Neurobiological Phenotypes Research Articles

Physiological and behavioural implications of the portosystemic shunt in C57Bl/6J mice.

A significant fraction of the popular inbred C57Bl/6J mice show structural and biochemical features of the congenital portosystemic shunt (PSS). How this hepatic abnormality affects physiological and behavioural parameters has not been explored in detail. Here, we confirmed the frequent occurrence of the PSS in C57Bl/6J mice by three different methods. We screened a cohort of 119 C57Bl/6J mice for total bile acids (TBA) in plasma, identified 11 animals (9.2%) with high TBA (>11µm; 171.1 ± 76.8µm), and confirmed PSS presence in that subset by magnetic resonance angiography and 1H-magnetic resonance spectroscopy of brain metabolites in the hippocampal area. In addition to the high glutamine and low myo-inositol levels, we detected lower levels of several neurotransmitters and metabolites in the hippocampus, higher brain weight and volume, as well as enhanced brain glucose utilisation in the PSS mice. We also observed differences in peripheral organ weights, haematological cell counts and clinical chemistry parameters in C57Bl/6J mice with and without PSS. Animals with PSS were slightly hyperlocomotive, had better balance on the rotarod, showed altered gait properties, and displayed attenuated fear memory in the fear conditioning test. Furthermore, we revealed a significant alteration of the pharmacokinetic profile of diazepam in C57Bl/6J mice with PSS. Our data support previous reports of hepatic disturbances and demonstrate an altered neurobiological phenotype in C57Bl/6J mice with PSS. Such congenital differences between inbred C57Bl/6J littermates may significantly distort experimental outcomes of pharmacological, behavioural and genetic studies. KEY POINTS: A significant proportion of C57Bl/6J mice, an inbred strain popular in preclinical research, have congenital portosystemic shunts (PSS) that allow venous blood to enter systemic circulation bypassing the liver. In this study, we extended existing knowledge of PSS consequences, particularly with respect to the effects on brain structure and function. We demonstrated that C57Bl/6J mice with PSS differ from their normal counterparts in brain size and contents of several neuroactive substances, as well as in peripheral organ weights, rate of glucose utilisation, blood cell counts and blood clinical chemistry parameters. C57Bl/6J mice with PSS showed altered locomotor behaviour, performed worse in a memory test and had abnormal blood pharmacokinetics of a benzodiazepine drug after a single administration. PSS presence may significantly complicate the interpretation of experiments in C57Bl/6J mice; therefore, we propose that before their use in biomedical studies, these mice should be screened with a simple blood test.

Genome-wide association analysis of treatment resistant schizophrenia for variant discovery and polygenic assessment

BackgroundTreatment resistant schizophrenia (TRS) is broadly defined as inadequate response to adequate treatment and is associated with a substantial increase in disease burden. Clozapine is the only approved treatment for TRS, showing superior clinical effect on overall symptomatology compared to other drugs, and is the prototype of atypical antipsychotics. Risperidone, another atypical antipsychotic with a more distinctive dopamine 2 antagonism, is commonly used in treatment of schizophrenia. Here, we conducted a genome-wide association study on patients treated with clozapine (TRS) vs. risperidone (non-TRS) and investigated whether single variants and/or polygenic risk score for schizophrenia are associated with TRS status. We hypothesized that patients who are treated with clozapine and risperidone might exhibit distinct neurobiological phenotypes that match pharmacological profiles of these drugs and can be explained by genetic differences. The study population (n = 1286) was recruited from a routine therapeutic drug monitoring (TDM) service between 2005 and 2022. History of a detectable serum concentration of clozapine and risperidone (without TDM history of clozapine) defined the TRS (n = 478) and non-TRS (n = 808) group, respectively.ResultsWe identified a suggestive association between TRS and a common variant within the LINC00523 gene with a significance just below the genome-wide threshold (rs79229764 C > T, OR = 4.89; p = 1.8 × 10−7). Polygenic risk score for schizophrenia was significantly associated with TRS (OR = 1.4, p = 2.1 × 10−6). In a large post-mortem brain sample from schizophrenia donors (n = 214; CommonMind Consortium), gene expression analysis indicated that the rs79229764 variant allele might be involved in the regulation of GPR88 and PUDP, which plays a role in striatal neurotransmission and intellectual disability, respectively.ConclusionsWe report a suggestive genetic association at the rs79229764 locus with TRS and show that genetic liability for schizophrenia is positively associated with TRS. These results suggest a candidate locus for future follow-up studies to elucidate the molecular underpinnings of TRS. Our findings further demonstrate the value of both single variant and polygenic association analyses for TRS prediction.

Ketamine-dependent patients with persistent psychosis have higher neurofilament light chain levels than patients with schizophrenia

ObjectivesKetamine can induce persisting psychosis in a subset of individuals who use it chronically and heavily. Previously, we found that the psychopathology and cognitive impairments in patients with ketamine dependence (KD) exhibiting persistent psychosis (KPP) bear resemblances with schizophrenia, albeit with less severity in those with no persistent psychosis (KNP). Furthermore, we also showed that patients with KD had higher blood levels of neurofilament light chain (NFL), a biomarker for neuroaxonal injury, compared to healthy controls. In this study, we aimed to investigate the differences in NFL levels between patients with KPP and KNP while comparing the levels of individuals with schizophrenia and healthy controls. MethodsWe enrolled 64 treatment-seeking ketamine-dependent patients (53 with KNP and 11 with KPP), 37 medication-free patients with schizophrenia, and 80 healthy controls. Blood NFL levels were measured by single molecule array immunoassay. ResultsNFL levels were highest in the KPP subgroup, followed by the KNP subgroup, and then the schizophrenia and control groups (mean ± SD: 24.5 ± 24.7, 12.9 ± 10.9, 9.2 ± 12.2, and 6.2 ± 2.2 pg/mL, respectively), with no significant difference observed between the schizophrenia and control groups. ConclusionsWe found that KD is associated with higher NFL levels compared to schizophrenia, with the KPP subgroup showing the most consistent alterations. The observation of accentuated neuroaxonal pathology in individuals with KPP implies that this clinical manifestation is associated with a specific neurobiological phenotype, despite prior evidence suggesting syndromal similarity between schizophrenia and KPP.

The interaction between early life complications and a polygenic risk score for schizophrenia is associated with brain activity during emotion processing in healthy participants.

Previous evidence suggests that early life complications (ELCs) interact with polygenic risk for schizophrenia (SCZ) in increasing risk for the disease. However, no studies have investigated this interaction on neurobiological phenotypes. Among those, anomalous emotion-related brain activity has been reported in SCZ, even if evidence of its link with SCZ-related genetic risk is not solid. Indeed, it is possible this relationship is influenced by non-genetic risk factors. Thus, this study investigated the interaction between SCZ-related polygenic risk and ELCs on emotion-related brain activity. 169 healthy participants (HP) in a discovery and 113 HP in a replication sample underwent functional magnetic resonance imaging (fMRI) during emotion processing, were categorized for history of ELCs and genome-wide genotyped. Polygenic risk scores (PRSs) were computed using SCZ-associated variants considering the most recent genome-wide association study. Furthermore, 75 patients with SCZ also underwent fMRI during emotion processing to verify consistency of their brain activity patterns with those associated with risk factors for SCZ in HP. Results in the discovery and replication samples indicated no effect of PRSs, but an interaction between PRS and ELCs in left ventrolateral prefrontal cortex (VLPFC), where the greater the activity, the greater PRS only in presence of ELCs. Moreover, SCZ had greater VLPFC response than HP. These results suggest that emotion-related VLPFC response lies in the path from genetic and non-genetic risk factors to the clinical presentation of SCZ, and may implicate an updated concept of intermediate phenotype considering early non-genetic factors of risk for SCZ.

Anti-angiogenic mechanisms and serotonergic dysfunction in the Rgs2 knockout model for the study of psycho-obstetric risk.

Psychiatric and obstetric diseases are growing threats to public health and share high rates of co-morbidity. G protein-coupled receptor signaling (e.g., vasopressin, serotonin) may be a convergent psycho-obstetric risk mechanism. Regulator of G Protein Signaling 2 (RGS2) mutations increase risk for both the gestational disease preeclampsia and for depression. We previously found preeclampsia-like, anti-angiogenic obstetric phenotypes with reduced placental Rgs2 expressionin mice. Here,we extend this to test whether conserved cerebrovascular and serotonergic mechanisms are also associated with risk for neurobiological phenotypes in the Rgs2 KO mouse. Rgs2 KO exhibited anxiety-, depression-, and hedonic-like behaviors. Cortical vascular density and vessel length decreased in Rgs2 KO; cortical and white matter thickness and cell densities were unchanged. In Rgs2 KO, serotonergic gene expression was sex-specifically changed (e.g., cortical Htr2a, Maoa increased in females but all serotonin targets unchanged or decreased in males); redox-related expression increased in paraventricular nucleus and aorta; and angiogenic gene expression was changed in male but not female cortex. Whole-cell recordings from dorsal raphe serotonin neurons revealed altered 5-HT1A receptor-dependent inhibitory postsynaptic currents (5-HT1A-IPSCs) in female but not male KO neurons. Additionally, serotonin transporter blockade by the SSRI sertraline increased the amplitude and time-to-peak of 5-HT1A-IPSCs in KO neurons to a greater extent than in WT neurons in females only. These results demonstrate behavioral, cerebrovascular, and sertraline hypersensitivity phenotypes in Rgs2 KOs, some of which are sex-specific. Disruptions may be driven by vascular and cell stress mechanisms linking the shared pathogenesis of psychiatric and obstetric disease to reveal future targets.

Impact of e-cigarette vaping aerosol exposure in pregnancy on mTOR signaling in rat fetal hippocampus.

Electronic cigarette (e-cig) use during pregnancy has become a major health concern in recent years and many view them as less harmful and may help quit or reduce combustible cigarettes. Implementing a state-of-the-art engineered vaping system, comprising an atomizer similar to those sold in vape shops, we aimed to utilize a translational e-cig inhalation delivery method to provide crucial information on the impact of prenatal e-cig aerosols on the developing brain hippocampal mTOR system in a rat model system. Gestational e-cig vaping significantly increased P-mTOR levels (p < 0.05) in the rat fetal hippocampi in the nicotine group (comprising of VG/PG + nicotine) compared to the control and the juice (comprising of VG/PG) groups. Total mTOR expression was not different among groups. Immunofluorescence imaging demonstrated P-mTOR was detected exclusively in the granule cells of the dentate gyrus of the fetal hippocampus. E-cig did not alter DEPTOR, but RAPTOR and RICTOR were higher (p < 0.05) in the Nicotine group. Gestational e-cig vaping with nicotine increased (p < 0.05) the activity and expression of 4EBP1, p70S6K, but decreased (p < 0.05) P-PKCα in the fetal hippocampi. In summary, dysregulation of mTORC1 and the related mTORC2, their activity, and downstream proteins together may play a critical role in e-cig-vaping-induced neurobiological phenotypes during development.

DNA Methylation Analysis of Imprinted Genes in the Cortex and Hippocampus of Cross-Fostered Mice Selectively Bred for Increased Voluntary Wheel-Running

We have previously shown that high runner (HR) mice (from a line genetically selected for increased wheel-running behavior) have distinct, genetically based, neurobiological phenotypes as compared with non-selected control (C) mice. However, developmental programming effects during early life, including maternal care and parent-of-origin-dependent expression of imprinted genes, can also contribute to variation in physical activity. Here, we used cross-fostering to address two questions. First, do HR mice have altered DNA methylation profiles of imprinted genes in the brain compared to C mice? Second, does maternal upbringing further modify the DNA methylation status of these imprinted genes? To address these questions, we cross-fostered all offspring at birth to create four experimental groups: C pups to other C dams, HR pups to other HR dams, C pups to HR dams, and HR pups to C dams. Bisulfite sequencing of 16 imprinted genes in the cortex and hippocampus revealed that the HR line had altered DNA methylation patterns of the paternally imprinted genes, Rasgrf1 and Zdbf2, as compared with the C line. Both fostering between the HR and C lines and sex modified the DNA methylation profiles for the paternally expressed genes Mest, Peg3, Igf2, Snrpn, and Impact. Ig-DMR, a gene with multiple paternal and maternal imprinted clusters, was also affected by maternal upbringing and sex. Our results suggest that differential methylation patterns of imprinted genes in the brain could contribute to evolutionary increases in wheel-running behavior and are also dependent on maternal upbringing and sex.

Right inferior frontal gyrus and ventromedial prefrontal activation during response inhibition is implicated in the development of PTSD symptoms

ABSTRACT Background Inhibition is a critical executive control process and an established neurobiological phenotype of PTSD, yet to our knowledge, no prospective studies have examined this using a contextual cue task that enables measurement of behavioural response and neural activation patterns across proactive and reactive inhibition. Objective The current longitudinal study utilised functional magnetic resonance imaging (fMRI) to examine whether deficits in proactive and reactive inhibition predicted PTSD symptoms six months after trauma. Method Twenty-three (65% males) medical patients receiving emergency medical care from a level 1 trauma centre were enrolled in the study and invited for an MRI scan 1-2-months post-trauma. PTSD symptoms were measured using self-report at scan and 6-months post-trauma. A stop-signal anticipation task (SSAT) during an fMRI scan was used to test whether impaired behavioural proactive and reactive inhibition, and reduced activation in right inferior frontal gyrus (rIFG), ventromedial prefrontal cortex (vmPFC), and bilateral hippocampus, were related to PTSD symptoms. We predicted that lower activation levels of vmPFC and rIFG during reactive inhibition and lower activation of hippocampus and rIFG during proactive inhibition would relate to higher 6-month PTSD symptoms. Results No significant associations were found between behavioural measures and 6-month PTSD. Separate linear regression analyses showed that reduced rIFG activation (F1,21 = 9.97, R2 = .32, p = .005) and reduced vmPFC activation (F1,21 = 5.19, R2 = .20, p = .03) significantly predicted greater 6-month PTSD symptoms; this result held for rIFG activation controlling for demographic variables and baseline PTSD symptoms (β = −.45, p = .04) and Bonferroni correction. Conclusion Our findings suggest that impaired rIFG and, to a lesser extent, vmPFC activation during response inhibition may predict the development of PTSD symptoms following acute trauma exposure. Given the small sample size, future replication studies are needed. HIGHLIGHTS Impaired inhibition may be an important risk factor for the development of PTSD following trauma, with less right inferior frontal gyrus and ventromedial prefrontal cortex activation during response inhibition predicting PTSD development.

Do behavioral test scores represent repeatable phenotypes of female mice?

The marble bury test is a commonly applied behavioral test often used to screen pharmaceuticals for treatment of compulsivity or anxiety disorders and to better understand the underlying neurobiology of these conditions using rodent models. We explore the use of the marble bury test in a repeated fashion over longer time intervals to assess how it may be used in a more chronic context. Assuming that marble bury scores represent a neurobiological phenotype of an individual, we hypothesize that the measurement of this phenotype is repeatable over time in a healthy animal. We performed four trials over the course of 12 weeks, using three overlapping scores for marble burying: 100%, >50%, and >0% buried. Despite intertrial differences in the mean number of marbles buried, we found significant repeatability scores across 12 weeks for two measurements: marbles buried 100% and marbles buried >50%. Exploration of pairwise repeatabilities between the trials revealed highest repeatability during shorter time intervals. Although the effect of time is difficult to disentangle from possible effects of body size/development on the scores, we hypothesize that a combination of these two factors together influence repeatability of scores and should be explored further. Understanding the patterns in repeatability in marble burying scores can inform experimental design to use this test over longer time intervals for chronic conditions or long-term interventions. Additionally, these data indicate that a pre-test, post-test design is possible, which can reduce the number of animals needed for research applications while maintaining statistical power.

Phenotypic differences between female and male individuals with suspicion of autism spectrum disorder

BackgroundAlthough autism spectrum disorder (ASD) is a common developmental disorder, our knowledge about a behavioral and neurobiological female phenotype is still scarce. As the conceptualization and understanding of ASD are mainly based on the investigation of male individuals, females with ASD may not be adequately identified by routine clinical diagnostics. The present machine learning approach aimed to identify diagnostic information from the Autism Diagnostic Observation Schedule (ADOS) that discriminates best between ASD and non-ASD in females and males.MethodsRandom forests (RF) were used to discover patterns of symptoms in diagnostic data from the ADOS (modules 3 and 4) in 1057 participants with ASD (18.1% female) and 1230 participants with non-ASD (17.9% % female). Predictive performances of reduced feature models were explored and compared between females and males without intellectual disabilities.ResultsReduced feature models relied on considerably fewer features from the ADOS in females compared to males, while still yielding similar classification performance (e.g., sensitivity, specificity).LimitationsAs in previous studies, the current sample of females with ASD is smaller than the male sample and thus, females may still be underrepresented, limiting the statistical power to detect small to moderate effects.ConclusionOur results do not suggest the need for new or altered diagnostic algorithms for females with ASD. Although we identified some phenotypic differences between females and males, the existing diagnostic tools seem to sufficiently capture the core autistic features in both groups.

Sources and Translational Relevance of Heterogeneity in Maternal Immune Activation Models.

The epidemiological literature reporting increased risk for neurodevelopmental and psychiatric disorders after prenatal exposure to maternal immune activation (MIA) is still evolving, and so are the attempts to model this association in animals. Epidemiological studies of MIA offer the advantage of directly evaluating human populations but are often limited in their ability to uncover pathogenic mechanisms. Animal models, on the other hand, are limited in their generalizability to psychiatric disorders but have made significant strides toward discovering causal relationships and biological pathways between MIA and neurobiological phenotypes. Like in any other model system, both planned and unplanned sources of variability exist in animal models of MIA. Therefore, the design, implementation, and interpretation of MIA models warrant a careful consideration of these sources, so that appropriate strategies can be developed to handle them satisfactorily. While every research group may have its own strategy to this aim, it is essential to report the methodological details of the chosen MIA model in order to enhancethe transparency and comparability of models across research laboratories. Even though it poses a challenge for attempts to compare experimental findings across laboratories, variability does not undermine the utility of MIA models for translational research. In fact, variability and heterogenous outcomes in MIA models offer unique opportunities for new discoveries and developments in this field, including the identification of disease pathways and molecular mechanisms determining susceptibility and resilience to MIA. This review summarizes the most important sources of variability in animal models of MIA and discusses how model variability can be used to investigate neurobiological and immunological factors causing phenotypic heterogeneity in offspring exposed to MIA.

Inflammation Subtypes and Translating Inflammation-Related Genetic Findings in Schizophrenia and Related Psychoses: A Perspective on Pathways for Treatment Stratification and Novel Therapies.

Dysregulation of immunological and inflammatory processes is frequently observed in psychotic disorders. Numerous studies have examined the complex components of innate and adaptive immune processes in schizophrenia and related psychoses. Elevated inflammation in these conditions is related to neurobiological phenotypes and associated with both genetics and environmental exposures. Recent studies have utilized multivariate cytokine approaches to identify what appears to be a subset of individuals with elevated inflammation. The degree to which these findings represent a general process of dysregulated inflammation or whether there are more refined subtypes remains unclear. Brain-imaging studies have attempted to establish the link between peripheral inflammation and gray matter disruption, white matter abnormalities, and neuropsychological phenotypes. However, the interplay between peripheral inflammation and neuroinflammation, as well as the consequences of this interplay, in the context of psychosis remains unclear and requires further investigation. This Perspectives article reviews the following elements of immune dysregulation and its clinical and therapeutic implications: (1) evidence supporting inflammation and immune dysregulation in schizophrenia and related psychoses; (2) recent advances in approaches to characterizing subgroups of patients with elevated inflammation; (3) relationships between peripheral inflammation and brain-imaging indicators of neuroinflammation; (4) convergence of large-scale genetic findings and peripheral inflammation findings; and (5) therapeutic implications: anti-inflammation interventions leveraging genetic findings for drug discovery and repurposing. We offer perspectives and examples of how multiomics technologies may be useful for constructing and studying immunogenetic signatures. Advancing research in this area will facilitate biomarker discovery, disease subtyping, and the development of etiological treatments for immune dysregulation in psychosis.

Morphological alteration in rat hippocampal neuronal dendrites following chronic binge prenatal alcohol exposure

Prenatal alcohol exposure (PAE) may result in Fetal Alcohol Spectrum Disorders (FASD). The hippocampus has been recognized as a vulnerable target to alcohol-induced developmental damage. However, the effect of prenatal exposure to alcohol on dendritic morphological adaptations throughout the hippocampal fields in the developing brain still remains largely unknown in the context of FASD. We hypothesized that chronic binge alcohol exposure during pregnancy alters dendrite arborization throughout the developing rat hippocampus. Pregnant Sprague-Dawley rats were assigned to either a pair-fed control (PF-Cont) or a binge alcohol (Alcohol) treatment group. Alcohol dams were acclimatized via a once-daily orogastric gavage of 4.5 g/kg alcohol from gestational day (GD) 5–10 and progressed to 6 g/kg alcohol from GD 11–21. Pair-fed dams similarly received isocaloric maltose dextrin. After parturition, all dams received an ad libitum diet and nursed their offspring until postnatal day (PND) 10 when the pup brains were collected for morphological analysis. PAE increased dendritic arborization and complexities of CA1, CA2/3, and DG neurons in the PND 10 rat hippocampus. The number of primary dendrites, total dendritic length, and number of dendritic branches were significantly increased following PAE, and Sholl analysis revealed significantly more intersections of the dendritic processes in PND 10 offspring following PAE compared with those in the PF-Cont group. We conclude that chronic binge PAE significantly alters hippocampal dendritic morphology in the developing hippocampus. We conjecture that this morphological alteration in postnatal rat hippocampal dendrites following chronic binge prenatal alcohol exposure may play a critical role in FASD neurobiological phenotypes.

Conceptual Analysis: A Social Neuroscience Approach to Interpersonal Interaction in the Context of Disruption and Disorganization of Attachment (NAMDA).

Humans are strongly dependent upon social resources for allostasis and emotion regulation. This applies especially to early childhood because humans—as an altricial species—have a prolonged period of dependency on support and input from caregivers who typically act as sources of co-regulation. Accordingly, attachment theory proposes that the history and quality of early interactions with primary caregivers shape children's internal working models of attachment. In turn, these attachment models guide behavior, initially with the set goal of maintaining proximity to caregivers but eventually paving the way to more generalized mental representations of self and others. Mounting evidence in non-clinical populations suggests that these mental representations coincide with differential patterns of neural structure, function, and connectivity in a range of brain regions previously associated with emotional and cognitive capacities. What is currently lacking, however, is an evidence-based account of how early adverse attachment-related experiences and/or the emergence of attachment disorganization impact the developing brain. While work on early childhood adversities offers important insights, we propose that how these events become biologically embedded crucially hinges on the context of the child–caregiver attachment relationships in which the events take place. Our selective review distinguishes between direct social neuroscience research on disorganized attachment and indirect maltreatment-related research, converging on aberrant functioning in neurobiological systems subserving aversion, approach, emotion regulation, and mental state processing in the wake of severe attachment disruption. To account for heterogeneity of findings, we propose two distinct neurobiological phenotypes characterized by hyper- and hypo-arousal primarily deriving from the caregiver serving either as a threatening or as an insufficient source of co-regulation, respectively.

Translational opportunities for circuit-based social neuroscience: advancing 21st century psychiatry.

The recent advancements of social behavioral neuroscience are unprecedented. Through manipulations targeting neural circuits, complex behaviors can be switched on and off, social bonds can be induced, and false memories can be 'incepted.' Psychiatry, however, remains tethered to concepts and techniques developed over half a century ago, including purely behavioral definitions of psychopathology and chronic, brain-wide pharmacological interventions. Drawing on recent animal and human research, we outline a circuit-level approach to the social brain and highlight studies demonstrating the translational potential of this approach. We conclude by suggesting ways both clinical practice and translational research can apply circuit-level neuroscientific knowledge to advance psychiatry, including adopting neuroscience-based nomenclature, stratifying patients into diagnostic subgroups based on neurobiological phenotypes, and pharmacologically enhancing psychotherapy.

Pre-conception exposure to THC fails to impact nicotine reward in adult offspring

Exposure to environmental stimuli in one generation can produce altered behavioral and neurobiological phenotypes in descendants. Recent work has shown that parental exposure to cannabinoids alters the rewarding properties of other abused drugs in the subsequent generation. However, whether preconception Δ9-tetrahydrocannabinol (THC) administration modifies the affective properties of nicotine in offspring is unknown. To address this question, male and female rats (F0) received THC (0 or 1.5 mg/kg) throughout the adolescent window and were bred on PND 65. In Experiment 1, adult F1-THC and F1-Veh progeny (males and females) underwent nicotine locomotor sensitization procedures during which nicotine (0 or 0.4 mg/kg) was administered every other day for five exposures, and locomotor activity was recorded on each exposure followed by a final nicotine challenge. There was no cross-generational effect of THC on nicotine locomotor sensitization, although acute exposure to nicotine produced greater activity in females relative to males independent of THC history. In Experiment 2, adult F1-THC and F1-Veh progeny (males and females) were implanted with jugular catheters and trained to self-administer nicotine (0.03 mg/kg/infusion). Following acquisition, all subjects were allowed to self-administer nicotine on a number of reinforcement schedules, e.g., FR2, FR5 and PR, followed by dose response and extinction procedures. Across all indices, F1-THC and F1-Veh subjects displayed similar IVSA of nicotine with no sex differences. The fact that there was no evidence of cross-generational effects of THC on nicotine suggests that such effects are drug-specific.

Chronic Binge Alcohol Exposure During Pregnancy Alters mTOR System in Rat Fetal Hippocampus.

Gestational alcohol exposure can contribute to fetal alcohol spectrum disorders (FASD), an array of cognitive, behavioral, and physical developmental impairments. Mammalian target of rapamycin (mTOR) plays a key role in regulating protein synthesis in response to neuronal activity, thereby modulating synaptic plasticity and long-term memory formation in the brain. Based on our previous quantitative mass spectrometry proteomic studies, we hypothesized that gestational chronic binge alcohol exposure alters mTOR signaling and downstream pathways in the fetal hippocampus. Pregnant Sprague-Dawley rats were assigned to either a pair-fed control (PF-Cont) or a binge alcohol (Alcohol) treatment group. Alcohol dams were acclimatized via a once-daily orogastric gavage of 4.5g/kg alcohol (peak BAC, 216mg/dl) from GD 5-10 and progressed to 6g/kg alcohol (peak BAC, 289mg/dl) from GD 11-21. Pair-fed dams similarly received isocaloric maltose dextrin. In the Alcohol group, following this exposure paradigm, fetal body weight and crown-rump length were decreased. The phosphorylation level of mTOR (P-mTOR) in the fetal hippocampus was decreased in the Alcohol group compared with controls. Alcohol exposure resulted in dysregulation of fetal hippocampal mTORC1 signaling, as evidenced by an increase in total 4E-BP1 expression. Phosphorylation levels of 4E-BP1 and p70 S6K were also increased following alcohol exposure. P-mTOR and P-4E-BP1 were exclusively detected in the dentate gyrus and oriens layer of the fetal hippocampus, respectively. DEPTOR and RICTOR expression levels in the fetal hippocampus were increased; however, RAPTOR was not altered by chronic binge alcohol exposure. We conclude that chronic binge alcohol exposure during pregnancy alters mTORC1 signaling pathway in the fetal hippocampus. We conjecture that this dysregulation of mTOR protein expression, its activity, and downstream proteins may play a critical role in FASD neurobiological phenotypes.

Brain regulation of emotional conflict predicts antidepressant treatment response for depression.

The efficacy of antidepressant treatment for depression is controversial due to only modest superiority demonstrated over placebo. However, neurobiological heterogeneity within depression may limit overall antidepressant efficacy. We sought to identify a neurobiological phenotype responsive to antidepressant treatment by testing pretreatment brain activation during response to, and regulation of, emotional conflict as a moderator of the clinical benefit of the antidepressant sertraline versus placebo. Using neuroimaging data from a large randomized controlled trial, we found widespread moderation of clinical benefits by brain activity during regulation of emotional conflict, in which greater down-regulation of conflict-responsive regions predicted better sertraline outcomes. Treatment-predictive machine learning utilizing brain metrics outperformed a model trained on clinical and demographic variables. Our findings demonstrate antidepressant response is predicted by brain activity underlying a key self-regulatory emotional capacity. Leveraging brain-based measures in psychiatry will forge a path toward better treatment personalization, refined mechanistic insights, and improved outcomes.Trial RegistrationEstablishing Moderators and Biosignatures of Antidepressant Response for Clinical Care for Depression (EMBARC),

Multivariate Analyses Reveal Biological Components Related to Neuronal Signaling and Immunity Mediating Electroencephalograms Abnormalities in Alcohol-Dependent Individuals from the Collaborative Study on the Genetics of Alcoholism Cohort.

The underlying molecular mechanisms associated with alcohol use disorder (AUD) risk have only been partially revealed using traditional approaches such as univariate genomewide association and linkage-based analyses. We therefore aimed to identify gene clusters related to Electroencephalograms (EEG) neurobiological phenotypes distinctive to individuals with AUD using a multivariate approach. The current project adopted a bimultivariate data-driven approach, parallel independent component analysis (para-ICA), to derive and explore significant genotype-phenotype associations in a case-control subset of the Collaborative Study on the Genetics of Alcoholism (COGA) dataset. Para-ICA subjects comprised N=799 self-reported European Americans (367 controls and 432 AUD cases), recruited from COGA, who had undergone resting EEG and genotyping. Both EEG and genomewide single nucleotide polymorphism (SNP) data were preprocessed prior to being subjected to para-ICA in order to derive genotype-phenotype relationships. From the data, 4 EEG frequency and 4 SNP components were estimated, with 2 significantly correlated EEG-genetic relationship pairs. The first such pair primarily represented theta activity, negatively correlated with a genetic cluster enriched for (but not limited to) ontologies/disease processes representing cell signaling, neurogenesis, transmembrane drug transportation, alcoholism, and lipid/cholesterol metabolism. The second component pair represented mainly alpha activity, positively correlated with a genetic cluster with ontologies similarly enriched as the first component. Disease-related enrichments for this component revealed heart and autoimmune disorders as top hits. Loading coefficients for both the alpha and theta components were significantly reduced in cases compared to controls. Our data suggest plausible multifactorial genetic components, primarily enriched for neuronal/synaptic signaling/transmission, immunity, and neurogenesis, mediating low-frequency alpha and theta abnormalities in alcohol addiction.

M10 - ALLELIC VARIATION IN GLRB PREDISPOSES TO AGORAPHOBIA BY INCREASING STARTLE RESPONSE AND MODULATING DEFENSIVE REACTIVITY

Background The molecular genetics of Panic Disorder (PD) with and without agoraphobia (AG) are still largely unknown and linkage, candidate gene and Genome-Wide Association Studies (GWAS) of PD/AG were mostly negative or inconsistent due to phenotypic diversity, genetic heterogeneity and underpowered sample sizes. Methods Assuming a dimension from agoraphobic cognitions to full PD/AG, we (1) conducted a GWAS on a dimensional anxiety phenotype (ACQ) in 1,370 healthy volunteers, (2) evaluated the found Glycine Receptor Beta (GLRB) locus in an extended sample of healthy 2,547 volunteers, (3) validated it in a population based sample (N=3,845) with another measure of AG symptoms [SCL-90], (4) assessed it relevance for the categorical phenotype PD/AG in 506 case-control pairs, (5) measured mRNA expression in vitro and post mortem (N=76), (6) examined the effect of GLRB risk polymorphisms on startle habituation, potentiation, and generalization (N=101 healthy volunteers), complemented by a behavior avoidance test (N=115 PD/AG patients) and fMRI analysis (N=76 healthy volunteers; N=86 patients with PD/AG) of fear network and general sensory activation and (7) performed analyses of agoraphobic behavior in partial Glrb knock-out mice. Results (1) GWAS on the ACQ phenotype resulted in two genome-wide significant (p Discussion Present results provide translational evidence that genetic variation within the GLRB gene predisposes to agoraphobia by modulation of the intermediate phenotype startle reflex. GWAS on the ACQ phenotype provided genome-wide significance for the GLRB locus, that we hence confirmed by validation in an independent cohort and by association with PD/AG. Results from behavioral studies in Glrb knockdown mice further supported that this gene is involved in agoraphobic behavior. As GLRB mutations are causal in hyperekpleksia, we probed whether the startle reflex as an intermediate phenotype is modulated by genetic variation in GLRB and demonstrated that risk alleles go along with impaired startle habituation and increased startle potentiation and generalization. Further fMRI analysis showed that GLRB risk alleles are associated with increased fear-induced activation of the fear network, but also with a general fear-independent activation of the sensory network. Our data propose how a genetic risk factor might via an intermediate neurobiological phenotype lead to development of a mental disorder, thus opening perspectives for novel therapeutic approaches.