Male/female differences in drug-induced emesis and motion sickness in Suncus murinus

In order to elucidate possible male/female differences in emesis, the effects of various emetogenic drugs (cisplatin, copper sulfate, veratrine, nicotine, serotonin) and motion stimulus were compared between male and female Suncus murinus. Cisplatin (IP), nicotine (SC), veratrine (SC) and copper sulfate (PO) induced dose-dependent emesis in either sex, and there was no apparent difference in estimated ED50 values. However, male animals tended to be more susceptible to serotonin-induced emesis. The ID50 values for tropisetron, a 5-HT3 receptor antagonist, to block serotonin-induced emesis were also similar between male and female animals. However, tropisetron was less effective against cisplatin-induced emesis in females. Therefore, cisplatin may release more serotonin to induce emesis in females. Reciprocal shaking (horizontal oscillation 40 mm, frequency 0.5 to 2.0 Hz, duration 5 min) induced more frequent emesis in male animals, and the latency to the first vomit was shorter in males than in females. These results suggest that there is substantial sex-dependent difference in the emetic responses and male animals are in general more susceptible. These results are discussed in the light of similar studies in man.