Parabrachial Nucleus Of Neuronal Nitric Oxide Synthase Involved In The Transduction Of Visceral Noxious Stimulation

Objective: 1. To observe the subnuclei localization of the Fos immunoreactive (Fos-IR) neurons in the parabrachial nucleus (PBN) after visceral noxious stimulation; 2. To investigate whether the neural nitric oxide synthase (nNOS) in the PBN takes part in the transmission of visceral noxious stimulation; 3. Furthermore, to address whether nNOS in the PBN was involved in the transmission of visceral noxious stimulation through the parabrachio-amygdaloid pathway.Methods: 1. The distribution of Fos-IR neurons was mapped in subnuclei of the PBN by Fos immunohistochemical method, following injection 2% formalin into the stomach of rats; 2. The detailed colocalization of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and Fos, as a neuronal activity marker, in the subnuclei of the PBN was mapped using NADPH-d histochemistry combined with Fos immunohistochemistry, following 2% formalin injection into the stomach of rats; 3. Triple-labeled techniques were used by fluorogold (FG) retrograde tracing combined with Fos immunofluorescence and NADPH-d histochemistry following FG injection into the central nucleus of amygdala.Results: 1. The NADPH-d positive neurons and fibers appeared wide distribution in the PBN with topographical subnuclei localization, which was similar to our previous findings. Type I NADPH-d positive neurons, intensely labeled and with long processes, were mainly located in the rostral part of the...