Progressive motor unit loss in the G93A mouse model of amyotrophic lateral sclerosis is unaffected by gender

Muscle Nerve. 2009 Mar;39(3):318-27. doi: 10.1002/mus.21160.


We examined whether there are gender differences in the progressive loss of functional motor units in SOD1(G93A) transgenic mice. Isometric muscle and motor unit twitch contractions were recorded in fast- and slow-twitch muscles in response to stimulation of the sciatic nerve. Using a modified motor unit number estimation technique (ITS-MUNE), we found that motor unit numbers declined rapidly from 40 to 90 days of age during the asymptomatic phase of ALS in fast- but not slow-twitch hindlimb muscles of both male and female mice. There was a corresponding decline in twitch and tetanic contractile forces of the fast-twitch muscles. Gender did not affect the progressive loss of motor units and associated decline in force production. We conclude that gender does not alter progressive, muscle-specific motor unit loss in ALS, even though gender does influence disease onset.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Amyotrophic Lateral Sclerosis / genetics*
  • Amyotrophic Lateral Sclerosis / pathology
  • Amyotrophic Lateral Sclerosis / physiopathology*
  • Animals
  • Disease Models, Animal
  • Disease Progression
  • Electromyography / methods
  • Female
  • Humans
  • Male
  • Mice
  • Mice, Transgenic
  • Motor Neurons / physiology*
  • Muscle Contraction / physiology
  • Muscle, Skeletal / pathology*
  • Muscle, Skeletal / physiopathology
  • Organ Size / physiology
  • Sex Factors
  • Superoxide Dismutase / genetics*


  • SOD1 G93A protein
  • Superoxide Dismutase