Immunohistochemical Localization of the Melanocortin-4 Receptor (MC4R) in the Colon Myenteric Plexus by

............................................................................................................................. ii Acknowledgements ............................................................................................................ iv List of Tables ................................................................................................................... vii List of Figures .................................................................................................................. viii List of Abbreviations ...........................................................................................................x Introduction............................................................................................1 Literature Review.....................................................................................2 Melanocortin System/Receptors ..................................................................................2 Central and Peripheral Expression of MC4R...............................................................5 Role of Leptin in the Regulation of the Melanocortin System ....................................5 Anatomy of the Colon ..................................................................................................7 Enteric Nervous System (ENS) ...................................................................................8 Enteric Glial Cells ......................................................................................................13 Expression and Potential Role of MC4R in the Gastrointestinal Tract .....................16 Inflammation ..............................................................................................................17 Inflammatory Bowel Disease (IBD) in the Colon .....................................................18 Role of Luminal Flora in IBD ....................................................................................20 Role of Intestinal Epithelium in IBD .........................................................................21