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Kang M, An JR, Li H, Zhuang W, Heo R, Park S, Mun SY, Park M, Seo MS, Han ET, Han JH, Chun W, Park WS. Blockade of voltage-dependent K+ channels by benztropine, a muscarinic acetylcholine receptor inhibitor, in coronary arterial smooth muscle cells. Toxicol Sci 2022; 189:260-267. [PMID: 35944222 DOI: 10.1093/toxsci/kfac083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We investigated the effect of the acetylcholine muscarinic receptor inhibitor benztropine on voltage-dependent K+ (Kv) channels in rabbit coronary arterial smooth muscle cells. Benztropine inhibited Kv currents in a concentration-dependent manner, with an apparent IC50 value of 6.11 ± 0.80 μM and Hill coefficient of 0.62 ± 0.03. Benztropine shifted the steady-state activation curves toward a more positive potential, and the steady-state inactivation curves toward a more negative potential, suggesting that benztropine inhibited Kv channels by affecting the channel voltage sensor. Train pulse (1 or 2 Hz)-induced Kv currents were effectively reduced by the benztropine treatment. Furthermore, recovery time constants of Kv current inactivation increased significantly in response to benztropine. These results suggest that benztropine inhibited vascular Kv channels in a use (state)-dependent manner. The inhibitory effect of benztropine was canceled by pretreatment with the Kv 1.5 inhibitor, but there was no obvious change after pretreatment with Kv 2.1 or Kv7 inhibitors. In conclusion, benztropine inhibited the Kv current in a concentration- and use (state)-dependent manner. Inhibition of the Kv channels by benztropine primarily involved the Kv1.5 subtype. Restrictions are required when using benztropine to patients with vascular disease.
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Affiliation(s)
- Minji Kang
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Hongliang Li
- Institute of Translational Medicine, Medical College, Jiangsu Key laboratory of integrated traditional Chinese and Western Medicine for prevention and treatment of Senile Diseases, Yangzhou University, Yangzhou, 225001, PR China
| | - Wenwen Zhuang
- Institute of Translational Medicine, Medical College, Jiangsu Key laboratory of integrated traditional Chinese and Western Medicine for prevention and treatment of Senile Diseases, Yangzhou University, Yangzhou, 225001, PR China
| | - Ryeon Heo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Seojin Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Seo-Yeong Mun
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Minju Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Mi Seon Seo
- Department of Physiology, Konkuk University School of Medicine, Chungju, 27478, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Wanjoo Chun
- Department of Pharmacology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
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Uribe LA, Leonardo S, Nielsen TT, Steinmann C, Campàs M, Fragoso A. Supramolecular Complexes of Plant Neurotoxin Veratridine with Cyclodextrins and Their Antidote-like Effect on Neuro-2a Cell Viability. Pharmaceutics 2022; 14:pharmaceutics14030598. [PMID: 35335973 PMCID: PMC8951692 DOI: 10.3390/pharmaceutics14030598] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 01/27/2023] Open
Abstract
Veratridine (VTD) is a plant neurotoxin that acts by blocking the voltage-gated sodium channels (VGSC) of cell membranes. Symptoms of VTD intoxication include intense nausea, hypotension, arrhythmia, and loss of consciousness. The treatment for the intoxication is mainly focused on treating the symptoms, meaning there is no specific antidote against VTD. In this pursuit, we were interested in studying the molecular interactions of VTD with cyclodextrins (CDs). CDs are supramolecular macrocycles with the ability to form host–guest inclusion complexes (ICs) inside their hydrophobic cavity. Since VTD is a lipid-soluble alkaloid, we hypothesized that it could form stable inclusion complexes with different types of CDs, resulting in changes to its physicochemical properties. In this investigation, we studied the interaction of VTD with β-CD, γ-CD and sulfobutyl ether β-CD (SBCD) by isothermal titration calorimetry (ITC) and nuclear magnetic resonance (NMR) spectroscopy. Docking and molecular dynamics studies confirmed the most stable configuration for the inclusion complexes. Finally, with an interest in understanding the effects of the VTD/CD molecular interactions, we performed cell-based assays (CBAs) on Neuro-2a cells. Our findings reveal that the use of different amounts of CDs has an antidote-like concentration-dependent effect on the cells, significantly increasing cell viability and thus opening opportunities for novel research on applications of CDs and VTD.
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Affiliation(s)
- Laura A. Uribe
- Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain;
| | - Sandra Leonardo
- IRTA, Carretera Poble Nou km 5.5, 43540 Sant Carles de la Ràpita, Spain; (S.L.); (M.C.)
| | - Thorbjørn Terndrup Nielsen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark; (T.T.N.); (C.S.)
| | - Casper Steinmann
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark; (T.T.N.); (C.S.)
| | - Mònica Campàs
- IRTA, Carretera Poble Nou km 5.5, 43540 Sant Carles de la Ràpita, Spain; (S.L.); (M.C.)
| | - Alex Fragoso
- Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain;
- Correspondence:
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Shibuta S, Varathan S, Mashimo T. Ketamine and thiopental sodium: individual and combined neuroprotective effects on cortical cultures exposed to NMDA or nitric oxide. Br J Anaesth 2006; 97:517-24. [PMID: 16928698 DOI: 10.1093/bja/ael192] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND An N-methyl-D-aspartate (NMDA) blocker, ketamine, has been shown to be neuroprotective both in vivo and in vitro. However, ketamine is not commonly recommended for use in patients suffering from cerebral ischaemia because of its adverse neurological effects. We hypothesized that combined administration of ketamine and thiopental sodium (TPS) would be highly effective in protecting cerebral cortical neurones from ischaemia, with possibly reduced dosages. METHODS We examined the degree of neuroprotection provided by various concentrations of ketamine and TPS, alone and in combination, in cortical cultures exposed to NMDA or a nitric oxide-releasing compound (NOC-5) for 24 h. The survival rate (SR) of E16 Wistar rat cortical neurones was evaluated using photomicrographs before and after exposure to these compounds. RESULTS The SRs of cortical neurones exposed to 30 microM NMDA or NOC-5 were 15.0 (3.8)%, 12.8 (3.1)%, respectively. Higher doses (5, 10 and 50 microM) but not lower doses (<1 microM) of ketamine improved SRs [57.9 (2.2)%, 61.1 (5.4)%, 76.7 (3.0)%, respectively] against NMDA but not NOC. Enhanced survival was observed with combined administration of 5 or 10 microM ketamine and 50 microM TPS [SR 71.3 (4.8)%, 74.7 (3.7)%, respectively, P<0.05 if ketamine alone, P<0.01 if TPS alone], against NMDA-induced neurotoxicity in vitro. Only the highest dose of TPS (50 microM) improved survival after NOC exposure. This neuroprotection was not influenced by ketamine. CONCLUSIONS These data indicate that a low, clinically relevant dose of ketamine offer significant neuroprotection during prolonged exposure to NMDA but not to NOC. Combinations of reduced doses of ketamine and TPS exhibited enhanced neuroprotection against NMDA-induced neurotoxicity. Hence, combinations of these two common i.v. anaesthetics agents could be developed to protect the brain from ischaemia.
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Affiliation(s)
- S Shibuta
- Department of Anaesthesiology and Intensive Care Medicine, Graduate School of Medicine D7, Osaka University 2-2, Yamadaoka, Suita 565-0871, Japan.
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Lingamaneni R, Hemmings HC. Differential interaction of anaesthetics and antiepileptic drugs with neuronal Na+ channels, Ca2+ channels, and GABA(A) receptors. Br J Anaesth 2003; 90:199-211. [PMID: 12538378 DOI: 10.1093/bja/aeg040] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Current theories favour multiple agent-specific neuronal actions for both general anaesthetics and antiepileptic drugs, but the pharmacological properties that distinguish them are poorly understood. We compared the interactions of representative agents from each class on their putative targets using well-characterized radioligand binding assays. METHODS Synaptosomes or membranes prepared from rat cerebral cortex were used to analyse drug effects on [(35)S]t-butyl bicyclophosphorothionate ([(35)S]TBPS) binding to the picrotoxinin site of GABA(A) receptors, [(3)H]batrachotoxinin A 20-alpha benzoate ([(3)H]BTX-B) binding to site 2 of voltage-gated Na(+) channels, (+)-[methyl-(3)H]isopropyl 4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-5-methoxycarboxyl-2,6-dimethyl-3-pyridinecarboxylate ([(3)H]PN200-110; isradipine) binding to L-type Ca(2+) channels, and [cyclohexyl-2,3-(3)H](N)glibenclamide ([(3)H]GB) binding to K(ATP) channels. RESULTS I.V. anaesthetics other than ketamine preferentially inhibited [(35)S]TBPS binding (etomidate approximately equal alphaxalone > propofol > thiopental > pentobarbital). Volatile anaesthetics inhibited both [(35)S]TBPS and [(3)H]BTX-B binding with comparable potencies (halothane approximately equal isoflurane approximately equal enflurane). Antiepileptic drugs preferentially antagonized either [(35)S]TBPS (diazepam > phenobarbital) or [(3)H]BTX-B (phenytoin > carbamazepine) binding. Local anaesthetics (lidocaine, tertracaine) selectively antagonized [(3)H]BTX-B binding. None of the drugs tested were potent antagonists of [(3)H]PN200-110 or [(3)H]GB binding. CONCLUSIONS Comparative radioligand binding assays identified distinct classes of general anaesthetic and antiepileptic drugs based on their relative specificities for a defined target set. I.V. anaesthetics interacted preferentially with GABA(A) receptors, while volatile anaesthetics were essentially equipotent at Na(+) channels and GABA(A) receptors. Antiepileptic drugs could be classified by preferential actions at either Na(+) channels or GABA(A) receptors. Anaesthetics and antiepileptic drugs have agent-specific effects on radioligand binding. Both general anaesthetics and antiepileptic drugs interact with Na(+) channels and GABA(A) receptors at therapeutic concentrations, in most cases with little selectivity.
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Affiliation(s)
- R Lingamaneni
- Department of Anesthesiology, Box 50, LC-203A, Weill Medical College of Cornell University, 525 East 68th Street, New York, NY 10021, USA
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Chen YF, Lin YT, Tan TW, Tsai HY. Effects of veratrine and paeoniflorin on isolated mouse vas deferens. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2002; 9:296-301. [PMID: 12120810 DOI: 10.1078/0944-7113-00122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this study, we attempted to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated mouse vas deferens. Paeoniflorin had no effect on isolated mouse vas deferens. Veratrine (1 x 10(-5) approximately 1 x 10(-3) g/ml) could directly induce contraction of isolated rat and mouse vas deferens. The concentration induced by veratrine (1 x 10(-5) g/ml) was completely inhibited by Ca2+-free solution and verapamil (1 x 10(-5) M), in both the epididymal and the prostatic portions of isolated mouse vas deferens. Naloxone (1 x 10(-5) M) did not alter the contraction induced by veratrine (1 x 10(-5) g/ml) in either the epididymal or the prostatic portions of isolated mouse vas deferens. Paeoniflorin (4.8 x 10(-5) g/ml) inhibited the contraction induced by veratrine (1 x 10(-5) g/ml) in both the epididymal and the prostatic portions of isolated mouse vas deferens. Paeoniflorin (4.8 x 10(-5) g/ml) potentiated norepinephrine (1 x 10(-5) M)-induced phasic contraction in the epididymal portion, but decreased contractions in the prostatic portion. Paeoniflorin (4.8 x 10(-5) g/ml) increased KCI (56 mM)-induced phasic contraction in the epididymal portion, but decreased the tonic contraction in either the epididymal or the prostatic portion. Veratrine (1 x 10(-5) g/ml)-induced contractions could be decreased by pretreatment with ryanodine (1 x 10(-5) M) in both the epididymal and the prostatic portions. Pretreatment with the combination of paeoniflorin (4.8 x 10(-5) g/ml) and ryanodine (1 x 10(-5) M) did not potentiate the inhibition of paeoniflorin in the veratrine-induced contraction in both the epididymal and the prostatic portions of isolated mouse vas deferens.
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Affiliation(s)
- Y F Chen
- Department of Pharmacology and Institute of Pharmaceutical Sciences, China Medical College, Taichung, Taiwan, ROC
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Spandou E, Karkavelas G, Soubasi V, Avgovstides-Savvopoulou P, Loizidis T, Guiba-Tziampiri O. Effect of ketamine on hypoxic-ischemic brain damage in newborn rats. Brain Res 1999; 819:1-7. [PMID: 10082854 DOI: 10.1016/s0006-8993(98)01333-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The present study tests the hypothesis that ketamine, a dissociative anesthetic known to be a non-competitive antagonist of the NMDA receptor, will attenuate hypoxic-ischemic damage in neonatal rat brain. Studies were performed in 7-day-old rat pups which were divided into four groups. Animals of the first group, neither ligated nor exposed to hypoxia, served as controls. The second group was exposed to hypoxic-ischemic conditions and sacrificed immediately afterwards. Animals of the third and fourth groups were treated either with saline or ketamine (20 mg/kg, i.p.) in four doses following hypoxia. Hypoxic-ischemic injury to the left cerebral hemisphere was induced by ligation of the left common carotid artery followed by 1 h of hypoxia with 8% oxygen. Measurements of high energy phosphates (ATP and phosphocreatine) and amino acids (glutamate and glutamine) and neuropathological evaluation of the hippocampal formation were used to assess the effects of hypoxia-ischemia. The combination of common carotid artery ligation and exposure to an hypoxic environment caused major alterations in the ipsilateral hemisphere. In contrast, minor alterations in amino acid concentrations were observed after the end of hypoxia in the contralateral hemisphere. These alterations were restored during the early recovery period. Post-treatment with ketamine was associated with partial restoration of energy stores and amino acid content of the left cerebral hemisphere. Limited attenuation of the damage to the hippocampal formation as demonstrated by a reduction in the number of damaged neurons was also observed. These findings demonstrate that systemically administered ketamine after hypoxia offers partial protection to the newborn rat brain against hypoxic-ischemic injury.
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Affiliation(s)
- E Spandou
- Department of Physiology and Pharmacology, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
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7
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Curti D, Izzo E, Brambilla L, Facchetti G, Sangiovanni G, Brambilla G. Effect of a ubiquinone-like molecule on oxidative energy metabolism in rat cortical synaptosomes at different ages. Neurochem Res 1995; 20:1001-6. [PMID: 8570002 DOI: 10.1007/bf00995552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Persistent stimulation of energy consumption, induced by depolarization with veratridine, mimics a condition of abnormally enhanced energy demand and causes an increase in the oxygen consumption rate (QO2) and in the interconversion of pyruvate dehydrogenase complex (PDHc) into its active form. Wistar rats at the age of 26 months do not show alterations of QO2 and the ability of veratridine to increase QO2 in comparison with 6 month-old animals whereas the active form of PDHc is slightly but significantly reduced. Idebenone, a ubiquinone-like molecule (1 microM), does not affect the QO2 or PDHc activation state in resting conditions but attenuates the veratridine-challenged increase in QO2 at all the ages tested and attenuates the increase in the percentage of PDHa reaching statistical significance in 26-month-old rats. At higher concentration (10 microM) idebenone totally abolishes the veratridine-induced increase in PDHa also in the 6 month-old rats. At the lower concentration, the drug does not affect the increase in QO2 induced by an uncoupler of oxidative phosphorylation. The results obtained suggest a protective effect of idebenone on the cerebral tissue against stressful conditions; this action may be exerted at the level of some mitochondrial component and/or on the Na+ homeostasis.
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Affiliation(s)
- D Curti
- Institute of Pharmacology, Faculty of Sciences, University of Pavia, Italy
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8
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Abstract
We investigated the neuroprotective effect of the noncompetitive N-methyl-D-asparatate (NMDA) antagonist ketamine when administered after onset of lithium-pilocarpine-induced status epilepticus (SE). Seizures were induced in Wistar rats with lithium chloride (3 mEq/kg) and pilocarpine (PC) (30-60 mg/kg intraperitoneally, i.p.). Fifteen minutes after SE onset, either ketamine 100 mg/kg or normal saline was injected i.p., and 3 h after SE onset atropine, diazepam (DZP), and phenobarbital (PB) were administered i.p. to terminate the seizures. Twenty-four hours later, rats underwent brain perfusion-fixation, with subsequent brain processing for light-microscopic examination. Rats adminstered saline (n = 5) had neuronal damage in 24 of 25 brain regions examined. Rats administered ketamine (n = 7) had significant neuroprotection in 22 of 24 damaged regions. Ketamine reduced the amplitude of seizure discharges, and in 3 rats EEG seizure activity ceased in 30 min; none of these rats had neuronal damage. In the other 4 rats, EEG seizure discharges persisted > 90 min; in these animals, 21 of 24 damaged regions were protected. In contrast, rats with 1-h high-dose PC-induced SE (400 mg/kg i.p. without lithium chloride preadministration) had 14 damaged regions, of which 7 were significantly different from the undamaged regions of the ketamine subgroup with persistent electrographic seizures. Thus, ketamine is remarkably neuroprotective when administered after onset of SE, whether or not seizure discharges are eliminated.
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Affiliation(s)
- D G Fujikawa
- Experimental Neurology Laboratory, Sepulveda VA Medical Center, CA 91343
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10
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Fujikawa DG, Daniels AH, Kim JS. The competitive NMDA receptor antagonist CGP 40116 protects against status epilepticus-induced neuronal damage. Epilepsy Res 1994; 17:207-19. [PMID: 7912191 DOI: 10.1016/0920-1211(94)90051-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We studied the efficacy of the competitive NMDA receptor antagonist CGP 40116 in protecting against seizure-induced neuronal necrosis from lithium-pilocarpine-induced status epilepticus (SE). Rats were given CGP 40116 either before SE (12 mg/kg i.p.) or 15 min after the onset of SE (4, 12 and 24 mg/kg); controls received normal saline 15 min after SE began. Diazepam and phenobarbital were given i.p. after 3 h of SE to stop the seizures. Rats were killed 24 h later, and their brains were processed for light microscopic examination. Neuronal damage occurred in 24 of 25 brain regions examined in saline-injected animals. Protection was maximal in rats given 12 and 24 mg/kg CGP 40116 after SE onset: 19 and 21 of the 24 damaged regions were protected respectively, but the 24 mg/kg group had a mortality rate comparable to saline-injected controls. No necrotic neurons were found in posterior cingulate and retrosplenial neurons at the two highest CGP 40116 doses, suggesting that the transient cytoplasmic vacuolization induced by NMDA receptor antagonists does not progress to frank necrosis. In rats given CGP 40116 seizure discharges were not eliminated, but their amplitudes were significantly reduced 2 h after SE began. The periodic epileptiform discharge (PED) EEG pattern, probably a sign of widespread neuronal damage, developed in saline-injected controls after 2-2.5 h of SE but not in rats given 12 and 24 mg/kg of CGP 40116. CGP 40116 provided widespread protection against seizure-induced neuronal necrosis, suggesting that an essential step in its production is NMDA receptor activation by endogenous glutamate. The neuroprotection provided was not simply an antiepileptic effect, since electrographic seizures persisted despite NMDA receptor blockade. CGP 40116 and NMDA receptor antagonists in general could be useful as adjunctive neuroprotectants in patients with refractory SE.
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Affiliation(s)
- D G Fujikawa
- Experimental Neurology Laboratory, Sepulveda VA Medical Center, CA 91343
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Giladi N, Sutton M, Lo B, Przedborski S, Fahn S, Cadet JL. Toxicity of the specific antimuscarinic agent methoctramine and other non-specific anticholinergic drugs in human neuroblastoma cell lines in vitro. Toxicol In Vitro 1993; 7:595-603. [PMID: 20732256 DOI: 10.1016/0887-2333(93)90093-k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/1992] [Revised: 03/22/1993] [Indexed: 10/27/2022]
Abstract
The highly selective cardiac-M(2) muscarinic acetylcholine receptor (mAChR) antagonist methoctramine shows a number of concentration-dependent biochemical responses. At micromolar concentrations it interacts allosterically with the mAChR and has 'agonist-like' effects on the phosphoinositide and cyclic AMP second messenger systems. Direct stimulation or inhibition of second messenger systems has been reported to modulate cellular homoeostasis and differentiation. This study showed that methoctramine was toxic, in micromolar concentrations, to the human neuroblastoma cell lines SK-N-SH, LAN-5 and SH-EP1, the last being a clone that does not contain muscarinic receptors. The selective M2 mAChR antagonists 11-{2-[(diethylamino)methyl]-1-piperidinyl}-5,11-dihydro-6H-pyrido(2,3-6)(1-4)benzodiazepine-6-on (AF-DX 116) and gallamine, as well as the selective M1 and M3 antagonists pirenzepine and 4-diphenylacetoxy-n-methylpiperidine (4-DAMP), had no toxic effects. Lithium provided significant protection against methoctramine toxicity, whereas carbamylcholine, pertussis toxin and forskolin had no influence on its toxicity. At micromolar concentrations, the clinically used, non-selective mAChR antagonists ethopropazine, benztropine, trihexyphenidyl and orphenadrine displayed toxicity similar to that of methoctramine. Methoctramine, ethopropazine, benztropine and trihexyphenidyl enhanced significantly [(3)H]thymidine uptake at subtoxic concentrations. These results demonstrate that (a) the toxicity of methoctramine is by way of non-muscarinic mechanism, (b) some anticholinergic drugs commonly used in clinical medicine have toxic properties similar to those of methoctramine and (c) at subtoxic micromolar concentrations anti-muscarinic drugs have some trophic properties.
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Affiliation(s)
- N Giladi
- Department of Neurology, Laboratory of Preclinical Neuroscience, Black Building, Room 310, Columbia University College of Physicians & Surgeons, 630 West 168th Street, New York, NY 10032, USA
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12
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Iredale PA, Martin KF, Hill SJ, Kendall DA. The control of intracellular calcium and neurotransmitter release in guinea pig-derived cerebral cortical synaptoneurosomes. Biochem Pharmacol 1993; 45:407-14. [PMID: 8094616 DOI: 10.1016/0006-2952(93)90077-a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Synaptoneurosomes are a simply derived brain vesicular preparation which are believed to contain elements of both presynaptic and postsynaptic material. Inositol phosphates production and neurotransmitter release in the synaptoneurosome have previously been shown to be under the control of a number of receptor agonists. However, there have been few investigations of the role of intracellular calcium ([Ca2+]i) in these events. In this study we report that potassium (K+; 50 mM) was able to increase [Ca2+]i and subsequently release [3H]noradrenaline in guinea pig cerebral cortical synaptoneurosomes via activation of dihydropyridine-insensitive, voltage-sensitive calcium channels. Veratridine (30 microM) produced similar effects but these involved activation of sodium channels which could be blocked by pre-incubation with tetrodotoxin (0.15 microM). A number of agonists were used to investigate possible modulation of these events and to look for agonist-stimulated mobilization of [Ca2+]i. No evidence was found for either receptor-mediated release of calcium from intracellular stores or for modulation of K(+)-induced neurotransmitter release. This might be related to the observed passive entry of calcium through the synaptoneurosomal membrane and the subsequently high levels of [Ca2+]i.
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Affiliation(s)
- P A Iredale
- Department of Physiology and Pharmacology, Medical School, Queen's Medical Centre, Nottingham, U.K
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13
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Keilhoff G, Wolf G, Stastný F. Effects of MK-801, ketamine and alaptide on quinolinate models in the maturing hippocampus. Neuroscience 1991; 42:379-85. [PMID: 1832751 DOI: 10.1016/0306-4522(91)90382-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The ability of the N-methyl-D-aspartate receptor antagonists, MK-801, ketamine and alaptide [a newly synthesized cyclo(1-amino-1-cyclopentane-carbonyl-L-alanyl) with protective properties in models of hypoxia], to prevent neuronal degeneration caused by intracerebroventricular application of quinolinic acid was investigated. Neurodegenerative effects of quinolinate in the hippocampal formation were found to increase with the degree of maturity of glutamatergic target structures. A protective potency of the N-methyl-D-aspartate receptor antagonists was observed at all developmental stages studied (12- and 30-day-old and adult rats). MK-801 showed the highest efficacy, alaptide the lowest. These findings suggest a parallelism in maturity of glutamatergic transmission processes as one prerequisite of quinolinate vulnerability and postnatal increases of target fields of the protectives. Application of MK-801 or ketamine after quinolinate injection intensified their protective effects when compared to simultaneous or preadministration. This observation is interpreted as indicating that quinolinate is a prompter of a delayed neurodegenerative process rather than acting immediately as a toxicant.
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Affiliation(s)
- G Keilhoff
- Institute of Biology, Medical Academy of Magdeburg, Germany
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14
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Curti D, Crociani F, G. B. Pyruvate dehydrogenase interconversion in cerebral cortex nerve endings: Effect of ketamine. Pharmacol Res 1990. [DOI: 10.1016/s1043-6618(09)80186-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Biziagos E, Crance JM, Passagot J, Deloince R. Inhibitory effects of atropine, protamine, and their combination on hepatitis A virus replication in PLC/PRF/5 cells. Antimicrob Agents Chemother 1990; 34:1112-7. [PMID: 2168143 PMCID: PMC171767 DOI: 10.1128/aac.34.6.1112] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Atropine, protamine, and the combination of these drugs were tested for their effects on hepatitis A virus (HAV) replication in cell culture. PLC/PRF/5 hepatoma cells were treated simultaneously with nontoxic concentrations of these drugs and inoculated with HAV strain CF 53 at several multiplicities of infection. The yields of infectious HAV after 4 and 15 days were markedly reduced by each drug, especially at the lowest multiplicity of infection. The activities of each drug were irreversible. Atropine was active when it was added as late as 2 h after inoculation with HAV. An anti-HAV effect was also induced by treating cells with atropine prior to inoculation. Protamine was active as late as 6 h postinoculation. The combination of atropine and protamine resulted in an enhanced anti-HAV effect. We concluded that these drugs affect undetermined, but separate, steps in the HAV replication cycle.
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Affiliation(s)
- E Biziagos
- Département de Biologie Cellulaire, Centre de Recherches du Service de Santé des Armées, La Tronche, France
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Dagani F, Feletti F, Canevari L. Effects of diltiazem on bioenergetics, K+ gradients, and free cytosolic Ca2+ levels in rat brain synaptosomes submitted to energy metabolism inhibition and depolarization. J Neurochem 1989; 53:1379-89. [PMID: 2795006 DOI: 10.1111/j.1471-4159.1989.tb08528.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Diltiazem was able to decrease the oxygen consumption rate and lactate production in synaptosomes isolated from rat forebrains, both under control and depolarized (40 microM veratridine) conditions, starting from a concentration of 250 microM. This effect was particularly evident when synaptosomes were depolarized by veratridine. This depolarization-counteracting action was evident also when transplasma membrane K+ diffusion potentials were measured after depolarization induced by veratridine and by rotenone with a glucose shortage. The concentrations of ATP, phosphocreatine, and creatine were less sensitive to diltiazem action. The concentration/response relationships were the same as those found for the oxygen consumption were the same as those found for the oxygen consumption rate, lactate production, and K+ diffusion potentials. The effects of 0.5 mM diltiazem in counteracting inhibition of energy metabolism induced by rotenone without glucose were no longer detectable when either Ca2+ or Na+ was absent from the incubation medium of synaptosomes. Diltiazem at the same concentrations (starting from 250 microM) was able to inhibit both the veratridine-induced and the rotenone-without-glucose-induced increase in intrasynaptosomal free Ca2+ levels evaluated with the fluorescent probe quin2. The results are discussed in view of a possible effect of diltiazem on voltage-dependent Na+ channels and the possibility of utilizing this approach for counteracting neuronal failure due to derangement of energy metabolism or hyperexcitation.
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Affiliation(s)
- F Dagani
- Institute of Pharmacology, Faculty of Science, University of Pavia, Italy
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