Anxiolytic-like effects and mechanism of (-)-myrtenol: a monoterpene alcohol.

The essential oil of Myrtus communis L. (Myrtaceae) and its compounds have been popularly used in numerous health disorders, including insomnia and nervous conditions, but their effects on central nervous system (CNS) have not been explored yet. We evaluated the anxiolytic-like effects and possible action mechanism of (-)-myrtenol (MYR), a monoterpenoid alcohol present in essential oil of M. communis L. Animal models of elevated plus maze (EPM), light-dark transition (LDT), open field and rotarod tests were used in the present study. MYR was administered in male rats. Diazepam was used as the standard drug (positive control) and flumazenil was used to elucidate the possible action mechanism. The results showed that none of the doses of MYR had effect on the resistance time in rotating bar, but caused reduction in the number of falls in rotarod tests when compared with a negative control. Similarly, MYR had no effect on the number of crossings, groomings or rearings in open field tests when compared with a negative control. However, in EPM and LDT tests, MYR significantly increased (p<0.001) the number of entries in open arms (F7,49=9.867), the time spent in open arms (F7,49=53.97) and the time spent in light compartment (F7,56=27.38), when compared with negative and positive controls, respectively. Flumazenil was able to reverse the effects of diazepam and MYR. These results suggest that MYR presents anxiolytic-like activity and that effect can be mediated by GABAergic transmission.