脊髓源性感觉神经元诱向因子初探

A PRELIMINARY STUDY ON NEURITE-OUTGROWTH PROMOTING SUBSTANCE FROM SPINAL CORD OF CAT

切除５只成年雄猫一侧Ｌ１～Ｌ５和Ｌ７～Ｓ２背根，保留Ｌ６背根为备用根。术后１１ｄ用两侧背角提取液大于５０ｋ组份进行实验。发现，手术组电泳迁移率为０．１的蛋白带内的蛋白含量明显增多，且其对鸡胚背根节神经突起生长的促进作用也显著增强；而手术组电泳迁移率为０．５的蛋白带内的蛋白含量却明显减少，但其促进神经突起生长的作用与对照组者比较无显著性差异。此结果表明，猫脊髓背角中分子量大于５０ｋＤ、电泳迁移率为０．１的蛋白质具有神经营养活性，去传入使其活性增强，这可能是导致部分去传入猫后角在体外的促神经突起生长活性增强与在体备用根纤维侧支出芽的直接原因之一。电泳迁移率为０．５的蛋白质与神经突起的生长似无直接关系。

Our previous studies have demonstrated that the neurite-outgrowth promoting activity of cat spinal dorsal horn increased obviously after partial deafferentation and the substance which cause this kind of change existed in the fraction larger than 50 kD in molecular weight(MW)extract from dorsal horn. In order to explore this substance,we used the larger than 50 kD fraction extract from dorsal horn of five male adult cats with unilateral partial dorsal rhizotomy of hind limb(sectioning L_1～S_2 dorsal roots,except L_6 as spared root),11 days after rhizotomy.The samples were analyzed with polyacrylamide gel electrophoresis.Nine protein zones of both operated(operated side)and control(unoperated side)groups were observed and their areal Percentage of absorption peak was measured by optical densitometer.The areal percentage of protein absorption peak in relative mobility (RM) 0.1 zone of operated group was significantly larger than that of control group(P<O.05).On the other hand,protein absorption peak in RM 0.5 was lewered in operated group(P<0.05).This indicates that the protein content of RM 0.1 zone was increased and RM 0.5 zone decreased in operated group.Then the gel of these two protein zones was divided into smaller pieces as 1×1 mm￣2 in size and was co-cultured with dorsal root ganglion(DRG)from chicken embryo at Hamburger stage 35.At culturing 48 h,the average neurlte length of DRG co-cultured with gel from RM 0.1 zone of operated group was longer than that of control group(P<0.05).This means that the neurite-outgrowth promoting activity of 0.1 zone protein from operated group increased. However, the neurite length of the RM 0.5 zone showed no significant difference between two groups(P>0.05).It means that the RM 0.5 zone protein was not related directly with neurite-outgrowth.The protein content of RM 0.1 zone which is larger than 50 kD was increased after spared root operation,as well as it's promoting effect on DRG neurite-outgrowth increased also.This indicates that this protein has an activity in promoting neurite-outgrowth in other words,neurotrophic effect.It suggests that the increase of protein content in RM 0.1 zone may be a direct cause which results in increase of the neurite-outgrowth promoting activity of dorsal horn in vitro and the spared root collateral sprouting in vivo finally.