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Negus SS, Baumann MH, Rothman RB, Mello NK, Blough BE. Selective suppression of cocaine- versus food-maintained responding by monoamine releasers in rhesus monkeys: benzylpiperazine, (+)phenmetrazine, and 4-benzylpiperidine. J Pharmacol Exp Ther 2009; 329:272-81. [PMID: 19151247 DOI: 10.1124/jpet.108.143701] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Monoamine releasers constitute one class of drugs currently under investigation as potential agonist medications for the treatment of cocaine dependence. The efficacy and safety of monoamine releasers as candidate medications may be influenced in part by their relative potency to release dopamine and serotonin, and we reported previously that releasers with approximately 30-fold selectivity for dopamine versus serotonin release may be especially promising. The present study examined the effects of the releasers benzylpiperazine, (+)phenmetrazine, and 4-benzylpiperidine, which have 20- to 48-fold selectivity in vitro for releasing dopamine versus serotonin. In an assay of cocaine discrimination, rhesus monkeys were trained to discriminate 0.4 mg/kg i.m. cocaine from saline in a two-key, food-reinforced procedure. Each of the releasers produced a dose- and time-dependent substitution for cocaine. 4-Benzylpiperidine had the most rapid onset and shortest duration of action. Phenmetrazine and benzylpiperazine had slower onsets and longer durations of action. In an assay of cocaine self-administration, rhesus monkeys were trained to respond for cocaine injections and food pellets under a second order schedule. Treatment for 7 days with each of the releasers produced a dose-dependent and selective reduction in self-administration of cocaine (0.01 mg/kg/injection). The most selective effects were produced by phenmetrazine. Phenmetrazine also produced a downward shift in the cocaine self-administration dose effect curve, virtually eliminating responding maintained by a 30-fold range of cocaine doses (0.0032-0.1 mg/kg/injection) while having only small and transient effects on food-maintained responding. These findings support the potential utility of dopamine-selective releasers as candidate treatments for cocaine dependence.
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Affiliation(s)
- S S Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA.
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Baumann MH, Clark RD, Franken FH, Rutter JJ, Rothman RB. Tolerance to 3,4-methylenedioxymethamphetamine in rats exposed to single high-dose binges. Neuroscience 2008; 152:773-84. [PMID: 18313226 PMCID: PMC2390896 DOI: 10.1016/j.neuroscience.2008.01.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 01/02/2008] [Accepted: 01/18/2008] [Indexed: 11/16/2022]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA or ecstasy) stimulates the transporter-mediated release of monoamines, including 5-HT. High-dose exposure to MDMA causes persistent 5-HT deficits (e.g. depletion of brain 5-HT) in animals, yet the functional and clinical relevance of such deficits are poorly defined. Here we examine functional consequences of MDMA-induced 5-HT depletions in rats. Male rats received binges of three i.p. injections of MDMA or saline, one injection every 2 h; MDMA was given at a threshold pharmacological dose (1.5 mg/kgx3, low dose) or at a fivefold higher amount (7.5 mg/kgx3, high dose). One week later, jugular catheters and intracerebral guide cannulae were implanted. Two weeks after binges, rats received acute i.v. challenge injections of 1 and 3 mg/kg MDMA. Neuroendocrine effects evoked by i.v. MDMA (prolactin and corticosterone secretion) were assessed via serial blood sampling, while neurochemical effects (5-HT and dopamine release) were assessed via microdialysis in brain. MDMA binges elevated core temperatures only in the high-dose group, with these same rats exhibiting approximately 50% loss of forebrain 5-HT 2 weeks later. Prior exposure to MDMA did not alter baseline plasma hormones or dialysate monoamines, and effects of i.v. MDMA were similar in saline and low-dose groups. By contrast, rats pretreated with high-dose MDMA displayed significant reductions in evoked hormone secretion and 5-HT release when challenged with i.v. MDMA. As tolerance developed only in rats exposed to high-dose binges, hyperthermia and 5-HT depletion are implicated in this phenomenon. Our results suggest that MDMA tolerance in humans may reflect 5-HT deficits which could contribute to further dose escalation.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, DHHS, 333 Cassell Drive, Suite 4500, Baltimore, MD 21224, USA.
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Wang X, Baumann MH, Dersch CM, Rothman RB. Restoration of 3,4-methylenedioxymethamphetamine-induced 5-HT depletion by the administration of l-5-hydroxytryptophan. Neuroscience 2007; 148:212-20. [PMID: 17629409 DOI: 10.1016/j.neuroscience.2007.05.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 05/21/2007] [Accepted: 05/26/2007] [Indexed: 11/16/2022]
Abstract
BACKGROUND 3,4-Methylenedioxymethamphetamine (MDMA) causes persistent decreases in brain 5-HT content and 5-HT transporter (SERT) binding, with no detectable changes in SERT protein. Such data suggest that MDMA impairs 5-HT transmission but leaves 5-HT nerve terminals intact. To further test this hypothesis, we carried out two types of experiments in rats exposed to high-dose MDMA. First, we examined the effects of MDMA on SERT binding and function using different in vitro assay conditions. Next, we treated rats with the 5-HT precursor, l-5-hydroxytryptophan (5-HTP), in an attempt to restore MDMA-induced depletions of 5-HT. METHODS Rats received three i.p. injections of saline or MDMA (7.5 mg/kg), one injection every 2 h. Rats in one group were decapitated, and brain tissue was assayed for SERT binding and [(3)H]5-HT uptake under conditions of normal (100 or 126 mM) and low (20 mM) NaCl concentration. Rats from another group received saline or 5-hydroxytryptophan/benserazide (5-HTP-B), each drug at 50 mg/kg i.p., and were killed 2 h later. RESULTS MDMA reduced SERT binding to 10% of control when assayed in 100 mM NaCl, but this reduction was only 55% of control in 20 mM NaCl. MDMA decreased immunoreactive 5-HT in caudate and hippocampus to about 35% of control. Administration of 5-HTP-B to MDMA-pretreated rats significantly increased the 5-HT signal toward normal levels in caudate (85% of control) and hippocampus (66% of control). CONCLUSION 1) Following high-dose MDMA treatment sufficient to reduce SERT binding by 90%, a significant number of functionally intact 5-HT nerve terminals survive. 2) The degree of MDMA-induced decreases in SERT binding depends on the in vitro assay conditions. 3) 5-HTP-B restores brain 5-HT depleted by MDMA, suggesting that this approach might be clinically useful in abstinent MDMA users.
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Affiliation(s)
- X Wang
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, P.O. Box 5180, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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Groer CE, Tidgewell K, Moyer RA, Harding WW, Rothman RB, Prisinzano TE, Bohn LM. An opioid agonist that does not induce mu-opioid receptor--arrestin interactions or receptor internalization. Mol Pharmacol 2006; 71:549-57. [PMID: 17090705 PMCID: PMC3926195 DOI: 10.1124/mol.106.028258] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
G protein-coupled receptor desensitization and trafficking are important regulators of opioid receptor signaling that can dictate overall drug responsiveness in vivo. Furthermore, different mu-opioid receptor (muOR) ligands can lead to varying degrees of receptor regulation, presumably because of distinct structural conformations conferred by agonist binding. For example, morphine binding produces a muOR with low affinity for beta-arrestin proteins and limited receptor internalization, whereas enkephalin analogs promote robust trafficking of both beta-arrestins and the receptors. Here, we evaluate muOR trafficking in response to activation by a novel mu-selective agonist derived from the naturally occurring plant product, salvinorin A. It is interesting that this compound, termed herkinorin, does not promote the recruitment of beta-arrestin-2 to the muOR and does not lead to receptor internalization. Moreover, whereas G protein-coupled receptor kinase overexpression can promote morphine-induced beta-arrestin interactions and muOR internalization, such manipulations do not promote herkinorin-induced trafficking. Studies in mice have shown that beta-arrestin-2 plays an important role in the development of morphine-induced tolerance, constipation, and respiratory depression. Therefore, drugs that can activate the receptor without recruiting the arrestins may be a promising step in the development of opiate analgesics that distinguish between agonist activity and receptor regulation and may ultimately lead to therapeutics designed to provide pain relief without the adverse side effects normally associated with the opiate narcotics.
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Affiliation(s)
- C E Groer
- Department of Pharmacology, the Ohio State University College of Medicine, 333 W 10th Avenue, 5184A Graves Hall, Columbus, OH 43210, USA
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Negus SS, Mello NK, Blough BE, Baumann MH, Rothman RB. Monoamine releasers with varying selectivity for dopamine/norepinephrine versus serotonin release as candidate "agonist" medications for cocaine dependence: studies in assays of cocaine discrimination and cocaine self-administration in rhesus monkeys. J Pharmacol Exp Ther 2006; 320:627-36. [PMID: 17071819 DOI: 10.1124/jpet.106.107383] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Monoamine releasers constitute one class of drugs under investigation as candidate medications for the treatment of cocaine abuse. Promising preclinical and clinical results have been obtained with amphetamine, which has high selectivity for releasing dopamine/norepinephrine versus serotonin. However, use of amphetamine as a pharmacotherapy is complicated by its high abuse potential. Recent preclinical studies suggest that nonselective monoamine releasers or serotonin-selective releasers have lower abuse liability and may warrant evaluation as alternatives to amphetamine. To address this issue, the present study evaluated the effects of five monoamine releasers in assays of cocaine discrimination and cocaine self-administration in rhesus monkeys. The releasers varied along a continuum from dopamine/norepinephrine-selective to serotonin-selective [m-fluoroamphetamine (PAL-353), methamphetamine, m-methylamphetamine (PAL-314), 1-napthyl-2-aminopropane (PAL-287), fenfluramine]. In drug discrimination studies, rhesus monkeys were trained to discriminate saline from cocaine (0.4 mg/kg i.m.) in a two-key, food-reinforced drug discrimination procedure. Substitution for cocaine was positively associated with selectivity for dopamine/norepinephrine versus serotonin release. In drug self-administration studies, rhesus monkeys responded for cocaine (0.01 and 0.032 mg/kg/injection) and food (1-g pellets) under a second-order fixed-ratio 2 (variable-ratio 16:S) schedule. In general, monoamine releasers produced dose-dependent and sustained decreases in cocaine self-administration. However, the dopamine/norepinephrine-selective releasers decreased cocaine self-administration with minimal effects on food-maintained responding, whereas the more serotonin-selective releasers produced nonselective reductions in both cocaine- and food-maintained responding. These results are consistent with the conclusion that dopamine/norepinephrine-selective releasers retain cocaine-like abuse-related effects but may also be capable of producing relatively selective reductions in the reinforcing effects of cocaine.
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Affiliation(s)
- S S Negus
- Alcohol and Drug Abuse Research Center, McLean Hospital, Harvard Medical School, Belmont, MA 02478-9106, USA.
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Halladay AK, Wagner GC, Sekowski A, Rothman RB, Baumann MH, Fisher H. Alterations in alcohol consumption, withdrawal seizures, and monoamine transmission in rats treated with phentermine and 5-hydroxy-L-tryptophan. Synapse 2006; 59:277-89. [PMID: 16416445 DOI: 10.1002/syn.20239] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have previously shown that coadministration of the dopamine (DA) agonist phentermine plus the serotonergic agonist fenfluramine suppresses alcohol intake and withdrawal seizures in rats. In the present study, phentermine and the serotonin (5-HT) precursor, 5-hydroxy-L-tryptophan (5-HTP), were administered alone, or in combination, to rats fed on a 6% alcohol-containing diet or an isocaloric control diet. Following a 9-h withdrawal period from the alcohol-containing diet, phentermine enhanced the effects of 5-HTP on both reduction of alcohol withdrawal seizures as well as changes in striatal serotonin. Food intake was monitored for 24 h after drug treatment, and neurochemical measures were examined at various time points. Phentermine alone reduced food intake in all diet conditions, but this anorectic effect was followed by hyperphagia in control rats. Phentermine plus 5-HTP reduced the consumption of the alcohol-containing diet, while its effects on consumption of control diets were mixed. In vivo microdialysis in rat nucleus accumbens revealed that phentermine increased extracellular DA, whereas 5-HTP caused marked elevations in extracellular 5-HT. Coadministration of phentermine and 5-HTP evoked simultaneous elevations in extracellular DA and 5-HT that mirrored the effects of each drug alone. Collectively, these findings show that coadministered phentermine plus 5-HTP is effective in reducing alcohol intake and suppressing alcohol withdrawal seizures. These therapeutic actions may be related to elevations in synaptic DA and 5-HT in critical brain regions.
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Affiliation(s)
- A K Halladay
- Department of Pharmacology, Rutgers University, New Brunswick, New Jersey 08901, USA
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Wang X, Xu H, Rothman RB. Intracerebroventricular administration of anti-endothelin-1 IgG selectively upregulates endothelin-A and kappa opioid receptors. Neuroscience 2005; 129:751-6. [PMID: 15541896 DOI: 10.1016/j.neuroscience.2004.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2004] [Indexed: 11/28/2022]
Abstract
Endothelin (ET) type A receptor antagonists enhance morphine-induced antinociception and restore morphine analgesia in morphine tolerant rats [Peptides 23 (2002) 1837; Peptides 24 (2003) 553]. These studies suggest that the central ET and opioid systems functionally interact. To explore this idea further, we determined the effect of i.c.v. administration of anti-ET-1 IgG (rabbit) on brain opioid receptor and ET receptor expression. Three days after implanting cannula into the lateral ventricle, male Sprague-Dawley rats were administered 10 microl (i.c.v.) of either control rabbit IgG (2.5 microg/microl) or anti-ET IgG (2.5 microg/microl) on day 1, day 3, and day 5. On day 6, animals were killed and the caudate and hippocampus collected. Anti-ET IgG had no significant effect on expression, measured by Western blots, of mu, delta or ET-B receptors, but increased kappa opioid (59%) and ET-A (33%) receptor protein expression in the caudate. [35S]-GTP-gamma-S binding assays demonstrated that anti-ET IgG decreased [D-Ala2-MePhe4, Gly-ol5]enkephalin efficacy, but not potency in the caudate. Control experiments showed that there was no detectable rabbit IgG in caudate and hippocampal samples. These results suggest that ET in the CSF negatively regulates kappa opioid and ET-A receptors in certain brain regions. These findings support the hypothesis that CSF neuropeptides have regulatory effects and further demonstrate a link between ET and the opioid receptor system.
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Affiliation(s)
- X Wang
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, PO Box 5180, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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Wee S, Anderson KG, Baumann MH, Rothman RB, Blough BE, Woolverton WL. Relationship between the serotonergic activity and reinforcing effects of a series of amphetamine analogs. J Pharmacol Exp Ther 2005; 313:848-54. [PMID: 15677348 DOI: 10.1124/jpet.104.080101] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
It has been reported that among drugs with mixed actions on central nervous system monoamine systems, increased serotonergic activity is associated with decreased potency as a reinforcer. The present experiment was designed to examine this relationship for amphetamine analogs that varied in serotonin releasing potency and to evaluate whether serotonergic actions can affect reinforcing efficacy. Compounds PAL 313 and 314 are para- and meta-methylamphetamine, respectively. PAL 303 and 353 are para- and meta-fluoroamphetamine, respectively. All compounds had similar potencies as in vitro releasers of dopamine (DA) and norepinephrine (NE) but differed in potency for 5-hydroxytryptamine (serotonin) (5-HT) release [EC(50) (nanomolar) PAL 313 = 53.4; PAL 314 = 218; PAL 303 = 939; PAL 353 = 1937]. When made available to rhesus monkeys (Macaca mulatta)(n = 4) for self-administration under a fixed-ratio 25 schedule, all were positive reinforcers with biphasic dose-response functions (0.003-1.0 mg/kg) and were equipotent. PAL 313 was self-administered at a lower rate than the other compounds, which were indistinguishable. Under a progressive-ratio schedule (n = 5), all drugs were positive reinforcers. Dose-response functions increased to a maximum or were biphasic (0.01-1.0 mg/kg), and drugs were equipotent. At maximum, PAL 313 maintained less responding than other PAL drugs, which maintained similar maxima. Thus, all compounds were positive reinforcers under both schedules, consistent with their potent DA actions. Responding was lower when 5-HT potency was higher and comparable with DA and NE potency. The results suggest that the mechanism for this effect involves a decrease in reinforcing potency and efficacy among monoamine releasing agents when 5-HT releasing potency is increased relative to DA.
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Affiliation(s)
- S Wee
- Department of Psychiatry, University of Mississippi Medical Center, Jackson, 39216-4505, USA
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Baumann MH, Milchanowski AB, Rothman RB. Evidence for alterations in α2-adrenergic receptor sensitivity in rats exposed to repeated cocaine administration. Neuroscience 2004; 125:683-90. [PMID: 15099682 DOI: 10.1016/j.neuroscience.2004.02.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 11/26/2022]
Abstract
It is well established that cocaine stimulates monoamine transmission by blocking reuptake of norepinephrine (NE), dopamine and serotonin into nerve cells, yet few investigations have addressed the effects of chronic cocaine on NE function. In the present study, we examined the effects of repeated cocaine injections on neuroendocrine responses evoked by the alpha2-adrenergic receptor agonist, clonidine. Previous findings show that clonidine increases pituitary growth hormone (GH) secretion by a central mechanism involving postsynaptic alpha2-adrenergic receptors. Male rats previously fitted with indwelling jugular catheters received two daily injections of cocaine (15 mg/kg, i.p.) or saline for 7 days. At 42 h and 8 days after treatment, rats were challenged with clonidine (25 microg/kg, i.v.) or saline, and serial blood samples were withdrawn. Plasma GH and corticosterone levels were measured by radioimmunoassay. Prior cocaine exposure did not affect basal levels of either hormone. However, cocaine-pretreated rats displayed a significant reduction in clonidine-evoked GH secretion at 42 h, and this blunted response was still apparent 8 days later. Corticosterone responses produced by clonidine were similar regardless of pretreatment. The present data suggest that withdrawal from repeated cocaine injections may be accompanied by desensitization of postsynaptic alpha2-adrenoreceptors coupled to GH secretion. Since human patients with depression often exhibit blunted GH responses to clonidine, our findings provide evidence that cocaine withdrawal might produce depressive-like symptoms via dysregulation of NE mechanisms.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, PO Box 5180, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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Baumann MH, Pablo J, Ali SF, Rothman RB, Mash DC. Comparative neuropharmacology of ibogaine and its O-desmethyl metabolite, noribogaine. Alkaloids Chem Biol 2002; 56:79-113. [PMID: 11705118 DOI: 10.1016/s0099-9598(01)56009-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Zhang Y, Joseph DB, Bowen WD, Flippen-Anderson JL, Dersch CM, Rothman RB, Jacobson AE, Rice KC. Synthesis and biological evaluation of tropane-like 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR 12909) analogues. J Med Chem 2001; 44:3937-45. [PMID: 11689080 DOI: 10.1021/jm0101592] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have prepared azabicyclo[3.2.1] derivatives (C-3-substituted tropanes) that bind with high affinity to the dopamine transporter and inhibit dopamine reuptake. Within the series, 3-[2-[bis-(4-fluorophenyl)methoxy]ethylidene]-8-methyl-8-azabicyclo[3.2.1]octane (8) was found to have the highest affinity and selectivity for the dopamine transporter. These azabicyclo[3.2.1] (bridged piperidine) series of compounds differ from the well-known benztropines by a 2-carbon spacer between C-3 and a diarylmethoxy moiety. Interestingly, these new compounds demonstrated a much lower affinity for the muscarinic-1 site, at least a 100-fold decrease compared to benztropine. Replacing N-methyl with N-phenylpropyl in two of the compounds resulted in a 3-10-fold increase in binding affinity for the dopamine transporter. However, those compounds lost selectivity for the dopamine transporter over the serotonin transporter. Replacement of the ether oxygen in the diarylmethoxy moiety with a nitrogen atom gave relatively inactive amines, indicating the important role which is played by the ether oxygen in transporter binding. Reduction of the C-3 double bond in 8 gave 3 alpha-substituted tropanes, as shown by X-ray crystallographic analyses of 11, 12, and 19. The 3 alpha-substituted tropanes had lower affinity and less selectivity than the comparable unsaturated ligands.
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Affiliation(s)
- Y Zhang
- Laboratory of Medicinal Chemistry, Building 8, Room B1-22, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA
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Ullrich T, Dersch CM, Rothman RB, Jacobson AE, Rice KC. Derivatives of 17-(2-methylallyl)-substituted noroxymorphone: variation of the delta address and its effects on affinity and selectivity for the delta opioid receptor. Bioorg Med Chem Lett 2001; 11:2883-5. [PMID: 11597422 DOI: 10.1016/s0960-894x(01)00580-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In an effort to establish the importance of the N-(2-methylallyl) substituent in the noroxymorphone series, several derivatives have been synthesized, retaining that N-substituent and modifying the delta address moiety. A few compounds showed moderate binding affinity and selectivity for the delta receptor; none displayed a pharmacological profile as exceptional as N-(2-methylallyl)noroxymorphindole. A second study showed that 3-O-methylation of all derivatives decreases binding affinity. The present results indicate that only a combination of the N-(2-methylallyl) group and an indole delta address provided high selectivity for the delta receptor.
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Affiliation(s)
- T Ullrich
- Laboratory of Medicinal Chemistry, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
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14
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Thomas JB, Atkinson RN, Rothman RB, Fix SE, Mascarella SW, Vinson NA, Xu H, Dersch CM, Lu Y, Cantrell BE, Zimmerman DM, Carroll FI. Identification of the first trans-(3R,4R)- dimethyl-4-(3-hydroxyphenyl)piperidine derivative to possess highly potent and selective opioid kappa receptor antagonist activity. J Med Chem 2001; 44:2687-90. [PMID: 11495579 DOI: 10.1021/jm015521r] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A structurally novel opioid kappa receptor selective ligand has been identified. This compound, (3R)-7-hydroxy-N-((1S)-1-[[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl]-2-methylpropyl)-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide (JDTic, 10) demonstrated high affinity for the kappa receptor in the binding assay (kappa K(i) = 0.3 nM) and highly potent and selective kappa antagonism in the [(35)S]GTP-gamma-S assay using cloned opioid receptors (kappa K(i) = 0.006 nM, mu/kappa ratio = 570, delta/kappa ratio > 16600).
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MESH Headings
- Animals
- Binding, Competitive
- Brain/metabolism
- Cloning, Molecular
- Guinea Pigs
- Humans
- In Vitro Techniques
- Isoquinolines/chemical synthesis
- Isoquinolines/chemistry
- Isoquinolines/metabolism
- Isoquinolines/pharmacology
- Narcotic Antagonists/chemical synthesis
- Narcotic Antagonists/chemistry
- Narcotic Antagonists/metabolism
- Narcotic Antagonists/pharmacology
- Piperidines/chemical synthesis
- Piperidines/chemistry
- Piperidines/metabolism
- Piperidines/pharmacology
- Radioligand Assay
- Rats
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Structure-Activity Relationship
- Tetrahydroisoquinolines
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Affiliation(s)
- J B Thomas
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, North Carolina 27709, USA
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Xu H, Lu YF, Rice KC, Ananthan S, Rothman RB. SoRI 9409, a non-peptide opioid mu receptor agonist/delta receptor antagonist, fails to stimulate [35S]-GTP-gamma-S binding at cloned opioid receptors. Brain Res Bull 2001; 55:507-11. [PMID: 11543951 DOI: 10.1016/s0361-9230(01)00550-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Recent work suggests that opioids which combine mu agonist and delta antagonist activity may be non-addicting antinociceptive agents. SoRI 9409 (5'-(4-Chlorophenyl)-17-(cyclopropylmethyl)-6,7-didehydro-3,14-dihydroxy-4,5alpha-epoxypyrido-[2',3':6,7]morphinan) is a naltrexone-derived non-peptide ligand which demonstrates partial mu and kappa agonist activity and antagonist activity at delta receptors. Chronic administration of SoRI 9409 to mice failed to produce tolerance to its antinociceptive effect and SoRI 9409 produced less withdrawal signs than naloxone in acute and chronic morphine dependence models. To further characterize SoRI 9409 we determined its effects in the guanosine 5'-O-(3-[35S]thio)-triphosphate binding assay. SoRI 9409 demonstrated no agonist activity at cloned mu delta, or kappa receptors. Other experiments demonstrated that SoRI 9409 was a potent and selective delta antagonist (K(i) = 0.08 nM) which acted also as an antagonist at mu and kappa receptors. Its profile of activity resembled that of naltrindole (NTI). Viewed collectively, the in vitro data reported here predict that SoRI 9409 should be a mu antagonist in vivo, which is not observed. Resolving these discrepant findings will require additional research.
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MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Benzamides/pharmacology
- Benzeneacetamides
- Binding, Competitive
- CHO Cells
- Cloning, Molecular
- Cricetinae
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
- Humans
- Iodine Radioisotopes
- Morphine/chemistry
- Morphine/pharmacology
- Morphine Derivatives
- Naltrexone/analogs & derivatives
- Naltrexone/chemistry
- Naltrexone/pharmacology
- Narcotic Antagonists/chemistry
- Narcotic Antagonists/pharmacology
- Piperazines/pharmacology
- Pyrrolidines/pharmacology
- Receptors, Opioid/genetics
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/genetics
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Sulfur Radioisotopes
- Tritium
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Affiliation(s)
- H Xu
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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16
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Xu H, Lu YF, Thomas JB, Carroll FI, Rice KC, Rothman RB. Opioid peptide receptor studies. 15. Relative efficacy of 4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide and related compounds at the cloned human delta-opioid receptor. Synapse 2001; 40:269-74. [PMID: 11309842 DOI: 10.1002/syn.1049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Previous data obtained from both binding and functional assays demonstrated that (-)-4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide [(-)-RTI5989-54] displays selective binding and full agonist activity relative to (+/-)-RTI5989-54 for the delta opioid receptor. The present study was conducted to evaluate the activities of structurally diverse opioid receptor delta ligands in the [(35)S]GTP-gamma-S binding assay, comparing the relationship between receptor binding, activation, efficacy, and intrinsic efficacy. The data, obtained with cloned human delta receptors, demonstrated that (-)-RTI5989-54 behaves like the highly selective delta agonist SNC80. Addition of the hydroxyl group to RTI5989-54 (RTI5989-61) or replacement of the allyl group with the trans-crotyl group on the piperidine nitrogen of RTI-5989-61 (RTI5989-62) increased binding affinity, produced full agonist activity, and decreased intrinsic efficacy at the delta opioid receptor. The order of potency for the EC(50) (GTP-gamma-S) was RTI5989-62 (0.20 nM) > RTI5989-61 (0.43 nM) > SNC80 (1.92 nM) > DPDPE (3.50 nM) > (-)-RTI5989-54 (17.6 nM) > (+/-)-RTI5989-54 (65.6 nM) > (+)-RTI5989-54 (483 nM). RTI5989-61 and RTI5989-62 were fully efficacious, but had intrinsic efficacy values that were 2.2-3.1 times lower than that of DPDPE and SNC80. Comparison of the binding K(i) in competitively inhibiting [(125)I]IOXY binding to the functional K(i) for delta antagonists [Ki (IOXY)/Ki (GTP-gamma-S)] shows that antagonists might antagonize agonist-evoked neurochemical effects with equal magnitude while occupying different proportions of target receptors.
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Affiliation(s)
- H Xu
- CPS, NIDA, IRP, NIDA, NIH, Baltimore, Maryland 21224, USA
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17
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Baumann MH, Rothman RB, Pablo JP, Mash DC. In vivo neurobiological effects of ibogaine and its O-desmethyl metabolite, 12-hydroxyibogamine (noribogaine), in rats. J Pharmacol Exp Ther 2001; 297:531-9. [PMID: 11303040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Ibogaine is a naturally occurring compound with purported antiaddictive properties. When administered to primates, ibogaine is rapidly o-demethylated to form the metabolite 12-hydroxyibogamine (noribogaine). Peak blood levels of noribogaine exceed those of ibogaine, and noribogaine persists in the bloodstream for at least 1 day. Very few studies have systematically evaluated the neurobiological effects of noribogaine in vivo. In the present series of experiments, we compared the effects of i.v. administration of ibogaine and noribogaine (1 and 10 mg/kg) on motor behaviors, stress hormones, and extracellular levels of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens of male rats. Ibogaine caused dose-related increases in tremors, whereas noribogaine did not. Both ibogaine and noribogaine produced significant elevations in plasma corticosterone and prolactin, but ibogaine was a more potent stimulator of corticosterone secretion. Neither drug altered extracellular DA levels in the nucleus accumbens. However, both drugs increased extracellular 5-HT levels, and noribogaine was more potent in this respect. Results from in vitro experiments indicated that ibogaine and noribogaine interact with 5-HT transporters to inhibit 5-HT uptake. The present findings demonstrate that noribogaine is biologically active and undoubtedly contributes to the in vivo pharmacological profile of ibogaine in rats. Noribogaine is approximately 10 times more potent than ibogaine as an indirect 5-HT agonist. More importantly, noribogaine appears less apt to produce the adverse effects associated with ibogaine, indicating the metabolite may be a safer alternative for medication development.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA.
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18
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Baumann MH, Ayestas MA, Dersch CM, Rothman RB. 1-(m-chlorophenyl)piperazine (mCPP) dissociates in vivo serotonin release from long-term serotonin depletion in rat brain. Neuropsychopharmacology 2001; 24:492-501. [PMID: 11282249 DOI: 10.1016/s0893-133x(00)00221-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Serotonin (5-HT) releasing agents such as d-fenfluramine are known to cause long-term depletion of forebrain 5-HT in animals, but the mechanism of this effect is unknown. In the present study, we examined the relationship between drug-induced 5-HT release and long-term 5-HT depletion in rat brain. The 5-HT-releasing actions of d-fenfluramine and a non-amphetamine 5-HT drug, 1-(m-chlorophenyl)piperazine (mCPP), were compared using in vivo microdialysis in the nucleus accumbens. The ability of d-fenfluramine and mCPP to interact with 5-HT transporters was tested using in vitro assays for [3H]5-HT uptake and radioligand binding. Local infusion of d-fenfluramine or mCPP (1-100 microM) increased extracellular 5-HT, with elevations in dopamine occurring at high doses. Intravenous injection of either drug (1-10 micromol/kg) produced dose-related increases in 5-HT without affecting dopamine. d-Fenfluramine and mCPP exhibited similar potency in their ability to stimulate 5-HT efflux in vivo and interact with 5-HT transporters in vitro. When rats received high-dose d-fenfluramine or mCPP (10 or 30 micromol/kg, i.p., every 2 h, 4 doses), only d-fenfluramine-treated rats displayed long-term 5-HT depletions. Thus, mCPP is a 5-HT releaser that does not appear to cause 5-HT depletion. Our data support the notion that 5-HT release per se may not be sufficient to produce the long-term 5-HT deficits associated with d-fenfluramine and other amphetamines.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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19
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McLamore S, Ullrich T, Rothman RB, Xu H, Dersch C, Coop A, Davis P, Porreca F, Jacobson AE, Rice KC. Effect of N-alkyl and N-alkenyl substituents in noroxymorphindole, 17-substituted-6,7-dehydro-4,5alpha-epoxy-3,14-dihydroxy-6,7:2',3'-indolomorphinans, on opioid receptor affinity, selectivity, and efficacy. J Med Chem 2001; 44:1471-4. [PMID: 11311071 DOI: 10.1021/jm000511w] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The N-alkyl analogues (N-ethyl through N-heptyl), branched N-alkyl chain analogues (N-isopropyl, N-2-methylpropyl, and N-3-methylbutyl), and N-alkenyl analogues ((E)-N-3-methylallyl (crotyl), N-2-methylallyl, and N-3,3-dimethylallyl) were prepared in the noroxymorphindole series (17-substituted-6,7-dehydro-4,5alpha-epoxy-3,14-dihydroxy-6,7:2',3'-indolomorphinans), and the effect of the N-substituent on opioid receptor affinity, selectivity, and efficacy was examined using receptor binding assays, [(35)S]GTPgammaS efficacy determinations, and smooth muscle functional assays (electrically stimulated mouse vas deferens and guinea pig ileum). All of the compounds acted as opioid antagonists, including those with N-substituents which usually confer either weak agonist-antagonist behavior (N-ethyl) or potent opioid agonist activity (N-pentyl) in morphinan-like ligands which interact with the mu-receptor. Several N-substituted noroxymorphindoles were found to be more mu/delta-selective than naltrindole (NTI). The N-2-methylallylnoroxymorphindole, in particular, was found to be more selective than NTI in receptor binding assays (mu/delta = 1700 vs 120; kappa/delta = 810 vs 140), as an antagonist in the GTPgammaS assay (mu/delta = 170 vs 140; kappa/delta = 620 vs 160), and considerably more selective than NTI in the functional assays (mu/delta > 2200 vs 90). It also had high affinity for the delta-opioid receptor (K(i) = 4.7 nM in the binding assay) and high antagonist potency (1.2 nM in the GTPgammaS assay; 8.9 nM in the MVD assay).
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MESH Headings
- Animals
- Binding, Competitive
- Electric Stimulation
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Guinea Pigs
- Ileum/drug effects
- Ileum/physiology
- In Vitro Techniques
- Male
- Mice
- Morphinans/chemical synthesis
- Morphinans/chemistry
- Morphinans/metabolism
- Morphinans/pharmacology
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Narcotic Antagonists
- Radioligand Assay
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Structure-Activity Relationship
- Vas Deferens/drug effects
- Vas Deferens/physiology
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Affiliation(s)
- S McLamore
- Laboratory of Medicinal Chemistry, Building 8, Room B1-23, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA
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20
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Thomas JB, Herault XM, Rothman RB, Atkinson RN, Burgess JP, Mascarella SW, Dersch CM, Xu H, Flippen-Anderson JL, George CF, Carroll FI. Factors influencing agonist potency and selectivity for the opioid delta receptor are revealed in structure-activity relationship studies of the 4-[(N-substituted-4-piperidinyl)arylamino]-N,N-diethylbenzamides. J Med Chem 2001; 44:972-87. [PMID: 11300879 DOI: 10.1021/jm000427g] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A study of the effect of transposition of the internal nitrogen atom for the adjacent benzylic carbon atom in delta-selective agonists such as BW373U86 (1) and SNC-80 (2) has been undertaken. It was shown that high-affinity, fully efficacious, and delta opioid receptor-selective compounds can be obtained from this transposition. In addition to the N,N-diethylamido group needed as the delta address, the structural features identified to promote delta receptor affinity in the set of compounds studied included a cis relative stereochemistry between the 3- and 4-substituents in the piperidine ring, a trans-crotyl or allyl substituent on the basic nitrogen, the lack of a 2-methyl group in the piperidine ring, and either no substitution or hydroxyl substitution in the aryl ring not substituted with the N,N-diethylamido group. Structural features found to be important for mu affinity include hydroxyl substitution in the aryl ring, the presence of a 2-methyl group in a cis relative relationship to the 4-amino group as well as N-substituents such as cyclopropylmethyl. It was also determined that mu receptor affinity could be increased while maintaining delta receptor affinity, especially when hydroxyl-substituted compounds are considered. Additionally, it was discovered that the somewhat lower mu/delta selectivities observed for the piperidine compounds relative to the piperazine-based ligands appear to arise as a consequence of the carbon-nitrogen transposition which imparts an overall lower delta and higher mu affinity to the piperidine-based ligands. This higher affinity for the mu receptor, apparently intrinsic to the piperidine-based compounds, suggests that ligands of this class will more easily be converted to mu/delta combination agonists compared to the piperazine ligands such as 1. This is particularly important since analogues of 1, which show both mu- and delta-type activity, are now recognized as important for their strong analgesia and cross-canceling of many of the side effects found in agonists operating exclusively from either the delta or mu opioid receptor.
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Affiliation(s)
- J B Thomas
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, North Carolina 27709, USA
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21
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Pepper JP, Baumann MH, Ayestas M, Rothman RB. Inhibition of MAO-A fails to alter cocaine-induced increases in extracellular dopamine and norepinephrine in rat nucleus accumbens. Brain Res Mol Brain Res 2001; 87:184-9. [PMID: 11245920 DOI: 10.1016/s0169-328x(01)00013-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Monoamine oxidase (MAO) inhibitors are being investigated as possible medications for cocaine dependence, but there are potential problems with this approach. In the present study, we tested the hypothesis that inhibition of catecholamine metabolism with the MAO-A inhibitor, clorgyline, might enhance cocaine-induced increases in extracellular dopamine and norepinephrine in rat nucleus accumbens. Male rats were pretreated with clorgyline (1 mg/kg, s.c.) or its saline vehicle (1 ml/kg, s.c.), and microdialysis probes were inserted into previously implanted guide cannulae. After overnight perfusion of the probes in situ, rats received an acute challenge injection of either cocaine (1 mg/kg, i.v.) or its saline vehicle (1 ml/kg, i.v.). Clorgyline pretreatment alone caused significant elevations in basal levels of dialysate norepinephrine but not dopamine. Cocaine administration elicited significant increases in extracellular dopamine and norepinephrine in all groups of rats, and this effect was not altered by clorgyline pretreatment. The 1 mg/kg dose of clorgyline decreased dopamine metabolites in postmortem brain tissue by more than 80%. Our data are consistent with clinical studies that demonstrate pretreatment with the MAO-B selective inhibitor, selegeline, fails to alter cocaine-induced subjective effects in human drug users. Moreover, these findings suggest that adverse consequences related to altered catecholamine transmission would not occur if patients taking phenelzine, a non-selective MAO inhibitor, relapsed and used cocaine.
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Affiliation(s)
- J P Pepper
- Clinical Psychopharmacology Section, Intramural Research Program, NIDA, NIH, P.O. Box 5180, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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22
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Xu H, Hashimoto A, Rice KC, Jacobson AE, Thomas JB, Carroll FI, Lai J, Rothman RB. Opioid peptide receptor studies. 14. Stereochemistry determines agonist efficacy and intrinsic efficacy in the [(35)S]GTP-gamma-S functional binding assay. Synapse 2001; 39:64-9. [PMID: 11071711 DOI: 10.1002/1098-2396(20010101)39:1<64::aid-syn9>3.0.co;2-j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Previous data obtained with the cloned rat mu opioid receptor demonstrated that stereochemistry affects the four parameters of the ligand-receptor interaction: potency (ED(50)), efficacy (maximal stimulation), intrinsic efficacy (effect as a function of receptor occupation), and binding affinity. This study evaluated the activities of structurally diverse opioid receptor ligands in the [(35)S]GTP-gamma-S binding assay, comparing the relationship between receptor binding, activation, efficacy, and intrinsic efficacy. The data, obtained with cloned rat mu receptors, demonstrated that an analgetic, (-)-5-m-hydroxyphenyl-2-methylmorphan (NIH8508), and its (+)-isomer (NIH8509), behave as partial agonists, but had different intrinsic efficacy in the [(35)S]GTP-gamma-S binding assay. Replacement of the methyl group with the phenethyl group on the piperidine nitrogen of NIH8508 and NIH8509 [(1R,5S)-AH019 and (1S, 5R)-AH019] increased affinity for the mu receptor and eliminated any agonist effect, supporting the hypothesis that certain structural features make these compounds antagonists. These study also show that all of the fully efficacious mu agonists studied here had high levels of intrinsic efficacy, producing a 50% response at about 10% receptor occupancy. Comparison of the binding K(i) in competitively inhibiting [(125)I]IOXY binding to the functional K(i) for opioid antagonists [K(i)(IOXY)/K(i)(GTP-gamma-S)] provides more detailed evidence that the [(35)S]GTP-gamma-S binding assay can be used to reliably determine apparent functional antagonist K(i) values in addition to agonist ED(50), efficacy and intrinsic efficacy.
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Affiliation(s)
- H Xu
- CPS, DIR, NIDA, Baltimore, Maryland 21224, USA
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23
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Rothman RB, Baumann MH, Dersch CM, Romero DV, Rice KC, Carroll FI, Partilla JS. Amphetamine-type central nervous system stimulants release norepinephrine more potently than they release dopamine and serotonin. Synapse 2001; 39:32-41. [PMID: 11071707 DOI: 10.1002/1098-2396(20010101)39:1<32::aid-syn5>3.0.co;2-3] [Citation(s) in RCA: 651] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A large body of evidence supports the hypothesis that mesolimbic dopamine (DA) mediates, in animal models, the reinforcing effects of central nervous system stimulants such as cocaine and amphetamine. The role DA plays in mediating amphetamine-type subjective effects of stimulants in humans remains to be established. Both amphetamine and cocaine increase norepinephrine (NE) via stimulation of release and inhibition of reuptake, respectively. If increases in NE mediate amphetamine-type subjective effects of stimulants in humans, then one would predict that stimulant medications that produce amphetamine-type subjective effects in humans should share the ability to increase NE. To test this hypothesis, we determined, using in vitro methods, the neurochemical mechanism of action of amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), (+)-methamphetamine, ephedrine, phentermine, and aminorex. As expected, their rank order of potency for DA release was similar to their rank order of potency in published self-administration studies. Interestingly, the results demonstrated that the most potent effect of these stimulants is to release NE. Importantly, the oral dose of these stimulants, which produce amphetamine-type subjective effects in humans, correlated with the their potency in releasing NE, not DA, and did not decrease plasma prolactin, an effect mediated by DA release. These results suggest that NE may contribute to the amphetamine-type subjective effects of stimulants in humans.
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Affiliation(s)
- R B Rothman
- Clinical Psychopharmacology Section, Intramural Research Program, NIDA, NIH, Baltimore, Maryland 21224, USA.
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24
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Gu XH, Yu H, Jacobson AE, Rothman RB, Dersch CM, George C, Flippen-Anderson JL, Rice KC. Design, synthesis, and monoamine transporter binding site affinities of methoxy derivatives of indatraline. J Med Chem 2000; 43:4868-76. [PMID: 11123996 DOI: 10.1021/jm000329v] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of methoxy-containing derivatives of indatraline 13a-f and 17 were synthesized, and their binding affinities for the dopamine, serotonin, and norepinephrine transporter binding sites were determined. Introduction of a methoxy group to indatraline affected its affinity and selectivity greatly. Except for the 4-methoxy derivative 13a,which had the same high affinity at the dopamine transporter binding site as indatraline, the other methoxy-containing analogues (13b-f and 17) exhibited lower affinity than indatraline for the three transporter binding sites. However, some of the analogues were more selective than indatraline, and the 6-methoxy derivative 13c displayed the highest affinity for both the serotonin and norepinephrine transporters. This compound retained reasonable affinity for the dopamine transporter and is a promising template for the development of a long-acting inhibitor of monoamine transporters. Such inhibitors have potential as medications for treatment, as a substitution medication, or for prevention of the abuse of methamphetamine-like stimulants.
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Affiliation(s)
- X H Gu
- Laboratory of Medicinal Chemistry, Building 8, Room B1-23, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA
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25
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Zhang Y, Rothman RB, Dersch CM, de Costa BR, Jacobson AE, Rice KC. Synthesis and transporter binding properties of bridged piperazine analogues of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR 12909). J Med Chem 2000; 43:4840-9. [PMID: 11123994 DOI: 10.1021/jm000300r] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of analogues related to 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine (2) and 1-¿2-[bis(4-fluorophenyl)methoxy]ethyl¿-4-(3-phenylpropyl)piperazine (3) (GBR 12935 and GBR 12909, respectively), in which the piperazine moiety was replaced by bridged piperazines for structural rigidity, has been designed, synthesized, and evaluated for their ability to bind to the dopamine transporter (DAT) and to inhibit the uptake of (3)H-labeled dopamine (DA). The binding data indicated that compounds 7 and 11, the N-methyl- and N-propylphenyl-3,8-diaza[3.2. 1]bicyclooctane analogues of 3, showed high affinity for the DAT (IC(50) = 8.0 and 8.2 nM, respectively), and 7 had high selectivity at the DAT relative to the serotonin transporter (SERT) (88- and 93-fold for binding and reuptake, respectively). They also displayed linear activity in DA uptake inhibition, possessing a similar binding and reuptake inhibition profile to 3. The N-indolylmethyl analogue 16 showed the highest affinity (IC(50) = 1.4 nM) of the series, with a 6-fold increase over its corresponding N-phenypropyl derivative 11. Interestingly, this compound exhibited a high ratio (29-fold) of IC(50) for the inhibition of DA reuptake versus binding to the DAT. Replacing the piperazine moiety of 2 and 3 with (1S, 4S)-2,5-diazabicyclo[2.2.1]heptane resulted in compounds 23-26, which showed moderate to poor affinity (IC(50) = 127-1170 nM) for the DAT. Substitution of the homopiperazine moiety of 4 with a more rigid 3,9-diazabicyclo[4.2.1]nonane gave compounds 28-33. However, the binding data showed that compound 32 displayed a 10-fold decrease in affinity at the DAT and a 100-fold decrease in selectivity at the DAT relative to the SERT compared to its corresponding homopiperazine compound 4.
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Affiliation(s)
- Y Zhang
- Laboratory of Medicinal Chemistry, Building 8, Room B1-22, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA
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26
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Rothman RB, Baumann MH, Savage JE, Rauser L, McBride A, Hufeisen SJ, Roth BL. Evidence for possible involvement of 5-HT(2B) receptors in the cardiac valvulopathy associated with fenfluramine and other serotonergic medications. Circulation 2000; 102:2836-41. [PMID: 11104741 DOI: 10.1161/01.cir.102.23.2836] [Citation(s) in RCA: 515] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Serotonergic medications with various mechanisms of action are used to treat psychiatric disorders and are being investigated as treatments for drug dependence. The occurrence of fenfluramine-associated valvular heart disease (VHD) has raised concerns that other serotonergic medications might also increase the risk of developing VHD. We hypothesized that fenfluramine or its metabolite norfenfluramine and other medications known to produce VHD have preferentially high affinities for a particular serotonin receptor subtype capable of stimulating mitogenesis. METHODS AND RESULTS Medications known or suspected to cause VHD (positive controls) and medications not associated with VHD (negative controls) were screened for activity at 11 cloned serotonin receptor subtypes by use of ligand-binding methods and functional assays. The positive control drugs were (+/-)-fenfluramine; (+)-fenfluramine; (-)-fenfluramine; its metabolites (+/-)-norfenfluramine, (+)-norfenfluramine, and (-)-norfenfluramine; ergotamine; and methysergide and its metabolite methylergonovine. The negative control drugs were phentermine, fluoxetine, its metabolite norfluoxetine, and trazodone and its active metabolite m-chlorophenylpiperazine. (+/-)-, (+)-, and (-)-Norfenfluramine, ergotamine, and methylergonovine all had preferentially high affinities for the cloned human serotonin 5-HT(2B) receptor and were partial to full agonists at the 5-HT(2B) receptor. CONCLUSIONS Our data imply that activation of 5-HT(2B) receptors is necessary to produce VHD and that serotonergic medications that do not activate 5-HT(2B) receptors are unlikely to produce VHD. We suggest that all clinically available medications with serotonergic activity and their active metabolites be screened for agonist activity at 5-HT(2B) receptors and that clinicians should consider suspending their use of medications with significant activity at 5-HT(2B) receptors.
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Affiliation(s)
- R B Rothman
- Clinical Psychopharmacology Section, Division of Intramural Research, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA
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Abstract
Three metabolites of diethylpropion (1), (+/-)-2-ethylamino-1-phenyl-propan-1-one (2), (1R,2S)-(-)-N,N-diethylnorephedrine (3a) and (1S,2R)-(-)-N,N-diethylnorephedrine (3b) were synthesized. Their uptake and release effects with biogenic amine transporters were evaluated. A major finding of this study is that the in vivo activity of diethylpropion on biogenic amine transporters is most likely due to metabolite 2 as diethylpropion (1) and the metabolites 3a and 3b showed little or no effect in the assays studied. These studies also revealed that 2 acted as a substrate at the norepinephrine (IC50 = 99 nM) and serotonin transporters (IC50 = 2118 nM) and an uptake inhibitor at the dopamine transporter (IC50 = 1014 nM). The potent action of 2 at the NE transporter supports the hypothesis that amphetamine-type subjective effects may be mediated in part by brain norepinephrine.
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Affiliation(s)
- H Yu
- Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA
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Partilla JS, Dersch CM, Yu H, Rice KC, Rothman RB. Neurochemical neutralization of amphetamine-type stimulants in rat brain by the indatraline analog (-)-HY038. Brain Res Bull 2000; 53:821-6. [PMID: 11179849 DOI: 10.1016/s0361-9230(00)00419-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amphetamine-type stimulants are substrates for the proteins that serve as transporters for the biogenic amines dopamine (DA), serotonin (5HT), and norepinephrine (NE) and release these neurotransmitters from neurons located in the peripheral and central nervous system. Using indatraline as a lead compound, we sought to develop a long-acting depot medication that would neutralize the deleterious effects of amphetamine-type stimulants. Our first efforts produced (+/-)-HY038, and its two stereoisomers, which are hydroxy-substituted analog of indatraline. The K(i) values for [(3)H]DA reuptake inhibition by (-)-HY038 and (+)-HY038 were 3.2 +/- 0.1 and 32 +/- 1 nM. Similar results were obtained for [(3)H]5HT reuptake inhibition. (-)-HY038 and (+)-HY038 were slightly less potent at inhibiting [(3)H]NE reuptake (K(i) values of 20 +/- 2 and 159 +/- 12 nM). Low doses of (-)-HY038 blunted the ability of AMPH to release [(3)H]DA by shifting the AMPH dose-response curve to the right in a dose-dependent manner. (-)-HY038 also inhibited the ability of (+)-methamphetamine and (+/-)-3,4-methylenedioxymethamphetamine ((+/-)-MDMA) to release [(3)H]DA. Low doses of (-)-HY038 blunted the ability of these stimulants to release [(3)H]NE and [(3)H]5HT by shifting their dose-response curves to the right in a manner similar to that seen for inhibition of [(3)H]DA release. These data indicate that (-)-HY038 inhibits the ability of AMPH, (+)-methamphetamine and (+/-)-MDMA to release DA, NE, and 5HT and therefore might have the potential to neutralize the neurotoxic and cardiovascular side-effects of substrate-type stimulants.
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Affiliation(s)
- J S Partilla
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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29
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Rothman RB. The age-adjusted mortality rate from primary pulmonary hypertension, in age range 20 to 54 years, did not increase during the years of peak "phen/fen" use. Chest 2000; 118:1516-7. [PMID: 11083718 DOI: 10.1378/chest.118.5.1516] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Abstract
Administration of d,l-fenfluramine (FEN), or the more active isomer d-fenfluramine (dFEN), causes long-term depletion of forebrain serotonin (5-HT) in animals. The mechanism underlying FEN-induced 5-HT depletion is not known, but appears to involve 5-HT transporters (SERTs) in the brain. Some investigators have postulated that 5-HT release evoked by FEN is responsible for the deleterious effects of the drug. In the present work, we sought to examine the relationship between drug-induced 5-HT release and long-term 5-HT depletion. The acute 5-HT-releasing effects of dFEN and the non-amphetamine 5-HT agonist 1-(m-chlorophenyl)piperazine (mCPP) were evaluated using in vivo microdialysis in rat nucleus accumbens. The ability of dFEN and mCPP to interact with SERTs was assessed using in vitro assays for [3H]-transmitter uptake and release in rat forebrain synaptosomes. Drugs were subsequently tested for potential long-lasting effects on brain tissue 5-HT after repeated dosing (2.7 or 8.1 mg/kg, ip x 4). dFEN and mCPP were essentially equipotent in their ability to stimulate acute 5-HT release in vivo and in vitro. Both drugs produced very selective effects on 5-HT with minimal effects on dopamine. Interestingly, when dFEN or mCPP was administered repeatedly, only dFEN caused long-term 5-HT depletion in the forebrain at 2 weeks later. These data suggest that acute 5-HT release per se does not mediate the long-term 5-HT depletion associated with dFEN. We hypothesize that dFEN and other amphetamine-type releasers gain entrance into 5-HT neurons via interaction with SERTs. Once internalized in nerve terminals, drugs accumulate to high concentrations, causing damage to cells. The relevance of this hypothesis for explaining clinical side effects of FEN and dFEN, such as cardiac valvulopathy and primary pulmonary hypertension, warrants further study.
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Affiliation(s)
- M H Baumann
- Medications Development Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA.
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Rothman RB, Partilla JS, Dersch CM, Carroll FI, Rice KC, Baumann MH. Methamphetamine dependence: medication development efforts based on the dual deficit model of stimulant addiction. Ann N Y Acad Sci 2000; 914:71-81. [PMID: 11085310 DOI: 10.1111/j.1749-6632.2000.tb05185.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Converging lines of evidence indicate that withdrawal from prolonged exposure to stimulants and alcohol results in synaptic deficits of both dopamine (DA) and serotonin (5-HT). According to the dual deficit model proposed by the authors, DA dysfunction during cocaine or alcohol withdrawal underlies anhedonia and psychomotor retardation, whereas 5-HT dysfunction gives rise to depressed mood, obsessional thoughts, and lack of impulse control. This model predicts that pharmacotherapies which correct only one of the two neurochemical deficits will not be effective. On the other hand, pharmacotherapies which "correct" both of the proposed DA and 5-HT abnormalities should be effective in treating stimulant and alcohol dependence. This paper reviews two approaches, based on the dual deficit model, taken by our laboratory to develop medications to treat stimulant abuse.
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Affiliation(s)
- R B Rothman
- Clinical Psychopharmacology Section, Intramural Research Program, NIDA, NIH, Baltimore, Maryland 21224, USA.
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32
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Baumann MH, Pablo JP, Ali SF, Rothman RB, Mash DC. Noribogaine (12-hydroxyibogamine): a biologically active metabolite of the antiaddictive drug ibogaine. Ann N Y Acad Sci 2000; 914:354-68. [PMID: 11085335 DOI: 10.1111/j.1749-6632.2000.tb05210.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ibogaine (IBO) is a plant-derived alkaloid that is being evaluated as a possible medication for substance use disorders. When administered peripherally to monkeys and humans, IBO is rapidly converted to an o-demethylated metabolite, 12-hydroxyibogamine (NORIBO). We have found in rats that peak blood levels of NORIBO can exceed those of the parent compound, and NORIBO persists in the bloodstream for at least 24 h. Surprisingly few studies have examined the in vivo biological activity of NORIBO. In the present series of experiments, we compared the effects of intravenous (i.v.) administration of IBO and NORIBO (1 and 10 mg/kg) on unconditioned behaviors, circulating stress hormones, and extracellular levels of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens of male rats. IBO caused dose-related increases in tremors and forepaw treading, whereas NORIBO did not. Both IBO and NORIBO produced significant elevations in plasma corticosterone and prolactin, but IBO was more potent as a stimulator of corticosterone secretion. Neither drug affected extracellular DA levels in the nucleus accumbens. However, both IBO and NORIBO increased extracellular 5-HT levels, and NORIBO was more potent in this regard. The present data demonstrate that NORIBO is biologically active and undoubtedly contributes to the in vivo pharmacological profile of IBO in rats. Most importantly, NORIBO appears less likely to produce the adverse effects associated with IBO (i.e., tremors and stress-axis activation), suggesting that the metabolite may be a safer alternative for medication development.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, NIDA, NIH, Baltimore, Maryland 21224, USA.
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33
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Furness MS, Zhang X, Coop A, Jacobson AE, Rothman RB, Dersch CM, Xu H, Porreca F, Rice KC. Probes for narcotic receptor-mediated phenomena. 27. Synthesis and pharmacological evaluation of selective delta-opioid receptor agonists from 4-[(alphaR)-alpha-(2S,5R)-4-substituted-2, 5-dimethyl-1-piperazinyl-3-methoxybenzyl]-N,N-diethylbenzamides and their enantiomers. J Med Chem 2000; 43:3193-6. [PMID: 10956228 DOI: 10.1021/jm0001222] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Potent, selective, and efficacious delta-opioid receptor agonists such as (+)-4-[(alphaR)-alpha-(2S,5R)-4-allyl-2, 5-dimethyl-1-piperazinyl-3-methoxybenzyl]-N,N-diethylbenzamide [SNC80, (+)-2] have been found to be useful tools for exploring the structural requirements which are necessary for ligands which interact with the delta-receptor. To determine the necessity for the 4-allyl moiety in (+)-2, this substituent was replaced with a variety of 4-alkyl, 4-arylalkyl, and 4-alkenyl substituents. The corresponding enantiomers of these compounds were also synthesized. The binding affinities for the mu-, delta-, and kappa-opioid receptors and efficacies in the functional GTPgammaS binding assay were determined for the (+)-2 related compounds and their enantiomers. The 4-crotyl analogue was found to have similar delta-receptor affinity and efficacy as (+)-2, but the 4-cyclopropylmethyl analogue, in the functional assay, appeared to be a partial agonist with little antagonist activity.
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Affiliation(s)
- M S Furness
- Laboratory of Medicinal Chemistry, Building 8, Room B1-22, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA
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34
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Thomas JB, Atkinson RN, Rothman RB, Burgess JP, Mascarella SW, Dersch CM, Xu H, Carroll FI. 4-[(8-Alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-diethylbenzamides: high affinity, selective ligands for the delta opioid receptor illustrate factors important to antagonist activity. Bioorg Med Chem Lett 2000; 10:1281-4. [PMID: 10866400 DOI: 10.1016/s0960-894x(00)00209-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The tropane derived compounds, 4-[(8-alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-d iethylbenzamides (5a-d), were synthesized and found to have high affinity and selectivity for the delta receptor. Compounds 5a-d are structurally similar to the full agonist (-)-RTI-5989-54 (3); yet, efficacy studies for compounds in this series (5a-d) reveal greatly diminished agonist activity as well as antagonism not found in piperidine-based compounds like 3.
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Affiliation(s)
- J B Thomas
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, NC 27709, USA
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35
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Baumann MH, Ayestas MA, Dersch CM, Brockington A, Rice KC, Rothman RB. Effects of phentermine and fenfluramine on extracellular dopamine and serotonin in rat nucleus accumbens: therapeutic implications. Synapse 2000; 36:102-13. [PMID: 10767057 DOI: 10.1002/(sici)1098-2396(200005)36:2<102::aid-syn3>3.0.co;2-#] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Combined administration of the amphetamine analogs phentermine and fenfluramine (PHEN/FEN) has been used in the treatment of obesity. While these medications are thought to modulate monoamine transmission, the precise neurochemical effects of the PHEN/FEN mixture have not been extensively studied. To assess the mechanism of PHEN/FEN action, in vivo microdialysis studies were performed in the nucleus accumbens of conscious freely moving rats. A series of amphetamine derivatives including phentermine, chlorphentermine, fenfluramine, and PHEN/FEN (1:1 ratio), were infused locally into the accumbens via reverse-dialysis (1, 10, 100 microM) or injected systemically (1 mg/kg, ip). Dialysate samples were assayed for dopamine (DA) and serotonin (5-HT) by high-performance liquid chromatography with electrochemical detection. When infused locally, phentermine preferentially increased extracellular DA, whereas fenfluramine selectively increased extracellular 5-HT. Local administration of chlorphentermine or the PHEN/FEN mixture caused parallel elevations of both transmitters. Analogous results were obtained when the drugs were injected systemically. Phentermine stimulated robust locomotor activity in mice, whereas chlorphentermine and fenfluramine did not. PHEN/FEN caused modest locomotor stimulation after a low dose, but had no effect at the highest dose. Accumulating evidence suggests that chronic drug and alcohol abuse is associated with deficits in both DA and 5-HT neuronal function. Thus, dual activation of DA and 5-HT neurotransmission with monoamine releasing agents may be an effective treatment strategy for substance use disorders, as well as for obesity. Synapse 36:102-113, 2000. Published 2000 Wiley-Liss, Inc.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA
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36
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Abstract
Ibogaine is a plant-derived alkaloid with putative 'anti-addictive' properties. Although ibogaine binds to multiple targets in the brain, recent evidence suggests the drug acts as an N-methyl-D-aspartate (NMDA) antagonist similar to MK-801. The purpose of the present study was to compare neurochemical and neuroendocrine effects of ibogaine and MK-801 in vivo. Male rats received either i.p. saline, ibogaine (10 and 100 mg/kg), or MK-801 (0.1 and 1 mg/kg). Groups of rats (N=6-8/group) were decapitated 30 or 60 min after injection. Brains were harvested for analysis of dopamine (DA) and its metabolites, while trunk blood was collected for analysis of plasma corticosterone and prolactin. Ibogaine produced marked dose-dependent reductions in tissue DA with concurrent increases in the metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). This profile of ibogaine-induced effects on DA metabolism was consistently observed in the cortex, striatum, olfactory tubercle, and hypothalamus. MK-801, on the other hand, did not reduce DA levels in any brain region but did cause modest region-specific elevations in DA metabolites. Ibogaine and MK-801 caused comparable elevations in circulating corticosterone, but only ibogaine increased prolactin. The present findings show that the effects of ibogaine on DA neurotransmission and neuroendocrine secretion are not fully mimicked by MK-801. Thus, the wide spectrum of in vivo actions of ibogaine can probably not be explained simply on the basis of antagonism at NMDA receptors.
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Affiliation(s)
- M H Baumann
- Medications Discovery Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, PO Box 5180, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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37
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Abstract
As expected on the basis of published research in both humans and animals, treatment with phentermine/fenfluramine lowers plasma 5-hydroxytryptamine [corrected], whereas treatment with phentermine had no significant effect. In light of these findings, future research should focus on mechanisms other than increased plasma 5-hydroxytryptamine [corrected] to explain how fenfluramine increases the risk of primary pulmonary hypertension and valvular heart disease.
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Rothman RB, Gorelick DA, Heishman SJ, Eichmiller PR, Hill BH, Norbeck J, Liberto JG. An open-label study of a functional opioid kappa antagonist in the treatment of opioid dependence. J Subst Abuse Treat 2000; 18:277-81. [PMID: 10742642 DOI: 10.1016/s0740-5472(99)00074-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Several lines of evidence, including the well-established observation that kappa opiate agonists produce dysphoria and psychotomimetic effects in humans, suggest that dysfunction of the endogenous kappa opioid system may contribute to opioid and cocaine addiction. The objective of this open-label study was to determine the effectiveness of a functional kappa antagonist as a treatment for opioid dependence. This was accomplished by combining a partial mu agonist/kappa antagonist (buprenorphine, 4 mg, sublingual) with a mu antagonist (naltrexone, 50 mg by mouth), theoretically leaving kappa antagonism as the major medication effect. Subjects were treatment-seeking heroin-dependent (as per Diagnostic and Statistical Manual of Mental Disorders, 4th ed.) men (41 +/- 7 years old; 19 +/- 8 years heroin use) eligible for methadone maintenance. After inpatient detoxification and a naloxone-challenge test to verify that they were not physically dependent on opioids, subjects received naltrexone. Starting on the fourth day, patients also received liquid buprenorphine. All patients received medication at the clinic 6 days per week and a full program of psychosocial treatment. The major endpoints of the study were: pupil diameter to determine if the mu agonist effects of buprenorphine were blocked by naltrexone, urine toxicology, and retention in treatment. Five patients (33%) completed the 3-month study. Four were abstinent from opioids and cocaine for the entire study, and one was abstinent from opioids and cocaine for the last 9 weeks. Six subjects dropped out due to either minor side effects or disliking the sensation of sublingual buprenorphine. There were no significant changes in pupillary diameter. The positive response to treatment exceeds that expected from naltrexone alone (90% dropout). These promising results suggest that controlled studies of this medication combination should be conducted.
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Affiliation(s)
- R B Rothman
- National Institute on Drug Abuse, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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Rothman RB, Partilla JS, Baumann MH, Dersch CM, Carroll FI, Rice KC. Neurochemical neutralization of methamphetamine with high-affinity nonselective inhibitors of biogenic amine transporters: a pharmacological strategy for treating stimulant abuse. Synapse 2000; 35:222-7. [PMID: 10657029 DOI: 10.1002/(sici)1098-2396(20000301)35:3<222::aid-syn7>3.0.co;2-k] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The abuse of methamphetamine (METH) and other amphetamine-like stimulants is a growing problem in the United States. METH is a substrate for the 12-transmembrane proteins which function as transporters for the biogenic amines dopamine (DA), serotonin (5-HT), and norepinephrine (NE). Increased release of CNS DA is thought to mediate the addictive effects of METH, whereas increased release of NE in both the peripheral and CNS is thought to mediate its cardiovascular effects. The neurotoxic effects of METH on both dopaminergic and serotonergic nerves requires the transport of METH into the nerve terminals. Thus, transport of METH into nerve terminals is the crucial first step in the production of METH-associated pharmacological and toxicological effects. A single molecular entity which would block the transport of METH at all three biogenic amine transporters might function to neurochemically neutralize METH. This agent would ideally be a high-affinity slowly dissociating agent at all three transporters, and also be amenable to formulation as a long-acting depot medication, such as has been accomplished with an analog of GBR12909. As a first step towards developing such an agent, we established an in vitro assay which selectively detects transporter substrates and used this assay to profile the ability of a lead compound, indatraline, to block the releasing effects of METH and MDMA at the DA, 5-HT, and NE transporters. The major finding reported here is that indatraline blocks the ability of METH and MDMA to release these neurotransmitters. Synapse 35:222-227, 2000. Published 2000 Wiley-Liss, Inc.
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Affiliation(s)
- R B Rothman
- Clinical Psychopharmacology Section, Intramural Research Program, NIDA, NIH, Baltimore, Maryland, USA.
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40
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Heyliger SO, Ni Q, Rothman RB. Resolution of two [(35)S]GTP-gamma-S binding sites and their response to chronic morphine treatment: a binding surface analysis. Brain Res Bull 2000; 51:357-62. [PMID: 10704787 DOI: 10.1016/s0361-9230(99)00261-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanisms by which prolonged exposure to morphine leads to tolerance are not fully understood. We investigated the effects of etorphine (ET) on [(35)S]guanosine 5'-(-thio)-triphosphate ([(35)S]GTP-gamma-S) binding in brains of rats made tolerant to morphine via the implantation of morphine (or placebo) pellets. Binding surface analysis was used to characterize the interactions of ET, Gpp(Np)H and GTP-gamma-S with sites labeled by [(35)S]GTP-gamma-S. Data sets were fitted to one- and two-site binding models using the nonlinear least squares curve fitting program MLAB-PC (Civilized Software, Bethesda, MD, USA). Two binding sites were readily resolved. Chronic morphine significantly increased the B(max) and K(d) of the high affinity binding site. ET stimulated [(35)S]GTP-gamma-S binding in placebo membranes via an increase in the B(max) of the high affinity binding site. In contrast, ET stimulated [(35)S]GTP-gamma-S in chronic morphine membranes via a large decrease in the K(d) of the high affinity site. These results suggest that chronic morphine treatment alters the mechanism by which ET stimulates [(35)S]GTP-gamma-S binding to G-proteins. Since proper G-protein/receptor coupling increases [(35)S]GTP-gamma-S binding via an increase in B(max) values, these results suggest that opioid receptors in chronic morphine membranes are not normally coupled to G-proteins. These findings corroborate earlier studies that reported changes in G-protein function in morphine tolerant animals.
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Affiliation(s)
- S O Heyliger
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Zhang X, Rice KC, Calderon SN, Kayakiri H, Smith L, Coop A, Jacobson AE, Rothman RB, Davis P, Dersch CM, Porreca F. Probes for narcotic receptor mediated phenomena. 26. Synthesis and biological evaluation of diarylmethylpiperazines and diarylmethylpiperidines as novel, nonpeptidic delta opioid receptor ligands. J Med Chem 1999; 42:5455-63. [PMID: 10639287 DOI: 10.1021/jm9903895] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We recently reported (+)-4-¿(alphaR)-alpha-¿(2S,5R)-4-allyl-2, 5-dimethyl-1-piperazinyl¿-3-methoxybenzyl-N,N-diethylbenzamide (1b, SNC80) as a novel nonpeptidic delta receptor agonist and explored the structure-activity relationships (SAR) of a series of related derivatives. We have found that delta binding activities and selectivity showed little change when the 3-methoxy group in 1b was removed or replaced by the other substituents, whereas the N, N-diethylbenzamide group is important for interaction with the delta receptor. Extensive modification of the piperazine nucleus led to the synthesis of a new series of N, N-diethyl(alpha-piperazinylbenzyl)benzamides (2, 3a-e), N, N-diethyl(alpha-piperidinyl or piperidinylidenebenzyl)benzamides (4a, 5a-c, 6a-b), and related derivatives (4b, 7a-c). Several compounds (2, 3a, 3e, 6a) strongly bound to the delta receptor with K(i) values in the low nanomolar range. On the other hand, the binding affinities of these compounds for the mu and kappa receptors were negligible, indicating excellent delta opioid receptor subtype selectivity. The two nitrogen atoms on the piperazine nucleus showed different SAR in the interaction of this series of compounds at the delta receptor. Nitrogen N(4) appears to be an important structural element and is essential for electrostatic interaction, while N(1) seems to be unnecessary for recognition at the delta receptor.
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Affiliation(s)
- X Zhang
- Laboratory of Medicinal Chemistry, Building 8, Room B1-23, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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42
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Coop A, Pinto J, Wang L, McCullough K, Rothman RB, Dersch C, Jacobson AE, Rice KC. Delta opioid binding selectivity of 3-ether analogs of naltrindole. Bioorg Med Chem Lett 1999; 9:3435-8. [PMID: 10617086 DOI: 10.1016/s0960-894x(99)00622-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Masking of the 3-phenol of naltrindole as a range of ethers caused a decrease in binding affinity at all three opiate receptors (mu, kappa, delta), however for the methyl ether, the reduction in affinity at both mu and kappa was greater than at delta, thereby increasing delta binding selectivity.
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Affiliation(s)
- A Coop
- Laboratory of Medicinal Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, Bethesda, MD 20892, USA
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43
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Heyliger SO, Jackson C, Rice KC, Rothman RB. Opioid peptide receptor studies. 10. Nor-BNI differentially inhibits kappa receptor agonist-induced G-protein activation in the guinea pig caudate: further evidence of kappa receptor heterogeneity. Synapse 1999; 34:256-65. [PMID: 10529720 DOI: 10.1002/(sici)1098-2396(19991215)34:4<256::aid-syn2>3.0.co;2-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
There is strong evidence supporting the existence of multiple kappa receptors. Previous studies proposed that U69,593 and (+)-tifluadom act on different kappa receptor subtypes, kappa(1) (kappa(1)) and kappa(2) (kappa(2)), respectively. In this study, we investigated the effects of the kappa selective antagonist nor-binaltorphimine (Nor-BNI) on U69,593- and (+)-tifluadom-induced receptor-mediated stimulation of [(35)S]-GTP-gamma-S binding in the guinea pig caudate. The IC(50) value of Nor-BNI in the presence of a stimulating concentration of U69,593 (1 microM) was 0.19+/-0.02; while the IC(50) for Nor-BNI in the presence of (+)-tifluadom (1 microM) was 13.9+/- 1.62 nM. The mu-opioid receptor antagonist CTAP (10,000 nM) significantly reduced (+)-tifluadom-stimulated [(35)S]-GTP-gamma-S binding in rat brain sections and guinea pig brain membranes, indicating that (+)-tifluadom has mu agonist activity. Under conditions in which the mu agonist activity of (+)-tifluadom was blocked by 1000 nM CTAP the Ki value for Nor-BNI for inhibition of U69,593-stimulated [(35)S]-GTP-gamma-S binding was 0.036+/-.004 nM, whereas, its Ki value for the (+)-tifluadom-stimulated [(35)S]-GTP-gamma-S binding was 0.27+/-.015 nM. These results suggest that (+)-tifluadom and U69,593 activate pharmacologically different receptors. This study provides functional evidence in support of kappa receptor heterogeneity.
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MESH Headings
- Animals
- Benzeneacetamides
- Benzodiazepines/antagonists & inhibitors
- Benzodiazepines/pharmacology
- Brain/drug effects
- Brain/metabolism
- Caudate Nucleus/drug effects
- Caudate Nucleus/metabolism
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- GTP-Binding Proteins/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Guinea Pigs
- In Vitro Techniques
- Inhibitory Concentration 50
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Oligopeptides/pharmacology
- Peptide Fragments
- Peptides/pharmacology
- Pyrrolidines/antagonists & inhibitors
- Pyrrolidines/pharmacology
- Rats
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Somatostatin
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Affiliation(s)
- S O Heyliger
- Clinical Psychopharmacology Section, Division of Intramural Research, National Institute on Drug Abuse, National Institutes of Health, P. O. Box 5180, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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44
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Thomas JB, Atkinson RN, Herault XM, Rothman RB, Mascarella SW, Dersch CM, Xu H, Horel RB, Carroll FI. Optically pure (-)-4-[(N-allyl-3-methyl-4-piperidinyl)phenyl-amino]-N,N-diethylbenzami de displays selective binding and full agonist activity for the delta opioid receptor. Bioorg Med Chem Lett 1999; 9:3347-50. [PMID: 10612597 DOI: 10.1016/s0960-894x(99)00613-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The optical isomers of 4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide+ ++ (3) have been prepared and tested in both binding and functional assays. The data show that (-)-3 is responsible for the delta opioid activity demonstrated by the racemic material. This compound displays a binding affinity of 5.5 nM for the delta opioid receptor as well as a 470-fold delta versus mu selectivity. Importantly, (-)-3 is a full agonist at the delta receptor in comparison with SNC-80 (2). Taken together, the data suggest that (-)-3 behaves more like the prototypical delta agonists, BW373U86 or SNC-80, and less like the peptidomimetic compound SL-3111 (5).
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Affiliation(s)
- J B Thomas
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, NC 27709, USA
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45
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Lewis DB, Matecka D, Zhang Y, Hsin LW, Dersch CM, Stafford D, Glowa JR, Rothman RB, Rice KC. Oxygenated analogues of 1-[2-(Diphenylmethoxy)ethyl]- and 1-[2-[Bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazines (GBR 12935 and GBR 12909) as potential extended-action cocaine-abuse therapeutic agents. J Med Chem 1999; 42:5029-42. [PMID: 10585212 DOI: 10.1021/jm990291q] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An investigation into the preparation of potential extended-release cocaine-abuse therapeutic agents afforded a series of compounds related to 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine (1a) and 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (1b) (GBR 12935 and GBR 12909, respectively), which were designed, synthesized, and evaluated for their ability to bind to the dopamine transporter (DAT) and to inhibit the uptake of [(3)H]-labeled dopamine (DA). The addition of hydroxy and methoxy substituents to the benzene ring on the phenylpropyl moiety of 1a-1d resulted in a series of potent and selective ligands for the DAT (analogues 5-28). The hydroxyl groups were included to incorporate a medium-chain carboxylic acid ester into the molecules, to form oil-soluble prodrugs, amenable to "depot" injection techniques. The introduction of an oxygen-containing functionality to the propyl side chain provided ketones 29 and 30, which demonstrated greatly reduced affinity for the DAT and decreased potency in inhibiting the uptake of [(3)H]DA, and benzylic alcohols 31-36, which were highly potent and selective at binding to the DAT and inhibiting [(3)H]DA uptake. The enantiomers of 32 (34 and 36) were practically identical in biological testing. Compounds 1b, 32, 34, and 36 all demonstrated the ability to decrease cocaine-maintained responding in monkeys without affecting behaviors maintained by food, with 34 and 36 equipotent to each other and both more potent in behavioral tests than the parent compound 1b. Intramuscular injections of compound 41 (the decanoate ester of racemate 32) eliminated cocaine-maintained behavior for about a month following one single injection, without affecting food-maintained behavior. The identification of analogues 32, 34, and 36, thus, provides three potential candidates for esterification and formulation as extended-release cocaine-abuse therapeutic agents.
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Affiliation(s)
- D B Lewis
- Laboratory of Medicinal Chemistry, Building 8, Room B1-23, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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46
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Goodman CB, Heyliger S, Emilien B, Partilla JS, Yang HY, Lee CH, Cadet JL, Rothman RB. Chronic exposure to antibodies directed against anti-opiate peptides alter delta-opioid receptor levels. Peptides 1999; 20:1419-24. [PMID: 10698116 DOI: 10.1016/s0196-9781(99)00151-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The development of addictive states in response to chronic opioid use may be regulated partially by the release of endogenous peptides. These anti-opiate peptides (AOP) are secreted or released into the CNS and produce diverse actions that counterbalance the effects of prolonged opiate exposure. Though the mechanism(s) by which these peptides exert their physiological properties remain largely unknown, there is some indication that AOP's modulate opioid receptor levels. In this study, we investigated the effects of chronically infused alpha-melanocyte stimulating hormone (alpha-MSH), dynorphin(1-8) (DYN(1-8)), dynorphin A (DYNA), and NPFF antibodies on delta-opioid receptor expression in rat brains. Quantitative autoradiographic experiments revealed that antibodies directed against alpha-MSH and DYNA produced significant increases in delta receptor levels in the caudate, claustrum, and cingulate cortex of the rat brain. Conversely, NPFF monoclonal antibodies caused significant decreases in the caudate, nucleus accumbens, olfactory tubercle, and cingulate cortex. These results suggest that the density of delta-opioid receptors is affected by changes in the levels of the anti-opioid peptides in the extracelluar fluid in the rat brain.
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Affiliation(s)
- C B Goodman
- Florida A&M University, College of Pharmacy and Pharmaceutical Sciences, Tallahassee, FL 32303, USA.
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47
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Donovan DM, Miner LL, Perry MP, Revay RS, Sharpe LG, Przedborski S, Kostic V, Philpot RM, Kirstein CL, Rothman RB, Schindler CW, Uhl GR. Cocaine reward and MPTP toxicity: alteration by regional variant dopamine transporter overexpression. Brain Res Mol Brain Res 1999; 73:37-49. [PMID: 10581396 DOI: 10.1016/s0169-328x(99)00235-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polygenic factors play important roles in animal models of substance abuse and susceptibility to dopaminergic neurodegeneration. Genetic factors are also likely to contribute to the etiology of human drug abuse disorders, and may alter human vulnerabilities to Parkinsonian neurodegeneration. The dopamine transporter (DAT; SLC6A3) is densely expressed by the dopaminergic midbrain neurons that play central roles in drug reward and is believed to be a primary site of action for cocaine reward. This transporter is necessary for the action of selective dopaminergic neurotoxins, and is uniquely expressed on neurons that are the primary targets of Parkinsonian neurodegeneration. To study possible influences of variant DAT expression on these processes, we have constructed transgenic mice (THDAT) in which tyrosine hydroxylase (TH) promoter sequences drive expression of a rat DAT cDNA variant, increase striatal DAT expression by 20-30%, and provide modest alterations in striatal levels of dopamine and its metabolites. THDAT mice habituate more rapidly to a novel environment than wildtype littermates. These animals display enhanced reward conferred by cocaine, as measured by conditioned place preference. However, locomotor responses to cocaine administration are similar to those of wildtype mice, except at high cocaine doses. THDAT mice display more than 50% greater losses of dopaminergic neurons following a course of MPTP treatment than do wildtype control mice. These results document a model for allelic variation at a gene locus that can exert significant effects in murine models of human substance abuse vulnerability and dopaminergic neurodegeneration.
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Affiliation(s)
- D M Donovan
- Molecular Neurobiology, Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 20857, USA.
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48
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Romero DV, Partilla JS, Zheng QX, Heyliger SO, Ni Q, Rice KC, Lai J, Rothman RB. Opioid peptide receptor studies. 12. Buprenorphine is a potent and selective mu/kappa antagonist in the [35S]-GTP-gamma-S functional binding assay. Synapse 1999; 34:83-94. [PMID: 10502307 DOI: 10.1002/(sici)1098-2396(199911)34:2<83::aid-syn1>3.0.co;2-s] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We utilized the [(35)S]-GTP-gamma-S functional binding assay to determine the selectivity of opioid receptor agonists in guinea pig caudate membranes. The study focused on two opioid agonists used for treating opioid-dependent patients: methadone and buprenorphine. Selective antagonists were used to generate agonist-selective conditions: TIPP + nor-BNI to measure mu receptors, CTAP + nor-BNI to measure gamma receptors and TIPP + CTAP to measure kappa receptors. The assay was first validated with opioid agonists of known subtype specificity (DAMGO for mu, SNC80 for delta, and U69, 593 for kappa receptors). Methadone-stimulated [(35)S]-GTP-gamma-S binding was mu-specific and less potent and efficacious than etorphine (K(d) = 1,537 nM vs. K(d) = 7.8 nM). Buprenorphine failed to stimulate [(35)S]-GTP-gamma-S binding but inhibited agonist-stimulated [(35)S]-GTP-gamma-S binding. The antagonist-K(i) values (nM) of buprenorphine at mu, delta, and kappa receptors were 0.088 nM, 1.15 nM, and 0.072 nM, respectively. The antagonist-K(i) values (nM) of naloxone at mu, delta, and kappa receptors were 1.39 nM, 25.0 nM, and 11.4 nM, respectively. Autoradiographic studies showed that buprenorphine failed to stimulate [(35)S]-GTP-gamma-S binding in caudate-level rat brain sections but blocked DAMGO-stimulated [(35)S]-GTP-gamma-S binding. In cells expressing the cloned rat mu receptor, buprenorphine was a partial agonist and potent mu antagonist. Administration of buprenorphine to rats produced a long-lasting (>24 h) decrease in mu and kappa2 receptor binding and attenuated mu-stimulated [(35)S]-GTP-gamma-S binding. Viewed collectively, these data indicate that, in this assay system, buprenorphine is a potent mu and gamma receptor antagonist. The clinical implications remain to be elucidated. Synapse 34:83-94, 1999. Published 1999 Wiley-Liss, Inc.
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Affiliation(s)
- D V Romero
- Clinical Psychopharmacology Section, DIR, NIDA, NIH, Baltimore, Maryland 21224, USA
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49
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Thomas JB, Herault XM, Rothman RB, Burgess JP, Mascarella SW, Xu H, Horel RB, Dersch CM, Carroll FI. (+/-)-4-[(N-allyl-cis-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide displays selective binding for the delta opioid receptor. Bioorg Med Chem Lett 1999; 9:3053-6. [PMID: 10571174 DOI: 10.1016/s0960-894x(99)00525-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Racemic 4-[(N-allyl-cis-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzam ide (3a) was synthesized and found to have good affinity and selectivity for the delta receptor. These compounds can be viewed as an analog of BW373U86 and SNC-80 where an internal piperazine nitrogen has been transposed with a benzylic carbon. Functionally, 3a behaves as an agonist at the delta receptor with no measurable stimulation of either the mu or kappa receptor subtypes and was found to be devoid of any measurable amount of antagonist activity for any opioid receptor. A comparison of 3a to SNC-80 and DPDPE in the [35S]GTPgammaS functional assay suggests that 3a may be more like the peptide DPDPE.
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Affiliation(s)
- J B Thomas
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, NC 27709, USA
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50
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Villemagne VL, Wong DF, Yokoi F, Stephane M, Rice KC, Matecka D, Clough DJ, Dannals RF, Rothman RB. GBR12909 attenuates amphetamine-induced striatal dopamine release as measured by [(11)C]raclopride continuous infusion PET scans. Synapse 1999; 33:268-73. [PMID: 10421707 DOI: 10.1002/(sici)1098-2396(19990915)33:4<268::aid-syn3>3.0.co;2-w] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Major neurochemical effects of methamphetamine include release of dopamine (DA), serotonin (5-HT), and norepinephrine (NE) via a carrier-mediated exchange mechanism. Preclinical research supports the hypothesis that elevations of mesolimbic DA mediate the addictive and reinforcing effects of methamphetamine and amphetamine. This hypothesis has not been adequately tested in humans. Previous in vivo rodent microdialysis demonstrated that the high affinity DA uptake inhibitor, GBR12909, attenuates cocaine- and amphetamine-induced increases in mesolimbic DA. The present study determined the ability of GBR12909 to attenuate amphetamine-induced increases in striatal DA as measured by [(11)C]raclopride continuous infusion positron emission tomography (PET) scans in two Papio anubis baboons. [(11)C]Raclopride was given in a continuous infusion paradigm resulting in a flat volume of distribution vs. time for up to 45 min postinjection. At that time, a 1.5 mg/kg amphetamine i.v. bolus was administered which caused a significant (30.3%) reduction in the volume of distribution (V(3)"). The percent reduction in the volume of distribution and, hence, a measure of the intrasynaptic DA release ranged between 22-41%. GBR12909 (1 mg/kg, slow i.v. infusion) was administered 90 min before the administration of the radiotracer. The comparison of the volume of distribution before and after administration of GBR12909 showed that GBR12909 inhibited amphetamine-induced DA release by 74%. These experiments suggest that GBR12909 is an important prototypical medication to test the hypothesis that stimulant-induced euphoria is mediated by DA and, if the DA hypothesis is correct, a potential treatment agent for cocaine and methamphetamine abuse. Furthermore, this quantitative approach demonstrates a way of testing various treatment medications, including other forms of GBR12909 such as a decanoate derivative.
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Affiliation(s)
- V L Villemagne
- Departments of Radiology and Environmental Health Sciences, Divisions of Nuclear Medicine and Radiation Health Sciences, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287-0807, USA
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