An autoradiographic method of mapping the distribution and density of monoamine neurons in mouse brain

A combined in vitro uptake and autoradiographic procedure as an important complement to the histochemical fluorescence method is described. Slabs of fresh mouse brain were incubated with 14C-NE, 14C-DA or 14C-5-HT, freeze-dried, and placed against X-ray film for autoradiography, Catecholamine nerve terminals were labeled by in vitro incubation with 14C-NE or 14C-DA. Dopaminergic terminals were labeled by 14C-NE incubation preceded by desipramine (to block uptake into NE terminals). With 14C-5-HT incubation, the uptake pattern indicated the possibility that 5-HT nerve terminals were being labeled. Advantages of this method are that it allows the visualization of overall density and distribution of selected monoamine nerve terminals or uptake sites of other putative neurotransmitters in whole coronal or sagittal sections, so that data are obtained from many areas of brain or spinal cord rather than in only those areas preselected for microscopic viewing.