Oxytocin and vulnerable romantic relationships

Oxytocin as neuro-hormone and neuro-regulator exert neuroprotective properties: A mechanistic graphical review

BACKGROUND

Neurodegeneration is progressive cell loss in specific neuronal populations, often resulting in clinical consequences with significant medical, societal, and economic implications. Because of its antioxidant, anti-inflammatory, and anti-apoptotic properties, oxytocin has been proposed as a potential neuroprotective and neurobehavioral therapeutic agent, including modulating mood disturbances and cognitive enchantment.

METHODS

Literature searches were conducted using the following databases Web of Science, PubMed, Elsevier Science Direct, Google Scholar, the Core Collection, and Cochrane from January 2000 to February 2023 for articles dealing with oxytocin neuroprotective properties in preventing or treating neurodegenerative disorders and diseases with a focus on oxidative stress, inflammation, and apoptosis/cell death.

RESULTS

The neuroprotective effects of oxytocin appears to be mediated by its anti-inflammatory properties, inhibition of neuro inflammation, activation of several antioxidant enzymes, inhibition of oxidative stress and free radical formation, activation of free radical scavengers, prevent of mitochondrial dysfunction, and inhibition of apoptosis.

CONCLUSION

Oxytocin acts as a neuroprotective agent by preventing neuro-apoptosis, neuro-inflammation, and neuronal oxidative stress, and by restoring mitochondrial function.

Effects of oxytocin receptor blockade on dyadic social behavior in monogamous and non-monogamous Eulemur

A prominent body of research spanning disciplines has been focused on the potential underlying role for oxytocin in the social signatures of monogamous mating bonds. Behavioral differences between monogamous and non-monogamous vole species, putatively mediated by oxytocinergic function, constitute a key source of support for this mechanism, but it is unclear to what extent this hormone-behavior linkage extends to the primate order. In a preregistered experiment, we test if oxytocin receptor blockade affects affiliative behavior in mixed-sex pairs of Eulemur, a genus of strepsirrhine primate containing both monogamous and non-monogamous species. Inconsistent with past studies in monogamous voles or monkeys, we do not find confirmatory evidence in Eulemur that monogamous pairs affiliate more than non-monogamous pairs, nor that oxytocin receptor blockade of one pair member selectively corresponds to reduced affiliative or scent-marking behavior in monogamous species. We do, however, find exploratory evidence of a pattern not previously investigated: simultaneously blocking oxytocin receptors in both members of a monogamous pair predicts lower rates of affiliative behavior relative to controls. Our study demonstrates the value of non-traditional animal models in challenging generalizations based on model organisms, and of methodological reform in providing a potential path forward for behavioral oxytocin research.

Association between salivary oxytocin levels and the amygdala and hippocampal volumes

Salivary oxytocin levels have been widely measured and studied in relation to social behavior because of procedural simplicity and noninvasiveness. Although the relationship between oxytocin levels in the blood and the hippocampus and amygdala is now becoming clear with reliable blood oxytocin studies, few studies have examined the relationship between salivary oxytocin and the brain function and structure. This study aimed to investigate whether the salivary oxytocin level is associated with the volume of the amygdala and hippocampus in 178 adults (92 women and 86 men) in their third to seventh decade of life. We performed volumetric analysis of the amygdala and hippocampus using FreeSurfer and measured salivary oxytocin levels using enzyme-linked immunosorbent assay. The results showed contradictory effects of the salivary oxytocin level on the amygdala volume by sex and no significant effect on the hippocampal volume. Specifically, men showed a positive correlation between the salivary oxytocin level and amygdala volume, whereas women showed a negative correlation between the salivary oxytocin level and amygdala volume. The present study's finding of sex differences in the association between salivary oxytocin and brain structure supports previous findings that there are sex differences in the oxytocin system.

Is oxytocin a trust hormone? Salivary oxytocin is associated with caution but not with general trust

Studies on the association between trust and oxytocin, a neuropeptide of the central nervous system, have not reached a consensus, thereby challenging the possibility of a direct association between the two. However, previous studies have not examined how oxytocin is correlated with trust, based on its categorization into different factors in the field of social science. For instance, based on Yamagishi’s trust theory, trust can be categorized into two factors: general trust and caution. General trust refers to beliefs about the trustworthiness of others, whereas caution refers to the belief that caution is needed when dealing with high social uncertainty. In this study, to examine the relationship between these two factors and oxytocin, we analyzed data of 197 adults (men = 98, women = 99; mean age = 41.7 years; standard deviation for age = 10.4 years) and examined the relationships between these two factors of trust and endogenous salivary oxytocin levels. We found that oxytocin was positively correlated with caution rather than with general trust thereby suggesting that oxytocin plays a role in regulating caution rather than general trust among the components of trust. The present study demonstrated that salivary oxytocin level can act as a biomarker that partially predicts one’s trust, especially as reflected by caution.

Exploring women's oxytocin responses to interactions with their pet cats

Background

Extensive research has evaluated the involvement of the neuropeptide oxytocin (OT) in human social behaviors, including parent-infant relationships. Studies have investigated OT’s connection to human attachment to nonhuman animals, with the majority of the literature focusing on domestic dogs (Canis lupis familiaris). Utilizing what is known about OT and its role in maternal-infant and human-dog bonding, we apply these frameworks to the study of human-domestic cat (Felis catus) interactions.

Methods

We investigated changes in salivary OT levels in 30 U.S. women of reproductive age before and after two conditions: reading a book (control) and interacting with their pet cat. Participant and cat behavioral patterns during the cat interaction condition were also quantified to determine if differences in women’s OT concentrations were associated with specific human and cat behaviors.

Results

Our results revealed no changes in women’s OT levels during the cat interaction, relative to the control condition, and pre-cat interaction OT levels. However, differences in women’s OT concentrations were correlated with some human-cat interactions (e.g., positively with petting cat and cat approach initiation, negatively with cat agonistic behavior) but not all observed behaviors (e.g., use of gentle or baby voice) coded during human-cat interactions.

Discussion

This study is the first to explore women’s OT in response to interactions with their pet cat and has identified distinct human and cat behaviors that influence OT release in humans.

Intranasal oxytocin administration but not peripheral oxytocin regulates behaviors of attachment insecurity: A meta-analysis

In light of the roles of oxytocin (OT) in social bonding and interpersonal relationship, studies have examined the roles of OT in human attachment, but by and large previous findings are inconsistent. Here, we conducted - meta-analyses to estimate the associations between peripheral OT level (e.g., blood and salivary OT) and attachment (i.e., attachment dimensions and behaviors of attachment insecurity) and examine the effects of intranasal OT administration on behaviors of attachment insecurity. The analyses indicated that: (1) Peripheral OT level was not significantly associated with attachment dimensions (e.g., attachment anxiety and attachment avoidance) and behaviors of attachment insecurity; (2) intranasal OT administration significantly reduced behaviors of attachment insecurity of neutral contexts, particularly behaviors of attachment avoidance. The findings suggest that intranasal OT administration is an available approach for reducing behaviors of attachment insecurity of interpersonal situations with ambiguous social cues, which implicates suggestions for therapeutic treatments of attachment-related dysfunctions.

I only have eyes for you: Oxytocin administration supports romantic attachment formation through diminished interest in close others and strangers

Animal studies confirm oxytocin's (OT) role in regulating monogamous sexual behavior in pair-bonding rodents; and human studies are beginning to translate how this highly conserved neuropeptide is implicated in romantic attachment formation. A number of studies have shown how OT promotes relationship exclusivity by diminishing interest in strangers and increasing reward response to partners. Less clear is whether these effects are modulated by romantic duration or life history factors, or if OT's social distancing effects generalize beyond strangers to close relationships. We report the results of a double-blind, placebo-controlled crossover study on the effects of a single dose of intranasal OT (24 IU) on forty-four young adults (91% female) in different stages of romantic attachment formation (M duration=21 months). Participants completed a screening survey and two lab visits separated by 4-weeks, including a diagrammatic measure of attachment to parents and peers, attitudes related to sexual conservatism and partner infidelity, ratings scales of closeness to romantic partners, and visual attractiveness ratings of strangers. Individual differences were examined by life history factors, including maternal love withdrawal and parental separation. Results indicated that OT administration decreased attachment to mothers, decreased attachment to subsidiary attachment figures, and decreased attraction to strangers. In all cases, emotional distancing was stronger among participants in newer romantic relationships. OT increased arousal to partner infidelity and increased sexual conservatism among participants with negative life history experiences (parental separation and high love withdrawal), whereas the reverse was true for participants reporting a more positive life history. Findings suggest that OT supports exclusivity through social distancing from strangers and close others within a sensitive period of attachment formation. In addition, findings indicate OT plays a different role in mate retention strategies by life history.

Salivary Oxytocin Is Negatively Associated With Religious Faith in Japanese Non-Abrahamic People

Spirituality and religiosity have a significant impact on one's well-being. Although previous studies have indicated that the neuropeptide hormone oxytocin is associated with spirituality/religiosity, existing findings remain inconsistent. Some studies have reported a positive relationship between oxytocin and spirituality/religiosity, while other studies have reported a negative association. Herein, we examined the association between endogenous oxytocin and spirituality/religiosity in 200 non-Abrahamic Japanese individuals (102 females, mean age ± standard deviation = 41.53 ± 10.46) by measuring the level of salivary oxytocin and spiritual/religious faith. We found that the level of salivary oxytocin was negatively associated with spiritual/religious faith. Individuals with higher levels of salivary oxytocin tend to have more negative spiritual/religious faith compared with those with low oxytocin levels (e.g., “Spirituality/religiosity makes people passive and clinging.”). Moreover, this tendency was only significant in individuals who were not interested in a specific religion. The uniqueness of spirituality/religiosity in Japan could help interpret the current findings.

Mothers' and fathers' joint profiles for testosterone and oxytocin in a small-scale fishing-farming community: Variation based on marital conflict and paternal contributions

INTRODUCTION

Testosterone and oxytocin are psychobiological mechanisms that interrelate with relationship quality between parents and the quantity and quality of parenting behaviors, thereby affecting child outcomes. Their joint production based on family dynamics has rarely been tested, particularly cross-culturally.

METHODS

We explored family function and salivary testosterone and oxytocin in mothers and fathers in a small-scale, fishing-farming society in Republic of the Congo. Fathers ranked one another in three domains of family life pertaining to the local cultural model of fatherhood.

RESULTS

Fathers who were viewed as better providers had relatively lower oxytocin and higher testosterone than men seen as poorer providers, who had lower testosterone and higher oxytocin. Fathers also had higher testosterone and lower oxytocin in marriages with more conflict, while those who had less marital conflict had reduced testosterone and higher oxytocin. In contrast, mothers in conflicted marriages showed the opposite profiles of relatively lower testosterone and higher oxytocin. Mothers had higher oxytocin and lower testosterone if fathers were uninvolved as direct caregivers, while mothers showed an opposing pattern for the two hormones if fathers were seen as involved with direct care.

CONCLUSIONS

These results shed new light on parents' dual oxytocin and testosterone profiles in a small-scale society setting and highlight the flexibility of human parental psychobiology when fathers' roles and functions within families differ across cultures.

Jealousy, Consent, and Compersion Within Monogamous and Consensually Non-Monogamous Romantic Relationships

Evolutionary psychological research has studied romantic jealousy extensively within monogamous relationships, but has largely ignored jealousy among partners who mutually consent to forming extra-pair relationships (i.e., consensual non-monogamy; CNM). We examined monogamous (n = 529) and CNM (n = 159) individuals' reactions to imagining their romantic partner(s)'s extra-pair involvement. For each romantic partner, men and women completed measures of relationship jealousy and reacted to scenarios of their partner's extra-pair emotional and sexual involvement. Scenarios prompted participants to indicate which type of involvement would be more distressing and more enjoyable. They also described whether or not participants had consented to their partner's extradyadic relationship. Monogamous men were more distressed by a partner's extradyadic sexual versus emotional involvement (and a partner's emotional involvement was more enjoyable) whether the scenario was consensual or not. Monogamous women were more distressed by a partner's emotional versus sexual involvement (and a partner's sexual involvement was more enjoyable) for consensual, but not non-consensual, scenarios. There were no gender differences among CNM participants. Monogamous individuals reported greater emotional distress toward a partner's imagined extradyadic involvement, whereas CNM individuals reported thinking about their partner's extra-pair relationships more frequently. Monogamous (vs. CNM) individuals reported greater confidence that their partner would never cheat on them (i.e., enter another relationship without their consent), and CNM participants were more confident that their primary versus secondary partner would never cheat, although this effect was stronger among CNM women. Moreover, CNM participants rated that it was more important that their primary versus secondary partner did not cheat, and reported greater distress imagining that their primary versus secondary partner had cheated. Women in CNM relationships rated it more important that their partner did not cheat sexually than emotionally. Finally, we replicated previous research showing that monogamous individuals mate guard more than CNM individuals, who mate guard their primary versus secondary partner more frequently. Future directions for developing evolutionary and romantic relationship research on CNM are discussed.

Testosterone, cortisol, and status-striving personality features: A review and empirical evaluation of the Dual Hormone hypothesis

Decades of research in behavioral endocrinology has implicated the gonadal hormone testosterone in the regulation of mating effort, often expressed in primates in the form of aggressive and/or status-striving behavior. Based on the idea that neuroendocrine axes influence each other, recent work among humans has proposed that links between testosterone and indices of status-striving are rendered conditional by the effects of glucocorticoids. The Dual Hormone hypothesis is one particular instance of this argument, predicting that cortisol blocks the effects of testosterone on dominance, aggression, and risk-taking in humans. Support for the Dual Hormone hypothesis is wide-ranging, but considerations of theoretical ambiguity, null findings, and low statistical power pose problems for interpreting the published literature. Here, we contribute to the development of the Dual Hormone hypothesis by (1) critically reviewing the extant literature-including p-curve analyses of published findings; and, (2) "opening the file drawer" and examining relationships between testosterone, cortisol, and status-striving personality features in seven previously published studies from our laboratories (total N = 718; median N per feature = 318) that examined unrelated predictions. Results from p-curve suggest that published studies have only 16% power to detect effects, while our own data show no robust interactions between testosterone and cortisol in predicting status-striving personality features. We discuss the implications of these results for the Dual Hormone hypothesis, limitations of our analyses, and the development of future research.

Oxytocin testing and reproductive health: Status and clinical applications

Oxytocin (OT) is a nonapeptide hormone mainly synthesized in the magnocellular neurons of the paraventricular and supraoptic nucleus of the hypothalamus. In the extra-hypothalamic brain areas, OT acts like neurotransmitters and modulators. The physiological functions of OT are multiple. OT participates to the coordination and control of gonadal development and reproduction. OT appears also as an important regulator of social behaviors such as affiliative, parental, and romantic behaviors. Recent evidence suggests other roles for OT such as potent effects on cardiometabolic functions or involvement in stress-related disorders. The growing interest around the clinical role of OT raised the question of the measurement of OT levels and performances of assays.

Urinary oxytocin levels in relation to post-conflict affiliations in wild male chimpanzees (Pan troglodytes verus)

Many animals living in social groups have evolved behaviors to resolve conflicts between group members, behaviors thought crucial for maintaining stable group life. Several hypotheses, based mainly on observational data, aim to explain how post-conflict (PC) affiliations, such as reconciliation and consolation, resolve conflicts by restoring relationships and/or alleviating anxiety. To examine a potential endocrinological mechanism of PC affiliations, we used an experimental-like procedure to investigate whether the oxytocinergic system is activated during naturally observed reconciliations, receiving bystander PC affiliations and aggressions not followed by PC affiliations in wild male chimpanzees. We compared urinary oxytocin (uOT) levels after reconciliations, receiving bystander PC affiliations or aggressions without affiliations with two control conditions: affiliations without previous aggression and after time periods without social interactions. We furthermore tested the 'valuable relationship' hypothesis of reconciliation, as well as the influence of relationship quality between individuals engaged in each of the three behavioral conditions involving aggression on uOT levels. We found that the probability to reconcile a conflict increased with increasing relationship quality between opponents, thus our results support the 'valuable relationship' hypothesis. However, relationship quality did not influence uOT levels, while behavioral condition had a significant effect on uOT levels. uOT levels after reconciliations, receiving bystander PC affiliations and affiliations not related to conflicts were higher than after aggressions alone and time periods without social interactions. Overall, our results indicate that the oxytocinergic system is activated during affiliative interactions, whether occurring as reconciliation, bystander PC affiliation or affiliation alone. We conclude that the oxytocinergic system, in addition to building and maintaining social relationships, also takes part in repairing them.

Revisiting the wandering womb: Oxytocin in endometriosis and bipolar disorder

Hippocrates attributed women's high emotionality - hysteria - to a 'wandering womb'. Although hysteria diagnoses were abandoned along with the notion that displaced wombs cause emotional disturbance, recent research suggests that elevated levels of oxytocin occur in both bipolar disorder and endometriosis, a gynecological condition involving migration of endometrial tissue beyond the uterus. We propose and evaluate the hypothesis that elevated oxytocinergic system activity jointly contributes to bipolar disorder and endometriosis. First, we provide relevant background on endometriosis and bipolar disorder, and then we examine evidence for comorbidity between these conditions. We next: (1) review oxytocin's associations with personality traits, especially extraversion and openness, and how they overlap with bipolar spectrum traits; (2) describe evidence for higher oxytocinergic activity in both endometriosis and bipolar disorder; (3) examine altered hypothalamic-pituitary-gonadal axis functioning in both conditions; (4) describe data showing that medications that treat one condition can improve symptoms of the other; (5) discuss fitness-related impacts of endometriosis and bipolar disorder; and (6) review a pair of conditions, polycystic ovary syndrome and autism, that show evidence of involving reduced oxytocinergic activity, in direct contrast to endometriosis and bipolar disorder. Considered together, the bipolar spectrum and endometriosis appear to involve dysregulated high extremes of normally adaptive pleiotropy in the female oxytocin system, whereby elevated levels of oxytocinergic activity coordinate outgoing sociality with heightened fertility, apparently characterizing, overall, a faster life history. These findings should prompt a re-examination of how mind-body interactions, and the pleiotropic endocrine systems that underlie them, contribute to health and disease.