![]() Endocrinology Summers |
Hormones Endocrine Glands Receptors Homeostasis 2nd Messengers |
Nuclear Receptors Genetic Regulation Hormone Synthesis Receptor Regulation Hypothalamo-Hypophysial Communication |
Tropic Hormones Neurohypophysial Nonapeptides Thyroid Axis Steroids Adrenal Axis |
Adrenal Medulla Osmotic-Pressure Balance Reproductive Endocrinology Prolactin Somatic Axis |
Growth Factors Immune Factors Ca++, PO4 Homeostasis Pancreatic Hormones GI Hormones |
Guts 'n Brains Brain Hormones Neurosteroids Neuropeptides Endocrine Evolution |
Figures for Endocrionology text:Vertebrate Endocrinology5th Edition - David O. Norris: Read pages 449-463, 484-489 for this lecture acronyms end |
XXVII. Gastrointestinal Hormones A. Hormones that stimulate exocrine secretions 1. regulate the secretion and/or absorption of H2O, ions, enzymes, and mucus 2. from the stomach a. gastric acid ([H+]) secretion i. gastrin17aa, GRP27aa/bombesin14aa (= gastrin releasing peptide), opioids, (1) gastrin1,2s ® histamine ® Ý H+ (2) parasympathetic (vagal) ACh ii. enteroglucagons: glicentin, oxyntomodulin, GLP1&2 (glucagon-like peptides) & galanin inhibit gastric parietal cells (i.e. acid) (1) proglucagon gives rise to glucagon (pancreas) or glicentin and GLP1&2 (intestine) (a) glicentin gives rise to oxyntomodulin (i) both glicentin and oxyntomodulin contain glucagon b. gastric pepsin i. gastrin, CCK (cholecystokinin), secretin & VIP (Vasoactive Intestinal Peptide) 3. intestinal secretion a. H2O and ions i. VIP ii. PYY (peptide YY) inhibits intestinal and pancreatic exocrine secretions (1) opioids stimulate intestinal absorption of Na+ and Cl- 4. pancreatic secretion a. H2O and CO3H- i. secretin b. enzymes i. 1o by CCK, also by secretin, substance P, GRP ii. pancreatic polypeptide (PP) inhibits exocrine and bile secretion 5. liver / bile a. most peptides of the secretin/glucagon & gastrin/CCK families 6. virtually all exocrine secretions are inhibited by somatostatin B. Hormones that affect endocrine secretions 1. CCK & glucagon/secretin families stimulate insulin & somatostatin 2. GRP stimulates virtually all gastrointestinal peptides 3. Somatostatin inhibits almost all other gastrointestinal peptides C. Hormones that control motility 1. stimulate movement (peristalsis, churning) a. motilin, GRP, gastrin, CCK, neurotensin 2. inhibit motility a. glucagon, GIP (gastric inhibitory peptide or glucose-dependent insulinotropic peptide), VIP, secretin, somatostatin b. b2-adrenergic receptors stimulated by sympathetic NE D. Stimulate gastrointestinal growth 1. epithelial cells (replacements) in GI tract and pancreas 2. stimulate DNA synthesis and cell division a. gastrin, CCK, GRP 3. inhibit growth: VIP, somatostatin E. Regulate blood flow 1. increase gastric, pancreatic, and/or intestinal blood flow a. gastrin, CCK, secretin, glucagon, neurotensin, VIP, & substance P 2, NPY (neuropeptide Y) reduces local blood flow and enhance adrenergic vasoconstriction a. colocalized with NE in a distinct population of noradrenergic neurons i. colocalized with CCK and somatostatin in enteric neurons F. Peptides ® Membrane Receptors 1. VIP, secretin: AC / cAMP 2. CCK, GRP, substance P, TRH: IP3 / Ca++ G. affect secretion in circulatory, respiratory, urogenital systems, control liver metabolism, exert various effects in the CNS including regulation of food intake