Elevated Interictal Oxytocin Associated With Affective Pain in Chronic Migraine
Capsaicin application to the volar forearm was used to model central sensitization and neurogenic inflammation.
According to the results of a study published in Headache, the higher interictal levels of oxytocin observed in patients with chronic migraine compared with unaffected individuals may contribute to the affective component of experimental pain.
To evaluate pain and neurogenic inflammation responses during the interictal period, 32 participants with migraine and 26 healthy participants were enrolled. In this study, capsaicin application to the volar forearm was used to model central sensitization and neurogenic inflammation. Pain perceived in the area around the capsaicin application site was assessed in response to nonnoxious and noxious stimuli to assess secondary allodynia and secondary hyperalgesia, respectively. Plasma oxytocin levels were measured in study participants.
Compared with healthy control patients, participants with migraines reported higher capsaicin-induced pain unpleasantness and had larger areas of flare (group effect, P =.019). Subgroup analysis revealed that greater capsaicin-induced pain unpleasantness was significant in participants with chronic migraine, but not those with episodic migraine (P =.007 and P <.2, respectively).
Oxytocin levels were reported to account for 18% of the variance in pain unpleasantness between participants with migraines and healthy control patients. Overall, no significant difference in oxytocin levels was reported between groups. In participants with migraine, higher interictal levels of oxytocin were associated with lower psychological distress (P <.03), but not with migraine symptom parameters.
The researchers concluded that the results suggest that "even between migraine attacks, migraineurs exhibit a generalized enhancement of affective pain, enhanced neurogenic inflammation, and elevated oxytocin levels, with higher oxytocin levels related to reduced affective and interpersonal distress."
You DS, Haney R, Albu S, Meagher MW. Generalized pain sensitization and endogenous oxytocin in individuals with symptoms of migraine: A cross-sectional study [published online November 2, 2017]. Headache. doi: 10.1111/head.13213