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Plaza A, Merino B, Del Olmo N, Ruiz-Gayo M. The cholecystokinin receptor agonist, CCK-8, induces adiponectin production in rat white adipose tissue. Br J Pharmacol 2019; 176:2678-2690. [PMID: 31012948 DOI: 10.1111/bph.14690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE A cholecystokinin (CCK) system has been identified in white adipose tissue (WAT). Nevertheless, the endocrine actions of CCK on WAT remain unknown. Our goal was to investigate the role of CCK in regulating the production of adiponectin, an adipokine expressed in WAT, which is pivotal in preserving energy homeostasis. EXPERIMENTAL APPROACH The effect of the bioactive CCK fragment CCK-8 on adiponectin production was studied both in vivo and in vitro. CCK-8 effects were characterized in rats treated with selective CCK1 and CCK2 receptor antagonists as well as in pre-adipocytes carrying the selective silencing of either CCK1 or CCK2 receptors. The influence of insulin on CCK-8 responses was also analysed. KEY RESULTS In WAT, CCK-8 increased plasma adiponectin levels and the expression of the adiponectin gene (Adipoq). In pre-adipocytes, CCK-8 up-regulated adiponectin production. CCK-8 effects were abolished by L-365,260, a selective CCK2 receptor antagonist. CCK2 receptor knockdown also abolished the effects of CCK-8 in pre-adipocytes. Moreover, in vitro CCK-8 effects were blocked by triciribine, a specific inhibitor of protein kinase B (Akt) and by the PPARγ antagonist T0070907. Silencing the expression of the insulin receptor inhibited CCK-8-induced Adipoq expression in pre-adipocytes. Furthermore, insulin potentiated the effect of CCK-8. CONCLUSION AND IMPLICATIONS CCK-8 stimulates adiponectin production in WAT by acting on CCK2 receptors, through a mechanism involving both Akt and PPARγ. Moreover, CCK-8 actions are only observed in the presence of insulin. Our results could have translational value in the design of new insulin-sensitizing therapies.
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Affiliation(s)
- Adrián Plaza
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU San Pablo, Madrid, Spain
| | - Beatriz Merino
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU San Pablo, Madrid, Spain
| | - Nuria Del Olmo
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU San Pablo, Madrid, Spain
| | - Mariano Ruiz-Gayo
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU San Pablo, Madrid, Spain
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Reidelberger R, Haver A, Anders K, Apenteng B. Role of capsaicin-sensitive peripheral sensory neurons in anorexic responses to intravenous infusions of cholecystokinin, peptide YY-(3-36), and glucagon-like peptide-1 in rats. Am J Physiol Endocrinol Metab 2014; 307:E619-29. [PMID: 25117406 PMCID: PMC4200310 DOI: 10.1152/ajpendo.00024.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholecystokinin (CCK)-induced suppression of feeding is mediated by vagal sensory neurons that are destroyed by the neurotoxin capsaicin (CAP). Here we determined whether CAP-sensitive neurons mediate anorexic responses to intravenous infusions of gut hormones peptide YY-(3-36) [PYY-(3-36)] and glucagon-like peptide-1 (GLP-1). Rats received three intraperitoneal injections of CAP or vehicle (VEH) in 24 h. After recovery, non-food-deprived rats received at dark onset a 3-h intravenous infusion of CCK-8 (5, 17 pmol·kg⁻¹·min⁻¹), PYY-(3-36) (5, 17, 50 pmol·kg⁻¹·min⁻¹), or GLP-1 (17, 50 pmol·kg⁻¹·min⁻¹). CCK-8 was much less effective in reducing food intake in CAP vs. VEH rats. CCK-8 at 5 and 17 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 39 and 71% in VEH rats and 7 and 18% in CAP rats. In contrast, PYY-(3-36) and GLP-1 were similarly effective in reducing food intake in VEH and CAP rats. PYY-(3-36) at 5, 17, and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 15, 33, and 70% in VEH rats and 13, 30, and 33% in CAP rats. GLP-1 at 17 and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 48 and 60% in VEH rats and 30 and 52% in CAP rats. These results suggest that anorexic responses to PYY-(3-36) and GLP-1 are not primarily mediated by the CAP-sensitive peripheral sensory neurons (presumably vagal) that mediate CCK-8-induced anorexia.
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MESH Headings
- Animals
- Anorexia/metabolism
- Anorexia/physiopathology
- Anorexia/prevention & control
- Behavior, Animal/drug effects
- Capsaicin/administration & dosage
- Capsaicin/toxicity
- Cholecystokinin/administration & dosage
- Cholecystokinin/metabolism
- Disease Models, Animal
- Energy Intake/drug effects
- Feeding Behavior/drug effects
- Glucagon-Like Peptide 1/administration & dosage
- Glucagon-Like Peptide 1/metabolism
- Infusions, Intravenous
- Injections, Intraperitoneal
- Intestinal Mucosa/drug effects
- Intestinal Mucosa/innervation
- Intestinal Mucosa/metabolism
- Intestinal Mucosa/physiopathology
- Intestine, Small/drug effects
- Intestine, Small/innervation
- Intestine, Small/metabolism
- Intestine, Small/physiopathology
- Male
- Neuritis/chemically induced
- Neuritis/metabolism
- Neuritis/physiopathology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Peptide Fragments/administration & dosage
- Peptide Fragments/metabolism
- Peptide YY/administration & dosage
- Peptide YY/metabolism
- Rats
- Vagus Nerve/drug effects
- Vagus Nerve/metabolism
- Vagus Nerve/physiopathology
- Vagus Nerve Diseases/chemically induced
- Vagus Nerve Diseases/metabolism
- Vagus Nerve Diseases/physiopathology
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Affiliation(s)
- Roger Reidelberger
- Veterans Affairs Research Service, Veterans Affairs Nebraska Western Iowa Health Care System, Omaha, Nebraska; and Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| | - Alvin Haver
- Veterans Affairs Research Service, Veterans Affairs Nebraska Western Iowa Health Care System, Omaha, Nebraska; and Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| | - Krista Anders
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| | - Bettye Apenteng
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
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Ahmed ASF, Dai L, Ho W, Ferguson AV, Sharkey KA. The subfornical organ: a novel site of action of cholecystokinin. Am J Physiol Regul Integr Comp Physiol 2014; 306:R363-73. [PMID: 24430886 DOI: 10.1152/ajpregu.00462.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subfornical organ (SFO) is an important sensory circumventricular organ implicated in the regulation of fluid homeostasis and energy balance. We investigated whether the SFO is activated by the hormone cholecystokinin (CCK). CCK₁ and CCK₂ receptors were identified in the SFO by RT-PCR. Dissociated SFO neurons that responded to CCK (40/77), were mostly depolarized (9.2 ± 0.9 mV, 30/77), but some were hyperpolarized (-7.3 ± 1.1 mV, 10/77). We next examined the responses of SFO neurons in vivo to CCK (16 μg/kg ip), in the presence and absence of CCK₁ or CCK₂ receptor antagonists (devazepide; 600 μg/kg and L-365,260; 100 μg/kg, respectively), using the functional activation markers c-Fos and phosphorylated extracellular signal-related kinase (p-ERK). The nucleus of the solitary tract (NTS) served as a control for CCK-induced activity. There was a significant increase in c-Fos expression in the NTS (259.2 ± 20.8 neurons) compared with vehicle (47.5 ± 2.5). Similarly, in the SFO, c-Fos was expressed in 40.5 ± 10.6 neurons in CCK-treated compared with 6.6 ± 2.7 in vehicle-treated rats (P < 0.01). Devazepide significantly reduced the effects of CCK in the NTS but not in SFO. L-365,260 blocked the effects of CCK in both brain regions. CCK increased the number of p-ERK neurons in NTS (27.0 ± 4.0) as well as SFO (18.0 ± 4.0), compared with vehicle (8.0 ± 2.6 and 4.3 ± 0.6, respectively; P < 0.05). Both devazepide and L-365,260 reduced CCK-induced p-ERK in NTS, but only L-365,260 reduced it in the SFO. In conclusion, the SFO represents a novel brain region at which circulating CCK may act via CCK₂ receptors to influence central autonomic control.
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Affiliation(s)
- Al-Shaimaa F Ahmed
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; and
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Goebel-Stengel M, Stengel A, Wang L, Ohning G, Taché Y, Reeve JR. CCK-8 and CCK-58 differ in their effects on nocturnal solid meal pattern in undisturbed rats. Am J Physiol Regul Integr Comp Physiol 2012; 303:R850-60. [PMID: 22874423 DOI: 10.1152/ajpregu.00365.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Various molecular forms of CCK reduce food intake in rats. Although CCK-8 is the most studied form, we reported that CCK-58 is the only detectable endocrine peptide form in rats. We investigated the dark-phase rat chow intake pattern following injection of CCK-8 and CCK-58. Ad libitum-fed male Sprague-Dawley rats were intraperitoneally injected with CCK-8, CCK-58 (0.6, 1.8, and 5.2 nmol/kg), or vehicle. Food intake pattern was assessed during the dark phase using an automated weighing system that allowed continuous undisturbed monitoring of physiological eating behavior. Both CCK-8 and CCK-58 dose dependently reduced 1-h, dark-phase food intake, with an equimolar dose of 1.8 nmol being similarly effective (-49% and -44%). CCK-58 increased the latency to the first meal, whereas CCK-8 did not. The intermeal interval was reduced after CCK-8 (1.8 nmol/kg, -41%) but not after CCK-58. At this dose, CCK-8 increased the satiety ratio by 80% and CCK-58 by 160%, respectively, compared with vehicle. When behavior was assessed manually, CCK-8 reduced locomotor activity (-31%), whereas grooming behavior was increased (+59%). CCK-58 affected neither grooming nor locomotor activity. In conclusion, reduction of food intake by CCK-8 and CCK-58 is achieved by differential modulation of food intake microstructure and behavior. These data highlight the importance of studying the molecular forms of peptides that exist in vivo in tissue and circulation of the animal being studied.
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Affiliation(s)
- Miriam Goebel-Stengel
- CURE: Digestive Diseases Research Center, Digestive Diseases Division, Department of Medicine, University of California, Los Angeles 90073, USA
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Stengel A, Taché Y. Interaction between gastric and upper small intestinal hormones in the regulation of hunger and satiety: ghrelin and cholecystokinin take the central stage. Curr Protein Pept Sci 2011; 12:293-304. [PMID: 21428875 PMCID: PMC3670092 DOI: 10.2174/138920311795906673] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 03/23/2011] [Indexed: 12/13/2022]
Abstract
Several peptides are produced and released from endocrine cells scattered within the gastric oxyntic and the small intestinal mucosa. These peptide hormones are crucially involved in the regulation of gastrointestinal functions and food intake by conveying their information to central regulatory sites located in the brainstem as well as in the forebrain, such as hypothalamic nuclei. So far, ghrelin is the only known hormone that is peripherally produced in gastric X/A-like cells and centrally acting to stimulate food intake, whereas the suppression of feeding seems to be much more redundantly controlled by a number of gut peptides. Cholecystokinin produced in the duodenum is a well established anorexigenic hormone that interacts with ghrelin to modulate food intake indicating a regulatory network located at the first site of contact with nutrients in the stomach and upper small intestine. In addition, a number of peptides including leptin, urocortin 2, amylin and glucagon-like peptide 1 interact synergistically with CCK to potentiate its satiety signaling effect. New developments have led to the identification of additional peptides in X/A-like cells either derived from the pro-ghrelin gene by alternative splicing and posttranslational processing (obestatin) or a distinct gene (nucleobindin2/nesfatin-1) which have been investigated for their influence on food intake.
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Affiliation(s)
- Andreas Stengel
- Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division UCLA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Yvette Taché
- Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division UCLA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
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Stengel A, Keire D, Goebel M, Evilevitch L, Wiggins B, Taché Y, Reeve JR. The RAPID method for blood processing yields new insight in plasma concentrations and molecular forms of circulating gut peptides. Endocrinology 2009; 150:5113-8. [PMID: 19819958 PMCID: PMC2775981 DOI: 10.1210/en.2009-0697] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The correct identification of circulating molecular forms and measurement of peptide levels in blood entails that the endocrine peptide being studied is stable and recovered in good yields during blood processing. However, it is not clear whether this is achieved in studies using standard blood processing. Therefore, we compared peptide concentration and form of 12 (125)I-labeled peptides using the standard procedure (EDTA-blood on ice) and a new method employing Reduced temperatures, Acidification, Protease inhibition, Isotopic exogenous controls, and Dilution (RAPID). During standard processing there was at least 80% loss for calcitonin-gene-related peptide and cholecystokinin-58 (CCK-58) and more than 35% loss for amylin, insulin, peptide YY forms (PYY((1-36)) and PYY((3-36))), and somatostatin-28. In contrast, the RAPID method significantly improved the recovery for 11 of 12 peptides (P < 0.05) and eliminated the breakdown of endocrine peptides occurring after standard processing as reflected in radically changed molecular forms for CCK-58, gastrin-releasing peptide, somatostatin-28, and ghrelin. For endogenous ghrelin, this led to an acyl/total ghrelin ratio of 1:5 instead of 1:19 by the standard method. These results show that the RAPID method enables accurate assessment of circulating gut peptide concentrations and forms such as CCK-58, acylated ghrelin, and somatostatin-28. Therefore, the RAPID method represents an efficacious means to detect circulating variations in peptide concentrations and form relevant to the understanding of physiological function of endocrine peptides.
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Affiliation(s)
- Andreas Stengel
- University of California and CURE Digestive Disease Research Center, Building 115, Room 117, Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, California 90073, USA
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8
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Antiobesity effect of recombinant human caseinomacropeptide in Sprague-Dawley rat. BIOTECHNOL BIOPROC E 2005. [DOI: 10.1007/bf02932020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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Garthoff LH, Henderson GR, Sager AO, Sobotka TJ, Gaines DW, O'Donnell MW, Chi R, Chirtel SJ, Barton CN, Brown LH, Hines FA, Solomon T, Turkleson J, Berry D, Dick H, Wilson F, Khan MA. Pathological evaluation, clinical chemistry and plasma cholecystokinin in neonatal and young miniature swine fed soy trypsin inhibitor from 1 to 39 weeks of age. Food Chem Toxicol 2002; 40:501-16. [PMID: 11893409 DOI: 10.1016/s0278-6915(01)00121-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The potential toxicity of dietary soy trypsin inhibitor (TI) was evaluated in neonatal miniature swine. From 1 to 6 weeks of age, two groups of male piglets were artificially reared in an Autosow and automatically fed either TI or control liquid diet. From 6 to 39 weeks of age, these two groups were fed either TI or control chow diet. A third group, sow control (SC), suckled from birth to 6 weeks of age, were also weaned to control chow from 6 to 39 weeks of age. Clinical chemistry and plasma cholecystokinin (CCK) determined at 6, 18, 30 and 39 weeks of age, and serum amylase activity with gross and histopathological analyses of major organs at 6 and 39 weeks of age are reported. TI had no effect on plasma CCK, serum amylase activity, or numerous clinical chemistry values. TI-fed piglets had a larger relative liver weight at 6 weeks of age. Relative pancreas weight decreased with age but was not affected by TI. Gross and histopathological analyses of major organs, except the spleen, were within normal limits. Increased incidence of extramedullary hematopoiesis was noted in the spleen of the TI group at 6 but not at 39 weeks of age. There was no consistent pattern in immunohistochemical foci for secretin, gastrin releasing polypeptide or CCK, and no change in DNA, RNA, mitotic index or nuclear density of pancreatic cells. At 6 weeks of age, TI increased pancreatic protein and amylase activity but not trypsin or chymotrypsin activity. None of the effects suggested that this dose of TI was toxic to either the neonatal or sexually mature miniature male swine.
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Affiliation(s)
- L H Garthoff
- US Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Toxicological Research and Nutritional Product Studies, Muirkirk Research Center, 8301 Muirkirk Road, Laurel, MD 20708, USA.
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Blevins JE, Hamel FG, Fairbairn E, Stanley BG, Reidelberger RD. Effects of paraventricular nucleus injection of CCK-8 on plasma CCK-8 levels in rats. Brain Res 2000; 860:11-20. [PMID: 10727619 DOI: 10.1016/s0006-8993(99)02478-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of the study was to determine whether paraventricular nucleus (PVN) injection of an anorexic 500-pmol dose of cholecystokinin (CCK)-8 could increase plasma CCK-8 levels sufficiently to suppress feeding by a peripheral mechanism. Rats received PVN injections of CCK-8 either alone or with 3H-labelled propionylated CCK-8 (3H-pCCK-8) and plasma samples were taken at various times from 3 to 120 min post-injection. Plasma CCK-8 levels were estimated from measurements of both total plasma CCK-like immunoreactivity (CCK-LI) and 3H-pCCK-8 activity. PVN injections of CCK-8 and 3H-pCCK-8 produced estimated peak increases in plasma CCK-8 of 15+/-11 and 22+/-3 pM, respectively. The i.v. infusion of CCK-8 doses (0.2 and 1 nmol/kg h) that bracketed the threshold dose for suppression of feeding, increased plasma CCK-LI from a basal level of 6+/-1 to 49+/-10 and 166+/-36 pM, respectively. The i.v. injections of 600 and 4800 pmol of CCK-8 did not suppress feeding. These results suggest that PVN injection of an anorexic 500-pmol dose of CCK-8 does not increase plasma CCK-8 levels sufficiently to suppress feeding by a peripheral mechanism.
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Affiliation(s)
- J E Blevins
- Veterans Administration Medical Center, Omaha, NE, USA
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Rehfeld JF. How to measure cholecystokinin in tissue, plasma and cerebrospinal fluid. REGULATORY PEPTIDES 1998; 78:31-9. [PMID: 9879744 DOI: 10.1016/s0167-0115(98)00133-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This review examines a major problem for an old hormone. Hormones are defined by the ability to reach their targets via blood. Consequently, knowledge about a hormone requires measurement of its behaviour in blood. So far, however, it has proven exceptionally difficult to measure the classical gut hormone, cholecystokinin (CCK), in circulation. The review therefore describes the premises for reliable plasma CCK measurements as compared to the premises for measurement in tissue extracts and cerebrospinal fluid. The critical plasma premises comprise equimolar quantitation of the bioactive CCK peptides in circulation (CCK-83, -58, -33, -22 and -8) without interference from homologous gastrin peptides. The latter may appear nearly impossible, because the bioactive epitopes of CCK and gastrin are almost identical, and because the plasma concentrations of gastrin are more than tenfold above those of CCK. In comparison, measurement of CCK in tissue is considerably simpler, especially in extracts of the two main production sites, the brain and jejunoileal mucosa. For cerebrospinal fluid, degradation, low levels and shortage of material constitute major problems so that the molecular nature and biological/clinical relevance of CCK measurements in CSF still remain to be settled. The review finally enlists the reports on plasma CCK measurements published so far. A multitude of different immuno- and bioassays have been used with corresponding variation in the results. The theory for different types of assays in combination with general assay experience suggest that accurate CCK measurements require radioimmunoassay technology based on high-affinity antibodies. These antibodies have to be exquisitely specific for the 0-sulfated C-terminal heptapeptide amide of CCK without binding the similar gastrin epitope. Only few of such antibodies have been raised.
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Affiliation(s)
- J F Rehfeld
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Denmark.
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Baldwin BA, Parrott RF, Ebenezer IS. Food for thought: a critique on the hypothesis that endogenous cholecystokinin acts as a physiological satiety factor. Prog Neurobiol 1998; 55:477-507. [PMID: 9670215 DOI: 10.1016/s0301-0082(98)00005-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This review evaluates the various lines of evidence supporting the hypothesis that cholecystokinin (CCK) released from the small intestine during feeding plays a physiological satiety. Issues considered include, the effects of systemic injection of CCK on consummatory and operant feeding, the role of the vagus nerve, the effects of CCKB receptor antagonists, and the neuroendocrine responses to exogenous CCK. A critical appraisal of this research indicates that while it is clearly demonstratable that exogenous peripheral CCK can alter food intake by acting on CCKA receptors, the mechanism involved may be more closely related to the induction if aversion and nausea, rather than satiety. With regard to peripheral endogenous CCK, the available evidence also does not seem to support a role for the hormone in satiety. In particular, it is doubtful whether plasma concentrations of CCK following a meal are sufficiently high to inhibit feeding. Moreover, CCKA receptor antagonist which do not cross the blood brain barrier fail to increase meal size, as would be expected if peripheral CCK was an effective satiety factor. In addition, the recent literature concerned with the possibility that CCK may have a direct action within the brain in the control of food intake has been reviewed. These studies show that CCK administered intracerebroventicularly, or by micoinjection into discrete brain regions, also inhibits feeding via a CCKA receptor mechanism. However, the physiological relevance of these findings have yet to be determined.
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Affiliation(s)
- B A Baldwin
- Neuro-Behaviour Biology Center, Institute of Science and Technology for Development, Mahidol University, Salaya, Thailand
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Affiliation(s)
- Rodger A Liddle
- Department of Medicine, Box 3913, Duke University Medical Center, Durham, NC 27710, Fax 919-684-8857
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Abstract
AbstractShortage of reliable plasma assays has hampered studies of cholecystokinin (CCK). The assay problems are low plasma concentrations, extensive molecular heterogeneity, and close homology of CCK to gastrin, which circulates in higher concentrations. To develop an accurate CCK RIA, antibodies were raised in rabbits, guinea pigs, and mice in titers from 200 to 4 000 000. The specificity of the antisera was tested with homologous peptides, and tissue and plasma extracts. Rabbit 92128 produced antibodies in high titer (≥500 000) with sufficient avidity (K \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(_{eff}^{{^\circ}}\) \end{document} ≥ 1012 mol−1) and the desired specificity. The antiserum binds the bioactive forms of CCK with equimolar potency and displays no reactivity with gastrin. CCK concentrations in plasma from healthy humans rose from 1.13 ± 0.10 pmol/L (mean ± SE, n = 26) to 4.92 ± 0.34 pmol/L after a mixed meal. Chromatography of human plasma revealed traces of CCK-58, a predominance of CCK-33 and CCK-22, and moderate amounts of CCK-8. The results show that it is possible to produce specific CCK-antisera using a sulfated CCK-12 analog.
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Affiliation(s)
- Jens F Rehfeld
- Dept. of Clinical Biochemistry, Rigshospitalet, DK-2100 Copenhagen, Denmark
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Backus RC, Rosenquist GL, Rogers QR, Calam J, Morris JG. Elevation of plasma cholecystokinin (CCK) immunoreactivity by fat, protein, and amino acids in the cat, a carnivore. REGULATORY PEPTIDES 1995; 57:123-31. [PMID: 7659788 DOI: 10.1016/0167-0115(95)00027-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The cat requires a diet high in protein and certain nutrients that are found only in animal tissue. It is possible that secretogogues of intestinal CCK in the cat may be different from those observed in non-carnivorous species. Plasma CCK concentrations were determined in cats (n = 6) given by oral-gastric tube either casein, whey protein, corn oil, or corn starch suspended in water. CCK was measured by RIA with a tyrosine sulfate-specific, C-terminal antibody, DINO. HPLC of plasma revealed that most CCK-immunoreactivity (CCK-LI) was associated with CCK-33 and a late eluting peak, presumably CCK-58. Casein, whey protein, and corn oil increased (P < 0.05) post-administration plasma CCK-LI, and at least for casein, the effect was dose related. An amino acid mixture approximating the residue composition of casein increased plasma CCK-LI (P < 0.05), however, the increase tended to be less than that caused by casein. Evaluation of post-administration levels of plasma amino acids indicated that intact protein and amino acids in the intestinal lumen affect CCK release by different mechanisms. Collectively, the results indicated that although cats are carnivores cats and humans secrete CCK in response to the same nutrients.
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Affiliation(s)
- R C Backus
- Department of Molecular Biosciences, University of California, Davis 95616, USA
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Beucher S, Levenez F, Yvon M, Corring T. Effects of gastric digestive products from casein on CCK release by intestinal cells in rat. J Nutr Biochem 1994. [DOI: 10.1016/0955-2863(94)90012-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Schmidt WE, Schenk S, Nustede R, Holst JJ, Fölsch UR, Creutzfeldt W. Cholecystokinin is a negative regulator of gastric acid secretion and postprandial release of gastrin in humans. Gastroenterology 1994; 107:1610-20. [PMID: 7958670 DOI: 10.1016/0016-5085(94)90799-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND/AIMS The role of cholecystokinin (CCK) in the regulation of gastric acid secretion is still controversial. This study examined the effect of the CCK-A receptor antagonist loxiglumide (lox) on gastrin- or CCK-induced gastric acid secretion and meal-stimulated plasma gastrin levels in a placebo-controlled study. METHODS Acid output was studied in eight subjects who received intravenously gastrin-17 (15, 30, and 60 pmol.kg-1.h-1); gastrin-17 plus lox; cholecystokinin octapeptide (CCK-8) (15, 30, and 60 pmol.kg-1.h-1); CCK-8 plus lox; or gastrin plus CCK-8. Sham feeding-induced acid output and meal-stimulated gastrin secretion were studied during lox infusion. RESULTS Gastrin-17 dose-dependently stimulated acid output to near-maximal levels. CCK-8 (15 pmol.kg-1.h-1) increased acid secretion 2.5-fold over basal; higher infusion rates had less or no effect. When combined with lox, CCK-8 produced a near-maximal acid response (6-fold over basal). CCK-8 together with gastrin-17 inhibited gastrin-induced acid output by 67%. Meal-stimulated plasma gastrin concentrations were elevated 3.2-fold, whereas sham feeding-induced acid secretion was not modified by lox. CONCLUSIONS Blockade of CCK-A receptors converts CCK-8 into a potent acid secretagogue and augments postprandial gastrin secretion. A CCK-mediated stimulation of paracrine somatostatin secretion from antral and fundic D cells represents a candidate mechanism for the inhibition of the parietal and gastrin cell in humans.
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Affiliation(s)
- W E Schmidt
- First Department of Medicine, Christian-Albrechts-University, Kiel, Germany
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18
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Höcker M, Schmidt WE, Creutzfeldt W, Choudhury AR, Nustede R, Schafmayer A, Fölsch UR. Determination of plasma cholecystokinin (CCK) concentrations by bioassay and radioimmunoassay in man. A critical evaluation. REGULATORY PEPTIDES 1992; 37:255-69. [PMID: 1557514 DOI: 10.1016/0167-0115(92)90619-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The present investigation was designed to perform a direct comparison of a rat pancreatic acini bioassay system and a specific CCK radioimmunoassay (antiserum G-160) for the measurement of fasting and meal-stimulated plasma CCK in the presence and absence of the CCK receptor antagonist loxiglumide. The G-160 CCK antiserum is directed against the C-terminal O-sulfated tyrosine residue of the CCK molecule which is essential for full bioactivity of CCK peptides. For plasma extraction prior to bioassay measurement, hydrophobic reverse-phase chromatography on octadecylsilane cartridges was employed and resulted in simultaneous adsorption and elution of both CCK peptides and loxiglumide with recoveries of 87.5 +/- 9% and 75.0 +/- 5.9%, respectively. In the absence of loxiglumide, fasting and meal-stimulated values for CCK-like bioactivity and CCK-immunoreactivity (IR-CCK) were nearly identical (basal values: 1-2 pmol/l; meal-stimulated plateau levels: 4-6 pmol/l). After intravenous infusion of loxiglumide (30 mg/kg/h for 10 min, 10 mg/kg/h thereafter), resulting in plasma steady state levels of 200-300 mumol/l, meal-stimulated CCK-like bioactivity was undetectable, whereas IR-CCK levels were augmented 6.5-fold. In the bioassay system, standard samples containing 50 mumol/l loxiglumide produced complete inhibition of acinar lipase release in response to 50 pmol/l synthetic CCK-8. We conclude, that postprandial circulating non-CCK-like factors do not contribute significantly to the direct receptor-mediated stimulation of exocrine pancreatic secretion. The good agreement of CCK-like bioactivity and IR-CCK levels in the absence of loxiglumide confirms the sensitive and specific recognition of bioactive CCK peptides by the G-160 antiserum and suggests that this antibody exerts binding characteristics probably similar to a pancreatic acinar receptor.
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Affiliation(s)
- M Höcker
- Department of Medicine, University Hospital, Georg-August-University of Göttingen, Germany
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19
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Schmidt WE, Creutzfeldt W, Höcker M, Nustede R, Choudhury AR, Schleser A, Rovati LC, Fölsch UR. Cholecystokinin receptor antagonist loxiglumide modulates plasma levels of gastro-entero-pancreatic hormones in man. Feedback control of cholecystokinin and gastrin secretion. Eur J Clin Invest 1991; 21:501-11. [PMID: 1752290 DOI: 10.1111/j.1365-2362.1991.tb01402.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effect of the potent specific cholecystokinin (CCK) receptor antagonist loxiglumide on meal-stimulated plasma concentrations of CCK, gastrin, pancreatic polypeptide (PP), neurotensin, glucose-dependent insulinotropic polypeptide (GIP), insulin and C peptide was investigated in a placebo-controlled study in 10 healthy male volunteers. Intravenous infusion of loxiglumide (10 mg kg-1 h-1) significantly augmented integrated incremental IR-CCK levels 7.3-fold after stimulation by a standard breakfast (504 +/- 54 vs 3.665 +/- 365 pmol-1 135 min-1, P less than 0.001), as measured by a specific CCK radioimmunoassay. Basal IR-CCK concentrations were not affected by administration of loxiglumide. Oral treatment with bile acids (2 g ursodeoxycholic acid plus 2 g chenodeoxycholic acid) together with the meal abolished this augmentation, whereas high-dose substitution with pancreatic enzymes (4.2 g pancreatin) reduced elevated IR-CCK levels by only 38%. CCK-like bioactivity, determined by a bioassay using rat pancreatic acini, was not detectable in all samples that contained loxiglumide at plasma concentrations of 100-250 micrograms ml-1. Plasma gastrin concentrations in response to the breakfast were elevated 3.2-fold during loxiglumide infusion and not influenced by substitution with bile acids or pancreatic enzymes. Meal-stimulated integrated incremental plasma PP concentrations were significantly suppressed (55-65% inhibition, P less than 0.01) by loxiglumide. Infusion of the CCK receptor antagonist only slightly increased postprandial peak plasma glucose, insulin and C-peptide levels, whereas GIP and neurotensin levels were not significantly influenced. These findings suggest: (i) CCK secretion is under feedback control by intraduodenal bile acids and to a lesser extent by pancreatic enzymes; (ii) simultaneous extraction of CCK and loxiglumide results in circulating plasma CCK-like bioactivity of zero; (iii) gastrin secretion is feedback controlled via an indirect mechanism probably involving CCK-induced somatostatin secretion; (iv) release of PP is under inhibitory control of CCK; (v) CCK does not play a major role as insulinotropic hormone in the entero-insular axis in humans.
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Affiliation(s)
- W E Schmidt
- Department of Medicine, University Hospital, Georg August University, Göttingen, Germany
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20
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Izzo RS, Pellecchia C, Weinstein MI, Massimillo AJ. Preparation and characterization of a fully active biotinylated probe of cholecystokinin. PREPARATIVE BIOCHEMISTRY 1990; 20:205-17. [PMID: 2287607 DOI: 10.1080/00327489008050197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this study we describe the synthesis and purification of biotinylated cholecystokinin-8 (Bio-CCK-8) and characterize its use as a probe for the pancreatic cholecystokinin receptor. CCK-8 (0.1 umoles) was reacted with either radiolabeled d-[8,9(-3)H]biotin succinimide ester (0.5 umoles) or N-hydroxysuccinimidyl-biotin in dimethylformamide and triethylamine, and purified by anion exchange chromatography. Concentrations of Bio-CCK-8 and CCK-8 needed for half-maximal inhibition of [125]I-CCK-8 binding to pancreatic membranes were the same (1.0 and 1.3 nM). Bio-CCK-8 retained full biological activity as determined by stimulation of pancreatic protein secretion from rats, and the biotin group bound to CCK-8 retained its high sensitivity for avidin.
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Affiliation(s)
- R S Izzo
- Department of Medicine, Nassau County Medical Center, East Meadow, New York 11554
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21
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Turrigiano GG, Selverston AI. A cholecystokinin-like hormone activates a feeding-related neural circuit in lobster. Nature 1990; 344:866-8. [PMID: 2330042 DOI: 10.1038/344866a0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The peptide hormone cholecystokinin (CCK) contributes to the production of feeding-related behaviour in mammals, but the mechanism by which it exerts its effects remains unclear. The gastric mill neural circuit of lobster is an experimentally accessible model system for studying the hormonal control of feeding-related behaviour. Composed of 11 identified neurons, this circuit produces rhythmic movement of teeth within the stomach. We have previously shown that the gastric mill motor pattern can be modulated by a cholecystokinin-like peptide in vitro. We report here that (1) after feeding, levels of CCK-like peptide in haemolymph increase with the activation of the gastric mill, (2) injections of CCK activate the gastric mill, and (3) a specific CCK antagonist inhibits feeding-induced gastric mill activity. This neatly demonstrates a casual link between in vivo release of a peptide hormone and activation of a neural circuit.
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Affiliation(s)
- G G Turrigiano
- Department of Biology, University of California, San Diego, La Jolla 92093
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22
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Lindén A, Carlquist M, Hansen S, Uvnäs-Moberg K. Plasma concentrations of cholecystokinin, CCK-8, and CCK-33, 39 in rats, determined by a method based on enzyme digestion of gastrin before HPLC and RIA detection of CCK. Gut 1989; 30:213-22. [PMID: 2703143 PMCID: PMC1378304 DOI: 10.1136/gut.30.2.213] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A new specific method for determination of cholecystokinin, CCK-8, and CCK-33, 39 in rat plasma is described. Plasma CCK radioimmunoassay (RIA) is difficult, because of cross-reactivity with gastrin. In the rat, problems because of difficulties in separating gastrin from CCK by high performance liquid chromatography (HPLC) exist. These were solved by enzyme digestion of gastrin before HPLC separation of molecular variants of CCK from gastrin fragments. Cholecystokinin immunoreactive forms in the HPLC fractions were determined by an antibody, which recognises the carboxyl terminus of CCK and gastrin. Fasting concentrations of small (CCK-8) and large (CCK-33, 39) molecular forms of CCK averaged 1.9 (0.3) pM and were raised to 13.4 (3.8) pM in rats fed ad libitum. Cholecystokinin in lactating rats rose two-fold after suckling, compared with 2.8 fold in response to feeding. The basal ratio between CCK-8 and CCK-33, 39 was approximately 1:1, but increased in favour of CCK-8 after feeding and in response to suckling. Gastrin like immunoreactivity measured in unextracted plasma was found to rise after feeding, but was unchanged in response to suckling.
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Affiliation(s)
- A Lindén
- Department of Pharmacology, Karolinska Institute, Stockholm, Sweden
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23
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Cox KL, Rosenquist GL, Iwahashi CK, Benisek WF, Reeve JR, Shively JE, Lee T, Huebner VD. Identification of serotonin from rabbit upper stomach as a stimulant of in vitro gallbladder contraction. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 967:364-72. [PMID: 3196756 DOI: 10.1016/0304-4165(88)90099-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Using an in vitro rabbit gallbladder bioassay, the distribution and identification of bioactive substances in rabbit gastrointestinal tract were investigated. Comparison of the bioactivities of tissue extracts before and after cholecystokinin was removed by affinity chromatography demonstrated that the distributions of cholecystokinin and non-cholecystokinin substances were different. While cholecystokinin bioactivity per g of tissue was highest in the duodenum, non-cholecystokinin bioactivity was greatest in the upper stomach. The biochemical properties of the non-cholecystokinin substance in the upper stomach could not be distinguished from those of serotonin. These included molecular weights of 176, identical ultraviolet spectra, similar nuclear magnetic resonance spectra, and co-chromatography in HPLC. By weight, serotonin had 1/6th of the bioactivity of cholecystokinin octapeptide. We conclude that the principal gallbladder-contracting substance in rabbit upper stomach is serotonin.
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Affiliation(s)
- K L Cox
- Department of Pediatrics, University of California, Davis
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24
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Bado A, Rodriguez M, Lewin MJ, Martinez J, Dubrasquet M. Cholecystokinin suppresses food intake in cats: structure-activity characterization. Pharmacol Biochem Behav 1988; 31:297-303. [PMID: 3244706 DOI: 10.1016/0091-3057(88)90349-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Our experimental models in this study were cats fitted with gastric fistulae. Intravenous infusion of sulfated CCK 8 and nonsulfated Boc CCK 7 inhibited both sham-feeding and feeding in fasted cats. The threshold dose (1.2 pmol/kg.hr) required for inhibition of sham-feeding was identical to that required to inhibit feeding in the same animals. However, the gastric secretory studies indicated that this dose was 90 times lower than the threshold dose stimulating gastric acid secretion (109 pmol/kg.hr). In nonfasted animals, sulfated CCK 8 and nonsulfated Boc CCK 7 (219 and 875 pmol/kg.hr) are both capable of decreasing the food intake at different intervals following the infusion with no significant effect on daily food intake. Our findings clearly show that there is no difference in the sensitivity of CCK's ability to inhibit sham-feeding and feeding, suggesting that CCK's suppressive effect on food intake does not solely involve gastric distension mechanisms. In contrast to gastric acid secretion, the sulfate group is not a "restrictive" factor for peripherally-induced CCK satiety.
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Affiliation(s)
- A Bado
- INSERM U.10, Hôpital Bichat, Paris, France
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25
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Colombel JF, Sutton A, Chayvialle JA, Modigliani R. Cholecystokinin release and biliopancreatic secretion in response to selective perfusion of the duodenal loop with aminoacids in man. Gut 1988; 29:1158-66. [PMID: 3197988 PMCID: PMC1434373 DOI: 10.1136/gut.29.9.1158] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The aim of this study was to measure the role of the duodenal loop in biliopancreatic secretion in man by infusing various stimuli at the ampulla of Vater and collecting duodenal contents at the ligament of Treitz, above an occluding balloon. Perfusion at 10 ml/min of a first mixture of aminoacids - phenylalanine (47.2 mmol), methionine (38.2 mmol), tryptophan (11 mmol), valine (61.6 mmol) - increased cholecystokinin (CCK) plasma concentrations and duodenal bile salt output (p less than 0.005) as compared with a control electrolyte solution, but did not change pancreatic enzyme secretion significantly; duodenal infusion of another aminoacid mixture - arginine (32.4 mmol), histidine (14.1 mmol), leucine (36 mmol), isoleucine (21.5 mmol), lysine (31 mmol), threonine (23 mmol) - did not change CCK plasma concentrations, bile salt or pancreatic enzyme output. The respective role of duodenal distension and endogenous CCK was investigated by perfusing the first aminoacid solution and the control solution at 2, 5, and 10 ml/min. Changing the perfusion rate of control solution from 2 to 5 ml/min led to a significant increase (p less than 0.01) in pancreatic secretion with no further increase at 10 ml/min. Bile salt output was not influenced by the perfusion rate of control solution. During the perfusion of the aminoacid solution, despite a stepwise increase in CCK release, the only significant change in pancreatic secretion was an increase of lipase output (p less than 0.05) when the infusion rate was raised from 2 to 5 ml/min. Our results suggest that duodenal CCK release (1) depends on the nature of aminoacids (2) has predominant role in the regulation of pancreatic secretion at low perfusion rate but is less effective when superimposed on a mechanical stimulus caused by duodenal distension (3) is a major stimulus for gall bladder contraction which is not influenced by duodenal distension.
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Affiliation(s)
- J F Colombel
- INSERM U 290, Hôpital Saint-Lazare, Paris, France
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26
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27
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Brugge WR, Burke CA, Izzo RS, Praissman M. Role of cholecystokinin in intestinal phase of human pancreatic secretion. Dig Dis Sci 1987; 32:155-63. [PMID: 3803143 DOI: 10.1007/bf01297103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In this study we have utilized a sensitive and specific radioimmunoassay for cholecystokinin (CCK) to determine the effects of a jejunal infusion (5 cc/min) of amino acids (44 g/liter), saline, and amino acids with intravenous atropine (20 micrograms X lg-1 X hr) on pancreatic exocrine secretion. Amino acids were found to stimulate pancreatic output of trypsin and release CCK, while a saline infusion at the same rate and osmolality (320 mosm/liter) failed to do so. In the presence of atropine, the amino acid infusion did not stimulate the pancreatic output of trypsin, despite an augmented CCK release. The total CCK released above baseline was greatest with the infusion of amino acids with atropine, while the total trypsin output above baseline was greatest with the infusion of amino acids. These results indicate that CCK release is not under cholinergic control and that cholinergic blockade inhibits pancreatic secretion by interrupting stimulating cholinergic fibers to the pancreas.
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28
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Schneider BS, Maimon J, Friedman J. Expression of a cholecystokinin precursor-related peptide in vertebrate and invertebrate tissues. THE AMERICAN JOURNAL OF PHYSIOLOGY 1986; 251:E707-14. [PMID: 3789138 DOI: 10.1152/ajpendo.1986.251.6.e707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have developed a radioimmunoassay for the nonapeptide predicted by cDNA sequence analysis to reside at the extreme C-terminus of the mouse cholecystokinin (CCK) precursor. Sensitivity of the assay is 1 pg synthetic CCK precursor-related peptide (CCK-PRP)/ml. The antibody has no cross-reactivity with cholecystokinin, gastrin, or a variety of other known neuropeptides. We have employed this assay to demonstrate the presence, in rodent brain, gut, and peripheral plasma, of peptides with immunological properties that are identical to, and gel filtration characteristics that are very similar to, those of the synthetic CCK-PRP. We have also detected a similar peptide in the culture media of a human CCK-producing tumor. The molar ratios of immunoreactive CCK-PRP/CCK vary widely among tissues of origin and during ontogeny, suggesting regional and developmental differences in the turnover rates or in posttranslational modification of the two peptides. Our studies suggest that peptides very similar to intact CCK-PRP are posttranslationally liberated from the cholecystokinin precursor in a variety of tissues and may have neurotransmitter and/or hormonal functions distinct from those of CCK. Relatively high quantities of material immunologically indistinguishable from CCK-PRP were also found in several coelenterate species, indicating that this epitope arose as early in evolution as did CCK.
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29
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Turkelson CM, Dale WE, Reidelberger R, Solomon TE. Development of cholecystokinin radioimmunoassay using synthetic CCK-10 as immunogen. REGULATORY PEPTIDES 1986; 15:205-17. [PMID: 3786838 DOI: 10.1016/0167-0115(86)90062-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Using an antiserum generated against synthetic CCK-10, we have developed a radioimmunoassay specific for the carboxyl-terminus of cholecystokinin (CCK). Three rabbits were immunized with synthetic sulfated carboxy-terminal CCK decapeptide (CCK-10) conjugated to keyhole limpet hemocyanin. Using 125I-CCK-39 prepared by the Iodogen method as a tracer, we found that all immunized rabbits produced antibodies against the conjugate. Antiserum R016 had the highest titer (1:225,000 after four immunizations) and was studied most extensively. R016 recognizes all molecular forms of CCK, including unsulfated and oxidized forms, but has negligible cross-reactivity with gastrin and other peptides. Using CCK-8 as a standard, the assay has a minimum detection limit of 0.5 pM and an ED50 of 11.5 pM. Serial dilutions of water/acid extracts of canine intestine were parallel to serial dilutions of sulfated CCK-8, CCK-33 and CCK-39. The assay was used to measure CCK concentrations in canine plasma after C18 Sep-Pak extraction; the concentration of immunoreactive CCK increased from a basal value of 7.8 +/- 1.0 to 9.5 +/- 1.2 and 11.1 +/- 1.2 pM 30 and 60 min postprandially (P less than 0.05 by paired analysis). This sensitive and uniquely specific CCK radioimmunoassay should be useful in characterizing several aspects of CCK physiology and the method for generating CCK antisera should be of value to other investigators.
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Reidelberger RD, Kalogeris TJ, Solomon TE. Comparative effects of caerulein on food intake and pancreatic secretion in dogs. Brain Res Bull 1986; 17:445-9. [PMID: 3768748 DOI: 10.1016/0361-9230(86)90253-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We compared effects of the CCK analog caerulein on feeding and pancreatic secretion. Nine fasted mongrel dogs with gastric and pancreatic fistulas received scalar doses of caerulein (0, 6.25, 12.5, 25, 50, 100, 200, 400 pmol/kg-hr, each for 30 min). The D50 dose for stimulation of pancreatic secretion was 15 pmol/kg-hr. Effects of intravenous caerulein (0 to 800 pmol/kg-hr; 15 min before and during a 45 min test meal) on food intake were examined in 8 beagles under 4 feeding conditions: 1 meal/day (22 hr fast), 2 meals/day (4 hr fast), 2 meals/day (19 hr fast), and after ad lib access to food followed by a 4 hr fast. The lowest doses that inhibited feeding were: 400 pmol/kg-hr for feeding condition, 200 pmol/kg-hr for and, and 150 pmol/kg-hr for. We conclude: the potency of caerulein for inhibition of food intake is dependent upon feeding condition; these results do not support a role for CCK as a satiety hormone, since the lowest dose of caerulein for inhibition of feeding was 10 times larger than the D50 dose of caerulein for stimulation of pancreatic secretion.
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Abstract
A sensitive and specific radioimmunoassay for cholecystokinin (CCK) in human plasma was developed using an antiserum specific for sequence 26-29 of CCK-33 and 125I-Bolton-Hunter labelled sulphated CCK-8 as tracer. Plasma was extracted in 96% ethanol before assay. The detection limit of the assay was 0.3 pmol/l. CCK-33 and CCK-8 were stable in plasma at 0 degree C for at least 3 h, but CCK-8 was degraded at 21 degrees C. The trypsin inhibitor, aprotinin, did not affect the degradation of CCK-8, while the aminopeptidase inhibitor, bestatin, had a significant inhibitory effect. The basal plasma concentration of CCK in 44 normal subjects was 1.6 +/- 0.2 pmol/l, ranging from undetectable (less than 0.3 pmol/l) to 4.4 pmol/l. After the ingestion of a mixed meal in seven normal subjects, concentrations of plasma CCK rose from 2.0 +/- 0.2 to 7.4 +/- 0.7 pmol/l. Diurnal registration in nine people showed similar increments after each meal. The validity of the assay was further substantiated by a strong correlation between CCK measurements of identical samples with other CCK specific antisera.
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32
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Lindemans J, van Kapel J, Abels J. Uptake of transcobalamin II-bound cobalamin by isolated rat kidney tubule cells. Scand J Clin Lab Invest 1986; 46:223-32. [PMID: 3715376 DOI: 10.3109/00365518609083663] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The uptake and intracellular processing of transcobalamin II-bound cobalamin by isolated rat kidney tubule cells were studied. The cells absorbed the complex in a temperature-and calcium-dependent process, which could be inhibited by monensin, an inhibitor of endocytosis. Cells, loaded with a mixture of 125I- and 57Co-labelled transcobalamin II-vitamin B12, released 125I-labelled protein-degradation products, while keeping the 57Co-labelled vitamin. Protein degradation was inhibited by chloroquine and monensin, which is further evidence for a process of endocytosis, followed by intralysosomal hydrolysis of the transport protein. Transcobalamin II-vitamin B12 uptake was not fully saturable and other proteins, for example, haemoglobin, inhibited the uptake in a concentration-dependent way. Apparently the uptake proceeds through relatively unspecific protein-binding sites, probably involved in the reabsorption of filtrated proteins, although the affinity for transcobalamin II seems relatively high. Consequently, elevated urinary excretion of cobalamin is expected in patients with overflow proteinuria, and was indeed found in a patient with paroxysmal nocturnal haemoglobinuria.
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