抄録
Recently, we developed a fictive cough model of the guinea pig to investigate the neuronal mechanisms underlying cough reflex and to assess the site of action of antitussive agents (Brain Res., Ohi et al., 2004). To clarify the functional importance of the nucleus tractus solitarius (NTS) in cough reflex, projection of the superior laryngeal nerve (SLN) afferents to the brainstem and the response induced by microstimulation of the NTS were studied. Strong fluorescence was detected ipsilaterally in the commissural NTS and the rostral NTS. At coronal slices, the fluorescent granules, lines and patches were located in the interstitial, ventromedial and dorsal areas of the NTS. Some activity was found in the contralateral dorsal area of the commissural NTS. Microstimulation of the rostral NTS, at which the strong fluorescence was detected, induced an increase in the inspiratory discharge of the phrenic nerve that was immediately followed by a large burst discharge of the iliohypogastric nerve. This serial response was identical to that induced by electrical stimulation of the SLN. The response induced by either NTS or SLN stimulation was suppressed by intravenous injection of codeine. Furthermore, the SLN-induced response was inhibited by microinjection of codeine into the ipsilateral NTS but not into the contralateral NTS. Ipsilateral lesion of the rostral NTS abolished both NTS and SLN-induced responses. These results suggest that the NTS plays essential roles in production of cough reflex and is possible sites of action of central antitussive agents. [Jpn J Physiol 55 Suppl:S107 (2005)]
