Role of P2X3 receptors in dorsal root ganglion in development of incisional pain in rats

Abstract

Objective To evaluate the role of P2X3 receptors in dorsal root ganglion in development of incisional pain in rats.Methods Twenty-four healthy male SD rats weighing 200-220 g were randomly divided into 3 groups(n = 8 each): control group(group C),incisional pain(group IP)and P2X3 receptor antagonist + IP group(group A).In group IP and A,a 1 cm longitudinal incision was made in the plantar surface of left hindpaw according to the method described by Brennan et al.in isoflurane-anesthetized rats.P2X3 receptor antagonist TNP-ATP 200 nmol was injected into the plantar surface of left hindpaw 30 min after plantar incision was made in group A,while equal volume of normal saline was given instead of TNP-ATP in group C and IP.The behavior of the hindpaw of the rats were assessed using cumulative pain score within 1 h after injection.The animals were sacri ficed 2 h after injection and the dorsal root ganglion was removed for determination of P2X3 receptor expression and intracellular Ca2+ concentrations.Results The cumulative pain scores,P2X3 receptor expression and Ca2 + concentrations were significantly higher in group IP and A than in group C(P ＜ 0.05).The cumulative pain scores,P2X3 receptor expression and Ca2+ concentrations were significantly lower in group A than in group IP(P ＜0.05).Conclusion P2X3 receptors in dorsal root ganglion is involved in the development of incisional pain through increasing intracellular Ca2+ concentrations in rats. Key words: Receptors,purinergic P2; Ganglia,spinal; Pain