Microneedles enhance topical delivery of 15-deoxy-Δ12,14-prostaglandin J2 and reduce nociception in temporomandibular joint of rats
The pain arising from temporomandibular disorders is often treated with opioids and agents that inhibit the immune response and are associated with substantial adverse effects and long-term risks. Thus, the development of new therapies that are safer and more effective is of great interest to patients and clinicians. 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) is naturally produced in the human body and has anti-inflammatory properties. We have previously shown in a rat temporomandibular joint (TMJ) model that injection of 15d-PGJ2 into the rat TMJ can provide antinociceptive relief against a subsequent noxious challenge from formalin injection into the same TMJ. However, intra-TMJ injections are painful. Thus, to make the treatment patient friendly, this study aimed to evaluate whether the antinociceptive property of 15d-PGJ2 cream can be enhanced with microneedles (MNs). We found that topical application of 15d-PGJ2 cream for 15 min directly on the rat TMJ skin did not induce any significant antinociceptive effect. However, if MNs were inserted in the skin for 5 min, removed, and then 15d-PGJ2 cream was applied, a significant reduction in formalin-induced nociceptive behavior was observed. This reduction in nociception was comparable to an intra-TMJ injection of 15d-PGJ2. A concentration-dependent effect of 15d-PGJ2 was observed, with higher concentrations of 15d-PGJ2 in the cream showing a more durable effect up to 8 h. 15d-PGJ2 cream associated with MNs also significantly reduced the release of tumor necrosis factor-α and interleukin-1 beta, which are pro-inflammatory cytokines. Our findings suggest that 15d-PGJ2 cream associated with MNs provides antinociceptive and anti-inflammatory effect, and can offer a potential patient-friendly therapeutic option for pain control related to inflammatory disorders of the TMJ.