Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.16.2 (PCP)
3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the ability of an array of putative noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists to suppress convulsions induced by a unilateral, focal injection of (-)-bicuculline methiodide (118 pmol) into the rat prepiriform cortex. The anticonvulsant potency of these compounds, (+)-5-methyl-10,11- dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) greater than dextrorphan greater than or equal to 1-(1-phenylcyclohexyl)piperidine hydrochloride (PCP) greater than dextromethorphan greater than (+)-pentazocine, upon microinjection into the prepiriform cortex, was highly correlated (r = 0.971; P less than 0.01) with their respective affinities for the [3H]dextrorphan-labelled NMDA receptors in rat forebrain membranes. These results suggest that noncompetitive antagonism of NMDA receptors underlies the anticonvulsant action of these compounds.
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PMID:Dextrorotatory opioids and phencyclidine exert anticonvulsant action in prepiriform cortex. 132 6

Characteristics of muscarinic cholinergic (mACh), gamma-aminobutyric acid(A) (GABAA) and phencyclidine (PCP) receptors in the spontaneously epileptic rats (SER), which exhibit both absence-like seizures and tonic convulsion, were examined using in vitro quantitative autoradiography. Computer analysis using autoradiographic technique revealed that the amount of the specific binding of [3H]quinuclidinyl benzilate (QNB) to mACh receptors in the striatum of SER was more than that of zitter rats, not exhibiting both seizures and convulsion. However, the specific bindings of [3H]muscimol and [3H]N-(1-[2-thienyl]cyclohexyl)3,4-piperidine (TCP) to GABAA and PCP receptors, respectively, of SER were not different from those of zitter rats in various regions tested. These results suggest that hyperfunction of mACh receptors in the striatum is involved in the appearance of absence-like seizures and tonic convulsion of SER.
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PMID:Characteristics of muscarinic cholinergic, gamma-aminobutyric acid(A) and phencyclidine receptors in spontaneously epileptic rats; in vitro quantitative autoradiographic analysis. 166 11

The effects of the non-competitive N-methyl-D-aspartate (NMDA) antagonists, (+)-MK-801 hydrogen maleate (MK-801) and phencyclidine hydrochloride (PCP), were tested against hypoxia-induced tonic convulsions and hippocampal epileptiform discharges. Systemic administration of MK-801 and PCP suppressed the hypoxia-induced tonic convulsions in dietary Mg(2+)-deficient mice in a dose-dependent manner. The ED50 values (and their 95% confidence limits) of MK-801 and PCP were 0.19 (0.14-0.26) and 1.14 (0.32-4.11) mumol/kg, respectively. These values were lower than those of the conventional anticonvulsants tested. Induction of epileptiform discharges following hypoxia was also prevented by the presence of MK-801 and PCP at concentrations of 5-30 microM. The hypoxia-induced epileptiform discharges, however, were reduced, but not blocked completely, by the application of MK-801 and PCP. These results strongly suggest that activation of NMDA receptors in the hippocampus plays a pivotal role in the induction of hypoxia-induced tonic convulsions in dietary Mg(2+)-deficient mice.
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PMID:Inhibitory effects of NMDA receptor antagonists on hypoxia-induced seizures in dietary Mg(2+)-deficient mice. 183 34

1. Pretreatment were pancuronium prevented convulsions and hyperthermia, but had no effect on acidemia or changes in cardiovascular parameters after intravenous (i.v.) infusion of phencyclidine (PCP). 2. While dogs survived higher amounts of PCP, they failed to regain spontaneous respiratory function. 3. Mechanical ventilation alone increased the mean lethal dose/time of PCP and reduced the effects of PCP on arterial systolic pressure, cardiac output, and PCO2. 4. EKG showed ventricular arrhythmias, which progressed to death. 5. Phenytoin pretreatment plus respiratory assistance increased the lethal dose and reduced PCP effects on cardiovascular parameters, body temperature, and cardiac rhythm. 6. Blocking of convulsions prevented hyperthermia and acidemia; respiratory support reduced circulatory effects, but respired dogs then died, at higher doses, from a primary myocardial toxicity of PCP.
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PMID:Factors in the lethality of i.v. phencyclidine in conscious dogs. 193 8

The impairment of rotarod ability and the convulsive activity of phencyclidine (PCP) and MK-801 were compared in male CD-1 mice. The putative interaction between nifedipine and PCP and MK-801 on these behavioral measurements was also quantitated and compared. MK-801 produced a dose dependent inhibition of rotarod ability with an ED50 of 0.5 mg/kg. Nifedipine potentiated the impairment of rotarod ability by MK-801. Both PCP and MK-801 produced convulsive behavior in mice which was characterized by jumping and wild running fits; the CD50 for MK-801 was 1.3 mg/kg. Nifedipine dose dependently inhibited the convulsions associated with MK-801 and PCP. PCP but not MK-801 increased [3H]nitrendipine binding to dihydropyridine (DHP) binding sites on mouse brain membranes. MK-801 blocked the effects of PCP on [3H]nitrendipine binding. These findings suggest that MK-801 is a potent PCP-like drug which interacts with nifedipine and neuronal DHP binding sites. Nifedipine's reduction of the hyperactivity and convulsions elicited by MK-801 may be of importance in the eventual development of MK-801 as an antiischaemic and anticonvulsant drug.
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PMID:Phencyclidine and MK-801: a behavioral and neurochemical comparison of their interactions with dihydropyridine calcium antagonists. 254 45

The high pressure neurological syndrome (HPNS) occurs when man or animals are exposed to hyperbaric pressure. Four non-competitive N-methyl-D-aspartate (NMDA) antagonists - MK-801, phencyclidine (PCP), SKF 10,047 and ketamine were tested in rats for effects on the HPNS. All drugs were injected i.p. prior to compression; ketamine was also infused i.v. Control rats received saline. Rats were exposed individually to increasing helium pressure (PO2 0.5 atmospheres absolute ATA). Three endpoints were used to assess HPNS: onset pressures for tremor, myoclonus and convulsions. Neither MK-801 (0.03 and 0.3 mg/kg) nor SKF 10,047 (50 mg/kg) had any effect on the onset pressures for tremor, myoclonus or convulsions, although the type of seizure was modified from the clonic/tonic seizure seen in controls to purely clonic. PCP (5 mg/kg) had no effect on the endpoints, but pressure enhanced the excitation and stereotypy seen at 1 ATA. Ketamine (100 mg/kg i.p.) did not affect tremor or myoclonus; ketamine infused i.v. at pressure only prevented tremor and myoclonus at 'anaesthetizing' concentrations. Our results show that these non-competitive NMDA antagonists had little effect on HPNS, in contrast to competitive NMDA antagonists, such as AP7, which are highly effective. Possible explanations for this lack of effect include (1) interactions with NMDA receptor channels are pressure dependent; (2) other actions of these antagonists override their effects on the NMDA receptor channel.
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PMID:The effects of non-competitive NMDA receptor antagonists on rats exposed to hyperbaric pressure. 254 78

The selective non-competitive NMDA receptor antagonist, MK-801, potently blocked convulsions induced in the mouse by N-methyl-DL-aspartic acid (NMDLA) with an i.v. ED50 dose of 0.2 mg/kg. Similar doses of MK-801 were also effective in blocking seizures induced by pentylenetetrazol (PTZ), electroshock and by sound in audiogenic seizure-prone animals. Other less selective non-competitive NMDA receptor antagonists including phencyclidine (PCP), thienylcyclohexylpiperidine (TCP), (+)-N-allylnormetazocine [+)-NANM, (+)-SKF 10,047) and ketamine also blocked NMDLA-induced seizures with a rank order of potency of MK-801 greater than PCP greater than TCP = (+)-NANM greater than ketamine. The competitive NMDA receptor antagonist, 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) blocked NMDLA-induced seizures with an ED50 of 4.5 mg/kg, 22- and 560-fold more potently than the competitive antagonists, 2-DL-amino-7-phosphonoheptanoic acid (2-APH) and 2-DL-amino-5-phosphonovaleric acid (2-APV), respectively. MK-801 was the most potent of the non-competitive antagonists to induce a motor syndrome including head weaving, body rolling, increased locomotion and ataxia, characteristic of the behavioural response to PCP in the mouse. The syndrome was also present following injection of the competitive NMDA receptor antagonists, although they were generally less potent (probably a reflection of poor brain penetration) and less efficacious than the non-competitive antagonists. For all compounds except CPP, the anticonvulsant ED50 dose was close to the minimum effective dose to induce motor stimulation: CPP was 5- to 10-fold more potent as an anticonvulsant.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The behavioural effects of MK-801: a comparison with antagonists acting non-competitively and competitively at the NMDA receptor. 255 Feb 53

1. Convulsions were induced reproducibly by intracerebroventricular injection of N-methyl-D-aspartic acid (NMDA) to conscious mice. 2. Competitive (carboxypiperazine-propylphosphonic acid, CPP; 2-amino-7-phosphonoheptanoic acid, AP7) and non-competitive (MK801; phencyclidine, PCP; thienylcyclohexylpiperidine, TCP; dextrorphan; dextromethorphan) NMDA antagonists prevented NMDA-induced convulsions. 3. Benzodiazepine receptor agonists and partial agonists (triazolam, diazepam, clonazepam, Ro 16-6028), classical anticonvulsants (diphenylhydantoin, phenobarbitone, sodium valproate) and meprobamate were also found to prevent NMDA-induced convulsions. 4. Flumazenil (a benzodiazepine receptor antagonist) and the GABA agonists THIP and muscimol (up to subtoxic doses) were without effect. 5. Flumazenil reversed the anticonvulsant action of diazepam, but not that of MK801. 6. Results obtained in this model differ somewhat from those described in a seizure model with systemic administration of NMDA. An explanation for this discrepancy is offered. 7. This model is a simple test for assessing the in vivo activity of NMDA antagonists and also expands the battery of chemically-induced seizure models for characterizing anticonvulsants not acting at NMDA receptors.
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PMID:Convulsions induced by centrally administered NMDA in mice: effects of NMDA antagonists, benzodiazepines, minor tranquilizers and anticonvulsants. 257 61

Phencyclidine (PCP) inhibits dopamine (DA) uptake and acts as a noncompetitive N-methyl-D-aspartate antagonist by binding to PCP receptors. The PCP analog N-[1-(2-benzo(b)thiophenyl) cyclohexyl]piperidine (BTCP, GK13) is a potent DA uptake inhibitor, but has low affinity for PCP receptors. The behavioral effects of BTCP were compared with those of PCP, ketamine, MK-801 and cocaine. In mice, BTCP, like cocaine, produced locomotion, sniffing and gnawing; haloperidol blocked these effects. PCP, ketamine and MK-801 produced locomotion, sniffing, swaying and falling. PCP, ketamine and MK-801 produced generalization in rats discriminating either cocaine, PCP or MK-801 from saline. Like cocaine, BTCP produced generalization in cocaine-discriminating rats only; haloperidol partially antagonized this effect. In pigeons, PCP-like catalepsy was produced by ketamine and MK-801, but not by BTCP. N-methyl-D-aspartate-induced convulsions in mice were antagonized by PCP, ketamine and MK-801, but not by BTCP or cocaine. Thus, BTCP shared only cocaine-like behavioral effects with PCP, ketamine and MK-801. A DA antagonist reduced the effects of BTCP. Therefore, the cocaine-like behavioral effects of BTCP may be mediated primarily by DA uptake mechanisms. However, PCP receptors, but not DA uptake mechanisms, may mediate the cocaine-like behavioral effects of PCP, ketamine and MK-801, because their order of potency in producing these effects (MK-801 greater than PCP greater than ketamine) is consistent with their potency order at PCP receptors, but not at DA uptake sites.
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PMID:The phencyclidine (PCP) analog N-[1-(2-benzo(B)thiophenyl) cyclohexyl]piperidine shares cocaine-like but not other characteristic behavioral effects with PCP, ketamine and MK-801. 267 16

The effects of phencyclidine (PCP) on the threshold and intensity of caffeine-induced convulsions in rats were examined. There was a dose-dependent effect of PCP on convulsion intensity with significant reduction in intensity at 4.0 and 8.0 mg/kg PCP. At 16.0 mg/kg PCP, convulsant intensity was reduced in 50% of subjects but potentiated to the point of death in the remaining 50%. PCP had no significant effect on threshold for caffeine-induced convulsions. These results suggest that PCP antagonizes caffeine-induced convulsions and further suggests that the mechanisms involved in onset of caffeine-induced convulsions and the decrease of convulsion intensity are pharmacologically dissociable.
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PMID:Phencyclidine (PCP) reduces the intensity of caffeine-induced convulsions in rats. 273 42


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