In humans, the cephalic phase response to food ingestion consists mostly of vagal efferent activation, which promotes the secretion of entero-pancreatic hormones, including ghrelin. Since symptomatic patients with bulimia nervosa (BN) are characterized by increased vagal tone, we hypothesized an enhanced ghrelin secretion in the cephalic phase of vagal stimulation. Therefore, we investigated ghrelin response to modified sham feeding (MSF) in both BN and healthy women.
Six drug-free BN women and 7 age-matched healthy females underwent MSF with initially seeing and smelling a meal, and then chewing the food without swallowing it. Blood samples were drawn immediately before and after MSF for hormone assay.
Circulating ghrelin increased after MSF in both groups with BN individuals exhibiting a greater ghrelin increase, which positively correlated with the patients’ weekly frequency of binge-purging.
These results show for the first time an increased ghrelin secretion in the cephalic phase of vagal stimulation in symptomatic BN patients, likely resulting in a potentiation of the peripheral hunger signal, which might contribute to their aberrant binge-purging behavior.
Bulimia nervosa (BN) is an eating disorder characterized by eating-related psychopathology resulting in episodes of massive food ingestion, followed by vomiting, prolonged periods of starvation, and other compensatory behaviors aiming to reduce energy intake or to increase its expenditure, generally with no pathological change in BW. Recent studies reported a derangement in the secretion of some gastro-entero-pancreatic hormones in response to food intake in symptomatic BN women and such alterations have been hypothesized to play a role in promoting and/or maintaining the patients’ aberrant eating behaviors (Monteleone et al., 2008a). For instance, the food-induced increase of plasma levels of peptide YY and cholecystokinin have been found to be reduced and/or delayed in symptomatic bulimic patients (Monteleone et al., 2005, Kojima et al., 2005 and Keel et al., 2007) while the post-prandial ghrelin secretion has been reported to be blunted (Monteleone et al., 2005 and Kojima et al., 2005). The physiological increase in circulating ghrelin occurring before the consumption of a meal, that is in the preabsorptive cephalic phase of food ingestion, has never been investigated in BN.
In humans, the preabsorptive cephalic phase response consists mostly of vagal efferent activation and concomitant release of some gastro-entero-pancreatic hormones, including the orexigenic ghrelin (Feldman and Richardson, 1986). BN patients have been shown to be characterized by an increased peripheral vagal activity resulting mainly in decreased hearth rate variability, bradycardia and increased somatic pain threshold (de Zwaan et al., 1996, Rissanen et al., 1998 and Murialdo et al., 2007). Based on this background, we hypothesized that, because of their vagal hyperactivity symptomatic BN individuals should exhibit an enhanced secretion of ghrelin in the cephalic phase of vagal stimulation.
The cephalic phase of vagal stimulation may be assessed by using a modified sham feeding (MSF) technique, where a subject thinks about a meal, smells a meal and chews a meal without actually swallowing the meal (Robertson et al., 2001). Therefore, we investigated the ghrelin response to a sham feeding condition in symptomatic women with BN as compared to age-matched healthy controls, and assessed relationships between hormone responses and subjects’ eating behavior.
