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Kuhar MJ, Jaworski JN, Hubert GW, Philpot KB, Dominguez G. Cocaine- and amphetamine-regulated transcript peptides play a role in drug abuse and are potential therapeutic targets. AAPS JOURNAL 2005; 7:E259-65. [PMID: 16146347 PMCID: PMC2751515 DOI: 10.1208/aapsj070125] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) peptides (55 to 102 and 62 to 102) are neurotransmitters with important roles in a number of physiologic processes. They have a role in drug abuse by virtue of the fact that they are modulators of mesolimbic function. Key findings supporting a role in drug abuse are as follows. First, high densities of CART-containing nerve terminals are localized in mesolimbic areas. Second, CART 55 to 102 blunts some of the behavioral effects of cocaine and dopamine (DA). This functional antagonism suggests that CART peptides be considered as targets for medications development. Third, CREB in the nucleus accumbens has been shown to have an opposing effect on cocaine self-administration. CREB may activate CART expression in that region, and, if so, CART may mediate at least some of the effects of CREB. Fourth, in addition to the effects of CART on DA, DA can influence CART in the accumbens. Thus a complex interacting circuitry likely exists. Fifth, in humans, CART is altered in the ventral tegmental area of cocaine overdose victims, and a mutation in the CART gene associates with alcoholism. Overall, it is clear that there are functional interactions among CART, DA, and cocaine and that plausible cellular mechanisms exist to explain some of these actions. Future studies will clarify and extend these findings.
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Herzig V, Capuani EMI, Kovar KA, Schmidt WJ. Effects of MPEP on expression of food-, MDMA- or amphetamine-conditioned place preference in rats. Addict Biol 2005; 10:243-9. [PMID: 16109585 DOI: 10.1080/13556210500223272] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Recent studies have revealed the effectiveness of 2-methyl-6-(phenylethynyl)pyridine (MPEP), a highly selective antagonist of metabotropic glutamate receptors subtype 5 (mGluR5), in conditioned drug reward. In a previous study we showed that MPEP blocks expression of context-conditioned morphine- but not cocaine reward in the rat. The present study now examines the effectiveness of MPEP in the expression of context-conditioned food, MDMA ('ecstasy') or amphetamine reward. Therefore, three groups of rats were conditioned either to food, MDMA or amphetamine in the conditioned place preference (CPP) paradigm. After conditioning, CPP expression and locomotion were determined simultaneously in the presence and absence of the respective reward (i.e. food or drug), or after application of 50 mg/kg MPEP (the dose that was most effective in reducing morphine CPP expression in our previous study). As a result, MPEP reduced locomotion in all groups. Furthermore, only expression of amphetamine CPP was inhibited by MPEP, while expression of food and MDMA CPP was not affected, suggesting that the MPEP-induced inhibition of amphetamine CPP expression was not causally linked to the reduction of locomotion. Overall, we conclude that MPEP reduces expression of context-conditioned amphetamine but not MDMA or food reward.
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Green-Sadan T, Kuttner Y, Lublin-Tennenbaum T, Kinor N, Boguslavsky Y, Margel S, Yadid G. Glial cell line-derived neurotrophic factor-conjugated nanoparticles suppress acquisition of cocaine self-administration in rats. Exp Neurol 2005; 194:97-105. [PMID: 15899247 DOI: 10.1016/j.expneurol.2005.01.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2004] [Revised: 01/19/2005] [Accepted: 01/26/2005] [Indexed: 10/25/2022]
Abstract
The neurotrophic factor glial cell line-derived neurotrophic factor (GDNF) may have therapeutic potential for preventing and treating cocaine addiction. Previously, we found that transplantation of a GDNF-expressing astrocyte cell line into the striatum and nucleus accumbens attenuates cocaine-seeking behavior in Sprague-Dawley rats. However, as a potential treatment for humans, cell transplantation presents several technical and ethical complications. Nanoparticulate systems are a safe and effective method for introducing exogenous compounds into the brain. Therefore, we examined the effect of GDNF-conjugated nanoparticles microinjected into the striatum and nucleus accumbens on cocaine self-administration in rats. GDNF-conjugated nanoparticles blocked the acquisition of cocaine self-administration compared to control treatments. Furthermore, a cocaine dose response demonstrated that decreased lever response in rats that received GDNF-conjugated nanoparticles persisted after substitution with different cocaine doses. This effect is not due to a non-specific disruption of locomotor or operant behavior, as seen following a water operant task. The current study is one of the first demonstrations that drug-conjugated nanoparticles may be effective in treating brain disorders. These findings suggest that GDNF-conjugated nanoparticles may serve as a novel potential treatment for drug addiction.
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GILBERT JEREMYG, NEWMAN AMYHAUCK, GARDNER ELIOTL, ASHBY CHARLESR, HEIDBREDER CHRISTIANA, PAK ARLENEC, PENG XIAOQING, XI ZHENGXIONG. Acute administration of SB-277011A, NGB 2904, or BP 897 inhibits cocaine cue-induced reinstatement of drug-seeking behavior in rats: role of dopamine D3 receptors. Synapse 2005; 57:17-28. [PMID: 15858839 PMCID: PMC3726034 DOI: 10.1002/syn.20152] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Recent studies have shown that the novel dopamine (DA) D3 receptor antagonists SB-277011A and NGB 2904 inhibit cocaine- and/or stress-induced reinstatement of drug-seeking behavior. The present study sought to determine if SB-277011A, NGB 2904, or BP-897 (a mixed D3 agonist/antagonist) similarly inhibit cocaine-associated cue-induced reinstatement of drug-seeking behavior. Long-Evans rats were allowed to self-administer cocaine. Each cocaine infusion was paired with discrete conditioned cue-light and tone. Subsequently, drug-seeking (i.e., lever-pressing) behavior was extinguished in the absence of cocaine and cocaine-associated cues. Rats were then tested for cue-induced reinstatement of drug-seeking. We found that cocaine-associated cues evoked robust reinstatement of lever-pressing. Acute intraperitoneal (i.p.) administration of SB-277011A (6, 12, or 24 mg/kg) produced a dose-dependent inhibition of cue-induced reinstatement of drug-seeking behavior by 35, 65, and 85%, respectively, compared to vehicle-treated animals. Acute i.p. administration of NGB 2904 (0.1, 1.0, or 5.0 mg/kg) produced a 45, 30, and 70% inhibition of cue-induced reinstatement, respectively, compared to vehicle-treated animals. Acute i.p. administration of either 0.1 or 1 mg/kg of BP 897 did not produce a significant effect on cue-induced reinstatement, whereas a dose of 3 mg/kg produced a 70% inhibition of cue-induced reinstatement. These findings, combined with previous data, suggest that DA D3 receptor antagonism may underlie the inhibitory effects of SB-277011A and NGB 2904 on cocaine cue-induced reinstatement, while the effects of BP 897 may involve D3 and non-D3 receptor mechanisms.
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Dar DE, Thiruvazhi M, Abraham P, Kitayama S, Kopajtic TA, Gamliel A, Slusher BS, Carroll FI, Uhl GR. Structure-activity relationship of trihexyphenidyl analogs with respect to the dopamine transporter in the on going search for a cocaine inhibitor. Eur J Med Chem 2005; 40:1013-21. [PMID: 16009468 DOI: 10.1016/j.ejmech.2005.04.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Revised: 04/16/2005] [Accepted: 04/18/2005] [Indexed: 12/18/2022]
Abstract
A series of trihexyphenidyl (THP) analogs were used to search for a derivative that could serve as a cocaine inhibitor. A compound that blocks binding of the cocaine analog carboxyfluorotropane (CFT), allows dopamine uptake and exhibits low side effects could serve as a good candidate for that purpose. All analogs were tested for the extent to which they inhibit CFT binding, dopamine uptake and n-methyl scopolamine (NMS) binding. Several structure-function relationships emerged. Methylation/halogenation of THP's benzene ring enhanced the compound's ability to block CFT binding in comparison to its ability to block dopamine uptake (5a-e). Replacement of the cyclohexyl ring with a benzene ring tended to create compounds that had lower affinities to the dopamine transporter (7b compared to THP, 7d compared to 5h, 7c compared to 8c) and modification of THP's piperidine ring tended to enhance affinity to the dopamine transporter (5f-h, 8a, 8c). One analog (5f) that showed little muscarinic activity indicating that it would probably have few side effects was investigated for its effects as an in vivo cocaine inhibitor. However, it showed few antagonistic effects in vivo. Nevertheless, this work greatly elucidates the structure-function relationships required for potential cocaine inhibitors and so lays out promising directions for future research.
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Zhang XY, Kosten TA. Prazosin, an alpha-1 adrenergic antagonist, reduces cocaine-induced reinstatement of drug-seeking. Biol Psychiatry 2005; 57:1202-4. [PMID: 15866561 DOI: 10.1016/j.biopsych.2005.02.003] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 11/30/2004] [Accepted: 02/03/2005] [Indexed: 11/23/2022]
Abstract
BACKGROUND Norepinephrine is implicated in cocaine's behavioral effects. In this study, we tested the effect of prazosin, an alpha1-adrenergic receptor antagonist, on cocaine-induced reinstatement of drug-seeking behavior. METHODS Rats were trained to self-administer cocaine intravenously under a fixed-ratio 3 schedule of reinforcement. After behavior was established, cocaine was replaced with saline and behavior extinguished. The ability of cocaine (0, 5-20 mg/kg) alone or combined with prazosin (.3 mg/kg) to reinstate lever press responding was tested. The effects of prazosin on lever press responding for food was examined in another set of rats. RESULTS Cocaine induced a dose-dependent reinstatement of drug-seeking behavior that was significantly attenuated by prazosin. This dose of prazosin did not alter lever press response rates for food. CONCLUSIONS The attenuation in drug-induced reinstatement is likely not due to prazosin-induced suppression of activity. These results suggest alpha1-adrenergic mechanisms contribute to reinstatement in rats and perhaps, to relapse in addicts.
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Winhusen T, Somoza E, Harrer JM, Moore E, Ussery T, Kropp F, Singal B, Elkashef A, Mojsiak J. Metyrapone and cocaine: A double-blind, placebo-controlled drug interaction study. Pharmacol Biochem Behav 2005; 80:631-8. [PMID: 15820533 DOI: 10.1016/j.pbb.2005.01.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 09/24/2004] [Accepted: 01/31/2005] [Indexed: 11/15/2022]
Abstract
Pre-clinical research suggests that suppression of adrenocorticosteroid synthesis might decrease susceptibility to stress-induced relapse. Metyrapone effectively suppresses cortisol synthesis and thus might have promise as a cocaine dependence treatment. The present inpatient study evaluated the interaction of metyrapone and cocaine to assess the safety of conducting an outpatient trial. Twelve nontreatment-seeking cocaine-dependent individuals completed this double-blind, placebo-controlled, crossover study with two factors: medication (750 mg of metyrapone vs. placebo) and infusion (40 mg of cocaine vs. saline). Safety measures included vital signs, adverse events, and electrocardiogram. Efficacy measures included visual analog scale (VAS) ratings of craving and drug effect. Neuroendocrine measures included cortisol and ACTH. As predicted, metyrapone was well tolerated and did not exacerbate cocaine's physiological effects. Also as predicted, metyrapone did not significantly alter cocaine's subjective effects. The results of the present study suggest that metyrapone at the dose studied can likely be used safely in an outpatient study with active cocaine users.
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Bailey DN, Briggs JR. The effect of lovastatin and thioridazine on the degradation of cocaine in human serum in vitro. Ther Drug Monit 2005; 27:168-70. [PMID: 15795647 DOI: 10.1097/01.ftd.0000151187.68593.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effect of lovastatin and thioridazine on the degradation of cocaine in human serum was studied by incubating therapeutic and toxic concentrations of either drug with cocaine in human serum at 37 degrees C. Without these other drugs, cocaine concentrations decreased by an average of 88% in 120 minutes. Lovastatin at all concentrations studied showed a negligible effect on the degradation of cocaine in human serum and did not alter the pseudocholinesterase activity of the serum. In contrast, in the presence of a therapeutic concentration of thioridazine, cocaine concentrations decreased by only 71% during this period of time, and, with a toxic concentration of thioridazine, cocaine concentrations decreased by only 55%. Thioridazine suppressed the pseudocholinesterase activity of human serum by up to 19% during the 120-minute incubation period, and this effect was more pronounced at higher thioridazine concentrations. These findings suggest that thioridazine may prolong the serum half-life of cocaine by inhibiting the pseudocholinesterase-mediated catabolism of cocaine to ecgonine methyl ester. This may be important in cocaine users who are treated with phenothiazines and other structurally similar drugs. They also may be of interest in cocaine-abusing patients who are treated with phenothiazines for schizophrenic disorders.
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Lodge DJ, Grace AA. Acute and Chronic Corticotropin-Releasing Factor 1 Receptor Blockade Inhibits Cocaine-Induced Dopamine Release: Correlation with Dopamine Neuron Activity. J Pharmacol Exp Ther 2005; 314:201-6. [PMID: 15784652 DOI: 10.1124/jpet.105.084913] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Corticotropin-releasing factor (CRF) is a neuropeptide associated with the integration of the physiological and behavioral responses to stress. Recently, CRF1 receptor antagonists have been shown to decrease cocaine self-administration and inhibit stress-induced reinstatement of cocaine-seeking behavior. The exact mechanisms underlying this effect are not clear. Based on the large amount of literature demonstrating an association between dopaminergic neurotransmission and reward-related behavior, the aim of the present study was to examine the effects of acute versus chronic CRF1 receptor blockade on mesencephalic dopamine (DA) neuron activity (determined by in vivo extracellular recordings) and extracellular DA levels in the nucleus accumbens (Acb) (using in vivo microdialysis). In addition, the effect of CRF1 receptor antagonism on cocaine-induced DA overflow in the Acb was examined and correlated with DA neuron activity in the ventral tegmental area (VTA). Acute (but not chronic) CRF1 receptor blockade by CRA-0450 [1-[8-(2,4-dichlorophenyl)-2-methylquinolin-4-yl]-1,2,3,6-tetrahydropyridine-4-carboxamide benzenesulfonate] was found to significantly increase DA neuron population activity without affecting burst firing, average firing rate, or Acb DA levels. In addition, both acute and chronic CRF1 receptor antagonism significantly reduced cocaine-stimulated DA overflow in the Acb, and this reduction was correlated with an attenuated cocaine-induced inhibition of DA population activity. Taken as a whole, these data demonstrate that, although DA neuron population activity exhibits tolerance to chronic CRF1 receptor antagonism (by CRA-0450), tolerance does not develop to the selective inhibition of cocaine-induced DA release (in the Acb) and, as such, may be beneficial in the treatment of cocaine addiction.
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Takahashi S, Ohshima T, Cho A, Sreenath T, Iadarola MJ, Pant HC, Kim Y, Nairn AC, Brady RO, Greengard P, Kulkarni AB. Increased activity of cyclin-dependent kinase 5 leads to attenuation of cocaine-mediated dopamine signaling. Proc Natl Acad Sci U S A 2005; 102:1737-42. [PMID: 15665076 PMCID: PMC547862 DOI: 10.1073/pnas.0409456102] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cocaine, a drug of abuse, increases synaptic dopamine levels in the striatum by blocking dopamine reuptake at axon terminals. Cyclin-dependent kinase 5 (Cdk5) and its activator p35, proteins involved in phosphorylation of substrates in postmitotic neurons, have been found to be up-regulated after chronic exposure to cocaine. To further examine the effects of Cdk5 and p35 induction on striatal dopamine signaling, we generated two independent transgenic mouse lines in which Cdk5 or p35 was overexpressed specifically in neurons. We report here that increased Cdk5 activity, as a result of p35 but not of Cdk5 overexpression, leads to attenuation of cocaine-mediated dopamine signaling. Increased Cdk5-mediated phosphorylation of dopamine and cAMP-regulated phosphoprotein, molecular mass 32 kDa (DARPP-32) at Thr-75, was accompanied by decreased phosphorylation of DARPP-32 at Thr-34. Increased Cdk5-mediated phosphorylation of extracellular signal-regulated kinase kinase 1 at Thr-286 was accompanied by decreased activation of extracellular signal-regulated kinase 1/2. These effects contributed to attenuation of cocaine-induced phosphorylation of cAMP response element-binding protein as well as a lesser induction of c-fos in the striatum. These results support the idea that Cdk5 activity is involved in altered gene expression after chronic exposure to cocaine and hence impacts the long-lasting changes in neuronal function underlying cocaine addiction.
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Herzig V, Schmidt WJ. Effects of MPEP on locomotion, sensitization and conditioned reward induced by cocaine or morphine. Neuropharmacology 2005; 47:973-84. [PMID: 15555632 DOI: 10.1016/j.neuropharm.2004.07.037] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 07/02/2004] [Accepted: 07/28/2004] [Indexed: 01/27/2023]
Abstract
Exposure to environmental cues is considered a major cause of relapse in detoxified addicts. Recent findings showed an involvement of glutamate in cue-induced relapse and suggest that subtype 5 of metabotropic glutamate receptors (mGluR5) is involved in conditioned drug-reward. The present study applied the conditioned place preference (CPP) paradigm to examine the involvement of mGluR5 in cocaine- and morphine-induced behaviours. Results of previous mice-studies were extended into rats by using the selective mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP). As a result, the evaluated behavioural parameters were dose-relatedly affected by MPEP. Low-dosed MPEP (10 mg/kg, i.p.) did not affect spontaneous locomotion, reduced cocaine-induced hyperlocomotion and produced sensitized locomotion, while showing no effect on sensitized locomotion induced by repeated cocaine or morphine. Low-dosed MPEP did not genuinely block development of cocaine- and morphine-CPP, but rendered CPP expression state-dependent. The medium MPEP-dose (30 mg/kg) was most effective in reducing spontaneous locomotion. The high MPEP-dose (50 mg/kg) was most effective in reducing both body-weight and morphine-CPP expression. Cocaine-CPP expression was not affected by any MPEP-dose. In conclusion, mGluR5 are involved in modulation of spontaneous and cocaine-induced locomotion, in state-dependent learning and in expression of morphine-CPP. Thus, MPEP may be beneficial for relapse prevention in morphine-addicts.
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Andersen ML, Tufik S. Inhibitory effect of GABAergic drugs in cocaine-induced genital reflexes in paradoxical sleep-deprived male rats. Pharmacol Biochem Behav 2005; 78:301-7. [PMID: 15219771 DOI: 10.1016/j.pbb.2004.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Revised: 03/26/2004] [Accepted: 04/05/2004] [Indexed: 11/25/2022]
Abstract
The aim of this study was to seek whether GABAergic drugs were involved in the action of cocaine on spontaneous genital reflexes (penile erection-PE, and ejaculation-EJ) of paradoxical sleep-deprived (PSD) male rats. After a 4-day period of PSD, each group was administered with GABAergic drugs 1 h prior to cocaine and placed in observation cages. The administration of gamma-aminobutyric acid (GABA)-A agonist (muscimol, 2 and 3 mg/kg sc) reduced the number of animals displaying PE, whereas all doses tested of muscimol and bicuculline significantly reduced the frequency of PE. Pretreatment with the lower doses of GABA-B antagonist, phaclofen (1 and 2 mg/kg sc), also significantly reduced the percentage of rats showing PE; however, after the higher dose injection, the proportion of animals with PE was similar to those seen after vehicle pretreatment. Both GABA-B agonist and antagonist significantly reduced the PE frequency for all doses used compared with the vehicle group. There were no significant differences between control and GABA-A drugs in EJ behavior, whereas phaclofen 2 mg/kg pretreatment increased the ejaculatory latency. These data show that GABAergic compounds inhibited PE in male PSD rats suggesting that this inhibition points to a differential role of GABA receptor subtypes.
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Bari AA, Pierce RC. D1-like and D2 dopamine receptor antagonists administered into the shell subregion of the rat nucleus accumbens decrease cocaine, but not food, reinforcement. Neuroscience 2005; 135:959-68. [PMID: 16111825 DOI: 10.1016/j.neuroscience.2005.06.048] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 04/26/2005] [Accepted: 06/17/2005] [Indexed: 11/27/2022]
Abstract
Cocaine self-administration experiments were designed to assess the respective roles of D1-like and D2-like dopamine receptors in the ventral forebrain in cocaine reinforcement. D1-like or D2-like dopamine receptor antagonists were microinjected into the nucleus accumbens core, nucleus accumbens shell, neostriatum or lateral septum prior to sessions in which cocaine was self-administered under a progressive ratio schedule by rats. The results indicated that administration of a D1/5 (SCH-23390) or a D2/D3/D4 (eticlopride), but not a D3 (U99194A) or D4 (L-750,667), dopamine receptor antagonist into the core and shell of the nucleus accumbens decreased the reinforcing efficacy of cocaine. However, in control experiments intra-accumbal core administration of SCH-23390 or eticlopride decreased food self-administration, whereas administration of these drugs into the accumbens shell had no effect on food reinforcement. Neither SCH-23390 nor eticlopride influenced cocaine reinforcement when administered into the neostriatum or lateral septum. Collectively, these results indicate that D1-like and D2 dopamine receptors in the nucleus accumbens shell selectively modulate the reinforcing efficacy of cocaine, whereas D1-like and D2 dopamine receptors in the accumbens core have a more general influence on reinforced behaviors.
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Jouvert P, Revel MO, Lazaris A, Aunis D, Langley K, Zwiller J. Activation of the cGMP pathway in dopaminergic structures reduces cocaine-induced EGR-1 expression and locomotor activity. J Neurosci 2004; 24:10716-25. [PMID: 15564589 PMCID: PMC6730124 DOI: 10.1523/jneurosci.1398-04.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Revised: 10/13/2004] [Accepted: 10/13/2004] [Indexed: 11/21/2022] Open
Abstract
Nitric oxide (NO) and the C-type natriuretic peptide (CNP) exert their action on brain via the cGMP signaling pathway. NO, by activating soluble guanylyl cyclase, and CNP, by stimulating membrane-bound guanylyl cyclase, cause intracellular increases of cGMP, activating cGMP-dependent protein kinases (PKGs). We show here that injection of CNP into the rat ventral tegmental area strongly reduced cocaine-induced egr-1 expression in the nucleus accumbens in a dose-dependent manner. The effect of CNP was reversed by the previous injection of a selective PKG inhibitor, KT5823. Activation of PKG by 8-bromo-cGMP reduced, like CNP, cocaine-induced gene transcription in dopaminergic structures. To confirm the involvement of PKG, this was overexpressed in either the mesencephalon or the caudate-putamen. Using the polyethyleneimine delivery system, an active protein was expressed by injecting a plasmid vector containing the human PKG-Ialpha cDNA. PKG was overexpressed in dopaminergic and GABAergic neurons when the plasmid was injected in the ventral tegmental area, whereas overexpression was observed in medium spiny GABAergic neurons and in both cholinergic and GABAergic interneurons when the PKG vector was injected into the caudate-putamen. Activation of the overexpressed PKG reduced cocaine-induced egr-1 expression in dopaminergic structures and affected behavior (i.e., locomotor activity). These effects were again reversed by previous injection of the selective PKG inhibitor. The current data suggest that NO and the neuropeptide CNP are potential regulators of cocaine-related effects on behavior.
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Meunier J, Maurice T. Beneficial effects of the sigma1 receptor agonists igmesine and dehydroepiandrosterone against learning impairments in rats prenatally exposed to cocaine. Neurotoxicol Teratol 2004; 26:783-97. [PMID: 15451042 DOI: 10.1016/j.ntt.2004.07.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Revised: 07/07/2004] [Accepted: 07/07/2004] [Indexed: 10/26/2022]
Abstract
In utero cocaine (IUC) exposure results in offspring rats in complex neurochemical and behavioral alterations, particularly affecting learning and memory processes. We examined here the impact of IUC exposure on memory functions in male and female offspring rats and report that selective sigma(1) (sigma(1)) receptor agonists are effective in reversing the deficits. Dams received a daily cocaine, 20 mg/kg ip, injection between gestational days E17 to E20. Learning was examined in offspring between day P30 and P41 using delayed alternation in the T-maze, water-maze learning and passive avoidance. Both male and female rats prenatally exposed to cocaine showed delayed alternation deficits and impairments of acquisition of a fixed platform position in the water maze, as shown by higher acquisition latencies and diminutions of time spent in the training quadrant during the probe test. The acquisition of a daily changing platform position also demonstrated impaired working memory. Finally, passive avoidance deficits were observed. Pretreatment with the synthetic sigma(1) agonist igmesine (0.1-1 mg/kg ip) or the neuroactive steroid dehydroepiandrosterone (DHEA 10-40 mg/kg ip) reversed the prenatal cocaine-induced learning deficits in offspring rats for each test. The sigma(1) antagonist BD1063 (1 mg/kg ip) failed to affect performances alone but blocked the igmesine and DHEA effects, confirming the involvement of the sigma(1) receptor. IUC exposure thus results in marked memory deficits, affecting spatial and nonspatial short- and long-term memories in juvenile male and female offspring rats. The activation of the sigma(1) neuromodulatory receptor allows a complete behavioral recovery of the memory functions in prenatally cocaine-exposed rats.
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Kreuter JD, Mattson BJ, Wang B, You ZB, Hope BT. Cocaine-induced Fos expression in rat striatum is blocked by chloral hydrate or urethane. Neuroscience 2004; 127:233-42. [PMID: 15219685 DOI: 10.1016/j.neuroscience.2004.04.047] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Revised: 04/20/2004] [Accepted: 04/27/2004] [Indexed: 11/18/2022]
Abstract
Anesthetics used in electrophysiological studies alter the effects of cocaine and amphetamine on neural activity in the striatum. However, the mechanism underlying this alteration has not been established. In the present study, we examined the effects of anesthetics on cocaine-induced neural activity in the striatum. We first assayed the ability of 20 mg/kg cocaine to induce Fos expression in the striatum following pretreatment with 400 mg/kg chloral hydrate or 1.3 g/kg urethane, two of the most commonly used anesthetics for in vivo electrophysiology. Chloral hydrate blocked, while urethane strongly attenuated cocaine-induced Fos expression without affecting basal levels of expression. We then examined dopaminergic and glutamatergic mechanisms for anesthetic effects on cocaine-induced Fos expression. Chloral hydrate and urethane did not attenuate basal or cocaine-induced increases of dopamine levels as assessed by microdialysis in dorsal striatum. In contrast, chloral hydrate attenuated glutamatergic neurotransmission as assessed by microdialysis in the presence of the glutamate transport blocker L-trans-pyrrolidone-2,4-dicarboxylic acid. Chloral hydrate attenuated basal levels of glutamate by 70%, while cocaine had no effect on glutamate levels. Since glutamate levels were tetrodotoxin-sensitive, the majority of glutamate measured in our assay was by synaptic release. To assess a causal role for a reduction of glutamatergic neurotransmission in anesthetic effects on cocaine-induced Fos expression, we injected the glutamate receptor agonists AMPA and NMDA into the dorsal striatum of chloral hydrate-anesthetized rats. The glutamate receptor agonists partially reinstated cocaine-induced Fos expression in anesthetized rats. We conclude anesthetics attenuate cocaine-induced neuronal activity by reducing glutamatergic neurotransmission.
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Shin EJ, Oh KW, Kim KW, Kwon YS, Jhoo JH, Jhoo WK, Cha JY, Lim YK, Kim IS, Kim HC. Attenuation of cocaine-induced conditioned place preference by Polygala tenuifolia root extract. Life Sci 2004; 75:2751-64. [PMID: 15464827 DOI: 10.1016/j.lfs.2004.04.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2004] [Accepted: 04/15/2004] [Indexed: 11/21/2022]
Abstract
A recent investigation indicated that Polygala tenuifolia Willdenow extract (PTE) possesses a potential antipsychotic effect. In this study, we examined the effects of PTE on the cocaine-induced changes in locomotor activity, conditioned place preference (CPP), fos-related antigen-immunoreactivity (FRA-IR), and activator protein (AP)-1 DNA binding activity. Cocaine-induced behavioral effects (hyperlocomotion and CPP) occurred in parallel with increases in FRA-IR and AP-1 DNA binding activity in the nucleus accumbens. These responses induced by cocaine were consistently attenuated by concurrent treatment with PTE (25 mg or 50 mg/kg/day, i.p. x 7). The adenosine A2A receptor antagonist, 1,3,7-trimethyl-8-(3-chlorostyrl)xanthine (0.5 or 1.0 mg/kg, i.p.), reversed the PTE-mediated pharmacological action in a dose related manner; neither the adenosine A(1) receptor antagonist, 8-cyclopentyl-1,3-dimethylxanthine (0.5 or 1.0 mg/kg, i.p.) nor the A2B receptor antagonist, alloxazine (1.5 or 3.0 mg/kg, i.p.) significantly affected this pharmacological action. Our results suggest that PTE prevents cocaine-induced behavioral effects, at least in part, via the activation of the adenosine A2A receptor.
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Chen Y, Banerjee A, Hess GP. Mechanism-based discovery of small molecules that prevent noncompetitive inhibition by cocaine and MK-801 mediated by two different sites on the nicotinic acetylcholine receptor. Biochemistry 2004; 43:10149-56. [PMID: 15287742 DOI: 10.1021/bi049590u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nicotinic acetylcholine receptor (nAChR) belongs to a group of five structurally related membrane proteins that play a major role in the communication between approximately 10(12) cells of the mammalian nervous system. The receptor is inhibited by both abused drugs and therapeutic agents. During the past two decades, many attempts have been made to find compounds that prevent cocaine inhibition of this protein. The use of newly developed transient kinetic techniques in investigations of the inhibition of the receptor by cocaine and MK-801 led to an inhibition mechanism not previously proposed. It was observed that the receptor contains two inhibitory sites: one that equilibrates with the tested noncompetitive inhibitors within approximately 50 ms, and a second site that equilibrates with inhibitors within approximately 1 s. The mechanism of inhibition of the rapidly equilibrating inhibitory site has been investigated, and based on that mechanism, the first evidence that small organic molecules exist that prevent inhibition of the rapidly equilibrating inhibitory site was obtained. These compounds did not prevent the inhibition due to the slowly equilibrating inhibitory site. Here, we present the first evidence that a compound (3-acetoxy ecgonine methyl ester) exists that prevents inhibition of the slowly equilibrating inhibitory site and that the mechanism of inhibition of this site differs from that of the rapidly equilibrating site. BC3H1 cells containing a fetal mouse muscle-type nAChR were used, and the receptor was activated by carbamoylcholine. The resulting whole-cell current due to the nondesensitized nAChR was determined. Because the nAChR desensitizes rapidly, the measurements required the use of a transient kinetic technique with a time resolution of 10 ms; the cell-flow technique was used. Inhibitors and compounds that alleviate inhibition were tested by determining their effects on the whole-cell current due to activation of the nAChR by carbamoylcholine.
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Carey RJ, DePalma G, Damianopoulos E, Hopkins A, Shanahan A, Müller CP, Huston JP. Dopaminergic and serotonergic autoreceptor stimulation effects are equivalent and additive in the suppression of spontaneous and cocaine induced locomotor activity. Brain Res 2004; 1019:134-43. [PMID: 15306247 DOI: 10.1016/j.brainres.2004.05.091] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2004] [Indexed: 10/26/2022]
Abstract
We used the D(2) receptor agonist, apomorphine (APO) and the 5-HT(1A) receptor agonist, 8-OHDPAT (8OH) in a low dose range to stimulate autoreceptors and in this way assess the separate and combined effects of reduced DA and 5-HT activity upon spontaneous and cocaine induced locomotor behavior. Two separate experiments were conducted. In the first experiment, separate groups of rats (N=10) were tested with either saline, 8OH, APO or 8OH plus APO (0.01, 0.025, 0.05 mg/kg). At 0.05 mg/kg, 8OH and APO induced similar dose related decreases (up to approximately 50%) in locomotor activity. The combined 8OH plus APO treatment induced dose-related decreases in locomotion (approximately 90%). At the 0.05 mg/kg dose level, the drug treatments given separately blocked cocaine induced increases in activity and the 8OH and APO inhibitory effects were again additive. In the second experiment, separate groups (N=10) received saline, 0.05 mg/kg APO, 0.05 mg/kg 8OH or 0.05 mg/kg APO plus 0.05 mg/kg 8OH. As in the first experiment, the 8OH and APO given separately reduced locomotor activity by approximately 50% and when given together, locomotor activity was virtually eliminated (reduced 80-90%). When the combined APO/8OH group also received the 5-HT(1A) antagonist, WAY 100635 (0.05 mg/kg), the effect on activity was equivalent to 0.05 mg/kg APO alone. Ex vivo neurochemical measurement of dopamine (DA) and serotonin (5-HT) metabolism confirmed that the APO decreased DA turnover, 8OH decreased 5-HT turnover and the combined treatment reduced both the DA and 5-HT turnover. Thus, for both spontaneous and cocaine induced locomotor behavior, the low dose 8OH and APO treatments suppressed locomotor activity and these effects were additive. These findings indicate that DA and 5-HT systems contribute separately to motoric activation. These results suggest that it is important to consider both DA and 5-HT contributions to disorders of motoric impoverishment such as Parkinson's disease as well as to hyperkinetic states such as those induced by stimulant drugs.
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Collins ED, Vosburg SK, Hart CL, Haney M, Foltin RW. Amantadine does not modulate reinforcing, subjective, or cardiovascular effects of cocaine in humans. Pharmacol Biochem Behav 2004; 76:401-7. [PMID: 14643838 DOI: 10.1016/j.pbb.2003.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Data from several clinical studies have suggested that amantadine, which has dopaminergic agonist and glutamatergic antagonist effects, may be useful for the treatment of cocaine dependence. The interaction between amantadine and smoked cocaine was examined in 10 cocaine smokers (7 men, 3 women), who participated in a 26-day inpatient study. Participants were maintained on amantadine (0 and 100 mg bid) for 5 days prior to laboratory testing, using a double-blind crossover design. Under each medication condition, participants smoked a sample dose of cocaine base (0, 12, 25, and 50 mg) once, and were subsequently given five choice opportunities, 14 min apart, to self-administer that dose of cocaine or receive a merchandise voucher ($5.00). Each cocaine dose was tested twice under each medication condition, and the order of medication condition and cocaine dose varied systematically. Cocaine produced stimulant-like reinforcing, subjective, and physiological effects. Amantadine maintenance did not modify the choice to self-administer smoked cocaine. These findings, taken together with the decidedly mixed literature, suggest that amantadine (100 mg bid) will not have a role in the treatment of cocaine dependence.
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Gasior M, Kaminski R, Witkin JM. Pharmacological modulation of GABA(B) receptors affects cocaine-induced seizures in mice. Psychopharmacology (Berl) 2004; 174:211-9. [PMID: 14985936 DOI: 10.1007/s00213-003-1743-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
RATIONALE Previous data have demonstrated that the convulsant effects of cocaine can be modulated by compounds that increase levels of endogenous gamma-aminobutyric acid (GABA) or that directly stimulate GABA(A) receptors. OBJECTIVES To determine whether the convulsant effects of cocaine can be modulated by ligands selective for GABA(B) receptors in mice. METHODS Effects of the GABA(B) receptor agonist ((+/-)-baclofen), antagonist (phaclofen), and their combination were tested against clonic seizures induced by cocaine (75 mg/kg). Enantiomers of baclofen were used to confirm stereospecificity of (+/-)-baclofen's effects. Pharmacological specificity of (+/-)-baclofen's effects was tested by comparison against seizures induced by GBR 12909 (monoamine transporter inhibitor), pentylenetetrazole (GABA(A) antagonist), N-methyl-D-aspartate (NMDA agonist), and aminophylline (A1/A2 adenosine antagonist). Additionally, effects of (+/-)-baclofen on kindled seizures induced by repeated administration of cocaine (60 mg/kg every 24 h for 6 days) were evaluated. The inverted screen test was used to assess behavioral side effects of baclofen. RESULTS (+/-)-Baclofen dose-dependently inhibited acute (ED50=4.1 mg/kg) and kindled (6.4 mg/kg) seizures induced by cocaine at doses somewhat lower than those producing behavioral side effects (11.5 mg/kg), and these effects were stereospecific. (+/-)-Baclofen suppressed seizures induced by GBR 12909 but not by pentylenetetrazole, NMDA, and aminophylline, suggesting selectivity of its anticonvulsant effects for monoamine-related mechanisms. Finally, phaclofen dose-dependently enhanced the convulsant effects of a threshold dose of cocaine (60 mg/kg). CONCLUSIONS Modulation of GABA(B) receptors can affect seizures induced by cocaine. This molecular mechanism may be involved in seizures induced by cocaine or, alternatively, may function as an independent inhibitory mechanism against seizures arising from blockade of monoamine uptake.
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Reeves R, Thiruchelvam M, Cory-Slechta DA. Expression of behavioral sensitization to the cocaine-like fungicide triadimefon is blocked by pretreatment with AMPA, NMDA and DA D1 receptor antagonists. Brain Res 2004; 1008:155-67. [PMID: 15145752 DOI: 10.1016/j.brainres.2004.01.079] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2004] [Indexed: 10/26/2022]
Abstract
Triadimefon (TDF) is a triazole fungicide that blocks the reuptake of dopamine (DA), much like cocaine. A recent study in our laboratory found that intermittent injections of TDF led to robust locomotor sensitization in response to challenge TDF after a 2-week withdrawal period. The current study sought to determine whether the expression of TDF behavioral sensitization could be prevented by the DA D1-like receptor antagonist SCH 23390 (SCH), the DA D2-like receptor antagonist remoxipride (Rem), the competitive NMDA antagonist CPP, or the AMPA antagonist NBQX. Adult male C57/BL6 mice were injected with vehicle or 75 mg/kg TDF twice a week for 7 weeks, with locomotor activity measured periodically across the 14 doses. After a 2-week withdrawal period, mice were pretreated with SCH (0.015 mg/kg), Rem (0.3 mg/kg), CPP (2.5 mg/kg) or NBQX (10.0 mg/kg) followed 30 min later by vehicle or 75 mg/kg TDF and tested for the expression of TDF sensitization. Intermittent administration of TDF led to the development and robust expression of behavioral sensitization in terms of vertical activity. Pretreatment with SCH, NBQX and CPP successfully blocked the expression of vertical sensitization to TDF, while Rem pretreatment did not. All four antagonists, however, attenuated the neurochemical changes normally associated with TDF sensitization as measured 8 h after the 2-week TDF challenge. This paper reveals that NMDA, AMPA and DA D1-like receptors are necessary for the behavioral expression of sensitization to the fungicide triadimefon.
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Matsumoto RR, Gilmore DL, Pouw B, Bowen WD, Williams W, Kausar A, Coop A. Novel analogs of the σ receptor ligand BD1008 attenuate cocaine-induced toxicity in mice. Eur J Pharmacol 2004; 492:21-6. [PMID: 15145701 DOI: 10.1016/j.ejphar.2004.03.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Accepted: 03/17/2004] [Indexed: 10/26/2022]
Abstract
Previous studies have shown that BD1008 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine) and related analogs attenuate the toxicity and stimulant effects of cocaine through antagonism of sigma receptors. In the present study, six analogs of BD1008 (UMB 98-103) were synthesized and evaluated in receptor binding and behavioral studies. Competition binding studies confirmed that all six compounds have high affinity for sigma1 receptors, moderate affinity for sigma2 receptors, and low to negligible affinity for monoamine transporters, opioid, N-methyl-D-aspartate, dopamine, and 5-HT receptors. In behavioral pharmacological studies, pretreatment of mice with UMB 100, UMB 101, or UMB 103 significantly attenuated cocaine-induced convulsions and lethality. Together with earlier studies, the data suggest that analogs of BD1008 are promising medication development leads for reducing the toxicity of cocaine.
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Grabowski J, Rhoades H, Stotts A, Cowan K, Kopecky C, Dougherty A, Moeller FG, Hassan S, Schmitz J. Agonist-like or antagonist-like treatment for cocaine dependence with methadone for heroin dependence: two double-blind randomized clinical trials. Neuropsychopharmacology 2004; 29:969-81. [PMID: 15039761 DOI: 10.1038/sj.npp.1300392] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Concurrent abuse of cocaine and heroin is a common problem. Methadone is effective for opioid dependence. The question arises as to whether combining agonist-like or antagonist-like medication for cocaine with methadone for opioid dependence might be efficacious. Two parallel studies were conducted. One examined sustained release d-amphetamine and the other risperidone for cocaine dependence, each in combination with methadone. In total, 240 subjects (120/study) were recruited, who were both cocaine and heroin dependent and not currently receiving medication. All provided consent. Both studies were carried out for 26 weeks, randomized, double-blind and placebo controlled. Study I compared sustained release d-amphetamine (escalating 15-30 or 30-60 mg) and placebo. Study II examined risperidone (2 or 4 mg) and placebo. All subjects underwent methadone induction and were stabilized at 1.1 mg/kg. Subjects attended clinic twice/week, provided urine samples, obtained medication take-home doses for intervening days, and completed self-report measures. Each had one behavioral therapy session/week. In Study I, reduction in cocaine use was significant for the 30/60 mg dose compared to the 15/30 mg and placebo. Opioid use was reduced in all groups with a trend toward greater reduction in the 30/60 mg d-amphetamine group. In Study II, methadone reduced illicit opioid use but cocaine use did not change in the risperidone or placebo groups. There were no adverse medication interactions in either study. The results provide support for the agonist-like (d-amphetamine) model in cocaine dependence treatment but not for antagonist-like (risperidone) treatment. They coincide with our previous reports of amphetamine or risperidone administered singly in cocaine-dependent individuals.
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Dohi T, Kitayama S, Morioka N, Kumagai K, Mitsuhata C, Morita K, Kozai K, Lin Z, Uhl GR. Regulation of dopamine and MPP+ transport by catecholamine transporters. NIHON SHINKEI SEISHIN YAKURIGAKU ZASSHI = JAPANESE JOURNAL OF PSYCHOPHARMACOLOGY 2004; 24:43-7. [PMID: 15164608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Following exocytotic release of the biogenic amine neurotransmitters, norepinephrine and dopamine, are removed from the synaptic cleft by the respective transporter, norepinephrine transporter (NET) and dopamine transporter (DAT) located on the plasma membrane. The catecholamine transporters are the molecular targets for psychoactive drugs as well as drugs of abuse such as cocaine and amphetamine and the Parkinsonism-inducing neurotoxin, MPP+. Nicotine regulates the transport of catecholamines and MPP+ and may exert self-medicating effects for depression, schizophrenia and attention deficit hyperactivity disorder, and neuroprotective effects against MPP+ through the regulation of the transporters. The availability of cDNAs of these transporters has permitted detailed pharmacological studies in heterologous expression systems for determining the mechanisms of action of nicotine on transporters. Moreover, functional analysis of the effect of single amino acid substitution suggests that specific residues in DAT molecules may play a significant role in interaction with MPP+ and cocaine, and thus would promise a development of novel drugs with diverse chemical structures.
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Abstract
We hypothesized that in humans, as in animals, isradipine, a dihydropyridine-class calcium channel antagonist, would antagonize cocaine's rewarding effects, based on preclinical evidence that isradipine inhibits cocaine-mediated increases in mesolimbic dopamine (DA), thereby reducing cocaine's abuse liability. Confirmation of our hypothesis would make isradipine a promising medication for treating cocaine dependence. Eighteen male and female volunteers (mean age, 32.6 years) who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for cocaine dependence participated in a double-blind, placebo-controlled, crossover study. Subjects received placebo or sustained-release (SR) low-dose or high-dose isradipine (15 or 30 mg), plus placebo or low-dose or high-dose cocaine HCl (0.325 or 0.650 mg/kg), for 9 treatment sessions separated by a 2-day interval. Standardized assessments of abuse liability, including a choice procedure to determine preference for cocaine with and without isradipine over monetary incentives, were conducted at scheduled intervals. Cocaine administration produced dose-related prototypic increases in stimulant-related effects, including euphoria, and drug preference over monetary incentives. Isradipine lacked any stimulant or abuse liability effects or the propensity to elicit craving, and it did not antagonize any of cocaine's stimulant-related effects associated with its abuse liability. In conclusion, SR isradipine (up to 30 mg) does not antagonize cocaine's rewarding effects in cocaine-dependent individuals. While higher isradipine doses may have been more effective at antagonizing cocaine reward, we could not test such doses due to the risk of serious adverse events. Also, isradipine-mediated inhibition of mesolimbic DA release may be an ineffective treatment of cocaine dependence.
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Prinssen EPM, Colpaert FC, Kleven MS, Koek W. Ability of dopamine antagonists to inhibit the locomotor effects of cocaine in sensitized and non-sensitized C57BL/6 mice depends on the challenge dose. Psychopharmacology (Berl) 2004; 172:409-14. [PMID: 14668976 DOI: 10.1007/s00213-003-1691-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2003] [Accepted: 10/23/2003] [Indexed: 10/26/2022]
Abstract
RATIONALE Studies in rats examining the ability of selective dopamine D(2) receptor class antagonists to attenuate the effects of a cocaine challenge have suggested that these agents are less potent in attenuating sensitized as opposed to non-sensitized locomotion. A potential issue with these studies is that the same challenge dose is used in sensitized and control conditions even though that dose may occupy different positions on the respective dose-response curves. OBJECTIVES To examine whether the ability of dopamine antagonists to attenuate cocaine-induced locomotion differs between sensitized and non-sensitized animals if they are challenged with the same dose of cocaine, and with the lowest dose to maximally increase locomotion, which is lower in sensitized than in non-sensitized animals. METHODS Mice were treated repeatedly with 20 mg/kg cocaine or saline (for 3 consecutive days) and then challenged (after an 11-day drug-free interval) with different challenge doses of cocaine after pretreatment with a dopamine antagonist or saline. RESULTS Using the same challenge dose of cocaine in both repeated treatment conditions (i.e. 20 mg/kg), the D(2 )class antagonists eticlopride and raclopride were less potent in attenuating the locomotor effects of cocaine in sensitized than those in non-sensitized animals. In contrast, when the lowest doses to maximally increase locomotion in each of the repeated treatment conditions were used (10 and 40 mg/kg), the D(2 )class antagonists attenuated the locomotor effects of cocaine in sensitized and non-sensitized animals with similar potencies. The ability of the D(1) class antagonist SCH23390 to attenuate the effects of cocaine demonstrated a similar dependency on the challenge dose. CONCLUSIONS These results show that, under the present conditions, the ability of dopamine antagonists to attenuate cocaine-induced locomotion is similar in sensitized and non-sensitized animals when challenged with pharmacologically equivalent doses of cocaine, but not when challenged with the same dose.
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Sakoori K, Murphy NP. Central administration of nociceptin/orphanin FQ blocks the acquisition of conditioned place preference to morphine and cocaine, but not conditioned place aversion to naloxone in mice. Psychopharmacology (Berl) 2004; 172:129-36. [PMID: 14624329 DOI: 10.1007/s00213-003-1643-3] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2002] [Accepted: 09/04/2003] [Indexed: 11/28/2022]
Abstract
RATIONALE Previous studies have suggested that nociceptin (known also as orphanin FQ) suppresses the rewarding potential of morphine and alcohol in the rat. However, little is known of the effect of nociceptin on the rewarding properties of these and other drugs in the mouse. OBJECTIVE To determine the effect of nociceptin on opiate or psychostimulant-induced conditioned place preference, or naloxone-induced conditioned place aversion in mice. METHODS C57BL6 mice were implanted with chronically indwelling intracranial cannulae targeted at the lateral cerebroventricle through which nociceptin (0.06, 0.6, or 6 nmol) could be administered. Animals were conditioned in an unbiased balanced paradigm to study the effect of nociceptin administration alone, or the effect of nociceptin on the acquisition of place conditioning to morphine, cocaine, or naloxone (all 7.6 mg/kg subcutaneous). RESULTS Administration of 0.06 nmol nociceptin alone stimulated locomotion during conditioning sessions, but had no hedonic effects. In contrast, administration of 6 nmol nociceptin alone markedly reduced basal locomotion during the conditioning sessions and induced a mild place aversion. Both morphine and cocaine induced robust place preferences, the acquisition of which was dose dependently suppressed by administration of nociceptin at doses of 0.6 nmol and above. Conditioning with naloxone produced a robust place aversion that was only weakly blocked by the maximum dose of nociceptin tested. CONCLUSION Nociceptin blocks the rewarding properties of drugs in both narcotic analgesic and psychostimulant classes in the mouse. In contrast, nociceptin has only a minor effect on the negative affective state experienced following naloxone administration.
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Scheggi S, Rauggi R, Nanni G, Tagliamonte A, Gambarana C. Repeated acetyl-l-carnitine administration increases phospho-Thr34 DARPP-32 levels and antagonizes cocaine-induced increase in Cdk5 and phospho-Thr75 DARPP-32 levels in rat striatum. Eur J Neurosci 2004; 19:1609-20. [PMID: 15066157 DOI: 10.1111/j.1460-9568.2004.03230.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Abstract Acute cocaine administration increases phosphorylation of dopamine and cAMP-regulated phosphoprotein (M(r) 32 kDa) (DARPP-32) at threonine (Thr)-34, whereas repeated cocaine administration increases DARPP-32 phosphorylation at Thr-75 in Sprague-Dawley rat striatum. Repeated acetyl-l-carnitine (ALCAR) administration persistently increases dopamine outflow in the nucleus accumbens. The present study examined the effect of repeated ALCAR administration on the DARPP-32 phosphorylation pattern in the nucleus accumbens and caudate-putamen. ALCAR increased phosphoThr-34 DARPP-32 levels and decreased phosphoThr-75 DARPP-32 levels, after 1 and 10 days of washout. We compared the effects of repeated cocaine and repeated ALCAR administrations on the behavioural response to cocaine challenge and on the DARPP-32 phosphorylation pattern and cyclin-dependent kinase 5 (Cdk5) levels in the striatum. We also studied whether ALCAR administered daily during or after cocaine sensitization procedure would interfere with the effects of cocaine. When the response to the cocaine challenge was assessed, cocaine- and ALCAR-treated rats showed a similar sensitized behavioural response, and rats receiving combined cocaine and ALCAR treatments, irrespective of treatment order, also showed a sensitized response. A week after the cocaine challenge, the two drugs had induced opposite modifications in DARPP-32 phosphorylation, as cocaine increased phosphorylation at Thr-75, while ALCAR increased phosphorylation at Thr-34. In cocaine plus ALCAR treated rats, irrespective of treatment order, ALCAR administration antagonized cocaine effects on DARPP-32 phosphorylation. Moreover, cocaine, but not ALCAR, increased DeltaFosB and Cdk5 expression, and the increase in Cdk5 was antagonized by ALCAR administration in rats receiving combined treatments. These effects were relatively persistent, as they were still present 7 days after the last treatment.
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Baker DA, McFarland K, Lake RW, Shen H, Toda S, Kalivas PW. N-acetyl cysteine-induced blockade of cocaine-induced reinstatement. Ann N Y Acad Sci 2004; 1003:349-51. [PMID: 14684458 DOI: 10.1196/annals.1300.023] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Müller CP, Thönnessen H, Barros M, Tomaz C, Carey RJ, Huston JP. Hippocampus 5-HT1A-receptors attenuate cocaine-induced hyperlocomotion and the increase in hippocampal but not nucleus accumbens 5-HT. Hippocampus 2004; 14:710-21. [PMID: 15318330 DOI: 10.1002/hipo.10209] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cocaine induces an increase in hippocampal and nucleus accumbens (Nac) serotonin (5-HT) concentration parallel to locomotor activation. Both effects can be modulated by systemic 5-HT(1A)-receptor agonism/antagonism. Given the contribution of the hippocampus to spontaneous behavioral activity, these observations suggest a role for hippocampal 5-HT as well in the modulation of cocaine effects on behavior. To determine the role of hippocampal 5-HT(1A)-receptors in cocaine effects on behavior and hippocampal 5-HT release, we used in vivo microdialysis in freely moving rats. The 5-HT(1A)-receptor agonist, 8-OH-DPAT (0, 0.1, 1 and 10 microM), was applied locally into the hippocampus by reversed dialysis followed by a cocaine (10 mg/kg) or saline i.p. injection. The hippocampal 5-HT(1A)-receptor activation attenuated cocaine-induced hyperlocomotion and rearing behavior dose-dependently. Parallel to that, the cocaine-induced 5-HT increase was attenuated dose-dependently in the hippocampus but was left unaffected in the Nac. The intra-hippocampal application of 8-OH-DPAT affected neither behavioral activity nor 5-HT concentration in the hippocampus and in the Nac. In accord with these findings, hippocampal 5-HT(1A)-receptors may not be directly involved in the regulation of spontaneous behavior or basal 5-HT concentration in the hippocampus and Nac. However, the results indicate an inhibitory role of hippocampal 5-HT(1A)-receptors in cocaine-induced hyperactivity and in the 5-HT increase evoked by cocaine in the hippocampus but not in the Nac.
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Appell M, Berfield JL, Wang LC, Dunn WJ, Chen N, Reith MEA. Structure-activity relationships for substrate recognition by the human dopamine transporter. Biochem Pharmacol 2004; 67:293-302. [PMID: 14698042 DOI: 10.1016/j.bcp.2003.09.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Information is available on the structure-activity relationships for dopamine as a substrate for uptake by the dopamine transporter. However, dopamine transport is a complex process involving substrate binding, translocation, release as well as transporter reorientation. The present study examines only the substrate recognition step by assessment of the potency of various dopamine-related compounds in inhibiting the binding of the cocaine analog [3H]2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane ([3H]WIN 35,428) to human dopamine transporters expressed in HEK-293 cells. alpha-Methylation of the side chain, the presence of the amine, and the 2-carbon-length of the side chain were found to be important for binding affinity, whereas beta-hydroxylation of the side chain and methoxylation at the phenyl ring generated weaker compounds. In addition, the presence of both m- and p-OH at the phenyl ring bestowed an increase in potency but the presence of p-OH alone a decrease. N-alkylation (propylation or methylation) had little or an even slightly beneficial effect on affinity, whereas alpha-carbonylation and alpha-methanoylation reduced affinity. Amino naphthalene compounds with a fused benzenoid ring system retained some potency consonant with the extended (i.e. beta-rotameric) trans (=anti) form of the side chain in dopamine when interacting with the transporter. In a second series of experiments, the interaction between dopamine and structural variants was assessed by monitoring the capability of a compound to shift the dopamine inhibition curve to the right as expected for a competitive inhibitor acting at the same site. Appreciable deviation from competitive interaction was observed by removal of the amine from the side chain, by alpha-carbonylation, and by alpha-methanoylation. Two blocker-type compounds, semi-rigid variants of cocaine, also displayed significant deviation. A substrate-based compound, inhibiting cocaine analog binding without interfering with dopamine recognition, could be a cocaine antagonist allowing conformational changes to occur during dopamine uptake.
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Jenab S, Festa ED, Russo SJ, Wu HBK, Inturrisi CE, Quinones-Jenab V. MK-801 attenuates cocaine induction of c-fos and preprodynorphin mRNA levels in Fischer rats. ACTA ACUST UNITED AC 2004; 117:237-9. [PMID: 14559159 DOI: 10.1016/s0169-328x(03)00319-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study shows that single (15 mg/kg) or binge (3x15 mg/kg) cocaine administration increases c-fos mRNA levels, but only binge cocaine administration increases preprodynorphin mRNA levels in the caudate/putamen of Fischer rats. This increase in both c-fos and preprodynorphin mRNA levels is attenuated by the noncompetitive NMDA antagonist MK-801 (0.25 mg/kg), suggesting a preferential role for NMDA receptor co-activation in cellular events leading to cocaine-induced behaviors.
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Licata SC, Schmidt HD, Pierce RC. Suppressing calcium/calmodulin-dependent protein kinase II activity in the ventral tegmental area enhances the acute behavioural response to cocaine but attenuates the initiation of cocaine-induced behavioural sensitization in rats. Eur J Neurosci 2004; 19:405-14. [PMID: 14725635 DOI: 10.1111/j.0953-816x.2003.03110.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the present experiments we administered an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonist (CNQX), N-methyl-D-aspartate (NMDA) receptor antagonist (AP-5), or l-type calcium channel blocker (diltiazem) directly into the ventral tegmental area (VTA) before each of four daily systemic cocaine injections in order to assess their influence on the initiation phase of behavioural sensitization. Results indicated that pretreatment with CNQX or AP-5 impaired the initiation of cocaine-induced behavioural sensitization. Intra-VTA administration of diltiazem significantly increased the behavioural activation induced by an acute cocaine injection, but impaired the development of cocaine-induced behavioural sensitization. Because AMPA and NMDA receptors, as well as l-type calcium channels are calcium permeable, we also investigated the role of the calcium-activated second messenger calcium/calmodulin-dependent protein kinase II (CaM-KII). Similar to the results obtained with diltiazem, administration of the CaM-KII inhibitor KN-93 into the VTA enhanced the acute behavioural response to cocaine but prevented the augmentation of cocaine-induced behavioural hyperactivity following repeated injections. Consistent with this finding, the behavioural hyperactivity produced by cocaine was markedly enhanced among homozygous alpha-CaM-KII knockout mice but the initiation of behavioural sensitization to cocaine was attenuated relative to wild-type mice. Separate experiments performed in rats demonstrated an increase in total protein levels of CaM-KII in the VTA 24 h after the last of seven daily injections of cocaine. Taken together, these results indicate that blocking l-type calcium channels or impairing CaM-KII activity in the VTA augments the acute behavioural hyperactivity induced by cocaine. The present findings also suggest that increased calcium influx through AMPA receptors, NMDA receptors and l-type calcium channels on dopaminergic neurons in the VTA contributes significantly to the initiation of behavioural sensitization by amplifying calcium signalling through CaM-KII.
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Busse GD, Lawrence ET, Riley AL. The modulation of cocaine-induced conditioned place preferences by alcohol: effects of cocaine dose. Prog Neuropsychopharmacol Biol Psychiatry 2004; 28:149-55. [PMID: 14687869 DOI: 10.1016/j.pnpbp.2003.09.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Busse and Riley [Biol. Psychiatry 26 (2002) 1373] have recently reported that alcohol dose dependently attenuated cocaine-induced place preferences. Although the mechanism for this effect is not known, it is possible that it is due to alcohol potentiating the aversive properties of cocaine, a potentiation that masks or abates cocaine's rewarding effects in this preparation. Given that the affective properties of cocaine (both aversive and rewarding) have been reported to be dose dependent, it might be expected that alcohol's ability to affect cocaine-induced place preferences would be influenced by changes in cocaine dose. To address this possibility, the following experiments assessed the effects of alcohol (0.5 g/kg) on place preferences induced by high (20, 30 and 40 mg/kg: Experiment 1) and low (2.5 and 5 mg/kg; Experiment 2) doses of cocaine. Specifically, every other day for four cycles male Sprague-Dawley rats were injected with cocaine, alcohol or one of several cocaine/alcohol combinations immediately before being placed on one side of a two-compartment place preference chamber. On alternate days, they were placed on the other side of the chamber after being injected with the drug vehicle(s). In Experiment 1, all doses of cocaine (20, 30 and 40 mg/kg) produced a significant preference for the drug-paired compartment, whereas alcohol alone produced no effect. When given in combination, alcohol attenuated the cocaine-induced place preference (at 30 and 40 mg/kg cocaine). In Experiment 2, neither cocaine (2.5 or 5 mg/kg) nor alcohol produced a significant effect when given alone. However, animals receiving the combination of alcohol and cocaine (5 mg/kg) displayed a significant place preference. These findings indicate that alcohol can both weaken and strengthen cocaine-induced place preferences, possibly via its effects on the rewarding and aversive properties of cocaine. The effect of alcohol is dependent on the dose of cocaine.
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Krivoshein AV, Hess GP. Mechanism-Based Approach to the Successful Prevention of Cocaine Inhibition of the Neuronal (α3β4) Nicotinic Acetylcholine Receptor. Biochemistry 2003; 43:481-9. [PMID: 14717603 DOI: 10.1021/bi034838l] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nicotinic acetylcholine receptor (nAChR) belongs to a family of five channel-forming proteins that regulate communication between the approximately 10(12) cells of the nervous system. A minimum mechanism of inhibition of the muscle-type nAChR (1) by the noncompetitive inhibitors cocaine and MK-801 [(+)-dizocilpine, an anticonvulsant] indicated they bind to a regulatory site, with higher affinity for the closed-channel form than for the open-channel form, thus shifting the equilibrium toward the closed-channel form and inhibiting receptor function. The mechanism predicts that compounds that bind to this regulatory site with equal or higher affinity for the open-channel conformation than for the closed-channel conformation will prevent receptor inhibition (1). Does a neuronal form of the receptor behave similarly? The mechanism of inhibition of the neuronal nAChR by cocaine and MK-801 using rapid chemical kinetic techniques was investigated. The alpha3beta4 nAChR stably expressed in HEK 293 cells was used in these investigations. Whole-cell currents originated from a major and minor nAChR isoform. Only the major isoform has been characterized. For the dominant, rapidly desensitizing isoform, the carbamoylcholine dissociation constant for the site controlling receptor activation, Kd, is 2 mM; the channel-opening equilibrium constant, Phi(-1), is 4; and the dominant desensitization rate constant, k34, is 20 s(-1). Cocaine inhibits the receptor noncompetitively, with an apparent KI of 84 and 26 microM at high and low carbamoylcholine concentrations, at which concentrations the receptor is mainly in the open- or closed-channel form, respectively. Similar results were obtained with MK-801. A combinatorially synthesized RNA ligand and a cocaine analogue alleviated cocaine inhibition of this neuronal receptor.
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Martin-Fardon R, Lorentz CU, Kamenka JM, Weiss F. 3-OH-pip-BTCP, a metabolite of the potent DA uptake blocker BTCP, exerts cocaine-like action in rats. Neuroreport 2003; 14:2439-44. [PMID: 14663207 DOI: 10.1097/00001756-200312190-00030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A previous study showed that N-[1-(2-benzo[b]thiophenyl)cyclohexyl]piperidin-3-ol (3-OH-pip-BTCP), an active metabolite of the potent dopamine reuptake inhibitor N-[1-(2-benzo[b]thiophenyl)cyclohexyl]piperidine (BTCP), exhibits stimulant effects in rats (i.e. increases dopamine levels in the nucleus accumbens and increases locomotion). The present study sought to further characterize the behavioral profile of 3-OH-pip-BTCP, specifically, its interaction with cocaine-maintained behavior. Cocaine self-administration was examined in 3-OH-pip-BTCP pretreated rats. 3-OH-pip-BTCP (0-20 mg/kg, i.p.) dose-dependently decreased cocaine self-administration. Additionally, 3-OH-pip-BTCP (10 mg/kg) shifted the cocaine dose-response to the left. Together, these results suggest that 3-OH-pip-BTCP shares similar reinforcing effects with cocaine and therefore may serve as a substitutive drug and possible agonist therapy for cocaine addiction.
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Wang LC, Cui XN, Chen N, Reith MEA. Binding of cocaine-like radioligands to the dopamine transporter at 37°C: effect of Na+ and substrates. J Neurosci Methods 2003; 131:27-33. [PMID: 14659820 DOI: 10.1016/s0165-0270(03)00230-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Although dopamine (DA) translocation by the DA transporter (DAT) requires Na+, a role for Na+ in the DA recognition step in the translocation cycle has been questioned. Thus, when binding techniques were used to indirectly measure the affinity of DA for DAT via its potency in inhibiting cocaine analog binding, no stimulation of DA binding was observed when assay temperature was at or below room temperature. The present work describes the use of 3H-labeled cocaine analogs for assays at 37 degrees C. When there is sufficient Na+ in the medium (> or =25 mM), [3H]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([3H]CIT) is an excellent radioligand to label human DAT with high affinity in membrane preparations of HEK-293 cells expressing the transporter. However, at 0 and 5 mM of Na+, appreciable binding of [3H]CIT occurs to proteins other than DAT, hampering accurate assessment of DAT-associated binding. No such problems occur with the binding of the 4-fluoro homolog of [3H]CIT, [3H]CFT at 37 degrees C, and this radioligand can be used at low [Na+], provided enough protein is present in the assay. The application of these assays show that, in contrast to the strong Na+ dependency of the binding of CFT, the substrates DA, D-amphetamine, p-tyramine, and DL-octopamine are not stimulated by Na+. This demonstrates that lack of Na+ stimulation of binding of substrates, including DA to DAT, in membrane preparations at room temperature is not caused by the reduced fluidity of the frozen state of the hydrocarbon membrane interior at this temperature as compared with the liquid-expanded state at 37 degrees C.
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Wilson LD, Shelat C. Electrophysiologic and Hemodynamic Effects of Sodium Bicarbonate in a Canine Model of Severe Cocaine Intoxication. ACTA ACUST UNITED AC 2003; 41:777-88. [PMID: 14677787 DOI: 10.1081/clt-120025342] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE Cocaine toxicity causes myocardial depression, malignant dysrhythmias, and sudden death, partially due to cocaine-related myocardial sodium channel blockade. Because of cocaine's ability to block cardiac sodium channels, sodium bicarbonate (NaHCO3) has been proposed as an antidote. The hypothesis of this study was that NaHCO3 would correct cocaine-induced conduction abnormalities and resultant hemodynamic compromise in an animal model simulating severe cocaine intoxication. METHODS DESIGN Prospective, controlled, experimental study in which 15 anesthetized dogs were given three successive boluses of cocaine (7 mg/kg) and then randomized to receive NaHCO3, 2 mEq/kg (n = 8) or placebo (n =7). MEASUREMENTS Arterial, left ventricular, and pulmonary artery pressures; cardiac output (CO); electrocardiogram (ECG); blood gases; and serum concentrations of cocaine were measured at baseline, at fixed time intervals after each bolus of cocaine, and then after administration of NaHCO3 or placebo. Statistical significance was determined by analysis of variance (ANOVA) for repeated measures. RESULTS Seven dogs experienced significant arrhythmias, including VT, pulseless electrical activity, and third-degree atrioventricular block; 2 of these dogs expired prior to receiving NaHCO3 and were excluded. Immediately after administering NaHCO3, QRS duration decreased by 30% (p < 0.001), returning to baseline more quickly than in the control group. This effect was associated with a brief 30% decrease in MAP (p = NS). After NaHCO3, CO increased 78% and remained increased for 5 min (p < 0.007). One dog converted from complete heart block to sinus rhythm shortly after NaHCO3 administration. CONCLUSIONS NaHCO3 improved ECG changes secondary to cocaine toxicity and improved myocardial function.
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Ikemoto S. Involvement of the olfactory tubercle in cocaine reward: intracranial self-administration studies. J Neurosci 2003; 23:9305-11. [PMID: 14561857 PMCID: PMC6740580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2003] [Revised: 08/20/2003] [Accepted: 08/27/2003] [Indexed: 04/27/2023] Open
Abstract
Cocaine has multiple actions and multiple sites of action in the brain. Evidence from pharmacological studies indicates that it is the ability of cocaine to block dopamine uptake and elevate extracellular dopamine concentrations, and thus increase dopaminergic receptor activation, that makes cocaine rewarding. Lesion studies have implicated the nucleus accumbens (the dorsal portion of the "ventral striatum") as the probable site of the rewarding action of the drug. However, the drug is only marginally self-administered into this site. We now report that cocaine (60 or 200 mm in 75 nl/infusion) is readily self-administered into the olfactory tubercle, the most ventral portion of the ventral striatum. Cocaine (200 mm) was self-administered marginally into the accumbens shell but not into the core, dorsal striatum, or ventral pallidum. In addition, cocaine injections (200 mm in 300 nl) into the tubercle but not the shell or ventral pallidum induced conditioned place preference. Rewarding effects of cocaine in the tubercle were blocked by coadministration of dopamine D1 or D2 antagonists (1 mm SCH 23390 or 3 mm raclopride) and were not mimicked by injections of the local anesthetic procaine (800 mm). In conclusion, the tubercle plays a critical role in mediating rewarding action of cocaine.
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Scheidweiler KB, Plessinger MA, Shojaie J, Wood RW, Kwong TC. Pharmacokinetics and Pharmacodynamics of Methylecgonidine, a Crack Cocaine Pyrolyzate. J Pharmacol Exp Ther 2003; 307:1179-87. [PMID: 14561847 DOI: 10.1124/jpet.103.055434] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Methylecgonidine is formed from cocaine base when smoked and has been identified in biological fluids of crack smokers. Ecgonidine, a metabolite of methylecgonidine formed via esterase activity, also has been identified in similar samples collected from crack smokers. Methylecgonidine and ecgonidine can be used as biomarkers to differentiate smoking from cocaine use via other routes of administration. We determined the pharmacokinetic properties of methylecgonidine and ecgonidine in sheep after intravenous administration of methylecgonidine at doses of 3.0, 5.6, and 10.0 mg/kg using gas chromatography-mass spectrometric assays. Methylecgonidine clears quickly from blood with a half-life of 18 to 21 min, whereas ecgonidine has a longer half-life of 94 to 137 min. Because ecgonidine clears more slowly, it may be a more effective biomarker of cocaine smoking. The cardiovascular stimulant effects of cocaine contrast with reported in vitro muscarinic agonist effects of methylecgonidine, decreasing contractility and stimulating nitric oxide production in cardiac cells and tissues. To test the hypothesis that methylecgonidine produces cardiovascular effects in vivo consistent with muscarinic agonism, methylecgonidine was administered to sheep intravenously (0.1-3.0 mg/kg) while monitoring heart rate and blood pressure. Significant hypotension and tachycardia occurred in all three sheep. Two of the three sheep demonstrated mild bradycardia 3 to 5 min after methylecgonidine injection. Intravenous pretreatment with atropine methyl bromide (15 microg/kg) antagonized methylecgonidine-induced hypotension in all three sheep, supporting the hypothesis that methylecgonidine acts as a muscarinic agonist in vivo.
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Jaworski JN, Kozel MA, Philpot KB, Kuhar MJ. Intra-Accumbal Injection of CART (Cocaine-Amphetamine Regulated Transcript) Peptide Reduces Cocaine-Induced Locomotor Activity. J Pharmacol Exp Ther 2003; 307:1038-44. [PMID: 14551286 DOI: 10.1124/jpet.103.052332] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Evidence suggests that CART (cocaine-amphetamine regulated transcript) peptides are mediators or modulators of the actions of psychostimulant drugs. In this study, the effects of intra-accumbal injections of rat long form (rl) CART 55-102 were examined. Injection of the peptide alone had no effect, but pretreatment with the peptide blunted or reduced the locomotor-inducing effects of cocaine after an i.p. injection. This effect was dose related and time limited, as expected. rlCART 1-27, a CART peptide fragment not active in other studies, was without effect on cocaine-induced locomotor activity. Because the actions of cocaine involve dopamine, the effect of rlCART 55-102 on dopamine-induced locomotor activity was examined. Intraaccumbal injection of dopamine produced a dose-related and time-limited increase in locomotor activity, as expected. Coinjection of rlCART 55-102 with dopamine blunted the effect. In summary, these data suggest that CART peptides in the nucleus accumbens would tend to oppose the actions of cocaine.
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Fadda P, Scherma M, Fresu A, Collu M, Fratta W. Baclofen antagonizes nicotine-, cocaine-, and morphine-induced dopamine release in the nucleus accumbens of rat. Synapse 2003; 50:1-6. [PMID: 12872287 DOI: 10.1002/syn.10238] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Evidence recently provided has suggested a specific involvement of the GABAergic system in modulating positive reinforcing properties of several drugs of abuse through an action on mesolimbic dopaminergic neurons. The GABA(B) receptor agonist baclofen has been proposed as a potential therapeutic agent for the clinical treatment of several forms of drug addiction. In the present study, using the in vivo microdialysis technique, we investigated the effect of baclofen on nicotine, cocaine, and morphine-induced increase in extracellular dopamine (DA) levels in the shell of the nucleus accumbens, a brain area supposedly involved in the modulation of the central effects of several drugs of abuse, of freely moving rats. As expected, nicotine (0.6 mg/kg s.c.), morphine (5 mg/kg s.c.), and cocaine (7.5 mg/kg i.p.) administration in rats induced a marked increase in extracellular DA concentrations in the nucleus accumbens, reaching a maximum value of +205 +/- 8.4%, +300 +/- 22.2%, and +370 +/- 30.7%, respectively. Pretreatment with baclofen (1.25 and 2.5 mg/kg i.p.) dose-dependently reduced the nicotine-, morphine-, and cocaine-evoked DA release in the shell of the nucleus accumbens. Furthermore, baclofen alone did not elicit changes in basal DA extracellular levels up to 180 min. Taken together, our data are in line with previous reports demonstrating the ability of baclofen to modulate the mesolimbic DAergic transmission and indicate baclofen as a putative candidate in the pharmacotherapy of polydrug abuse.
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Vanderschuren LJMJ, Beemster P, Schoffelmeer ANM. On the role of noradrenaline in psychostimulant-induced psychomotor activity and sensitization. Psychopharmacology (Berl) 2003; 169:176-85. [PMID: 12768274 DOI: 10.1007/s00213-003-1509-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Accepted: 04/07/2003] [Indexed: 10/26/2022]
Abstract
RATIONALE Psychostimulant drugs exert their behavioral effects primarily through enhancement of monoaminergic neurotransmission. Augmented dopamine activity is thought to play a critical role in the psychomotor stimulant effects of amphetamine and cocaine, as well as in the development of long-term behavioral sensitization evoked by repeated exposure to amphetamine. However, despite the fact that brain dopamine and noradrenaline systems are closely interconnected, the extent to which noradrenergic transmission contributes to these behavioral effects of psychostimulants is a relatively unexplored issue. OBJECTIVES By inhibiting noradrenergic neurotransmission with the alpha2-adrenoceptor agonist clonidine, the alpha1-antagonist prazosin and the beta-antagonist propranolol, we investigated the involvement of noradrenaline neurotransmission in the psychomotor stimulant and long-term sensitizing effects of d-amphetamine and cocaine in rats. METHODS Clonidine (0.003-0.1 mg/kg), prazosin (0.1-3.0 mg/kg) and propranolol (1.0-3.0 mg/kg) were administered prior to d-amphetamine (1.0 mg/kg), cocaine (15 mg/kg) or apomorphine (1.0 mg/kg) and psychomotor activity was measured. In separate studies, clonidine (0.03 mg/kg), prazosin (1.0 mg/kg) or propranolol (3.0 mg/kg) were co-administered with d-amphetamine (2.5 mg/kg) or cocaine (30 mg/kg) for 5 days, and locomotor sensitization was assessed 3 weeks post-treatment. RESULTS The psychomotor stimulant effect of d-amphetamine, but not that of cocaine or apomorphine, was dose-dependently inhibited by clonidine and prazosin, and enhanced by propranolol. Clonidine, prazosin, and propranolol did not influence the induction of sensitization by amphetamine or cocaine. CONCLUSIONS Enhancement of synaptic noradrenaline concentrations contributes to the psychomotor stimulant effect of d-amphetamine, but not cocaine or apomorphine. In addition, noradrenergic neurotransmission is not critically involved in the induction of psychostimulant sensitization.
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Hotsenpiller G, Wolf ME. Baclofen attenuates conditioned locomotion to cues associated with cocaine administration and stabilizes extracellular glutamate levels in rat nucleus accumbens. Neuroscience 2003; 118:123-34. [PMID: 12676144 DOI: 10.1016/s0306-4522(02)00951-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have used cocaine-conditioned locomotion in rats as an animal model for cocaine-conditioned responses that contribute to drug craving and relapse in human addicts. The purpose of the present study was to examine the ability of the GABA(B) agonist, baclofen, to attenuate such associative responses. First, experiments were conducted to identify a dose range of baclofen that did not impede exploratory or spontaneous behavior. This dose range was used during testing for conditioned locomotion specific to a flashing light and metronome, which were previously associated with administration of cocaine (PAIRED group) or saline (UNPAIRED group). At 2.0 mg/kg, baclofen attenuated conditioned locomotion in PAIRED subjects to the level of UNPAIRED subjects receiving saline or 2.0 mg/kg baclofen. Considering the importance of glutamate transmission in the nucleus accumbens (NAc) during associative responses to reward-related stimuli, the effect of baclofen on extracellular levels of glutamate in the NAc was tested with microdialysis. Baclofen (2.0 mg/kg) did not alter basal glutamate levels. However, baclofen pretreatment prevented the predatory odor, 2,5-dihydro-2,4,5-trimethylthiazoline, from increasing glutamate levels. This is the first report of baclofen modulating extracellular levels of glutamate in the NAc. Baclofen may prove to have general utility for suppressing stimulus-evoked increases in NAc glutamate levels. This could explain its ability to prevent cocaine-conditioned responses. In summary, our results suggest that enhancing GABA(B) transmission inhibits cocaine-conditioned responses, possibly by suppressing glutamate transmission in the NAc. A better understanding of interactions between GABA and glutamate transmission in the NAc may lead to the development of pharmacotherapies for cocaine craving.
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Skoubis PD, Maidment NT. Blockade of ventral pallidal opioid receptors induces a conditioned place aversion and attenuates acquisition of cocaine place preference in the rat. Neuroscience 2003; 119:241-9. [PMID: 12763085 DOI: 10.1016/s0306-4522(03)00121-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Peripheral administration of naloxone is known to produce a conditioned place aversion and to block cocaine-induced conditioned place preference. The ventral pallidum receives a dense enkephalinergic projection from the nucleus accumbens and is implicated as a locus mediating the rewarding and reinforcing effects of psychostimulant and opiate drugs. We sought to provide evidence for the involvement of pallidal opioid receptors in modulating affective state using the place-conditioning paradigm. Microinjection of naloxone (0.01-10 microg) into the ventral pallidum once a day for 3 days dose-dependently produced a conditioned place aversion when tested in the drug-free state 24 h after the last naloxone injection. This effect was reproduced using the mu-opioid receptor selective agonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP, 1 microg). Locomotor activity was reduced following injection of the highest dose of naloxone (10 microg) but elevated following CTOP (1 microg). Daily injection of cocaine (10 mg/kg) for 3 days produced a conditioned place preference 24 h later. This effect of cocaine was attenuated by concomitant intra-ventral pallidal injection of naloxone at a dose (0.01 microg) that had no significant aversive property when injected alone. In contrast, the locomotor activation induced by peripheral cocaine injection was unaffected by naloxone injection into the ventral pallidum. The data implicate endogenous opioid peptide systems within the ventral pallidum as regulators of hedonic status.
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Abstract
Ethanol and cocaine are frequently abused in combination, but little is known about how the subjective effects of the two drugs interact. The ability of ethanol and other GABA(A)-active compounds to alter the discriminative stimulus effects of cocaine was tested. Male Sprague-Dawley rats were trained to discriminate cocaine (10 mg/kg ip) from saline using either single- or cumulative-dosing methods. In single-dose testing, ethanol (0.1-0.5 g/kg) dose-dependently decreased cocaine-appropriate responding following the training dose of cocaine. Ethanol (0.5 g/kg) produced a rightward shift in the cocaine cumulative dose-effect curve. Ethanol (0.1-1.0 g/kg) failed to substitute for the discriminative stimulus effects of cocaine and the higher doses (1-2 g/kg) completely suppressed responding. Indirect GABA(A) agonists diazepam (benzodiazepine site) and pentobarbital (barbiturate site) did not block the discriminative stimulus effects of cumulative doses of cocaine. The GABA(A) antagonist pentylenetetrazol (PTZ) (10-40 mg/kg) did not substitute for cocaine. These findings suggest that ethanol can modulate the discriminative stimulus effects of cocaine, and that these effects may not be mediated by the actions of ethanol at the GABA(A) receptor.
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Nakao S. Is attenuation of extracellular dopamine increase in the nucleus accumbens the major mechanism by which dexmedetomidine increases the cocaine seizure threshold in rats? Anesthesiology 2003; 98:1520; author reply 1520. [PMID: 12766673 DOI: 10.1097/00000542-200306000-00043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Liu Y, He HR, Ding JH, Gu B, Wang H, Hu G. Iptkalim inhibits cocaine challenge-induced enhancement of dopamine levels in nucleus accumbens and striatum of rats by up-regulating Kir6.1 and Kir6.2 mRNA expression. Acta Pharmacol Sin 2003; 24:527-33. [PMID: 12791178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
AIM To investigate the effect and mechanism of novel ATP-sensitive potassium channel opener (KCO) iptkalim (IPT) on acute and cocaine challenge-induced alterations in the levels of dopamine (DA) and glutamate (Glu) from nucleus accumbens (NAc), striatum, and prefrontal cortex (PFC) in rats. METHODS The levels of DA and Glu were assayed using high performance liquid chromatography (HPLC) combined with amperometric and fluorescent detection, respectively. The mRNA levels of Kir6.1, Kir6.2, SUR1, and SUR2 were measured by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS IPT did not affect acute cocaine (30 mg/kg, ip)-induced elevations in either DA levels from NAc and striatum or Glu levels from NAc and PFC. An acute cocaine challenge (30 mg/kg, ip) on d 21 after withdrawal caused an elevation in DA levels in NAc and striatum. Moreover, the same treatment also increased Glu levels in PFC and NAc of cocaine-pretreated rats. Repeated IPT injections reversed cocaine challenge-induced DA increase in NAc and striatum. Cocaine challenge increased Kir6.1 and Kir6.2 mRNA expression in striatum and NAc and only elevate Kir6.2 expression in PFC in both cocaine-pretreated rats and rats pretreated with IPT plus cocaine. Moreover, expression of Kir6.1 and Kir6.2 mRNA was augmented in rats pretreated with IPT plus cocaine compared to rats pretreated with cocaine alone. No significant change was found in the SUR1 and SUR2 expression of all four groups. CONCLUSION IPT inhibited cocaine challenge-induced enhancement of DA levels in NAc and striatum by up-regulating Kir6.1 and Kir6.2 mRNA expression.
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Matsumoto RR, Liu Y, Lerner M, Howard EW, Brackett DJ. Sigma receptors: potential medications development target for anti-cocaine agents. Eur J Pharmacol 2003; 469:1-12. [PMID: 12782179 DOI: 10.1016/s0014-2999(03)01723-0] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The ability of cocaine to interact with sigma receptors suggests a viable target for medications development. Recently, numerous novel compounds and antisense oligodeoxynucleotides targeting sigma receptors have been synthesized and shown to prevent the behavioral toxicity and psychomotor stimulant effects of cocaine in animals. Protective doses of sigma receptor antagonists have also been shown to prevent changes in gene expression that are induced by cocaine. Together, the studies provide insight and promising future directions for the development of potential medications for the treatment of cocaine addiction and overdose.
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