Role of interleukin-17 in spinal dorsal horns in neuropathic pain in rats and its effect on activation of astrocytes / 中华麻醉学杂志

ABSTRACT

Objective To investigate the role of interleukin-17 (IL-17) in spinal dorsal horns in neuropathic pain (NP) in rats and its effect on activation of astrocytes.Methods In vivo experiment Sixty-four male SPF Sprague-Dawley rats,aged 6-8 weeks,weighing 180-200 g,were randomly divided into 3 groups using a random number tablecontrol group (group C,n =16),sham operation group (group S,n =24) and group NP (n =24).The animals were anesthetized with intraperitoneal pentobarbital sodium,the L5,6 spinal nerves of the left side of the rat were gently separated and exposed,tightly ligated with 5-0 silk suture and transected.In group S,the L5,6 spinal nerves of the left side of the rat were only exposed.In group C,no operation was performed.Mechanical pain threshold was measured at day 1 before operation and days 1,3,5,7,10 and 14 after operation.The expression of IL-17,IL-6,IL-1β and tumor necrosis factor-alpha (TNF-α) mRNA in the spinal dorsal horn was determined using quantitative real-time PCR at day 7 and day 14 after operation.At day 7 after operation,the activation of astrocytes in the spinal dorsal horn was detected.In vitro experiment Primarily cultured astrocytes of neonatal rats were randomly divided into 4 groups using a random number tablecontrol group (group C,n=22),10 ng/ml IL-17 group (I10 group,n=18),50 ng/ml IL-17 group (I50 group,n-18) and 100 ng/ml IL-17 group (I100 group,n=22).In I10,I50 and I100 groups,the astrocytes were incubated with the culture medium containing 10,50 and 100 ng/ml IL-17,respectively.The proliferation of astrocytes was detected by MTT at 24,48 and 72 h of incutation or culture.The expression of IL-6,IL-1β and TNF-α mRNA was determined using quantitative real-time PCR.Results In vivo experiment Compared with group C,the mechanical pain threshold was significantly decreased at 3-14 days after operation,the expression of IL-17,IL-6 and IL-1β mRNA in the spinal dorsal horn was up-regualted at 7 days after operation,and the activation of astrocytes was increased in group NP,and no significant change was detected in the mechanical pain threshold at each time point after operation in group S.In vitro experiment Compared with group C,the proliferation of astrocytes was significantly increased at 48 h of incubation in I10 and I50 groups,the proliferation of astrocytes was significantly increased at 48 and 72 h of incubation,and the expression of IL-6 and IL-1β mRNA was up-regulated in I100 group,and no significant change was found in the proliferation of astrocytes in group S.Conclusion Up-regulated expression of IL-17 in spinal dorsal horns may be involved in the maintenance of NP,and the mechanism is related to promoted activation of astrocytes and induced inflammatory responses in rats.