SEROTONIN

There has been a controversy as to whether mental diseases are caused by dopamine errors or serotonin errors. This author favors dopamine theories. For one thing, dopamine is a precursor of stress-related substances. For another thing, dopamine is a precursor of pigments (neuromelanin). Pigment excesses have been reported by neuropathologists in mental disease.
There is some evidence in favor of serotonin theories. For one thing the chemical structure of serotonin resembles that of some hallucinogens. For another thing tryptophan is a prescursor of serotonin. Excessive tryptophan has been found to flood the cells in schizophrenia and also in depression.

This drawing shows pathways of dopamine and of serotonin neurons. Dopamine is found in the basal ganglia and in the frontal lobes. Serotonin is found in the brain and also in the intestines. Both are important neurotransmitters.

Shown here is the metabolic pathway leading to serotonin. Tryptophan also has another pathway which leads to the production of niacin.

This is the chemical structure of serotonin, an important neurotransmitter. Measurements of serotonin itself are normal in the brain in schizophrenia. One theory postulates a toxin made from serotonin in the brain. One such theory is the bufotenin theory.

Shown here are some brain toxins derived from tryptophan. DMT is a hallucinogen. Serotonin is beneficial. Bufotenin is very toxic. Bufotenin could be produced from serotonin by a double methylation of serotonin. Whether this happens or not is unclear.