Beta cell

Beta cells (beta-cells, β-cells) are a type of cell in the pancreas in areas called the islets of Langerhans. They make up 65-80% of the cells in the islets.

Function

Beta cells make and release insulin, a hormone that controls the level of glucose in the blood. There is a baseline level of insulin maintained by the pancreas, but it can respond quickly to spikes in blood glucose by releasing stored insulin while simultaneously producing more. The response time is fairly quick, taking approximately 10 minutes.

Apart from insulin, beta cells release C-peptide, a byproduct of insulin production, into the bloodstream in equimolar quantities. C-peptide helps to prevent neuropathy, and other symptoms of diabetes related to vascular deterioration [Y. Ido, A. Vindigni, K. Chang, L. Stramm, R. Chance, W. F. Heath, R. D. DiMarchi, E. Di Cera, J. R. Williamson. 1997. Prevention of Vascular and Neural Dysfunction in Diabetic Rats by C-Peptide. Science, Vol. 277. no. 5325, pp. 563 - 566.] . Measuring the levels of C-peptide can give a practitioner an idea of the viable beta cell mass. [cite journal |author=Hoogwerf B, Goetz F |title=Urinary C-peptide: a simple measure of integrated insulin production with emphasis on the effects of body size, diet, and corticosteroids |journal=J Clin Endocrinol Metab |volume=56 |issue=1 |pages=60–7 |year=1983 |pmid=6336620]

β-cells also produce amylin, [cite journal |author=Moore C, Cooper G |title=Co-secretion of amylin and insulin from cultured islet beta-cells: modulation by nutrient secretagogues, islet hormones and hypoglycemic agents |journal=Biochem Biophys Res Commun |volume=179 |issue=1 |pages=1–9 |year=1991 |pmid=1679326 | doi = 10.1016/0006-291X(91)91325-7 ] also known as IAPP, islet amyloid polypeptide. Amylin functions as part of the endocrine pancreas and contributes to glycemic control. Amylin's metabolic function is now somewhat well characterized as an inhibitor of the appearance of nutrient [especially glucose] in the plasma. It thus functions as a synergistic partner to insulin. Whereas insulin regulates long term food intake, increased amylin decreases food intake in the short term.

Pathology

* Diabetes mellitus type 1 is caused by the destruction or dysfunction of insulin-producing beta cells by the cells of the immune system.

* In Diabetes mellitus type 2, by contrast, beta cells decline gradually over time, and insulin resistance plays at least as large a role in the disease [cite journal |author= |title=U.K. prospective diabetes study 16. Overview of 6 years' therapy of type II diabetes: a progressive disease. U.K. Prospective Diabetes Study Group |journal=Diabetes |volume=44 |issue=11 |pages=1249–58 |year=1995 |pmid=7589820|doi=10.2337/diabetes.44.11.1249] [cite journal |author=Rudenski A, Matthews D, Levy J, Turner R |title=Understanding "insulin resistance": both glucose resistance and insulin resistance are required to model human diabetes |journal=Metabolism |volume=40 |issue=9 |pages=908–17 |year=1991 |pmid=1895955 | doi = 10.1016/0026-0495(91)90065-5 ]

* Insulinoma is a rare tumor (usually benign) derived from beta cells. It results in recurrent and prolonged attacks of hypoglycemia.

Research

Much research is being done in the field of beta-cell physiology and pathology. One major research topic is its effects on diabetes. Many researchers are trying to find ways to use these beta-cells to help control or prevent diabetes. A major topic is the replication of adult beta-cells and the application of these to diabetes. The Larry L. Hillblom Islet Research Center at UCLA [ [http://www.lhirc.med.ucla.edu/index.htm The Larry L. Hillblom Islet Research Center ] ] is a leading research center in the field, within the Diabetes and Endocrinology Research Center [ [http://www.med.upenn.edu/idom/derc_index.html The DERC Homepage has moved ] ] , directed by Dr.Peter Butler. [ [http://www.lhirc.med.ucla.edu/faculty.htm Faculty ] ]

A team science effort also exists, known as the Beta Cell Biology Consortium (BCBC). [ [http://www.betacell.org Beta Cell Biology Consortium ] ] The BCBC is responsible for facilitating interdisciplinary approaches that will advance the understanding of pancreatic islet development and function. The long-term goal of the BCBC is to develop a cell-based therapy for insulin delivery.

In a study presented on June 8, 2008 at the American Diabetes Association’s 68th Scientific Sessions, a team showed that mice lacking insulin receptors in their beta cells had problems in the processing of insulin leading to excess, unprocessed levels of the hormone. Unprocessed insulin is unable to properly control glucose levels in the body. High circulating levels of unprocessed insulin and insulin resistance, a condition in which normal amounts of insulin are inadequate to produce a normal insulin response, are both known to be early indicators of type 2 diabetes. [ [http://newswise.com/articles/view/541502/ Newswise: Beta Cell Defect Linked to Type 2 Diabetes] Retrieved on June 8, 2008.]

ee also

* Gastric inhibitory polypeptide receptor
*List of terms associated with diabetes

References

External links

*