Variation in oxytocin receptor gene (OXTR) polymorphisms is associated with emotional and behavioral reactions to betrayal

OXTR polymorphisms associated with severity and treatment responses of schizophrenia

The mechanisms generating specific symptoms of schizophrenia remain unclear and genetic research makes it possible to explore these issues at a fundamental level. Taking into account the associations between the oxytocin system and social functions, which are apparently impaired in schizophrenia patients, we hypothesized that the oxytocin receptor gene (OXTR) might be associated with schizophrenia symptoms in both severity and responses to antipsychotics and did this exploratory positional study. A total of 2363 patients with schizophrenia (1181 males and 1182 females) included in our study were randomly allocated to seven antipsychotic treatment groups and received antipsychotic monotherapy for 6 weeks. Their blood DNA was genotyped for OXTR polymorphisms. Their symptom severity was assessed by Positive and Negative Syndrome Scale (PANSS), and the scores were transformed into seven factors (positive, disorganized, negative symptoms apathy/avolition, negative symptoms deficit of expression, hostility, anxiety and depression). Percentage changes in PANSS scores from baseline to week 6 were calculated to quantify antipsychotic responses. We found that OXTR polymorphisms were nominally associated with the severity of overall symptoms (rs237899, β = 1.669, p = 0.019), hostility symptoms (rs237899, β = 0.427, p = 0.044) and anxiety symptoms (rs13316193, β = -0.197, p = 0.038). As for treatment responses, OXTR polymorphisms were nominally associated with the improvement in negative symptoms apathy/avolition (rs2268490, β = 2.235, p = 0.0499). No association between severity or response to treatment and OXTR polymorphisms was found with statistical correction for multiplicity. Overall, our results highlighted the possibility of nominally significant associations of the OXTR gene with the severity and improvement in schizophrenia symptoms. Given the exploratory nature of this study, these associations are indicative of the role of the OXTR gene in the pathology of schizophrenia and may contribute to further elucidate the mechanism of specific symptoms of schizophrenia and to exploit antipsychotics more effective to specific symptoms.

The Pan social brain: An evolutionary history of neurochemical receptor genes and their potential impact on sociocognitive differences

Humans have unique cognitive capacities that, compared with apes, are not only simply expressed as a higher level of general intelligence, but also as a quantitative difference in sociocognitive skills. Humans' closest living relatives, bonobos (Pan paniscus), and chimpanzees (Pan troglodytes), show key between-species differences in social cognition despite their close phylogenetic relatedness, with bonobos arguably showing greater similarities to humans. To better understand the evolution of these traits, we investigate the neurochemical mechanisms underlying sociocognitive skills by focusing on variation in genes encoding proteins with well-documented roles in mammalian social cognition: the receptors for vasopressin (AVPR1A), oxytocin (OXTR), serotonin (HTR1A), and dopamine (DRD2). Although these genes have been well studied in humans, little is known about variation in these genes that may underlie differences in social behavior and cognition in apes. We comparatively analyzed sequence data for 33 bonobos and 57 chimpanzees, together with orthologous sequence data for other apes. In all four genes, we describe genetic variants that alter the amino acid sequence of the respective receptors, raising the possibility that ligand binding or signal transduction may be impacted. Overall, bonobos show 57% more fixed substitutions than chimpanzees compared with the ancestral Pan lineage. Chimpanzees, show 31% more polymorphic coding variation, in line with their larger historical effective population size estimates and current wider distribution. An extensive literature review comparing allelic changes in Pan with known human behavioral variants revealed evidence of homologous evolution in bonobos and humans (OXTR rs4686301(T) and rs237897(A)), while humans and chimpanzees shared OXTR rs2228485(A), DRD2 rs6277(A), and DRD2 rs11214613(A) to the exclusion of bonobos. Our results offer the first in-depth comparison of neurochemical receptor gene variation in Pan and put forward new variants for future behavior-genotype association studies in apes, which can increase our understanding of the evolution of social cognition in modern humans.

The promiscuity of the oxytocin-vasopressin systems and their involvement in autism spectrum disorder

Oxytocin and vasopressin systems have been studied separately in autism spectrum disorder (ASD). Here, we provide evidence from an evolutionary and neuroscience perspective about the shared mechanisms and the common roles in regulating social behaviors. We first discuss findings on the evolutionary history of oxytocin and vasopressin ligands and receptors that highlight their common origin and clarify the evolutionary background of the crosstalk between them. Second, we conducted a comprehensive review of the increasing evidence for the role of both neuropeptides in regulating social behaviors. Third, we reviewed the growing evidence on the associations between the oxytocin/vasopressin systems and ASD, which includes oxytocin and vasopressin dysfunction in animal models of autism and in human patients, and the impact of treatments targeting the oxytocin or the vasopressin systems in children and in adults. Here, we highlight the potential of targeting the oxytocin/vasopressin systems to improve social deficits observed in ASD and the need for further investigations on how to transfer these research innovations into clinical applications.

Associations between Oxytocin Receptor (OXTR) Genotype and Elementary School Children's Likability, Dis-likability and Friendship among Classroom Peers: A Longitudinal Study

The single nucleotide polymorphism rs53576 of the oxytocin receptor (OXTR) gene is involved in forming and maintaining relationships in various social contexts. However, this has not been studied in the childhood peer context. The present study followed 359 children (51.6% girls) from age 9 to 12 to explore associations between OXTR rs53576 genotype (i.e., AA, AG or GG genotype) and three indicators of children’s relationships with peers: likability and dis-likability among, and friendship with, classroom peers. Our results showed that OXTR rs53576 was associated with likability among boys, but not with dis-likability and friendship or among girls. Boys with an A and a G allele (i.e., AG genotype) became increasingly more liked by their peers across the four-year studied period than those with two A alleles or two G alleles (i.e., AA and GG genotype). This study indicates that OXTR rs53576 genotype might influence children’s peer relationships, particularly their likeability among peers. Associations between OXTR rs53576 and peer relationships may differ depending on children’s sex and the specific type of peer-relationship under scrutiny.

Conduct problems in youth and the RDoC approach: A developmental, evolutionary-based view

Problems related to aggression in young people are traditionally subsumed under the header of conduct problems, which include conduct disorder and oppositional defiant disorder. Such problems in children and adolescents are an important societal and mental health problem. In this paper we present an evolutionarily informed developmental psychopathology view of conduct problems inspired by the NIMH Research Domain Criteria (RDoC) initiative. We assume that while there are many pathways to conduct problems, chronic or temporary impairments in the domain of social cognition or mentalizing are a common denominator. Specifically, we conceptualize conduct problems as reflecting temporary or chronic difficulties with mentalizing, that is, the capacity to understand the self and others in terms of intentional mental states, leading to a failure to inhibit interpersonal violence through a process of perspective-taking and empathy. These difficulties, in turn, stem from impairments in making use of a normally evolutionarily protected social learning system that functions to facilitate intergenerational knowledge transmission and protect social collaborative processes from impulsive and aggressive action. Temperamental, biological, and social risk factors in different combinations may all contribute to this outcome. This adaptation then interacts with impairments in other domains of functioning, such as in negative and positive valence systems and cognitive systems. This view highlights the importance of a complex interplay among biological, psychological, and environmental factors in understanding the origins of conduct problems. We outline the implications of these views for future research and intervention.

Polymorphisms of the oxytocin receptor gene and overeating: the intermediary role of endophenotypic risk factors

Background/Objectives:

Oxytocin (OXT) is an evolutionarily ancient neuropeptide with strong links to affiliative and prosocial behaviors, and the management of stress. Increases in OXT also tend to decrease food intake, especially of sweet carbohydrates. The social correlates of low OXT levels mesh with the social deficits and stress proneness identified in interpersonal models of overeating, as well as the increased appetite for highly palatable foods typically seen in chronic overeaters. The objectives of this study were to investigate links between polymorphisms of the oxytocin receptor (OXTR) gene and overeating, and to examine OXTR links with relevant endophenotypes of overeating related to reward and stress sensitivity, and to food preferences.

Subject/Methods:

The sample comprised 460 adults between the ages of 25 and 50 years recruited from the community, and representing a broad range of body weights. Overeating, reward and punishment sensitivity, and food preferences, were quantified as composite variables using well-validated questionnaires. In addition, seven single-nucleotide polymorphisms (rs237878, rs237885, rs2268493, rs2268494, rs2254298, rs53576, rs2268498) of the OXTR gene were genotyped.

Results:

Analyses identified a four-marker haplotype that was significantly related to food preferences. Individual genotype analyses also found that at least one of the markers was related to each of the phenotypic variables. In addition, an empirically derived structural equation model linking genetic and phenotype variables produced a good fit to the data.

Conclusions:

The results of this preliminary study have demonstrated that OXTR variation is associated with overeating, and with endophenotypic traits such as sweet and fatty food preferences, and reward and punishment sensitivity. In general, the genetic findings also favor the view that overeating may be associated with relatively low basal OXT levels.

Genetic modulation of oxytocin sensitivity: a pharmacogenetic approach

Intranasal administration of the neuropeptide oxytocin has been shown to influence a range of complex social cognitions and social behaviors, and it holds therapeutic potential for the treatment of mental disorders characterized by social functioning deficits such as autism, social phobia and borderline personality disorder. However, considerable variability exists in individual responses to oxytocin administration. Here, we undertook a study to investigate the role of genetic variation in sensitivity to exogenous oxytocin using a socioemotional task. In a randomized, double-blind, placebo-controlled experiment with a repeated-measures (crossover) design, we assessed the performance of 203 men on an emotion recognition task under oxytocin and placebo. We took a haplotype-based approach to investigate the association between oxytocin receptor gene variation and oxytocin sensitivity. We identified a six-marker haplotype block spanning the promoter region and intron 3 that was significantly associated with our measure of oxytocin sensitivity. Specifically, the TTCGGG haplotype comprising single-nucleotide polymorphisms rs237917-rs2268498-rs4564970-rs237897-rs2268495-rs53576 is associated with increased emotion recognition performance under oxytocin versus placebo, and the CCGAGA haplotype with the opposite pattern. These results on the genetic modulation of sensitivity to oxytocin document a significant source of individual differences with implications for personalized treatment approaches using oxytocin administration.

The association between 2D:4D ratio and cognitive empathy is contingent on a common polymorphism in the oxytocin receptor gene (OXTR rs53576)

Both testosterone and oxytocin influence an individual's accuracy in inferring another's feelings and emotions. Fetal testosterone, and the second-to-forth digit ratio (2D:4D) as its proxy, plays a role in social cognitive development, often by attenuating socio-affective skill. Conversely, oxytocin generally facilitates socio-affiliative and empathic cognition and behavior. A common polymorphism in the oxytocin receptor gene, OXTR rs53576, has been repeatedly linked with psychosocial competence, including empathy, with individuals homozygous for the G allele typically characterized by enhanced socio-cognitive skills compared to A allele carriers. We examined the role of oxytocin and testosterone in collectively contributing to individual differences in cognitive empathy as measured by Baron-Cohen's "Reading the Mind in the Eyes" task (RMET). Findings are based on a large cohort of male and female students (N=1463) of Han Chinese ethnicity. In line with existing literature, women outperformed men in the RMET. Men showed significantly lower 2D:4D ratio compared to women, indicating higher exposure to testosterone during the prenatal period. Interestingly, variation in the OXTR gene was found to interact with 2D:4D to predict men's (but not women's) RMET performance. Among men with GG allelic variation, those with low fetal testosterone performed better on the RMET, compared to men with GG and high fetal testosterone, suggesting greater identification of another's emotional state. Taken together, our data lend unique support to the mutual influence of the oxytocin and testosterone systems in shaping core aspect of human social cognition early in development, further suggesting that this effect is gender-specific.

Signatures of positive selection in the cis-regulatory sequences of the human oxytocin receptor (OXTR) and arginine vasopressin receptor 1a (AVPR1A) genes

BACKGROUND

The evolutionary highly conserved neurohypophyseal hormones oxytocin and arginine vasopressin play key roles in regulating social cognition and behaviours. The effects of these two peptides are meditated by their specific receptors, which are encoded by the oxytocin receptor (OXTR) and arginine vasopressin receptor 1a genes (AVPR1A), respectively. In several species, polymorphisms in these genes have been linked to various behavioural traits. Little, however, is known about whether positive selection acts on sequence variants in genes influencing variation in human behaviours.

RESULTS

We identified, in both neuroreceptor genes, signatures of balancing selection in the cis-regulative acting sequences such as transcription factor binding and enhancer sequences, as well as in a transcriptional repressor sequence motif. Additionally, in the intron 3 of the OXTR gene, the SNP rs59190448 appears to be under positive directional selection. For rs59190448, only one phenotypical association is known so far, but it is in high LD' (>0.8) with loci of known association; i.e., variants associated with key pro-social behaviours and mental disorders in humans.

CONCLUSIONS

Only for one SNP on the OXTR gene (rs59190448) was a sign of positive directional selection detected with all three methods of selection detection. For rs59190448, however, only one phenotypical association is known, but rs59190448 is in high LD' (>0.8), with variants associated with important pro-social behaviours and mental disorders in humans. We also detected various signatures of balancing selection on both neuroreceptor genes.

An attempt to identify single nucleotide polymorphisms contributing to possible relationships between personality traits and oxytocin-related genes

BACKGROUND

The neuropeptides oxytocin and vasopressin play a central role in social behavior. Trials with intranasal oxytocin have been conducted and many indicate that the hormone facilitates affiliative behavior and trust. Intranasal oxytocin administration is suggested as a treatment option for psychiatric illnesses with altered sociability as a core symptom and the effects may be due to differences in variants of oxytocin- and vasopressin-related genes. The purpose of the present study was to investigate the endogenous oxytocin system by exploring the relationship between variants in the oxytocin gene factors and personality traits closely related to trust, anxiety and social behavior.

METHODS

72 single nucleotide polymorphisms (SNPs) in the genes coding for oxytocin (OXT), vasopressin (AVP), the oxytocin receptor (OXTR) and CD38 (CD38), including polymorphisms reported earlier to be related to social phenotypes and novel SNPs, were investigated in 196 healthy subjects. Association analysis between these variants and 3 personality traits (agreeableness, neuroticism and extraversion) measured by the Neuroticism-Extraversion-Openness Five-Factor Inventory was performed.

RESULTS

We found 7 nominally significant associations for personality traits: agreeableness [rs857240 (AVP, p = 0.0075), rs2270463 (OXTR, p = 0.047)], neuroticism [rs3756242 (CD38, p = 0.024), rs13104011 (CD38, p = 0.024), rs6816486 (CD38, p = 0.024), rs7655635 (CD38, p = 0.034)] and extraversion [rs237878 (OXTR, p = 0.019)]. None of these associations remained significant after the Bonferroni correction (p threshold = 2.31 × 10(-4)).

CONCLUSION

Our results do not contradict the hypothesis of associations between personality traits and oxytocin-related gene variants; however, there are no statistically significant associations after correcting for multiple testing, warranting replication in larger samples.

Associations between oxytocin receptor genotypes and social cognitive performance in individuals with schizophrenia

Individuals with schizophrenia often show substantial deficits in social cognitive abilities, which are strongly associated with social functioning. To advance our understanding of the genetic variation that is associated with social cognitive deficits in schizophrenia, we genotyped 74 schizophrenia outpatients who completed social cognitive performance measures assessing mentalizing, social perception, and emotional intelligence, as well as clinical symptoms. We assessed seven single nucleotide polymorphisms (SNPs) of the oxytocin receptor (OXTR) previously found to show replicable associations with socio-emotional processes. For one of the seven SNPs, rs2268493, the 'T' allele was significantly associated with poorer performance on a composite social cognition index, as well as specific tests of mentalizing and social perception. None of the SNPs were associated with clinical symptoms. Though the sample size is small, these findings provide initial support for the involvement of genetic variants of the OXTR in social cognitive impairments in schizophrenia.

Social cognition, face processing, and oxytocin receptor single nucleotide polymorphisms in typically developing children

Recent research has provided evidence of a link between behavioral measures of social cognition (SC) and neural and genetic correlates. Differences in face processing and variations in the oxytocin receptor (OXTR) gene have been associated with SC deficits and autism spectrum disorder (ASD) traits. Much work has examined the qualitative differences between those with ASD and typically developing (TD) individuals, but very little has been done to quantify the natural variation in ASD-like traits in the typical population. The present study examines this variation in TD children using a multidimensional perspective involving behavior assessment, neural electroencephalogram (EEG) testing, and OXTR genotyping. Children completed a series of neurocognitive assessments, provided saliva samples for sequencing, and completed a face processing task while connected to an EEG. No clear pattern emerged for EEG covariates or genotypes for individual OXTR single nucleotide polymorphisms (SNPs). However, SNPs rs2254298 and rs53576 consistently interacted such that the AG/GG allele combination of these SNPs was associated with poorer performance on neurocognitive measures. These results suggest that neither SNP in isolation is risk-conferring, but rather that the combination of rs2254298(A/G) and rs53576(G/G) confers a deleterious effect on SC across several neurocognitive measures.

Common polymorphism in the oxytocin receptor gene (OXTR) is associated with human social recognition skills

The neuropeptides oxytocin and vasopressin are evolutionarily conserved regulators of social perception and behavior. Evidence is building that they are critically involved in the development of social recognition skills within rodent species, primates, and humans. We investigated whether common polymorphisms in the genes encoding the oxytocin and vasopressin 1a receptors influence social memory for faces. Our sample comprised 198 families, from the United Kingdom and Finland, in whom a single child had been diagnosed with high-functioning autism. Previous research has shown that impaired social perception, characteristic of autism, extends to the first-degree relatives of autistic individuals, implying heritable risk. Assessments of face recognition memory, discrimination of facial emotions, and direction of gaze detection were standardized for age (7-60 y) and sex. A common SNP in the oxytocin receptor (rs237887) was strongly associated with recognition memory in combined probands, parents, and siblings after correction for multiple comparisons. Homozygotes for the ancestral A allele had impairments in the range -0.6 to -1.15 SD scores, irrespective of their diagnostic status. Our findings imply that a critical role for the oxytocin system in social recognition has been conserved across perceptual boundaries through evolution, from olfaction in rodents to visual memory in humans.

Navigating the complex path between the oxytocin receptor gene (OXTR) and cooperation: an endophenotype approach

Although cooperation represents a core facet of human social behavior there exists considerable variability across people in terms of the tendency to cooperate. One factor that may contribute to individual differences in cooperation is a key gene within the oxytocin (OT) system, the OT reception gene (OXTR). In this article, we aim to bridge the gap between the OXTR gene and cooperation by using an endophenotype approach. We present evidence that the association between the OXTR gene and cooperation may in part be due to how the OXTR gene affects brain systems involved in emotion recognition, empathy/theory of mind, social communication and social reward seeking. There is evidence that the OXTR gene is associated with the functional anatomy of the amygdala, visual cortex (VC), anterior cingulate and superior temporal gyrus (STG). However, it is currently unknown how the OXTR gene may be linked to the functional anatomy of other relevant brain regions that include the fusiform gyrus (FG), superior temporal sulcus (STS), ventromedial prefrontal cortex (VMPFC), temporoparietal junction (TPJ) and nucleus accumbens (NAcc). We conclude by highlighting potential future research directions that may elucidate the path between OXTR and complex behaviors such as cooperation.

A paradoxical association of an oxytocin receptor gene polymorphism: early-life adversity and vulnerability to depression

Several prosocial behaviors may be influenced by the hormone oxytocin. In line with this perspective, the oxytocin receptor (OXTR) gene single nucleotide polymorphism (SNP), rs53576, has been associated with a broad range of social behaviors. In this regard, the G allele of the OXTR SNP has been accompanied by beneficial attributes such as increased empathy, optimism, and trust. In the current study among university students (N = 288), it was shown that early-life maltreatment was associated with depressive symptoms, and that the OXTR genotype moderated this relationship, such that under high levels of childhood maltreatment, only individuals with GG/GA genotype demonstrated increased depressive symptomatology compared to those with the AA genotype. In addition, the role of distrust in mediating the relation between childhood maltreatment and depression seemed to be more important among G allele carriers compared to individuals with the AA genotype. Thus, a breach in trust (i.e., in the case of early-life abuse or neglect) may have a more deleterious effect among G carriers, who have been characterized as more prosocial and attuned to social cues. The data suggested that G carriers of the OXTR might favor social sensitivity and thus might have been more vulnerable to the effects of early-life adversity.