Relationship between gamma-hydroxybutyric acid receptors and the hypnotic and analgesic effects of emulsified inhalation anesthetics.

OBJECTIVES: This study was designed to investigate the role of gamma-hy - droxybutyric acid receptors (GHBR) in hypno - sis and analgesia induced by emulsified inhala - tion anesthetics. MATERIALS AND METHODS: After having established the mice model of hypnosis and analgesia by intraperitoneal injections of ap - propriate doses of enflurane, isoflurane, or sevoflurane, we intracerebroventricularly (ICV) or intrathecally injected different doses of NCS- 382 (antagonist of GHBR) and, then, observed the effects on the sleeping time using awaken test and the pain threshold in hot-plate test (HPPT) using HPPT. RESULTS: In the awaken test, 1, 5, and 25 g of NCS-382 (ICV) significantly decreased the sleeping time of the mice treated with the three emulsified inhalation anesthetics mentioned above ( p 0.05); in con - trast, 1, 5, and 25 g of NCS-382 (intrathecally) significantly decreased the HPPT of the mice treated with emulsified inhalation anesthetics (p < 0.05 or 0.01). CONCLUSIONS: The data presented in this study suggest that GHBR may be important tar - gets for the hypnotic and analgesic effects in - duced by emulsified enflurane, isoflurane, and sevoflurane.