Intranasal oxytocin attenuates the cortisol response to physical stress: a dose-response study.
BACKGROUND
Intranasal oxytocin attenuates cortisol levels during social stress inductions. However, no research to date has documented the dose-response relation between intranasal oxytocin administration and cortisol, and researchers examining intranasal oxytocin have not examined the cortisol response to physical stress. We therefore examined the effects of 24IU and 48IU of intranasal oxytocin on the cortisol response to vigorous exercise.


METHODS
Seventeen males participated in a randomized, placebo-controlled, double-blind, and within-subject experiment. Participants engaged in vigorous exercise for 60min following the administration of placebo or intranasal oxytocin on three occasions. Saliva samples and mood ratings were collected at eight intervals across each session.


RESULTS
Salivary cortisol concentrations changed over time, peaking after 60min of exercise (quadratic: F(1,16)=7.349, p=.015, partial η(2)=.32). The 24IU dose of oxytocin attenuated cortisol levels relative to placebo (F(1,16)=4.496, p=.05, partial η(2)=.22) and the 48IU dose, although the latter fell just short of statistical significance (F(1,16)=3.054, p=.10, partial η(2)=.16). There was no difference in the cortisol response to exercise in participants who were administered 48IU of intranasal oxytocin relative to placebo. Intranasal oxytocin had no effect on mood.


CONCLUSIONS
This is the first study to demonstrate that the effect of intranasal oxytocin on salivary cortisol is dose-dependent, and that intranasal oxytocin attenuates cortisol levels in response to physical stress. Future research using exogenous oxytocin will need to consider the possibility of dose-response relations.
Centre for Research in Human Development, Department of Psychology, Concordia University, Montréal, QC, Canada.
Christopher
C
Cardoso
Mark A
MA
Ellenbogen
Mark Anthony
MA
Orlando
Simon L
SL
Bacon
Ridha
R
Joober
D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D000339:Affect / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D010121:Oxytocin / Q000008:administration & dosage* / Q000494:pharmacology*; D012463:Saliva / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects* / Q000502:physiology*; D013997:Time Factors
D010121:Oxytocin; D006854:Hydrocortisone