L-linalool exerts a neuroprotective action on hemiparkinsonian rats

Linalool (LIN) is a monoterpene, responsible for the aroma of essential oils in some species. It presents a sedative and anxiolytic potential, enhancing GABAergic currents and behaving as a benzodiazepine-type of drug. The objectives of the present work were to study the neuroprotective effects of LIN on a model of Parkinson's disease. For that, male Wistar rats were divided into the following groups: sham-operated (SO), 6-OHDA-lesioned, and 6-OHDA-lesioned and treated with LIN (25, 50, and 100 mg/kg, p.o.) for 2 weeks. Afterwards, the animals were subjected to behavioral tests (apomorphine-induced rotations, open field, and forced swimming tests). Then, the animals were euthanized, and the striatum, hippocampus, and prefrontal cortex were processed for neurochemistry (nitrite and lipoperoxidation measurements) and immunohistochemistry (TH and DAT) assays. The results were analyzed by ANOVA and Tukey's test for multiple comparisons and considered significant at p < 0.05. LIN significantly improved the behavioral alterations of the 6-OHDA-lesioned group, as evaluated by the apomorphine-induced rotations, open field, and forced swimming tests. In addition, LIN partially reversed the decreased DA, DOPAC, and HVA contents observed in the 6-OHDA-lesioned striatum. The untreated 6-OHDA group presented increased nitrite contents and lipoperoxidation in all the brain areas studied, and these changes were completely reversed after LIN treatments. Finally, LIN significantly prevented the reduction in TH and DAT expressions demonstrated in the right 6-OHDA-lesioned striatum. All these data strongly suggest that LIN presents a neuroprotective action in hemiparkinsonian rats, probably related to the drug anti-inflammatory and antioxidant activities.