ABSTRACT
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