Ontogeny and the effect of aging on pancreatic polypeptide and peptide YY

Pancreatic PYY but not PPY expression is responsive to short-term nutritional state and the pancreas constitutes the major site of PYY mRNA expression in chickens

PP-fold peptides such as peptide YY (PYY) and pancreatic polypeptide (PPY) are known to play key roles in vertebrate energy homeostasis. Until recently, no gene sequence was available for avian PYY and therefore a gap in knowledge of regulation of its expression exists in avian species. Here we further evidence the mRNA sequence for chicken PYY and show that the pancreas is the major site of its mRNA expression, with a secondary peak of expression around the distal jejunum, in contrast to mammals where the large intestine is the major site of PYY expression. We also demonstrate that pancreatic PYY expression is responsive to short-term and long-term nutritional state, increasing within hours of feeding, in contrast to intestinal PYY which does not fluctuate to the same extent, and pancreatic PPY which appears to be primarily determined by long-term energy state. Both pancreatic PYY and PPY expression were found to exhibit ontogeny, being evenly distributed throughout the pancreas in young (2wk) chicks but having a decreasing splenic to duodenal gradient by adolescence (12wk).

Molecular cloning, expression analysis, and potential food intake attenuation effect of peptide YY in grass carp (Ctenopharyngodon idellus)

The peptide YY (PYY) is a 36 amino acid peptide involved in the food intake control in vertebrates. We have cloned and characterized a PYY gene from grass carp Ctenopharyngodon idellus. The full-length cDNA encodes a precursor protein of grass carp PYY (gcPYY) that consists of a putative 28-amino acid signal peptide, a 36-amino acid mature peptide, an amidation-proteolytic site, and a 30-amino acid carboxy-terminal extension. The gcPYY gene is comprised of 4 exons interspaced by 3 introns as seen in PYYs from other species. Amino acid alignment and gene structure comparison indicate that the structure of PYY is well preserved throughout vertebrate phylogeny. The tissue distribution and postprandial changes in gcPYY mRNA expression were evaluated by real-time PCR, which showed that the gcPYY is expressed abundantly in the central nervous system, with significantly increased expression following a single meal. During embryogenesis, the presence of gcPYY mRNA was detected in early developing embryos, and high expression levels were observed when most larvae completed their switch from endogenous nourishment to exogenous feeding. Reduced food intake by juveniles during a single meal after giving perpheral injection of gcPYY1-36 suggests a potentially important role of PYY in the food intake attenuation in grass carp.

Reg IV is differently expressed in enteroendocrine cells of human small intestine and colon

Reg IV is a 17 kD secreted C-type lectin physiologically found in selected enteroendocrine cells (EEC). It is thought be involved in the regulation of normal and pathological intestinal and/or neuroendocrine differentiation and proliferation but its ultimate functional role(s) is still unclear. We used immunostaining and compared the cellular expression of Reg IV with a panel of neuroendocrine markers in human GI-tract tissue samples. Reg IV showed cellular co-distribution with serotonin and chromogranin A in all parts of GI-tract. Co-localization of Reg IV with somatostatin was seen in colon and with substance P in ileum. Subpopulations of cells expressing Reg IV overlapped with EECs containing GLP-1, GLP-2, secretin, PYY, and ghrelin, depending on the anatomical localization of the samples. The results further underscore the high degree of diversity among EECs and suggest that Reg IV may be involved in the finetuning of functions exerted by the neuroendocrine cells in the GI-tract.

The role of peptide YY in gastrointestinal diseases and disorders (review)

Peptide YY (PYY) is affected in several gastrointestinal diseases and disorders. Changes in PYY appear to be an adaptive response to alterations in pathophysiological conditions caused by the disease. This applies to gastrointestinal diseases/disorders such as irritable bowel syndrome, inflammatory bowel disease, celiac disease, systemic sclerosis, and post-intestinal resection. By contrast, the changes in PYY in chronic idiopathic slow transit constipation (CST) seem to be of a primary nature, and may be one etiological factor of the disease. Abnormalities in PYY seem to contribute to the development of symptoms present in irritable bowel syndrome, inflammatory bowel disease, gastroenteropathy in long-standing diabetes and CST. The changes in PYY could, however, be favorable in some gastrointestinal disorders such as celiac disease, systemic sclerosis and post-intestinal resection state. Investigating changes in PYY in gastrointestinal diseases/disorders could be beneficial in clinical practice, where a receptor agonist or an antagonist can be used as a drug, depending on the condition. Similar to other neuroendocrine peptides/amines of the gut, PYY has broad physiological/pharmacological effects: it can bind to and activate several receptors with independent actions. Thus, in order to use PYY as a drug, receptor-specific agonists or antagonists need to be developed.