Relationship between neuronal nicotinic acetylcholine receptors and the hypnotic and analgesic effects of isoflurane and sevoflurane

Aim To investigate the relationship between neuronal nicotinic acetylcholine receptors(nnAChRs) and the hypnotic and analgesic effects of isoflurane and sevoflurane.Methods After the establishment of the mice model of hypnosis and analgesia by intraperitoneal injection(ip)of appropriate doses of isoflurane or sevoflurane, the different doses of nicotine were injected intra-cerebroventricularly(icv) or intrathecally(it) and then their effects were observed on the sleeping time(ST), the pain threshold in hot-plate test (HPPT) and writhing times by using acetic acid-induced writhing test.Results In awaken test,nicotine 10,20,40 μg(icv) could significantly decrease ST of the mice treated with isoflurane or sevoflurane(P0.05 or P0.01);in hot-plate test, nicotine 5,10,15 μg (it) did not affect the HPPT in conscious mice(P0.05),in contrast,nicotine 5,10,15 μg (it) could significantly and dose-dependently decrease the HPPT of the mice treated with isoflurane or sevoflurane(P0.05 or P0.01).In acetic acid-induced writhingtest,writhing times inhibition induced by sc admi-nistered isoflurane or sevoflurane was not affected by the nicotine 5,10,15 μg(P0.05).Conclusions nnAChRs may be important targets for the hypnotic effects and analgesic effects on thermal-induced nociception but not chemcial-induced nociception of isoflurane and sevoflurane.