Exogenous synapsin I promotes functional maturation of developing neuromuscular synapses

Neuron. 1992 Mar;8(3):521-9. doi: 10.1016/0896-6273(92)90280-q.


We have investigated the possible role of synapsin I, a nerve terminal-specific protein, in the maturation of neuromuscular synapses in Xenopus cell cultures. Purified synapsin I was loaded into embryonic spinal neurons by injection of the protein into one of the early blastomeres of a Xenopus embryo. At synapses made by synapsin I-loaded neurons, spontaneous synaptic currents occurred with higher frequency and amplitude, and the amplitude exhibited an earlier appearance of a bell-shaped distribution. These characteristics are indicative of more mature quantal secretion. Impulse-evoked synaptic currents also showed a significant increase in amplitude. Using cell manipulation techniques, enhanced transmitter release from synapsin I-loaded neurons was shown to occur at the onset of synaptogenesis, suggesting a presynaptic developmental action of synapsin I prior to synaptic contact. Taken together, these results suggest that endogenous synapsin I may participate in the functional maturation of synapses.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcholine / metabolism
  • Animals
  • Cells, Cultured
  • Electric Conductivity
  • In Vitro Techniques
  • Neuromuscular Junction / growth & development*
  • Synapses / physiology*
  • Synapsins / metabolism*
  • Synaptic Transmission
  • Time Factors
  • Xenopus laevis / embryology


  • Synapsins
  • Acetylcholine