INDUCTION OF FOS-LIKE PROTEIN IN NEURONS OF THE MEDULLA-OBLONGATA AFTER ELECTRICAL-STIMULATION OF THE VAGUS NERVE IN ANESTHETIZED RABBIT

Antibodies against the c-fos protein product Fos were used to map the first- and higher-order neurons in the rabbit medulla oblongata after electrical stimulation of the vagus nerve. Fos immunoreactivity appear ed bilaterally except in the nucleus tractus solitarii. Seven areas we re labeled: the nucleus tractus solitarii, the area postrema, the subn ucleus lateralis caudalis magnocellularis medullar oblongata, the late ral reticular nucleus, the ambiguus nucleus, the dorsal part of the sp inal trigeminal nucleus, the nucleus reticularis lateralis, the latera l border of the external cuneatus nucleus, the medial part of the infe rior olivary nucleus (subnucleus P). The last two areas have never bee n visualized with conventional tracing techniques and may represent hi gher-order neurons connected to visceral vagal pathways. No labeling w as observed in the nodose ganglion.