Abnormal glucocorticoid receptor mRNA and protein isoform expression in the prefrontal cortex in psychiatric illness

Cortisol in schizophrenia spectrum disorders: A comprehensive meta-analysis

Schizophrenia spectrum disorders (SSD) are characterized by alterations in cortisol levels across various parameters, including stress reactivity, hair cortisol, and baseline levels, which may be influenced by antipsychotic treatment. To provide a comprehensive overview of cortisol dysregulation in SSD, we conducted meta-analyses assessing (1) the effects of antipsychotic treatment in SSD patients, and additionally comparing cortisol in SSD patients versus healthy controls (HC) (2) following stress induction (metabolic, physiological, psychological stressors), (3) in hair and (4) baseline levels. Systematic literature searches in PubMed, Web of Science, and PsycINFO (November 2024) identified 121 studies (9049 SSD patients) for inclusion. Meta-analytic results revealed that antipsychotic treatment significantly reduced cortisol levels in SSD (k = 16, g = -0.480, 95 % CI [-0.818, -0.142], p = 0.005). Additionally, compared to HC, SSD was associated with reduced cortisol suppression following dexamethasone exposure (k = 9, g = 0.299, 95 % CI [0.091, 0.507], p = 0.005) and with elevated baseline cortisol levels in the morning (k = 71, g = 0.38, 95 % CI [0.210, 0.546], p < 0.001) and evening (k = 11, g = 0.368, 95 % CI [0.076, 0.661], p = 0.014). However, there were no significant group differences in afternoon baseline cortisol, hair cortisol or cortisol reactivity to stress (p > 0.05). These findings offer a detailed understanding of cortisol alterations in SSD and improve our understanding of HPA axis dysregulation in SSD.

Molecular evidence of altered stress responsivity related to neuroinflammation in the schizophrenia midbrain

Stress and inflammation are risk factors for schizophrenia. Chronic psychosocial stress is associated with subcortical hyperdopaminergia, a core feature of schizophrenia. Hyperdopaminergia arises from midbrain neurons, leading us to hypothesise that changes in stress response pathways may occur in this region. To identify whether transcriptional changes in glucocorticoid and mineralocorticoid receptors (NR3C1/GR, NR3C2/MR) or other stress signalling molecules (FKBP4, FKBP5) exist in schizophrenia midbrain, we measured gene expression in the human brain (N = 56) using qRT-PCR. We assessed whether alterations in these mRNAs were related to previously identified high/low inflammatory status. We investigated relationships between stress-related transcripts themselves, and between FKBP5 mRNA, dopaminergic, and glial cell transcripts in diagnostic and inflammatory subgroups. Though unchanged by diagnosis, GR mRNA levels were reduced in high inflammatory compared to low inflammatory schizophrenia cases (p = 0.026). We found no effect of diagnosis or inflammation on MR mRNA. FKBP4 mRNA was decreased and FKBP5 mRNA was increased in schizophrenia (p < 0.05). FKBP5 changes occurred in high inflammatory (p < 0.001), whereas FKBP4 changes occurred in low inflammatory schizophrenia cases (p < 0.05). The decrease in mRNA encoding the main stress receptor (GR), as well as increased transcript levels of the stress-responsive negative regulator (FKBP5), may combine to blunt the midbrain response to stress in schizophrenia when neuroinflammation is present. Negative correlations between FKBP5 mRNA and dopaminergic transcripts in the low inflammatory subgroup suggest higher levels of FKBP5 mRNA may also attenuate dopaminergic neurotransmission in schizophrenia even when inflammation is absent. We report alterations in GR-mediated stress signalling in the midbrain in schizophrenia.

Effects of Antipsychotics on the Hypothalamus-Pituitary-Adrenal Axis in a Phencyclidine Animal Model of Schizophrenia

Schizophrenia (SCH) is a mental disorder that requires long-term antipsychotic treatment. SCH patients are thought to have an increased sensitivity to stress. The dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, observed in SCH, could include altered levels of glucocorticoids, glucocorticoid receptors (GRs), and associated proteins. The perinatal administration of phencyclidine (PCP) to rodents represents an animal model of SCH. This study investigated the effects of perinatal PCP exposure and subsequent haloperidol/clozapine treatment on corticosterone levels measured by ELISA and the expression of GR-related proteins (GR, pGR, HSP70, HSP90, FKBP51, and 11β-Hydroxysteroid dehydrogenase-11β-HSD) determined by Western blot, in different brain regions of adult rats. Six groups of male rats were treated on the 2nd, 6th, 9th, and 12th postnatal days (PN), with either PCP or saline. Subsequently, one saline and one PCP group received haloperidol/clozapine from PN day 35 to PN day 100. The results showed altered GR sensitivity in the rat brain after PCP exposure, which decreased after haloperidol/clozapine treatment. These findings highlight disturbances in the HPA axis in a PCP-induced model of SCH and the potential protective effects of antipsychotics. To the best of our knowledge, this is the first study to investigate the effects of antipsychotic drugs on the HPA axis in a PCP animal model of SCH.

The Glucocorticoid Receptor: Isoforms, Functions, and Contribution to Glucocorticoid Sensitivity

Glucocorticoids exert pleiotropic effects on all tissues to regulate cellular and metabolic homeostasis. Synthetic forms are used therapeutically in a wide range of conditions for their anti-inflammatory benefits, at the cost of dose and duration-dependent side effects. Significant variability occurs between tissues, disease states, and individuals with regard to both the beneficial and deleterious effects. The glucocorticoid receptor (GR) is the site of action for these hormones and a vast body of work has been conducted understanding its function. Traditionally, it was thought that the anti-inflammatory benefits of glucocorticoids were mediated by transrepression of pro-inflammatory transcription factors, while the adverse metabolic effects resulted from direct transactivation. This canonical understanding of the GR function has been brought into question over the past 2 decades with advances in the resolution of scientific techniques, and the discovery of multiple isoforms of the receptor present in most tissues. Here we review the structure and function of the GR, the nature of the receptor isoforms, and the contribution of the receptor to glucocorticoid sensitivity, or resistance in health and disease.

Hippocampal subfields, daily stressors, and resting cortisol in individuals at clinical high-risk for psychosis

INTRODUCTION

The hippocampus, comprised of functionally distinct subfields, both regulates stress and is affected by it during psychosis pathogenesis. Hippocampal abnormalities are evident across psychosis spectrum and are associated with aberrant cortisol levels and greater environmental stressors exposure. These associations, particularly at the subfield-level, are poorly understood in individuals at clinical high-risk (CHR) for psychosis. This represents a significant literature gap given this critical pathogenetic period is characterized by an interplay between environmental stressors and biological susceptibility.

METHODS

A total of 121 participants including 51 CHR (mean age=18.61) and 70 healthy controls (HC; mean age=18.3) were enrolled in the study. Participants completed a structural scan, salivary cortisol assays, and a self-report measure assessing distress from daily stressors exposure (DSI). Hippocampal subfield segmentation was conducted using Freesurfer.

RESULTS

Smaller hippocampal subfields were associated with greater stress levels. Greater DSI was associated with lower volumes in CA1 (r = -0.38) and CA2/3 (r = -0.29), but not in CA4/DG (r = -0.28), presubiculum (r = -0.09), or subiculum (r = -0.17). Higher resting cortisol was associated with lower volumes in presubiculum (r = -0.4) but not subiculum (r = -0.22), CA1 (r = 0.08), CA2/3 (r = 0.1), or CA4/DG (r = -0.005). Regressions indicated effects for CA1 and DSI (β = 0.57, p = .03) and presubiculum and cortisol (β = 0.61, p = .02) are specific to CHR participants relative to HCs.

CONCLUSIONS

The findings provided insights into links between stress and brain vulnerability during psychosis-risk period. Regional differences highlighted potentially different mechanisms by which stress impacts specific subfields. Presubiculum may be more susceptible to the impact of early stress on HPA-axis and cornu amonis to acute stressors.

Neuroimmune transcriptome changes in patient brains of psychiatric and neurological disorders

Neuroinflammation has been implicated in multiple brain disorders but the extent and the magnitude of change in immune-related genes (IRGs) across distinct brain disorders has not been directly compared. In this study, 1275 IRGs were curated and their expression changes investigated in 2467 postmortem brains of controls and patients with six major brain disorders, including schizophrenia (SCZ), bipolar disorder (BD), autism spectrum disorder (ASD), major depressive disorder (MDD), Alzheimer's disease (AD), and Parkinson's disease (PD). There were 865 IRGs present across all microarray and RNA-seq datasets. More than 60% of the IRGs had significantly altered expression in at least one of the six disorders. The differentially expressed immune-related genes (dIRGs) shared across disorders were mainly related to innate immunity. Moreover, sex, tissue, and putative cell type were systematically evaluated for immune alterations in different neuropsychiatric disorders. Co-expression networks revealed that transcripts of the neuroimmune systems interacted with neuronal-systems, both of which contribute to the pathology of brain disorders. However, only a few genes with expression changes were also identified as containing risk variants in genome-wide association studies. The transcriptome alterations at gene and network levels may clarify the immune-related pathophysiology and help to better define neuropsychiatric and neurological disorders.

DNA Methylation Pattern of Gene Promoters of MB-COMT, DRD2, and NR3C1 in Turkish Patients Diagnosed with Schizophrenia

OBJECTIVE

We aim to evaluate the methylation status of membrane-bound catechol-O-methyltransferase (MB-COMT) promotor, dopamine receptor D2 (DRD2), and nuclear receptor subfamily 3 group C member 1 (NR3C1) gene in pa- tients with SCZ by comparing healthy controls.

METHODS

A sample of 110 patients with SCZ and 100 age- and sex-matched healthy volunteers was included in the study. The interview was started by filling out data forms that included sociodemographic and clinical information. The Structured Clinical Interview for DSM-IV Axis I Disorders was used to confirming the diagnosis according to DSM-IV-TR criteria. Then the patients were evaluated with the Positive and Negative Symptoms Scale in terms of symp- tom severity. Methylation-specific polymerase chain reaction was used to determine the methylation status of MB-COMT promotor, DRD2 , and NR3C1 gene from DNA material.

RESULTS

When we compared the percentages of MB-COMT promotor, DRD2, and NR3C1 gene methylation status in SCZ patients with the healthy control group, the percentages of MB-COMT promotor (OR: 0.466; 95% CI: 0.268- 0.809; p = 0.006), DRD2 (OR: 0.439; 95% CI: 0.375-0.514; p < 0.001), and NR3C1 (OR: 0.003; 95% CI: 0.001- 0.011; p < 0.001) gene methylation status of SCZ was found to be significantly different from the control group. Whereas unmethylation of MB-COMT promotor and NR3C1 genes were associated with SCZ, the partial methylation of the DRD2 gene was related to the SCZ.

CONCLUSION

The MB-COMT promotor, DRD2, and NR3C1 gene methylation status may be associated with the SCZ in the Turkish population.

Blood-derived deoxyribonucleic acid methylation clusters associate with adverse social exposures and endophenotypes of stress-related psychiatric illness in a trauma-exposed cohort of women

Adverse social exposures (ASEs) such as low income, low educational attainment, and childhood/adult trauma exposure are associated with variability in brain region measurements of gray matter volume (GMV), surface area (SA), and cortical thickness (CT). These CNS morphometries are associated with stress-related psychiatric illnesses and represent endophenotypes of stress-related psychiatric illness development. Epigenetic mechanisms, such as 5-methyl-cytosine (5mC), may contribute to the biological embedding of the environment but are understudied and not well understood. How 5mC relates to CNS endophenotypes of psychiatric illness is also unclear. In 97 female, African American, trauma-exposed participants from the Grady Trauma Project, we examined the associations of childhood trauma burden (CTQ), adult trauma burden, low income, and low education with blood-derived 5mC clusters and variability in brain region measurements in the amygdala, hippocampus, and frontal cortex subregions. To elucidate whether peripheral 5mC indexes central nervous system (CNS) endophenotypes of psychiatric illness, we tested whether 73 brain/blood correlated 5mC clusters, defined by networks of correlated 5mC probes measured on Illumina's HumanMethylation Epic Beadchip, mediated the relationship between ASEs and brain measurements. CTQ was negatively associated with rostral middle frontal gyrus (RMFG) SA (β =-0.231, p = 0.041). Low income and low education were also associated with SA or CT in a number of brain regions. Seven 5mC clusters were associated with CTQ (pmin = 0.002), two with low education (pmin = 0.010), and three with low income (pmin = 0.007). Two clusters fully mediated the relation between CTQ and RMFG SA, accounting for 47 and 35% of variability, respectively. These clusters were enriched for probes falling in DNA regulatory regions, as well as signal transduction and immune signaling gene ontology functions. Methylome-network analyses showed enrichment of macrophage migration (p = 9 × 10-8), T cell receptor complex (p = 6 × 10-6), and chemokine-mediated signaling (p = 7 × 10-4) pathway enrichment in association with CTQ. Our results support prior work highlighting brain region variability associated with ASEs, while informing a peripheral inflammation-based epigenetic mechanism of biological embedding of such exposures. These findings could also serve to potentiate increased investigation of understudied populations at elevated risk for stress-related psychiatric illness development.

Early Life Stress Alters Expression of Glucocorticoid Stress Response Genes and Trophic Factor Transcripts in the Rodent Basal Ganglia

Early life stress shapes the developing brain and increases risk for psychotic disorders. Yet, it is not fully understood how early life stress impacts brain regions in dopaminergic pathways whose dysfunction can contribute to psychosis. Therefore, we investigated gene expression following early life stress in adult brain regions containing dopamine neuron cell bodies (substantia nigra, ventral tegmental area (VTA)) and terminals (dorsal/ventral striatum). Sprague-Dawley rats (14F, 10M) were separated from their mothers from postnatal days (PND) 2-14 for 3 h/day to induce stress, while control rats (12F, 10M) were separated for 15 min/day over the same period. In adulthood (PND98), brain regions were dissected, RNA was isolated and five glucocorticoid signalling-related and six brain-derived neurotrophic factor (Bdnf) mRNAs were assayed by qPCR in four brain regions. In the VTA, levels of glucocorticoid signalling-related transcripts differed in maternally separated rodents compared to controls, with the Fkbp5 transcript significantly lower and Ptges3 transcript significantly higher in stressed offspring. In the VTA and substantia nigra, maternally separated rodents had significantly higher Bdnf IIA and III mRNA levels than controls. By contrast, in the ventral striatum, maternally separated rodents had significantly lower expression of Bdnf I, IIA, IIC, IV and VI transcripts. Sex differences in Nr3c1, Bag1 and Fkbp5 expression in the VTA and substantia nigra were also detected. Our results suggest that early life stress has long-lasting impacts on brain regions involved in dopamine neurotransmission, changing the trophic environment and potentially altering responsiveness to subsequent stressful events in a sex-specific pattern.

Corticosterone and Glucocorticoid Receptor in the Cortex of Rats during Aging-The Effects of Long-Term Food Restriction

Numerous beneficial effects of food restriction on aging and age-related pathologies are well documented. It is also well-established that both short- and long-term food restriction regimens induce elevated circulating levels of glucocorticoids, stress-induced hormones produced by adrenal glands that can also exert deleterious effects on the brain. In the present study, we examined the effect of long-term food restriction on the glucocorticoid hormone/glucocorticoid receptor (GR) system in the cortex during aging, in 18- and 24-month-old rats. Corticosterone level was increased in the cortex of aged ad libitum-fed rats. Food restriction induced its further increase, accompanied with an increase in the level of 11β-hydroxysteroid dehydrogenase type 1. However, alterations in the level of GR phosphorylated at Ser²³² were not detected in animals on food restriction, in line with unaltered CDK5 level, the decrease of Hsp90, and an increase in a negative regulator of GR function, FKBP51. Moreover, our data revealed that reduced food intake prevented age-related increase in the levels of NFκB, gfap, and bax, confirming its anti-inflammatory and anti-apoptotic effects. Along with an increase in the levels of c-fos, our study provides additional evidences that food restriction affects cortical responsiveness to glucocorticoids during aging.

Aberrant anterior cingulate processing of anticipated threat as a mechanism for psychosis

Stress and abnormal stress response are associated with schizophrenia spectrum disorder (SSD), but the brain mechanisms linking stress to symptomatology remain unclear. In this study, we used a stress-based functional neuroimaging task, reverse-translated from preclinical studies, to test the hypothesis that abnormal corticolimbic processing of stressful threat anticipation is associated with psychosis and affective symptoms in SSD. Participants underwent an MRI-compatible ankle-shock task (AST) in which the threat of mild electrical shock was anticipated. We compared functional brain activations during anticipatory threat periods from N = 18 participants with SSD (10 M/8F) to those from N = 12 community controls (9 M/3F). After family-wise error correction, only one region, the ventral anterior cingulate cortex (vACC), showed significantly reduced activation compared with controls. vACC activation significantly correlated with clinical symptoms measured by the Brief Psychiatric Rating Scale total score (r = 0.54) and the psychosis subscale (r = 0.71), and inversely correlated with trait depression measured by the Maryland Trait and State Depression scale (r=-0.48). Deficient activation in vACC under stress of anticipated threat may lead to aberrant interpretation of such threat, contributing to psychosis and mood symptoms in SSD. This experimental paradigm has translational potential and may identify circuitry-level mechanisms of stress-related mental illness, leading to more targeted treatment.

Gene Expression Of Methylation Cycle And Related Genes In Lymphocytes And Brain Of Patients With Schizophrenia And Non-Psychotic Controls

Some of the biochemical abnormalities underlying schizophrenia, involve differences in methylation and methylating enzymes, as well as other related target genes. We present results of a study of differences in mRNA expression in peripheral blood lymphocytes (PBLs) and post-mortem brains of chronic schizophrenics (CSZ) and non-psychotic controls (NPC), emphasizing the differential effects of sex and antipsychotic drug treatment on mRNA findings. We studied mRNA expression in lymphocytes of 61 CSZ and 49 NPC subjects using qPCR assays with TaqMan probes to assess levels of DNMT, TET, GABAergic, NR3C1, BDNF mRNAs, and several additional targets identified in a recent RNA sequence analysis. In parallel we studied DNMT1 and GAD67 in samples of brain tissues from 19 CSZ, 26 NPC. In PBLs DNMT1 and DNMT3A mRNA levels were significantly higher in male CSZ vs NPC. No significant differences were detected in females. The GAD1, NR3C1 and CNTNAP2 mRNA levels were significantly higher in CSZ than NPC. In CSZ patients treated with clozapine, GAD-1 related, CNTNAP2, and IMPA2 mRNAs were significantly higher than in CSZ subjects not treated with clozapine. Differences between CSZ vs NPC in these mRNAs was primarily attributable to the clozapine treatment. In the brain samples, DNMT1 was significantly higher and GAD67 was significantly lower in CSZ than in NPC, but there were no significant sex differences in diagnostic effects. These findings highlight the importance of considering sex and drug treatment effects in assessing the substantive significance of differences in mRNAs between CSZ and NPC.

Conserved allosteric ensembles in disordered proteins using TROSY/anti-TROSY R2-filtered spectroscopy

Defining the role of intrinsic disorder in proteins in the myriad of biological processes with which it is involved represents a significant goal in modern biophysics. Toward this end, NMR is uniquely suited for molecular studies of dynamic and disordered regions, but studying these regions in concert with their more structured domains and binding partners presents spectroscopic challenges. Here, we investigate the interactions between the structured and disordered regions of the human glucocorticoid receptor (GR). To do this, we developed an NMR strategy that relies on a novel relaxation filter for the simultaneous study of structured and unstructured regions. Using this approach, we conducted a comparative analysis of three translational isoforms of GR containing a folded DNA-binding domain (DBD) and two disordered regions that flank the DBD, one of which varies in size in the different isoforms. Notably, we were able to assign resonances that had previously been inaccessible because of the spectral complexity of the translational isoforms, which in turn allowed us to 1) identify a region of the structured DBD that undergoes significant changes in the local chemical environment in the presence of the disordered region and 2) determine differences in the conformational ensembles of the disordered regions of the translational isoforms. Furthermore, an ensemble-based thermodynamic analysis of the isoforms reveals conserved patterns of stability within the N-terminal domain of GR that persist despite low sequence conservation. These studies provide an avenue for further investigations of the mechanistic underpinnings of the functional relevance of the translational isoforms of GR while also providing a general NMR strategy for studying systems containing both structured and disordered regions.

Cortisol-dehydroepiandrosterone ratios are inversely associated with hippocampal and prefrontal brain volume in schizophrenia

While high levels of glucocorticoids are generally neuro-damaging, a related adrenal steroid, dehydroepiandrosterone (DHEA), has anti-glucocorticoid and neuroprotective properties. Previous work has shown increased circulating levels of DHEA and abnormal cortisol/DHEA ratios in people with schizophrenia, however reports are limited and their relationship to neuropathology is unclear. We performed the largest study to date to compare levels of serum DHEA and cortisol/DHEA ratios in people with schizophrenia and healthy controls, and investigated the extent to which cortisol/DHEA ratios predict brain volume. Serum cortisol and DHEA were assayed in 94 people with schizophrenia and 81 healthy controls. T1-weighted high-resolution anatomical scans were obtained using a 3 T Achieva scanner on a subset of 59 people with schizophrenia and 60 healthy controls. Imaging data were preprocessed and analyzed using SPM12. People with schizophrenia had significantly increased serum DHEA levels (p = 0.002), decreased cortisol/DHEA ratios (p = 0.02) and no difference in cortisol levels compared to healthy controls. Cortisol/DHEA ratios were inversely correlated with hippocampal (r = -0.33 p = 0.01) and dorsolateral prefrontal cortex (r = -0.30, p = 0.02) volumes in patients. Our findings suggest that the cortisol/DHEA ratio may be a molecular blood signature of hippocampal and cortical damage. These results further implicate the role of DHEA and hypothalamic-pituitary-adrenal axis dysfunction in the pathophysiology of schizophrenia.

Increased macrophages and changed brain endothelial cell gene expression in the frontal cortex of people with schizophrenia displaying inflammation

Elevated pro-inflammatory cytokines exist in both blood and brain of people with schizophrenia but how this affects molecular indices of the blood-brain barrier (BBB) is unclear. Eight mRNAs relating to BBB function, a microglia and three immune cell markers were measured by qPCR in the prefrontal cortex from 37 people with schizophrenia/schizoaffective disorder and 37 matched controls. This cohort was previously grouped into "high inflammation" and "low inflammation" subgroups based on cortical inflammatory-related transcripts. Soluble intercellular adhesion molecule-1 (sICAM1) was measured in the plasma of 78 patients with schizophrenia/schizoaffective disorder and 73 healthy controls. We found that sICAM1 was significantly elevated in schizophrenia. An efflux transporter, ABCG2, was lower, while mRNAs encoding VE-cadherin and ICAM1 were higher in schizophrenia brain. The "high inflammation" schizophrenia subgroup had lower ABCG2 and higher ICAM1, VE-cadherin, occludin and interferon-induced transmembrane protein mRNAs compared to both "low inflammation" schizophrenia and "low inflammation" control subgroups. ICAM1 immunohistochemistry showed enrichment in brain endothelium regardless of diagnosis and was localised to astrocytes in some brains. Microglia mRNA was not altered in schizophrenia nor did it correlate with ICAM1 expression. Immune cell mRNAs were elevated in "high inflammation" schizophrenia compared to both "low inflammation" schizophrenia and controls. CD163+ perivascular macrophages were identified by immunohistochemistry in brain parenchyma in over 40% of "high inflammation" schizophrenia brains. People with high levels of cytokine expression and schizophrenia display changes consistent with greater immune cell transmigration into brain via increased ICAM1, which could contribute to other neuropathological changes found in this subgroup of people.

Altered Expression of Glucocorticoid Receptor and Neuron-Specific Enolase mRNA in Peripheral Blood in First-Episode Schizophrenia and Chronic Schizophrenia

INTRODUCTION

It is well-known that altered hypothalamus-pituitary-adrenal (HPA) axis process has an important role in the neurodegenerative process in schizophrenia (SZ). However, this neurodegenerative mechanism has not been clarified in SZ. Therefore, the main purpose of this study was to determine HPA axis damage in the first-episode, unmedicated schizophrenia (FES) patients and chronic schizophrenia (CSZ) patients in comparison with healthy controls (HC) by means of quantitative analysis of the peripheral blood mRNA expression of glucocorticoid receptor (GR), GR transcripts containing exons 1B (GR-1B), and neuron specific enolase (NSE) genes and serum cortisol and NSE, a specific serum marker for neuronal damage.

METHODS

In the present study, 43 FES patients, 39 CSZ, and 47 HC were included. The peripheral blood mRNA expressions for GR, GR-1B, and NSE genes were determined by real-time quantitative polymerase chain reaction (RT-qPCR). Serum cortisol and NSE were analyzed by electrochemiluminescence immunoassay technique.

RESULTS

Levels of GR mRNA were significantly lower in FES and CSZ than that in HC. The expression of GR-1B mRNA was significantly decreased in CSZ when compared with that in FES. Levels of NSE mRNA were significantly lower in CSZ than that in FES patients or HC patients. CSZ patients showed significantly lower cortisol concentrations than FES and HC patients. FES patients showed significantly higher NSE concentrations than CSZ and HC.

CONCLUSION

Our findings support that there is disrupted HPA axis system in the SZ and suggest that CSZ patients suffer a greater HPA axis damage than FES patients. Our research implicated underlying GR mRNA dysregulation in SZ and the potential importance of the functional GR-1B transcription in CSZ.

Transcriptional changes in the stress pathway are related to symptoms in schizophrenia and to mood in schizoaffective disorder

Altered levels of stress-signalling transcripts have been identified in post-mortem brains of people with schizophrenia, and since stress effects may be expressed throughout the body, there should be similar changes in peripheral cells. However, the extent to which these markers are altered in peripheral white blood cells of people with schizophrenia is not known. Furthermore, how peripheral cortisol and stress-related mRNA are associated with negative symptom severity and emotional states in people with schizophrenia versus schizoaffective disorder has not been determined. Whole blood samples were collected from 86 patients with either schizophrenia or schizoaffective disorder (56 people with schizophrenia and 30 people with schizoaffective disorder), and 77 healthy controls. Total RNA was isolated, cDNA was synthesized, and stress-signalling mRNA levels (for NR3C1, FKBP5, FKBP4, PTGES3 and BAG1) were determined. Stress and symptom severity scores were measured by the Depression, Anxiety and Stress Scale, and the Positive and Negative Syndrome Scale, respectively. We found increased FKBP5 mRNA, Z(156) = 2.5, p = 0.01, decreased FKBP4 mRNA, t(155) = 3.5, p ≤ 0.001, and decreased PTGES3 mRNA, t(153) = 3.0, p ≤ 0.01, in schizophrenia and schizoaffective disorder cohorts combined compared to healthy controls. Stress-related peripheral mRNA levels were differentially correlated with negative emotional states and symptom severity in schizoaffective disorder (β's = -0.45-0.56, p's = 0.05-0.001) and schizophrenia (β's = -0.34-0.38, p's = 0.04-0.03), respectively. Therefore, molecules of the stress-signalling pathway appear to differentially contribute to clinical features of schizophrenia versus schizoaffective disorder.

Glucocorticoid receptor alpha translational isoforms as mediators of early adversities and negative emotional states

Childhood trauma (CT) increases the risk for psychopathology through disturbed acquisition and extinction of fear. The effects of CT are mediated by abnormalities of the hypothalamic-pituitary-adrenal axis and glucocorticoid receptor (GR). Since, the alterations in GRα translational isoforms have been documented in psychiatric disorders we sought to: 1) explore whether multiple GRα isoforms in the human peripheral blood mononuclear cells of two independent cohorts (whole cell n = 40; and nuclear extracts n = 43, adult subjects) mediate the effect of CT on negative affectivity (NA) measured by Depression, Anxiety and Stress Scales (DASS), and 2) examine their role/function during fear extinction in the animal model. In multiple regression analysis, CT, nuclear 40-kDa GRα, their interactions and FKBP5 explained 22%-35% of variance in DASS scores. Structural equation modeling showed that CT had a significant direct effect on 40-kDa and DASS in both cohorts, and on the nuclear 25-kDa GRα. The association between 40-kDa and total DASS was significantly mediated by nuclear FKBP5, whereas on DASS anxiety, over FKBP5 in both cohorts and nuclear full length GRα. Nuclear 40-kDa GRα and its interaction with CT had a significant direct effect on DASS anxiety. In mice, the successful extinction learning was followed by nuclear translocation of 40-kDa GRα and induction of BDNF exon IV expression. Our data revealed that the association between CT and adult NA in non-clinical subjects is mediated by the GRα translational isoforms, in particular 40-kDa GRα, and emphasized its role in fear extinction and neural plasticity.

Intracellular compartment-specific proteasome dysfunction in postmortem cortex in schizophrenia subjects

Protein homeostasis is an emerging component of schizophrenia (SZ) pathophysiology. Proteomic alterations in SZ are well-documented and changes in transcript expression are frequently not associated with changes in protein expression in SZ brain. The underlying mechanism driving these changes remains unknown, though altered expression of ubiquitin proteasome system (UPS) components have implicated protein degradation. Previous studies have been limited to protein and transcript expression, however, and do not directly test the function of the proteasome. To address this gap in knowledge, we measured enzymatic activity associated with the proteasome (chymotrypsin-, trypsin-, and caspase-like) in the superior temporal gyrus (STG) of 25 SZ and 25 comparison subjects using flourogenic substrates. As localization regulates which cellular processes the proteasome contributes to, we measured proteasome activity and subunit expression in fractions enriched for nucleus, cytosolic, and membrane compartments. SZ subjects had decreased trypsin-like activity in total homogenate. This finding was specific to the nucleus-enriched fraction and was not associated with changes in proteasome subunit expression. Interestingly, both chymotrypsin-like activity and protein expression of 19S RP subunits, which facilitate ubiquitin-dependent degradation, were decreased in the cytosol-enriched fraction of SZ subjects. Intracellular compartment-specific proteasome dysfunction implicates dysregulation of protein expression both through altered ubiquitin-dependent degradation of cytosolic proteins and regulation of protein synthesis due to degradation of transcription factors and transcription machinery in the nucleus. Together, these findings implicate proteasome dysfunction in SZ, which likely has a broad impact on the proteomic landscape and cellular function in the pathophysiology of this illness.

Glucocorticoid receptor isoform-specific regulation of development, circadian rhythm, and inflammation in mice

Glucocorticoids are primary stress hormones, and their synthetic derivatives are widely used clinically. The therapeutic efficacy of these steroids is limited by side effects and glucocorticoid resistance. Multiple glucocorticoid receptor (GR) isoforms are produced from a single gene by alternative translation initiation; however, the role individual isoforms play in tissue-specific responses to glucocorticoids is unknown. We have generated knockin mice that exclusively express the most active receptor isoform, GR-C3. GR-C3 knockin mice die at birth due to respiratory distress. Microarray analysis of fibroblasts from wild-type and GR-C3 mice indicated that most genes regulated by GR-C3 were unique to this isoform. Antenatal glucocorticoid administration rescued GR-C3 knockin mice from neonatal death. Dual-energy X-ray absorptiometry revealed no major alterations in body composition for rescued knockin mice. Rescued female, but not male, GR-C3 mice exhibited increased wheel running activity in the light portion of the day. LPS administration induced premature mortality in rescued GR-C3 knockin mice, and gene expression studies revealed a deficiency in the ability of GR-C3 to repress a large cohort of immune and inflammatory response genes. These findings demonstrate that specific GR translational isoforms can influence development, circadian rhythm, and inflammation through the regulation of distinct gene networks.-Oakley, R. H., Ramamoorthy, S., Foley, J. F., Busada, J. T., Lu, N. Z., Cidlowski, J. A. Glucocorticoid receptor isoform-specific regulation of development, circadian rhythm, and inflammation in mice.

Nuclear Receptors and Neuroinflammation in Schizophrenia

Introduction

Several nuclear receptor family members have been associated with schizophrenia and inflammation. Vitamins A and D exert anti-inflammatory actions, but their receptors (mainly nuclear receptors) have not been extensively studied in either schizophrenia brains or in association with neuroinflammation. We examined the expression of vitamin A (RARs and RXRs) and vitamin D and protein disulphide-isomerase A3 (PDIA3) receptors, as well as nuclear orphan receptors (NR4As), in the context of elevated cytokine expression in the dorsolateral prefrontal cortex (DLPFC).

Methods

mRNA levels of nuclear receptors were measured in DLPFC tissues via RT-qPCR. ANCOVAs comparing high inflammation schizophrenia, low inflammation schizophrenia and low inflammation control groups were performed.

Results

RARG, RXRB, NR4A1 and NR4A3 transcripts showed significant differential expression across the three groups (ANCOVA p = 0.02-0.001). Post hoc testing revealed significant reductions in RARG expression in schizophrenia with low inflammation compared to schizophrenia with high inflammation and to controls, and RXRB mRNA was significantly reduced in schizophrenia with low inflammation compared to controls. NR4A1 and NR4A3 mRNAs were decreased in schizophrenia with high inflammation compared to schizophrenia with low inflammation, with NR4A1 also significantly different to controls.

Conclusion

In schizophrenia, changes in nuclear receptor mRNA levels involved with mediating actions of vitamin A derivatives vary according to the inflammatory state of brains.

Considerations for optimal use of postmortem human brains for molecular psychiatry: lessons from schizophrenia

Schizophrenia is a disabling disease impacting millions of people around the world, for which there is no known cure. Current antipsychotic treatments for schizophrenia mainly target psychotic symptoms, do little to ameliorate social or cognitive deficits, have side-effects that cause weight gain, and diabetes and 30% of people do not respond. Thus, better therapeutics for schizophrenia aimed at the route biologic changes are needed and discovering the underlying neurobiology is key to this quest. Postmortem brain studies provide the most direct and detailed way to determine the pathophysiology of schizophrenia. This chapter outlines steps that can be taken to ensure the best-quality molecular data from postmortem brain tissue are obtained. In this chapter, we also discuss targeted and high-throughput methods for examining gene and protein expression and some of the strengths and limitations of each method. We briefly consider why gene and protein expression changes may not always concur within brain tissue. We conclude that postmortem brain research that investigates gene and protein expression in well-characterized and matched brain cohorts provides an important foundation to be considered when interpreting data obtained from studies of living schizophrenia patients.

Transcriptomic Analysis Shows Decreased Cortical Expression of NR4A1, NR4A2 and RXRB in Schizophrenia and Provides Evidence for Nuclear Receptor Dysregulation

Many genes are differentially expressed in the cortex of people with schizophrenia, implicating factors that control transcription more generally. Hormone nuclear receptors dimerize to coordinate context-dependent changes in gene expression. We hypothesized that members of two families of nuclear receptors (NR4As), and retinoid receptors (RARs and RXRs), are altered in the dorsal lateral prefrontal cortex (DLPFC) of people with schizophrenia. We used next generation sequencing and then qPCR analysis to test for changes in mRNA levels for transcripts encoding nuclear receptors: orphan nuclear receptors (3 in the NR4A, 3 in the RAR, 3 in the RXR families and KLF4) in total RNA extracted from the DLPFC from people with schizophrenia compared to controls (n = 74). We also correlated mRNA levels with demographic factors and with estimates of antipsychotic drug exposure (schizophrenia group only). We tested for correlations between levels of transcription factor family members and levels of genes putatively regulated by these transcription factors. We found significantly down regulated expression of NR4A1 (Nurr 77) and KLF4 mRNAs in people with schizophrenia compared to controls, by both NGS and qPCR (p = or <0.01). We also detected decreases in NR4A2 (Nurr1) and RXRB mRNAs by using qPCR in the larger cohort (p<0.05 and p<0.01, respectively). We detected decreased expression of RARG and NR4A2 mRNAs in females with schizophrenia (p<0.05). The mRNA levels of NR4A1, NR4A2 and NR4A3 were all negative correlated with lifetime estimates of antipsychotic exposure. These novel findings, which may be influenced by antipsychotic drug exposure, implicate the orphan and retinoid nuclear receptors in the cortical pathology found in schizophrenia. Genes down stream of these receptors can be dysregulated as well, but the direction of change is not immediately predictable based on the putative transcription factor changes.

Peripheral blood mRNA expressions of stress biomarkers in manic episode and subsequent remission

Theoretical models of the neuroprogressive nature of bipolar disorder (BD) are based on the hypothesis that it is an accelerated aging disease, with the allostatic load playing a major role. Glucocorticoids, oxidative stress markers, inflammatory cytokines and neurotrophins play important roles in BD. The messenger ribonucleic acid (mRNA) expressions of brain-derived neurotrophic factor (BDNF), tissue plasminogen activator (tPA), glucocorticoid receptor (GR), heat shock protein 70 (HSP70), tumour necrosis factor-alpha (TNF-α) were examined in the peripheral blood of 20 adult male, drug-free BD patients during manic and remission periods and in 20 adult male, healthy controls. mRNA expression was measured using the quantitative real-time polymerase chain reaction (qRT-PCR). Compared to the controls, the expressions of BDNF and tPA mRNA were down-regulated in mania. In remission, BNDF and tPA mRNA levels increased, but they were still lower than those of the controls. Between mania and remission periods, only the change in mRNA levels of BDNF reached statistical significance. The results suggest that BDNF and tPA may be biomarkers of BD and that proteolytic conversion of BDNF may be important in the pathophysiology of BD. The change in BDNF levels between mania and remission could be adaptive and used to follow the progression of BD.

Neurodevelopmental origins of bipolar disorder: iPSC models

Bipolar disorder (BP) is a chronic neuropsychiatric condition characterized by pathological fluctuations in mood from mania to depression. Adoption, twin and family studies have consistently identified a significant hereditary component to BP, yet there is no clear genetic event or consistent neuropathology. BP has been suggested to have a developmental origin, although this hypothesis has been difficult to test since there are no viable neurons or glial cells to analyze, and research has relied largely on postmortem brain, behavioral and imaging studies, or has examined proxy tissues including saliva, olfactory epithelium and blood cells. Neurodevelopmental factors, particularly pathways related to nervous system development, cell migration, extracellular matrix, H3K4 methylation, and calcium signaling have been identified in large gene expression and GWAS studies as altered in BP. Recent advances in stem cell biology, particularly the ability to reprogram adult somatic tissues to a pluripotent state, now make it possible to interrogate these pathways in viable cell models. A number of induced pluripotent stem cell (iPSC) lines from BP patient and healthy control (C) individuals have been derived in several laboratories, and their ability to form cortical neurons examined. Early studies suggest differences in activity, calcium signaling, blocks to neuronal differentiation, and changes in neuronal, and possibly glial, lineage specification. Initial observations suggest that differentiation of BP patient-derived neurons to dorsal telencephalic derivatives may be impaired, possibly due to alterations in WNT, Hedgehog or Nodal pathway signaling. These investigations strongly support a developmental contribution to BP and identify novel pathways, mechanisms and opportunities for improved treatments.

Dissection of glucocorticoid receptor-mediated inhibition of the hypothalamic-pituitary-adrenal axis by gene targeting in mice

Negative feedback regulation of glucocorticoid (GC) synthesis and secretion occurs through the function of glucocorticoid receptor (GR) at sites in the hypothalamic-pituitary-adrenal (HPA) axis, as well as in brain regions such as the hippocampus, prefrontal cortex, and sympathetic nervous system. This function of GRs in negative feedback coordinates basal glucocorticoid secretion and stress-induced increases in secretion that integrate GC production with the magnitude and duration of the stressor. This review describes the effects of GR loss along major sites of negative feedback including the entire brain, the paraventricular nucleus of the hypothalamus (PVN), and the pituitary. In genetic mouse models, we evaluate circadian regulation of the HPA axis, stress-stimulated neuroendocrine response and behavioral activity, as well as the integrated response of organism metabolism. Our analysis provides information on contributions of region-specific GR-mediated negative feedback to provide insight in understanding HPA axis dysregulation and the pathogenesis of psychiatric and metabolic disorders.

Toward the identification of peripheral epigenetic biomarkers of schizophrenia

Schizophrenia (SZ) is a heritable, nonmendelian, neurodevelopmental disorder in which epigenetic dysregulation of the brain genome plays a fundamental role in mediating the clinical manifestations and course of the disease. The authors recently reported that two enzymes that belong to the dynamic DNA methylation/demethylation network-DNMT (DNA methyltransferase) and TET (ten-eleven translocase; 5-hydroxycytosine translocator)-are abnormally increased in corticolimbic structures of SZ postmortem brain, suggesting a causal relationship between clinical manifestations of SZ and changes in DNA methylation and in the expression of SZ candidate genes (e.g., brain-derived neurotrophic factor [BDNF], glucocorticoid receptor [GCR], glutamic acid decarboxylase 67 [GAD67], reelin). Because the clinical manifestations of SZ typically begin with a prodrome followed by a first episode in adolescence with subsequent deterioration, it is obvious that the natural history of this disease cannot be studied only in postmortem brain. Hence, the focus is currently shifting towards the feasibility of studying epigenetic molecular signatures of SZ in blood cells. Initial studies show a significant enrichment of epigenetic changes in lymphocytes in gene networks directly relevant to psychiatric disorders. Furthermore, the expression of DNA-methylating/demethylating enzymes and SZ candidate genes such as BDNF and GCR are altered in the same direction in both brain and blood lymphocytes. The coincidence of these changes in lymphocytes and brain supports the hypothesis that common environmental or genetic risk factors are operative in altering the epigenetic components involved in orchestrating transcription of specific genes in brain and peripheral tissues. The identification of DNA methylation signatures for SZ in peripheral blood cells of subjects with genetic and clinical high risk would clearly have potential for the diagnosis of SZ early in its course and would be invaluable for initiating early intervention and individualized treatment plans.

Markers of inflammation and stress distinguish subsets of individuals with schizophrenia and bipolar disorder

Schizophrenia and bipolar disorder share a number of common features, both symptomatically and biologically. Abnormalities in the neuroimmune and the stress-signaling pathways have been previously identified in brains of individuals with both diseases. However, the possible relationship between abnormalities in stress and neuroimmune signaling within the cortex of people with psychotic illness has not been defined. To test the hypothesis that combined alterations in brain stress responsiveness and neuroimmune/inflammatory status are characteristic of some individuals suffering from major mental illness, we examined gene expression in the Stanley Array Cohort of 35 controls, 35 individuals with schizophrenia and 34 individuals with bipolar disorder. We used levels of 8 inflammatory-related transcripts, of which SERPINA3 was significantly elevated in individuals with schizophrenia (F(2,88)=4.137, P<0.05), and 12 glucocorticoid receptor signaling (stress) pathway transcripts previously examined, to identify two clusters of individuals: a high inflammation/stress group (n=32) and a low (n=68) inflammation/stress group. The high inflammation/stress group has a significantly greater number of individuals with schizophrenia (n=15), and a trend toward having more bipolar disorder individuals (n=11), when compared with controls (n=6). Using these subgroups, we tested which microarray-assessed transcriptional changes may be associated with high inflammatory/stress groups using ingenuity analysis and found that an extended network of gene expression changes involving immune, growth factors, inhibitory signaling and cell death factors also distinguished these groups. Our work demonstrates that some of the heterogeneity in schizophrenia and bipolar disorder may be partially explained by inflammation/stress interactions, and that this biological subtype cuts across Diagnostic and Statistical Manual of Mental Disorders (DSM)-defined categories.

Stress, glucocorticoid receptors, and adult neurogenesis: a balance between excitation and inhibition?

Adult neurogenesis, the birth of new neurons in the mature brain, has attracted considerable attention in the last decade. One of the earliest identified and most profound factors that affect adult neurogenesis both positively and negatively is stress. Here, we review the complex interplay between stress and adult neurogenesis. In particular, we review the role of the glucocorticoid receptor, the main mediator of the stress response in the proliferation, differentiation, migration, and functional integration of newborn neurons in the hippocampus. We review a multitude of mechanisms regulating glucocorticoid receptor activity in relationship to adult neurogenesis. We postulate a novel concept in which the level of glucocorticoid receptor expression directly regulates the excitation-inhibition balance, which is key for proper neurogenesis. We furthermore argue that an excitation-inhibition dis-balance may underlie aberrant functional integration of newborn neurons that is associated with psychiatric and paroxysmal brain disorders.

Neuropathology of stress

Environmental challenges are part of daily life for any individual. In fact, stress appears to be increasingly present in our modern, and demanding, industrialized society. Virtually every aspect of our body and brain can be influenced by stress and although its effects are partly mediated by powerful corticosteroid hormones that target the nervous system, relatively little is known about when, and how, the effects of stress shift from being beneficial and protective to becoming deleterious. Decades of stress research have provided valuable insights into whether stress can directly induce dysfunction and/or pathological alterations, which elements of stress exposure are responsible, and which structural substrates are involved. Using a broad definition of pathology, we here review the "neuropathology of stress" and focus on structural consequences of stress exposure for different regions of the rodent, primate and human brain. We discuss cytoarchitectural, neuropathological and structural plasticity measures as well as more recent neuroimaging techniques that allow direct monitoring of the spatiotemporal effects of stress and the role of different CNS structures in the regulation of the hypothalamic-pituitary-adrenal axis in human brain. We focus on the hypothalamus, hippocampus, amygdala, nucleus accumbens, prefrontal and orbitofrontal cortex, key brain regions that not only modulate emotions and cognition but also the response to stress itself, and discuss disorders like depression, post-traumatic stress disorder, Cushing syndrome and dementia.

Dysregulation of glucocorticoid receptor co-factors FKBP5, BAG1 and PTGES3 in prefrontal cortex in psychotic illness

Molecular abnormalities within the glucocorticoid receptor (GR) stress signaling pathway may confer, or reflect, susceptibility to stress in schizophrenia and bipolar disorder, but the extent of such abnormalities in the brain is not known. Using RNA-Seq and qPCR in two postmortem cohorts totaling 55 schizophrenia, 34 bipolar disorder and 55 control individuals, we identified increased FKBP5 and PTGES3 mRNA expression, and decreased BAG1 mRNA expression, in the prefrontal cortex in schizophrenia cases relative to controls (68.0% [p < 0.001], 26.0% [p < 0.01] and 12.1% [p < 0.05] respectively). We also observed increased FKBP5 and decreased BAG1 mRNA expression in bipolar disorder (47.5% [p < 0.05] and 14.9% [p < 0.005]). There were no diagnostic differences in steady-state FKBP51 protein levels, nor in HSPA1A, HSP90AA1, DNAJB1 or HSPB1 mRNA levels. GR, co-factor and chaperone mRNA levels were strongly correlated. These results reveal coordinated cortical dysregulation of FKBP5, PTGES3, BAG1 and GR genes within the glucocorticoid signaling pathway in psychotic illness.

DNA-methylation gene network dysregulation in peripheral blood lymphocytes of schizophrenia patients

The epigenetic dysregulation of the brain genome associated with the clinical manifestations of schizophrenia (SZ) includes altered DNA promoter methylation of several candidate genes. We and others have reported that two enzymes that belong to the DNA-methylation/demethylation network pathways-DNMT1 (DNA-methyltransferase) and ten-eleven translocator-1(TET1) methylcytosine deoxygenase are abnormally increased in corticolimbic structures of SZ postmortem brain. The objective of this study was to investigate whether the expression of these components of the DNA-methylation-demethylation pathways known to be altered in the brain of SZ patients are also altered in peripheral blood lymphocytes (PBL). The data show that increases in DNMT1 and TET1 and in glucocorticoid receptor (GCortR) and brain derived neurotrophic factor (BDNF) mRNAs in PBL of SZ patients are comparable to those reported in the brain of SZ patients. The finding that the expressions of DNMT1 and TET1 are increased and SZ candidate genes such as BDNF and GCortR are altered in the same direction in both the brain and PBL together with recent studies showing highly correlated patterns of DNA methylation across the brain and blood, support the hypothesis that a common epigenetic dysregulation may be operative in the brain and peripheral tissues of SZ patients.

DNA modifications and neurological disorders

Mounting evidence has recently underscored the importance of DNA methylation in normal brain functions. DNA methylation machineries are responsible for dynamic regulation of methylation patterns in discrete brain regions. In addition to methylation of cytosines in genomic DNA (5-methylcytosine; 5mC), other forms of modified cytosines, such as 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine, can potentially act as epigenetic marks that regulate gene expression. Importantly, epigenetic modifications require cognate binding proteins to read and translate information into gene expression regulation. Abnormal or incorrect interpretation of DNA methylation patterns can cause devastating consequences, including mental illnesses and neurological disorders. Although DNA methylation was generally considered to be a stable epigenetic mark in post-mitotic cells, recent studies have revealed dynamic DNA modifications in neurons. Such reversibility of 5mC sheds light on potential mechanisms underlying some neurological disorders and suggests a new route to correct aberrant methylation patterns associated with these disorders.

The biology of the glucocorticoid receptor: new signaling mechanisms in health and disease

Glucocorticoids are primary stress hormones necessary for life that regulate numerous physiologic processes in an effort to maintain homeostasis. Synthetic derivatives of these hormones have been mainstays in the clinic for treating inflammatory diseases, autoimmune disorders, and hematologic cancers. The physiologic and pharmacologic actions of glucocorticoids are mediated by the glucocorticoid receptor (GR), a member of the nuclear receptor superfamily of ligand-dependent transcription factors. Ligand-occupied GR induces or represses the transcription of thousands of genes through direct binding to DNA response elements, physically associating with other transcription factors, or both. The traditional view that glucocorticoids act through a single GR protein has changed dramatically with the discovery of a large cohort of receptor isoforms with unique expression, gene-regulatory, and functional profiles. These GR subtypes are derived from a single gene by means of alternative splicing and alternative translation initiation mechanisms. Posttranslational modification of these GR isoforms further expands the diversity of glucocorticoid responses. Here we discuss the origin and molecular properties of the GR isoforms and their contribution to the specificity and sensitivity of glucocorticoid signaling in healthy and diseased tissues.

Neuropathological changes in the nucleus basalis in schizophrenia

The nucleus basalis has not been examined in detail in severe mental illness. Several studies have demonstrated decreases in glia and glial markers in the cerebral cortex in schizophrenia, familial bipolar disorder and recurrent depression. Changes in neocortical neuron size and shape have also been reported. The nucleus basalis is a collection of large cholinergic neurons in the basal forebrain receiving information from the midbrain and limbic system, projecting to the cortex and involved with attention, learning and memory, and receives regulation from serotonergic inputs. Forty-one cases aged 41-60 years with schizophrenia or major depressive disorder with age-matched controls were collected. Formalin-fixed paraffin-embedded coronal nucleus basalis sections were histologically stained for oligodendrocyte identification with cresyl-haematoxylin counterstain, for neuroarchitecture with differentiated cresyl violet stain and astrocytes were detected by glial fibrillary acid protein immunohistochemistry. Cell density and neuroarchitecture were measured using Image Pro Plus. There were larger NB oval neuron soma in the combined schizophrenia and major depression disorder groups (p = 0.038), with no significant change between controls and schizophrenia and major depression disorder separately. There is a significant reduction in oligodendrocyte density (p = 0.038) in the nucleus basalis in schizophrenia. The ratio of gemistocytic to fibrillary astrocytes showed a greater proportion of the former in schizophrenia (18.1 %) and major depressive disorder (39.9 %) than in controls (7.9 %). These results suggest glial cell abnormalities in the nucleus basalis in schizophrenia possibly leading to cortical-limbic disturbance and subcortical dysfunction.

Distribution of the glucocorticoid receptor in the human amygdala; changes in mood disorder patients

Exposure to stress activates the hypothalamic-pituitary-adrenal (HPA) axis that stimulates glucocorticoid (GC) release from the adrenal. These hormones exert numerous effects in the body and brain and bind to a.o. glucocorticoid receptors (GR) expressed in the limbic system, including the hippocampus and amygdala. Hyperactivity of the HPA axis and disturbed stress feedback are common features in major depression. GR protein is present in the human hypothalamus and hippocampus, but little is known-neither in healthy subjects nor in depressed patients-about GR expression in the amygdala, a brain structure involved in fear and anxiety. Since chronic stress in rodents affects GR expression in the amygdala, altered GR protein level in depressed versus healthy controls can be expected. To test this, we investigated GR-α protein expression in the post-mortem human amygdala and assessed changes in ten major or bipolar depressed patients and eight non-depressed controls. Abundant GR immunoreactivity was observed in the human amygdala, both in neurons and astrocytes, with a similar pattern in its different anatomical subnuclei. In major depression, GR protein level as well as the percentage of GR-containing astrocytes was significantly higher than in bipolar depressed patients or in control subjects. Taken together, the prominent expression of GR protein in the human amygdala indicates that this region can form an important target for corticosteroids and stress, while the increased GR expression in major, but not bipolar, depression suggests possible involvement in the etiology of major depression.

Glucocorticoid receptor mRNA and protein isoform alterations in the orbitofrontal cortex in schizophrenia and bipolar disorder

BACKGROUND

The orbitofrontal cortex (OFC) may play a role in the pathogenesis of psychiatric illnesses such as bipolar disorder and schizophrenia, in which hypothalamic-pituitary-adrenal (HPA) axis abnormalities are observed and stress has been implicated. A critical component of the HPA axis which mediates cellular stress responses in the OFC, and has been implicated in psychiatric illness, is the glucocorticoid receptor (GR).

METHODS

In the lateral OFC, we employed quantitative real-time PCR and western blotting to investigate GR mRNA and protein expression in 34 bipolar disorder cases, 35 schizophrenia cases and 35 controls. Genotype data for eleven GR gene (NR3C1) polymorphisms was also used to explore possible effects of NR3C1 sequence variation on GR mRNA and protein expression in the lateral OFC.

RESULTS

We found no diagnostic differences in pan GR, GR-1C or GR-1F mRNA expression. However, the GR-1B mRNA transcript variant was decreased (14.3%) in bipolar disorder cases relative to controls (p < 0.05), while GR-1H mRNA was decreased (22.0%) in schizophrenia cases relative to controls (p < 0.005). By western blotting, there were significant increases in abundance of a truncated GRα isoform, putative GRα-D1, in bipolar disorder (56.1%, p < 0.005) and schizophrenia (31.5% p < 0.05). Using genotype data for eleven NR3C1 polymorphisms, we found no evidence of effects of NR3C1 genotype on GR mRNA or GRα protein expression in the OFC.

CONCLUSIONS

These findings reveal selective abnormalities of GR mRNA expression in the lateral OFC in psychiatric illness, which are more specific and may be less influenced by NR3C1 genotype than those of the dorsolateral prefrontal cortex reported previously. Our results suggest that the GRα-D1 protein isoform may be up-regulated widely across the frontal cortex in psychiatric illness.

Effects of environmental manipulations in genetically targeted animal models of affective disorders

Mental illness is the leading cause of disability worldwide. We are only just beginning to reveal and comprehend the complex interaction that exists between the genetic makeup of an organism and the potential modifying effect of the environment in which it lives, and how this translates into mediating susceptibility to neurological and psychiatric conditions. The capacity to address this issue experimentally has been facilitated by the availability of rodent models which allow the precise manipulation of genetic and environmental factors. In this review, we discuss the valuable nature of animal models in furthering our understanding of the relationship between genetic and environmental factors in affective illnesses, such as anxiety and depressive disorders. We first highlight the behavioral impairments exhibited by genetically targeted animal models of affective disorders, and then provide a discussion of the underlying neurobiology, focusing on animal models that involve exposure to stress. This is followed by a review of recent studies that report of beneficial effects of environmental manipulations such as environmental enrichment and enhanced physical activity and discuss the likely mechanisms that mediate those benefits.

Glucocorticoid receptor 1B and 1C mRNA transcript alterations in schizophrenia and bipolar disorder, and their possible regulation by GR gene variants

Abnormal patterns of HPA axis activation, under basal conditions and in response to stress, are found in individuals with schizophrenia and bipolar disorder. Altered glucocorticoid receptor (GR) mRNA and protein expression in the dorsolateral prefrontal cortex (DLPFC) in psychiatric illness have also been reported, but the cause of these abnormalities is not known. We quantified expression of GR mRNA transcript variants which employ different 5′ promoters, in 35 schizophrenia cases, 31 bipolar disorder cases and 34 controls. We also explored whether sequence variation within the NR3C1 (GR) gene is related to GR mRNA variant expression. Total GR mRNA was decreased in the DLPFC in schizophrenia cases relative to controls (15.1%, p<0.0005) and also relative to bipolar disorder cases (8.9%, p<0.05). GR-1B mRNA was decreased in schizophrenia cases relative to controls (20.2%, p<0.05), while GR-1C mRNA was decreased in both schizophrenia and bipolar disorder cases relative to controls (16.1% and 17.2% respectively, both p<0.005). A dose-dependent effect of rs10052957 genotype on GR-1B mRNA expression was observed, where CC homozygotes displayed 18.4% lower expression than TC heterozygotes (p<0.05), and 31.8% lower expression than TT homozygotes (p<0.005). Similarly, a relationship between rs6190 (R23K) genotype and GR-1C expression was seen, with 24.8% lower expression in GG homozygotes than GA heterozygotes (p<0.01). We also observed an effect of rs41423247 (Bcl1) SNP on expression of 67 kDa GRα isoform, the most abundant GRα isoform in the DLPFC. These findings suggest possible roles for the GR-1B and GR-1C promoter regions in mediating GR gene expression changes in psychotic illness, and highlight the potential importance of sequence variation within the NR3C1 gene in modulating GR mRNA expression in the DLPFC.