Activity-dependent deformations of presynaptic grids at central synapses

Area of Science:

• Neuroscience
• Cell Biology
• Synaptic Transmission

Background:

• Exocytosis, the process of neurotransmitter release, occurs at the presynaptic grid in the central nervous system (CNS).
• The dynamic structural changes of the presynaptic grid during exocytosis are not fully understood.

Purpose of the Study:

• To investigate alterations in the presynaptic grid structure during exocytosis.
• To explore the role of the presynaptic grid in regulating neurotransmitter release.

Main Methods:

• Studied synapses of unmyelinated club endings on Mauthner cells in teleosts.
• Utilized aldehyde fixation, cooling, and high-KCl Ringer solution perfusion.
• Performed morphometric analysis of the presynaptic grid structure.

Main Results:

• Cooling diminished vesicle openings, while high-KCl perfusion enhanced them.
• Increased exocytotic events correlated with increased distance between presynaptic dense projections.
• The spaces between dense projections enlarged transiently with vesicle exocytosis.

Conclusions:

• The presynaptic grid is dynamically involved in the secretory process.
• Presynaptic dense projection movement may be linked to plasma membrane interactions.
• Grid distortion might regulate the number of vesicles released per impulse.
• Dense projections may stabilize the plasma membrane during intense release.