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The CCK-A receptor antagonist, devazepide, blocks the anorectic action of CCK but not peripheral serotonin in rats.

A role has been proposed for cholecystokinin (CCK)-A-type receptors in mediating the anorectic action produced by serotonergic stimulation in rats. We examined the effect of pretreatment with the CCK-A antagonist devazepide (DVZ) on anorexia produced by peripheral administration of serotonin [5-hydroxytryptamine (5-HT)] or CCK-8 in 3-h food-deprived rats consuming a 30-min test meal of sweetened mash. The anorectic effect of CCK-8 (4.0 nmol/kg, IP) was antagonized in a dose-dependent manner by DVZ (0.03, 0.10, and 0.30 mumol/kg, IP), with even the lowest dose producing a significant reversal. Under identical testing conditions, a supramaximal dose of DVZ (.75 mumol/kg) did not attenuate the reductions in food intake produced by either a moderate (4.0 mumol/kg) or a high dose (10.0 mumol/kg) of 5-HT. These data confirm established findings that the anorectic action of peripheral CCK depends upon CCK-A receptors. However, peripherally administered 5-HT reduces food intake independently of CCKergic function.

Animals↗

Reduction of [125I]Bolton Hunter CCK8 and [3H]MK-329 (devazepide) binding to CCK receptors in the substantia nigra/VTA complex and its forebrain projection areas following MPTP-induced hemi-parkinsonism in the monkey.

Cholecystokinin (CCK) receptors were visualized autoradiographically using [125I]Bolton Hunter CCK8 ([125I]BHCCK8) in the fore- and midbrain of 3 monkeys rendered hemi-parkinsonian by unilateral intra-carotid infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). More specifically, CCK-A receptors were detected using [3H]MK-329 (devazepide), a peripheral-type (CCK-A) receptor antagonist. In the substantia nigra pars compacta, ipsilateral to the toxin infusion, where dopamine D2 receptors (labelled with [3H]sulpiride) were lost, there was a decrease in the binding of both [125I]BHCCK8 and [3H]MK-329. Binding of the two CCK ligands was also reduced in the ipsilateral nucleus accumbens and most medial part of the caudate nucleus, whereas 3H-sulpiride binding was increased in the lateral caudate nucleus and putamen. These results indicate that CCK-A receptors may be located on dopaminergic cells within the substantia nigra, which are lost in the parkinsonian brain, and may also be present on dopaminergic terminals within restricted regions of nigral/ventral tegmental area projection sites.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

Devazepide reversed effect of sincalide against morphine on rat jejunal activities.

AIM: To study the antagonism of sincalide to the effect of morphine and its mechanism. METHODS: The electrophysiologic and mechanic activities of rat jejunum in vitro were recorded. RESULTS: Acetylcholine (ACh, 150 nmol.L-1) increased the spike potential amplitude (SPA) and the number (SPN) of rat jejunum in vitro, followed by an increase of jejunal contraction amplitudes (CA), showing a positive correlation. Morphine 330 nmol.L-1 inhibited the potentiation of ACh, showing a negative correlation. Sincalide 0.7 nmol.L-1 antagonized the effects of morphine, i.e., the SPA and SPN were increased again, followed by an increase of CA. CCK-A receptor antagonist devazepide (10 nmol.L-1) reversed the antagonism of sincalide to the effect of morphine. CONCLUSION: Sincalide antagonized the effect of morphine which inhibited the potentiation of ACh on jejunal activities in vitro. The antagonistic effect of sincalide on morphine was mainly mediated by CCK-A receptor.

Action Potentials↗

Effect of the CCKA antagonist devazepide on eating stimulated by raphe injection of 8-OH-DPAT.

Several recent studies have suggested that feeding suppression is mediated jointly by enhanced neurotransmission of cholecystokinin (CCK) and serotonergic (5-HT) systems. In the present study the CCKA receptor antagonist devazepide (50-200 micrograms kg-1, s.c.) was found reliably to potentiate the feeding response elicited by dorsal or median raphe injection of the 5-HT1A agonist 8-OH-DPAT (0.2-0.8 nmol). This effect was evident following co-administration of both feeding threshold and subthreshold doses of either compound, suggesting that the simultaneous suppression of CCK and 5-HT function may interact as joint effectors of overeating.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

Effect of devazepide reversed antagonism of CCK-8 against morphine on electrical and mechanical activities of rat duodenum in vitro.

AIM:To study the antagonism of cholecystokinin octapeptide (CCK-8) against the effect of morphine and its mechanism.METHODS:The method of simultaneously recording the electrical and mechanical activities of rat duodenum in vitro was adopted.RESULTS:Acetylcholine (ACh) could increase the amplitude and the number of the spike potential (SPA and SPN of rat duodenum in vitro, followed by the increase of the duodenal contraction amplitudes (CA), showing a positive correlation. Morphine, on the contrary, inhibited the potentiation of ACh, showing a negative correlation. CCK-8 could antagonize the effects of morphine, i.e. th SPA and SPN were increased again, followed by the increase of CA. On the basis of the above, CCK-A receptor antagonist Devazepide could reverse the antagonism of CCK-8 to the effect of morphine.CONCLUSION:CCK-8 could antagonize the effect of morphine which inhibited the potentiation of ACh on the duodenal activities in vitro.Furthermore, it was inferred that the antagonistic effect of CCK-8 on morphine was mainly mediated by CCK-A receptor.

Journal Article↗

Differential involvement of CCK-A and CCK-B receptors in the regulation of locomotor activity in the mouse.

The influence of the CCK-A antagonist devazepide and the CCK-B/gastrin antagonist L-365,260 on the locomotor activity of mice was studied. Devazepide and L-365,260 had opposite effects on spontaneous locomotor activity, and on caerulein- and apomorphine-induced hypomotility in the mouse. Devazepide in high doses (0.1-1 mg/kg IP) reduced spontaneous motor activity, whereas L-365,260 at a high dose (1 mg/kg IP) increased the activity of mice. Devazepide (0.1-10 micrograms/kg) moderately antagonized the sedative effect of apomorphine (0.1 mg/kg SC) and caerulein (25 micrograms/kg SC), whereas L-365,260 (1-10 micrograms/kg) significantly potentiated the actions of dopamine and CCK agonists. Concomitant administration of caerulein (15 micrograms/kg SC) and apomorphine (0.1 mg/kg SC) caused an almost complete loss of locomotor activity in the mouse. Devazepide and L-365,260 (0.1-10 micrograms/kg) were completely ineffective against caerulein-induced potentiation of apomorphine hypomotility. Devazepide in high doses (0.1-1 mg/kg), reducing the spontaneous motor activity of mice, counteracted the motor excitation induced by d-amphetamine (5 mg/kg IP). The CCK agonist caerulein (100 micrograms/kg SC) had a similar antiamphetamine effect. Devazepide (1-100 micrograms/kg) and L-365,260 (1 micrograms/kg) reversed completely the antiamphetamine effect of caerulein. The results of present study reflect apparently distinct role of CCK-A and CCK-B receptors in the regulation of motor activity. The opposite effect of devazepide and L-365,260 on caerulein- and apomorphine-induced hypolocomotion is probably related to the antagonistic role of CCK-A and CCK-B receptor subtypes in the regulation of mesencephalic dopaminergic neurons. The antiamphetamine effect of caerulein is possibly linked to the stimulation of CCK-A receptors in the mouse brain, whereas the blockade of both subtypes of the CCK-8 receptor is involved in the antiamphetamine effect of devazepide.

Amphetamine↗

Intracerebroventricular cholecystokinin A-receptor antagonist does not reduce satiation by endogenous CCK.

Suppression of sham feeding by exogenous CCK-8 or intraintestinal oleate infusion is attenuated by peripheral administration of the CCK-A receptor antagonist, devazepide, but not by the CCK-B antagonist, L365260. Likewise, systemically administered devazepide increases food intake by real feeding rats. These results suggest that endogenous CCK participates in the reduction of food intake by intestinal oleate and ingested food. Although originally categorized as a "peripheral" receptor subtype, the CCK-A receptor is also present in the brain. In an effort to examine whether devazepide acts in the brain or in the periphery to attenuate suppression of food intake by intraintestinal oleate, we injected devazepide into the lateral or fourth cerebral ventricles of intraintestinally infused, sham-fed rats. We also compared the ability of intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) devazepide to elicit increased food intake in real feeding rats. Doses of devazepide that were sufficient to attenuate or abolish oleate-induced suppression of sham feeding, when administered i.p., failed to attenuate suppression of intake when administered i.c.v., i.p. devazepide also was more effective than i.c.v. devazepide for attenuation of the suppression of sham feeding by i.p. injection of exogenous CCK-8. Finally, i.c.v. devazepide was ineffective for increasing real food intake, whereas the same dose administered i.p. significantly increased food intake. Our results do not support participation of brain CCK-A receptors in the suppression of food intake by exogenous CCK, or by endogenous CCK released after intraintestinal oleate infusion, or food intake.

Animals↗

Changes in motor activity and forebrain [propionyl-3H]propionylated-CCK-8 binding in mice after repeated administration of drugs affecting cholecystokinin receptors.

The effects of acute or repeated treatment of male albino BKW mice with caerulein, a cholecystokinin octapeptide (CCK-8) agonist, and with devazepide (MK-329) and L-365,260, antagonists at CCKA ('peripheral') and CCKB ('central') receptors respectively, on motor activity and [propionyl-3H]propionylated-CCK-8 ([3H]pCCK-8) binding were studied. Acute treatment with a large dose of caerulein (100 micrograms/kg s.c.) suppressed motor activity (line crossings and rearings) whereas devazepide (2 mg/kg i.p.) had the opposite action. L-365,260 (2 mg/kg i.p.) increased only the number of rearings. Tolerance developed to the locomotor effects of caerulein and devazepide when these same doses were administered once daily (caerulein) or twice daily (devazepide) for 10 days. Twice daily administration of L-365,260 (2 mg/kg) for 10 days did not significantly alter the locomotor activity of mice. The sedative effect of caerulein (20 micrograms/kg s.c.) was markedly reduced in mice receiving repeated injections of either a larger amount of caerulein (100 micrograms/kg) or devazepide but not after L-365,260. The stimulant effect of (+)-amphetamine (2 mg/kg s.c.) on motor activity was increased by subchronic administration of either devazepide or caerulein, but not by L-365,260. All three compounds (caerulein, devazepide and L-365,260) increased the number of [( 3H]pCCK-8 binding sites in mouse forebrain but the increase was only significant after L-365,260. The effects of long-term treatment with caerulein are probably related to the stimulation of CCKA receptors, whereas the paradoxically similar action of devazepide may be linked to the blockade of both subtypes of the CCK-8 receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Pharmacological evaluation of IQM-95,333, a highly selective CCKA receptor antagonist with anxiolytic-like activity in animal models.

1. The pyridopyrimidine derivative IQM-95,333 ((4aS,5R)-2-benzyl-5-[N alpha-tert-butoxicarbonyl)L-tryptophyl] amino-1,3dioxoperhydropyrido[1,2-c]pyrimidine), a new non-peptide antagonist of cholecystokinin type A (CCKA) receptors, has been evaluated in vitro and in vivo in comparison with typical CCKA and CCKB receptor antagonists, such as devazepide, lorglumide, L-365,260 and PD-135,158. 2. IQM-95,333 displaced [3H]-CCK-8S binding to CCKA receptors from rat pancreas with a high potency in the nanomolar range. Conversely, the affinity of this new compound at brain CCKB receptors was negligible (IC50 > 10 microM). IQM-95,333 was a more selective CCKA receptor ligand than devazepide and other CCKA receptor antagonists. 3. Like devazepide, IQM-95,333 was a more potent antagonist of CCK-8S- than of CCK-4-induced contraction of the longitudinal muscle from guinea-pig ileum, suggesting selective antagonism at CCKA receptors. 4. IQM-95,333 and devazepide were also potent inhibitors of CCK-8S-stimulated amylase release from isolated pancreatic acini, a CCKA receptor-mediated effect. The drug concentrations required (IC50s around 20 nM) were higher than in binding studies to pancreas homogenates. 5. Low doses (50-100 micrograms kg-1, i.p.) of IQM-95,333 and devazepide, without any intrinsic effect on food intake or locomotion, blocked the hypophagia and the hypolocomotion induced by systemic administration of CCK-8S, two effects associated with stimulation of peripheral CCKA receptors. 6. IQM-95,333 showed an anxiolytic-like profile in the light/dark exploration test in mice over a wide dose range (10-5,000 micrograms kg-1). Typical CCKA and CCKB antagonists, devazepide and L-365,260 respectively, were only effective within a more limited dose range. 7. In a classical conflict paradigm for the study of anxiolytic drugs, the punished-drinking test, IQM-95,333, devazepide and L-365,260 were effective within a narrow dose range. The dose-response curve for the three drugs was biphasic, suggesting that other mechanisms are operative at higher doses. 8. In conclusion, IQM-95,333 is a potent and selective CCKA receptor antagonist both in vitro and in vivo with an anxiolytic-like activity in two different animal models, which can only be attributed to blockade of this CCK receptor subtype.

Amylases↗

Role of endogenous CCK in the inhibition of gastric emptying by peptone and Intralipid in rats.

To assess the role of endogenous cholecystokinin in the control of gastric emptying of peptone solutions and Intralipid suspensions, we examined the ability of a dose range of the CCK-A antagonist, devazepide to accelerate the gastric emptying of various caloric concentrations of peptone and Intralipid in rats. In the absence of devazepide, both peptone and Intralipid emptying slowed with increasing concentration. Devazepide's effect on peptone gastric emptying diminished with increasing peptone concentration. The threshold dose for accelerating the emptying of 0.2 kcal/ml peptone was lower than the threshold dose for affecting 0.5 kcal/ml peptone and devazepide had no effect on the gastric emptying of 1.0 kcal/ml peptone. In contrast, devazepide affected Intralipid gastric emptying at all three Intralipid concentrations and the threshold dose decreased with increasing Intralipid concentration. However, the magnitude of the effect of devazepide on peptone or Intralipid gastric emptying was partial and did not increase as a function of concentration. These data demonstrate a role for endogenous CCK in the emptying of peptone and Intralipid but suggest that endogenous CCK does not account for the increased slowing of gastric emptying evident with increased caloric concentration.

Animals↗

Continuous infusion of cholecystokinin leads to down-regulation of the cholecystokinin-A receptor in the rat pancreas.

BACKGROUND: Infusion of sulphated cholecystokinin-8 (CCK-8S) in rats transiently increased the proliferation of pancreatic acinar cells, whereas the CCK-A receptor antagonist devazepide decreased such proliferation. This effect ceased after 3 days. CCK-8S or devazepide injected twice daily induced a persistent effect on the cell proliferation involving the major cells of the exocrine pancreas. The aim of this study was to examine the effect of continuous infusion of CCK-8S and devazepide on CCK-A receptor gene expression. METHODS: Male Sprague-Dawley rats received subcutaneous continuous infusion of 5 microg/kg/h CCK-8S, 200 microg/kg/h devazepide, or 1% bovine serum albumin (BSA) by means of osmotic minipumps. The rats were killed after 4 days; I h before being killed they received 5-bromo-2-deoxyuridine (BrdU) intraperitoneally. Plasma was collected for analysis of CCK. The pancreas was dissected, and indirect immunofluorescence for BrdU and CCK-A receptor was performed. In situ hybridization to CCK-A receptor mRNA was performed for examination and semiquantification of receptor gene expression. RESULTS: Continuous infusion of CCK-8S led to a sixfold increase in plasma CCK and a 40% increase in pancreatic weight. Devazepide did not affect the CCK level but decreased the pancreatic weight by 24% compared with BSA-infused rats. The BrdU labeling indicated that CCK-8S had no effect on cell proliferation. Immunofluorescence for the CCK-A receptor showed a decreased labeling intensity after CCK-8S infusion. The mean optical density of in situ hybridization labeling of the sections from CCK-8S-treated rats was decreased to 37% +/- 3% of that in controls. Devazepide did not affect the CCK-A receptor gene expression. CONCLUSIONS: Continuous stimulation of the CCK-A receptor led to a downregulation of the receptor gene expression in pancreatic acinar cells and decreased labeling of the receptor at immunohistochemistry. The results suggest that down-regulation of the receptor is a protective mechanism against overstimulation.

Animals↗

Cholecystokinin satiety involves CCKA receptors perfused by the superior pancreaticoduodenal artery.

Three experiments compared the potency of the type A cholecystokinin (CCKA)-receptor antagonist devazepide for increasing intake of 30% sucrose when injected into the superior pancreaticoduodenal (SPD) artery (SPD group) or jugular vein (IV group). In experiment 1, 15 min of sucrose intake in adult, male Sprague-Dawley rats after 6 h of food deprivation was increased by devazepide (20 micrograms/kg) administered into the SPD artery whether given alone or in conjunction with cholecystokinin octapeptide (CCK-8, 2 micrograms/kg ip). Devazepide had no effect in the IV group. In experiment 2, injection of 8, 20, and 50 micrograms/kg of devazepide into the SPD artery increased sucrose intake of nondeprived rats. Only the highest dose was effective in the IV group. On subsequent tests, administration of 1 microgram/kg of CCK-8 significantly suppressed intake only in the SPD group. In experiment 3, nondeprived rats with SPD artery and jugular vein catheters were tested in a within-subjects design. Devazepide (20 micrograms/kg) increased sucrose intake after injection into the SPD artery, but not into the jugular vein. In experiment 4, intraduodenal devazepide (8, 20, and 50 micrograms/kg) had no effect. These results indicate that CCKA receptors within the SPD arterial bed mediate the satiating action of CCK, consistent with local action of duodenal CCK.

Animals↗

Role of cholecystokinin in the anorexia produced by duodenal delivery of peptone in rats.

We used the cholecystokinin receptor antagonist devazepide to assess the importance of CCK in mediating the anorexia produced by 2-h duodenal infusions of peptone, a protein digest, at dark onset in nonfasted rats. Peptone alone (0.14-2.24 g/h) suppressed food intake dose dependently by 18-96%, with an approximate half-maximal dose of 1 g/h. Peptone-induced reductions in caloric ingestion were comparable to the caloric loads infused. Devazepide alone (30-1,000 microgram/kg) stimulated food intake dose dependently by 30-73%, with a minimal effective dose of 100 micrograms/kg. Devazepide appeared to reverse the anorexic response to peptone (1.1 g/h) dose dependently by 29-65%, with a minimal effective dose of 30 micrograms/kg. The magnitudes of these devazepide-induced effects were similar to, and in some cases were larger than, those produced when the same doses of devazepide were administered alone. Coadministration of devazepide (1,000 micrograms/kg) and a lower peptone dose (0.8 g/h) produced similar results. These results suggest that an essential CCK mechanism plays a significant role in mediating the satiety response to duodenal delivery of protein.

Animals↗

Reactivation of cocaine conditioned place preference induced by stress is reversed by cholecystokinin-B receptors antagonist in rats.

The effects of different cholecystokinin (CCK) receptor antagonists (devazepide and L365,260) on cocaine or stress-induced reactivation of cocaine conditioned place preference (CPP) were investigated in rats. After receiving alternate injection of cocaine (10 mg/kg) and saline for 8 consecutive days, the rats spent more time in the drug-paired side (cocaine CPP) on day 9. These animals did not show cocaine CPP on day 31 following saline-paired training daily from days 10 to 30 (21-day extinction). However, a single injection of cocaine (10 mg/kg) or 15 min of intermittent footshock could reinstate CPP on day 32 with significant more time spent in the drug-paired side in comparison with that on day 0. Systemic injection of CCK-A receptor antagonists, devazepide (0.1 and 1 mg/kg, i.p.), 30 min before cocaine priming, significantly attenuated cocaine-induced reinstatement of CPP, while CCK-B receptor antagonist, L365,260 (0.1 and 1 mg/kg, i.p.), did not show a similar effect. In contrast, pretreatment with L365,260 (0.1 and 1 mg/kg, i.p.) but not devazepide (0.1 and 1 mg/kg, i.p.) significantly blocked stress-induced reinstatement of CPP. In another experiment, CCK-A or B receptor antagonists were infused into nucleus accumbens or amygdala to determine which brain area are involved in the role of different CCK receptors in stress or drug-induced relapse to cocaine seeking. The results show that infusion of the devazepide (10 microg) into the nucleus accumbens significantly inhibited the cocaine-induced reinstatement of CPP, while infusion of devazepide (1 and 10 microg) into amygdala did not affect cocaine-induced reactivation of CPP. Interestingly, infusion of L365,260 (1 and 10 microg) into both nucleus accumbens or amygdala significantly attenuated or blocked stress-induced reinstatement of CPP. These findings demonstrate that CCK-A and B receptor have different roles in relapse to drug craving and further suggest that the brain areas involved in the CCK receptors on reinstatement of drug seeking are not identical. CCK-B receptor antagonists might be of some value in the treatment and prevention of relapse to stress-induced to drug craving following long-term detoxification.

Animals↗