Genetics of the serotonergic system in suicidal behavior

Resilience to Early Life Adversity Effects on Stress Reactivity by Postnatal Knockdown of 5-HT 1A Autoreceptors

Early Life Adversity (ELA) predisposes to stress hypersensitivity in adulthood, but neurobiological mechanisms that can protect from long-lasting effects of ELA are poorly understood. Serotonin 1A (5HT 1A ) autoreceptors in the raphé nuclei regulate adult stress vulnerability, but if 5HT 1A could be targeted to prevent ELA effects on susceptibility to future stressors is unknown. Here, we exposed mice with postnatal knockdown of 5HT 1A autoreceptors to the limited bedding and nesting model of ELA from postnatal day (P)3-10. We then tested behavioral, neuroendocrine, neurogenic, and neuroinflammatory responses to an acute swim stress in male and female mice in adolescence (P35) and in adulthood (P56). In ELA-exposed females, adult swim stress exposure increased passive coping and despair-like behavior, corticosterone levels at baseline and after stress, and neuronal activity and corticotropin releasing hormone levels in the paraventricular nucleus of the hypothalamus. ELA also reduced neurogenesis and increased microglia activation in the ventral dentate gyrus (DG) of the hippocampus - an important mediator of individual differences in stress susceptibility. These effects of ELA were specific to females, but not males, and manifested predominantly in adulthood, but not earlier on in adolescence. Postnatal 5HT 1A autoreceptor knockdown prevented ELA effects on stress reactivity and on neurogenesis and neuroinflammation in the DG, indicating that reducing 5HT 1A autoreceptors confers resilience to ELA. Our findings demonstrate that ELA induces long-lasting and sex-specific impairments in stress reactivity and ventral DG function across development, and identify 5HT 1A autoreceptors as potential targets to prevent these persistent effects of ELA.

5-HT1A and 5-HT2B receptor interaction and co-clustering regulate serotonergic neuron excitability

Many psychiatric diseases have been associated with serotonin (5-HT) neuron dysfunction. The firing of 5-HT neurons is known to be under 5-HT1A receptor-mediated autoinhibition, but functional consequences of coexpressed receptors are unknown. Using co-immunoprecipitation, BRET, confocal, and super-resolution microscopy in hippocampal and 5-HT neurons, we present evidence that 5-HT1A and 5-HT2B receptors can form heterodimers and co-cluster at the plasma membrane of dendrites. Selective agonist stimulation of coexpressed 5-HT1A and 5-HT2B receptors prevents 5-HT1A receptor internalization and increases 5-HT2B receptor membrane clustering. Current clamp recordings of 5-HT neurons revealed that 5-HT1A receptor stimulation of acute slices from mice lacking 5-HT2B receptors in 5-HT neurons increased their firing activity trough Ca2+-activated potassium channel inhibition compared to 5-HT neurons from control mice. This work supports the hypothesis that the relative expression of 5-HT1A and 5-HT2B receptors tunes the neuronal excitability of serotonergic neurons through potassium channel regulation.

In vivo serotonin transporter and 1A receptor binding potential and ecological momentary assessment (EMA) of stress in major depression and suicidal behavior

We examined relationships between the serotonin system and stress in major depression and suicidal behavior. Twenty-five medication-free depressed participants (13 suicide attempters) underwent same-day [11C]DASB and [11C]CUMI-101 positron emission tomography (PET) imaging. Binding potential (BPND) to the serotonin transporter (5-HTT) and serotonin 1A (5-HT1A) receptor, respectively, was quantified using the NRU 5-HT atlas, reflecting distinct spatial distributions of multiple serotonin targets. Ecological momentary assessment (EMA) measured current stress over one week proximal to imaging. EMA stress did not differ between attempters and non-attempters. In all depressed participants, 5-HTT and 5-HT1A BPND were unrelated to EMA stress. There were region-specific effects of 5-HTT (p=0.002) and 5-HT1A BPND (p=0.03) in attempters vs. nonattempters. In attempters, region-specific associations between 5-HTT (p=0.03) and 5-HT1A (p=0.005) BPND and EMA stress emerged. While no post-hoc 5-HTT BPND correlations were significant, 5-HT1A BPND correlated positively with EMA stress in attempters in 9/10 regions (p-values<0.007), including the entire cortex except the largely occipital region 5. Brodmann-based regional analyses found diminished effects for 5-HTT and subcortically localized positive corrrelations between 5-HT1A and EMA stress, in attempters only. Given comparable depression severity and childhood and current stress between attempters and nonattempters, lower 5-HTT binding in attempters vs. nonattempters may suggest a biological risk marker. Localized lower 5-HTT and widespread higher 5-HT1A binding with stress among attempters specifically may suggest that a serotonergic phenotype might be a key determinant of risk or resiliency for suicidal behavior.

The Implication of 5-HT Receptor Family Members in Aggression, Depression and Suicide: Similarity and Difference

Being different multifactorial forms of psychopathology, aggression, depression and suicidal behavior, which is considered to be violent aggression directed against the self, have principal neurobiological links: preclinical and clinical evidence associates depression, aggression and suicidal behavior with dysregulation in central serotonergic (5-HT) neurotransmission. The implication of different types of 5-HT receptors in the genetic and epigenetic mechanisms of aggression, depression and suicidality has been well recognized. In this review, we consider and compare the orchestra of 5-HT receptors involved in these severe psychopathologies. Specifically, it concentrates on the role of 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2B, 5-HT_2C, 5-HT₃ and 5-HT₇ receptors in the mechanisms underlying the predisposition to aggression, depression and suicidal behavior. The review provides converging lines of evidence that: (1) depression-related 5-HT receptors include those receptors with pro-depressive properties (5-HT_2A, 5-HT₃ and 5-HT₇) as well as those providing an antidepressant effect (5-HT_1A, 5-HT_1B, 5-HT_2C subtypes). (2) Aggression-related 5-HT receptors are identical to depression-related 5-HT receptors with the exception of 5-HT₇ receptors. Activation of 5-HT_1A, 5-HT_1B, 5-HT_2A, 5-HT_2C receptors attenuate aggressiveness, whereas agonists of 5-HT₃ intensify aggressive behavior.

Mechanistic Insights into the Link between Gut Dysbiosis and Major Depression: An Extensive Review

Depression is a highly common mental disorder, which is often multifactorial with sex, genetic, environmental, and/or psychological causes. Recent advancements in biomedical research have demonstrated a clear correlation between gut dysbiosis (GD) or gut microbial dysbiosis and the development of anxiety or depressive behaviors. The gut microbiome communicates with the brain through the neural, immune, and metabolic pathways, either directly (via vagal nerves) or indirectly (via gut- and microbial-derived metabolites as well as gut hormones and endocrine peptides, including peptide YY, pancreatic polypeptide, neuropeptide Y, cholecystokinin, corticotropin-releasing factor, glucagon-like peptide, oxytocin, and ghrelin). Maintaining healthy gut microbiota (GM) is now being recognized as important for brain health through the use of probiotics, prebiotics, synbiotics, fecal microbial transplantation (FMT), etc. A few approaches exert antidepressant effects via restoring GM and hypothalamus–pituitary–adrenal (HPA) axis functions. In this review, we have summarized the etiopathogenic link between gut dysbiosis and depression with preclinical and clinical evidence. In addition, we have collated information on the recent therapies and supplements, such as probiotics, prebiotics, short-chain fatty acids, and vitamin B12, omega-3 fatty acids, etc., which target the gut–brain axis (GBA) for the effective management of depressive behavior and anxiety.

Association between TPH1 polymorphisms and the risk of suicide behavior: An updated meta-analysis of 18,398 individuals

OBJECTIVES

We aimed to examine the association of TPH1 polymorphisms with the risk of suicide behavior (SB).

DESIGN

Systematic review and meta-analysis.

METHOD

All relevant studies that evaluated the association between the A218C (rs1800532), A779C (rs1799913) and A6526G (rs4537731) polymorphisms and the susceptibility to SB published up to September 2021 were identified through a comprehensive systematic search in PubMed, Scopus, EBSCO and Science Direct electronic databases. The association between TPH1 gene polymorphisms and SB was evaluated using inherence models by odds ratio (OR) and 95% confidence interval (CI). Subgroup analyses, heterogeneity analyses, and publication bias were also tested in this meta-analysis.

RESULTS

The meta-analysis for TPH1 A218C revealed an increased risk of SB in the dominant model (OR = 1.11, 95%CI 1.01-1.22). We also observed a positive association in the allelic (OR = 1.13, 95%CI 1.05-1.21), homozygous (OR = 1.22, 95%CI 1.06-1.40), heterozygous (OR = 1.21, 95%CI 1.08-1.37) and dominant (OR = 1.21, 95%CI 1.09-1.34) inherence models with the suicide attempt. Additionally, in the heterozygous (OR = 0.84, 95%CI 0.73-0.97) and dominant (OR = 0.79, 95%CI 0.68-0.91) inherence models we detected an association with completed suicide. Based on ethnicity, an association of SB in the European population also was observed (OR = 1.29, 95%CI 1.12-1.51). However, for both A779C and A6526G polymorphisms we did not find evidence of an association with SB.

CONCLUSION

This meta-analysis suggests that the A218C polymorphism of TPH1 gene could be a possible risk factor of SB. Future large-scale studies are required to analyze the molecular mechanisms by which affect the susceptibility of developing suicide behavior.

Effects of a Cc2d1a/Freud-1 Knockdown in the Hippocampus on Behavior, the Serotonin System, and BDNF

The serotonin 5-HT_1A receptor is one of the most abundant and widely distributed brain serotonin (5-HT) receptors that play a major role in the modulation of emotions and behavior. The 5-HT_1A receptor gene (Htr1a) is under the control of transcription factor Freud-1 (also known as Cc2d1a/Freud-1). Here, using adeno-associated virus (AAV) constructs in vivo, we investigated effects of a Cc2d1a/Freud-1 knockdown in the hippocampus of C57BL/6J mice on behavior, the brain 5-HT system, and brain-derived neurotrophic factor (BDNF). AAV particles carrying the pAAV_H1-2_shRNA-Freud-1_Syn_EGFP plasmid encoding a short-hairpin RNA targeting mouse Cc2d1a/Freud-1 mRNA had an antidepressant effect in the forced swim test 5 weeks after virus injection. The knockdown impaired spatiotemporal memory as assessed in the Morris water maze. pAAV_H1-2_shRNA-Freud-1_Syn_EGFP decreased Cc2d1a/Freud-1 mRNA and protein levels. Furthermore, the Cc2d1a/Freud-1 knockdown upregulated 5-HT and its metabolite 5-hydroxyindoleacetic acid but not their ratio. The Cc2d1a/Freud-1 knockdown failed to increase mRNA and protein levels of Htr1a but diminished a 5-HT_1A receptor functional response. Meanwhile, the Cc2d1a/Freud-1 knockdown reduced Creb mRNA expression and CREB phosphorylation and upregulated cFos mRNA. The knockdown enhanced the expression of a BDNF precursor (proBDNF protein), which is known to play a crucial part in neuroplasticity. Our data indicate that transcription factor Cc2d1a/Freud-1 is implicated in the pathogenesis of depressive disorders not only via the 5-HT_1A receptor and transcription factor CREB but also through an influence on BDNF.

Comprehensive analysis of the 5-HTTLPR allelic polymorphism effect on behavioral and neurophysiological indicators of executive control in people from different ethnic groups in Siberia

The allelic polymorphism of the serotonin transporter's gene 5-HTTLPR is considered as one of the factors determining an individual genetic predisposition to the development of a wide range of affective disorders, including depression. Many studies have shown that the climatic and social conditions of people's life can have a significant impact on the connections of 5-HTTLPR with the risk of depression. The stop-signal paradigm (SSP) is an experimental method allowing evaluating an individual ability to the self-control of behavior in a changing environment. In the SSP experiment, a subject should either press one of several buttons quickly after the appearance of the target stimuli or suppress the already started movement if an inhibitory signal follows the target stimulus. The aim of this study is a research of associations between the allelic the 5-HTTLPR polymorphism and the individual scores of the personal anxiety level, as well as the behavioral and neurophysiological indicators of the ability to self-control over motor reactions in the SSP. The study was conducted among people from three ethno-regional groups: healthy Caucasoids from Novosibirsk, the Mongoloid groups of the indigenous population of the Tuva Republic and Sakha Republic (Yakutia). Genetic, ethnographic, and psychological influences on an individual's ability to control motor responses were compared. The amplitude of the premotor peak of the evoked brain potential was used as a neurophysiological marker of the person's readiness to the execution of target-directed activity. It was revealed that the frequency of the S-allele polymorphism 5-HTTLPR was significantly higher for both mongoloid groups compared to the Caucasoids. The S/S genotype was associated with an increased level of personal anxiety and at the same time with a better ability to the self-control of behavior in the SSP experiment. Anxiety level, participants' sex, ethnicity, and allelic polymorphism 5-HTTLPR had a statistically significant effect on the amplitude of the premotor readiness potential recorded under the SSP conditions in the frontal and parietal-occipital cortical regions. Our data support the hypothesis that the S/S genotype of the 5-HTTLPR polymorphism may be associated with more success in adapting to the climatic conditions connected with high life risk in comparison to L/L and L/S genotypes.

RNA editing of the 5-HT2C receptor in the central nucleus of the amygdala is involved in resilience behavior

Post-traumatic-stress-disorder (PTSD) is a stress-related condition that may develop after exposure to a severe trauma-event. One of the core brain areas that is considered to be a key regulatory region of PTSD is the amygdala. Specifically, the central amygdala (CeA) is involved in emotion processing and associative fear learning memory, two main circuits involved in PTSD. Long term dysregulation of trauma-related emotional processing may be caused by neuroadaptations that affect gene expression. The adenosine-(A) to-inosine (I) RNA editing machinery is a post-transcriptional process that converts a genomic encoded A to I and is critical for normal brain function and development. Such editing has the potential to increase the transcriptome diversity, and disruption of this process has been linked to various central nervous system disorders. Here, we employed a unique animal model to examine the possibility that the RNA editing machinery is involved in PTSD. Detection of RNA editing specifically in the CeA revealed changes in the editing pattern of the 5-HT2C serotonin receptor (5-HT2CR) transcript accompanied by dynamic changes in the expression levels of the ADAR family enzymes (ADAR and ADARb1). Deamination by ADAR and ADARb1 enzymes induces conformational changes in the 5-HT2CR that decrease the G-protein-coupling activity, agonist affinity, and thus serotonin signaling. Significantly, a single intra-CeA administration of a 5-HT2CR pharmacological antagonist produced a robust alleviation of PTSD-like behaviors (that was maintained for three weeks) as well as single systemic treatment. This work may suggest the way to a new avenue in the understanding of PTSD regulation.

[The role of genetic factors in the development of suicidal behavior in individuals with dependence on synthetic cathinones]

OBJECTIVE

To identify polymorphisms in the genes of dopaminergic and serotonergic systems associated with the risk of suicidal behavior in individuals with dependence on synthetic cathinones.

MATERIAL AND METHODS

One hundred and eighty-two men with the diagnosis of Substance dependence (ICD-10 F15) tested positive for metabolites of synthetic cathinones (a-PVP, MDPV) in the urine were studied. Genotyping was performed for rs1800497 DRD2, rs4646984 DRD4, VNTR 40 b.p. SLC6A3, rs27072 SLC6A3, rs6313 HTR2A and rs6296 HTR1B using PCR and RFLP technique.

RESULTS AND CONCLUSION

It was found that the genes of the serotonergic system HTR2A and HTR1B are predictors of the development of some endophenotypes of suicidal behavior in individuals with dependence on synthetic cathinones.

Association of TPH1 and serotonin transporter genotypes with treatment response for suicidal ideation: a preliminary study

Variants in three genes coding for components of the serotonergic system, the tryptophan hydroxylase 1 (TPH1) rs1799913, serotonin transporter (SLC6A4) 5-HTTLPR, and serotonin receptor 2A (HTR2A) rs6311, were evaluated for association with suicidal ideation (SI) and with recovery from SI in a psychiatric inpatient population. Five hundred and eighty-two adult inpatients, including 390 patients who had SI, collected from December 2012 to April 2016 were assessed. SI recovery, calculated as change in SI between the first two-week period after admission and weeks 5 and 6, was appraised for association with the three variants. In this preliminary study, both TPH1 and 5-HTTLPR genotypes were associated with recovery (TPH1: recessive model, increased recovery with AC genotype, P = 0.026; additive model, increased recovery with AC genotype, P = 0.037; 5-HTTLPR: recessive model, increased recovery with AC, P = 0.043). When patients with comorbid alcohol use disorder (AUD) were removed, given that TPH1 has been associated with alcoholism, the associations of those recovered from SI with TPH1 rs1799913 remained significant for the additive (increased recovery with AC, P = 0.045) and recessive (increased recovery with C-carriers, P = 0.008) models, and with 5-HTTLPR using the dominant model (increased recovery with S'S', P = 0.016). In females, an association of SI recovery with TPH1 rs1799913 was found using a recessive model (increased recovery with C-carriers, P = 0.031), with 5-HTTLPR using additive (increased recovery with L'S', P = 0.048) and recessive (increased recovery with S'S', P = 0.042) models. Additionally, an association of SI with TPH1 rs1799913 was found in females using both additive (increased risk in AC, P = 0.033) and recessive (increased risk in C-carriers, P = 0.043) models, and with 5-HTTLPR using a recessive model (increased risk in S'S', P = 0.030). This study provides evidence that variation in the TPH1 and serotonin transporter genes play key roles in moderating recovery from SI during treatment in an inpatient psychiatric clinic.

Calcium-binding proteins are altered in the cerebellum in schizophrenia

Alterations in the cortico-cerebellar-thalamic-cortical circuit might underlie the diversity of symptoms in schizophrenia. However, molecular changes in cerebellar neuronal circuits, part of this network, have not yet been fully determined. Using LC-MS/MS, we screened altered candidates in pooled grey matter of cerebellum from schizophrenia subjects who committed suicide (n = 4) and healthy individuals (n = 4). Further validation by immunoblotting of three selected candidates was performed in two cohorts comprising schizophrenia (n = 20), non-schizophrenia suicide (n = 6) and healthy controls (n = 21). We found 99 significantly altered proteins, 31 of them previously reported in other brain areas by proteomic studies. Transport function was the most enriched category, while cell communication was the most prevalent function. For validation, we selected the vacuolar proton pump subunit 1 (VPP1), from transport, and two EF-hand calcium-binding proteins, calmodulin and parvalbumin, from cell communication. All candidates showed significant changes in schizophrenia (n = 7) compared to controls (n = 7). VPP1 was altered in the non-schizophrenia suicide group and increased levels of parvalbumin were linked to antipsychotics. Further validation in an independent cohort of non-suicidal chronic schizophrenia subjects (n = 13) and non-psychiatric controls (n = 14) showed that parvalbumin was increased, while calmodulin was decreased in schizophrenia. Our findings provide evidence of calcium-binding protein dysregulation in the cerebellum in schizophrenia, suggesting an impact on normal calcium-dependent synaptic functioning of cerebellar circuits. Our study also links VPP1 to suicide behaviours, suggesting a possible impairment in vesicle neurotransmitter refilling and release in these phenotypes.

Victims of bullying in childhood and suicide attempts in adulthood

Purpose

To examine whether self-reported exposure to bullying during childhood is associated with suicide attempts over the life course, and if so, what mechanisms could account for this relationship.

Subjects and methods

A random probability sample comprising 7461 respondents was interviewed for the 2007 survey of psychiatric morbidity of adults in Great Britain. Survey respondents were asked about suicidal attempts and whether they were bullied in childhood.

Results

Recall of being bullied in childhood decreased with age from 25% of 16–24-year-olds to 4% among those 75 or over with few differences in the proportions between men and women. Bullying co-occurred with several victimisation experiences including sexual abuse and severe beatings and with running away from home. Even after controlling for lifetime factors known to increase the risk of suicidal behaviour, adults who reported bullying in childhood were still more than twice as likely as other adults to attempt suicide later in life.

Discussion

Being the victim of bullying involves the experience of suffering a defeat and humiliation that in turn could lead to entrapment, hopelessness, depression and suicidal behaviour.

Conclusions

Bullying is already known to be associated with substantial distress and other negative consequences and this further evidence of a strong correlation with the risk of suicide in later life should increase further the motivation of society, services and citizens to act decisively to reduce bullying in childhood.

Therapeutic Duration and Extent Affect the Effect of Moxibustion on Depression-Like Behaviour in Rats via Regulating the Brain Tryptophan Transport and Metabolism

Moxibustion has been widely accepted as an alternative therapy for major depressive disease (MDD). However, the efficacy of moxibustion treatment on MDD is highly variable because of its irregular operation. This study was designed to investigate how therapeutic duration and extent influence the anti-depression effect of moxibustion and the underlying mechanism involved. Rats with lipopolysaccharide-induced depression-like behavior were treated by moxibustion treatment. The anti-depression effect was determined by forced swimming test and open field test. Tryptophan (Trp) transport and its metabolism to serotonin (5-HT) and kynurenine (Kyn) were evaluated to explore the anti-depression mechanism. The results showed that moxibustion treatment could alleviate the depression-like behavior in rats. Trp transport and 5-HT generation were significantly increased, and the Trp-Kyn pathway was moderately inhibited by moxibustion. Prolonged therapy could be beneficial to the anti-depression effect by promoting the brain uptake of Trp and shifting the Trp metabolism to 5-HT. An enhanced therapeutic extent could increase 5-HT generation. In conclusion, this study determined that the anti-depression effect of moxibustion involves improved Trp transport and metabolism. The therapeutic duration benefits antidepressant effects, but the complex influence of the therapeutic extent on moxibustion efficacy requires further studies.

Brain region-specific alterations of RNA editing in PDE8A mRNA in suicide decedents

Phosphodiesterases (PDE) are key modulators of signal transduction and are involved in inflammatory cell activation, memory and cognition. There is a two-fold decrease in the expression of phosphodiesterase 8A (PDE8A) in the temporal cortex of major depressive disorder (MDD) patients. Here, we studied PDE8A mRNA-editing profile in two architectonically distinct neocortical regions in a clinically well-characterized cohort of age- and sex-matched non-psychiatric drug-free controls and depressed suicide decedents. By using capillary electrophoresis single-stranded conformational polymorphism (CE-SSCP), a previously validated technique to identify A-to-I RNA modifications, we report the full editing profile of PDE8A in the brain, including identification of two novel editing sites. Editing of PDE8A mRNA displayed clear regional difference when comparing dorsolateral prefrontal cortex (BA9) and anterior cingulate cortex (BA24). Furthermore, we report significant intra-regional differences between non-psychiatric control individuals and depressed suicide decedents, which could discriminate the two populations. Taken together, our results (i) highlight the importance of immune/inflammatory markers in major depressive disorder and suicide and (ii) establish a direct relationship between A-to-I RNA modifications of peripheral markers and A-to-I RNA editing-related modifications in brain. This work provides the first immune response-related brain marker for suicide and could pave the way for the identification of a blood-based biomarker that predicts suicidal behavior.

Effect of 5-HTTLPR on current source density, connectivity, and topological properties of resting state EEG networks

The S allele of serotonin transporter gene (5-HTTLPR) has been found to increase the risk of depression and other mental health problems, but some evidence suggests that S-allele carriers outperform subjects carrying the long allele in an array of cognitive tasks. Evidence linking this polymorphism with individual variation in electrophysiological properties of resting state brain networks is very limited. This study investigated the effect of 5-HTTLPR polymorphism on EEG current source density, connectivity, and topological properties of resting state networks. We collected genetic and resting state EEG data in 113 Caucasians. As compared to L-homozygotes, S-allele carriers showed lower current source density and connectivity in most frequency bands in areas overlapping with the default mode and emotion regulation regions. The analysis of graph-theoretical measures showed that S-allele carriers, as compared to L-homozygotes, have less optimal topological properties of brain networks in theta, but more optimal in alpha band. This dissociation may reflect the predisposition to emotional disorders, which is inherent to S-allele carriers, and, on the other hand, their superior functioning in some cognitive domains.

Molecular network-selected pharmacogenomics in a case of bipolar spectrum disorder

Personal genomic analysis was used for molecular diagnosis and pharmacogenomics in a 53-year-old female suffering from alternating depressive and dysphoric episodes. A total of 52 genes and 108 SNPs were analyzed in the whole genome. Results from the pharmacogenomic analysis were consistent with the pharmacological history and indicate mutations associated with low monoaminergic tone, but also a hyperactive 5HT2A receptor, a feature that associates to a high probability of developing a bipolar condition, especially under 5-hydroxytryptamine potentiating pharmacology. This aligns with the patient developing dysphoria with high clomipramine. The pharmacokinetic genomics pointed out to some absorption, distribution, metabolism, and excretion (ADME) alterations that can lower or nullify drug's activity. A personalized regimen was proposed, with a positive outcome after 1 year.

Association between serotonin transporter gene polymorphisms and increased suicidal risk among HIV positive patients in Uganda

BACKGROUND

Persons living with HIV/AIDS (PLWHA) are at an increased risk of suicide. Increased suicidal risk is a predictor of future attempted and completed suicides and has been associated with poor quality of life and poor adherence with antiretroviral therapy. Clinical risk factors have low predictive value for suicide, hence the interest in potential neurobiological correlates and specific heritable markers of suicide vulnerability. The serotonin transporter gene has previously been implicated in the aetiology of increased suicidal risk in non-HIV infected study populations and its variations may provide a platform for identifying genetic risk for suicidality among PLWHA. The present cross-sectional study aimed at identifying two common genetic variants of the serotonin transporter gene and their association with increased suicidal risk among human immunodeficiency virus (HIV)-positive adults in Uganda.

RESULTS

The prevalence of increased suicidal risk (defined as moderate to high risk suicidality on the suicidality module of the Mini Neuropsychiatric Interview (M.I.N.I) was 3.3% (95% CI, 2.0-5.3). The 5-HTTLPR was found to be associated with increased suicidal risk before Bonferroni correction (p-value = 0.0174). A protective effect on increased suicidal risk was found for the 5-HTTLPR/rs25531 S A allele (p-value = 0.0046)- which directs reduced expression of the serotonin transporter gene (5-HTT).

CONCLUSION

The S A allele at the 5-HTTLPR/rs25531 locus is associated with increased suicidal risk among Ugandan PLWHA. Further studies are needed to validate this finding in Ugandan and other sub-Saharan samples.

Stress inhibits tryptophan hydroxylase expression in a rat model of depression

Serotonin (5-hydroxytryptamine, 5-HT) dysfunction is associated with the pathophysiology of depression. Tryptophan hydroxylase (TPH), the rate-limiting enzyme in 5-HT biosynthesis, is believed to have essential role in many mental disorders, including depression. In the present study, we generated a rat model of depression by exposing the animals to stress, and the rats were then treated with paroxetine. The results indicated that the concentration of 5-HT in the brain and liver tissues were significantly lower in the rat model of depression than in healthy or treated rats. Immunohistochemical analyses of TPH1/2 showed less TPH1 and TPH2 expression, specifically TPH2, in the brain, liver and kidney of the depressive rats than in the healthy rats; In addition, the two TPH isoforms, TPH1 and TPH2, had different spatial distributions,the mRNAs of the TPH1/2 genes were significantly decreased and TPH1/2 were highly methylated in the depressive model rat, but treatment with paroxetine ameliorated the expression and methylation of TPH1/2. All together, stress was able to inhibit expression of TPH1/2 in brain tissue and decrease concentration of 5-HT, the mechanism maybe involve in increasing the methylation of TPH2 genes promoter; Paroxetine has a role in confronting the effect of stress in depressive rat model.

Gintonin attenuates depressive-like behaviors associated with alcohol withdrawal in mice

BACKGROUND

Panax ginseng Meyer extracts have been used to improve mood and alleviate symptoms of depression. However, little is known about the extracts' active ingredients and the molecular mechanisms underlying their reported anti-depressive effects.

METHODS

Gintonin is an exogenous lysophosphatidic acid (LPA) receptor ligand isolated from P. ginseng. BON cells, an enterochromaffin cell line, and C57BL/6 mice were used to investigate whether gintonin stimulates serotonin release. Furthermore, the effects of gintonin on depressive-like behaviors following alcohol withdrawal were evaluated using the forced swim and tail suspension tests.

RESULTS

Treatment of BON cells with gintonin induced a transient increase in the intracellular calcium concentration and serotonin release in a concentration- and time-dependent manner via the LPA receptor signaling pathway. Oral administration of the gintonin-enriched fraction (GEF) induced an increase in the plasma serotonin concentration in the mice. Oral administration of the GEF in mice with alcohol withdrawal decreased the immobility time in two depression-like behavioral tests and restored the alcohol withdrawal-induced serotonin decrease in plasma levels.

LIMITATIONS

We cannot exclude the possibility that the gintonin-mediated regulation of adrenal catecholamine release in the peripheral system, and acetylcholine and glutamate release in the central nervous system, could also contribute to the alleviation of depressive-like behaviors.

CONCLUSION

The GEF-mediated attenuation of depressive-like behavior induced by alcohol withdrawal may be mediated by serotonin release from intestinal enterochromaffin cells. Therefore, the GEF might be responsible for the ginseng extract-induced alleviation of depression-related symptoms.

Sexual Trauma, the Dopamine D4 Receptor, and Suicidal Ideation Among Hospitalized Adolescents: A Preliminary Investigation

Though an association exists between sexual trauma and adolescent suicidal thoughts and behaviors (STBs), not all adolescents with a sexual assault history develop STBs. The present study examined whether carrier status of the DRD4 VNTR polymorphism (DRD4 L vs. DRD4S) moderated the relationship between sexual trauma and STBs in a sample of psychiatrically hospitalized adolescents. A total of 76 psychiatrically hospitalized adolescents provided saliva samples for genotyping procedures and completed assessment measures. Using hierarchical regression analyses, results indicated that DRD4 L carriers with a sexual trauma history reported significantly more severe suicidal ideation than DRD4S homozygotes. There was no interaction evident for the prediction of suicide attempts. To our knowledge, this is the first study to provide preliminary support for synergistic effects of sexual trauma, DRD4, and severity of SI in adolescents. Further studies of the relationship between sexual trauma, DRD4, and STBs utilizing larger samples are needed.

Emerging RNA editing biomarkers will foster drug development

Unanticipated adverse drug reactions (ADRs) on the central nervous system are a major cause of clinical attrition and market withdrawal. Current practices for their prospective assessment still lean on extensive analysis of rodent behaviour despite their highly controversial predictive value. Human-derived in vitro models that objectively quantify mechanism-related biomarkers can greatly contribute to better ADR prediction at early developmental stages. Adenosine-to-inosine RNA editing constitutes a physiological cellular process that translates environmental cues by regulating protein function at the synaptic level in health and disease. Robust solutions based on NGS-based quantification of RNA editing biomarkers have emerged to predict the likelihood of treatment-related suicidal ideation and behaviour allowing cost-effective high-throughput drug screening as a strategy for risk mitigation.

[Seasons, circadian rhythms, sleep and suicidal behaviors vulnerability]

INTRODUCTION

Suicidal behaviors are common in the general population and are so a major public health problem. In order to improve suicide prevention and to reduce the mortality by suicide, it appears essential to better identify suicide risk factors. Seasonality, circadian rhythms and sleep abnormalities have been already associated with numerous psychiatric disorders. This review aimed to characterize the associations between seasonality, circadian rhythms, sleep and suicidal behaviors including suicide attempts and completed suicides.

METHODS

We conducted a literature search between 1973 and 2015 in PubMed databases using the following terms: ("suicide" OR "suicidality" OR "suicide attempts" OR "suicidal behavior") AND ("circadian rhythms" OR "seasons" OR "sleep").

RESULTS

Many studies confirm a specific seasonality for suicide with a higher peak of suicides in spring for both sex and a lower peak in autumn especially for women. This distribution seems to correlate with depressive symptoms (especially for the autumn peak), gender and different types of suicide. Regarding gender and type of suicide differences, males more commonly commit violent suicide with a higher rate of suicides in spring. Suicide behaviors appear to be influenced by climatic and biological factors like sunshine, daylight cycles, temperature, air pollutants, viruses, parasites and aeroallergens. Circadian variations exist in suicide rates depending on age with a morning peak for elder and an evening peak for youth. In addition, completed suicide peak in early morning whereas suicide attempts peak rather in later afternoon. Several biomarkers dysregulation like melatonin, serotonin and cortisol may be implicated in suicide circadian variations. Furthermore, specific sleep disorders like insomnia, nightmares and sleep deprivation are common risk factors of suicide and possibly independently of the presence of depressive symptoms. Finally, the efficacy of chronotherapeutics (such as luminotherapy, dark therapy, sleep deprivation and melatonin drugs) has been suggested in the reduction of suicidal behaviors.

CONCLUSION

The suicide seasonality is very well documented showing a main peak in spring and another one in autumn. A suicide circadian distribution also exists depending of the suicidal behavior intensity and of the age. Numerous sleep disorders are also suicide risk factors and can be treated with chronotherapeutics. A better identification of seasonality, circadian rhythms and sleep abnormalities in suicidal behaviors could allow a better prevention in suicidal attempts and a reduction in death by suicide.

Region-specific alterations of A-to-I RNA editing of serotonin 2c receptor in the cortex of suicides with major depression

Brain region-specific abnormalities in serotonergic transmission appear to underlie suicidal behavior. Alterations of RNA editing on the serotonin receptor 2C (HTR2C) pre-mRNA in the brain of suicides produce transcripts that attenuate 5-HT2CR signaling by impairing intracellular G-protein coupling and subsequent intracellular signal transduction. In brain, the distribution of RNA-editing enzymes catalyzing deamination (A-to-I modification) shows regional variation, including within the cerebral cortex. We tested the hypothesis that altered pre-mRNA 5-HT2CR receptor editing in suicide is region-specific. To this end, we investigated the complete 5-HT2CR mRNA-editing profile in two architectonically distinct cortical areas involved in mood regulation and decision-making in a clinically well-characterized cohort of age- and sex-matched non-psychiatric drug-free controls and depressed suicides. By using an original biochemical detection method, that is, capillary electrophoresis single-stranded conformational polymorphism (CE-SSCP), we corroborated the 5-HT2CR mRNA-editing profile previously described in the dorsolateral prefrontal cortex (Brodmann area 9 (BA9)). Editing of 5-HT2CR mRNA displayed clear regional difference when comparing dorsolateral prefrontal cortex (BA9) and anterior cingulate cortex (BA24). Compared with non-psychiatric control individuals, alterations of editing levels of 5-HT2CR mRNA were detected in both cortical areas of depressed suicides. A marked increase in editing on 5-HT2CR was especially observed in the anterior cingulate cortex in suicides, implicating this cortical area in suicide risk. The results suggest that region-specific changes in RNA editing of 5-HT2CR mRNA and deficient receptor function likely contribute to the etiology of major depressive disorder or suicide.

The investigation of factors related to suicide attempts in Southeastern Turkey

BACKGROUND

Suicide is an important health problem in Turkey as it is in all regions of the world. Suicidal behavior has multiple causes, which are broadly divided into those related to proximal stressors and those due to predisposition. Suicide statistics may be associated with mental health disorders, which are among the foremost predictors of suicide attempts. More than 90% of patients who commit suicide have a diagnosable psychiatric disorder, usually a major depressive disorder. Other major risk factors for suicide attempts are history of suicide attempts in the family, stressful life events, sleep disturbances, poor income, unemployment, severity of symptoms of depression, and anxiety. Sleep is a complex phenomenon. Sleep disturbances can therefore be contributed to the emergence of suicidal behavior allowing for the possibility of predicting future suicides.

METHODS

We evaluated 106 patients who were admitted after suicide attempts to the Department of Psychiatry at Dicle University Faculty of Medicine. The recruited subjects were assessed by Structured Clinical Interview for DSM-IV Axis I disorders, and the intensity of symptoms was evaluated using the Beck Anxiety Inventory, Hamilton Depression Rating Scale, and Pittsburgh Sleep Quality Index. The mean values of the subjects attempting multiple and single suicides were compared using appropriate inferential statistical tests.

RESULTS

Most suicide attempts are believed to be preventable. Our results revealed that a great variety of risk factors are associated with an increased risk for multiple suicide attempts. Most of these attempts appeared to be spontaneous and impulsive rather than planned. In particular, this study highlights the importance of previous suicide attempts, history of suicide in the family, history of stressful life events in the previous 6 months, poor income, unemployment, sleep disturbances, severe hopelessness with depression, and coexisting symptoms of anxiety as risk factors.

CONCLUSION

The first step in prevention of suicides is doubtlessly strong and reliable communication, due to the fact that the majority of subjects who commit suicide have had contact with a health professional during the month before the suicide.

The Supreme Court of Canada Ruling on Physician-Assisted Death: Implications for Psychiatry in Canada

On February 6, 2015, the Supreme Court of Canada ruled that the prohibition of physician-assisted death (PAD) was unconstitutional for a competent adult person who "clearly consents to the termination of life" and has a "grievous and irremediable (including an illness, disease, or disability) condition that causes enduring suffering that is intolerable to the individual in the circumstances of his or her condition." The radically subjective nature of this ruling raises important questions about who will be involved and how this practice might be regulated. This paper aims to stimulate discussion about psychiatry's role in this heretofore illegal practice and to explore how psychiatry might become involved in end-of-life care in a meaningful, patient-centred way. First, I will review existing international legislation and professional regulatory standards regarding psychiatry and PAD. Second, I will discuss important challenges psychiatry might face regarding capacity assessment, the notion of rational suicide, and the assessment of suffering.

The emerging field of retinal electrophysiological measurements in psychiatric research: A review of the findings and the perspectives in major depressive disorder

Major depressive disorder (MDD) is a severe mental illness leading to long-term disabilities. One of the current challenges in psychiatric research is to develop new approaches to investigate the pathophysiology of MDD and monitor drug response in order to provide better therapeutic strategies to the patients. Since the retina is considered as part of the central nervous system, it was suggested that it constitutes an appropriate site to investigate mental illnesses. In the past years, several teams assessed the retinal function of patients with mood disorders and many relevant abnormalities have been reported. Investigation of the retinal electrophysiological abnormalities in MDD remains a young emerging field, but we believe that the current findings are very promising and we argue that objective retinal electrophysiological measurements may eventually become relevant tools to investigate the pathophysiology of MDD. Here, we review the retinal abnormalities detected with objective electrophysiological measurements such as the flash electroretinogram (fERG), the pattern electroretinogram (PERG) and the electrooculogram (EOG) in patients with MDD. We discuss how these changes might reflect the pathophysiology of MDD in both clinical and scientific points of view, according especially to the monoamine neurotransmission deficiency hypothesis. We also discuss the technical details that must be taken into consideration for a potential use of the objective retinal electrophysiological measurements as tools to investigate the pathophysiology of MDD.

Evaluation of psychiatric and genetic risk factors among primary relatives of suicide completers in Delhi NCR region, India

Suicide as a public health problem is studied worldwide and association of psychiatric and genetic risk factors for suicidal behavior are the point of discussion in studies across different ethnic groups. The present study is aimed at evaluating psychiatric and genetic traits among primary relatives of suicide completer families in an urban Indian population. Bi-variate analysis shows significant increase in major depression (PHQ and Hamilton), stress, panic disorder, somatoform disorder and suicide attemptamong primary compared to other relatives. Sib pair correlations also reveal significant results for major depression (Hamilton), stress, suicide attempt, intensity of suicide ideation and other anxiety syndrome. 5-HTTLPR, 5-HTT (Stin2) and COMT risk alleles are higher among primary relatives, though statistically insignificant. Backward conditional logistic regression analysis show only independent variable, Depression (Hamilton) made a unique statistically significant contribution to the model in primary relatives.

Methylation of the tryptophan hydroxylase‑2 gene is associated with mRNA expression in patients with major depression with suicide attempts

Tryptophan hydroxylase-2 (TPH2) contributes to alterations in the function of neuronal serotonin (5-HT), which are associated with various psychopathologies, including major depressive disorder (MDD) or suicidal behavior. The methylation of a single CpG site in the promoter region of TPH2 affects gene expression. Suicide and MDD are strongly associated and genetic factors are at least partially responsible for the variability in suicide risk. The aim of the present study was to investigate whether variations in TPH2 methylation in peripheral blood samples may predispose patients with MDD to suicide attempts. TPH2 mRNA expression levels differed significantly between 50 patients with MDD who had attempted suicide (MDD + suicide group) and 75 control patients with MDD (MDD group); TPH2 expression levels were significantly decreased (P=0.0005) in the patients who had attempted suicide. Furthermore, the frequency of TPH2 methylation was 36.0% in the MDD + suicide group, while it was 13.0% in the MDD group. The results of the present study demonstrated that methylation in the promoter region of TPH2 significantly affected the mRNA expression levels of TPH2, thus suggesting that methylation of the TPH2 promoter may silence TPH2 mRNA expression in MDD patients with or without suicidal behavior. In addition, there was a significant correlation between the methylation status of the TPH2 promoter and depression, hopelessness and cognitive impairment in the MDD + suicide group. In conclusion, the present study demonstrated that TPH2 expression was regulated by DNA methylation of the TPH2 promoter region in patients with MDD.

Serum triglycerides, but not cholesterol or leptin, are decreased in suicide attempters with mood disorders

BACKGROUND

Many peripheral biomarkers, including low cholesterol and its fractions, have been examined to identify suicidal behavior. Herein, we assessed serum lipid profile and some proteins putatively associated with suicidal behavior in subjects with mood disorder (bipolar disorder or major depressive disorder) with a recent suicide attempt and with no lifetime history of suicide attempts.

METHODS

Fifty subjects had presented an episode of attempted suicide during the last 15 days, and 36 subjects had no history of any suicide attempt. We measured total cholesterol, HDL, LDL and triglycerides as well as serum leptin, brain-derived neurotrophic factor (BDNF), S100B and C-reactive protein (CRP).

RESULTS

Individuals that had attempted suicide presented decreased body mass index (BMI) and waist circumference. After adjusting for these confounders, we found that triglycerides were decreased in attempted suicide subjects. We found no differences among total cholesterol, LDL, and HDL or leptin, S100B, CRP and BDNF.

LIMITATIONS

This is a cross-sectional study, and we cannot therefore assess whether a decrease in triglycerides caused a mood episode with suicidal ideation that led to a suicide attempt or if the presence of a mood episode originated a loss of appetite and consequent loss of weight, therefore decreasing triglyceride levels.

CONCLUSIONS

These results do not support the hypothesis that lower levels of cholesterol are associated with suicidal behavior in a mood disorder sample. However, our data support the idea that adiposity is differentiated in these patients (reduced BMI, waist circumference and serum triglycerides), which could lead to an altered communication between the adipose tissue and brain.

Transcriptional dys-regulation in anxiety and major depression: 5-HT1A gene promoter architecture as a therapeutic opportunity

The etiology of major depression remains unclear, but reduced activity of the serotonin (5-HT) system remains implicated and treatments that increase 5-HT neurotransmission can ameliorate depressive symptoms. 5-HT1A receptors are critical regulators of the 5- HT system. They are expressed as both presynaptic autoreceptors that negatively regulate 5-HT neurons, and as post-synaptic heteroreceptors on non-serotonergic neurons in the hippocampus, cortex, and limbic system that are critical to mediate the antidepressant actions of 5-HT. Thus, 5-HT1A auto- and heteroreceptors have opposite actions on serotonergic neurotransmission. Because most 5-HT1A ligands target both auto- and heteroreceptors their efficacy has been limited, resulting in weak or unclear responses. We propose that by understanding the transcriptional regulation of the 5-HT1A receptor it may be possible to regulate its expression differentially in raphe and projection regions. Here we review the transcriptional architecture of the 5-HT1A gene (HTR1A) with a focus on specific DNA elements and transcription factors that have been shown to regulate 5-HT1A receptor expression in the brain. Association studies with the functional HTR1A promoter polymorphism rs6295 suggest a new model for the role of the 5-HT1A receptor in susceptibility to depression involving early deficits in cognitive, fear and stress reactivity as stressors that may ultimately lead to depression. We present evidence that by targeting specific transcription factors it may be possible to oppositely regulate 5-HT1A auto- and heteroreceptor expression, synergistically increasing serotonergic neurotransmission for the treatment of depression.

Monoamine-sensitive developmental periods impacting adult emotional and cognitive behaviors

Development passes through sensitive periods, during which plasticity allows for genetic and environmental factors to exert indelible influence on the maturation of the organism. In the context of central nervous system development, such sensitive periods shape the formation of neurocircuits that mediate, regulate, and control behavior. This general mechanism allows for development to be guided by both the genetic blueprint as well as the environmental context. While allowing for adaptation, such sensitive periods are also vulnerability windows during which external and internal factors can confer risk to disorders by derailing otherwise resilient developmental programs. Here we review developmental periods that are sensitive to monoamine signaling and impact adult behaviors of relevance to psychiatry. Specifically, we review (1) a serotonin-sensitive period that impacts sensory system development, (2) a serotonin-sensitive period that impacts cognition, anxiety- and depression-related behaviors, and (3) a dopamine- and serotonin-sensitive period affecting aggression, impulsivity and behavioral response to psychostimulants. We discuss preclinical data to provide mechanistic insight, as well as epidemiological and clinical data to point out translational relevance. The field of translational developmental neuroscience has progressed exponentially providing solid conceptual advances and unprecedented mechanistic insight. With such knowledge at hand and important methodological innovation ongoing, the field is poised for breakthroughs elucidating the developmental origins of neuropsychiatric disorders, and thus understanding pathophysiology. Such knowledge of sensitive periods that determine the developmental trajectory of complex behaviors is a necessary step towards improving prevention and treatment approaches for neuropsychiatric disorders.

Mood disorders

Mood disturbances, especially depressive disorders, are the most frequent neuropsychiatric complication of traumatic brain injury (TBI). These disorders have a complex clinical presentation and are highly comorbid with anxiety, substance misuse, and other behavioral alterations such as impulsivity and aggression. Furthermore, once developed, mood disorders tend to have a chronic and refractory course. Thus, the functional repercussion of these disorders is huge, affecting the rehabilitation process and the long-term outcome of TBI patients. The pathophysiology of mood disorders involves the interplay of factors that precede trauma (e.g., genetic vulnerability and previous psychiatric history), factors that pertain to the traumatic injury itself (e.g., type, extent, and location of brain damage) and factors that influence the recovery process (e.g., family and social support). It is hardly surprising that mood disorders are associated with structural and functional changes of neural circuits linking brain areas specialized in emotional processing such as the prefrontal cortex, basal ganglia, and amygdala. In turn, the onset of mood disorders may contribute to further prefrontal dysfunction among TBI patients. Finally, in spite of the prevalence and impact of these disorders, there have been relatively few rigorous studies of therapeutic options. Development of treatment strategies constitutes a priority in this field of research.

Serotonin: a never-ending story

The neurotransmitter serotonin is an evolutionary ancient molecule that has remarkable modulatory effects in almost all central nervous system integrative functions, such as mood, anxiety, stress, aggression, feeding, cognition and sexual behavior. After giving a short outline of the serotonergic system (anatomy, receptors, transporter) the author's contributions over the last 40 years in the role of serotonin in depression, aggression, anxiety, stress and sexual behavior is outlined. Each area delineates the work performed on animal model development, drug discovery and development. Most of the research work described has started from an industrial perspective, aimed at developing animals models for psychiatric diseases and leading to putative new innovative psychotropic drugs, like in the cases of the SSRI fluvoxamine, the serenic eltoprazine and the anxiolytic flesinoxan. Later this research work mainly focused on developing translational animal models for psychiatric diseases and implicating them in the search for mechanisms involved in normal and diseased brains and finding new concepts for appropriate drugs.

Gender differences in association between serotonin transporter gene polymorphism and resting-state EEG activity

Human brain oscillations represent important features of information processing and are highly heritable. Gender has been observed to affect association between the 5-HTTLPR (serotonin-transporter-linked polymorphic region) polymorphism and various endophenotypes. This study aimed to investigate the effects of 5-HTTLPR on the spontaneous electroencephalography (EEG) activity in healthy male and female subjects. DNA samples extracted from buccal swabs and resting EEG recorded at 60 standard leads were collected from 210 (101 men and 109 women) volunteers. Spectral EEG power estimates and cortical sources of EEG activity were investigated. It was shown that effects of 5-HTTLPR polymorphism on electrical activity of the brain vary as a function of gender. Women with the S/L genotype had greater global EEG power compared to men with the same genotype. In men, current source density was markedly different among genotype groups in only alpha 2 and alpha 3 frequency ranges: S/S allele carriers had higher current source density estimates in the left inferior parietal lobule in comparison with the L/L group. In women, genotype difference in global power asymmetry was found in the central-temporal region. Contrasting L/L and S/L genotype carriers also yielded significant effects in the right hemisphere inferior parietal lobule and the right postcentral gyrus with L/L genotype carriers showing lower current source density estimates than S/L genotype carriers in all but gamma bands. So, in women, the effects of 5-HTTLPR polymorphism were associated with modulation of the EEG activity in a wide range of EEG frequencies. The significance of the results lies in the demonstration of gene by sex interaction with resting EEG that has implications for understanding sex-related differences in affective states, emotion and cognition.

N-(4-[(18)F]-fluoropyridin-2-yl)-N-{2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl}carboxamides as analogs of WAY100635. New PET tracers of serotonin 5-HT(1A) receptors

N-(4-[(18)F]-Fluoropyridin-2-yl)-N-{2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl}-carboxamides were prepared by labeling their 4-nitropyridin-2-yl precursors through nitro substitution by the (18)F anion. In vitro and in vivo tests showed that the cyclohexanecarboxamide derivative is a reversible, selective and high affinity 5-HT1A receptor antagonist (IC50 = 0.29 nM, ki = 0.18 nM) with high brain uptake, slow brain clearance and stability to defluorination when compared with conventional standards. This PET radioligand is a promising candidate for an improved in vivo quantification of 5-HT1A receptors in neuropsychiatric disorders.

Mood disorders after TBI

In this article, we examine the epidemiology and risk factors for the development of the most common mood disorders observed in the aftermath of TBI: depressive disorders and bipolar spectrum disorders. We describe the classification approach and diagnostic criteria proposed in the fifth edition of the Diagnostic and Statistical Manual for Mental Disorders. We also examine the differential diagnosis of post-TBI mood disorders and describe the mainstay of the evaluation process. Finally, we place a special emphasis on the analysis of the different therapeutic options and provide guidelines for the appropriate management of these conditions.

Study on genes of the serotonergic system and suicidal behavior: protocol for a case-control study in Mexican population

BACKGROUND

Suicidal behavior is a leading cause of injury and death worldwide. Several studies have provided a possible relationship between genetic factors and suicidal behavior. Also, these studies have shown evidence for altered serotonergic neural transmission in the pathogenesis of suicidal behavior. In addition, genes pertaining to the serotonergic system have been proposed as candidates to establish biological correlates between suicidal behavior and the serotonergic system. The most studied genes are SCL6A4, HTR2A, HTR2C, HTR1A, HTR1B, TPH-1, and TPH-2. To get a comprehensive understanding of the association with suicidal behavior we will conduct genotype assays studies in a Mexican population.

METHODS/DESIGN

We will conduct a case-control study. The population sample will comprise adolescent and adult patients admitted for attempted of suicide and diagnosed by a psychiatrist. A peripheral blood sample will be taken from all the subjects (cases and controls). Genomic DNA from the leukocytes blood sample will be extracted. The genotypes of interest are distributed in the following genes: SCL6A4, HTR2A, HTR1A, HTR1B, HTR2C, TPH-2 and TPH-1. All the samples will be analyzed using a polymerase chain reaction (PCR) end-point method. We will evaluate the Hardy-Weinberg Equilibrium. The chi-squared test or Fisher's exact test will be used to compare genotype and allele frequencies between control and case groups. The Quanto 1.2 software will measure the sample size of the association. For all the association analyses the level of significance will be set at p = 0.05 and the confidence interval at 95%.

DISCUSSION

Suicidal behavior has been increase in Mexico, principally in young population. Our study will demonstrate the association between serotoninergic genes and suicide behavior in Mexican population.

Association of TPH1, TPH2, and 5HTTLPR with PTSD and depressive symptoms

OBJECTIVE

To examine the potential contribution of the serotonin hydroxylase (TPH1 and TPH2) genes, and the serotonin transporter promoter polymorphism (5HTTLPR) to the unique and pleiotropic risk of PTSD symptoms and depressive symptoms.

METHODS

Participants included 200 adults exposed to the 1988 Spitak earthquake from 12 multigenerational families (3 to 5 generations). Severity of trauma exposure, PTSD, and depressive symptoms were assessed using standard psychometric instruments. Pedigree-based variance component analysis was used to assess the association between select genes and the phenotypes.

RESULTS

After adjusting for age, sex, exposure and environmental variables, there was a significant association of PTSD symptoms with the 't' allele of TPH1 SNP rs2108977 (p<0.004), explaining 3% of the phenotypic variance. This allele also showed a non-significant trend for an association with depressive symptoms (p=0.08). Also, there was a significant association of PTSD symptoms and the 't' allele of TPH2 SNP rs11178997 (p=0.03), explaining 4% of the variance. Depressive symptoms were significantly associated with the 's' allele of 5HTTLPR (p=0.03), explaining 4% of the variance.

LIMITATIONS

Retrospective rating of exposure may have been subject to memory failure leading to misestimation of symptom severities. Second, findings may not be generalizable to other ethnic/racial populations.

CONCLUSION

To our knowledge, this is the first published report showing that variants in TPH1 and TPH2 genes constitute risk factors for PTSD symptoms. Additionally, the TPH1 gene may be associated pleiotropically with PTSD and depressive symptoms. The association of the 's' allele of 5HTTLPR polymorphism with depression adds to similar findings from case/case-control studies.

The association of attempted suicide with genetic variants in the SLC6A4 and TPH genes depends on the definition of suicidal behavior: a systematic review and meta-analysis

The global prevalence of suicide has increased substantially over the last four decades. Suicidal behavior manifests owing to a combination of biological, behavioral and social factors; however, the etiology of suicidality remains elusive. Even though twin studies have reported a significant heritability of 30-50%, meta-analyses have not highlighted a common genetic variant associated with the spectrum of suicidal behavior. Here, we performed a systematic review of the literature (n = 112) to assess the association between serotonergic and non-serotonergic genetic polymorphisms and suicidal behavior. Using an inverse variance random-effects model, we developed pooled odds ratios for the 10 most commonly studied genetic variants related to suicidal behavior, each with at least five independent studies that met our stringent inclusion criteria. Our pooled results indicate no significant correlation between genetic polymorphisms and overall suicidal behavior. However, subgroups of suicide attempts demonstrated actual significance with the serotonin transporter (SLC6A4) 5HTTLPR (OR = 1.13 (95% confidence interval = 1.05-1.21), P = 0.001) and reached nominal significance with the tryptophan hydroxylase rs1800532 (1.22 (1.05-1.41), P = 0.007) variant. Subgroups of suicidal behavior (completions and attempts) displayed reduced heterogeneity compared with the overall suicidal behavior spectrum. Our findings suggest that the 5HTTLPR and rs1800532 polymorphisms are significantly associated with suicide attempts, but not associated with completed suicides. The high degree of heterogeneity in past studies may be attributed to the lack of a phenotypic distinction between suicidal attempts and completions. Consequently, we have identified an important source of phenotypic heterogeneity that provides a rationale for the current lack of a common genetic variant associated with suicidal behavior.

Effects of sunshine on suicide rates

OBJECTIVES

Seasonal spring peaks of suicide are well described in epidemiological studies, but their origin is poorly understood. More recent evidence suggests that this peak may be associated with the increase in the duration of sunshine in spring. We investigated the effect of number of sunshine hours per month on suicide rates in Austria between 1996 and 2006.

METHODS

Suicide data, differentiated by month of suicide, sex, and method of suicide (violent vs nonviolent methods), were provided by Statistics Austria. Data on the average number of sunshine hours per month were calculated from 39 representative meteorological stations (provided by the Austrian Central Institute for Meteorology and Geodynamics). For statistical analysis, analysis of variance tests, Kruskal-Wallis tests, and Pearson correlation tests were used.

RESULTS

A total of 16,673 suicides with a median of 126 ± 19.8 suicides per month occurred in the examined period. A clear seasonal pattern was observed, with suicide frequencies being highest between March and May and lowest between November and January (df = 11, F = 5.2, P < .0001) for men (df = 11, F = 4.9, P < .0001) and women (df = 11, F = 2.4, P = .008). The average number of sunshine hours per month was significantly correlated with the number of suicides among both sexes (r = .43, P < .0001), violent methods (r = .48, P < .0001) but not with nonviolent methods (r = .03, P = .707).

CONCLUSIONS

This study shows that seasonal changes in sunshine account for variations in the number of suicides and especially violent suicides. We propose that sunshine, via interactions with serotonin neurotransmission, may trigger increased impulsivity and promote suicidal acts. However, because of the hypothesis-generating design of this study, more research is needed to further clarify the role of sunshine in triggering neurobiologic changes, which might contribute to suicidal behavior.