Activity of phasic motor neurons partially transforms the neuronal and muscle phenotype to a tonic-like state.
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.
Cooper
R L
RL
Section of Organismal and Integrative Biology, Thomas Hunt Morgan School of Biological Sciences, Lexington, Kentucky, USA.
Warren
W M
WM
Ashby
H E
HE
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D003400:Astacoidea / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology; D004558:Electric Stimulation; D004576:Electromyography; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology; D009124:Muscle Proteins / Q000032:analysis; D009129:Muscle Tonus / Q000502:physiology*; D009132:Muscles / Q000737:chemistry / Q000294:innervation / Q000502:physiology; D009210:Myofibrils / Q000737:chemistry / Q000502:physiology; D010641:Phenotype
D009124:Muscle Proteins