Effect of alcohol extract from leave Juglans regia on antinociceptive induced by morphine in formalin test

For many years, the opioid drugs, especially morphine, have a high efficiency in the mitigation of acute and chronic pains, but because they result in tolerance and addiction following long or frequent use, their administration in mitigating chronic pains has been restricted. The present study intended to use alcohol extract of juglans regia leave accompanied by morphine to increase the analgesic effect of morphine and decrease its dosage. The experiment was carried out on 70 adult male rats, weighting approximately 200-220 g. The animals were divided into seven groups, considered as control, sham and experimental groups. The experimental groups were divided into five sub-groups. The first group received 2 mg/kg of morphine, 3 groups received 2 mg/kg of morphine accompanied by alcohol extract of leave juglans regia with different doses of 0.5, 1 and 1.5 mg/kg and the last group received only 1.5 mg/kg of the alcohol extract. The drugs were injected intraperiotoneal 15 minutes before the formalin test (minute 0-5 and 15-60 were designated respectively as the acute and chronic phase of pain). Alcohol extract of walnut leave in dose of 1.5 mg/kg caused a significant nociception decrease in acute phase of formalin test and this effect was dose dependent. Moreover groups that received combination of morphine and alcohol extract showed more nociception especially in acute phase of formalin test, in comparison to the groups that received each separately and the control group (P 0.05). The leave of juglans regia has antinociceptive effect and its administration accompanied by morphine causes an increase in antinociceptive effect of morphine in acute phase.