856 Abstracts / Appetite 52 (2009) 815–868 Social influence on youth food intake and choice of activities S.J. SALVY University at Buffalo, Buffalo, NY, USA An ever-increasing number of children and adolescents are considered overweight and obese. The social environment clearly influences youths’ eating behavior and choice of activities. In this presentation we will review a series of studies conducted in our laboratory on the effects of peers and friends on children’s eating behavior and choice of activities. This research shows that over- weight youth eat more when alone than when in company of peers and also eat more in the presence of overweight peers than in the presence of leaner peers. Additionally, time spent alone is directly associated with sedentary levels of activity. These findings sug- gest that the presence of peers and friends can be used to promote healthier eating and involvement in physically active leisure activi- ties in overweight youth. By contrast, social isolation resulting from being rejected due to weight status may decrease the reinforcing value of physical activity and increase the value of sedentary activ- ities that can be completed alone such as television watching and snacking. doi:10.1016/j.appet.2009.04.170 Selective ER antagonist’s effect on food intake in ovariectomized and cycling rats J. SANTOLLO * , L.A. ECKEL Program in Neuroscience, Florida State University, Tallahassee, FL, USA Estrogens exert many of their behavioral effects by binding to nuclear estrogen receptor (ER) proteins, ER and ER. Recent stud- ies involving ER knockout mice and selective ER agonists suggest that estradiol’s anorexigenic effect is mediated via activation of ER. To further investigate this hypothesis, we examined whether presumptive ER antagonists could block estradiol’s anorexigenic effect. In the first series of experiments, the effects a silent ER antagonist (MPP) on food intake and uterine weight were monitored in ovariectomized (OVX) rats treated with either a phys- iological dose of estradiol benzoate (EB) or a selective ER agonist (PPT). In the next set of experiments, food intake was monitored following acute administration of MPP in ovarian-intact (cycling) female rats. Contrary to our hypothesis, MPP failed to attenuate either EB’s or PPT’s ability to decrease food intake and increase uter- ine weight in OVX rats. However, in ovarian-intact rats, a similar regimen of MPP treatment attenuated the phasic decrease in food intake that is associated with estrus. We conclude that MPP may be a useful tool to investigate the behavioral actions of endogenous estradiol, but may have limited utility in studying the behavioral effects of exogenous estradiol in OVX rats. doi:10.1016/j.appet.2009.04.171 Neuroendocrinology of anorexia nervosa A.J.W. SCHEURINK 1,* , P. SODERSTEN 2 1 Department of Neuroen- docrinology, University of Groningen, Haren, Netherlands 2 Section of Applied Neuroendocrinology, Karolinska Institute, Huddinge, Sweden We reviewed the literature on the effects of food restriction and starvation in humans and suggest that the symptoms of anorexia nervosa are epiphenomena to starvation and the associated disor- dered eating. Keys and collaborators decreased the food available to mentally and physically healthy men and found that these men developed most of the symptoms of eating disorders, including the psychiatric symptoms, indicating that an eating disorder can be developed without an antecedent mental disorder. Humans have evolved to cope with the challenge of starvation and the neu- roendocrine mechanisms that have been under this evolutionary pressure are responses to the externally imposed shortage of food. We will provide examples for this by showing the actions and alterations of Neuropeptide Y, dopamine and norepinephrine in an animal model for anorexia nervosa. Based on the observation in patients in the anorexia clinic in Sweden and experiments with the rat model we developed a theoretic framework for the develop- ment of anorexia nervosa suggesting that the brain mechanisms of reward are activated when food intake is reduced and that disor- dered eating behavior is subsequently maintained by conditioning to the situations in which the disordered eating behavior devel- oped via the neural system for attention. In a method based on this framework, patients are taught how to eat normally, their physical activity is controlled and they are provided with external heat. The method has been proven effective in a randomized controlled trial. doi:10.1016/j.appet.2009.04.172 The varied influences of intestinal ‘bitter taste’ on ingestive behavior L.A. SCHIER 1,2,* , E.M. SWOVERLAND 1 , T.L. DAVIDSON 1,2 , T.L. POWLEY 1,2 1 Department of Psychological Sciences, West Lafayette, IN, USA 2 Ingestive Behavior Research Center, Purdue University, West Lafayette, IN, USA Bitter taste receptors are expressed in the intestinal mucosa, but little is known about their roles in detection and ingestive behavior. The present study examined the effects of concurrent intraduode- nal (ID) infusions of a bitter stimulus, denatonium benzoate (DB), on the microstructure of licking for water. Rats with ID catheters were trained to take their daily water in 30 min. During control sessions, each lick at a lickometer spout delivered water simultaneously to the spout (4 L) and ID (2 L). Probe sessions were identical to con- trol sessions, except that DB instead of H 2 O was infused ID during 5–8 min. An ascending DB series (0.01–10 mM) over 12 probe ses- sions was applied. Even at the lowest concentration (0.01mM), ID infusions of DB caused more licks per session. This difference was characterized by a faster lick rate, pronounced by more rapid inter- lick intervals (<250 ms), and further evident in an increase in lick burst size, with no change in burst duration, in DB probe sessions. The DB stimulation effect weakened over the ascending concentra- tion series, suggesting that habituation may have occurred. To test for habituation, rats were given a single offline pairing of oral DB and LiCl. This dishabituation pairing reinstated responding to ID DB. Finally, to determine if the ID DB was aversive, rats were trained to associate a flavor (CS+) with ID 10 mM DB and another flavor with ID water. In a two-bottle test, rats avoided the CS+. The results suggest ID DB has rapid, distinct unconditioned and conditioned effects on ingestive behavior. NIH HD052112 and DK27627. doi:10.1016/j.appet.2009.04.173