alpha-Methyl tryptophan as a tracer for in vivo studies of brain serotonin system, from autoradiography to positron emission tomography.

The procedure for measuring the brain serotonin synthesis rate in living brain using labelled alpha-methyl-L-tryptophan (alpha-MTrp), a tryptophan analog, is described. This tracer could also be used for the anterograde axonal transport measurement of serotonin. One advantage of this method is that alpha-MTrp is converted in situ into a serotonin tracer, alpha-methyl serotonin, and should be distributed into the same compartments as serotonin.