The endocrine function of the gastrointestinal tract

A. Pearse( 1969) formulated a theory about the presence in the body of a functionally active system of cells of neuroectoderm origin - APUD-systems( amine content, precursor uptake, decarboxylation).Characteristic properties of this system are the ability to absorb and accumulate biogenic amine precursors, subsequent decarboxylation, resulting in the formation of biologically active substances and polypeptide hormones( gastrin, secretin, vasoactive intestinal polypeptide, etc.).APUD-system cells are present in many tissues of the gastrointestinal tract, paraganglia, various endocrine organs( hypothalamus, pituitary, adrenal, thyroid and pancreas, etc.).These cells secrete polypeptide hormones and biologically active peptides that function as hormones and neuromediators. APUD-system in the human body carries out endocrine, neuroendocrine, neurocrine and paracrine functions.

Tumors developing from the cells of the APUD system are called apu-domes. Many endocrine syndromes( carcinoid syndrome, hypoglycemia, Ithenko-Cushing syndromes, Zollinger-Ellison syndromes, MEN I, II and III types) are caused by the presence of an indigestion. Recently, instead of the broader term "APUDomy", the term "gastroenteropancreatic endocrine tumors"( GEPEO) has been used in the clinical literature to refer to endocrine tumors of the pancreas and gastrointestinal tract.

Approximately 19 GEPEO types are currently described. Most tumors are characterized by multi-hormonal secretion, but in the clinical picture, the symptoms of increased secretion of a single hormone usually prevail. In Table.the classification of GEPEO is presented.

Study of the hormones that characterize the function of the incremental apparatus of the gastrointestinal tract and pancreas plays an important role in the diagnosis of HEPEO.The main GEPEO are insulinoma, gastrinoma, glucagonoma, VIPoma, tumors that cause the development of carcinoid syndrome and hormoneally inactive endocrine tumors.

Carcinoid tumors are tumors from enterochromaffin cells. According to their origin, they are divided into outgoing from the anterior gut( bronchi, stomach, duodenum, bile duct, pancreas), midgut( lean, ileum, appendix, ascending colonic intestine), hindgut( transverse, descending colon,sigmoid and rectum).In rare cases, carcinoid tumors develop in the sex glands, prostate gland, kidneys, mammary glands, thymus gland or skin.

Laboratory diagnostics of violations of the incremental function of the gastrointestinal tract and GEPEO is based on the determination of various hormones produced by the cells of this system.

Table Classification of gastroenteropancreatic endocrine tumors

Table Classification of gastroenteropancreatic endocrine tumors

Note. VIP - vaso-intestinal peptide.

Note. VIP - vaso-intestinal peptide.