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Guiraud J, van den Brink W. Sodium oxybate: A comprehensive review of efficacy and safety in the treatment of alcohol withdrawal syndrome and alcohol dependence. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 178:213-281. [PMID: 39523055 DOI: 10.1016/bs.irn.2024.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2024]
Abstract
Alcohol dependence (AD) significantly impacts public health, affecting 3.4% of people aged 18-64 and contributing to around 12% of overall mortality. Individuals with AD have a markedly reduced life expectancy, dying up to 28 years earlier than the general population. Current treatments for AD show limited efficacy, with many patients not responding to these interventions, highlighting the need for new therapeutic options with novel mechanisms of action. Sodium oxybate (SMO), the sodium salt of GHB, is one such candidate, pharmacologically similar to alcohol; it acts on several neurotransmitters including GABA, potentially mitigating withdrawal symptoms and craving for alcohol. SMO has been clinically used in Italy and Austria since the 1990s, approved for treating alcohol withdrawal syndrome (AWS) and for maintaining abstinence in AD patients. Several randomized clinical trials (RCTs) and meta-analyses showed evidence of SMO to be effective and safe in these indications. For AWS, SMO was more effective than placebo and as effective as benzodiazepines in reducing withdrawal symptoms. For maintaining abstinence, SMO significantly improved continuous abstinence duration and abstinence rate compared to placebo. Comprehensive clinical data indicate that SMO is well-tolerated, with main adverse effects being mild, such as dizziness and vertigo, and serious adverse events being rare. The effectiveness and safety of SMO, coupled with its approval in two EU countries affirm its potential as a treatment option for AD, particularly in severe cases. Further RCTs, especially with stratification by severity of dependence, are suggested to refine our understanding of its efficacy across different patient subgroups.
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Affiliation(s)
- Julien Guiraud
- Department of Psychiatry, Amsterdam Neuroscience, Amsterdam UMC, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Vergio, Clichy, France.
| | - Wim van den Brink
- Department of Psychiatry, Amsterdam Neuroscience, Amsterdam UMC, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Gamma hydroxybutyrate (GHB), gamma butyrolactone (GBL) and 1,4-butanediol (1,4-BD; BDO): A literature review with a focus on UK fatalities related to non-medical use. Neurosci Biobehav Rev 2015; 53:52-78. [PMID: 25843781 DOI: 10.1016/j.neubiorev.2015.03.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 03/08/2015] [Accepted: 03/25/2015] [Indexed: 11/22/2022]
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Nasrallah FA, Maher AD, Hanrahan JR, Balcar VJ, Rae CD. γ-Hydroxybutyrate and the GABAergic footprint: a metabolomic approach to unpicking the actions of GHB. J Neurochem 2010; 115:58-67. [PMID: 20681954 DOI: 10.1111/j.1471-4159.2010.06901.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gamma-hydroxybutyrate is found both naturally in the brain and self-administered as a drug of abuse. It has been reported to act at endogenous γ-hydroxybutyrate (GHB) receptors and GABA(B) receptors [GABA(B)R], and may also be metabolized to GABA. Here, the metabolic fingerprints of a range of concentrations of GHB were measured in brain cortical tissue slices and compared with those of ligands active at GHB and GABA-R using principal components analysis (PCA) to identify sites of GHB activity. Low concentrations of GHB (1.0 μM) produced fingerprints similar to those of ligands active at GHB receptors and α4-containing GABA(A)R. A total of 10 μM GHB clustered proximate to mainstream GABAergic synapse ligands, such as 1.0 μM baclofen, a GABA(B)R agonist. Higher concentrations of GHB (30 μM) clustered with GABA(C)R agonists and the metabolic responses induced by blockade of the GABA transporter-1 (GAT1). The metabolic responses induced by 60 and 100 μM GHB were mimicked by simultaneous blockade of GAT1 and GAT3, addition of low concentrations of GABA(C)R antagonists, or increasing cytoplasmic GABA concentrations by incubation with the GABA transaminase inhibitor vigabatrin. These data suggest that at concentrations > 30 μM, GHB may be active via metabolism to GABA, which is then acting upon an unidentified GABAergic master switch receptor (possibly a high-affinity extrasynaptic receptor), or GHB may itself be acting directly on an extrasynaptic GABA-R, capable of turning off large numbers of cells. These results offer an explanation for the steep dose-response curve of GHB seen in vivo, and suggest potential target receptors for further investigation.
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Carter LP, Koek W, France CP. Behavioral analyses of GHB: receptor mechanisms. Pharmacol Ther 2008; 121:100-14. [PMID: 19010351 DOI: 10.1016/j.pharmthera.2008.10.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 10/14/2008] [Indexed: 11/25/2022]
Abstract
GHB is used therapeutically and recreationally, although the precise mechanism of action responsible for its different behavioral effects is not entirely clear. The purpose of this review is to summarize how behavioral procedures, especially drug discrimination procedures, have been used to study the mechanism of action of GHB. More specifically, we will review several different drug discrimination procedures and discuss how they have been used to qualitatively and quantitatively study different components of the complex mechanism of action of GHB. A growing number of studies have provided evidence that the behavioral effects of GHB are mediated predominantly by GABAB receptors. However, there is also evidence that the mechanisms mediating the effects of GHB and the prototypical GABAB receptor agonist baclofen are not identical, and that other mechanisms such as GHB receptors and subtypes of GABAA and GABAB receptors might contribute to the effects of GHB. These findings are consistent with the different behavioral profile, abuse liability, and therapeutic indications of GHB and baclofen. A better understanding of the similarities and differences between GHB and baclofen, as well as the pharmacological mechanisms of action underlying the recreational and therapeutic effects of GHB, could lead to more effective medications with fewer adverse effects.
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Carai MA, Lobina C, Maccioni P, Cabras C, Colombo G, Gessa GL. γ-Aminobutyric AcidB (GABAB)-Receptor Mediation of Different In Vivo Effects of γ-Butyrolactone. J Pharmacol Sci 2008; 106:199-207. [DOI: 10.1254/jphs.fp0071487] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Quang LS, Colombo G, Lobina C, Maccioni P, Orru A, Gessa GL, Maher TJ, Carai MAM. Evaluation for the withdrawal syndrome from gamma-hydroxybutyric acid (GHB), gamma-butyrolactone (GBL), and 1,4-butanediol (1,4-BD) in different rat lines. Ann N Y Acad Sci 2007; 1074:545-58. [PMID: 17105952 DOI: 10.1196/annals.1369.055] [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: 11/12/2022]
Abstract
A severe and life-threatening gamma-hydroxybutyric acid (GHB) withdrawal syndrome, clinically similar to the alcohol withdrawal syndrome, is increasingly being reported in GHB addicts. We investigated for the occurrence of withdrawal in Wistar and Sprague-Dawley rats, and in the selectively bred lines of GHB-sensitive (GHB-S) and Sardinian alcohol-preferring (sP) rats, following chronic administration of GHB, gamma-butyrolactone (GBL), and/or 1,4-butanediol (1,4-BD). Using validated rodent alcohol withdrawal scoring scales, little to no spontaneous or pharmacologically precipitated withdrawal effects were observed in Wistar, Sprague-Dawley, or GHB-S rats. Conversely, sP rats displayed both spontaneous and precipitated audiogenic seizures following abrupt cessation of chronic GHB or 1,4-BD administration and following pharmacological challenge with the GABA(B) receptor-selective antagonist, SCH 50911, respectively.
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Affiliation(s)
- Lawrence S Quang
- Division of Pediatric Pharmacology & Critical Care, Rainbow Babies & Children's Hospital, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
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Koek W, Carter LP, Wu H, Coop A, France CP. Discriminative stimulus effects of flumazenil: perceptual masking by baclofen, and lack of substitution with gamma-hydroxybutyrate and its precursors 1,4-butanediol and gamma-butyrolactone. Behav Pharmacol 2006; 17:239-47. [PMID: 16572002 DOI: 10.1097/00008877-200605000-00005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pigeons trained to discriminate 0.1 mg/kg flumazenil, proposed as an in-vivo model to study interactions with diazepam-insensitive gamma-aminobutyric acid (GABA)A receptors, were tested with various GABAergic and non-GABAergic compounds. As a result of its pharmacological selectivity, the model was suitable for further examining previously reported flumazenil-like effects of gamma-hydroxybutyrate (GHB). Flumazenil and the GABAA negative modulator Ro 15-4513 produced 82-100% flumazenil-appropriate responding. Diazepam and the direct-acting GABAA agonists muscimol and 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-3-ol (THIP) produced 38-64% flumazenil-appropriate responding. GHB, its precursors 1,4-butanediol (1,4-BD) and gamma-butyrolactone (GBL), and the GABAB agonists baclofen and SKF97541 produced 0-24% flumazenil-appropriate responding. Baclofen shifted the flumazenil dose-response curve to the right and down, possibly involving perceptual masking of the discriminative stimulus effects of flumazenil by agonist activity at GABAB receptors. These masking effects of baclofen were blocked by the GABAB antagonist CGP35348. When CGP35348 was given together with GHB to block its GABAB agonist effects, GHB did not produce flumazenil-appropriate responding. Conceivably, effects of GHB at non-GABAB receptors (e.g. diazepam-sensitive GABAA receptors and GHB receptors) may interfere with the expression of its flumazenil-like discriminative stimulus effects. The asymmetric substitution between GHB and flumazenil is consistent with the hypothesis that the discriminative stimulus effects of GHB consist of several components, not all of which are mimicked by flumazenil.
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Affiliation(s)
- Wouter Koek
- Department of Psychiatry, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA.
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Smith MA, Gergans SR, Lyle MA. The motor-impairing effects of GABA(A) and GABA(B) agonists in gamma-hydroxybutyrate (GHB)-treated rats: cross-tolerance to baclofen but not flunitrazepam. Eur J Pharmacol 2006; 552:83-9. [PMID: 17026996 DOI: 10.1016/j.ejphar.2006.08.080] [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] [Received: 07/01/2006] [Revised: 08/28/2006] [Accepted: 08/31/2006] [Indexed: 11/27/2022]
Abstract
gamma-Hydroxybutyrate (GHB) is believed to function as a neurotransmitter in the mammalian brain by binding to a GHB-specific binding site. In addition, GHB may also indirectly enhance the neuroinhibitory actions of gamma-aminobutyric acid (GABA) by converting to GABA at neuronal synapses. The purpose of the present study was to examine the effects of representative GABA(A) and GABA(B) receptor agonists in rats treated chronically with GHB. Using a rotorod apparatus, the motor-impairing effects of GHB, the indirect GABA(A) receptor agonist, flunitrazepam, and the direct GABA(B) receptor agonist, baclofen, were examined before, during and after chronic treatment with 1000 mg/kg GHB, b.i.d. Prior to chronic treatment, all three drugs produced dose-dependent decreases in motor performance at low (8 rpm) and high (32 rpm) rotational speeds. Chronic treatment with GHB significantly decreased the potency of baclofen at both speeds, but did not alter the potency of either GHB or flunitrazepam. Following termination of chronic treatment, the potency of baclofen increased significantly at both speeds and returned to that observed prior to chronic treatment. These data indicate that chronic treatment with GHB confers tolerance to a GABA(B) receptor agonist under conditions in which tolerance is not conferred to a GABA(A) receptor agonist. These findings are consistent with the in vivo behavioral profile of GHB, which reveals a greater role for GABA(B) receptors than for GABA(A) receptors in its behavioral effects.
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Affiliation(s)
- Mark A Smith
- Department of Psychology, Davidson College, Davidson, NC 28035-7037, USA.
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Carai MAM, Colombo G, Gessa GL. Resuscitative effect of a gamma-aminobutyric acid B receptor antagonist on gamma-hydroxybutyric acid mortality in mice. Ann Emerg Med 2006; 45:614-9. [PMID: 15940094 DOI: 10.1016/j.annemergmed.2004.12.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
STUDY OBJECTIVE In the present study, a number of compounds were tested to evaluate their efficacy in exerting a protective effect on gamma-hydroxybutyric acid (GHB)-induced mortality in mice. The drugs investigated were the gamma-aminobutyric acid B (GABA B ) receptor antagonist SCH 50911, the GABA A receptor antagonist bicuculline, the benzodiazepine receptor antagonist flumazenil, the putative GHB receptor antagonist NCS-382, the opioid receptor antagonist naltrexone, and the amino acid and possible neuromodulator, taurine. METHODS All mice were initially treated with a lethal dose of GHB (7 g/kg, administered intragastrically). Once mice had displayed clear signs of GHB intoxication, animals from each group were treated acutely with either SCH 50911 (vehicle; 75, 150, and 300 mg/kg, administered intraperitoneally), bicuculline (vehicle; 2, 4, 6, and 8 mg/kg, administered intraperitoneally), flumazenil (vehicle; 1, 3, and 10 mg/kg, administered intraperitoneally), NCS-382 (vehicle; 50 and 200 mg/kg, administered intraperitoneally), naltrexone (vehicle; 3 and 10 mg/kg, administered intraperitoneally), or taurine (vehicle; 250 and 750 mg/kg, administered intraperitoneally). The various doses of each single drug were administered to 10 mice, randomly allocated throughout the experimental groups. Mortality was recorded every hour for the first 9 hours and subsequently 12, 18, and 24 hours after GHB injection. RESULTS In each experiment, all vehicle-treated mice died within 24 hours of GHB injection. Doses of 150 and 300 mg/kg SCH 50911 produced a marked protection on GHB-induced mortality, evidenced by the death of only 0 of 10 and 2 of 10 mice in the 150- and 300-mg/kg SCH 50911 groups, respectively. In contrast, at all doses tested, bicuculline, flumazenil, NCS-382, naltrexone, and taurine were not observed to exert any protective effect on GHB-induced mortality (9 to 10/10 mice died in each treatment group). CONCLUSION These results suggest an involvement of the GABA B receptor, at least in rodents, in the mediation of the lethal effects of GHB.
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Affiliation(s)
- Mauro A M Carai
- Bernard B. Brodie Department of Neuroscience, School of Medicine, University of Cagliari, and CNR Institute of Neuroscience, Section of Cagliari, Italy.
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Cook CD, Biddlestone L, Coop A, Beardsley PM. Effects of combining ethanol (EtOH) with gamma-hydroxybutyrate (GHB) on the discriminative stimulus, locomotor, and motor-impairing functions of GHB in mice. Psychopharmacology (Berl) 2006; 185:112-22. [PMID: 16453156 DOI: 10.1007/s00213-005-0276-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2005] [Accepted: 10/01/2005] [Indexed: 12/01/2022]
Abstract
RATIONALE Gamma-hydroxybutyrate (GHB) is a drug of abuse that is often coabused with ethanol (EtOH) and has been implicated as a date rape agent in conjunction with EtOH. Much information is lacking regarding the manner in which GHB interacts with EtOH. OBJECTIVE This study was designed to further characterize the behavioral effects of GHB alone and in combination with EtOH in male Swiss-Webster mice. METHODS The effects of GHB (0.1-1.0 g/kg) and EtOH (2.0-5.0 g/kg) alone, as well as the effects of GHB in combination with EtOH, were examined using an automated locomotor activity procedure, a functional observational battery (FOB) and a GHB drug discrimination procedure. RESULTS GHB decreased, whereas EtOH had little effect on locomotor activity. In the FOB, EtOH dose-dependently decreased activity in combination with 0.3 g/kg GHB. Alone, each drug had little effect on the righting reflex, but combining ineffective doses of GHB and EtOH significantly impaired righting. GHB and EtOH decreased forelimb grip strength. Combinations of ineffective doses of GHB and EtOH decreased forelimb grip strength when given together. GHB and EtOH impaired inverted screen performance, and EtOH increased the impairing effects of low, but not high, doses of GHB. GHB and EtOH increased hind limb splay, and EtOH increased the effects of 0.1 and 0.3 g/kg GHB on splay. GHB and EtOH decreased body temperature, and EtOH augmented the temperature-decreasing effects of GHB. EtOH produced less than 50% GHB-like discriminative stimulus effects, and GHB failed to alter the GHB-like discriminative stimulus effects of EtOH. CONCLUSIONS Overall, EtOH increased the effects of GHB on several gross measures of behavior and only partially occasioned the discriminative stimulus properties of GHB.
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Affiliation(s)
- Charles D Cook
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 410 North 12th Street, Smith Building, P.O. Box 980613, Richmond, VA 23298-0613, USA
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Goodwin AK, Froestl W, Weerts EM. Involvement of gamma-hydroxybutyrate (GHB) and GABA-B receptors in the acute behavioral effects of GHB in baboons. Psychopharmacology (Berl) 2005; 180:342-51. [PMID: 15739078 DOI: 10.1007/s00213-005-2165-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 12/22/2004] [Indexed: 10/25/2022]
Abstract
RATIONALE Gamma-hydroxybutyrate (GHB) is used for the treatment of narcolepsy, but it is also a drug of abuse. The behavioral pharmacology of GHB is not well defined. OBJECTIVES The current study was conducted to characterize the behavioral effects of a range of GHB doses in baboons (N=4) and to evaluate whether a GABA-B receptor antagonist and a GHB receptor antagonist would block a behaviorally active dose of GHB. METHODS In the first experiment, GHB (32-420 mg/kg) or vehicle was administered via an intragastric catheter. Sixty min after dosing, subjects were presented with a fine-motor task and observed. Food pellets were available under a fixed-ratio schedule of reinforcement 20-h/day. In the second experiment, the GABA-B antagonist CGP36742 (10-56 mg/kg), the putative GHB antagonist NCS-382 (0.1-10 mg/kg), or vehicle were administered alone and then in combination with GHB (320 mg/kg). RESULTS GHB dose-dependently decreased the number of food pellets earned. Performance in the motor task was also impaired and accompanied by signs of sedation and gastrointestinal discomfort. Pretreatment with CGP36742 antagonized GHB-induced suppression of food-maintained behavior and performance on the fine-motor task. Signs of abdominal discomfort, ataxia, and muscle relaxation produced by GHB were also reduced by pretreatment with CGP36742. In contrast, pretreatment with NCS-382 sometimes restored performance in the fine-motor task and increased food-maintained behavior, but the effect was variable across doses and baboons. Some doses of NCS-382 appeared to exacerbate ataxia and gastrointestinal discomfort produced by GHB in some subjects. CONCLUSIONS These data indicate that while GABA-B receptors play a significant role in mediating the behavioral effects of GHB in baboon, the role of GHB receptors is less clear.
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Affiliation(s)
- Amy K Goodwin
- Johns Hopkins Bayview, Behavioral Biology Research Center, 5510 Nathan Shock Dr., Suite 3000, Baltimore, MD 21224, USA
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Carai MAM, Quang LS, Atzeri S, Lobina C, Maccioni P, Orrù A, Gessa GL, Maher TJ, Colombo G. Withdrawal syndrome from γ-hydroxybutyric acid (GHB) and 1,4-butanediol (1,4-BD) in Sardinian alcohol-preferring rats. ACTA ACUST UNITED AC 2005; 15:75-8. [PMID: 15886053 DOI: 10.1016/j.brainresprot.2005.04.001] [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] [Received: 02/21/2005] [Revised: 04/05/2005] [Accepted: 04/07/2005] [Indexed: 11/30/2022]
Abstract
Gamma-hydroxybutyric acid (GHB) and its precursors, 1,4-butanediol (1,4-BD) and gamma-butyrolactone (GBL), are recreational drugs widely abused in the US, Europe and Australasia. A severe withdrawal syndrome from GHB, 1,4-BD and GBL has been increasingly documented over the last years, necessitating the development of a reliable animal model for investigations of potential therapeutic approaches. The present study describes the induction and occurrence of audiogenic seizures as a sign of withdrawal from GHB and 1,4-BD in selectively bred Sardinian alcohol-preferring (sP) rats, treated with escalating doses of GHB (1.5-3.5 g/kg, twice daily; i.g.) or 1,4-BD (500-1000 mg/kg, twice daily; i.g.) for 9 consecutive days. Acute administration of the selective GABA(B) receptor antagonist, SCH 50911, dramatically increased seizure occurrence. We propose that the inherent sensitivity of sP rats to different GHB-associated responses may have contributed to the unraveling of a phenomenon which was otherwise not recognizable in other rat strains.
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Affiliation(s)
- Mauro A M Carai
- Department of Neuroscience, University of Cagliari, Viale Diaz 182, I-09126 Cagliari, Italy
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Weerts EM, Goodwin AK, Griffiths RR, Brown PR, Froestl W, Jakobs C, Gibson KM. Spontaneous and precipitated withdrawal after chronic intragastric administration of gamma-hydroxybutyrate (GHB) in baboons. Psychopharmacology (Berl) 2005; 179:678-87. [PMID: 15645222 DOI: 10.1007/s00213-004-2079-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Accepted: 10/13/2004] [Indexed: 10/25/2022]
Abstract
RATIONALE gamma-Hydroxybuyrate (GHB) is a current drug of abuse that may produce physical dependence. OBJECTIVES The present study characterized the behavioral effects of chronic GHB in baboons (n = 4), and evaluated whether signs of withdrawal occurred (1) after administration of the GABA-B antagonist CGP36742 during chronic GHB administration (precipitated withdrawal) and (2) following discontinuation of chronic GHB administration (spontaneous withdrawal). METHODS Water (vehicle) and then GHB was continuously infused via intragastric (IG) catheters. GHB administration was initiated at 350 mg/kg per day, and the dose was increased by 100 mg/kg over 4 days to 750 mg/kg per day. Food pellets were available 20 h/day under a fixed ratio (FR5 or 10) schedule of reinforcement. Observation sessions and a 2-min fine motor task were conducted during vehicle and GHB administration. CGP36742 (32 and 56 mg/kg, IM) was administered during vehicle and chronic GHB administration. After a total of 32-36 days GHB administration was abruptly discontinued. Blood samples were collected during all interventions and analyzed for GHB content. RESULTS Chronic GHB decreased food-maintained behavior, disrupted performance of the fine motor task, and produced ataxia, muscle relaxation, tremors and jerks. At the end of GHB administration, plasma levels of GHB ranged from 486 to 2080 micromol/L. Administration of CGP36742 during chronic GHB administration produced increases in aggression, self-directed behaviors, vomit/retch, tremors and/or jerks, which is consistent with a precipitated withdrawal syndrome. Similar signs were observed when GHB administration was discontinued. Seizures were not observed. CONCLUSIONS These data indicate that chronic GHB administration produced physical dependence and that activation of the GABA-B receptor may be important for GHB physical dependence.
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Affiliation(s)
- Elise M Weerts
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Koek W, Carter LP, Lamb RJ, Chen W, Wu H, Coop A, France CP. Discriminative stimulus effects of gamma-hydroxybutyrate (GHB) in rats discriminating GHB from baclofen and diazepam. J Pharmacol Exp Ther 2005; 314:170-9. [PMID: 15774716 DOI: 10.1124/jpet.105.083394] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gamma-hydroxybutyrate (GHB) is a drug of abuse with actions at GHB and GABA receptors. This study tried to increase the selectivity of the discriminative stimulus effects of GHB by training animals to discriminate GHB from compounds that share pharmacological mechanisms with GHB. In comparison with a previous GHB versus saline discrimination (group 1), rats were trained to discriminate GHB (200 mg/kg) either from saline and the GABA(B) agonist baclofen (3.2 mg/kg) (group 2) or from saline, baclofen, and the positive GABA(A) modulator diazepam (1 mg/kg) (group 3). In all groups, GHB produced more than 80% GHB-appropriate responding. Baclofen produced 84% GHB-appropriate responding in group 1 but less than 30% in groups 2 and 3. Diazepam produced 68% GHB-appropriate responding in group 1, 30% in group 2, and only 5% in group 3. The GABA(B) receptor antagonists CGP35348 [3-[aminopropyl(diethoxymethyl)phosphinic acid] and CGP52432 [3-[[[((3,4-dichlorophenyl)methyl]amino]propyl]diethoxymethyl)phosphinic acid] attenuated the discriminative stimulus effects of GHB; CGP35348 did so with similar potency in all groups, but CGP52432 was significantly less potent in groups 2 and 3 than in group 1. In all groups, the GHB antagonist NCS-382 [(2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid] partially attenuated the discriminative stimulus effects of GHB. The selective GHB receptor ligand UMB86 (4-hydroxy-4-napthylbutanoic acid sodium) tended to attenuate the discriminative stimulus effects of GHB more in group 3 than in the other groups. The finding that animals can discriminate GHB from baclofen is further evidence that the effects of GHB and baclofen are not identical. Effects that GHB does not share with baclofen may involve GHB receptors or differential interactions with GABA(B) receptors.
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Affiliation(s)
- Wouter Koek
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., Mail Code 7792, San Antonio, TX 78229-3900, USA.
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Carter LP, Wu H, Chen W, Matthews MM, Mehta AK, Hernandez RJ, Thomson JA, Ticku MK, Coop A, Koek W, France CP. Novel gamma-hydroxybutyric acid (GHB) analogs share some, but not all, of the behavioral effects of GHB and GABAB receptor agonists. J Pharmacol Exp Ther 2005; 313:1314-23. [PMID: 15769868 DOI: 10.1124/jpet.104.077578] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
gamma-Hydroxybutyrate (GHB), a therapeutic for narcolepsy and a drug of abuse, has several mechanisms of action that involve GHB and GABA(B) receptors, metabolism to GABA, and modulation of dopaminergic signaling. The aim of these studies was to examine the role of GHB and GABA(B) receptors in the behavioral effects of GHB. Three approaches were used to synthesize GHB analogs that bind selectively to GHB receptors and are not metabolized to GABA-active compounds. Radioligand binding assays identified UMB86 (4-hydroxy-4-napthylbutanoic acid, sodium salt), UMB72 [4-(3-phenylpropyloxy)butyric acid, sodium salt], UMB73 (4-benzyloxybutyric acid, sodium salt), 2-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid (3-HPA), and 4-hydroxy-4-phenylbutyric acid as compounds that displace [(3)H]NCS-382 [5-[(3)H]-(2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7] annulen-6-ylidene) ethanoic acid] from GHB receptors at concentrations that do not markedly affect [(3)H]GABA binding to GABA(B) receptors. In rats and pigeons, GHB discriminative stimulus effects were not mimicked or attenuated by UMB86, UMB72, or 3-HPA up to doses that decreased responding. In mice, GHB, GHB precursors (gamma-butyrolactone and 1,4-butanediol) and GABA(B) receptor agonists [SKF97541 [3-aminopropyl(methyl)phosphinic acid hydrochloride] and baclofen] dose-dependently produced hypolocomotion, catalepsy, ataxia, and loss of righting. The GABA(B) receptor antagonist CGP35348 (3-aminopropyl(diethoxymethyl)phosphinic acid) attenuated catalepsy and ataxia that was observed after GHB and GABA(B) receptor agonists SKF97541 and baclofen. UMB86, UMB72, UMB73, and 3-HPA, like GHB, produced hypolocomotion, ataxia, and loss of righting; however, catalepsy was never observed with these compounds, which is consistent with the cataleptic effects of GHB being mediated by GABA(B) receptors. Ataxia that was observed with UMB86, UMB72, UMB73, and 3-HPA was not antagonized by CGP35348, suggesting that ataxia induced by these analogs is not mediated by GABA(B) receptors and might involve GHB receptors.
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Affiliation(s)
- Lawrence P Carter
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 78229-3900, USA
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Wong CGT, Chan KFY, Gibson KM, Snead OC. Gamma-hydroxybutyric acid: neurobiology and toxicology of a recreational drug. ACTA ACUST UNITED AC 2004; 23:3-20. [PMID: 15298489 DOI: 10.2165/00139709-200423010-00002] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
gamma-Hydroxybutyric acid (GHB) is a short-chain fatty acid that occurs naturally in mammalian brain where it is derived metabolically from gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. GHB was synthesised over 40 years ago and its presence in the brain and a number of aspects of its biological, pharmacological and toxicological properties have been elucidated over the last 20-30 years. However, widespread interest in this compound has arisen only in the past 5-10 years, primarily as a result of the emergence of GHB as a major recreational drug and public health problem in the US. There is considerable evidence that GHB may be a neuromodulator in the brain. GHB has multiple neuronal mechanisms including activation of both the gamma-aminobutyric acid type B (GABA(B)) receptor, and a separate GHB-specific receptor. This complex GHB-GABA(B) receptor interaction is probably responsible for the protean pharmacological, electroencephalographic, behavioural and toxicological effects of GHB, as well as the perturbations of learning and memory associated with supra-physiological concentrations of GHB in the brain that result from the exogenous administration of this drug in the clinical context of GHB abuse, addiction and withdrawal. Investigation of the inborn error of metabolism succinic semialdehyde deficiency (SSADH) and the murine model of this disorder (SSADH knockout mice), in which GHB plays a major role, may help dissect out GHB- and GABA(B) receptor-mediated mechanisms. In particular, the mechanisms that are operative in the molecular pathogenesis of GHB addiction and withdrawal as well as the absence seizures observed in the GHB-treated animals.
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Affiliation(s)
- C Guin Ting Wong
- Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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Castelli MP, Pibiri F, Carboni G, Piras AP. A review of pharmacology of NCS-382, a putative antagonist of gamma-hydroxybutyric acid (GHB) receptor. CNS DRUG REVIEWS 2004; 10:243-60. [PMID: 15492774 PMCID: PMC6741708 DOI: 10.1111/j.1527-3458.2004.tb00025.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gamma-hydroxybutyric acid (GHB), a naturally occurring metabolite of gamma-aminobutyric acid (GABA), has been postulated to act as a specific agonist of GHB receptors and as well as a weak GABA(B) receptor agonist. To date, 6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylideneacetic acid (NCS-382), a semirigid compound structurally related to GHB, is the only compound reported to be an antagonist of the GHB receptor sites. In this article we review the in vivo and in vitro pharmacological properties of NCS-382 and its interaction with GHB and GABA(B) receptors. Binding studies have demonstrated that NCS-382 is a stereoselective ligand for GHB-binding sites, with both, the high and the low component of population, showing the same distribution of GHB receptors. Indeed, this compound did not display affinity for GABA(A), GABA(B), or any other known receptors, while conflicting data have been reported as to its selective antagonist action at GHB receptor. Only a few studies have shown that NCS-382 antagonizes GHB-induced effect, but a re-evaluation of all data reported in the literature suggests that the antagonistic effect of this compound could be due to an indirect action at GABA(B) receptors. As revealed by several behavioral studies, NCS-382 fails to antagonize GHB discriminative stimuli, GHB-induced inhibition of locomotor activity and ataxia or suppression of operant responses. Moreover, it is capable of either eliciting qualitatively similar effects to those of GHB or enhancing some actions of GHB. In addition, the NCS-382-sensitive electrophysiological effects of endogenous and exogenous GHB observed in vivo have not been completely replicated in vitro. The only electrophysiological action of GHB antagonized in vitro by NCS-382 required a previous blockade of GABA(B) receptors. We concluded that NCS-382 is a good ligand but not a selective antagonist for GHB receptor.
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Affiliation(s)
- M Paola Castelli
- B. B. Brodie Department of Neuroscience, University of Cagliari, 09042 Monserrato (CA) Italy.
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de Fiebre CM, de Fiebre NEC, Coleman SL, Forster MJ. Comparison of the actions of gamma-butyrolactone and 1,4-butanediol in Swiss-Webster mice. Pharmacol Biochem Behav 2004; 77:705-10. [PMID: 15099915 DOI: 10.1016/j.pbb.2004.01.009] [Citation(s) in RCA: 11] [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: 08/19/2003] [Revised: 01/20/2004] [Accepted: 01/20/2004] [Indexed: 11/28/2022]
Abstract
The abuse of gamma-hydroxybutyrate (GHB) and two of its precursors, gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) are recognized as a public health concern. Here, we report dose-response and time-course analyses for effects of GBL and 1,4-BD on locomotor activity and body temperature in Swiss-Webster mice. Locomotor activity was measured for 2 h following a single injection of one of four doses of each agent plus a saline vehicle control. At 50 mg/kg, GBL produced an initial depression of locomotor activity which was followed by stimulation of locomotor activity. In contrast, 1,4-BD at 50 mg/kg stimulated locomotor activity without producing any depression of activity. At higher doses, GBL produced primarily a dose-dependent decrease in locomotor activity that returned to baseline within 50 min. In contrast, 1,4-BD produced an initial depression which was followed by stimulation of activity. Body temperature was measured rectally across a 2.5-h time course following injection with either agent. Both drugs produced hypothermia with peak effects occurring at 20 and 30 min for both drugs for the lower and higher dose, respectively. At 150 mg/kg, GBL produced a greater hypothermic response; however, no differences in hypothermic response were observed at 100 mg/kg. These studies demonstrate that the precursor drugs to GHB have some differential actions from each other.
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Affiliation(s)
- Christopher M de Fiebre
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, USA.
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Koek W, Flores LR, Carter LP, Lamb RJ, Chen W, Wu H, Coop A, France CP. Discriminative stimulus effects of gamma-hydroxybutyrate in pigeons: role of diazepam-sensitive and -insensitive GABA(A) and GABA(B) receptors. J Pharmacol Exp Ther 2004; 308:904-11. [PMID: 14718595 DOI: 10.1124/jpet.103.056093] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
gamma-Hydroxybutyrate (GHB) is an emerging drug of abuse with multiple mechanisms of action. This study is part of an effort to examine the role of GHB, GABA(A), and GABA(B) receptors in the discriminative stimulus (DS) effects of GHB. In pigeons trained to discriminate 100 mg/kg GHB from saline, GHB and its precursors gamma-butyrolactone and 1,4-butanediol produced 80 to 100% GHB-appropriate responding, whereas other compounds such as morphine, naltrexone, cocaine, and haloperidol produced no more than 34%. Compounds interacting with GABA receptors produced different maximal levels of GHB-appropriate responding. For example, the GABA(A) agonist muscimol produced 3%; the GABA(A)-positive modulators diazepam, pentobarbital, and ethanol, and the GABA(B) agonist baclofen produced levels ranging from 54 to 73%; and the benzodiazepine antagonist flumazenil and inverse agonist Ro 15-4513 (ethyl 8-azido-6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-alpha]-[1,4]-benzodiazepine-3-carboxylate) both produced 96%. The putative GHB receptor antagonist (2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid (NCS-382) produced 70% GHB-appropriate responding. The GABA(B) antagonist (3-aminopropyl)(diethoxymethyl)phosphinic acid (CGP 35348) completely blocked the GHB-like DS effects of NCS-382 and baclofen at a dose of 56 mg/kg. CGP 35348 also blocked the DS effects of GHB, but incompletely and only at a dose of 560 mg/kg. Together, these results are consistent with a role for diazepam-sensitive and -insensitive GABA(A) and GABA(B) receptors in the DS effects of GHB. Together with previous findings, the present results suggest that diazepam-insensitive GABA(A) receptors are more prominently involved in the DS effects of GHB in pigeons than in rats, whereas GABA(B) receptors are less prominently involved. Exploring the role of GHB receptors with NCS-382 is hampered by its GABA(B) receptor-mediated, GHB-like agonist activity.
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Affiliation(s)
- Wouter Koek
- Departments of Psychiatry and Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA.
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Castelli MP, Ferraro L, Mocci I, Carta F, Carai MAM, Antonelli T, Tanganelli S, Cignarella G, Gessa GL. Selective gamma-hydroxybutyric acid receptor ligands increase extracellular glutamate in the hippocampus, but fail to activate G protein and to produce the sedative/hypnotic effect of gamma-hydroxybutyric acid. J Neurochem 2003; 87:722-32. [PMID: 14535954 DOI: 10.1046/j.1471-4159.2003.02037.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Two gamma-hydroxybutyric acid (GHB) analogues, trans-gamma-hydroxycrotonic acid (t-HCA) and gamma-(p-methoxybenzyl)-gamma-hydroxybutyric acid (NCS-435) displaced [3H]GHB from GHB receptors with the same affinity as GHB but, unlike GHB, failed to displace [3H]baclofen from GABAB receptors. The effect of the GHB analogues, GHB and baclofen, on G protein activity and hippocampal extracellular glutamate levels was compared. While GHB and baclofen stimulated 5'-O-(3-[35S]thiotriphospate) [35S]GTPgammaS binding both in cortex homogenate and cortical slices, t-HCA and NCS-435 were ineffective up to 1 mm concentration. GHB and baclofen effect was suppressed by the GABAB antagonist CGP 35348 but not by the GHB receptor antagonist NCS-382. Perfused into rat hippocampus, 500 nm and 1 mm GHB increased and decreased extracellular glutamate levels, respectively. GHB stimulation was suppressed by NCS-382, while GHB inhibition by CGP 35348. t-HCA and NCS-435 (0.1-1000 microm) locally perfused into hippocampus increased extracellular glutamate; this effect was inhibited by NCS-382 (10 microm) but not by CGP 35348 (500 microm). The results indicate that GHB-induced G protein activation and reduction of glutamate levels are GABAB-mediated effects, while the increase of glutamate levels is a GHB-mediated effect. Neither t-HCA nor NCS-435 reproduced GHB sedative/hypnotic effect in mice, confirming that this effect is GABAB-mediated. The GHB analogues constitute important tools for understanding the physiological role of endogenous GHB and its receptor.
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Ren X, Mody I. Gamma-hydroxybutyrate reduces mitogen-activated protein kinase phosphorylation via GABA B receptor activation in mouse frontal cortex and hippocampus. J Biol Chem 2003; 278:42006-11. [PMID: 12923192 DOI: 10.1074/jbc.m304238200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
gamma-Hydroxybutyrate (GHB) naturally occurs in the brain, but its exogenous administration induces profound effects on the central nervous system in animals and humans. The intracellular signaling mechanisms underlying its actions remain unclear. In the present study, the effects of GHB on the activation (phosphorylation) of mitogen-activated protein kinases (MAP kinases), extracellular signal-regulated kinase 1 and 2 (ERK1/2), were investigated. Acute administration of GHB (500 mg/kg, intraperitoneal) induced a fast and long lasting inhibition of MAP kinase phosphorylation in both frontal cortex and hippocampus. The reduced MAP kinase phosphorylation was observed in the CA1 and CA3 areas but not in the dentate gyrus. Pretreatment with the specific gamma-aminobutyric acid, type B (GABAB), receptor antagonist CGP56999A (20 mg/kg, intraperitoneal) prevented the action of GHB, and the effect of GHB was mimicked by baclofen, a selective GABAB receptor agonist, whereas the high affinity GHB receptor antagonist NCS-382 (200 mg/kg, intraperitoneal) had no effect on GHB-inhibited MAP kinase phosphorylation. Moreover, the GHB dehydrogenase inhibitor valproate (500 mg/kg, intraperitoneal), which inhibits the conversion of GHB into GABA, failed to block the effect of GHB on MAP kinase phosphorylation. Altogether, these data suggest that GHB, administered in vivo, reduces MAP kinase phosphorylation via a direct activation of GABAB receptors by GHB. In contrast, GHB (10 mm for 15 min) was found ineffective on MAP kinase phosphorylation in brain slices, indicating important differences in the conditions required for the second messenger activating action of GHB.
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Affiliation(s)
- Xiuhai Ren
- Departments of Neurology and Physiology, The David Geffen School of Medicine, University of California at Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095, USA
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23
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Carter LP, Wu H, Chen W, Cruz CM, Lamb RJ, Koek W, Coop A, France CP. Effects of γ-Hydroxybutyrate (GHB) on Schedule-Controlled Responding in Rats: Role of GHB and GABAB Receptors. J Pharmacol Exp Ther 2003; 308:182-8. [PMID: 14569056 DOI: 10.1124/jpet.103.058909] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gamma-hydroxybutyrate (GHB), a metabolite of gamma-aminobutyric acid (GABA), is an increasingly popular drug of abuse and was recently approved for the treatment of narcolepsy (Xyrem). GHB and GABA receptors have been implicated in mediating effects of GHB; however, the relative importance of each of these receptors is unclear. This study evaluated the effects of selective antagonists in combination with GHB and related compounds on schedule-controlled responding. Eight male Sprague-Dawley rats responded under a fixed-ratio schedule of food presentation. Cumulative dose-effect curves were generated and ED50 values calculated to evaluate the relative potency at decreasing responding. The rank-order potency was as follows: diazepam = baclofen > gamma-butyrolactone (GBL) > 1,4-butanediol (1,4-BDL) = GHB. All compounds decreased responding 20 min after administration. The duration of action of diazepam, GHB, and GBL was shorter than that of 1,4-BDL and baclofen. p-3-Aminopropyl-p-diethoxymethyl phosphinic acid (CGP 35348) antagonized the rate-decreasing effects of baclofen and not GHB; flumazenil antagonized the effects of diazepam and not GHB. The GHB receptor antagonist (2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid (NCS-382) did not attenuate the rate-decreasing effects of GHB, baclofen, or diazepam; larger doses of NCS-382 further decreased rate of responding when given in combination with each of these compounds. These studies show that GBL, 1,4-BDL, and GHB differ significantly in potency and duration of action. The ability of CGP 35348 to antagonize the rate-decreasing effects of baclofen may be limited by the involvement of multiple GABAB receptor subtypes and the lack of antagonism of GHB by NCS-382 may be due to its own GHB-like effects.
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Affiliation(s)
- Lawrence P Carter
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA
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Gould GG, Mehta AK, Frazer A, Ticku MK. Quantitative autoradiographic analysis of the new radioligand [(3)H](2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene) ethanoic acid ([(3)H]NCS-382) at gamma-hydroxybutyric acid (GHB) binding sites in rat brain. Brain Res 2003; 979:51-6. [PMID: 12850570 DOI: 10.1016/s0006-8993(03)02865-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
(2E)-(5-Hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene) ethanoic acid (NCS-382) is an antagonist for gamma-hydroxybutyric acid (GHB) at GHB receptor sites. Advantages of using [(3)H]NCS-382 over [(3)H]GHB in radioligand binding studies are that unlike GHB, NCS-382 does not appear to bind to, activate, or interfere with the functioning of GABA(B) or GABA(A) receptors, either directly or indirectly. Herein we establish a protocol for use of [(3)H]NCS-382 by quantitative autoradiography. GHB was used to define non-specific binding, since it displaced [(3)H]NCS-382 to an extent equivalent to NCS-382. Among many areas of brain examined, two regions in which high specific binding of [(3)H]NCS-382 occurred were the hippocampus and cerebral cortex. Areas such as the striatum and nucleus accumbens exhibited intermediate levels of specific binding. No or very low binding was observed in other areas such as the cerebellum and dorsal raphe nucleus. The distribution of GHB binding sites as defined by [(3)H]NCS-382 suggests that GHB may play a role in neuromodulation or neurotransmission in frontal brain areas.
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Affiliation(s)
- Georgianna G Gould
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, 78229-3900, San Antonio, TX, USA.
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Lamb RJ, Munn J, Duiker NJ, Coop A, Wu H, Koek W, France CP. Interactions of gamma-hydroxy butyrate with ethanol and NCS 382. Eur J Pharmacol 2003; 470:157-62. [PMID: 12798953 DOI: 10.1016/s0014-2999(03)01791-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined the effects of gamma-hydroxy butyrate (GHB) alone and in combination with either ethanol or NCS 382 [(2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene], a purported antagonist at the GHB receptor. These effects were examined on the responding of rats under a fixed-ratio (FR) 10 schedule of sugar solution (14%, w/v; 0.1 ml) presentation. GHB dose-relatedly decreased responding. When GHB was combined with ethanol, the effects of the two drugs were less than additive. NCS 382 did not antagonize the rate-decreasing effects of GHB. These observations are consistent with the notion that many of the behavioral actions of exogenously administered GHB result from GHB's actions at sites other than the GHB receptor, and are inconsistent with the popular notion that the effects of GHB and ethanol are synergistic.
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Affiliation(s)
- Richard J Lamb
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, Mail Code 7792, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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Carter LP, Flores LR, Wu H, Chen W, Unzeitig AW, Coop A, France CP. The role of GABAB receptors in the discriminative stimulus effects of gamma-hydroxybutyrate in rats: time course and antagonism studies. J Pharmacol Exp Ther 2003; 305:668-74. [PMID: 12606639 DOI: 10.1124/jpet.102.047860] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
gamma-Hydroxybutyrate (GHB) is a neurotransmitter in brain and an emerging drug of abuse, although its mechanism of action is poorly understood. This study characterized the role of GABA(A), GABA(B), and other receptors in the discriminative stimulus effects of GHB. Eight rats reliably discriminated 200 mg/kg GHB from saline after a median of 35 (range: 23-41) training sessions. GHB, a metabolic precursor 1,4-butanediol (1,4-BDL), and the GABA(B) agonist (+/-)baclofen all occasioned greater than 83% responding on the GHB lever. The onset of action was similar for GHB and 1,4-BDL; however, 1,4-BDL exhibited a longer duration of action than GHB. The GHB precursor gamma-butyrolactone, the benzodiazepine diazepam, the neuroactive steroid pregnanolone, the opioid agonist morphine, and the N-methyl-d-aspartate antagonist ketamine elicited substantial GHB-appropriate responding, although none occasioned greater than 66% drug-lever responding. The barbiturate pentobarbital and the GABA(A) receptor agonist muscimol did not occasion greater than 17% drug-lever responding at any dose tested. The benzodiazepine antagonist flumazenil attenuated GHB-lever responding occasioned by diazepam, but not GHB. The GABA(B) receptor antagonist CGP 35348 antagonized GHB-lever responding occasioned by baclofen or GHB. Small doses of the purported GHB receptor antagonist (2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid (NCS-382) attenuated partially the effects of GHB, whereas larger doses of NCS-382 alone occasioned partial GHB-lever responding. These results implicate GABA(B) mechanisms in the discriminative stimulus effects of GHB and further suggest that the effects of 1,4-BDL under these conditions result from its conversion to GHB. That NCS-382 shares effects with GHB could explain the lack of antagonism reported for NCS-382 in some studies.
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Affiliation(s)
- Lawrence P Carter
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
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