Potential material basis of Kangbingdu Granules for treatment of coronavirus disease 2019 (COVID-19) based on network pharmacology and molecular docking technology / 中草药

Objective: To explore the potential material basis of Kangbingdu Granules for the treatment of coronavirus disease 2019 (COVID-19) through network pharmacology and molecular docking technology. Methods: The chemical constituents and action targets of Isatidis Radix, Forsythiae Fructus, Gypsum Fibrosum, Anemarrhenae Rhizoma, Phragmitis Rhizoma, Rehmanniae Radix Praeparata, Pogostemon cablin, Acoritataninowii Rhizoma and Curcumae Radix in Kangbingdu Granules were searched by TCMSP. The gene corresponding to the target was searched by UniProt database, and Cytoscape 3.6.1 was used to build a medicinal material-compound-target (gene) network. DAVID was used to perform gene ontology (GO) function enrichment analysis and KEGG pathway enrichment analysis to predict its mechanism. Molecular docking of the top 15 components was carried out in the medicinal material-compound-target network with SARS-CoV-2 3CL hydrolase, and molecular docking with bicuculline, luteolin, quercetin and angiotensin-converting enzyme II (ACE2) was performed. Results: The medicinal material-compound-target (gene) network contained eight medicinal materials, 75 compounds and 255 targets. GO function enrichment analysis revealed 161 GO items (P < 0.05), including 65 biological process (BP) items, 36 cell composition (CC) items, and 60 molecular function (MF) items. KEGG pathway enrichment screened 131 signaling pathways (P < 0.05). The results of molecular docking showed that the core active compounds such as bicuculline, luteolin, and quercetin in the Kangbingdu Granules had similar affinities with those recommended by COVID-19. Conclusion: The active compounds in Kangbingdu Granules can interact with angiotensin-converting enzyme II (ACE2) via targets PTGS2, HSP90AB1, and PTGS1 to regulate multiple signaling pathways, thereby exerting therapeutic effects on COVID-19.

Investigation on mechanism and active components of Shufeng Jiedu Capsule in treatment of COVID-19 based on network pharmacology and molecular docking / 中草药

Objective: To explore the novel coronavirus disease 2019 (COVID-19) treatment mechanism and active ingredients of Shufeng Jiedu Capsule by network pharmacology and molecular docking. Methods: TCMSP databases were used to search the chemical composition and target of Shufeng Jiedu Capsule, which was composed of Isatidis Radix, Polygonum cuspidatum, Forsythia suspensa, Phragmitis Rhizoma, Patrinia, Verbena officinalis, Bupleurum chinense, and Glycyrrhiza uralensis. The Swiss target prediction database was used to remove the target with possibility of 0. The corresponding targets of the disease were searched in the GeneCards and OMIM databases with the key words of "coronavirus", "pneumonia", "cough", and "fever". Through the UniProt databases to correct the name of the target point, take the intersection of Shufeng Jiedu Capsule and the disease target point, then use the software of Cytoscape 3.7.2 to build the network of traditional Chinese medicine-compound-target for visualization, through DAVID databases to carry out the GO function enrichment analysis and KEGG pathway enrichment analysis, predict the interaction mechanism of the target, and draw the column and bubble chart for visualization. The novel coronavirus (SARS-CoV-2) 3CL hydrolase was then docking with all compounds and the first five compounds with the least binding energy were selected for docking with angiotensin-converting enzyme II (ACE2). Results: The traditional Chinese medicine-compound-target compound target network contains eight kinds of traditional Chinese medicine-compound-target, 157 compounds and 260 corresponding targets. The key targets were PTGS2, ESR1, AR, etc. There were 393 items in GO functional enrichment analysis (P < 0.05), and 139 signaling pathways in KEGG pathway enrichment analysis. Molecular docking results showed that SARS-CoV-2 3CL hydrolase and ACE2 binding energy of the five core compounds, including 6-(3-oxoindolin-2-ylidene) indolo [2,1-b] quinazolin-12-one, bicuculline, physciondiglucoside, dihydroverticillatine, and licoisoflavanone, was smaller than that of recommended chemical drugs, and the binding energy to ACE2 was similar to that of the recommended chemical drug. Conclusion: The compounds in Shufeng Jiedu Capsule can regulate the signaling pathway of human cytomegalovirus infection, Kaposi's sarcoma associated herpesvirus infection, IL-17 signaling pathway, small cell lung cancer, etc. to treat COVID-19 by binding with SARS-CoV-2 3CL hydrolase and ACE2.

HPLC fingerprint and multicomponents determination of Corydalis Decumbentis Rhizoma / 中草药

Objective: To establish the HPLC fingerprint and multicomponents determination of Corydalis Decumbentis Rhizoma, and provide a scientific basis for the improvement of its quality standards. Methods The separation was performed on a chromatographic Diamonsil C18 column (250 mm × 4.6 mm, 5 μm), with acetonitrile-0.2% acetic acid (adjusting pH to 6.0 with triethylamine) as the mobile phase for gradient elution. Volume flow rate was 1.0 mL/min. Column temperature was 35 ℃. Injection was 10 μL and the detection wavelength was 280 nm. The fingerprints of 15 batches of Corydalis Decumbentis Rhizoma were established and evaluated by the similarity evaluation system of TCM (version 2012A), which were divided into two categories by clustering analysis and principal component analysis. Meanwhile, the content of protopine, palmatine, bicuculline and tetrahydropalmatine was determinated. Results:The fingerprint of Corydalis Decumbentis Rhizoma was established. There were 10 common peaks in the fingerprint. Protopine, palmatine, bicuculline and dl-tetrahydropalmatine were separated with good linearity relationships (r > 0.999 9). The average recovery rates of the investigated compounds were 97.12%, 100.09%, 98.53%, and 99.71%, respectively. Conclusion:HPLC fingerprint combined with multicomponents determination can provide the reference for the quality evaluation of Corydalis Decumbentis Rhizoma.

GABA Receptor Activity Suppresses the Transition from Inter-ictal to Ictal Epileptiform Discharges in Juvenile Mouse Hippocampus / 神经科学通报·英文版

Exploring the transition from inter-ictal to ictal epileptiform discharges (IDs) and how GABA receptor-mediated action affects the onset of IDs will enrich our understanding of epileptogenesis and epilepsy treatment. We used Mg-free artificial cerebrospinal fluid (ACSF) to induce epileptiform discharges in juvenile mouse hippocampal slices and used a micro-electrode array to record the discharges. After the slices were exposed to Mg-free ACSF for 10 min-20 min, synchronous recurrent seizure-like events were recorded across the slices, and each event evolved from inter-ictal epileptiform discharges (IIDs) to pre-ictal epileptiform discharges (PIDs), and then to IDs. During the transition from IIDs to PIDs, the duration of discharges increased and the inter-discharge interval decreased. After adding 3 μmol/L of the GABA receptor agonist muscimol, PIDs and IDs disappeared, and IIDs remained. Further, the application of 10 μmol/L muscimol abolished all the epileptiform discharges. When the GABA receptor antagonist bicuculline was applied at 10 μmol/L, IIDs and PIDs disappeared, and IDs remained at decreased intervals. These results indicated that there are dynamic changes in the hippocampal network preceding the onset of IDs, and GABA receptor activity suppresses the transition from IIDs to IDs in juvenile mouse hippocampus.

Neuroprotective effect of propofol on fetal ratbrain in intrauterine ischemia/reperfusion injury / 中国药理学通报

Aim To observe the neuroprotective effect of different doses of propofol on ischemic fetal rat brain.Methods Eighteen healthy pregnant SD rats were randomly allocated into the following six groups with three rats in each.Group S: sham operation group, Group IR: ischemia/reperfusion group, Group P1~P3: different doses of propofol groups, Group B: bicuculline group.In group S and group IR, 1 ml saline solution was administered via caudal vein.In group P1~P3, 10, 30, 50 mg·kg-1 of propofol was administered via caudal vein respectively.In group B, when 50 mg·kg-1 propfol was administered via caudal vein, 5 mg·kg-1 bicuculline was injected intraperitoneally at the same time.Bilateral uterine ovarian arteries were clamped for 11 mins to make intrauterine distress model of the fetal rats.The brains of fetal rats were removed after 3 days of reperfusion.Brain sections(5 μm thick) were mounted and stained with Hematoxylin and eosin(HE).The profile of the hippocampus CA1 was evaluated under a light microscope and neuronal Lesion-index(LI) was calculated.MDA content of fetal rat brain was detected by thiobarbituric acid reaction method to determine the lipid peroxidation degree of brain.Results LI was (7.2±0.9) and MDA was (3.86±0.20) μmol·g-1 in group S.LI was 71.9±2.8 and the content of MDA was (9.10±0.45) μmol·g-1 in group IR, which increased significantly compared with those in group S(P<0.01).LI was (40.8±2.6), (21.4±1.4), (20.1±1.3) and the content of MDA was (7.32±0.41), (5.65±0.27), (5.44±0.28) μmol·g-1 in propofol groups, which decreased significantly compared with those in group IR(P<0.05).LI and the content of MDA was (51.2±2.3), (7.54±0.31) μmol·g-1 in group B,respectively, reversing partly the neuroprotevtive effect of propofl.Conclusion Propofol could protect the neurons in hippocampus CA1 region of fetal rat against intrauterine distress by reducing the concentration of MDA in the brain.

Anticonvulsant mechanism of saponins fraction from adventitious roots of Ficus religiosa: possible modulation of GABAergic, calcium and sodium channel functions

ABSTRACT In our previous studies, quantified saponins-rich fraction from adventitious root extract of Ficus religiosa L., Moraceae, showed anticonvulsant effect in acute, as well as chronic mice models of epilepsy. The present study was designed to reveal putative anticonvulsant mechanism of quantified saponins-rich fraction using target specific animal models. The anticonvulsant effect of quantified saponins-rich fraction was initially studied in maximal electroshock and pentylenetetrazol test at 1, 2 and 4 mg/kg; i.p. doses. Based on the results of initial anticonvulsant testing, different groups of mice were injected with vehicle or quantified saponins-rich fraction (4 mg/kg; i.p.), 30 min prior to an injection of N-methyl-D-aspartic acid (100 mg/kg; s.c.), bicuculline (5 mg/kg; i.p.), strychnine hydrochloride (2 mg/kg; i.p.), BAY k-8644 (37.5 µg; i.c.v.), veratridine (500 µg/kg; i.p.) and the convulsive episodes were studied. Treatment with the extract (1, 2 and 4 mg/kg) showed significant protection in maximal electroshock and pentylenetetrazol-induced convulsion tests, in a dose-dependent manner. Moreover, quantified saponins-rich fraction at 4 mg/kg dose showed significant increase in latency to clonic convulsions, decrease in seizure severity and increase in average wave amplitude in bicuculline, BAY k-8644 and veratridine tests, respectively, as compared to vehicle control. However, SRF treatment failed to abolish N-methyl-D-aspartic acid and strychnine-induced convulsions, indicated by insignificant change in the appearance of turning behavior and onset of tonic extension, respectively, as compared to vehicle control. From the results of present study, it is concluded that quantified saponins-rich fraction suppress maximal electroshock, pentylenetetrazol, bicuculline, BAY k-8644 and veratridine-induced convulsions, indicating its GABAergic, Na+ and Ca2+ channel modulatory effects. Further it can be correlated that quantified saponins-rich fraction causes deactivation of voltage-gated Na+ and Ca2+ channels, without effecting ligand-gated Na+ and Ca2+ channels. More studies are required at molecular levels using in vitro techniques to understand the exact molecular interactions of quantified saponins-rich fraction with these pathways.

Study on removing (-)-bicuculline from Corydalis Decumbentis Rhizoma total alkaloids by fast centrifugal partition chromatography / 中草药

Objective: Using fast centrifugal partition chromatography (FCPC) to remove (-)-bicuculline from Corydalis Decumbentis Rhizoma total alkaloids. Methods: The technological parameters of orthogonal experiment of FCPC was optimized by flow rate, rotation speed, and loading sample size. The optimized process was compared with the solvent extraction method, and the linear amplification experiments were carried out using the optimal process. Results: The optimized parameters were as follows: rotation speed was 1200 r/min, flow rate was 4 mL/min, and loading sample size was 80 mg/mL. The new prepared alkaloids fraction of Corydalis Decumbentis Rhizoma using amplification experiments has > 94.0% removed rate of BI and >85.0% recovery of the other alkaloids, which were higher than those of the solvent extraction method. This simple method with good repeatability could be completed in a short time. Conclusion: The simple and fast method could improve the safety of Corydalis Decumbens Rhizoma total alkaloids, and provide the industrialization of non-toxic total alkaloids.

Antiepileptogenic and Anticonvulsant Actions of Dalbergia saxatilis (Hook, F.) in Sub-toxic Chemical Kindling and Toxic Convulsant Models.

Aims: The aqueous root extract of Dalbergia saxatilis (DS) is used in traditional African medicine to manage convulsions and epilepsies. This study aimed at investigating DS action against models that mimic seizure development in the neurons of epileptics, the sub-toxic dose kindling models. Study Design: Sub-toxic doses of strychnine and picrotoxin chemical kindling models; as well as single-dose toxic bicuculline convulsive models in mice. Place and Duration of Study: Neuropharmacology Unit Laboratory, Department of Pharmacology, College of Medicine, University of Lagos, Lagos, Nigeria, between July 2006 and March 2008. Methodology: Strychnine kindling was produced by a 48h interval, i.m administration of 1.5mg/kg strychnine for 9 trials. The mice were treated with 200mg/kg, p.o. DS, before strychnine thus: Group I: throughout the 1st - 9th kindling; group II: During the 1st - 5th kindling; and group III: during the 6th - 9th kindling trials. Control group received distilled water instead of DS throughout the 1st - 9th kindling trials. For picrotoxin study, a subconvulsant dose of 1.5mg/kg picrotoxin was injected i.p. 3 times a week for 10 weeks, 200mg/kg of DS was administered orally before picrotoxin thus: Group I: throughout the 1st - 30th kindling trials; group II: during the 1st - 12th kindling trials; group III: during the 13th - 30th kindling trials; control group received distilled water instead of DS throughout the 30 trials. Behavioural seizures were classified for seizure stages. In another study, DS (50- 200 mg/kg, p.o.) was administered to mice, 30 min. before 10mg/kg, s.c. bicuculline and onset to seizures and time to death noted. Results: DS significantly (P=.05) retarded the development and progression of strychnine kindling, but did not reverse already reached kindled state. Moreover, DS significantly (P=.05) retarded the development of picrotoxin kindling, decreased the scoring from kindling progression and prevented convulsion in fully picrotoxin-kindled mice. A significant delay of seizure onset, with complete protection at 200mg/kg DS was produced against bicuculline seizures in mice. Conclusion: DS may attenuate development of seizures in both GABAergic and glycinergic mechanisms and be useful in the prevention of seizures as well as neuroprotection in epileptics, justifying its use in the folkloric management of epilepsies.

Effect of intrathecal glycine and related amino acids on the allodynia and hyperalgesic action of strychnine or bicuculline in mice / 대한마취과학회지

BACKGROUND: The intrathecal (IT) administration of glycine or GABAA receptor antagonist result in a touch evoked allodynia through disinhibition in the spinal cord. Glycine is an inhibitory neurotransmitter that appears to be important in sensory processing in the spinal cord. This study was aimed to evaluate the effect of glycine-related amino acids on antagonizing the effects of IT strychnine (STR) or bicuculline (BIC) when each amino acid was administered in combination with STR or BIC. METHODS: A total of 174 male ICR mice were randomized to receive an IT injection of equimolar dose of glycine, betaine, beta-alanine, or taurine in combination with STR or BIC. Agitation in response to innocuous stimulation with a von Frey filament after IT injection was assessed. The pain index in hot-plate test were observed after it injection. The effect of it muscimol in combination with str or bic were also observed. RESULTS: The allodynia induced by STR was relieved by high dose of glycine or betaine. But, allodynia induced by BIC was not relieved by any amino acid. Whereas the STR-induced thermal hyperalgesia was only relieved by high dose of taurine at 120 min after IT injection, the BIC-induced one was relieved by not only high dose of taurine at 120 min but also low dose of glycine or betaine at 60 min after IT injection. The BIC-induced allodynia and thermal hyperalgesia was relieved by IT muscimol. CONCLUSIONS: This study suggests that IT glycine and related amino acids can reduce the allodynic and hyperalgesic action of STR or BIC in mice.

Establishment and comparison of DHPG and BMI induced epileptic discharge models / 上海第二医科大学学报

Objective To develop models of epileptic discharge by activating group Ⅰ metabotropic glutamate receptors (mGluR) or by blocking gamma-aminobutyric acid (GABA) receptors on rat hippocampal slices. Methods Rat hippocampal slices were exposed to mGluR group Ⅰ specific agonist dihydroxyphenylglycine (DHPG) or to GABAA receptor antagonists bicuculline methiodide(BMI), and single pyramidal cell in the CA3 region of the slice was recorded by whole cell patch clamp technique. Results Exposure to DHPG or BMI resulted in the induction of spontaneously occurring epileptic discharge in the CA3 region of rat hippocampal slice, and there was no significant difference in the frequency of discharge between them(P>0.05). Conclusion Epileptic discharge can be generated in vitro in response to a loss of balance between excitatory and inhibitory influences.

EFFECTS OF UROTENSIN II ON ELECTRICAL ACTIVITY OF PARAVENTRICULAR NEURONS IN RAT HYPOTHALAMIC SLICES / 神经解剖学杂志

Effects of urotensin II (UII) on paraventricular nucleus (PVN) neurons of hypothalamus from brain slices of rats were examined by using extracellular recording technique. The results are as follows: (1) In response to application of UII (0.3, 3.0, 30.0, 300.0 nmol/L, n=39) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 32/39 (82.05% ) neurons were significantly decreased in a dose-dependent manner; (2) Pretreatment with bicuculline (BIC, 100 μmol/L), a specific GABAA receptor antagonist, led to a marked increase in SDR of 5/7 ( 71.43% ) neurons in an epileptiform pattern. The increased discharges were not significantly changed after UII ( 30.0 nmol/L ) was applied into the perfusate for 2 min; (3) Pretreatment with picrotoxin ( PIC, 50 μmol/L ), a selective blocker of Cl- channel, led to an increase in the SDR of all 12/12 (100%) neurons. The increased discharges were not influenced by the applied UII (30.0 nmol/L) for 2 min in 11/12 (91.67%) neurons; (4) Application of nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 50 μmol/L ) into the perfusate could significantly augment the SDR of 11/12 ( 91.67% ) neurons , while UII ( 30.0 nmol/L ) applied into the perfusate for 2 min led the augmented SDR of all (12/12, 100%) neurons decrease. The results suggest that UII decreases the excitability of PVN neurons of hypothalamus by potentiating GABAA receptor-mediated Cl- current.

Effect of Potassium, Bicuculline and CNQX on Epileptiform Activity Induced by Pilocarpine in the Rat Visual Cortex Slice

BACKGROUND: The purpose of this study was to investigate the effect of potassium, bicuculline (BIC) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) on epileptiform activity induced by pilocarpine in the rat visual cortex slices. METHODS: In the rat visual cortex slices, we observed the change of pilocarpine-induced epileptiform discharges using extracellular recordings during perfusion of artificial cerebro-spinal fluid (ACSF) with various potassium concentrations ([K+], 2.5, 5, 7.5 and 10 mM) and ACSF with 10 micrometer BIC and 20 micrometer CNQX under 7.5 mM [K+]. RESULTS: Spontaneous interictal epileptiform activity induced by pilocarpine was observed in 5 mM or higher [K+] and ictal discharge was only detected in 7.5 mM [K+]. Increase of [K+] from 2.5 to 7.5 mM not only resulted in the increase of frequency and amplitude of epileptiform activity but also favored the transformation of pilocarpine-induced interictal activity into ictal activity in the rat visual cortex. However, in 10 mM [K+], the ictal discharge was unprovoked and interictal activity was provoked with decreased frequency and amplitude. The spontaneous ictal discharge was blocked but interictal activity was maintained with increased frequency and amplitude by BIC. Interictal and ictal activities were completely blocked by CNQX. CONCLUSIONS: These results suggested that the extracellular potassium concentration, GABA system, and non-NMDA mechanism seemed to be involved in the development and maintenance of pilocarpine-induced epileptiform activity in the rat visual cortex.

Bicuculline Induced Epileptiform Activity

PURPOSE: The goal of this study was to investigate the effects of bicuculline(BIC) on the excitability of visual cortex, observe the induction of epileptiform activity and define the characteristics of spontaneous activity. METHODS: We divided 19 to 23-day-old Sprague-Dawley rats into 3 groups by the concentration of BIC:5(n=10), 20(n=12), and 40(n=10) microM. The slices from the rats were incubated in artificial CSF for 1 hour, and then extracellular recordings were performed. RESULTS: Spontaneous epileptiform activities were observed in all of the BIC groups. The latencies of 5, 20, and 40 microM BIC were 31.6+/-13.0, 34.0+/-11.9, and 6.3+/-3.2 min. The frequencies of 5, 20, and 40 microM BIC were 1.1+/-0.5, 2.7+/-1.8, and 19.1+/-23.3 min-1. The amplitudes of 5, 20, and 40 microM BIC were 5.4+/-1.4, 6.9+/-0.9, 11.1+/-1.3 mV. The durations of 5, 20, and 40 microM BIC were 444.6+/-169.1, 865.2+/-151.2, and 1,014.7+/-613.8 ms. CONCLUSION: BIC is associated with increased excitability in the visual cortex and induces spontaneous epileptiform activities. This induction was decreased by D-AP5 or CNQX.

Interhemispheric Modulation on Afferent Sensory Transmission to the Ventral Posterior Medial Thalamus by Contralateral Primary Somatosensory Cortex

Single unit responses of the ventral posterior medial (VPM) thalamic neurons to stimulation were monitored in anesthetized rats during activation of contralateral primary somatosensory (SI) cortex by GABA antagonist. The temporal changes of afferent sensory transmission were quantitatively analyzed by poststimulus time histogram (PSTH). Mainly, afferent sensory transmission to VPM thalamus was facilitated (15 neurons of total 23) by GABA antagonist (bicuculline) applied to contralateral cortex, while 7 neurons were suppressed. However, when ipsilateral cortex was inactivated by GABA agonist, musimol, there was significant suppression of afferent sensory transmission of VPM thalamus. This suppressed responsiveness by ipsilateral musimol was not affected by bicuculline applied to contralateral cortex. These results suggest that afferent transmission to VPM thalamus may be subjected to the interhemispheric modulation via ipsilateral cortex during inactivation of GABAergic neurons in contralateral SI cortex.

Effects of intracerebroventricular injection of bicuculline or NMDA on the amnestic effect induced by etomidate / 中国药理学通报

Aim To investigate the relationship between GABAA receptor or NMDA receptor and the amnestic effect induced by etomidate.Methods Amnestic model was established by intraperitoneal injection of etomidate(3 mg?kg-1) in mice before intracerebroventricular injection of different doses of bicuculline or NMDA,then the error times,step down latency and step through latency were observed and recorded in the step down test and step through test.Results Bicuculline(2,4 ?g) instead of NMDA by intracerebroventricular injection could decrease the error times and increase the step down latency and step through latency of amnestic mice in the step down test and step through test.Conclusion GABAA receptor rather than NMDA receptor may be an important target for the amnestic effect induced by etomidate.

Partial mediation of GABA_A receptor in the antinociceptive stimulation of propofol at spinal level in rats / 中国药理学通报

Aim To observe the effects of propofol at spinal level on nociceptive response in rats and the possible role of GABA_A receptor.Methods In the praxiology test,Sprague-Dawley(SD) female rats were randomized into groups.Bicuculline and propofol were microinjected into intrathecally(ith).The noxious response was evaluated with hot plate and formalin test.In immunohistochemistry test,Fos-like immunoreactivity(FLI) neurons expressed in spinal dorsal horn(DH) induced by formalin intraplantar injection(sc) of one hindpaw were used as a neuroactive marker to observe the effects of propofol on the noxious transmission in DH.Results In hot-plate test,significant analgesia produced by propofol(10 g?L~(-1)) was antagonized about 81%,55%,81% and 97% at 10,20,30 and 40 min by ith bicuculline(0.01 g?L~(-1),P

The Effects of GABA-receptor Antagonists on the Spinal Cord Stimulation-induced Antinociception in Cats / 대한마취과학회지

BACKGROUND: Spinal cord stimulation (SCS) is a clinical off spring of the gate-control theory and known as an effective treatment for pain from a neurogenic origin. The prolonged pain relief following a short stimulation period is believed to be related with the GABAergic system. The aims of this study were to see if the SCS, similar to that being used in clinical condition, suppressed the nociceptive transmission in the spinal dorsal horn, and if so, which type of GABA receptor may be involved in the antinociceptive process. METHODS: The cord dorsum potential (CDP) was recorded at the dorsal root entry zone of the lumbosacral enlargement for a long time period (60 min) in response to electrical stimulation of the dorsal root, respectively, after SCS in anesthetized cats. CDP was recorded after intrathecal application of bicuculline (GABA (A) receptor antagonist) and phaclofen (GABA (B) receptor antagonist) and 20 min after SCS that followed the intrathecal application of bicuculline or phaclofen. Asigma- and C-fiber wave responses were differentiated according to the conduction velocity. RESULTS: The C-fiber wave decreased significantly after SCS but the Asigma-fiber wave did not on the CDP. After intrathecal administration of bicuculline, the Asigma- and C-fiber waves increased significantly and bicuculline also prevented a SCS-induced reduction of the C-fiber wave. Phaclofen did not change the amplitude of Asigma- and C-fiber wave. When the phaclofen was administered intrathecally, SCS did not decrease the amplitude of the Asigma- and C-fiber waves. CONCLUSIONS: In conclusion, the present results indicate that SCS suppresses C-fiber transmission of acute nociceptive electrical stimuli and both GABA (A) and (B) receptors mediate the long-lasting antinociceptive effect of SCS.

A Study on the Neurotransmitters Acting on the Medullospinal Tract Cells Related to the Cardiovascular Activity / 대한흉부외과학회지

The medullospinal tract cells are known to play an important role in the control of the cardiovascular activities. To clarify the modes of action of the neurotransmitters on these cells, glutamate, GABA (gamma-aminobutyric acid) and bicuculline were applicated iontophoretically into the rostral ventrolateral medulla in adult cats anesthetised with alpha-chloralose. Followings are the results obtained : 1. The spontaneous activities of the cardiac-related neurons in rostral ventrolateral medulla (RVLM) were increased by the glutamate and decreased by the GABA. 2. Bicuculline, an antagonist of GABA, alone didn't increase the frequency of the action potentials, but could reverse the cellular response to the GABA, simultaneously applicated. 3. GABA seemed to decrease the peak as well as the basal discharge of the neurons in RVLM, but hardly changed their periodicities. 4. The cellular responses of RVLM evoked by the peripheral nerve stimulation could be inhibited by the iontophoretically released GABA. In conclusion, GABA seemed to act as an inhibitory neurotransmitter on the cardiac-related neurons in RVLM of the cats anesthetized with alpha-chloralose. But the maintenance of the periodicities of these cells after the application of bicuculline suggested that the afferent activity of the baroreceptor didn't play a key role in the spontaneous activities of the RVLM neurons.

Influence of Glutamate on the Circling Movement In the Unilateral Substantia Nigra-lesioned Rats / 신경정신의학

The aim of this study was to examine the effects of various concentrations of glutamate(10(-8), 10(-6) and 10(-4) M) on the circling movement induced by apomorphine in the unilateral substantia nigra-lesioned rats. Subcutaneous apomorphine(0.1 mg/kg) elicited contralateral circling movement(641.7+/-163.9/hr), Glutamate(10(-6)-10(-4) M) significantly reduced the numbers of apomorphine-induced circling movement. This reducing effect of glutamate was antagonized and/or reversed by 10(-7) M GABA antagonist bicuculline. These results suggest that glutamate reduces circling movement induced by apomorphine and this reducing effect of glutamate may be mediated by increased GABA concentration in striatum and substantia nigra.

Effect of muscimol and bicuculline on brain cAMP content in rats undergoing isoflnrane anesthesia / 中华麻醉学杂志

Objective To investigate the effects of GABAA receptor agonist-muscimol and GABAA receptor antagonist-bicuculline on brain cyclic adenosine monophosphate (cAMP) content in rats undergoing isoflurane anesthesia. Methods Forty-eight SD rats of both-sexes weighing 200-250g were randomly divided into 6 groups: group I received intraperitoneal (ip) normal saline (NS) 10ml.kg-1 (control group); group II in which animals inhaled 1.4% isoflurane for 30 min, 30 min after NS ip (isoflurane group);group IE in which animals inhaled 1.4% isoflurane for 30 min, 30 min after muscimol Img-kg ip (muscimol + isoflurane group); group IV in which animals inhaled 1.4% isoflurane for 30min, 30 min right after bicuculline 8 mg.kg-1 ip (bicuculline + isoflurane group); group V received muscimol lmg. kg-1 (muscimol group); group VI received bicuculline 8mg.kg (bicuculline group). The animals were decapitated 1h after 30min isoflurane inhalation or intraperitoneal NS or muscimol or 5min after bicuculline ip (rats developed convulsion within 7 min after bicuculline ip) . Brain was removed immediately for determination of cAMP content of cortex or brain stem. Loss of righting reflex was taken as sign of anesthesia. Brain cAMP content was measured by competitive protein binding assay. Results Muscimol shortened the time of loss of righting reflex induced by isoflurane (P