FOS EXPRESSION IN FERRET DORSAL VAGAL COMPLEX AFTER PERIPHERAL EMETICSTIMULI

The aim of this study was to investigate neuronal activation in the do rsal vagal complex of the halothane-anesthetized ferret after peripher al emetic stimuli. Neuronal activity was studied by examining the dist ribution of the nuclear phosphoprotein Fos using immunohistochemistry. The emetic stimuli used were electrical stimulation of the supradiaph ragmatic vagal communicating branch (SVCB) or intraduodenal injection of hypertonic saline. Electrical stimulation of the SVCB induced the d ensest Fos expression within the medial subnucleus of the nucleus of t he solitary tract. After hypertonic saline injection, the greatest den sity of Fos-positive nuclei was observed within the area postrema and also in the medial subnucleus of the nucleus of the solitary tract. It was concluded that the emetic response to hypertonic saline involves neurons in both the area postrema and the nucleus of the solitary trac t, especially the medial subnucleus, and that the medial subnucleus is important in the emetic response to SVCB stimulation.