National Institute on Drug Abuse RESEARCH MONOGRAPH SERIES Sigma, PCP, and NMDA Receptors 133 U.S. Department of Health and Human Services • Public Health Service • National Institutes of Health Sigma, PCP, and NMDA Receptors Editors: Errol B. De Souza, Ph.D. Addiction Research Center National Institute on Drug Abuse Doris Clouet, Ph.D. Division of Basic Research National Institute on Drug Abuse Edythe D. London, Ph.D. Addiction Research Center National Institute on Drug Abuse Research Monograph 133 1993 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Substance Abuse and Mental Health Services Administration National Institute on Drug Abuse 5600 Fishers Lane Rockville, MD 20857 ACKNOWLEDGMENT This monograph is based on the papers and discussions from a technical review on “Sigma, PCP, and NMDA Receptors Systems” held on September 27-28, 1989, in Baltimore, MD. The review meeting was sponsored by the National Institute on Drug Abuse. COPYRIGHT STATUS The National Institute on Drug Abuse has obtained permission from the copyright holders to reproduce certain previously published material as noted in the text. Further reproduction of this copyrighted material is permitted only as part of a reprinting of the entire publication or chapter. For any other use, the copyright holder’s permission is required. All other material in this volume except quoted passages from copyrighted sources is in the public domain and may be used or reproduced without permission from the Institute or the authors. Citation of the source is appreciated. Opinions expressed in this volume are those of the authors and do not necessarily reflect the opinions or official policy of the National Institute on Drug Abuse or any other part of the Department of Health and Human Services. The U.S. Government does not endorse or favor any specific commercial product or company. Trade, proprietary, or company names appearing in this publication are used only because they are considered essential in the context of the studies reported herein. NIDA Research Monographs are indexed in the Index Medicus. They are selectively included in the coverage of American Statistics Index, BioSciences lnformation Service, Chemical Abstracts, Current Contents, Psychological Abstracts, and Psychopharmacology Abstracts. National Institute on Drug Abuse NIH Publication No. 93-3587 Printed 1993 ii Contents Phencyclidine Receptor Binding as a Probe of NMDA Receptor Functioning: Implications for Drug Abuse Research 1 Stephen R. Zukin and Daniel C. Javitt Pharmacologic Regulation of the NMDA Receptor-lonophore Complex 13 Kenneth M. Johnson, Lawrence D. Snell, Aida I. Sacaan, and Susan M. Jones Pharmacologic Characterizations of Receptors 41 Tsung-Ping Su Studies of Receptors and Metabolic Responses to Ligands in the Brain 55 E. D. London Receptors and Signal Transduction: Negative Modulation of Signaling Through Phosphoinositide-Linked Receptor Systems 69 Wayne D. Bowen, Paul J. Tolentino, Brian N. Kirschner, Paul Varghese, Brian R. de Costa, and Kenner C. Rice and Phencyclidine Receptors in the Brain-Endocrine-Immune Axis 95 Seth A. Wolfe, Jr., and Errol B. De Souza iii A Role for Binding in the Antipsychotic Profile of BMY 14802? 125 Duncan P. Taylor, Michael S. Eison, Sandra L. Moon, R. Francis Schlemmer, Jr., Umesh A. Shukla, Cam P. VanderMaelen, Frank D. Yocca, Dennis J. Gallant, Susan H. Behling, Christopher G. Boissard, John P. Braselton, Houston H. Davis, Jr., Marlene N. Duquette, Raymond C. Lamy, Judith M. Libera, Elaine Ryan, and Robert N. Wright Molecular Biology of PCP and NMDA Receptors 159 Leslie Kushner, Michael V.L. Bennett, and R. Suzanne Zukin Excitatory Amino Acid Neurotoxicity in the Developing Brain 185 John W. McDonald and Michael V. Johnston Isolation and Characterization of an Endogenous Ligand for the PCP and Receptors From Porcine, Rat, and Human Tissue 207 Patricia C. Contreras, Nancy M. Gray, Debora A. DiMaggio, Margaret E. Bremer, and Julie A. Bussom Summary and Future Directions 223 Edward F. Domino iv Phencyclidine Receptor Binding as a Probe of NMDA Receptor Functioning: Implications for Drug Abuse Research Stephen R. Zukin and Daniel C. Javitt INTRODUCTION Phencyclidine (1 ,1-phenylcyclohexylpiperidine; PCP; “angel dust”), originally developed as a general anesthetic in the late 1950s was found to produce loss of consciousness and analgesia sufficient for the performance of surgical procedures while not causing significant respiratory or cardiovascular depression (Greifenstein et al. 1958; Meyer et al. 1959; Johnstone et al. 1958). However, a significant proportion of patients subjected to PCP anesthesia developed psychotic episodes typically lasting 12 to 72 hours but occasionally as long as 7 to 10 days. These episodes were characterized by excitation, unmanageability, paranoia, concreteness of thought (Greifenstein et al. 1958; Meyer et al. 1959), and “maniacal episodes” (Johnstone et al. 1958). Subanesthetic doses (0.1 mg/kg iv) were subsequently found to induce psychotic episodes in normal volunteers and to rekindle presenting symptomatology in recompensated schizophrenic subjects (Davies and Beech 1960; Luby et al. 1959, 1962). In addition, subanesthetic doses of PCP, but not lisergic acid diethylamide (LSD), amobarbital, or amphetamine, could induce abnormalities in tests of abstract reasoning, cognitive processing, attention, motor function, and proprioception in normal volunteers that closely resembled those seen in patients with chronic schizophrenia (Rosenbaum et al. 1959; Cohen et al. 1962; Domino and Luby 1981). Despite evoking behavioral effects apparently so dysphoric, PCP emerged as a major drug of abuse during the 1970s (Petersen and Stillman 1978), and the rate of PCP abuse increased again during the 1980s (Crider 1986). PCP possesses powerful reinforcing and abuse-promoting effects (Balster 1986). The key to developing interventions targeting the clinical and public-health 1 problems posed by PCP-like drugs will be found in elucidating the mechanisms underlying their psychotomimetic and abuse-promoting properties. PCP binds with high affinity to a specific brain PCP receptor (Zukin and Zukin 1979; Vincent et al. 1979; Reynolds et al. 1987). Several lines of evidence indicate that the PCP receptor is a site within the ion channel gated by the N-methyl-D-aspartate (NMDA)-type excitatory amino acid receptor. First, PCP and NMDA receptors are co-localized in the central nervous system (Maragos et al. 1988). Second, PCP receptor ligands have been shown to inhibit NMDA-receptor-mediated conductances noncompetitively (Anis et al. 1983) in a voltage- and use-dependent fashion (Honey et al. 1985; Huettner and Bean 1988). Finally, binding of PCP receptor ligands is enhanced by NMDA receptor agonists, such as L-glutamate or NMDA, and is diminished by competitive NMDA receptor antagonists, such as D(-)-2-amino-5-phosphonovaleric acid (D(-)AP5) (Javitt et al. 1987; Fagg 1987; Loo et al. 1987). Such data suggest a model in which NMDA and PCP receptors represent distinct sites associated with a supramolecular NMDA receptor complex. The identification of noncompetitive inhibition of NMDA receptor function as a possible mechanism underlying the psychotomimetic effects of PCP suggests that elucidation of the functioning of the NMDA receptor complex may reveal mechanisms relevant to the pathogenesis and treatment of schizophrenia. MECHANISMS OF PCP-NMDA RECEPTOR INTERACTION To shed light on the mechanisms underlying NMDA receptor activation, binding of the selective PCP receptor ligand [3H]MK-801 was determined in the presence and absence of L-glutamate and either glycine or D-serine, agents that had previously been shown to stimulate binding to PCP receptors (Reynolds et al. 1987; Javitt and Zukin 1989a). L-glutamate mediates its actions as an agonist at the NMDA recognition site, whereas both glycine and D-serine mediate their actions at a non-strychnine-sensitive glycine recognition site associated with the NMDA receptor complex. For these studies, rat forebrain homogenates were subjected to extensive washing, freezing, and thawing to reduce the high endogenous concentrations of L-glutamate and glycine present in crude brain homogenate. Specific binding of [3H]MK-801 was determined at 12 to 16 time points between 5 minutes and 24 hours using a filtration radioreceptor assay in the presence of a 5 mM Tris buffer system adjusted to pH 7.4 and a low (30 µM) concentration of Mg2+ (Javitt and Zukin 1989b). These studies produced three novel findings. First, analysis of association curves using a computer-assisted, nonlinear-curve-fitting technique revealed 2 FIGURE 1. Association curves of 1 nM [3H]MK-801 under control conditions (filled circles) or in the presence of 10 µM concentrations of D(-)AP5 (open circles), glycine (open triangles), L-glutamate (filled triangles), or L-glutamate plus glycine (open squares). Under control conditions or in the presence of D(-)APS, binding was fit best by single exponentials with apparent t1/2 values of 3.2 and 5.8 hours, respectively. In the presence of combined L-glutamate and glycine, binding was best fit by a single exponential with an apparent t1/2 of 12 minutes. In the presence of L-glutamate alone, binding was best fit by dual exponentials with apparent t1/2 values of 5.5 minutes and 1.6 hours for the fast (dashed line) and slow (dotted line) components, respectively. (Reprinted from Javitt and Zukin 1989b. Copyright 1989, American Society for Pharmacology and Experimental Therapeutics.) the