Lavandula angustifolia Essential Oil and Linalool Counteract Social Aversion Induced by Social Defeat

Abstract

Many vegetable extracts, essential oils, and their main constituents are active on the Central Nervous System (CNS). In fact, they have been used as sedatives, hypnotics, or tranquilizers for their activity in treating CNS disorders. In this research, we studied the possible activities of Lavandula angustifolia (LA) essential oil and of its main constituent, linalool, as anti-stress compounds on anxiety and social interaction and their in vitro effects on proteins (pERK and PKA) involved in the transmission of the signal. An acute intraperitoneal injection of linalool (100 mg/kg) and of LA essential oil (200 mg/kg) reduced motor activity without any anxiolytic effect, but significantly increased social interaction. Stressed mice, after being exposed to a social defeat encounter, showed heightened anxiety and social avoidance. Acute administration of LA essential oil blocked stress-induced anxiety, while linalool showed no effects. However, both compounds were capable of reversing social aversion, acting as antidepressant agents. Our results showed that linalool inhibits pERK and PKA expression in the SH-SY5Y cell, but no effect was detected with the LA essential oil. Therefore, the LA essential oil and linalool may be considered as useful alternative tools to the available traditional treatments for social stress-induced mental illnesses.

Keywords: Lavandula angustifolia; essential oil; linalool; social defeat.

Figure 1

Effects of linalool (100 mg/kg) and Lavandula angustifolia (LA) essential oil (200 mg/kg) in the open field test. (A) Effects on the distance travelled (cm) by mice; (B) Effects on the velocity (cm/s) of mice. The bars represent the mean ±SEM of animals in the different treatment groups. ** p < 0.01 significant difference compared to control.

Figure 2

Effects of linalool and LA essential oil acute administration in the elevated plus maze (EPM) test. Animals were divided into the following three treatment groups: Control (saline) (n = 15), Linalool (n = 15) and LA essential oil (n = 15). Results are presented as mean values ±SEM. (A) Entries in closed arms. * p < 0.05; ** p < 0.01 differences with the control group. (B) Total entries. * p < 0.05 difference with the control group.

Figure 3

Representative Western blot (A) and relative expression levels of the PKA (B) and pERK (C) in SH-SY5Y cells treated with linalool. Values are the mean ± SD in each group (n = 3). * p < 0.05, ** p < 0.01, *** p < 0.001, compared to the control (ANOVA followed by Dunnett’s multiple comparison test).