Systemic administration of dorsomorphin relieves inflammatory nociception in the mouse formalin test.

Inflammatory pain is the most important clinical symptom of inflammatory diseases. Despite intensive research into inflammatory pain mechanisms, the majority of analgesics available are based on mechanistic classes of compounds that have been known for many years, as a result, inflammatory pain control remains a challenge for drug design in the context of clinically unmet needs in terms of safety and efficacy. A growing literature supports that pro-inflammatory cytokine signaling plays a crucial role in the development of inflammatory pain. Modulation of the pro-inflammatory cytokine may hold the key to improved pain management. Previous studies have reported that dorsomorphin played key roles in inflammation. But the role of dorsomorphin in the formalin-induced inflammatory nociception in mice has never been reported. Here, we report a new function of dorsomorphin which can inhibit formalin-induced inflammatory nociception in mice. The antinociceptive effect of dorsomorphin mainly depended on inhibiting the p38 MAPK/c-fos signaling and regulating inflammatory mediators.