RESEARCH PROGRAM:
Animals, including people, show a remarkable ability to adapt their behaviors depending on their internal state. For example, when animals reach sexually maturity, a new set of social behaviors emerge in response to potential mates. This developmentally appropriate control of mating behavior promotes reproductive success. Gonadal hormones, like estrogens, are critical for controlling these behaviors. Likewise, when animals are deficient in calories, water, or electrolytes, the appropriate ingestive behaviors are elicited to restore energy and fluid balance. The hormone leptin acts as a signal for energy stored as fat, whereas the hormone angiotensin is an indicator for fluid depletion. In disease states, abnormal leptin and angiotensin signaling may underlie aberrations of body weight and blood pressure.
How do hormones alter brain function to elicit appropriate behavioral responses? To answer this question, we focus on three behavioral paradigms:
1) Mating: The ovarian steroid estradiol induces neural plasticity in the hypothalamus, a region that controls mating behaviors in females.
2) Drinking: The peptide hormone angiotensin prompts thirst and sodium appetite. The location of angiotensin receptors in the brain is known, and we are now investigating how angiotensin may change neural activity to produce water and salt ingestion.
3) Food Intake: The hormone leptin, an indicator of adequate fat storage, normally reduces food intake. When animals overeat, they can become unresponsive to leptin. We are examining possible effects of leptin on synaptic connections in the brain to explain this disruption in energy balance.
Techniques range from behavioral studies, to cellular protein and molecular assays, to analysis of synaptic connections.
This research will help answer basic questions about the biological controls of social behavior and the maintenance of body weight and fluid balance. In addition, our findings may be relevant for improved therapies for obesity and cardiovascular disease. This research has been funded by the National Institute of Health.