Quinolones and fenbufen interact with GABAA receptor in dissociated hippocampal cells of rat

1991 ◽  
Vol 66 (2) ◽  
pp. 497-504 ◽  
Author(s):  
N. Akaike ◽  
T. Shirasaki ◽  
T. Yakushiji
Keyword(s):  
Gabaa Receptor ◽  
Pyramidal Neurons ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inflammatory Agent ◽  
Quinolone Antibiotics ◽  
Anti Inflammatory

1. Interaction of quinolone antibiotics and the anti-inflammatory agent fenbufen with the gamma-aminobutyric acid-A (GABAA) receptor-chloride channel complex in pyramidal neurons freshly dissociated from the hippocampal CA1 region of the rats was investigated in whole-cell mode, using the patch-clamp technique under voltage-clamp conditions. 2. Quinolones in clinical doses had no effects on the GABA-gated Cl- current (ICl) but slightly suppressed the response at concentrations greater than 10(-5) M. A metabolite of fenbufen, 4-biphenylacetic acid (BPA), also had little effect on the GABA response at therapeutic concentrations. 3. Coadministration of one of quinolones and BPA suppressed the GABA-gated ICl with increase in each of them in a concentration-dependent manner, and there was a parallel shift of the concentration-response curve for GABA to the right but with no effect on the maximum response, thereby indicating a competitive antagonism. The inhibitory potency of antibiotics in combination with BPA was in the order of norfloxacin much greater than enoxacin greater than cyprofloxacin greater than pipemidic acid much greater than ofloxacin greater than cinoxacin = piromidic acid = nalidixic acid = 0. 4. Norfloxacin and BPA, administered simultaneously, also strongly suppressed pentobarbital sodium (PB)-gated ICl, but they did not act on benzodiazepine (BZP) receptors. 5. Both GABA- and PB-induced ICls reversed at the Cl- equilibrium potential (ECl). In the presence of BPA, the quinolone-induced inhibition of GABA-gated ICls showed no voltage dependence. 6. It was concluded that, in the presence of an anti-inflammatory agent, the quinolone antibiotics decrease the affinity of GABAA receptors, the result being induction of epileptogenic neurotoxicities.

gamma-Aminobutyric acid-induced response in rat dissociated paratracheal ganglion cells

1992 ◽  
Vol 67 (5) ◽  
pp. 1367-1374 ◽  
Author(s):  
S. Itabashi ◽  
K. Aibara ◽  
H. Sasaki ◽  
N. Akaike
Keyword(s):  
Response Curve ◽  
Ganglion Cells ◽  
Aminobutyric Acid ◽  
Equilibrium Potential ◽  
Induced Response ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Concentration Response Curve

1. The pharmacologic properties of gamma-aminobutyric acid (GABA)-induced Cl- current (ICl) were studied in the paratracheal ganglion cells freshly dissociated from 7- to 10-day-old rat trachea in a whole-cell recording mode by the use of a conventional patch-clamp technique. 2. GABA- and muscimol-induced currents increased sigmoidally in a concentration-dependent manner, and both currents reversed at approximately -3 mV, which was close to the Cl- equilibrium potential (ECl). 3. Strychnine (STR) at low concentration and bicuculline (BIC) inhibited GABA response competitively, whereas STR at the higher concentrations, benzylpenicillin (PCG), or picrotoxin (PTX) inhibited noncompetitively. Inhibition of GABA response by PCG but not other antagonists was voltage dependent, indicating that PCG acts as a Cl- channel blocker. 4. The concentration-response curve of pentobarbital sodium (PB)-induced ICl was bell shaped. At concentrations higher than 10(-3) M, both the peak and plateau currents decreased, and a transient "hump" current appeared immediately after washing out PB. In the presence of PB, the concentration-response curve of GABA shifted toward left without changing the maximum response. 5. Although diazepam (DZP) at concentration used did not induce a response, it potentiated the GABA response in a concentration-dependent manner between 10(-8) and 10(-6) M. DZP also caused a parallel shift toward left in the concentration-response curve of GABA. 6. PB or DZP further enhanced the GABA response in the presence of the other agent. 7. It is concluded that the properties of GABAA receptors in the paratracheal ganglion cells are essentially similar to those reported in other preparations.

gamma-Aminobutyric acid-induced response in acutely isolated nucleus solitarii neurons of the rat

1991 ◽  
Vol 260 (4) ◽  
pp. C745-C749 ◽  
Author(s):  
T. Nakagawa ◽  
M. Wakamori ◽  
T. Shirasaki ◽  
T. Nakaye ◽  
N. Akaike
Keyword(s):  
Response Curve ◽  
Aminobutyric Acid ◽  
Equilibrium Potential ◽  
Induced Response ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Voltage Dependent ◽  
Concentration Response Curve

The gamma-aminobutyric acid (GABA)-induced macroscopic Cl- current (ICl) was investigated in acutely isolated nucleus tractus solitarii (NTS) neurons by a conventional patch-clamp technique combined with a rapid drug application method. The GABA- and muscimol-induced ICl increased in a concentration-dependent manner. The reversal potentials were close to the Cl- equilibrium potential. Pentobarbital sodium (PB) itself elicited a current. Bicuculline (BIC), strychnine (STR), picrotoxin, benzylpenicillin (PCG), Cd2+, and Zn2+ suppressed the GABA response in a concentration-dependent manner. Both BIC and STR shifted the concentration-response curve for GABA response to the right, whereas PCG suppressed the maximum response without affecting the threshold, indicating that BIC and STR antagonized competitively and PCG noncompetitively. The inhibitory action of PCG on GABA response was in a highly voltage-dependent manner. PB shifted the concentration-response curve for GABA response to the left. The augmentatory effect of PB was voltage dependent.

Allosteric modulation of GABAA receptors in acutely dissociated neurons of the suprachiasmatic nucleus

1996 ◽  
Vol 270 (6) ◽  
pp. C1726-C1734 ◽  
Author(s):  
M. Shimura ◽  
N. Harata ◽  
M. Tamai ◽  
N. Akaike
Keyword(s):  
Gabaa Receptor ◽  
Suprachiasmatic Nucleus ◽  
Gabaa Receptors ◽  
Response Curve ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Gabaa Receptor Antagonist ◽  
Inward Currents ◽  
Concentration Response Curve

The gamma-aminobutyric acid (GABA)-induced response was investigated in acutely dissociated suprachiasmatic nucleus (SCN) neurons of 11- to 14-day-old rats, under the voltage-clamp condition of nystatin-perforated patch recording. At a holding potential of -40 mV, application of GABA induced inward currents in a concentration-dependent manner. Pentobarbital and 5 beta-pregnan-3 alpha-ol-20-one (pregnanolone) similarly induced inward currents. GABA-induced inward currents were suppressed in a concentration-dependent manner by pretreating neurons with a GABAA receptor antagonist, bicuculline. Bicuculline (3 x 10(-6) M) shifted the concentration-response curve of GABA to the left in a competitive manner. Reversal potential of the GABA response (EGABA) was -3.4 +/- 0.7 mV, close to the theoretical Cl- equilibrium potential of -4.1 mV. Pretreating SCN neurons with diazepam, pentobarbital, and pregnanolone enhanced the 3 x 10(-6) M GABA response. Diazepam (3 x 10(-8) M), pentobarbital (3 x 10(-5) M), and pregnanolone (10(-7) M) shifted the concentration-response curve of GABA to the left without changing the maximal amplitude of GABA responses. EGABA in the presence of diazepam, pentobarbital, or pregnanolone was the same as that in their absence. These results show that the GABA response in acutely dissociated SCN neurons is mediated by the GABAA receptor. Because the GABAA receptor of SCN neurons is allosterically augmented by diazepam, pentobarbital, and pregnanolone, similarly as in other regions of the central nervous system, the present study opens up ways to functionally modulate the GABAA receptors in SCN.

Serotonin-operated potassium current in CA1 neurons dissociated from rat hippocampus

1993 ◽  
Vol 69 (4) ◽  
pp. 1044-1052 ◽  
Author(s):  
H. Uneyama ◽  
S. Ueno ◽  
N. Akaike
Keyword(s):  
Pyramidal Neurons ◽  
Muscarinic Acetylcholine Receptor ◽  
Outward Current ◽  
Membrane Conductance ◽  
External Solution ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Hippocampal Pyramidal Neurons ◽  
Outward Currents

1. The intracellular mechanisms of serotonin (5-HT) response were investigated in dissociated rat hippocampal pyramidal neurons using the nystatin-perforated patch technique. 2. Under voltage-clamp conditions, 5-HT evoked outward currents (I5-HT) with an increase in membrane conductance at a holding potential of -40 mV. The outward current reversed at the K+ equilibrium potential, which shifted 59.4 mV with a 10-fold change in extracellular K+ concentration. 3. The first application of 5-HT on neurons perfused with Ca(2+)-free external solution induced outward currents of I5-HT but the amplitude was diminished dramatically with successive applications. Pretreatment with the membrane-permeant Ca2+ chelator 1,2-bis-(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, tetraacetoxymethyl ester (BAPTA-AM) also diminished the I5-HT amplitude. 4. Pretreatment with pertussis toxin (PTX) had no effect on I5-HT. 5. The I5-HT was not cross-desensitized with the caffeine-induced outward current but with outward current mediated by the muscarinic acetylcholine receptor. Pretreatment with Li+ significantly enhanced the I5-HT, indicating that I5-HT is involved in the elevation of intracellular free Ca2+ released from inositol triphosphate (IP3)-sensitive Ca2+ store sites but not from the caffeine-sensitive ones. 6. The calmodulin (CaM) antagonists, trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), inhibited I5-HT in a concentration-dependent manner. 7. The Ca2+/CaM-dependent protein kinase II inhibitor 1-[N,O-Bis (5-isoquinolinesulfonyl)-N-methyl-L-tyrosil]-4-phenylpiperazine depressed the I5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of glucose deprivation on NMDA-induced current and intracellular Ca2+ in rat substantia nigra neurons

1996 ◽  
Vol 75 (2) ◽  
pp. 740-749 ◽  
Author(s):  
Y. Nakashima ◽  
H. Ishibashi ◽  
N. Harata ◽  
N. Akaike
Keyword(s):  
Substantia Nigra ◽  
Outward Current ◽  
Glucose Deprivation ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Induced Current ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inward Current ◽  
Rat Substantia Nigra

1. The effects of glucose deprivation on N-methyl-D-asparate (NMDA)-induced current (INMDA) and the intracellular free Ca2+ concentration ([Ca2+]i) in the acutely dissociated rat substantia nigra neurons were investigated using the nystatin-perforated patch-clamp technique under voltage clamp and the microfluometry with a fluorescent probe, Indo-1. 2. Application of NMDA induced a peak and a successive steady-state inward current, and an outward current immediately after washout at a holding potential of -40 mV. The amplitudes of the three current components of INMDA were increased by increasing the concentrations of NMDA with half-maximum concentrations (EC50s) of 1.1 x 10(-4) M, 1.2 x 10(-4) M, and 1.6 x 10(-4) M, respectively. 3. The reversal potentials of the peak inward and outward currents were -4 +/- 3 (SE) mV and -76 +/- 2 mV, respectively. The latter was close to the theoretical K+ equilibrium potential (-82 mV). 4. The outward current was potentiated by increase in extracellular Ca2+ concentration and was blocked by Cs+ internal solution and suppressed by 5 x 10(-3) M tetraethylammonium chloride and 10(-7) M charybdotoxin, indicating that it was Ca(2+)-activated K+ current. 5. Application of NMDA increased [Ca2+]i in a concentration-dependent manner with an EC50 of 3.9 x 10(-5) M. 6. Depriving the external solution of glucose induced a slowly developing outward current and increased the basal level of [Ca2+]i. It also prolonged the NMDA-induced outward current without affecting the peak inward current, and prolonged the NMDA-induced increase in [Ca2+]i without changing the peak [Ca2+]i. 7. These findings suggest that the deprivation of glucose did not affect the NMDA-induced influx of Ca2+ into the cells, but it inhibited Ca2+ clearance by affecting the efflux of Ca2+ to the extracellular space, reuptake into the intracellular Ca2+ stores, and/or active extrusion from intracellular stores.

scholarly journals Bioactivity-Guided Extract Optimization of Osmanthus fragrans var. aurantiacus Leaves and Anti-Inflammatory Activities of Phillyrin

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1545
Author(s):  
Hwa-Young Song ◽  
Da-Eun Jeong ◽  
Mina Lee
Keyword(s):  
Biological Activities ◽  
Radical Scavenging ◽  
No Production ◽  
Dependent Manner ◽  
Optimal Method ◽  
Concentration Dependent Manner ◽  
Osmanthus Fragrans ◽  
Tnf Α ◽  
Anti Inflammatory ◽  
Extracellular Regulated Kinase

The aim of this study was to identify the optimal extraction conditions for leaves of Osmanthus fragrans var. aurantiacus. Inhibitory effects of various extracts on NO production were compared. Antioxidant evaluations for total phenol and flavonoid contents were carried out using various extracts of O. fragrans var. aurantiacus leaves obtained under optimal extraction conditions that showed the greatest effect on NO production. The optimal method for extracting O. fragrans var. aurantiacus leaves resulted in an extract named OP OFLE. OP OFLE showed DPPH and ABTS radical scavenging activities in a concentration-dependent manner. Phillyrin (PH) was isolated as a major compound from OP OFLE by HPLC/DAD analysis. OP OFLE and PH reduced inducible nitric oxide (iNOS) and cyclooxygenase (COX)-2 protein expression and downregulated proinflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in LPS-stimulated RAW 264.7 and HT-29 cells. To determine the signal pathway involved in the inhibition of NO production, a Western blot analysis was performed. Results showed that OP OFLE decreased phosphorylation of extracellular regulated kinase (pERK) 1/2 and the expression of nuclear factor-kappa B (NF-κB). Our results suggest that extracts of O. fragrans var. aurantiacus leaves and its major components have biological activities such as antioxidative and anti-inflammatory properties.

scholarly journals Epipregnanolone as a Positive Modulator of GABAA Receptor in Rat Cerebellar and Hippocampus Neurons

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 791
Author(s):  
Julia Bukanova ◽  
Elena Solntseva ◽  
Rodion Kondratenko ◽  
Eva Kudova
Keyword(s):  
Gabaa Receptor ◽  
Purkinje Cells ◽  
Hippocampal Neurons ◽  
Pyramidal Neurons ◽  
Patch Clamp Technique ◽  
Dual Effect ◽  
Combined Application ◽  
Gabaa Receptor Antagonist ◽  
Positive Modulator ◽  
Endogenous Steroid

Epipregnanolone (3β-hydroxy-5β-pregnan-20-one, Epi) is an endogenous steroid with important physiological effects and high affinity for GABAA receptors. The effect of Epi on GABA-induced chloride current (IGABA) in native neurons has hardly been studied. In this work, we studied the influence of Epi on the IGABA in the Purkinje cells of rat cerebellum and pyramidal neurons of rat hippocampus with the patch clamp technique. We showed that Epi is a positive modulator of the IGABA with EC50 of 5.7 µM in Purkinje cells and 9.3 µM in hippocampal neurons. Epi-induced potentiation of the IGABA was more potent at low vs. high GABA concentrations. Isopregnanolone (3β-hydroxy-5α-pregnan-20-one, Iso) counteracted Epi, reducing its potentiating effect by 2–2.3 times. Flumazenil, a nonsteroidal GABAA receptor antagonist, does not affect the Epi-induced potentiation. Comparison of the potentiating effects of Epi and allopregnanolone (3α-hydroxy-5α-pregnan-20-one, ALLO) showed that ALLO is, at least, a four times more potent positive modulator than Epi. The combined application of ALLO and Epi showed that the effects of these two steroids are not additive. We conclude that Epi has a dual effect on the IGABA increasing the current in the control solution and decreasing the stimulatory effect of ALLO.

scholarly journals Oxytocin Inhibits T-Type Calcium Current of Human Decidual Stromal Cells

2005 ◽  
Vol 90 (7) ◽  
pp. 4191-4197 ◽  
Author(s):  
Bo Liu ◽  
Stephen J. Hill ◽  
Raheela N. Khan
Keyword(s):  
Stromal Cells ◽  
Calcium Current ◽  
Elective Cesarean Section ◽  
Dependent Manner ◽  
Uterine Contractility ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inactivation Curve ◽  
Decidual Cells ◽  
Elective Cesarean

Abstract Context: Little is known about the crosstalk between the decidua and myometrium in relation to human labor. The hormone oxytocin (OT) is considered to be a key mediator of uterine contractility during parturition, exerting some of its effects through calcium channels. Objective: The objective was to characterize the effect of OT on the T-type calcium channel in human decidual stromal cells before and after the onset of labor. Design: The nystatin-perforated patch-clamp technique was used to record inward T-type calcium current (ICa(T)) from acutely dispersed decidual stromal cells obtained from women at either elective cesarean section [CS (nonlabor)] or after normal spontaneous vaginal delivery [SVD (labor)]. Setting: These studies took place at the University of Nottingham Medical School. Results: I Ca(T) of both SVD and CS cells were blocked by nickel (IC50 of 5.6 μm) and cobalt chloride (1 mm) but unaffected by nifedipine (10 μm). OT (1 nm to 3.5 μm) inhibited ICa(T) of SVD cells in a concentration-dependent manner, with a maximal inhibition of 79.0% compared with 26.2% in decidual cells of the CS group. OT-evoked reduction of ICa(T) was prevented by preincubation with the OT antagonist L371,257 in the SVD but not CS group. OT, in a concentration-dependent manner, displaced the steady-state inactivation curve for ICa(T) to the left in the SVD group with no significant effect on curves of the CS group. Conclusion: Inhibition of ICa(T) by OT in decidual cells obtained during labor may signify important functional remodeling of uterine signaling during this period.

Analysis of voltage-gated and synaptic conductances contributing to network excitability defects in the mutant mouse tottering

1994 ◽  
Vol 71 (1) ◽  
pp. 1-10 ◽  
Author(s):  
S. A. Helekar ◽  
J. L. Noebels
Keyword(s):  
Gabaa Receptor ◽  
Pyramidal Neurons ◽  
Hippocampal Slices ◽  
Channel Blockers ◽  
Gamma Aminobutyric Acid ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Prolonged Duration ◽  
Ca3 Pyramidal Neurons ◽  
The Difference

1. Intracellular current- and voltage-clamp recordings were carried out in CA3 pyramidal neurons from hippocampal slices of adult tg/tg mice and their coisogenic C57BL/6J (+/+) controls with the use of the single-electrode switch-clamp technique. The principal aim of this study was to investigate the mechanisms responsible for the tg gene-linked prolongation (mean 60%) of a giant synaptic response, the potassium-induced paroxysmal depolarizing shift (PDS) at depolarized membrane potentials (Vm -47 to -54 mV) during synchronous network bursting induced by 10 mM potassium ([K+]o). 2. To examine the role of intrinsic voltage-dependent conductances underlying the mutant PDS prolongation, neurons were voltage clamped by the use of microelectrodes filled with 100 mM QX-314 or QX-222 chloride (voltage-gated sodium channel blockers) and 2 M cesium sulphate (potassium channel blocker). The whole-cell currents active during the PDS showed a significantly prolonged duration (mean 34%) at depolarized Vms in tg/tg compared with +/+ cells, indicating that a defect in voltage-dependent conductances is unlikely to completely account for the mutant phenotype. 3. Bath application of 40 microM (DL)-2-aminophosphonovalerate (DL-APV) produced a 30% reduction in PDS duration in both genotypes but failed to significantly alter the tg gene-linked prolongation compared with the wild type. These data indicate that the mutant PDS abnormality does not result from a selective increase of the N-methyl-D-aspartate (NMDA) receptor-mediated excitatory synaptic component. 4. Blockade of gamma-aminobutyric acid-A (GABAA) transmission with picrotoxin (50 microM) or bicuculline (1–5 microM) completely eliminated the difference in PDS duration between the genotypes. Furthermore, although both GABAA receptor antagonists increased the mean PDS duration in +/+ neurons, they did not significantly alter it in tg/tg neurons. These findings are consistent with a reduction in GABAA receptor-mediated synaptic inhibition during bursting in the tg CA3 hippocampal network. 5. To test this hypothesis, bursting CA3 pyramidal neurons were loaded intracellularly with chloride by the use of KCl-filled microelectrodes to examine the effect of reversing the hyperpolarizing chloride-dependent GABAA receptor-mediated inhibitory postsynaptic component of the PDS. Chloride loading prolonged PDS duration in both genotypes, but the increase was greater in +/+ than in tg/tg neurons, indicating that a smaller GABAA inhibitory postsynaptic potential (IPSP) component was reversed in the mutant.(ABSTRACT TRUNCATED AT 400 WORDS)

Alpha-subunit of calcium/calmodulin-dependent protein kinase II enhances gamma-aminobutyric acid and inhibitory synaptic responses of rat neurons in vitro

1995 ◽  
Vol 73 (5) ◽  
pp. 2099-2106 ◽  
Author(s):  
R. A. Wang ◽  
G. Cheng ◽  
M. Kolaj ◽  
M. Randic
Keyword(s):  
Protein Kinase ◽  
Gabaa Receptor ◽  
Aminobutyric Acid ◽  
Alpha Subunit ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Dependent Protein Kinase ◽  
Calcium Calmodulin Dependent ◽  
Protein Kinase Ii ◽  
Dependent Protein

1. Here we report that in acutely isolated rat spinal dorsal horn neurons, the gamma-aminobutyric acid-A (GABAA) receptor can be regulated by calcium/calmodulin-dependent protein kinase II (CaM-KII). Intracellularly applied, the alpha-subunit of CaM-KII enhanced GABAA-receptor-activated current recorded with the use of the whole cell patch-clamp technique. This effect was associated with reduced desensitization of GABA responses. 2. GABA-induced currents are also potentiated by calyculin A, an inhibitor of protein phosphatases 1 and 2A. 3. Conventional intracellular recordings were made from hippocampal CA1 neurons in slices to determine the effect of intracellular application of CaM-KII on inhibitory synaptic potentials evoked by electrical stimulation of the stratum oriens/alveus. The inhibitory synaptic potential was enhanced by CaM-KII; this mechanism may contribute to long-term enhancement of inhibitory synaptic transmission and may also play a role in other forms of plasticity in the mammalian brain.

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