1. Enteric Neuromuscular Disorders and Visceral Pain Center, Division of Gastroenterology, Department of Internal Medicine, The University of Texas Medical Branch at Galveston, Texas;
2. Department of Pharmacology and Toxicology, Center for Addiction Research, The University of Texas Medical Branch at Galveston, Texas
3. Department of Neuroscience and Cell Biology, The University of Texas Medical Branch at Galveston, Texas; and