Figure 7.

Schematic illustration of the proposed substrates for LTP in the LPP. The present evidence, and results described in the literature, suggest that the illustrated events are critical for the production of LPP-LTP. Glutamate (green triangles) released with brief bursts of high-frequency afferent stimulation activates NMDA- and mGluR5-type glutamate receptors and increases postsynaptic calcium content; these events engage the 2-AG synthesizing enzyme DGL-α. 2-AG produced postsynaptically then diffuses across the synapse and binds to CB₁ receptors on LPP terminals, thereby initiating signaling via small GTPases and the assembly of latrunculin-sensitive actin filaments. The resultant reorganization of the terminal actin cytoskeleton enhances evoked transmitter release.