piperidines and vanoxerine

HPC-1/syntaxin1A (STX1A), a neuronal soluble N-ethylmaleimide-sensitive fusion attachment protein receptor, contributes to neural function in the CNS by regulating transmitter release. Recent studies reported that STX1A is associated with human neuropsychological disorders, such as autism spectrum disorder and attention deficit hyperactivity disorder. Previously, we showed that STX1A null mutant mice (STX1A KO) exhibit neuropsychological abnormalities, such as fear memory deficits, attenuation of latent inhibition, and unusual social behavior. These observations suggested that STX1A may be involved in the neuropsychological basis of these abnormalities. Here, to study the neural basis of social behavior, we analyzed the profile of unusual social behavior in STX1A KO with a social novelty preference test, which is a useful method for quantification of social behavior. Interestingly, the unusual social behavior in STX1A KO was partially rescued by intracerebroventricular administration of oxytocin (OXT). In vivo microdialysis studies revealed that the extracellular OXT concentration in the CNS of STX1A KO was significantly lower compared with wild-type mice. Furthermore, dopamine-induced OXT release was reduced in STX1A KO. These results suggested that STX1A plays an important role in social behavior through regulation of the OXTergic neural system. Dopamine (DA) release is reduced in CNS of syntaxin1A null mutant mice (STX1A KO). Unusual social behavior was observed in STX1A KO. We found that oxytocin (OXT) release, which was stimulated by DA, was reduced and was rescued the unusual social behavior in STX1A KO was rescued by OXT. These results indicated that STX1A plays an important role in promoting social behavior through regulation of DA-induced OXT release in amygdala.

Topics: Amygdala; Analysis of Variance; Animals; Benzoxazines; Disease Models, Animal; Dopamine; Dopamine Uptake Inhibitors; Exploratory Behavior; Female; Gene Expression Regulation; Humans; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microdialysis; Ovariectomy; Oxytocin; Piperazines; Piperidines; Receptors, Oxytocin; Social Behavior Disorders; Syntaxin 1

Analogs of the flexible dopamine reuptake inhibitor, GBR 12909 (1), may have potential utility in the treatment of cocaine abuse. As a first step in the 3D-QSAR modeling of the dopamine transporter (DAT)/serotonin transporter (SERT) selectivity of these compounds, we carried out conformational analyses of two analogs of 1: a piperazine (2) and a related piperidine (3). Ensembles of conformers consisting of local minima on the potential energy surface of the molecule were generated in the vacuum phase and in implicit solvent by random search conformational analysis using the Tripos and MMFF94 force fields. Some differences were noted in the conformer populations due to differences in the treatment of the tertiary amine nitrogen and ether oxygen atom types by the force fields. The force fields also differed in their descriptions of internal rotation around the C(sp³)-O(sp³) bond proximal to the bisphenyl moiety. Molecular orbital calculations at the HF/6-31G(d) and B3LYP/6-31G(d) levels of C-O internal rotation in model compound (5), designed to model the effect of the proximity of the bisphenyl group on C-O internal rotation, showed a broad region of low energy between -60° to 60° with minima at both -60° and 30° and a low rotational barrier at 0°, in closer agreement with the MMFF94 results than the Tripos results. Molecular mechanics calculations on model compound (6) showed that the MMFF94 force field was much more sensitive than the Tripos force field to the effects of the bisphenyl moiety on C-O internal rotation.

Topics: Models, Chemical; Piperazine; Piperazines; Piperidines; Solvents

It is well known that amphetamine induces disrupted prepulse inhibition (PPI) in humans and rodents. We have previously reported that intracerebroventricular (i.c.v.) administration of p-hydroxyamphetamine (p-OHA) induces multiple behavioral responses, such as increased locomotor activity and head-twitch response in rodents. To reveal the characteristics of p-OHA on sensorimotor function in rodents, herein we tested the effects of p-OHA on PPI in mice. i.c.v. administration of p-OHA dose-dependently induced PPI disruptions for all prepulse intervals tested. This effect of p-OHA on PPI was attenuated by pretreatment with haloperidol or clozapine. p-OHA-induced PPI disruptions were also attenuated by pretreatment with L-741,626 (a selective D(2) receptor antagonist), L-745,870 (a selective D(4) receptor antagonist) or 6-hydroxydopamine (a neurotoxin which targets DA-containing neurons), but not by SCH 23390 (a selective D(1) receptor antagonist), eticlopride (a D(2)/D(3) receptor antagonist) or GBR 12909 (a DA-reuptake inhibitor). These results indicate that selective blockade of either the D(2) or D(4) receptor subtype may prevent disruption of PPI induced by p-OHA via presynaptic DA release.

Topics: Animals; Benzazepines; Clozapine; Dopamine; Dose-Response Relationship, Drug; Drug Interactions; Haloperidol; Indoles; Injections, Intraventricular; Male; Mice; Mice, Inbred Strains; Oxidopamine; p-Hydroxyamphetamine; Piperazines; Piperidines; Pyridines; Pyrroles; Reflex, Startle; Salicylamides; Sensory Gating; Sympathomimetics; Synaptic Transmission

Analysis of large, flexible molecules, such as the dopamine reuptake inhibitor GBR 12909 (1), is complicated by the fact that they can take on a wide range of closely related conformations. The first step in the analysis is to classify the conformers into groups. Here, Singular Value Decomposition (SVD) was used to group conformations of GBR 12909 analogs by the similarity of their nonring torsional angles. The significance of the present work, the first application of SVD to the analysis of very flexible molecules, lies in the development of a novel scaling technique for circular data and in the grouping of molecular conformations using a technique that is independent of molecular alignment. Over 700 conformers each of a piperazine (2) and piperidine (3) analog of 1 were studied. Analysis of the score and loading plots showed that the conformers of 2 separate into three large groups due to torsional angles on the naphthalene side of the molecule, whereas those of 3 separate into nine groups due to torsional angles on the bisphenyl side of the molecule. These differences are due to nitrogen inversion at the unprotonated piperazinyl nitrogen of 2, which results in a different ensemble of conformers than those of 3, where no inversion is possible at the corresponding piperidinyl carbon.

Topics: Computer Simulation; Dopamine Uptake Inhibitors; Molecular Structure; Piperazine; Piperazines; Piperidines

A series of 4-(2-(bis(4-fluorophenyl)methoxy)ethyl)-(substituted benzyl) piperidines with substituents at the ortho and meta positions in the aromatic ring of the N-benzyl side chain were synthesized and their affinities and selectivities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) were determined. One analogue, 4-(2-(bis(4-fluorophenyl)methoxy)ethyl)-1-(2-trifluoromethylbenzyl)piperidine (the C(2)-trifluoromethyl substituted compound), has been found to act as an allosteric modulator of hSERT binding and function. It had little affinity for any of the transporters. Several compounds showed affinity for the DAT in the low nanomolar range and displayed a broad range of SERT/DAT selectivity ratios and very little affinity for the NET. The pharmacological tools provided by the availability of compounds with varying transporter affinity and selectivity could be used to obtain additional information about the properties a compound should have to act as a useful pharmacotherapeutic agent for cocaine addiction and help unravel the pharmacological mechanisms relevant to stimulant abuse.

Topics: Allosteric Regulation; Benzhydryl Compounds; Binding, Competitive; Dopamine Plasma Membrane Transport Proteins; Humans; Molecular Structure; Norepinephrine Plasma Membrane Transport Proteins; Piperazines; Piperidines; Serotonin Plasma Membrane Transport Proteins; Stereoisomerism; Structure-Activity Relationship

Pharmacophore modeling of large, drug-like molecules, such as the dopamine reuptake inhibitor GBR 12909, is complicated by their flexibility. A comprehensive hierarchical clustering study of two GBR 12909 analogs was performed to identify representative conformers for input to three-dimensional quantitative structure-activity relationship studies of closely-related analogs. Two data sets of more than 700 conformers each produced by random search conformational analysis of a piperazine and a piperidine GBR 12909 analog were studied. Several clustering studies were carried out based on different feature sets that include the important pharmacophore elements. The distance maps, the plot of the effective number of clusters versus actual number of clusters, and the novel derived clustering statistic, percentage change in the effective number of clusters, were shown to be useful in determining the appropriate clustering level. Six clusters were chosen for each analog, each representing a different region of the torsional angle space that determines the relative orientation of the pharmacophore elements. Conformers of each cluster that are representative of these regions were identified and compared for each analog. This study illustrates the utility of using hierarchical clustering for the classification of conformers of highly flexible molecules in terms of the three-dimensional spatial orientation of key pharmacophore elements.

Topics: Cluster Analysis; Dopamine Uptake Inhibitors; Drug Design; Fuzzy Logic; Models, Molecular; Molecular Conformation; Molecular Structure; Piperazines; Piperidines; Quantitative Structure-Activity Relationship; Thermodynamics

Previous studies identified partial inhibitors of serotonin (5-HT) transporter and dopamine transporter binding. We report here on a partial inhibitor of 5-HT transporter (SERT) binding identified among a group of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine analogs (4-[2-[bis(4-fluorophenyl)-methoxy]ethyl]-1-(2-trifluoromethyl-benzyl)-piperidine; TB-1-099). Membranes were prepared from rat brains or human embryonic kidney cells expressing the cloned human dopamine (hDAT), serotonin (hSERT), and norepinephrine (hNET) transporters. beta-(4'-(125)Iodophenyl)tropan-2beta-carboxylic acid methyl ester ([(125)I]RTI-55) binding and other assays followed published procedures. Using rat brain membranes, TB-1-099 weakly inhibited DAT binding (K(i) = 439 nM), was inactive at NET binding ([(3)H]nisoxetine), and partially inhibited SERT binding with an extrapolated plateau ("A" value) of 20%. Similarly, TB-1-099 partially inhibited [(125)I]RTI-55 binding to hSERT with an extrapolated plateau (A value) of 14%. Upon examining the effect of increasing concentrations of TB-1-099 on the apparent K(d) and B(max) of [(125)I]RTI-55 binding to hSERT, we found that TB-1-099 decreased the B(max) in a dose-dependent manner and affected the apparent K(d) in a manner well described by a sigmoid dose-response curve. TB-1-099 increased the K(d) but not to the magnitude expected for a competitive inhibitor. In rat brain synaptosomes, TB-1-099 noncompetitively inhibited [(3)H]5-HT, but not [(3)H]dopamine, uptake. Dissociation experiments indicated that TB-1-099 promoted the rapid dissociation of a small component of [(125)I]RTI-55 binding to hSERT. Association experiments demonstrated that TB-1-099 slowed [(125)I]RTI-55 binding to hSERT in a manner unlike that of the competitive inhibitor indatraline. Viewed collectively, these results support the hypothesis that TB-1-099 allosterically modulates hSERT binding and function.

Topics: Animals; Benzhydryl Compounds; Binding, Competitive; Brain; Cell Line; Cocaine; Dopamine; Humans; In Vitro Techniques; Kinetics; Male; Membrane Glycoproteins; Membrane Transport Proteins; Nerve Tissue Proteins; Neurotransmitter Agents; Piperazines; Piperidines; Protein Binding; Rats; Rats, Sprague-Dawley; Selective Serotonin Reuptake Inhibitors; Serotonin; Serotonin Plasma Membrane Transport Proteins

Compound (+)-R,R-D-84 is an optically active trans-hydroxy-substituted derivative of 4-(2-benzhydryloxy-ethyl)-1-(4-fluorobenzyl)piperidine (D-164). As a hydroxypiperidine analog of GBR 12935, (+)-R,R-D-84 is a candidate dopamine transporter compound for the treatment of cocaine dependence. The present work addresses the functional activity of (+)-R,R-D-84 at monoamine transporters and its potential molecular mechanism involving acidic amino acids (D and E). The selectivity for the dopamine vs. serotonin transporter of (+)-R,R-D-84 was greater than that of (-)-S,S-D-83, its enantiomer, and the selectivity of both compounds was greater than that of GBR 12909 (diphenyl-fluorinated GBR 12935). Only (+)-R,R-D-84 displayed improved selectivity vs. the norepinephrine transporter. D313N or E215Q mutation did not alter the pattern of affinities (measured by membrane binding of the cocaine analog [3H]CFT) for the dopamine transporter of (+)-R,R-D-84, (-)-S,S-D-83, D-164 (non-hydroxylated analog), or GBR 12909. In contrast, D68N mutation specifically lowered the affinity of (+)-R,R-D-84, pointing to a role for D68 in the interaction with (+)-R,R-D-84, possibly through hydrogen bonding between the hydroxyl and the carboxyl group of D68 which is lacking in N68. The present results, combined with behavioral data, implicate D68 in the dopamine transporter in cocaine antagonist activity of (+)-R,R-D-84.

Topics: Animals; Aspartic Acid; Benzhydryl Compounds; Binding Sites; Binding, Competitive; Biological Transport; Cell Line; Cell Membrane; Cerebral Cortex; Cocaine; Corpus Striatum; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dose-Response Relationship, Drug; Humans; Male; Membrane Glycoproteins; Membrane Transport Proteins; Models, Molecular; Mutation; Nerve Tissue Proteins; Norepinephrine; Piperazines; Piperidines; Protein Binding; Rats; Rats, Sprague-Dawley; Serotonin; Stereoisomerism; Synaptosomes; Tritium

A series of 4-[2-[bis(4-fluorophenyl)methoxy]ethyl-1-benzylpiperidines were examined for their ability to bind to the dopamine transporter (DAT), the serotonin transporter (SERT), and the norepinephrine transporter (NET). Binding results indicated that the presence of an electron-withdrawing group in the C(4)-position of the N-benzyl group is beneficial for binding to the DAT. Several analogues have been identified with high affinity for the DAT, up to 500-fold selectivity over the SERT and about 170-fold selectivity over the NET in binding and uptake inhibition assays.

Topics: Carrier Proteins; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Membrane Glycoproteins; Membrane Transport Modulators; Membrane Transport Proteins; Nerve Tissue Proteins; Norepinephrine; Norepinephrine Plasma Membrane Transport Proteins; Piperazines; Piperidines; Protein Binding; Radioligand Assay; Serotonin; Serotonin Plasma Membrane Transport Proteins; Structure-Activity Relationship; Symporters

To explore structure-activity relationships (SAR) of a novel conformationally constrained lead cis-3,6-disubstituted piperidine derivative derived from (2,2-diphenylethyl)-[1-(4-fluorobenzyl)piperidine-4-ylmethyl]amine (I), a series of compounds was synthesized by derivatizing the exocyclic N-atom at the 3-position of the lead. This study led to the formation of substituted phenyl and heterocyclic derivatives. All novel compounds were tested for their affinity at the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in competing for the binding of [3H]WIN 35 428, [3H]citalopram, and [3H]nisoxetine, respectively. Selected compounds were also evaluated for their activity in inhibiting the uptake of [3H]DA. The SAR results demonstrated that the nature of substitutions on the phenyl ring is important in activity at the DAT with the presence of an electron-withdrawing group having the maximum effect on potency. Replacement of the phenyl ring in the benzyl group by heterocyclic moieties resulted in the development of compounds with moderate activity for the DAT. Two most potent racemic compounds were separated by a diastereoisomeric separation procedure, and differential affinities were observed for the enantiomers. Absolute configuration of the enantiomers was obtained unambiguously by X-ray crystal structural study. One of the enantiomers, compound S,S-(-)-19a, exhibited the highest potency for the DAT (IC50 = 11.3 nM) among all the compounds tested and was as potent as GBR 12909 (1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine). However, the compound (-)-19a was more selective than GBR 12909 in binding to the DAT compared with binding to the SERT and NET. The present results establish the newly developed 3,6-disubstituted piperidine derivatives as a novel template for high-affinity inhibitors of DAT. Structurally these molecules are more constrained compared to our earlier flexible piperidine molecules and, thus, should provide more insights about their bioactive conformations.

Topics: Animals; Binding, Competitive; Biogenic Monoamines; Biological Transport; Brain; Carrier Proteins; Crystallography, X-Ray; Dopamine Plasma Membrane Transport Proteins; In Vitro Techniques; Membrane Glycoproteins; Membrane Transport Proteins; Molecular Conformation; Nerve Tissue Proteins; Nitriles; Norepinephrine Plasma Membrane Transport Proteins; Piperazines; Piperidines; Radioligand Assay; Rats; Serotonin Plasma Membrane Transport Proteins; Stereoisomerism; Structure-Activity Relationship; Symporters

1. The pharmacology of the acute hyperthermia that follows 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') administration to rats has been investigated. 2. MDMA (12.5 mg kg(-1) i.p.) produced acute hyperthermia (measured rectally). The tail skin temperature did not increase, suggesting that MDMA may impair heat dissipation. 3. Pretreatment with the 5-HT(1/2) antagonist methysergide (10 mg kg(-1)), the 5-HT(2A) antagonist MDL 100,907 (0.1 mg kg(-1)) or the 5-HT(2C) antagonist SB 242084 (3 mg kg(-1)) failed to alter the hyperthermia. The 5-HT(2) antagonist ritanserin (1 mg kg(-1)) was without effect, but MDL 11,939 (5 mg kg(-1)) blocked the hyperthermia, possibly because of activity at non-serotonergic receptors. 4. The 5-HT uptake inhibitor zimeldine (10 mg kg(-1)) had no effect on MDMA-induced hyperthermia. The uptake inhibitor fluoxetine (10 mg kg(-1)) markedly attenuated the MDMA-induced increase in hippocampal extracellular 5-HT, also without altering hyperthermia. 5. The dopamine D(2) antagonist remoxipride (10 mg kg(-1)) did not alter MDMA-induced hyperthermia, but the D(1) antagonist SCH 23390 (0.3 - 2.0 mg kg(-1)) dose-dependently antagonized it. 6. The dopamine uptake inhibitor GBR 12909 (10 mg kg(-1)) did not alter the hyperthermic response and microdialysis demonstrated that it did not inhibit MDMA-induced striatal dopamine release. 7. These results demonstrate that in vivo MDMA-induced 5-HT release is inhibited by 5-HT uptake inhibitors, but MDMA-induced dopamine release may not be altered by a dopamine uptake inhibitor. 8. It is suggested that MDMA-induced hyperthermia results not from MDMA-induced 5-HT release, but rather from the increased release of dopamine that acts at D(1) receptors. This has implications for the clinical treatment of MDMA-induced hyperthermia.

Topics: 3,4-Methylenedioxyamphetamine; Acute Disease; Animals; Benzazepines; Body Temperature; Corpus Striatum; Dopamine; Dopamine Antagonists; Dopamine Uptake Inhibitors; Fever; Hallucinogens; Hippocampus; Male; Methysergide; N-Methyl-3,4-methylenedioxyamphetamine; Neuroprotective Agents; Piperazines; Piperidines; Rats; Rats, Inbred Strains; Receptor, Serotonin, 5-HT2A; Receptor, Serotonin, 5-HT2C; Receptors, Serotonin; Remoxipride; Ritanserin; Selective Serotonin Reuptake Inhibitors; Serotonin Antagonists

In our effort to develop a novel radioligand selective for the dopamine transporter, compound 1b (O-972) was designed and characterized. The compound 1b was characterized for its binding both in monkey and rat striatum tissue, which demonstrated its high selectivity for the dopamine transporter (DAT) when its binding was compared with that at the serotonin transporter (SERT). The compound 5, which is a precursor for the tritiated radiolabel ligand [3H]O-972, was synthesized and biologically characterized. The preliminary characterization of this novel radioligand revealed its strong binding affinity for the DAT. Thus, the pharmacological profile of [3H]O-972 indicated that DAT inhibitors, which include GBR 12909, mazindol, CFT, and cocaine, could potently displace this novel radioligand from monkey brain striatum tissue. On the other hand, compounds known to be not selective for and potent at the DAT were very weak to do so. Initial binding results also indicate that [3H]O-972 may interact with the DAT in a manner that is not identical to that for GBR 12909 and tropane analogs.

Topics: Animals; Benzhydryl Compounds; Binding, Competitive; Carrier Proteins; Cocaine; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Female; Ligands; Macaca mulatta; Male; Mazindol; Membrane Glycoproteins; Membrane Transport Proteins; Neostriatum; Nerve Tissue Proteins; Piperazines; Piperidines; Radioligand Assay; Tritium

The dopamine transporter (DAT) has been implicated strongly in cocaine's reinforcing effects. Many derivatives of piperidine analogs of GBR 12909 have been developed and were found to be quite potent and selective for the DAT. In this regard, most of these derivatives were found to be much more selective for the DAT than conventional GBR compounds e.g. GBR 12909 when their selectivity was compared with the serotonin transporter (SERT). A brief structure-activity relationship (SAR) study has been carried out in the development of a novel photoaffinity ligand which illustrated the effect of the presence of a sterically bulky iodine atom next to the azido group in activity and selectivity for the DAT. This SAR study also led to the development of the compound 4 which is one of the most potent and selective blockers for the DAT known today. The photoaffinity ligand [125I]AD-96-129 was incorporated into the DAT molecule as was demonstrated by immunoprecipitation with serum 16 which is specific for DAT. This photolabeling was antagonized by DAT-specific blockers and was unaffected by specific SERT and norepinephrine transporter (NET) blockers indicating interaction of this novel ligand with the DAT.

Topics: Animals; Carrier Proteins; Corpus Striatum; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Drug Design; Membrane Glycoproteins; Membrane Transport Proteins; Nerve Tissue Proteins; Photoaffinity Labels; Piperazines; Piperidines; Rats; Serotonin Plasma Membrane Transport Proteins; Structure-Activity Relationship

The purpose of the present study was to compare the effectiveness of the selective 5-HT2A antagonist M100907 in different psychosis models. The classical neuroleptic haloperidol was used as reference compound. Two hyperdopaminergia and two hypoglutamatergia mouse models were used. Hyperdopaminergia was produced by the DA releaser d-amphetamine or the DA uptake inhibitor GBR 12909. Hypoglutamatergia was produced by the un-competitive NMDA receptor antagonist MK-801 or the competitive NMDA receptor antagonist D-CPPene. M100907 was found to counteract the locomotor stimulant effects of the NMDA receptor antagonists MK-801 and D-CPPene, but spontaneous locomotion, d-amphetamine- and GBR-12909-induced hyperactivity were not significantly affected. Haloperidol, on the other hand, antagonized both NMDA antagonist- and DA agonist-induced hyperactivity, as well as spontaneous locomotion in the highest dose used. Based on the present and previous results we draw the conclusion that 5-HT2A receptor antagonists are particularly effective against behavioural anomalies resulting from hypoglutamatergia of various origins. The clinical implications of our results and conclusions would be that a 5-HT2A receptor antagonist, due to i a the low side effect liability, could be the preferable treatment strategy in various disorders associated with hypoglutamatergia; such conditions might include schizophrenia, childhood autism and dementia disorders.

Topics: Amphetamine; Animals; Dizocilpine Maleate; Dopamine; Dopamine Agonists; Dopamine Uptake Inhibitors; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; Fluorobenzenes; Glutamic Acid; Haloperidol; Hyperkinesis; Male; Mice; Mice, Inbred Strains; Motor Activity; N-Methylaspartate; Piperazines; Piperidines; Receptor, Serotonin, 5-HT2A; Receptors, Serotonin; Serotonin Antagonists

Molecular structural modifications of 4-[2-(diphenylmethoxy)ethyl]-1-(3-phenylpropyl)piperidine (1a), a dopamine transporter (DAT)-specific ligand, generated several novel analogues. Biological activities of these new molecules for their binding to the DAT and serotonin transporter (SERT) were evaluated in rat striatal membranes. Some of these new analogues were more potent and selective than GBR 12909 when their binding to the DAT relative to SERT was compared. Thus compounds 9 and 19a were among the most potent (IC50 = 6.6 and 6.0 nM, respectively) and selective (DAT/SERT = 33.8 and 30.0, respectively) compounds in this series, and they were more active than GBR 12909 (IC50 = 14 nM, DAT/SERT = 6.1). Introduction of a double bond in the N-propyl side chain of these molecules did not influence their activities to a great extent. Bioisosteric replacement of the aromatic phenyl group by a thiophene moiety produced some of the most potent compounds in this series.

Topics: Animals; Benzhydryl Compounds; Carrier Proteins; Cell Membrane; Cocaine; Corpus Striatum; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Male; Membrane Glycoproteins; Membrane Transport Proteins; Molecular Structure; Nerve Tissue Proteins; Piperazines; Piperidines; Rats; Rats, Sprague-Dawley; Structure-Activity Relationship

The replacement of the benzhydrylic oxygen atom of our previously developed dopamine transporter (DAT)-specific ligands 4-[2-(diphenylmethoxy)ethyl]-1-[(4-fluorophenyl)methyl]piperidine, 1a, and 4-[2-(bis(4-fluorophenyl)methoxy)ethyl]-1-benzylpiperidine, 1b, by a nitrogen atom resulted in the development of the N-analogues 4-[2-((diphenylmethyl)amino)ethyl]-1-[(4-fluorophenyl)methyl]pi peridi ne, 4a, and 4-[2-((bis(4-fluorophenyl)methyl)amino)ethyl]-1-benzylpiperidine, 4b. Biological evaluation of these compounds in rat striatal tissue and in HEK-293 cells expressing the cloned human transporters demonstrated high potency and selectivity of these compounds for the DAT. Thus the potency of the compound 4a for the DAT was 9.4 and 30 nM in rat striatal tissue and in the cloned transporter cells, and its binding selectivity for the DAT compared to the serotonin transporter (SERT) for these two systems was 62 and 195, respectively. The compound 4b similarly exhibited high potency and selectivity for the DAT. Thus, the replacement of the O atom in 1a,b by an N atom in 4a,b only had small effects on potency and selectivity. In comparison with GBR 12909 [1-[2-(bis(4-fluorophenyl)methoxy)ethyl]-4-(3-phenylpropyl)piperazine ] and WIN 35,428 [3beta-(p-fluorophenyl)-2beta-carbomethoxytropane] binding, these two novel N-analogues were slightly more potent and far more selective for the DAT. Thus, these novel N-analogues represent more polar new-generation piperidine congeners of GBR 12909. They might have useful potential application in developing a pharmacotherapy for cocaine dependence.

Topics: Animals; Carrier Proteins; Cell Line; Citalopram; Cloning, Molecular; Cocaine; Corpus Striatum; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Drug Design; Humans; Ligands; Membrane Glycoproteins; Membrane Transport Proteins; Molecular Structure; Nerve Tissue Proteins; Piperazines; Piperidines; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Serotonin; Serotonin Plasma Membrane Transport Proteins; Structure-Activity Relationship; Transfection

We recently demonstrated that some H-antagonists have cocaine or methamphetamine-like discriminative stimulus effects. In the present study, the effects of optical isomers of chlorpheniramine (D-, L- and DL-forms) on the discriminative stimulus effects of cocaine and methamphetamine were examined in rats trained to discriminate between cocaine (10.0 mg/kg) or methamphetamine (1.0 mg/kg) and saline, to determine whether these effects of H1-antagonists are mediated by the blockade of H-receptors. In generalization tests with optical isomers of chlorpheniramine, the D-, L- and DL-forms all completely generalized to the discriminative stimulus effects of cocaine, but did not generalize to those of methamphetamine. Dose-generalization by the optical isomers of chlorpheniramine to the discriminative stimulus effects of cocaine did not correlate with the H-antagonistic potency of these drugs. These results suggest that all of the optical isomers of chlorpheniramine have cocaine-like discriminative stimulus effects, but that these effects are not mediated by H1-receptor blockade. On the other hand, the H2-antagonist, zolantidine, generalized to the discriminative stimulus effects of methamphetamine, but not to those of cocaine, suggesting that zolantidine may have methamphetamine-like discriminative stimulus effects. In the present study, GBR12909 (dopamine uptake inhibitor) completely generalized to the discriminative stimulus effects of cocaine, but not to those of methamphetamine, whereas apomorphine (dopamine receptor agonist) generalized more potently to the discriminative stimulus effects of methamphetamine than to those of cocaine. These findings imply that although the dopaminergic system plays an important role in the discriminative stimulus effects of both cocaine and methamphetamine, there may be differences between their effects.

Topics: Animals; Antidepressive Agents, Tricyclic; Benzothiazoles; Chlorpheniramine; Clomipramine; Cocaine; Desipramine; Discrimination, Psychological; Dopamine Uptake Inhibitors; Dose-Response Relationship, Drug; Generalization, Stimulus; Histamine H1 Antagonists; Histamine H2 Antagonists; Humans; Male; Methamphetamine; Middle Aged; Phenoxypropanolamines; Piperazines; Piperidines; Rats; Rats, Inbred F344; Thiazoles

The extracellular concentration of dopamine in the striatum and medial prefrontal cortex of the rat was determined following the systemic administration of sigma receptor ligands. The (+)-benzomorphan, (+)-pentazocine, significantly increased the extracellular concentration of dopamine in the striatum also was produced by the (+)-, but not the (-)-, enantiomer of N-allylnormetazocine, as well as by the non-benzomorphans 1-(cyclopropylmethyl)-4-(2'-(4"-fluorophenyl)-2'-oxoothyl-piper idi ne (DUP 734) and (-)-butaclamol. In contrast, the dopamine concentration was unaffected by di-o-tolylguanidine and markedly suppressed by (+)-3-[3-hydroxyphenyl]-N-(1-propyl)piperidine (3-PPP). Finally, the (+)-pentazocine-induced elevation of the extracellular concentration of dopamine was not suppressed by an inhibitor of the dopamine transporter, 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-[3-phenylpropyl]piperazine (GBR 12909). Thus, benzomorphan, e.g., (+)-pentazocine and (+)-N-allylnormetazocine, and non-benzomorphan, e.g., DUP 734 and (-)-butaclamol, sigma receptor ligands appear to facilitate dopamine release from nigrostriatal, and presumably mesocorticolimbic, neurons through a non-transporter-mediated mechanism.

Topics: Animals; Benzomorphans; Corpus Striatum; Dopamine; Guanidines; Ligands; Male; Pentazocine; Piperazines; Piperidines; Prefrontal Cortex; Rats; Rats, Sprague-Dawley; Receptors, sigma; Stereoisomerism

The present study has shown that a subthreshold dose of the uncompetitive N-methyl-D-aspartate (NMDA) antagonist MK-801, combined with a subthreshold dose of LSD, produces marked locomotor stimulation in monoamine-depleted mice. Likewise, MK-801, as well as the muscarine receptor antagonist atropine and the alpha-adrenoceptor agonist clonidine, were found to interact synergistically with the putative 5-HT2 receptor agonist UH-232 to produce locomotor activation in monoamine-depleted mice. All these responses were effectively blocked by the highly selective 5-HT2A receptor antagonist MDL 100,907. On the other hand, MDL 100,907 did not antagonize the hyperactivity response produced by clonidine given in combination with MK-801 or atropine in monoamine-depleted mice, nor the response produced by the mixed DA receptor agonist apomorphine, underlining the selectivity in the antagonistic action of MDL 100,907. Furthermore, MDL 100,907 attenuated the hyperactivity produced in intact mice by such disparate agents as MK-801, atropine or the DA uptake inhibitor GBR 12,909. A putative "permissive" role of the 5-HT2 receptor in the context of psychomotor activation is discussed, as well as its possible importance as target for antipsychotic therapy.

Topics: Animals; Biogenic Monoamines; Disease Models, Animal; Dizocilpine Maleate; Dopamine Uptake Inhibitors; Excitatory Amino Acid Antagonists; Fluorobenzenes; Glutamic Acid; Hallucinogens; Lysergic Acid Diethylamide; Male; Mice; Mice, Inbred Strains; Neurotransmitter Agents; Piperazines; Piperidines; Psychomotor Performance; Psychotic Disorders; Receptor, Serotonin, 5-HT2A; Receptors, Muscarinic; Receptors, Serotonin; Serotonin; Serotonin Antagonists

In preparation for expression studies for rat brain sigma-binding sites, Xenopus oocytes were tested for the presence of [3H]di-o-tolylguanidine (DTG)-binding sites. Native oocytes were found to contain two intrinsic [3H]DTG-binding sites, a high-affinity site (Kd = 32 +/- 6 nM, Bmax of 45.7 +/- 19 pmol/mg protein) and a low-affinity binding site (Kd = 1.3 +/- 0.7 microM, Bmax of 3.2 +/- 0.7 nmol/mg protein). In a series of radioligand-binding-displacement studies, the high-affinity binding sites were found to have a binding profile which has a similar Kd to that of the mammalian sigma 2-binding site (32 vs. 38 nM). Comparison of the IC50 values for inhibition of [3H]DTG binding in rat liver and oocytes for DTG, haloperidol (HAL), (-)-pentazocine, (+)-3-(3-hydroxyphenyl)-N-propylpiperidine hydrochloride ((+)-3-PPP), (+)-pentazocine and Zn2+, showed similarity in rank (r2 = 0.913) but a 7-fold lower potency in oocytes. These results suggest that the high-affinity [3H]DTG-binding site in oocytes represents a sigma 2-like binding site.

Topics: Animals; Binding Sites; Binding, Competitive; Carbazoles; Dextromethorphan; Female; Guanidines; Haloperidol; Liver; Mazindol; Oocytes; Pentazocine; Phenazocine; Piperazines; Piperidines; Radioligand Assay; Rats; Receptors, sigma; Xenopus laevis; Zinc

The present study was undertaken to characterize [3H]ifenprodil binding in rat brain. [3H]Ifenprodil showed saturable, high-affinity binding at 4 degrees C. Specific binding, defined with 10 microM ifenprodil as a competitor, was inhibited biphasically by the s receptor ligands, GBR 12909, 1,3-di-o-tolylguanidine (DTG), and (+)-3-(3-hydroxyphenyl)-N-propylpiperidine ((+)-3-PPP). At 4 degrees C, 3 microM GBR 12909, which inhibited about 50% of specific binding of [3H]ifenprodil was used to mask sigma receptors. Under these conditions, specific binding of [3H]ifenprodil was inhibited potently by ifenprodil, SL 82.0715, poly(L-arginine), poly(L-lysine), neomycin, ruthenium red, spermine, arcaine and spermidine. In the presence of 3 microM GBR 12909, Zn2+ and Mg2+ partially inhibited specific binding of [3H]ifenprodil at 4 degrees C. In contrast, in the absence of GBR 12909, at 37 degrees C specific binding of [3H]ifenprodil was partially inhibited by Zn2+, but not by Mg2+. The anatomical distribution of [3H]ifenprodil binding at 4 degrees C (GBR 12909 included) in rat brain closely paralleled that of [3H]MK-801 (dizocilpine) binding (r = 0.971, P < 0.005). Without GBR 12909, specific [3H]ifenprodil binding at 37 degrees C was inhibited potently by sigma ligands. In the presence of 3 microM GBR 12909, [3H]ifenprodil binding at 4 degrees C was highest in synaptosomal and myelin fractions; however, without GBR 12909, [3H]ifenprodil binding at 37 degrees C was highest in microsomal and myelin fractions, consistent with the subcellular distribution of sigma receptors. The results suggest that, in the presence of 3 microM GBR 12909, at 4 degrees C, [3H]ifenprodil binds to sites that are sensitive to polyamines and related compounds; and that without GBR 12909, at 37 degrees C, [3H]ifenprodil interacts with sigma receptors in rat brain.

Topics: Adrenergic alpha-Antagonists; Animals; Binding Sites; Binding, Competitive; Brain; Dizocilpine Maleate; Dopamine Agents; Dose-Response Relationship, Drug; Guanidines; In Vitro Techniques; Male; Neurotransmitter Uptake Inhibitors; Piperazines; Piperidines; Rats; Rats, Inbred F344; Receptors, sigma

1,4-Disubstituted piperazines such as GBR 12909 (1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine) and GBR 12935 (1-[2-(bis(phenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine) are among the most potent and selective ligands for the dopamine transporter in brain. However, they also bind to a widely distributed "piperazine acceptor site". In order to assess whether the piperazine moiety of GBR 12909 is critical for binding to the dopamine transporter, two piperidine analogs of GBR 12909, one with the nitrogen proximal to the diphenylmethyloxy moiety (O-549, (1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperidine), the other distal to this moiety (O-526, 4-[2-[bis(4-fluorophenyl)methoxy]ethyl]-1- (3-phenylpropyl)piperidine) were synthesized. The affinities of O-526, O-549 and GBR 12909 for the dopamine and serotonin transporters in monkey caudate-putamen (Macaca fascicularis) were evaluated using [3H]WIN 35,428 ([3H]CFT, 2 beta-carbomethoxy-3 beta-4-(fluorophenyl)tropane) or [3H]GBR 12935 and [3H]citalopram to label the dopamine and serotonin transporters, respectively. O-526 inhibited [3H]WIN 35,428 binding with potencies that were similar to GBR 12909 (IC50: 24.9 +/- 3.23 vs. 22.0 +/- 2.2 nM, respectively) whereas O-549 was 24 times less potent than O-526 (IC50: 595 +/- 148 nM). The selectivity of GBR 12909 for the dopamine over the serotonin transporter was retained by O-526 but not by O-549 which was relatively non-selective. These results indicate that only one of the two nitrogens on the basic GBR structure is needed for high affinity binding to the dopamine transporter.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Carrier Proteins; Caudate Nucleus; Citalopram; Cocaine; Dopamine Plasma Membrane Transport Proteins; In Vitro Techniques; Macaca fascicularis; Membrane Glycoproteins; Membrane Transport Proteins; Nerve Tissue Proteins; Neurotransmitter Uptake Inhibitors; Piperazines; Piperidines; Protein Binding; Putamen; Serotonin; Serotonin Plasma Membrane Transport Proteins

Fluspirilene and GBR-12909, two compounds structurally similar to BMY-14802 and haloperidol, were assessed for their ability to interact with sigma receptors. Fluspirilene, an antipsychotic agent that interacts potently with dopamine receptors, inhibited the binding of [3H]-(+) 3-PPP (IC50 = 380 nM) more potently than rimcazole, a putative sigma antagonist that was tested clinically for antipsychotic activity. GBR-12909, a potent dopamine uptake blocker, also inhibited the binding of [3H]-(+) 3-PPP with an IC50 of 48 nM. However, other compounds that block the re-uptake of catecholamines, such as nomifensine, desipramine, imipramine, xylamine, benztropine and cocaine, were much weaker than GBR-12909 as sigma ligands. Thus, GBR-12909 and fluspirilene, compounds structurally similar to BMY-14802, are potent sigma ligands.

Topics: Animals; Antipsychotic Agents; Brain; Dopamine Agents; Fluspirilene; Male; Neurotransmitter Uptake Inhibitors; Piperazines; Piperidines; Radioligand Assay; Rats; Rats, Inbred Strains; Receptors, Opioid; Receptors, sigma

At concentrations greater than or equal to 100 microM, phencyclidine (PCP), N-(1-(2-thienyl)-cyclohexyl)piperidine (TCP), and MK-801 induced [3H]dopamine release from dissociated cell cultures of rat mesencephalon. This release was Ca2+ independent and tetrodotoxin insensitive. Tetrodotoxin (2 microM) itself had no effect on spontaneous release of [3H]dopamine. [3H]Dopamine release was induced by 1,3-di(2-tolyl)guanidine, a sigma ligand, and by 4-aminopyridine (1-3 mM), a K+ channel blocker. No stereoselectivity was observed for [3H]dopamine release evoked by the dioxadrol enantiomers, dexoxadrol, and levoxadrol, or by enantiomers of N-allylnormetazocine (SKF 10,047). The selective dopamine uptake inhibitor 1-(2-[bis(4-fluorophenyl)methoxy]ethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (GBR 12909) did not affect spontaneous or TCP-evoked [3H]dopamine release. Together, these data suggest that the dopamine-releasing effects of PCP-like compounds on the mesencephalic cells were not mediated by actions at the PCP receptor or sigma binding site, Ca2+, or Na+ channels, or at the high affinity dopamine uptake site. It remains conceivable that blocking actions of PCP-like compounds at voltage-regulated K+ channels may at least partly explain the response. These results are discussed in comparison with findings in intact brain.

Topics: 2-Amino-5-phosphonovalerate; Animals; Anticonvulsants; Binding Sites; Cells, Cultured; Dioxolanes; Dizocilpine Maleate; Dopamine; Dose-Response Relationship, Drug; Guanidines; Mesencephalon; N-Methylaspartate; Neurotransmitter Uptake Inhibitors; Phencyclidine; Piperazines; Piperidines; Rats; Rats, Inbred Strains; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Receptors, Phencyclidine; Sigma Factor; Tritium