Synthesis and biological evaluation of thioadatanserin and its dialkylated products as partial 5-HTR1A agonists and 5-HTR2A antagonists for potential use in depression and anxiety disorders.

Thionation of adatanserin hydrochloride (2) with Lawesson's reagent in toluene/triethylamine afforded novel compound, (3r,5r,7r)-N-(2-(4-(pyrimidin-2-yl)piperazin-1-yl)ethyl)adamantane-1-carbothioamide (thioadatanserin, 3) in 84-90% isolated yield. Thioadatanserin underwent a tandem double alkylation with methyl iodide and benzyl bromide in NaH/THF to produce novel dialkylated products 6 and 7 respectively. The single X-ray crystal structure of 7 was determined to be 1-(2-((E- ((3r,5r,7r)-adamantan-1-yl)benzylthio)methylene)amino)ethyl)-1-benzyl-4- (pyrimidin-2-yl)piperazin-1-ium bromide showing that the piperazine ring adopts a chair-like configuration that is not co-planar with the pyrimidine ring. Thioadatanserin emerged as a dual potent partial agonist with activity against 5-HTR1A (EC50 6.7 nM) and antagonist activity against 5-HTR2A (IC50 62.3 nM) and was selective over 5-HTR2C receptor (IC50 > 3333 nM) in the PathHunter® ß-arrestin assays.

Phytochemical screening and effect of Viscum album L. on monoamine oxidase A and B activity and serotonin, dopamine and serotonin receptor 5-HTR1A levels in Galleria mellonealla (Lepidoptera).

ETHNOPHARMACOLOGICAL RELEVANCE: Viscum album L. (European mistletoe), a member of the Santalaceae, is a hemiparasitic, evergreen shrub growing on deciduous and coniferous trees. In traditional and folk medicine, mistletoe was used for the treatment of central nervous system disorders such as epilepsy, hysteria, insomnia, nervous excitability, neuralgia, headache, dizziness and fatigue. However, relatively little is known of its neuropharmacological activity. AIM OF THE STUDY: The aim of the present study was to evaluate the effect of treatment with aqueous and hydroethanolic extracts from Viscum album L. parasitizing birch, linden and pine, on MAO-A and MAO-B activity as well as serotonin, dopamine and serotonin receptor 5-HTR1A levels in Galleria mellonella (Lepidoptera) larvae. MATERIALS AND METHODS: The phytochemical composition of the extracts was characterised using UPLC-DAD-ESI-MS/MS. To investigate the neuropharmacological activity of Viscum album L. extracts, Galleria mellonella (Lepidoptera) larvae were used as a model organism. The inhibitory potential of the extracts against MAO-A and MAO-B was determined by fluorometry. The serotonin, dopamine and serotonin receptor 5-HTR1A levels in larvae hemolymph after treatment were quantified by ELISA. RESULTS: UPLC-DAD-ESI-MS/MS analysis allowed the identification of 88 compounds, either full or in part. Most of the characterised phytochemicals were flavonoids, hydroxycinnamic acids and lignans. Screening found that aqueous and hydroethanolic mistletoe extracts inhibited the enzymatic activity of either MAO-A or MAO-B or both. Additionally, mistletoe extract administration increased the levels of serotonin and serotonin receptor 5-HTR1A. None of the tested extracts had any significant effect on dopamine level. CONCLUSIONS: A key novel finding was that the aqueous and hydroethanolic extracts from Viscum album L. inhibited monoamine oxidase activity and increased the levels of serotonin and serotonin receptor 5-HTR1A in Galleria mellonella (Lepidoptera) larvae. These properties may be due to the presence of phenolic constituents, particularly flavonoids. Further research based on bioassay-guided fractionation of mistletoe is needed to identify CNS-active molecules.

A preliminary association study between serotonin transporter (5-HTTLPR), receptor polymorphisms (5-HTR1A, 5-HTR2A) and depression symptom-clusters in a north Indian population suffering from Major Depressive Disorder (MDD).

INTRODUCTION: Major Depressive Disorder (MDD) is a broad heterogeneous diagnostic construct. Previous studies have shown that it can be resolved into several symptom-clusters which are proposed to be associated with single nucleotide polymorphisms (SNPs) of the serotonergic pathway (5-HTTLPR, 5HTR1A, 5-HTR2A). METHODS AND MATERIAL: In a cross-sectional study conducted at a tertiary level mental health care set-up in north India, 80 out-patients with MDD were evaluated with Montgomery Asberg Depression Rating Scale (MADRS) and then genotyping was done. The different clinical and genetic variables were compared across the factor structures of MADRS. Also, the comparison of the genetic data of cases was done with the pre-existing database of the non-blood related healthy ethnically-matched controls. RESULTS: There was no significant association between age, gender, other clinical variables, SNPs like 5-HTTLPR SS/SL, rs6295 CC/CG/GG, rs6311GG/GA/AA, rs6313 CC/CT/TT and different factor-structures like 'detachment' consisting of items like concentration difficulty, lassitude, inability to feel; 'psychic anxiety' consisting of suicidal thoughts and inner tension; 'mood-pessimism' consisting of symptoms like apparent sadness, reported sadness, pessimistic thoughts and 'vegetative symptoms' like decreased sleep, poor appetite. Neither there was any association between genotype of the cases compared with the controls. CONCLUSIONS: No significant association was obtained between the four-factor structures of depression in MADRS and serotonin transporter and receptor SNPs in a study with a small sample size. This study evaluates whether depression symptom-clusters have distinct genotypic determinants and necessitates more comprehensive studies for unravelling the genetic determinants of depression.

Serotonergic gene polymorphisms (5-HTTLPR, 5HTR1A, 5HTR2A), and population differences in aggression: traditional (Hadza and Datoga) and industrial (Russians) populations compared.

BACKGROUND: Current knowledge on genetic basis of aggressive behavior is still contradictory. This may be due to the fact that the majority of studies targeting associations between candidate genes and aggression are conducted on industrial societies and mainly dealing with various types of psychopathology and disorders. Because of that, our study was carried on healthy adult individuals of both sex (n = 853). METHODS: Three populations were examined: two traditional (Hadza and Datoga) and one industrial (Russians), and the association of aggression with the following polymorphisms 5-HTTLPR, rs6295 (5HTR1A gene), and rs6311 (5HTR2A gene) were tested. Aggression was measured as total self-ratings on Buss-Perry Aggression Questionnaire. RESULTS: Distributions of allelic frequencies of 5-HTTLPR and 5HTR1A polymorphisms were significantly different among the three populations. Consequently, the association analyses for these two candidate genes were carried out separately for each population, while for the 5HTR2A polymorphism, it was conducted on the pooled data that made possible to introduce ethnic factor in the ANOVA model. The traditional biometrical approach revealed no sex differences in total aggression in all three samples. The three-way ANOVA (µ + 5-HTTLPR + 5HTR1A + 5HTR2A +ε) with measures of self-reported total aggression as dependent variable revealed significant effect of the second serotonin receptor gene polymorphism for the Hadza sample. For the Datoga, the interaction effect between 5-HTTLPR and 5HTR1A was significant. No significant effects of the used polymorphisms were obtained for Russians. The results of two-way ANOVA with ethnicity and the 5HTR2A polymorphism as main effects and their interactions revealed the highly significant effect of ethnicity, 5HTR2A polymorphism, and their interaction on total aggression. CONCLUSIONS: Our data provided obvious confirmation for the necessity to consider the population origin, as well as cultural background of tested individuals, while searching for associations between genes and behavior, and demonstrated the role of cultural attitudes towards the use of in-group aggression. Our data partly explained the reasons for disagreement in results of different teams, searching for candidate-gene associations with behavior without considerations of culturally desirable norms. Previous studies suggested that the 5HTR2A gene polymorphism associates with aggression and criminality. Our data extended these findings, demonstrating the role of rs6311 (5HTR2A gene) in aggression in adult healthy men and women from our samples. We found that G-allele carriers were rated higher on total aggression.

The impact of cue learning, trait anxiety and genetic variation in the serotonin 1A receptor on contextual fear.

In everyday life, aversive events are usually associated with certain predictive cues. Normally, the acquisition of these contingencies enables organisms to appropriately respond to threat. Presence of a threat cue clearly signals 'danger', whereas absence of such cues signals a period of 'safety'. Failure to identify threat cues may lead to chronic states of anxious apprehension in the context in which the threat has been imminent, which may be instrumental in the pathogenesis of anxiety disorders. In this study, existing data from 150 healthy volunteers in a cue and context virtual reality fear conditioning paradigm were reanalyzed. The aim was to further characterize the impact of cue acquisition and trait anxiety, and of a single nucleotide polymorphism in the serotonin 1A receptor gene (5-HTR1A, rs6295), on cued fear and contextual anxiety before and after fear contingencies were explicitly introduced. Fear conditioned responding was quantified with fear potentiation of the eyeblink startle reflex and subjective fear ratings. First, we replicated previous findings that the inability to identify danger cues during acquisition leads to heightened anxious apprehension in the threat context. Second, in subjects who did not identify the danger cue initially, contextual fear was associated with trait anxiety after the contingencies were explicitly instructed. Third, genetic variability within 5-HTR1A (rs6295) was associated with contextual fear independent of awareness or trait anxiety. These findings confirm that failure to acquire cue contingencies impacts contextual fear responding, in association with trait anxiety. The observed 5-HTR1A effect is in line with models of anxiety, but needs further replication.

The Effects of 5-HTR1A Polymorphism on Cingulum Connectivity in Patients with Panic Disorder.

OBJECTIVE: Serotonin-1A receptors (5-HTR1A) is suggested to be involved in the etiology of several psychiatric disorders including panic disorder (PD). A few imaging studies have suggested the alterations of the cingulum bundle in PD. The objective of this study is to examine the structural changes of cingulum related to the 5-HTR1A polymorphism rs6295 in the patients with PD. METHODS: Thirty-two right-handed patients with PD [11 men, 21 women; 40.34±13.17 (mean±SD) age] who met the diagnostic criteria in Structured Clinical Interview for DSM-IV were examined by means of MRI at 3 Tesla. We divided the patients with PD into CC genotype group and non CC genotype group (GG/CG genotype group) of the 5-HTR1A rs6295 polymorphism to compare the cingulum white matter connectivity. RESULTS: Tract-based spatial statistics showed significantly increased fractional anisotropy (FA) values in cingulate gyrus process of left cingulum in 5-HTR1A CC genotype compared to GG/CG genotype in PD. Significant positive correlations were shown between the Albany Panic and Phobia Questionnaire (APPQ) interoceptive fear subscale scores, the Anxiety Sensitivity Inventory-Revised fear of publicly observable anxiety reaction subscale scores and FA values of cingulate gyrus process of left cingulum in 5-HTR1A rs6295 GG/CG genotype group. In CC genotype group, APPQ total, APPQ agoraphobia subscale and APPQ social phobia subscale scores also showed significant positive correlations with FA values of hippocampal process of right cingulum. CONCLUSION: This preliminary study suggests that 5-HTR1A polymorphism may be associated with the cingulum white matter connectivity in PD.

Genetic association studies between SNPs and suicidal behavior: a meta-analytical field synopsis.

The large number of published meta-analyses on the associations between single-nucleotide polymorphisms (SNPs) and suicidal behavior mirrors the enormous research interest in this topic. Although meta-analytic evidence is abundant and certain patterns are apparent, those have not been integrated into a general framework as of yet. In a systematic review, genetic association studies between SNPs and suicidal behavior were identified. Previously published meta-analyses for eight SNPs were updated and the results of the different meta-analyses were compared. Meta-analyses for 15 SNPs, which had not been subjected to meta-analysis before, were conducted. The present meta-analytical field synopsis showed five major similarities between new and published analyses: 1) Summary effect sizes were small and rarely statistically significant, 2) heterogeneity between studies was often substantial, 3) there were no time trends, 4) effects were easily swayed and were largely dependent on individual studies, and 5) publication bias does not play a role in this field of research. Meta-analytic data show once more that major contributions of single genes are unlikely. However, association studies and corresponding meta-analyses have been an important and necessary stepping stone in the development of modern and more complex approaches in the genetics of suicidal behavior.