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Background Suicide represents a major health concern, especially in developing countries. While many demographic risk factors have been proposed, the underlying molecular pathology of suicide remains poorly understood. A body of evidence suggests that aberrant DNA methylation and expression is involved. In this study, we examined DNA methylation profiles and concordant gene expression changes in the prefrontal cortex of Mexicans who died by suicide. Methods In collaboration with the coroner’s office in Mexico City, brain samples of males who died by suicide (n = 35) and age-matched sudden death controls (n = 13) were collected. DNA and RNA were extracted from prefrontal cortex tissue and analyzed with the Infinium Methylation480k and the HumanHT-12 v4 Expression Beadchips, respectively. Results We report evidence of altered DNA methylation profiles at 4430 genomic regions together with 622 genes characterized by differential expression in cases vs controls. Seventy genes were found to have concordant methylation and expression changes. Metacore-enriched analysis identified 10 genes with biological relevance to psychiatric phenotypes and suicide (ADCY9, CRH, NFATC4, ABCC8, HMGA1, KAT2A, EPHA2, TRRAP, CD22, and CBLN1) and highlighted the association that ADCY9 has with various pathways, including signal transduction regulated by the cAMP-responsive element modulator, neurophysiological process regulated by the corticotrophin-releasing hormone, and synaptic plasticity. We therefore went on to validate the observed hypomethylation of ADCY9 in cases vs control through targeted bisulfite sequencing. Conclusion Our study represents the first, to our knowledge, analysis of DNA methylation and gene expression associated with suicide in a Mexican population using postmortem brain, providing novel insights for convergent molecular alterations associated with suicide.

Second-generation antipsychotics are the drugs of choice for the treatment of neurodevelopmental-related mental diseases such as schizophrenia. Despite the effectiveness of these drugs to ameliorate some of the symptoms of schizophrenia, specifically the positive ones, the mechanisms beyond their antipsychotic effect are still poorly understood. Second-generation antipsychotics are reported to have anti-inflammatory, antioxidant and neuroplastic properties. Using the neonatal ventral hippocampus lesion (nVHL) in the rat, an accepted schizophrenia-related model, we evaluated the effect of the second-generation antipsychotic olanzapine (OLZ) in the behavioral, neuroplastic, and neuroinflammatory alterations exhibited in the nVHL animals. OLZ corrected the hyperlocomotion and impaired working memory of the nVHL rats but failed to enhance social behavior disturbances of these animals. In the prefrontal cortex (PFC), OLZ restored the pyramidal cell structural plasticity in the nVHL rats, enhancing the dendritic arbor length, the spinogenesis and the proportion of mature spines. Moreover, OLZ attenuated astrogliosis as well as some pro-inflammatory, oxidative stress, and apoptosis-related molecules in the PFC. These findings reinforce the evidence of anti-inflammatory, antioxidant, and neurotrophic mechanisms of second-generation antipsychotics in the nVHL schizophrenia-related model, which allows for the possibility of developing more specific drugs for this disorder and thus avoiding the side effects of current schizophrenia treatments.

Suicidal behavior is result of the interaction of several contributors, including genetic and environmental factors. The integration of approaches considering the polygenic component of suicidal behavior, such as polygenic risk scores (PRS) and DNA methylation is promising for improving our understanding of the complex interplay between genetic and environmental factors in this behavior. The aim of this study was the evaluation of DNA methylation differences between individuals with high and low genetic burden for suicidality. The present study was divided into two phases. In the first phase, genotyping with the Psycharray chip was performed in a discovery sample of 568 Mexican individuals, of which 149 had suicidal behavior (64 individuals with suicidal ideation, 50 with suicide attempt and 35 with completed suicide). Then, a PRS analysis based on summary statistics from the Psychiatric Genomic Consortium was performed in the discovery sample. In a second phase, we evaluated DNA methylation differences between individuals with high and low genetic burden for suicidality in a sub-sample of the discovery sample (target sample) of 94 subjects. We identified 153 differentially methylated sites between individuals with low and high-PRS. Among genes mapped to differentially methylated sites, we found genes involved in neurodevelopment (CHD7, RFX4, KCNA1, PLCB1, PITX1, NUMBL) and ATP binding (KIF7, NUBP2, KIF6, ATP8B1, ATP11A, CLCN7, MYLK, MAP2K5). Our results suggest that genetic variants might increase the predisposition to epigenetic variations in genes involved in neurodevelopment. This study highlights the possible implication of polygenic burden in the alteration of epigenetic changes in suicidal behavior.

We assessed the association between Toxoplasma gondii (T. gondii) infection of the central nervous system and suicide correlates in suicide decedents. Eighty-seven decedents who died by suicide received in a forensic setting for medico-legal autopsies in Mexico City were studied. Two samples of brain (amygdala and prefrontal cortex) from each decedent were examined for detection of T. gondii using immunohistochemistry. Correlates of suicide including a history of previous suicide attempts, co-morbid mental disorder, consumption of alcohol or tobacco, irritability and aggression, economic problems, presence of drugs or alcohol in blood and suicide method were obtained and analyzed for their association with T. gondii infection. T. gondii immunohistochemistry was positive in prefrontal cortex sections in 6 decedents and in an amygdala section in one decedent. Thus, the prevalence of T. gondii infection in brain in suicide victims was 8.0% (7/87). Bivariate and logistic regression analysis of suicide correlates showed that only a history of depression was associated with T. gondii infection of the brain in suicide victims (OR: 12.00; 95% CI: 2.26–63.46; p = 0.003). Our results provide evidence that T. gondii infection in brain is associated with a history of depression in suicide decedents.

This study aimed to determine the association between suicide and Toxoplasma gondii (T. gondii) seropositivity. Serum samples of 89 decedents who committed suicide (cases) and 58 decedents who did not commit suicide (controls) were tested for anti-T. gondii IgG and IgM antibodies using enzyme-linked immunosorbent assays. Anti-T. gondii IgM antibodies were further detected by enzyme-linked fluorescence assay (ELFA). A total of 8 (9.0%) of the 89 cases and 6 (10.3%) of the 58 controls were positive for anti-T. gondii IgG antibodies (OR: 0.85, 95% CI: 0.28–2.60, p = 0.78). Anti-T. gondii IgG levels were higher than 150 IU/mL in two (2.2%) cases and in five (8.6%) controls (OR: 0.24, 95% CI: 0.04–1.30, p = 0.11). Anti-T. gondii IgM antibodies were not found in any case or control using the enzyme immunoassay and were found in only one (1.7%) control using ELFA (p = 0.39). Rates of IgG seropositivity and high levels of anti-T. gondii antibodies were similar in cases and in controls regardless of their sex or age groups. The results do not support an association between T. gondii seropositivity and suicide. However, the statistical power of the test was low. Further research is necessary to confirm this lack of association.

Genetic factors have been implicated in suicidal behavior. It has been suggested that one of the roles of genetic factors in suicide could be represented by the effect of genetic variants on gene expression regulation. Alteration in the expression of genes participating in multiple biological systems in the suicidal brain has been demonstrated, so it is imperative to identify genetic variants that could influence gene expression or its regulatory mechanisms. In this study, we integrated DNA methylation, gene expression, and genotype data from the prefrontal cortex of suicides to identify genetic variants that could be factors in the regulation of gene expression, generally called quantitative trait locus (xQTLs). We identify 6,224 methylation quantitative trait loci and 2,239 expression quantitative trait loci (eQTLs) in the prefrontal cortex of suicide completers. The xQTLs identified influence the expression of genes involved in neurodevelopment and cell organization. Two of the eQTLs identified (rs8065311 and rs1019238) were previously associated with cannabis dependence, highlighting a candidate genetic variant for the increased suicide risk in subjects with substance use disorders. Our findings suggest that genetic variants may regulate gene expression in the prefrontal cortex of suicides through the modulation of promoter and enhancer activity, and to a lesser extent, binding transcription factors.

Patients with substance use disorders (SUD) are at high risk to die by suicide. So far, the neurobiology of the suicide-SUD association has not been elucidated. This study aimed to identify potential pharmacological targets among hub genes from brain gene co-expression networks of individuals with SUD in a suicidal and non-suicidal context. Post-mortem samples from the prefrontal cortex of 79 individuals were analyzed. Individuals were classified into the following groups: suicides with SUD (n = 28), suicides without SUD (n = 23), nonsuicides with SUD (n = 9), nonsuicides without SUD (n = 19). Gene expression profiles were evaluated with the Illumina HumanHT-12 v4 array. Co-expression networks were constructed in WGCNA using the differentially expressed genes found in the comparisons: (a) suicides with and without SUD and (b) nonsuicides with and without SUD. Hub genes were selected for drug-gene interaction testing in the DGIdb database. Among drugs interacting with hub genes in suicides we found MAOA inhibitors and dextromethorphan. In the nonsuicide individuals, we found interactions with eglumegad and antipsychotics (olanzapine, clozapine, loxapine). Modafinil was found to interact with genes in both suicides and nonsuicides. These drugs represent possible candidate treatments for patients with SUD with and without suicidal behavior and their study in each context is encouraged.

Background Gene expression alterations have been implicated in suicide pathology. However, the study of the regulatory effect of DNA methylation on gene expression in the suicidal brain has been restricted to candidate genes. Objective The objective of the study was to identify genes whose expression levels are correlated with DNA methylation in the prefrontal cortex of suicides. Methods Postmortem prefrontal cortex samples from 21 suicides and six non-suicides were collected. Transcriptomic and DNA methylation profiles were evaluated with microarrays; cis correlations between gene expression and CpG methylation were screened. We then analyzed the presence of transcription factor (TF) binding sites (TFBS) at CpG sites correlated with gene expression. Gene expression of TFs involved in neurodevelopmental binding to predicted TFBS was determined in the BrainSpan database. Results We identified 22 CpG sites whose methylation levels correlated with gene expression in the prefrontal cortex of suicides. Genes annotated to identified CpG sites were involved in neurodevelopment (BBS4, NKX6-2, AXL, CTNND1, and MBP) and polyamine metabolism (polyamine oxidase [PAOX]). Such correlations were not detected in the nonsuicide group. Nine TFs (USF1, TBP, SF1, NRF1, RFX1, SP3, PKNOX1, MAZ, and POU3F2) showed differential expression in pre- and post-natal developmental periods, according to BrainSpan database. Conclusions The integration of different omic technologies provided novel candidates for the investigation of genes whose expression is altered in the suicidal brain and their potential regulatory mechanisms.

Objective: Dual diagnosis (DD) is the co-occurrence of at least one substance use disorder and one or more mental disorders in a given individual. Despite this comorbidity being highly prevalent an...

Background Suicidal behavior may be divided into completed suicide, suicide attempts, and suicidal ideation. It has been suggested that these behaviors represent a continuum and result from the interaction of several contributors, including genetic and environmental factors. The integration of approaches considering the polygenic component of suicidal behavior, such as polygenic risk scores (PRS) and DNA methylation is promising for improving our understanding of the complex interplay between genetic and environmental factors in this behavior. The aim of this study was the evaluation of DNA methylation differences between individuals with high and low genetic burden for suicidality. Methods The present study was divided into two phases. In the first phase, genotyping with the Psycharray chip was performed in a discovery sample of 568 Mexican individuals, of which 149 had suicidal behavior (64 individuals with suicidal ideation, 50 with suicide attempt and 35 with completed suicide) and 419 non-suicide controls. Then, a PRS analysis based on summary statistics from the Psychiatric Genomic Consortium was performed in the discovery sample. In a second phase, we evaluated DNA methylation differences between individuals with high and low genetic burden for suicidality in a sub-sample of the discovery sample (target sample) of 94 subjects. Methylation profile from individuals in the target sample was assessed with the Illumina Infinium Human Methylation EPIC BeadChip. Results We identified 153 differentially methylated sites between individuals with low and high-PRS. From these, 91 sites were hypermethylated and 62 hypomethylated in the high PRS group relative to low PRS group. Among genes mapped to differentially methylated sites, we found genes involved in neurodevelopment and ATP binding. Discussion To our knowledge, this is the first study integrating polygenic risk scores and DNA methylation in suicidality. Our results suggest that genetic variants might increase the predisposition to epigenetic variations in genes involved in neurodevelopment. This study highlights the possible implication of polygenic burden in the alteration of epigenetic changes in suicidal behavior.

Background Suicide rates vary substantially by sex. Suicides committed by males significantly outnumber female suicides. Disparities in community and social factors provide a partial explanation for this phenomenon. Thus, the evaluation of sex differences at a biological level might contribute to the elucidation of the factors involved in this imbalance. The aim of the present study was to evaluate sex-specific gene expression patterns in the suicidal brain. Methods postmortem samples from the dorsolateral prefrontal cortex (DLPFC) of 75 Latino individuals were analyzed. We considered the following groups: i) male suicides (n = 38), ii) female suicides (n = 10), iii) male controls (n = 20), and iv) female controls (n = 7). Gene expression profiles were evaluated by microarrays. Differentially expressed genes among the groups were identified with a linear model. Similarities and differences in the gene sets between the sexes were identified. Results Differentially expressed genes were identified between suicides and controls of each sex: 1,729 genes in females and 1,997 genes in males. Female-exclusive suicide genes were related to cell proliferation and immune response. Meanwhile, male-exclusive suicide genes were associated to DNA binding and ribonucleic protein complex. Sex-independent suicide genes showed enrichment in mitochondrial and vesicular functions. Limitations Relatively small sample size. Our diagnosis approach was limited to information found on coroner's records. The analysis was limited to a single brain area (DLPFC) and we used microarrays. Conclusion Previously unexplored sex differences in the brain gene expression of suicide completers were identified, providing valuable foundation for the evaluation of sex-specific factors in suicide.

Background Dual diagnosis is the co-occurrence of at least one substance use disorder (SUD) and one or more mental disorders in a given individual. Despite this comorbidity is highly prevalent and associated with adverse clinical outcomes, its neurobiology remains unclear. Furthermore, patients with dual diagnosis are at higher risk for suicidal behavior in comparison with single disorder patients. Our objective was to evaluate brain gene expression patterns in individuals with dual diagnosis who died by suicide. Methods We compared the gene expression profile in the dorsolateral prefrontal cortex of suicides with DD (n= 10) to the transcriptome of suicides with SUD alone (n=10), suicides with mood disorders alone (n=13), and suicides without mental comorbidities (n=5). Gene expression profiles were assessed by microarrays. Microarray data quality control was performed. Then, microarray data were background corrected and quantile normalized. Differentially expressed genes among the conditions were identified by a linear model implemented in the limma package. Results When comparing the transcriptome of suicides with dual diagnosis to suicides with SUD alone and suicides with mood disorders alone, we identified 255 and 172 differentially expressed genes, respectively. When comparing suicides with DD to suicides without mental comorbidities, we identified 330 differentially expressed genes, mainly enriched in neurogenesis. Discussion Our results suggest that suicides with dual diagnosis present a gene expression profile distinct from that of suicides with a single disorder and suicides without mental disorders. Also, suicides with dual diagnosis, SUD and mood disorders exhibited alterations in the expression of synaptic genes. However, suicides with each condition (dual diagnosis, SUD or mood disorders) exhibited unique gene expression changes at different levels within synaptic signaling. These gene expression differences might contribute to the phenotypical and clinical discrepancies observed in patients with dual diagnosis and patients with a single disorder

Suicidal behavior is a complex human behavior and current data suggests that suicide is an increasing cause of death among young people. The neurobiology of suicide is unknown and data investigating the role of the pituitary in suicidal behavior is scarce. Imaging data suggests that this gland increases in size in patients with major depression and recent data implicates hyperactivity of the hypothalamus-pituitary-adrenal axis in suicidal behavior. In this study, we evaluate the size and number of cells as well as markers related to oxidative stress and lipid peroxidation of the anterior and posterior sections of the pituitary gland of male suicide completers. Stereological analysis is used to quantify the total cell number in anterior- and posterior-pituitary regions. We examined nitric oxide (NO) levels, Zinc (Zn) levels, superoxide dismutase (SOD) activity, 4-hydroxy-alkenals (4-HDA), malondialdehyde (MDA) and metallothioneins (MTs). Our results indicate that the anterior-pituitary region of suicide completers exhibits increased weight, likely due to an enhanced number of cells compared to the control group. In addition, we found a reduction of NO levels with higher SOD activity in the anterior-pituitary region of suicide victims. No changes in Zn, MDA, MTs, 4-HDA or MDA were observed in tissue of suicide completers compared to the control group. This study demonstrates that there is an increased number of cells, with an imbalance in oxidative stress without a process of lipid peroxidation in the anterior-pituitary region of young male suicide completers.

Background It is estimated that subjects with alcohol abuse are almost 10 times more likely to commit suicide and those with substance abuse about 14 times more. The prefrontal cortex is the cerebral area responsible for decision making, inhibition and short-term memory, functions that have been altered in subjects with suicidal behavior. In addition, structural and functional changes in individuals with suicidal behavior have been identified in this area. Cognitive abilities associated with the prefrontal area, specifically the dorsolateral prefrontal cortex, have been identified in subjects with substance abuse. Therefore, it is of special interest to evaluate gene expression in this cerebral area in order to identify genes expressed in suicide subjects with substance use compared with suicide death without this comorbidity to have a better understanding of the pathology of suicide and that could be used in the future as biomarkers of suicidal behavior in subjects with substance abuse and implement adequate prevention measures for this sector of the population. Methods We collected samples from the dorsolateral prefrontal cortex of subjects who committed suicide and of subjects with death other than suicide. RNA isolation was performed using the Qiagen RNAeasy, after RNA extraction the purity of RNA extracted by means of spectrophotometry (NanoDrop1000 Spectrophotometer from Thermo Fisher) and its integrity with 1% agarose gel electrophoresis was evaluated. The expression of messenger RNA from 67 samples (43 Subjects with consummate suicide and 24 subjects with death other than suicide) through the HumanHT-12 v4 BeadChip microarray containing 47, 231 probes was evaluated. The analysis of the data obtained from the microarray will be performed comparing the expression of messenger RNA between the group with consummate suicide and the group with death other than suicide with a paired t-test for each probe evaluated in the microarray. Subsequently, a statistical model of ANOVA will be applied to assess whether the diagnosis of substance abuse during the lifetime and toxicology at the time of death had any effect on the expression of messenger RNA. The genes that are differentially expressed will be validated by real-time PCR. Results The final sample consisted of 67 brain samples divided into the group of "individuals who consumed suicide" (n=43) and the group of "controls" or subjects with a cause of death other than suicide (n=24). There were no significant differences in gender and age between both groups. The analysis of microarray data will be performed in the next weeks. Discussion Subjects with substance abuse are at increased risk for suicidal behavior, most studies of expression have excluded this group of patients and little is known about the molecular basis of the association between substance abuse and suicidal behavior. We hypothesize that subjects with death by self-harm and substance abuse have different expression profiles of the messenger RNA in the dorsolateral prefrontal cortex compared to suicide victims without substance abuse and controls who had a death from other causes. I believe that after conducting the analysis of the results of the microarray (which will take only a few weeks) we will be able to extend the discussion by commenting on the differences between the study groups.

TRESK (TWIK-related spinal cord K(+)) channel, encoded by KCNK18 gene, belongs to the double-pore domain K(+) channel family and in normal conditions is expressed predominantly in the central nervous system. In our previous patch-clamp study on Jurkat T lymphoblasts we have characterized highly selective K(+) channel with pharmacological profile identical to TRESK. In the present work, the presence of KCNK18 mRNA was confirmed in T lymphoblastic cell lines (Jurkat, JCaM, H9) but not in resting peripheral blood lymphocytes of healthy donors. Positive immunostaining for TRESK was demonstrated in lymphoblastic cell lines, in germinal centers of non-tumoral lymph nodes, and in clinical samples of T acute lymphoblastic leukemias/lymphomas. Besides detection in the plasma membrane, intracellular TRESK localization was also revealed. Possible involvement of TRESK channel in lymphocyte proliferation and tumorigenesis is discussed.

Cerebrolysin (Cbl) shows neurotrophic and neuroprotective properties while donepezil (Dnp) is a potent acetylcholinesterase (AChE) inhibitor, both drugs are prescribed for Alzheimer's disease (AD) treatment. Previous studies have shown that the Dnp and Cbl administered separately, modify dendritic morphology of neurons in the prefrontal cortex and hippocampus in senile rodents. Since the deficit of neurotrophic factor activity is implicated in the degeneration of cholinergic neurons of basal forebrain, a combination therapy of Dnp and Cbl has been tested recently in Alzheimer's patients. However, the plastic changes that may underlie this combined treatment have not yet been explored. We present here the effect of the combined administration of Cbl and Dnp on dendritic morphology in brain regions related to learning and memory in aged mice. The Golgi-Cox staining protocol and Sholl analysis were used for studying dendritic changes. Cbl and Dnp were administrated daily for 2 months to 9-months-old mice. Locomotor activity was assessed, as well as the dendritic morphology of neurons in several limbic regions was analyzed. Results showed that Cbl and Dnp induced an increase in locomotor activity without synergistic effect. The Cbl or Dnp treatment modified the dendritic morphology of neurons from prefrontal cortex (PFC), dorsal hippocampus (DH), dentate gyrus (DG), and the shell of nucleus accumbens (NAcc). These changes show an increase in the total dendritic length and spine density, resulting in an improvement of dendritic arborization. Prominently, a synergistic effect of Cbl and Dnp was observed on branching order and total dendritic length of pyramidal neurons from PFC. These results suggest that Dnp and Cbl may induce plastic changes in a manner independent of each other, but could enhance their effect in target cells from PFC.

Recently in Mexico the number of cosmetic surgeries has increased. These procedures are often carried out by unqualified people using obsolete and contraindicated products such as injectable oil, which cause uncorrectable disfigurement or more serious complications, even death, after reaching the systemic circulation. We report the case of a fat embolism syndrome (FES) caused by injections of vitamin E (tocopherol) in order to increase the volume of the buttocks. This case of a FES caused by injections of vitamin E was confirmed by gas chromatography coupled to mass spectrometry.

Acetylcholinesterase (AChE), the enzyme that rapidly splits acetylcholine into acetate and choline, presents non-cholinergic functions through which may participate in the control of cell proliferation and apoptosis. These two features are relevant in cancer, particularly in hepatocellular carcinoma (HCC), a very aggressive liver tumor with high incidence and poor prognosis in advanced stages. Here we explored the relation between acetylcholinesterase and HCC growth by testing the influence of AChE on proliferation of Huh-7 and HepG2 cell lines, addressed in monolayer cultures, spheroid formation and human liver tumor samples. Results showed a clear relation in AChE expression and cell cycle progression, an effect which depended on cell confluence. Inhibition of AChE activity led to an increase in cell proliferation, which was associated with downregulation of p27 and cyclins. The fact that Huh-7 and HepG2 cell lines provided similar results lent weight to the relationship of AChE expression with cell cycle progression in hepatoma cell lines at least. Human liver tumor samples exhibited a decrease in AChE activity as compared with normal tissue. The evidence presented herein provides additional support for the proposed tumor suppressor role of AChE, which makes it a potential therapeutic target in therapies against hepatocellular carcinoma.