Biology subjects

Barkley-Levenson, A. M.

Publications and source records attributed to Barkley-Levenson, A. M..

7 recordsLinked to original sources

bioRxiv2026

Functional validation and characterization of Slc39a8 genotype effects on ethanol consumption and related phenotypes

Alcohol use disorders are heritable, and large-scale genome-wide association studies have recently identified novel genetic loci that are correlated with alcohol consumption and problematic alcohol use. One such gene is Slc39a8, which encodes the ion transporter ZIP8, responsible for cellular import of zinc and other metals. Slc39a8 is highly pleiotropic, and a common missense variant has been associated with decreased problematic alcohol use. Here, we used Slc39a8 heterozygous (HET) knockout mice and their wild type (WT) littermates to characterize the effects of reduced gene function on two models of voluntary alcohol consumption (drinking in the dark and intermittent access two-bottle choice), and anxiety- and depression-like behavior. We found that HET mice consumed less alcohol than WT in the intermittent access two-bottle choice procedure. No evidence was found for genotypic differences in baseline locomotor activity, anxiety-like, or depression-like behavior in the open field and forced swim tests. Slc39a8 mRNA expression and alcohol metabolism experiments confirmed decreased brain expression of Slc39a8 in HET mice and unchanged alcohol metabolism. Basal and post-alcohol measurement of zinc levels showed that HET mice after ethanol exposure had lower zinc concentrations in the liver and higher concentrations in blood than WT animals. Analysis of the spatial distribution of multiple trace metals in the brains of naive Slc39a8 HET and WT mice using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) showed region-specific genotypic differences in levels of zinc and iron. These results provide evidence for a direct role of Slc39a8 in ethanol consummatory behavior that does not appear to be due to metabolism, affective state, or locomotor activity. Moreover, we confirm that this animal model shows tissue- and brain region-specific alterations in zinc levels, highlighting potential mechanisms for future study.

neuroscience↗

bioRxiv2025

Dpp6 Homozygous Knockout Mice Exhibit Increased Ethanol Conditioned Place Preference and Acute Ethanol-Induced Anxiolytic Behavior

The gene DPP6 has been associated with behavioral phenotypes of alcohol use disorder (AUD) in recent human genome wide association studies. DPP6 encodes an auxiliary subunit that modulates A-type voltage-gated potassium channels, particularly Kv4.2. To further assess the role of this gene in ethanol-related traits, we tested Dpp6 knockout (KO) mice for ethanol conditioned place preference (CPP), locomotor activity, and ethanol-induced anxiolysis. Male homozygous KO mice (HOM) showed greater preference for the ethanol-paired context compared to wild type littermates (WT) and heterozygous KO mice (HET), while female mice showed no genotypic difference. HOM of both sexes exhibited greater novelty-induced hyperactivity in the CPP apparatus than HET and WT mice in the first two minutes. In a separate experiment, HOM mice showed enhanced locomotor activity following a 1.5 g/kg ethanol injection; however, they also displayed greater locomotor activity during habituation, suggesting basal locomotor differences. Following 1.5 and 2 g/kg injections, HOM mice exhibited EtOH-induced anxiolysis in the first 5 minutes, while the HET and WT mice did not. Lastly, HOM mice displayed a significant sedative response compared to WT animals following a 2 g/kg injection of ethanol. Ultimately, these findings validate a role for Dpp6 in modulating ethanols rewarding, anxiolytic, and sedative effects in a sex-dependent manner.

neuroscience↗

bioRxiv2025

Effects of binge-like ethanol drinking on nest building behavior in mice

Nest building is a natural behavior that can readily be analyzed in mice in the home cage environment. Nest building is involved in thermoregulation, positive motivational states, and motor function, and alterations in this behavior have been proposed as an index for ethanol withdrawal severity in mice. However, nest building outcomes after voluntary ethanol consumption have not been examined. Here, we tested male and female C57BL/6J mice on a 4-day drinking in the dark (DID) paradigm of binge-like drinking with either ethanol or a water control and analyzed nest scores at two timepoints (48 hours and 7 days) after the last DID session. At 48 hours after the last DID session, there were no differences between the two groups in nest quality. At 7 days after DID, ethanol-drinking animals showed significantly lower nest scores than the water group (z = -2.369, p=0.030). No differences were found between the ethanol- and water-drinking groups in locomotor activity or anxiety-like behavior at this timepoint in an open field test, indicating that nest building deficits in the ethanol group were likely not due to underlying differences in these behaviors. Together, these results validate the use of nest building as a naturalistic assessment of post-ethanol behavioral changes following voluntary binge-like drinking.

neuroscience↗

bioRxiv2024

Investigating the Role of Glyoxalase 1 as a Therapeutic Target for Cocaine and Oxycodone Use Disorder

Methylglyoxal (MG) is an endogenously produced non-enzymatic side product of glycolysis that acts as a partial agonist at GABAA receptors. MG that is metabolized by the enzyme glyoxalase-1 (GLO1). Inhibition of GLO1 increases methylglyoxal levels, and has been shown to modulate various behaviors, including decreasing seeking of cocaine-paired cues and ethanol consumption. The goal of these studies was to determine if GLO1 inhibition could alter cocaine-or oxycodone-induced locomotor activation and/or conditioned place preference (CPP) to cocaine or oxycodone. We used both pharmacological and genetic manipulations of GLO1 to address this question. Administration of the GLO1 inhibitor s-bromobenzylglutathione cyclopentyl diester (pBBG) did not alter the locomotor response to cocaine or oxycodone. Additionally, pBBG had no significant effect on place preference for cocaine or oxycodone. Genetic knockdown of Glo1, which is conceptually similar to pharmacological inhibition, did not have any significant effects on cocaine place preference, nor did Glo1 overexpression affect locomotor response to cocaine. In summary, our results show that neither pharmacological nor genetic manipulations of GLO1 influence locomotor response or CPP to cocaine or oxycodone.

neuroscience↗

bioRxiv2020

Genetic and pharmacological manipulations of glyoxalase 1 mediate ethanol withdrawal seizure susceptibility in mice

Central nervous system (CNS) hyperexcitability is a clinically significant feature of acute ethanol withdrawal. There is evidence for a genetic contribution to withdrawal severity, but specific genetic risk factors have not be identified. The gene glyoxalase 1 (Glo1) has been previously implicated in ethanol consumption in mice, and GLO1 inhibition can attenuate drinking in mice and rats. Here, we investigated whether genetic and pharmacological manipulations of GLO1 activity can also mediate ethanol withdrawal seizure severity in mice. Mice from two transgenic lines overexpressing Glo1 on different genetic backgrounds (C57BL/6J [B6] and FVB/NJ [FVB]) were tested for handling induced convulsions (HICs) as a measure of acute ethanol withdrawal. Following an injection of 4 g/kg alcohol, both B6 and FVB mice overexpressing Glo1 showed increased HICs compared to wild type littermates, though only the FVB line showed a statistically significant difference. We also administered daily ethanol injections (2 g/kg + 9 mg/kg 4-methylpyrazole) to wild type B6 mice for 10 days and tested them for HICs on the 10th day, following treatment with either vehicle or a GLO1 inhibitor (S-bromobenzylglutathione cyclopentyl diester [pBBG]). Treatment with pBBG reduced HICs, although this effect was only statistically significant following two 10-day cycles of ethanol exposure and withdrawal. These results provide converging genetic and pharmacological evidence that GLO1 can mediate ethanol withdrawal seizure susceptibility. We discuss the possible role of GLO1s substrate, methylglyoxal, acting as an agonist at GABAA receptors.

neuroscience↗

bioRxiv2019

Assessing the motivational effects of ethanol in mice using a discrete-trial current-intensity intracranial self-stimulation procedure

BackgroundAlcohol (ethanol) produces both rewarding and aversive effects, and sensitivity to these effects is associated with risk for an alcohol use disorder (AUD). Measurement of these motivational effects in animal models is an important but challenging aspect of preclinical research into the neurobiology of AUD. Here, we evaluated whether a discrete-trial current-intensity intracranial self-stimulation (ICSS) procedure can be used to assess both reward-enhancing and aversive responses to ethanol in mice.\n\nMethodsC57BL/6J mice were surgically implanted with bipolar stimulating electrodes targeting the medial forebrain bundle and trained on a discrete-trial current-intensity ICSS procedure. Mice were tested for changes in response thresholds after various doses of ethanol (0.5 g/kg-1.75 g/kg), using a Latin square design.\n\nResultsA 1 g/kg dose of ethanol produced a significant reward-enhancement (i.e., lowered response thresholds), whereas a 1.75 g/kg dose produced an aversive effect (elevated response thresholds).\n\nConclusionsThe discrete-trial current-intensity ICSS procedure is an effective assay for measuring both reward-enhancing responses to ethanol as well as aversive responses in the same animal. This should prove to be a useful tool for assessing the effects of experimental manipulations on the motivational effects of ethanol in mice.

neuroscience↗

bioRxiv2017

Glyoxalase (GLO1) inhibition or genetic overexpression does not alter ethanol locomotor effects: implications for GLO1 as a therapeutic target in alcohol use disorders

BackgroundGlyoxalase 1 (GLO1) is an enzyme that metabolizes methylglyoxal (MG), which is a competitive partial agonist at GABAA receptors. Inhibition of GLO1 increases concentrations of MG in the brain and decreases binge-like ethanol drinking. The present study assessed whether inhibition of GLO1, or genetic over expression of Glo1, would also alter the locomotor effects of ethanol, which might explain reduced ethanol consumption following GLO1 inhibition. We used the prototypical GABAA receptor agonist muscimol as a positive control.\n\nMethodsMale C57BL/6J mice were pretreated with aeither the GLO1 inhibitor S-bromobenzylglutathione cyclopentyl diester (pBBG; 7.5 mg/kg; Experiment 1) or muscimol (0.75 mg/kg; Experiment 2), or their corresponding vehicle. We then determined whether locomotor response to a range of ethanol doses (0, 0.5, 1.0, 1.5, 2.0, and 2.5) was altered by either pBBG or muscimol pretreatment. We also examined the locomotor response to a range of ethanol doses in FVB/NJ wild type and transgenic Glo1 over expressing mice (Experiment 3). Anxiety-like behavior (time spent in the center of the open field) was assessed in all three experiments.\n\nResultsThe ethanol dose-response curve was not altered by pretreatment with pBBG or by transgenic overexpression of Glo1. In contrast, muscimol blunted locomotor stimulation at low ethanol doses, and potentiated locomotor sedation at higher ethanol doses. No drug or genotype differences were seen in anxiety-like behavior after ethanol treatment.\n\nConclusionsThe dose of pBBG used in this study is within the effective range shown previously to reduce ethanol drinking. Glo1 overexpression has been previously shown to increase ethanol drinking. However, neither manipulation altered the dose response curve for ethanols locomotor effects, whereas muscimol appeared to enhance the locomotor sedative effects of ethanol. The present data demonstrate that reduced ethanol drinking caused by GLO1 inhibition is not due to potentiation of ethanols stimulant or depressant effects.

neuroscience↗