Gut brain commmunication

Norepinephrine ; arousal

During acute stress, brain-derived norepinephrine affects on the gastrointestinal tract through the sympathetic nervous system, changing motility and activating gut bacteria.

Dopamine; sense of pleasure 

Short-chain fatty acids (SCFAs), which affect brain dopamine signaling via the gut-brain axis and affect motivation, reward, mood, and cognitive function, are produced by microbiota through the synthesis of neurotransmitters and the breakdown of precursors. 

GABA; inhibitor

GABA is produced by the gut bacteria from food ingredients and regulates anxiety and inhibitory transmission. Influenced by the microbiome, peripheral GABA can work directly on to reduced stress and anxiety.

Serotonin; mood regulation

Tryptophan metabolism, serotonin reuptake, and serotonin synthesis are all regulated by gut flora. Serotonin levels in the brain and colon can be raised by some bacteria, such as Akkermansia muciniphila.