Activity of phasic motor neurons partially transforms the neuronal and muscle phenotype to a tonic-like state

Muscle Nerve. 1998 Jul;21(7):921-31. doi: 10.1002/(sici)1097-4598(199807)21:7<921::aid-mus10>;2-t.


We present a model preparation, the crayfish, to investigate chronic stimulation effects in muscle fiber type and neuronal conversion from fast to slow. The results show a presynaptic alteration in transmitter release after 1 week of stimulation at 5 Hz for a 2-h daily regime. With the same stimulation paradigm, the muscle proteins displayed on a polyacrylamide gel only start to show changes after 3 weeks. The original phasic motoneurons within 1 week display an enhanced ability to resist synaptic depression, as do tonic motoneurons. The results show that identified phasic motoneurons and muscle fibers in the crayfish can be transformed to a toniclike state, and that the nerve terminals convert prior to the muscle fibers. Electrophysiological clinical measures indicating a change in transmitter release properties may not necessarily mean that the muscle fibers have fully adapted for long-lasting effects. This preparation allows stimulation conditions to be examined with ease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Astacoidea / physiology*
  • Conditioning, Psychological / physiology
  • Electric Stimulation
  • Electromyography
  • Excitatory Postsynaptic Potentials / physiology
  • Motor Neurons / physiology*
  • Muscle Fatigue / physiology
  • Muscle Proteins / analysis
  • Muscle Tonus / physiology*
  • Muscles / chemistry
  • Muscles / innervation
  • Muscles / physiology
  • Myofibrils / chemistry
  • Myofibrils / physiology
  • Phenotype


  • Muscle Proteins