Quantitative Histochemical Studies of Formaldehyde‐induced Parenchymal Fluorescence Following L‐dopa Administration

A microfluorimetric method is described for quantitative histochemical study of diffuse formaldehyde‐induced fluorescence in the neuropil of various brain regions and was used to investigate the effects of L‐DOPA in the rat and cat. Regional and species differences in the effects of L‐DOPA on the CNS are reported and discussed. In the rat, suitable doses of L‐DOPA led to increases in the intensity of fluorescence in the neuropil of the samples of caudate nucleus, which were greater than the increases in the neuropil of the other regions studied. Marked increases in the intensity of fluorescence in the neuropil of the cat brain samples were produced by doses of L‐DOPA/kg body wt. which were too low to produce detectable increases in the fluorescence of the rat brain samples.