Relationship between mechanism underlying antidepressant effect of S-ketamine and hippocampal GABA BR in mice / 中华麻醉学杂志

Objective:To evaluate the relationship between the mechanism underlying the antidepressant effect of S-ketamine and hippocampal gamma-aminobutyric acid B receptor (GABA BR) in mice. Methods:A total of 54 male C57BL/6(B6) mice, aged 8 weeks, weighing 25-30 g, were used in this study. Forty mice were selected to develop the depression model by chronic social defeat stress. Twenty-six depression-susceptible mice were screened out by social avoidance test at day 11 after developing the model and divided into 2 groups ( n=13 each) by a random number table method: depression-susceptible group (Sus group) and depression-susceptible + S-ketamine group (Sus + S-ket group). The remaining 14 mice served as control group (C group). Starting from day 12 after developing the model, S-ketamine 10 mg/kg was intraperitoneally injected every day for 3 consecutive days in Sus+ S-ket group, while the equal volume of normal saline was given instead in C group and Sus group. The open field test was performed at 1 h after the last administration, and the total distance of movement was recorded. The forced swimming test was performed at 1 day after the open field test, and the immobile time was recorded. The sucrose preference test was performed to calculate the proportion of sucrose consumption at 1 day after the forced swimming test. One hour after the end of behavioral test, mice were sacrificed, and the hippocampal tissues were removed. Western blot was used to detect the expression of GABA BR1, GABA BR2, mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), phosphorylated TrkB (p-TrkB), glutamate receptor 1 (GluR1) and postsynaptic dense protein 95 (PSD95). The p-mTOR/mTOR ratio and p-TrkB/TrkB ratio were calculated. The fluorescence intensity of BDNF in hippocampal CA1 region was detected by immunofluorescence. The number of dendritic spines in hippocampal CA1 region was measured by Golgi staining. Results:In the open field test, no statistically significant difference in the total distance was detected among the three groups ( P>0.05). Compared with C group, the immobile time in the forced swimming test was significantly prolonged, the proportion of sucrose consumption was decreased, the expression of hippocampal GABA BR1, GABA BR2, BDNF, GluR1 and PSD95 was down-regulated, and the ratios of p-mTOR/mTOR and p-TrkB/TrkB were decreased, the fluorescence intensity of BDNF and total number of dendritic spines in the hippocampal CA1 region were decreased in Sus group ( P<0.05), and no significant change was found in the parameters mentioned above in Sus+ S-ket group ( P>0.05). Compared with Sus group, the immobile time in the forced swimming test was significantly shortened, the proportion of sucrose consumption was increased, the expression of hippocampal GABA BR1, GABA BR2, BDNF, GluR1 and PSD95 was up-regulated, the ratios of p-mTOR/mTOR and p-TrkB/TrkB were increased, and the fluorescence intensity of BDNF and total number of dendritic spines in the hippocampal CA1 region were increased in Sus+ S-ket group ( P<0.05). Conclusions:The mechanism underlying the antidepressant effect of S-ketamine may be related to up-regulation of hippocampal GABA BR expression, activation of mTOR-BDNF signaling pathway, and improvement in synaptic plasticity in mice.

Phytohormone abscisic acid boosts pentobarbital-induced sleep through activation of GABA-A, PPARß and PPARγ receptor signaling / O fito-hormônio ácido abscísico estimula o sono induzido por fenobarbital por meio de ativação da sinalização de receptores GABA-A, PPARß e PPARγ

ABSTRACT Background: Sleep disorders induce anxiety and forgetfulness and change habits. The chemical hypnotic drugs currently used have serious side effects and, therefore, people are drawn towards using natural compounds such as plant-based healing agents. Abscisic acid (ABA) is produced in a variety of mammalian tissues and it is involved in many neurophysiological functions. Objective: To investigate the possible effect of ABA on pentobarbital-induced sleep and its possible signaling through GABA-A and PPAR (γ and β) receptors, in male Wistar rats. Methods: The possible effect of ABA (5 and 10 µg/rat, intracerebroventricularly) on sleep onset latency time and duration was evaluated in a V-maze model of sleep. Pentobarbital sodium (40 mg/kg, intraperitoneally) was injected to induce sleep 30 min after administration of ABA. PPARβ (GSK0660, 80 nM/rat), PPARγ (GW9662, 3 nM/rat) or GABA-A receptor (bicuculline, 6 µg/rat) antagonists were given 15 min before ABA injection. Diazepam (2 mg/kg, intraperitoneally) was used as a positive control group. Results: ABA at 5 µg significantly boosted the pentobarbital-induced subhypnotic effects and promoted induction of sleep onset in a manner comparable to diazepam treatment. Furthermore, pretreatment with bicuculline significantly abolished the ABA effects on sleep parameters, while the amplifying effects of ABA on the induction of sleep onset was not significantly affected by PPARβ or PPARγ antagonists. The sleep prolonging effect of ABA was significantly prevented by both PPAR antagonists. Conclusions: The data showed that ABA boosts pentobarbital-induced sleep and that GABA-A, PPARβ and PPARγ receptors are, at least in part, involved in ABA signaling.

RESUMO Introdução: Os distúrbios do sono induzem a ansiedade e esquecimento e mudam hábitos. Os medicamentos hipnóticos químicos utilizados atualmente têm efeitos colaterais graves e, portanto, as pessoas são atraídas para o uso de compostos naturais, como agentes de cura à base de plantas. O ácido abscísico (ABA) é produzido em uma variedade de tecidos de mamíferos e está envolvido em muitas funções neurofisiológicas. Objetivo: Investigar o possível efeito do ABA no sono induzido por pentobarbital e sua possível sinalização por meio dos receptores GABA-A e PPAR (γ e β), em ratos Wistar machos. Métodos: O possível efeito do ABA (5 e 10 µg/rato, intracerebroventricularmente) no tempo de latência e duração do início do sono foi avaliado em um modelo de labirinto em V de sono. Pentobarbital sódico (40 mg/kg, intraperitonealmente) foi injetado para induzir o sono 30 minutos após a administração de ABA. PPARβ (GSK0660, 80 nM/rato), PPARγ (GW9662, 3 nM/rato) ou antagonistas do receptor GABA-A (bicuculina, 6 µg/rato) foram administrados 15 minutos antes da injeção de ABA. Diazepam (2 mg/kg, intraperitonealmente) foi utilizado como grupo de controle positivo. Resultados: ABA a 5 µg aumentou significativamente os efeitos sub-hipnóticos induzidos por pentobarbital e promoveu a indução do início do sono de forma comparável ao tratamento com diazepam. Além disso, o pré-tratamento com bicuculina aboliu significativamente os efeitos do ABA nos parâmetros do sono, ao passo que os efeitos amplificadores do ABA na indução do início do sono não foram significativamente afetados pelos antagonistas do PPARβ ou PPARγ. O efeito de prolongamento do sono do ABA foi significativamente prevenido por ambos os antagonistas do PPAR. Conclusões: Os dados mostraram que o ABA estimula o sono induzido por pentobarbital e que os receptores GABA-A, PPARβ e PPARγ estão, pelo menos em parte, envolvidos na sinalização ABA.

Progress in research on the role of cannabinoid receptor 1 signaling pathway in epilepsy / 中华神经科杂志

Epilepsy,a group of chronic neurological disorders characterized by spontaneous and recurrent seizures and learning and memory impairments,results in transient brain dysfunction due to sudden abnormal discharge of brain neurons.The pathogenesis of epilepsy is very complicated and has not yet been fully elucidated.The imbalance between excitatory glutamate and inhibitory gamma-aminobutyric acid (GABA) neurotransmitters in the central nervous system and changes in ionic functions of N-methyl-D-aspartate receptors directly induce epileptic seizures.The endocannabinoid system plays an important role in retrograde synaptic transmission and exerts the anti-epileptic effect in cannabinoid receptor 1 (CBR1) dependent manner by regulating the synaptic transmission of glutamatergic and GABAergic neurons and homeostatsis of ionic channel function.Elucidating the specific mechanism of action of CBR1 signaling pathway in epilepsy,can provide an effective theoretical basis and novel drug's target for clinical treatment of epilepsy.

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.

Effect of oxycodone on function of GABAA receptors in dorsal root ganglion neurons of rats with neuropathic pain / 中华麻醉学杂志

Objective To evaluate the effect of oxycodone on function of GABAA receptors in dor-sal root ganglion ( DRG ) neurons of rats with neuropathic pain ( NP ) . Methods Thirty-six adult male Sprague-Dawley rats, weighing 180-220 g, aged 10 weeks, were allocated into 3 groups ( n=12 each) u-sing a random number table method: sham operation group ( group S ) , group NP and oxycodone group ( group O) . The sciatic nerve was only isolated but not ligated in group S. NP was induced by chronic con-striction injury. The sciatic nerve was exposed and 4 loose ligatures were placed on the sciatic nerve at 1 mm intervals with 4-0 chromic catgut. Oxycodone 15μg∕kg was intraperitoneally injected once a day for 14 con-secutive days from ligating the sciatic nerve to satisfaction in group O. The thermal paw withdrawal latency( TWL) was measured at 1 day before establishing the model ( T0 ) and 3, 5, 7, 10 and 14 days after es-tablishing the model ( T1-5 ) . The rats were sacrificed after measurement of pain threshold at T5 , and DRG neurons were acutely isolated for recording the amplitude of GABAA receptors-activated currents using whole-cell patch-clamp technique. Results Compared with group S, the TWL was significantly shortened at T1-5, and the amplitude of GABAA receptors-activated currents in DRG neurons was decreased in NP and O groups (P<0. 05). Compared with group NP, the TWL was significantly prolonged at T1-5, and the ampli-tude of GABAA receptors-activated currents in DRG neurons was increased in group O ( P<0. 05) . Conclu-sion Oxycodone can enhance the function of GABAA receptors-activated currents in DRG neurons and thus enhance GABAA receptors-mediated presynaptic inhibition, which may be related to the mechanism of oxyc-odone-induced reduction of NP in rats.

Changes in expression of gamma-aminobutyric acid receptor subunit genes in dorsal root ganglia in a mouse model of neuropathic pain / 中华麻醉学杂志

Objective To evaluate the changes in the expression of gamma-aminobutyric acid (GABA) receptor subunit genes in the dorsal root ganglia (DRG) in a mouse model of neuropathic pain. Methods Experiment Ⅰ Twenty-four male C57BL6 mice, aged 8 weeks, weighing 25-30 g, were di-vided into sham operation group (group Sham, n=12) and neuropathic pain group (group NP, n=12) by using a random number table method. Neuropathic pain was produced by bilateral L4 spinal nerve ligation in anesthetized mice in group NP . The mechanical pain threshold of bilateral hindpaws was measured at 1 day before establishing the model and 7 days after establishing the model. Mice were then sacrificed and DRGs of the bilateral L4 were removed to perform transcriptome sequencing and to analyze the expression of GABA receptor subunit genes. Experiment Ⅱ Twenty-four male C57BL6 mice, aged 8 weeks, weighing 25-30 g, were studied. Neuropathic pain was produced by the left L4 spinal nerve ligation in anesthetized mice. Six mice were selected at 1 day before establishing the model and 3, 7 and 14 days after establishing the model, and the mechanical pain threshold of the left hindpaw was measured. Mice were then sacrificed and DRGs of the left L4 were removed to verify the expression of differentially expressed GABA receptor subunitgenes described in experiment Ⅰby quantitative real-time polymerase chain reaction. Results ExperimentⅠ Compared with group Sham, the mechanical pain threshold was significantly increased, the expression of Gabra1, Gabra2, Gabrb3, Gabrg2, Gabbr1 and Gabbr2 in DRGs was down-regulated, and the expres-sion of Gabrg1 in DRGs was up-regulated at 7 days after establishing the model in group NP ( P<0. 05 or 0. 01) . Experiment Ⅱ Compared with the baseline at 1 day before establishing the model, the mechanical pain threshold was significantly increased, and the expression of Gabra1, Gabra2, Gabrb3, Gabrg2, Gab-br1 and Gabbr2 in DRGs was down-regulated at each time point after establishing the model ( P<0. 05 or 0. 01) , and no significant change was found in the expression of Gabrg1 in DRGs at each time point after establishing the model ( P>0. 05) . Conclusion The expression of GABA receptor subunit genes Gabra1, Gabra2, Gabrb3, Gabrg2, Gabbr1 and Gabbr2 in DRGs is down-regulated, and the expression of Gabrg1 in DRGs is up-regulated in a mouse model of neuropathic pain.

A prescrição de benzodiazepínicos no Brasil: uma análise da literatura / The prescription of benzodiazepines in Brazil: a literature review

Benzodiazepínicos são medicamentos psicotrópicos de prescrição restrita e sujeitos a controle especial, conforme a Portaria nº 344, de 12 de maio de 1998. São utilizados como hipnóticos e sedativos, sendo bastante comuns na prática clínica. O uso prolongado destes fármacos pode causar dependência e por isso é necessário identificar seu perfil de prescrição. Este estudo busca revisar a literatura sobre os trabalhos que descreveram o uso de benzodiazepínicos no Brasil. Para isso, uma busca direta foi realizada em três bases de dados, Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), PubMed e Scientific Eletronic Library Online (SciELO), utilizando os descritores prescrição/prescription, benzodiazepínicos/benzodiazepines, Brasil/Brazil. Depois de aplicados os critérios de inclusão e exclusão, restaram 12 artigos, os quais foram analisados. A análise destes trabalhos mostrou que, no Brasil, os benzodiazepínicos são utilizados especialmente por mulheres com tendência ao aumento do uso com o avançar da idade. Desta maneira, conclui-se que permanece a necessidade de políticas públicas que busquem o uso racional destes fármacos.

Benzodiazepines are prescription restricted psychotropic drugs, subject to special control according to Decree nº 344 of May 12, 1998. They are used as hypnotics and sedatives, being widely used in clinical practice. Prolonged use of these drugs can cause dependence, and therefore it is necessary to identify their prescription profile. This study aims to review the literature on studies that described the use of benzodiazepines in Brazil. For such, a direct search was conducted in databases, such as LILACS, Pubmed and SciELO, with the descriptors, in Portuguese and English, "prescrição" (prescription), "benzodiazepínicos" (benzodiazepines) and "Brasil" (Brazil). After applying the criteria for inclusion and exclusion, 12 articles remained, which were analyzed in this work. The analysis of these data has shown that, in Brazil, benzodiazepines are used especially by women with a tendency to increased use with advancing age. On this wat, we might conclude that Brazil's needs to improve his politics to promote rational use of Benzodiazepines.

Effects of different ratios of medicine dosage for isoflurane and propofol on GABAAreceptor α1sub-unit proteostasis during hypoxia injury to hippocampal neurons of rats / 中华麻醉学杂志

Objective To evaluate the effects of different ratios of medicine dosage for isoflurane and propofol on GABAAreceptor(GABAAR)α1subunit proteostasis during hypoxia injury to hippocampal neurons of rats. Methods The hippocampal neurons isolated from fetal rats obtained from Wistar rats were primarily cultured and divided into 6 groups(n=60 each)using a random number table: control group (group C), hypoxia group(group H), isoflurane group(group I), propofol group(group P)and dif-ferent ratios of medicine dosage for isoflurane and propofol groups(group IP1and group IP2). The cells were subjected to hypoxia for 6 h in group H. Cells were incubated for 3 h with 1.9 % isoflurane and with 22.4 μmol∕L propofol after being subjected to hypoxia for 6 h in I and P groups, respectively. Cells were incubated for 3 h with 1.0% isoflurane and 6.7 μmol∕L propofol and with 1.4% isoflurane and 3.4 μmol∕L propofol after being subjected to hypoxia for 6 h in IP1and IP2groups, respectively. Then the culture medi-um was replaced with plain culture medium. At 24 h of incubation, the cells were collected for measure-ment of cell viability by CCK-8 assay, GABAAR α1mRNA expression(by quantitative polymerase chain reaction), GABAAR α1expression in the cytomembrane(by Western blot), level of GABAAR α1subunit endoplasmic reticulum-associated degradation(ERAD)(by immunoprecipitation and Western blot)and CCAAT∕enhancer-binding protein homologous protein(CHOP)expression(by immunofluorescence). Re-sults Compared with group C, the cell viability was significantly decreased, the expression of GABAAR α1mRNA and GABAAR α1in cytomembrane was down-regulated, the expression of CHOP was up-regula-ted, and the level of GABAAR α1subunit ERAD was increased in the other five groups(P<0.05). Com-pared with group H, the cell viability was significantly decreased, the expression of GABAAR α1mRNA and GABAAR α1in cytomembrane was down-regulated, the expression of CHOP was up-regulated, and the level of GABAAR α1subunit ERAD was increased in I, P and IP2groups(P <0.05), and no significant change was found in the parameters mentioned above in group IP1(P<0.05). Compared with group I or group P, the cell viability was significantly increased, the expression of GABAAR α1mRNA and GABAAR α1 in cytomembrane was up-regulated, the expression of CHOP was down-regulated, and the level of GABAAR α1subunit ERAD was decreased in IP1and IP2groups(P<0.05). Compared with group IP1, the cell viability was significantly decreased, the expression of GABAAR α1mRNA and GABAAR α1in cy-tomembrane was down-regulated, the expression of CHOP was up-regulated, and the level of GABAAR α1 subunit ERAD was increased in group IP2(P<0.05). Conclusion Combination of 1.0% isoflurane and 6.7 μmol∕L propofol does not aggravate hypoxia-induced destruction of GABAAR α1subunit proteostasis in hippocampal neurons of rats.

Encefalitis autoinmune por anticuerpos contra el receptor GABA-A: caso clínico / Autoimmune encephalitis induced by antibodies against GABA-A receptor

Among autoimmune encephalitides, a prevalent group are those associated with antibodies against the N-Methyl-D-aspartate receptor, which present with behavior abnormalities, psychosis, seizures and abnormal movements. A new variant, mediated by antibodies against the GABA-A receptor, was recen­tly described. We report a 66-years-old female with this form of encephalitis whose main manifestation was the presence of severe seizures leading to status epilepticus. The patient had a good response to immunomodulatory therapy with intravenous methylprednisolone, azathioprine and anticonvulsants. The laboratory tests initially detected anti-thyroid peroxidase antibodies which lead to the misdiagnosis of Hashimoto Encephalitis, which was ruled out after the detection of antibodies against GABA-A receptor. No malignancy was detected.

Clinical analysis of autoimmune encephalitis with co-existence of multiple anti-neuronal antibodies / 中华神经科杂志

Objective To explore the clinical significance of expressing multiple autoantibodies in patients with autoimmune encephalitis.Methods Cerebrospinal fluid and serum were tested in patients with undefined encephalitis admitted to Peking Union Medical College Hospital from May 2013 to December 2014.Indirect immunofluorescence test was firstly used to identify the antibodies to neuronal cell-surface or synaptic receptors (including N-methyl-D-aspartate receptor (NMDAR),contactin-associated protein-like 2 (CASPR2),α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR),leucine-rich glioma inactivated protein 1 (LGI1),and gamma-aminobutyric acid beta receptor (GABABR)).In those patients with positive antibodies,antibodies against intracellular neuronal antigens associated with paraneoplastic neurological symptoms were tested.Anti-aquaporin protein-4 (AQP4) antibody was tested depending on patients' clinical manifestations.Results Ten patients were detected combined with additional autoantibodies in 531 patients with positive antibodies related to autoimmune encephalitis.AntiHu antibody was positive in 5 patients with anti-GABABR encephalitis,in 1 of whom anti-NMDAR antibody was also identified;anti-AQP4 antibody was positive in 1 patient with relapsing anti-NMDAR encephalitis;anti-CASPR2 and anti-Yo antibodies were respectively positive in 2 patients with anti-LGI1 encephalitis;anti-CV2 and anti-Hu antibodies were respectively positive in 2 patients with anti-AMPAR encephalitis.Clinical presentation of all cases was consistent with typical encephalitis or limbic encephalitis.Brain stem was involved in 3 patients.Peripheral sensory neuropathy was present in 1 patient,while myalgia and fasciculation were present in 1 patient.Seven patients responded well to the immunotherapy.Tumors were pathologically or radiologically confirmed in 7 cases,including lung cancer in 5 cases,suspected thymoma in 1 case and highly suspected mediastinal tumor without pathological identification in 1 case.Conclusions Due to the pathological mechanism,co-existence of multiple autoantibodies affects clinical manifestations of patients and results in variation and overlap of them.The additional positivity of onconeuronal antibodies directs the search for occult tumor.

An analysis and literature review of two cases of autoimmune encephalitis with GABAB receptor antibodies / 中华内科杂志

Autoimmune encephalitis with GABAB receptor antibodies has been rarely reported.Two cases of GABAB receptor antibodies encephalitis were presented here.Epilepsy was the onset symptom,followed by declined consciousness and frequent seizures.Fever was presented in the whole course of the disease.Myorhythmia of the two hands and pilomotor seizures were shown in the later course of the disease.No specificity was demonstrated in electroencephalograms and magnetic resonance imaging.Sensitive response was shown to the first-line immunotherapy.

Utilização de benzodiazepínicos e estratégias farmacêuticas em saúde mental / Use of benzodiazepines and drug strategies in mental health

O artigo enfoca a heterogeneidade no uso de benzodiazepínicos, sob o enfoque farmacêutico, observada nos Centros de Atenção Psicossocial e Unidades Básicas de Saúde da Família. Os benzodiazepínicos estão incluídos entre os medicamentos mais prescritos para tratar distúrbios de ansiedade. Os avanços da reforma psiquiátrica, a criação dos Centros de Atenção Psicossocial (Caps) e o redirecionamento das atividades de saúde primária tornam imperiosa a adequação da prática farmacêutica através de atividades de orientação e acolhimento ao usuário de benzodiazepínicos.

This article focuses on the discrepancies in the use of benzodiazepines, under the pharmaceutical approach, observed daily in Centers of Psychosocial Care (Caps) and in Basic Units of Family Health. Benzodiazepines are among the most prescribed medications for the treatment of anxiety disorders. Advances in psychiatric reform, the creation of Caps and the new approach to primary health activities make imperative the adequacy of pharmaceutical practice through guidance and care activities to benzodiazepines' users.

Effects of propofol on hippocampal GABAA and NMDA receptor expression in a rat model of inflammatory pain / 中华麻醉学杂志

Objective To evaluate the effects of propofol on the expression of hippocampal γ-aminobutyric acid (GABAA) and NMDA receptor in a rat model of inflammatory pain (IP).Methods A total of 32 female Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 4 groups (n =8 each):control group (group C),group IP,and different doses of propofol groups (P1,2 groups).IP was induced by injection of formalin.In group C,normal saline and dimethyl sulfoxide (DMSO) 0.1 ml/kg were injected intraperitoneally.In group IP,normal saline and DMSO 0.1 ml/kg were injected intraperitoneally,and 5 min later formalin was injected.In P1,2 groups,propofol 30 and 100 mg/kg were intraperitoneally injected,respectively,and 5 min later formalin was injected.The pain behavior of rats was observed within 1 h after injection of formalin and pain intensity scoring (PIS) value was calculated.The animals were sacrificed at 1 h after injection of formalin and the hippocampi were isolated for determination of GABAA and NMDA receptor expression by immunohistochemisty.Results Compared with group C,PIS value was significantly increased,GABAA and NMDA receptor expression was up-regulated in IP and P1.2 groups.Compared with group IP,PIS value was significantly decreased,GABAA receptor expression was up-regulated,and NMDA receptor expression was down-regulated in P1,2 groups.PIS value was significantly lower,GABAA receptor expression was higher,and NMDA receptor expression was lower in group P2 than in group P1.Conclusion Intraperitoneal propofol can down-regulate NMDA receptor expression in hippocampi of rats with IP,thus inhibiting responses to pain sensitivity; intraperitoneal propofol can up-regulate hippocampal GABAA receptor expression,thus enhancing endogenous mechanism of analgesia.

Decreased expression of γ-aminobutyric acid receptor in the hippocampal tissues of pharmacoresistant temporal lobe epileptic rats / 中华神经科杂志

Objective To establish a multi-drug resistant model of temporal lobe epilepsy,and to observe the changes of γ-aminobutyric acid (GABA) receptor expression in the hippocampal tissues so as to explore its effects in pharmacoresistant epileptogenesis.Methods One hundred rats were selected to prepare the amygdaloid kindled model of epilepsy by chronic stimulation of amygaloid basal lateral nucleus.After the kindled model of epilepsy was prepared successfully(n =52),pharmacoresistant epileptic rats were selected according to their response to the phenobabital and phenytoin.The selected pharmacoresistant epileptic rats (n =8)were sacrificed and the hippocampus was removed to determine the GABA receptor expression,and the same number of pharmacosensitive epileptic rats was used as control.Results The pharmacoresistant epileptic rats displayed degenerative and necrotic hippocampal neurons.The arrangement of hippocampal neurons was disordered,and the structural characteristics of the arrangement of the hippocampal neurons disappeared.The gray values of GABAA-positive neurons in the hippocampal tissues (141.15 ± 14.72) increased significantly compared with the pharmacosensitive epileptic rats (92.56 ± 5.17; t =3.380,P =0.006).Western blot method demonstrated that the band of GABAA became narrowed and thin.The relative quantity of GABAA in the hippocampal tissues (0.38 ± 0.08) decreased significantly as compared with the pharmacosensitive epileptic rats (0.88 ± 0.18).A significant difference was observed (t =5.420,P =0.002).Conclusions GABA receptor expression might be decreased in the hippocampal tissues of pharmacoresistant epileptic rats.It might play a certain role in the formation of pharnmacoresistant epilepsy.

Effect of noxious stimulation factor on γ-aminobutyric acid distribution in dog spinal cord during propofol anesthesia / 中华麻醉学杂志

Objective To evaluate the effect of the noxious stimulation factor on γ-aminobutyric acid (GABA) distribution in dog spinal cord during propofol anesthesia.Methods Sixteen healthy mongrel dogs of both sexes,aged 12-18 months,weighing 10-12 kg,were randomly divided into 2 groups (n =8 each):noxious stimulation group (S group) and control group (C group).Anesthesia was induced with propofol 7 mg/kg.The animals were mechanically ventilated after tracheal intubation.Right femoral artery was cannulated for mean arterial pressure (MAP) and pulse rate monitoring.Anesthesia was maintained with propofol infusion at a constant rate of 70 mg· kg-1 · h-1.5 ％ formalin 300 μl was subcutaneously injected into the central region of tails in group S,while the equal volume of normal saline was injected instead of formalin in group C.MAP and pulse rate were recorded before injection of formalin or normal saline (T1) and after injection of formalin or normal saline (T2).The dogs were scarified by decapitation at 50 min of continuous propofol infusion and cervical 2-3 segments of the spinal cord were removed for determination of GABA level in different regions of the spinal cord (frontal horn,posterior horn,intermediate zone,frontal funiculus,posterior funiculus and lateral funiculus) by HPLC.Results MAP and pulse rate were significantly higher at T2 than at T1 in S group (P ＜ 0.05).There were no significant differences in GABA level among the different regions of the spinal cord in C group (P ＞ 0.05).Compared with C group,GABA level in the frontal horn and posterior horn was significantly increased (P ＜ 0.05),and no significant change was found in the other regions of the spinal cord in S group (P ＞ 0.05).Conclusion The noxious stimulation factor can induce an increase in GABA level in the frontal horn and posterior horn of dog spinal cord during propofol anesthesia.

Effects of midazolam on GABAA receptor-activated currents in isolated dorsal root ganglion neurons in rats / 中华麻醉学杂志

Objective To investigate the effects of midazolam on GABAA receptor-activated currents in isolated dorsal root ganglion (DRG) neurons in rats.Methods Sprague-Dawley rats of both sexes,weighing 200-250 g,aged 4 weeks,were used in the study.The DRG neurons were isolated and GABAA receptor-activated currents were recorded using the whole-cell patch-clamp technique.GABAA receptor-activated currents were recorded after administration of the mixture of midazolam 3.00 μmol/L (final concentration)and the different final concentrations (0.03,0.10,1.00,10.00,100.00 and 1000.00 μmol/L) of GABA,after different concentrations of midazolam (0.03,0.10,1.00,3.00,10.00 and 100.00 μmol/L) was given,after administration of the mixture of different final concentrations(0.03,0.10,1.00,3.00,10.00 and 100.00 μmol/L) of midazolam and GABA 100.00 μmol/L (final concentration),and after administration of the mixture of midazolam 1.00μmol/L (final concentration) and GABA 100.00 μmol/L (final concentration)at the preset time points of perfusion with different concentrations of midazolam (0,20,40,60 and 120 s of perfusion).The enhancement rate of the currents was calculated.Results No change in the membrane currents was found after midazolam was perfused in the neurons sensitive to GABA.GABAA receptor-activated currents were enhanced after administration of the mixture of different concentrations of GABA and midazolam.GABAA receptor-activated currents were enhanced after different concentrations of midazolam were given compared with that before administration,and the enhancement rate of the GABAA receptoractivated currents was gradually increased with the increase in the concentration of midazolam and reached the peak at the concentration of 3.00 μmol/L.The enhancement rate of the GABAA receptor-activated currents was gradually increased with the prolongation of perfusion time and peaked at 40 s of perfusion.Conclusion Midazolam can enhance the GABAA receptor-activated currents in rat dorsal root ganglion neurons,indicating that midazolam increases the role of GABA through increasing the activity of GABAA receptors and has analgesic effect at the spinal cord level.

Role of gamma-aminobutyric acid A receptor in isoflurane-induced cognitive dysfunction in neonatal rats / 中华麻醉学杂志

Objective To evaluate the role of gamma-aminobutyric acid A (GABAA) receptor in isoflurane-induced cognitive dysfunction in neonatal rats.Methods Twenty-eight 7-day-old Sprague Dawley rats,weighing 16-18 g,were randomly divided into 4 groups (n =7 each):control group (group Con),securinine group (group See),isoflurane group (group Iso) and securinine + isoflurane group (group Sec + Iso).Normal saline 0.2 ml was injected intraperitoneally in group Con.Specific GABAA receptor antagonist securinine 30 mg/kg was injected intraperitoneally at the corresponding time points in group Sec.Normal saline 0.2 ml was injected intraperitoneally and 1.4％ isoflurane was inhaled for 6 h in group Iso.Securinine 30 mg/kg was injected intraperitoneally at 30 min before isoflurane inhalation and 3 h of inhalation,and 1.4％ isoflurane was inhaled for 6 h in group Sec + Iso.The rats were then sacrificed at 3 weeks after administration,their brains were immediately removed and hippocampal slices were prepared for electrophysiological experiments.The value of population spike amplitude (PSA) and long-term potentiation (LTP) were measured every 5 min.The successful LTP induction was recorded.Results Compared with group Con,the values of PSA and rates of successful LTP induction were significantly decreased in group Iso (P ＜ 0.01),and no significant change was found in the parameters mentioned above in groups Sec and Sec + Iso (P ＞ 0.05).The values of PSA and rates of successful LTP induction were significantly higher in group Sec + Iso than in group Iso (P ＜ 0.01).Conclusion GABAA receptor is involved in isoflurane-induced cognitive dysfunction in the neonatal rats.

Role of gamma-aminobutyric acid A receptor in lung tissues in lipopolysaccharide-induced acute lung injury in rats / 中华麻醉学杂志

Objective To investigate the role of gamma-aminobutyric acid (GABA) A receptor (GABAAR) in lung tissues in lipopolysaccharide (LPS)-induced acute lung injury in rats.Methods Thirty-two male Wistar rats,aged 8 weeks,weighing 200-230 g,were randomly divided into 4 groups (n =8 each) ∶ control group (group C),group LPS,GABA pretreatment + LPS group (group GABA) and GABAAR antagonist bicuculline pretreatment + LPS group (group BIC).Acute lung injury was induced by intravenous LPS 5 mg/kg in groups LPS,GABA and BIC,while the equal volume of normal saline was given in group C.GABA 50 mg/kg and bicuculline 10 μmol/kg were injected intraperitoneally 30 min before LPS injection in GABA and BIC groups,respectively.Arterial blood samples were collected at 6 h after LPS injection for measurement of arterial partial pressure of oxygen (PaO2).The animals were then sacrificed and lungs removed for determination of W/D lung weight ratio,GABAAR expression,contents of interleukin-6 (IL-6),tumor necrosis factor-α (TNF-α) and malondialdehyde (MDA) and superoxide dismutase (SOD) activity in lung tissues and for microscopic examination.Results Compared with group C,PaO2 was significantly decreased in the other three groups,and W/D lung weight ratio,TNF-α,IL-6 and MDA contents were significantly increased,GABAAR expression was up-regulated,and SOD activity was decreased in groups LPS and GABA (P ＜ 0.05).Compared with group LPS,W/D lung weight ratio,TNF-α,IL-6 and MDA contents were significantly increased,GABAAR expression was up-regulated,and SOD activity was decreased in group GABA (P ＜ 0.05),and no significant change was found in the parameters mentioned above in group BIC and in PaO2 in groups GABA and BIC (P ＞ 0.05).Conclusion GABAA R in lung tissues is involved in the development of acute lung injury induced by LPS.

Role of spinal cord GABAA receptors in the analgesic effect of propofol on visceral pain in rats / 中华麻醉学杂志

Objective To evaluate the role of spinal cord CABAA receptors in the analgesic effect of propofol on visceral pain in rats. Methods Adult female SD rats, weighing 190-240 g, were used in this study.The animals were anesthetized with intraperitoneal ketamine 50-100 mg/kg. Intrathecal (IT) catheters were placed at L5-6 interspace according to the technique described by Storkson et al. Thirty-two animals in which IT catheters were successfully placed were randomly divided into 4 groups ( n = 8 each) : dimethyl sulphoxide (DMSO) group (group D), propofol group (group P), bicuculline group (group B) and bicuculline + propofol group (group B +P). Visceral pain was induced by injecting 10% formalin 100 μl underneath the mucous membrane of rectum.Groups D, P and B received IT DMSO 5 μl, propofol 10 μg and bicuculline 2 μg respectively. Group BP received IT bicuculline 2 μg and then IT propofol 10 μg 10 min later. The L5-S1 segment of the spinal cord was removed 2 h after formalin injection to determine FOS protein expression by hnmuno-histochemistry. Results Compared with groups D and B, FOS protein expression was significantly down-regulated in group P ( P ＜ 0.05 ) . There was no significant difference in FOS protein expression between groups D and B ( P ＞ 0.05) . FOS protein expression was significantly up-regulated in group BP compared with group P ( P ＜ 0.05) . Conclusion Propofol has analgesic effect on visceral pain in rats through spinal cord GABAA receptor action.

Role of GABAA receptors in uninjured dorsal root ganglion in a rat model of neuropathic pain / 中华麻醉学杂志

Objective To evaluate the role of GABAA receptors in uninjured dorsal root ganglion(L4DRG)in a rat model of neuropathic pain.Methods Thirty adult female SD rats weighing 200-250 g were randomly divided into 3 groups(n = 10 each): control group(group C),muscimol group(group M)and bicuculline group(group B).Neuropathic pain was produced by L5 spinal nerve ligation.Normal saline 50 μl,GABAA receptor agonist-muscimol 50 μl or GABAA receptor antagonist- bicucullin 50 μl was injected into the L4 DRG.The thermal pain threshold and mechanical pain threshold were measured and recorded from 1 day before operation to 10 days after operation.Results Compared with group C,the mechanical pain threshold was significantly increased(P ＜ 0.05),while no significant difference was found in thermal pain threshold in group M(P ＞ 0.05),and the thermal pain threshold and mechanical pain threshold were significantly decreased in group B(P ＜ 0.05).Conclusion Activation of GABAA receptors in uninjured DRG is involved in mechanical hyperalgesia in a rat model of neuropathic pain,but it dose not play a leading role.