Effects of puerarin on the inflammatory role of burn-related procedural pain mediated by P2X(7) receptors.

BACKGROUND: Burn injury can induce an inflammatory response in the blood and wound of patients. Procedural activities in burn patients are particularly problematic in burn care due to their high intensity and frequency; hence, procedural pain evoked by burn dressing changes is a common severe issue. Previous studies demonstrated that purinergic signalling is one of the major pathways involved in the initiation, progression and down-regulation of the inflammatory response. Adenosine 5'-triphosphate (ATP) contributes to inflammation, and increased extracellular ATP levels amplify inflammation in vivo via the P2X7 receptor. In the present study, the effect of puerarin, an active ingredient extracted from Chinese herbal medicine Ge Gen, on pain relief of burn patients during dressing change and the mechanism related to the regulation of the purinergic signalling pathway were investigated. METHODS: Burn patients were randomly divided into the normal saline group (NS-treated burn patients) and the puerarin-treated group (PUE-treated burn patients), and healthy volunteers were recruited as a control group. The visual Analogue Scale (VAS) scores, heart rate (HR) and respiratory rate (RR) of NS- and PUE-treated burn patients were observed. In addition, interleukin (IL)-1 and IL-4 levels in blood samples, as well as expression of P2X7 receptor messenger RNA (mRNA) and protein in peripheral blood mononuclear cells (PBMCs) were determined. RESULTS: The IL-1 levels in the PUE-treated burn patients at post-dressing changes were significantly decreased in comparison with those in NS-treated burn patients; in contrast, the IL-4 levels in PUE-treated burn patients were increased. The expression levels of P2X7 protein and mRNA in PBMCs of PUE-treated burn patients were significantly decreased in comparison with those in NS-treated burn patients. CONCLUSIONS: The inflammation and associated pain involved in dressing changes of burn patients were relieved by puerarin treatment. The effects were correlated with the decreased expression level of P2X7 receptor mRNA and protein in PBMCs of burn patients.