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It is well known that small neurotransmitters like monoamines (dopamine, serotonin, etc), acetylcholine, glutamate, etc are loaded into vesicles at the axon terminal. Stated differently, synaptic vesicles,SVs (which are the name of the vesicle type that store small neurotransmitters), are made locally within the axon terminal, and then ultimately loaded with small neurotransmitters.

However, I cannot seem to find when larger molecules, like neuropeptides, are actually loaded into their vesicles. I know that neuropeptides are made in the soma, but I am unsure of when they are loaded into their vesicles.

Are neuropeptides loaded into their vesicles at the synapse?

" Small-molecule neurotransmitters are synthesized locally within the axon terminal" https://web.williams.edu/imput/synapse/pages/I.html

"As a rule, the synthesis of small-molecule neurotransmitters occurs within presynaptic terminals" https://www.ncbi.nlm.nih.gov/books/NBK11110/

"SVs are made locally at the terminals and are regenerated after exocytosis" https://www.sciencedirect.com/science/article/pii/B9780080450469013929

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    $\begingroup$ Can you cite your sources? There are major errors in your question, almost all of the things you say you "know" are incorrect. $\endgroup$
    – Bryan Krause
    Apr 23, 2019 at 15:09
  • $\begingroup$ here are the citations. If the small molecules are synthesized locally within the axon terminal, they are clearly being stored in the vesicle within the axon terminal. This is the general dogma of vesicular packaging. $\endgroup$
    – S.C.
    Apr 23, 2019 at 15:19
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    $\begingroup$ What about the rest of your statements? You've cited only the things are correct, you haven't corrected anything that is wrong. $\endgroup$
    – Bryan Krause
    Apr 23, 2019 at 15:19
  • $\begingroup$ I am unaware of any of my statements being wrong. Could you please enlighten me? I am not trying to promulgate false information. These are my understandings of concepts. $\endgroup$
    – S.C.
    Apr 23, 2019 at 15:21
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    $\begingroup$ " Stated differently, vesicles are made in the soma, shipped down to the axon terminal (via motor proteins), and then ultimately loaded with small neurotransmitters." is wrong. $\endgroup$
    – Bryan Krause
    Apr 23, 2019 at 15:25

1 Answer 1

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Neuropeptides are packaged in the soma via the Golgi into dense core vesicles, similar to how other types of secreted proteins are packaged.

These vesicles are transported to axon terminals where they await release signals.


Sossin, W. S., Fisher, J. M., & Scheller, R. H. (1989). Cellular and molecular biology of neuropeptide processing and packaging. Neuron, 2(5), 1407-1417.

Wong, M. Y., Zhou, C., Shakiryanova, D., Lloyd, T. E., Deitcher, D. L., & Levitan, E. S. (2012). Neuropeptide delivery to synapses by long-range vesicle circulation and sporadic capture. Cell, 148(5), 1029-1038.

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  • $\begingroup$ Do dense core vesicles also have all of the traditional synaptic transmembrane proteins in them like synaptotagmin and synaptobrevin? Or are those specifically unique to the "synaptic vesicles" $\endgroup$
    – S.C.
    Apr 24, 2019 at 8:33
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    $\begingroup$ @S.Cramer At least some of them do. Some are not released by calcium so I'm not sure what machinery they have for membrane fusion. $\endgroup$
    – Bryan Krause
    Apr 24, 2019 at 13:35
  • $\begingroup$ Interesting. I ask because the one article that I mentioned in the comments above (about "synaptic vesicles") explains that the specific transmembrane synaptic proteins are only incorporated into the vesicle once the components have FIRST merged with the axon terminal. Then, via an endocytosis process, these transmembrane proteins are somehow selected to be included in the synaptic vesicle during its assembly. If you're saying that "at least some of them do", then clearly these transmembrane proteins are being incorporated in to the vesicle membrane in a very different manner. Cheers~ $\endgroup$
    – S.C.
    Apr 24, 2019 at 14:30
  • $\begingroup$ Can you point me to where in the article you see that? $\endgroup$
    – Bryan Krause
    Apr 24, 2019 at 14:37
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    $\begingroup$ Ah I see, well for the small molecule vesicles of course that is the case because they do not come pre-packaged and are recycling membrane from the synapse. It's possible that dense core vesicles undergo some merge with an endosome at some point, I'm not sure though, I'd have to research that separately. I just know that at some point some of them will contain synaptotagmin. $\endgroup$
    – Bryan Krause
    Apr 24, 2019 at 14:58

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