Induction of emesis in Suncus murinus by pyrogallol, a generator of free radicals

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Abstract
1 We investigated whether or not pyrogallol, a generator of free radicals, is emetogenic in Suncus murinus, the house musk shrew. Pyrogallol (i.p.) caused dose-dependent emesis in suncus with an ED50 value of 77.3 mg kg−1. At a dose of 128 mg kg−1, all suncus vomited with mean latency of 18.8 ± 5.2 min and the number of vomiting episodes was 8.6 ± 2.9. 2 The prophylactic effects of N-(2-mercaptopropionyl)-glycine (MPG), an antioxidant, and tropisetron, a 5-hydroxytryptamine3 (5-HT3) receptor antagonist, were studied. Pyrogallol (128 mg kg−1, i.p.)-induced emesis was prevented by treatment with MPG (i.p.) or tropisetron (s.c.) with ID50 values of 149 mg kg−1 and 117 μg kg−1, respectively. 3 Pyrogallol-induced emesis was completely prevented by surgical abdominal vagotomy. 4 The present results indicate that pyrogallol-induced emesis is characteristically very similar to that caused by cisplatin and support the idea that generation of free radicals causes the release of peripheral 5-HT, which stimulates vagal afferent sensory nerves to cause emesis.