5-HT1A Receptors Mediate Analgesia Induced by Emulsified Sevoflurane in Thermal Nociception but Have Little Effect on Chemical Nociception.

OBJECTIVE

The study aimed to investigate the relationship between the analgesic effect of sevoflurane and 5-serotonin receptor 1A (5-HT1A R) in the spinal cords of mice.

METHODS

Analgesic mouse models were established by intraperitoneal injection of emulsified sevoflurane, and the influence of p-MPPF (a specific antagonist of 5-HT1A Rs) intrathecal injection on the changes in tail-flick latency in tail-withdrawal test, pain threshold in hot-plate test (HPPT), and writhing times in acetic acid-induced writhing test were recorded.

RESULTS

Intraperitoneal injection of emulsified sevoflurane alone produced an analgesic effect (p < 0.05). p-MPPF (2, 4, and 8 μg) alone had no impact on tail-flick latency, HPPT, and writhing times in mice (p > 0.05). The 3 doses of p-MPPF reduced the tail-flick latency or HPPT. p-MPPF 8 μg can increase the writhing times (p < 0.05) in analgesic mice with sevoflurane, while p-MPPF 2 and 4 μg did not affect the writhing times.

CONCLUSION

5-HT1A Rs in the spinal cord may be an important target for the analgesic effect of sevoflurane on the thermal nociception, but it has little relation to the anti-chemical chemical nociceptive effect of sevoflurane.