Ephrem Engidawork, Ashenafi Girma, Asfaw Gerbi, Faiz mohammed and Girma Seyoum
Accepted Abstracts: Nat Prod Chem Res
Chewing of khat (Catha edulis F., Celastracea) is thought to produce euphoria, alertness and improve learning and memory. These effects have made the habit popular among large segment of the population in khat belt countries. Although comparative studies of amphetamine and khat on physiological and psychological behaviour are extensive, little is known about the effect of khat on learning and memory. The aim of this study was therefroe to evaluate the effect of acute, sub-acute and subchronic exposure of mice to crude khat extract on learning and memory in rodents. To this effect, animals were administered crude khat extract obtained using a mixture of chloroform and diethyl ether (1:3) orally in doses of 100, 200, 300/400 mg/kg or Tween 80 2% v/v in water for various period. Morris water maze (MWM), and multiple T-maze (MTM) paradiagms were used to obtain learning and memory parameters, including escape latency, time spent in the target quadrant and latency to reach the goal box. In addition, the effect of the extract on morphology of dentate granule cells was assessed using stereological methods. Parameters such as brain weight, volume of dentate granule cell layer, numerical density, total number and mean diameter of dentate granule cells were measured. Acute and subacute administration of khat did not have any effect on MTM and MWM tasks. Subchronic administration of khat had no appreciable effect in learning as well as longterm memory in both models. Short-term memory, however, was significantlyimpaired by 200 mg/kg (p<0.01) and 300 mg/kg (p<0.001). Whilst brain weight of khat-treated rat was found to be smaller than controls, no apparent diffrence was noted in geometrical properties of dentate granule cells between the two groups. These findings collectively indicate that khat alters only short-term memory without affecting morphological characterstics of dentate granule cells implicated in memory formation.
