The Effects of Imperatorin on Anxiety and Memory-Related Behavior in Male Swiss Mice

The purpose of the reported experiments was to examine the effects of imperatorin [9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one], a bioactive furanocoumarin isolated from the fruits of Angelica archangelica (Angelica officinalis) on anxiety and memory-related behaviors of mice. Male Swiss mice were tested for anxiety and cognition, in the elevated plus maze test (EPM), using two different procedures. In the present experiments, imperatorin was administered acutely (at the doses of 5, 10, 20, 30, and 50 mg/kg); injections were made 15, 30, and 60 min before test (anxiety); 30 min before the first trial (memory acquisition); or immediately after the first trial (memory consolidation), as well as subchronically, twice a day for 6 days. On the seventh day, the mice were injected once with imperatorin (10 and 20 mg/kg, i.p.) 30 min before the test (anxiety) and 30 min before the first trial (memory acquisition), or immediately after the first trial (memory consolidation). We observed that imperatorin when administered acutely and repeatedly, at the doses of 10 and 20 mg/kg, exerted an anxiolytic effect on mice tested 30 min after the injection measured in the EPM test. By contrast, no such effect was observed after the acute administration of imperatorin at the doses of 5, 30 and 50 mg/kg. Moreover, other observations carried out 15 and 60 mm after a single injection of the drug did not reveal any effect of imperatorin on anxiety behavior in the EPM test. Furthermore, acute and repeated administration of imperatorin (10 and 20 mg/kg) improved different stages of memory processes (both acquisition and consolidation) in a modified EPM test (mEPM). The results of our research suggest imperatorin to be an interesting therapeutical option in disorders with high anxiety levels and memory impairment.