THE DISTRIBUTION AND ORIGIN OF AXON TERMINALS WITH NADPH DIAPHORASE ACTIVITY IN THE NUCLEUS OF THE SOLITARY TRACT OF THE RAT

The distribution and origin of axon terminals containing nitric oxide synthase (NOS) were examined in the nucleus of the solitary tract (NST) of the rat by NADPH diaphorase histochemistry combined with nodose ganglionectomy. Axon terminals with NADPH diaphorase activity were densely distributed in the middle and caudal part of the NST. After removal of the nodose ganglion (NG), most of the axon terminals with NADPH activity in the NST were eliminated on the ipsilateral side. These results indicated that most of the axon terminals with NADPH diaphorase in the NST derive from the primary afferent neurons in the NG, and that NOS may be richly contained in the central terminals of NG neurons to produce nitric oxide as a transmitter.