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 Osmo-Pressure Balance Reproductive Endocrinology Prolactin Somatic Axis

Growth Factors Immune System Ca++, PO4 Homeostasis Pancreatic Hormones GI Hormones

Guts 'n Brains Brain Hormones Neurosteroids Neuropeptides Evolution

Figures for Endocrionology text:Vertebrate Endocrinology4th Edition - David O. Norris: Read pages 427-485 for this lecture acronyms    end

XXVII. Gastrointestinal Hormones 			back to XXVI. Glucose Homeostasis


	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