Tlr4 activation triggers tryptophan hydroxylase, leading to serotonin production, with 90% of serotonin produced in the GI tract.

“also because you're activating tlr4 that actually directly triggers the activation of the enzyme tryptophan hydroxylase and since tryptophan is always available it's a component of your muscle tissue um it's one of the essential amino acids right then you basically do whatever is floating around in the blood it's going to get converted into serotonin and it looks like the cells that Express the three to five hydroxy enzyme there's only two two regions in the body where this happens the GI tract and the Brain um so 90 of the serotonial produced can be produced in the GI tract another 10 in the brain”