Do the estrogen receptors 1 gene variants influence the temperament and character inventory scores in suicidal attempters and healthy subjects?

Sex differences in avoidance behavior and cued threat memory dynamics in mice: Interactions between estrous cycle and genetic background

Anxiety disorders are the most prevalent mental illnesses worldwide, exhibit high heritability, and affect twice as many women as men. To evaluate potential interactions between genetic background and cycling ovarian hormones on sex differences in susceptibility to negative valence behaviors relevant to anxiety disorders, we assayed avoidance behavior and cued threat memory dynamics in gonadally-intact adult male and female mice across four common inbred mouse strains: C57Bl/6J, 129S1/SVlmJ, DBA/2J, and BALB/cJ. Independent of sex, C57Bl/6J mice exhibited low avoidance but high threat memory, 129S1/SvlmJ mice high avoidance and high threat memory, DBA/2J mice low avoidance and low threat memory, and BALB/cJ mice high avoidance but low threat memory. Within-strain comparisons revealed reduced avoidance behavior in the high hormone phase of the estrous cycle (proestrus) compared to all other estrous phases in all strains except DBA/2J, which did not exhibit cycle-dependent behavioral fluctuations. Robust and opposing sex differences in threat conditioning and extinction training were found in the C57Bl/6J and 129S1/SvlmJ lines, whereas no sex differences were observed in the DBA/2J or BALB/cJ lines. C57Bl/6J males exhibited enhanced acute threat memory, whereas 129S1/SvlmJ females exhibited enhanced sustained threat memory, compared to their sex-matched littermates. These effects were not mediated by estrous cycle stage or sex differences in active versus passive defensive behavioral responses. Our data demonstrate that core features of behavioral endophenotypes relevant to anxiety disorders, such as avoidance and threat memory, are genetically driven yet dissociable and can be influenced further by cycling ovarian hormones.

Polymorphisms in sex steroid receptors: From gene sequence to behavior

Sex steroid receptors have received much interest as potential mediators of human behaviors and mental disorders. Candidate gene association studies have identified about 50 genetic variants of androgen and estrogen receptors that correlate with human behavioral phenotypes. Because most of these polymorphisms lie outside coding regions, discerning their effect on receptor function is not straightforward. Thus, although discoveries of associations improve our ability to predict risk, they have not greatly advanced our understanding of underlying mechanisms. This article is intended to serve as a starting point for psychologists and other behavioral biologists to consider potential mechanisms. Here, I review associations between polymorphisms in sex steroid receptors and human behavioral phenotypes. I then consider ways in which genetic variation can affect processes such as mRNA transcription, splicing, and stability. Finally, I suggest ways that hypotheses about mechanism can be tested, for example using in vitro assays and/or animal models.

Intronic SNP in ESR1 encoding human estrogen receptor alpha is associated with brain ESR1 mRNA isoform expression and behavioral traits

Genetic variants of ESR1 have been implicated in multiple diseases, including behavioral disorders, but causative variants remain uncertain. We have searched for regulatory variants affecting ESR1 expression in human brain, measuring allelic ESR1 mRNA expression in human brain tissues with marker SNPs in exon4 representing ESR1-008 (or ESRα-36), and in the 3'UTR of ESR1-203, two main ESR1 isoforms in brain. In prefrontal cortex from subjects with bipolar disorder, schizophrenia, and controls (n = 35 each; Stanley Foundation brain bank), allelic ESR1 mRNA ratios deviated from unity up to tenfold at the exon4 marker SNP, with large allelic ratios observed primarily in bipolar and schizophrenic subjects. SNP scanning and targeted sequencing identified rs2144025, associated with large allelic mRNA ratios (p = 1.6E10-6). Moreover, rs2144025 was significantly associated with ESR1 mRNA levels in the Brain eQTL Almanac and in brain regions in the Genotype-Tissue Expression project. In four GWAS cohorts, rs2104425 was significantly associated with behavioral traits, including: hypomanic episodes in female bipolar disorder subjects (GAIN bipolar disorder study; p = 0.0004), comorbid psychological symptoms in both males and females with attention deficit hyperactivity disorder (GAIN ADHD, p = 0.00002), psychological diagnoses in female children (eMERGE study of childhood health, subject age ≥9, p = 0.0009), and traits in schizophrenia (e.g., grandiose delusions, GAIN schizophrenia, p = 0.0004). The first common ESR1 variant (MAF 12-33% across races) linked to regulatory functions, rs2144025 appears conditionally to affect ESR1 mRNA expression in the brain and modulate traits in behavioral disorders.

An overview of the neurobiology of suicidal behaviors as one meta-system

Suicidal behaviors (SB) may be regarded as the outmost consequence of mental illnesses, or as a distinct entity per se. Regardless, the consequences of SB are very large to both society and affected individuals. The path leading to SB is clearly a complex one involving interactions between the subject's biology and environmental influences throughout life. With the aim to generate a representative and diversified overview of the different neurobiological components hypothesized or shown implicated across the entire SB field up to date by any approach, we selected and compiled a list of 212 gene symbols from the literature. An increasing number of novel gene (products) have been introduced as candidates, with half being implicated in SB in only the last 4 years. These candidates represent different neuro systems and functions and might therefore be regarded as competing or redundant explanations. We then adopted a unifying approach by treating them all as parts of the same meta-system, using bioinformatic tools. We present a network of all components connected by physical protein-protein interactions (the SB interactome). We proceeded by exploring the differences between the highly connected core (~30% of the candidate genes) and its peripheral parts, observing more functional homogeneity at the core, with multiple signal transduction pathways and actin-interacting proteins connecting a subset of receptors in nerve cell compartments as well as development/morphology phenotypes and the stress-sensitive synaptic plasticity processes of long term potentiation/depression. We suggest that SB neurobiology might also be viewed as one meta-system and perhaps be explained as intrinsic unbalances acting within the core or as imbalances arising between core and specific peripheral components.

Sex hormone activity in alcohol addiction: integrating organizational and activational effects

There are well-known sex differences in the epidemiology and etiopathology of alcohol dependence. Male gender is a crucial risk factor for the onset of alcohol addiction. A directly modifying role of testosterone in alcohol addiction-related behavior is well established. Sex hormones exert both permanent (organizational) and transient (activational) effects on the human brain. The sensitive period for these effects lasts throughout life. In this article, we present a novel early sex hormone activity model of alcohol addiction. We propose that early exposure to sex hormones triggers structural (organizational) neuroadaptations. These neuroadaptations affect cellular and behavioral responses to adult sex hormones, sensitize the brain's reward system to the reinforcing properties of alcohol and modulate alcohol addictive behavior later in life. This review outlines clinical findings related to the early sex hormone activity model of alcohol addiction (handedness, the second-to-fourth-finger length ratio, and the androgen receptor and aromatase) and includes clinical and preclinical literature regarding the activational effects of sex hormones in alcohol drinking behavior. Furthermore, we discuss the role of the hypothalamic-pituitary-adrenal and -gonadal axes and the opioid system in mediating the relationship between sex hormone activity and alcohol dependence. We conclude that a combination of exposure to sex hormones in utero and during early development contributes to the risk of alcohol addiction later in life. The early sex hormone activity model of alcohol addiction may prove to be a valuable tool in the development of preventive and therapeutic strategies.

Influence of neuronal cell adhesion molecule (NCAM1) variants on suicidal behaviour and correlated traits

Suicide is a public health problem all around the world. Family studies showed a strong heritability but, to date, few genetic data are available. Thus, in the present study we investigated whether a panel of single nucleotide polymorphisms (SNPs) in neuronal cell adhesion molecule 1 (NCAM) 1 was associated with suicidal behaviour as well as specific traits related to suicide. A total of two hundred and fifty-nine individuals with a positive history of suicidal behaviour and 312 healthy subjects were enrolled in the study. Rs2301228, rs1884, rs1245113, rs1369816, rs2196456 and rs584427 in NCAM1 were genotyped. No marker was significantly associated with suicidal behaviour vs. controls or with sub-types of attempted vs. completed, violent vs. non-violent, impulsive vs. non-impulsive suicide. Nonetheless rs1884 and rs2196456 SNPs were both marginally associated with the trait "inhibition of aggressiveness" in suicide attempters. Even though the investigated SNPs in NCAM1 do not seem to be directly associated with suicidal behaviour, our results could suggest that SNP variants in NCAM1 may impact on related traits, particularly by mediating inhibition of aggressiveness. However, independent studies are needed to validate these results.

Association between the estrogen receptor TA polymorphism and Harm avoidance

In the last decade a large number of studies focused on the recognition of gene variants modulating temperamental traits. The gene coding for the estrogen receptor alpha (ESR1) appears to be an interesting candidate and it has been found to be linked to Harm avoidance (HA). The aim of the present study was to investigate whether the ESR1 TA dinucleotide repeat polymorphism is associated with HA temperamental trait in a sample of Caucasian University students. One hundred ninety healthy subjects were genotyped for ESR1 TA dinucleotide repeat polymorphism and were administered the Temperament and Character Inventory (TCI). ESR1 TA repeat lengths were dichotomized into short and long categories. ANOVA was used to examine the influence of ESR1 variants (short/long) on the means of the TCI HA scores. HA was significantly associated with age and gender in our sample, being higher in older and female subjects. In the global sample as well as in men and women separately, individuals carrying the S/S variant showed significantly higher HA scores. Further analysis on the HA subscales revealed that specific differences could exist between men and women. Our results further suggest a possible role of ESR1 variants on HA. Further research is needed to replicate our findings as well as to better explore the neuro-biological mechanisms of the modulation of ESR1 on HA.