic pain have shown. Therefore, this study was designed to evaluate the antinociceptive effects of artemisinin during inflammatory pain and interaction with the GABAergic and opioidergic systems by using a writhing response test. METHODS: On the whole, 198 adult male albino mice were used in 4 experiments, including 9 groups (n = 6) each with three replicates, by intraperitoneal (i.p.) administration of artemisinin (2.5, 5, and 10 mg/kg), naloxone (2 mg/kg), bicuculline (2 mg/kg), saclofen (2 mg/kg), indomethacin (5 mg/kg), and ethanol (10 mL/kg). Writhing test responses were induced by i.p. injection of 10 mL/kg of 0.6% acetic acid, and the percentage of writhing inhibition was recorded. RESULTS: Results showed significant dose dependent anti-nociceptive effects from artemisinin which, at a 10 mg/kg dose, was statistically similar to indomethacin. Neither saclofen nor naloxone had antinociceptive effects and did not antagonize antinociceptive effects of artemisinin, whereas bicuculline significantly inhibited the antinocicptive effect of artemisinin. CONCLUSIONS: It seems that antinocicptive effects of artemisinin are mediated by GABAA receptors.

Astrocytic proBDNF and Tonic GABA Distinguish Active versus Reactive Astrocytes in Hippocampus

Astrocytes are the most abundant cell type in the brain and they make close contacts with neurons and blood vessels. They respond dynamically to various environmental stimuli and change their morphological and functional properties. Both physiological and pathological stimuli can induce versatile changes in astrocytes, as this phenomenon is referred to as ‘astrocytic plasticity’. However, the molecular and cellular mechanisms of astrocytic plasticity in response to various stimuli remain elusive, except for the presence of hypertrophy, a conspicuous structural change which is frequently observed in activated or reactive astrocytes. Here, we investigated differential characteristics of astrocytic plasticity in a stimulus-dependent manner. Strikingly, a stab wound brain injury lead to hypertrophy of astrocytes accompanied by increased GABA expression and tonic GABA release in mouse CA1 hippocampus. In contrast, the mice experiencing enriched environment exhibited astrocytic hypertrophy with enhanced proBDNF immunoreactivity but without GABA signal. Based on the results, we define proBDNF-positive/GABA-negative hypertrophic astrocytes as ‘active’ astrocytes and GABA-positive hypertrophic astrocytes as ‘reactive’ astrocytes, respectively. We propose for the first time that astrocytic proBDNF can be a bona fide molecular marker of the active astrocytes, which are distinct from the reactive astrocytes which show hypertrophy but with aberrant GABA.

Fatty Acid Increases cAMP-dependent Lactate and MAO-B-dependent GABA Production in Mouse Astrocytes by Activating a G(αs) Protein-coupled Receptor

Medium-chain fatty acids (MCFAs) are mostly generated from dietary triglycerides and can penetrate the blood-brain barrier. Astrocytes in the brain use MCFAs as an alternative energy source. In addition, MCFAs have various regulatory and signaling functions in astrocytes. However, it is unclear how astrocytes sense and take up MCFAs. This study demonstrates that decanoic acid (DA; C10), a saturated MCFA and a ligand of G(αs) protein-coupled receptors (G(αs)-GPCRs), is a signaling molecule in energy metabolism in primary astrocytes. cAMP synthesis and lactate release were increased via a putative G(αs)-GPCR and transmembrane adenylyl cyclase upon short-term treatment with DA. By contrast, monoamine oxidase B-dependent gamma-aminobutyric acid (GABA) synthesis was increased in primary cortical and hypothalamic astrocytes upon long-term treatment with DA. Thus, astrocytes respond to DA by synthesizing cAMP and releasing lactate upon short-term treatment, and by synthesizing and releasing GABA upon long-term treatment, similar to reactive astrocytes. Our data suggest that astrocytes in the brain play crucial roles in lipid-sensing via GPCRs and modulate neuronal metabolism or activity by releasing lactate via astrocyte-neuron lactate shuttle or GABA to influence neighboring neurons.