Anxiolytic-Like Effect of Methanol Leaf Extract of Laggera aurita Linn. F. (Asteraceae) in Mice

Idris Aliyu Guragi; Hadiza Kyari; Sani Malami

doi:10.5812/archneurosci.63441

Anxiolytic-Like Effect of Methanol Leaf Extract of Laggera aurita Linn. F. (Asteraceae) in Mice

authors:

Idris Aliyu Guragi ¹ , Hadiza Kyari ² , Sani Malami ^{1
, *}

1 Department of Pharmacology and Therapeutics, Bayero University, Kano, Nigeria

2 Department of Pharmacology and Therapeutics, Ahmadu Bello University, Zaria, Nigeria

how to cite: Guragi I A, Kyari H, Malami S. Anxiolytic-Like Effect of Methanol Leaf Extract of Laggera aurita Linn. F. (Asteraceae) in Mice. Arch Neurosci. 2018;5(2):e63441. https://doi.org/10.5812/archneurosci.63441.

Abstract

Background:

Laggera aurita belongs to the Asteraceae family; it is an annual herb found growing as weeds in Sub-Saharan Africa, including Nigeria. In Nigeria, Laggera aurita is used as a remedy for paediatric malaria and in the management of epilepsy. Previous studies on extracts of this plant suggested its anticonvulsant activity via GABA-mediated neurotransmission. Therefore, this study aimed at evaluating anxiolytic-like effect of the plant extract.

Methods:

Anxiolytic potential of the methanol leaf extract of Laggera aurita was evaluated using staircase, elevated plus maze, hole board, open field, beam walking assay, and diazepam-induced sleep tests.

Results:

The extract significantly (P < 0.05) decreased the number of rearing in the staircase test at 600 and 300 mg/kg. In the elevated plus maze test, there was a significant (P < 0.05 at 600 and 300 mg/kg) increase in the total number of open arm entries and total time spent in the open arms (600 mg/kg). In the hole board test, the extract significantly (P ≤ 0.05 at 600mg/kg) decreased the number of head dips. Using the open field test, the axiolytic activity of the extract was further reflected by the significant (P < 0.05) decrease in the number of rearing (150, 300, and 600 mg/kg). The effect of the extract on beam walking assay showed a significant (P < 0.05) increase (600 mg/kg) in number of foot slips and time spent on beam. The extract (600 mg/kg) significantly (P < 0.05) increased the duration of sleep induced by diazepam.

Conclusions:

The results of this study revealed that the leaf extract of Laggera aurita possesses anxiolytic-like properties.

Keywords

Anxiolytic Rearing Diazepam Laggera aurita

1. Background

Anxiety disorders are the most prevalent class of mental disorders and have posed a substantial public health burden (1). These disorders are regarded as a global health burden, affecting a large population (2, 3). Nigerians are the most affected in Africa with over 5 million patients with anxiety disorder (4). The common medicines for anxiety disorders are benzodiazepines and antidepressants (5, 6). However, side effects, such as psychomotor impairment, decreased alertness, sexual dysfunction, reliance liability, and potentiating activity of other sedatives, have limited their use (7).

Laggera aurita Linn (Asteraceae) is native to Sub-Saharan Africa and is a herbaceous plant found growing as a weed in Nigeria (8). Essential oils from the plant of L. aurita are used for the treatment of different diseases, such as cancer, atherosclerosis, and thrombosis (9). Anticonvulsant activity (10), anti-inflammatory and analgesic activity (11), antiviral, antibacterial and hepatoprotective properties (12), and antinociceptive properties (13), have been reported by previous studies. The traditional use of the plant in epilepsy (10) and paediatric malaria have also been reported (14). This study aimed at establishing the anxiolytic property of methanol leaf extract of Laggera aurita (LAME).

2. Methods

2.1. Drugs and Equipment

Diazepam (Roche Product Ltd.), methanol (Sigma-Aldrich, St.Louis U.S.A.), stair case apparatus, elevated plus maze apparatus, hole board apparatus, open field apparatus and beam walk apparatus were the drugs and material used in this study.

2.2. Preparation of Plant Material

The leaves of Laggera aurita Lam were collected in March 2017, from Kakiyaye village, Zaria, Nigeria. The plant was identified by Mallam Baha’uddeen of the herbarium unit, department of plant biology, Bayero University Kano. A voucher specimen number (BUKHAN 0138) was collected for future reference. The sample was washed, dried under shade, pound using mortar, and pestle into coarse powder. A portion (1250 g) of the powdered leaves was cold-macerated in methanol (2.5 Litres) for 5 days. The solvent was decanted in an evaporating dish and evaporated to dryness over a water bath, maintained at about 40°C. The dried methanol leaf extract of Laggera aurita was stored in an air-tight container. The solutions of the extract were always freshly prepared for each study by dissolution of the appropriate amount required in distilled water.

2.3. Animas

Adult Swiss albino mice of both genders (16 to 22 g) were obtained from the department of pharmacology, Bayero University, Kano, Nigeria. They were maintained under standard experimental conditions with access to animal feeds (Excel Feeds Plc, Kaduna, Nigeria) and water. All experiments performed were in accordance with the Bayero University research policy guidelines on use and care of animals.

2.4. Experimental Groupings and Treatments

Mice were randomly grouped to 5 groups of 6 mice each. Group 1 served as the control group and was treated with distilled water (10 mL/kg); groups 2, 3, and 4 were treated with the extract at 600, 300, and 150 mg/kg, respectively, while those in group 5 received diazepam at either 0.5 or 1 mg/kg, except in the diazepam-induced sleep experiment. Treatments were via the Intraperitoneal route (i.p) and observation period for recording the behavioural episodes was 30 minutes post treatment in each experiment.

2.5. Staircase Test

The method was adopted as described by Simiand et al. (15). The staircase is composed of 5 identical steps, 2.5 cm high, 10 cm wide, and 7.5 cm deep. Mice were placed individually on the floor of the box with their back to the staircase. The number of steps climbed and the number of rearing were counted over a 5-minute period.

2.6. Elevated Plus Maze Test (EPM)

This method was described by Pellow and File (16). It consists of 2 open arms (35 × 5 cm) crossed with 2 closed arms (35 × 5 × 20 cm) elevated about 25 cm in a dimly illuminated room. Mice were placed individually in the centre of the EPM, facing a closed arm. The time spent in both the open and closed arms were recorded for 5 minutes and the numbers of entries into the open and closed arms were also counted. An entry was regarded as when all 4 paws are within the arm. Increase in the open arm exploration time was regarded as anxiolysis.

2.7. Hole-Board Test for Exploratory Behaviour

This study was described by Sonavane et al. (17). It was conducted using a wooden board measuring 20 cm by 40 cm with 16 evenly spaced holes. Individual mice were placed on the board and allowed to explore, the number of times each mouse dipped its head into the holes to the level of eyes was counted during a 5-minute period. Anxiolytic compounds were considered to increase the number of head dips.

2.8. Open Field Test

Open Field Test, as described by Kulkarni and Reddy (18), was adopted. It is a floor of half square meter divided to a series of 25 squares, each alternatively coloured black and white with a 40-cm height wall. Numbers of squares travelled, time spent at the central square, and the number of rearing by the animals were counted for 5 minutes. Number of squares travelled, number of rearing, and time spent at the central square were observed and recorded.

2.9. Beam Walk Assay of Motor Coordination Deficit

This method was carried out as described by Stanley et al. (19). The beam was made of wood 8-mm in diameter, 60 cm long, and elevated 30 cm above the bench by metal supports. Adult mice were trained to walk from a start platform along a ruler (80 cm long and 3 cm wide) elevated 30 cm above the bench by a metal support to a goal box. Each mouse was placed on the beam at one end and allowed to walk to the goal box. Mice that fell were returned to the position they fell from, with a maximum time of 60 seconds allowed on the beam. The indices recorded for each mouse were time spent while crossing the beam and the number of foot slips.

2.10. Diazepam-Induced Sleep Test

The method was adopted as described by Rakotonirina et al. (20). Mice were divided to 4 groups of 6 mice each and received different treatments. Group 1 were treated with distilled water (10 mL/kg, IP) while groups 2, 3, and 4 were treated with 3 doses of the plant extracts at 600, 300, and 150 mg/kg, respectively. Thirty minutes post treatment, each group received diazepam at a dose of 20 mg/kg (IP) and the sleep potentiating effects of the plant extract was studied. The onset and duration of sleep were recorded. Loss of righting reflex was described as the onset of sleep while the time between the loss and regaining of the righting reflex was regarded as duration of sleep.

2.12. Statistical Analysis

Data analysis was conducted using one-way analysis of variance (ANOVA) followed by Dunnett’s post-hoc test (SPSS Version 20). Values obtained were expressed as mean ± standard error of the mean (SEM) and differences were considered at P ≤ 0.05.

3. Results

The extract showed a decrease in the number of steps climbed at all the doses (600, 300, and 150 mg/kg). There was also decreased number of rearing at all doses yet was significant (P < 0.05) at doses 600 and 300 mg/kg (Table 1).

Table 1.