Serotonin from the gut affects vagal neurons. They carry that signal directly to the brain. That has a significant effect on up and down regulation of mood and arousal.
replyOkay that’s like my company that uses Salesforce that sends an invoice to another company that also uses Salesforce.
replyThe fact that we both use Salesforce does not matter. It’s internal and doesn’t mean anything outside the company. Both the brain and gut re-used the molecule for their own internal signaling. Evolutionarily it was cheaper to use an existing molecule.
To the brain, the invoice is just “I’m full” or “I’m hangry.” It doesn’t care how much serotonin the gut had to produce internally to issue that “invoice.” The brain will produce its own serotonin from the signal of satiety but it won’t give you any more than you can from just feeling full.
It is a powerful neuron hormone. The mechanisms are different. It is still important to recognize the rather dramatic influence this has on the brain. That was what this article was about. This pathway can easily lead to depression and significant broad down regulation in the brain. Serotonin inside of the brain works very specifically. The vagus nerve signal has a very broad impact and should not be hand waved. If your vasovagal system has dysregulation it can lead to all sorts of specific brain internal negative outcomes systemically. I think your model of how this works is not very accurate regarding how broadly connected the vagal signaling pathway is and how that impacts how your brain functions.
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