Tyrosine hydroxylase and NADPH-diaphorase in the rat nodose ganglion: Colocalization and central projection

The present study was conducted to reveal the morphological characteristics of neurons of the nodose ganglion expressing nitric oxide synthase (NOS) a nd/or tyrosine hydroxylase (TH). The NADPH-diaphorase activity, a histochem ical marker for NOS, was observed in 60% of ganglionic neurons, but TH-immu noreactivity shared only 8% of total ganglionic neurons. In this ganglion, 55 % of TH-immunoreactive neurons expressed NADPH-diaphorase activity. By t he triple combination of retrograde neuronal tracer (rhodamine-labeled late x microspheres) injected into the rostral part of the nucleus tractus solit arius, the NADPH-diaphorase histochemistry and TH-immunocytochemistry, we f ound that 38 % of NADPH-diaphorase positive neurons, 70% of TH-immunoreacti ve neurons, and 72% of NADPH-diaphorase/TH-positive neurons contained the r hodamine-latex fluorobeads. Thus, it is concluded that many of NOS and/or T H expressing neurons in the nodose ganglion centrally project primary senso ry neurons.