Rat pancreatic response to intestinal infusion of intact and hydrolyzed protein

Green, G. M.; Miyasaka, Kyoko

doi:10.1152/ajpgi.1983.245.3.g394

Cited by 19 publications

(15 citation statements)

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“…Pancreatic secretion in conscious rats is characterized by highly parallel secretion of protein and fluid when stimulated by dietary protein (casein), fat, trypsin inhibitors, diversion of bile-pancreatic juice from the intestine (6,21,24,36,40), and stimulation by vagal efferent discharge (1,11,23). Such a pattern in the present study was reproduced by CCK-58 but not by CCK-8.…”

Section: Discussionsupporting

confidence: 49%

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Yamamoto¹,

Reeve²,

Keire³

et al. 2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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Pancreatic secretion of protein, water, chloride, and bicarbonate under basal conditions and in response to intravenous and intraduodenal stimuli were studied in awake rats fully recovered from surgery. During the basal phase of pancreatic secretion, protein output and water output were weakly correlated or uncorrelated, consistent with separate regulation and distinct cellular origin of enzyme (acinar cells) and water (duct cells), referred to as the two-component paradigm of pancreatic secretion. When pancreatic secretion was stimulated physiologically, water and protein output abruptly became strongly and significantly correlated, suggesting that protein secretion and water secretion are tightly coupled or that protein secretion is dependent on water secretion. The apparent function of this coupling is to resist or prevent increases in protein concentration as protein output increases. This pattern of secretion was reproduced by intravenous infusion of the CCK-58 form of cholecystokinin, which strongly stimulates pancreatic water and chloride secretion, but not by CCK-8, which only weakly stimulates water and chloride secretion in a non-dose-dependent manner. The remarkably tight association of water and protein secretion in food-stimulated and CCK-58-stimulated pancreatic secretion is consistent with a single cell type as the origin of both water and enzyme secretion, i.e., the acinar cell, and is not consistent with the two-component paradigm of pancreatic secretion. Because CCK-58 is the only detectable endocrine form of cholecystokinin in the rat and its bioactivity pattern is markedly and qualitatively different from CCK-8, actions previously recorded for CCK-8 should be reexamined.

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Section: Discussionsupporting

confidence: 49%

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Yamamoto¹,

Reeve²,

Keire³

et al. 2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…The diluted intestinal secretions (intestinal washout) were collected on ice and at the end of the collection period (5 hr), the washout was boiled for 10 min, cooled, and then filtered through Whatman no. 4 Male Wistar rats were prepared with pancreatic, biliary, duodenal, and jugular vein cannulae as described in detail elsewhere (19). The bioassay for CCK-releasing activity was a modification of the methods described by Miyasaka et al (20).…”

Section: And Latermentioning

confidence: 99%

Purification and characterization of a luminal cholecystokinin-releasing factor from rat intestinal secretion.

Spannagel

Green

Guan

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

104

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Cholecystokinin (CCK) secretion in rats and humans is inhibited by pancreatic proteases and bile acids in the intestine. It has been hypothesized that the inhibition of CCK release caused by pancreatic proteases is due to proteolytic inactivation of a CCK-releasing peptide present in intestinal secretion. To purify the putative luminal CCK-releasing factor (LCRF), intestinal secretions were collected by perfusing a modified Thiry-Vella fistula of jejunum in conscious rats. From these secretions, the peptide was concentrated by ultrafiltration followed by low-pressure reverse-phase chromatography and purified by reverse-phase high-pressure liquid chromatography. Purity was confirmed by high-performance capillary electrophoresis. Fractions were assayed for CCK-releasing activity by their ability to stimulate pancreatic protein secretion when infused into the proximal small intestine of conscious rats. Partially purified fractions strongly stimulated both pancreatic secretion and CCK release while CCK receptor blockade abolished the pancreatic response. Amino acid analysis and mass spectral analysis showed that the purified peptide is composed of 70-75 amino acid residues and has a mass of 8136 Da. Microsequence analysis of LCRF yielded an amino acid sequence for 41 residues as follows: STFWAYQPDGDNDPTDYQKYEHTSSPSQLLAPGDYPCVIEV. When infused intraduodenally, the purified peptide stimulated pancreatic protein and fluid secretion in a dose-related manner in conscious rats and significantly elevated plasma CCK levels. Immunoaffinity chromatography using antisera raised to synthetic LCRF-(1-6) abolished the CCK releasing activity of intestinal secretions. These studies demonstrate, to our knowledge, the first chemical characterization of a luminally secreted enteric peptide functioning as an intraluminal regulator of intestinal hormone release.

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“…In dogs (Meyer and Kelly, 1976) and humans (Thimister et al, 1996) amino acids and peptides are more effective than intact proteins in stimulating pancreatic exocrine secretion. However, trypsin secretion is more stimulated by intact proteins than by hydrolyzed proteins or amino acids in rats (Green and Miyasaka, 1983), fishes (Cahu et al, 2004) and insects Lehane et al, 1995). In order to study Site numbers start at the first residue of lobster trypsinogens (Perera et al, 2010a).…”

Section: Signals For Trypsin Secretion and Expressionmentioning

confidence: 99%

Dietary protein quality differentially regulates trypsin enzymes at the secretion and transcription level in Panulirus argus by distinct signaling pathways

Perera

Rodríguez-Viera

Rodríguez-Casariego

et al. 2012

Journal of Experimental Biology

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with the results of previous digestibility studies (Ward et al., 2003; Irving and Williams, 2007;Perera et al., 2010b). Poor protein use could be related to some impairment in digestive progression when lobsters are fed on pelleted diets (Simon and Jeffs, 2008;Simon, 2009).The aim of the present work was to assess the effect of feeding P. argus with different protein sources on trypsin expression and secretion. Our results demonstrate that trypsin enzymes are differentially regulated at the transcription and secretion level by ingested proteins. Additionally, we provide evidence that intact proteins, rather than small peptides or free amino acids, are the major signal eliciting the prandial secretory response in lobster, whereas SUMMARYThe effects of pelleted diets with different protein composition (fish, squid or soybean meals as main protein sources) on trypsin secretion and expression were studied in the lobster Panulirus argus. Trypsin secretion was shown to be maximal 4h after ingestion. At this time, fish-and squid-based diets induced trypsin secretion, as well as up-regulation of the major trypsin isoform at the transcription level. While fish-and squid-based diets elicited a prandial response, soybean-based diet failed to stimulate the digestive gland to secrete trypsin into the gastric fluid or induce trypsin expression above the levels observed in fasting lobsters. In vitro assays showed that intact proteins rather than protein hydrolysates stimulate trypsin secretion in the lobster. However, the signal for trypsin transcription appears to be different to that for secretion and is probably mediated by the appearance of free amino acids in the digestive gland, suggesting a stepwise regulation of trypsin enzymes during digestion. We conclude that trypsin enzymes in P. argus are regulated at the transcription and secretion level by the quality of dietary proteins through two distinct signaling pathways. Our results indicate that protein digestion efficiency in spiny lobsters can be improved by selecting appropriated protein sources. However, other factors like the poor solubility of dietary proteins in dry diets could hamper further enhancement of digestion efficiency.

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Rat pancreatic response to intestinal infusion of intact and hydrolyzed protein

Cited by 19 publications

References 0 publications

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8

Purification and characterization of a luminal cholecystokinin-releasing factor from rat intestinal secretion.

Dietary protein quality differentially regulates trypsin enzymes at the secretion and transcription level in Panulirus argus by distinct signaling pathways

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