Fos Expression in the Brainstem Nuclei Evoked by Nasal Air-Jet Stimulation in Rats

Abstract

Background Noxious stimulation of the nasal mucosa may induce protective reflexes in the upper airway in rats. Previously, we have reported that nasal air-jet stimulation increases the activities of the laryngeal muscles in decerebrate cats; however, the neuronal mechanism of this phenomenon still is not clarified. Methods After the application of nasal air-jet stimulation for 2 hours, we investigated the distribution of Fos-positive cells (FPCs) throughout the medulla compared with sham-operated rats using Fos immunoreactivity. Results FPCs in the spinal trigeminal nucleus, the parvocellular reticular nucleus, and the nucleus of the solitary tract were more frequent than the sham-operated rats. Conclusion These results suggest that the afferents induced by air-jet stimulation were conveyed to these FPCs and that some of these cells might participate in the augmentation of laryngeal muscle activities during nasal air-jet stimulation.