Oxytocin may help modulate pain experience

Intranasal oxytocin facilitates pain anticipation and modulates pain processing, a new study has found.

Researchers randomly assigned 46 males to receive either a single intranasal dose of oxytocin 24 IU (n=23; mean age, 22.39±5.74 years) or a placebo nasal spray with the same inactive components (n=23; mean age, 24.87±3.77 years).

Participants then underwent 48 trials of conditioning, wherein they were exposed to three different abstract visual cues coincident with a heat pain stimulus (50^oC; 12 trials), a nonpainful warm stimulus (43^oC; 12 trials) or no change in temperature (16 trials).

In the subsequent experimental trials, participants were then asked to rate their expectancy of receiving a nonpainful stimulus, a painful heat stimulus or no temperature change after being shown a visual cue. Visual analogue scale (VAS) pain ratings were also recorded. All tests were performed under functional magnetic resonance imaging.

Participants who received intranasal oxytocin had more accurate pain expectations and provided significantly more correct responses for pain anticipation than their placebo counterparts (p<0.05). Moreover, expectations were more accurate in no stimulus and pain stimulus conditions than in the warm condition, indicating better overall learning for those who were administered oxytocin.

Moreover, oxytocin appeared to modulate the response in the ventral striatum after exposure to painful vs warm unconditioned stimuli, as well as reduce activity in the anterior insula after repeated pain exposure. No between-group differences were reported in terms of pain and warm sensation threshold.