Vitamin E Potentiates the Anti-nociceptive Effects by Intraperitoneal Administration of Lidocaine in Rats

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 lidocaine-induced antinociceptive effects. However, intraperitoneal injection of 0.5 g/kg of vitamin E enhanced the lidocaine-induced 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.

Doppler assessment of fetal aortic isthmus flow in twin

OBJECTIVE: The purpose of this study was to investigate the aortic isthmus (AoI) flow difference between larger fetus and smaller fetus of twin; and to evaluate the predictive value of early diagnosis of hemodynamic change in twin growth. METHODS: This prospective study on 49 pairs of twin fetuses was performed to obtain AoI blood flow data. Cases with structural or chromosomal abnormalities and co-twin death were excluded. The interval from examination to delivery was within 4 weeks and 3 cases over 4 weeks interval were re-examined. Assessment of fetal AoI Doppler parameters were peak systolic velocity (PSV), end-diastolic velocity, times-averaged maximum velocities, pulsatility index (PI), and resistance index (RI). According to the direction of the diastolic flow in the AoI, antegrade and retrograde flow were made and was used to analyze the perinatal outcomes of each fetus. The predictive value of AoI Doppler parameters in predicting fetal growth was obtained by using ANOVA and logistic regression analysis of quantitative variables in each fetus of twins. RESULTS: There were significant differences in the gestational weeks at delivery, birth weight and the incidence of growth discordance over 20% or more between monochorionic twin and dichorionic twin. The AoI PI and RI were significantly higher in smaller fetus than in larger regardless of chorionicity. Retrograde flow was noted in 8 of 98 cases (8.2%) and the only one case was of the larger fetus and the others were smaller fetuses of twin. Significant correlations were found between the AoI PI and birthweight (P=0.018) and between the PSV and growth discordance (P=0.032). In monochorionic twin, linear correlation was shown between the AoI PI and birthweight (P=0.004) and between AoI PI and growth discordance (P=0.031). Also, the meaningful correlation between the PSV and birthweight (P=0.036) was found by using logistic regression analyses. CONCLUSION: On the basis of our observation, AoI PI has revealed their hemodynamic status and this result may improve the understanding of growth patterns in twins.