How Oxytocin Receptor (OXTR) Single Nucleotide Polymorphisms Act on Prosociality: The Mediation Role of Moral Evaluation

Oxytocin, but not vasopressin, decreases willingness to harm others by promoting moral emotions of guilt and shame

Prosocial and moral behaviors have overlapping neural systems and can both be affected in a number of psychiatric disorders, although whether they involve similar neurochemical systems is unclear. In the current registered randomized placebo-controlled trial on 180 adult male and female subjects, we investigated the effects of intranasal administration of oxytocin and vasopressin, which play key roles in influencing social behavior, on moral emotion ratings for situations involving harming others and on judgments of moral dilemmas where others are harmed for a greater good. Oxytocin, but not vasopressin, enhanced feelings of guilt and shame for intentional but not accidental harm and reduced endorsement of intentionally harming others to achieve a greater good. Neither peptide influenced arousal ratings for the scenarios. Effects of oxytocin on guilt and shame were strongest in individuals scoring lower on the personal distress subscale of trait empathy. Overall, findings demonstrate for the first time that oxytocin, but not vasopressin, promotes enhanced feelings of guilt and shame and unwillingness to harm others irrespective of the consequences. This may reflect associations between oxytocin and empathy and vasopressin with aggression and suggests that oxytocin may have greater therapeutic potential for disorders with atypical social and moral behavior.

Moral judgment and hormones: A systematic literature review

This systematic review of the literature aims to evaluate possible associations between moral judgment and hormones. The electronic databases PsycINFO, PubMed, Scielo, Web of Science, Scopus, and LILACS were used. Twenty studies with different methodological designs were reviewed, covering the hormones cortisol, oxytocin, and testosterone, assessing aspects related to polymorphisms in receptor genes, endogenous levels, and exogenous administration. Taken together, the reviewed studies showed a trend towards an association between hormones and moral judgment, with important specificities involving biological, environmental, and individual aspects. Endogenous levels of cortisol, released under stress, showed negative associations with altruistic and utilitarian decisions only in highly emotionally charged dilemmas. Oxytocin receptor gene polymorphisms (rs2268498, rs237889, and rs2254298) and acute administration of this hormone were associated with variability in moral judgment, with sex as an important moderating variable. Testosterone studies have tended to show a positive association with utilitarian moral judgments, particularly in female and in individuals with low prenatal exposure to this hormone. Knowing how hormones influence moral judgment may help expand our understanding of the plurality of human behavior. However, this area of research is new and still little explored, which does not allow for conclusions with a high level of evidence. Subsequent research will benefit from methodological improvements to extend current findings.

The OXTR rs53576 Impacts Moral Permissibility of Attempted but Failed Harms in Populations of Students and Prisoners

Previous research has highlighted the roles of oxytocin in empathy and altruistic behaviors. Based on these findings, recent studies have examined the association between the oxytocin receptor gene (OXTR) and outcome-based moral judgment with sacrificial dilemmas (e.g. runaway trolley case). However, little is known about the relationships between OXTR polymorphisms and intent-based moral judgment of harms (e.g. attempted but failed harm or intentionally committed harm). This study investigated the association between the OXTR rs53576 and intent-based moral judgment in college students (N = 544) and prisoners (N = 540). Results indicated that both students and prisoners with the GG genotype of OXTR rs53576 rated attempted but failed harm as less permissible than those with the AA and AG genotypes. These findings highlight the role of the OXTR gene in intent-based moral judgment.

Functional Polymorphisms in Oxytocin and Dopamine Pathway Genes and the Development of Dispositional Compassion Over Time: The Young Finns Study

Background: We define compassion as an enduring disposition that centers upon empathetic concern for another person's suffering and the motivation to act to alleviate it. The contribution of specific candidate genes to the development of dispositional compassion for others is currently unknown. We examine candidate genes in the oxytocin and dopamine signaling pathways.

Methods: In a 32-year follow-up of the Young Finns Study (N = 2,130, 44.0% men), we examined with multiple indicators latent growth curve modeling the molecular genetic underpinnings of dispositional compassion for others across the life span. We selected five single nucleotide polymorphisms (SNPs) whose functions are known in humans: rs2268498 (OXTR), rs3796863 (CD38) (related to lower oxytocin levels), rs1800497 (ANKK1/DRD2), rs4680 (COMT), and rs1611115 (DBH) (related to higher dopamine levels). Compassion was measured with Cloninger's Temperament and Character Inventory on three repeated observations spanning 15 years (1997–2012). Differences between gender were tested.

Results: We did not find an effect of the five SNPs in oxytocin and dopamine pathway genes on the initial levels of dispositional compassion for others. Individuals who carry one or two copies of the T-allele of DBH rs1611115, however, tend to increase faster in compassion over time than those homozygotes for the C-allele, b = 0.063 (SE = 0.027; p = 0.018). This effect was largely driven by male participants, 0.206 (SE = 0.046; p < 0.001), and was not significant in female participants when analyzed separately.

Conclusions: Men who are known to have, on average, lower compassion than women seem to reduce this difference over time if they carry the T-allele of DBH rs1611115. The direction of the association indicates that dopamine signaling activity rather than overall dopamine levels might drive the development of compassion.

Intranasal oxytocin in the treatment of autism spectrum disorders: A multilevel meta-analysis

Intranasal oxytocin has been shown to promote social functioning and has recently been applied as a treatment for autism spectrum disorders (ASD). The current meta-analysis aims to assess the crucial question of oxytocin's efficacy in the treatment of ASD. We performed a systematic literature search, including randomized, single- or double-blind/open-label and placebo-controlled clinical trials as well as single-arm, non-randomized and uncontrolled studies investigating exogenous oxytocin effect on ASD. A total of 28 studies (N = 726 ASD patients) met our predefined inclusion criteria. We used a multilevel meta-analytic model and found that oxytocin had beneficial effects on social functioning, but did not find strong evidence for symptoms improvement in the non-social domain. Our findings suggest that oxytocin administration can be regarded as an effective treatment for some core aspects of ASD, especially in the domain of social functioning, highlighting the promise of using oxytocin as a new-generation therapeutic to address core social impairments in ASD.

A genetic profile of oxytocin receptor improves moral acceptability of outcome-maximizing harm in male insurance brokers

In recent years, conflicting findings have been reported in the scientific literature about the influence of dopaminergic, serotonergic and oxytocinergic gene variants on moral behavior. Here, we utilized a moral judgment paradigm to test the potential effects on moral choices of three polymorphisms of the Oxytocin receptor (OXTR): rs53576, rs2268498 and rs1042770. We analyzed the influence of each single polymorphism and of genetic profiles obtained by different combinations of their genotypes in a sample of male insurance brokers (n = 129), as compared to control males (n = 109). Insurance brokers resulted significantly more oriented to maximize outcomes than control males, thus they expressed more than controls the utilitarian attitude phenotype. When analyzed individually, none of the selected variants influenced the responses to moral dilemmas. In contrast, a composite genetic profile that potentially increases OXTR activity was associated with higher moral acceptability in brokers. We hypothesize that this genetic profile promotes outcome-maximizing behavior in brokers by focusing their attention on what represents a greater good, that is, saving the highest number of people, even though at the cost of sacrificing one individual. Our data suggest that investigations in a sample that most expresses the phenotype of interest, combined with the analysis of composite genetic profiles rather than individual variants, represent a promising strategy to find out weak genetic influences on complex phenotypes, such as moral behavior.

Gender differences across multiple types of prosocial behavior in adolescence: A meta-analysis of the prosocial tendency measure-revised (PTM-R)

INTRODUCTION

Literature on adolescent prosocial behavior (PB) has grown tremendously since the development of The Prosocial Tendency Measure-Revised (PTM-R), which includes subscales assessing different types of PB. However, findings of gender differences are inconsistent across studies. Thus, we computed meta-analyses to examine gender differences in adolescents' PB. Further, we examined the moderating roles of type of PB, and various sample (i.e., mean age, gender composition, ethnic composition) and study (i.e., reporter type, measurement form, reliability) characteristics in gender differences in PB.

METHODS

Using online databases (e.g., ProQuest), journal article references, and conference programs, we identified a total of 46 records from 32 studies (215 effect sizes, N = 12,024) across the globe that had measured adolescents' (age 10-18; 51% male) PB using the PTM-R or the PTM.

RESULTS

Gender differences in the PB were small to medium in magnitude (ds ranged from 0 to 0.35) for absolute gender differences (i.e., overall magnitude of gender differences regardless of which gender was higher). There were larger gender differences for gender-typed prosocial behaviors (e.g., altruistic, d = 0.35) than gender-neutral behaviors (e.g., anonymous, d = 0.03). The type of PB (i.e., altruistic, compliant, public, emotional, dire, anonymous) and region (i.e., European, U.S., traditional cultures, Asian) and were significant moderators.

CONCLUSIONS

Although males and females generally are more similar than different in their prosociality, it is important to consider the type of PB when examining gender differences.

Variations in the oxytocin receptor gene and prosocial behavior: moderating effects of situational factors

Humans are the most prosocial primate species and they often exhibit high levels of prosocial behavior toward genetically unrelated individuals. Traditional evolutionary theories are not sufficient to explain the individual differences and mechanisms related to prosociality. In this study, we focused on the gene-situation interaction in prosocial behaviors, and the patterns of genotype variance related to cooperation and comforting in different situations. We explored the interaction between the oxytocin receptor (OXTR) gene and situations, and the genotype variance under low and high prosociality situations between outgroup and ingroup recipients in a sample of 422 Chinese males. Prosociality was tested by measuring the prosocial tendencies, and prosocial behaviors were tested in cooperation and comforting tasks. OXTR single nucleotide polymorphisms (SNPs) were genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis. The results suggested that the relationship between OXTR SNPs (specifically rs13316193, rs1042778 and rs237887) and prosocial behavior varied across different situations, and that the associations were moderated by the recipient's identity and the prosocial cost. Our findings indicate the action of a moderating mechanism between the OXTR gene and prosocial behaviors according to situational factors.

Microsatellite Polymorphisms Adjacent to the Oxytocin Receptor Gene in Domestic Cats: Association with Personality?

A growing number of studies have explored the oxytocin system in humans and non-human animals, and some have found important genetic polymorphisms in the oxytocin receptor gene (OXTR) associated with the bonding system, social behaviors, and personality in several species. Although single nucleotide polymorphisms in OXTR have been well-examined in various species, microsatellites (or short tandem repeats) adjacent to OXTR have rarely been studied, despite some suggestions that microsatellite polymorphisms near genes might play a role in genetic transcription and translation. In this study, we surveyed microsatellites in the upstream, intron, and downstream regions of OXTR in domestic cats (Felis catus). We succeeded in amplifying 5 out of 10 regions, and recognized these five regions as polymorphic. We compared allele frequencies in these five regions between mongrel cats in Japan (n = 100) and cats of 10 pure breeds (n = 40). There were significant differences in allele frequencies between the two populations in all microsatellite regions. Additionally, the owners of mongrel cats answered a comprehensive personality questionnaire, and factor analysis extracted four factors (Openness, Friendliness, Roughness, and Neuroticism). We examined the association between the microsatellite genotypes, age, sex, neutering status, and personality scores. Compared to their counterparts, younger cats tended to score higher on Openness, male cats scored higher on Friendliness, and female and neutered cats scored higher on Roughness. When we divided the sample into three groups depending on the length of alleles, we found a marginally significant association between Friendliness and MS3. Additionally, we found a sex-mediated effect of genotypes in MS4 on Friendliness, resulting in different effects on females and males. Our findings that mongrel cats had longer alleles in MS3 and MS4 than purebred cats, and that those cats tended to score higher on Friendliness, supported the previous findings. However, future studies such as comparison between purebred cats with apparently different origin or personality are required to determine the association of genetic variants in the OXTR with personality.

Genetically-Driven Enhancement of Dopaminergic Transmission Affects Moral Acceptability in Females but Not in Males: A Pilot Study

Moral behavior has been a key topic of debate for philosophy and psychology for a long time. In recent years, thanks to the development of novel methodologies in cognitive sciences, the question of how we make moral choices has expanded to the study of neurobiological correlates that subtend the mental processes involved in moral behavior. For instance, in vivo brain imaging studies have shown that distinct patterns of brain neural activity, associated with emotional response and cognitive processes, are involved in moral judgment. Moreover, while it is well-known that responses to the same moral dilemmas differ across individuals, to what extent this variability may be rooted in genetics still remains to be understood. As dopamine is a key modulator of neural processes underlying executive functions, we questioned whether genetic polymorphisms associated with decision-making and dopaminergic neurotransmission modulation would contribute to the observed variability in moral judgment. To this aim, we genotyped five genetic variants of the dopaminergic pathway [rs1800955 in the dopamine receptor D4 (DRD4) gene, DRD4 48 bp variable number of tandem repeat (VNTR), solute carrier family 6 member 3 (SLC6A3) 40 bp VNTR, rs4680 in the catechol-O-methyl transferase (COMT) gene, and rs1800497 in the ankyrin repeat and kinase domain containing 1 (ANKK1) gene] in 200 subjects, who were requested to answer 56 moral dilemmas. As these variants are all located in genes belonging to the dopaminergic pathway, they were combined in multilocus genetic profiles for the association analysis. While no individual variant showed any significant effects on moral dilemma responses, the multilocus genetic profile analysis revealed a significant gender-specific influence on human moral acceptability. Specifically, those genotype combinations that improve dopaminergic signaling selectively increased moral acceptability in females, by making their responses to moral dilemmas more similar to those provided by males. As females usually give more emotionally-based answers and engage the "emotional brain" more than males, our results, though preliminary and therefore in need of replication in independent samples, suggest that this increase in dopamine availability enhances the cognitive and reduces the emotional components of moral decision-making in females, thus favoring a more rationally-driven decision process.