Double Staining Method for Monoamine Oxidase and Cholinesterase

Abstract

For the investigation on neurohumoral theory, we have studied histochemically the distribution of monoamine oxidase (MAO) and cholinesterase (ChE) in various animals. Our hypothesis thereby was that the neuron with ChE activity is cholinergic and the neuron with MAO activity and noradrenalinelike fluorescing is adrenergic. In the course of our study, however, some nerve cells with high activity of MAO were found to show marked reaction not only in the cytoplasm, but also seemingly in the nucleus. Sympathetic ganglia consist mainly cells of this“nuclear-positive”type and this type was supposed to be the characteristic feature of the adrenergic cell. The question arised about the nature of another“nuclear-negative”type of MAO-positive cells and about the relationship of these two types with ChE-positive cells. On the other hand, both MAO and ChE activity were found to be present simultaneously in some ganglia and nuclei of the central nervous system. The problem was whether these two enzymes coexisted to the same cell or they were contained in different cells which were mixed up one with the other.To meet the technical demands in solving these problems a“double staining method”was investigated which would allow to demonstrate the activity of both enzymes on the same tissue section. This method was found to be valuable also for the observation of minute interrelationship between the localization on MAO and ChE.