The effect of Khat (Catha edulis) as an appetite suppressant is independent of ghrelin and PYY secretion

Background: The leaves of the khat plant (Catha edulis) are chewed for their pleasurable effects. Chewing releases cathinone which may decrease appetite through an unknown mechanism. Levels of the peptide ghrelin increase with hunger and decrease immediately post-prandially, while peptide YY is released following a meal. We hypothesised that the anorexigenic effects of khat may be mediated through changes in these hormones. Materials and methods: Six habitual khat chewers attended on two separate occasions. For a period of 3 h they chewed either khat leaves or lettuce. Blood pressure (BP) and pulse rate (PR) were monitored throughout, as were subjective assessments of hunger and fullness. Plasma samples were analysed for cathinone, ghrelin and PYY levels. Results: Chewing khat significantly decreased subjective feelings of hunger and increased fullness (p < 0.05) but had no effect on ghrelin and PYY levels. Khat led to an increase in cathinone levels as well as an increase in BP and PR. Cathinone levels correlated positively with fullness and pulse rate and negatively with hunger. Conclusions: Chewing khat decreases subjective feelings of hunger and increases systemic sympathetic tone, but has no effect on ghrelin and PYY levels. We conclude that the anorexigenic effect of khat may be secondary to central mechanisms mediated via cathinone. (C) 2008 Elsevier Ltd. All rights reserved.