The Kölliker-Fuse nucleus mediates the trigeminally induced apnoea in the rat

The present study examined whether the Kölliker-Fuse nucleus (KF) plays a role in mediating the trigeminally induced apnoea which occurs after noxious perturbation of the nasal mucosa. We stimulated the ethmoidal nerve (EN5) electrically and recorded respiratory responses before and after injections of the calcium channel blocker CoCl2 into the KF. Unilateral EN5 stimulations resulted in an apnoea or in a reduction of respiratory frequency and tidal volume. EN5 stimulations immediately after ipsilateral CoCl2 injections into the caudal KF caused only minor respiratory suppression, indicating a blockade of synaptic transmission. Recovery of the respiratory responses was observed 15-120 min after the CoCl2 injection. Our data strongly suggest that the caudal KF is an obligatory relay site for trigeminally induced apnoea.