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Background & aim: Morphine dependence is a compulsive pattern of drug taking, resulting from the positive reinforcement of the rewarding effects of drug taking and the negative reinforcement of withdrawal syndrome that accompanies the cessation of drug taking. The objective of this study was to investigate the effect of ethanol extract of aerial parts of the Mentha piperita in the acquisition, tolerance expression and dependence to morphine in adult male mice Methods: In the present study, 75 NMRI mice were divided into fifiteen groups. The Hot-plate test was used to survey the morphine activity. Morphine was injected (2.5, 5, 10, 20, 40 mg/kg, i.p.) twice daily for seven days, except in 8th day in which morphine was administrated at a single dose (50 mg/kg). The extract (50, 75, 100 mg/kg) was injected for eight days. The control animals were intact, and sham animals only received morphine. Naloxone was injected (10 mg/kg) five hours after the final dose of morphine and the withdrawal signs were recorded during a 30 minute period. The data were expressed as mean values ± SEM and tested, using analysis of one-way ANOVA test. Results: Peppermint extract at doses of 75 and 100 kg significantly improved the tolerance expression and dependence to morphine in animals and significantly reduced the symptoms of withdrawal. Conclusion: Peppermint extract was commuted morphine tolerance and dependence in mice.The plant contained component(s) that alleviate morphine withdrawal syndrome. The extract possibly be effective in improving tolerance to morphine.

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Background & aim: Angiotensin II plays a key role in body fluid homeostasis. In the present study, the interaction of i.c.v. injection of morphine, heroin and losartan’s material, opioidergic and angiotensinergic systems on water intake in male rabbits were investigated. Methods: In the present experimental study, sixty-five male rabbits were divided into eight groups as follows: a control group without operation, control with surgical accompanying with cannula, the control surgery and cannulated with a saline injection, morphine (at doses of 5, 10 and 20 mg rabbit kg), heroin group (2.5, 5 and 10 mg/kg rabbit), losartan group (45, 90 and 180 mg kg rabbit), losartan (90 mg/kg rabbit) with morphine (5/10 kg rabbit), losartan (90 mg kg) and heroin (2.5 and 5 mg kg rabbits) were received. A cannula was used to ICV treatment in the right lateral ventricle of rabbits. After recovering the animals were deprived of water for 24 hours. The different drugs injected and the amount of drinking water was measured for one hour was measured. The gathered data were analyzed using one-way ANOVA and Tukey test. Result: The results showed that Morphine (agonist of opioid’s receptor, 10 µg/rabbit), Heroin (agonist of opioid’s receptor, 5 µg/rabbit), Losartan (antagonist of Angiotensin II receptor, 90 µg/rabbit) decreased water intake. Blockade of Angiotensin II with losartan, attenuate the inhibitory effect of Morphin and Heroin. Renin- Angiotensin System can regulate water intake via its effect on vasoconstriction and secretion of AVP and Aldestrone. All of these effects will be blocked with Angiotensin II antagonist (losartan). Conclusion: The Opioidergic system was influential in the adjustment of water and electrolyte balance through affecting peripheral and central receptors. The role of the Opioidergic system in regulation of drinking mechanisms was related to the secretion of Antiduretic hormone. According to the obtained results, a marked correlation was seen between angiogenesis systems, Opioidergic system and morphine (opioid) on water intake.