The present study was to evaluate effects of vitamin E on intravenous administration of lidocaine-induced antinociception. Experiments were carried out using male Sprague-Dawley rats. Orofacial formalin-induced nociceptive behavioral responses were used as the orofacial animal pain model. Subcutaneous injection of formalin produced significant nociceptive scratching behavior. Intraperitoneal injection of 5 and 10 mg/kg of lidocaine attenuated formalin-induced nociceptive behavior in the 2nd phase, compared to the vehicle-treated group. Intraperitoneal injection of 1 g/kg of vitamin E also attenuated the formalin-induced nociceptive behavior in the 2nd phase, compared to the vehicle-treated group. However, low dose of vitamin E (0.5 g/kg) did not affect the nociceptive behavioral responses produced by subcutaneous injection of formalin. The present study also investigated effects of intraperitoneal injection of both vitamin E and lidocaine on orofacial formalin-induced behavioral responses. Vehicle treatment affected neither formalin-induced behavioral responses nor lidocaineinduced antinociceptive effects. However, intraperitoneal injection of 0.5 g/kg of vitamin E enhanced the lidocaineinduced antinociceptive effects in the 2nd phase compared to the vehicle-treated group. Intraperitoneal injection of naloxone, an opioid receptor antagonist, did not affect antinociception produced by intraperitoneal injections of both vitamin E and lidocaine. These results suggest that treatment with vitamin E enhances the systemic treatment with lidocaine-induced antinociception and reduces side effects when systemically treated with lidocaine. Therefore, the combined treatment with vitamin E and lidocaine is a potential therapeutic for chronic orofacial pain.

Optimum concentrations of anesthetic clove oil and anesthetic lidocaine-HCl were determined for a species of adult marine medaka, Oryzias dancena, over a range of salinity conditions, and investigated in a transport simulation experiment by analyzing various water and physiological parameters. Research indicated that the higher the concentration of anesthetic at each salinity, the shorter the anesthesia time at each salinity. At each concentration, fish were anesthetized slower at water salinities over 10 ppt (P<0.05). Anesthesia time at 10 ppt was faster than any other salinity. In 10 ppt salinity, the dissolved oxygen (DO) concentrations and respiratory frequencies of the clove-oil-administered groups decreased until 48 hours (P<0.05), whereas the NH4 + and CO2 concentrations increased until 48 hours (P<0.05). In same period, the DO, NH4 +, and CO2 concentrations and respiratory frequencies all decreased as the clove oil concentration increased (P<0.05). The trends in the DO, NH4 +, and CO2 concentrations and respiratory frequencies in the lidocaine-HCl-administered groups were similar to those in the clove-oil-administered groups. In conclusion, clove oil and lidocaine-HCl are effective anesthetics, improving the transportation of the marine medaka. The results from this study will contribute to safe laboratory handling of the marine medaka, which are commonly required by many research studies and experiments.