Biology subjects

Kallupi, M.

Publications and source records attributed to Kallupi, M..

17 recordsLinked to original sources

bioRxiv2026

Addiction-Like Severity Predicts Prolonged Oxycodone Withdrawal-Induced Allodynia in Genetically Diverse Rats

Opioid withdrawal is associated with heightened pain sensitivity, including allodynia. Although opioid-induced allodynia is well-documented in humans and animal models, the relationship between the severity of opioid withdrawal-induced allodynia and individual addiction-like behaviors remains poorly understood. To address this gap, Heterogeneous Stock rats underwent long access (12 hours/day) intravenous oxycodone self-administration, followed by measurement of mechanical sensitivity at six timepoints across three weeks of abstinence. Rats were stratified by an Addiction Index derived from individual differences in the escalation of oxycodone intake, motivation to consume oxycodone, tolerance to oxycodones analgesic effects, and acute withdrawal-induced mechanical pain sensitivity. Here, we show that oxycodone withdrawal induces significant and prolonged allodynia for up to three weeks, with High Addiction Index rats exhibiting greater intensity and longer duration of pain sensitivity than Low Addiction Index rats. Results remained consistent even when excluding allodynia from the Addiction Index, highlighting the robustness of the association between addiction-like severity and protracted allodynia. Linear regression associations revealed that self-administration behaviors, particularly oxycodone intake escalation and motivation to seek oxycodone, predicted subsequent withdrawal-induced allodynia severity. These findings demonstrate that greater addiction-like severity is associated with more intense and prolonged withdrawal-induced pain, supporting mechanical allodynia as a marker of addiction severity. These results motivate future work to define the mechanisms linking addiction severity to protracted opioid withdrawal-induced pain, with the goal of informing targeted clinical interventions for individuals most susceptible to severe abstinence-related allodynia.

pharmacology and toxicology↗

bioRxiv2025

Ivermectin Reduces Withdrawal-Induced Alcohol Intake via CeA GABAergic Enhancement

Although FDA-approved medications for alcohol use disorder (AUD) are available, their efficacy varies across patients, highlighting the need for novel therapeutics that address inter-individual differences in disease etiology and treatment response. Genetic models, particularly heterogeneous stock (HS) rats, recapitulate human-like genetic diversity and behavioral heterogeneity, enabling the dissection of individual differences in vulnerability to AUD and pharmacotherapeutic sensitivity. P2X4 receptors, which are encoded by the gene P2rx4, are ATP-gated ion channels inhibited by ethanol and abundantly expressed in neurons found in reward and stress circuits. P2X4 receptors have emerged as key modulators of ethanol sensitivity and consumption in preclinical models. Here, we genetically predicted P2rx4 expression in whole brain in a cohort of 130 HS rats exposed to chronic intermittent ethanol (CIE) vapor and phenotyped for self-administration during acute abstinence. Rats were dichotomized into high- and low-predicted expression groups. Higher predicted P2rx4 expression was associated with increased post-vapor intake and escalation. In 32 CIE-escalated rats, ivermectin, a positive allosteric modulator of P2X4 receptors, dose-dependently reduced drinking. We stratified rats into three groups: non-responders, mild responders, and high responders. Electrophysiological recordings from CeA slices revealed that ivermectin differentially enhanced GABAergic IPSCs: high-responders exhibited sustained increases in IPSC frequency and selective amplitude reductions, while the two other groups showed transient frequency increases. All groups displayed prolonged rise times, however non-responders showed extended decay times. These findings suggest that P2rx4 upregulation serves as a vulnerability marker for dependence-like behaviors, with ivermectin attenuating withdrawal-driven alcohol consumption by enhancing CeA GABAergic inhibition.

pharmacology and toxicology↗

bioRxiv2025

Genome-wide association study of cocaine self-administration behavior in Heterogeneous Stock rats

BackgroundCocaine use disorder (CUD) is a major public health crisis with detrimental individual and societal effects. The specific genes mediating CUD remain largely unknown. MethodsWe conducted a genome-wide association study (GWAS) using outbred N/NIH Heterogeneous Stock (HS; n = 836, female = 415, male = 421) rats. We examined multiple CUD-related phenotypes that captured acquisition of self-administration, escalation of intake, and compulsive-like responding. ResultsConsistent with the existing literature, these traits were phenotypically and genetically correlated and exhibited modest heritability (h2 = 0.07 - 0.16). We identified six genome-wide significant associations. One locus on chromosome 19 was associated with the variable time between cocaine infusions (post infusion interval) and contains several carboxylesterase genes that are orthologous to the human CES1 gene; notably, carboxylesterases metabolize cocaine. Three non-synonymous coding variants in the genes Ces1c and Ces1d were in perfect linkage disequilibrium with this locus, suggesting that one or more of them might be the causal SNP. The other 5 loci also contained promising coding and expression variants, including Trak2, a gene previously associated with CUD in human GWAS and Slc10a7, Plcl1, and Satb2 which have been associated with alcohol and tobacco use disorder. ConclusionsThis is the largest genetic study of cocaine self-administration ever conducted in any species. Our results replicate previous loci associated with CUD in humans and provide several novel biological insights including the potential of pharmacological strategies targeting carboxylesterases for the treatment of CUD.

genetics↗

bioRxiv2025

A Preclinical Alcohol BioBank: Samples from Behaviorally Characterized HS Rats for AUD Research

Alcohol use disorder (AUD) imposes a significant global health burden, yet effective treatments remain limited due to the scarcity of well-characterized biological sample repositories. To address this gap, we established the UCSD Alcohol BioBank, a comprehensive resource containing thousands of samples from over 700 genetically diverse heterogeneous stock (HS) rats. Modeled after successful cocaine and oxycodone biobanks, this repository utilizes the chronic intermittent ethanol vapor exposure (CIE) model, paired with oral self-administration, to characterize AUD-like behaviors, including ethanol consumption, preference, motivation, and withdrawal symptoms such as allodynia and anxiety-like behavior. Longitudinal samples (blood, urine, and feces) are collected before, during, and after ethanol exposure, while terminal samples (brain, heart, liver, kidneys, cecum, reproductive organs, adrenal glands, peripheral blood mononuclear cells) are obtained at intoxication, acute withdrawal, protracted abstinence, or from naive controls. Samples are preserved via snap-freezing or paraformaldehyde fixation to support diverse applications, including genomics, transcriptomics, proteomics, and neuroanatomy. The genetic diversity of HS rats enables genome-wide association studies (GWAS) to identify AUD-related genetic variants. Freely available to non-profit organizations at www.alcoholbiobank.org, with genetic and behavioral data deposited in public repositories, the Alcohol BioBank facilitates collaborative research to uncover biomarkers and develop novel therapies for AUD, addressing a critical need in addiction science.

animal behavior and cognition↗

bioRxiv2025

High Incidence of Estrous Cycle Irregularities in Heterogeneous Stock (HS) Rats is Associated with Severe Cocaine Addiction-like Behaviors

Hormonal fluctuations throughout the estrous cycle have been hypothesized to influence drug-related behaviors. Preclinical models show that some cocaine-related behaviors are influenced by the estrous cycle. However, the extent to which the estrous cycle modulates cocaine self-administration in outbred heterogeneous stock (HS) rats, a population that captures human genetic diversity, is unknown. This study aimed to examine the relationship between estrous phases and cocaine self-administration behavior in HS rats using a model of extended access to cocaine self-administration. We focused on the escalation of intake, breaking point, and resistance to foot shock. Using vaginal swabbing and lavage techniques, we first characterized the relationship between estrous phase and cocaine intake. We then comprehensively evaluated estrous cycling patterns in young adult and adult HS rats, comparing them with Wistar rats. Contrary to our hypothesis, estrous phase showed no association with cocaine self-administration in HS rats. HS rats exhibited irregular estrous cycling with variability to the phase length, even in the absence of drug exposure, a phenomenon not observed in the Wistar strain. Irregular estrous cycle was associated with high cocaine-related behaviors. This study provides the first evidence that some female HS rats exhibit irregular estrous cycling. Moreover, rats with severe addiction-like behaviors had more instances of irregular cycling. These results demonstrate that, in HS rats, the estrous phase per se has no major influence on cocaine self-administration, but that the severity of addiction-like behaviors are associated with more irregularity of the estrus cycle. As HS rats gain popularity in behavioral and genome-wide studies, understanding these cycle disruptions is crucial as they may reveal genetic links into female vulnerability to drugs.

neuroscience↗

bioRxiv2022

Cocaine addiction-like behaviors are associated with long-term changes in gene regulation, energy metabolism, and GABAergic inhibition within the amygdala

The amygdala processes positive and negative valence and contributes to the development of addiction, but the underlying cell type-specific gene regulatory programs are unknown. We generated an atlas of single nucleus gene expression and chromatin accessibility in the amygdala of outbred rats with low and high cocaine addiction-like behaviors following prolonged abstinence. Between rats with different addiction indexes, we identified thousands of cell type-specific differentially expressed genes enriched for energy metabolism-related pathways that are known to affect synaptic transmission and action potentials. Rats with high addiction-like behaviors showed enhanced GABAergic transmission in the amygdala, which, along with relapse-like behaviors, were reversed by inhibition of Glyoxalase 1, which metabolizes the GABAA receptor agonist methylglyoxal. Finally, we identified thousands of cell type-specific chromatin accessible sites and transcription factor (TF) motifs where accessibility was associated with addiction index, most notably at motifs for pioneer TFs in the Fox, Sox, helix-loop-helix, and AP1 families.

genomics↗

bioRxiv2022

Individual differences in oxycodone addiction-like behaviors in a large cohort of heterogeneous stock (HS) rats

Family and twin studies demonstrate that genetic factors determine 20-60% of the vulnerability to opioid use disorder. However, the genes/alleles that mediate the risk of developing addiction-related behaviors, including the sensitivity to the analgesic efficacy of opioids, the development of tolerance, dependence, and escalation of oxycodone taking and seeking, have been ill-defined, thus hindering efforts to design pharmacological interventions to enable precision medicine strategies. Here we characterized oxycodone addiction-like behaviors in heterogeneous stock (HS) rats, that show high genetic diversity that mimics the high genetic variability in humans. HS rats were allowed to self-administer oxycodone for two h/daily for four days (ShA) and then moved to 12h/daily (LgA) for 14 days. Animals were screened for motivation to self-administer oxycodone using a progressive-ratio (PR) schedule of reinforcement and for the development of withdrawal-induced hyperalgesia and tolerance to the analgesic effects of oxycodone using the von-Frey and tail immersion tests, respectively. To reduce cohort-specific effects, we used cohorts of 46-60 rats and normalized the response level within cohorts using a Z-score. To take advantage of the four opioid-related behaviors and further identify subjects that are consistently vulnerable vs. resilient to compulsive oxycodone use, we computed an Addiction Index by averaging normalized responding (Z-scores) for the four behavioral tests. Results showed high individual variability between vulnerable and resilient rats, likely to facilitate the detection of gene variants associated with vulnerable vs. resilient individuals. Such data will have considerable translational value for designing follow-up studies in humans.

neuroscience↗

bioRxiv2022

Identification of individual differences in response to methadone, buprenorphine, and naltrexone in animal models of opioid use disorder

RationaleCurrent medications for opioid use disorder include buprenorphine, methadone, and naltrexone. While these medications show significant efficacy in reducing craving and opioid use, there are substantial individual differences in response to these treatments in humans. The reason for such difference is poorly known. ObjectivesHere, we tested the hypothesis that similar individual differences may be observed in a large population of heterogenous stock rats, that have been bred to maximize genetic diversity, using a behavioral paradigm relevant to opioid use disorder. MethodsOver 500 rats were given intermittent (4d/week) and extended access (12h/day) to oxycodone self-administration for 14 sessions to establish oxycodone dependence and escalation of intake. We then measured the effect of buprenorphine (0.5mg/kg), methadone (3mg/kg) and naltrexone (3mg/kg) on the motivation to self-administer oxycodone by using a progressive ratio schedule of reinforcement. ResultsWe found that naltrexone and buprenorphine significantly decreased motivation to oxycodone rewards. While naltrexone reduced oxycodone intake in both males and females, systemic administration with buprenorphine reduced progressive ratio responses only in males. Methadone reduced motivation to oxycodone self-administration in nearly 25% of the population, without reaching statical significance. Our results showed that the efficacy of these medications depends on the severity of addiction like behaviors, indicated by the addiction index. ConclusionsThese results demonstrate individual differences in response to medications to treat opioid use disorder in a genetically diverse population of rats.

neuroscience↗

bioRxiv2022

Identification of pre-existing microbiome and metabolic vulnerabilities to escalation of oxycodone self-administration and identification of a causal role of short-chain fatty acids in addiction-like behaviors.

The gut brain axis is thought to play a role in behavior and physiological responses through chemical, immunological, and metabolite signaling. Antibiotics, diet, and drugs can alter the transit time of gut contents as well as the makeup of the microbiome. Heterogeneity in genetics and environment are also well-known factors involved in the initiation and perpetuation of substance use disorders. Few viable genetic or biological markers are available to identify individuals who are at risk of escalating opioid intake. Primarily, the addiction field has focused on the nervous system, limiting the discovery of peripheral factors that contribute to addiction. To address this gap, we characterized the microbiome before and after drug exposure, and after antibiotics depletion in male and female heterogenous stock rats to determine if microbiome constituents are protective of escalation. We hypothesized that individuals that are prone to escalation of opioid self-administration will have distinct microbial and metabolic profiles. The fecal microbiome and behavioral responses were measured over several weeks of oxycodone self-administration and after antibiotic treatment. Antibiotic treatment reduces circulating short-chain fatty acids (SCFA) by depleting microbes that ferment fiber into these essential signaling molecules for the gut-brain axis. Depletion of the microbiome increased oxycodone self-administration in a subpopulation of animals (Responders). Supplementation of SCFAs in antibiotic depleted animals decreased elevated oxycodone self-administration. Phylogenetic functional analysis reveals distinct metabolic differences in the subpopulations of animals that are sensitive to antibiotic depletion and animals rescued by SCFA supplementation. In conclusion, this study identifies pre-existing microbiome and metabolic vulnerabilities to escalation of oxycodone self-administration, demonstrates that escalation of oxycodone self-administration dysregulates the microbiome and metabolic landscape, and identifies a causal role of short-chain fatty acids in addiction-like behaviors.

neuroscience↗

bioRxiv2022

Voluntary and forced exposure to ethanol vapor produces similar escalation of alcohol drinking but differential recruitment of brain regions related to stress, habit, and reward in male rats.

A major limitation of the most widely used current animal models of alcohol dependence is that they use forced exposure to ethanol including ethanol-containing liquid diet and chronic intermittent ethanol (CIE) vapor to produce clinically relevant blood alcohol levels (BAL) and addiction-like behaviors. We recently developed a novel animal model of voluntary induction of alcohol dependence using ethanol vapor self-administration (EVSA). In this model, naive outbred rats given intermittent access to alcohol vapor self-administration exhibit BAL in the 150-300 mg% range and develop somatic signs of withdrawal during acute abstinence. However, it is unknown whether EVSA leads to an escalation of alcohol drinking per se, and whether such escalation is associated with neuroadaptations in brain regions related to stress, reward, and habit. To address these issues, we compared the levels of alcohol drinking during withdrawal between rats passively exposed to alcohol (CIE) or voluntarily exposed to EVSA and measured the number of Fos+ neurons during acute withdrawal (16 h) in the central nucleus of the amygdala (CeA), dorsomedial striatum (DMS), dorsolateral striatum (DLS), nucleus accumbens core (Nacc), periaqueducal grey area (PAG), lateral Habenula (HbL), and the paraventricular nucleus of the thalamus (PVT). The rats were first trained to orally self-administer alcohol in standard operant chambers and then divided in 4 groups (CIE, CI-Air, EVSA and Air-SA) and exposed to intermittent ethanol vapor (passive or active) or intermittent air (passive or active) for 8 h/day, 3 days a week. CIE and EVSA rats exhibited similar BAL (150-300 mg% range) and similar escalation of alcohol drinking during withdrawal, while no changes in terms of drinking were observed in the air exposed rats. CIE and EVSA also increased the motivation for alcohol compared to their respective air control groups under a progressive ratio schedule of reinforcement. Acute withdrawal from EVSA and CIE recruited a similar number of Fos+ neurons in the CeA, however, acute withdrawal from EVSA recruited a higher number of Fos+ neurons in every other brain region analyzed compared to acute withdrawal from CIE. Moreover, acute withdrawal from EVSA specifically recruited the DMS and PVT, a pattern not observed in CIE rats. In summary, these results demonstrate that EVSA produces similar escalation of alcohol drinking, motivation to drink, and blood-alcohol levels than the CIE model, while letting animals voluntary initiate alcohol exposure and maintain alcohol dependence. Moreover, while the behavioral measures of alcohol dependence between the voluntary (EVSA) and passive (CIE) model was similar, the recruitment of neuronal ensembles during acute withdrawal was very different with a higher recruitment of Fos+ neurons in key brain regions important for stress, reward and habit-related processes. The EVSA model may be particularly useful to unveil the neuronal networks and pharmacology responsible for the voluntary induction and maintenance of alcohol dependence and may improve translational studies by providing preclinical researchers with an animal model with better face validity for alcohol use disorder.

neuroscience↗

bioRxiv2021

Characterization of cocaine addiction-like behavior in heterogeneous stock rats

Addiction is commonly characterized by escalation of drug intake, compulsive drug seeking, and continued use despite harmful consequences. However, the factors contributing to the transition from moderate drug use to these problematic patterns remain unclear, particularly regarding the role of sex. Many preclinical studies have been limited by small sample sizes, low genetic diversity, and restricted drug access, making it challenging to model significant levels of intoxication or dependence and translate findings to humans. To address these limitations, we characterized addiction-like behaviors in a large sample of >500 outbred heterogeneous stock (HS) rats using an extended cocaine self-administration paradigm (6 h/daily). We analyzed individual differences in escalation of intake, progressive-ratio (PR) responding, continued use despite adverse consequences (contingent foot shocks), and irritability-like behavior during withdrawal. Principal component analysis showed that escalation of intake, progressive ratio responding, and continued use despite adverse consequences loaded onto a single factor that was distinct from irritability-like behaviors. Categorizing rats into resilient, mild, moderate, and severe addiction-like phenotypes showed that females exhibited higher addiction-like behaviors, with a lower proportion of resilient individuals compared to males. These findings suggest that, in genetically diverse rats with extended drug access, escalation of intake, continued use despite adverse consequences, and PR responding are highly correlated measures of a shared underlying construct. Furthermore, our results highlight sex differences in resilience to addiction-like behaviors.

neuroscience↗

bioRxiv2019

Vaping nicotine-containing electronic cigarettes produces addiction-like behaviors and cardiopulmonary abnormalities in rats

The debate about electronic cigarettes has divided healthcare professionals, policymakers, and communities. Central points of disagreement are whether vaping electronic cigarettes are addictive and whether they produce major pulmonary complications. We developed a novel model of nicotine vapor self-administration in rats and found that rats voluntarily exposed themselves to nicotine vapor to the point of reaching blood nicotine levels that are similar to humans, exhibiting both addiction-like behaviors and cardiopulmonary abnormalities. The smoking cessation drug varenicline decreased electronic cigarette self-administration. These findings confirm the addictive properties and harmful effects of nicotine vapor and identify a potential medication for the treatment of electronic cigarette addiction.\n\nOne Sentence SummaryVaping nicotine-containing electronic cigarettes produces cardiopulmonary abnormalities, nicotine dependence and addiction-like behaviors, which are reduced by the smoking cessation drug varenicline.

neuroscience↗

bioRxiv2019

Characterization of the brain functional architecture of psychostimulant withdrawal using single-cell whole brain imaging

Numerous brain regions have been identified as contributing to addiction-like behaviors, but unclear is the way in which these brain regions as a whole lead to addiction. The search for a final common brain pathway that is involved in addiction remains elusive. To address this question, we used male C57BL/6J mice and performed single-cell whole-brain imaging of neural activity during withdrawal from cocaine, methamphetamine, and nicotine. We used hierarchical clustering and graph theory to identify similarities and differences in brain functional architecture. Although methamphetamine and cocaine shared some network similarities, the main common neuroadaptation between these psychostimulant drugs was a dramatic decrease in modularity, with a shift from a cortical- to subcortical-driven network, including a decrease in total hub brain regions. These results demonstrate that psychostimulant withdrawal produces the drug-dependent remodeling of functional architecture of the brain and suggest that the decreased modularity of brain functional networks and not a specific set of brain regions may represent the final common pathway that leads to addiction.\n\nSignificance StatementA key aspect of treating drug abuse is understanding similarities and differences of how drugs of abuse affect the brain. In the present study we examined how the brain is altered during withdrawal from psychostimulants. We found that each drug produced a unique pattern of activity in the brain, but that brains in withdrawal from cocaine and methamphetamine shared similar features. Interestingly, we found the major common link between withdrawal from all psychostimulants, when compared to controls, was a shift in the broad organization of the brain in the form of reduced modularity. Reduced modularity has been shown in several brain disorders, including traumatic brain injury, and dementia, and may be the common link between drugs of abuse.

neuroscience↗

bioRxiv2018

Deep brain stimulation of the nucleus accumbens shell does not decrease cocaine self-administration in cocaine-dependent rats but increases GluR1/GluA1 in the central nucleus of the amygdala

BackgroundCocaine addiction is a major public health problem. Despite decades of intense research, no effective treatments are available. Both preclinical and clinical studies of drug addiction strongly suggest that the nucleus accumbens (NAcc) is a viable target for deep brain stimulation (DBS).\n\nObjectiveAlthough previous studies have shown that DBS of the NAcc decreases cocaine seeking and reinstatement, the effects of DBS on cocaine intake in cocaine-dependent animals have not yet been investigated.\n\nMethodsRats were made cocaine-dependent by allowing them to self-administer cocaine in long-access sessions (6 h, 0.5 mg/kg/infusion). The effects of high-frequency DBS of the NAcc shell on cocaine intake was then studied. Furthermore, cocaine-induced locomotor activity, irritability-like behavior during cocaine abstinence and the levels of the -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits 1 and 2 (GluR1/GluA1 and GluR2/GluA2) after DBS were investigated.\n\nResultsContrary to our expectations, DBS of the NAcc shell induced a slight increase in both cocaine self-administration and cocaine-induced locomotor activity. In addition, 18 h into cocaine withdrawal, we found that DBS decreased irritability-like behavior. We also found that DBS-induced a robust increase in both cytosolic and synaptosomal levels of GluR1, but not GluR2, specifically in the central nucleus of the amygdala but not in other brain regions.\n\nConclusionsThese preclinical results with cocaine-dependent animals do not support high-frequency DBS of the NAcc shell as a therapeutic approach for the treatment of cocaine addiction in active cocaine users. However, the decrease in irritability-like behavior during cocaine abstinence, together with previous findings showing that DBS of the NAcc shell reduces the reinstatement of cocaine seeking in abstinent animals, warrants future investigations of DBS as a treatment for negative emotional states and craving during abstinence.\n\nHighlightsO_LIHigh-frequency DBS of the NAcc shell for the treatment of cocaine addiction is proposed\nC_LIO_LIDBS of the NAcc shell does not decrease cocaine intake in cocaine-dependent rats\nC_LIO_LIDBS increases the level of GluR1 specifically in the central nucleus of the amygdala\nC_LI

neuroscience↗

bioRxiv2017

Dynorphin counteracts orexin in the paraventricular nucleus of the thalamus: cellular and behavioral evidence

The orexin (Orx) system is known to play a critical role in drug addiction and reward-related behaviors. The dynorphin (Dyn) system, conversely, promotes depressive-like behavior and plays a key role in the aversive effects of stress. Orexin and Dyn are co-released and have opposing functions in reward and motivation in the ventral tegmental area (VTA). Earlier studies showed that microinjections of OrxA in the posterior paraventricular nucleus of the thalamus (pPVT) exerted priming-like effects and reinstated cocaine-seeking behavior, suggesting that Orx transmission in the pPVT participates in cocaine-seeking behavior. The present study sought to determine whether Orx and Dyn interact in the pPVT. Using a cellular approach, brain slices were prepared for whole-cell recordings and to study excitatory transmission in pPVT neurons. The superfusion of OrxA increased spontaneous glutamatergic transmission by increasing glutamate release onto pPVT neurons, whereas DynA decreased glutamate release. Furthermore, the augmentation of OrxA-induced glutamate release was reversed by DynA. To corroborate the electrophysiological data, separate groups of male Wistar rats were trained to self-administer cocaine or sweetened condensed milk (SCM). After self-administration training, the rats underwent extinction training and were tested with intra-pPVT administration of OrxA{+/-}DynA under extinction conditions. OrxA reinstated cocaine-and SCM-seeking behavior, with a greater effect in cocaine animals. DynA selectively blocked OrxA-induced cocaine seeking vs. SCM seeking. The data indicate that DynA in the pPVT prevents OrxA-induced cocaine seeking, perhaps by reversing the OrxA-induced increase in glutamate release, identifying a novel therapeutic target to prevent cocaine relapse.

neuroscience↗

bioRxiv2017

CRF1 receptor-dependent increases in irritability-like behavior during abstinence from chronic intermittent ethanol vapor exposure

BackgroundIn humans, emotional and physical signs of withdrawal from ethanol are commonly seen. Many of these symptoms, including anxiety-like and depression-like behavior, have been characterized in animal models of ethanol dependence. One issue with several current behavioral tests measuring withdrawal in animal models is they are often not repeatable within subjects over time. Additionally, irritability, one of the most common symptoms of ethanol withdrawal in humans, has not been well characterized in animal models. The corticotropinreleasing factor (CRF)-CRF1 receptor system has been suggested to be critical for the emergence of anxiety-like behavior in ethanol dependence, but the role of this system in irritability-like behavior has not been characterized.\n\nMethodsThe present study compared the effects of chronic intermittent ethanol vapor exposure (CIE)-induced ethanol dependence on irritabilitylike behavior in rats using the bottle-brush test during acute withdrawal and protracted abstinence. Rats were trained to self-administer ethanol in operant chambers and then either left in a nondependent state or made dependent via CIE. Naive, nondependent, and dependent rats were tested for irritability-like behavior in the bottle-brush test 8 h and 2 weeks into abstinence from ethanol. A separate cohort of dependent rats was used to examine the effect of the specific CRF1 receptor antagonist R121919 on irritability-like behavior.\n\nResultsDependent rats exhibited escalated ethanol intake compared with their own pre-CIE baseline and nondependent rats. At both time-points of abstinence, ethanol-dependent rats exhibited increased aggressive-like responses compared with naive and nondependent rats. R121919 blocked the increased irritability-like behavior in dependent rats.\n\nConclusionsThe effect of R121919 to block increased irritability-like behavior suggests that CRF plays an important role in this behavior, similar to other negative emotional withdrawal symptoms. Quantifying and understanding the molecular basis of irritability-like behavior may yield new insights into withdrawal from ethanol and other drugs of abuse.

neuroscience↗

bioRxiv2017

Optogenetic Characterization Of CeA CRF Pathways In Alcohol Dependence

Alcohol withdrawal activates a neuronal ensemble in the central nucleus of the amygdala (CeA) that is responsible for high levels of uncontrolled alcohol drinking. However, the neuronal phenotypes and circuits controlled by these neurons are unknown. We investigated the cellular identity of this CeA neuronal ensemble and found that most neurons expressed corticotropin-releasing factor (CRF). Using Crh-Cre transgenic rats combined with in vivo optogenetics, we tested the role of CeA CRF neurons and their projections in excessive alcohol self-administration during withdrawal. Rats were injected with AAV-DIO-NpHR-eYFP or AAV-DIO-eYFP and implanted with optical fibers over the CeA. Animals were then exposed to chronic intermittent ethanol vapor to induce alcohol dependence. Inactivation of CeA CRF neurons decreased alcohol drinking in dependent rats to non-dependent levels and completely suppressed activation of the CeA neuronal ensemble (Fos+ neurons) during withdrawal. No effects were observed on water or saccharin self-administration. In a second experiment, CeA CRF neurons were infected with AAV-DIO-NpHR-eYFP and optical fibers were implanted into downstream projection regions, including the bed nucleus of the stria terminalis (BNST), lateral hypothalamus (LH), parasubthalamic nucleus (pSTN), substantia innominata (SI), and parabrachial nuclei (PBN). Optogenetic inactivation of CRF terminals in the BNST reduced alcohol drinking and withdrawal signs, whereas inactivation of all other projections had no effect. These results demonstrate that CeA CRF neurons and their projections to the BNST drive excessive alcohol drinking and withdrawal in dependent rats.

neuroscience↗