Pancreatic polypeptide cells
Pancreatic polypeptide cells (PP cells), or formerly as gamma cells (γ-cells), or F cells, are cells in the pancreatic islets (Islets of Langerhans) of the pancreas. Their main role is to help synthesize and regulate the release of pancreatic polypeptide (PP), after which they have been named. The pancreatic islets, where PP cells reside, was discovered in 1869 by a German pathological anatomist and scientist, Paul Langerhans. PP cells help to make up the pancreas but are smallest in proportion to the other cells previously stated. The proportions can vary based on which animals are being studied, but in humans, PP cells make up less than 2% of the pancreatic islet cell population.[1]
Structure and role
The pancreas serves multiple roles within mammalian organisms. It plays a role in the digestive system and the endocrine system making it an organ and a very important gland.[2] PP cells tend to located in the pancreatic islets, and are one of the rarer pancreatic cell types.[1] Some small clusters may also be found surrounded by exocrine pancreas.[3] They tend to be located in the duodenal part of the pancreas more medially.[3] Given their location in pancreatic islets along with their low population, they are able to respond efficiently to changes in blood sugar, nerve impulses, and chemical signaling through gap junctions or cellular signaling. PP cells show the highest concentration at the head of the pancreas.[1]
PP cells play an important role when it comes to the regulation of
Pancreatic polypeptide cells are most active and secrete more pancreatic polypeptide after a meal with high protein, fasting, physical activity, and acute hypoglycemia. These same cells are inhibited by somatostatin, an inhibitory gastrointestinal hormone, and the presence of glucose.[7]
Through different microscopy techniques, the structural related details of PP cells have been able to be better understood. This is inclusive of how big they are, what their cellular membranes look like, the proteins associated with them, and even their size. PP cells are elongated cells. Another one of these details can be noted in insulins secretory granules, or container like buds, that store insulin within a cell. In PP cells, the size of the insulin granules are smaller and spherical and similar to those in alpha cells. This is noted in human PP cells, but different animals have been shown to have different sized granules compared to humans, like rodents. In cats and dogs, PP cells have large granules.[8] In rats, PP cells have few granules, similar to humans. In dogs, some PP cells are located in the walls of the antrum of the stomach.[3]
Clinical significance
Pancreatic polypeptide cells are one of the most poorly understood cells in the pancreas.[1] This is due to a number of reasons, but most notably due to its small proportion in relation to the other cells located in the pancreatic islets. Another reason that these cells are so poorly understood has to do with the difficulty in researching and analyzing these cells. Different studies conducted by various organizations and labs have all led to conflicting reports when trying to quantify PP cell populations in type 1 and type 2 diabetes due to the fact that these cells proliferate when there is damage to the pancreas.[1]
Given that PP cells reside in the pancreas and serve both the digestive and endocrine systems, the roles it can play within a clinical setting are vast and important to analyze. Many of the applications geared around pancreatic polypeptide cells and the substances they secrete serve to better understand and treat
See also
List of distinct cell types in the adult human body
References
- ^ PMID 26216135.
- ^ "Pancreas: What Is It, Function & Location". Cleveland Clinic. Retrieved 2022-04-03.
- ^ ISBN 978-0-12-475570-3, retrieved 2021-02-03
- ^ "PP Cell - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-04-03.
- ^ "Pancreatic Polypeptide - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-04-03.
- PMID 7025798.
- ^ "Pancreatic Polypeptide". Bioanalytical Lab & Top CRO for Large Molecule Bioanalysis. Retrieved 2022-04-03.
- ISBN 978-0-12-475570-3, retrieved 2021-02-03