Constant amplitude of postsynaptic responses for single presynaptic action potentials but not bursting input during growth of an identified neuromuscular junction in the lobster, Homarus americanus

Stefan R Pulver, Dirk Bucher, David J Simon, Eve Marder

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

As lobsters grow from early juveniles to adults their body size increases more than 20-fold, raising the question of how function is maintained during these ongoing changes in size. To address this question we studied the pyloric 1 (p1) muscle of the stomach of the lobster, Homarus americanus. The p1 muscle receives multiterminal innervation from one motor neuron, the lateral pyloric neuron of the stomatogastric ganglion. Staining with antibodies raised against synaptotagmin showed that as the muscle fibers increased in length, the spacing between the terminal innervation increased proportionally, so the number of synaptic contact regions/muscle fiber did not change. Muscle fibers were electrically coupled in both juveniles and adults. The amplitude of single intracellularly recorded excitatory junctional potentials evoked by motor nerve stimulation was the same in both juveniles and adults. Nonetheless, the peak depolarizations reached in response to ongoing pyloric rhythm activity or in response to high-frequency trains of stimuli similar to those produced during the pyloric rhythm were approximately twofold larger in juveniles than in adults. This suggests that homeostatic regulation of synaptic connections may operate at the level of the amplitude of the single synaptic potential rather than on the summed depolarization evoked during strong rhythmic activity.
Original languageEnglish
Pages (from-to)47-61
Number of pages15
JournalJournal of neurobiology
Volume62
Issue number1
DOIs
Publication statusPublished - Jan 2005

Keywords

  • Action Potentials
  • Aging
  • Animals
  • Calcium-Binding Proteins
  • Cell Size
  • Electric Stimulation
  • Excitatory Postsynaptic Potentials
  • Homeostasis
  • Membrane Glycoproteins
  • Motor Neurons
  • Muscle Fibers, Skeletal
  • Muscles
  • Nephropidae
  • Nerve Tissue Proteins
  • Neuromuscular Junction
  • Periodicity
  • Presynaptic Terminals
  • Stomach
  • Synaptic Transmission
  • Synaptotagmins

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