Possible Dysregulation of Orexin and Dopamine Systems in Anorexia Nervosa

Anorexia nervosa (AN) is a psychiatric illness characterized by a lack of motivation and a taste for rewarding food consumption. Mood disorders such as depression and stress are frequently associated with this condition. Abnormalities in several neural systems have been identified in patients with AN, including serotonin, dopamine (DA), appetite-related neuropeptides, and other neurochemical systems. Moreover, the changes that occur between the mesolimbic dopaminergic pathway and the orexin neurons in the lateral hypothalamus (LH) in response to the reduction in food consumption are key in the development of AN. Several studies suggest a functional relationship between orexin and dopaminergic circuits. LH orexin neurons project dense fibers on dopaminergic neurons, potently activating these neurons. DA and orexin neurons regulate negative and positive motivational states, such as drug and food seeking behavior. For this reason, it is important to extend the study of the functional and emotional interactions that exist between both neuronal systems to design new drugs that act at a behavioral and molecular level to treat AN. This chapter provides an overview of the evidence from literature implicating dopamine-orexin systems in AN and discusses recent advances that have contributed to our current understanding of the mechanisms underlying the molecular bases of AN.