Insulin secretion, regulation

Taken together, these data emphasize the importance of insulin action in the liver for glucose homeostasis, in the regulation of insulin secretion from (3-cells and indicate that the INSR plays an important role in the central regulation of body weight and reproduction [4, 5]. 

Metabolic diseases In the pancreatic (3-cells, KATP channel derived from >SUR1 and Kir6.2, links cellular metabolism to electrical activity and regulates insulin secretion. Mutations in SUR1 and Kir6.2 that result in loss of Katp channel function have been identified in families with familial persistent hyperinsulinemic hypoglycemia of infancy (PHHI). 

Sorenson RL, Brelje TC and Roth C. 1994. Effect of tyrosine kinase inhibitors on islets of Langerhans evidence for tyrosine kinases in the regulation of insulin secretion. Endocrinology 134(4)4975—1978. 

Glutamine, along with glucose, can stimulate insulin secretion by the endocrine pancreas. The significance of this is the regulation of the plasma glutamine concentration is not known. 

Figure 7.2 Glucose regulation by insulin. Increased concentrations of glucose and amino acids in the circulation, vagus nerve stimulation and circulating hormones e.g. GLP) stimulate insulin secretion by 3-cells of the pancreatic islets. Insulin suppresses glucose production by the liver and increases glucose uptake by skeletal muscle and fat, leading to decreased circulating glucose concentrations.

Ahuja, N., Schwer, B., Carobbio, S., Waltregny D., North, B.J., Castronovo, V., Maechler, P. and Verdin, F. (2007) Regulation of insulin secretion by SIRT4, a mitochondrial ADP-ribosyltransferase. The Journal of Biological Chemistry, 282, 33583-33592. 

Gluc on and insulin secretion is regulated in response to blood glucose levels. 

The incretin hormone glucagon-like peptide-1 (GLP-1) plays a crucial role in the regulation of insulin by acting on the pancreas to potentiate glucose-induced insulin secretion. GLP-1 is rapidly cleaved by serine protease dipeptidylpeptidase IV. The inhibitors of DDP-IV are new drugs for the oral treatment of type 2 diabetes. 

Brixel, L. R., Monteilh-Zoller, M. K., Ingenbrandt, C. S., Fleig, A., Penner, R., Enklaar, T., Zabel, B. U., and Prawitt, D. (2010). TRPM5 regulates glucose-stimulated insulin secretion. Pflugers Arch, doi 10.1007/s00424-010-0835-z. 

Effect on endocrine function Catecholamines are important endogenous regulators of hormone secretion from a number of glands. Insulin secretion is stimulated by beta receptors and inhibited by a2-receptors. Similarly, renin secretion is stimulated by Pj and inhibited by receptors indeed, beta-receptor antagonists may lower plasma renin at least part by this mechanism. 

In their report the researchers describe a culturing technique that can turn mouse embryonic stem cells into cell clusters that resemble pancreatic islets. The clusters inner cells produced insulin, while outer cells produced glucagon and somatostatin, two other proteins typically synthesized by pancreatic cells. Most important, the embryonic stem cell-derived pancreas cells produce insulin in response to glucose, the fundamental role of beta cells that regulate insulin secretion. The major shortcoming of the system at this time is the low levels of insulin production. Refinements in culture technique or drug manipulation may be needed to achieve therapeutic levels. 

Over 5% of the population of western nations is afflicted with diabetes. TTie most prevalent form of diabetes, non-insulin-dependent diabetes mellitus (NIDDM, or type 11), is commonly associated with obesity and hypertension, and is believed to be the consequence of altered insulin action or insulin secretion (for review see Defronzo, 1988 Defronzo and Ferrannini, 1991). Insulin-dependent diabetes mellitus (IDDM, or type 1 diabetes) accounts for approximately 10% of all cases of diabetes. IDDM is characterized by specific destruction of insulin secreting /3-cells found in islets of Langerhans. Destruction of 80-90% of islet /3-cells causes insulin deficiency and the inability to regulate blood glucose levels. 

The receptor for l,25(OH)2D exists in a wide variety of tissues—not just bone, gut, and kidney. In these "nonclassic" tissues, l,25(OH)2D exerts a number of actions including regulation of parathyroid hormone secretion from the parathyroid gland, insulin secretion from the pancreas, cytokine production by macrophages and T cells, and proliferation and differentiation of a large number of cells, including cancer cells. Thus, the clinical utility of l,25(OH)2D and its... 

T Biosynthesis and degradation of triacylglycerols are regulated such that the favored path depends on the metabolic resources and requirements of the moment. The rate of triacylglycerol biosynthesis is profoundly altered by the action of several hormones. Insulin, for example, promotes the conversion of carbohydrate to triacylglycerols (Fig. 21-19). People with severe diabetes mellitus, due to failure of insulin secretion or action, not only are unable to use glucose properly but also fail to synthesize fatty acids from... 

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