Response of neurons in the solitary tract nucleus, area postrema and lateral parabrachial nucleus to gastric load of hypertonic saline

c-Fos was induced in the solitary tract nucleus (NTS), area postrema (AP) and lateral parabrachial nucleus (LPB) by the intragastric injection of hypertonic saline. The effect was bilateral and most dramatic in the NTS caudal to the facial nucleus and the AP, the areas receiving dense vagal afferent projection from the subdiaphragmatic structures. At least a part of these Fos-LI is considered to have been induced by the activation of the visceral osmoreceptors.