Effect of hydroalcoholic extract of Avena sativa L. on morphine withdrawal signs in male mice

Background and Purpose: It showed that antidepressants may reduce the abuse potential of opioid. In other hand, studies showed avena sativa has antidepressant and sedative properties. So the aim of this study was to investigate the effect of ethanolic extract of Avena sativa on morphine withdrawal signs in male mice

Material and Methods: In this experimental study forty male NMRI mice [20-30 g] were randomly divided into 5 groups of 8: control groups received morphine and normal saline [10ml/kg] and other groups received ethanol [3%] and different doses of ethanolic extract of Avena sativa [50,100 and 200mg/kg] .Morphine dependency was induced using a four- day schedule method with 50, 50, 75 and 50 mg/kg dosing respectively. In fourth day 2 hours after single dose of morphine, naloxone was injected [5 mg /kg] and withdrawal signs were recorded with number of jumping and diarrhea, grooming, wet dog shake, teeth chattering, writing, climbing as scores of 0 to 3 during 30min.The data were expressed with one-way ANOVA for quantities and Mann-Whitney U test for qualities data's and they were analyzed with SPSS 15 and P values less than 0.05 were considered significant

Results: The present study findings showed that all doses of ethanolic extract_ of Avena sativa compared to control group, significantly and dose- dependently decrease the number of jumping in morphine dependent mice [56.12 +/- 6.46, 40.0 +/- 5.33 and 31.5 +/- 2.5 respectively]] P<0.05 and P<0.01 respectively].Grooming and teeth chattering also decreased with all doses of extract [P<0.05]. Wet dog shakes, climbing and rearing significantly decreased only by high doses [200mg/kg] of extract. Diarrhea also decreased with 100 and 200 mg/kg of extract [P<0.05]

Conclusion: Findings of present study showed that hydroalcoholic extract of avena sativa attenuate morphine withdrawal signs .But, Further studies need to be carried out to better understanding of their mechanism

effect of vitamin C on expression of morphine-induced conditioned place preference in male mice

Background: Dopaminergic and glutamatergic systems play a critical role in expression of morphine-induced place conditioning, while vitamin C, released from glutamatergic neurons, modulates the synaptic action of dopamine and glutamate. This study investigated the effect of vitamin C on expression of morphineinduced place conditioning in male mice

Materials and Methods: In this experimental study, 96 male NMRI mice [20-30g] were randomly divided into 12 groups of 8: control groups received normal saline [10 ml/kg] and treatment groups received morphine [2.5, 5, and 10 mg/kg] and vitamin C [1, 5, and 30 mg/kg] alone and with morphine. The study took place on six consecutive days, consisting of three phases: preconditioning, conditioning, and postconditioning. In the first set, vitamin C alone were administered in conditioning and postconditioning phases to see if they induced conditioned place preference [CPP] or aversion [CPA]. In the second set, mice received vitamin C in postconditioning phase after conditioning with morphine

Results: Different doses of morphine [5 and 10 mg/kg, p<0.001] induced CPP [112.06 +/- 14.44 and 128.65 +/- 16.12 sec, respectively] compared to control group [?9.34 +/- 2.04 sec]. Different doses of vitamin C alone did not induce any significant CPP or CPA. However, coadministration of vitamin C [5 and 30 mg/kg; p<0.01 and p<0.001, respectively] with morphine [5 mg/kg] significantly induced morphine-like CPP [80.4 +/- 9.61 and 56.45 +/- 13.52 sec, respectively]

Conclusion: Low doses of vitamin C induced morphine-like CPP probably by agonistic action on dopaminergic and glutamatergic systems. Therefore, this vitamin may be useful for controlling compulsive drug-seeking behavior in morphine addicts

[ effect of concurrent injection of amantadine and paroxetine on positive reinforcing effect of morphine in conditioned place preference[CPP] model in mice]

Increased level of dopamine in accumbens nucleus has a key role in the rewarding effects or positive reinforcement of abused drugs, whereas serotonin facilitates dopamine release in brain .The aim of this study was to investigate the effect of concurrent use of amantadine and paroxetine on reinforcing effect of morphine in conditioned place preference model in mice. In this experimental study male NMRI mice [20-30 g] were used within 6 consecutive days including preconditioning, conditioning and postconditioning phases. On the first day, after removal of the partitions, time spent in every 3 compartments was measured for 10 minutes. After determination of low and high preferred side, animals received morphine sulfate [5 mg/kg] intraperitoneally on the 2nd and 4th days in the least preferred side, but on the 3rd and 5th days of the test, animals received saline [10ml/kg] in high preferred side. On the test day or postconditioning phase, animals received amantadine, and paroxetine alone or their concurrent does, instead of morphine. Control group received saline in both sides [n = 8]. Our results show that morphine significantly and dose dependently [2.5, 5,10 mg/kg] induced CPP [P<0.001]. Amantadine, only in doses of 5 and 10 mg /kg [P<0.01, P<0.001, respectively] induced CPP. Paroxetine induced CPP in all doses. Concurrent use of amantadine[10mg/kg] and paroxetine [10mg/kg] significantly enhances morphine - like CPP [P <0.001]. Concurrent use of drugs, releases dopamine and inhibit reuptake of serotonin, and may potentiate morphine-like CPP and could be useful in decreasing some opioid withdrawal signs