Conditioned nausea induced by cisplatin and emetine identified by a taste reactivity test in rats.

No prior studies have shown that gaping reactions are produced with the avoidance of conditioned taste caused by cisplatin and emetine. Therefore, we tried to demonstrate it using a taste reactivity test in rats and found the gaping reactions induced when saccharin is readministered after gustatory conditioning that paired saccharin with cisplatin or emetine. Since conditioned gaping reactions indicate the aversion to saccharin taste and conditioned nausea, the present study suggest that the taste aversion is induced by cisplatin and emetine. It was also found that with intraperitoneal injections of emetine alone, gaping almost never occurs.

Effects of area postrema lesions and bilateral subdiaphragmatic afferent vagotomy on emetine-induced conditioned taste avoidance in rats.

We investigated the effect of area postrema lesions and selective vagotomy of afferent fibers on emetine-induced nausea in rats. We evaluated the acquisition of the conditioned taste avoidance (CTA) to 0.1% saccharin solution after conditioning with emetine dihydrochloride (5.54 mg/kg, i.p., 1% BW). The CTA was measured in three groups of rats: a bilateral subdiaphragmatic afferent vagotomy group, an area postrema lesion group, and a sham lesion group. The bilateral vagotomy and sham groups of rats showed acquisition of CTA within 2 days of the test date. Taste avoidance was never conditioned in the area postrema lesion group. These results indicate that the area postrema plays a crucial role in the induction of emetine-induced nausea.