Dr. Joel Elmquist (image) UT Southwestern Medical Center Share Print E-Mail Caption Dr. Joel Elmquist, professor of internal medicine, is helping shed light on how the brain chemical serotonin works to affect appetite. The study he led found that serotonin activates some neurons and melanocortin-4 receptors to curb appetite and at the same time blocks other neurons that normally act to increase appetite. Credit UT Southwestern Medical Center Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.