Effect of peptide YY (PYY) on food-associated conflict.

Peptide YY (PYY) administered centrally in rats induces powerful overeating. PYY also occurs endogenously in humans and is elevated in abstaining bulimic patients. To examine the effect of PYY in an environment that parallels some aspects of bulimia, rats were tested in a paradigm associated with approach-avoidance behavior, choosing a preferred (sweet) food paired with shock, over regular food safe from shock. PYY-treated rats chose to sustain shock to retrieve and consume the preferred food, at a significantly greater speed and quantity. The number of approaches that were met without retrieval of food due to anxiety after PYY treatment indicates that PYY increased motivation towards feeding, rather than anxiolysis. This effect of PYY in a model of conflict associated with food choice resembles aspects of bulimic binge-eating, which is characterized by the repetitive, rapid intake of food, despite anxiety associated with this behavior.