Introduction: Previous studies revealed that anise (Pimpinella anisum L.) has several
pharmacological effects including analgesic, antidepressant, anxiolytic, anti-inflammatory and
antispasmodic activities. This study aimed to evaluate its effect on morphine physical dependence
in mice.
Methods: In this experimental study, 40 male NMRI mice (25-30 g) were randomly divided into 5
groups of 8. Control group received morphine and normal saline (10 mL/kg, i.p.) and other groups
received diazepam (5 mg/kg) plus one of three doses of P. anisum (50,100 or 200 mg/kg, i.p.).
Dependence was induced by administration of increasing doses (50-75 mg/kg, i.p.) of morphine. A
time of 30 minutes after naloxone injection was considered for the critical period of the withdrawal
syndrome. The number of jumps and scores of 0 to 3 were given for incidences of wet dog shakes,
teeth chattering, climbing, writing, diarrhea, grooming, and rearing during a 30-minute period.
Results: All doses of P. anisum (P<0.01) reduced the number of jumps. Additionally, all doses of the
extract reduced the behaviors of grooming (P<0.05, P<0.01 and P<0.01, respectively) and writhing
(P<0.05, P<0.001and P<0.001, respectively). None doses of the extract could reduce diarrhea
(P>0.05). Climbing, rearing and wet dog shakes reduced only by the high dose of the extract
(P<0.05). Teeth chattering reduced by 100 and 200 mg/kg of the extract (P<0.05).
Conclusion: These results obviously show that P. anisum ethanolic extract is effective in suppression
of morphine physical dependence and further studies are needed to find out the responsible
constituents and also the exact mechanisms of actions
