[ effect of carbenoxolone on morphine-induced withdrawal symptoms in rats]

The exact mechanisms of morphine dependence and withdrawal syndrome remain unclear. Many studies have been performed to find a drug for prevention of withdrawal syndrome. The aim of this study was to evaluate the effect of carbenoxolone [a gap junction inhibitor] on morphine withdrawal syndrome in male rats. In this experimental study, adult male Sprague Dawley rats with weights between 225 and 275 g were selected randomly and divided into 8 groups. Each group consisted of 8 rats. In order to induce dependency, morphine was injected subcutaneously for nine days [1[st] day: 5mg/kg, 2[nd] and 3[rd] days: 10 mg/kg, 4[th] and 5[th] days: 15 mg/kg, 6[th] and 7[th] days: 20 mg/kg, 8[th] and 9[th] days: 25 mg/kg]. On the ninth day only the morning dose of morphine was injected, then control group and treatment groups received IP injection of saline [1 ml/kg] and IP injection of carbenoxolone [5, 25, 50, 100 mg/kg] respectively. After 30 min all groups received IP injection of naloxone [4 mg/kg] and the withdrawal signs including: jumping, rearing, genital grooming, abdominal writhing, body grooming and wet dog shake, were recorded for 60 minutes. Our results showed that carbenoxolone not only decreased all withdrawal signs, but also reduced the total withdrawal scores, significantly. In conclusion we found that carbenoxolone as a gap junction inhibitor was effective in decreasing the symptoms of morphine withdrawal syndrome.

[Evaluation of the analgesic and anti-inflammatory effects of aqueous extract of peppermint [Mentha piperita]]

The aim of this study was to investigate the analgesic and anti-inflammatory effects of aqueous extract of mint plant which has been used in folk medicine as a pain reliever. In this experimental study, male NMRI mice received intra-peritoneal injections of peppermint extract with different doses of 20,40,60,90 and 120mg/kg. Then anti-inflammatory and analgesic effects of peppermint were determined by using formaldehyde and xylene tests. Anova and Tukey test were used for data analysis. All doses of peppermint extract showed significant anti-inflammatory effect on the ear inflammation induced by xylene in comparison to the control group [p<0.05]. Doses of 40, 60, 90, 120 mg/ kg significantly reduced the pain [p<0.05], but the group treated with the dose of 20mg/kg showed no significant reduction of the pain. The results of this study are indicative of anti-inflammatory and analgesic effects of peppermint. We recommend further studies on this subject in the future.

[ effect of donepezil on morphine-induced withdrawal syndrome in rats]

Long-term exposure to opiates induces physical and psychological dependency. Despite a large number of studies on this subject, cellular mechanism involved in this phenomenon is not yet exactly clear. In this study, we investigated the effects of donepezil, an acetylcholine esterase inhibitor, on morphin-induced withdrawal symptoms in rats. In this experimental study,6 groups of male Sprague Dawly rats weighting between 225 and 300 g, received 10 mg/kg, ip morphine/ day in addition to 1 ml/kg,ip saline or 0.5, 1 and 1.5 mg/kg, ip donepezil. In order to induce dependency, morphine was administered subcutaneously every 12 hours for nine days. On the ninth day, 30 minutes after the last dose of morphine, control groups received 1 ml/kg, ip saline and experimental groups received ip donepezil. After 30 min, naloxone [4 mg/kg, ip] were administered for all groups and the withdrawal symptoms including: jumping, rearing, genital grooming, abdomen writhing, body grooming and wet dog shake, were recorded for 60 minutes. Our results showed that donepezil decreased withdrawal symptoms, also it could attenuate the total withdrawal score, significantly. The results of this study showed that donepezil as an acetylcholine esterase inhibitor, could decrease withdrawal symptoms in rats