Jack D. Barchas

Genome-wide association and meta-analysis of bipolar disorder in individuals of European ancestry

Bipolar disorder (BP) is a disabling and often life-threatening disorder that affects ≈1% of the population worldwide. To identify genetic variants that increase the risk of BP, we genotyped on the Illumina HumanHap550 Beadchip 2,076 bipolar cases and 1,676 controls of European ancestry from the National Institute of Mental Health Human Genetics Initiative Repository, and the Prechter Repository and samples collected in London, Toronto, and Dundee. We imputed SNP genotypes and tested for SNP-BP association in each sample and then performed meta-analysis across samples. The strongest association P value for this 2-study meta-analysis was 2.4 × 10−6. We next imputed SNP genotypes and tested for SNP-BP association based on the publicly available Affymetrix 500K genotype data from the Wellcome Trust Case Control Consortium for 1,868 BP cases and a reference set of 12,831 individuals. A 3-study meta-analysis of 3,683 nonoverlapping cases and 14,507 extended controls on >2.3 M genotyped and imputed SNPs resulted in 3 chromosomal regions with association P ≈ 10−7: 1p31.1 (no known genes), 3p21 (>25 known genes), and 5q15 (MCTP1). The most strongly associated nonsynonymous SNP rs1042779 (OR = 1.19, P = 1.8 × 10−7) is in the ITIH1 gene on chromosome 3, with other strongly associated nonsynonymous SNPs in GNL3, NEK4, and ITIH3. Thus, these chromosomal regions harbor genes implicated in cell cycle, neurogenesis, neuroplasticity, and neurosignaling. In addition, we replicated the reported ANK3 association results for SNP rs10994336 in the nonoverlapping GSK sample (OR = 1.37, P = 0.042). Although these results are promising, analysis of additional samples will be required to confirm that variant(s) in these regions influence BP risk.

Immunocytochemical localization of methionine enkephalin: Preliminary observations

Abstract Antiserum directed against methionine enkephalin (metenkephalin) was used to determine its anatomical distribution in rat brain. Cross reactivity of that antiserum was not detectable against leucine enkephalin (leu-enkephalin), β-lipotropin (β-LPH), β-endorphin or assorted peptide fragments of met-enkephalin; alpha-endorphin was 370 times less active than met-enkephalin. The localization of met-enkephalin was carried out in the presence of excess leu-enkephalin and yet could be blocked with equal amounts of met-enkephalin. Met-enkephalin was detected in several structures in the spinal cord, medulla, pons, mesencephalon, diencephalon and telencephalon. No met-enkephalin was detected in cerebellum or cerebral cortex.

Catecholamine Secretion as a Function of Perceived Coping Self-Efficacy

The present research tested the hypothesis that perceived coping self-efficacy mediates the effects of environmental events on catecholamine secretion. Differential levels of perceived self-efficacy were induced in phobic subjects through modeling. Their level of catecholamine secretion was then measured as they were presented coping tasks in their high, medium, and low ranges of perceived self-efficacy. High perceived self-efficacy was accompanied by low levels of plasma epinephrine and norepinephrine during interaction with a phobic object, whereas moderate perceived self-inefficacy gave rise to substantial increases in plasma catecholamines. Both catecholamines dropped sharply when phobics declined tasks for which they judged themselves completely inefficacious. In contrast, dopac was released maximally by mere apperception of task demands that phobics regarded as overwhelming their coping capabilities. After perceived self-efficacy was strengthened to the maximal level by participant modeling, all of the tasks were performed without any differential catecholamine responses.

Circadian patterns of gene expression in the human brain and disruption in major depressive disorder

A cardinal symptom of major depressive disorder (MDD) is the disruption of circadian patterns. However, to date, there is no direct evidence of circadian clock dysregulation in the brains of patients who have MDD. Circadian rhythmicity of gene expression has been observed in animals and peripheral human tissues, but its presence and variability in the human brain were difficult to characterize. Here, we applied time-of-death analysis to gene expression data from high-quality postmortem brains, examining 24-h cyclic patterns in six cortical and limbic regions of 55 subjects with no history of psychiatric or neurological illnesses (“controls”) and 34 patients with MDD. Our dataset covered ∼12,000 transcripts in the dorsolateral prefrontal cortex, anterior cingulate cortex, hippocampus, amygdala, nucleus accumbens, and cerebellum. Several hundred transcripts in each region showed 24-h cyclic patterns in controls, and >100 transcripts exhibited consistent rhythmicity and phase synchrony across regions. Among the top-ranked rhythmic genes were the canonical clock genes BMAL1(ARNTL), PER1-2-3, NR1D1(REV-ERBa), DBP, BHLHE40 (DEC1), and BHLHE41(DEC2). The phasing of known circadian genes was consistent with data derived from other diurnal mammals. Cyclic patterns were much weaker in the brains of patients with MDD due to shifted peak timing and potentially disrupted phase relationships between individual circadian genes. This transcriptome-wide analysis of the human brain demonstrates a rhythmic rise and fall of gene expression in regions outside of the suprachiasmatic nucleus in control subjects. The description of its breakdown in MDD suggests potentially important molecular targets for treatment of mood disorders.

Epinephrine, norepinephrine, dopamine and serotonin: differential effects of acute and chronic stress on regional brain amines.

Following acute cold swim stress, hypothalamic epinephrine concentrations were markedly lowered and remained decreased for 24 h, while norepinephrine concentrations were decreased, but returned to baseline within 14 h. With oscillation stress repeated daily for 21 days, hypothalamic norepinephrine, hypothalamic epinephrine, and hippocampal norepinephrine turnover were decreased and absolute concentrations were increased. Repeated stress had little effect on serotonin, dopamine or their metabolites. These results suggest that hypothalamic epinephrine concentration and turnover are particularly responsive to acute and chronic stress. The decreased epinephrine and norepinephrine turnover under chronic stress may be responsible in part for the behavioral and endocrine changes observed in chronically stressed rats.

Altered expression of glutamate signaling, growth factor and glia genes in the locus coeruleus of patients with major depression

Several studies have proposed that brain glutamate signaling abnormalities and glial pathology have a role in the etiology of major depressive disorder (MDD). These conclusions were primarily drawn from post-mortem studies in which forebrain brain regions were examined. The locus coeruleus (LC) is the primary source of extensive noradrenergic innervation of the forebrain and as such exerts a powerful regulatory role over cognitive and affective functions, which are dysregulated in MDD. Furthermore, altered noradrenergic neurotransmission is associated with depressive symptoms and is thought to have a role in the pathophysiology of MDD. In the present study we used laser-capture microdissection (LCM) to selectively harvest LC tissue from post-mortem brains of MDD patients, patients with bipolar disorder (BPD) and from psychiatrically normal subjects. Using microarray technology we examined global patterns of gene expression. Differential mRNA expression of select candidate genes was then interrogated using quantitative real-time PCR (qPCR) and in situ hybridization (ISH). Our findings reveal multiple signaling pathway alterations in the LC of MDD but not BPD subjects. These include glutamate signaling genes, SLC1A2, SLC1A3 and GLUL, growth factor genes FGFR3 and TrkB, and several genes exclusively expressed in astroglia. Our data extend previous findings of altered glutamate, astroglial and growth factor functions in MDD for the first time to the brainstem. These findings indicate that such alterations: (1) are unique to MDD and distinguishable from BPD, and (2) affect multiple brain regions, suggesting a whole-brain dysregulation of such functions.

Epinephrine and norepinephrine responses in continuously collected human plasma to a series of stressors.

&NA; The present study employed continuous blood withdrawal to examine epinephrine and norepinephrine responses to a cognitive stressor (mental arithmetic), active physical stressors (handgrip and knee bends), passive painful stressors (venipuncture and cold pressor), and a medical procedure that was considered nonstressful (blood pressure measurements). The data were analyzed by analysis of variance (ANOVA) and by time series analysis. The ANOVA indicated that epinephrine and norepinephrine increased significantly in response to the stressors. Epinephrine showed a greater increase to the cognitive stressor than to the others. Time series analysis, however, showed a more varied pattern. It indicated that the height and duration of response differed considerably across subjects and across interventions. The results from both analytic procedures are compared and discussed in terms of current hypotheses of catecholamine response.

Constitutively expressed rat mRNA encoding a 70-kilodalton heat-shock-like protein.

A nearly full-length cDNA clone isolated from the rat pheochromocytoma cell line, PC12, revealed extensive nucleotide sequence similarity between the rat cDNA and the Drosophila melanogaster hsp70 gene. The rat recombinant clone encodes a 71,000-dalton protein that is 70% identical with the dipteran hsp70 protein. Remarkably, a truncated segment of this cDNA clone was originally isolated by immunoreactivity with antisera raised to catecholamine-synthesizing enzymes, suggesting that this heat shock protein and these catecholamine enzymes shared antigenic determinants. The rat hsp70-related mRNA is responsible for the production of a constitutive hsp70 protein, because it is present in abundant amounts in various tissues at normal growth temperatures and is only minimally induced by hyperthermia. The rat hsp70-related sequence is part of a multigene family that extends across species to mice and humans.

Parachlorophenylalanine and habituation to repetitive auditory startle stimuli in rats

Abstract The relationship between brain serotonin levels and habituation of a skeletal-motor startle response was studied using parachlorophenylalanine (PCPA), a drug which inhibits the formation of serotonin. Depletion of brain serotonin by PCPA slows down, but does not prevent, habituation. PCPA given to rats that were habituated before starting drug treatment causes a transitory increase in startle response magnitude. Whether PCPA is administered before or after habituation, the treated rats exhibit heightened reactivity to startle stimuli following exposure to novel stimuli. These results suggest that brain serotonin plays a role in inhibitory processes.

III. Determination of plasma catecholamines and free 3, 4-dihydroxyphenylacetic acid in continuously collected human plasma by high performance liquid chromatography with electrochemical detection

Abstract We have presented a sensitive and relatively simple and inexpensive method for continuous sampling and determination of plasma catecholamines and a major dopamine metabolite, DOPAC. This method provides the basis for determination of the short-term magnitude of catecholamine response as well as the time course of such a response following several physical or psychological interventions. Resting levels of plasma catecholamines--norepinephrine 292 pg/ml, epinephrine 81 pg/ml and dopamine 29 pg/ml--are comparable to those obtained by other methods. Dopamine and free DOPAC were unaffected by physical or psychological interventions while norepinephrine was considerably increased by isometric handgrip, knee bends, and cold pressor and epinephrine increased during knee bends, mental arithmetic, cold pressor, and blood pressure measurement.