Gamma-hydroxybutyric acid

Systematic assessment of gamma hydroxybutyrate (GHB) effects during and after acute intoxication

We adapted and tested a previously published questionnaire battery eliciting sensory and cognitive symptoms during (acute) and immediately after (post-acute) GHB intoxication. Studying 125 GHB users, we assessed the instrument's internal consistency using Cronbach's alpha (CA) and responsiveness to change comparing acute and post-acute symptoms. The final 14-item battery demonstrated good internal consistency (CA >or= 0.85, both acute and post-acute). The median symptom score (possible range 0-64) was 30 (acute) and 6 (post-acute; difference p < 0.001). This modified substance-specific symptom battery, which is easily administered, demonstrated excellent performance characteristics. It can be used to study GHB and, potentially, related drugs of abuse.

Baclofen and gamma-hydroxybutyrate withdrawal

INTRODUCTION

Benzodiazepine treatment of life-threatening gamma-hydroxybutyrate (GHB) withdrawal is frequently unsatisfactory. Animal studies suggest strongly that treatment with GABA(B) agonists, such as baclofen, will be a more effective strategy.

METHODS

A case report from the medical intensive care unit (ICU) of the university tertiary care hospital.

RESULTS

A 61-year-old woman was admitted to the medical ICU for severe withdrawal symptoms from chronic GHB use. This manifested as delirium, tremor, and seizures despite only small decreases in GHB dose and treatment with benzodiazepines. The addition of baclofen allowed the rapid sequential decreases in the GHB dose without seizure or delirium and resulted in long-term improvement of her tremor.

CONCLUSIONS

Baclofen, a GABA(B) agonist, may be a useful agent in the treatment of severe GHB withdrawal.

[Poisoning by liquid ecstasy (GHB) in hospital emergency departments of Barcelona: a 2-years study]

BACKGROUND AND OBJECTIVE

Liquid ecstasy (GHB) is a new cause of drug overdose in our country. To describe the epidemiological profile and clinical manifestations, we analyzed cases of poisoning by GHB attended by the Emergency Departments (ED) of 2 hospitals of the city of Barcelona.

PATIENTS AND METHOD

During two years (2003-2004) all cases of poisoning or overdose due to GHB attended in the ED of the Hospital del Mar and the Hospital Clinic of Barcelona were collected. The diagnosis was clinical and/or by means of toxicological analysis. Epidemiological, clinical, laboratory and therapeutic variables as well as the evolution were collected.

RESULTS

A total of 339 patients (mean age 23.5 years, 62% male) were identified. Most patients (89%) were admitted during the early morning and during weekends (89%). Symptoms began in a public place in 97%. Reduced consciousness was the most important clinical manifestation, since 72% of patients had a Glasgow Coma Score of 12 or less. Seventy per cent stated having consumed GHB with other drugs, mainly ethyl alcohol (53%) and cocaine (16%). Some form of treatment was required in 32% of cases and 20 cases were administered an antidote: naloxone (12 cases), flumazenil (8 cases) and physostigmine (6 cases). Five patients needed orotracheal intubation and ventilatory support. One patient needed advanced vital support. There were no deaths.

CONCLUSIONS

GHB intoxication leading to reduced consciousness is a frequent motive for admission to the ED, mostly in young people and in the early morning during the weekend. GHB intoxication should be discarded in all cases of coma of unknown origin.

Care of the adolescent sexual assault victim

Sexual assault is a broad-based term that encompasses a wide range of sexual victimizations including rape. Since the American Academy of Pediatrics published its last policy statement on sexual assault in 2001, additional information and data have emerged about sexual assault and rape in adolescents and the treatment and management of the adolescent who has been a victim of sexual assault. This report provides new information to update physicians and focuses on assessment and care of sexual assault victims in the adolescent population.

New developments for the pharmacological treatment of alcohol withdrawal syndrome. A focus on non-benzodiazepine GABAergic medications

Alcohol withdrawal syndrome (AWS) can be a life-threatening condition affecting some alcohol-dependent patients who abruptly discontinue or decrease their alcohol consumption. The main objectives of the clinical management of AWS include: to decrease the severity of symptoms, prevent more severe withdrawal clinical manifestations and facilitate entry of the patient into a treatment program in order to attempt to achieve and maintain long-term abstinence from alcohol. At present, benzodiazepines represent the drugs of choice in the treatment of AWS. However, in line with the possible side effects and addictive properties related to benzodiazepine use, there is growing evidence to suggest that non-benzodiazepine GABAergic compounds represent promising medications in the treatment of alcohol-dependent patients. This review focuses on research into non-benzodiazepine GABAergic medications for the treatment of AWS. Among them, carbamazepine, gabapentin and valproic acid are the most studied. The studies on carbamazepine seem to be the most compelling. Preliminary data have also suggested the possible utility of baclofen and topiramate, although further evidence is needed. The promising results in terms of both safety and efficacy are reported. However, we also note the need of more methodologically controlled studies on a greater number of patients, involving more complicated forms of AWS.

Pathogenesis of CNS involvement in disorders of amino and organic acid metabolism

Inherited disorders of amino and organic acid metabolism have a high cumulative frequency, and despite heterogeneous aetiology and varying clinical presentation, the manifestation of neurological disease is common. It has been demonstrated for some of these diseases that accumulating pathological metabolites are directly involved in the manifestation of neurological disease. Various pathomechanisms have been suggested in different in vitro and in vivo models including an impairment of brain energy metabolism, an imbalance of excitatory and inhibitory neurotransmission, altered transport across the blood-brain barrier and between glial cells and neurons, impairment of myelination and disturbed neuronal efflux of metabolic water. This review summarizes recent knowledge on pathomechanisms involved in phenylketonuria, glutaric aciduria type I, succinic semialdehyde dehydrogenase deficiency and aspartoacylase deficiency with examples, highlighting general as well as disease-specific concepts and their putative impact on treatment.

Hazardous use of gamma hydroxybutyrate: driving under the influence

Focus group discussions elicited descriptive experiences of driving under the influence of gamma hydroxybutyrate (GHB), and uncovered motivations that led participants to decide whether to get behind the wheel after ingesting this illegal psychoactive substance. Of the 51 current and past users interviewed, average age 31.1 +/- 7.7 years, 40% were female. All were recruited from the San Francisco Bay Area, in 2004. Factors making users vulnerable to adverse complications of driving while under the influence of GHB are also examined. Study limitations were noted. Implications for various law enforcement agencies and health professionals are derived from the data.

Comparing and combining gamma-hydroxybutyric acid (GHB) and naltrexone in maintaining abstinence from alcohol: an open randomised comparative study

Maintaining abstinence from alcohol is the main goal in treating alcohol dependence. Our aim was to evaluate the efficacy of gamma-hydroxybutyric acid (GHB) and naltrexone (NTX), and their combination in maintaining abstinence. Fifty-five alcoholics were randomly enrolled in three groups and treated for 3 months with GHB, GHB plus NTX, and NTX, respectively. At the end of treatments, abstinence was maintained by 13 patients (72.2%) in combination group, 8 patients (40%; P=0.03) in GHB group, and one patient (5.9%; P=0.0001) in NTX group. Relapses in heavy drinking tended to occur more frequently in GHB group (15%) than in either combination group (no cases) or NTX group (5.9%), but such differences were not statistically significant. The GHB/NTX combination was more effective than either drug given alone; this suggests that the two drugs combine their different actions synergistically without suppressing the favourable effects of each other.

A ketogenic diet rescues the murine succinic semialdehyde dehydrogenase deficient phenotype

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a heritable disorder of GABA degradation characterized by ataxia, psychomotor retardation and seizures. To date, there is no effective treatment for SSADH deficiency. We tested the hypothesis that a ketogenic diet (KD) would improve outcome in an animal model of SSADH deficiency, the SSADH knockout mouse (Aldh5a1-/-). Using a 4:1 ratio of fat to combined carbohydrate and protein KD we set out to compare the general phenotype, in vivo and in vitro electrophysiology and [35S]TBPS binding in both Aldh5a1-/- mice and control (Aldh5a1+/+) mice. We found that the KD prolonged the lifespan of mutant mice by >300% with normalization of ataxia, weight gain and EEG compared to mutants fed a control diet. Aldh5a1-/- mice showed significantly reduced mIPSC frequency in CA1 hippocampal neurons as well as significantly decreased [35S]TBPS binding in all brain areas examined. In KD fed mutants, mIPSC activity normalized and [35S]TBPS binding was restored in the cortex and hippocampus. The KD appears to reverse toward normal the perturbations seen in Aldh5a1-/- mice. Our data suggest that the KD may work in this model by restoring GABAergic inhibition. These data demonstrate a successful experimental treatment for murine SSADH deficiency using a KD, giving promise to the idea that the KD may be successful in the clinical treatment of SSADH deficiency.

RGS2 modulates coupling between GABAB receptors and GIRK channels in dopamine neurons of the ventral tegmental area

Agonists of GABA(B) receptors exert a bi-directional effect on the activity of dopamine (DA) neurons of the ventral tegmental area, which can be explained by the fact that coupling between GABA(B) receptors and G protein-gated inwardly rectifying potassium (GIRK) channels is significantly weaker in DA neurons than in GABA neurons. Thus, low concentrations of agonists preferentially inhibit GABA neurons and thereby disinhibit DA neurons. This disinhibition might confer reinforcing properties on addictive GABA(B) receptor agonists such as gamma-hydroxybutyrate (GHB) and its derivatives. Here we show that, in DA neurons of mice, the low coupling efficiency reflects the selective expression of heteromeric GIRK2/3 channels and is dynamically modulated by a member of the regulator of G protein signaling (RGS) protein family. Moreover, repetitive exposure to GHB increases the GABA(B) receptor-GIRK channel coupling efficiency through downregulation of RGS2. Finally, oral self-administration of GHB at a concentration that is normally rewarding becomes aversive after chronic exposure. On the basis of these results, we propose a mechanism that might underlie tolerance to GHB.

Diagnostic challenges in a severely delayed infant with hypersomnolence, failure to thrive and arteriopathy: a unique case of gamma-hydroxybutyric aciduria and Williams syndrome

Metabolic work-up, pursued in a 5-month-old female infant with hypersomnolence, failure to thrive, and global developmental delay, led to the identification of gamma-hydroxybutyric aciduria (GHB). Succinic semialdehyde dehydrogenase deficiency (SSADH deficiency) was confirmed enzymatically and molecularly. Characteristic dysmorphic facies, cardiovascular anomalies, and hypercalcemia led to clinical suspicion of Williams-Beuren syndrome (WS), confirmed by cytogenetic studies. This rare occurrence of two unrelated genetic conditions highlights the importance of instituting comprehensive metabolic studies despite the presence of syndromic findings, even in the absence of other metabolic abnormalities that may be indicative of metabolic disease such as hyperammonemia, hypoglycemia, ketonuria, and metabolic acidosis.

Effects of gamma hydroxybutyric acid on inhibition and excitation in rat neocortex

The mechanism by which the sedative and amnestic recreational drug gamma hydroxybutyric acid (GHB) acts is controversial. Some studies indicate that it acts at its unique receptor, while others demonstrate effects mediated through the GABAB receptor. We examined the effect of GHB on evoked GABAA receptor-mediated mono- and polysynaptic inhibitory postsynaptic currents (IPSCs) as well as on N-methyl-d-aspartate (NMDA) and AMPA-mediated excitatory postsynaptic currents (EPSCs) in layers II/III pyramidal cells of the frontal cortex of rat brain. One millimolar (mM) GHB suppressed monosynaptic IPSCs by 20%, whereas polysynaptic IPSCs were reduced by 56%. GHB (1 mM) also produced a significant suppression of NMDA-mediated EPSCs by 53% compared with 27% suppression of AMPA-mediated EPSCs. All effects of GHB on IPSCs and EPSCs were reversed by the specific GABAB antagonist CGP 62349, but not by the GHB receptor antagonist (2E)-5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid. Consistent with a presynaptic site of action, GHB reduced the frequency but not the amplitude of AMPA receptor-mediated mEPSCs and had no effect on postsynaptic currents evoked by direct application of NMDA. Finally, even though GHB appeared to be acting at presynaptic GABAB receptors, GHB and the GABAB agonist baclofen appeared to have opposite potencies for depression of NMDA- vs. AMPA-mediated EPSCs. GHB showed a preference for depressing NMDA responses while baclofen more potently suppressed AMPA responses. The suppression of NMDA more than AMPA responses by GHB at intoxicating doses may make it attractive as a recreational drug and may explain why GHB is abused and baclofen is not.

Antagonism of phencyclidine-induced stimulus control in the rat by other psychoactive drugs

It has been observed that agents with agonist activity at 5-HT2A receptors prevent neurotoxicity induced by the non-competitive NMDA antagonist, dizocilpine (MK-801). Subsequent behavioral studies reported complete antagonism by LSD and DOM of the stimulus effects of the related NMDA antagonist, phencyclidine [PCP]. The present study sought to extend those observations to include other psychoactive drugs. Male F-344 rats were trained in a 2-lever, fixed-ratio 10, food-reinforced task with PCP (3.0 mg/kg; IP; 30 min pretreatment) as a discriminative stimulus. Tests of generalization were then conducted using the training dose of PCP in combination with a range of doses of DOM, LSD, d-amphetamine, MDMA, psilocybin, buspirone, and GHB. All of the drugs tested in combination with PCP produced a statistically significant diminution of PCP-appropriate responding but for none was antagonism complete. These data, obtained using a stimulus control model of the hallucinogenic effects of PCP, fail to support the hypothesis that LSD and DOM completely antagonize stimulus control by PCP. Instead, the data suggest complex interactions between PCP-induced stimulus control and a variety of psychoactive drugs including GHB, an agent with no known affinity for serotonergic receptors.

Typical versus atypical absence seizures: network mechanisms of the spread of paroxysms

PURPOSE

Typical absence seizures differ from atypical absence seizures in terms of semiology, EEG morphology, network circuitry, and cognitive outcome, yet have the same pharmacological profile. We have compared typical to atypical absence seizures, in terms of the recruitment of different brain areas. Our initial question was whether brain areas that do not display apparent paroxysmal discharges during typical absence seizures, are affected during the ictal event in terms of synchronized activity, by other, distant areas where seizure activity is evident. Because the spike-and-wave paroxysms in atypical absence seizures invade limbic areas, we then asked whether an alteration in inhibitory processes in hippocampi may be related to the spread seizure activity beyond thalamocortical networks, in atypical seizures.

METHODS

We used two models of absence seizures in rats: one of typical and the other of atypical absence seizures. We estimated phase synchronization, and evaluated inhibitory transmission using a paired-pulse paradigm.

RESULTS

In typical absence seizures, we observed an increase in synchronization between hippocampal recordings when spike-and-wave discharges occurred in the cortex and thalamus. This indicates that seizure activity in the thalamocortical circuitry enhances the propensity of limbic areas to synchronize, but is not sufficient to drive hippocampal circuitry into a full paroxysmal discharge. Lower paired-pulse depression was then found in hippocampus of rats that displayed atypical absence seizures.

CONCLUSIONS

These observations suggest that circuitries in brain areas that do not display apparent seizure activity become synchronized as seizures occur within thalamocortical circuitry, and that a weakened hippocampal inhibition may predispose to develop synchronization into full paroxysms during atypical absence seizures.

Sodium oxybate: a review of its use in the management of narcolepsy

Sodium oxybate (Xyrem) is the sodium salt of the CNS depressant gamma-hydroxybutyric acid (GHB) and is therefore subject to prescription restrictions. It is approved in the US for the treatment of cataplexy and excessive daytime sleepiness (EDS) in patients with narcolepsy, and in the EU for the treatment of narcolepsy with cataplexy. Sodium oxybate is generally well tolerated and effective in the treatment of symptoms of narcolepsy with cataplexy. While its short half-life necessitates twice-nightly administration, it is highly effective in reducing the frequency of cataplexy, improving sleep architecture and reducing EDS in patients with narcolepsy. Sodium oxybate therefore offers a valuable alternative or addition to the use of TCAs, SSRIs and stimulants in the treatment of the symptoms of narcolepsy including cataplexy and EDS.

An interactive lesson in acid/base and pro-drug chemistry using sodium gamma-hydroxybutyrate and commercial test coasters

OBJECTIVE

To develop a classroom activity that applied pertinent pharmaceutical concepts to examine the use and limitations of a commercially available test drink coaster in detecting the presence of a date-rape drug, sodium gamma-hydroxybutyrate (NaGHB), in beverages.

DESIGN

An activity exercise involving a combination of self-study, hands on participation, and classroom discussion was developed. Topics incorporated into the activity were drug-assisted rape, the concepts of false positives and negatives, and prodrug and pH chemistry.

ASSESSMENT

Based on questionnaires completed by the students, the intended concepts were reinforced and students demonstrated an increased awareness of the potential shortcomings of the commercial test devices. The activity was well received by the majority of students.

CONCLUSION

The developed activity stimulated student awareness and interest in several principles relevant in pharmaceutical education, including drug-assisted rape, consumer-based drug testing of NaGHB, and the chemical basis for its limitations. The activity requires no special equipment other than the drink coasters and can be easily completed in one 2-hour classroom session.

Experiences of gamma hydroxybutyrate (GHB) ingestion: a focus group study

GHB (gamma hydroxybutyrate) is a significant new drug of abuse added to the United States Controlled Substance Act in 2000. The majority of the published literature on GHB consists of clinical case reports, mainly from emergency departments, and a collection of laboratory-based studies, focused mainly on anesthesia. While comments about the various experiences and behaviors of human users are often included in such studies or reports, these aspects of GHB are only just beginning to be systematically investigated or detailed. Reported here are data from a qualitative study using focus group methods on the consumption habits, experiences, and beliefs of GHB users. A total of 51 people, 30 men and 21 women, mean age of 31.1+/-7.6 years (range 18 to 52 years), who report having used GHB for an average of 4.3+/-2.5 years (range one to 11 years), were interviewed in 10 separate groups held in 2004. This article discusses broadly the general experience of the GHB high, major perceived benefits including sexual responses to the drug, perceived risks and dangers of ingestion, co-ingestion, and various contexts of use. It concludes with a discussion of the implications drawn from this information for clinicians treating patients who use GHB.

Designing a gamma hydroxybutyrate (GHB) structured telephone-administered survey instrument

INTRODUCTION

As part of a larger study assessing the covariates and outcomes of GHB use, we developed a telephone-survey instrument for hospitalized GHB exposed patients identified through poison control center surveillance and for self-identified GHB users recruited from the general public.

METHODS

We used an iterative review process with an interdisciplinary team, including pharmacists, a physician, and a medical anthropologist. In designing the structured, telephone-survey instrument, we prioritized inclusion of validated, drug-specific, and generic questionnaire batteries or individual items related to GHB or to other drugs of abuse. Only one published survey instrument specific to GHB use was identified, which we extensively expanded and modified. We also developed a number of GHB-specific items new to this survey. Finally, we included items from the National Survey on Drug Use & Health, CAGE questionnaire items on alcohol abuse, the SF-12 instrument, and selected National Health Interview items.

RESULTS

The final questionnaire consisted of 272 content items, the majority of which required simple yes or no responses. The bulk of the items (74%) were GHB-specific. The questionnaire was easily administered using computer-assisted telephone interview (CATI) software. A total of 131 interviews were administered with a mean administration time of 33+/-10 minutes. The instrument can also be used in other interview formats.

CONCLUSION

Developing a successful questionnaire calls for a multidisciplinary and systematic process. Structured, telephone administered surveys are particularly suited to expand and explore the basic information obtained by poison centers for case management.

Differential regulation of the tyrosine hydroxylase and enkephalin neuropeptide transmitter genes in rat PC12 cells by short chain fatty acids: Concentration-dependent effects on transcription and RNA stability

At physiologic concentrations, butyrate regulates the expression of individual genes involving at least three mechanisms: (i) through induction of cis- and trans-acting butyrate-dependent transcription factors for selected genes, (ii) by inhibition of histone deacetylation and attendant chromatin remodeling and (iii) by affecting turnover of mRNAs. Our previous work illustrated gradual accumulation of mRNA for tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis and the neuropeptide transmitter proenkephalin (ppEnk) in butyrate-differentiated PC12 cells (Nankova, B.B., Chua, J., Mishra, R., Kobasiuk, C.D., La Gamma, E.F. 2003. Nicotinic induction of preproenkephalin and tyrosine hydroxylase gene expression in butyrate-differentiated rat PC12 cells: a model for adaptation to gut-derived environmental signals. Pediatr. Res. 53, 113-118.). However, at higher physiological concentrations (6 mM), TH mRNA levels are significantly reduced while ppEnk mRNA transcripts remained elevated. These differential effects suggest suppression of endogenous TH gene transcription, targeted degradation of TH mRNA or both. By using nuclear run-on assays, we found that transcription increased for both endogenous TH and ppEnk genes, even at time points and concentrations when reduced steady-state levels of TH mRNA were observed. The reduction in TH mRNA was blocked by cycloheximide consistent with a protein-dependent mechanism. We also observed a dose-dependent accumulation of luciferase reporter molecules driven by TH promoter in transient transfection experiments, data that provide additional support for separate regulatory pathways. Significantly, butyrate-dependent decreases in TH mRNA were also reflected in a reduction in TH protein. Our results suggest a novel mode of regulation for TH by butyrate operating via both transcriptional and post-transcriptional mechanisms. We speculate that, depending on plasma concentrations of butyrate, this naturally occurring signaling molecule can function as an in vivo molecular switch to alter levels of TH mRNA, its protein and thus the biosynthesis of endogenous catecholamines.

The mechanistic classification of addictive drugs

The authors review recent research on the molecular mechanisms of addiction and propose a new classification for addictive drugs.

Low-carb diets, fasting and euphoria: Is there a link between ketosis and gamma-hydroxybutyrate (GHB)?

Anecdotal evidence links the initial phase of fasting or a low-carbohydrate diet with feelings of well-being and mild euphoria. These feelings have often been attributed to ketosis, the production of ketone bodies which can replace glucose as an energy source for the brain. One of these ketone bodies, beta-hydroxybutyrate (BHB), is an isomer of the notorious drug of abuse, GHB (gamma-hydroxybutyrate). GHB is also of interest in relation to its potential as a treatment for alcohol and opiate dependence and narcolepsy-associated cataplexy. Here I hypothesize that, the mild euphoria often noted with fasting or low-carbohydrate diets may be due to shared actions of BHB and GHB on the brain. Specifically, I propose that BHB, like GHB, induces mild euphoria by being a weak partial agonist for GABA(B) receptors. I outline several approaches that would test the hypothesis, including receptor binding studies in cultured cells, perception studies in trained rodents, and psychometric testing and functional magnetic resonance imaging in humans. These and other studies investigating whether BHB and GHB share common effects on brain chemistry and mood are timely and warranted, especially when considering their structural similarities and the popularity of ketogenic diets and GHB as a drug of abuse.

[Agitation and gamma-hydroxybutyrate]

Agitation is a symptom in various disorders. Gamma-hydroxybutyrate (GHB) is often abused because of its stimulating effects. Side effects comprise loss of consciousness, coma, and agitated states. We present a 50-year-old patient with repeated GHB intoxications and abstinent alcohol dependency and a video document showing an agitated state. Diagnostic workup is discussed considering the relevant literature on this topic. Intoxication and dependence on GHB are important entities in the contexts of neurology and psychiatry.

Gamma-hydroxybutyrate--a drug of abuse

Gamma-hydroxybutyrate (GHB) is a drug of abuse that causes euphoria, anxiolysis, and hypnosis. The recent rise in the recreational intake of GHB, as well as its association with 'drug rape', has turned the attention to GHB in acute hospital settings. Acutely admitted GHB intoxicated patients may display various levels of sedation or coma, but may also show paradoxical agitation, combativeness, or self-injurious behaviors. The symptoms can be nonspecific and the definite diagnosis therefore normally relies on the detection of GHB in blood or body fluids, which is an analysis that may not be promptly available. As a basis for understanding the clinical features of GHB intoxication and abuse, we here review the pharmacological and neurophysiological knowledge about GHB, which stems from decades of clinical and basic GHB research. In addition, we discuss the latest discoveries in the quest for distinct GHB receptors in the brain, and their possible implications for future therapies of GHB abuse.

Club Drugs and HIV Infection: A Review

Club drug use is common among populations with human immunodeficiency virus (HIV) and populations at high risk for HIV infection. Club drugs have a myriad of acute and chronic medical consequences. Club drug-related visits to the emergency department and admissions for treatment of substance use have increased dramatically over the past 15 years. Most epidemiological data support the role of club drugs in increasing sexual risk behavior, with some studies demonstrating an independent association between use of certain club drugs and HIV infection. The direct influence of club drugs on progression of HIV disease remains to be determined; however, club drugs may interact with certain retroviral medications and have been associated with decreased adherence to medication. Clinicians should ask all patients about patterns of club drug use, counsel patients about the risks associated with club drug use, and refer patients to appropriate behavioral treatment programs for substance use when clinically indicated.

D-2-hydroxyglutaric aciduria in three patients with proven SSADH deficiency: genetic coincidence or a related biochemical epiphenomenon?

Succinic semialdehyde dehydrogenase (SSADH) deficiency and D-2-hydroxyglutaric aciduria (D-2-HGA) are rare inborn errors of metabolism primarily revealed by urinary organic acid screening. Three patients with proven SSADH deficiency excreted, in addition to GHB considerable amounts of D-2-HG. We examined whether these patients suffered from two inborn errors of metabolism by measuring D-2-HG concentrations in the culture medium of cells from these patients. In addition, mutation analysis of the D-2-hydroxyglutarate dehydrogenase gene was performed. Normal concentrations of D-2-HG were measured in the culture media of fibroblasts or lymphoblasts derived from the three patients. In one patient, we found a heterozygous likely pathogenic mutation in the D-2-hydroxyglutarate dehydrogenase gene. These combined results argue against the hypothesis that the patients are affected with "primary" D-2-HGA in combination with their SSADH deficiency. Moderately increased levels of D-2-HG were also found in urine, plasma, and cerebrospinal fluid samples derived from 12 other patients with SSADH deficiency, revealing that D-2-HG is a common metabolite in this disease. The increase of D-2-HG in SSADH deficiency can be explained by the action of hydroxyacid-oxoacid transhydrogenase, a reversible enzyme that oxidases GHB in the presence of 2-ketoglutarate yielding SSA and D-2-HG.

GABA(B) receptor-mediated modulation of hypocretin/orexin neurones in mouse hypothalamus

Hypocretin/orexin (Hcrt) is a critical neurotransmitter for the maintenance of wakefulness and has been implicated in several other functions, including energy metabolism and reward. Using whole-cell patch-clamp recordings from transgenic mice in which enhanced green fluorescent protein was linked to the Hcrt promoter, we investigated GABAergic control of the Hcrt neurones in hypothalamic slices. Bath application of GABA or muscimol caused an early hyperpolarization mediated by Cl(-) and a late depolarization mediated by the efflux of bicarbonate. These GABA(A) receptor-mediated responses were blocked by picrotoxin and bicuculline. Under the GABA(A) blockade condition, GABA produced consistent hyperpolarization, decreased firing rate and input resistance. The selective GABA(B) agonist (R)-baclofen caused a similar response with an EC(50) of 7.1 mum. The effects of (R)-baclofen were blocked by the GABA(B) antagonist CGP 52432 but persisted in the presence of tetrodotoxin, suggesting direct postsynaptic effects. The existence of GABA(B) modulation was supported by GABA(B(1)) subunit immunoreactivity on Hcrt cells colabelled with antisera to the Hcrt-2 peptide. Furthermore, GABA(B) receptor activation inhibited the presynaptic release of both glutamate and GABA. (R)-Baclofen depressed the amplitude of evoked excitatory postsynaptic currents (EPSCs) and inhibitory synaptic currents (IPSCs), and also decreased the frequency of both spontaneous and miniature EPSCs and IPSCs with a modest effect on their amplitudes. These data suggest that GABA(B) receptors modulate Hcrt neuronal activity via both pre- and postsynaptic mechanisms, which may underlie the promotion of non-rapid eye movement sleep and have implications for the use of GABA(B) agonists in the treatment of substance addiction through direct interaction with the Hcrt system.

Resuscitative Treatments on 1,4-Butanediol Mortality in Mice

STUDY OBJECTIVE

Recent reports on fatalities associated with overdoses from 1,4-butanediol (1,4-BD), a precursor of the drug of abuse gamma-hydroxybutyric acid (GHB), pose the need for investigations focusing on possible pharmacologic remedies. Accordingly, the present study investigates whether 4-methylpyrazole (4-MP; also termed fomepizole and Antizol), an inhibitor of alcohol dehydrogenase (the enzyme involved in the first step of the conversion of 1,4-BD into GHB), and the gamma-aminobutyric acid B (GABAB) receptor antagonist (2S)(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), provides protection against 1,4-BD-induced mortality in CD1 mice.

METHODS

Two sets of experiments were conducted with mortality as the outcome measure. In all experiments, mice were initially treated with a lethal dose of 1,4-BD (3 g/kg, intragastric [i.g.]). In the first set of experiments (dose-response curves), once mice had displayed clear signs of 1,4-BD intoxication, animals were randomly allocated in separate groups (n=10) and treated acutely with either 4-MP (vehicle, 3, 10, 30, and 100 mg/kg, intraperitoneal [i.p.]) or SCH 50911 (vehicle, 75, 150, and 300 mg/kg, i.p.). Mortality was recorded every hour for the first 9 hours and 12, 18, and 24 hours after 1,4-BD injection. In the second set of experiments (time course), mice were randomly allocated in separate groups (n=10). A single dose of either 4-MP (30 mg/kg, i.p.) or SCH 50911 (150 mg/kg, i.p.) was administered 15, 30, 60, 90, or 120 minutes after administration of 3 g/kg 1,4-BD (i.g.). Again, mortality was recorded every hour for the first 9 hours and 12, 18, and 24 hours after 1,4-BD injection.

RESULTS

In the dose-response experiments, the acute administration of 4-MP and SCH 50911 exerted a dose-dependent resuscitative effect in mice acutely intoxicated by 3 g/kg 1,4-BD. Specifically, 30 and 100 mg/kg 4-MP and 150 mg/kg SCH 50911 protected all treated mice against 1,4-BD-induced mortality. Conversely, all mice treated with 4-MP- and SCH 50911-vehicle died. In the time-course experiments, protection induced by 30 mg/kg 4-MP was complete when administered up to 90 minutes after 1,4-BD injection. Vice versa, the complete protection induced by 150 mg/kg SCH 50911 progressively diminished as the time between 1,4-BD and SCH 50911 administration was increased from 15 to 120 minutes.

CONCLUSION

These results indicate that both 4-MP and SCH 50911 protected against mortality induced by 1,4-BD. Further, these results suggest that 1,4-BD-induced mortality in mice is a result of conversion of 1,4-BD into GHB and GHB-induced activation of the GABAB receptor. Because both 4-MP and GABAB receptor antagonists are available for human use, clinical studies on their ability to reverse the consequences of 1,4-BD and GHB intoxication, including fatal events, might be considered.

γ-Hydroxybutyrate induces cyclic AMP-responsive element-binding protein phosphorylation in mouse hippocampus: An involvement of GABAB receptors and cAMP-dependent protein kinase activation

gamma-Hydroxybutyrate is a widely used recreational drug. Its abuse has been associated with cognitive impairments and development of tolerance and dependence. However, the neural mechanisms underlying these effects remain unclear. In the present study we investigated the possible cellular signaling mechanisms that might mediate gamma-hydroxybutyrate's action. Acute administration of gamma-hydroxybutyrate (500 mg/kg, i.p.) was found to cause a rapid and long-lasting increase in the phosphorylation level of the cAMP-responsive element-binding protein in mouse (C57/BL6) hippocampus. Pretreatment with the specific GABA(B) receptor antagonist [3-[1-(R)-[(3-cyclohexylmethyl)hydroxyphosphinyl]-2-(S)-hydroxy-propyl]amino]ethyl]-benzoic acid (20 mg/kg, i.p.) prevented the action of gamma-hydroxybutyrate, confirming a GABA(B) receptor-mediated mechanism. In addition, acute gamma-hydroxybutyrate administration induced a significant increase in cytosolic cAMP-dependent protein kinase activity in the hippocampus, and pretreatment with the cAMP-dependent protein kinase inhibitor H-89 could prevent the effect of gamma-hydroxybutyrate on cAMP-responsive element-binding protein phosphorylation, indicating a direct involvement of cAMP-dependent protein kinase in gamma-hydroxybutyrate-induced cAMP-responsive element-binding protein phosphorylation. On the other hand, the increased expression of phosphorylated cAMP-responsive element-binding protein was not observed in the hippocampus of mice subjected to repeated gamma-hydroxybutyrate exposure, suggesting the development of a gamma-hydroxybutyrate-induced desensitization of the signaling pathway leading to cAMP-responsive element-binding protein activation. Since cAMP-responsive element-binding protein activation has been implicated in a variety of neural plasticities, our findings may have revealed a new mechanism underlying gamma-hydroxybutyrate-induced neuroadaptations.

Murine succinate semialdehyde dehydrogenase (SSADH) deficiency, a heritable disorder of GABA metabolism with epileptic phenotype

Murine models of inborn errors of metabolism represent an established approach for investigating pathophysiological mechanisms associated with the corresponding human disorder. Our laboratory studies human inherited defects of GABA synthesis and degradation. One of these, succinate semialdehyde dehydrogenase (SSADH) deficiency (or gamma-hydroxybutyric aciduria; OMIM 271980; E.C. 1.2.1.24), has recently been modeled via gene targeting in the mouse. SSADH-/- mice succumb to early lethality in status epilepticus at postnatal (PN) days 20 - 26. Numerous metabolic, neurochemical and neurophysiological abnormalities have been documented using in vitro and in vivo approaches, substantially altering our thoughts about the complexity of the corresponding human condition. Moreover, novel preclinical treatment paradigms have been developed through drug trials in gene-ablated animals. The greatest utility of this animal, however, may reside in its transition from early absence seizures to generalized convulsions and eventual status epilepticus. Accurate neurochemical assessment during this transition may provide clues to the same transition process in patients, for which the underlying mechanisms remain undefined.