Where are you getting your information? Tricyclic antidepressants are generally SNRIs, which definitely do effect the brain. It is true that the gut also has serotonin receptors, so there can definitely be side effects there, but to say that it's the only place where TCAs have an effect contradicts decades of medical research.
> Tricyclics work directly on gut neurology. [The effect you are noticing] [has] nothing to do with the brain [as it is a direct result of the direct effect the tricyclic has on the gut].
