The ReCoDe addiction research consortium: Losing and regaining control over drug intake-Findings and future perspectives.

Substance use disorders (SUDs) are seen as a continuum ranging from goal-directed and hedonic drug use to loss of control over drug intake with aversive consequences for mental and physical health and social functioning. The main goals of our interdisciplinary German collaborative research centre on Losing and Regaining Control over Drug Intake (ReCoDe) are (i) to study triggers (drug cues, stressors, drug priming) and modifying factors (age, gender, physical activity, cognitive functions, childhood adversity, social factors, such as loneliness and social contact/interaction) that longitudinally modulate the trajectories of losing and regaining control over drug consumption under real-life conditions. (ii) To study underlying behavioural, cognitive and neurobiological mechanisms of disease trajectories and drug-related behaviours and (iii) to provide non-invasive mechanism-based interventions. These goals are achieved by: (A) using innovative mHealth (mobile health) tools to longitudinally monitor the effects of triggers and modifying factors on drug consumption patterns in real life in a cohort of 900 patients with alcohol use disorder. This approach will be complemented by animal models of addiction with 24/7 automated behavioural monitoring across an entire disease trajectory; i.e. from a naïve state to a drug-taking state to an addiction or resilience-like state. (B) The identification and, if applicable, computational modelling of key molecular, neurobiological and psychological mechanisms (e.g., reduced cognitive flexibility) mediating the effects of such triggers and modifying factors on disease trajectories. (C) Developing and testing non-invasive interventions (e.g., Just-In-Time-Adaptive-Interventions (JITAIs), various non-invasive brain stimulations (NIBS), individualized physical activity) that specifically target the underlying mechanisms for regaining control over drug intake. Here, we will report on the most important results of the first funding period and outline our future research strategy.

Associations of Menstrual Cycle and Progesterone-to-Estradiol Ratio With Alcohol Consumption in Alcohol Use Disorder: A Sex-Separated Multicenter Longitudinal Study.

OBJECTIVE: Alcohol use disorder (AUD) constitutes a critical public health issue and has sex-specific characteristics. Initial evidence suggests that progesterone and estradiol might reduce or increase alcohol intake, respectively. However, there is a need for a better understanding of how the menstrual cycle in females and the ratio of progesterone to estradiol in females and males influence alcohol use patterns in individuals with AUD. METHODS: In this sex-separated multicenter longitudinal study, the authors analyzed 12-month data on real-life alcohol use (from 21,460 smartphone entries), menstrual cycle, and serum progesterone-to-estradiol ratios (from 667 blood samples at four individual study visits) in 74 naturally cycling females and 278 males with AUD between 2020 and 2022, using generalized and general linear mixed modeling. RESULTS: Menstrual cycle phases were significantly associated with binge drinking and progesterone-to-estradiol ratio. During the late luteal phase, females showed a lower predicted binge drinking probability of 13% and a higher predicted marginal mean of progesterone-to-estradiol ratio of 95 compared with during the menstrual, follicular, and ovulatory phases (binge drinking probability and odds ratios vs. late luteal phase, respectively: 17%, odds ratio=1.340, 95% CI=1.031, 1.742; 19%, odds ratio=1.523, 95% CI=1.190, 1.949; and 20%, odds ratio=1.683, 95% CI=1.285, 2.206; difference in progesterone-to-estradiol ratios, respectively: -61, 95% CI=-105.492, -16.095; -78, 95% CI=-119.322, -37.039; and -71, 95% CI=-114.568, -27.534). In males, a higher progesterone-to-estradiol ratio was related to lower probabilities of binge drinking and of any alcohol use, with a 10-unit increase in the hormone ratio resulting in odds ratios of 0.918 (95% CI=0.843, 0.999) and 0.914 (95% CI=0.845, 0.988), respectively. CONCLUSIONS: These ecologically valid findings suggest that high progesterone-to-estradiol ratios can have a protective effect against problematic alcohol use in females and males with AUD, highlighting the progesterone-to-estradiol ratio as a promising treatment target. Moreover, the results indicate that females with AUD may benefit from menstrual cycle phase-tailored treatments.

Association between iron accumulation in the dorsal striatum and compulsive drinking in alcohol use disorder.

RATIONALE: Brain iron accumulation has been observed in neuropsychiatric disorders and shown to be related to neurodegeneration. OBJECTIVES: In this study, we used quantitative susceptibility mapping (QSM), an emerging MRI technique developed for quantifying tissue magnetic susceptibility, to examine brain iron accumulation in individuals with alcohol use disorder (AUD) and its relation to compulsive drinking. METHODS: Based on our previous projects, QSM was performed as a secondary analysis with gradient echo sequence images, in 186 individuals with AUD and 274 healthy participants. Whole-brain susceptibility values were calculated with morphology-enabled dipole inversion and referenced to the cerebrospinal fluid. Then, the susceptibility maps were compared between AUD individuals and healthy participants. The relationship between drinking patterns and susceptibility was explored. RESULTS: Whole-brain analyses showed that the susceptibility in the dorsal striatum (putamen and caudate) among AUD individuals was higher than healthy participants and was positively related to the Obsessive Compulsive Drinking Scale (OCDS) scores and the amount of drinking in the past three months. CONCLUSIONS: Increased susceptibility suggests higher iron accumulation in the dorsal striatum in AUD. This surrogate for the brain iron level was linearly associated with the compulsive drinking pattern and the recent amount of drinking, which provides us a new clinical perspective in relation to brain iron accumulation, and also might indicate an association of AUD with neuroinflammation as a consequence of brain iron accumulation. The iron accumulation in the striatum is further relevant for functional imaging studies in AUD by potentially producing signal dropout and artefacts in fMRI images.

Anterior insula stimulation suppresses appetitive behavior while inducing forebrain activation in alcohol-preferring rats.

The anterior insular cortex plays a key role in the representation of interoceptive effects of drug and natural rewards and their integration with attention, executive function, and emotions, making it a potential target region for intervention to control appetitive behaviors. Here, we investigated the effects of chemogenetic stimulation or inhibition of the anterior insula on alcohol and sucrose consumption. Excitatory or inhibitory designer receptors (DREADDs) were expressed in the anterior insula of alcohol-preferring rats by means of adenovirus-mediated gene transfer. Rats had access to either alcohol or sucrose solution during intermittent sessions. To characterize the brain network recruited by chemogenetic insula stimulation we measured brain-wide activation patterns using pharmacological magnetic resonance imaging (phMRI) and c-Fos immunohistochemistry. Anterior insula stimulation by the excitatory Gq-DREADDs significantly attenuated both alcohol and sucrose consumption, whereas the inhibitory Gi-DREADDs had no effects. In contrast, anterior insula stimulation failed to alter locomotor activity or deprivation-induced water drinking. phMRI and c-Fos immunohistochemistry revealed downstream activation of the posterior insula and medial prefrontal cortex, as well as of the mediodorsal thalamus and amygdala. Our results show the critical role of the anterior insula in regulating reward-directed behavior and delineate an insula-centered functional network associated with the effects of insula stimulation. From a translational perspective, our data demonstrate the therapeutic potential of circuit-based interventions and suggest that potentiation of insula excitability with neuromodulatory methods, such as repetitive transcranial magnetic stimulation (rTMS), could be useful in the treatment of alcohol use disorders.

Addiction Research Consortium: Losing and regaining control over drug intake (ReCoDe)-From trajectories to mechanisms and interventions.

One of the major risk factors for global death and disability is alcohol, tobacco, and illicit drug use. While there is increasing knowledge with respect to individual factors promoting the initiation and maintenance of substance use disorders (SUDs), disease trajectories involved in losing and regaining control over drug intake (ReCoDe) are still not well described. Our newly formed German Collaborative Research Centre (CRC) on ReCoDe has an interdisciplinary approach funded by the German Research Foundation (DFG) with a 12-year perspective. The main goals of our research consortium are (i) to identify triggers and modifying factors that longitudinally modulate the trajectories of losing and regaining control over drug consumption in real life, (ii) to study underlying behavioral, cognitive, and neurobiological mechanisms, and (iii) to implicate mechanism-based interventions. These goals will be achieved by: (i) using mobile health (m-health) tools to longitudinally monitor the effects of triggers (drug cues, stressors, and priming doses) and modify factors (eg, age, gender, physical activity, and cognitive control) on drug consumption patterns in real-life conditions and in animal models of addiction; (ii) the identification and computational modeling of key mechanisms mediating the effects of such triggers and modifying factors on goal-directed, habitual, and compulsive aspects of behavior from human studies and animal models; and (iii) developing and testing interventions that specifically target the underlying mechanisms for regaining control over drug intake.

Deep grey matter iron accumulation in alcohol use disorder.

PURPOSE: Evaluate brain iron accumulation in alcohol use disorder (AUD) patients compared to controls using quantitative susceptibility mapping (QSM). METHODS: QSM was performed retrospectively by using phase images from resting state functional magnetic resonance imaging (fMRI). 20 male AUD patients and 15 matched healthy controls were examined. Susceptibility values were manually traced in deep grey matter regions including caudate nucleus, combined putamen and globus pallidus, combined substantia nigra and red nucleus, dentate nucleus, and a reference white matter region in the internal capsule. Average susceptibility values from each region were compared between the patients and controls. The relationship between age and susceptibility was also explored. RESULTS: The AUD group exhibited increased susceptibility in caudate nucleus (+8.5%, p=0.034), combined putamen and globus pallidus (+10.8%, p=0.006), and dentate nucleus (+14.9%, p=0.022). Susceptibility increased with age in two of the four measured regions - combined putamen and globus pallidus (p=0.013) and combined substantia nigra and red nucleus (p=0.041). AUD did not significantly modulate the rate of susceptibility increase with age in our data. CONCLUSION: Retrospective QSM computed from standard fMRI datasets provides new opportunities for brain iron studies in psychiatry. Substantially elevated brain iron was found in AUD subjects in the basal ganglia and dentate nucleus. This was the first human AUD brain iron study and the first retrospective clinical fMRI QSM study.

The Calpain Inhibitor A-705253 Attenuates Alcohol-Seeking and Relapse with Low Side-Effect Profile.

Preclinical studies revealed contribution of N-methyl-D-aspartate receptors (NMDARs) to a variety of neuropsychiatric diseases including alcoholism, but development of NMDAR antagonists for therapeutic use has been a challenge, in part due to severe side effects. One of the key intracellular events resulting from stimulation of NMDAR is activation of calpains-calcium-dependent cysteine proteases. Here we studied whether inhibition of calpains would produce therapeutic-like effects of NMDAR antagonists but without their NMDAR-mediated side-effect profile. The calpain inhibitor A-705253 (3-10 mg/kg) was tested in a model of cue-induced reinstatement of alcohol-seeking behavior in post-dependent Wistar rats and in an alcohol deprivation effect (ADE) model in long-term alcohol drinking Wistar rats, two behavioral models for alcohol-seeking and relapse, respectively. We also tested the effect of A-705253 on the saccharine deprivation effect (SDE) as a selectivity measure. Acute treatment with A-705253 dose-dependently reduced cue-induced reinstatement of alcohol-seeking behavior. Repeated administration of A-705253 caused significant reductions of relapse-like excessive alcohol intake during the post-abstinence drinking days, an effect that persisted during two more successive drug-free drinking weeks, which was selective for the ADE as the SDE was unaffected. However, A-705253 did not produce psychostimulant, cognition impairing (delayed-matching-to-position), or psychotomimetic effects (specifically, phencyclidine discriminative stimulus effects). Taken together, these results demonstrate the involvement of calpains in alcohol-seeking and relapse and present a rationale for a novel pharmacological intervention that may reduce craving and relapse with minimal side effects in alcohol-dependent patients.

An integrated genome research network for studying the genetics of alcohol addiction.

Alcohol drinking is highly prevalent in many cultures and contributes to the global burden of disease. In fact, it was shown that alcohol constitutes 3.2% of all worldwide deaths in the year 2006 and is linked to more than 60 diseases, including cancers, cardiovascular diseases, liver cirrhosis, neuropsychiatric disorders, injuries and foetal alcohol syndrome. Alcoholism, which has been proven to have a high genetic load, is one potentially fatal consequence of chronic heavy alcohol consumption, and may be regarded as one of the most prevalent neuropsychiatric diseases afflicting our society today. The aim of the integrated genome research network 'Genetics of Alcohol Addiction'--which is a German inter-/trans-disciplinary life science consortium consisting of molecular biologists, behavioural pharmacologists, system biologists with mathematicians, human geneticists and clinicians--is to better understand the genetics of alcohol addiction by identifying and validating candidate genes and molecular networks involved in the aetiology of this pathology. For comparison, addictive behaviour to other drugs of abuse (e.g. cocaine) is studied as well. Here, we present an overview of our research consortium, the current state of the art on genetic research in the alcohol field, and list finally several of our recently published research highlights. As a result of our scientific efforts, better insights into the molecular and physiological processes underlying addictive behaviour will be obtained, new targets and target networks in the addicted brain will be defined, and subsequently, novel and individualized treatment strategies for our patients will be delivered.

Ethanol-induced activation of AKT and DARPP-32 in the mouse striatum mediated by opioid receptors.

The reinforcing properties of ethanol are in part attributed to interactions between opioid and dopaminergic signaling pathways, but intracellular mediators of such interactions are poorly understood. Here we report that an acute ethanol challenge induces a robust phosphorylation of two key signal transduction kinases, AKT and DARPP-32, in the striatum of mice. Ethanol-induced AKT phosphorylation was blocked by the opioid receptor antagonist naltrexone but unaffected by blockade of dopamine D2 receptors via sulpiride. In contrast, DARPP-32 phosphorylation was abolished by both antagonists. These data suggest that ethanol acts via two distinct but potentially synergistic striatal signaling cascades. One of these is D2-dependent, while the other is not. These findings illustrate that pharmacology of ethanol reward is likely more complex than that for other addictive drugs.

Increased mRNA Levels of TCF7L2 and MYC of the Wnt Pathway in Tg-ArcSwe Mice and Alzheimer's Disease Brain.

Several components in the Wnt pathway, including ß-catenin and glycogen synthase kinase 3 beta, have been implied in AD pathogenesis. Here, mRNA brain levels from five-month-old tg-ArcSwe and nontransgenic mice were compared using Affymetrix microarray analysis. With surprisingly small overall changes, Wnt signaling was the most affected pathway with altered expression of nine genes in tg-ArcSwe mice. When analyzing mRNA levels of these genes in human brain, transcription factor 7-like 2 (TCF7L2) and v-myc myelocytomatosis viral oncogene homolog (MYC), were increased in Alzheimer's disease (AD) (P < .05). Furthermore, no clear differences in TCF7L2 and MYC mRNA were found in brains with frontotemporal lobar degeneration, suggesting that altered regulation of these Wnt-related genes could be specific to AD. Finally, mRNA levels of three neurogenesis markers were analyzed. Increased mRNA levels of dihydropyrimidinase-like 3 were observed in AD brain, suggesting that altered Wnt pathway regulation may signify synaptic rearrangement or neurogenesis.

Neuropeptide Y (NPY) suppresses yohimbine-induced reinstatement of alcohol seeking.

INTRODUCTION: Reinstatement of responding to a previously alcohol-associated lever following extinction is an established model of relapse-like behavior and can be triggered by stress exposure. Here, we examined whether neuropeptide Y (NPY), an endogenous anti-stress mediator, blocks reinstatement of alcohol-seeking induced by the pharmacological stressor yohimbine. MATERIALS AND METHODS: NPY [5.0 or 10.0 mug/rat, intracerebroventricularly (ICV)] dose-dependently blocked the reinstatement of alcohol seeking induced by yohimbine (1.25 mg/kg, i.p.) but failed to significantly suppress the maintenance of alcohol self-administration. We then used c-fos expression mapping to examine neuronal activation following treatment with yohimbine or NPY alone or yohimbine following NPY pre-treatment. RESULTS AND DISCUSSION: The analysis was focused on a network of structures previously implicated in yohimbine-induced reinstatement, comprised of central (CeA) and basolateral (BLA) amygdala and the shell of the nucleus accumbens (Nc AccS). Within this network, both yohimbine and NPY potently induced neuronal activation, and their effects were additive, presumably indicating activation of excitatory and inhibitory neuronal populations, respectively. CONCLUSION: These results suggest that NPY selectively suppresses relapse to alcohol seeking induced by stressful events and support the NPY system as an attractive target for the treatment of alcohol addiction.

Acute ethanol challenge inhibits glycogen synthase kinase-3beta in the rat prefrontal cortex.

Intracellular signalling pathways emerge as key mediators of the molecular and behavioural effects of addictive drugs including ethanol. Previously, we demonstrated that the innate high ethanol preference in AA rats is driven by dysfunctional endocannabinoid signalling in the medial prefrontal cortex (mPFC). Here, we report that acute ethanol challenge, at a dose commonly regarded as reinforcing, strongly phosphorylates glycogen synthase kinase-3beta (GSK-3beta) in this region with corresponding increased phosphorylation of AKT, a major regulator of GSK-3beta. In the non-preferring counterpart ANA line we found a weaker, AKT-independent phosphorylation of GSK-3beta by ethanol. Furthermore, AA rats showed rapid and transient dephosphorylation of ERK1/2 upon acute ethanol challenge in the medial prefrontal cortex (mPFC) and to a lesser degree in the nucleus accumbens; ANA rats were completely non-responsive for this mechanism. Together, these results identify candidate pathways for mediating high ethanol preference and emphasize the importance of the mPFC in controlling this behaviour.

Neuroplasticity in brain reward circuitry following a history of ethanol dependence.

Mitogen-activated and extracellular regulated kinase (MEK) and extracellular signal-regulated protein kinase (ERK) pathways may underlie ethanol-induced neuroplasticity. Here, we used the MEK inhibitor 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene (UO126) to probe the role of MEK/ERK signaling for the cellular response to an acute ethanol challenge in rats with or without a history of ethanol dependence. Ethanol (1.5 g/kg, i.p.) induced expression of the marker genes c-fos and egr-1 in brain regions associated with both rewarding and stressful ethanol actions. Under non-dependent conditions, ethanol-induced c-fos expression was generally not affected by MEK inhibition, with the exception of the medial amygdala (MeA). In contrast, following a history of dependence, a markedly suppressed c-fos response to acute ethanol was found in the medial pre-frontal/orbitofrontal cortex (OFC), nucleus accumbens shell (AcbSh) and paraventricular nucleus (PVN). The suppressed ethanol response in the OFC and AcbSh, key regions involved in ethanol preference and seeking, was restored by pre-treatment with UO126, demonstrating a recruitment of an ERK/MEK-mediated inhibitory regulation in the post-dependent state. Conversely, in brain areas involved in stress responses (MeA and PVN), an MEK/ERK-mediated cellular activation by acute ethanol was lost following a history of dependence. These data reveal region-specific neuroadaptations encompassing the MEK/ERK pathway in ethanol dependence. Recruitment of MEK/ERK-mediated suppression of the ethanol response in the OFC and AcbSh may reflect devaluation of ethanol as a reinforcer, whereas loss of an MEK/ERK-mediated response in the MeA and PVN may reflect tolerance to its aversive actions. These two neuroadaptations could act in concert to facilitate progression into ethanol dependence.