Antidepressant and anxiolytic activity of Lavandula officinalis aerial parts hydroalcoholic extract in scopolamine-treated rats

Abstract

Context: Anxiety and depression are common in Alzheimer's disease (AD). Despite some evidence, it is difficult to confirm Lavandula officinalis Chaix ex Vill (Lamiaceae) as an anxiolytic and antidepressant drug.

Objective: The effects of L. officinalis extract were studied in scopolamine-induced memory impairment, anxiety and depression-like behaviour.

Materials and methods: Male NMRI rats were divided into control, scopolamine alone-treated group received scopolamine (0.1 mg/kg) intraperitoneally (i.p.), daily and 30 min prior to performing behavioural testing on test day, for 12 continuous days and extract pretreated groups received aerial parts hydro alcoholic extract (i.p.) (100, 200 and 400 mg/kg), 30 min before each scopolamine injection. Memory impairment was assessed by Y-maze task, while, elevated plus maze and forced swimming test were used to measure anxiolytic and antidepressive-like activity.

Results: Spontaneous alternation percentage in Y maze is reduced by scopolamine (36.42 ± 2.60) (p ≤ 0.001), whereas lavender (200 and 400 mg/kg) enhanced it (83.12 ± 5.20 and 95 ± 11.08, respectively) (p ≤ 0.05). Also, lavender pretreatment in 200 and 400 mg/kg enhanced time spent on the open arms (15.4 ± 3.37 and 32.1 ± 3.46, respectively) (p ≤ 0.001). On the contrary, while immobility time was enhanced by scopolamine (296 ± 4.70), 100, 200 and 400 mg/kg lavender reduced it (193.88 ± 22.42, 73.3 ± 8.25 and 35.2 ± 4.22, respectively) in a dose-dependent manner (p ≤ 0.001).

Discussion and conclusion: Lavender extracts improved scopolamine-induced memory impairment and also reduced anxiety and depression-like behaviour in a dose-dependent manner.

Keywords: Memory impairment; Y maze; anxiety; depression; elevated plus maze; forced swimming.

Figure 1.

Effects of the scopolamine alone treatment and Lavandula officinalis extract pretreatment in different doses, on spontaneous alternation percentage in Y maze. Values are means ± SEM (n = 10 animals per group), #p ≤ 0.001 in compared with the control group. For post hoc analysis: Lav 200 + Sco and Lav400 + Sco versus Sco: *p ≤ 0.05. Sco: scopolamine; Lav: L. officinalis. Effects of the scopolamine alone treatment and L. officinalis extract pretreatment in different doses, on spontaneous alternation percentage in Y maze.

Figure 2.

Effects of the scopolamine alone treatment and Lavandula officinalis extract pretreatment in different doses, on time spent on the open arms in elevated plus maze task. Values are means ± SEM (n = 10 animals per group), *p ≤ 0.001 in compared with control and scopolamine groups. For post hoc analysis: Lav 200 + Sco versus Lav400 + Sco: $p ≤ 0.05. Sco: scopolamine; Lav: L. officinalis. Effects of the scopolamine alone treatment and L. officinalis extract pretreatment in different doses, on time spent on the open arms in elevated plus maze task.

Figure 3.

Effects of the scopolamine alone treatment and Lavandula officinalis extract pretreatment in different doses, on immobility time in forced swimming test. Values are means ± SEM (n = 10 animals per group), *p ≤ 0.001 in compared with the control group, $p ≤ 0.05 in compared with the scopolamine group and #p ≤ 0.05 in compared with 100 mg/kg lavender extract. Sco: scopolamine; Lav: L. officinalis. Effects of the scopolamine alone treatment and L. officinalis extract pretreatment in different doses, on immobility time in forced swimming test.