Effect of intrathecal insulin-like growth factor-1 on chemotherapy-induced neuropathic pain in mice / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of intrathecal insulin-like growth factor-1 (IGF-1) on chemotherapy-induced neuropathic pain (NP) in mice.Methods:Forty clean-grade healthy male C57 mice, aged 7-9 weeks, weighing 22-24 g, were divided into 4 groups ( n=10 each) using a random number table method: control group (group C), chemotherapy-induced NP group (group CIPN), low-dose IGF-1 group (group I1) and high-dose IGF-1 group (group I2). In CIPN, I1 and I2 groups, oxaliplatin 5 mg/kg was intraperitoneally injected for 5 consecutive days to establish chemotherapy-induced NP model.Normal saline 0.2 ml was given in group C. After measurement of the pain threshold at 10 days after establishment of the model, IGF-1 0.5 and 1.0 μg were intrathecally injected in group I1 and group I2, respectively.Normal saline 5 μl was intrathecally injected in C and CINP groups.Mechanical withdrawal threshold (MWT) was measured at 3, 5, 8, 10, 11, 13 and 15 days after establishment of the model.After measurement of the pain threshold at 15 days after establishment of the model, the expression of spinal IGF-1, IGF-1receptor (IGF-1R), interleukin (IL)-17A, IL-1β and tumor necrosis factor (TNF)-α was detected, and IGF-1 positive cells were counted using immunofluorescence. Results:Compared with group C, MWT was significantly decreased, the expression of spinal IGF-1 was down-regulated, the count of IGF-1 positive cells was decreased, and expression of IL-17A, IL-1β and TNF-α was up-regulated at 3-25 days after establishment of the model in CINP, I1 and I2 groups ( P<0.05). Compared with group CIPN, MWT was significantly increased at 15 days after establishment of the model in group I1, and MWT was increased, the expression of spinal IGF-1 was up-regulated, the count of IGF-1 positive cells was increased, and expression of IL-17A, IL-1β and TNF-α was down-regulated at 13 and 15 days after establishment of the model in group I2 ( P<0.05). Compared with group I1, the count of IGF-1 positive cells in spinal dorsal horn was increased in group I2 ( P<0.05). There was no significant difference in the expression of spinal IGF-1R among the 4 groups ( P>0.05). Conclusion:Intrathecal IGF-1 can alleviate chemotherapy-induced NP, and the mechanism may be related to inhibiting the inflammatory responses in spinal cord of mice.