[Histofluorescence of catecholamines and visualization of retrograde transported peroxidase in the same tissue section and in the same neuron].

The demonstration of fluorescent catecholamines and horseradish peroxidase (HRP) in the same neuron has been achieved in the Rat in two ways: by submitting vibratome sections to a modified glyoxylic acid fluorescence method followed by the usual procedure to reveal HRP; or by combining the last procedure with the cryostat technique of Chiba et coll. After HRP injection into the striatum or the nucleus accumbens of the Rat, non-fluorescent HRP labelled neurons were observed in the substantia nigra and the ventral tegmental area respectively, in addition to the HRP labelled fluorescent dopaminergic neurons.