2--hydroxy-5-9-dimethyl-2-allyl-6-7-benzomorphan and tenocyclidine

The ability of non-competitive NMDA antagonists and other selected compounds to inhibit [3H]MK-801 binding to the NMDA receptor in brain membranes was evaluated in female, dark Agouti rats. In homologous competition binding studies the average apparent affinity (KD) of [3H]MK-801 for its binding site was 5.5 nM and the binding site density (Bmax) was 1.83 pmol/mg protein. Inhibition of [3H]MK-801 binding by non-competitive NMDA antagonists was best described with a one-site competition model and the average Hill coefficients were -1. A series of eight non-competitive NMDA antagonists inhibited [3H]MK-801 binding with the following rank order of affinity (K(i), nM): MK-801 (5.5) > dexoxadrol (21.5) > or = TCP (24.2) > phencyclidine (100.8) > (+)-SKF 10,047 (357.7) > dextrorphan (405.2) > ketamine (922.2) > dextromethorphan (2913). These inhibition binding constants determined in dark Agouti rat brain membranes were significantly correlated (P = 0.0002; r2 = 0.95) with previously reported values determined in Sprague-Dawley rats [Wong et al., 1988, J. Neurochem. 50, 274-281]. Despite significant differences in metabolic capability between these strains, the central nervous system NMDA receptor ion channel shares similar characteristics.

Topics: Animals; Binding, Competitive; Brain; Dextromethorphan; Dioxolanes; Dizocilpine Maleate; Dose-Response Relationship, Drug; Female; Ketamine; N-Methylaspartate; Phenazocine; Phencyclidine; Piperidines; Rats; Rats, Mutant Strains; Receptors, N-Methyl-D-Aspartate; Scintillation Counting; Tritium

High-affinity binding sites (apparent KD 2.87 nM) for [3H]desmethylimipramine ([3H]DMI), have been demonstrated and characterized in membrane preparations of bovine adrenal medulla. The binding of [3H]DMI improved upon pretreatment of the membrane with KCl and was saturable, sodium dependent, and potently inhibited by nisoxetine and imipramine. [3H]DMI binding was also inhibited by various phencyclidine (PCP)- and (or) sigma-receptor ligands, with the following order of potency: haloperidol > rimcazole > (-)-butaclamol > dextromethorphan > MK-801 > (+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ((+)-3-PPP) > PCP > N-(2-thienyl)cyclohexyl-3,4-piperidine (TCP) > (+)-SKF-10047 > (-)-SKF-10047. The inhibition produced by sigma ligands was not attributed to stimulation of either sigma 1- or sigma 2-receptors, owing to inactivity of the selective sigma-receptor ligands (+)-pentazocine and 1,3-di(2-tolyl)guanidine (DTG). The inhibition of [3H]DMI binding by sigma- and PCP-receptor ligands was not attributed to PCP1- or PCP2-receptor stimulation, owing to the decreased potency (100-fold) of these ligands in [3H]DMI assays compared with the affinity for brain PCP1 sites, and the ineffectiveness of the PCP2-ligand N-(1-(2-benzo(b)thiophenyl)cyclohexyl)piperidine (BTCP). Scatchard analysis of the inhibition by the sigma-ligands haloperidol and (+)-3-PPP, as well as the PCP1 receptor ligand MK-801, demonstrated noncompetitive interaction with the site bound by [3H]DMI. These studies indicate that bovine adrenomedullary membranes possess a specific receptor for the noradrenaline uptake inhibitor [3H]DMI, which is sensitive to allosteric modulation produced by PCP and sigma-ligands.

Topics: Adrenal Medulla; Animals; Binding Sites; Cattle; Desipramine; Dextromethorphan; Dizocilpine Maleate; Phenazocine; Phencyclidine; Piperidines; Potassium Chloride; Receptors, Opioid, delta; Receptors, Phencyclidine; Tranquilizing Agents

Several arylcyclohexylamines and opioid benzomorphans that bind to phencyclidine (PCP) receptors were studied for their effects on punished and unpunished responding maintained under fixed-interval schedules of food presentation. All of these drugs increased both punished and unpunished responding, although higher doses decreased responding. The order of potency for increasing punished responding was MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzoa(a,d)-cyclohepten-5,1 0-imine] greater than [1-[1-(2-thienyl)cyclohexyl]piperidine] = PCP greater than (+)-N-allylnormetazocine = (-)-N-allynormetazocine. There was a high correlation (0.95) between the relative potency of these drugs in increasing punished responding and their relative affinity for PCP receptors. Because some of these drugs also bind to sigma receptors, drugs with a high affinity for sigma receptors, such as haloperidol, BD 737 [1S,2R-(-)-cis-N-[2-(3,4-dichlorophenyl)ethyl]-N- methyl-2-(1-pyrrolidinyl) cyclohexylamine] and (+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine, were also studied for their effects on punished and unpunished responding. These drugs produced only rate-decreasing effects. The correlation between the relative potency of drugs in increasing punished responding and their relative affinity for sigma receptors was low (-0.19). These data suggest that the PCP receptor is involved in some drug-induced increases in punished responding.

Topics: Animals; Buspirone; Dizocilpine Maleate; Haloperidol; Learning; Male; Pentobarbital; Phenazocine; Phencyclidine; Punishment; Rats; Rats, Inbred Strains; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Phencyclidine; Receptors, sigma

Quantitative ligand binding studies have been used to characterize binding sites for N-allylnormetazocine ((+)SKF10,047) (SKF), 1-(1-phenylcyclohexyl) piperidine (PCP), N-[1-(2-thienyl)cyclohexyl]piperidine (TCP) and haloperidol in membranes from the brain of rat and guinea pig under conditions which permitted simultaneous analysis of the binding of both PCP and SKF. Using four labelled ligands (SKF, TCP, PCP and haloperidol), each displaced by the corresponding four unlabelled ligands, four classes of binding sites were observed in membranes from the brain of the rat, corresponding to sigma (sigma), two classes of PCP sites (PCP1, PCP2) and dopamine (D2) sites. The sigma site was suppressed by 50 nM haloperidol, while the PCP1 and PCP2 sites were not. These results were confirmed by studies employing a self- and cross-displacement design and dose-response surfaces for SKF and TCP, with and without blockade by haloperidol of the sigma site. Using mathematical modelling, employing the program LIGAND, it was possible to reject simpler models involving a common "PCP/sigma" site or a model involving only two classes of sites (sigma and PCP). Similar methods were used to identify two classes of sigma binding sites and two classes of PCP binding sites, in membranes prepared from the brain of the guinea pig. The relative potencies of 18 ligands for displacement of (+)[3H]SKF10,047 and [3H]TCP were compared: there were significant qualitative and quantitative differences in the "sigma" binding sites in the brain of rat and guinea pig, while the PCP binding sites were very similar in the two species.

Topics: Animals; Binding Sites; Brain; Cell Membrane; Guinea Pigs; Male; Phenazocine; Phencyclidine; Psychotropic Drugs; Radioligand Assay; Rats; Rats, Inbred Strains; Receptors, Opioid; Receptors, sigma

JO 1784 ((+)-cinnamyl-1-phenyl-1-N-methyl-N-cyclopropylene) is a potent ligand for (+)-[3H]SKF 10,047 (2'-hydroxy-5,9-dimethyl-2-allyl-6,7-benzomorphan) binding sites in rat brain membrane preparations with an IC50 of 39 +/- 8 nM, which is comparable to that of haloperidol. The stereoisomer of JO 1784 is ten fold less potent. When administered to mice i.p. or p.o. JO 1784 displaced (+)-[3H]SKF 10,047 (5 muCi i.v.) from its sites in the brain with ID50 values of 1.2 and 3.5 mg kg-1, respectively. The high selectivity of JO 1784 for the sigma-binding site was assessed by its lack of significant affinity for more than 20 other sites including those for phencyclidine.

Topics: Animals; Brain Chemistry; Cinnamates; Cyclopropanes; In Vitro Techniques; Male; Mice; Phenazocine; Phencyclidine; Rats; Rats, Inbred Strains; Receptors, Opioid; Receptors, Opioid, delta

Homogenates from guinea pig vas deferens were examined for possible existence of sigma receptor and phencyclidine (PCP) receptor using a radioligand binding assay. [3H](+)-SKF-10047 bound saturably in the homogenates to a single population of binding sites with a Kd of 311 and a Bmax of 1090 fmol/mg protein. IC50S of several representative sigma in displacing [3H](+)-SKF-10047 from this binding site were very much similar to the IC50S of those drugs in the brain sigma receptor binding assay. A correlation coefficient of 0.96 was obtained when IC50S from vas deferens were compared with those from the brain assay. Attempts to demonstrate PCP receptors in this tissue using [3H]TCP (N-[1-(2-thienyl)cyclohexyl]piperidine), however, yielded negative results. The results indicate that while guinea pig vas deferens contains sigma receptors, PCP receptors may be absent in this tissue.

Topics: Animals; Binding, Competitive; Guinea Pigs; Male; Phenazocine; Phencyclidine; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Phencyclidine; Receptors, sigma; Vas Deferens

A series of 1,2,3,4-tetrahydroisoquinolines, tetrahydrothieno[2,3-c]pyridines, and related compounds were evaluated for their ability to inhibit binding of [3H]-1-[1-(2-thienyl)piperidine and [3H]-N-allylnormetazocine to phencyclidine (PCP) and sigma receptors, respectively. A representative series of compounds was evaluated in behavioral assays to determine the ability of the compounds to induce PCP-like stereotyped behavior and ataxia. All of the compounds caused stereotyped behavior and ataxia, indicating their agonist actions at the PCP site.

Topics: Animals; Ataxia; Behavior, Animal; Chemical Phenomena; Chemistry; Isoquinolines; Male; Molecular Structure; Phenazocine; Phencyclidine; Rats; Rats, Inbred Strains; Receptors, Neurotransmitter; Receptors, Phencyclidine; Stereotyped Behavior; Structure-Activity Relationship; Tetrahydroisoquinolines

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)

Topics: Animals; Anticonvulsants; Aspartic Acid; Behavior, Animal; Binding, Competitive; Dibenzocycloheptenes; Discrimination Learning; Dizocilpine Maleate; Dose-Response Relationship, Drug; Ketamine; Male; Motor Activity; N-Methylaspartate; Phenazocine; Phencyclidine; Rats; Rats, Inbred Strains; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Seizures

The experiments on male albino rats have shown that 15 days haloperidol (0.5 mg/kg) and raclopride (1 mg/kg) treatment, but not acute administration, causes the increase of density of sigma receptors in the brain. The number of phencyclidine receptors was also elevated, but this increase was not statistically evident. The behavioral effects of ketamine (5 mg/kg) were evidently decreased after long-term haloperidol and raclopride treatment. The motor stimulation and stereotyped behavior induced by apomorphine (0.15 mg/kg) were increased only after treatment of haloperidol, but not raclopride. It seems probable that repeated neuroleptic (haloperidol and raclopride) treatment causes the hyposensitivity of sigma and phencyclidine receptors, despite the increase of their number. It is possible that this change is related to the depolarization inactivation of dopamine neurons caused by repeated neuroleptic administration.

Topics: Adaptation, Physiological; Animals; Apomorphine; Behavior, Animal; Drug Interactions; Haloperidol; Ketamine; Phenazocine; Phencyclidine; Raclopride; Rats; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Phencyclidine; Receptors, sigma; Salicylamides; Time Factors; Tritium

Topics: Animals; Brain Chemistry; Haloperidol; In Vitro Techniques; Male; Neuropeptide Y; Pentazocine; Peptide YY; Peptides; Phenazocine; Phencyclidine; Rats; Rats, Inbred Strains; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Phencyclidine; Receptors, sigma

The potent noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist [3H]MK-801 bound with nanomolar affinity to rat brain membranes in a reversible, saturable, and stereospecific manner. The affinity of [3H]MK-801 was considerably higher in 5 mM Tris-HCl (pH 7.4) than in previous studies using Krebs-Henseleit buffer. [3H]MK-801 labels a homogeneous population of sites in rat cerebral cortical membranes with KD of 6.3 nM and Bmax of 2.37 pmol/mg of protein. This binding was unevenly distributed among brain regions, with hippocampus greater than cortex greater than olfactory bulb = striatum greater than medulla-pons, and the cerebellum failing to show significant binding. Detailed pharmacological characterization indicated [3H]MK-801 binding to a site which was competitively and potently inhibited by known noncompetitive NMDA receptor antagonists, such as phencyclidine, thienylcyclohexylpiperidine (TCP), ketamine, N-allylnormetazocine (SKF 10,047), cyclazocine, and etoxadrol, a specificity similar to sites labelled by [3H]TCP. These sites were distinct from the high-affinity sites labelled by the sigma receptor ligand (+)-[3H]SKF 10,047. [3H]MK-801 binding was allosterically modulated by the endogenous NMDA receptor antagonist Mg2+ and by other active divalent cations. These data suggest that [3H]MK-801 labels a high-affinity site on the NMDA receptor channel complex, distinct from the NMDA recognition site, which is responsible for the blocking action of MK-801 and other noncompetitive NMDA receptor antagonists.

Topics: Animals; Anticonvulsants; Brain; Cations, Divalent; Cell Membrane; Cerebral Cortex; Dibenzocycloheptenes; Dizocilpine Maleate; Kinetics; Male; Phenazocine; Phencyclidine; Rats; Rats, Inbred Strains; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Tissue Distribution; Tritium

Opioid, sigma, and phencyclidine (PCP) receptors were characterized in the mouse neuroblastoma--Chinese hamster brain hybrid cell line NCB-20. Quantitative receptor assays under equilibrium binding conditions with highly specific radioligands demonstrated the presence of delta, but not mu or kappa, opioid receptors on NCB-20 cell membranes. NCB-20 cells were shown to possess two distinct sites specific for sigma opioids and PCP derivatives. One site was labeled by (+)-[3H]N-allylnormetazocine [(+)-[3H]SKF-10,047] (Kd = 69 nM; Bmax = 4100 fmol/mg of protein). The rank order of potency of drugs at this site was (+)-3-(3-hydroxy-phenyl)-N-(1-propyl)piperidine [(+)-3-PPP] greater than haloperidol greater than (+)-SKF-10,047 greater than (+/-)-ethylketocyclazocine greater than (+/-)-bremazocine greater than N-[1-(2-thienyl) cyclohexyl]piperidine (TCP) greater than dexoxadrol. This site is similar in its ligand selectivity to the haloperidol-sensitive sigma receptor of rat brain. The other site was labeled by the potent phencyclidine derivative [3H]TCP (Kd = 335 nM; Bmax = 9300 fmol/mg of protein). This density is equivalent to approximately 60,000 sites/cell. The rank order of potency of drugs at this site was TCP greater than (+)-3-PPP greater than PCP greater than dexoxadrol greater than haloperidol greater than cyclazocine greater than levoxadrol greater than (+)-SKF-10,047; mu and delta ligands were inactive. This site is similar to the rat brain PCP receptor. The NCB-20 cell line is the only cultured cell line that has been demonstrated to have PCP receptors.

Topics: Animals; Brain Chemistry; Cell Line; Cricetinae; Hybrid Cells; Kinetics; Mice; Neuroblastoma; Phenazocine; Phencyclidine; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Phencyclidine; Receptors, sigma

Biochemical and electrophysiological studies have provided evidence that a complex comprising the N-methyl-D-aspartate (NMDA)-type excitatory amino acid (EAA) receptor and the phencyclidine (PCP) recognition site exists in mammalian brain. This complex, which has been compared to that established for the inhibitory amino acid, gamma-aminobutyric acid, and the benzodiazepine anxiolytic, diazepam, is sensitive to the effects of the divalent cation Mg2+, which has suggested the presence of a third, ion channel component. Using a radioreceptor assay for the PCP receptor, L-glutamate (L-Glu) produced a concentration-dependent increase in the binding of [3H]thienyl cyclohexylpiperazine ([3H]TCP) in well washed membranes from rat forebrain. The EAA produced a maximal increase in specific binding of 400%, with an EC50 value of 340 nM. The ability of L-Glu to enhance [3H]TCP binding was 10-fold more potent in the presence of 30 microM Mg2+, which inhibits NMDA-evoked responses in intact tissue preparations and produces a 50% increase in [3H]TCP binding on its own. Analysis of saturation curves indicated that the effect of both L-Glu and Mg2+ could be attributed to an increase in receptor affinity as well as increases in the proportion of a high affinity state of the PCP-binding site. Assessment of the effect of a number of EAAs on basal [3H]TCP binding (well washed membranes in the absence of either L-Glu or Mg2+) showed that the EAA recognition site involved in the effects of L-Glu was the NMDA subtype. Further studies examined a series of compounds thought to interact with either the NMDA or PCP components of the receptor complex under four binding conditions: basal, +Mg2+; +L-Glu; and +Mg2+/L-Glu. These results showed that dissociative anesthetics, such as dexoxadrol and PCP, as well as the novel anticonvulsant MK-801, selectively interact with the high affinity state of the PCP receptor. NMDA antagonists, such as CPP, were also found to inhibit binding to the high affinity state of the PCP receptor, although not as potently as the dissociative anesthetics. Interestingly, the NMDA antagonists did not inhibit any of the binding to the low affinity state of the receptor. The sigma ligands (+/-)-SKF 10,047 and haloperidol recognized two components of [3H]TCP binding only in the presence of L-Glu. The results of the present study are consistent with the finding that agonists of the NMDA receptor induce a high affinity state of the PCP receptor.

Topics: Animals; Brain; Glutamates; Glutamic Acid; In Vitro Techniques; Kinetics; Magnesium; Male; Phenazocine; Phencyclidine; Rats; Rats, Inbred Strains; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Receptors, Phencyclidine

The benzomorphan opioid, SKF 10,047, is the prototypical agonist for the sigma receptor. In this study, pharmacological and autoradiographic analyses reveal that (+)-[3H]SKF 10,047 labels two sites in brain: a high affinity site resembling the sigma receptor and a second site, labeled with lower affinity by (+)-[3H] SKF 10,047, similar to the phencyclidine (PCP) receptor. The drug specificity of the high affinity site for (+)-[3H]SKF 10,047 resembles that of the putative sigma receptor labeled with (+)-[3H]-3-[3-hydroxyphenyl]-N-(1-propyl)piperidine [(+)-[3H]-3-PPP], being potently inhibited by (+)-3-PPP, haloperidol and (+/-)-pentazocine, and demonstrating stereoselectivity for the (+)-isomer of SKF 10,047. In contrast, these drugs are weak in inhibiting binding of (+)-[3H]SKF 10,047 to the low affinity site, whereas PCP analogs, such as 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) and 1-[1-(m-aminophenyl)cyclohexyl]piperidine (m-NH2-PCP), are potent inhibitors. No stereoselectivity for the isomers of SKF 10,047 is noted at the low affinity binding site. Autoradiographic localizations of high affinity (+)-[3H]SKF 10,047 binding sites closely resemble those of (+)-[3H]-3-PPP labeled sites with high levels of binding in the hippocampal pyramidal cell layer, hypothalamus, pontine and cranial nerve nuclei and cerebellum. By contrast, low affinity (+)-[3H]SKF 10,047 sites are most abundant in nonpyramidal layers of the hippocampus, the cerebral cortex and thalamic nuclei, similar to the distribution of [3H]TCP labeled PCP receptors.

Topics: Animals; Autoradiography; Binding, Competitive; Brain Chemistry; In Vitro Techniques; Kinetics; Male; Phenazocine; Phencyclidine; Piperidines; Radioligand Assay; Rats; Rats, Inbred Strains; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Phencyclidine; Receptors, sigma; Stereoisomerism

Topics: Autoradiography; Brain; Humans; In Vitro Techniques; Membranes; Phenazocine; Phencyclidine; Piperidines; Receptors, Neurotransmitter; Receptors, Opioid; Receptors, Opioid, delta; Receptors, Phencyclidine