Endocrinology, lecture on Gut Hormones
USD Department of Biology
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 ®  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

XXVIII. Guts 'n Brains