Glutamate-like immunoreactivity in medulla oblongata catecholamine/substance P neurons

Immunofluorescence histochemistry was performed on sections of the rat medulla oblongata with a well characterized antibody to the amino acid glutamate (GLU) combined with antisera to catecholamine synthesizing enzymes and substance P. GLU-like immunoreactive (LIR) neurons were seen in many areas of the medulla, and were particularly intensely stained in the rostral ventrolateral medulla. In this area, nearly all adrenaline neurons were GLU-LIR. This immunoreactivity was also seen in catecholamine neurons of the C2, C3, A1 and A2 cell groups. Many adrenaline neurons, especially of the C1 group, contained substance P-LI in addition to GLU-like immunoreactivity (LI).