Molecular Brain Adaptations to Ethanol: Role of Glycogen Synthase Kinase-3 Beta in the Transition to Excessive Consumption

Alcoholism is a complex neuropsychiatric disease that is characterized by compulsive alcohol use and intensifying cravings and withdrawals, often culminating in physiologic dependency. Fundamental alterations in brain chemistry underlie the transition from initial ethanol exposure to repetitive excessive use. Key mediators of this adaptation include changes in gene expression and signal transduction. Here we investigated gene expression pathways in prefrontal cortex and nucleus accumbens following acute or chronic ethanol treatment, to identify genes with potentially conserved involvement in the long-term response of the corticolimbic system to repeated ethanol exposure. We investigated Gsk3b, which encodes glycogen synthase kinase 3-beta, as a highly ethanol responsive gene associated with risk for long-term maladaptive responses to ethanol. On the level of the protein, we found that GSK3B and to a lesser extent the GSK3A isoform showed robust increases in inhibitory phosphorylation following acute ethanol. This inhibition may underlie aspects of the behavioral response to acute ethanol, as pre-treatment with a GSK3B inhibitor (tideglusib) augmented ethanol’s locomotor effects. Following long term ethanol exposure, we re-tested GSK3B phosphorylation and found that its ethanol response is blunted, consistent with molecular tolerance as a corollary to increased consumption. As the prefrontal cortex (PFC) plays a vital role in the reward pathway via its glutamatergic projections to the nucleus accumbens, we investigated the role of the Gsk3b gene specifically in PFC and in glutamatergic neurons. Overexpression of Gsk3b in the PFC robustly increased ethanol consumption, while deletion in Camk2a-positive neurons significantly attenuated ethanol consumption. Pharmacologic antagonism of GSK3B also decreased drinking in a model of binge-like consumption. Collectively this data implicates GSK3B as a mediator of excessive ethanol intake via its kinase activity, wherein inhibition of the kinase via phosphorylation exerts a protective effect in the context of acute ethanol, but desensitizes with repeated exposure

Posterior Contraction Rates for the Bayesian Approach to Linear Ill-Posed Inverse Problems

We consider a Bayesian nonparametric approach to a family of linear inverse problems in a separable Hilbert space setting with Gaussian noise. We assume Gaussian priors, which are conjugate to the model, and present a method of identifying the posterior using its precision operator. Working with the unbounded precision operator enables us to use partial differential equations (PDE) methodology to obtain rates of contraction of the posterior distribution to a Dirac measure centered on the true solution. Our methods assume a relatively weak relation between the prior covariance, noise covariance and forward operator, allowing for a wide range of applications

Selective GSK3B Deletion in Camk2a+ Forebrain Neurons or Inhibition Via Tideglusib, Decreases Ethanol Consumption in C57BL/6J Mice

Purpose: We previously identified glycogen synthase kinase-3 beta (Gsk3b) as a central member of a gene network highly regulated by acute ethanol in medial prefrontal cortex (mPFC) and associated with risk for alcohol dependence in humans. Further, we have demonstrated modulation of Gsk3b alters ethanol consumption in rodent models. GSK3B could thus represent a potential new therapeutic target for the treatment of alcohol use disorder (AUD). Here, we investigate the mechanisms of Gsk3b action in ethanol consumption and report preclinical evidence for the selective GSK3B inhibitor, tideglusib, as a therapeutic agent for AUD. Methods: (1) Selective Cre-induced Gsk3b deletion in Camk2a-neurons within the forebrain using transgenic Camk2a-CreER/Gsk3b floxed mice bred with Gsk3b fl/fl mice to produce Cre/Gsk3b fl/fl mice, which were injected with tamoxifen to induce Gsk3b deletion or (2) selective pharmacological antagonism of GSK3B using Tideglusib delivered via gavage in a corn oil vehicle. Actions on drinking behavior were measured using mouse intermittent ethanol, two-bottle choice self-administration models in C57BL/6J mice. Results: Deletion of Gsk3b in Camk2a-neurons decreased ethanol consumption and preference. There was no significant effects of sex or sex*genotype on either consumption or preference, so sexes were pooled. Gsk3b deletion did not alter basal locomotor activity, anxiety-like behavior (light-dark box), taste preference for quinine or saccharin, or ethanol pharmacokinetics. Initial administration of tideglusib (100mg/kg twice daily) or corn oil vehicle via gavage decreased total fluid consumption in all groups, regardless of ethanol drinking history or tideglusib treatment. However, following prolonged tideglusib, mice decreased binge (2hr) and daily (24hr) ethanol consumption and preference after three weeks of administration relative to vehicle controls. Tideglusib studies were only performed in male mice. Control studies showed no effect of tideglusib on liver fat accumulation in ethanol consuming animals. Ongoing work is assessing alternative oral tideglusib delivery methods in decreasing ethanol consumption. Conclusion: These results suggest GSK3B may be a therapeutic target for treatment of AUD. Deletion of Gsk3b in forebrain Camk2a-neurons showed a regional and cell-type specificity in GSK3B’s modulation of ethanol consumption and preference, providing insight into the mechanisms of Gsk3b action in ethanol consumption. Targeting GSK3B using tideglusib, a selective GSK3B inhibitor, also produced a decrease in ethanol consumption and preference over water during the fourth week of treatment. These findings were consistent with previous work in our lab investigating the delivery of tideglusib through intraperitoneal injections, though these studies were limited to a shorter drug-administration period. Here we have used a more therapeutically translatable route of administration via oral gavage and begun to investigate the longer-term effects of tideglusib on ethanol behaviors and toxicity. Tideglusib is a clinically available agent that warrants investigation in the treatment of AUD. Supported by NIAAA grants P50AA022537 and R01AA027581.https://scholarscompass.vcu.edu/gradposters/1161/thumbnail.jp

Reciprocal Relationships Between Stress and Depressive Symptoms: The Essential Role of the Nucleus Accumbens

BACKGROUND: Stress and depression have a reciprocal relationship, but the neural underpinnings of this reciprocity are unclear. We investigated neuroimaging phenotypes that facilitate the reciprocity between stress and depressive symptoms. METHODS: In total, 22 195 participants (52.0% females) from the population-based UK Biobank study completed two visits (initial visit: 2006-2010, age = 55.0 ± 7.5 [40-70] years; second visit: 2014-2019; age = 62.7 ± 7.5 [44-80] years). Structural equation modeling was used to examine the longitudinal relationship between self-report stressful life events (SLEs) and depressive symptoms. Cross-sectional data were used to examine the overlap between neuroimaging correlates of SLEs and depressive symptoms on the second visit among 138 multimodal imaging phenotypes. RESULTS: Longitudinal data were consistent with significant bidirectional causal relationship between SLEs and depressive symptoms. In cross-sectional analyses, SLEs were significantly associated with lower bilateral nucleus accumbal volume and lower fractional anisotropy of the forceps major. Depressive symptoms were significantly associated with extensive white matter hyperintensities, thinner cortex, lower subcortical volume, and white matter microstructural deficits, mainly in corticostriatal-limbic structures. Lower bilateral nucleus accumbal volume were the only imaging phenotypes with overlapping effects of depressive symptoms and SLEs ( CONCLUSIONS: The nucleus accumbens may play a key role in the reciprocity between stress and depressive symptoms

Brain Deficit Patterns of Metabolic Illnesses Overlap With Those for Major Depressive Disorder: A New Metric of Brain Metabolic Disease

Metabolic illnesses (MET) are detrimental to brain integrity and are common comorbidities in patients with mental illnesses, including major depressive disorder (MDD). We quantified effects of MET on standard regional brain morphometric measures from 3D brain MRI as well as diffusion MRI in a large sample of UK BioBank participants. The pattern of regional effect sizes of MET in non-psychiatric UKBB subjects was significantly correlated with the spatial profile of regional effects reported by the largest meta-analyses in MDD but not in bipolar disorder, schizophrenia or Alzheimer\u27s disease. We used a regional vulnerability index (RVI) for MET (RVI-MET) to measure individual\u27s brain similarity to the expected patterns in MET in the UK Biobank sample. Subjects with MET showed a higher effect size for RVI-MET than for any of the individual brain measures. We replicated elevation of RVI-MET in a sample of MDD participants with MET versus non-MET. RVI-MET scores were significantly correlated with the volume of white matter hyperintensities, a neurological consequence of MET and age, in both groups. Higher RVI-MET in both samples was associated with obesity, tobacco smoking and frequent alcohol use but was unrelated to antidepressant use. In summary, MET effects on the brain were regionally specific and individual similarity to the pattern was more strongly associated with MET than any regional brain structural metric. Effects of MET overlapped with the reported brain differences in MDD, likely due to higher incidence of MET, smoking and alcohol use in subjects with MDD

Effects of Independent Versus Dependent Stressful Life Events on Major Symptom Domains of Schizophrenia

We evaluated two models to link stressful life events (SLEs) with the psychopathology of schizophrenia spectrum disorders (SSD). We separated SLEs into independent (iSLEs, unlikely influenced by one\u27s behavior) and dependent (dSLEs, likely influenced by one\u27s behavior). Stress-diathesis and stress generation models were evaluated for the relationship between total, i- and d- SLEs and the severity of positive, negative, and depressive symptoms in participants with SSD. Participants with SSD (n = 286; 196 males; age = 37.5 ± 13.5 years) and community controls (n = 121; 83 males; 35.4 ± 13.9 years) completed self-report of lifetime negative total, i- and d- SLEs. Participants with SSD reported a significantly higher number of total SLEs compared to controls (B = 1.11, p = 6.4 × 1

Brain deficit patterns of metabolic illnesses overlap with those for major depressive disorder: A new metric of brain metabolic disease

Metabolic illnesses (MET) are detrimental to brain integrity and are common comorbidities in patients with mental illnesses, including major depressive disorder (MDD). We quantified effects of MET on standard regional brain morphometric measures from 3D brain MRI as well as diffusion MRI in a large sample of UK BioBank participants. The pattern of regional effect sizes of MET in non-psychiatric UKBB subjects was significantly correlated with the spatial profile of regional effects reported by the largest meta-analyses in MDD but not in bipolar disorder, schizophrenia or Alzheimer\u27s disease. We used a regional vulnerability index (RVI) for MET (RVI-MET) to measure individual\u27s brain similarity to the expected patterns in MET in the UK Biobank sample. Subjects with MET showed a higher effect size for RVI-MET than for any of the individual brain measures. We replicated elevation of RVI-MET in a sample of MDD participants with MET versus non-MET. RVI-MET scores were significantly correlated with the volume of white matter hyperintensities, a neurological consequence of MET and age, in both groups. Higher RVI-MET in both samples was associated with obesity, tobacco smoking and frequent alcohol use but was unrelated to antidepressant use. In summary, MET effects on the brain were regionally specific and individual similarity to the pattern was more strongly associated with MET than any regional brain structural metric. Effects of MET overlapped with the reported brain differences in MDD, likely due to higher incidence of MET, smoking and alcohol use in subjects with MDD

Brain-Wide Versus Genome-Wide Vulnerability Biomarkers for Severe Mental Illnesses

Severe mental illnesses (SMI), including major depressive (MDD), bipolar (BD), and schizophrenia spectrum (SSD) disorders have multifactorial risk factors and capturing their complex etiopathophysiology in an individual remains challenging. Regional vulnerability index (RVI) was used to measure individual\u27s brain‐wide similarity to the expected SMI patterns derived from meta‐analytical studies. It is analogous to polygenic risk scores (PRS) that measure individual\u27s similarity to genome‐wide patterns in SMI. We hypothesized that RVI is an intermediary phenotype between genome and symptoms and is sensitive to both genetic and environmental risks for SMI. UK Biobank sample of N = 17,053/19,265 M/F (age = 64.8 ± 7.4 years) and an independent sample of SSD patients and controls (N = 115/111 M/F, age = 35.2 ± 13.4) were used to test this hypothesis. UKBB participants with MDD had significantly higher RVI‐MDD (Cohen\u27s d = 0.20, p = 1 × 10−23) and PRS‐MDD (d = 0.17, p = 1 × 10−15) than nonpsychiatric controls. UKBB participants with BD and SSD showed significant elevation in the respective RVIs (d = 0.65 and 0.60; p = 3 × 10−5 and .009, respectively) and PRS (d = 0.57 and 1.34; p = .002 and .002, respectively). Elevated RVI‐SSD were replicated in an independent sample (d = 0.53, p = 5 × 10−5). RVI‐MDD and RVI‐SSD but not RVI‐BD were associated with childhood adversity (p \u3c .01). In nonpsychiatric controls, elevation in RVI and PRS were associated with lower cognitive performance (p \u3c 10−5) in six out of seven domains and showed specificity with disorder‐associated deficits. In summary, the RVI is a novel brain index for SMI and shows similar or better specificity for SMI than PRS, and together they may complement each other in the efforts to characterize the genomic to brain level risks for SMI

Association Between Brain Similarity to Severe Mental Illnesses and Comorbid Cerebral, Physical, and Cognitive Impairments

Severe mental illnesses (SMIs) are often associated with compromised brain health, physical comorbidities, and cognitive deficits, but it is incompletely understood whether these comorbidities are intrinsic to SMI pathophysiology or secondary to having SMIs. We tested the hypothesis that cerebral, cardiometabolic, and cognitive impairments commonly observed in SMIs can be observed in non-psychiatric individuals with SMI-like brain patterns of deviation as seen on magnetic resonance imaging. 22,883 participants free of common neuropsychiatric conditions from the UK Biobank (age = 63.4 ± 7.5 years, range = 45–82 years, 50.9% female) were split into discovery and replication samples. The regional vulnerability index (RVI) was used to quantify each participant’s respective brain similarity to meta-analytical patterns of schizophrenia spectrum disorder, bipolar disorder, and major depressive disorder in gray matter thickness, subcortical gray matter volume, and white matter integrity. Cluster analysis revealed five clusters with distinct RVI profiles. Compared with a cluster with no RVI elevation, a cluster with RVI elevation across all SMIs and brain structures showed significantly higher volume of white matter hyperintensities (Cohen’s d = 0.59, pFDR \u3c 10−16), poorer cardiovascular (Cohen’s d = 0.30, pFDR \u3c 10−16) and metabolic (Cohen’s d = 0.12, pFDR = 1.3 × 10−4) health, and slower speed of information processing (|Cohen’s d| = 0.11–0.17, pFDR = 1.6 × 10−3-4.6 × 10−8). This cluster also had significantly higher level of C-reactive protein and alcohol use (Cohen’s d = 0.11 and 0.28, pFDR = 4.1 × 10−3 and 1.1 × 10−11). Three other clusters with respective RVI elevation in gray matter thickness, subcortical gray matter volume, and white matter integrity showed intermediate level of white matter hyperintensities, cardiometabolic health, and alcohol use. Our results suggest that cerebral, physical, and cognitive impairments in SMIs may be partly intrinsic via shared pathophysiological pathways with SMI-related brain anatomical changes