Involvement of 5-hydroxytryptamine type 3 receptors in sevoflurane-induced hypnotic and analgesic effects in mice

In the present study, we investigated the role of 5-hydroxytryptamine type 3 (5-HT3) receptors in hypnosis and analgesia induced by emulsified sevoflurane. Amouse model of hypnosis and analgesia was established by an intraperitoneal or subcutaneous injection of emulsified sevoflurane. We intracerebroventricularly (icv) or intrathecally (it) administered YM-31636, a 5-HT3 receptor agonist, to mice and observed sleep time during hypnosis. In addition, the tail withdrawal latency was measured using the tail withdrawal test, and the writhing time was determined using the acetic acid writhing test. In the hypnosis test, YM-31636 (5, 10 and 15 µg, icv) treatment significantly decreased emulsified sevoflurane-induced mouse sleep time (p < 0.05 or p < 0.01). YM-31636 (2.5, 5 and 10 µg, it) treatment significantly and dose-dependently decreased the tail withdrawal latency (p < 0.05 or p < 0.01) and increased the writhing time (p < 0.01) of mice treated with emulsified sevoflurane. These results suggest that 5-HT3 receptors may modulate the hypnotic and analgesic effects induced by emulsified sevoflurane.