Etanercept ameliorates chronic mild stress-induced depressive-like behavior in rats: Crosstalk between MAPK and STAT3 pathways and norepinephrine and serotonin transporters.

Depression is a serious medical illness characterized by persistent feelings of sadness, hopelessness, and lack of interest in daily activities. It can interfere with daily functioning and quality of life. Despite decades of research, the pathophysiology of depression remains incompletely understood. The correlation between depression and inflammation has recently attracted considerable attention. This study investigated the potential antidepressant effect of etanercept, a tumor necrosis factor-alpha (TNF-α) inhibitor, utilizing a chronic mild stress (CMS) model in rats. Male Wistar rats were divided into two groups; one following a non-stressed protocol and the other a stressed protocol for 5 weeks. From the beginning of the third week, rats were treated either with saline daily or with etanercept twice a week (0.3 mg/kg, i.p.) or with fluoxetine daily (10 mg/kg, i.p) as a reference. Etanercept exhibited comparable effects to those of fluoxetine in counteracting CMS-induced behavioral manifestation in the forced swimming and splash tests. Etanercept also restored serotonin and norepinephrine levels to control values in the prefrontal cortex (PFC). Moreover, the current study verified the antioxidant and anti-inflammatory effects of etanercept. Interestingly, etanercept halted the expression of both norepinephrine and serotonin transporters in stressed rats. This could be attributed to abrogation of the p38 mitogen-activated protein kinase (p38 MAPK) and signal transducer and activator of transcription 3 (STAT-3) pathways in the PFC. The findings of the present study contribute to the understanding of the potential of etanercept as an antidepressant and provide insights into the neurobiological mechanisms underlying its therapeutic effects.

Modulation of Serotonin-Related Genes by Extracellular Vesicles of the Probiotic Escherichia coli Nissle 1917 in the Interleukin-1ß-Induced Inflammation Model of Intestinal Epithelial Cells.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition involving dysregulated immune responses and imbalances in the gut microbiota in genetically susceptible individuals. Current therapies for IBD often have significant side-effects and limited success, prompting the search for novel therapeutic strategies. Microbiome-based approaches aim to restore the gut microbiota balance towards anti-inflammatory and mucosa-healing profiles. Extracellular vesicles (EVs) from beneficial gut microbes are emerging as potential postbiotics. Serotonin plays a crucial role in intestinal homeostasis, and its dysregulation is associated with IBD severity. Our study investigated the impact of EVs from the probiotic Nissle 1917 (EcN) and commensal E. coli on intestinal serotonin metabolism under inflammatory conditions using an IL-1ß-induced inflammation model in Caco-2 cells. We found strain-specific effects. Specifically, EcN EVs reduced free serotonin levels by upregulating SERT expression through the downregulation of miR-24, miR-200a, TLR4, and NOD1. Additionally, EcN EVs mitigated IL-1ß-induced changes in tight junction proteins and oxidative stress markers. These findings underscore the potential of postbiotic interventions as a therapeutic approach for IBD and related pathologies, with EcN EVs exhibiting promise in modulating serotonin metabolism and preserving intestinal barrier integrity. This study is the first to demonstrate the regulation of miR-24 and miR-200a by probiotic-derived EVs.

Serotonin 2C receptor in a rat model of temporal lobe epilepsy: From brainstem expression to pharmacological blockade in relation to ventilatory function.

Because of its involvement in breathing control and neuronal excitability, dysregulation of the serotonin (5-HT) 2C receptor (5-HT2C) might play a key role in sudden unexpected death in epilepsy. Seizure-induced respiratory arrest is thus prevented by a 5-HT2B/C agonist in different seizure model. However, the specific contribution of 5-HT2C in chronic epilepsy-related respiratory dysfunction remains unknown. In a rat model of temporal lobe epilepsy (EPI rats), in which we previously reported interictal respiratory dysfunctions and a reduction of brainstem 5-HT tone, quantitative reverse transcriptase polymerase chain reaction showed overexpression of TPH2 (5-HT synthesis enzyme), SERT (5-HT reuptake transporter), and 5-HT2C transcript levels in the brainstem of EPI rats, and of RNA-specific adenosine deaminase (ADAR1, ADAR2) involved in the production of 5-HT2C isoforms. Interictal ventilation was assessed with whole-body plethysmography before and 2 h after administration of SB242084 (2 mg/kg), a specific antagonist of 5-HT2C. As expected, SB242084 administration induced a progressive decrease in ventilatory parameters and an alteration of breathing stability in both control and EPI rats. However, the size of the SB242084 effect was lower in EPI rats than in controls. Increased 5-HT2C gene expression in the brainstem of EPI rats could be part of a compensatory mechanism against epilepsy-related low 5-HT tone and expression of 5-HT2C isoforms for which 5-HT affinity might be lower.

A Conserved Intramolecular Ion-Pair Plays a Critical but Divergent Role in Regulation of Dimerization and Transport Function among the Monoamine Transporters.

The monoamine transporters, including the serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET), are the therapeutic targets for the treatment of many neuropsychiatric disorders. Despite significant progress in characterizing the structures and transport mechanisms of these transporters, the regulation of their transport functions through dimerization or oligomerization remains to be understood. In the present study, we identified a conserved intramolecular ion-pair at the third extracellular loop (EL3) connecting TM5 and TM6 that plays a critical but divergent role in the modulation of dimerization and transport functions among the monoamine transporters. The disruption of the ion-pair interactions by mutations induced a significant spontaneous cross-linking of a cysteine mutant of SERT and an increase in cell surface expression but with an impaired specific transport activity. On the other hand, similar mutations of the corresponding ion-pair residues in both DAT and NET resulted in an opposite effect on their oxidation-induced dimerization, cell surface expression, and transport function. Reversible biotinylation experiments indicated that the ion-pair mutations slowed down the internalization of SERT but stimulated the internalization of DAT. In addition, cysteine accessibility measurements for monitoring SERT conformational changes indicated that substitution of the ion-pair residues resulted in profound effects on the rate constants for cysteine modification in both the extracellular and cytoplasmatic substrate permeation pathways. Furthermore, molecular dynamics simulations showed that the ion-pair mutations increased the interfacial interactions in a SERT dimer but decreased it in a DAT dimer. Taken together, we propose that the transport function is modulated by the equilibrium between monomers and dimers on the cell surface, which is regulated by a potential compensatory mechanism but with different molecular solutions among the monoamine transporters. The present study provided new insights into the structural elements regulating the transport function of the monoamine transporters through their dimerization.

Chronic exposure to imipramine induces a switch from depression-like to mania-like behavior in female serotonin transporter knockout rats: Role of BDNF signaling in the infralimbic cortex.

BACKGROUND: Bipolar disorder (BD) is a highly burdensome psychiatric disorder characterized by alternating states of mania and depression. A major challenge in the clinic is the switch from depression to mania, which is often observed in female BD patients during antidepressant treatment such as imipramine. However, the underlying neural basis is unclear. METHODS: To investigate the potential neuronal pathways, serotonin transporter knockout (SERT KO) rats, an experimental model of female BD patients, were subjected to a battery of behavioral tests under chronic treatment of the antidepressant imipramine. In addition, the expression of brain-derived neurotrophic factor (BDNF) and its downstream signaling was examined in the prefrontal cortex. RESULTS: Chronic exposure to imipramine reduced anxiety and sociability and problem-solving capacity, and increased thigmotaxis and day/night activity in all animals, but specifically in female SERT KO rats, compared to female wild-type (WT) rats. Further, we found an activation of BDNF-TrkB-Akt pathway signaling in the infralimbic, but not prelimbic, cortex after chronic imipramine treatment in SERT KO, but not WT, rats. LIMITATIONS: Repeated testing behaviors could potentially affect the results. Additionally, the imipramine induced changes in behavior and in the BDNF system were measured in separate animals. CONCLUSIONS: Our study indicates that female SERT KO rats, which mirror the female BD patients with the 5-HTTLPR s-allele, are at higher risk of a switch to mania-like behaviors under imipramine treatment. Activation of the BDNF-TrkB-Akt pathway in the infralimbic cortex might contribute to this phenotype, but causal evidence remains to be provided.

Membrane Transporter of Serotonin and Hypercholesterolemia in Children.

The serotonin membrane transporter is one of the main mechanisms of plasma serotonin concentration regulation. Serotonin plays an important role in the pathogenesis of various cardiovascular diseases, stimulating the proliferation of smooth muscle cells, key cells in the process of hypertrophic vascular remodeling. Vascular remodeling is one of the leading prognostically unfavorable factors of atherosclerosis, the main manifestation of familial hypercholesterolemia. Familial hypercholesterolemia is one of the most common genetically determined lipid metabolism disorders and occurs in 1 in 313 people. The aim of our study was to investigate the levels of plasma and platelet serotonin, 5-hydroxyindoleacetic acid, and membrane transporter in a cross-sectional study of two pediatric groups, including patients with familial hypercholesterolemia and the control group, which consisted of apparently healthy children without cardiovascular diseases. The study involved 116 children aged 5 to 17 years old. The proportion of boys was 50% (58/116) and the average age of the children was 10.5 years (CI 2.8-18.1). The concentrations of serotonin in blood plasma and platelets and 5-hydroxyindoleacetic acid were higher in children with familial hypercholesterolemia than in the controls. The concentration of the serotonin transporter in platelets in healthy children, compared with the main group, was 1.3 times higher. A positive correlation was revealed between the level of serotonin (5-HT and PWV: ρ = 0.6, p < 0.001), its transporter (SERT and PWV: ρ = 0.5, p < 0.001), and the main indicators of arterial vascular stiffness. Our study revealed the relationship between high serotonin and SERT concentrations and markers of arterial stiffness. The results we obtained suggest the involvement of serotonin and SERT in the process of vascular remodeling in familial hypercholesterolemia in children.

Butyrate acts as a positive allosteric modulator of the 5-HT transporter to decrease availability of 5-HT in the ileum.

BACKGROUND AND PURPOSE: Radiation therapy-induced gastrointestinal distress is partly associated with the elimination of gut microbiota. The effectiveness of 5-HT receptor antagonists to treat radiation therapy-induced emesis implies a pathophysiological role of 5-HT. Peripheral 5-HT is derived from intestinal epithelium. We have investigated the role of gut microbiota in regulating intestinal 5-HT availability. EXPERIMENTAL APPROACH: A radiation therapy murine model accompanied by faecal microbiota transplantation from donors fed different diets was investigated, and mouse ileal organoids were used for mechanistic studies. The clinical relevance was validated by a small-scale human study. KEY RESULTS: Short-term high-fat diet (HFD) induced gut bacteria to produce butyrate. Irradiated mice receiving HFD-induced microbiome had the lowest ileal levels of 5-HT, compared with other recipients. Treatment with butyrate increased 5-HT uptake in mouse ileal organoids, assayed by the real-time tracking of a fluorescent substrate for monoamine transporters. Silencing the 5-HT transporter (SERT) in the organoids abolished butyrate-stimulated 5-HT uptake. The competitive tests using different types of selective 5-HT reuptake inhibitors suggested that butyrate acted as a positive allosteric modulator of SERT. In human gut microbiota, butyrate production was associated with the interconversion between acetate and butyrate. Faecal contents of both acetate and butyrate were negatively associated with serum 5-HT, but only butyrate was positively correlated with body mass index in humans. CONCLUSION AND IMPLICATIONS: Short-term HFD may be beneficial for alleviating gastrointestinal reactions by increasing butyrate to suppress local 5-HT levels and providing energy to cancer patients given radiation therapy.

Effect of different factors on patient perception of surgical discomfort in third molar surgery

Abstract: The aim of this study was to evaluate patient perception of surgical discomfort in third molar surgery and the association with clinical variables and polymorphisms associated with the FKBP5, SLC6A4, and COMT genes. This cross-sectional observational study was carried out on 196 participants aged between 18 and 64 years at the Federal University of Paraná in 11 months. The intensity of surgical discomfort was assessed using the QCirDental questionnaire. Data on surgical and individual procedures were also cataloged. The oral health related quality of life was assessed by the Oral Health Impact Profile questionnaire (OHIP-14). The DNA sample was obtained from cells of the oral mucosa. Five markers of the FKBP5, SLC6A4, and COMT genes were genotyped. The data were submitted to statistical analysis with a significance level of 5%. Women reported greater intensity of discomfort associated with third molar surgery compared to men (p = 0.001). In the recessive model, the AA genotype of the rs3800373 marker was associated with greater surgical discomfort (p = 0.026). Therefore, women and individuals of the AA genotype for the rs3800373 marker in the FKBP5 gene reported greater surgical discomfort associated with third molar surgery.

Association of BDNF, HTR2A, TPH1, SLC6A4, and COMT polymorphisms with tDCS and escitalopram efficacy: ancillary analysis of a double-blind, placebo-controlled trial

Objective: We investigated whether single nucleotide polymorphisms (SNPs) associated with neuroplasticity and activity of monoamine neurotransmitters, such as the brain-derived neurotrophic factor (BDNF, rs6265), the serotonin transporter (SLC6A4, rs25531), the tryptophan hydroxylase 1 (TPH1, rs1800532), the 5-hydroxytryptamine receptor 2A (HTR2A, rs6311, rs6313, rs7997012), and the catechol-O-methyltransferase (COMT, rs4680) genes, are associated with efficacy of transcranial direct current stimulation (tDCS) in major depression. Methods: Data from the Escitalopram vs. Electrical Current Therapy for Treating Depression Clinical Study (ELECT-TDCS) were used. Participants were antidepressant-free at baseline and presented with an acute, moderate-to-severe unipolar depressive episode. They were randomized to receive escitalopram/tDCS-sham (n=75), tDCS/placebo-pill (n=75), or placebo-pill/sham-tDCS (n=45). General linear models assessed the interaction between treatment group and allele-wise carriers. Additional analyses were performed for each group and each genotype separately. Results: Pairwise group comparisons (tDCS vs. placebo, tDCS vs. escitalopram, and escitalopram vs. placebo) did not identify alleles associated with depression improvement. In addition, exploratory analyses also did not identify any SNP unequivocally associated with improvement of depression in any treatment group. Conclusion: Larger, combined datasets are necessary to identify candidate genes for tDCS response.

Polymorphism of Serotonin Transporter SLC6A4 (5-HTTLPR) Gene in Cheilitis Angularis Patients

Abstract Objective: To determine the relationship between the Serotonin transporter SLC6A4 (5-HTTLPR) gene polymorphism in cheilitis angularis patients. Material and Methods: We conducted a descriptive analysis of 100 DNA samples extracted from the blood serum of 50 patients with cheilitis angularis and 50 patients without cheilitis angularis. Analysis of the Serotonin transporter SLC6A4 (5-HTTLPR) gene polymorphism was observed by carrying out PCR method followed by electrophoresis for the analysis, without the usage of restriction enzyme. The Chi-square test was used for statistical analysis Results: In the cheilitis angularis group there were 24 samples with SS genotype, 23 samples with LS genotype, and 3 samples with LL genotype. Whereas in the non-cheilitis angularis group, there were 5 samples with SS genotype, 18 samples with LS genotype, and 27 samples with LL genotype. In the cheilitis angularis group found 71 S alleles and 29 L alleles, and in the non-cheilitis angularis group 28 S alleles and 72 L alleles were found. A statistically significant difference was found between the groups (p<0.001) Conclusion: There were significant differences in the distribution of the Serotonin transporter SLC6A4 (5-HTTLPR) gene polymorphism between patients with and without cheilitis angularis.

Interaction between polymorphisms in SLC6A4 and BDNF on major depressive disorder in a sample of the argentinean population / Interacción entre polimorfismos en SLC6A4 y BDNF en el trastorno depresivo mayor en una muestra de la población argentina

The dysfunction in the serotoninergic neurotransmission has been classically associated with major depressive disorder (MDD); however, other pathways and processes seem to have a role in this illness, such as neurogenesis and related molecules: the Brain-Derived Neurotrophic Factor (BDNF) and the Apolipoprotein E (APOE). There are many reports that indicate an association between certain polymorphism in these genes and MDD. The aim of our study was to analyze the possible association between MDD and polymorphisms in HTR2A (5-hydroxytryptamine receptor 2A), BDNF and APOE genes in a sample of the Argentinean population previously studied for 2 polymorphisms in SLC6A4 (Solute Carrier Family 6 Member 4) gene. Five polymorphisms were studied (rs6311 and rs6313 in HTR2A; rs429358 and rs7412 in APOE, and rs6265 in BDNF) in 95 MDD patients and 107 non-related controls. No statistically significant differences were observed between groups when analyzing the association with a single marker using logistic regression; however, when a possible combinatory effect of the polymorphisms (including previously studied polymorphisms in SLC6A4 gene) was analyzed using a dominant model for the risk alleles, the genotypes L/S_10/12_G/A (OR=3.57(95%CI=1.43-8.93); p=0.004, adjusted p-value=0.01) in SLC6A4 and BDNF genes and L/S_10/12_T/C_3/3_G/A in SLC6A4, HTR2A, APOE and BDNF genes (OR=5.99(95%CI=1.66-21.56); p=0.002, adjusted p-value=0.07), were more prevalent in patients than in controls (20%vs.6% and 15%vs.3%, respectively). Even though it is necessary to replicate these findings in a larger population, our results suggest a possible interaction between molecules involved in neurogenesis (BDNF and APOE), serotoninergic neurotransmission (SLC6A4 and HTR2A) and the pathogenesis of MDD. (AU)

La disfunción en la neurotransmisión serotoninérgica ha sido clásicamente asociada con el trastorno depresivo mayor (TDM); sin embargo, otras vías y procesos parecerían tener un rol en esta enfermedad, como la neurogénesis y moléculas asociadas: el factor neurotrófico derivado del cerebro (BDNF) y la apoliproteína E (APOE). Existen reportes en los que se establecen asociaciones entre polimorfismos en estos genes y el TDM. El objetivo de nuestro trabajo fue analizar la posible asociación entre el TDM y polimorfismos en los genes HTR2A (receptor 5-hidroxitriptamina 2A), BDNF y APOE en una muestra de la población argentina previamente estudiada para 2 polimorfismos en el gen SLC6A4 (transportador soluble familia 6 miembro 4). Se estudiaron 5 polimorfismos (rs6311 y rs6313 en HTR2A; rs429358 y rs7412 en APOE; rs6265 en BDNF) en 95 pacientes con TDM y 107 controles no relacionados. No se observaron diferencias significativas entre grupos al analizar la asociación por regresión logística con un único marcador; cuando se analizó el posible efecto combinatorio de polimorfismos (incluyendo los previamente estudiados para el gen SCL6A4) usando un modelo dominante para los alelos de riesgo, los genotipos L/S_10/12_G/A (OR=3,57(95%CI=1,43-8,93); p=0,004, valor-p-ajustado=0,01) en SLC6A4 y BDNF y L/S_10/12_T/C_3/3_G/A en SLC6A4, HTR2A, APOE y BDNF (OR=5,99(95%CI=1,66-21,56); p=0,002, valor-p-ajustado=0,07), fueron más prevalentes en pacientes que controles (20%vs.6% y 15%vs.3% respectivamente). Si bien es necesario replicar estos hallazgos en una población más grande, nuestros resultados sugieren una posible interacción entre moléculas involucradas en la neurogénesis (BDNF y APOE), la neurotransmisión serotoninérgica (SLC6A4 y HTR2A) y la patogenia de la depresión mayor. (AU)

Desenvolvimento e validação de métodos bioanalíticos para o monitoramento dos produtos das vias metabólicas do triptofano em linhagem celular de glioma humano / Development and validation of bioanalytical methods for monitoring the product of the metabolic pathways of tryptophan in human glioma cell line

O metabolismo do triptofano (Trp) se dá pela via das quinureninas (QUIN), pela via serotoninérgica (SER) e pela via das aminas traço. A primeira gera QUIN e uma variedade de outros metabólitos secundários. Quando conduzida pela enzima indolamina 2,3 dioxigenase (IDO) contribui para os fenômenos de tolerância e imune escape de células tumorais; e quando conduzida pela triptofano 2,3 dioxigenase (TDO) no fígado, participa na síntese da niacina e NAD. A via SER leva à formação do neurotransmissor serotonina (SER), que pode gerar o hormônio melatonina (MEL), respectivamente e outros metabólitos biologicamente ativos. Outra via menos estudada, a via das aminas traço, produz produtos neuroativos. Dada a abrangência e importância das rotas metabólicas do Trp, nós desenvolvemos e validamos uma metodologia bioanalítica robusta, seletiva e sensível por cromatografia líquida de alta eficiência (HPLC), acoplado espectrometria de massas (MS) para a determinação simultânea do Trp e seus 15 metabólitos. Para tanto, escolhemos para a avaliação das três vias, linhagens de glioma humano. A escolha por este tipo celular deveu-se ao grande interesse de estudos de metabolismo de Trp em células tumorais, no qual células de glioma tem sido modelo. Nos ensaios com as células de glioma acompanhamos os efeitos de um indutor e inibidores da primeira etapa de metabolização do Trp pela via das quinureninas, ou seja, IFN-γ (indutor da IDO), 1-metiltriptofano (1-MT; inibidor competitivo da IDO) e 680C91 (inibidor seletivo da TDO). Pudemos observar o impacto que a indução ou a inibição do primeiro passo teve sobre os metabólitos subsequentes e as diferenças no metabolismo das duas linhagens estudadas, A172 e T98G. A linhagem T98G só tem atividade de IDO, enquanto que a A172 tem tanto atividade IDO quanto TDO. A indução por IFN-γ mostrou que essa citocina não só atua na formação da via QUIN, mas possui um impacto modesto nas demais rotas. Observamos também que a inibição do 1-MT mostrou seu impacto nos metabólitos invdividualmente, do que a simples relação Trp-QUIN. Contudo, nosso resultados nos permitiu mostrar pela primeira vez a descrição completa dessas vias, em especial nessas linhagens celulares, podendo supor estratégias terapêuticas nessas rotas que estão relacionadas a progressão ou não tumoral

The tryptophan metabolism (Trp) takes place by means of kynurenine (QUIN), by the serotonin pathway (SER) and by the pathway of trace amines synthesis. The first generates QUIN and a variety of other secondary metabolites. When driven by the enzyme indoleamine 2,3 dioxygenase (IDO) contributes to the phenomena of tolerance and immune escape of tumor cells; and when conducted by tryptophan 2,3 -dioxygenase (TDO) in the liver, participates in the niacin synthesis NAD. The SER pathway leads to the serotonin neurotransmitter (SER) formation, which can generate the hormone melatonin (MEL), respectively and other biologically active metabolites. Another less studied amines trace synthesis pathway produces neuroactive products. Given the scope and importance of Trp metabolic pathways,we developed and validated a robust, sensitive and selective bioanalytical method by high performance liquid chromatography (HPLC) coupled mass spectrometry (MS) for simultaneous determination of TRP and its 16 metabolites. Therefore, we chose to evaluate the three routes, glioma cell lines. The initial choice of this type of cell was due to the great interest in Trp metabolism studies in tumor cells, which glioma cells has been a model. In assays with glioma cells, we followed the effects of an inductor and inhibitors of the first stage of Trp metabolism, via the kynurenine pathway, or IFN -γ (IDO inducer) 1- methyltryptophane (1- MT; competitive IDO inhibitor) and 680C91 (selective TDO inhibitor). We could observe the first step induction or inhibition impact had over the further metabolites and the metabolism differences between the two studied strains, A172 and T98G. The T98G glioma cell has only IDO activity, while the A172 has both IDO and TDO activity as well. The IFN-γ indution showed that this cytokine not only acts in the formation of QUIN route, but has a modest impact on the others routes. Inhibition of IDO showed that the competitive inhibitor has activity in itself than a simple Trp-QUIN relationship. However, our results allow us to show the first time the complete description of these pathways, in particular, in these cell lines that can assume therapeutic strategies in these routes that are related or not with tumor progression

Asociación entre los polimorfismos 5HTTLPR, uMAOA y depresión en una cohorte de pacientes de atención primaria / Association between serotonin transporter and monoamine oxidase A gene polymorphisms and depression

Background: Serotonin plays a central role regulating mood and on the development of depressive disorders. Aim: To study whether 5HTTLPR functional polymorphisms in the serotonin transporter gene or the Monoamine oxidase A gene (uMAOA) were risk markers for depression. Material and Methods: The Composite International Diagnostic Interview (CIDI) was applied to 1,062 consultants in primary health care centers aged between 18 and 75 years to establish the diagnosis of depression. A sample of saliva was obtained for DNA extraction and genetic analyses. Results: No association between the presence of depressive disorders and 5HTTLPR (ss) or uMAOA (3/3) risk genotypes was found. Psychological abuse and the presence of two or more life events were found to be predictors of depression in the studied sample. Conclusions: In this study, 5HTTLPR and uMAOA polymorphisms were not risk factors for depression. However, psychological abuse and the presence of two or more life events were risk factors for depressive disorders.

Lack of association between the 5-HTTLPR and positive screening for mental disorders among children exposed to urban violence and maltreatment

Objective: To ascertain whether genetic variations in the serotonin transporter gene (5-HTTLPR 44-bp insertion/deletion polymorphism) influence an increase in depressive and anxiety symptoms in children and adolescents exposed to high levels of violence. Methods: Saliva samples were collected from a group of children who were working on the streets and from their siblings who did not work on the streets. DNA was extracted from the saliva samples and analyzed for 5-HTTLPR polymorphism genotypes. Results: One hundred and seventy-seven children between the ages of 7 and 14 years were analyzed (114 child workers and 63 siblings). Data on socioeconomic conditions, mental symptoms, and presence and severity of maltreatment and urban violence were collected using a sociodemographic inventory and clinical instruments. There was no positive correlation between the 5-HTTLPR polymorphism and presence of mental symptoms in our sample, although the children were exposed to high levels of abuse, neglect, and urban violence. Conclusions: Despite previous studies that associated adult psychiatric disorders with the 5-HTTLPR polymorphism and a history of childhood maltreatment, no such association was found in this sample of children at risk. .

Genetic polymorphism in the serotonin transporter gene-linked polymorphic region and response to serotonin reuptake inhibitors in patients with premature ejaculation

OBJECTIVES: Serotonin plays a central role in ejaculation and selective serotonin reuptake inhibitors have been successfully used to treat premature ejaculation. Here, we evaluated the relationship between a polymorphism in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the response of patients with premature ejaculation to SSRI medication. METHODS: Sixty-nine premature ejaculation patients were treated with 20 mg/d paroxetine for three months. The Intravaginal Ejaculatory Latency Time and International Index of Erectile Function scores were compared with baseline values. The patients were scored as having responded to therapy when a 2-fold or greater increase was observed in Intravaginal Ejaculatory Latency Time compared with baseline values after three months. Three genotypes of 5-HTTLPR were studied: LL, LS and SS. The appropriateness of the allele frequencies in 5-HTTLPR were analyzed according to Hardy-Weinberg equilibrium using the χ2-test. RESULTS: The short (S) allele of 5-HTTLPR was significantly more frequent in responders than in nonresponders (p<0.05). Out of the 69 total PE patients, 41 patients (59%) responded to therapy. There was no significant difference in the International Index of Erectile Function score at the end of therapy between the responder and nonresponder groups. The frequencies of the L allele and S allele were 20% and 39%, respectively, in the responder group (p<0.05). CONCLUSION: We conclude that premature ejaculation patients with the SS genotype respond well to selective serotonin reuptake inhibitor therapy. Further studies with large patient groups are necessary to confirm this conclusion. .

Mini-revisión: Variantes genéticas del transportador de serotonina en trastornos neuropsiquiátricos / Serotonin Transporter gene variants in neuropsychiatric disorders

The SLC6A4 gene encodes the serotonin transporter SERT. Since the discovery of the role of SLC6A4 polymorphisms on human behavior, there is an increasingly growing wealth of information regarding SLC6A4 gene variants associated with anxiety and mood disorders, as well as their pharmacogenetic implications. In this brief review, the main discoveries on SLC6A4 variants, their functional impact and their suggested roles in neuropsychiatric and neurodevelopmental disorders are discussed.

El gen SLC6A4 codifica el transportador de serotonina SERT. Desde el descubrimiento inicial del rol que tienen polimorfismos de SLC6A4 en el comportamiento humano, hay una creciente cantidad de información acerca de variantes genéticas de SLC6A4 asociadas con trastornos de ansiedad y de estado de ánimo, así como de sus implicancias farmacogenéticas. En esta breve revisión, se discuten los principales descubrimientos de variantes de SLC6A4, su impacto funcional y sus roles sugeridos en enfermedades neuropsiquiátricas y de neurodesarrollo.

Evidencia de asociación entre el gen SLC6A4 y efectos epistáticos con variantes en HTR2A en la etiología del autismo en la población antioqueña / Evidence for association and epistasis between the genetic markers SLC6A4 and HTR2A in autism etiology

Introducción. El espectro autista constituye un grupo de trastornos graves del neurodesarrollo, con un fuerte componente genético. Se ha sugerido un papel importante del sistema serotoninérgico en el desarrollo de este grupo de trastornos, con base en los estudios de respuesta a medicamentos y la hiperserotoninemia, característica común en el autismo. Se han implicado múltiples moléculas en el metabolismo y la neurotransmisión de la serotonina; sin embargo, los resultados de los estudios han tenido poca congruencia entre diferentes poblaciones. Objetivos. Evaluar la relación entre el autismo y el polimorfismo de nucleótido simple (Single Nucleotide Polymorphism, SNP) en los genes SLC6A4, HTR2A e ITGB3, en una muestra de la población antioqueña. Materiales y métodos. Se genotipificaron 42 núcleos familiares con autismo para 10 variantes en los genes SLC6A4, ITGB3 y HTR2A. Se evaluó la asociación utilizando la prueba de desequilibrio en la transmisión. Se exploró el impacto de la interacción entre estos genes y el autismo, utilizando la reducción multidimensional. Resultados. Se encontró asociación de las variantes rs4583306 (OR=2,6, p=0,004) y rs2066713 (OR=2,2 p=0,03), en el gen SLC6A4, y asociación de combinaciones genotípicas entre los genes SLC6A4 y HTR2A y el riesgo de autismo (p=0,0001). Conclusiones. Se encontró asociación significativa con variantes en el gen transportador de serotonina con el autismo, al igual que interacción entre variantes en los genes HTR2A con SLC6A4. Estos resultados concuerdan con los de estudios previos en otras poblaciones y son pruebas a favor del papel del sistema serotoninérgico en la etiología del espectro autista.

Introduction. Autism spectrum disorders are severe neurodevelopmental disorders with a strong genetic component. The potential role of the serotoninergic system in the development of autistic disorder has been based on the observation of hyperserotoninemia in autistic subjects and the results of drug treatment studies. Multiple molecules involved in serotonin metabolism and neurotransmission have been studied; however, replication studies have been inconsistent. This may be partially related to the marked genetic heterogeneity of autism in different populations. Objectives. The relationship between autism and single nucleotide polymorphisms of SLC6A4, HTR2A and ITGB3 genes was evaluated in an urban population of northwestern Colombia. Materials and methods. In Antioquia, Colombia, 42 families with history of autism were screened for 10 SNPs in SLC6A4, HTR2A and ITGB3 genes and evaluated for associations with the transmission disequilibrium test. The interactions among these genes and autism was assessed with multidimensional reduction methods. Results. A significant main effect was seen among the SLC6A4 gene variants rs4583306 (OR=2.6, p=0.004) and rs2066713 (OR=2.2, p=0.03). No main effect of the ITGB3 or HTR2A variants was found, however, in the interaction effects, the SLC6A4 and HTR2A genes demonstrated significant evidence of association with autism (p<0.001). Conclusion. Significant association of markers were discovered within the SLC6A4 gene and the combination of SLC6A4 and HTR2A (S-A) genes to autism. These results were consistent with previous studies conducted in other populations and provide further evidence for the implication of the serotoninergic system in the etiology of autistic disorders.

Effect of the 5-HT4 receptor and serotonin transporter on visceral hypersensitivity in rats

Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT4 receptor and the serotonin transporter (SERT) as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times) between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT4 receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05) and increased 5-HT4 receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05). Treatment with fluoxetine (10 mg·kg-1·day-1, days 36-42), tegaserod (1 mg·kg-1·day-1, day 43), or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT4 receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01) but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654). These results indicate that both the 5-HT4 receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT level.

Polimorfismos en el gen del transportador de serotonina (SLC6A4) y el trastorno afectivo bipolar en dos centros regionales de salud mental del Eje Cafetero(Colombia) / Polymorphism in the serotonin transporter gene (SLC6A4) and emotional bipolar disorder in two regional mental health centers from the Eje Cafetero (Colombia)

Introducción: Los polimorfismos indel en la región promotora y los polimorfismos de tamaño en el intrón 2 del gen transportador de serotonina se han asociado con el trastorno afectivo bipolar 1 (TAB 1) en diferentes poblaciones. El objetivo fue analizar las frecuencias genotípicas y alélicas en ambas regiones del gen en un estudio de casos y controles en Risaralda y Quindío (Colombia) para encontrar una asociación con TAB 1 y compararlas con estudios similares. Métodos: Se analizaron 133 pacientes y 120 controles. Con PCR se analizaron los polimorfismos indel L y S de la región promotora y los de tamaño (VNTR) STin 2.10 y STin 2.12 del segundo intrón del gen SLC6A4. Resultados: Las frecuencias genotípicas y alélicas en los polimorfismos S y L fueron muy similares en casos y controles. Sin embargo, el genotipo LL se encontró incrementado no significativamente en la población general con TAB 1 (OR=1,89; IC95%= 1,1-3,68) y al separarla por género. Los OR para este genotipo en la oblación general (OR=1,89; IC95%=1,1-3,68) en mujeres (OR=2,22; IC95%=1,04-5,66) y en hombres (OR=1,62; IC95%=0,71-4,39). En los polimorfismos VNTR STin 2.10 y STin2.212 tampoco se observaron diferencias significativas entre las frecuencias genotípicas y alélicas. Conclusiones: No encontramos asociación entre los polimorfismos de las regiones 5-HTTLPR y el intrón 2 del gen transportador de serotonina en los pacientes con TAB 1, ni en la población total, ni al separarla por género. Nuestros resultados son similares a los encontrados en poblaciones caucásicas y difieren de los encontrados en asiáticas y brasileras…

Introduction: The indel polymorphisms in the promoting region and the 2nd intron polymorphisms in the serotonin transporter gene (SLC6A4) have been associated to bipolar disorder 1 (BD1) in several population studies. The objective was to analyze the genotypic and allelic frequencies in both gene regions in a study of cases and controls with individuals from Risaralda and Quindío (Colombia) so as to establish possible associations to BD1, and compare results with previous and similar studies. Methods: 133 patients and 120 controls were studied. L and S indel polymorphisms in the promoting region were analyzed by PCR, together with VNTR STin2.10 and STin 2.12 VNTRs polymorphisms in the 2nd intron of the SLC6A4 gene Results: Genotypic and allelic frequencies for the S and L polymorphisms were similar both in cases and controls. However, the LL genotype was significantly increased both in BD1 population (OR=1.89; CI95%=1.1-3.68), and when discriminated by gender. This particular genotype in general population is OR=2.22; IC95%=1.04-5.66 for women, and OR=1.62; IC 95%=0.71-4.39 for men. No significant genotypic and allelic differences were found for VNTR STin2.10 and STin 2.12. polymorphisms. Conclusions: No association was found between polymorphisms of 5-HTTLPR polymorphisms and the 2nd intron of the serotonin ransporting gene in general patients with BD1, nor when compared by gender. Our results are similar to those reported for Caucasian populations and differ from those of Asian and Brazilian populations…

Serotonin transporter gene polymorphisms: a case-control study

Considerable evidence indicates that serotonergic mechanisms, particularly the serotonin transporter, are involved in alcoholism and tobacco use and are influenced by polymorphism of the promoter region of 5HTT (5-HTTLPR). As alcohol and tobacco consumption have been implicated in the pathogenesis of oral cancer, the purpose of this study was to investigate 5-HTTLPR polymorphism in patients with oral squamous cell carcinoma (OSCC) compared with a control group in a sample of Brazilian patients. One hundred and three patients affected by OSCC and 103 volunteers without OSCC were genotyped for 5-HTTLPR. Both groups were matched for age, sex and tobacco use. The chi-squared test was used for statistical analysis (α=0.05). There was no statistically significant difference in 5-HTTLPR genotypes between case and control group (p= 0.408). In conclusion, the present investigation demonstrated that serotonin transporter polymorphisms are not implicated in the OSSC development.

Consideráveis evidências indicam que mecanismos serotoninérgicos, particularmente o transportador de serotonina, estão envolvidos no alcoolismo e no uso de fumo e são influenciados pelo polimorfismo da região promotora do 5HTT (5-HTTLPR). Como o consumo de álcool e fumo está implicado na patogênese do câncer, o objetivo deste estudo foi investigar o polimorfismo 5-HTTLPR em pacientes com carcinoma bucal de células escamosas (CBCE) comparado com um grupo controle em uma amostra de pacientes brasileiros. Cento e três pacientes afetados por CBCE e 103 voluntários sem história de CBCE foram genotipados para 5-HTTLPR. Ambos os grupos foram pareados pela idade, gênero e uso de fumo. O teste do qui-quadrado foi usado para análise estatística. Não houve diferença estatística entre os genótipos dos grupos caso e controle (p= 0,408). Concluindo, a presente investigação demonstrou que os polimorfismos do transportador de serotonina não estão implicados no desenvolvimento do CBCE.