Eating Disorders from Binge to Anorexia: Basic and Clinical Approaches for a Translational Research

“Eating disorders” cover a variety of psychiatric illnesses in which individuals express abnormal eating behaviors often resulting in either insufficient or excessive food intake. Eating disorders include anorexia nervosa, bulimia nervosa and binge eating. Food intake, like drinking or reproduction, is a complex motivated behavior essential for the survival of the organism through the regulation of homeostatic and hedonic systems. The challenge is to understand how the feeding behavior can become aberrant to the extent that it can become life threatening. In mammals, while there has evolved a finely tuned physiological system that controls the balance between energy expenditure and energy intake, there is no clear evidence to support the idea that eating is simply an automatic response to an acute energy demand. In fact, food intake involves endocrine and central effectors directly linked to energy homeostasis, but also to neuronal circuitries regulating stress, emotions, reward, biological rhythms, learning, individual experience with food (anticipatory adaptation) and, in humans, cognitive processes and socio-cultural factors. Eating depends on a concomitant functioning of a hard-wired homeostatic hypothalamic circuitry that is almost entirely identical between mammals resulting from evolutionary selection, together with a more flexible non-homeostatic hedonic circuitry, also called the reward meso- corticolimbic system, whose functions vary according to individuals’ experiences and/or epigenetic variations. Several hypotheses have been formulated to better apprehend the mechanisms leading to eating disorders, like gene polymorphisms, epigenetic changes, altered reward processes, early perinatal stress, dysbiosis or endocrine disruptors... The use of translational research which aims bridging the gap between basic research and medical practice is essential to assess more precisely the complex crosstalk between the central nervous system and peripheral organs. The aim of this topic is thus to develop different aspects of this translational research by presenting recent data obtained in animal and/or cellular models which benefit from the advances of new technologies, but also the recent outputs obtained from patients.