Davis H L, Heinicke E A
Brain Res. 1984 Sep 10;309(2):293-8. doi: 10.1016/0006-8993(84)90595-x.
Atrophy in a denervated muscle results from the disuse caused by paralysis of the muscle, and from the loss of special neurotrophic substances. Daily injections of proteins extracted from rats' sciatic nerves have been shown to prevent the non-disuse atrophy of rats' muscles denervated for 7 days. The trophic factor from chicken sciatic nerve which stimulates differentiation in aneural chick muscle in vitro has been purified and found to be closely similar to transferrin. We undertook to determine whether the trophic properties of mammalian nerve extract on denervated rats' muscles in vivo were due to the presence of serum transferrin in the extract. Atrophy was measured as the reduction in cross-sectional areas of type IIB fibers in the extensor digitorum longus muscle. Muscles denervated for 7 days and injected daily with 1 of several doses of iron-conjugated rat transferrin exhibited a rate of atrophy equivalent to that in denervated muscles that either were not treated or were injected with saline. Denervated muscles injected with crude extract of rats' sciatic nerves had significantly less atrophy than their controls. Removal of transferrin from the crude extract by immunoaffinity chromatography did not diminish its ameliorative effects on denervated muscle. Therefore, the trophic action of mammalian nerve extract on denervated rats' muscles in vivo is not due to the presence of serum transferrin in the extract.
失神经支配肌肉的萎缩是由肌肉麻痹导致的废用以及特殊神经营养物质的丧失引起的。每日注射从大鼠坐骨神经中提取的蛋白质已被证明可预防失神经支配7天的大鼠肌肉的非废用性萎缩。从鸡坐骨神经中提取的、能在体外刺激无神经支配的鸡肌肉分化的营养因子已被纯化，发现其与转铁蛋白非常相似。我们着手确定哺乳动物神经提取物对体内失神经支配大鼠肌肉的营养特性是否归因于提取物中血清转铁蛋白的存在。萎缩程度通过测量趾长伸肌中IIB型纤维横截面积的减少来确定。失神经支配7天且每日注射几种剂量的铁结合大鼠转铁蛋白之一的肌肉，其萎缩率与未治疗或注射生理盐水的失神经支配肌肉相当。注射大鼠坐骨神经粗提物的失神经支配肌肉的萎缩程度明显低于其对照组。通过免疫亲和层析从粗提物中去除转铁蛋白并不会削弱其对失神经支配肌肉的改善作用。因此，哺乳动物神经提取物对体内失神经支配大鼠肌肉的营养作用并非归因于提取物中血清转铁蛋白的存在。
