Topical application of Ibunex suppresses hyperalgesia and allodynia and inhibits sensory neuron hyperexcitability and upregulation of Nav1.7 and Nav1.8 in rats with intervertebral foramen inflammation

There is lack of evidence that topical application of an anti-inflammatory reagent on the surface of local skin can alleviate intervertebral foramen (IVF) inflammation-induced pain. We investigated effects and neural mechanisms of topical application of an anti-inflammatory cream Ibunex on behavioral pain, dorsal root ganglion (DRG) neuron hyperexcitability, alteration of the sodium channels and the associated pathological changes following IVF inflammation. The results showed that repetitive, topical application of Ibunex significantly reduced the severity and shortened duration of IVF inflammation-induced thermal hyperalgesia and mechanical allodynia, and suppressed DRG neuron hyperexcitability. Western blotting analysis showed that the inflammation-induced significant upregulation of Nav1.7 and Nav1.8 was reduced by Ibunex treatment. Further, pathological manifestations of the inflamed DRG such as the increased vascularization and satellitosis were markedly alleviated 2–3 weeks after treatment. These r...