CCK Peptides Research Articles

Role of Cholecystokinin (cck) in Feeding Regulation of Largemouth Bass (Micropterus salmoides): Peptide Activation and Antagonist Inhibition.

This study investigated the role of cholecystokinin (cck) in the feeding regulation of largemouth bass (Micropterus salmoides) via peptide activation and antagonist inhibition. The results show that the cck gene was expressed in various tissues, with the highest expression level occurring in the brain. Feeding, continuous feeding, and refeeding after fasting could significantly improve the mRNA levels of cck in the brain. Moreover, the activation of cck via injecting an exogenous CCK peptide could inhibit feed intake by regulating the mRNA levels of anorexigenic and feed-promoting factors in the brain and intestine. Furthermore, the CCK peptide reduced feed intake; however, the presence of an antagonist (Ly225910-CCK1R and devazepide-CCK2R) could reverse this effect through regulating the mRNA levels of anorexigenic and feed-promoting factors in the brain and intestine. Treatment with devazepide + CCK (CCK2R) reversed feed intake more effectively than Ly225910 + CCK (CCK1R) treatment. In summary, cck could regulate the feed intake of largemouth bass through regulating feeding-related genes in the brain and intestine. In addition, cck required binding with the receptor to inhibit feed intake more effectively in largemouth bass, and the binding effect of CCK1R was better than that of CCK2R.

Substance P, NPY, CCK and their receptors in five brain regions in major depressive disorder with transcriptomic analysis of locus coeruleus neurons

Major depressive disorder (MDD) is a serious disease and a burden to patients, families and society. Rodent experiments and human studies suggest that several neuropeptide systems are involved in mood regulation. The aim of this study is two-fold: (i) to monitor, with qPCR, transcript levels of the substance P/tachykinin (TAC), NPY and CCK systems in bulk samples from control and suicide subjects, targeting five postmortem brain regions including locus coeruleus (LC); and (ii) to analyse expression of neuropeptide family transcripts in LC neurons of ‘normal’ postmortem brains by using laser capture microdissection with Smart-Seq2 RNA sequencing. qPCR revealed distinct regional expression patterns in male and female controls with higher levels for the TAC system in the dorsal raphe nucleus and LC, versus higher transcripts levels of the NPY and CCK systems in prefrontal cortex. In suicide patients, TAC, TAC receptors and a few NPY family transcript levels were increased mainly in prefrontal cortex and LC. The second study on ‘normal’ noradrenergic LC neurons revealed expression of transcripts for GAL, NPY, TAC1, CCK, and TACR1 and many other peptides (e.g. Cerebellin4 and CARTPT) and receptors (e.g. Adcyap1R1 and GPR173). These data and our previous results on suicide brains indicates that the tachykinin and galanin systems may be valid targets for developing antidepressant medicines. Moreover, the perturbation of neuropeptide systems in MDD patients, and the detection of further neuropeptide and receptor transcripts in LC, shed new light on signalling in noradrenergic LC neurons and on mechanisms possibly associated with mood disorders.

Identification and target of action of cholecystokinin-releasing peptides from simulated digestion hydrolysate of wheat protein.

Wheat protein intake leads to improved appetite control. However, the active components causing appetite in wheat have not been fully clarified. Gut cholecystokinin (CCK) plays a vital role in appetite control. This study aimed to investigate the ability of wheat protein digest (WPD) to stimulate CCK secretion and clarify the active components and target of action. WPD was prepared by a simulated gastrointestinal digestion model. WPD treatment with a concentration of 5 mg mL-1 significantly stimulated CCK secretion in enteroendocrine STC-1 cells (P < 0.05). Furthermore, oral gavage with WPD in mice significantly increased plasma CCK level at 60 min (P < 0.01). Preparative C18 column separation was used to isolate peptide fractions associated with CCK secretion and peptide sequences were identified by liquid chromatography-tandem mass spectrometry. A new CCK-releasing peptide, RYIVPL, that potently stimulated CCK secretion was successfully identified. After pretreatment with a specific calcium-sensing receptor (CaSR) antagonist, NPS 2143, CCK secretion induced by WPD or RYIVPL was greatly suppressed, suggesting that CaSR was involved in WPD- or RYIVPL-induced CCK secretion. The present study demonstrated that WPD has an ability to stimulate CCK secretion in vitro and in vivo, and determined that peptide RYIVPL in WPD could stimulate CCK secretion through CaSR. © 2023 Society of Chemical Industry.

In vitro gastrointestinal digestion of highland barley protein: identification and characterization of novel bioactive peptides involved in gut cholecystokinin secretion.

The satiety hormone cholecystokinin (CCK) plays an important role in food intake inhibition. Its secretion is regulated by dietary components. The search for bioactive compounds that induce CCK secretion is currently an active area of research. The objective of this study was to evaluate the ability of highland barley protein digest (HBPD) to stimulate CCK secretion in vitro and in vivo and identify the responsible peptide sequences. HBPD was prepared by in vitro gastrointestinal digestion model. Peptides of <1000 Da in HBPD accounted for 82%. HBPD was rich in essential amino acids Leu, Phe and Val, but lack in sulfur amino acids Met and Cys. HBPD treatment at a concentration of 5 mg mL-1 significantly stimulated CCK secretion from enteroendocrine STC-1 cells (P < 0.05). Moreover, oral gavage with HBPD in mice significantly increased plasma CCK level. Chromatographic separation was performed to isolate peptide fractions involved in CCK secretion and peptide sequence was determined by ultra-performance liquid chromatography-tandem mass spectrometry. Two novel CCK-releasing peptides, PDLP and YRIVPL, were pointed out for their outstanding CCK secretagogue activity. This study demonstrated for the first time that HBPD had an ability to stimulate CCK secretion in vitro and in vivo and determined the bioactive peptides exerting CCK secretagogue activity in HBPD. © 2023 Society of Chemical Industry.

Cholecystokinin Receptor Antagonist Induces Pancreatic Stellate Cell Plasticity Rendering the Tumor Microenvironment Less Oncogenic.

CCK receptors are expressed on pancreatic cancer epithelial cells, and blockade with receptor antagonists decreases tumor growth. Activated pancreatic stellate cells or myofibroblasts have also been described to express CCK receptors, but the contribution of this novel pathway in fibrosis of the pancreatic cancer microenvironment has not been studied. We examined the effects of the nonselective CCK receptor antagonist proglumide on the activation, proliferation, collagen deposition, differential expression of genes, and migration in both murine and human PSCs. CCK receptor expression was examined using western blot analysis. Collagen production using activated PSCs was analyzed by mass spectroscopy and western blot. Migration of activated PSCs was prevented in vitro by proglumide and the CCK-B receptor antagonist, L365,260, but not by the CCK-A receptor antagonist L365,718. Proglumide effectively decreased the expression of extracellular matrix-associated genes and collagen-associated proteins in both mouse and human PSCs. Components of fibrosis, including hydroxyproline and proline levels, were significantly reduced in PSC treated with proglumide compared to controls. CCK peptide stimulated mouse and human PSC proliferation, and this effect was blocked by proglumide. These investigations demonstrate that targeting the CCK-B receptor signaling pathway with proglumide may alter the plasticity of PSC, rendering them more quiescent and leading to a decrease in fibrosis in the pancreatic cancer microenvironment.

Cholecystokinin receptors in GtoPdb v.2023.1

Cholecystokinin receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on CCK receptors [90]) are activated by the endogenous peptides cholecystokinin-8 (CCK-8), CCK-33, CCK-58 and gastrin (gastrin-17). There are only two distinct subtypes of CCK receptors, CCK1 and CCK2 receptors [64, 124], with some alternatively spliced forms most often identified in neoplastic cells. The CCK receptor subtypes are distinguished by their peptide selectivity, with the CCK1 receptor requiring the carboxyl-terminal heptapeptide-amide that includes a sulfated tyrosine for high affinity and potency, while the CCK2 receptor requires only the carboxyl-terminal tetrapeptide shared by each CCK and gastrin peptides. These receptors have characteristic and distinct distributions, with both present in both the central nervous system and peripheral tissues.

Compounds Interacting with Cholecystokinin as Potential Drugs Against Excessive Weight Gain and Obesity

Cholecystokinin (CCK) is a peptide family that functions pancreatic enzyme secretion, gallbladder contraction, intestinal motility, satiety, and stomach acid secretion. The CCK peptides are derived from pro-CCK with a specific amino acid sequence (Asp, Tyr, Met, Gly, Trp, Met, Asp, and Phe) at their C-terminus, where the Tyr residue is sulfated. The CCK peptides are ligands of the CCK receptors 1 (CCK1) and 2 (CCK2). In this study, we propose an approach for treating overweight and obese patients, preventing or reducing CCK1 activation using compounds that specifically interact with CCK peptides to regulate their interactions with CCK1. The compounds were selected by molecular docking using a chemical library with the selected residues (Asp, Tyr, Met, Gly, Trp, Met, Asp, and Phe) in CCK. Their effects were evaluated in a diet-induced obese mice model. We show that compounds K2 and K5 decreased and maintained the body weight of the diet-induced obese mice model, respectively, likely by preventing/hindering interactions between CCK peptides and CCK1, modifying its activity. This study demonstrates another approach to treating overweight and obesity by regulating CCK1 functions. The K2 and K5 compounds have properties supporting their continued development as new drugs against these risk factors.

Cholecystokinin (CCK) and its receptors (CCK1R and CCK2R) in chickens: functional analysis and tissue expression

Cholecystokinin (CCK) is widely distributed in the gastrointestinal tract and central nervous system, regulating a range of physiological functions by activating its receptors (CCK1R and CCK2R). Compared to those in mammals, the CCK gene and its receptors have already been cloned in various birds, such as chickens. However, knowledge regarding their functionality and tissue expression is limited. In this study, we examined the expression of CCK and its 2 receptors in chicken tissues. In addition, the functionality of the 2 receptors was investigated. Using 3 cell-based luciferase reporter systems and western blots, we demonstrated that chicken (c-) CCK1R could be potently activated by cCCK-8S but not cCCK-4, whereas cCCK2R could be activated by cCCK-8S and cCCK-4 with similar efficiency. Using RNA-sequencing, we revealed that cCCK is abundantly expressed in the testis, ileum, and several brain regions (cerebrum, midbrain, cerebellum, hindbrain, and hypothalamus). The abundant expression of CCK in the hypothalamus was further supported by immunofluorescence. In addition, cCCK1R is highly expressed in the pancreas and moderately expressed in various intestinal regions (ileum, cecum, and rectum) and the pituitary gland, whereas cCCK2R expression is primarily restricted to the brain. Our data reveal the differential specificities of CCK receptors for various CCK peptides. In combination with the differential tissue distribution of CCK and its receptors, the present study helps to understanding the physiological functions of CCK/CCKRs in birds.

Evidence that increased cholecystokinin (CCK) in the periaqueductal gray (PAG) facilitates changes in Resident–Intruder social interactions triggered by peripheral nerve injury

Individual differences in the effects of a chronic neuropathic injury on social behaviours characterize both the human experience and pre-clinical animal models. The impacts of these changes to the well-being of the individual are often underappreciated. Earlier work from our laboratory using GeneChip® microarrays identified increased cholecystokinin (CCK) gene expression in the periaqueductal gray (PAG) of rats that showed persistent changes in social interactions during a Resident-Intruder encounter following sciatic nerve chronic constriction injury (CCI). In this study, we confirmed these gene regulation patterns using RT-PCR and identified the anatomical location of the CCK-mRNA as well as the translated CCK peptides in the midbrains of rats with a CCI. We found that rats with persistent CCI-induced changes in social behaviours had increased CCK-mRNA in neurons of the ventrolateral PAG and dorsal raphe nuclei, as well as increased CCK-8 peptide expression in terminal boutons located in the lateral and ventrolateral PAG. The functional significance of these changes was explored by microinjecting small volumes of CCK-8 into the PAG of uninjured rats and observing their Resident-Intruder social interactions. Disturbances to social interactions identical to those observed in CCI rats were evoked when injection sites were located in the rostral lateral and ventrolateral PAG. We suggest that CCI-induced changes in CCK expression in these PAG regions contributes to the disruptions to social behaviours experienced by a subset of individuals with neuropathic injury.

Abstract 1931: Evaluation of cholecystokinin receptor expression and function in non-small cell lung cancer

Abstract Introduction: Lung cancer is the leading cause of cancer-related death in the United States, with nearly 85% of cases histologically classified as non-small cell lung cancer (NSCLC). A recent epidemiological study provides evidence of an increased risk ratio for NSCLC in association with adherence to a Western dietary pattern, which has a higher dietary fat content, compared to vegetarian or Tex-Mex dietary patterns. Our laboratory and others have measured increased tumor burden in murine models of NSCLC when feeding diets are high in fat compared to a standard rodent cereal diet. In our laboratory, increased tumor burden is associated with increased tumor multiplicity, but no change in proliferative markers (Ki-67 and pS6) were observed. Dietary fat increases both tumorigenesis in mouse models of pancreatic cancer and circulating levels of the gastrointestinal hormone cholecystokinin (CCK). Inhibition of CCK receptors antagonizes progression of precursor lesions in murine models of pancreatic cancer. Although CCK receptor expression has not been detected in normal human pulmonary tissue, the CCK-B receptor has been identified immunohistologically in human lung tumors. Further, the CCK-A receptor is expressed in normal murine pulmonary epithelium. Hypothesis: At concentrations approximating circulating levels in mice fed a high fat diet, CCK reduces apoptosis of NSCLC cells in vitro. Materials and Methods: The murine NSCLC cell line IO33 was grown in serum-replete RPMI 1640 or serum-deprived RPM 1640 with 0 to 1000 pM exogenous CCK-8 peptide added. Expression of CCK-A and CCK-B receptors were measured in IO33 and human NSCLC cell lines by qPCR. Apoptosis was assessed using a Caspase-3/7 peptide cleavage assay. Results: Expression of CCK-A and CCK-B receptors are reported in IO33 cells and 11 human lung cancer cell lines. Apoptosis of IO33 cells was significantly decreased by greater than 30% at CCK concentrations greater than 100pM (P &amp;lt; 0.03), which is the circulating concentration of CCK in mice fed a high fat diet. Conclusions: CCK receptors are expressed in human and murine NSCLC cells and circulating CCK may reduce NSCLC cell apoptosis. Citation Format: Alexander C. Miller, Shelby J. Subry, Manijeh M. Assar, Krista Pearman, Jeffrey William Norris. Evaluation of cholecystokinin receptor expression and function in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1931.

Structures of the human cholecystokinin 1 (CCK1) receptor bound to Gs and Gq mimetic proteins provide insight into mechanisms of G protein selectivity.

G protein–coupled receptors (GPCRs) are critical regulators of cellular function acting via heterotrimeric G proteins as their primary transducers with individual GPCRs capable of pleiotropic coupling to multiple G proteins. Structural features governing G protein selectivity and promiscuity are currently unclear. Here, we used cryo-electron microscopy (cryo-EM) to determine structures of the cholecystokinin (CCK) type 1 receptor (CCK1R) bound to the CCK peptide agonist, CCK-8 and 2 distinct transducer proteins, its primary transducer Gq, and the more weakly coupled Gs. As seen with other Gq/11–GPCR complexes, the Gq–α5 helix (αH5) bound to a relatively narrow pocket in the CCK1R core. Surprisingly, the backbone of the CCK1R and volume of the G protein binding pocket were essentially equivalent when Gs was bound, with the Gs αH5 displaying a conformation that arises from “unwinding” of the far carboxyl-terminal residues, compared to canonically Gs coupled receptors. Thus, integrated changes in the conformations of both the receptor and G protein are likely to play critical roles in the promiscuous coupling of individual GPCRs.

Gut sensing of dietary amino acids, peptides and proteins, and feed-intake regulation in pigs

Amino acids (AA) play key metabolic roles in the regulation of feed intake, growth, and immunity among other physiological functions. Dietary AA supplements (i.e. non-protein-bound synthetic AA) and proteins (through peptides and free AA coming from digestion) regulate appetite by stimulating the release of gut hormones from enteroendocrine cells located throughout the gastrointestinal tract, via activation of transmembrane receptors of the G-protein coupled transmembrane receptor (GPCR) family, including calcium sensing receptor, GPCR of the class C Group 6 Member A (GPRC6A), T1R1–T1R3 of taste receptor family 1 and lysophosphatidic acid receptor 5 (GPR92). In addition, growing evidence supports the role of AA transporters in mediating AA sensing in the gut. While most of the current literature available on the topic relates to research undertaken in laboratory rodents, there has been a growing demand on the confirmation of these physiological mechanisms in pigs. In pigs, limiting essential AA L-tryptophan, and branched-chain AA L-leucine and L-isoleucine were shown to stimulate anorexigenic hormones cholecystokinin (CCK) and glucagon-like peptide 1 mediated by calcium sensing receptor and T1R1–T1R3, using primary tissue cultures. Tryptophan was shown to stimulate the orexigenic hormone ghrelin in pigs. In addition, L-lysine and L-methionine have also been shown to affect feed intake. Other free AA affecting CCK and glucagon-like peptide 1 levels in pigs are L-phenylalanine and L-arginine. Similar functions have been reported for some dietary proteins such as casein, lectin, or whey and for protein hydrolysates. Overall, this review uncovers recent evidence that dietary non-protein-bound AA are efficient modulators of appetite on the basis of their strong effects on orexigenic and anorexigenic hormones in pigs. However, little has been explored to assess the relevance of essential versus non-essential dietary AA impact on feed intake. Further understanding of the role of AA and proteins on appetite modulation and the mechanisms behind gut hormone release could prove to be a relevant tool to improve swine nutrition and performance.

Abstract 5193: Cholecystokinin-B receptor mediates growth of hepatocellular carcinoma

Abstract Background: The fastest-growing cause of cancer-related death is hepatocellular carcinoma (HCC), which is in part attributable to the obesity epidemic and nonalcoholic steatohepatitis (NASH). The gastrointestinal (GI) peptides, gastrin and cholecystokinin (CCK), regulate digestive functions and growth of the GI tract through the G-protein coupled receptors CCK- receptors (CCK-Rs). Both peptides activate the CCK-B receptor (CCK-BR) whereas only CCK peptide activates the CCK-A receptor (CCK-AR). CCK-Rs and gastrin are low or absent in normal mouse hepatocytes. We have previously shown that CCK blood levels increase and CCK-Rs become overexpressed in the livers of mice eating a high saturated fat diet that induced NASH and HCC. Hypothesis: CCK and gastrin mediate the growth of HCC through the CCK-R and that interruption of this signaling pathway could decrease growth of HCC. Methods: RNA was extracted from murine Hepa1-6, RIL-175, and human HepG2 cells and was evaluated by qRT-PCR for expression of CCK-AR, CCK-BR, and gastrin. CCK-R protein expression was analyzed by flow cytometry. In order to determine which CCK-R mediated the growth effects, growth was studied in vitro using selective receptor antagonists or CRISPR Cas9 technology to knock-out each receptor. HCC cells were treated in vitro with CCK peptide (1-10nM), the CCK-AR antagonist (L364,718), or the CCK-BR antagonist (L365,260). Proliferation of selective CCK-R KO cells was compared to that of wild-type cells. To determine the effect of a CCK-R antagonist on tumor growth in vivo, two cohorts of mice bearing subcutaneous Hepa1-6 or RIL-175 HCC tumors were treated with an oral bioavailable CCK-R antagonist, proglumide (1 mg/ml) or untreated water (controls) for 3-4 weeks. The mice bearing Hepa1-6 tumors were placed on a high-fat diet to raise blood CCK levels. Mice bearing RIL-175 tumors were fed standard chow to determine if proglumide could block autocrine growth by gastrin. Results: The mRNA expression of CCK-AR, CCK-BR and gastrin were increased 80-90-fold in all HCC cell lines compared to that of normal liver. CCK-BRs were detected on &amp;gt;85% of the cells by flow cytometry. CCK peptide (1nM) stimulated HCC growth in vitro in both wild-type cells and in CCK-AR KO cells but not in CCK-BR KO cells. CCK-BR antagonist blocked CCK-stimulated growth in vitro but the CCK-AR antagonist did not, suggesting that the CCK-BR was responsible for mediating proliferation. In vivo tumor growth was significantly reduced with proglumide treatment by 70% (p&amp;lt;0.05) in Hepa1-6 and by 73% (p&amp;lt;0.001) in RIL-75 tumors, respectively. Conclusion: CCK-Rs are overexpressed in HCC and proliferation appears to be mediated through the CCK-BR. Downregulation with CRISPR Cas9 or blockade of the CCK-BR with an antagonist decreases growth in vitro and proglumide therapy decreases tumor growth in vivo. Strategies that block signaling at the CCK-BR may provide a novel therapeutic option for HCC treatment. Citation Format: Martha D. Gay, Anita Safronenka, Hong Cao, Robin Tucker, Narayan Shivapurkar, Jill P. Smith. Cholecystokinin-B receptor mediates growth of hepatocellular carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5193.

Intra-islet GLP-1, but not CCK, is necessary for \u03b2-cell function in mouse and human islets

Glucagon-like peptide 1 (GLP-1) and cholecystokinin (CCK) are gut-derived peptide hormones known to play important roles in the regulation of gastrointestinal motility and secretion, appetite, and food intake. We have previously demonstrated that both GLP-1 and CCK are produced in the endocrine pancreas of obese mice. Interestingly, while GLP-1 is well known to stimulate insulin secretion by the pancreatic β-cells, direct evidence of CCK promoting insulin release in human islets remains to be determined. Here, we tested whether islet-derived GLP-1 or CCK is necessary for the full stimulation of insulin secretion. We confirm that mouse pancreatic islets secrete GLP-1 and CCK, but only GLP-1 acts locally within the islet to promote insulin release ex vivo. GLP-1 is exclusively produced in approximately 50% of α-cells in lean mouse islets and 70% of α-cells in human islets, suggesting a paracrine α to β-cell signaling through the β-cell GLP-1 receptor. Additionally, we provide evidence that islet CCK expression is regulated by glucose, but its receptor signaling is not required during glucose-stimulated insulin secretion (GSIS). We also see no increase in GSIS in response to CCK peptides. Importantly, all these findings were confirmed in islets from non-diabetic human donors. In summary, our data suggest no direct role for CCK in stimulating insulin secretion and highlight the critical role of intra-islet GLP-1 signaling in the regulation of human β-cell function.

Tibetan medicine Ru-yi-Zhen-bao Pills exhibits anti-migraine effect through mediating PAG anti-nociceptive channel.

Migraine is a disabling neurovascular disorder, which increases risk of cardiovascular events and is a social burden worldwide. The present first-line anti-migraine medications can cause overwhelming side-effects, of which one includes the onset of cardiovascular disease. As one of the marketed Tibetan drugs, Ru-yi-Zhen-bao Pills (RYZBP) have been clinically used to treat cardiovascular disorders and as anti-migraine medication. However, there is currently no research exploring the anti-migraine actions of RYZBP. The current research was designed to assess the anti-migraine roles of RYZBP and explore the underlying mechanisms in a nitroglycerin (NTG)-induced migraine rat model trial. 120 rats were randomly divided into the following six groups of 20 rats each: normal control group, model control group, positive control group, and RYZBP high/medium/low-dose groups (Ru-yi-Zhen-bao Pills; TH 1.00 g/kg, TM 0.50 g/kg and TL 0.25 g/kg). All rats were administered intragastrically for 7 consecutive days, which were subcutaneously injected with the NTG (10mg/kg) after the last gavage (except in the normal control group). 3min after NTG treatment, 30 rats (5 rats from each group) were anesthetized and devoted to electroencephalogram(EEG) testing, which was used to evaluate the analgesic effect of RYZBP. One hour after NTG treatment, the rest of the 90 rats (15 rats from each group) were anesthetized and midbrain tissue sample was dissected. The dissection was then washed with physiological saline and collected. The histopathological changes in the periaqueductal gray(PAG) of 5 tissue samples were determined by aematoxylin-eosin (H&E) staining, as well as an estimation of substance P (SP) and neurokinin 1 receptor (NK1R) expression through immunohistochemically staining(IHC). Another 5 midbrain preparations were carried out to evaluate calcitonin gene-related peptide (CGRP), proenkephalin (PENK), SP, and cholecystokinin (CCK) expressions by real-time quantitative polymerase chain reaction (RT-qPCR). The rest of the 5 brainstem tissues were then used to measure CCK, CGRP, and opioid peptide receptor (DORR) levels by western blotting(WB). In the EEG test, RYZBP (TM 0.50 g / kg) treatment transformed the EEG pain-wave of the NTG-induced migraine model rats in different time period. In the mechanism assay, compared with the model control group, RYZBP pretreatment reduced inflammatory cell infiltration, fibrosis and vacuolation of neuronal cells of PAG tissue seen by HE staining. IHC experiments further showed that RYZBPTM up-regulated SP expression levels and enhanced NK1R levels in the NTG-induced migraine rats (P<0.05). Therapeutic administration of RYZBP also increased PENK mRNA expression and DORR protein level. Both RT-qPCR and western blotting trials indicated that RYZBP treatment significantly decreased CCK and CGRP expression levels (P<0.01 or P<0.05) in the NTG-induced migraine rats. RYZBP has the potential to be an effective anti-migraine treatment through suppressing the EEG pain-wave, increasing the levels of SP, PENK, DORR and reducing expression of CCK and CGRP. Mediating the PAG anti-nociceptive channel and inhibiting central sensitization were the two potential mechanisms, which offers further evidence for clinical therapy.

Cholecystokinin receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

Cholecystokinin receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on CCK receptors [89]) are activated by the endogenous peptides cholecystokinin-8 (CCK-8), CCK-33, CCK-58 and gastrin (gastrin-17). There are only two distinct subtypes of CCK receptors, CCK1 and CCK2 receptors [63, 123], with some alternatively spliced forms most often identified in neoplastic cells. The CCK receptor subtypes are distinguished by their peptide selectivity, with the CCK1 receptor requiring the carboxyl-terminal heptapeptide-amide that includes a sulfated tyrosine for high affinity and potency, while the CCK2 receptor requires only the carboxyl-terminal tetrapeptide shared by each CCK and gastrin peptides. These receptors have characteristic and distinct distributions, with both present in both the central nervous system and peripheral tissues.

Quantitation and chemical coding of enteroendocrine cell populations in the human jejunum.

Recent studies reveal substantial species and regional differences in enteroendocrine cell (EEC) populations, including differences in patterns of hormone coexpression, which limit extrapolation between animal models and human. In this study, jejunal samples, with no histologically identifiable pathology, from patients undergoing Whipple's procedure were investigated for the presence of gastrointestinal hormones using double- and triple-labelling immunohistochemistry and high-resolution confocal microscopy. Ten hormones (5-HT, CCK, secretin, proglucagon-derived peptides, PYY, GIP, somatostatin, neurotensin, ghrelin and motilin) were localised in EEC of the human jejunum. If only single staining is considered, the most numerous EEC were those containing 5-HT, CCK, ghrelin, GIP, motilin, secretin and proglucagon-derived peptides. All hormones had some degree of colocalisation with other hormones. This included a population of EEC in which GIP, CCK and proglucagon-derived peptides are costored, and four 5-HT cell populations, 5-HT/GIP, 5-HT/ghrelin, 5-HT/PYY, and 5-HT/secretin cell groups, and a high degree of overlap between motilin and ghrelin. The presence of 5-HT in many secretin cells is consistent across species, whereas lack of 5-HT and CCK colocalisation distinguishes human from mouse. It seems likely that the different subclasses of 5-HT cells subserve different roles. At a subcellular level, we examined the vesicular localisation of secretin and 5-HT, and found these to be separately stored. We conclude that hormone-containing cells in the human jejunum do not comply with a one-cell, one-hormone classification and that colocalisations of hormones are likely to define subtypes of EEC that have different roles.

Identification and synthesis of low-molecular weight cholecystokinin B receptor (CCKBR) agonists as mediators of long-term synaptic potentiation

Recently, He et al. reported that CCKB receptors located in the neocortex of the brain when bound to their bound natural ligand, CCK peptides, enhance memory, bringing up the possibility that agonists targeting the CCKB receptor may act as therapeutic agents in diseases in which memory loss is marked as observed in dementia and Alzheimer’s. In this report, we describe the synthesis of novel low-molecular weight benzoamine CCKB receptor agonists. The compounds made in this series were determined to be mostly partial agonists, although some antagonists were identified, as well, capable of triggering calcium release in a cell line that overexpresses the CCKB receptor. Compound 35 demonstrated an EC50 of 0.15 µM in the cell-based assay, but more importantly, several of the compounds, including 35, demonstrated a physiological effect, inducing long-term potentiation in rat brains comparable to the CCK-8 peptide albeit at much higher concentrations. Based on these findings, benzoamines may be the basis for a new series of CCKB receptor agonists in drug-discovery efforts that seek to develop therapeutics to prevent memory loss.

Premises for Cholecystokinin and Gastrin Peptides in Diabetes Therapy.

Gastrin and cholecystokinin (CCK) are classical gastrointestinal peptide hormones. Their biogenesis, structures, and intestinal secretory patterns are well-known with the striking feature that their receptor-bound ‘active sites’ are highly homologous and that this structure is conserved for more than 500 million years during evolution. Consequently, gastrin and CCK are agonists for the same receptor (the CCK2 receptor). But in addition, tyrosyl O-sulphated CCK are also bound to the specific CCK1 receptor. The receptors are widely expressed in the body, including pancreatic islet-cell membranes. Moreover, CCK and gastrin peptides are at various developmental stages and diseases expressed in pancreatic islets; also in human islets. Accordingly, bioactive gastrin and CCK peptides stimulate islet-cell growth as well as insulin and glucagon secretion. In view of their insulinotropic effects, gastrin and CCK peptides have come into focus as drug targets, either alone or in combination with other insulinotropic gut hormones or growth factors. So far, modified CCK and gastrin peptides are being examined as potential drugs for therapy of type 1 as well as type 2 diabetes mellitus.

Chemical Reactivity Properties, Drug-Likeness Features and Bioactivity Scores of the Cholecystokinin Peptide Hormone

Five density functionals, CAM-B3LYP, LC-ωPBE, MN12SX, N12SX and ωB97XD, in connection with the Def2TZVP basis set were assessed together with the SMD solvation model for the calculation of the molecular and chemical reactivity properties of the Cholecystokinin peptide hormone (CCK-8) in the presence of water. All the chemical reactivity descriptors for the systems were calculated via Conceptual Density Functional Theory (CDFT). The potential bioavailability and druggability as well as the bioactivity scoresfor CCK-8 were predicted through different methodologies already reported in the literature which have been previously validated during the study of different peptidic systems. The conclusion was that the CCK-8 peptide will be moderately bioactive regarding all the interactions.