Feeding Pathways

Hunger vs. Satiety Controlled by communication between the gut and parasympathetic nervous system Neuroscience (Bears, Connors, Paradiso)

Some Basic Feeding Terminology Feeding Behavior: Hyperphagy: increase in food intake (often used to explain pathological eating) Hypophagy: decrease in food intake Feeding Physiology: Orexigenic: release of a drug or hormone that increases food intake Anorexigenic: release of a drug or hormone that decrease food intake

Peripheral Regulation of Food Intake Leptin (anorexigenic; satiety) Ghrelin (orexigenic; hunger)

Dysregulation of leptin leads to… The ob/ob mouse: do not have circulating leptin levels, but this does not mean that they are insensitive to leptin In fact, they are hypersensitized to exogenously administered leptin. WHY? animal model of Type II diabetes

Central Regulation of Food Intake The BIG THREE hypothalamic areas regulating food intake are: Lateral hypothalamus Ventromedial hypothalamus Arcuate Nucleus

Central Regulation of Hyperphagy NPY/AgRP-containing enhance feeding behavior

Central Regulation of Hypophagy αMSH/CART-containing inhibit feeding behavior

Balance Between Two Pathways Competitive agonism of MSH receptors and antagonism of MC4 receptors by leptin

Central Regulation of Thirst Communication between neurons in the pituitary (organum vasculosum of lamina terminalis [OVLT] and vasopressin-secreting neurons) and kidneys Diabetes Insipidus