CCK Receptor Antagonist Proglumide Research Articles

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.

Deoxynivalenol (Vomitoxin)-Induced Anorexia Is Induced by the Release of Intestinal Hormones in Mice.

Deoxynivalenol (DON), also known as vomitoxin, is a mycotoxin that can cause antifeeding and vomiting in animals. However, the mechanism of DON inducing anorexia is complicated. Studies have shown that intestinal hormones play a significant part in the anorexia caused by DON. We adopted the “modeling of acute antifeeding in mice” as the basic experimental model, and used two methods of gavage and intraperitoneal injection to explore the effect of intestinal hormones on the antifeedant response induced by DON in mice. We found that 1 and 2.5 mg/kg·bw of DON can acutely induce anorexia and increase the plasma intestinal hormones CCK, PYY, GIP, and GLP-1 in mice within 3 h. Direct injection of exogenous intestinal hormones CCK, PYY, GIP, and GLP-1 can trigger anorexia behavior in mice. Furthermore, the PYY receptor antagonist JNJ-31020028, GLP-1 receptor antagonist Exendin(9-39), CCK receptor antagonist Proglumide, GIP receptor antagonist GIP(3-30)NH2 attenuated both intestinal hormone and DON-induced anorectic responses. These results indicate that intestinal hormones play a critical role in the anorexia response induced by DON.

Aptamer-Targeted Calcium Phosphosilicate Nanoparticles for Effective Imaging of Pancreatic and Prostate Cancer

PurposeAccurate tumor identification and staging can be difficult. Aptamer-targeted indocyanine green (ICG)-nanoparticles can enhance near-infrared fluorescent imaging of pancreatic and prostate tumors and could improve early cancer detection. This project explored whether calcium-phosphosilicate nanoparticles, also known as NanoJackets (NJs), that were bioconjugated with a tumor-specific targeting DNA aptamer could improve the non-invasive detection of pancreatic and prostate tumors.MethodsUsing in vivo near-infrared optical imaging and ex vivo fluorescence analysis, DNA aptamer-targeted ICG-loaded NJs were compared to untargeted NJs for detection of tumors.ResultsNanoparticles were bioconjugated with the DNA aptamer AP1153, which binds to the CCK-B receptor (CCKBR). Aptamer bioconjugated NJs were not significantly increased in size compared with unconjugated nanoparticles. AP1153-ICG-NJ accumulation in orthotopic pancreatic tumors peaked at 18 h post-injection and the ICG signal was cleared by 36 h with no evidence on uptake by non-tumor tissues. Ex vivo tumor imaging confirmed the aptamer-targeted NJs accumulated to higher levels than untargeted NJs, were not taken up by normal pancreas, exited from the tumor vasculature, and were well-dispersed throughout pancreatic and prostate tumors despite extensive fibrosis. Specificity for AP1153-NJ binding to the CCK-B receptor on pancreatic tumor cells was confirmed by pre-treating tumor-bearing mice with the CCK receptor antagonist proglumide. Proglumide pre-treatment reduced the in vivo tumoral accumulation of AP1153-NJs to levels comparable to that of untargeted NJs.ConclusionThrough specific interactions with CCK-B receptors, tumor-targeted nanoparticles containing either ICG or rhodamine WT were well distributed throughout the matrix of both pancreatic and prostate tumors. Tumor-targeted NJs carrying various imaging agents can enhance tumor detection.

Effect of intracerebroventricular administration of two molecular forms of sulfated CCK octapeptide on anxiety-like behavior in the zebrafish danio rerio

Cholecystokinin octapeptide with sulfate (CCK−8s) regulates feeding behavior and psychomotor activity. In rodents and goldfish, intracerebroventricular (ICV) injection of CCK−8s decreases food intake and also induces anxiety-like behavior. The zebrafish has several merits for investigating the psychophysiological roles of neuropeptides. However, little is known about the brain localization of CCK and the behavioral action of CCK−8s in this species. Here we investigated the brain localization of CCK-like immunoreactivity and found that it was distributed throughout the brain. As CCK-like immunoreactivity was particularly evident in the ventral habenular nucleus, the interpeduncular nucleus and superior raphe, we subsequently examined the effect of zebrafish (zf) CCK−8s on psychomotor control. Since the zebrafish possesses two molecular forms of zfCCK−8s (zfCCKA−8s and zfCCKB−8s), two synthetic peptides were administered intracerebroventricularly at 1, 5 and 10 pmol g−1 body weight (BW). As the zebrafish shows a greater preference for the lower area of a tank than for to the upper area, we used this preference for assessment of anxiety-like behavior. ICV administration of zfCCKA−8 s or zfCCKB−8s at 10 pmol g−1 BW significantly shortened the time spent in the upper area. The actions of these peptides mimicked that of the central-type benzodiazepine receptor inverse agonist FG-7142 (an anxiogenic agent) at 10 pmol g−1 BW. The anxiogenic-like action of the two peptides was attenuated by treatment with the CCK receptor antagonist proglumide at 200 pmol g−1 BW. These results indicate that zfCCKA−8s and zfCCKB−8s potently induce anxiety-like behavior via the CCK receptor-signaling pathway in the zebrafish brain.

Intracerebroventricular administration of sulphated cholecystokinin octapeptide induces anxiety-like behaviour in goldfish.

Sulphated cholecystokinin octapeptide (CCK-8s) is involved in feeding regulation as an anorexigenic neuropeptide in vertebrates. In rodents, i.c.v. administration of CCK-8s has been shown to affect not only feeding behaviour, but also psychomotor activity. However, there is still no information available concerning the psychophysiological effects of CCK-8s in goldfish. Therefore, in the present study, we examined the effect of synthetic goldfish (gf) CCK-8s on psychomotor activity in this species. Intracerebroventricular administration of gfCCK-8s at 0.1, 0.5 and 2.5pmolg-1 body weight (BW) did not affect swimming distance (locomotor activity). Because goldfish prefer the lower to the upper area of a tank, we used this as a preference test (upper/lower test) to assess anxiety-like behaviour. Intracerebroventricular administration of gfCCK-8s at 2.5pmolg-1 BW shortened the time spent in the upper area. The action of gfCCK-8s mimicked that of FG-7142 (the central-type benzodiazepine receptor inverse agonist, an anxiogenic agent) at 5 and 10pmolg-1 BW. The anxiogenic-like effect of gfCCK-8s was abolished by treatment with the CCK receptor antagonist proglumide at 50pmolg-1 BW. We also investigated the localisation of CCK/gastrin-like immunoreactivity in the goldfish brain. CCK/gastrin-like immunoreactivity was observed in the anxiety-related regions (the nucleus habenularis and the interpeduncular nucleus). These data indicate that gfCCK-8s potently affects psychomotor activity in goldfish, and exerts an anxiogenic-like effect via the CCK receptor-signalling pathway.

Dietary fat stimulates pancreatic cancer growth and promotes fibrosis of the tumor microenvironment through the cholecystokinin receptor.

The gastrointestinal peptide cholecystokinin (CCK) is released from the duodenum in response to dietary fat to aid in digestion, and plasma CCK levels are elevated with the consumption of high-fat diets. CCK is also a trophic peptide for the pancreas and has also been shown to stimulate growth of pancreatic cancer. In the current investigation, we studied the influence of a diet high in saturated fat on the growth of pancreatic cancer in syngeneic murine models before the mice became obese to exclude the confounding factors associated with obesity. The high-fat diet significantly increased growth and metastasis of pancreatic cancer compared with the control diet, and the stimulatory effect was blocked by the CCK-receptor antagonist proglumide. We then selectively knocked out the CCK receptor on the pancreatic cancer cells using clustered regularly interspaced short palindromic repeats technology and showed that without CCK-receptors, dietary fat was unable to stimulate cancer growth. We next demonstrated that dietary fat failed to influence pancreatic cancer xenograft growth in genetically engineered CCK peptide knockout mice. The tumor-associated fibrosis that is so prevalent in the pancreatic cancer microenvironment was significantly decreased with CCK-receptor antagonist therapy because fibroblasts also have CCK receptors. The CCK-receptor antagonist proglumide also altered tumor metalloprotease expression and increased tumor suppressor genes by a PCR array. Our studies confirm that a diet high in saturated fat promotes growth of pancreatic cancer and the action is mediated by the CCK-receptor pathway. NEW & NOTEWORTHY Diets high in long-chain saturated fats promote growth of pancreatic cancer independent of obesity. The mechanism through which dietary fat promotes cancer is mediated through the cholecystokinin (CCK) receptor pathway. Therapy with a CCK-receptor antagonist altered the tumor microenvironment by reducing fibrosis, increasing cluster of differentiation 8+ lymphocytes, increasing tumor suppressor genes, and thus decreasing metastases. Use of CCK-receptor antagonist therapy with standard chemotherapy for pancreatic cancer may improve response by altering the tumor microenvironment.

Abstract LB-133: De novo expression of gastrin and CCK-B receptors in cell lines derived from KPC mice

Abstract Background: Animal models to study cancer progression and therapeutics are essential but these animal models are most useful when they resemble human cancers, particularly with respect to inflammation and the immune system in carcinogenesis and therapy. Hence, athymic nude mice bearing human cancer explants are being replaced by genetically modified animal models with intact immune systems. Panc02 cancer cells have been used to create a syngeneic immune competent murine model of pancreatic cancer. However, unlike human pancreatic cancer, Panc02 cells express wild-type KRAS and CCK-A type receptors (rather than CCK-B type receptors). We previously showed that the Pdx1-Cre / LSL-KrasG12D transgenic mice develop de novo CCK-B receptors with PanIN progression. Aim: The goal of this investigation was to examine cell cultures derived from the KrasG12D mice to determine if they are indeed similar to human cancers in regard to in vivo growth properties and expression of gastrin and CCK-B receptors. Methods: Five different pancreatic cell lines were obtained that had been derived from the KPC mice (KPC1, KPC2) or organoids (MT3-2D, MT4-2D, and MT5-2D) of the KPC mice. RNA was extracted from the cell lines and evaluated for CCK-A and CCK-B receptors and the ligand gastrin. Growth studies were characterized in syngeneic C57BL/6 mice. The effects of CCK receptor blockade with proglumide was evaluated on tumor growth in vivo. Histologic sections were stained with H&E, Trichrome, and a PD-L1 Ab.Results: RT-PCR revealed that the KPC and MT-2D cells no longer express the CCK-A receptor found in normal mouse pancreas but all expressed the CCK-B receptor, characteristic of human pancreatic cancers. Gastrin expression was also detected by RT-PCR in all cells. Subcutaneous tumors grew rapidly to 1000mm3 within 21 days after inoculation of 105 cells. Tumor growth in MT3-2D tumors was significantly inhibited and survival of mice prolonged with the CCK-receptor antagonist proglumide compared to PBS controls (p=0.0048). Tumors showed extensive fibrosis characteristic of the human PDAC microenvironment and all tumors had PD-L1 expression. Conclusion: These studies show that cell lines developed from PanIN lesions in KRAS mice exhibit phenotypic and genetic characteristics comparable to human pancreatic cancers and therefore are promising models to study the relationship of CCK receptor-mediated biology to the development and therapy of pancreatic cancer. De novo expression of the CCK-B receptor and gastrin from mouse pancreas suggests a possible relationship between CCK receptor signaling and mutant KRAS expression.Supported by NCI CA50633, CA51008, and CA194745 Citation Format: Jill P. Smith, Shangzi Wang, Louis Weiner, Sandeep Nadella. De novo expression of gastrin and CCK-B receptors in cell lines derived from KPC mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-133. doi:10.1158/1538-7445.AM2017-LB-133

Activation of galanin and cholecystokinin receptors in the lumbosacral spinal cord is required for ejaculation in male rats.

The spinal ejaculation generator is comprised of lumbar spinothalamic (LSt) cells and their axonal projections to autonomic and motor neurons in the lumbosacral spinal cord. LSt cells regulate ejaculatory reflexes by release of neuropeptides that are co-expressed in their axons, as previously demonstrated for gastrin-releasing peptide and enkephalin. Here, the role of two other neuropeptides co-expressed in LSt cells for ejaculatory reflexes is demonstrated: galanin and cholecystokinin (CCK). Adult male rats were anesthetized, spinalized, and received intrathecal infusions of galanin receptor antagonist Galantide (1 or 10nmol) or CCK receptor antagonist proglumide (71 or 714nmol). The dorsal penile nerve (DPN) was electrically stimulated to trigger ejaculatory reflexes and seminal vesicle pressure (SVP) and rhythmic contractions of the bulbocavernosus muscle (BCM) were analyzed as parameters of emission and expulsion respectively. Treatment with galanin or CCK antagonists significantly reduced SVP increases and BCM bursting, demonstrating that galanin and CCK are required for ejaculation. Next, anesthetized, spinalized males received intrathecal infusions of galanin (0.15 or 0.3nmol) or CCK(26-33) (4.35nmol) and effects on subthreshold DPN stimulations were determined. Intrathecal infusions of galanin or CCK facilitated ejaculatory reflexes induced by subthreshold DPN stimulation in all animals, but did not trigger ejaculatory reflexes in the absence of DPN stimulation. Together, these results demonstrate that galanin and CCK both act in the spinal ejaculation generator to regulate ejaculation. However, effects of galanin and CCK were dependent on DPN stimulation, suggesting that these neuropeptides may act in concert with other LSt co-expressed neuropeptides.

Peripheral participation of cholecystokinin in the morphine-induced peripheral antinociceptive effect in non-diabetic and diabetic rats

The effects of cholecystokinin (CCK-8) and the CCK receptor antagonist proglumide, on antinociception induced by local peripheral (subcutaneous) injected morphine in non-diabetic (ND) and streptozotocin-induced diabetic (D) rats, were examined by means of the formalin test. Morphine induced dose-dependent antinociception both in ND and D rats. However, in D rats, antinociceptive morphine potency was about twofold less than in ND rats. Pre-treatment with CCK-8 abolished the antinociceptive effect of morphine in a dose-dependent manner in both groups of rats. Additionally, proglumide enhanced the antinociceptive effect induced by all doses of morphine tested. Both CCK-8 and proglumide had no effect on flinching behaviour when given alone to ND rats. Unlike ND rats, in D rats proglumide produced dose-dependent antinociception and CCK-8 enhanced formalin-evoked flinches, as observed during the second phase of the test. In conclusion, our data show a decrease in peripheral antinociceptive potency of morphine when diabetes was present. Additionally, peripheral CCK plays an antagonic role to the peripheral antinociceptive effect of morphine, additional to the well known CCK/morphine interaction at spinal and supraspinal level.

Involvement of cholecystokinin in peripheral nociceptive sensitization during diabetes in rats as revealed by the formalin response

The possible pronociceptive role of peripheral cholecystokinin (CCK-8) as well as CCK A and CCK B receptors in diabetic rats was assessed. Subcutaneous injection of 0.5% formalin induced a greater nociceptive behavior in diabetic than in non-diabetic rats. Moreover, local peripheral injection of CCK-8 (0.1–100 μg) significantly increased 0.5% formalin-induced nociceptive activity in diabetic, but not in non-diabetic, rats. This effect was restricted to the formalin-injected paw as administration of CCK-8 into the contralateral paw was ineffective. Local peripheral administration of CCK-8, in the absence of formalin injection, produced a low level of, but significant increase in, flinching behavior in diabetic compared to non-diabetic rats. In addition, local peripheral administration of the non-selective CCK receptor antagonist proglumide (1–100 μg), CCK A receptor antagonist lorglumide (0.1–100 μg) or CCK B receptor antagonist CR-2945 (0.1–100 μg), but not vehicle or contralateral administration of CCK receptor antagonists, significantly reduced 0.5% formalin-induced flinching in diabetic rats. CR-2945 was the most effective drug in this condition. These effects were not observed in non-diabetic rats. The local peripheral pronociceptive effect of CCK-8 (100 μg) was significantly reduced by proglumide (100 μg), lorglumide (100 μg), and CR-2945 (100 μg). Results suggest that diabetes-induced peripheral sensitization could be due to a local peripheral release of CCK-8, which in turn would act on CCK B, mainly but also in CCK A, receptors located on the primary afferent neurons.

Differential contribution of cholecystokinin receptors to stress-induced modulation of seizure and nociception thresholds in mice

Recent evidence suggest that endogenous cholecystokinin (CCK) has important roles in central responses to stress. CCK receptors are known as functional modulators of opioidergic system with a tonic antiopioid effect in nociceptive pathways. In contrast, CCK receptor ligands are known to induce anticonvulsant effects similar to endogenous opioids. It is not clear whether endogenous CCK may play a role in the anticonvulsant effects of stress, especially in those stressful paradigms that are associated with strong activation of opioid pathways. The present study examined the role of endogenous CCK receptors in acute stress-induced modulation of seizure (clonic seizures induced by pentylenetetrazole) and nociception (tail-flick) thresholds. Acute restraint stress (for 2 h) and prolonged intermittent footshock stress (30 min) both induced opioid-dependent anticonvulsant and antinociceptive effects. While CCK receptor antagonist proglumide (10, 20, or 40 mg/kg) had no effect on seizure or nociception threshold by itself, it inhibited the anticonvulsant effects of both these types of stress while potentiating their antinociceptive effects. Moreover, proglumide exerted a similar inhibition of the anticonvulsant effect and potentiation of the antinociceptive effect of acute morphine at 1 mg/kg. In contrast, brief and continuos footshock stress (3 min) that induced a nonopioid type of antinociception did not increase the seizure threshold. Proglumide pretreatment did not alter any of these effects of brief footshock stress paradigm. The present data suggest that CCK receptors specifically and differentially modulate the opioid-mediated anticonvulsant and antinociceptive effects of acute stress.

Role of leptin in the control of feeding of goldfish Carassius auratus: interactions with cholecystokinin, neuropeptide Y and orexin A, and modulation by fasting

To assess the role of leptin on food intake regulation in goldfish, we examined the effects of central (intracerebroventricular, ICV) and peripheral (intraperitoneal, IP) injections of recombinant murine leptin on feeding behavior. Centrally (100 ng/g) and peripherally (300 ng/g) injected leptin both caused a significant decrease in food intake, compared to the saline-treated controls. To test the hypothesis that leptin influenced orexigenic neuropeptide systems in goldfish, fish were co-injected with neuropeptide Y (NPY) or orexin A and leptin. Both NPY (5 ng/g) and orexin A (10 ng/g) significantly increased food intake. Fish co-injected ICV with NPY (5 ng/g) or orexin A (10 ng/g) and leptin (1 or 10 ng/g) had a food intake lower than that of fish treated with NPY or orexin A alone. NPY mRNA expression in goldfish brain was reduced 2 and 6 h following central injection of leptin. To test the hypothesis that the cholecystokinin (CCK) mediates the effects of leptin in goldfish, fish were simultaneously injected ICV with an ineffective dose of leptin (10 ng/g) and either ICV or IP with an ineffective doses of CCK (1 ng/g ICV or 25 ng/g IP). These fish had a food intake lower than vehicle-treated fish, suggesting that leptin potentiates the satiety actions of CCK. CCK hypothalamic mRNA expression was increased 2 h following central treatment with leptin. The CCK receptor antagonist proglumide blocked both central and peripheral CCK satiety effects. Blockade of CCK brain receptors by proglumide resulted in an inhibition of the leptin-induced decrease in food intake and an attenuation of the inhibiting action of leptin on both NPY- and orexin A-induced feeding. These data suggests that CCK has a role in mediating the effects of leptin on food intake. Fasting potentiated the actions of leptin and attenuated the effects of CCK. Whereas fasting had no effects on the brain mRNA expression of CCK, it increased the brain mRNA expression of NPY and decreased the expression of CART. These changes in neuropeptide expression were partially reversed when fish were treated ICV with leptin. These results provide strong evidence that, in goldfish, leptin influences food intake, in part by modulating the orexigenic effects of NPY and orexin and that its actions are mediated, at least in part, by CCK.

Involvement of local cholecystokinin in the tolerance induced by morphine microinjections into the periaqueductal gray of rats

The ventrolateral periaqueductal gray (PAG) is a key structure for the development of opioid tolerance. An increased activity of ‘anti-opioids’ like cholecystokinin (CCK) has been proposed as a possible mechanism for opioid tolerance. The present study evaluates the role of PAG-located CCK in the opioid tolerance induced by repeated microinjections of morphine (MOR) into PAG. Male rats were implanted with chronic guide cannulae aimed at the PAG. Microinjection of MOR (0.5 μg in 0.5 μl) into PAG caused antinociception as quantified with the tail flick and the hot plate tests. When MOR microinjection was repeated twice daily, the antinociceptive effect disappeared within 2 days (tolerance). However, if each MOR microinjection was preceded (within 15 min) by a microinjection of the non-selective CCK receptor antagonist proglumide (PRO), (0.4 μg in 0.5 μl) into the same PAG site, the microinjections of MOR always produced antinociception and did not induce tolerance. If PRO microinjections were suspended, subsequent MOR microinjections induced tolerance. In MOR-tolerant rats, a single PRO microinjection into the same PAG site was enough to restore the antinociceptive effect of MOR. On the other hand, if CCK (1 ng in 0.5 μl) was microinjected into PAG, then MOR microinjection administered 15 min later into the same PAG site did not elicit antinociception. These results show that CCK has anti-opioid activity in PAG and that tolerance to MOR in PAG can be prevented or reversed if CCK receptors are blocked with PRO. Finally, opioid tolerance induced by repeated systemic MOR injections (5 mg/kg intraperitoneal ) was reversed by a single microinjection of PRO into PAG. This emphasizes the central importance of PAG in the MOR/CCK interactions that lead to opioid tolerance.

Effect of cholecystokinin octapeptide on tumor necrosis factor alpha transcription and nuclear factor-kappaB activity induced by lipopolysaccharide in rat pulmonary interstitial macrophages.

To elucidate the anti-inflammatory mechanism of an intestinal neuropeptide, sulfated cholecystokinin octapeptide (sCCK-8), the effects of sCCK-8 on lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-alpha) mRNA expression and NF-kappaB activity in pulmonary interstitial macrophages (PIMs) were studied. PIMs from rat were stimulated with LPS (1 mg.L(-1)) in the presence or absence of sCCK-8 (10(-8)-10(-6)mol.L(-1)) or/and CCK receptor antagonist proglumide (2 mg.L(-1)). The expression of TNF-alpha mRNA was assayed by reverse transcription polymerase chain reaction (RT-PCR) at 3h of the stimulation, and nuclear factor-kappaB (NF-kappaB) binding activity was analyzed by electrophoretic mobility shift assay (EMSA) at 1 h of stimulation. The IkappaBalpha protein level in the cytoplasma at 30 min of the stimulation was detected by Western blot. sCCK-8, at concentrations from 10(-8) mol.L(-1) to 10(-6) mol.L(-1) obviously inhibited LPS-induced TNF-alpha mRNA expression and NF-kappaB binding activity in a dose-dependent manner, P<0.05, P<0.01. Stimulation PIMs with LPS resulted in a reduction of IkappaBalpha protein level, P<0.01, which was elevated by sCCK-8, P<0.05. The effects of sCCK-8 on NF-kappaB activity and IkappaB protein level were attenuated by CCK receptor antagonist proglumide, P<0.01. sCCK-8 inhibits LPS-induced TNF-alpha mRNA expression by regulating NF-kappaB activity in rat PIMs, which is mediated through CCK receptors and inhibiting IkappaB-alpha degradation. This represents one of the anti-inflammatory mechanisms of sCCK-8.

Cholecystokinin actions in the parabrachial nucleus: effects on thirst and salt appetite.

The present study investigated the effects of bilateral injections of the nonselective CCK receptor antagonist proglumide or CCK-8 into the lateral parabrachial nuclei (LPBN) on the ingestion of 0.3 M NaCl and water induced by intracerebroventricular injection of ANG II or by a combined treatment with subcutaneous furosemide (Furo) + captopril (Cap). Compared with the injection of saline (vehicle), bilateral LPBN injections of proglumide (50 micrograms . 200 nl-1 . site-1) increased the intake of 0.3 M NaCl induced by intracerebroventricular ANG II (50 ng/1 microliter). Bilateral injections of proglumide into the LPBN also increased ANG II-induced water intake when NaCl was simultaneously available, but not when only water was present. Similarly, the ingestion of 0.3 M NaCl and water induced by the treatment with Furo (10 mg/kg) + Cap (5 mg/kg) was increased by bilateral LPBN proglumide pretreatment. Bilateral CCK-8 (0.5 microgram . 200 nl-1 . site-1) injections into the LPBN did not change Furo + Cap-induced 0.3 M NaCl intake but reduced water consumption. When only water was available after intracerebroventricular ANG II, bilateral LPBN injections of proglumide or CCK-8 had no effect or significantly reduced water intake compared with LPBN vehicle-treated rats. Taken together, these results suggest that CCK actions in the LPBN play a modulatory role on the control of NaCl and water intake induced by experimental treatments that induce hypovolemia and/or hypotension or that mimic those states.

Cholecystokinin octapeptide antagonized opioid analgesia mediated by μ- and κ- but not δ-receptors in the spinal cord of the rat

Intrathecal (ith) injection of cholecystokinin octapeptide (CCK-8) to the rat with single dose of 4 or 40 ng, or successive doses from 0.1 to 1 μg at 10 min intervals produced neither analgesia nor hyperalgesia. However, the analgesia produced by ith injection of PL017, a specific μ-receptor agonist or 66A-078, a specific κ-receptor agonist could be markedly antagonized by CCK-8 at a dose as small as 4 ng. In contrast, analgesia produced by ith injection of δ-agonist DPDPE could not be blocked by CCK-8 even at a dose as high as 40 ng. Since the effect of CCK-8 could be totally reversed by the CCK receptor antagonist proglumide, this effect is most probably mediated by CCK receptors.

Cholecystokinin facilitates ejaculation in male rats: blockade with proglumide and apomorphine

Systemic administration of the active, sulfated form of cholecystokinin-octapeptide (CCK-8S), at a dose known to inhibit dopamine (DA) release, significantly reduced the latency to ejaculate and number of intromissions preceding ejaculation in sexually active male rats. This effect was identical to that reported for low doses of the DA receptor agonist apomorphine, which bind preferentially to presynaptic DA autoreceptors. The facilitatory effect of CCK-8S on ejaculation was blocked by the putative CCK receptor antagonist proglumide and by a presynaptic dose of apomorphine. Blockade of the effect of CCK-8S with a presynaptic dose of apomorphine is consistent with CCK induction of depolarization block in DA neurons. These data suggest that CCK-8S and apomorphine may reduce the ejaculation threshold in sexually active male rats by inhibition of DA release via two different mechanisms of action.

Reversal by cholecystokinin of apomorphine-induced inhibition of dopamine release in the nucleus accumbens of the rat

In vivo electrochemical techniques were used to study the effects of the sulfated (CCK8-S) and unsulfated (CCK8-US) forms of cholecystokinin octapeptide on apomorphine-induced inhibition of dopamine (DA) release in the nucleus accumbens of the anesthetized rat. A dose-dependent inhibition of DA release was observed with intravenous (i.v.) injections of apomorphine. CCK8-S administered i.v. at the nadir of the apomorphine-induced inhibition of DA release produced a transient and dose-dependent increase followed by a prolonged decrease in DA release. CCK8-US was ineffective in altering apomorphine's inhibitory effects on DA release. The CCK receptor antagonist proglumide injected i.v. 10 min after apomorphine administration had no effect on apomorphine-induced inhibition of DA release, but blocked the effects of CCK8-S on this inhibition. Given that apomorphine may inhibit DA release by a direct hyperpolarizing action on DA neurons, the observation that CCK8-S temporarily reverses apomorphine-induced effects and further inhibits DA release suggests that CCK8-S exerts its inhibitory effects via a process of depolarization block in DA neurons. These findings indicate that apomorphine and CCK8-S may inhibit DA release in vivo by opposite effects on DA cell membrane potentials and suggest that endogenously released CCK may serve to modulate mesolimbic DA neurotransmission.

Role of cholecystokinin in the negative feedback control of pancreatic enzyme secretion in conscious rats

Using a specific radioimmunoassay for cholecystokinin (CCK) we have studied the relation between circulating CCK concentrations and the feedback regulation of pancreatic enzyme secretion in conscious rats. Recirculation of diverted bile-pancreatic juice into the duodenum or intraduodenal perfusion of trypsin during biliary-pancreatic juice diversion produced basal output of amylase and trypsin and low portal CCK levels (<10 pmol/L). Biliary-pancreatic juice diversion or inactivation of trypsin caused increased CCK concentrations (peak values 50–100 pmol/L) and enzyme outputs. During biliary-pancreatic juice diversion, infusion of the CCK receptor antagonist proglumide suppressed the enzyme response without altering the increase in CCK. Measurement of portal and peripheral CCK during biliary-pancreatic juice diversion yielded values of 131 ± 37 and 32 ± 5 pmol/L, respectively. The peripheral CCK levels corresponded to concentrations achieved during exogenous CCK-8 infusion which resulted in similar enzyme outputs. Gel chromatography of portal plasma during diversion of biliary-pancreatic juice revealed one peak of CCK corresponding to CCK-8, and a larger peak eluted between CCK-33 and CCK-8, probably representing CCK-22. Similar CCK components were found in water extracts of jejunal mucosa, whereas the acetic acid extracts mainly contained CCK-33/39. We conclude that the negative feedback regulation of pancreatic enzyme secretion in rats is mediated by the release of CCK from the intestine and that the major molecular form of CCK in plasma is probably CCK-22.

In vivo electrochemical analysis of cholecystokinin-induced inhibition of dopamine release in the nucleus accumbens

In vivo electrochemical techniques were used to study the effects of the sulfated (CCK 8-S) and unsulfated (CCK 8-US) forms of the cholecystokinin octapeptide on dopamine (DA) release in the nucleus accumbens. A dose-dependent inhibition of DA release was observed only with CCK 8-S. This inhibitory effect was blocked by the CCK receptor antagonist proglumide, and was reversed by systemic injections of apomorphine. Given that apomorphine can hyperpolarize DA neurons, these data indicate that CCK may inhibit the release of DA by a process of depolarization block and suggest a mechanism by which CCK may regulate overactive mesolimbic DA transmission.