Liu H M, Lei H Y, Kao K P
Department of Pathology, National Cheng Kung University, Medical College, Tainan, Taiwan, Republic of China.
Exp Neurol. 1995 Mar;132(1):24-32. doi: 10.1016/0014-4886(95)90055-1.
When a silicone tube is implanted in transected rat sciatic nerve, there is plasma accumulation and formation of a fibrin cable followed by proliferation and migration of neural and nonneural cells from the nerve stumps into the cable. The wound fluid exhibited neurotrophic activity of unknown origin and nature. In this study, we analyzed the NGF level in wound fluid by a sensitive enzyme immunoassay and correlated the NGF level with the cytological localization of NGF, low affinity NGF receptor (p75NGFR), and Trk receptor in the axotomized nerve by immunohistochemistry. We demonstrated a rising NGF level in wound fluid from 490 pg/ml on Day 1 to 950 pg/ml on Day 7; the serum NGF level was 1/20 of that in the wound fluid. The infiltrating leukocytes expressed strong NGF but no p75NGFR. The proliferative fibroblasts and vascular cells exhibited a short period of NGF but no p75NGFR staining. Schwann cells in the distal segment showed a prolonged period of NGF and p75NGFR expression. No Trk receptor was demonstrated on leukocytes or non-neural cells. These findings suggest that locally synthesized NGF is mainly responsible for the neurotrophic activity in the wound chamber fluid. The NGF produced by the nonneural cells may be bound and stored in the p75NGFR in Schwann cells in the distal segment prior to the arrival of the regenerating axons.
当将硅胶管植入切断的大鼠坐骨神经时，会有血浆积聚并形成纤维蛋白索，随后神经和非神经细胞从神经残端增殖并迁移到纤维蛋白索中。伤口液表现出来源和性质不明的神经营养活性。在本研究中，我们通过灵敏的酶免疫测定法分析了伤口液中的神经生长因子（NGF）水平，并通过免疫组织化学将NGF水平与NGF、低亲和力NGF受体（p75NGFR）和Trk受体在轴突切断神经中的细胞定位相关联。我们证明伤口液中NGF水平从第1天的490 pg/ml上升到第7天的950 pg/ml；血清NGF水平是伤口液中NGF水平的1/20。浸润的白细胞表达强NGF但不表达p75NGFR。增殖的成纤维细胞和血管细胞表现出短暂的NGF表达但无p75NGFR染色。远端段的雪旺细胞显示出较长时间的NGF和p75NGFR表达。白细胞或非神经细胞上未检测到Trk受体。这些发现表明，局部合成的NGF主要负责伤口腔液中的神经营养活性。非神经细胞产生的NGF可能在再生轴突到达之前被结合并储存在远端段雪旺细胞的p75NGFR中。
