Thirst is an incredibly potent drive state. People and animals work very hard to get water when thirsty, and understanding how our brain controls these behaviors is an important step toward understanding more general concepts in motivation and reward. In our attempt to fully understand the thirst response, we have several main lines of research that focus primarily on the neurohormonal control of thirst and salt appetite. Current projects generally fall into at least one of the following three categories.
Understanding the interactions between feeding- and drinking-related systems
Recent advances in science and the worldwide rise of obesity have fueled a remarkable surge in the study of feeding behavior. These studies have revealed a large number of peptides that influence feeding behavior, but far less attention has been paid to the role these peptides may play in drinking behavior. Our laboratory performs experiments that test the effect of several “feeding-related” peptides on water and salt intake. These studies have most recently focused on two peptide systems, ghrelin and GLP-1. Ghrelin is particularly puzzling because it increases food intake, but decreases fluid intake. Understanding how these effects occur in different directions is an important step toward elucidating non-overlapping networks that respond to ghrelin. We are also very interested in the ingestive responses to glucagon-like peptide-1 (GLP-1). Our studies have shown that activation of GLP-1 receptors decreases water and salt intakes, and that blocking the receptor increases these behaviors. We have also found that the act of drinking itself affects GLP-1 in the brain, and we are currently trying to understand the circuits through which this acts.
Studying the behavioral relevance of angiotensin intracellular signaling pathways
One line of research focuses on the control of behavior and cardiovascular systems by the hormone angiotensin II. Angiotensin II is a key hormone in the response to dehydration, and many drugs used to treat hypertension work by blocking the actions of angiotensin II. Our laboratory has a particular interest in the cell signaling pathways activated by the receptor for angiotensin II, and how these signaling pathways lead to both sensitization and desensitization of the responses to the hormone. These studies have the potential to generate important knowledge that could be useful in the development of new treatment strategies for high blood pressure or dehydration. Our most recent work has focused on the effect of repeated administration of angiotensin II, and how this leads to enhanced or blunted responses.