But sometimes it doesn't get that far, because special types of bugs in your gut get to the building block version first. They do the same thing your brain does to it, but it's unclear what the effects are, because it's happening in your gut before it gets to your brain.
This is a paper confirming and isolating one of those special types of bugs. The implications could be pretty big: Are these bugs affecting medications? Moods? Are they stealing our brain's supply of feel good chemical? Can we use their powers for good?
Endorphins are more accurately "feel good" chemicals.
Dopamine is involved in motivation through reward reinforcement, movement, and cognition in the human nervous system.
Another nitpick: L-DOPA isn't a building block of dopamine. It's dopamine with an extra molecule attached to it that makes it "inactive." This molecule gets snapped off by the AADC enzyme, which "activates" it. L-DOPA is the precursor to dopamine.
Third nitpick: We can understand how these gut flora affect ingestion of L-DOPA, and neurotransmitter precursors, by looking at how it's used in medical treatments. Most notably, Parkinson's patients. Suffice to say, it really makes no fucking difference, and orally-administered L-DOPA (with a dehydroxylaze inhibitor) is effective.
Whatever L-DOPA is stolen by gut-flora, can be augmented with a higher dosage. If for some strange reason, the converted L-DOPA -> Dopamine gets released into the digestive tract, and absorbed by the body, it's readily broken down in the blood. L-DOPA converts to dopamine in the blood-stream anyway, so it makes absolutely no difference.
I wanted this paper to be novel, but after reading it, it's not.
Gut flora have AADC-like enzymes, cool?
That dopamine release is what is directly responsible for pleasure and euphoria associated with endorphin release.