The Effects of Crocus sativus Extract on the Acquisition and Expression of Morphine-Induced Conditioned Place Preference in Mice

The effects of Crocus sativus (Saffron) on the euphoric properties of morphine have not yet been studied. In the present study, the effects of water extract of C. sativus stigma on the acquisition and expression of morphine-induced Conditioned Place Preference (CPP) in male N-MARI mice (weighted 20-25 g) were investigated. This experimental study was conducted on 136 male mice that were divided into 17 groups (n=8/group). In a pilot study, different doses of morphine (1, 2, 4 and 8 mg/kg) and C. sativus extract (10, 50 and 100 mg/kg) were injected to the animals, to evaluate the drugs ability in induction of place preference. In the second phase of the experiments, the extract of the C. sativus was administered during or after induction of morphine CPP. Then, CPP were tested in the animals. One-way analysis of variance (ANOVA) was performed for statistical procedure. Administration of morphine (1, 2, 4 and 8 mg/kg), increased the required time in the compartment paired with morphine (i.e. CPP) that was significant (p<0.001) for those animals that received 4 and 8 mg/kg of morphine. Administration of the plant extract (50 mg/kg) also produced a significant CPP (p<0.01) compared with control group. Injection of the same dose of the extract before morphine (8 mg/kg) administration, caused a decrease in the time spent in drug-paired side only in dose of 100 mg/kg of the extract (p<0.05). In addition, injection of the plant extract in the test days to the animals, which reveived morphine (8 mg/kg) in the conditioning days, enhanced the expression of morphine CPP in the animals, that was statisticaly significant for the extract at the concentration of 50 mg/kg (p<0.05). It could be concluded that injection of the extract of C. sativus can inhibit the acquisition but enhanced the expression of morphine-induced CPP. In addition, the extract can produce CPP by itself.