Quantitative histochemical studies of striatal dopamine depletion following dl-α-methyl-p-tyrosine administration

This study investigated the use of a microfluorimetric histochemical method for the measurement of the depletion of dopamine in the rat caudate nucleus, following α-methyl-p-tyrosine (α-MT) administration. The depletion in three behavioral situations was compared with that of a control group which remained in a cage.The results of the control group indicate that there had been a reduction of approximately 50% in the intensity of the formaldehyde-induced fluorescence derived from dopamine in a region of the neuropil of the caudate nucleus, during the interval (3 hr 40 min) between α-MT, 300 mg/kg i.p., and killing. Disruption of conditioned avoidance response (CAR) performance after α-MT administration was confirmed, but in this study CAR performance in previously trained rats did not have a significant effect on the depletion of formaldehyde-induced fluorescence of the striatal neuropil after α-MT administration. The levels of α-MT-induced depletion of formaldehyde-induced fluorescence in the striatal neuropil following a period of muscular co-ordination/activity and following a period of CAR training were also not significantly different from those shown by a control group.