Gorin F, Herrick K, Froman B, Palmer W, Tait R, Carlsen R
Department of Neurology, School of Medicine, University of California, Davis 95616, USA.
Am J Physiol. 1996 Jan;270(1 Pt 2):R238-45. doi: 10.1152/ajpregu.1996.270.1.R238.
We evaluated the physiological, histochemical, and biochemical consequences of inhibiting contractile activity in rat skeletal muscles with botulinum toxin A (BTX). Contractile activity was entirely eliminated 12-18 h after a single, focal, intramuscular injection of BTX into the rat tibialis anterior muscle (TA). Neuromuscular transmission remained completely inhibited for 10-12 days, then slowly recovered. BTX-treated muscles exhibited a lower resistance to both high- and low-frequency fatigue at 7 and 14 days after injection, but contractile force recovered more rapidly in treated TA after fatigue. Treated TA showed a twofold increase in the activity of the triglyceride hydrolase enzyme lipoprotein lipase (LPL) and a comparable increase in the relative abundance of LPL steady-state mRNA. In contrast, there was a 28% reduction in protein levels of the muscle isozyme of glycogen phosphorylase (MGP) and a 70% decrease in relative MGP transcript levels. Similar changes in relative transcript levels of LPL and MGP were observed in the predominantly fast-twitch extensor digitorum longus after BTX injection, but relative LPL and MGP mRNA levels were not altered in predominantly slow-twitch soleus. Histochemical evidence indicated that fast-twitch glycolytic fibers had increased lipid content. These biochemical alterations were reversed 120 days after BTX treatment despite persistent atrophy.
我们评估了用A型肉毒杆菌毒素（BTX）抑制大鼠骨骼肌收缩活动所产生的生理、组织化学和生化后果。在大鼠胫前肌（TA）进行单次局部肌肉注射BTX后12 - 18小时，收缩活动完全消除。神经肌肉传递在10 - 12天内一直受到完全抑制，然后缓慢恢复。注射后7天和14天，经BTX处理的肌肉对高频和低频疲劳的抵抗力较低，但疲劳后经处理的TA中的收缩力恢复得更快。经处理的TA中甘油三酯水解酶脂蛋白脂肪酶（LPL）的活性增加了两倍，LPL稳态mRNA的相对丰度也有类似增加。相比之下，糖原磷酸化酶肌肉同工酶（MGP）的蛋白质水平降低了28%，相对MGP转录水平降低了70%。在注射BTX后，在主要为快肌的趾长伸肌中也观察到LPL和MGP相对转录水平的类似变化，但在主要为慢肌的比目鱼肌中，LPL和MGP的相对mRNA水平没有改变。组织化学证据表明，快肌糖酵解纤维的脂质含量增加。尽管持续萎缩，但这些生化改变在BTX处理120天后逆转。
