Effect of prucalopride, a new enterokinetic agent, on gastrointestinal transit and anorectal function in healthy volunteers.
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BACKGROUND: Prucalopride (PR) is a novel 5-HT4 agonist enterokinetic compound. AIM: To evaluate its effect on bowel function, gut transit and anorectal function in healthy volunteers using a double-blind, placebo-controlled crossover study. METHODS: Twenty-four healthy volunteers (12 men, 12 women, mean age 25 years, range 20-53 years) were randomly assigned to 1 mg/placebo or 2 mg/placebo (PL). The trial consisted of five consecutive 1 week periods: no drug treatment, PR treatment or PL, washout, PL or PR, no treatment. Subjects maintained a diary of bowel function during the entire study period. Total intestinal transit time (TITT), mean colonic transit time (MCTT) and anorectal function (anal manometry, rectal sensitivity and rectal compliance) were assessed at the end of both treatment periods. Electrocardiography and blood sampling were performed for safety analysis; blood sampling was also used to check compliance. RESULTS: No subjects withdrew from the study. Treatment with PR 2 mg showed a statistically significant increase in mean number of weekly stools (11.5 vs. 7.1 compared to PL, P = 0.04) and in the percentage of loose/watery stools (48 vs. 12% compared to PL, P = 0.005). Within 1 week, stool frequency and consistency returned to baseline values when treatment was stopped. MCTT was shortened significantly with both doses, i.e. from 35 h on PL to 25 h on PR 1 mg (P = 0.01) and from 43 h on PL to 22 h on PR 2 mg (P = 0.02). Anorectal function was unaffected by PR. Transient and moderate headache occurred in nine subjects during PR treatment and in six subjects during PL treatment. CONCLUSION: Prucalopride is well tolerated by healthy subjects and has a marked and consistent effect on stool frequency and consistency, and on colonic transit. In the present study prucalopride did not affect visceral sensitivity or sphincter function. It holds promise for patients with slow transit constipation. (+info)
ATP-sensitive potassium channels and efaroxan-induced insulin release in the electrofusion-derived BRIN-BD11 beta-cell line.
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The properties of ATP-sensitive K+ (K(ATP)) channels were explored in the electrofusion-derived, glucose-responsive, insulin-secreting cell line BRIN-BD11 using patch-clamp techniques. In intact cells, K(ATP) channels were inhibited by glucose, the sulfonylurea tolbutamide, and the imidazoline compounds efaroxan and phentolamine. Each of these agents initiated insulin secretion and potentiated the actions of glucose. K(ATP) channels were blocked by ATP in a concentration-dependent manner and activated by ADP in the presence of ATP. In both intact cells and excised inside-out patches, the K(ATP) channel agonists diazoxide and pinacidil activated channels, and both compounds inhibited insulin secretion evoked by glucose, tolbutamide, and imidazolines. The mechanisms of action of imidazolines were examined in more detail. Pre-exposure of BRIN-BD11 cells to either efaroxan or phentolamine selectively inhibited imidazoline-induced insulin secretion but not the secretory responses of cells to glucose, tolbutamide, or a depolarizing concentration of KCl. These conditions did not result in the loss of depolarization-dependent rises in intracellular Ca2+ ([Ca2+]i), K(ATP) channel operation, or the actions of either ATP or efaroxan on K(ATP) channels. Desensitization of the imidazoline receptor following exposure to high concentrations of efaroxan, however, was found to result in an increase in SUR1 protein expression and, as a consequence, an upregulation of K(ATP) channel density. Our data provide 1) the first characterization of K(ATP) channels in BRIN-BD11 cells, a novel insulin-secreting cell line produced by electrofusion techniques, and 2) a further analysis of the role of imidazolines in the control of insulin release. (+info)
(-)1-(Benzofuran-2-yl)-2-propylaminopentane, [(-)BPAP], a selective enhancer of the impulse propagation mediated release of catecholamines and serotonin in the brain.
(27/1327)
1. The brain constituents beta-phenylethylamine (PEA) and tryptamine enhance the impulse propagation mediated transmitter release (exocytosis) from the catecholaminergic and serotoninergic neurons in the brain ('catecholaminergic/serotoninergic activity enhancer, CAE/SAE, effect'). (-)Deprenyl (Selegiline) and (-)1-phenyl-2-propylaminopentane [(-)PPAP] are amphetamine derived CAE substances devoid of the catecholamine releasing property. 2. By changing the aromatic ring in PPAP we developed highly potent and selective CAE/SAE substances, structurally unrelated to the amphetamines. Out of 65 newly synthetized compounds, a tryptamine derived structure, (-)1-(benzofuran-2-yl)-2-propylaminopentane [(-)BPAP] was selected as a potential follower of (-)deprenyl in the clinic and as a reference compound for further analysis of the CAE/SAE mechanism in the mammalian brain. 3. (-)BPAP significantly enhanced in 0.18 micromol 1(-1) concentration the impulse propagation mediated release of [(3)H]-noradrenaline and [(3)H]-dopamine and in 36 nmol 1(-1) concentration the release of [(3)H]-serotonin from the isolated brain stem of rats. The amount of catecholamines and serotonin released from isolated discrete rat brain regions (dopamine from the striatum, substantia nigra and tuberculum olfactorium, noradrenaline from the locus coeruleus and serotonin from the raphe) enhanced significantly in the presence of 10(-12) - 10(-14) M (-)BPAP. BPAP protected cultured hippocampal neurons from the neurotoxic effect of beta-amyloid in 10(-14) M concentration. In rats (-)BPAP significantly enhanced the activity of the catecholaminergic and serotoninergic neurons in the brain 30 min after acute injection of 0.1 microg kg(-1) s.c. In the shuttle box, (-)BPAP in rats was about 130 times more potent than (-)deprenyl in antagonizing tetrabenazine induced inhibition of performance. (+info)
The adrenergic receptor agonist, clonidine, potentiates the anti-parkinsonian action of the selective kappa-opioid receptor agonist, enadoline, in the monoamine-depleted rat.
(28/1327)
1. The treatment of Parkinson's disease relies predominantly upon dopamine replacement therapy, usually with l-dihydroxyphenylalanine (L-DOPA). However, side-effects of long-term treatment, such as L-DOPA-induced dyskinesias can be more debilitating than the disease itself. Non-dopaminergic treatment strategies might therefore be advantageous. 2. The aim of this study was to investigate the potential anti-parkinsonian efficacy of the kappa-opioid receptor agonist, enadoline, and the alpha-adrenoreceptor agonist, clonidine, both alone or in combination, in the reserpine-treated rat model of Parkinson's disease. 3. Rats were treated with reserpine (3 mg kg-1), and experiments carried out 18 h later, at which time they exhibited profound akinesia (normal animals 1251+/-228 mobile counts h-1, reserpine-treated animals 9+/-2 mobile counts h-1). Both enadoline and clonidine increased locomotion in reserpine-treated rats in a dose-dependent manner. The maximum locomotor-stimulating effect of enadoline alone was seen at a dose of 0.2 mg kg-1 (208+/-63 mobile counts h-1). The maximum effect of clonidine was seen at a dose of 2 mg kg-1 (536+/-184 mobile counts h-1). 4. Co-administration of enadoline (0.1 mg kg-1) and clonidine (0.01 - 0.1 mg kg-1) at sub-threshold doses, synergistically increased locomotion. 5. The synergistic stimulation of locomotion in the reserpine-treated rat involved activation of kappa-opioid receptors and a combination of both alpha1 and alpha2-adrenoreceptors. 6. The results presented suggest a need for further studies on the potential of stimulating kappa-opioid and/or alpha-adrenoreceptors as a therapy for Parkinson's disease. Furthermore, the studies may offer potential mechanistic explanations of the ability of alpha2-adrenergic receptor antagonist to reduce L-DOPA-induced dyskinesia in Parkinson's disease. (+info)
Serum polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans among people eating contaminated home-produced eggs and beef.
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We compared serum polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) among residents of two homes to levels among age- and sex-matched comparison subjects. The residents of the two homes consumed contaminated eggs and beef from animals raised at the homes. The animals had greater soil contact than those raised with conventional commercial husbandry practices. The comparison subjects were from a similar rural area, but did not consume home-produced beef and eggs. Serum levels of 2,3,7, 8-substituted tetra-, penta-, and hexaCDDs and penta-, hexa-, and heptaCDFs were increased between 2- and 6-fold in residents from one home; contaminated eggs and beef were consumed by residents for 2-15 years. Elevations were less for those in the other index home, where only home-produced eggs were consumed for 2 years; a 3-fold elevation of 1,2,3,7,8,9-hexaCDD as compared to controls was most apparent. Very strong bivariate correlations among all of the 2,3,7, 8 penta- and hexaCDDs/CDFs were observed. The elevations observed verify that PCDD/PCDF-contaminated food contributed to the body burden of these compounds. The blood levels among the highest exposed participants are generally higher than those observed in other studies of U.S. contaminated-fish consumers and higher than average adipose tissue levels observed in U.S. urban populations. There are sufficient animal toxicologic and human epidemiologic data to recommend that exposures be reduced. In the study area, pentachlorophenol and pentachlorophenol incineration sources have been identified, and the animal contamination and blood elevations probably reflect these sources. Soil reference values and site-specific risk assessments should include estimates of exposures to contamination in home-produced animal products. Such estimates can be verified with limited PCDD/PCDF sampling of animals and humans. (+info)
Effects of SK-951, a benzofuran derivative, as a prokinetic agent in rats and dogs.
(30/1327)
The gastrokinetic activity of SK-951 ((-)4-amino-N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-5-chloro-2,3-dihy dro-2-methylbenzo[b]furan-7-carboxamide hemifumarate), a benzofuran derivative with 5-hydroxytryptamine (5-HT)4-receptor agonist activity, was studied in rats and dogs. The effects of SK-951 were also investigated in a model of vagotomy-induced gastroparesis in comparison with cisapride. In rats, both SK-951 and cisapride enhanced gastric emptying of liquids (phenol red) at a dose of 1-100 mg/kg, p.o. Gastric emptying of liquid (acetaminophen) in fasted beagle dogs was enhanced significantly by SK-951 (1.0 mg/kg, i.v.), whereas the effect of cisapride (0.2-1.0 mg/kg, i.v.) was not statically significant. Similar results were found when radiopaque markers were given with standard meal to dogs with vagotomy-induced gastroparesis. The delayed gastric emptying of radiopaque markers by vagotomy was reversed by SK-951 (1.0 mg/kg, i.v.), whereas cisapride showed no effect at doses from 0.1 to 1.0 mg/kg, i.v. These results indicated that oral and intravenous administration of SK-951 accelerates gastric emptying of both liquids and solids in animal models. Thus, SK-951 may be a highly potent and useful prokinetic agent in comparison to cisapride. (+info)
Memnobotrins and memnoconols: novel metabolites from Memnoniella echinata.
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Four novel metabolites have been isolated from a rice culture of Memnoniella echinata (JS6308) by solvent extraction and radial silica chromatography. The structures were elucidated by spectroscopic techniques, and the absolute stereochemistry of memnobotrin A determined by X-ray crystallography. (+info)
dl-3-n-butylphthalide attenuates reperfusion-induced blood-brain barrier damage after focal cerebral ischemia in rats.
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AIM: To study the protective effect of dl-3-n-butylphthalide (NBP) on blood-brain barrier (BBB) damage induced by reperfusion following focal cerebral ischemia. METHODS: Focal cerebral ischemia in rats was performed by inserting a nylon suture into intracranial segment of internal carotid artery to block the origin of middle cerebral artery and reperfusion by withdrawing the nylon suture. Permeability of BBB was determined by extravasation of the protein-bound Evans blue dye to cerebral cortex and further evaluated by immunohistochemical or electronmicroscopic method. RESULTS: Reperfusion for 3 h following focal cerebral ischemia for 3 h produced BBB damage which exhibited the increase in extravasation in cerebral cortex, elevation of the expression of immunoglobulin (IgG), and pore formation in endothelial cell membrane of capillary in cerebral cortex. NBP (5-20 mg.kg-1) decreased the extravasation in a dose-dependent manner. The expression of IgG in cerebral cortex was decreased and the ultrastructure damage of capillaries was alleviated after treatment with NBP. NBP 20 mg.kg-1 also alleviated brain edema caused by 3-h reperfusion following 3-h middle cerebral artery occlusion (MCAO). CONCLUSION: NBP has protective effect on BBB damage induced by reperfusion after MCAO. (+info)