Evaluation of the anxiolytic effect of Nepeta persica Boiss. in mice

Abstract

The aim of the present study was to evaluate the anxiolytic effects of hydroalcoholic extract (HE) of Nepeta persica Boiss. (Lamiaceae) on the elevated plus-maze (EPM) model of anxiety. The extract of arial parts of the plant was administered intraperitoneally to male NMRI mice, at various doses, 30 min before behavioural evaluation. The HE extract of N. persica at the dose of 50 mg kg(-1) significantly increased the percentage of time spent and percentage of arm entries in the open arms of the EPM. This dose of plant extract affected neither animal's locomotor activity nor ketamine-induced sleeping time. The 50 mg kg(-1) dose of the plant extract seemed to be the optimal dose in producing the anxiolytic effects, lower or higher doses of the plant produce either sedative or stimulant effects. At 100 mg kg(-1), the plant extract increased the locomotor activity. These results suggested that the extract of N. persica at dose of 50 mg kg(-1) possess anxiolytic effect with less sedative and hypnotic effects than that of diazepam and causes a non-specific stimulation at 100 mg kg(-1).

Keywords: Nepeta persica; anxiety; elevated plus-maze; sedative.

Figure 1.

Diazepam, saline and different doses of N. persica extract on (A) the percentage of time spent in the open arms and on (B) time spent in the open arms during a 5 min test in mice. Various doses of the plant, diazepam or vehicle, were injected 30 min prior to test. Data are presented as mean ± SEM for each group of nine mice. *P < 0.05 compared with vehicle-treated control. ⁺P < 0.05 compared with diazepam-treated group.

Figure 2.

Diazepam, saline and different doses of N. persica extract on (A) the percentage of entries in the open arms and on (B) entries in the open arms during a 5 min test in mice. Various doses of the plant, diazepam or vehicle, were injected 30 min prior to test. Data are presented as mean values ± SEM for each group of nine mice. *P < 0.05 compared with vehicle-treated control. ⁺P < 0.05 compared with diazepam-treated group.

Figure 3.

Diazepam, saline and different doses of N. persica extract on total number of entries in open and close arms. Various doses of the plant, diazepam or vehicle, were injected 30 min prior to test. Data are presented as mean ± SEM for each group of nine mice. *P < 0.05 compared with vehicle-treated control. ⁺P < 0.05 compared with diazepam-treated group.

Figure 4.

Diazepam, saline and different doses of N. persica extract on (A) spontaneous locomotor activity during three 5-min intervals and on (B) spontaneous locomotor activity during total 15 min. The locomotor activity counts (mean ± SEM) were measured over a 15-min period, beginning 30 min after the administration of saline, diazepam or different doses of N. persica. Data are presented as mean ± SEM for each group of six mice. *P < 0.05 compared with vehicle-treated control. ⁺P < 0.05 compared with diazepam-treated group.

Figure 5.

Diazepam and N. persica extract on (A) the latency to loss of righting reflex and (B) total sleep time. The interval between the administration of ketamin until the loss of the righting reflex was recorded as onset of sleep. The time from loss of righting reflex to regaining of the righting reflex was recorded as duration of sleep. Results represent mean ± SEM from six mice. *P < 0.05 compared with vehicle-treated control. ⁺P < 0.05 compared with diazepam-treated group.