POS0715 QUANTIFYING THE PSYCHOSOCIAL IMPACT OF UNDIFFERENTIATED CONNECTIVE TISSUE DISEASE (UCTD)

Background:

Only half of patients diagnosed with SLE fulfill classification criteria; the rest have “SLE-like” illnesses such as UCTD. SLE patients are known to experience impaired health-related quality of life (HRQoL) and significant anxiety, depression, and fatigue,1 yet the psychosocial aspects of UCTD are less established. In a qualitative study, we found that most UCTD patients had engaged in psychotherapy and felt additional support was needed.2

Objectives:

Using multiple validated instruments, this study aims to quantify the psychosocial impact of UCTD.

Methods:

The Hospital for Special Surgery UCTD and Overlap Registry includes UCTD patients aged ≥ 18 years with ANA ≥ 1:80 and ≥ 1 sign or symptom of rheumatic disease who do not fulfill classification criteria for a defined CTD. We administered the 36-Item Short Form Health Survey (SF-36), General Anxiety Disorder-7 (GAD-7), Beck Depression Inventory (BDI), and Fatigue Severity Scale (FSS) to all patients to assess HRQoL, anxiety, depression, and fatigue. Instruments were scored based on established algorithms and results were summarized using predefined scales and severity thresholds.

Results:

The composite questionnaire was administered to 85 UCTD patients and completed by 75 (97.3% female, 60% white, mean age ± SD 48.8 ± 13.6 years). The SF-36 Physical Component Summary mean score was 37.8 and Mental Component Summary mean score was 41.1. Across the 8 SF-36 subscales, mean scores were lowest for role limitations due to physical health (39.3) and vitality (39.7) and highest for physical functioning (67.2), role limitations due to emotional health (67.1), and mental health (67.1). Approximately half of UCTD patients reported anxiety (GAD-7 ≥ 6); 20% had moderate/severe anxiety (GAD-7 ≥ 10). The prevalence of depression (BDI ≥ 14) was 26.7%; 13.3% had moderate/severe depression (BDI ≥ 20). Fatigue (FSS ≥ 3) was reported by 82.8% of patients (median FSS score of 4.7) [Table 1].

Table 1.

Psychosocial Survey Scores of Patients with Undifferentiated Connective Tissue Disease (n=75)

36-Item Short Form Health Survey (SF-36)Range 1-100 – Mean (SD)*Physical Component Summary∘Physical functioning∘Role-Physical∘Bodily PainoGeneral Health38.2 (11.2)67.2 (26.3)39.3 (46.3)49.5 (22.1)42.9 (21.5)Mental Component Summary∘Vitality∘Social Functioning∘Role-EmotionaloMental Health41.3 (10.7)39.7 (21.7)59.3 (25.9)67.1 (41.9)67.1 (18.3)Generalized Anxiety Disorder-7 (GAD-7)Range 0-21 – N (%)**None [0-5]Mild [6-10]Moderate [11-15]Severe [16-21]38 (50.7)22 (29.3)14 (18.7)1 (1.3)Beck Depression Inventory (BDI)Range 0-63 – N (%)**Minimal [0-13]Mild [14-19]Moderate [20-28]Severe [29-63]55 (73.3)10 (13.3)7 (9.3)3 (4.0)Fatigue Severity Scale (FSS) Range 1-7 – Median (IQR)**4.7 (1.5)

*Higher number indicates better health state. **Higher number indicates greater severity.

Conclusion:

UCTD patients have significantly impaired HRQoL and a high prevalence of anxiety, depression, and fatigue, suggesting substantial psychosocial impact of UCTD comparable to that reported in SLE.3,4 Impaired HRQoL in UCTD is driven to similar degrees by aspects of physical and mental health. In future studies, we will compare age- and sex- matched UCTD to SLE patients and longitudinally evaluate psychosocial metrics alongside clinical trajectories.

References:

[1]Dietz B, Katz P, Dall’Era M, et al. Major depression and adverse patient-reported outcomes in systemic lupus erythematosus: Results from a prospective longitudinal cohort. Arthritis Care Res. 2021;73(1):48-54.

[2]Siegel CH, Kleinman J, Barbhaiya M, et al. The psychosocial impact of undifferentiated connective tissue disease on patient health and well-being: A qualitative study. J Clin Rheumatol. In press.

[3]Gu M, Cheng Q, Wang X, et al. The impact of SLE on health-related quality of life assessed with SF-36: A systemic review and meta-analysis. Lupus. 2019;28(3):371-382.

[4]Zhang L, Fu T, Yin R, Zhang Q, Shen B. Prevalence of depression and anxiety in systemic lupus erythematosus: A systematic review and meta-analysis. BMC Psychiatry. 2017;17(1).

Acknowledgements:

This project was supported by the Barbara Volcker Center for Women and Rheumatic Diseases and the Robin J. Sillau Memorial Research Fund for Connective Tissue Disease. Dr. Barbhaiya is supported by the Rheumatology Research Foundation Investigator Award.

Disclosure of Interests:

None declared

Genetic vulnerability to DUSP22 promoter hypermethylation is involved in the relation between in utero famine exposure and schizophrenia

Epigenetic changes may account for the doubled risk to develop schizophrenia in individuals exposed to famine in utero. We therefore investigated DNA methylation in a unique sample of patients and healthy individuals conceived during the great famine in China. Subsequently, we examined two case-control samples without famine exposure in whole blood and brain tissue. To shed light on the causality of the relation between famine exposure and DNA methylation, we exposed human fibroblasts to nutritional deprivation. In the famine-exposed schizophrenia patients, we found significant hypermethylation of the dual specificity phosphatase 22 (DUSP22) gene promoter (Chr6:291687-293285) (N = 153, p = 0.01). In this sample, DUSP22 methylation was also significantly higher in patients independent of famine exposure (p = 0.025), suggesting that hypermethylation of DUSP22 is also more generally involved in schizophrenia risk. Similarly, DUSP22 methylation was also higher in two separate case-control samples not exposed to famine using DNA from whole blood (N = 64, p = 0.03) and postmortem brains (N = 214, p = 0.007). DUSP22 methylation showed strong genetic regulation across chromosomes by a region on chromosome 16 which was consistent with new 3D genome interaction data. The presence of a direct link between famine and DUSP22 transcription was supported by data from cultured human fibroblasts that showed increased methylation (p = 0.048) and expression (p = 0.019) in response to nutritional deprivation (N = 10). These results highlight an epigenetic locus that is genetically regulated across chromosomes and that is involved in the response to early-life exposure to famine and that is relevant for a major psychiatric disorder.

Longitudinal analyses of the DNA methylome in deployed military servicemen identify susceptibility loci for post-traumatic stress disorder

In order to determine the impact of the epigenetic response to traumatic stress on post-traumatic stress disorder (PTSD), this study examined longitudinal changes of genome-wide blood DNA methylation profiles in relation to the development of PTSD symptoms in two prospective military cohorts (one discovery and one replication data set). In the first cohort consisting of male Dutch military servicemen (n=93), the emergence of PTSD symptoms over a deployment period to a combat zone was significantly associated with alterations in DNA methylation levels at 17 genomic positions and 12 genomic regions. Evidence for mediation of the relation between combat trauma and PTSD symptoms by longitudinal changes in DNA methylation was observed at several positions and regions. Bioinformatic analyses of the reported associations identified significant enrichment in several pathways relevant for symptoms of PTSD. Targeted analyses of the significant findings from the discovery sample in an independent prospective cohort of male US marines (n=98) replicated the observed relation between decreases in DNA methylation levels and PTSD symptoms at genomic regions in ZFP57, RNF39 and HIST1H2APS2. Together, our study pinpoints three novel genomic regions where longitudinal decreases in DNA methylation across the period of exposure to combat trauma marks susceptibility for PTSD.

Altered expression of histamine signaling genes in autism spectrum disorder

The histaminergic system (HS) has a critical role in cognition, sleep and other behaviors. Although not well studied in autism spectrum disorder (ASD), the HS is implicated in many neurological disorders, some of which share comorbidity with ASD, including Tourette syndrome (TS). Preliminary studies suggest that antagonism of histamine receptors 1-3 reduces symptoms and specific behaviors in ASD patients and relevant animal models. In addition, the HS mediates neuroinflammation, which may be heightened in ASD. Together, this suggests that the HS may also be altered in ASD. Using RNA sequencing (RNA-seq), we investigated genome-wide expression, as well as a focused gene set analysis of key HS genes (HDC, HNMT, HRH1, HRH2, HRH3 and HRH4) in postmortem dorsolateral prefrontal cortex (DLPFC) initially in 13 subjects with ASD and 39 matched controls. At the genome level, eight transcripts were differentially expressed (false discovery rate <0.05), six of which were small nucleolar RNAs (snoRNAs). There was no significant diagnosis effect on any of the individual HS genes but expression of the gene set of HNMT, HRH1, HRH2 and HRH3 was significantly altered. Curated HS gene sets were also significantly differentially expressed. Differential expression analysis of these gene sets in an independent RNA-seq ASD data set from DLPFC of 47 additional subjects confirmed these findings. Understanding the physiological relevance of an altered HS may suggest new therapeutic options for the treatment of ASD.

Obesity and age-related alterations in the gene expression of zinc-transporter proteins in the human brain

The incidence of Alzheimer's disease (AD) is increasing. Major risk factors for AD are advancing age and diabetes. Lately, obesity has been associated with an increased risk of dementia. Obese and diabetic individuals are prone to decreased circulating levels of zinc, reducing the amount of zinc available for crucial intracellular processes. In the brain, zinc co-localizes with glutamate in synaptic vesicles, and modulates NMDA receptor activity. Intracellular zinc is involved in apoptosis and fluctuations in cytoplasmic Zn(2+) affect modulation of intracellular signaling. The ZNT and ZIP proteins participate in intracellular zinc homeostasis. Altered expression of zinc-regulatory proteins has been described in AD patients. Using microarray data from human frontal cortex (BrainCloud), this study investigates expression of the SCLA30A (ZNT) and SCLA39A (ZIP) families of genes in a Caucasian and African-American sample of 145 neurologically and psychiatrically normal individuals. Expression of ZNT3 and ZNT4 were significantly reduced with increasing age, whereas expression of ZIP1, ZIP9 and ZIP13 were significantly increased. Increasing body mass index (BMI) correlated with a significant reduction in ZNT1 expression similar to what is seen in the early stages of AD. Increasing BMI also correlated with reduced expression of ZNT6. In conclusion, we found that the expression of genes that regulate intracellular zinc homeostasis in the human frontal cortex is altered with increasing age and affected by increasing BMI. With the increasing rates of obesity throughout the world, these findings warrant continuous scrutiny of the long-term consequences of obesity on brain function and the development of neurodegenerative diseases.

DEGS2 polymorphism associated with cognition in schizophrenia is associated with gene expression in brain

A genome-wide association study of cognitive deficits in patients with schizophrenia in Japan found association with a missense genetic variant (rs7157599, Asn8Ser) in the delta(4)-desaturase, sphingolipid 2 (DEGS2) gene. A replication analysis using Caucasian samples showed a directionally consistent trend for cognitive association of a proxy single-nucleotide polymorphism (SNP), rs3783332. Although the DEGS2 gene is expressed in human brain, it is unknown how DEGS2 expression varies during human life and whether it is affected by psychiatric disorders and genetic variants. To address these questions, we examined DEGS2 messenger RNA using next-generation sequencing in postmortem dorsolateral prefrontal cortical tissue from a total of 418 Caucasian samples including patients with schizophrenia, bipolar disorder and major depressive disorder. DEGS2 is expressed at very low levels prenatally and increases gradually from birth to adolescence and consistently expressed across adulthood. Rs3783332 genotype was significantly associated with the expression across all subjects (F3,348=10.79, P=1.12 × 10(-)(3)), particularly in control subjects (F1,87=13.14, P=4.86 × 10(-4)). Similar results were found with rs715799 genotype. The carriers of the risk-associated minor allele at both loci showed significantly lower expression compared with subjects homozygous for the non-risk major allele and this was a consistent finding across all diagnostic groups. DEGS2 expression showed no association with diagnostic status after correcting for multiple testing (P>0.05). Our findings demonstrate that a SNP showing genome-wide association study significant association with cognition in schizophrenia is also associated with regulation of DEGS2 expression, implicating a molecular mechanism for the clinical association.

Contrasting changes in DRD1 and DRD2 splice variant expression in schizophrenia and affective disorders, and associations with SNPs in postmortem brain

Dopamine 2 receptor (DRD2) is of major interest to the pathophysiology of schizophrenia (SCZ) both as a target for antipsychotic drug action as well as a SCZ-associated risk gene. The dopamine 1 receptor (DRD1) is thought to mediate some of the cognitive deficits in SCZ, including impairment of working memory that relies on normal dorsolateral prefrontal cortex (DLPFC) function. To better understand the association of dopamine receptors with SCZ, we studied the expression of three DRD2 splice variants and the DRD1 transcript in DLPFC, hippocampus and caudate nucleus in a large cohort of subjects (~700), including patients with SCZ, affective disorders and nonpsychiatric controls (from 14th gestational week to 85 years of age), and examined genotype-expression associations of 278 single-nucleotide polymorphisms (SNPs) located in or near DRD2 and DRD1 genes. Expression of D2S mRNA and D2S/D2-long (D2L) ratio were significantly increased in DLPFC of patients with SCZ relative to controls (P<0.0001 and P<0.0001, respectively), whereas D2L, D2Longer and DRD1 were decreased (P<0.0001). Patients with affective disorders showed an opposite pattern: reduced expression of D2S (major depressive disorder, P<0.0001) and increased expression of D2L and DRD1 (bipolar disorder, P<0.0001). Moreover, SCZ-associated risk alleles at rs1079727, rs1076560 and rs2283265 predicted increased D2S/D2L expression ratio (P<0.05) in control individuals. Our data suggest that altered splicing of DRD2 and expression of DRD1 may constitute a pathophysiological mechanism in risk for SCZ and affective disorders. The association between SCZ risk-associated polymorphism and the ratio of D2S/D2L is consistent with this possibility.

RNA-sequencing of the brain transcriptome implicates dysregulation of neuroplasticity, circadian rhythms and GTPase binding in bipolar disorder

RNA-sequencing (RNA-seq) is a powerful technique to investigate the complexity of gene expression in the human brain. We used RNA-seq to survey the brain transcriptome in high-quality postmortem dorsolateral prefrontal cortex from 11 individuals diagnosed with bipolar disorder (BD) and from 11 age- and gender-matched controls. Deep sequencing was performed, with over 350 million reads per specimen. At a false discovery rate of <5%, we detected five differentially expressed (DE) genes and 12 DE transcripts, most of which have not been previously implicated in BD. Among these, Prominin 1/CD133 and ATP-binding cassette-sub-family G-member2 (ABCG2) have important roles in neuroplasticity. We also show for the first time differential expression of long noncoding RNAs (lncRNAs) in BD. DE transcripts include those of serine/arginine-rich splicing factor 5 (SRSF5) and regulatory factor X4 (RFX4), which along with lncRNAs have a role in mammalian circadian rhythms. The DE genes were significantly enriched for several Gene Ontology categories. Of these, genes involved with GTPase binding were also enriched for BD-associated SNPs from previous genome-wide association studies, suggesting that differential expression of these genes is not simply a consequence of BD or its treatment. Many of these findings were replicated by microarray in an independent sample of 60 cases and controls. These results highlight common pathways for inherited and non-inherited influences on disease risk that may constitute good targets for novel therapies.

Genetic neuropathology of obsessive psychiatric syndromes

Anorexia nervosa (AN), bulimia nervosa (BN) and obsessive-compulsive disorder (OCD) are complex psychiatric disorders with shared obsessive features, thought to arise from the interaction of multiple genes of small effect with environmental factors. Potential candidate genes for AN, BN and OCD have been identified through clinical association and neuroimaging studies; however, recent genome-wide association studies of eating disorders (ED) so far have failed to report significant findings. In addition, few, if any, studies have interrogated postmortem brain tissue for evidence of expression quantitative trait loci (eQTLs) associated with candidate genes, which has particular promise as an approach to elucidating molecular mechanisms of association. We therefore selected single-nucleotide polymorphisms (SNPs) based on candidate gene studies for AN, BN and OCD from the literature, and examined the association of these SNPs with gene expression across the lifespan in prefrontal cortex of a nonpsychiatric control cohort (N=268). Several risk-predisposing SNPs were significantly associated with gene expression among control subjects. We then measured gene expression in the prefrontal cortex of cases previously diagnosed with obsessive psychiatric disorders, for example, ED (N=15) and OCD/obsessive-compulsive personality disorder or tics (OCD/OCPD/Tic; N=16), and nonpsychiatric controls (N=102) and identified 6 and 286 genes that were differentially expressed between ED compared with controls and OCD cases compared with controls, respectively (false discovery rate (FDR) <5%). However, none of the clinical risk SNPs were among the eQTLs and none were significantly associated with gene expression within the broad obsessive cohort, suggesting larger sample sizes or other brain regions may be required to identify candidate molecular mechanisms of clinical association in postmortem brain data sets.

Altered gene expression in the dorsolateral prefrontal cortex of individuals with schizophrenia

The underlying pathology of schizophrenia (SZ) is likely as heterogeneous as its symptomatology. A variety of cortical and subcortical regions, including the prefrontal cortex, have been implicated in its pathology, and a number of genes have been identified as risk factors for disease development. We used in situ hybridization (ISH) to examine the expression of 58 genes in the dorsolateral prefrontal cortex (DLPFC, comprised of Brodmann areas 9 and 46) from 19 individuals with a premorbid diagnosis of SZ and 33 control individuals. Genes were selected based on: (1) previous identification as risk factors for SZ; (2) cell type markers or (3) laminar markers. Cell density and staining intensity were compared in the DLPFC, as well as separately in Brodmann areas 9 and 46. The expression patterns of a variety of genes, many of which are associated with the GABAergic system, were altered in SZ when compared with controls. Additional genes, including C8orf79 and NR4A2, showed alterations in cell density or staining intensity between the groups, highlighting the need for additional studies. Alterations were, with only a few exceptions, limited to Brodmann area 9, suggesting regional specificity of pathology in the DLPFC. Our results agree with previous studies on the GABAergic involvement in SZ, and suggest that areas 9 and 46 may be differentially affected in the disease. This study also highlights additional genes that may be altered in SZ, and indicates that these potentially interesting genes can be identified by ISH and high-throughput image analysis techniques.

Interactions of human truncated DISC1 proteins: implications for schizophrenia

Numerous genetic linkage and association reports have implicated the Disrupted-in-Schizophrenia (DISC1) gene in psychiatric illness. The Scottish family translocation, predicted to encode a C-terminus-truncated protein, suggests involvement of short isoforms in the pathophysiology of mental disorders. We recently reported complex alternative splicing patterns for the DISC1 gene and found that short isoforms are overexpressed in the brains of patients with schizophrenia and in carriers of risk-associated alleles. Investigation into the protein-protein interactions of alternative DISC1 isoforms may provide information about the functional consequences of overexpression of truncated forms in mental illness. Human embryonic kidney (HEK293) cells were transiently co-transfected with human epitope-tagged DISC1 variants and epitope-tagged NDEL1, FEZ1, GSK3β and PDE4B constructs. Co-immunoprecipitation assays demonstrated that all truncated DISC1 variants formed complexes with full-length DISC1. Short DISC1 splice variants LΔ78, LΔ3 and Esv1 showed reduced or no binding to NDEL1 and PDE4B proteins, but fully interacted with FEZ1 and GSK3β. The temporal expression pattern of GSK3β in the human postmortem tissue across the lifespan closely resembled that of the truncated DISC1 variants, suggesting the possibility of interactions between these proteins in the human brain. Our results suggest that complexes of full-length DISC1 with truncated DISC1 variants may result in cellular disturbances critical to DISC1 function.

Promoter specific alterations of brain-derived neurotrophic factor mRNA in schizophrenia

The brain-derived neurotrophic factor (BDNF) gene contains multiple 5' promoters which generate alternate transcripts. Previously, we found that pan-BDNF mRNA and protein are reduced in the dorsolateral prefrontal cortex (DLPFC) from patients with schizophrenia. In this study, we determined which of the four most abundant and best characterized BDNF alternate transcripts, I-IX, II-IX, IV-IX, and VI-IX are altered in schizophrenia. Using a cohort from the NIMH, USA, we found that BDNF II-IX mRNA was significantly reduced in the DLPFC of patients with schizophrenia, and we replicated this finding using a second cohort from Sydney, Australia. Moreover, we show that BDNF protein expression [including prepro ( approximately 32 kDa), pro ( approximately 28 kDa) and mature ( approximately 14 kDa) BDNF] is reduced in the DLPFC of patients with schizophrenia. We next determined the regional specificity of the BDNF mRNA reduction by measuring BDNF transcripts in the parietal cortex and hippocampus and found no significant changes. The effect of antipsychotics on BDNF alternate transcript expression was also examined and we found no relationship between BDNF mRNA expression and antipsychotic use. As schizophrenic patients are often prescribed antidepressants which can up-regulate expression of BDNF, we investigated the relationship between antidepressant treatment and BDNF transcript expression. All four BDNF transcripts were significantly up-regulated in schizophrenic patients treated with antidepressants. Moreover, we found significant reductions in BDNF transcripts II-IX and IV-IX in the parietal cortex and VI-IX in the hippocampus of patients with schizophrenia who did not have a history of treatment with antidepressants. This suggests that down-regulation of at least one out of four major BDNF transcripts occurs in various brain regions of patients with schizophrenia, particularly in the DLPFC which appears to have the most robust BDNF deficit in schizophrenia.

Oestrogen receptor alpha localisation in the prefrontal cortex of three mammalian species

Oestrogen modulates cognitive function and affective behaviours subserved by the prefrontal cortex (PFC). Identifying and localising oestrogen receptor (ER)alpha, in human PFC will contribute to our understanding of the molecular mechanism of oestrogen action in this region. Inferences about the site of action of oestrogen in human brain are derived largely from studies performed in nonhuman mammalian species; however, the congruence of findings across species has not been demonstrated. Furthermore, the laminar, cellular, and subcellular localisation of ERalpha in the cortex is debated. Therefore, we compared the distribution of ERalpha in human dorsolateral prefrontal cortex (DLPFC) with that of monkey DLPFC and rat medial PFC. Immunohistochemistry performed on frontal cortex from the three species demonstrated ERalpha positive cells throughout all layers of the PFC, in pyramidal and nonpyramidal neurones, with both nuclear and cytoplasmic immunoreactivity. Western blot analyses and preabsorption studies confirmed that the antibody used recognised ERalpha and not ERbeta. A strong ERalpha immunoreactive band corresponding to the full-length ERalpha protein (65-67 kDa) in the frontal cortex of all three species matched the size of the predominant immunoreactive band detected in breast cancer cell lines known to express ERalpha. Additionally, other ERalpha immunoreactive proteins of varying molecular weight in breast cancer cells, rat ovary and mammalian brain were detected, suggesting that ERalpha may exist in more than one form in the mammalian frontal cortex. The present study provides evidence that ERalpha protein exists in neurones in mammalian PFC and that ERalpha is anatomically well-positioned to directly mediate oestrogen action in these neurones.

Allelic variation in GAD1 (GAD67) is associated with schizophrenia and influences cortical function and gene expression

Cortical GABAergic dysfunction has been implicated as a key component of the pathophysiology of schizophrenia and decreased expression of the gamma-aminobutyric acid (GABA) synthetic enzyme glutamic acid decarboxylase 67 (GAD(67)), encoded by GAD1, is found in schizophrenic post-mortem brain. We report evidence of distorted transmission of single-nucleotide polymorphism (SNP) alleles in two independent schizophrenia family-based samples. In both samples, allelic association was dependent on the gender of the affected offspring, and in the Clinical Brain Disorders Branch/National Institute of Mental Health (CBDB/NIMH) sample it was also dependent on catechol-O-methyltransferase (COMT) Val158Met genotype. Quantitative transmission disequilibrium test analyses revealed that variation in GAD1 influenced multiple domains of cognition, including declarative memory, attention and working memory. A 5' flanking SNP affecting cognition in the families was also associated in unrelated healthy individuals with inefficient BOLD functional magnetic resonance imaging activation of dorsal prefrontal cortex (PFC) during a working memory task, a physiologic phenotype associated with schizophrenia and altered cortical inhibition. In addition, a SNP in the 5' untranslated (and predicted promoter) region that also influenced cognition was associated with decreased expression of GAD1 mRNA in the PFC of schizophrenic brain. Finally, we observed evidence of statistical epistasis between two SNPs in COMT and SNPs in GAD1, suggesting a potential biological synergism leading to increased risk. These coincident results implicate GAD1 in the etiology of schizophrenia and suggest that the mechanism involves altered cortical GABA inhibitory activity, perhaps modulated by dopaminergic function.

Postnatal alterations in dopaminergic markers in the human prefrontal cortex

Dopamine in the prefrontal cortex plays a critical role in normal cognition throughout the lifespan and has been implicated in the pathophysiology of neuropsychiatric disorders such as schizophrenia and attention deficit disorder. Little is known, however, about the postnatal development of the dopaminergic system in the human prefrontal cortex. In this study, we examined pre- and post-synaptic markers of the dopaminergic system in postmortem tissue specimens from 37 individuals ranging in age from 2 months to 86 years. We measured the levels of tyrosine hydroxylase, the rate limiting enzyme in dopamine biosynthesis, using Western immunoblotting. We also examined the gene expression of the three most abundant dopamine receptors (DARs) in the human prefrontal cortex: DAR1, DAR2 and DAR4, by in situ hybridization. We found that tyrosine hydroxylase concentrations and DAR2 mRNA levels were highest in the cortex of neonates. In contrast, the gene expression of DAR1 was highest in adolescents and young adults. No significant changes across age groups were detected in mRNA levels of DAR4. Both DAR1 and DAR2 mRNA were significantly lower in the aged cortex. Taken together, our data suggest dynamic changes in markers of the dopamine system in the human frontal cortex during postnatal development at both pre-and post-synaptic sites. The peak in DAR1 mRNA levels around adolescence/early adulthood may be of particular relevance to neuropsychiatric disorders such as schizophrenia in which symptoms manifest during the same developmental period.

Catechol-o-methyltransferase enzyme activity and protein expression in human prefrontal cortex across the postnatal lifespan

The prefrontal cortex (PFC) dopamine system, which is critical for modulating PFC function, undergoes remodeling until at least young adulthood in primates. Catechol-o-methyltransferase (COMT) alters extracellular dopamine levels in PFC, and its gene contains a functional polymorphism (Val(158)Met) that has been associated with variation in PFC function. We examined COMT enzyme activity and protein immunoreactivity in the PFC during human postnatal development. Protein was extracted from PFC of normal individuals from 6 age groups: neonates (1-4 months), infants (5-11 months), teens (14-18 years), young adults (20-24 years), adults (31-43 years), and aged individuals (68-86 years; n = 5-8 per group). There was a significant 2-fold increase in COMT enzyme activity from neonate to adulthood, paralleled by increases in COMT protein immunoreactivity. Furthermore, COMT protein immunoreactivity was related to Val(158)Met genotype, as has been previously demonstrated. The significant increase in COMT activity from neonate to adulthood complements previous findings of protracted postnatal changes in the PFC dopamine system and may reflect an increasing importance of COMT for PFC dopamine regulation during maturation.

BDNF and trkB mRNA expression in the hippocampus and temporal cortex during the human lifespan

Brain-derived neurotrophic factor (BDNF) and its receptor tyrosine kinase B (trkB) influence neuronal survival, differentiation, synaptogenesis, and maintenance. Using in situ hybridization we examined the spatial and temporal expression of mRNAs encoding these proteins during diverse stages of life in the human hippocampus and inferior temporal cortex. We examined six postnatal time points: neonatal (1-3 months), infant (4-12 months), adolescent (14-18 years), young adult (20-24 years), adult (34-43 years), and aged (68-86 years). Within the hippocampus, levels of BDNF mRNA did not change significantly with age. However, levels of both the full-length form of trkB (trkB TK+) mRNA and the truncated form of trkB (trkB TK-) decreased over the life span (p < 0.05). In the temporal cortex, BDNF and trkB TK+ mRNA levels were highest in neonates and decreased with age (r = -0.4 and r = -0.7, respectively, both p < 0.05). In contrast, TrkB TK- mRNA levels remained constant across the life span in the temporal cortex. The peak in both BDNF and trkB TK+ mRNA expression in the neonate temporal cortex differs from that previously described for the frontal cortex where both mRNAs peak in expression during young adulthood. The increase in BDNF and trkB TK+ mRNA in the temporal cortex of the neonate suggests that neurotrophin signaling is important in the early development of the temporal cortex. In addition, since BDNF and both forms of its high affinity receptor are expressed throughout the development, maturation, and aging of the human hippocampus and surrounding neocortex they are likely to play roles not only in early growth but also in maintenance of neurons throughout life.

Reductions in neurotrophin receptor mRNAs in the prefrontal cortex of patients with schizophrenia

Patients with schizophrenia have reduced neurotrophin levels in their dorsolateral prefrontal cortex (DLPFC) compared to normal unaffected individuals. The tyrosine kinase-containing receptors, trkB and trkC, mediate the growth-promoting effects of neurotrophins and respond to changes in growth factor availability. We hypothesized that trkB and/or trkC expression would be altered in the DLPFC of patients with schizophrenia. We measured mRNA encoding the tyrosine kinase domain (TK+)-containing form of trkB and measured pan trkC mRNA in schizophrenics (N=14) and controls (N=15) using in situ hybridization. TrkB and trkC mRNAs were detected in large and small neurons in multiple cortical layers of the human DLPFC. We found significantly diminished expression of trkB(TK+) mRNA in large neurons in multiple cortical layers of patients as compared to controls, while small neurons also showed reductions in trkB(TK+) mRNA that did not reach statistical significance. In normals, strong positive correlations were found between trkB(TK+) mRNA levels and brain-derived neurotrophic factor (BDNF) mRNA levels among various neurons, while no correlation between BDNF and trkB(TK+) was found in patients with schizophrenia. TrkC mRNA was also reduced in the DLPFC of schizophrenics in large neurons in layers II, III, V and VI and in small neurons in layer IV. Since neurons in the DLPFC integrate and communicate signals to various cortical and subcortical regions, these reductions in growth factor receptors may compromise the function and plasticity of the DLPFC in schizophrenia.

Basic fibroblast growth factor and fibroblast growth factor receptor-1 in the human hippocampal formation

Basic fibroblast growth factor (bFGF) is an important mitogen and neurotrophic factor that binds and signals through the high-affinity receptor, fibroblast growth factor receptor 1 (FGFR1). However, only a limited amount of information is available concerning the molecular forms and anatomical distribution of fibroblast growth factors (FGFs) in the normal human brain. We found multiple bFGF and FGFR1 mRNA transcripts which vary in expression pattern across human brain regions. Using in situ hybridization and immunohistochemistry, we localized bFGF and FGFR1 mRNA and protein to cells in the normal adult human hippocampus and caudal entorhinal cortex (ERC). The majority of pyramidal neurons contained FGFR1 mRNA and protein in the mesial temporal lobe, with neurons in the CA2/CA3 region demonstrating the highest levels of FGFR1 mRNA. In contrast to FGFR1, bFGF mRNA expression was detected at very low levels in a small fraction of the neurons in the human hippocampus and caudal ERC. While bFGF mRNA may be expressed at low levels in neurons, bFGF-immunopositive cells with astrocytic features were detected throughout the mesial temporal lobe in rats, monkeys and humans. bFGF immunoreactive processes are found traversing the dentate gyrus, and bFGF immunoreactive cells are found in the neurogenic subgranular zone in all three mammalian species studied. The anatomical distribution of these two FGF family members suggests that bFGF is endogenously positioned to be involved in ongoing neurogenesis in the adult hippocampus, and that FGF trophic signaling to differentiated neurons could involve the release of astrocytic bFGF acting on neuronal FGFR1 in the normal adult human hippocampus.

Glial fibrillary acidic protein mRNA levels in the cingulate cortex of individuals with depression, bipolar disorder and schizophrenia

Recent studies have shown a decrease in glial number and glial fibrillary acidic protein (GFAP) levels in the frontal and cingulate cortices of individuals with mood disorders and schizophrenia. In an attempt to verify and expand these findings we examined GFAP messenger ribonucleic acid (mRNA) levels in postmortem sections of the anterior cingulate cortex (ACC) from the Stanley Neuropathology Consortium (SNC). The consortium consists of 15 cases in each of four groups (schizophrenia, bipolar disorder, non-psychotic depression and unaffected controls). By in situ hybridization, we found higher levels of GFAP mRNA in white matter and at the pial surface as compared with gray matter levels in all cases. In the white matter of ACC we detected a significant effect of diagnosis (P<0.04) with GFAP mRNA levels decreased in individuals with schizophrenia and bipolar disorder as compared with normal controls. In the gray matter there was a significant effect of layer (P<0.01) with the highest levels of GFAP mRNA in layer VI in all groups. As in the white matter, the mean GFAP mRNA levels were decreased in individuals with schizophrenia and bipolar disorder as compared with the unaffected controls, however the difference failed to reach statistical significance. Thus, astrocytes positive for GFAP may contribute to the decrease in glial density previously described in subjects with major mental illness, however the relative contribution of astrocytes may vary with diagnosis.

Expression of estrogen receptor alpha exon-deleted mRNA variants in the human and non-human primate frontal cortex

Although estrogen receptor alpha (ERalpha) mRNA has been detected in the primate frontal cortex, the types of ERalpha transcripts expressed, including exon-deleted variants (Delta), have not been determined in the monkey or human frontal cortex. Because the types of ERalpha mRNA expressed in brain could define neuronal responses to estrogens, we examined the transcript pool of ERalpha mRNAs expressed in normal adult and developing human and macaque frontal cortex. We reverse transcribed total RNA from the postmortem frontal cortex of 29 normal adult humans, 12 rhesus macaques, and 19 people ranging from infants to adults and employed two rounds of nested polymerase chain reaction (PCR) to generate ERalpha products spanning the coding domain. In a third nested PCR, we used primers specific for novel sequences of exon-exon junctions created when whole exons are missing. By sequencing PCR products, we detected 60 instances of 12 distinct DeltaERalpha mRNAs in adult humans and 94 instances of 13 distinct DeltaERalpha mRNAs in monkeys in differing patterns from one individual to another. In adult humans, 83% of individuals expressed at least 1 DeltaERalpha mRNA variant, and 100% of the monkeys expressed at least 1 DeltaERalpha mRNA variant. The single Delta2, Delta5, and Delta7 variants were frequently expressed in both human and monkey frontal cortex, Delta3 variants were rare in both species, and Delta6 variants were more frequently expressed in monkeys. In both species, we detected double, triple and quadruple Deltas, but these were less common than single Deltas. The pattern of human variant expression did not appear to change dramatically as a function of age. These findings imply the potential to produce different ERalpha proteins in frontal cortex, possibly with altered structure and function which may have physiological relevance for gene transcription by virtue of altered functional interactions with each other, other steroid hormone receptors, and genomic DNA.

Reduced GSK-3? mRNA levels in postmortem dorsolateral prefrontal cortex of schizophrenic patients

Glycogen Synthase Kinase (GSK)-3 is a ubiquitous serine/threonine protein kinase highly abundant in brain which plays a key role in neural development and neuron survival. We have previously reported that GSK-3beta protein levels and GSK-3 activity are reduced by over 40% in postmortem prefrontal cortex of schizophrenic patients compared to patients with bipolar illness, unipolar depression and to normal controls, and Emamian et al. have recently presented convergent evidence for impaired AKT1-GSK-3beta signaling in schizophrenia. Using specimens of dorsolateral prefrontal cortex tissue obtained from The Stanley Medical Research Institute's Brain Collection, from the same subjects used previously, we now show that GSK-3beta, but not GSK-3alpha, mRNA levels are 36% lower in the patients with schizophrenia compared to all other comparison groups. The present study lends further support to the finding of low GSK-3beta levels in schizophrenia and extends this observation by suggesting that the decrease in GSK-3beta may be due to reduced protein synthesis possibly due to altered transcriptional drive of the GSK-3beta gene.

Expression analysis of neuregulin-1 in the dorsolateral prefrontal cortex in schizophrenia

Genetic linkage and association have implicated neuregulin-1 (NRG-1) as a schizophrenia susceptibility gene. We measured mRNA expression levels of the three major isoforms of NRG-1 (ie type I, type II, and type III) in the postmortem dorsolateral prefrontal cortex (DLPFC) from matched patients and controls using real-time quantitative RT-PCR. Expression levels of three internal controls-GAPDH, cyclophilin, and beta-actin-were unchanged in schizophrenia, and there were no changes in the absolute levels of the NRG-1 isoforms. However, type I expression normalized by GAPDH levels was significantly increased in schizophrenia DLPFC (by 23%) and positively correlated with antipsychotic medication dosage. Type II/type I and type II/type III ratios were significantly decreased (18 and 23% respectively). There was no effect on the NRG-1 mRNA levels of genotype at two SNPs previously associated with schizophrenia, suggesting that these alleles are not functionally responsible for abnormal NRG-1 expression patterns in patients. Subtle abnormalities in the expression patterns of NRG-1 mRNA isoforms in DLPFC may be associated with schizophrenia.

Neuregulin-1 (NRG-1) mRNA and protein in the adult human brain

Neuregulin-1 (NRG-1) plays important roles in the development and plasticity of the brain, and it has recently been identified as a susceptibility gene for schizophrenia. Though there are rodent data, little is known about its distribution in the human brain. The aim of this study was to ascertain the localization of NRG-1 and its mRNA in multiple regions of the normal adult human brain. We investigated NRG-1 mRNA in 11 subjects using in situ hybridization and northern analysis, and NRG-1 protein in six subjects using immunohistochemistry and Western blotting. NRG-1 mRNA was present as bands of approximately 2, 3 and 6 kb. It was clearly detected in the prefrontal cortex (middle laminae), hippocampal formation (except CA1), cerebellum, oculomotor nucleus, superior colliculus, red nucleus and substantia nigra pars compacta. At the cellular level, NRG1 mRNA was abundant in hippocampal and cortical pyramidal neurons and some interneurons, and in cerebellar Purkinje cells and Golgi cells. NRG-1 protein was detected as bands of approximately 140, 110, 95 and 60 kD. Immunohistochemistry revealed NRG-1 in many cell populations, consistent with the mRNA data, being prominent in pyramidal neurons, Purkinje cells, several brainstem nuclei, and white matter neurons. Moderate NRG-1 immunoreactivity was also observed in cerebellar and dentate gyrus granule cells, and some glia. Within neurons, NRG-1 staining was primarily somatodendritic; in the cell body staining was granular, with clustering close to the plasma and nuclear membranes. There was also labeling of some fiber tracts, and local areas of neuropil (e.g. in the dentate nucleus) suggestive of a pre-synaptic location of NRG-1. The data show a widespread expression of NRG-1 in the adult human brain, including, but not limited to, brain areas and cell populations implicated in schizophrenia. Using these normative data, future studies can ascertain whether the role of NRG-1 in the disease is mediated, or accompanied, via alterations in its expression.

Presynaptic proteins in the prefrontal cortex of patients with schizophrenia and rats with abnormal prefrontal development

Dysfunction of the prefrontal cortex in schizophrenia may be associated with abnormalities in synaptic structure and/or function and reflected in altered concentrations of proteins in presynaptic terminals and involved in synaptic plasticity (synaptobrevin/ vesicle-associated membrane protein (VAMP), synaptosomal-associated protein-25 (SNAP-25), syntaxin, synaptophysin and growth-associated protein-43 (GAP-43)). We examined the immunoreactivity of these synapse-associated proteins via quantitative immunoblotting in the prefrontal cortex of patients with schizophrenia (n=18) and in normal controls (n=23). We also tested the stability of these proteins across successive post-mortem intervals in rat brains (at 0, 3, 12, 24, 48, and 70 h). To investigate whether experimental manipulation of prefrontal cortical development in the rat alters prefrontal synaptic protein levels, we lesioned the ventral hippocampus of rats on postnatal day 7 and measured immunoreactivity of presynaptic proteins in the prefrontal cortex on postnatal day 70. VAMP immunoreactivity was lower in the schizophrenic patients by 22% (P<0.03). There were no differences in the immunoreactivity of any other proteins measured in schizophrenic patients as compared to the matched controls. Proteins were fairly stable up to 24 h and thereafter the abundance of most proteins examined was significantly reduced (falling to as low as 20% of baseline levels at 48-70 h). VAMP immunoreactivity was higher in the lesioned rats as compared to sham controls by 22% (P&<0.03). There were no significant differences between the lesioned rats and sham animals in any other presynaptic protein. These data suggest that apparently profound prefrontal cortical dysfunction in schizophrenia, as well as in an animal model of schizophrenia, may exist without gross changes in the abundance of many synaptic proteins but discrete changes in selected presynaptic molecules may be present.

The use of microarrays to characterize neuropsychiatric disorders: postmortem studies of substance abuse and schizophrenia

Neuropsychiatric disorders are generally diagnosed based on a classification of behavioral and, in some cases, specific neurological deficits. The lack of distinct quantitative and qualitative biological descriptors at the anatomical and cellular level complicates the search for and understanding of the neurobiology of these disorders. The advent of microarray technology has enabled large-scale profiling of transcriptional activity, allowing a comprehensive characterization of transcriptional patterns relating to the pathophysiology of neuropsychiatric disorders. We review some of the unique methodological constraints related to the use of human postmortem brain tissue in addition to the generally applicable requirements for microarray experiments. Microarray studies undertaken in neuropsychiatric disorders such as schizophrenia and substance abuse by the use of postmortem brain tissue indicate that transcriptional changes relating to synaptic function and plasticity, cytoskeletal function, energy metabolism, oligodendrocytes, and distinct intracellular signaling pathways are generally present. These have been supported by microarray studies in experimental models, and have produced multiple avenues to be explored at the functional level. The quality and specificity of information obtained from human postmortem tissue is rapidly increasing with the maturation and refinement of array-related methodologies and analysis tools, and with the use of focused cell populations. The development of experimental models of gene regulation in these disorders will serve as the initial step towards a comprehensive genome-linked analysis of the brain and associated disorders, and help characterize the integration and coordinate regulation of complex functions within the CNS.

Catechol O-methyltransferase mRNA expression in human and rat brain: evidence for a role in cortical neuronal function

Catechol O-methyltransferase (COMT) is involved in the inactivation of catecholamines, including the neurotransmitter dopamine. A Val(108/158) Met functional polymorphism of the COMT gene has been shown to affect working memory-associated frontal lobe function in humans. In the present study, in situ hybridization histochemistry was employed to determine the mRNA expression profile of COMT in the human prefrontal cortex, striatum and midbrain and in the rat forebrain. In both species, COMT mRNA signals were observed in large pyramidal and smaller neurons in all cortical layers of the prefrontal cortex as well as in medium and large neurons in the striatum. Levels of COMT mRNA were obviously higher in neurons than in glia. The striatum, which receives a dense dopaminergic input, expressed lower levels of COMT mRNA as compared with the prefrontal cortex. Consistent with previous protein expression data, COMT mRNA was abundant in ependymal cells lining the cerebral ventricles. In the midbrain, COMT mRNA was detected in dopaminergic neurons in both species, albeit at low levels. In the rat forebrain, dense labeling was also detected in choroid plexus and hippocampal dentate gyrus and Ammon's horn neurons. Contrary to expectations that COMT would be expressed predominantly in non-neuronal cells, the present study shows that neurons are the main cell populations expressing COMT mRNA in the prefrontal cortex and striatum. Combined with previous data about protein localization, the present results suggest that the membrane-bound isoform of COMT having a high affinity for dopamine is expressed at neuronal dendritic processes in human cortex, consistent with functional evidence that it plays an important role in dopaminergic neurotransmission.

Reduced brain-derived neurotrophic factor in prefrontal cortex of patients with schizophrenia

Anatomical and molecular abnormalities of excitatory neurons in the dorsolateral prefrontal cortex (DLPFC) are found in schizophrenia. We hypothesized that brain-derived neurotrophic factor (BDNF), a protein capable of increasing pyramidal neuron spine density and augmenting synaptic efficacy of glutamate, may be abnormally expressed in the DLPFC of patients with schizophrenia. Using an RNase protection assay and Western blotting, we detected a significant reduction in BDNF mRNA (mean=23%) and protein (mean=40%) in the DLPFC of patients with schizophrenia compared to normal individuals. At the cellular level, BDNF mRNA was expressed at varying intensities in pyramidal neurons throughout layers II, III, V, and VI of DLPFC. In patients with schizophrenia; neuronal BDNF expression was decreased in layers III, V and VI. Our study demonstrates a reduction in BDNF production and availability in the DLPFC of schizophrenics, and suggests that intrinsic cortical neurons, afferent neurons, and target neurons may receive less trophic support in this disorder.

Reduction of synapsin in the hippocampus of patients with bipolar disorder and schizophrenia

Several studies suggest that decreased expression of presynaptic proteins may be characteristic of schizophrenia. We examined one such protein, synapsin, in schizophrenia and bipolar disorder. Samples of hippocampal tissue from controls (n = 13), patients with schizophrenia (n = 16), or bipolar disorder (n = 6), and suicide victims (n = 7) were used. The membrane and cytosolic fractions were analyzed by Western immunoblotting for synapsin using an antibody that detects synapsin Ia, IIa, and IIIa proteins. Synaptophysin was also measured for comparison. Total synapsin was decreased significantly in patients with schizophrenia (P = 0.034) and in bipolar disorder (P = 0.00008) as compared to controls. The synapsin/synaptophysin ratios were decreased in schizophrenia and bipolar disorder, and additionally in suicide victims (P = 0.014). Age, postmortem interval, percentage of protein extracted, and pH of brain were not different between groups. No changes in total synapsin or synaptophysin in the hippocampus were produced by injecting rats with either lithium or haloperidol for 30 days. Reductions in synapsin in both patients with schizophrenia (synapsin IIa and IIIa) and bipolar disorder (synapsin Ia, IIa and IIIa) imply that altered or reduced synaptic function in the hippocampus may be involved in these disorders.

Transcriptional profiling in the human prefrontal cortex: evidence for two activational states associated with cocaine abuse

CNS-focused cDNA microarrays were used to examine gene expression profiles in dorsolateral prefrontal cortex (dlPFC, Area 46) from seven individual sets of age- and post-mortem interval-matched male cocaine abusers and controls. The presence of cocaine and related metabolites was confirmed by gas chromatography-mass spectrometry. Sixty-five transcripts were differentially expressed, indicating alterations in energy metabolism, mitochondria and oligodendrocyte function, cytoskeleton and related signaling, and neuronal plasticity. There was evidence for two distinct states of transcriptional regulation, with increases in gene expression predominating in subjects testing positive for a metabolite indicative of recent 'crack' cocaine abuse and decreased expression profiles in the remaining cocaine subjects. This pattern was confirmed by quantitative polymerase chain reaction for select transcripts. These data suggest that cocaine abuse targets a distinct subset of genes in the dlPFC, resulting in either a state of acute activation in which increased gene expression predominates, or a relatively destimulated, refractory phase.

Comparative analysis of group II metabotropic glutamate receptor immunoreactivity in Brodmann's area 46 of the dorsolateral prefrontal cortex from patients with schizophrenia and normal subjects

Glutamate is the primary excitatory neurotransmitter in the mammalian central nervous system, and a key neurotransmitter in prefrontal cortical function. Converging lines of evidence implicate prefrontal cortical dysfunction in the neurobiology of schizophrenia. Thus, aberrant glutamate neurotransmission may underlie schizophrenia and other complex disorders of behavior. Group II metabotropic receptors (mGluRs) are important modulators of glutamatergic and non-glutamatergic neurotransmission. Moreover, in an animal model, an agonist for group II mGluRs has been shown to reverse the behavioral, locomotor, and cognitive effects of the psychotomimetic drug phencyclidine. Accordingly, group II mGluRs constitute attractive targets for the pharmacotherapeutics and study of schizophrenia. Using immunocytochemistry and Western immunoblotting, we compared the localization and levels of group II mGluRs in Brodmann's area 46 of the dorsolateral prefrontal cortex from patients with schizophrenia and normal subjects. Consistent with previous reports, we found that immunolabeling of group II mGluRs is prominent in Brodmann's area 46. The majority of labeling was present on axon terminals distributed in a lamina-specific fashion. No apparent difference in the cellular localization or laminar distribution of immunoreactive group II mGluRs was noted between the two diagnostic groups. Similarly, the levels of receptor immunoreactivity determined by quantitative Western immunoblotting were comparable between schizophrenic patients and normal subjects. We conclude that while the function of group II mGluRs in Brodmann's area 46 of dorsolateral prefrontal cortex may be altered in patients with schizophrenia, this is not evident at the level of protein expression using an antibody against mGluR2 and mGluR3.

Alterations in trkB mRNA in the human prefrontal cortex throughout the lifespan

Signalling through tyrosine kinase receptor B (trkB) influences neuronal survival, differentiation and synaptogenesis. trkB exists in a full-length form (trkB(TK+)), which contains a catalytic tyrosine kinase (TK) domain, and a truncated form (trkB(TK-)), which lacks this domain. In the rodent brain, expression of trkB(TK+) decreases and trkBTK- increases during postnatal life. We hypothesized that both forms of trkB receptor mRNA would be present in the human neocortex and that the developmental profile of trkB gene expression in human may be distinct from that in rodent. We detected both trkB(TK+) and trkB(TK-) mRNA in RNA extracted from multiple human brain regions by Northern blot. Using in situ hybridization, we found trkB(TK+) mRNA in all cortical layers, with highest expression in layer IV and intermediate-to-high expression in layers III and V of the human dorsolateral prefrontal cortex. trkB(TK+) mRNA was present in neurons with both pyramidal and nonpyramidal shapes in the dorsolateral prefrontal cortex. trkB(TK+) mRNA levels were significantly increased in layer III in young adults as compared with infants and the elderly. In the elderly, trkB(TK+) mRNA levels were reduced markedly in all cortical layers. Unlike the mRNA encoding the full-length form of trkB, trkB(TK-) mRNA was distributed homogeneously across the grey matter, and trkB(TK-) mRNA levels increased only slightly during postnatal life. The results suggest that neurons in the human dorsolateral prefrontal cortex are responsive to neurotrophins throughout postnatal life and that this responsiveness may be modulated during the human lifespan.

A comparison of verbal fluency tasks in schizophrenic patients and normal controls

Previous studies have reported significant impairment on verbal fluency tasks (semantic and letter) among schizophrenic subjects. However, the possibility of specific categorical deficits has not been adequately investigated. Nor have the effects of task duration, the stability between testing sessions, and the relationship between intelligence and performance on fluency been thoroughly studied. We performed a series of 3 min fluency tasks (semantic/syntactic and letter) to determine whether duration specific or category-specific differences exist between schizophrenic subjects and normal controls. Each subject was tested at three different times as a means of estimating word pool and assessing the stability of fluency output. Subjects were asked to generate exemplars from each of four semantic/syntactic categories (animals, tools, common nouns and verbs) and three letters (G, E and T). Data from 13 schizophrenic subjects and 15 sex-, age- and pre-morbid-IQ-matched control subjects revealed that patients' overall performance on both the semantic and letter fluency tasks was impaired. While differential impairment on specific semantic categories was noted between groups, no differential effects relating to task duration or testing session were present. Further, by comparing the number of novel words produced in the three testing sessions, we found the groups to be equivalent, a finding we take to suggest that schizophrenic patients' lexicon is intact. Covarying current IQ eliminated the group difference robustly for letter fluency, while only marginally for semantic fluency. Our data revealed the presence of impairment in semantic and letter fluency tasks in schizophrenic patients consistent with previous reports, and also that patients were differentially impaired on semantic categories.

A quantitative immunohistochemical study of astrocytes in the entorhinal cortex in schizophrenia, bipolar disorder and major depression: absence of significant astrocytosis

A number of macroscopic changes have been reported in the temporal lobe in schizophrenia. We have evaluated the density of glial fibrillary acidic protein (GFAP)-positive astrocytes in cortical layers 2 through 6 in the intermediate subarea of entorhinal cortex in two cohorts: the first, 15 cases, made up of schizophrenic (n = 7) and normal nonpsychiatric control subjects (n = 8), and the second, 56 cases, composed of schizophrenic (n = 14), bipolar disorder (n = 13), major depressive (n = 14) and normal control subjects (n = 15). No significant difference in density of GFAP-positive astrocytes was detected between the psychiatric diagnostic groups and the normal controls in either of the two cohorts. In both cohorts there was a positive correlation between increasing age and astrocytic density which reached statistical significance in only the larger cohort (r = 0.38, p = 0.004). Our results find no evidence for astrocytosis in the entorhinal cortex in several mental illnesses. Although other studies have reported macroscopic and other structural abnormalities in this region, we have not detected astrocytic proliferation, which is a typical hallmark of atrophy and/or progressive neuronal loss.

Synaptophysin and GAP-43 mRNA levels in the hippocampus of subjects with schizophrenia

Synaptophysin and growth associated protein-43 (GAP-43) are synaptic proteins colocalized to the presynaptic terminal, and involved in regulating transmitter release and synaptic plasticity. Recent studies have proposed an alteration in the number of synapses in the brains of individuals with schizophrenia. As a corollary, we hypothesized that there may be an alteration in the level of mRNAs that code for synaptic proteins in brains of patients with schizophrenia. Using in situ hybridization, we investigated the levels of synaptophysin and GAP-43 mRNA in the medial temporal lobe of 10 normal subjects, 11 subjects with schizophrenia and 10 psychiatric control subjects. Synaptophysin mRNA levels were significantly reduced in several hippocampal subfields in both the schizophrenic and psychiatric control groups. GAP-43 mRNA levels were not significantly reduced in either group. The implications of these findings are discussed in relation to neuroleptic treatment and the pathophysiology of mental illness.

Reduced GAP-43 mRNA in dorsolateral prefrontal cortex of patients with schizophrenia

Schizophrenia has been associated with anatomical and functional abnormalities of the dorsolateral prefrontal cortex (DLPFC), which may reflect abnormal connections of DLPFC neurons. We measured mRNA levels of growth-associated protein (GAP-43), a peptide linked to the modifiability of neuronal connections, in post-mortem brain tissue from two cohorts of patients with schizophrenia and controls. Using the RNase protection assay (RPA), we found a significant reduction in GAP-43 mRNA in the DLPFC, but not in the hippocampus, of patients with schizophrenia. With in situ hybridization histo- chemistry (ISHH), performed on a separate cohort, we confirmed the reduction of GAP-43 mRNA in the DLPFC of patients with schizophrenia. We detected reduced GAP-43 mRNA per neuron in layers III, V and VI of patients with schizophrenia compared with normal controls and patients with bipolar disorder. Thus, glutamate neurons in DLPFC of schizophrenic patients may synthesize less GAP-43, which could reflect fewer and/or less modifiable connections than those in normal human brain, and which may be consistent with the deficits of prefrontal cortical function that characterize schizophrenia.

Advanced theory of mind in high-functioning adults with autism

Twenty-four high-functioning adults with autism (16 men) who passed a first-order theory-of-mind task and 24 nonautistic adults (10 men) attributed mental states to recordings of various verbal intonations and to photos of people's eyes to assess advanced theory of mind. Participants with autism performed significantly worse than nonautistic participants on both tasks. Thus, the previously described inattention to others' eyes exhibited by adults with autism is not solely responsible for their inability to attribute mental states from eyes, as they also did not correctly attribute mental states from voices. These findings support the view that a core deficit for people with autism lies in their theory of mind, that is, their inability to attribute mental states to others.

Trinucleotide repeat expansion in the beta1 subunit of the sodium pump in manic-depression illness: a negative study

BACKGROUND

Trinucleotide repeats have become a recognized molecular abnormality in a variety of neuropsychiatric conditions. Bipolar illness has been purported to be a possible trinucleotide repeat-associated disease. Since abnormalities in the expression and regulation of the sodium- and potassium-activated adenosine triphosphatase (Na,K-ATPase) have been documented in bipolar patients and since the beta1 subunit of this pump contains a heterogenous GCC repeat, we decided to investigate the possibility of a repeat expansion in beta1 subunit of Na,K-ATPase in bipolar patients.

METHODS

DNA from postmortem temporal cerebral cortex tissue of five bipolar subjects and five matched normal controls and five lyumphoblastoid cells lines from the Old Order Amish bipolar pedigrees and match normal controls were used for this study. The GCC rich region of beta1 DNA was amplified by polymerase chain reaction (PCR) and sequenced.

RESULTS

The range of GCC repeat in the beta1 gene is between 7 and 9 in our population. This is not different in bipolar patients from normal controls.

LIMITATIONS

This study examined a small number of patients and examined a very limited portion of the locus.

CONCLUSION

It appears that there is not an expansion of the GCC repeat in the beta1 gene in bipolar patients.

Neuropathology of bipolar disorder

The literature on the neuropathology of bipolar disorder (BD) is reviewed. Postmortem findings in the areas of pathomorphology, signal transduction, neuropeptides, neurotransmitters, cell adhesion molecules, and synaptic proteins are considered. Decreased glial numbers and density in both BD and major depressive disorder (MDD) have been reported, whereas cortical neuron counts were not different in BD (in Brodmann's areas [BAs] 9 and 24). In contrast, MDD patients showed reductions in neuronal size and density (BA 9, BA 47). There are a number of findings of alterations in neuropeptides and monoamines in BD brains. Norepinephrine turnover was increased in several cortical regions and thalamus, whereas the serotonin metabolite, 5-hydroxyindoleacetic acid, and the serotonin transporter were reduced in the cortex. Several reports further implicated both cyclic adenosine monophosphate and phosphatidylinositol (PI) cascade abnormalities. G protein concentrations and activity increases were found in the occipital, prefrontal, and temporal cortices in BD. In the PI signal cascade, alterations in PKC activity were found in the prefrontal cortex. In the occipital cortex, PI hydrolysis was decreased. Two isoforms of the neural cell adhesion molecules were increased in the hippocampus of BD, whereas the synaptic protein marker, synaptophysin, was not changed. The findings of glial reduction, excess signal activity, neuropeptide abnormalities, and monoamine alterations suggest distinct imbalances in neurochemical regulation. Possible alterations in pathways involving ascending projections from the brain stem are considered. Larger numbers of BD brains are needed to further refine the conceptual models that have been proposed, and to develop coherent models of the pathophysiology of BD.

Localization of epidermal growth factor receptors and putative neuroblasts in human subependymal zone

Studies in rodents and monkeys suggest that neuronal precursor cells continue to exist and differentiate well into adulthood in these species. These results challenge the long held assumption that neurogenesis does not occur in the postnatal human brain. We examined the rostral subependymal zone (SEZ) of postnatal human brain for expression of cell phenotypic markers that have been associated with neuronal precursors and neuroblasts in rodent brain. We found epidermal growth factor receptor (EGF-R) mRNA and protein to be expressed in infant, teen, young adult, and adult human SEZ. Some SEZ cells expressed the polysialic acid form of neural cell adhesion molecule (PSA-NCAM), characteristic of migrating neuroblasts, as well as class III beta-tubulin and Hu protein, characteristic of neuroblasts and early neurons. These neuroblast-like cells were negative for glial fibrillary acidic protein (GFAP), 2;,3;-cyclic nucleotide 3;-phosphohydrolase (CNPase), and vimentin, suggesting that they were not differentiating as glia. Our results show that neuroblast-like cells exist in the human SEZ and support the theory that SEZ of postnatal human brain has neurogenic potential.

Evidence for a deficit in cholinergic interneurons in the striatum in schizophrenia

Neurochemical and functional abnormalities of the striatum have been reported in schizophrenic brains, but the cellular substrates of these changes are not known. We hypothesized that schizophrenia may involve an abnormality in one of the key modulators of striatal output, the cholinergic interneuron. We measured the densities of cholinergic neurons in the striatum in schizophrenic and control brains in a blind analysis, using as a marker of this cell population immunoreactivity for choline acetyltransferase, the synthetic enzyme of acetylcholine. As an independent marker, we used immunoreactivity for calretinin, a protein which is co-localized with choline acetyltransferase in virtually all of the cholinergic interneurons of the striatum. A significant decrease in choline acetyltransferase-positive and calretinin-positive cell densities was found in the schizophrenic cases compared with controls in the striatum as a whole [for the choline acetyltransferase-positive cells: controls: 3.21 +/- 0.48 cells/mm2 (mean +/- S.D.), schizophrenics: 2.43 +/- 0.68 cells(mm2; P < 0.02]. The decrease was patchy in nature and most prominent in the ventral striatum (for the choline acetyltransferase-positive cells: controls: 3.47 +/- 0.59 cells/mm2, schizophrenics: 2.52 +/- 0.64 cells/ mm2; P < 0.005) which included the ventral caudate nucleus and nucleus accumbens region. Three of the schizophrenic cases with the lowest densities of cholinergic neurons had not been treated with neuroleptics for periods from more than a month to more than 20 years. A decrease in the number or function of the cholinergic interneurons of the striatum may disrupt activity in the ventral striatal-pallidal-thalamic-prefrontal cortex pathway and thereby contribute to abnormalities in function of the prefrontal cortex in schizophrenia.

Differential effects of haloperidol and clozapine on ionotropic glutamate receptors in rats

Despite multiple lines of investigation the effect of neuroleptics on glutamate-mediated neurotransmission remains controversial. To study the effects of typical and atypical neuroleptics on selected parameters of glutamate-mediated neurotransmission, male Sprague-Dawley rats were randomly assigned to a 21-day oral treatment course with vehicle, haloperidol (HDL), or clozapine (CLZ). Coronal slices of rat brain were then incubated with tritiated ligands to measure NMDA, AMPA, and kainate receptor, and glutamate reuptake site density. Regions of interest included the frontal cortex, anterior cingulate cortex, dorsal striatum, ventral striatum, and the nucleus accumbens. CLZ increased the density of AMPA receptors significantly in the frontal and anterior cingulate cortices compared with normal controls. In the dorsal and ventral striatum, and nucleus accumbens as a whole, CLZ-treated rats had a higher AMPA receptor density compared with both the HDL- and vehicle-treated controls. Additionally, within the nucleus accumbens, CLZ-treated rats had a higher density of AMPA receptors compared with the HDL group in the core, and at trend level in the shell. There was a group by region interaction for NMDA receptor density, primarily reflecting the tendency of HDL treated rats to have high receptor densities in the frontal and anterior cingulate cortices. Kainate receptors and glutamate reuptake site densities did not differ significantly across groups. These results suggest a critical role for glutamate in the mediation of atypical antipsychotic drug action in anatomically-specific regions, and further encourage the investigation of glutamate neurotransmitter systems in schizophrenia.

Alterations of hippocampal secreted N-CAM in bipolar disorder and synaptophysin in schizophrenia

Schizophrenia and bipolar disorder have both been linked to structural abnormalities of the hippocampus, which is consistent with a neurodevelopmental anomaly. One isoform of the neural cell adhesion molecule (N-CAM) protein, cytosolic N-CAM 105-115 kDa, was previously shown to be increased in schizophrenia in the hippocampus and prefrontal cortex. Another isoform of N-CAM, the variable alternative spliced exon of N-CAM, was also increased in the hippocampus and prefrontal cortex of bipolar disorder patients. In the present study, the secreted isoform of N-CAM (SEC N-CAM), synaptophysin, and actin proteins were measured in the hippocampus of controls, suicide victims, and patients with bipolar disorder or schizophrenia by quantitative Western immunoblotting. Previous measurements of cytosolic N-CAM (105-115 kDa) protein, from the same hippocampus samples, were used to calculate the N-CAM (105-115 kDa)/synaptophysin ratio. An affinity purified antibody to SEC N-CAM recognized SEC N-CAM (108 kDa and 115 kDa) in brain but SEC N-CAM was not detectable in CSF. In bipolar disorder, but not in schizophrenia, an increased SEC N-CAM 115 kDa/108 kDa ratio was found as compared to controls (P = 0.03). The synaptophysin/actin ratio was significantly decreased in schizophrenia (P = 0.014) as compared to controls. The cytosolic N-CAM 105-115 kDa/synaptophysin ratio was increased in patients with schizophrenia (P= 0.017), but not in bipolar disorder. Thus, bipolar disorder patients show altered expression of SEC N-CAM in the hippocampus. Patients with schizophrenia show a decrease in synaptophysin and an increase in the cytosolic N-CAM 105-115 kDa/synaptophysin ratio. The results offer further evidence of differences in protein expression between bipolar disorder and schizophrenia in the hippocampus, which is consistent with a distinct neuropathology for each neuropsychiatric disorder.

Coupling efficiency of brain beta-adrenergic receptors to Gs protein in suicide, alcoholism and control subjects

Abnormal beta-adrenergic receptor (betaAR) density in the brains of suicide victims has been reported, although results of studies are inconsistent. Ethanol modifies betaAR-mediated signal transduction. Moreover abnormal betaAR function has been implicated in alcoholism. BetaAR antagonists, which were used as ligands in previous betaAR binding studies, also bind to 5-HT1B/1Dbeta receptors; hence, their estimates of betaAR density are confounded by binding to 5-HT1B/1Dbeta receptors. More importantly, previous studies did not examine betaAR agonist affinity or coupling efficiency to Gs protein. We investigated agonist affinity and coupling efficiency of betaAR to Gs protein in the brains of ten suicide victims, six subjects with alcoholism, and eight controls. There were no differences in betaAR density in either the frontal cortex or hippocampus of suicide victims or alcoholic subjects compared to controls. Preliminary results indicate betaAR supercoupling in suicide victims in both brain regions and uncoupling in alcoholic subjects in the frontal cortex. These results are discussed in view of the existing literature on the role of betaAR in suicide and alcoholism and the mechanism of action of antidepressants.