Serotonin is an important neurotransmitter, which plays a role in the brain and endows people with the ability to feel happiness. Therefore, it is also known as a “happy neurotransmitter”. The serotonin system is involved in a wide range of physiological functions of the human body, including the regulation of brain memory, cognition, emotion, learning, and addiction. The disorder of the serotonin system may cause a variety of mental diseases…