Involvement of dopamine and opioids in the motivation to eat: influence of palatability, homeostatic state, and behavioral paradigms.

Rationale: Motivation for food depends on several variables including food palatability, the homeostatic state of the organism, and the nature of the behavior required to obtain the reward. However, few studies to date have tried to evaluate motivation for food considering all these variables at the same time. Since dopamine and opioids have been deeply involved in the regulation of feeding, it is of interest to investigate their role considering all the mentioned variables.