Further evidence for the existence of endogenous serotonin uptake inhibitors and their purification by calmodulin affinity chromatography.

Experimental evidence suggests the occurrence of endogenous antidepressant-like compounds in the brain, blood plasma, and urine. After extensive purification by calmodulin-sepharose affinity chromatography, and further purification of the urine-derived sample by exclusion chromatography, at least three distinctive fractions have been identified. These fractions effectively inhibited serotonin uptake, imipramine, and/or paroxetine binding, and they apparently contained some compounds that were recognized by the anti-imipramine or anti-paroxetine antibodies. Their identification may have significant implications for studies of affective illness.