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Figure 1. Schematic diagram shows models for PDYN trafficking, storage, and processing in neurons. Results support synaptic hypothesis depicted in B. A) Classical model postulates that in neurons processing of neuropeptide precursors into mature neuropeptides is initiated in somatic trans-Golgi network (TGN) and takes place in secretory vesicles during their transport from the perikaryon to nerve terminals. B) The synaptic model proposed here is that neuropeptide precursors are transported to axon terminals and dendrites where they are stored in an unprocessed form. Their processing at these locations may be activated by neuronal activity or extracellular stimuli, thus providing a local mechanism for regulation of synaptic transmission.
