Recombinant GABA-A receptors - in vitro model to study the effects of neurosteroid dehydroepiandrosterone sulphate

Dehidroepiandrosteron-sulfat (DHEAS) je neurosteroid uključen u važne funkcije mozga poput neuralne plastičnosti, učenja, pamćenja i ponašanja, te pokazuje potencijal u liječenju različitih neuropsihijatrijskih poremećaja, uključujući i ishemijski moždani udar. Učinci DHEAS-a u središnjem živčanom sustavu posredovani su putem GABA i glutamatnog neurotransmitorskog sustava, ali i drugih. Cilj rada bio je ispitati učinke primjene DHEAS-a na rekombinantne GABAA receptore, usporedbom djelovanja ovog neurosteorida na embrionalne stanice bubrega čovjeka (HEK 293), netransficirane i stabilno transficirane GABAA receptorima 122S, te istražiti njegovo potencijalno neuroprotektivno djelovanje u modelu deprivacije kisika i glukoze, te reperfuzije in vitro (OGDR). Istraživanje je pokazalo da se DHEAS ponaša kao alosterički antagonist rekombinantnih GABAA receptora, ali da njegova produljena primjena ne utječe na broj, afinitet, kao ni na funkcionalnu povezanost receptorskih veznih mjesta. Rezultati su također pokazali da DHEAS, primijenjen i prije i nakon OGDR djeluje protektivno na stanice HEK 293, te da se citoprotektivan učinak ovog neurosteroida barem dijelom ostvaruje putem GABAA receptora.Dehydroepiandrosterone sulfate (DHEAS) is a neurosteroid involved in various important brain functions such as neural plasticity, learning, memory and behavior, demonstrating the potential to treat a variety of neuropsychiatric disorders, including ischemic stroke. Effects of DHEAS in the central nervous system are mediated through GABAergic, glutamatergic and other neurotransmitter systems. The aim of this study was to investigate the effects of DHEAS on recombinant GABAA receptors by comparing the effects of this neurosteorid on human embryonic kidney (HEK) 293 cells, stably transfected and untransfected with 122S GABAA receptors, and to explore the potential neuroprotective effect of this neurosteroid using in vitro model of oxygen and glucose deprivation and reperfusion (OGDR). The study has shown that DHEAS acts as an allosteric antagonist of recombinant GABAA receptors, but that its prolonged administration does not affect the number, affinity, or the functional coupling of receptor binding sites. The results also suggested that DHEAS, applied both before and after OGDR has protective effect on HEK 293 cells, and that cytoprotective effect of this neurosteroid is at least partly achieved via GABAA receptors

THE ASSOCIATION BETWEEN SEROTONIN TRANSPORTER POLYMORPHISM, PLATELET SEROTONIN CONCENTRATION AND INSOMNIA IN NON-DEPRESSED VETERANS WITH POSTTRAUMATIC STRESS DISORDER

Background: The role of serotonin transporter and its functional gene polymorphism (5-HTTLPR, serotonin transporter linked polymorphic region) was investigated in sleep disturbances in various mental disorders, with conflicting findings. Here, the association of particular sleep disturbances with 5-HTTLPR genotypes and platelet serotonin (5 HT) concentration was determined simultaneously in veterans with posttraumatic stress disorder (PTSD), who were subdivided into those with or without comorbid depression. Subjects and methods: Croatian male, medication-free war veterans with PTSD (N=325), subdivided into those with or without comorbid depression, and subdivided further according to the various sleep disturbances, were evaluated using the Structured Clinical Interview, the Hamilton Rating Scale for Depression and the Clinician Administered PTSD Scale. Genotyping and platelet 5-HT concentration measurements were conducted using PCR and spectrofluorimetric methods, respectively. Results: Nominally higher frequency of the 5-HTTLPR LL genotype compared to S carriers (p=0.026; ????² test) and significantly higher platelet 5-HT concentration (p=0.001; one-way ANOVA) were detected in non-depressed veterans with PTSD with early insomnia, compared to matched veterans without early insomnia. Conclusions: Over-representation of the LL genotype of the 5-HTTLPR and higher platelet 5-HT concentrations were detected in veterans with PTSD who did not develop comorbid depression but had severe early insomnia. These results suggest that 5- HTTLPR genotypes and platelet 5-HT concentration are associated with early insomnia in non-depressed veterans with PTSD. Limitations of the study were the cross-sectional nature of the study, biallelic assessment of the 5-HTTLPR, and a lack of use of the specific sleep measurement scales. These results should be replicated in larger samples, validated on different populations, using specific sleep measurement scales and triallelic 5-HTTLPR assessment

REMISSION IS NOT ASSOCIATED WITH DRD2 RS1800497 AND DAT1 RS28363170 GENETIC VARIANTS IN MALE SCHIZOPHRENIC PATIENTS AFTER 6-MONTHS MONOTHERAPY WITH OLANZAPINE

Background: Symptomatic remission is an achievable goal in the treatment of schizophrenia. The type of antipsychotic medication and particular genetic variants of the dopaminergic system might be associated with remission. Potential pharmacogenetic markers of the treatment response to antipsychotic medication are missing. This study assessed the possible association between dopamine receptor type 2 (DRD2 rs1800497) and dopamine transporter (DAT1 rs28363170) gene variants with symptomatic remission in schizophrenia. Subjects and methods: Olanzapine (5-20 mg/d) monotherapy was administered for 6 months to 150 male Caucasian subjects with schizophrenia. Remission was evaluated according to "Remission in Schizophrenia Working Group" criteria. Genotyping was performed by PCR-RFLP. Results: Symptomatic remission was found in 31% of patients. DRD2 rs1800497 and DAT1 rs28363170 gene variants were not significantly associated with symptomatic remission. The limitations are a relatively small sample size of patients with schizophrenia (N=150), especially of group with symptomatic remission (N=45). However, the study had moderate but adequate sample sizes for most of the comparisons. Only two dopaminergic polymorphisms were analyzed, and plasma concentration of olanzapine was not determined. Conclusion: These results revealed a lack of association between DRD2 rs1800497 and DAT1 rs28363170 genetic variants and symptomatic remission in male patients treated with olanzapine, suggesting that these genetic variants could not be used to predict symptomatic remission to olanzapine monotherapy. Negative results should be further confirmed or rejected in the larger samples, including haplotype analyses, to detect clinically useful and easy obtainable pharmacogenetic markers that might predict therapeutic response or remission in schizophrenia

ANHEDONIA IN SCHIZOPHRENIA: MINI-REVIEW

The perception of reward exerts a powerful influence on human behavior. While anhedonia might occur in healthy individuals, its prevalence and severity are much higher in psychiatric patients, particularly those with depression and schizophrenia. Anhedonia is a negative symptom, and presumably a trait marker in schizophrenia. Recent research confirmed that anhedonia is a complex construct, consisting of anticipatory, consummatory, and reward learning components. In general, schizophrenia patients show anticipation deficits, and a substantial portion of them have physical (PA) and social anhedonia (SA). The relationship between anhedonia and psychopathology appears bidirectional. While gene-environment interactions affect reward circuity, anhedonia modulates clinical features, such as suicidality and nicotine consumption. Future clinical research employing longitudinal designs may shed more light on the dynamics and treatment of anhedonia in schizophreni

N-glycomic Profile in Combat Related Post- Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) develops in a portion of individuals exposed to extreme trauma. Glycosylation is a post-translational modification that affects protein functions and is altered in various pathophysiological states and aging. There are still no validated biomarkers of PTSD. The aim of this study was to evaluate the N-glycomic profile in 543 male Caucasian individuals (299 veterans with PTSD and 244 control subjects). The study included discovery (N = 233) and replication (N = 310) cohort. Hydrophilic interaction HPLC and ultra- performance liquid chromatography were used to separate and detect 39 plasma and 24 IgG N- glycan species, respectively. All results were corrected for the effects of age and multiple testing. Significant results included only significantly altered N-glycans in cases/controls in both cohorts, in the same direction. Results showed that six plasma N- glycans (four increased and two decreased) were altered in PTSD vs. controls in both cohorts, but IgG N-glycans were similar between groups. The severity of PTSD was not associated with different plasma N-glycans. This is the first study detecting alterations in plasma N-glycans in PTSD. These N-glycans are also associated with other neuropsychiatric disorders and inflammation, suggesting possible shared glycosylation mechanisms

The associations between COMT and MAO-B genetic variants with negative symptoms in patients with schizophrenia

Negative symptoms of schizophrenia, including anhedonia, represent a heavy burden on patients and their relatives. These symptoms are associated with cortical hypodopamynergia and impaired striatal dopamine release in response to reward stimuli. Catechol-O-methyltransferase (COMT) and monoamine oxidase type B (MAO-B) degrade dopamine and affect its neurotransmission. The study determined the association between COMT rs4680 and rs4818, MAO-B rs1799836 and rs6651806 polymorphisms, the severity of negative symptoms, and physical and social anhedonia in schizophrenia. Sex-dependent associations were detected in a research sample of 302 patients with schizophrenia. In female patients with schizophrenia, the presence of the G allele or GG genotype of COMT rs4680 and rs4818, as well as GG haplotype rs4818-rs4680, which were all related to higher COMT activity, was associated with an increase in several dimensions of negative symptoms and anhedonia. In male patients with schizophrenia, carriers of the MAO-B rs1799836 A allele, presumably associated with higher MAO-B activity, had a higher severity of alogia, while carriers of the A allele of the MAO-B rs6651806 had a higher severity of negative symptoms. These findings suggest that higher dopamine degradation, associated with COMT and MAO-B genetic variants, is associated with a sex-specific increase in the severity of negative symptoms in schizophrenia patients

Plasma Brain-Derived Neurotrophic Factor (BDNF) Concentration and BDNF/TrkB Gene Polymorphisms in Croatian Adults with Asthma

Brain-derived neurotrophic factor (BDNF) and its tropomyosin-related kinase B (TrkB) receptor might contribute to normal lung functioning and immune responses ; however, their role in asthma remains unclear. Plasma BDNF concentrations, as well as BDNF and NTRK2 (TrkB gene) polymorphisms, were investigated in 120 asthma patients and 120 healthy individuals using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively. The genotype and allele frequencies of BDNF Val66Met (rs6265) and NTRK2 rs1439050 polymorphisms did not differ between healthy individuals and asthma patients, nor between patients grouped according to severity or different asthma phenotypes. Although plasma BDNF concentrations were higher among healthy subjects carrying the BDNF Val66Met GG genotype compared to the A allele carriers, such differences were not detected in asthma patients, suggesting the influences of other factors. Plasma BDNF concentration was not affected by NTRK2 rs1439050 polymorphism. Asthma patients had higher plasma BDNF concentrations than control subjects ; however, no differences were found between patients subdivided according to asthma severity, or Type-2, allergic, and eosinophilic asthma. Higher plasma BDNF levels were observed in asthma patients with aspirin sensitivity and aspirin-exacerbated respiratory disease. These results suggest that plasma BDNF may serve as a potential peripheral biomarker for asthma, particularly asthma with aspirin sensitivity

Short overview on metabolomic approach and redox changes in psychiatric disorders

Schizophrenia, depression and posttraumatic stress disorder (PTSD) are severe mental disorders and complicated diagnostic entities, due to their phenotypic, biological and genetic heterogeneity, unknown etiology, and poorly understood alterations in biological pathways and biological mechanisms. Disturbed homeostasis between overproduction of oxidant species, overcoming redox regulation and a lack of cellular antioxidant defenses, resulting in free radical-mediated pathology and subsequent neurotoxicity contributes to development of depression, schizophrenia and PTSD, their heterogeneous clinical presentation and resistance to treatment. Metabolomics is a discipline that combines different strategies with the aim to extract, detect, identify and quantify all metabolites that are present in a biological sample and might provide mechanistic insights into the etiology of various psychiatric disorders. Therefore, oxidative stress research combined with metabolomics might offer a novel approach in dissecting psychiatric disorders, since these data-driven but not necessarily hypothesis-driven methods might identify new targets, molecules and pathways responsible for development of schizophrenia, depression or PTSD. Findings from the oxidative research in psychiatry together with metabolomics data might facilitate development of specific and validated prognostic, therapeutic and clinical biomarkers. These methods might reveal bio- signatures of individual patients, leading to individualized treatment approach. In reviewing findings related to oxidative stress and metabolomics in selected psychiatric disorders, we have highlighted how these novel approaches might make a unique contribution to deeper understanding of psychopathological alterations underlying schizophrenia, depression and PTSD