Role of CXCR4 in dorsal root ganglia in incisional pain in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of C-X-C chemokine receptor type 4 ( CXCR4) in the dorsal root ganglia ( DRG) in incisional pain in rats. Methods Thirty-two male Sprague-Dawley rats, aged 7-10 weeks, weighing 250-300 g, in which intrathecal catheters were successfully implanted, were divided into 4 groups (n＝8 each) using a random number table method: sham operation group (group S), CXCR4 antagonist AMD3100 plus sham operation group (group A+S), incisional pain group (group I) and CXCR4 antagonist AMD3100 plus incisional pain group (group A+I). Rats were anesthetized with sevoflu-rane. AMD3100 20 μg (in 10 μl of normal saline) was intrathecally injected, and no incision was made 30 min later in group A+S. A 1-cm longitudinal incision was made through skin, fascia and muscle of the plantar aspect of the left hindpaw in group I. AMD3100 20 μg (in 10 μl of normal saline) was intrathecally injected, and 30 min later the model of incisional pain was established in group A+I. The mechanical paw withdrawal threshold ( MWT) and thermal paw withdrawal latency ( TWL) were measured at 24 h before surgery and 2, 4, 8, 16 and 24 h after surgery. The rats were sacrificed after the last measurement of pain threshold and the DRGs of the lumbar segment (L4-6) were removed for detecting the expression of CXCR4, phosphorylated extracellular regulated protein kinase ( p-ERK) and total ERK ( t-ERK) by Western blot. Results Compared with group S, MWT was significantly decreased and TWL was shortened at T1-5in group I and group A+I, and the expression of CXCR4 and p-ERK in DRGs was significantly up-regulated (P＜0. 05), and no significant change was found in the expression of t-ERK in group I, no significant change was found in the expression of CXCR4, p-ERK and t-ERK in group A+I, and no significant change was found in the parameters mentioned above in group A+S (P＞0. 05). Compared with group I, MWT was significantly increased and TWL was prolonged at T1-5, the expression of CXCR4 and p-ERK in DRGs was down-regulated (P＜0. 05), and no significant change was found in the expression of t-ERK in group A+I (P＞0. 05). Conclusion CXCR4 in DRGs is involved in incisional pain, and the mechanism may be re-lated to activating ERK1∕2 signaling pathway in rats.