Expression of GABAA α2-, ß1- and ε-receptors are altered significantly in the lateral cerebellum of subjects with schizophrenia, major depression and bipolar disorder.

There is abundant evidence that dysfunction of the γ-aminobutyric acid (GABA)ergic signaling system is implicated in the pathology of schizophrenia and mood disorders. Less is known about the alterations in protein expression of GABA receptor subunits in brains of subjects with schizophrenia and mood disorders. We have previously demonstrated reduced expression of GABA(B) receptor subunits 1 and 2 (GABBR1 and GABBR2) in the lateral cerebella of subjects with schizophrenia, bipolar disorder and major depressive disorder. In the current study, we have expanded these studies to examine the mRNA and protein expression of 12 GABA(A) subunit proteins (α1, α2, α3, α5, α6, ß1, ß2, ß3, δ, ε, γ2 and γ3) in the lateral cerebella from the same set of subjects with schizophrenia (N=9-15), bipolar disorder (N=10-15) and major depression (N=12-15) versus healthy controls (N=10-15). We found significant group effects for protein levels of the α2-, ß1- and ε-subunits across treatment groups. We also found a significant group effect for mRNA levels of the α1-subunit across treatment groups. New avenues for treatment, such as the use of neurosteroids to promote GABA modulation, could potentially ameliorate GABAergic dysfunction in these disorders.

mRNA and protein expression for novel GABAA receptors θ and ρ2 are altered in schizophrenia and mood disorders; relevance to FMRP-mGluR5 signaling pathway.

Fragile X mental retardation protein (FMRP) is an RNA-binding protein that targets ∼5% of all mRNAs expressed in the brain. Previous work by our laboratory demonstrated significantly lower protein levels for FMRP in lateral cerebella of subjects with schizophrenia, bipolar disorder and major depression when compared with controls. Absence of FMRP expression in animal models of fragile X syndrome (FXS) has been shown to reduce expression of gamma-aminobutyric acid A (GABAA) receptor mRNAs. Previous work by our laboratory has found reduced expression of FMRP, as well as multiple GABAA and GABAB receptor subunits in subjects with autism. Less is known about levels for GABAA subunit protein expression in brains of subjects with schizophrenia and mood disorders. In the current study, we have expanded our previous studies to examine the protein and mRNA expression of two novel GABAA receptors, theta (GABRθ) and rho 2 (GABRρ2) as well as FMRP, and metabotropic glutamate receptor 5 (mGluR5) in lateral cerebella of subjects with schizophrenia, bipolar disorder, major depression and healthy controls, and in superior frontal cortex (Brodmann Area 9 (BA9)) of subjects with schizophrenia, bipolar disorder and healthy controls. We observed multiple statistically significant mRNA and protein changes in levels of GABRθ, GABRρ2, mGluR5 and FMRP molecules including concordant reductions in mRNA and proteins for GABRθ and mGluR5 in lateral cerebella of subjects with schizophrenia; for increased mRNA and protein for GABRρ2 in lateral cerebella of subjects with bipolar disorder; and for reduced mRNA and protein for mGluR5 in BA9 of subjects with bipolar disorder. There were no significant effects of confounds on any of the results.

Glial fibrillary acidic protein is elevated in superior frontal, parietal and cerebellar cortices of autistic subjects.

Autism is a debilitating neurodevelopmental disorder of early childhood with both genetic and environmental origins. Immune system dysregulation has been hypothesized to be involved in this disorder. We quantified levels of glial fibrillary acidic protein (GFAP) and ss-actin in three areas of the brain, namely, area 9, area 40 and cerebellum, in age matched autistic and control postmortem specimen using SDS-PAGE and western blotting techniques. Significant elevations in levels of GFAP were observed in all three brain areas in autism. This report confirms a recent report showing microglial and astroglial activation in autism. Increased GFAP levels in autistic brains signify gliosis, reactive injury, and perturbed neuronal migration processes.

Prenatal viral infection in mouse causes differential expression of genes in brains of mouse progeny: a potential animal model for schizophrenia and autism.

Schizophrenia and autism are neurodevelopmental disorders with genetic and environmental etiologies. Prenatal viral infection has been associated with both disorders. We investigated the effects of prenatal viral infection on gene regulation in offspring of Balb-c mice using microarray technology. The results showed significant upregulation of 21 genes and downregulation of 18 genes in the affected neonatal brain homogenates spanning gene families affecting cell structure and function, namely, cytosolic chaperone system, HSC70, Bicaudal D, aquaporin 4, carbonic anhydrase 3, glycine receptor, norepinephrine transporter, and myelin basic protein. We also verified the results using QPCR measurements of selected mRNA species. These results show for the first time that prenatal human influenza viral infection on day 9 of pregnancy leads to alterations in a subset of genes in brains of exposed offspring, potentially leading to permanent changes in brain structure and function.

Reelin glycoprotein: structure, biology and roles in health and disease.

Reelin glycoprotein is a secretory serine protease with dual roles in mammalian brain: embryologically, it guides neurons and radial glial cells to their corrected positions in the developing brain; in adult brain, Reelin is involved in a signaling pathway which underlies neurotransmission, memory formation and synaptic plasticity. Disruption of Reelin signaling pathway by mutations and selective hypermethylation of the Reln gene promoter or following various pre- or postnatal insults may lead to cognitive deficits present in neuropsychiatric disorders like autism or schizophrenia.

Human influenza viral infection in utero alters glial fibrillary acidic protein immunoreactivity in the developing brains of neonatal mice.

Epidemiological reports describe a strong association between prenatal human influenza viral infection and later development of schizophrenia. Postmodern human brain studies, however, indicate a lack of gliosis in schizophrenic brains presumably secondary to absence of glial cells during the second trimester viral infection in utero. We hypothesized that human influenza infection in day 9 pregnant mice would alter the expression of glial fibrillary acidic protein (GFAP, an important marker of gliosis, neuron migration, and reactive injury) in developing brains of postnatal days 0, 14 and 35 mice. Determination of cellular GFAP immunoreactivity (IR) expressed as cell density in cortex and hippocampus of control and experimental brains showed increases in GFAP-positive density in exposed cortical (P = 0.03 day 14 vs control) and hippocampal cells (P = 0.035 day 14, P = 0.034 day 35). Similarly, ependymal cell layer GFAP-IR cell counts showed increases with increasing brain age from day 0, to days 14 and 35 in infected groups (P = 0.037, day 14) vs controls. The GFAP-positive cells in prenatally exposed brains showed 'hypertrophy' and more stellate morphology. These results implicate a significant role of prenatal human influenza viral infection on subsequent gliosis, which persists throughout brain development in mice from birth to adolescence.

Altered levels of Reelin and its isoforms in schizophrenia and mood disorders.

Reelin is a secreted extracellular matrix protein approximately 410 kDa mol. wt that is reduced in brains of patients with schizophrenia, autism, bipolar disorder and major depression. Recent reports also indicate its near absence in sera of some patients with an autosomal recessive form of lissencephaly. Moreover, Reelin is involved not only in normal cortical lamination of the brain during mammalian embryogenesis but is also implicated in cell signaling systems subserving cognition in adult brain. Here, we show that blood levels of Reelin and its isoforms are altered in three psychiatric disorders, namely, schizophrenia, bipolar disorder and major depression. The changes include significant increases in 410 kDa Reelin moiety of 49% in schizophrenic patients (p < 0.022) of four ethnic compositions (Caucasian, Vietnamese, Hmong and Laotian) and non-significant increases in depressed patients by 34% vs control blood. In contrast, 410 kDa Reelin levels decreased by 33% in bipolar blood, albeit non-signficantly, vs. controls. There was a significant increase of 90% (p < 0.0061) in 330 kDa Reelin in Caucasian schizophrenics; the depressed value was elevated by 30% vs. control but non-significantly. Again, in contrast, bipolar 330 kDa value decreased by 31% vs control (p < 0.0480). Finally, all 180 kDa Reelin values varied minimally in schizophrenics vs controls. In contrast, the 180 kDa Reelin values dropped significantly by 49% (p < 0.0117) and 29% (p < 0.0424) in bipolar and depressed patients, respectively, compared with controls. The alterations in blood Reelin values appear to be specific since levels of two other blood proteins, ceruloplasmin and albumin did not vary significantly between all psychiatric subjects and controls. These findings suggest that blood Reelin levels and its isoforms may be used as potential peripheral markers to diagnose presence of several psychiatric disorders and may also serve as targets for future therapeutic interventions.

Altered levels of the synaptosomal associated protein SNAP-25 in hippocampus of subjects with mood disorders and schizophrenia.

SNAP-25 levels were measured in ventral hippocampus in subjects with unipolar depression (n = 12), bipolar disorder (n = 13), schizophrenia (n = 15) and controls (n = 15) using quantitative immunocytochemistry. SNAP-25 levels were reduced significantly in stratum oriens of bipolar patients compared with controls (p < 0.05); they were also reduced significantly in st. oriens (p < 0.01 vs schizophrenia), in alveous (p < 0.01 vs schizophrenia) and in presubiculum (p < 0.05 vs depressed). SNAP-25 levels were also reduced in several layers of schizophrenics, only significantly so in st. granulosum (p < 0.05 vs controls). In contrast, depressed SNAP-25 levels increased in st. moleculare (p < 0.01 vs schizophrenics) and presubiculum (p < 0.05 vs controls and bipolars; p < 0.01 vs schizophrenics). SNAP-25 values were not affected by age, sex, race, post-mortem interval, brain pH, side of brain, age of onset of disease, family history of psychiatric disease, drug or alcohol use, antipsychotic drug treatment, or mode of death. The reported changes in SNAP-25 levels appear to be disease specific, separating synaptic pathology in unipolar depression from that observed in schizophrenia and bipolar disorders.

Reduction in anti-apoptotic protein Bcl-2 in autistic cerebellum.

Autism is a neurodevelopmental disorder with genetic and environmental etiologies. Neurohistologic findings have shown Purkinje cell depletion and atrophy in the cerebellum of autistic subjects. We hypothesized that apoptotic mechanisms might explain these Purkinje cell findings. Bcl-2 is a potent anti-apoptotic regulatory protein, which is reduced in schizophrenic brains. Autistic and normal control cerebellar cortices matched for age, sex and PMI were prepared for SDS-gel electrophoresis and Western blotting using specific anti-Bcl-2 antibodies. Quantification of Bcl-2 showed a significant 34-51% reduction in autistic cerebellum (mean (+/- s.d.) optical density/75 microg protein 0.290 +/- 0.08, n = 5) compared with controls (0.595 +/- 0.31, n = 8; p < 0.04); levels of neuronal-specific class III beta-tubulin (controls 49.8 +/- 6.7; autistics 36.2 +/- 18.2), or beta-actin (controls 7.3 +/- 2.7; autistics 6.77 +/- 0.66) in the same homogenates did not differ significantly between groups. These results indicate for the first time that autistic cerebellum may be vulnerable to pro-apoptotic stimuli and to neuronal atrophy as a consequence of decreased Bcl-2 levels.

Dysregulation of Reelin and Bcl-2 proteins in autistic cerebellum.

Autism is a severe neurodevelopmental disorder with potential genetic and environmental causes. Cerebellar pathology including Purkinje cell atrophy has been demonstrated previously. We hypothesized that cell migration and apoptotic mechanisms may account for observed Purkinje cell abnormalities. Reelin is an important secretory glycoprotein responsible for normal layering of the brain. Bcl-2 is a regulatory protein responsible for control of programmed cell death in the brain. Autistic and normal control cerebellar corteces matched for age, sex, and post-mortem interval (PMI) were prepared for SDS-gel electrophoresis and Western blotting using specific anti-Reelin and anti-Bcl-2 antibodies. Quantification of Reelin bands showed 43%, 44%, and 44% reductions in autistic cerebellum (mean optical density +/- SD per 30 microg protein 4.05 +/- 4.0, 1.98 +/- 2.0, 13.88 +/- 11.9 for 410 kDa, 330 kDa, and 180 kDa bands, respectively; N = 5) compared with controls (mean optical density +/- SD per 30 microg protein, 7.1 +/- 1.6, 3.5 +/- 1.0, 24.7 +/- 5.0; N = 8, p < 0.0402 for 180 kDa band). Quantification of Bcl-2 levels showed a 34% to 51% reduction in autistic cerebellum (M +/- SD per 75 microg protein 0.29 +/- 0.08; N = 5) compared with controls (M +/- SD per 75 microg protein 0.59 +/- 0.31; N = 8, p < 0.0451). Measurement of beta-actin (M +/- SD for controls 7.3 +/- 2.9; for autistics 6.77 +/- 0.66) in the same homogenates did not differ significantly between groups. These results demonstrate for the first time that dysregulation of Reelin and Bcl-2 may be responsible for some of the brain structural and behavioral abnormalities observed in autism.

Reduction in Reelin immunoreactivity in hippocampus of subjects with schizophrenia, bipolar disorder and major depression.

Accumulation of neurobiological knowledge points to neurodevelopmental origins for certain psychotic and mood disorders. Recent landmark postmortem reports implicate Reelin, a secretory glycoprotein responsible for normal lamination of brain, in the pathology of schizophrenia and bipolar disorders. We employed quantitative immunocytochemistry to measure levels of Reelin protein in various compartments of hippocampal formation in subjects diagnosed with schizophrenia, bipolar disorder and major depression compared to normal controls. Significant reductions were observed in Reelin-positive adjusted cell densities in the dentate molecular layer (ANOVA, P < 0.001), CA4 area (ANOVA, P < 0.001), total hippocampal area (ANOVA, P < 0.038) and in Reelin-positive cell counts in CA4 (ANOVA, P < 0.042) of schizophrenics vs controls. Adjusted Reelin-positive cell densities were also reduced in CA4 areas of subjects with bipolar disorder (ANOVA, P < 0.001) and nonsignificantly in those with major depression. CA4 areas were also significantly reduced in schizophrenic (ANOVA, P < 0.009) patients. No significant effects of confounding variables were found. The exception was that family history of psychiatric illness correlated strongly with Reelin reductions in several areas of hippocampus (CA4, adjusted cell density, F = 13.77, P = 0.001). We present new immunocytochemical evidence showing reductions in Reelin expression in hippocampus of subjects with schizophrenia, bipolar disorder and major depression and confirm recent reports documenting a similar deficit involving Reelin expression in brains of subjects with schizophrenia and bipolar disorder.

Prenatal viral infection causes alterations in nNOS expression in developing mouse brains.

Epidemiological evidence points to prenatal viral infection being responsible for some forms of schizophrenia and autism. We hypothesized that prenatal human influenza viral infection in day 9 pregnant mice may cause changes in the levels of neuronal nitric oxide synthase (nNOS), an important molecule involved in synaptogenesis and excitotoxicity, in neonatal brains. Brains from 35- and 56-day-old mice were prepared for SDS-gel electrophoresis and Western blotting using polyclonal anti nNOS antibody. Quantification of nNOS showed time and region-dependent changes in the levels of nNOS protein. Mean rostral brain area value from prenatally infected animals showed a significant (p=0.067) increase of 147% in nNOS levels at 35 days postnatally, with an eventual 29% decrease on day 56. Middle and caudal brain areas showed reductions in nNOS in experimental mice at 35 and 56 days, with a significant 27% decrease in nNOS in the middle segment of day 56 brains (p=0.016). Significant interactions were found between group membership and brain area (Wilks lambda=0.440, F(2.9)=5.72, p=0.025); there was also a significant interaction between brain area, group and age (Wilks lambda=0.437, F(2.9)=5.79, p=0.024). These results provide further support for the notion that prenatal viral infection affects brain development adversely via the pathological involvement of nNOS expression.