Insulin protein metabolism

Diabetes mellitus (DM) is a group of metabolic disorders characterized by hyperglycemia and abnormalities in carbohydrate, fat, and protein metabolism. It results from defects in insulin secretion, insulin sensitivity, or both. Chronic microvascular, macrovascular, and neuropathic complications may ensue. 

The peptide hormone insulin (see Box 13.1) is produced by the pancreas and plays a key role in the regulation of carbohydrate, fat, and protein metabolism, hi particular, it has a hypoglycaemic effect, lowering the levels of glucose in the blood. A malfunctioning pancreas may produce a deficiency in insulin synthesis or secretion, leading to the condition known as diabetes mellitus. This results in increased amounts of glucose in the blood and urine, diuresis, depletion of carbohydrate stores, and subsequent breakdown of fat and protein. Incomplete breakdown of fat leads to the accumulation of ketones in the blood, severe acidosis, coma, and death. 

Diabetes mellitus is characterized by hypergly-caemia and disturbances of carbohydrate, fat and protein metabolism that are associated with absolute or relative deticiencies in insulin action and/or insulin secretion. Although diabetes is an endocrine deficiency or resistance state its major manifestations are those of metabolic disease with wide ranging tissue effects. Insulin resistance does exist in type 2 diabetes, however it is also exists in many individuals without diabetes. It is difficult to accept insulin resistance is the sole determining pathogenic factor in type 2 diabetes. Therefore, it is more appropriate to describe type 2 diabetes as a condition of /3-cell dysfunction in an insulin resistance background. 

Progesterone has little effect on protein metabolism. It stimulates lipoprotein lipase activity and seems to favor fat deposition. The effects on carbohydrate metabolism are more marked. Progesterone increases basal insulin levels and the insulin response to glucose. There is... 

Mechanism of Action. Few data are available that describe the effects of anabolic steroids on protein metabolism even fewer data exist for assessment of direct effects of anabolic steroids on lipid metabolism in growing ruminants. The lack of any consistent change in somatotropin, prolactin, insulin, or other metabolic hormones (qv) in a total of 15 studies has been noted (1,38). 

Protein metabolism Cortisol promotes the breakdown of proteins and inhibits protein synthesis. This leads to muscle wasting in the quadriceps-femoris groups, and muscular activities may become difficult as a result. The effect of cortisol is opposite to that of insulin. 

Insulin (protein) Pancreas Various tissues, fat, muscle behavior Glucose uptake, metabolism... 

The endocrine islet cells comprise only 1-2% of the pancreatic tissue. They synthesize the hormones insulin, glucagon, somatostatin, and pancreatic polypeptide. Insulin and glucagon maintain glucose homeostasis via their actions on lipid, carbohydrate, and protein metabolism. The pancreas originates from two patches of epithelium in the duodenum during the fifth week of gestation in humans. The endocrine pancreatic cells begin to differentiate very... 

In humans and animals, chromium(ni) is an essential nutrient that plays a role in glucose, fat, and protein metabolism by potentiating the action of insulin (Anderson 1981). The biologically active form of chromium, called glucose tolerance factor (GTF), is a complex of chromium, nicotinic acid, and possibly amino acids (glycine, cysteine, and glutamic acid). Both humans and animals are capable of converting... 

Insulin affects the protein metabolism by an increased uptake of amino acids as a result of the increased permeability of the cell membranes. 

Shangraw, R. E., Stuart, C. A., Prince, M. J., Peters, E. J., and Wolfe, R. R. (1988). Insulin responsiveness of protein metabolism in vivo following bed rest in humans. Am.. Physiol. 255, E548-E558. 

Clark AS, Fagan JM, Mitch WE. 1985. Selectivity of the insulin-like actions of vanadate on glucose and protein metabolism in skeletal muscle. Biochem J 232 273-276. 

Diabetes mellitus is a group of metabolic disorders of fat, carbohydrate, and protein metabolism that results from de-fectsin insulin secretion, insulin action (sensitivity), or both. 

Urea, the end product of nitrogen metabolism, accumulates rapidly in ARF. Most patients with ARF have a primary stressful illness that results in ureagenesis, and thus protein breakdown is markedly accelerated. Protein catabolism in ARF may be stimulated as the result of insulin resistance, metabolic acidosis, circulating proteases and inflammatory mediators, and the effects of uremic toxins. The mechanism may be direct, via modulation of protein synthesis, or indirect, by inhibiting the action of anabolic hormones. ... 

According to this mechanism, Akt kinase regulates central metabolic pathways of the cell. It is a major regulator in insulin-dependent metabolic pathways. The PI3-kinase/Akt pathway is activated by insulin and thereby mediates many of the metabolic effects of insulin, including glucose transport, lipid metabolism, glycogen synthesis and protein synthesis (see Section 1.5.6). Furthermore, by phosphorylating pro-... 

Insulin is essential for the metabolism of glucose and control of blood glucose levels, but it also has important effects on fat and protein metabolism. 

Protein metabolism. Insulin stimulates transport and uptake of amino acids, as well as the incorporation of amino acids into proteins. 

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