Abstract
Tryptophan metabolites through 5-hydroxytryptamine in the synovial fluid and blood of patients with rheumatoid arthritis and those with osteoarthritis were investigated in order to know the role of serotonin in the joint diseases. A metabolic map of tryptophan in the synovial fluid was also made. There were no significant differences in the levels of 5-hydroxytryptamine and 5-hydroxyindole acetic acid in the synovial fluid between rheumatoid arthritis and osteoarthritis, but the activity of monoamine oxidase in the synovial fluid was higher in osteoarthritis than in rheumatoid arthritis.
