Extra pancreatic synthesis of insulin

Abstract

It is currently believed that insulin, an essential hormone for carbohydrate metabolism, is produced only in the pancreas. Many investigators on the other hand had reported that various cells in different organs of the body beside pancreas are also capable of synthesizing insulin. This hormone not only has a critical role in the carbohydrate metabolism, but the protein is also reported to prevent the atherosclerosis and hypertension. The multifunctional synthesis of the protein in different cells in various organs is presented in the review. Insulin was reported to be synthesized in the liver, brain, thymus, adipocytes, gastrointestinal tract, bone marrow and in the leukocytes. Insulin synthesis was confirmed by cDNA analysis, amino acid sequence and by bioassay of the hormone. Liver was found to synthesize insulin, and glucose was found to stimulate NO synthesis in the liver and NO thus produced stimulated insulin and Glut-4 synthesis in the liver. Insulin synthesis occurs not only in human but also all animals. The lymphocytes and the leucocytes in the circulation were found to synthesize insulin. It is possible that synthesis of insulin in leucocytes could be involved for the ready supply of insulin in the prevention of thrombosis in platelets which did not produce any insulin. The synthesis of insulin in different organs in many different animals has also been reported. It was concluded that the synthesis of insulin in different cells was essential to maintain the cellular integrity from carbohydrate derived energy for all living organisms.