Publication Date:
2018
Description:
〈p〉Neuropeptides are essential signaling molecules transported and secreted by dense-core vesicles (DCVs), but the number of DCVs available for secretion, their subcellular distribution, and release probability are unknown. Here, we quantified DCV pool sizes in three types of mammalian CNS neurons 〈i〉in vitro〈/i〉 and 〈i〉in vivo〈/i〉. Super-resolution and electron microscopy reveal a total pool of 1,400–18,000 DCVs, correlating with neurite length. Excitatory hippocampal and inhibitory striatal neurons 〈i〉in vitro〈/i〉 have a similar DCV density, and thalamo-cortical axons 〈i〉in vivo〈/i〉 have a slightly higher density. Synapses contain on average two to three DCVs, at the periphery of synaptic vesicle clusters. DCVs distribute equally in axons and dendrites, but the vast majority (80%) of DCV fusion events occur at axons. The release probability of DCVs is 1–6%, depending on the stimulation. Thus, mammalian CNS neurons contain a large pool of DCVs of which only a small fraction can fuse, preferentially at axons.〈/p〉
Print ISSN:
0261-4189
Electronic ISSN:
1460-2075
Topics:
Biology
,
Medicine
Permalink