Gastrointestinal Regulatory Peptides

The most comprehensive and conceptual one-volume treatment of this field available and the first to emphasize the cellular and molecular aspects of gut peptide biology. Authored by an array of internationally distinguished scientists, it deals with issues of peptide localization and biosynthesis in gastrointestinal cells, mechanisms of peptide release and inactivation and the nature of peptide receptors. The breadth and readability make it an invaluable reference source for scientists in all disciplines interested in any aspect of brain-gut peptides.

Regulatory peptides represent the most diverse and versatile family of messenger molecules. They are produced by all living organisms from bacteria to mammals. They are involved in a wide variety of biological functions. Biologically active peptides and their receptors thus constitute an unlimited source of inspiration for the development of innovative drugs and cosmetics. The present eBook is a unique collection of research articles and reviews that provide a representative examplification of the latest progress in regulatory peptide research.

The mammalian gastrointestinal mucosa is a rapidly self-renewing tissue in the body, and its homeostasis is preserved through the strict regulation of epithelial cell proliferation, growth arrest, and apoptosis. The control of the growth of gastrointestinal mucosa is unique and, compared with most other tissue in the body, complex. Mucosal growth is regulated by the same hormones that alter metabolism in other tissues, but the gastrointestinal mucosa also responds to host events triggered by the ingestion and presence of food within the digestive tract. These gut hormones and peptides regulate the growth of the exocrine pancreas, gallbladder epithelium, and the mucosa of the oxyntic gland region of the stomach and the small and large intestines. Luminal factors, including nutrients or other dietary factors, secretions, and microbes that occur within the lumen and distribute over a proximal-to-distal gradient, are also crucial for maintenance of normal gut mucosal regeneration and could explain the villous-height-crypt-depth gradient and variety of adaptation, since these factors are diluted, absorbed, and destroyed as they pass down the digestive tract. Recently, intestinal stem cells, cellular polyamines, and noncoding RNAs are shown to play an important role in the regulation of gastrointestinal mucosal growth under physiological and various pathological conditions. In this book, we highlight key issues and factors that control gastrointestinal mucosal growth and homeostasis, with special emphasis on the mechanisms through which epithelial renewal and apoptosis are regulated at the cellular and molecular levels.

Strictly speaking, the term regulatory peptides may include any peptide which has a regulatory function in any organism. In recent years, how ever, the term has come to mean those originally classified as brain-gut peptides. The peptides initially defined as those belonging to the brain gut axis had a dual location in neurones of the brain and endocrine cells of the gut. We now include a number of neuropeptides found in the autonomic nervous system of the gut, the cardiovascular system and other systems. To many scientists comparative physiology means comparison of the mechanisms of certain functions in the rat, the guinea-pig, the cat and maybe some other mammal. If the philosophy is that man is the centre of the universe and other mammals can be used as 'models' of man, this may well be the most useful way to study the functions of the human being, without actually chopping somebody up. However, with a some what wider perspective on life, it is easy to see the importance of a full understanding of the function of all living organisms, in its own right as well as a link in the evolution towards individuals able to survive and reproduce in very different environments. The importance of com parative studies in all living organisms cannot be emphasized too much. It has been the ambition with this book to treat all animals as equally important.

Gastrointestinal Endocrinology: Receptors and Post-Receptor Mechanisms provides information pertinent to the fundamental aspects of receptors and post-receptor mechanisms. This book discusses a variety of topics, including normal and neoplastic growth, molecular biology and genetics, and actions of gut hormones and their clinical importance. Organized into 37 chapters, this book begins with an overview of the initial step in the interaction of a gastrointestinal peptide with its target cell. This text then examines the concept that the receptor proteins are a major control mechanism by which a cell engineers the effects of a hormone. Other chapters consider the epidermal growth factor (EGF), which is a heat-stable polypeptide that exerts both short- and long-term regulatory effects on various cellular processes. This book discusses as well the developments in the ability to measure the concentration of ionized calcium in cells. The final chapter deals with the hormonal mechanisms in gallbladder motility. This book is a valuable resource for biochemists.

The secretions of the exocrine pancreas provide for digestion of a meal into components that are then available for processing and absorption by the intestinal epithelium. Without the exocrine pancreas, malabsorption and malnutrition result. This chapter describes the cellular participants responsible for the secretion of digestive enzymes and fluid that in combination provide a pancreatic secretion that accomplishes the digestive functions of the gland. Key cellular participants, the acinar cell and the duct cell, are responsible for digestive enzyme and fluid secretion, respectively, of the exocrine pancreas. This chapter describes the neurohumoral pathways that mediate the pancreatic response to a meal as well as details of the cellular mechanisms that are necessary for the organ responses, including protein synthesis and transport and ion transports, and the regulation of these responses by intracellular signaling systems. Examples of pancreatic diseases resulting from dysfunction in cellular mechanisms provide emphasis of the importance of the normal physiologic mechanisms.