Obestatin was recently described as a bioactive peptide encoded for by the same gene as ghrelin but with opposite actions on food intake. Although some groups have confirmed these findings others ...find no effect. We investigated the effect of obestatin on feeding in rodents over a wide range of doses. Acute administration of obestatin inhibited feeding at doses of 10-100 nmol/kg i.p. in mice and 100-300 nmol/kg i.p. in lean and Zucker fatty rats. Interestingly, the dose-response relationship was U-shaped such that both low and high doses were without effect in either species. Treatment of mice with obestatin over a 7-day period decreased body weight gain and food consumption. Overall, obestatin suppressed food intake and body weight gain in rodent and an unusual dose-response relationship was found. These findings may explain the difficulties in reproducing the effects of obestatin on feeding reported by some groups.
The hypoxia-inducible factor (HIF) prolyl hydroxylase (PHD) enzymes represent novel targets for the treatment of anemia, ulcerative colitis, and ischemic and metabolic disease inter alia. We have ...identified a novel small-molecule inhibitor of PHD, 1-(5-chloro-6-(trifluoromethoxy)-1H-benzoimidazol-2-yl)-1H-pyrazole-4-carboxylic acid (JNJ-42041935), through structure-based drug design methods. The pharmacology of JNJ-42041935 was investigated in enzyme, cellular, and whole-animal systems and was compared with other compounds described in the literature as PHD inhibitors. JNJ-42041935, was a potent (pK(I) = 7.3-7.9), 2-oxoglutarate competitive, reversible, and selective inhibitor of PHD enzymes. In addition, JNJ-42041935 was used to compare the effect of selective inhibition of PHD to intermittent, high doses (50 μg/kg i.p.) of an exogenous erythropoietin receptor agonist in an inflammation-induced anemia model in rats. JNJ-42041935 (100 μmol/kg, once a day for 14 days) was effective in reversing inflammation-induced anemia, whereas erythropoietin had no effect. The results demonstrate that JNJ-42041935 is a new pharmacological tool, which can be used to investigate PHD inhibition and demonstrate that PHD inhibitors offer great promise for the treatment of inflammation-induced anemia.
Transient receptor potential vanilloid 1 (TRPV1) plays an integral role in modulating the cough reflex, and it is an attractive antitussive drug target. The purpose of this study was to characterize ...a TRPV1 antagonist, 4-(3-trifluoromethyl-pyridin-2-yl)-piperazine-1-carboxylic acid (5-trifluoromethyl-pyridin-2-yl)-amide (JNJ17203212), against the guinea pig TRPV1 receptor in vitro followed by a proof-of-principle study in an acid-induced model of cough. The affinity of JNJ17203212 for the recombinant guinea pig TRPV1 receptor was estimated by radioligand binding, and it was functionally characterized by antagonism of low-pH and capsaicin-induced activation of the ion channel (fluorometric imaging plate reader and electrophysiology). The nature of antagonism was further tested against the native channel in isolated guinea pig tracheal rings. Following pharmacokinetic characterization of JNJ17203212 in guinea pigs, pharmacodynamic and efficacy studies were undertaken to establish the antitussive efficacy of the TRPV1 antagonist. The pK(i) of JNJ17203212 for recombinant guinea pig TRPV1 was 7.14 +/- 0.06. JNJ17203212 inhibited both pH (pIC(50) of 7.23 +/- 0.05) and capsaicin (pIC(50) of 6.32 +/- 0.06)-induced channel activation. In whole-cell patch clamp, the pIC(50) for inhibition of guinea pig TRPV1 was 7.3 +/- 0.01. JNJ17203212 demonstrated surmountable antagonism in isolated trachea, with a pK(B) value of 6.2 +/- 0.1. Intraperitoneal administration of 20 mg/kg JNJ17203212 achieved a maximal plasma exposure of 8.0 +/- 0.4 microM, and it attenuated capsaicin evoked coughs with similar efficacy to codeine (25 mg/kg). Last, JNJ17203212 dose-dependently produced antitussive efficacy in citric acid-induced experimental cough in guinea pigs. Our data provide preclinical support for developing TRPV1 antagonists for the treatment of cough.
Background and Purpose
Small‐molecule inhibitors of prolyl hydroxylase (PHD) enzymes are a novel target for the treatment of anaemia and functional iron deficiency (FID). Other than being orally ...bioavailable, the differentiation of PHD inhibitors from recombinant human erythropoietin (rhEPO) has not been demonstrated.
Experimental Approach
JNJ‐42905343 was identified and characterized as a novel inhibitor of PHD and its action was compared with rhEPO in healthy rats and in a rat model of inflammation‐induced anaemia and FID peptidoglycan‐polysaccharide (PGPS) model.
Key Results
Oral administration of JNJ‐42905343 to healthy rats increased the gene expression of cytochrome b (DcytB) and divalent metal‐ion transporter 1 (DMT1) in the duodenum, and increased plasma EPO. Repeated administration of JNJ‐42905343 for 28 days increased blood haemoglobin, mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV). The serum iron concentration was increased with low doses (0.3 mg·kg−1) but reduced at high doses (6 mg·kg−1). In PGPS‐treated rats, administration of JNJ‐42905343 for 28 days corrected FID and anaemia, as reflected by increased blood haemoglobin, MCH and MCV. Increased expression of DcytB and DMT1 genes in the duodenum resulting in increased iron availability was defined as the mechanism for these effects. rhEPO did not affect DcytB and DMT1 and was not effective in PGPS‐treated rats.
Conclusions and Implications
PHD inhibition has a beneficial effect on iron metabolism in addition to stimulating the release of EPO. Small‐molecule inhibitors of PHD such as JNJ‐42905343 represent a mechanism distinct from rhEPO to treat anaemia and FID.
Asthma research is arguably limited by an absence of appropriate animal models to study the pharmacology of inflammatory mediators that affect airway hyperresponsiveness and remodelling. Here we ...assessed an assay based on mouse tracheal segments cultured for 1–32 days, and investigated contractile responses mediated by muscarinic and 5‐hydroxytryptamine (5‐HT) receptors following long‐term exposure to tumour necrosis factor‐alpha (TNFα).
Following culture, in the absence of TNFα, maximum contractile responses to KCl and carbachol were similar, with an increase in response up to day two and a decrease to a stable level after 8 days. Maximal relaxations to isoprenaline were not affected by the culture procedure. The potency of KCl and isoprenaline increased throughout the study. DNA microarray data revealed that global gene expression changes were greater when tissues were introduced to culture than when they were maintained in culture. The morphology of smooth muscle cells was maintained throughout the culture period.
5‐HT induced a weak contraction in both fresh and cultured (up to 8 days) segments. Culture with TNFα produced a time‐ and concentration‐dependent increase in the maximal contraction to 5‐HT, evidently mediated by 5‐HT
2A
receptors, whereas, the potency for carbachol was reduced.
In conclusion, the phenotype of airway smooth muscle remained largely intact during the culture period, even though minor changes were obtained during the first days of culture. The time‐dependent effect of TNFα indicates the importance of studying the long‐term effect of cytokines on the smooth muscle cells in relation to airway hyperresponsiveness and remodelling.
British Journal of Pharmacology
(2002)
137
, 971–982. doi:
10.1038/sj.bjp.0704928
The scientific legacy of Sir James W. Black Page, Clive P; Schaffhausen, Joanna; Shankley, Nigel P
Trends in pharmacological sciences (Regular ed.),
04/2011, Letnik:
32, Številka:
4
Journal Article
A series of indeno1,2-
cpyrazoles were discovered to be the first known inhibitors of heme-regulated eukaryotic initiation factor 2α (HRI) kinase. The synthesis, structure–activity relationship ...profile, and in-vitro pharmacological characterization of this inaugural series of HRI kinase inhibitors are detailed.
The peptide ligand neuromedin U (NMU) has been implicated in an array of biological activities, including contraction of uterine, intestinal and urinary bladder smooth muscle. However, many of these ...responses appear to be species‐specific. This study was undertaken to fully elucidate the range of smooth muscle‐stimulating effects of NMU in rats, mice and guinea‐pigs, and to examine the extent of the species differences. In addition, the NMU1 receptor knockout mouse was used to determine which receptor subtype mediates the contractile responses generated by NMU in the mouse.
A range of isolated organ in vitro bioassays were carried out, which were chosen to re‐confirm previous literature reports (uterine and stomach fundus contraction) and also to explore potentially novel smooth muscle responses to NMU. This investigation uncovered a number of previously unidentified NMU‐mediated responses: contraction of rat lower esophageal sphinster (LES), rat ileum, mouse gallbladder, enhancement of electrically evoked contractions in rat and mouse vas deferens, and a considerable degree of cross‐species differences.
Studies using the NMU1 receptor knockout mice revealed that in the mouse fundus and gallbladder assays the NMU contractile response was mediated entirely through the NMU1 receptor subtype, whereas, in assays of mouse uterus and vas deferens, the response to NMU was unchanged in the NMU1 receptor knockout mouse, suggesting that the NMU response may be mediated through the NMU2 receptor subtype. NMU receptor subtype‐selective antagonists are required to further elucidate the role of the individual receptor subtypes.
British Journal of Pharmacology (2006) 147, 886–896. doi:10.1038/sj.bjp.0706677
HIF prolyl 4-hydroxylases (PHD) are a family of enzymes that mediate key physiological responses to hypoxia by modulating the levels of hypoxia inducible factor 1-α (HIF1α). Certain ...benzimidazole-2-pyrazole carboxylates were discovered to be PHD2 inhibitors using ligand- and structure-based methods and found to be potent, orally efficacious stimulators of erythropoietin secretion in vivo.
A new molecular modeling approach has been used to derive a pharmacophore of the potent and selective cholecystokinin-2 (CCK2) receptor antagonist 5 (JB93182), based on features shared with two ...related series. The technique uses “field points” as simple and effective descriptions of the electrostatic and van der Waals maxima and minima surrounding a molecule equipped with XED (extended electron distribution) charges. Problems associated with the high levels of biliary elimination of 5 in vivo required us to design a compound with significantly lower molecular weight without sacrificing its nanomolar levels of in vitro activity. Two new series of compounds were designed to mimic the arrangement of field points present in the pharmacophore rather than its structural elements. In a formal sense, two of the three amides in 5 were replaced with either a simple pyrrole or imidazole, while some features thought to be essential for the high levels of in vitro activity of the parent compounds were retained and others deleted. These compounds maintained activity and selectivity for this receptor over CCK1. In addition, the reduction in molecular weight coupled with lower polarities greatly reduced levels of biliary elimination associated with 5. This makes them good lead compounds for development of drug candidates whose structures are not obviously related to those of the parents and represents the first example of scaffold hopping using molecular field points.
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