Aaron Roseberry

Neurobiology of Feeding and Reward

The main interest of my laboratory is the neural regulation of feeding and body weight, including the development of obesity.  We focus primarily on the mesolimbic dopamine system, which is the brain’s “reward” circuitry.  While these neural “reward” circuits are primarily associated with their roles in drug abuse and addiction, it has been suggested that they were originally designed to respond to natural rewards such as food and water.  For example, multiple studies have shown that food can act as a “reward” to stimulate dopamine release in specific regions of the brain similar to what is seen with abused drugs.

The rise in obesity levels has been paralleled by a significant increase in the intake of processed foods high in fat and sugar, suggesting that pathways regulating the intake of these foods may be sites that could be targeted for therapies to help prevent or reverse obesity.  Thus, we are interested in how pleasurable & appetizing foods (such as those high in fat and sugar) activate the “reward” pathways in the brain, and how these responses change with obesity.  In addition, we are trying to understand how changes in the activity of dopamine pathways in turn affect feeding and body weight.

In the lab we use a number of different techniques to examine these questions, including cellular electrophysiology and immunohistochemistry, along with multiple different cellular, molecular and genetic approaches.

Currently, there are 3 different major projects in the laboratory:

1. How does feeding affect the activity of different parts of the mesolimbic dopamine system?  In these studies we are trying to determine how feeding affects the activity of different components of dopamine circuitry, and how these changes affect other processes such as future feeding and drug abuse/addiction.  For example, we are seeking to understand the changes that occur when animals are allowed restricted or prolonged access to appetizing high fat or high sugar foods, or when they undergo feeding protocols similar to what is seen with human dieting.
2. How do other hormones, neurotransmitters and neuropeptides interact with dopamine circuitry to regulate feeding and body weight?  There are a large number of substances that play an important role in the regulation of feeding and body weight, and many of them have been shown to interact with dopamine pathways (i.e. leptin, insulin, ghrelin, orexin etc).  We are currently focusing on a family of peptides termed the melanocortins.  These are peptides that are expressing the hypothalamus and serve to decrease feeding, stimulate energy expenditure, and regulate glucose levels.  We are using a number of different techniques to determine whether melanocortins regulate processes such as feeding, activity, and drug abuse/addiction through actions on the mesolimbic dopamine system.