A compound present in blood platelets and serum that constricts the blood vessels and acts as a neurotransmitter.
- ‘These work by raising the levels of the chemicals serotonin and noradrenaline in the brain, which both tend to elevate the mood.’
- ‘There is some evidence of that the neurotransmitter serotonin may play a role in this disorder.’
- ‘These physiological changes decrease patients' pain thresholds and thereby increase pain sensation, anxiety, fear, and the release of pain transmitters, such as histamines, serotonins, kinins, and prostaglandins.’
- ‘Tryptophan is an amino acid that serves as a precursor to the neurotransmitter serotonin.’
- ‘Both serotonin and noradrenaline are activated in the brain by anxiety-inducing circumstances.’
1940s: from serum + tonic + -in.