Botulinum-induced muscle paralysis alters metabolic gene expression and fatigue recovery

Fredric A Gorin, Kevin Herrick, Byron Froman, Warren Palmer, Robert Tait, Richard Carlsen

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Abstract

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.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume270
Issue number1 39-1
StatePublished - 1996

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Keywords

  • botulinum A toxin
  • contractile properties
  • lipoprotein lipase gene
  • muscle isozyme of glycogen phosphorylase gene
  • skeletal muscle

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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