Definitions

1. noun

A neurotransmitter that functions as a hormone, playing a key role in regulating mood, appetite, and sleep, among other functions.

“The study of serotonin levels in the brain can help us understand the causes of depression.”

2. noun

A group of tryptophan derivatives found in the brain and intestines, involved in various physiological processes.

“The researchers discovered that the levels of serotonin in the gut were linked to the immune system.”