Effects of topiramate and other anti-glutamatergic drugs on the acute intoxicating actions of ethanol in mice: modulation by genetic strain and stress

Neuropharmacology of Alcohol Addiction with Special Emphasis on Proteomic Approaches for Identification of Novel Therapeutic Targets

Alcohol is a generic pharmacological agent with only a few recognized primary targets. Nmethyl- D-aspartate, gamma-aminobutyric acid, glycine, 5-hydroxytryptamine 3 (serotonin), nicotinic acetylcholine receptors, and L-type Ca2+ channels and G-protein-activated inwardly rectifying K channels are all involved. Following the first hit of alcohol on specific brain targets, the second wave of indirect effects on various neurotransmitter/neuropeptide systems begins, leading to the typical acute behavioral effects of alcohol, which range from disinhibition to sedation and even hypnosis as alcohol concentrations rise. Recent research has revealed that gene regulation is significantly more complex than previously thought and does not fully explain changes in protein levels. As a result, studying the proteome directly, which differs from the genome/transcriptome in terms of complexity and dynamicity, has provided unique insights into extraordinary advances in proteomic techniques that have changed the way we can analyze the composition, regulation, and function of protein complexes and pathways underlying altered neurobiological conditions. Neuroproteomics has the potential to revolutionize alcohol research by allowing researchers to gain a better knowledge of how alcohol impacts protein structure, function, connections, and networks on a global scale. The amount of information collected from these breakthroughs can aid in identifying valuable biomarkers for early detection and improved prognosis of an alcohol use disorder and future pharmaceutical targets for the treatment of alcoholism.

Antagonism of GluK1-containing kainate receptors reduces ethanol consumption by modulating ethanol reward and withdrawal

Alcohol use disorder (AUD) is a neuropsychiatric condition affecting millions of people worldwide. Topiramate (TPM) is an antiepileptic drug that has been shown to reduce ethanol drinking in humans. However, TPM is associated with a variety of adverse effects due to its interaction with many receptor systems and intracellular pathways. GluK1-containing kainate receptors (GluK1*KARs) are non-selectively inhibited by TPM, and genetic association studies suggest that this receptor system could be targeted to reduce drinking in AUD patients. We examined the efficacy of LY466195, a selective inhibitor of GluK1*KAR, in reducing ethanol consumption in the intermittent two-bottle choice paradigm in mice. The effect of LY466195 on various ethanol-related phenotypes was investigated by quantification of alcohol intake, physical signs of withdrawal, conditioned place preference (CPP) and in vivo microdialysis in the nucleus accumbens. Selective GluK1*KAR inhibition reduced ethanol intake and preference in a dose-dependent manner. LY466195 treatment attenuated the physical manifestations of ethanol withdrawal and influenced the rewarding properties of ethanol. Interestingly, LY466195 injection also normalized changes in dopamine levels in response to acute ethanol in ethanol-dependent mice, but had no effect in ethanol-naïve mice, suggesting ethanol state-dependent effects. The data point to GluK1*KARs as an attractive pharmacological target for the treatment of AUD.

Neurogranin in the nucleus accumbens regulates NMDA receptor tolerance and motivation for ethanol seeking

Dysfunction of N-methyl-d-aspartate receptor (NMDAR) signaling in the nucleus accumbens (NAc) has been implicated in the pathophysiology of alcohol use disorders (AUD). Neurogranin (Ng), a calmodulin-binding protein, is exclusively expressed in the post-synapse, and mediates NMDAR driven synaptic plasticity by regulating the calcium-calmodulin (Ca²⁺-CaM) pathway. To study the functional role of Ng in AUD, we administrated behavior tests including Pavlovian instrument transfer (PIT), operant conditioning, and rotarod test using Ng null mice (Ng^-/- mice). We used adeno-associated virus (AAV)-mediated Ng expression and pharmacological manipulation to validate behavioral responses in Ng^-/- mice. The results from our multidisciplinary approaches demonstrated that deficit of Ng increases tolerance to NMDAR inhibition and elicit faster cue reactivity during PIT without changes in ethanol reward. Operant conditioning results demonstrated that Ng^-/- mice self-administered significantly more ethanol and displayed reduced sensitivity to aversive motivation. We identified that ethanol exposure decreases mGluR5 (metabotropic glutamate receptor 5) expression in the NAc of Ng^-/- mice and pharmacological inhibition of mGluR5 reverses NMDAR desensitization in Ng^-/- mice. Together these findings specifically suggest that accumbal Ng plays an essential role in the counterbalance between NMDAR and mGluR5 signaling; which alters NMDAR resistance, and thereby altering aversive motivation for ethanol and may ultimately contribute to susceptibility for alcohol addiction.

Mouse strain differences in punished ethanol self-administration

Determining the neural factors contributing to compulsive behaviors such as alcohol-use disorders (AUDs) has become a significant focus of current preclinical research. Comparison of phenotypic differences across genetically distinct mouse strains provides one approach to identify molecular and genetic factors contributing to compulsive-like behaviors. Here we examine a rodent assay for punished ethanol self-administration in four widely used inbred strains known to differ on ethanol-related behaviors: C57BL/6J (B6), DBA/2J (D2), 129S1/SvImJ (S1), and BALB/cJ (BALB). Mice were trained in an operant task (FR1) to reliably lever-press for 10% ethanol using a sucrose-fading procedure. Once trained, mice received a punishment session in which lever pressing resulted in alternating ethanol reward and footshock, followed by tests to probe the effects of punishment on ethanol self-administration. Results indicated significant strain differences in training performance and punished attenuation of ethanol self-administration. S1 and BALB showed robust attenuation of ethanol self-administration after punishment, whereas behavior in B6 was attenuated only when the punishment and probe tests were conducted in the same contexts. By contrast, D2 were insensitive to punishment regardless of context, despite receiving more shocks during punishment and exhibiting normal footshock reactivity. Additionally, B6, but not D2, reduced operant self-administration when ethanol was devalued with a bitter tastant. B6 and D2 showed devaluation of sucrose self-administration, and punished suppression of sucrose seeking was context dependent in both the strains. While previous studies have demonstrated avoidance of ethanol in D2, particularly when ethanol is orally available from a bottle, current findings suggest this strain may exhibit heightened compulsive-like self-administration of ethanol, although there are credible alternative explanations for the phenotype of this strain. In sum, these findings offer a foundation for future studies examining the neural and genetic factors underlying AUDs.

Preliminary investigation of 6,7-dihydropyrazolo[1,5-a]pyrazin-4-one derivatives as a novel series of mGlu5 receptor positive allosteric modulators with efficacy in preclinical models of schizophrenia

As part of our efforts to identify a suitable back-up compound to our recently disclosed mGlu5 positive allosteric modulator (PAM) clinical candidate VU0490551/JNJ-46778212, this letter details the investigation and challenges of a novel series of 6,7-dihydropyrazolo[1,5-a]pyrazin-4-one derivatives. From these efforts, compound 4k emerged as a potent and selective mGlu5 PAM displaying overall attractive in vitro (pharmacological and ADMET) and PK profiles combined with in vivo efficacy in preclinical models of schizophrenia. However, further advancement of the compound was precluded due to severely limiting CNS-related side-effects confirming the previously reported association between excessive mGlu5 activation and target-related toxicities.

The effects of single nucleotide polymorphisms in glutamatergic neurotransmission genes on neural response to alcohol cues and craving

The aim of the current study was to determine genotype effects of four single nucleotide polymorphisms (SNPs) in the genes of the N-Methyl-d-aspartate receptor (GRIN1, GRIN2A, GRIN2C) and kainate receptor (GRIK1), which have been previously associated with alcoholism, on behavior, neural cue-reactivity and drinking outcome. Eighty-six abstinent alcohol dependent patients were recruited from an in-patient setting. Neuropsychological tests, genotyping and functional magnetic resonance imaging (fMRI) were used to study genotype effects. GRIN2C risk allele carriers displayed increased alcohol cue-induced activation in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC). Neural activation in the ACC positively correlated with craving for alcohol (r = 0.201, P = 0.032), whereas activation in the dlPFC showed a negative association (r = -0.215, P = 0.023). In addition, dlPFC activation predicted time to first relapse (HR = 2.701, 95%CI 1.244-5.864, P = 0.012). GRIK1 risk allele carriers showed increased cue-induced activation in the medial prefrontal (PFC) and orbitofrontal cortex (OFC) and in the lateral PFC and OFC. Activation in both clusters positively correlated with alcohol craving (rmedOFC, medPFC  = 0.403, P = 0.001, rlatOFC, latPFC  = 0.282, P = 0.008), and activation in the cluster that encompassed the medial OFC predicted time to first relapse (HR = 1.911, 95%CI 1.030-3.545, P = 0.040). Findings indicate that SNPs in the GRIN2C and GRIK1 genes are associated with altered cue-induced brain activation that is related to craving for alcohol and relapse risk.

Tolerance to ethanol intoxication after chronic ethanol: role of GluN2A and PSD-95

The neural and genetic factors underlying chronic tolerance to alcohol are currently unclear. The GluN2A N-methyl-D-aspartate receptors (NMDAR) subunit and the NMDAR-anchoring protein PSD-95 mediate acute alcohol intoxication and represent putative mechanisms mediating tolerance. We found that chronic intermittent ethanol exposure (CIE) did not produce tolerance [loss of righting reflex (LORR)] or withdrawal-anxiety in C57BL/6J, GluN2A or PSD-95 knockout mice assayed 2-3 days later. However, significant tolerance to LORR was evident 1 day after CIE in C57BL/6J and PSD-95 knockouts, but absent in GluN2A knockouts. These data suggest a role for GluN2A in tolerance, extending evidence that human GluN2A gene variation is involved in alcohol dependence.

Glutamatergic mechanisms associated with stress-induced amygdala excitability and anxiety-related behavior

The neural factors underlying individual differences in susceptibility to chronic stress remain poorly understood. Preclinical studies demonstrate that mouse strains vary greatly in anxiety-related responses to chronic stress in a manner paralleled by differential stress-induced changes in glutamatergic signaling in the basolateral amygdala (BLA). Previous work has also shown that alterations in the amygdala gene expression of the GluN1 NMDA and the GluK1 kainate receptors are associated with stress-induced alterations in anxiety-like behavior in the C57BL/6J mouse strain. Using in vivo behavioral pharmacological and ex vivo physiological approaches, the aim of the current study was to further elucidate changes in glutamate neurotransmission in the BLA caused by stress and to test the functional roles of GluN1 and GluK1 in mediating stress-related changes in behavior. Results showed that stress-induced alterations in anxiety-like behavior (light/dark exploration test) were absent following bilateral infusion of the GluK1 agonist ATPA into the BLA. Intra-BLA infusion of the competitive NMDA antagonist AP5 produced a generalized behavioral disinhibition/locomotor hyperactivity, irrespective of stress. Slice electrophysiological recordings showed that ATPA augmented BLA GABAergic neurotransmission and that stress increased the amplitude of network-dependent spontaneous excitatory postsynaptic currents and amplitude of GABAergic miniature inhibitory postsynaptic currents in BLA. These findings could indicate stress-induced BLA glutamatergic neuronal network hyperexcitability and a compensatory increase in GABAergic neurotransmission, suggesting that GluK1 agonism augmented GABAergic inhibition to prevent behavioral sequelae of stress. Current data could have implications for developing novel therapeutic approaches, including GluK1 agonists, for stress-related anxiety disorders.

Amantadine and cognitive flexibility: decision making in Parkinson's patients with severe pathological gambling and other impulse control disorders

INTRODUCTION

Dopamine replacement therapy for Parkinson's disease (PD) was recently linked to the development of impulse control disorders such as pathological gambling (PG), hypersexuality, compulsive shopping, and binge or compulsive eating. Antiglutamatergic agents including amantadine (Ama) reduce these behaviors in PD and non-PD patients. The aim of our study is to evaluate the changes in executive functions, emotions, and reward/loss processing during Ama treatment in PD patients.

METHODS

Thirty-three patients affected by idiopathic PD were selected from a cohort of 1,096 PD patients and categorized in three different groups: ten affected by PG (PD-PG); nine PD patients with other impulse control disorder (PD-ICD); and 14 PD patient without any psychiatric disorder (PD-CTR-controls). For the neuropsychological evaluation, the following behavioral tasks where administered: the Stroop, the emotional Stroop, and the monetary reward/loss risk-taking tasks.

RESULTS

During Ama treatment, PD-PGs showed a decrease in risky choices and an increase in non-risky choices (t(9)=-2.40, P<0.05 and t(9)=2,67, P<0.05 uncorrected, respectively). Between-group comparison showed a significant decrease in risky choices for PD-PG with respect to PD-CTR (t(22)=-4.16, P<0.01), and a decreased accuracy for positive words in comparison between PD-PG and PD-ICD (t(17)=-7,49, P<0.01) and PD-PG and PD-CTR (t(22)=-4.29, P<0.01). No within- and between-group differences were observed for Stroop task.

DISCUSSION

Our data showed that Ama add-on therapy reduces hypersensitivity to reward and sustains activation toward uncertainty in PD-PG patients. These finding might explain the behavioral mechanism underlying the effect of antiglutamatergic drugs.

Glutamatergic targets for new alcohol medications

RATIONALE

An increasingly compelling literature points to a major role for the glutamate system in mediating the effects of alcohol on behavior and the pathophysiology of alcoholism. Preclinical studies indicate that glutamate signaling mediates certain aspects of ethanol's intoxicating and rewarding effects, and undergoes adaptations following chronic alcohol exposure that may contribute to the withdrawal, craving and compulsive drug-seeking that drive alcohol abuse and alcoholism.

OBJECTIVES

We discuss the potential for targeting the glutamate system as a novel pharmacotherapeutic approach to treating alcohol use disorders, focusing on five major components of the glutamate system: the N-methyl-D-aspartate (NMDA) receptor and specific NMDA subunits, the glycineB site on the NMDA receptors (NMDAR), L-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid ionotropic (AMPA) and kainate (KAR) receptors, metabotropic receptors (mGluR), and glutamate transporters.

RESULTS

Chronic alcohol abuse produces a hyperglutamatergic state, characterized by elevated extracellular glutamate and altered glutamate receptors and transporters. Pharmacologically manipulating glutamatergic neurotransmission alters alcohol-related behaviors including intoxication, withdrawal, and alcohol-seeking, in rodents and human subjects. Blocking NMDA and AMPA receptors reduces alcohol consumption in rodents, but side-effects may limit this as a therapeutic approach. Selectively targeting NMDA and AMPA receptor subunits (e.g., GluN2B, GluA3), or the NMDAR glycineB site offers an alternative approach. Blocking mGluR5 potently affects various alcohol-related behaviors in rodents, and mGluR2/3 agonism also suppresses alcohol consumption. Finally, glutamate transporter upregulation may mitigate behavioral and neurotoxic sequelae of excess glutamate caused by alcohol.

CONCLUSIONS

Despite the many challenges that remain, targeting the glutamate system offers genuine promise for developing new treatments for alcoholism.

Probing the modulation of acute ethanol intoxication by pharmacological manipulation of the NMDAR glycine co-agonist site

BACKGROUND

Stimulating the glycine(B) binding site on the N-methyl-d-aspartate ionotropic glutamate receptor (NMDAR) has been proposed as a novel mechanism for modulating behavioral effects of ethanol (EtOH) that are mediated via the NMDAR, including acute intoxication. Here, we pharmacologically interrogated this hypothesis in mice.

METHODS

Effects of systemic injection of the glycine(B) agonist, d-serine, the GlyT-1 glycine transporter inhibitor, ALX-5407, and the glycine(B) antagonist, L-701,324, were tested for the effects on EtOH-induced ataxia, hypothermia, and loss of righting reflex (LORR) duration in C57BL/6J (B6) and 129S1/SvImJ (S1) inbred mice. Effects of the glycine(B) partial agonist, d-cycloserine (DCS), the GlyT-1 inhibitor, N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine (NFPS), and the glycine(B) antagonist, 5,7-dichlorokynurenic (DCKA), on EtOH-induced LORR duration were also tested. Interaction effects on EtOH-induced LORR duration were examined via combined treatment with d-serine and ALX-5407, d-serine and MK-801, d-serine and L-701,324, as well as L-701,324 and ALX-5407, in B6 mice, and d-serine in GluN2A and PSD-95 knockout mice. The effect of dietary depletion of magnesium (Mg), an element that interacts with the glycine(B) site, was also tested.

RESULTS

Neither d-serine, DCS, ALX-5407, nor NFPS significantly affected EtOH intoxication on any of the measures or strains studied. L-701,324, but not DCKA, dose-dependently potentiated the ataxia-inducing effects of EtOH and increased EtOH-induced (but not pentobarbital-induced) LORR duration. d-serine did not have interactive effects on EtOH-induced LORR duration when combined with ALX-5407. The EtOH-potentiating effects of L-701,324, but not MK-801, on LORR duration were prevented by d-serine, but not ALX-5407. Mg depletion potentiated LORR duration in B6 mice and was lethal in a large proportion of S1 mice.

CONCLUSIONS

Glycine(B) site activation failed to produce the hypothesized reduction in EtOH intoxication across a range of measures and genetic strains, but blockade of the glycine(B) site potentiated EtOH intoxication. These data suggest endogenous activity at the glycine(B) opposes EtOH intoxication, but it may be difficult to pharmacologically augment this action, at least in nondependent subjects, perhaps because of physiological saturation of the glycine(B) site.

The use of a novel drinkometer system for assessing pharmacological treatment effects on ethanol consumption in rats

BACKGROUND

There are numerous studies in the preclinical alcohol research field showing that pharmacological interventions and many other manipulations can influence ethanol (EtOH) consumption in a free-choice paradigm in rats. Most of these studies are based on 24-hour measurements. These studies provide a measure of the total amount of EtOH consumed per day, but do not provide information on the drinking patterns within this period of measurement. Here, we used a novel drinkometer system in combination with Fourier analysis to provide detailed information on drinking patterns.

METHODS

Our automated drinkometer system measures fluid consumption by means of high-precision sensors attached to the drinking bottles in the home cage of the rat and thereby ameliorates several limitations of a classical lickometer-based drinkometer system. As an example of its application, we used the alcohol deprivation effect (ADE) model for relapse-like drinking and tested as a reference compound lamotrigine, which has a robust effect on the ADE. Fourier analysis was chosen as the main strategy for 24-hour drinking pattern recognition during water/EtOH drinking.

RESULTS

Under baseline conditions, voluntary EtOH consumption in rats can be expressed as characteristic oscillations that follow diurnal activity and differ in their amplitude, depending on the EtOH concentration. This diurnal drinking rhythmicity was altered during a relapse condition. Furthermore, lamotrigine given during the ADE did not significantly affect the drinking frequency or the number of approaches to the EtOH bottles when compared to vehicle-treated animals. However, EtOH intake during a drinking approach was dramatically reduced.

CONCLUSIONS

The use of the drinkometer system and mathematical modeling allows the characterization of treatment effects on relapse-like drinking with a great level of detail. One use of such detailed information may lie in its translational predictability. For instance, owing to lamotrigine treatment's lack of effect on EtOH drinking frequency or the number of approaches to the EtOH bottles, this compound might not be effective in relapse prevention per se but may reduce hedonic EtOH effects and could therefore be used in alcohol-dependent patients if harm reduction is the primary goal of treatment.

Quantitative trait loci for sensitivity to ethanol intoxication in a C57BL/6J×129S1/SvImJ inbred mouse cross

Individual variation in sensitivity to acute ethanol (EtOH) challenge is associated with alcohol drinking and is a predictor of alcohol abuse. Previous studies have shown that the C57BL/6J (B6) and 129S1/SvImJ (S1) inbred mouse strains differ in responses on certain measures of acute EtOH intoxication. To gain insight into genetic factors contributing to these differences, we performed quantitative trait locus (QTL) analysis of measures of EtOH-induced ataxia (accelerating rotarod), hypothermia, and loss of righting reflex (LORR) duration in a B6 × S1 F2 population. We confirmed that S1 showed greater EtOH-induced hypothermia (specifically at a high dose) and longer LORR compared to B6. QTL analysis revealed several additive and interacting loci for various phenotypes, as well as examples of genotype interactions with sex. QTLs for different EtOH phenotypes were largely non-overlapping, suggesting separable genetic influences on these behaviors. The most compelling main-effect QTLs were for hypothermia on chromosome 16 and for LORR on chromosomes 4 and 6. Several QTLs overlapped with loci repeatedly linked to EtOH drinking in previous mouse studies. The architecture of the traits we examined was complex but clearly amenable to dissection in future studies. Using integrative genomics strategies, plausible functional and positional candidates may be found. Uncovering candidate genes associated with variation in these phenotypes in this population could ultimately shed light on genetic factors underlying sensitivity to EtOH intoxication and risk for alcoholism in humans.

A novel role for PSD-95 in mediating ethanol intoxication, drinking and place preference

The synaptic signaling mechanisms mediating the behavioral effects of ethanol (EtOH) remain poorly understood. Post-synaptic density 95 (PSD-95, SAP-90, Dlg4) is a key orchestrator of N-methyl-D-aspartate receptors (NMDAR) and glutamatergic synapses, which are known to be major sites of EtOH's behavioral actions. However, the potential contribution of PSD-95 to EtOH-related behaviors has not been established. Here, we evaluated knockout (KO) mice lacking PSD-95 for multiple measures of sensitivity to the acute intoxicating effects of EtOH (ataxia, hypothermia, sedation/hypnosis), EtOH drinking under conditions of free access and following deprivation, acquisition and long-term retention of EtOH conditioned place preference (CPP) (and lithium chloride-induced conditioned taste aversion), and intoxication-potentiating responses to NMDAR antagonism. PSD-95 KO exhibited increased sensitivity to the sedative/hypnotic, but not ataxic or hypothermic, effects of acute EtOH relative to wild-type controls (WT). PSD-95 KO consumed less EtOH than WT, particularly at higher EtOH concentrations, although increases in KO drinking could be induced by concentration-fading and deprivation. PSD-95 KO showed normal EtOH CPP 1 day after conditioning, but showed significant aversion 2 weeks later. Lithium chloride-induced taste aversion was impaired in PSD-95 KO at both time points. Finally, the EtOH-potentiating effects of the NMDAR antagonist MK-801 were intact in PSD-95 KO at the dose tested. These data reveal a major, novel role for PSD-95 in mediating EtOH behaviors, and add to growing evidence that PSD-95 is a key mediator of the effects of multiple abused drugs.

Reward-related behavioral paradigms for addiction research in the mouse: performance of common inbred strains

The mouse has emerged as a uniquely valuable species for studying the molecular and genetic basis of complex behaviors and modeling neuropsychiatric disease states. While valid and reliable preclinical assays for reward-related behaviors are critical to understanding addiction-related processes, and various behavioral procedures have been developed and characterized in rats and primates, there have been relatively few studies using operant-based addiction-relevant behavioral paradigms in the mouse. Here we describe the performance of the C57BL/6J inbred mouse strain on three major reward-related paradigms, and replicate the same procedures in two other commonly used inbred strains (DBA/2J, BALB/cJ). We examined Pavlovian-instrumental transfer (PIT) by measuring the ability of an auditory cue associated with food reward to promote an instrumental (lever press) response. In a separate experiment, we assessed the acquisition and extinction of a simple stimulus-reward instrumental behavior on a touchscreen-based task. Reinstatement of this behavior was then examined following either continuous exposure to cues (conditioned reinforcers, CRs) associated with reward, brief reward and CR exposure, or brief reward exposure followed by continuous CR exposure. The third paradigm examined sensitivity of an instrumental (lever press) response to devaluation of food reward (a probe for outcome insensitive, habitual behavior) by repeated pairing with malaise. Results showed that C57BL/6J mice displayed robust PIT, as well as clear extinction and reinstatement, but were insensitive to reinforcer devaluation. DBA/2J mice showed good PIT and (rewarded) reinstatement, but were slow to extinguish and did not show reinforcer devaluation or significant CR-reinstatement. BALB/cJ mice also displayed good PIT, extinction and reinstatement, and retained instrumental responding following devaluation, but, unlike the other strains, demonstrated reduced Pavlovian approach behavior (food magazine head entries). Overall, these assays provide robust paradigms for future studies using the mouse to elucidate the neural, molecular and genetic factors underpinning reward-related behaviors relevant to addiction research.

Effect of topiramate treatment on ethanol consumption in rats

RATIONALE

Results from clinical studies have shown that topiramate effectively reduces alcohol consumption in a population of heavy-drinking alcohol-dependent humans.

OBJECTIVES

We undertook this preclinical study in order to establish topiramate's efficacy in a rodent model and to determine whether topiramate's efficacy may vary with level of drinking and/or genetic background.

METHODS

The effects of acutely administered topiramate (0, 5, and 10 mg/kg) on ethanol consumption were examined in a large group of ethanol-preferring (P) rats (N = 20) in order to assess the relationship between level of consumption and treatment effect using a two-bottle free-choice paradigm (10% ethanol versus water). We also evaluated the effects of topiramate in two groups of Wistar rats that were given access to ethanol under either the standard two-bottle free-choice paradigm or under conditions that are known to produce higher levels of daily ethanol consumption (i.e. three-bottle free choice).

RESULTS

Topiramate treatment produced a modest, but persistent (average of 5 days), reduction in ethanol consumption in P rats, and this effect did not vary with level of consumption. Topiramate did not affect ethanol consumption in either group of Wistar rats.

CONCLUSIONS

The results from this study establish in a rodent model that topiramate effectively and persistently reduces ethanol consumption and suggests that its efficacy may depend on genetic vulnerability but not level of drinking.

Young Investigator Award symposium

This article highlights the research presented at the inaugural meeting of Alcoholism and Stress: A Framework for future Treatment Strategies. This meeting was held on May 6-8, 2008 in Volterra, Italy. It is an international meeting dedicated to developing preventive strategies and pharmacotherapeutic remedies for stress- and alcohol-related disorders. For the first time, the National Institute on Alcohol Abuse and Alcoholism (NIAAA) conferred a Young Investigator Award to promote the work of young researchers and highlight their outstanding achievements in the fields of addiction medicine and stress disorders. The awardees were Dr. Katie Witkiewitz (University of Washington), Dr. Andrew Holmes (NIAAA), Dr. Lara A. Ray (Brown University), Dr. James Murphy (University of Memphis), and Dr. Heather Richardson (The Scripps Research Institute). The symposium was chaired by Drs. Fulton Crews and Antonio Noronha.