炎性痛致大鼠脊髓后角ProBDNF及其受体的表达变化

Inflammatory pain induced expression changes of ProBDNF and its receptors in rat spinal dorsal horn

目的:探讨完全弗氏佐剂(complete Freund’s Adjuvant,CFA)致炎性疼痛后大鼠脊髓后角内ProBDNF及受体P75NTR和Sortilin的表达变化及意义。方法:大鼠随机分为正常组和实验组,实验组大鼠左侧足底皮下注射CFA和生理盐水混合溶剂100μl,建立炎性疼痛模型,实验组包括注射CFA后6 h、1、3、7和14 d组。采用Von Frey纤维测定不同时间点大鼠机械缩足阈值(pawwithdrawal threshold,PWT)的变化;采用免疫组织化学方法检测ProBDNF及P75NTR、Sortilin在脊髓后角的表达变化。结果:足底注射CFA后1 h PWT即下降,并在6 h后达到最低值,3 d后逐渐上调,至14 d仍低于基础值。ProBDNF在正常脊髓后角可见阳性表达;注射CFA后1 d注射侧脊髓后角较对侧其ProBDNF的表达明显上调,上调持续到7 d左右,至14 d逐渐恢复。正常大鼠脊髓后角P75NTR有较弱表达,主要集中在后角I、II层纤维;注射CFA后6 h开始,注射侧脊髓后角内P75NTR的表达明显上调,III-V层的阳性产物也逐渐增加,这种上调持续到7 d左右达高峰,至14 d逐渐下降。Sortilin在正常脊髓后角浅层仅有较弱阳性产物表达,注射CFA后不同时间点脊髓后角Sortilin的表达无明显差异。结论:CFA能诱导大鼠产生为期2周以上的炎性痛病程;脊髓后角ProBDNF和P75NTR的表达上调可能与炎性疼痛中外周痛觉信号的传导和中枢敏化有关。

Objective： To explore expression changes of ProBDNF and its receptors P75NTR and Sortilin in posterior horn of the spinal cord followed by Complete Freund’s Adjuvant（CFA） induced inflammatory pain.Methods： Rats were received plantar subcutaneous injection of CFA and saline mixed solvent 100 μl,establishing inflammatory pain model.Rats were randomly divided into normal group and experimental group.The experimental group included rats with CFA injecyion at 6 h,1 d,3 d,7 d and 14 d.The change of paw withdrawal threshold（PWT） was observed by Von Frey fibers in rats at different time points;the expressions of ProBDNF,P75NTR and Sortilin in spinal dorsal horn were detected using immunohistochemistry.Results： PWT decreased quickly 1 h after CFA injection,and to the lowest value at 6 h.PWT gradually rose at 3 d and was still lower than baseline at 14 d.ProBDNF expression can be seen in the normal spinal dorsal horn.Compared with the contralateral side,ProBDNF was significantly increased in the ispilateral spinal dorsal horn 1 d after CFA injection;the increase continued until 7 d,and gradually restored at 14 d.Normal rat spinal dorsal horn had a weak expression of P75NTR,mainly in the laminae I and II;P75NTR was significantly increased in the spinal dorsal horn of the injected side 6 h after CFA injection,positive products in laminae III-V were also increased.This increase reached its peak at 7 d and gradually decreased at 14 d.Sortilin positive product was weak in the normal superficial spinal dorsal horn.Sortilin expression in the spinal dorsal horn had no significant difference at different time points after CFA injection.Conclusion： CFA can induce inflammatory pain more than 2 weeks duration;ProBDNF and P75NTR upregulation in spinal dorsal horn may be related to peripheral pain signal transmission and central sensitization under inflammatory pain.