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Sarkar J, Chakraborti T, Pramanik PK, Ghosh P, Mandal A, Chakraborti S. PKCζ-NADPH Oxidase-PKCα Dependent Kv1.5 Phosphorylation by Endothelin-1 Modulates Nav1.5-NCX1-Cav1.2 Axis in Stimulating Ca 2+ Level in Caveolae of Pulmonary Artery Smooth Muscle Cells. Cell Biochem Biophys 2020; 79:57-71. [PMID: 33095400 DOI: 10.1007/s12013-020-00954-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2020] [Indexed: 11/29/2022]
Abstract
Endothelin-1 (ET-1) is a potent endogenously derived vasoconstrictor, which increases pulmonary hypertension via stimulation of [Ca2+]i level in pulmonary artery smooth muscle cells (PASMCs). In this communication, we sought to investigate the mechanism by which ET-1 causes stimulation of Ca2+ concentration in caveolae vesicles of bovine PASMCs (BPASMCs). ET-1 activates PKC-α in the caveolae vesicles by O2.- derived from PKCζ-NADPH oxidase dependent pathway. PKC-α phosphorylates Kv1.5 channels leading to a marked stimulation of Na+ and Ca2+ concentration in the caveolae vesicles. The stimulation of Ca2+ concentration in the caveolae vesicles by ET-1 occurs predominantly via Cav1.2 channels. Additionally, an increase in Na+ concentration by ET-1 due to stimulation of Nav1.5 channels marginally increases Ca2+ level in the caveolae vesicles via reverse-mode Na+/Ca2+ exchanger (NCX-1) and also through "slip-mode conductance" Nav1.5 channels. 4-AP, a well-known inhibitor of Kv channels, also increases Ca2+ concentration in the caveolae vesicles via Cav1.2 channels, reverse-mode NCX-1 and Nav1.5 channels by phosphorylation independent modulation of Kv1.5 channels without the involvement of PKCζ-NADPH oxidase-PKCα signaling axis. Overall, PKCζ-NADPH oxidase-PKCα dependent phosphorylation of Kv1.5 by ET-1 modulates Nav1.5-NCX1-Cav1.2 axis for stimulation of Ca2+ concentration in caveolae vesicles of BPASMCs, which provides a crucial mechanism for better understanding of ET-1-mediated modulation of pulmonary vascular tone.
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Affiliation(s)
- Jaganmay Sarkar
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, 741235, India
| | - Tapati Chakraborti
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, 741235, India
| | - Pijush Kanti Pramanik
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, 741235, India
| | - Priyanka Ghosh
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, 741235, India
| | - Amritlal Mandal
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, 741235, India
| | - Sajal Chakraborti
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, West Bengal, 741235, India.
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Odawara A, Matsuda N, Ishibashi Y, Yokoi R, Suzuki I. Toxicological evaluation of convulsant and anticonvulsant drugs in human induced pluripotent stem cell-derived cortical neuronal networks using an MEA system. Sci Rep 2018; 8:10416. [PMID: 29991696 PMCID: PMC6039442 DOI: 10.1038/s41598-018-28835-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 07/02/2018] [Indexed: 12/14/2022] Open
Abstract
Functional evaluation assays using human induced pluripotent stem cell (hiPSC)-derived neurons can predict the convulsion toxicity of new drugs and the neurological effects of antiepileptic drugs. However, differences in responsiveness depending on convulsant type and antiepileptic drugs, and an evaluation index capable of comparing in vitro responses with in vivo responses are not well known. We observed the difference in synchronized burst patterns in the epileptiform activities induced by pentylentetrazole (PTZ) and 4-aminopryridine (4-AP) with different action mechanisms using multi-electrode arrays (MEAs); we also observed that 100 µM of the antiepileptic drug phenytoin suppressed epileptiform activities induced by PTZ, but increased those induced by 4-AP. To compare in vitro results with in vivo convulsive responses, frequency analysis of below 250 Hz, excluding the spike component, was performed. The in vivo convulsive firing enhancement of the high γ wave and β wave component were observed remarkably in in vitro hiPSC-derived neurons with astrocytes in co-culture. MEA measurement of hiPSC-derived neurons in co-culture with astrocytes and our analysis methods, including frequency analysis, appear effective for predicting convulsion toxicity, side effects, and their mechanism of action as well as the comparison of convulsions induced in vivo.
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Affiliation(s)
- A Odawara
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, 35-1 Yagiyama Kasumicho, Taihaku-ku, Sendai, Miyagi, 982-8577, Japan.,Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 982-8577, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - N Matsuda
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, 35-1 Yagiyama Kasumicho, Taihaku-ku, Sendai, Miyagi, 982-8577, Japan
| | - Y Ishibashi
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, 35-1 Yagiyama Kasumicho, Taihaku-ku, Sendai, Miyagi, 982-8577, Japan
| | - R Yokoi
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, 35-1 Yagiyama Kasumicho, Taihaku-ku, Sendai, Miyagi, 982-8577, Japan
| | - I Suzuki
- Department of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, 35-1 Yagiyama Kasumicho, Taihaku-ku, Sendai, Miyagi, 982-8577, Japan. .,iPS-non-Clinical Experiments for Nervous System (iNCENS) Project, Kanagawa, Japan. .,Consortium for Safety Assessment using Human iPS Cells (CSAHi), Kanagawa, Japan.
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Sitges M, Aldana BI, Reed RC. Effect of the Anti-depressant Sertraline, the Novel Anti-seizure Drug Vinpocetine and Several Conventional Antiepileptic Drugs on the Epileptiform EEG Activity Induced by 4-Aminopyridine. Neurochem Res 2016; 41:1365-74. [PMID: 26830290 DOI: 10.1007/s11064-016-1840-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/18/2016] [Accepted: 01/20/2016] [Indexed: 11/25/2022]
Abstract
Seizures are accompanied by an exacerbated activation of cerebral ion channels. 4-aminopyridine (4-AP) is a pro-convulsive agent which mechanism of action involves activation of Na(+) and Ca(2+) channels, and several antiepileptic drugs control seizures by reducing these channels permeability. The antidepressant, sertraline, and the anti-seizure drug vinpocetine are effective inhibitors of cerebral presynaptic Na(+) channels. Here the effectiveness of these compounds to prevent the epileptiform EEG activity induced by 4-AP was compared with the effectiveness of seven conventional antiepileptic drugs. For this purpose, EEG recordings before and at three intervals within the next 30 min following 4-AP (2.5 mg/kg, i.p.) were taken in anesthetized animals; and the EEG-highest peak amplitude values (HPAV) calculated. In control animals, the marked increase in the EEG-HPAV observed near 20 min following 4-AP reached its maximum at 30 min. Results show that this epileptiform EEG activity induced by 4-AP is prevented by sertraline and vinpocetine at a dose of 2.5 mg/kg, and by carbamazepine, phenytoin, lamotrigine and oxcarbazepine at a higher dose (25 mg/kg). In contrast, topiramate (25 mg/kg), valproate (100 mg/kg) and levetiracetam (100 mg/kg) failed to prevent the epileptiform EEG activity induced by 4-AP. It is concluded that 4-AP is a useful tool to elicit the mechanism of action of anti-seizure drugs at clinical meaningful doses. The particular efficacy of sertraline and vinpocetine to prevent seizures induced by 4-AP is explained by their high effectiveness to reduce brain presynaptic Na(+) and Ca(2+) channels permeability.
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Affiliation(s)
- Maria Sitges
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, A.P. 70228, Ciudad Universitaria, 04510, Mexico, DF, Mexico.
| | - Blanca Irene Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ronald Charles Reed
- Department of Pharmacy Practice, Husson University, One College Circle, Bangor, ME, 04401-2999, USA
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Effects of Levetiracetam, Carbamazepine, Phenytoin, Valproate, Lamotrigine, Oxcarbazepine, Topiramate, Vinpocetine and Sertraline on Presynaptic Hippocampal Na(+) and Ca(2+) Channels Permeability. Neurochem Res 2015; 41:758-69. [PMID: 26542150 DOI: 10.1007/s11064-015-1749-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/22/2015] [Accepted: 10/27/2015] [Indexed: 10/22/2022]
Abstract
Ion channels are targets of various antiepileptic drugs. In cerebral presynaptic nerve endings Na(+) and Ca(2+) channels are particularly abundant, as they control neurotransmitter release, including the release of glutamate (Glu), the most concentrated excitatory amino acid neurotransmitter in the brain. Several pre-synaptic channels are implicated in the mechanism of action of the pro-convulsive agent, 4-aminopyridine (4-AP). In the present study the effects of levetiracetam and other established and newer (vinpocetine) anti-epileptic drugs, as well as of the anti-depressant, sertraline on the increase in Ca(2+) induced by 4-AP in hippocampal isolated nerve endings were investigated. Also the effects of some of the anti-seizure drugs on the selective increase in Ca(2+) induced by high K(+), or on the selective increase in Na(+) induced by veratridine were tested. Sertraline and vinpocetine effectively inhibited the rise in Ca(2+) induced by 4-AP, which was dependent on the out-in Na(+) gradient and tetrodotoxin sensitive. Carbamazepine, phenytoin, lamotrigine and oxcarbazepine inhibited the rise in Ca(2+) induced by 4-AP too, but at higher concentrations than sertraline and vinpocetine, whereas levetiracetam, valproic acid and topiramate did not. The three latter antiepileptic drugs also failed in modifying other responses mediated by the activation of brain presynaptic Na(+) or Ca(2+) channels, including Glu release. This indicates that levetiracetam, valproic acid and topiramate mechanisms of action are unrelated with a decrease in presynaptic Na(+) or Ca(2+) channels permeability. It is concluded that depolarized cerebral isolated nerve endings represent a useful tool to unmask potential antiepileptic drugs targeting presynaptic Na(+) and/or Ca(2+) channels in the brain; such as vinpocetine or the anti-depressant sertraline, which high effectiveness to control seizures in the animal in vivo has been demonstrated.
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Sitges M, Gómez CD, Aldana BI. Sertraline reduces IL-1β and TNF-α mRNA expression and overcomes their rise induced by seizures in the rat hippocampus. PLoS One 2014; 9:e111665. [PMID: 25364907 PMCID: PMC4218797 DOI: 10.1371/journal.pone.0111665] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 09/30/2014] [Indexed: 12/26/2022] Open
Abstract
We recently discovered that the antidepressant sertraline is an effective inhibitor of hippocampus presynaptic Na+ channel permeability invitro and of tonic-clonic seizures in animals invivo. Several studies indicate that the pro-inflammatory cytokines in the central nervous system are increased in epilepsy and depression. On the other hand inhibition of Na+ channels has been shown to decrease pro-inflammatory cytokines in microglia. Therefore, the possibility that sertraline could overcome the rise in pro-inflammatory cytokine expression induced by seizures has been investigated. For this purpose, IL-1β and TNF-α mRNA expression was determined by RT-PCR in the hippocampus of rats administered once, or for seven consecutive days with sertraline at a low dose (0.75 mg/kg). The effect of sertraline at doses within the range of 0.75 to 25 mg/kg on the increase in IL-1β and TNF-α mRNA expression accompanying generalized tonic-clonic seizures, and increase in the pro-inflammatory cytokines expression induced by lipopolysaccharide was also investigated. We found that under basal conditions, a single 0.75 mg/kg sertraline dose decreased IL-1β mRNA expression, and also TNF-α expression after repeated doses. The increase in IL-1β and TNF-α expression induced by the convulsive agents and by the inoculation of lipopolysaccharide in the hippocampus was markedly reduced by sertraline also. Present results indicate that a reduction of brain inflammatory processes may contribute to the anti-seizure sertraline action, and that sertraline can be safely and successfully used at low doses to treat depression in epileptic patients.
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Affiliation(s)
- María Sitges
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Distrito Federal, México
- * E-mail:
| | - Carlos D. Gómez
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Distrito Federal, México
| | - Blanca I. Aldana
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Distrito Federal, México
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Gómez CD, Buijs RM, Sitges M. The anti-seizure drugs vinpocetine and carbamazepine, but not valproic acid, reduce inflammatory IL-1β and TNF-α expression in rat hippocampus. J Neurochem 2014; 130:770-9. [PMID: 24903676 DOI: 10.1111/jnc.12784] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/26/2014] [Accepted: 05/30/2014] [Indexed: 12/25/2022]
Abstract
In the present study, the effects of the two classical anti-epileptic drugs, carbamazepine and valproic acid, and the non-classical anti-seizure drug vinpocetine were investigated on the expression of the pro-inflammatory cytokines IL-1β and TNF-α in the hippocampus of rats by PCR or western blot after the administration of one or seven doses. Next, the effects of the anti-seizure drugs were investigated on the rise in cytokine expression induced by lipopolysaccharides (LPS) inoculation in vivo. To validate our methods, the changes induced by the pro-convulsive agents 4-aminopyridine, pentylenetetrazole and pilocarpine were also tested. Finally, the effect of the anti-seizure drugs on seizures and on the concomitant rise in pro-inflammatory cytokine expression induced by 4-aminopyridine was explored. Results show that vinpocetine and carbamazepine reduced the expression of IL-1β and TNF-α from basal conditions, and the increase in both pro-inflammatory cytokines induced by LPS. In contrast, valproic acid failed to reduce both the expression of the cytokines from basal conditions and the rise in IL-1β and TNF-α expression induced by LPS. Tonic-clonic seizures induced either by 4-aminopyridine, pentylenetetrazole or pilocarpine increased the expression of IL-1β and TNF-α markedly. 4-aminopyridine-induced changes were reduced by all the tested anti-seizure drugs, although valproic acid was less effective. We conclude that the anti-seizure drugs, vinpocetine and carbamazepine, whose mechanisms of action involve a decrease in ion channels permeability, also reduce cerebral inflammation. The mechanism of action of anti-seizure drugs like vinpocetine and carbamazepine involves a decrease in Na(+) channels permeability. We here propose that this mechanism of action also involves a decrease in cerebral inflammation.
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Affiliation(s)
- Carlos D Gómez
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, DF, México
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Westphalen RI, Desai KM, Hemmings HC. Presynaptic inhibition of the release of multiple major central nervous system neurotransmitter types by the inhaled anaesthetic isoflurane. Br J Anaesth 2012; 110:592-9. [PMID: 23213036 DOI: 10.1093/bja/aes448] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Presynaptic effects of general anaesthetics are not well characterized. We tested the hypothesis that isoflurane exhibits transmitter-specific effects on neurotransmitter release from neurochemically and functionally distinct isolated mammalian nerve terminals. METHODS Nerve terminals from adult male rat brain were prelabelled with [(3)H]glutamate and [(14)C]GABA (cerebral cortex), [(3)H]norepinephrine (hippocampus), [(14)C]dopamine (striatum), or [(3)H]choline (precursor of [(3)H]acetylcholine; striatum). Release evoked by depolarizing pulses of 4-aminopyridine (4AP) or elevated KCl was quantified using a closed superfusion system. RESULTS Isoflurane at clinical concentrations (<0.7 mM; ~2 times median anaesthetic concentration) inhibited Na(+) channel-dependent 4AP-evoked release of the five neurotransmitters tested in a concentration-dependent manner. Isoflurane was a more potent inhibitor [expressed as IC(50) (SEM)] of glutamate release [0.37 (0.03) mM; P<0.05] compared with the release of GABA [0.52 (0.03) mM], norepinephrine [0.48 (0.03) mM], dopamine [0.48 (0.03) mM], or acetylcholine [0.49 (0.02) mM]. Inhibition of Na(+) channel-independent release evoked by elevated K(+) was not significant at clinical concentrations of isoflurane, with the exception of dopamine release [IC(50)=0.59 (0.03) mM]. CONCLUSIONS Isoflurane inhibited the release of the major central nervous system neurotransmitters with selectivity for glutamate release, consistent with both widespread inhibition and nerve terminal-specific presynaptic effects. Glutamate release was most sensitive to inhibition compared with GABA, acetylcholine, dopamine, and norepinephrine release due to presynaptic specializations in ion channel expression, regulation, and/or coupling to exocytosis. Reductions in neurotransmitter release by volatile anaesthetics could contribute to altered synaptic transmission, leading to therapeutic and toxic effects involving all major neurotransmitter systems.
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Affiliation(s)
- R I Westphalen
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
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Sitges M, Aldana BI, Gómez CD, Nekrassov V. The antidepressant sertraline prevents the behavioral and EEG changes induced in two animal models of seizures. Epilepsy Behav 2012; 25:511-6. [PMID: 23153716 DOI: 10.1016/j.yebeh.2012.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 09/10/2012] [Accepted: 09/12/2012] [Indexed: 11/16/2022]
Abstract
In order to investigate a potential anticonvulsive action of sertraline (i.p.), its effects on seizures, EEG epileptiform activity and EEG amplitude increases induced by two convulsive agents were evaluated and compared with the effects of carbamazepine. Around 20 min following 4-aminopyridine (4-AP, 2.5 mg/kg, i.p.), tonic-clonic seizures and epileptiform activity were observed in control animals. A single sertraline pre-injection of 2.5 mg/kg, but not of 0.75 mg/kg, prevented these changes to 4-AP. Repeated daily administration of 0.75 mg/kg for one week, however, effectively inhibited the changes induced by 4-AP. The first generalized tonic-clonic seizure and EEG changes in response to pentylenetetrazole (PTZ, 50 mg/kg, i.p.) were observed near the first minute in control animals. Single sertraline doses above 5 mg/kg prevented the PTZ-induced changes. Moreover, a single carbamazepine dose of 25 mg/kg (i.p.), but not of 15 mg/kg, prevented the changes induced by the above convulsive agents. An anti-seizure action of the antidepressant sertraline is strongly suggested by these findings.
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Affiliation(s)
- María Sitges
- Depto. de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México.
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Sitges M, Sanchez-Tafolla B, Chiu L, Aldana B, Guarneros A. Vinpocetine inhibits glutamate release induced by the convulsive agent 4-aminopyridine more potently than several antiepileptic drugs. Epilepsy Res 2011; 96:257-66. [DOI: 10.1016/j.eplepsyres.2011.06.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 06/08/2011] [Accepted: 06/11/2011] [Indexed: 10/18/2022]
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Herrera-Mundo N, Sitges M. Mechanisms underlying striatal vulnerability to 3-nitropropionic acid. J Neurochem 2010; 114:597-605. [PMID: 20477912 DOI: 10.1111/j.1471-4159.2010.06789.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The striatum is a cerebral structure particularly susceptible to the metabolic challenge exerted by 3-nitropropionic acid (3-NPA), a toxin that inhibits the respiratory chain at complex II. The striatum, which receives the nerve endings of the nigro-striatal pathway, concentrates the largest amount of 3,4-dihydroxyphenylethylamine or dopamine (DA) in the brain. DA is metabolized to 3,4-dihydroxyphenylacetic acid (DOPAC) by monoamine oxidase (MAO), an enzyme that contains a redox-active disulfide in the active site. In striatum isolated nerve endings exposed to 3-NPA in vitro, DA increased and DOPAC decreased already after 10 min, and after 2 h also an increase in reactive oxygen species and DA-quinone products formation was detected. These 3-NPA-induced effects resulted in an increase in DA release after 2 h. In striatum homogenates from animals presenting motor disturbances in response to 3-NPA in vivo, the DA metabolites homovanillic acid and DOPAC were increased. It is concluded that in the striatum nerve endings where DA is particularly concentrated, the increase in reactive oxygen species induced by 3-NPA, oxidizes DA generating DA-quinones. These DA-quinones may form adducts with the active site of MAO type A reducing its activity. The DA not metabolized to DOPAC is both, used to unchain generation of more of the harmful DA-oxidation products and released to the external medium, where is metabolized by the non-neuronal enzymes MAO type B and catechol-O-methyltransferase.
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Affiliation(s)
- Nieves Herrera-Mundo
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México DF, México
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Takenouchi T, Iwamaru Y, Sugama S, Sato M, Hashimoto M, Kitani H. Lysophospholipids and ATP mutually suppress maturation and release of IL-1 beta in mouse microglial cells using a Rho-dependent pathway. THE JOURNAL OF IMMUNOLOGY 2008; 180:7827-39. [PMID: 18523246 DOI: 10.4049/jimmunol.180.12.7827] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The P2X7 receptor (P2X7R), an ATP-gated ion channel, plays essential roles in the release and maturation of IL-1beta in microglial cells in the brain. Previously, we found that lysophosphatidylcholine (LPC) potentiated P2X7R-mediated intracellular signals in microglial cells. In this study, we determined whether the lysophospholipids, i.e., LPC and sphingosylphosphorylcholine (SPC), modulate the ATP-induced release and processing of IL-1beta mediated by P2X7R in mouse MG6 microglial cells. LPC or SPC alone induced the release of precursor (pro-IL-1beta) and mature IL-1beta (mIL-1beta) from LPS-primed MG6 cells, possibly due to lytic functions. However, these lysophospholipids inhibited ATP-induced caspase-1 activation that is usually followed by the release of mIL-1beta. Conversely, ATP inhibited the release of pro-IL-1beta and mIL-1beta induced by LPC/SPC. This suggests that lysophospholipids and ATP mutually suppressed each function to release IL-1beta. P2X7R activation resulted in microtubule reorganization in the MG6 cells that was blocked in the presence of LPC and SPC. LPC/SPC reduced the amount of activated RhoA after stimulation with ATP, implying that these lysophospholipids block ATP-induced microtubule reorganization by interfering with RhoA activation. In addition, the microtubule inhibitor colchicine inhibited ATP-induced release of mIL-1beta similar to that of LPC and SPC. This suggests that the impairment of the microtubule reassembly may be associated with the inhibitory effects of LPC/SPC on ATP-induced mIL-1beta release. Mutual suppression by ATP and LPC/SPC on the maturation of IL-1beta was observed in LPS-primed primary microglia. Collectively, these data suggest opposing functions by lysophospholipids, either proinflammatory or anti-inflammatory, in regard to the maturation and release of IL-1beta from microglial cells.
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Affiliation(s)
- Takato Takenouchi
- Transgenic Animal Research Center, National Institute of Agrobiological Sciences, Tsukuba, Japan
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Kobayashi K, Nishizawa Y, Sawada K, Ogura H, Miyabe M. K+-Channel Openers Suppress Epileptiform Activities Induced by 4-Aminopyridine in Cultured Rat Hippocampal Neurons. J Pharmacol Sci 2008; 108:517-28. [DOI: 10.1254/jphs.08214fp] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Sitges M, Guarneros A, Nekrassov V. Effects of carbamazepine, phenytoin, valproic acid, oxcarbazepine, lamotrigine, topiramate and vinpocetine on the presynaptic Ca2+ channel-mediated release of [3H]glutamate: Comparison with the Na+ channel-mediated release. Neuropharmacology 2007; 53:854-62. [PMID: 17904592 DOI: 10.1016/j.neuropharm.2007.08.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 07/03/2007] [Accepted: 08/13/2007] [Indexed: 10/22/2022]
Abstract
The effect of carbamazepine, phenytoin, valproate, oxcarbazepine, lamotrigine and topiramate, that are among the most widely used antiepileptic drugs (AEDs), and of the new putative AED vinpocetine on the Ca(2+) channel-mediated release of [(3)H]Glu evoked by high K(+) in hippocampal isolated nerve endings was investigated. Results show that carbamazepine, oxcarbazepine and phenytoin reduced [(3)H]Glu release to high K(+) to about 30% and 55% at concentrations of 500 microM and 1500 microM, respectively; lamotrigine and topiramate to about 27% at 1500 microM; while valproate failed to modify it. Vinpocetine was the most potent and effective; 50 microM vinpocetine practically abolished the high K(+) evoked release of [(3)H]Glu. Comparison of the inhibition exerted by the AEDs on [(3)H]Glu release evoked by high K(+) with the inhibition exerted by the AEDs on [(3)H]Glu release evoked by the Na(+) channel opener, veratridine, shows that all the AEDs are in general more effective blockers of the presynaptic Na(+) than of the presynaptic Ca(2+) channel-mediated response. The high doses of AEDs required to control seizures are frequently accompanied by adverse secondary effects. Therefore, the higher potency and efficacy of vinpocetine to reduce the permeability of presynaptic ionic channels controlling the release of the most important excitatory neurotransmitter in the brain must be advantageous in the treatment of epilepsy.
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Affiliation(s)
- María Sitges
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, Apartado Postal 70228, Ciudad Universitaria 04510, México D.F., Mexico.
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Sitges M, Chiu LM, Guarneros A, Nekrassov V. Effects of carbamazepine, phenytoin, lamotrigine, oxcarbazepine, topiramate and vinpocetine on Na+ channel-mediated release of [3H]glutamate in hippocampal nerve endings. Neuropharmacology 2006; 52:598-605. [PMID: 17070874 DOI: 10.1016/j.neuropharm.2006.09.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 08/14/2006] [Accepted: 09/05/2006] [Indexed: 11/22/2022]
Abstract
Several of the most effective antiepileptic drugs are believed to stop the paroxysmal neuronal activity acting as Na(+) channel blockers. However, no single study comparing in parallel the potency and efficacy of the most commonly used antiepileptic drugs on brain Na(+) channel-mediated responses is available. In the present study the effects of increasing concentrations of carbamazepine, phenytoin, lamotrigine, oxcarbazepine and topiramate, which are among the most frequently used antiepileptic drugs, and of the new putative antiepileptic drug, vinpocetine, on the release of glutamate (Glu) elicited by the Na(+) channel opener, veratridine were investigated in hippocampal isolated nerve endings preloaded with the labeled excitatory amino acid neurotransmitter. The present results show that carbamazepine, phenytoin, lamotrigine and oxcarbazepine, in the range from 150 to 1500 microM, progressively inhibit [(3)H]Glu release induced by veratridine. Also vinpocetine progressively inhibits the veratridine-induced response, but in a much lower range of concentrations (from 1.5 to 15 microM), whereas topiramate only exerts a modest inhibition (20%) of Glu release to veratridine at the highest dose tested (1500 microM). These results indicate that the mechanism of action of several of the most widely used antiepileptic drugs involves reduction in cerebral presynaptic voltage sensitive Na(+) channels permeability. Considering that the high doses of antiepileptic drugs required to control seizures are frequently accompanied by adverse secondary effects, the higher potency of vinpocetine to reduce Na(+) channels permeability might be advantageous.
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Affiliation(s)
- María Sitges
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, Apartado Postal 70228, Ciudad Universitaria 04510, México D.F., Mexico.
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Costa J, Lobo MG, Correia-de-Sá P. Paradoxical nifedipine facilitation of 45Ca uptake into rat hippocampal synaptosomes. Eur J Pharmacol 2006; 544:39-48. [PMID: 16843457 DOI: 10.1016/j.ejphar.2006.06.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2005] [Revised: 05/23/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
Nifedipine has a high incidence of neurologic adverse reactions as compared with other dihydropyridine Cav1 (L-type) channel blockers used for treating cardiovascular diseases. The mechanism mediating neuronal excitation by nifedipine is still in debate. Nifedipine caused a dual role on veratridine-induced 45Ca uptake by rat hippocampal synaptosomes. In the nanomolar range (0.001-0.3 microM), nifedipine decreased 45Ca uptake in a cadmium-sensitive manner. In contrast with nitrendipine (0.001-10 microM), nifedipine consistently facilitated 45Ca accumulation when used in low micromolar concentrations (0.3-10 microM). The cadmium-insensitive nifedipine facilitation became less evident upon increasing veratridine concentration from 5 to 20 microM and was not detected when the synaptosomes where depolarised with 30 mM KCl. Na+ substitution by N-methyl-D-glucamine (132 mM) or blockade of Na+ currents with tetrodotoxin (1 microM) both prevented nifedipine excitation. The Na+/Ca2+-exchanger inhibitor, KB-R7943 (3-50 microM), did not reproduce nifedipine actions. Data suggest that tetrodotoxin-sensitive Na+ channels may operate paradoxical nifedipine facilitation of 45Ca uptake by rat hippocampal synaptosomes.
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Affiliation(s)
- Joana Costa
- Laboratório de Farmacologia/UMIB, Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, L. Prof. Abel Salazar, 2, 4099-003 Porto, Portugal
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Sitges M, Chiu LM, Nekrassov V. Single and combined effects of carbamazepine and vinpocetine on depolarization-induced changes in Na+, Ca2+ and glutamate release in hippocampal isolated nerve endings. Neurochem Int 2006; 49:55-61. [PMID: 16621162 DOI: 10.1016/j.neuint.2005.12.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Accepted: 12/21/2005] [Indexed: 11/22/2022]
Abstract
The single and combined effects of carbamazepine and vinpocetine on the release of the excitatory amino acid neurotransmitter glutamate, on the rise in internal Na+ (Na(i), as determined with SBFI), and on the rise in internal Ca2+ (Ca(i), as determined with fura-2) induced by an increased permeability of presynaptic Na+ channels, with veratridine, or by an increased permeability of presynaptic Ca2+ channels with high K+, were investigated in isolated hippocampal nerve endings. The present study shows that carbamazepine and vinpocetine, both inhibit dose dependently the release of preloaded [3H]Glu induced by veratridine. However, carbamazepine is two orders of magnitude less potent than vinpocetine. The calculated IC(50)'s for carbamazepine and vinpocetine to inhibit veratridine-induced [3H]Glu release are 200 and 2 microM, respectively. Consistently 150 microM carbamazepine and 1.5 microM vinpocetine reduce the veratridine-induced rise in Na(i) in a similar extent. The single effects of carbamazepine and of vinpocetine on the presynaptic Na+ channel mediated responses, namely the rise in Na(i) and the release of Glu induced by veratridine, are additive. Responses that depend on the entrance of external Ca2+ via presynaptic Ca2+ channels, such as the release of [3H]Glu and the rise in Ca(i) induced by high K+, are insensitive to 300 microM carbamazepine and slightly reduced by 5 microM vinpocetine. It is concluded that the additive effects of carbamazepine, which is one of the most common antiepileptic drugs, and vinpocetine that besides its known neuroprotective action and antiepileptic potential is a memory enhancer, may perhaps be advantageous in the treatment of epileptic patients.
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Affiliation(s)
- María Sitges
- Depto. de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, Apartado Postal 70228, Ciudad Univeresitaria, 04510 México D.F., Mexico.
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Zhen J, Chen N, Reith MEA. Differences in interactions with the dopamine transporter as revealed by diminishment of Na+ gradient and membrane potential: Dopamine versus other substrates. Neuropharmacology 2005; 49:769-79. [PMID: 16122767 DOI: 10.1016/j.neuropharm.2005.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Revised: 06/22/2005] [Accepted: 07/05/2005] [Indexed: 01/12/2023]
Abstract
In heterologous cells expressing the dopamine transporter (DAT), simultaneous elevation of intracellular Na(+) and depolarization of the membrane with gramicidin reduced the potency of various DAT substrates, including dopamine, d-amphetamine, beta-phenethylamine, p-tyramine, and MPP(+), in inhibiting binding of the cocaine analog [(3)H]CFT, with the greatest reduction observed for d-amphetamine. In rat striatal synaptosomes, gramicidin exerted similar effects; in addition, the potency of d-amphetamine was reduced by the Na(+)-channel activator veratridine. The latter effect was counteracted by the Na(+)-channel blocker tetrodotoxin. In broken membranes, where, as the situation with gramicidin, both sides of the non-polarized membrane were exposed to 130 mM Na(+), gramicidin was ineffective. Dopamine had a potency for membrane preparations that was not significantly different from that for control cells or synaptosomes, while other substrates had potencies for membrane preparations that were reduced to a level similar to those observed in gramicidin-treated cells or synaptosomes. These results suggest that diminishing Na(+) gradient and membrane potential may convert DAT to a conformational state that dopamine could easily bind to when gaining free access to its intracellular portion. In contrast, non-dopamine substrates may not be able to readily interact with this state from either side of the membrane.
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Affiliation(s)
- Juan Zhen
- Department of Biological Sciences, Illinois State University, Normal, IL, USA
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