Gender and brain regions specific differences in brain derived neurotrophic factor protein levels of depressed individuals who died through suicide.

Considerable evidence supports the view that depressive illness and suicidal behaviour stem from perturbations of neuroplasticity. Presently, we assessed whether depressed individuals who died by suicide displayed brain region-specific changes in brain derived neurotrophic factor (BDNF) and whether such effects varied by gender. Using postmortem samples from non-psychiatric controls and depressed individuals who died by suicide, BDNF protein levels were assessed within the hippocampus and frontopolar prefrontal cortex using Western blot. As expected, BDNF levels were reduced within the frontopolar prefrontal cortex among female depressed suicides; however, males showed no such effect. Contrastingly, within the hippocampus, depressed male but not female suicides displayed significant reductions of BDNF protein levels. Although the mechanisms driving the gender and brain region specific BDNF changes are unclear, our data do support the notion that complex alterations of neuroplasticity may be fundamentally involved in the illness.

Impact of monoamine-related gene polymorphisms on hippocampal volume in treatment-resistant depression.

OBJECTIVE: In major depressive disorder (MDD), single nucleotide polymorphisms (SNPs) in monoaminergic genes may impact disease susceptibility, treatment response, and brain volume. The objective of this study was to examine the effect of such polymorphisms on hippocampal volume in patients with treatment-resistant MDD and healthy controls. Candidate gene risk alleles were hypothesised to be associated with reductions in hippocampal volume. METHODS: A total of 26 outpatients with treatment-resistant MDD and 27 matched healthy controls underwent magnetic resonance imaging and genotyping for six SNPs in monoaminergic genes [serotonin transporter (SLC6A4), norepinephrine transporter (SLC6A2), serotonin 1A and 2A receptors (HTR1A and HTR2A), catechol-O-methyltransferase (COMT), and brain-derived neurotrophic factor (BDNF)]. Hippocampal volume was estimated using an automated segmentation algorithm (FreeSurfer). RESULTS: Hippocampal volume did not differ between patients and controls. Within the entire study sample irrespective of diagnosis, C allele-carriers for both the NET-182 T/C [rs2242446] and 5-HT1A-1019C/G [rs6295] polymorphisms had smaller hippocampal volumes relative to other genotypes. For the 5-HTTLPR (rs25531) polymorphism, there was a significant diagnosis by genotype interaction effect on hippocampal volume. Among patients only, homozygosity for the 5-HTTLPR short (S) allele was associated with smaller hippocampal volume. There was no association between the 5-HT2A, COMT, and BDNF SNPs and hippocampal volume. CONCLUSION: The results indicate that the volume of the hippocampus may be influenced by serotonin- and norepinephrine-related gene polymorphisms. The NET and 5-HT1A polymorphisms appear to have similar effects on hippocampal volume in patients and controls while the 5-HTTLPR polymorphism differentially affects hippocampal volume in the presence of depression.

Catechol-O-methyltransferase Val158Met polymorphism and altered COMT gene expression in the prefrontal cortex of suicide brains.

Catechol-O-methyltransferase (COMT) plays a key role in the degradation of catecholamine neurotransmitters within the brain. A functional polymorphism COMT Val158Met has been associated with psychiatric disorders including suicidal behavior. In the present study we examined whether this polymorphism was related to COMT mRNA expression in frontal cortical regions, and whether the expression of COMT differed between depressed suicide victims and psychiatric healthy controls. The Val158Met polymorphism was determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. The levels of COMT mRNA expression in the frontopolar cortex (FPC; 29 suicides vs. 27 controls) and orbital frontal cortex (OFC; 19 suicides vs. 15 controls) were significantly increased among depressed individuals that died by suicide relative to those of controls, being up-regulated by approximately 60% and 65% in the FPC and OFC, respectively. Furthermore, among individuals with the Met allele (Met/Met and Met/Val genotypes) who died by suicide COMT mRNA expression was elevated relative to that of the nondepressed Met allele carriers. However, significant differences were not detected between suicides (n=49) and controls (n=72) with respect to the Val158Met genotypic distribution and allelic frequencies. These results are consistent with the perspective that altered COMT mRNA expression in frontal cortical brain regions might contribute to suicide and/or depression, further supporting the role of dysregulation of catecholaminergic pathway genes in the pathophysiology of suicide behaviors.

Altered Organization of GABA(A) Receptor mRNA Expression in the Depressed Suicide Brain.

Inter-relationships ordinarily exist between mRNA expression of GABA(A) subunits in the frontopolar cortex (FPC) of individuals that had died suddenly from causes other than suicide. However, these correlations were largely absent in persons that had died by suicide. In the present investigation, these findings were extended by examining GABA(A) receptor expression patterns (of controls and depressed individuals that died by suicide) in the orbital frontal cortex (OFC), hippocampus, amygdala. locus coeruleus (LC) and paraventricular nucleus (PVN), all of which have been implicated in either depression, anxiety or stress responsivity. Using QPCR analysis, we found that in controls the inter-relations between GABA(A) subunits varied across brain regions, being high in the hippocampus and amygdala, intermediate in the LC, and low in the OFC and PVN. The GABA(A) subunit inter-relations were markedly different in persons that died by suicide, being reduced in hippocampus and amygdala, stable in the LC, but more coordinated in the OFC and to some extent in the PVN. It seems that altered brain region-specific inhibitory signaling, stemming from altered GABA(A) subunit coordination, are associated with depression/suicide. Although, it is unknown whether GABA(A) subunit re-organization was specifically tied to depression, suicide, or the accompanying distress, these data show that the coordinated expression of this transcriptome does vary depending on brain region and is plastic.

GABAA receptor promoter hypermethylation in suicide brain: implications for the involvement of epigenetic processes.

BACKGROUND: Epigenetic mechanisms may be involved in the reprogramming of gene expression in response to stressful stimuli. This investigation determined whether epigenetic phenomena might similarly be associated with suicide/depression. METHODS: The expression of DNA methyltransferase (DNMT) mRNA was assessed in several brain regions of individuals who had committed suicide and had been diagnosed with major depression relative to that of individuals who had died suddenly as a result of factors other than suicide. RESULTS: The DNMT gene transcripts' expression was altered in several brains regions of suicides, including frontopolar cortex, amygdala, and the paraventricular nucleus of the hypothalamus. Importantly, an increase of both mRNA and protein expression was found in the frontopolar cortex. In addition, although transcript abundance of various forms of DNMT was highly correlated in normal control subjects, this coordination of DNMT isoform expression was diminished in suicide brain. Further, within the frontopolar cortex, gene-specific aberrations in DNA methylation were apparent in the gamma-aminobutyric acid (GABA)(A) receptor alpha1 subunit promoter region, the transcript of which is underexpressed in suicide/major depressive disorder (MDD) brains. Indeed, three cytosine/guanosine sites were hypermethylated relative to control subjects. Finally, we found that DNMT-3B mRNA abundance was inversely correlated to alpha1 mRNA abundance. CONCLUSIONS: These data show that DNMT mRNA expression was altered in suicide brain, and this change in expression in the frontopolar cortex was associated with increased methylation of a gene whose mRNA expression has previously been shown to be reduced. These observations suggest that epigenetic mechanisms may be associated with altered gene expression in suicide/MDD.

Serotonin receptor subtype and p11 mRNA expression in stress-relevant brain regions of suicide and control subjects.

OBJECTIVE: Studies comparing people suffering from depression who committed suicide with control subjects have yielded inconsistent results regarding serotonin (5-HT) involvement in pathology, possibly owing to procedural factors. Our objective was to investigate which 5-HT receptor subtypes might be associated with depression and suicide, whether receptor differences vary across brain regions and whether they are moderated by sex. METHODS: We assessed messenger ribonucleic acid (mRNA) expression of several 5-HT receptor subtypes and that of p11, a protein involved in the functional expression of 5-HT(1B), in several stress-relevant brain regions. Tissue was obtained soon after death, and RNA integrity and pH was confirmed to be appropriate. Brain tissue from suicide subjects suffering from depression and from control subjects who had died from other causes (10 men and 10 women in each condition) was obtained within 6.5 hours postmortem. Quantitative polymerase chain reaction analyses determined mRNA expression of 5-HT receptor subtypes and p11 within the frontopolar cortex, orbitofrontal cortex, hippocampus, amygdala and paraventricular nucleus. The 5-HT transporter (5-HTT) was also assessed in the raphe nucleus. RESULTS: Differences of 5-HT(1A), 5-HT(1B) and p11 mRNA expression between people who committed suicide and control subjects were relatively widespread, whereas 5-HT(2A) and 5-HT(2C) variations were restricted to the frontopolar cortex and amygdala. Within the dorsal raphe nucleus, neither 5-HT(1A) nor 5-HTT mRNA expression differed between those who committed suicide and control subjects. CONCLUSION: Several 5-HT receptor subtypes are associated with depression and suicide, but these receptor differences vary across brain regions and are moderated by sex.

Corticotropin-releasing hormone, arginine vasopressin, gastrin-releasing peptide, and neuromedin B alterations in stress-relevant brain regions of suicides and control subjects.

BACKGROUND: Postmortem levels of several stress- and depression-relevant neuropeptides were assessed in brain regions of depressed suicides relative to control subjects that had died of other causes. METHODS: Brains of suicides and those that died from other causes were collected soon after death (typically <6 hours). Immunoreactivity levels (ir) of corticotropin-releasing hormone (CRH-ir) and arginine vasopressin (AVP-ir), and the bombesin analogs, gastrin-releasing peptide (GRP-ir), and neuromedin B (NMB-ir), were assessed. RESULTS: Levels of CRH-ir among suicides were elevated in the locus coeruleus (LC), frontopolar, dorsolateral prefrontal (DMPFC) and ventromedial prefrontal cortices, but were reduced at the dorsovagal complex (DVC). The concentration of AVP-ir was elevated at the paraventricluar hypothalamic nucleus, LC, and DMPFC, and reduced at the DVC. Finally, GRP and NMB variations, which might influence anxiety states, were limited, although GRP-ir within the LC of suicides was higher than in control subjects, while NMB-ir was reduced at the DVC of suicides. CONCLUSIONS: The data show several neuropeptide changes in relation to suicide, although it is premature to ascribe these outcomes specifically to the suicide act versus depression. Likewise, it is uncertain whether the neuropeptide alterations were etiologically related to suicide/depression or secondary to the depressive state.

MAO-A gene polymorphisms are associated with major depression and sleep disturbance in males.

We investigated whether the genetic variants of the MAO-A gene were associated with major depression and/or the clusters of depressive symptoms. The EcoRV and the uVNTR polymorphisms were studied in a population of 191 patients with major depression and 233 control subjects. The EcoRV polymorphism was found to be associated with depression in males but not in females. Haplotype analysis revealed that one of the haplotypes (EcoRV2-uVNTR1) was significantly more frequent among male patients than male controls. Among the HAMD symptom clusters, insomnia scores were significantly higher in male patients carrying allele 2 of the EcoRV polymorphism. These data suggest that the EcoRV and uVNTR polymorphisms may be involved in the pathogenesis of major depression and associated with insomnia in depressed patients.

Association of the C(-1019)G 5-HT1A functional promoter polymorphism with antidepressant response.

Antidepressants, such as serotonin or noradrenaline reuptake inhibitors (e.g. fluoxetine, nefadozone) or 5-HT1A agonists (flibanserin), desensitize the 5-HT1A autoreceptor, which may contribute to their clinical efficacy. The 5-HT1A receptor gene is repressed by NUDR/DEAF-1 in raphe cells at the C-, but not at the G-allele of the C(-1019)G polymorphism that is associated with major depression and suicide. Depressed patients (n=118) were treated with antidepressants including fluoxetine or nefadozone combined with pindolol or flibanserin alone. The severity of depression was assesssed using the Hamilton Rating Scale for Depression. Although patients had similar severity initially, those with the homozygous G(-1019) genotype responded significantly less to flibanserin (p=0.039) and in pooled antidepressant treatment groups (p=0.0497) and were approximately twice as likely to be non-responders as those with the C(-1019)C genotype. These results implicate the C(-1019)G 5-HT1A gene polymorphism as a potential marker for antidepressant response, suggesting a role for repression of the 5-HT1A gene.

Dysregulation in the suicide brain: mRNA expression of corticotropin-releasing hormone receptors and GABA(A) receptor subunits in frontal cortical brain region.

Corticotropin-releasing hormone (CRH) and GABA have been implicated in depression, and there is reason to believe that GABA may influence CRH functioning. The levels of CRH, and mRNA for CRH-binding protein, CRH1, and CRH2 receptors, as well as various GABA(A) receptor subunits (alpha1, alpha2, alpha3, alpha4, alpha5, delta, and gamma2), were determined in several frontal cortical brain regions of depressed suicide victims and nondepressed individuals who had not died by suicide. Relative to the comparison group, CRH levels were elevated in frontopolar and dorsomedial prefrontal cortex, but not in the ventrolateral prefrontal cortex of suicide victims. Conversely, using quantitative PCR analyses, it was observed that, in frontopolar cortex, mRNA for CRH1, but not CRH2, receptors were reduced in suicide brains, possibly secondary to the high levels of CRH activity. In addition, mRNA of the alpha1, alpha3, alpha4, and delta receptor subunits was reduced in the frontopolar region of suicide victims. Interestingly, a partial analysis of the GABA(A) receptor functional genome revealed high cross-correlations between subunit expression in cortical regions of nondepressed individuals, suggesting a high degree of coordinated gene regulation. However, in suicide brains, this regulation was perturbed, independent of overall subunit abundance. These findings raise the possibility that the CRH and GABA(A) receptor subunit changes, or the disturbed coordination between these GABA(A) receptor subunits, contribute to depression and/or suicidality or are secondary to the illness/distress associated with it.

Impaired repression at a 5-hydroxytryptamine 1A receptor gene polymorphism associated with major depression and suicide.

Inhibition of serotonergic raphe neurons is mediated by somatodendritic 5-HT1A autoreceptors, which may be increased in depressed patients. We report an association of the C(-1019)G 5-HT1A promoter polymorphism with major depression and suicide in separate cohorts. In depressed patients, the homozygous G(-1019) allele was enriched twofold versus controls (p = 0.0017 and 0.0006 for G/G genotype and G allele distribution, respectively), and in completed suicide cases the G(-1019) allele was enriched fourfold (p = 0.002 and 0.00008 for G/G genotype and G allele distribution, respectively). The C(-1019) allele was part of a 26 bp imperfect palindrome that bound transcription factors nuclear NUDR [nuclear deformed epidermal autoregulatory factor (DEAF-1)]/suppressin and Hairy/Enhancer-of-split-5 (Drosophila) (Hes5) to repress 5-HT1A or heterologous promoters, whereas the G(-1019) allele abolished repression by NUDR, but only partially impaired Hes5-mediated repression. Recombinant NUDR bound specifically to the 26 bp palindrome, and endogenous NUDR was present in the major protein-DNA complex from raphe nuclear extracts. Stable expression of NUDR in raphe cells reduced levels of endogenous 5-HT1A protein and binding. NUDR protein was colocalized with 5-HT1A receptors in serotonergic raphe cells, hippocampal and cortical neurons, and adult brain regions including raphe nuclei, indicating a role in regulating 5-HT1A autoreceptor expression. Our data indicate that NUDR is a repressor of the 5-HT1A receptor in raphe cells the function of which is abrogated by a promoter polymorphism. We suggest a novel transcriptional model in which the G(-1019) allele derepresses 5-HT1A autoreceptor expression to reduce serotonergic neurotransmission, predisposing to depression and suicide.

High activity-related allele of MAO-A gene associated with depressed suicide in males.

Abnormalities in brain monoamine oxidase A activity have been implicated in the pathogenesis of depressive illness and suicidal behavior. The present investigation was to determine whether there is an association between MAO-A gene polymorphism and depressed suicide. The EcoRV polymorphism in MAO-A gene with alleles associated with enzyme activity was studied in postmortem brain samples from 44 depressed suicide victims and 92 control subjects of the same ethnic background. We have found significant differences in genotype/allele distribution between depressed suicide victims and controls in males (p = 0.012) but not in females or the total sample. The odds ratio (OR) for the high activity-related allele of the MAO-A gene associated with depressed suicide in males was 3.1. Our finding suggests that MAO-A may be a susceptibility gene in depressed male suicide victims. The results thus provide further evidence that genetic factors can modulate risk for depression, suicide or both by influencing monoaminergic activity in sexually dimorphic manner.

Does fluoxetine influence major depression by modifying five-factor personality traits?

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) are effective in the treatment of depression, though response to them is difficult to predict. The aims of this study were two-fold: (1) to determine the differences in personality profile between patients with major depression and healthy control subjects and (2) to assess the effect of treatment with fluoxetine on personality domain scores and determine whether any of the personality traits can predict the outcome of antidepressant treatment. METHODS: The study included 53 patients with major depression and 53 healthy controls. The NEO-Five-Factor Inventory (NEO-FFI) was administered to all subjects before and after 24 weeks of treatment with fluoxetine. RESULTS: The patients in an episode of major depression had a significantly different personality profile compared to healthy controls at baseline and the severity of their illness correlated with higher scores in the Neuroticism domain. Treatment with fluoxetine was associated with a reversal of high Neuroticism scores and low Extraversion scores in the whole sample and in a subgroup of responders but not in non-responders. Among the FFI personality domains, Agreeableness was a better predictor of treatment outcome than baseline HAMD-17 scores. LIMITATIONS: There was no placebo group, which would have permitted the evaluation of the effect of non-drug factors in treatment outcome and changes in personality domain scores. The sample size was only moderate. CONCLUSIONS: The results suggest that (a) significant differences exist between the personality profiles of depressed patients and healthy control subjects and (b) responders to treatment with fluoxetine show significant changes in personality profile. These changes may be attributed to improvement of depressive symptoms.

Tryptophan hydroxylase gene 218A/C polymorphism is not associated with depressed suicide.

Abnormalities in functioning of the central serotonergic system are believed to be involved in the pathogenesis of depressive illness and suicidal behaviour. Recently, polymorphism in the tryptophan hydroxylase (TPH) gene has been studied for association with aggression, anger-related traits and suicidal behaviour, but the results are inconclusive. The present investigation was to determine whether there are differences in genotype and allele distribution of the TPH gene 218A/C polymorphism in post-mortem brain samples from 35 depressed suicide victims and 84 control subjects of the same ethnic background. A functional polymorphism in the promoter region of 5-HT transporter gene was also re-examined in this increased sample size. No significant difference in TPH gene 218A/C polymorphism between controls and depressed suicide victims was detected. This may suggest that the TPH gene has no significant effect on suicidality in depressed subjects. In a previous study on a smaller sample we found the frequency of the long allele of 5-HT transporter gene to be higher in depressed suicide victims. In this increased sample size, both the genotype and alleles of the 5-HT transporter gene were significantly associated with completed suicide. The frequency of the L/L genotype in depressed suicide victims was almost double of that found in control group (48.6 vs. 26.2%). The odds ratio for the L allele associated with depressed suicide was 2.1 (95% CI, 1.2-3.7). The relatively small sample size does not exclude the possibility of false-positive results and the finding needs replication.