Evidence for the existence of ornithine decarboxylase-immunoreactive neurons in the rat brain

By means of polyclonal antibodies against purified mouse kidney ornithine decarboxylase (ODC) and using the biotin-avidin immunoperoxidase procedure in combination with image analysis the cellular localization and distribution of ODC immunoreactivity (ODC IR) have been demonstrated in the rat brain. ODC IR was located in a large number of neuronal populations. A nuclear ODC IR was always present but in many neurons also a cytoplasmic localization of ODC IR was demonstrated (dendrites, axons and putative terminals). Based on the present findings central neurons may be mapped out not only on the basis of their transmitter contents but also on the basis of their contents of trophic factors.