The mechanism of feedback regulation of cholecystokinin (CCK) secretion by pancreatic proteases will be studied. The purification and characterization of an intestinal CCK-releasing peptide that is hypothesized to mediate protease-specific feedback inhibition of CCK release will be attempted. Acid extracts of porcine proximal small intestinal mucosa will be fractionated by preparative HPLC and the fractions bioassayed for CCK-releasing activity by infusing them intraduodenally in conscious rats. Fractions possessing CCK-releasing activity will be further purified by HPLC until suitable for amino acid sequencing. The peptide will be chemically synthesized and the natural and synthetic peptide will be compared biochemically and physiologically. Physiological studies will be conducted to compare the actions of intestinal CCK-releasing peptide with that of monitor peptide, the CCK-releasing peptide of pancreatic juice. Polyclonal and monoclonal antibodies will be raised to the purified or synthetic intestinal CCK-releasing peptide to be used in immunocytochemical studies to localize the peptide in the small intestine, and to develop a radioimmunoassay (RIA). The RIA will be used to investigate the regulation of the secretion of the CCK-releasing peptide in intestinal juice, using conscious rats with isolated Thiry-Vella fistulas of proximal small intestine. The effect of i.v. infusion of cholinergic and adrenergic blockers, somatostatin, and of intraintestinal infusion of amino acids, fatty acids, glucose and bile acids on secretion of the intestinal CCK-releasing peptide into the Thiry-Vella loop will be studied. The role of CCK in induction and maintenance of pancreatic growth will be studied. Rats adapted to 5% casein diets will be presented with 70% casein diets for 14 days and the effect of administration of the CCK receptor antagonist MK-329 on pancreatic growth in response to 70% casein feeding will be determined. The antagonist will be administered beginning at the onset of feeding the 70% casein diet or beginning 7 days later, to contrast the effect of MK-329 on induction vs maintenance of pancreatic growth. Similar studies will be done using trypsin inhibitor as the dietary trophic stimulus. The results of these studies will provide important basic physiological information about the control of CCK secretion and its influence in gastrointestinal function. These data will help to understand and treat gastrointestinal diseases, particularly pancreatic and gallbladder diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK037482-06
Application #
3236425
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1987-05-01
Project End
1995-04-30
Budget Start
1993-05-01
Budget End
1994-04-30
Support Year
6
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Texas Health Science Center San Antonio
Department
Type
Schools of Medicine
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
Criddle, David N; Booth, David M; Mukherjee, Rajarshi et al. (2009) Cholecystokinin-58 and cholecystokinin-8 exhibit similar actions on calcium signaling, zymogen secretion, and cell fate in murine pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 297:G1085-92
Murphy, John A; Criddle, David N; Sherwood, Mark et al. (2008) Direct activation of cytosolic Ca2+ signaling and enzyme secretion by cholecystokinin in human pancreatic acinar cells. Gastroenterology 135:632-41
Yamamoto, Mitsuyoshi; Reeve Jr, Joseph R; Green, Gary M (2007) Supramaximal CCK-58 does not induce pancreatitis in the rat: role of pancreatic water secretion. Am J Physiol Gastrointest Liver Physiol 292:G964-74
Yamamoto, M; Reeve Jr, J R; Keire, D A et al. (2005) Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8. Am J Physiol Gastrointest Liver Physiol 288:G866-79
Reeve Jr, Joseph R; Liddle, Rodger A; McVey, Douglas C et al. (2004) Identification of nonsulfated cholecystokinin-58 in canine intestinal extracts and its biological properties. Am J Physiol Gastrointest Liver Physiol 287:G326-33
Reeve Jr, Joseph R; Keire, David A; Coskun, Tamer et al. (2003) Synthesis of biologically active canine CCK-58. Regul Pept 113:71-7
Jin, Wei; Green, Gary M (2003) Circulating ethanol does not stimulate pancreatic secretion in conscious rats. Pancreas 27:e90-5
Reeve Jr, Joseph R; Green, Gary M; Chew, Peter et al. (2003) CCK-58 is the only detectable endocrine form of cholecystokinin in rat. Am J Physiol Gastrointest Liver Physiol 285:G255-65
Wang, Yu; Prpic, Vera; Green, Gary M et al. (2002) Luminal CCK-releasing factor stimulates CCK release from human intestinal endocrine and STC-1 cells. Am J Physiol Gastrointest Liver Physiol 282:G16-22
Spannagel, A W; Green, G M (1999) Pancreatic hypersecretion in the jejunal-bypass rat. Pancreas 18:47-52

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