Evaluation of antinociceptive and gastro protective effects of orally and inhaled administered Thevetia peruviana Pers. K. Schum essential oil

Abstract

In the present study, the antinociceptive and the gastroprotective effects of orally administered or inhaled Thevetia peruviana Pers. K. (Schum) (Oleander) volatile oil, and its principal constituents linalool and 1,8-cineole were evaluated in mice. Either when orally administered (100 µl/kg) or inhaled for 60 min, T. peruviana volatile oil significantly reduced the acetic acid-writhing response in a naloxone-sensitive manner. In the hot plate test, analgesic activity observed after oil inhalation was inhibited by naloxone and atropine sulphate pretreatment suggesting the involvement of opioidergic as well as cholinergic pathways. Regardless of the administration route and the experimental model used both linalool and 1,8-cineole did not produce significant analgesic response. Oral or inhalatory treatment with analgesic doses of volatile oil did not affect mice spontaneous locomotors activity. Concerning the gastric effects, Oleander oil, linalool and 1,8-cineole oral administration protected against acute ethanol-induced gastric ulcers but did not prevent indomethacin-induced lesions indicating no interference with arachidonic acid metabolic cascade. In conclusion, besides this gastroprotection, Oleander oil reveals an interesting analgesic activity mainly relevant after inhalation, at doses devoid of sedative side effect, suggesting the interest for potential application of this oil in aromatherapy.

Keywords: Antinociceptive activity, gastroprotection, essential oils, Thevetia peruviana, writhing test, locomotors activity, hot plate test.