DNA damage after chronic oxytocin administration in rats: a safety yellow light?

Intrapartum exposure to synthetic oxytocin, maternal BMI, and neurodevelopmental outcomes in children within the ECHO consortium

BACKGROUND

Synthetic oxytocin (sOT) is frequently administered during parturition. Studies have raised concerns that fetal exposure to sOT may be associated with altered brain development and risk of neurodevelopmental disorders. In a large and diverse sample of children with data about intrapartum sOT exposure and subsequent diagnoses of two prevalent neurodevelopmental disorders, i.e., attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), we tested the following hypotheses: (1) Intrapartum sOT exposure is associated with increased odds of child ADHD or ASD; (2) associations differ across sex; (3) associations between intrapartum sOT exposure and ADHD or ASD are accentuated in offspring of mothers with pre-pregnancy obesity.

METHODS

The study sample comprised 12,503 participants from 44 cohort sites included in the Environmental Influences on Child Health Outcomes (ECHO) consortium. Mixed-effects logistic regression analyses were used to estimate the association between intrapartum sOT exposure and offspring ADHD or ASD (in separate models). Maternal obesity (pre-pregnancy BMI ≥ 30 kg/m2) and child sex were evaluated for effect modification.

RESULTS

Intrapartum sOT exposure was present in 48% of participants. sOT exposure was not associated with increased odds of ASD (adjusted odds ratio [aOR] 0.86; 95% confidence interval [CI], 0.71-1.03) or ADHD (aOR 0.89; 95% CI, 0.76-1.04). Associations did not differ by child sex. Among mothers with pre-pregnancy obesity, sOT exposure was associated with lower odds of offspring ADHD (aOR 0.72; 95% CI, 0.55-0.96). No association was found among mothers without obesity (aOR 0.97; 95% CI, 0.80-1.18).

CONCLUSIONS

In a large, diverse sample, we found no evidence of an association between intrapartum exposure to sOT and odds of ADHD or ASD in either male or female offspring. Contrary to our hypothesis, among mothers with pre-pregnancy obesity, sOT exposure was associated with lower odds of child ADHD diagnosis.

Effects of chronic intranasal oxytocin on behavior and cerebral glucose uptake in juvenile titi monkeys

Intranasal oxytocin (IN OXT) has been proposed as a treatment for autism spectrum disorder (ASD); however, little is known about the effects of long-term exposure. This is the first study in a non-human primate species to examine how developmental exposure to chronic IN OXT affects juvenile's interactions with family members, social preference for parents versus strangers, anxiety-like behavior, and cerebral glucose metabolism. Titi monkeys are socially monogamous and biparental; their family bonds share important characteristics with human family bonds. Fourteen males and 15 females were treated intranasally with saline (n = 14) or 0.8 IU/kg OXT (n = 15), daily from 12 to 18 months of age. Compared to SAL-treated animals, OXT-treated animals of both sexes spent significantly more time grooming other family members (F₁ = 8.97, p = 0.006). Overall, OXT-treated subjects were more social (F₁ = 8.35, p = 0.005) during preference tests. OXT-treated females displayed an enhanced preference for their parents (t = 2.265, p = 0.026). OXT-treated males had a blunted preference for their parents and an increase in the time spent near unfamiliar pairs (F1 = 10.89, p = 0.001). During anxiety tests, OXT-treated males refused to complete the task more often than SAL-treated males and had longer latencies (p < 0.0001). Neuroimaging studies revealed that OXT-treated animals had higher glucose uptake across the social salience network as a whole after one month of treatment (F_1,9 = 1.07, p = 0.042). Our results suggest moderate prosocial effects of chronic IN OXT, that did not depend on anxiolytic properties. We also found important sex differences that should be considered in a translational context.

Chronic oxytocin administration as a tool for investigation and treatment: A cross-disciplinary systematic review

Oxytocin (OT) subserves various physiological, behavioral, and cognitive processes. This paired with the ability to administer OT with minimal and inconsistent side effects has spurred research to explore its therapeutic potential. Findings from single-dose studies indicate that OT administration may be beneficial, at least under certain circumstances. The state of the field, however, is less clear regarding effects from chronic OT administration, which more closely resembles long-term treatment. To address this gap, this review synthesizes existing findings on the use of chronic OT administration in animal and human work. In addition to detailing the effects of chronic OT administration across different functional domains, this review highlights factors that have contributed to mixed findings. Based on this review, a basic framework of interrelated regulatory functions sensitive to chronic OT administration is offered. The paper also identifies future research directions across different contexts, populations, and outcomes, specifically calling for more systematic and standardized research on chronic OT administration in humans to supplement and expand what is currently known from preclinical work.