19. The spectrophotofluorimeter and early spectrophotofluorimetric findings with reserpine and iproniazid.
The Aminco Bowman spectrophotofluorimeter was constructed by Bowman, Caulfield and Udenfriend in the mid-1950s. The resolution power of the new instrument allowed for the first time to analyze by chemical methods several compounds that occur in small amounts in the brain, such as the monoamines involved in neuronal transmission and their precursors and metabolites. By measuring the turnover rate of cerebral monoamines with the employment of the spectrophotofluorimeeter, in 1956 and 1957, Alfred Pletscher and his associates, in Bernard Brodie’s laboratories, found that administration of reserpine decreased, whereas the administration of iproniazid, a monoamine oxidase inhibitor, increased, brain serotonin levels. Considering the euphoria encountered in some tubercular patients in the course of treatment with iproniazid, the possibility was entertained that monoamine oxidase inhibition, and the resulting increase of brain serotonin levels, was responsible for the mood lifting effect of iproniazid; and considering the dysphoria, encountered in some hypertensive patients in the course of treatment with reserpine, and the finding that only the biologically active, i.e., “sedating” and “catalepsy-inducing,” Rauwolfia alkaloids, produced a decrease of serotonin, the possibility was entertained that the decrease of serotonin levels was responsible for the mood depressant effect of reserpine.