Background/Purpose: Fibromyalgia is a chronic disease characterized by widespread musculoskeletal pain throughout the body accompanied by fatigue, sleep, and memory issues, but there are no effective drugs in clinical. Oxytocin is synthesized within the paraventricular nucleus and supraoptic nucleus of the hypothalamus, and well known to facilitate the parturition and suckling. In addition to these pharmacological effects, oxytocin has been reported to have antinociceptive effect on neuropathic pain. However, the effect of oxytocin on fibromyalgia has not been reported. In this study, we examined the effect of oxytocin using experimental fibromyalgia model rats.

Methods: SD rats were exposed to repeated cold stress (23℃ for 2 h and -3℃ for 2 h for 5 cycles, -3℃ for 4 h for 1 cycle; for 5 days) in the automatically controlled chamber. Two days after repeated cold stress, rats were intranasally treated with vehicle or oxytocin (25 μL/body), or orally treated with Pregabalin. Mechanical sensitivity was assessed by von Frey filament at 1 and 3 h after treatment. Corticosterone and ACTH in plasma were measured.

Results: Repeated cold stress induced significant tactile allodynia in rats. Pregabalin a drug used for fibromyalgia, significantly improved allodynia at 1 and 3 h after treatment. Intranasal oxytocin significantly attenuated allodynia in a dose-dependent manner. Plasma ACTH and corticosterone were decreased in repeated cold stress rats. Intranasal oxytocin inhibited the decreases in plasma ACTH and corticosterone levels, but pregabalin failed.

Conclusion: This is the first report showing that oxytocin attenuates tactile allodynia in fibromyalgia model. Intranasal oxytocin is expected to be therapeutic option for fibromyalgia.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/oxytocin-attenuates-tactile-allodynia-in-experimental-fibromyalgia-rats/