Full Length Research Paper

Effect of single and daily khat (Catha edulis) extract on locomotor behaviour in CBA mice

Samuel T. Kimani^{1, 2}*, Nilesh B. Patel¹ and Paul G. Kioy¹

¹Department of Medical Physiology, University of Nairobi, P. O BOX 30197, Nairobi, Kenya.

²School of Nursing Sciences, University of Nairobi, P. O BOX 19676, Nairobi, Kenya.

*Corresponding author. E-mail: tkimani@uonbi.ac.ke.  Tel: +254 20 2711250.

Accepted 2 May, 2008

   Abstract

It has been demonstrated that administration of cathinone is capable of increasing locomotor activity in animals. The present study was carried out with a psychostimulant Catha edulis extract. In this experiment, twenty CBA male mice, weighing 20 to 30 g, 5 to 6 weeks old were injected intraperitoneally with a single dose khat extract. Thereafter, they were continued to be injected daily with single daily khat extract for seventeen (17) days. The animals were divided into one controls group (injected 0.5 ml normal saline) and three experimental groups (injected 40, 120 and 360) mg/kg body weight khat extract, respectively. The animals were then submitted to open field task performance. Line crossings, centre square and rearing frequency were observed at 5 min block interval for 55 min. Single high dose (360 mg/kg) body weight khat extract significantly (P < 0.001) enhanced the line crossing in CBA mice. However, single low khat extract (40 and 120 mg/kg body weight) dose had no effect on the line crossing. On the other hand, single khat extract doses (40, 120 and 360 mg/kg) body weight significantly (P < 0.001) inhibited the centre square and rearing frequencies in CBA mice. Generally, single daily khat extract (40, 120 and 360 mg/kg) body weight treated CBA mice had significantly (P < 0.001) higher line crossings than control and single dose treated animals. The centre square and rearing frequencies were significantly higher (P < 0.05) in CBA mice injected with single daily doses of khat than the single dose treated group. However, mice treated with single daily doses (40, 120 and 360) mg/kg body weight khat extract had significantly (P < 0.05) lower rearing frequency than the control. Mice treated with 40 mg/kg b.wt single daily khat extract had higher (P < 0.05) centre square frequency than the control and mice injected with 120 and 360 mg/kg body weight khat extract. We demonstrate that repeated single daily khat causes behavioral sensitization, affecting both locomotor and anxiety behaviours.

Key words: Locomotor activity, behavioural sensitization, khat, CBA mice, single and repeated daily dose, line crossing, centre square frequency, rearing frequency..