Abstract

Background: The prevalance of opioid addiction is releativly high in Iran. Since the mechanism (s) of opioid addiction are not clear, this social problem is still remained unresolved. In the present study, the effects of water extract of Crocus sativus on the acquisition and expression of morphine-induced behavioral sensitization in female N-MARI mice (20-25 g) are investigated. Methods: Sensitization was induced by single injection of morphine (5 mg/kg) for three consecutive days followed by five days resting. On the 9th day of the experiments, the sensitization was assessed in animals by a single injection of very low dose of morphine (0.5 mg/kg). The extract of the C. sativus was administered during or after induction of morphine sensitization. Then, the sensitization were tested in the animals. In order to evaluate the effects of the drugs on locomotor activity, morphine and the extract were administered to the animal in a pilot study. Results: Our findings show that administration of morphine (0.5, 5 and 50 mg/kg), induced a significant activity in animals. The increament was significant for the dose 50 mg/kg of morphine. On the other hand, administration of the plant extract (10, 50 and 100 mg/kg) also produced a significant hyperactivity and hypoactivity in the animals. Preadministration of the animals by extract (10, 50 and 100 mg/kg, i.p.) reduced morphine effects. Injection of the same extract (10, 50 and 100 mg/kg) 30 min before the morphine (5 mg/kg) administration in the training days, caused a significant decrease in locomotor activity in animals, i.e. reduced the acquisition of morphine-induced behavioral sensitization. Injection of the plant extract (10, 50 and 100 mg/kg) in the test day, 30 min before morphine (0.5 mg/kg) administration also reduced the locomotor activity in the animals, i.e. reduced the expression of morphine-induced behavioral sensitization. Conclusion: It can be concluded that the extract of C sativus may inhibit morphine-induced hyperactivity and also acquisition and expression of morphine-induced behavioral sensitization in female mice which could be also usefull in human.