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Lodge D, Mercier MS. Ketamine and phencyclidine: the good, the bad and the unexpected. Br J Pharmacol 2015; 172:4254-76. [PMID: 26075331 DOI: 10.1111/bph.13222] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 12/21/2022] Open
Abstract
The history of ketamine and phencyclidine from their development as potential clinical anaesthetics through drugs of abuse and animal models of schizophrenia to potential rapidly acting antidepressants is reviewed. The discovery in 1983 of the NMDA receptor antagonist property of ketamine and phencyclidine was a key step to understanding their pharmacology, including their psychotomimetic effects in man. This review describes the historical context and the course of that discovery and its expansion into other hallucinatory drugs. The relevance of these findings to modern hypotheses of schizophrenia and the implications for drug discovery are reviewed. The findings of the rapidly acting antidepressant effects of ketamine in man are discussed in relation to other glutamatergic mechanisms.
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Affiliation(s)
- D Lodge
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - M S Mercier
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, Bristol, UK
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Kozlowski DA, Schallert T. Relationship between dendritic pruning and behavioral recovery following sensorimotor cortex lesions. Behav Brain Res 1998; 97:89-98. [PMID: 9867234 DOI: 10.1016/s0166-4328(98)00030-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A unilateral injury to the forelimb area of the sensorimotor cortex results in an increase in dendritic arborization in the contralateral homotopic cortex which is followed by a pruning back of these dendritic arbors. The increase in arborization is due to an increase in the use of the unimpaired forelimb for postural-motor support; whereas, the dendritic pruning is related, in time, to the return to more symmetrical limb use, but is not prevented by the maintenance of asymmetrical limb use. Dendritic pruning can be prevented by administering an NMDA receptor antagonist (such as MK801 or ethanol) during the pruning phase. This manipulation also coincides with the chronic reinstatement of behavioral deficits. The purpose of this study was to see whether removing the antagonism of the NMDA receptor results in the eventual return of dendritic pruning and behavioral recovery. Therefore, MK801 was administered to lesioned animals starting at post-lesion day 18. One group received MK801 injections until day 60 (Lesion + MK60) and another lesioned group received MK801 until day 30 after which the injections were changed to saline until day 60 (Lesion + MK30). Lesion + MK60 animals showed a prevention of dendritic pruning as well as a chronic reinstatement of forelimb deficits. Lesion + MK30 animals also showed a prevention of dendritic pruning, however, they showed behavioral recovery. These findings suggest that pruning of dendritic arbors may not be directly related to behavioral recovery.
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Affiliation(s)
- D A Kozlowski
- Department of Psychology and Institute for Neuroscience, University of Texas at Austin, 78712, USA.
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Are N-methyl-d-aspartate (NMDA) and phencyclidine (PCP) receptors always functionally coupled to each other? Neurochem Int 1990; 17:1-8. [DOI: 10.1016/0197-0186(90)90060-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/1989] [Accepted: 01/23/1990] [Indexed: 11/19/2022]
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Rogawski MA, Pieniek M, Suzuki S, ffrench-Mullen JM. Phencyclidine selectively blocks the sustained voltage-dependent potassium conductance in PC12 cells. Brain Res 1988; 456:38-48. [PMID: 2457411 DOI: 10.1016/0006-8993(88)90344-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We investigated the effects of phencyclidine (PCP), a psychotomimetic dissociative anesthetic, and several related drugs on voltage-dependent K+ currents in PC12 cells, a neuron-like clonal cell line derived from a rat pheochromocytoma. Whole-cell voltage clamp recordings demonstrated two kinetically distinct voltage-dependent outward (K+) current components in these cells: a rapidly activating and inactivating component, IA, that was selectively eliminated by 4-aminopyridine (2 mM) and a slowly activating, minimally inactivating (sustained) component, IK, that was specifically blocked by tetraethylammonium (20 mM). PCP (1-100 microM) produced a dose-dependent blockade of both IK and IA, however, at low doses the drug selectively reduced IK with little effect on IA; the IC50s for blockade of IK and IA were 4 and 25 microM, respectively. The blockade of IK was voltage-dependent so that the degree of block decreased with increasing depolarization, indicating that the blocking mechanism is likely one in which the positively charged PCP molecule is drawn into the channel pore. Several PCP related drugs also suppressed IK. Thienyl-PCP (TCP), a drug that is behaviorally more potent than PCP, partially blocked IK at low doses (31% at 1 microM), but even at high doses (25 microM) the degree of block was never as great as that produced by PCP. The optically active PCP congeners (+)-PCMP (1-(1-phenylcyclohexyl)-3-methyl-piperidine) and dexoxadrol were also potent blockers of IK. However, in contrast to the stereospecificity these compounds demonstrate in binding to high-affinity PCP receptors and in eliciting PCP-like behavioral responses, their enantiomers (-)-PCMP and levoxadrol showed similar potencies as the parent compounds in blocking IK. These results demonstrate that PCP and related drugs are powerful, selective blockers of IK in PC12 cells. The structure-activity studies indicate that this effect occurs at a site that is pharmacologically distinct from the behaviorally relevant PCP receptor. Blockade of K+ channels is unlikely to be responsible for the psychotomimetic or anti-convulsant properties of PCP, but could account for the convulsant potential of the drug.
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Affiliation(s)
- M A Rogawski
- Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, MD 20892
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Leander JD, Lawson RR, Ornstein PL, Zimmerman DM. N-methyl-D-aspartic acid-induced lethality in mice: selective antagonism by phencyclidine-like drugs. Brain Res 1988; 448:115-20. [PMID: 3292008 DOI: 10.1016/0006-8993(88)91107-9] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
N-Methyl-D-aspartic acid (NMDA) produced a dose-related increase in lethality in mice, with 200 mg/kg (i.p.) effecting 100% lethality. Upon daily dosing, acutely sublethal doses of NMDA produced deaths. This NMDA-induced lethality was stereoselective; N-methyl-L-aspartic acid had no effects at doses as high as 400 mg/kg. Moderate doses of phencyclidine (PCP) and drugs having PCP-like behavioral effects blocked the NMDA-induced lethality. Other classes of psychoactive drugs, including opioids, anticonvulsants and antipsychotics, were ineffective in preventing NMDA-induced lethality. The potency of PCP-like drugs to block the NMDA-induced lethality correlates highly with the dose necessary to produce PCP-like catalepsy and PCP-like discrimination in pigeons. These data support the hypothesis that PCP-like drugs produce many of their effects by impairing the normal functioning of the NMDA-defined excitatory neurotransmitter receptor in the central nervous system.
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Affiliation(s)
- J D Leander
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285
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Contreras PC, Monahan JB, Lanthorn TH, Pullan LM, DiMaggio DA, Handelmann GE, Gray NM, O’Donohue TL. Phencyclidine. Mol Neurobiol 1988. [DOI: 10.1007/978-1-4612-4604-6_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Contreras PC, Monahan JB, Lanthorn TH, Pullan LM, DiMaggio DA, Handelmann GE, Gray NM, O'Donohue TL. Phencyclidine. Physiological actions, interactions with excitatory amino acids and endogenous ligands. Mol Neurobiol 1987; 1:191-211. [PMID: 2855791 DOI: 10.1007/bf02936608] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Phenycyclidine (PCP) produces many profound effects in the central nervous system. PCP has numerous behavioral and neurochemical effects such as inhibiting the uptake and facilitating the release of dopamine, serotonin, and norepinephrine. PCP also interacts with sigma, mu opioid, muscarinic, and nicotinic receptors. However, the psychotomimetic effects induced by PCP are believed to be mediated by specific PCP receptors, where PCP binds with greater potency than sigma compounds. Electrophysiological, behavioral, and neuro-chemical evidence strongly suggests that at least some of the many PCP actions result from antagonism of excitatory amino acid-induced responses via PCP receptors. The recent isolation and partial characterization of the alpha and beta endopsychosins and the identification of other endogenous ligands for the PCP and sigma receptors, is another promising area of research in the elucidation of the physiological role of an endogenous PCP and sigma system.
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Affiliation(s)
- P C Contreras
- Central Nervous Systems Research, G.D. Searle & Co., Chesterfield, MO 63198
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Gundlach AL, Largent BL, Snyder SH. Phencyclidine (PCP) receptors: autoradiographic localization in brain with the selective ligand, [3H]TCP. Brain Res 1986; 386:266-79. [PMID: 3022881 DOI: 10.1016/0006-8993(86)90163-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Receptor binding sites for the phencyclidine (PCP) analogue, [3H]TCP, have been localized in the rat and guinea pig central nervous systems by in vitro autoradiography. Quantitation of [3H]TCP binding site densities in rat brain reveals highest levels in the forebrain, in particular the strata oriens and radiatum of the hippocampus, the molecular layer of the dentate gyrus and superficial layers of the cerebral cortex. Moderate levels of binding occur in the amygdala, thalamus, anterior olfactory nucleus, external plexiform layer of the olfactory bulb, olfactory tubercle, geniculate nuclei and deep layers of the cortex. Low levels of binding occur throughout most of the septum, diagonal band, hypothalamus, pons-medulla and cerebellum. Spinal cord grey matter also has low levels of binding. Excitotoxin lesions of the hippocampal formation, which destroy the pyramidal and granule cells, reduce the binding of [3H]TCP to strata radiatum and oriens and the molecular layer of the dentate gyrus by 60% suggesting that [3H]TCP labels intrinsic neurons in these regions. Residual binding is probably on afferent terminals. Ibotenic acid lesions of the caudate-putamen reduce [3H]TCP binding by 70%, indicating that binding sites are localized on intrinsic striatal neurons. 6-Hydroxydopamine lesions do not alter [3H]TCP binding levels in the caudate, suggesting the absence of binding sites on dopaminergic terminals in the caudate.
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Abstract
Intracellular recordings were made from neurones in the rat locus coeruleus in a brain slice maintained in vitro. Phencyclidine and related psychotomimetic drugs, applied in known concentrations in the fluid bathing the slice, depressed responses to N-methyl-D-aspartic acid noradrenaline (in the presence of the uptake inhibitor desmethylimipramine) and [D-Ala2,MePhe4,Gly-ol5]enkephalin and also prolonged the action potential. The sensitivities of these responses to depression by phencyclidine was N-methyl-D-aspartic acid (IC50 0.4 microM) greater than noradrenaline (IC50 3.9 microM) greater than [D-Ala2,MePhe4,Gly-ol5]enkephalin (IC50 8.5 microM) greater than prolongation of the action potential (41% increase by 30 microM). Stereoselectivity was observed only in the depression of responses to N-methyl-D-aspartic acid where (+)-1-(1-phenylcyclohexyl)-3-methyl piperidine was 3.3-fold more potent in suppressing N-methyl-D-aspartic acid depolarizations than its (-) isomer. The responses to N-methyl-D-aspartic acid were also depressed by the structurally unrelated psychotomimetic (+/-)-N-allyl-N-normetazocine (IC50 0.9 microM). All of the effects of the psychotomimetic drugs examined were slow in onset and difficult to reverse following washout. No effect of phencyclidine (0.03-100 microM) or related drugs was observed on membrane potential, input resistance or spontaneous action potential firing rate of locus coeruleus neurones. The depression of responses to N-methyl-D-aspartic acid by phencyclidine was the most potent and the only stereoselective effect of those studied. The importance of this effect and of those not showing stereoselectivity in relation to the phencyclidine behavioural syndrome is discussed.
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Berry SC, Dawkins SL, Lodge D. Comparison of sigma- and kappa-opiate receptor ligands as excitatory amino acid antagonists. Br J Pharmacol 1984; 83:179-85. [PMID: 6091823 PMCID: PMC1987176 DOI: 10.1111/j.1476-5381.1984.tb10133.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Using the technique of microelectrophoresis in pentobarbitone-anaesthetized cats and rats, the effects of benzomorphans, with known actions at sigma- and kappa- opioid receptors, were tested on responses of spinal neurones to amino acids and acetylcholine. The racemic mixture and both enantiomers of the sigma opiate receptor agonist, N-allylnormetazocine (SKF 10, 047), and the dissociative anaesthetic, ketamine, reduced or abolished excitation evoked by N-methyl-aspartate (NMA) with only small and variable effects on responses to quisqualate or kainate. (+)-SKF 10, 047 was 1.2 +/- 0.7 times more potent than the (-)-enantiomer in antagonizing NMA. On Renshaw cells, (+)-SKF 10, 047 enhanced responses to acetylcholine whereas the (-) enantiomer produced only a small reduction. The kappa- opiate receptor agonist, ethylketocyclazocine, had no selective effects on responses to amino acids or to acetylcholine. We conclude that actions at sigma- but not kappa-, opiate receptors are responsible for the NMA antagonism observed with benzomorphans.
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Berry SC, Anis NA, Lodge D. The effect of the dioxolanes on amino acid induced excitation in the mammalian spinal cord. Brain Res 1984; 307:85-90. [PMID: 6147179 DOI: 10.1016/0006-8993(84)90463-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The effects of the dissociative anaesthetic, etoxadrol, and the stereoisomers of dioxadrol, dexoxadrol and levoxadrol, were examined on the excitation of spinal neurones by electrophoretically administered amino acids in pentobarbitone- or urethane-anaesthetized rats, or pentobarbitone-anaesthetized cats. Both etoxadrol and the (+)isomer of dioxadrol, dexoxadrol, administered locally or systemically, exhibited a selective antagonism of N-methyl-D,L-aspartate relative to quisqualate and kainate. This selective antagonism was not observed with the (-)isomer of dioxadrol, levoxadrol. Since such a stereoselective antagonism of the excitation of spinal neurones by N-methyl-D,L-aspartate is also displayed by the dissociative anaesthetics phencyclidine and ketamine, it is suggested that a reduced efficiency at excitatory synapses utilising N-methyl-D,L-aspartate receptors contributes to that part of the pharmacological spectrum common to both arylcyclohexylamines and dioxolanes.
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