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Sample records for aldosterone receptor antagonist

  1. Effect of aldosterone breakthrough on albuminuria during treatment with a direct renin inhibitor and combined effect with a mineralocorticoid receptor antagonist.

    PubMed

    Sato, Atsuhisa; Fukuda, Seiichi

    2013-10-01

    We have reported observing aldosterone breakthrough in the course of relatively long-term treatment with renin-angiotensin (RA) system inhibitors, where the plasma aldosterone concentration (PAC) increased following an initial decrease. Aldosterone breakthrough has the potential to eliminate the organ-protective effects of RA system inhibitors. We therefore conducted a study in essential hypertensive patients to determine whether aldosterone breakthrough occurred during treatment with the direct renin inhibitor (DRI) aliskiren and to ascertain its clinical significance. The study included 40 essential hypertensive patients (18 men and 22 women) who had been treated for 12 months with aliskiren. Aliskiren significantly decreased blood pressure and plasma renin activity (PRA). The PAC was also decreased significantly at 3 and 6 months; however, the significant difference disappeared after 12 months. Aldosterone breakthrough was observed in 22 of the subjects (55%). Urinary albumin excretion differed depending on whether breakthrough occurred. For the subjects in whom aldosterone breakthrough was observed, eplerenone was added. A significant decrease in urinary albumin excretion was observed after 1 month, independent of changes in blood pressure. In conclusion, this study demonstrated that aldosterone breakthrough occurs in some patients undergoing DRI therapy. Aldosterone breakthrough affects the drug's ability to improve urinary albumin excretion, and combining a mineralocorticoid receptor antagonist with the DRI may be useful for decreasing urinary albumin excretion. When the objective is organ protection in hypertensive patients, a two-pronged approach using combination therapy to inhibit both the RA system and aldosterone may be highly effective.

  2. The risks and benefits of therapy with aldosterone receptor antagonist therapy.

    PubMed

    Sica, Domenic A

    2007-01-01

    Spironolacotone and eplerenone are mineralocorticoid-blocking agents. These compounds block both the epithelial and non-epithelial actions of aldosterone with the latter assuming increasing clinical importance. Spironolactone and eplerenone both effectively reduce blood pressure either as mono- or add-on therapy; moreover, they each offer survival benefits in diverse circumstances of heart failure and the potential for renal protection in proteinuric chronic kidney disease. However, as the use of mineralocorticoid-blocking agents has increased the hazards inherent to use of such drugs has become more apparent. Whereas; the endocrine side-effects of spironolactone are in most cases little more than a cosmetic annoyance the potassium-sparing effects of both spironolactone and eplerenone can prove fatal if sufficient degrees of hyperkalemia develop. However, for most patients the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered as a possibility in any patient receiving one or the other of these medications. As such, steps should be taken to lessen the likelihood of its occurring if therapy is being contemplated with agents in this class.

  3. Aldosterone and mineralocorticoid receptors in the cardiovascular system.

    PubMed

    Funder, John W

    2010-01-01

    Aldosterone is currently thought to exert its physiologic effects by activating epithelial mineralocorticoid receptors, and its pathologic effects on the cardiovascular system via mineralocorticoid receptors in the heart and blood vessels. Recent studies have extended this understanding to include a reevaluation of the roles of aldosterone and mineralocorticoid receptor activation in blood pressure control; the rapid, nongenomic effects of aldosterone; the role of cortisol as a mineralocorticoid receptor agonist under conditions of redox change/tissue damage/reactive oxygen species generation; the growing consensus that primary aldosteronism accounts for approximately 10% of all essential hypertension; recent new insights into the cardioprotective role of spironolactone; and the development of third- and fourth-generation mineralocorticoid receptor antagonists for use in cardiovascular and other inflammatory disease. These findings on aldosterone action and mineralocorticoid receptor blockade are analyzed in the context of the prevention and treatment of cardiovascular disease.

  4. Role of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and aldosterone antagonists in the prevention of atrial and ventricular arrhythmias.

    PubMed

    Makkar, Kathy M; Sanoski, Cynthia A; Spinler, Sarah A

    2009-01-01

    Atrial arrhythmias, ventricular arrhythmias, and sudden cardiac death (SCD) are significant health problems and an economic burden to society. The renin-angiotensin-aldosterone system (RAAS) may play a key role in the occurrence of structural and electrical remodeling, potentially explaining the development of atrial and ventricular arrhythmias. Angiotensin II has been shown to regulate cardiac cell proliferation and to modulate cardiac myocyte ion channels. Results of post hoc analyses from prospective clinical trials appear to show that angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are most effective in the prevention of new-onset atrial fibrillation in patients with heart failure. It is difficult to determine if these agents are useful in the prevention of new-onset atrial fibrillation after myocardial infarction, and available evidence suggests that the benefit of ACE inhibitors and ARBs for prevention of new-onset atrial fibrillation in patients with hypertension appears limited to those with left ventricular hypertrophy. Patients with structural changes in cardiac muscle, such as those with heart failure and left ventricular hypertrophy, appear to benefit the most from RAAS blockade, possibly due to the theory of reversal of cardiac remodeling. There is no evidence, to our knowledge, that either ACE inhibitors or ARBs facilitate direct electrical current cardioversion in patients with atrial fibrillation; however, it appears that RAAS blockade may be useful in the prevention of recurrent atrial fibrillation after direct electrical current cardioversion. Whether ACE inhibitors may prevent life-threatening ventricular arrhythmias or SCD is unclear. Aldosterone antagonists appear to be useful for the prevention of SCD in patients with left ventricular systolic dysfunction. Results from ongoing clinical trials are anticipated to provide further insight on the potential roles of RAAS inhibitors for the prevention of

  5. Renin-angiotensin-aldosterone system inhibition: overview of the therapeutic use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and direct renin inhibitors.

    PubMed

    Mercier, Kelly; Smith, Holly; Biederman, Jason

    2014-12-01

    Angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) therapy in hypertensive diabetic patients with macroalbuminuria, microalbuminuria, or normoalbuminuria has been repeatedly shown to improve cardiovascular mortality and reduce the decline in glomerular filtration rate. Renin-angiotensin-aldosterone system (RAAS) blockade in normotensive diabetic patients with normoalbuminuria or microalbuminuria cannot be advocated at present. Dual RAAS inhibition with ACE inhibitors plus ARBs or ACE inhibitors plus direct renin inhibitors has failed to improve cardiovascular or renal outcomes but has predisposed patients to serious adverse events.

  6. The Impact Exerted on Clinical Outcomes of Patients With Chronic Heart Failure by Aldosterone Receptor Antagonists: A Meta-Analysis of Randomized Controlled Trials

    PubMed Central

    De Vecchis, Renato; Cantatrione, Claudio; Mazzei, Damiana; Barone, Augusto; Maurea, Nicola

    2017-01-01

    Background Aldosterone receptor antagonists (ARAs) have been associated with improved clinical outcomes in patients with heart failure with reduced left ventricular ejection fraction (HFREF), but not in those with heart failure with preserved left ventricular ejection fraction (HFpEF). With the aim to study this topic more deeply, we carried out a meta-analysis of selective and non-selective ARAs in HFREF and HFpEF. Methods We searched PubMed and Scopus databases. We decided to incorporate in the meta-analysis only randomized controlled trials (RCTs) of ARAs in patients with chronic heart failure (CHF) if they met the following criteria: experimental groups included patients with CHF treated with ARAs in addition to the conventional therapy; control groups included patients with CHF receiving conventional therapy without ARAs. Outcomes of interest were all-cause death, hospitalizations from cardiovascular cause, hyperkalemia, or gynecomastia. Results We detected 15 studies representing 15,671 patients. ARAs were associated with a reduced odds of all-cause death (odds ratio (OR): 0.79; 95% confidence interval (CI): 0.73 - 0.87) and hospitalizations from cardiovascular cause (OR: 0.73; 95% CI: 0.61 - 0.89). However, subgroup analysis showed that these advantages were limited to HFREF (all-cause death: OR: 0.77, 95% CI: 0.69 - 0.84; hospitalizations from cardiovascular cause: OR: 0.66, 95% CI: 0.51 - 0.85), but they did not affect the HFpEF group (all-cause death: OR: 0.91, 95% CI: 0.76 - 1.1; hospitalizations from cardiovascular cause: OR: 0.85, 95% CI: 0.7 - 1.09). ARAs increased the risk of hyperkalemia (OR: 2.17; 95% CI: 1.88 - 2.5). Non-selective ARAs, but not selective ARAs, increased the risk of gynecomastia (OR: 8.22, 95% CI: 4.9 - 13.81 vs. OR: 0.74, 95% CI: 0.43 - 1.27). Conclusions ARAs reduced the risk of adverse cardiac events in HFREF but not HFpEF. In particular, ARA use in HFpEF patients is questionable, since in this CHF type, no significant

  7. Azilsartan, aliskiren, and combination antihypertensives utilizing renin-angiotensin-aldosterone system antagonists.

    PubMed

    Lanier, Gregg; Sankholkar, Kedar; Aronow, Wilbert S

    2014-01-01

    Health care providers managing hypertension (HTN) have a large selection of pharmacologic agents to choose from, including several different classes of drugs and many similar drugs within each class. Antagonism of the renin-angiotensin-aldosterone system has been shown to be very effective for HTN, especially in patients with cardiovascular disease, diabetes, and heart failure. Within this group, there have been 2 new agents recently introduced to the US market and approved by the Food and Drug Administration. It is important for the HTN specialist to be familiar with the merits of these 2 drugs: the angiotensin receptor blocker Edarbi (azilsartan) and the renin inhibitor Tekturna (aliskiren). Additionally, there have been several new, fixed-dose combination antihypertensives introduced to the market since 2006 that use a renin-angiotensin-aldosterone antagonist. Seven of these combine 2 drugs together in a single pill: Edarbyclor (azilsartan/chlorthalidone), Exforge (amlodipine/valsartan), Azor (olmesartan/amlodipine), Twynsta (amlodipine/telmisartan), Tekturna HCT [aliskiren/hydrochlorothiazide (HCTZ)], Valturna (aliskiren/valsartan), Tekamlo (aliskiren/amlodipine). Three triple-drug combination medications have also been introduced recently: Exforge HCT (amlodipine/valsartan/HCTZ), Tribenzor (olmesartan/amlodipine/HCTZ), and Amturnide (aliskiren/amlodipine/hydrocholorothiazide). This review will summarize the trial data and important pharmacologic merits of these 2 new renin-angiotensin-aldosterone antagonists and the advantages of initiating treatment with one of the new fixed-dose, combination drugs approved over the last 5 years.

  8. SP 01-3 ALDOSTERONE ANTAGONISTS IN HEART FAILURE.

    PubMed

    Johnston, Colin

    2016-09-01

    Aldosterone's deleterious pathophysiological effects on the cardiovascular system if blocked by mineralcorticord antagonists (MRAs) logically should lead to improvement in heart function and outcomes in heart failure (HF). The first trial to test this hypothesis was tthe RALES trial in 1999 which treated patients with class III-IV HF with spironolactone. It showed significant reduction in mortality and cardiovascular hospitalzation rates. This was confirmed & extended in EMHASIS-HF RCT with classs II-III being treated with ACEIs & BB who received placebo or elperinone (a MRA) with again a statistically significant fall in mortality & hospitalization.The possible cardioprotective effects of MRA post acute myocardial infarct (MI) is less clear. The EPHESUS RCT in 2003 demostrated that elperinone given 3-14 days AMI in patients with early signs of HF reduced mortality & morbidity. However in the ALBTROSS trial using spironolactone 2 days after AMI showed no benfit in patients without HF but in a subgroup with ST elevation there was a 80% reduction in mortality after 6 months. However a recent meta-analysis from 25 RCT with data invovling 19,333 patients with either HF or post MI assigned aldosterone antagonists (AA)or placebo showed a 18% reduction in mortality including a 20% fall in CV mortality and a 19% reduction in SCD.The role of AA in HFPEF is even even more contraversial. The TOPCAT RCT of 3445 patients with symptomatc HFPEF randomised to spironolactone failed to meet the primary composite end point of death, aborted cardiac arrest or hospitalization although there was a reduction in hospitalization for HF (HR 0.83 P = 0.04).The differences between selective or non-selective MRAs, their ADRs & off target effects will also be discussed.

  9. Aldosterone-induced brain MAPK signaling and sympathetic excitation are angiotensin II type-1 receptor dependent.

    PubMed

    Zhang, Zhi-Hua; Yu, Yang; Wei, Shun-Guang; Felder, Robert B

    2012-02-01

    Angiotensin II (ANG II)-induced mitogen-activated protein kinase (MAPK) signaling upregulates angiotensin II type-1 receptors (AT(1)R) in hypothalamic paraventricular nucleus (PVN) and contributes to AT(1)R-mediated sympathetic excitation in heart failure. Aldosterone has similar effects to increase AT(1)R expression in the PVN and sympathetic drive. The present study was undertaken to determine whether aldosterone also activates the sympathetic nervous system via MAPK signaling and, if so, whether its effect is independent of ANG II and AT(1)R. In anesthetized rats, a 4-h intravenous infusion of aldosterone induced increases (P < 0.05) in phosphorylated (p-) p44/42 MAPK in PVN, PVN neuronal excitation, renal sympathetic nerve activity (RSNA), mean blood pressure (MBP), and heart rate (HR). Intracerebroventricular or bilateral PVN microinjection of the p44/42 MAPK inhibitor PD-98059 reduced the aldosterone-induced RSNA, HR, and MBP responses. Intracerebroventricular pretreatment (5 days earlier) with pooled small interfering RNAs targeting p44/42 MAPK reduced total and p-p44/42 MAPK, aldosterone-induced c-Fos expression in the PVN, and the aldosterone-induced increases in RSNA, HR, and MBP. Intracerebroventricular infusion of either the mineralocorticoid receptor antagonist RU-28318 or the AT(1)R antagonist losartan blocked aldosterone-induced phosphorylation of p44/42 MAPK and prevented the increases in RSNA, HR, and MBP. These data suggest that aldosterone-induced sympathetic excitation depends upon that AT(1)R-induced MAPK signaling in the brain. The short time course of this interaction suggests a nongenomic mechanism, perhaps via an aldosterone-induced transactivation of the AT(1)R as described in peripheral tissues.

  10. Muscarinic Receptor Antagonists.

    PubMed

    Matera, Maria Gabriella; Cazzola, Mario

    2017-01-01

    Parasympathetic activity is increased in patients with chronic obstructive pulmonary disease (COPD) and asthma and appears to be the major reversible component of airway obstruction. Therefore, treatment with muscarinic receptor antagonists is an effective bronchodilator therapy in COPD and also in asthmatic patients. In recent years, the accumulating evidence that the cholinergic system controls not only contraction by airway smooth muscle but also the functions of inflammatory cells and airway epithelial cells has suggested that muscarinic receptor antagonists could exert other effects that may be of clinical relevance when we must treat a patient suffering from COPD or asthma. There are currently six muscarinic receptor antagonists licenced for use in the treatment of COPD, the short-acting muscarinic receptor antagonists (SAMAs) ipratropium bromide and oxitropium bromide and the long-acting muscarinic receptor antagonists (LAMAs) aclidinium bromide, tiotropium bromide, glycopyrronium bromide and umeclidinium bromide. Concerns have been raised about possible associations of muscarinic receptor antagonists with cardiovascular safety, but the most advanced compounds seem to have an improved safety profile. Further beneficial effects of SAMAs and LAMAs are seen when added to existing treatments, including LABAs, inhaled corticosteroids and phosphodiesterase 4 inhibitors. The importance of tiotropium bromide in the maintenance treatment of COPD, and likely in asthma, has spurred further research to identify new LAMAs. There are a number of molecules that are being identified, but only few have reached the clinical development.

  11. The aldosterone-mineralocorticoid receptor pathway exerts anti-inflammatory effects in endotoxin-induced uveitis.

    PubMed

    Bousquet, Elodie; Zhao, Min; Ly, André; Leroux Les Jardins, Guillaume; Goldenberg, Brigitte; Naud, Marie-Christine; Jonet, Laurent; Besson-Lescure, Bernadette; Jaisser, Frederic; Farman, Nicolette; De Kozak, Yvonne; Behar-Cohen, Francine

    2012-01-01

    We have previously shown that the eye is a mineralocorticoid-sensitive organ and we now question the role of mineralocorticoid receptor (MR) in ocular inflammation. The endotoxin-induced uveitis (EIU), a rat model of human intraocular inflammation, was induced by systemic administration of lipopolysaccharide (LPS). Evaluations were made 6 and 24 hours after intraocular injection of aldosterone (simultaneous to LPS injection). Three hours after onset of EIU, the MR and the glucocorticoid metabolizing enzyme 11-beta hydroxysteroid dehydrogenase type 2 (11β-HSD2) expression were down-regulated in iris/ciliary body and the corticosterone concentration was increased in aqueous humor, altering the normal MR/glucocorticoid receptor (GR) balance. At 24 hours, the GR expression was also decreased. In EIU, aldosterone reduced the intensity of clinical inflammation in a dose-dependent manner. The clinical benefit of aldosterone was abrogated in the presence of the MR antagonist (RU26752) and only partially with the GR antagonist (RU38486). Aldosterone reduced the release of inflammatory mediators (6 and 24 hours: TNF-α, IFN-γ, MIP-1α) in aqueous humor and the number of activated microglia/macrophages. Aldosterone partly prevented the uveitis-induced MR down-regulation. These results suggest that MR expression and activation in iris/ciliary body could protect the ocular structures against damages induced by EIU.

  12. The Diuretic Torasemide Does Not Prevent Aldosterone-Mediated Mineralocorticoid Receptor Activation in Cardiomyocytes

    PubMed Central

    Gravez, Basile; Tarjus, Antoine; Jimenez-Canino, Ruben; El Moghrabi, Soumaya; Messaoudi, Smail; de la Rosa, Diego Alvarez; Jaisser, Frederic

    2013-01-01

    Aldosterone binds to the mineralocorticoid receptor (MR) and exerts pleiotropic effects beyond enhancing renal sodium reabsorption. Excessive mineralocorticoid signaling is deleterious during the evolution of cardiac failure, as evidenced by the benefits provided by adding MR antagonists (MRA) to standard care in humans. In animal models of cardiovascular diseases, MRA reduce cardiac fibrosis. Interestingly diuretics such as torasemide also appear efficient to improve cardiovascular morbidity and mortality, through several mechanisms. Among them, it has been suggested that torasemide could block aldosterone binding to the MR. To evaluate whether torasemide acts as a MRA in cardiomyocytes, we compared its effects with a classic MRA such as spironolactone. We monitored ligand-induced nuclear translocation of MR-GFP and MR transactivation activity in the cardiac-like cell line H9C2 using a reporter gene assay and known endogenous aldosterone-regulated cardiac genes. Torasemide did not modify MR nuclear translocation. Aldosterone-induced MR transactivation activity was reduced by the MRA spironolactone, not by torasemide. Spironolactone blocked the induction by aldosterone of endogenous MR-responsive genes (Sgk-1, PAI-1, Orosomucoid-1, Rgs-2, Serpina-3, Tenascin-X), while torasemide was ineffective. These results show that torasemide is not an MR antagonist; its association with MRA in heart failure may however be beneficial, through actions on complementary pathways. PMID:24040049

  13. Mineralocorticoid receptor antagonists and endothelial function

    PubMed Central

    Maron, Bradley A.; Leopold, Jane A.

    2010-01-01

    Hyperaldosteronism has been associated with endothelial dysfunction and impaired vascular reactivity in patients with hypertension or congestive heart failure. The mineralocorticoid receptor (MR) antagonists spironolactone and eplerenone have been shown to reduce morbidity and mortality, in part, by ameliorating the adverse effects of aldosterone on vascular function. Although spironolactone and eplerenone are increasingly utilized in patients with cardiovascular disease, widespread clinical use is limited by the development of gynecomastia with spironolactone and hyperkalemia with both agents. This suggests that the development of newer agents with favorable side effect profiles is warranted. PMID:18729003

  14. Finerenone Impedes Aldosterone-dependent Nuclear Import of the Mineralocorticoid Receptor and Prevents Genomic Recruitment of Steroid Receptor Coactivator-1*

    PubMed Central

    Amazit, Larbi; Le Billan, Florian; Kolkhof, Peter; Lamribet, Khadija; Viengchareun, Say; Fay, Michel R.; Khan, Junaid A.; Hillisch, Alexander; Lombès, Marc; Rafestin-Oblin, Marie-Edith; Fagart, Jérôme

    2015-01-01

    Aldosterone regulates sodium homeostasis by activating the mineralocorticoid receptor (MR), a member of the nuclear receptor superfamily. Hyperaldosteronism leads todeleterious effects on the kidney, blood vessels, and heart. Although steroidal antagonists such as spironolactone and eplerenone are clinically useful for the treatment of cardiovascular diseases, they are associated with several side effects. Finerenone, a novel nonsteroidal MR antagonist, is presently being evaluated in two clinical phase IIb trials. Here, we characterized the molecular mechanisms of action of finerenone and spironolactone at several key steps of the MR signaling pathway. Molecular modeling and mutagenesis approaches allowed identification of Ser-810 and Ala-773 as key residues for the high MR selectivity of finerenone. Moreover, we showed that, in contrast to spironolactone, which activates the S810L mutant MR responsible for a severe form of early onset hypertension, finerenone displays strict antagonistic properties. Aldosterone-dependent phosphorylation and degradation of MR are inhibited by both finerenone and spironolactone. However, automated quantification of MR subcellular distribution demonstrated that finerenone delays aldosterone-induced nuclear accumulation of MR more efficiently than spironolactone. Finally, chromatin immunoprecipitation assays revealed that, as opposed to spironolactone, finerenone inhibits MR, steroid receptor coactivator-1, and RNA polymerase II binding at the regulatory sequence of the SCNN1A gene and also remarkably reduces basal MR and steroid receptor coactivator-1 recruitment, unraveling a specific and unrecognized inactivating mechanism on MR signaling. Overall, our data demonstrate that the highly potent and selective MR antagonist finerenone specifically impairs several critical steps of the MR signaling pathway and therefore represents a promising new generation MR antagonist. PMID:26203193

  15. Pharmacological treatment of aldosterone excess.

    PubMed

    Deinum, Jaap; Riksen, Niels P; Lenders, Jacques W M

    2015-10-01

    Primary aldosteronism, caused by autonomous secretion of aldosterone by the adrenals, is estimated to account for at least 5% of hypertension cases. Hypertension explains the considerable cardiovascular morbidity caused by aldosteronism only partly, calling for specific anti-aldosterone drugs. The pharmacology of aldosterone is complex due to high homology with other steroids, the resemblance of steroid receptors, and the common pathways of steroid synthesis. Classically, pharmacological treatment of aldosteronism relied on the mineralocorticoid receptor (MR) antagonist spironolactone, which is highly effective, but causes considerable, mainly sexual side-effects due to limited selectivity for the MR. New agents have been developed or are being developed that aim at higher selectivity for MR antagonists (eplerenone, dihydropyridine-derived calcium channel blockers (CCB)), or inhibition of aldosterone synthesis. Eplerenone is less potent than spironolactone, but causes fewer adverse effects due to its selectivity for the MR. Non-steroidal MR antagonists have been developed from dihydropyridine CCBs, having lost their CCB activity and being highly selective for the MR. The first clinical studies with these drugs are underway. Aldosterone synthase inhibitors are an attractive alternative, but are prone to interference with cortisol synthesis due to the inhibition of 11-β-hydroxylation, an essential step in both cortisol and aldosterone synthesis, and accumulation of mineralocorticoid precursors. In coming years clinical research will provide the answers as to which drugs and strategies to treat high-aldosterone states are the most effective.

  16. Angiotensin receptor blocker drugs and inhibition of adrenal beta-arrestin-1-dependent aldosterone production: Implications for heart failure therapy

    PubMed Central

    Lymperopoulos, Anastasios; Aukszi, Beatrix

    2017-01-01

    Aldosterone mediates many of the physiological and pathophysiological/cardio-toxic effects of angiotensin II (AngII). Its synthesis and secretion from the zona glomerulosa cells of the adrenal cortex, elevated in chronic heart failure (HF), is induced by AngII type 1 receptors (AT1Rs). The AT1R is a G protein-coupled receptor, mainly coupling to Gq/11 proteins. However, it can also signal through β-arrestin-1 (βarr1) or -2 (βarr2), both of which mediate G protein-independent signaling. Over the past decade, a second, Gq/11 protein-independent but βarr1-dependent signaling pathway emanating from the adrenocortical AT1R and leading to aldosterone production has become appreciated. Thus, it became apparent that AT1R antagonists that block both pathways equally well are warranted for fully effective aldosterone suppression in HF. This spurred the comparison of all of the currently marketed angiotensin receptor blockers (ARBs, AT1R antagonists or sartans) at blocking activation of the two signaling modes (G protein-, and βarr1-dependent) at the AngII-activated AT1R and hence, at suppression of aldosterone in vitro and in vivo. Although all agents are very potent inhibitors of G protein activation at the AT1R, candesartan and valsartan were uncovered to be the most potent ARBs at blocking βarr activation by AngII and at suppressing aldosterone in vitro and in vivo in post-myocardial infarction HF animals. In contrast, irbesartan and losartan are virtually G protein-“biased” blockers at the human AT1R, with very low efficacy for βarr inhibition and aldosterone suppression. Therefore, candesartan and valsartan (and other, structurally similar compounds) may be the most preferred ARB agents for HF pharmacotherapy, as well as for treatment of other conditions characterized by elevated aldosterone.

  17. [Mineralocorticoid receptor antagonists and therapeutic strategies of cardiovascular damage].

    PubMed

    Verdugo, Fernando J; Montellano, Felipe A; Carreño, Juan E; Marusic, Elisa T

    2014-01-01

    In recent years, much attention has focused on the role of aldosterone and mineralocorticoid receptors (MRs) in the pathophysiology of hypertension and cardiovascular disease. Patients with primary aldosteronism, in whom angiotensin II levels are low, have a higher incidence of cardiovascular complications than patients with essential hypertension. The Randomized Aldactone Evaluation Study (RALES) demonstrated that adding a non-specific MR antagonist, spironolactone, to a standard therapy that included angiotensin-converting enzyme (ACE) inhibitors, loop diuretics, and digoxin, significantly reduced morbidity and mortality in patients with moderate to severe heart failure. Similarly, the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS) showed that the addition of a selective MR antagonist (ARM), eplerenone, to an optimal medical therapy reduces morbidity and mortality among patients with acute myocardial infarction complicated by left ventricular dysfunction and heart failure. These data suggest that aldosterone induces cardiac injury through activation of MRs and support the notion that MR blockade has beneficial effects on aldosterone-dependent cardiac injury, through mechanisms that cannot be simply explained by hemodynamic changes. Although, MRA are highly effective in patients with heart failure, the risk of hyperkalemia should not be overlooked. Serious hyperkalemia events were reported in some MRA clinical trials; however these risks can be mitigated through appropriate patient selection, dose selection, patient education, monitoring, and follow-up.

  18. Renal Aldosterone Receptors: Studies with [3H]Aldosterone and the Anti-Mineralocorticoid [3H]Spirolactone (SC-26304)

    PubMed Central

    Marver, Diana; Stewart, John; Funder, John W.; Feldman, David; Edelman, Isidore S.

    1974-01-01

    In vivo, a spirolactone (SC-26304) inhibited the effects of aldosterone on urinary K+:Na+ ratios and the binding of [3H]aldosterone to renal cytoplasmic and nuclear receptors. Cytoplasmic binding of [3H]aldosterone and [3H]spirolactone (SC-26304) was similar in magnitude and involved the same set of sites. Under three sets of conditions—(i) in the intact rat, (ii) in kidney slices, and (iii) in reconstitution studies (mixing prelabeled cytoplasm with either purified renal nuclei or chromatin), [3H]spirolactone (SC-26304) did not yield specific nuclear complexes in contrast to the reproducible generation of these complexes with [3H]aldosterone. In glycerol density gradients, cytoplasmic [3H]aldosterone receptor complexes sedimented at 8.5 S and 4 S in low concentrations of salt and at 4.5 S in high concentrations of salt. Cytoplasmic [3H]spirolactone (SC-26304) receptor complexes sedimented at 3 S in low concentrations of salt and 4 S in high concentrations of salt. These results are discussed in terms of an allosteric model of the receptor system. Images PMID:4364539

  19. Type I receptors in parotid, colon, and pituitary are aldosterone selective in vivo

    SciTech Connect

    Sheppard, K.; Funder, J.W. )

    1987-10-01

    Previous in vivo studies have demonstrated that type I receptors in the rat kidney are aldosterone selective, whereas those in the hippocampus do not appear to discriminate between aldosterone and corticosterone. The authors have injected mature rats with ({sup 3}H)aldosterone or ({sup 3}H)corticosterone plus 100-fold excess of RU 28362, with or without unlabeled aldosterone or corticosterone, and compared type I receptor occupancy in two classic mineralocorticoid target tissues (parotid and colon) and in the pituitary. Mature rats were killed 10-180 min after tracer administration; ({sup 3}H)aldosterone was well taken up and retained in all tissues, whereas ({sup 3}H)corticosterone was significantly retained only in the pituitary 10 min after tracer administration. To assess a possible role for corticosterone-binding globulin (CBG) in conferring aldosterone specificity on type I receptors, 10-day-old rats (with very low levels of CBG) were similarly injected. In the colon and parotid, ({sup 3}H)aldosterone binding was at least an order of magnitude higher than that of corticosterone; in the pituitary aldosterone binding was approximately three times that of corticosterone. They interpret these data as evidence that in the parotid and colon type I receptors are aldosterone selective by a non-CBG-requiring mechanism, whereas in the pituitary there appear to be both aldosterone-selective and nonselective type I sites.

  20. The L-, N-, and T-type triple calcium channel blocker benidipine acts as an antagonist of mineralocorticoid receptor, a member of nuclear receptor family.

    PubMed

    Kosaka, Hiromichi; Hirayama, Kazunori; Yoda, Nobuyuki; Sasaki, Katsutoshi; Kitayama, Tetsuya; Kusaka, Hideaki; Matsubara, Masahiro

    2010-06-10

    Aldosterone-induced activation of mineralocorticoid receptor, a member of the nuclear receptor family, results in increased tissue damage such as vascular inflammation and cardiac and perivascular fibrosis. Benidipine, a long-lasting dihydropyridine calcium channel blocker, is used for hypertension and angina. Benidipine exhibits pleiotropic pharmacological features such as renoprotective and cardioprotective effects through triple blockade of L-, N-, and T-type calcium channels. However, the mechanism of additional beneficial effects on end-organ damage is poorly understood. Here, we examined the effects of benidipine and other calcium channel blockers on aldosterone-induced mineralocorticoid receptor activation using luciferase reporter assay system. Benidipine showed more potent activity than efonidipine, amlodipine, or azelnidipine. Benidipine depressed the response to higher concentrations of aldosterone, whereas pretreatment of eplerenone, a steroidal mineralocorticoid receptor antagonist, did not. Binding studies using [(3)H] aldosterone indicated that benidipine and other calcium channel blockers competed for binding to mineralocorticoid receptor. Benidipine and other calcium channel blockers showed antagonistic activity on Ser810 to Leu mutant mineralocorticoid receptor, which is identified in patients with early-onset hypertension. On the other hand, eplerenone partially activated the mutant. Results of analysis using optical isomers of benidipine indicated that inhibitory effect of aldosterone-induced mineralocorticoid receptor activation was independent of its primary blockade of calcium channels. These results suggested that benidipine directly inhibits aldosterone-induced mineralocorticoid receptor activation, and the antagonistic activity might contribute to the drug's pleiotropic pharmacological features.

  1. Third Generation Mineralocorticoid Receptor Antagonists; Why We Need a Fourth

    PubMed Central

    Gomez-Sanchez, Elise

    2015-01-01

    The first mineralocorticoid receptor (MR) antagonist, spironolactone, was developed almost 60 years ago to treat primary aldosteronism and pathological edema. Its use waned in part due to its lack of selectivity. Subsequently knowledge of the scope of MR function was expanded along with clinical evidence of the therapeutic importance of MR antagonists to prevent the ravages of inappropriate MR activation. Forty-two years elapsed between the first and MR-selective second generation of MR antagonists. Fifteen years later, despite serious shortcomings of the existing antagonists, a third generation antagonist has yet to be marketed. Progress has been slowed by the lack of appreciation of the large variety of cell types that express the MR and its diverse cell-type-specific actions, as well as its uniquely complex interactions actions at the molecular level. New MR antagonists should preferentially target the inflammatory and fibrotic effects of MR and perhaps its excitatory effects on sympathetic nervous system, but not the renal tubular epithelium or neurons of the cortex and hippocampus. This review briefly describes efforts to develop a third generation MR antagonist and why fourth generation antagonists and selective agonists based on structural determinants of tissue and ligand-specific MR activation should be contemplated. PMID:26466326

  2. Safety profile of mineralocorticoid receptor antagonists: Spironolactone and eplerenone.

    PubMed

    Lainscak, Mitja; Pelliccia, Francesco; Rosano, Giuseppe; Vitale, Cristiana; Schiariti, Michele; Greco, Cesare; Speziale, Giuseppe; Gaudio, Carlo

    2015-12-01

    Spironolactone was first developed over 50 years ago as a potent mineralocorticoid receptor antagonist with undesirable side effects; it was followed a decade ago by eplerenone, which is less potent but much more mineralocorticoid receptor-specific. From a marginal role as a potassium-sparing diuretic, spironolactone has been shown to be an extraordinarily effective adjunctive agent in the treatment of progressive heart failure. Also, spironolactone is safe and protective in arterial hypertension, particularly in patients with so-called resistant hypertension. Eplerenone is the second oral aldosterone antagonist available for the treatment of arterial hypertension and heart failure. Treatment with eplerenone has been associated with decreased blood pressure and improved survival for patients with heart failure and reduced left ventricular ejection fraction. Due to the selectivity of eplerenone for the aldosterone receptor, severe adverse effects such as gynecomastia and vaginal bleeding seem to be less likely in patients who take eplerenone than in those who take spironolactone. The most common and potentially dangerous side effect of spironolactone--hyperkalemia--is also observed with eplerenone but the findings from clinical trials do not indicate more hyperkalemia induced drug withdrawals. Treatment with eplerenone should be initiated at a dosage of 25mg once daily and titrated to a target dosage of 50mg once daily preferably within 4 weeks. Serum potassium levels and renal function should be assessed prior to initiating eplerenone therapy, and periodic monitoring is recommended, especially in patients at high risk of developing hyperkalemia.

  3. The use of plasma aldosterone and urinary sodium to potassium ratio as translatable quantitative biomarkers of mineralocorticoid receptor antagonism

    PubMed Central

    2011-01-01

    Background Accumulating evidence supports the role of the mineralocorticoid receptor (MR) in the pathogenesis of diabetic nephropathy. These findings have generated renewed interest in novel MR antagonists with improved selectivity against other nuclear hormone receptors and a potentially reduced risk of hyperkalemia. Characterization of novel MR antagonists warrants establishing translatable biomarkers of activity at the MR receptor. We assessed the translatability of urinary sodium to potassium ratio (Na+/K+) and plasma aldosterone as biomarkers of MR antagonism using eplerenone (Inspra®), a commercially available MR antagonist. Further we utilized these biomarkers to demonstrate antagonism of MR by PF-03882845, a novel compound. Methods The effect of eplerenone and PF-03882845 on urinary Na+/K+ and plasma aldosterone were characterized in Sprague-Dawley rats and spontaneously hypertensive rats (SHR). Additionally, the effect of eplerenone on these biomarkers was determined in healthy volunteers. Drug exposure-response data were modeled to evaluate the translatability of these biomarkers from rats to humans. Results In Sprague-Dawley rats, eplerenone elicited a rapid effect on urinary Na+/K+ yielding an EC50 that was within 5-fold of the functional in vitro IC50. More importantly, the effect of eplerenone on urinary Na+/K+ in healthy volunteers yielded an EC50 that was within 2-fold of the EC50 generated in Sprague-Dawley rats. Similarly, the potency of PF-03882845 in elevating urinary Na+/K+ in Sprague-Dawley rats was within 3-fold of its in vitro functional potency. The effect of MR antagonism on urinary Na+/K+ was not sustained chronically; thus we studied the effect of the compounds on plasma aldosterone following chronic dosing in SHR. Modeling of drug exposure-response data for both eplerenone and PF-03882845 yielded EC50 values that were within 2-fold of that estimated from modeling of drug exposure with changes in urinary sodium and potassium excretion

  4. High potassium promotes mutual interaction between (pro)renin receptor and the local renin-angiotensin-aldosterone system in rat inner medullary collecting duct cells.

    PubMed

    Xu, Chuanming; Fang, Hui; Zhou, Li; Lu, Aihua; Yang, Tianxin

    2016-10-01

    (Pro)renin receptor (PRR) is predominantly expressed in the collecting duct (CD) with unclear functional implication. It is not known whether CD PRR is regulated by high potassium (HK). Here, we aimed to investigate the effect of HK on PRR expression and its role in regulation of aldosterone synthesis and release in the CD. In primary rat inner medullary CD cells, HK augmented PRR expression and soluble PPR (sPRR) release in a time- and dose-dependent manner, which was attenuated by PRR small interfering RNA (siRNA), eplerenone, and losartan. HK upregulated aldosterone release in parallel with an increase of CYP11B2 (cytochrome P-450, family 11, subfamily B, polypeptide 2) protein expression and upregulation of medium renin activity, both of which were attenuated by a PRR antagonist PRO20, PRR siRNA, eplerenone, and losartan. Similarly, prorenin upregulated aldosterone release and CYP11B2 expression, both of which were attenuated by PRR siRNA. Interestingly, a recombinant sPRR (sPRR-His) also stimulated aldosterone release and CYP11B2 expression. Taken together, we conclude that HK enhances a local renin-angiotensin-aldosterone system (RAAS), leading to increased PRR expression, which in turn amplifies the response of the RAAS, ultimately contributing to heightened aldosterone release.

  5. Aldosterone Induces Renal Fibrosis and Inflammatory M1-Macrophage Subtype via Mineralocorticoid Receptor in Rats

    PubMed Central

    Martín-Fernández, Beatriz; Rubio-Navarro, Alfonso; Cortegano, Isabel; Ballesteros, Sandra; Alía, Mario; Cannata-Ortiz, Pablo; Olivares-Álvaro, Elena; Egido, Jesús; de Andrés, Belén; Gaspar, María Luisa; de las Heras, Natalia; Lahera, Vicente; Moreno, Juan Antonio

    2016-01-01

    We aimed to evaluate macrophages heterogeneity and structural, functional and inflammatory alterations in rat kidney by aldosterone + salt administration. The effects of treatment with spironolactone on above parameters were also analyzed. Male Wistar rats received aldosterone (1 mgkg-1d-1) + 1% NaCl for 3 weeks. Half of the animals were treated with spironolactone (200 mg kg-1d-1). Systolic and diastolic blood pressures were elevated (p<0.05) in aldosterone + salt–treated rats. Relative kidney weight, collagen content, fibronectin, macrophage infiltrate, CTGF, Col I, MMP2, TNF-α, CD68, Arg2, and SGK-1 were increased (p<0.05) in aldosterone + salt–treated rats, being reduced by spironolactone (p<0.05). Increased iNOS and IFN-γ mRNA gene expression (M1 macrophage markers) was observed in aldosterone + salt rats, whereas no significant differences were observed in IL-10 and gene ArgI mRNA expression or ED2 protein content (M2 macrophage markers). All the observed changes were blocked with spironolactone treatment. Macrophage depletion with liposomal clodronate reduced macrophage influx and inflammatory M1 markers (INF-γ or iNOS), whereas interstitial fibrosis was only partially reduced after this intervention, in aldosterone plus salt-treated rats. In conclusion, aldosterone + salt administration mediates inflammatory M1 macrophage phenotype and increased fibrosis throughout mineralocorticoid receptors activation. PMID:26730742

  6. Management of hyperkalaemia consequent to mineralocorticoid-receptor antagonist therapy.

    PubMed

    Roscioni, Sara S; de Zeeuw, Dick; Bakker, Stephan J L; Lambers Heerspink, Hiddo J

    2012-12-01

    Mineralocorticoid-receptor antagonists (MRAs) reduce blood pressure and albuminuria in patients treated with angiotensin-converting-enzyme inhibitors or angiotensin-II-receptor blockers. The use of MRAs, however, is limited by the occurrence of hyperkalaemia, which frequently occurs in patients older than 65 years with impaired kidney function, and/or diabetes. Patients with these characteristics might still benefit from MRA therapy, however, and should not be excluded from this treatment option. This limitation raises the question of how to optimize the therapeutic use of MRAs in this population of patients. Understanding the individual variability in patients' responses to MRAs, in terms of albuminuria, blood pressure and serum potassium levels, might lead to targeted intervention. MRA use might be restricted to patients with high levels of mineralocorticoid activity, evaluated by circulating renin and aldosterone levels or renal excretion of potassium. In addition, reviewing the patient's diet and concomitant medications might prove useful in reducing the risk of developing subsequent hyperkalaemia. If hyperkalaemia does develop, treatment options exist to decrease potassium levels, including administration of calcium gluconate, insulin, β(2)-agonists, diuretics and cation-exchange resins. In combination with novel aldosterone blockers, these strategies might offer a rationale with which to optimize therapeutic intervention and extend the population of patients who can benefit from use of MRAs.

  7. The necessity and effectiveness of mineralocorticoid receptor antagonist in the treatment of diabetic nephropathy.

    PubMed

    Sato, Atsuhisa

    2015-06-01

    Diabetes mellitus is a major cause of chronic kidney disease (CKD), and diabetic nephropathy is the most common primary disease necessitating dialysis treatment in the world including Japan. Major guidelines for treatment of hypertension in Japan, the United States and Europe recommend the use of angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, which suppress the renin-angiotensin system (RAS), as the antihypertensive drugs of first choice in patients with coexisting diabetes. However, even with the administration of RAS inhibitors, failure to achieve adequate anti-albuminuric, renoprotective effects and a reduction in cardiovascular events has also been reported. Inadequate blockade of aldosterone may be one of the reasons why long-term administration of RAS inhibitors may not be sufficiently effective in patients with diabetic nephropathy. This review focuses on treatment in diabetic nephropathy and discusses the significance of aldosterone blockade. In pre-nephropathy without overt nephropathy, a mineralocorticoid receptor antagonist can be used to enhance the blood pressure-lowering effects of RAS inhibitors, improve insulin resistance and prevent clinical progression of nephropathy. In CKD categories A2 and A3, the addition of a mineralocorticoid receptor antagonist to an RAS inhibitor can help to maintain 'long-term' antiproteinuric and anti-albuminuric effects. However, in category G3a and higher, sufficient attention must be paid to hyperkalemia. Mineralocorticoid receptor antagonists are not currently recommended as standard treatment in diabetic nephropathy. However, many studies have shown promise of better renoprotective effects if mineralocorticoid receptor antagonists are appropriately used.

  8. Rapid effects of aldosterone in primary cultures of cardiomyocytes - do they suggest the existence of a membrane-bound receptor?

    PubMed

    Araujo, Carolina Morais; Hermidorff, Milla Marques; Amancio, Gabriela de Cassia Sousa; Lemos, Denise da Silveira; Silva, Marcelo Estáquio; de Assis, Leonardo Vinícius Monteiro; Isoldi, Mauro César

    2016-10-01

    Aldosterone acts on its target tissue through a classical mechanism or through the rapid pathway through a putative membrane-bound receptor. Our goal here was to better understand the molecular and biochemical rapid mechanisms responsible for aldosterone-induced cardiomyocyte hypertrophy. We have evaluated the hypertrophic process through the levels of ANP, which was confirmed by the analysis of the superficial area of cardiomyocytes. Aldosterone increased the levels of ANP and the cellular area of the cardiomyocytes; spironolactone reduced the aldosterone-increased ANP level and cellular area of cardiomyocytes. Aldosterone or spironolactone alone did not increase the level of cyclic 3',5'-adenosine monophosphate (cAMP), but aldosterone plus spironolactone led to increased cAMP level; the treatment with aldosterone + spironolactone + BAPTA-AM reduced the levels of cAMP. These data suggest that aldosterone-induced cAMP increase is independent of mineralocorticoid receptor (MR) and dependent on Ca(2+). Next, we have evaluated the role of A-kinase anchor proteins (AKAP) in the aldosterone-induced hypertrophic response. We have found that St-Ht31 (AKAP inhibitor) reduced the increased level of ANP which was induced by aldosterone; in addition, we have found an increase on protein kinase C (PKC) and extracellular signal-regulated kinase 5 (ERK5) activity when cells were treated with aldosterone alone, spironolactone alone and with a combination of both. Our data suggest that PKC could be responsible for ERK5 aldosterone-induced phosphorylation. Our study suggests that the aldosterone through its rapid effects promotes a hypertrophic response in cardiomyocytes that is controlled by an AKAP, being dependent on ERK5 and PKC, but not on cAMP/cAMP-dependent protein kinase signaling pathways. Lastly, we provide evidence that the targeting of AKAPs could be relevant in patients with aldosterone-induced cardiac hypertrophy and heart failure.

  9. Aldosterone and the vascular system.

    PubMed

    Cachofeiro, Victoria; Miana, Maria; de Las Heras, Natalia; Martín-Fernández, Beatriz; Ballesteros, Sandra; Fernández-Tresguerres, Jesús; Lahera, Vicente

    2008-04-01

    Aldosterone can act in different tissues exerting physiological and pathological effects. At the vascular level, aldosterone affects endothelial function since administration of aldosterone impaired endothelium-dependent relaxations. In addition, the administration of mineralocorticoid receptor antagonists ameliorate relaxation to acetylcholine in models of both hypertension and atherosclerosis and in patients with heart failure. A reduction in nitric oxide levels seems to be the main mechanism underlying this effect due to a reduction in its production as well as an increase in its degradation by reactive oxygen species. Aldosterone is a pro-inflammatory factor that can participate in the vascular inflammatory process associated with different pathologies including hypertension through activation of the NFkappaB system, which mediates the vascular production of different cytokines. This mineralocorticoid also participates in the vascular remodeling observed in hypertensive rats since the administration of eplerenone improved the media-to-lumen ratio in these animals. This effect seems to be due to an increase in extracellular matrix. In summary, aldosterone through mineralocorticoid receptors can participate in the vascular damage associated with different pathologies including hypertension through its prooxidant, pro-inflammatory and profibrotic effects that triggered endothelial dysfunction, an inflammatory process and vascular remodeling.

  10. Modulation of Immunity and Inflammation by the Mineralocorticoid Receptor and Aldosterone

    PubMed Central

    Muñoz-Durango, N.; Vecchiola, A.; Gonzalez-Gomez, L. M.; Simon, F.; Riedel, C. A.; Fardella, C. E.; Kalergis, A. M.

    2015-01-01

    The mineralocorticoid receptor (MR) is a ligand dependent transcription factor. MR has been traditionally associated with the control of water and electrolyte homeostasis in order to keep blood pressure through aldosterone activation. However, there is growing evidence indicating that MR expression is not restricted to vascular and renal tissues, as it can be also expressed by cells of the immune system, where it responds to stimulation or antagonism, controlling immune cell function. On the other hand, aldosterone also has been associated with proinflammatory immune effects, such as the release of proinflammatory cytokines, generating oxidative stress and inducing fibrosis. The inflammatory participation of MR and aldosterone in the cardiovascular disease suggests an association with alterations in the immune system. Hypertensive patients show higher levels of proinflammatory mediators that can be modulated by MR antagonism. Although these proinflammatory properties have been observed in other autoimmune and chronic inflammatory diseases, the cellular and molecular mechanisms that mediate these effects remain unknown. Here we review and discuss the scientific work aimed at determining the immunological role of MR and aldosterone in humans, as well as animal models. PMID:26448944

  11. Modulation of Immunity and Inflammation by the Mineralocorticoid Receptor and Aldosterone.

    PubMed

    Muñoz-Durango, N; Vecchiola, A; Gonzalez-Gomez, L M; Simon, F; Riedel, C A; Fardella, C E; Kalergis, A M

    2015-01-01

    The mineralocorticoid receptor (MR) is a ligand dependent transcription factor. MR has been traditionally associated with the control of water and electrolyte homeostasis in order to keep blood pressure through aldosterone activation. However, there is growing evidence indicating that MR expression is not restricted to vascular and renal tissues, as it can be also expressed by cells of the immune system, where it responds to stimulation or antagonism, controlling immune cell function. On the other hand, aldosterone also has been associated with proinflammatory immune effects, such as the release of proinflammatory cytokines, generating oxidative stress and inducing fibrosis. The inflammatory participation of MR and aldosterone in the cardiovascular disease suggests an association with alterations in the immune system. Hypertensive patients show higher levels of proinflammatory mediators that can be modulated by MR antagonism. Although these proinflammatory properties have been observed in other autoimmune and chronic inflammatory diseases, the cellular and molecular mechanisms that mediate these effects remain unknown. Here we review and discuss the scientific work aimed at determining the immunological role of MR and aldosterone in humans, as well as animal models.

  12. Pharmacological analysis of calcium antagonist receptors

    SciTech Connect

    Reynolds, I.J.

    1987-01-01

    This work focuses on two aspects of the action of calcium antagonist drugs, namely, the interaction of drugs with receptors for verapamil-like calcium antagonists, and the interactions of drugs with voltage-sensitive calcium fluxes in rat brain synaptosomes. From binding studies I have found that the ligand of choice for labeling the verapamil receptor is (-)(/sup 3/H)desmethoxy-verapamil. This drug labels potently, reversibly and stereoselectively two receptors in membranes prepared from rat brain and rabbit skeletal muscle tissues. In equilibrium studies dihydropyridine calcium antagonists interact in a non-competitive fashion, while many non-DHPs are apparently competitive. In-depth kinetic studies in skeletal muscle membranes indicate that the two receptors are linked in a negative heterotropic fashion, and that low-affinity binding of (-) (/sup 3/H)desmethoxy-verapamil may be to the diltiazem receptor. However, these studies were not able to distinguish between the hypothesis that diltiazem binds to spatially separate, allosterically coupled receptors, and the hypothesis that diltiazem binds to a subsite of the verapamil receptor.

  13. Placental growth factor mediates aldosterone-dependent vascular injury in mice.

    PubMed

    Jaffe, Iris Z; Newfell, Brenna G; Aronovitz, Mark; Mohammad, Najwa N; McGraw, Adam P; Perreault, Roger E; Carmeliet, Peter; Ehsan, Afshin; Mendelsohn, Michael E

    2010-11-01

    In clinical trials, aldosterone antagonists reduce cardiovascular ischemia and mortality by unknown mechanisms. Aldosterone is a steroid hormone that signals through renal mineralocorticoid receptors (MRs) to regulate blood pressure. MRs are expressed and regulate gene transcription in human vascular cells, suggesting that aldosterone might have direct vascular effects. Using gene expression profiling, we identify the pro-proliferative VEGF family member placental growth factor (PGF) as an aldosterone-regulated vascular MR target gene in mice and humans. Aldosterone-activated vascular MR stimulated Pgf gene transcription and increased PGF protein expression and secretion in the mouse vasculature. In mouse vessels with endothelial damage and human vessels from patients with atherosclerosis, aldosterone enhanced expression of PGF and its receptor, FMS-like tyrosine kinase 1 (Flt1). In atherosclerotic human vessels, MR antagonists inhibited PGF expression. In vivo, aldosterone infusion augmented vascular remodeling in mouse carotids following wire injury, an effect that was lost in Pgf-/- mice. In summary, we have identified PGF as what we believe to be a novel downstream target of vascular MR that mediates aldosterone augmentation of vascular injury. These findings suggest a non-renal mechanism for the vascular protective effects of aldosterone antagonists in humans and support targeting the vascular aldosterone/MR/PGF/Flt1 pathway as a therapeutic strategy for ischemic cardiovascular disease.

  14. Emerging cardiovascular indications of mineralocorticoid receptor antagonists.

    PubMed

    Parviz, Yasir; Iqbal, Javaid; Pitt, Bertram; Adlam, David; Al-Mohammad, Abdallah; Zannad, Faiez

    2015-04-01

    Mineralocorticoid receptor (MR) antagonism is a well-established treatment modality for patients with hypertension, heart failure, and left ventricular systolic dysfunction (LVSD) post-myocardial infarction (MI). There are emerging data showing potential benefits of MR antagonists in other cardiovascular conditions. Studies have shown association between MR activation and the development of myocardial fibrosis, coronary artery disease, metabolic syndrome, and cerebrovascular diseases. This review examines the preclinical and clinical data of MR antagonists for novel indications including heart failure with preserved ejection fraction (HFPEF), pulmonary arterial hypertension (PAH), arrhythmia, sudden cardiac death, valvular heart disease, metabolic syndrome, renal disease, and stroke. MR antagonists are not licensed for these conditions yet; however, emerging data suggest that indication for MR antagonists are likely to broaden; further studies are warranted.

  15. G-protein-coupled receptors in aldosterone-producing adenomas: a potential cause of hyperaldosteronism.

    PubMed

    Ye, Ping; Mariniello, Barbara; Mantero, Franco; Shibata, Hirotaka; Rainey, William E

    2007-10-01

    The source of aldosterone in 30-40% of patients with primary hyperaldosteronism (PA) is unilateral aldosterone-producing adenoma (APA). The mechanisms causing elevated aldosterone production in APA are unknown. Herein, we examined the expression of G-protein-coupled receptors (GPCRs) in APA and demonstrated that when compared with normal adrenals, there is a general elevation of certain GPCR in many APA and/or ectopic expression of GPCR in others. RNA samples from normal adrenals (n = 5), APAs (n = 10), and cortisol-producing adenomas (CPAs; n = 13) were used on 15 genomic expression arrays, each of which included 223 GPCR transcripts presented in at least 1 out of 15 of the independent microarrays. The array results were confirmed using real-time RT-PCR (qPCR). Four GPCR transcripts exhibited a statistically significant increase that was greater than threefold when compared with normal adrenals, suggesting a general increase in expression when compared with normal adrenal glands. Four GPCR transcripts exhibited a > 15-fold increase of expression in one or more of the APA samples when compared with normal adrenals. qPCR analysis confirmed array data and found the receptors with the highest fold increase in APA expression to be LH receptor, serotonin receptor 4, GnRH receptor, glutamate receptor metabotropic 3, endothelin receptor type B-like protein, and ACTH receptor. There are also sporadic increased expressions of these genes in the CPAs. Together, these findings suggest a potential role of altered GPCR expression in many cases of PA and provide candidate GPCR for further study.

  16. Medicinal chemistry of competitive kainate receptor antagonists.

    PubMed

    Larsen, Ann M; Bunch, Lennart

    2011-02-16

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1-5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure-activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field.

  17. Medicinal Chemistry of Competitive Kainate Receptor Antagonists

    PubMed Central

    2010-01-01

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1−5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure−activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field. PMID:22778857

  18. NMDA Receptor Antagonists for Treatment of Depression

    PubMed Central

    Ates-Alagoz, Zeynep; Adejare, Adeboye

    2013-01-01

    Depression is a psychiatric disorder that affects millions of people worldwide. Individuals battling this disorder commonly experience high rates of relapse, persistent residual symptoms, functional impairment, and diminished well-being. Medications have important utility in stabilizing moods and daily functions of many individuals. However, only one third of patients had considerable improvement with a standard antidepressant after 2 months and all patients had to deal with numerous side effects. The N-methyl-d-aspartate (NMDA) receptor family has received special attention because of its critical role in psychiatric disorders. Direct targeting of the NMDA receptor could result in more rapid antidepressant effects. Antidepressant-like effects of NMDA receptor antagonists have been demonstrated in different animal models. MK-801 (a use-dependent channel blocker), and CGP 37849 (an NMDA receptor antagonist) have shown antidepressant properties in preclinical studies, either alone or combined with traditional antidepressants. A recent development is use of ketamine clinically for refractory depression. The purpose of this review is to examine and analyze current literature on the role of NMDA receptor antagonists for treatment of depression and whether this is a feasible route in drug discovery. PMID:24276119

  19. Genomic and rapid effects of aldosterone: what we know and do not know thus far.

    PubMed

    Hermidorff, Milla Marques; de Assis, Leonardo Vinícius Monteiro; Isoldi, Mauro César

    2017-01-01

    Aldosterone is the most known mineralocorticoid hormone synthesized by the adrenal cortex. The genomic pathway displayed by aldosterone is attributed to the mineralocorticoid receptor (MR) signaling. Even though the rapid effects displayed by aldosterone are long known, our knowledge regarding the receptor responsible for such event is still poor. It is intense that the debate whether the MR or another receptor-the "unknown receptor"-is the receptor responsible for the rapid effects of aldosterone. Recently, G protein-coupled estrogen receptor-1 (GPER-1) was elegantly shown to mediate some aldosterone-induced rapid effects in several tissues, a fact that strongly places GPER-1 as the unknown receptor. It has also been suggested that angiotensin receptor type 1 (AT1) also participates in the aldosterone-induced rapid effects. Despite this open question, the relevance of the beneficial effects of aldosterone is clear in the kidneys, colon, and CNS as aldosterone controls the important water reabsorption process; on the other hand, detrimental effects displayed by aldosterone have been reported in the cardiovascular system and in the kidneys. In this line, the MR antagonists are well-known drugs that display beneficial effects in patients with heart failure and hypertension; it has been proposed that MR antagonists could also play an important role in vascular disease, obesity, obesity-related hypertension, and metabolic syndrome. Taken altogether, our goal here was to (1) bring a historical perspective of both genomic and rapid effects of aldosterone in several tissues, and the receptors and signaling pathways involved in such processes; and (2) critically address the controversial points within the literature as regarding which receptor participates in the rapid pathway display by aldosterone.

  20. Mineralocorticoid Receptor Antagonists for Treatment of Hypertension and Heart Failure.

    PubMed

    Sica, Domenic A

    2015-01-01

    Spironolactone and eplerenone are both mineralocorticoid-receptor antagonists. These compounds block both the epithelial and nonepithelial actions of aldosterone, with the latter assuming increasing clinical relevance. Spironolactone and eplerenone both affect reductions in blood pressure either as mono- or add-on therapy; moreover, they each afford survival benefits in diverse circumstances of heart failure and the probability of renal protection in proteinuric chronic kidney disease. However, as use of mineralocorticoid-blocking agents has expanded, the hazards inherent in taking such drugs have become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove disastrous, even fatal, if sufficient degrees of hyperkalemia emerge. For most patients, however, the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered a possibility in patients receiving either of these medications; therefore, anticipatory steps should be taken to minimize the likelihood of its occurrence if long-term therapy of these agents is being considered.

  1. Aldosterone: effects on the kidney and cardiovascular system.

    PubMed

    Briet, Marie; Schiffrin, Ernesto L

    2010-05-01

    Aldosterone, a steroid hormone with mineralocorticoid activity, is mainly recognized for its action on sodium reabsorption in the distal nephron of the kidney, which is mediated by the epithelial sodium channel (ENaC). Beyond this well-known action, however, aldosterone exerts other effects on the kidney, blood vessels and the heart, which can have pathophysiological consequences, particularly in the presence of a high salt intake. Aldosterone is implicated in renal inflammatory and fibrotic processes, as well as in podocyte injury and mesangial cell proliferation. In the cardiovascular system, aldosterone has specific hypertrophic and fibrotic effects and can alter endothelial function. Several lines of evidence support the existence of crosstalk between aldosterone and angiotensin II in vascular smooth muscle cells. The deleterious effects of aldosterone on the cardiovascular system require concomitant pathophysiological conditions such as a high salt diet, increased oxidative stress, or inflammation. Large interventional trials have confirmed the benefits of adding mineralocorticoid-receptor antagonists to standard therapy, in particular to angiotensin-converting-enzyme inhibitor and angiotensin II receptor blocker therapy, in patients with heart failure. Small interventional studies in patients with chronic kidney disease have shown promising results, with a significant reduction of proteinuria associated with aldosterone antagonism, but large interventional trials that test the efficacy and safety of mineralocorticoid-receptor antagonists in chronic kidney disease are needed.

  2. Development of Kappa Opioid Receptor Antagonists

    PubMed Central

    Carroll, F. Ivy; Carlezon, William A.

    2013-01-01

    Kappa opioid receptors (KORs) belong to the G-protein coupled class of receptors (GPCRs). They are activated by the endogenous opioid peptide dynorphin (DYN) and expressed at particularly high levels within brain areas implicated in modulation of motivation, emotion, and cognitive function. Chronic activation of KORs in animal models has maladaptive effects including increases in behaviors that reflect depression, the propensity to engage in drug-seeking behavior, and drug craving. The fact that KOR activation has such a profound influence on behaviors often triggered by stress has led to interest in selective KOR antagonists as potential therapeutic agents. This perspective provides a description of preclinical research conducted in the development of several different classes of selective KOR antagonists, a summary of the clinical studies conducted thus far, and recommendations for the type of work needed in the future to determine if these agents would be useful as pharmacotherapies for neuropsychiatric illness. PMID:23360448

  3. Drug therapy of apparent treatment-resistant hypertension: focus on mineralocorticoid receptor antagonists.

    PubMed

    Glicklich, Daniel; Frishman, William H

    2015-04-01

    Apparent treatment-resistant hypertension (aTRH) is defined as blood pressure (BP) >140/90 mmHg despite three different antihypertensive drugs including a diuretic. aTRH is associated with an increased risk of cardiovascular events, including stroke, chronic renal failure, myocardial infarction, congestive heart failure, aortic aneurysm, atrial fibrillation, and sudden death. Preliminary studies of renal nerve ablation as a therapy to control aTRH were encouraging. However, these results were not confirmed by the Symplicity 3 trial. Therefore, attention has refocused on drug therapy. Secondary forms of hypertension and associated conditions such as obesity, sleep apnea, and primary aldosteronism are common in patients with aTRH. The pivotal role of aldosterone in the pathogenesis of aTRH in many cases is well recognized. For patients with aTRH, the Joint National Committee-8, the European Society of Hypertension, and a recent consensus conference recommend that a diuretic, ACE inhibitor, or angiotensin receptor blocker and calcium channel blocker combination be used to maximally tolerated doses before starting a 'fourth-line' drug such as a mineralocorticoid receptor (MR) antagonist. Although the best fourth-line drug for aTRH has not been extensively investigated, a number of studies summarized here show that an MR antagonist is effective in reducing BP when added to the standard multi-drug regimen.

  4. Investigation of orexin-2 selective receptor antagonists: Structural modifications resulting in dual orexin receptor antagonists.

    PubMed

    Skudlarek, Jason W; DiMarco, Christina N; Babaoglu, Kerim; Roecker, Anthony J; Bruno, Joseph G; Pausch, Mark A; O'Brien, Julie A; Cabalu, Tamara D; Stevens, Joanne; Brunner, Joseph; Tannenbaum, Pamela L; Wuelfing, W Peter; Garson, Susan L; Fox, Steven V; Savitz, Alan T; Harrell, Charles M; Gotter, Anthony L; Winrow, Christopher J; Renger, John J; Kuduk, Scott D; Coleman, Paul J

    2017-03-15

    In an ongoing effort to explore the use of orexin receptor antagonists for the treatment of insomnia, dual orexin receptor antagonists (DORAs) were structurally modified, resulting in compounds selective for the OX2R subtype and culminating in the discovery of 23, a highly potent, OX2R-selective molecule that exhibited a promising in vivo profile. Further structural modification led to an unexpected restoration of OX1R antagonism. Herein, these changes are discussed and a rationale for selectivity based on computational modeling is proposed.

  5. Rational discovery of novel nuclear hormone receptor antagonists

    NASA Astrophysics Data System (ADS)

    Schapira, Matthieu; Raaka, Bruce M.; Samuels, Herbert H.; Abagyan, Ruben

    2000-02-01

    Nuclear hormone receptors (NRs) are potential targets for therapeutic approaches to many clinical conditions, including cancer, diabetes, and neurological diseases. The crystal structure of the ligand binding domain of agonist-bound NRs enables the design of compounds with agonist activity. However, with the exception of the human estrogen receptor-, the lack of antagonist-bound "inactive" receptor structures hinders the rational design of receptor antagonists. In this study, we present a strategy for designing such antagonists. We constructed a model of the inactive conformation of human retinoic acid receptor- by using information derived from antagonist-bound estrogen receptor-α and applied a computer-based virtual screening algorithm to identify retinoic acid receptor antagonists. Thus, the currently available crystal structures of NRs may be used for the rational design of antagonists, which could lead to the development of novel drugs for a variety of diseases.

  6. Endothelin receptor antagonists in pulmonary arterial hypertension.

    PubMed

    Dupuis, J; Hoeper, M M

    2008-02-01

    The endothelin (ET) system, especially ET-1 and the ET(A) and ET(B) receptors, has been implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Together with prostanoids and phosphodiesterase 5 inhibitors, ET receptor antagonists have become mainstays in the current treatment of PAH. Three substances are currently available for the treatment of PAH. One of these substances, bosentan, blocks both ET(A) and ET(B) receptors, whereas the two other compounds, sitaxsentan and ambrisentan, are more selective blockers of the ET(A) receptor. There is ongoing debate as to whether selective or nonselective ET receptor blockade is advantageous in the setting of PAH, although there is no clear evidence that receptor selectivity is relevant with regard to the clinical effects of these drugs. For the time being, other features, such as safety profiles and the potential for pharmacokinetic interactions with other drugs used in the treatment of PAH, may be more important than selectivity or nonselectivity when selecting treatments for individual patients.

  7. Determinants and Changes Associated with Aldosterone Breakthrough after Angiotensin II Receptor Blockade in Patients with Type 2 Diabetes with Overt Nephropathy

    PubMed Central

    Moranne, Olivier; Bakris, George; Fafin, Coraline; Favre, Guillaume; Pradier, Christian

    2013-01-01

    Summary Background and objectives Inhibition of the renin-angiotensin-aldosterone system decreases proteinuria and slows estimated GFR decline in patients with type 2 diabetes mellitus with overt nephropathy. Serum aldosterone levels may increase during renin-angiotensin-aldosterone system blockade. The determinants and consequences of this aldosterone breakthrough remain unknown. Design, setting, participants, & measurements This study examined the incidence, determinants, and changes associated with aldosterone breakthrough in a posthoc analysis of a randomized study that compared the effect of two angiotensin II receptor blockers in patients with type 2 diabetes mellitus with overt nephropathy. Results Of 567 of 860 participants included in this posthoc analysis, 28% of participants developed aldosterone breakthrough, which was defined by an increase greater than 10% over baseline values of serum aldosterone levels after 1 year of angiotensin II receptor blocker treatment. Factors independently associated with aldosterone breakthrough at 1 year were lower serum aldosterone and potassium levels at baseline, higher decreases in sodium intake, systolic BP, and estimated GFR from baseline to 1 year, and use of losartan versus telmisartan. Aldosterone breakthrough at 6 months was not sustained at 1 year in 69% of cases, and it did not predict estimated GFR decrease and proteinuria increase between 6 months and 1 year. Conclusions Aldosterone breakthrough is a frequent event 1 year after initiating renin-angiotensin-aldosterone system blockade, particularly in participants exposed to intensive lowering of BP with sodium depletion and short-acting angiotensin II receptor blockers. Short-term serum aldosterone level increases at 6 months are not associated with negative kidney outcomes between 6 months and 1 year. PMID:23929924

  8. Efficacy and Safety of Complete RAAS Blockade with ALISKIREN in Patients with Refractory Proteinuria Who were already on Combined ACE Inhibitor, ARB, and Aldosterone Antagonist

    PubMed Central

    Sreelatha, M

    2016-01-01

    Introduction Proteinuria is always associated with intrinsic kidney disese and is a strong predictor of later development of End Stage Renal Disease (ESRD). As Renin Angiotensin Aldosterone System (RAAS) has a role in mediating proteinuria, inhibitors of this system are renoprotective and patients with refractory proteinuria are put on a combination of these agents. The routinely employed triple blockade of RAAS with Angiotensin Converting Enzyme (ACE) inhibitor, ARB and Aldosterone antagonist has many limitations. Addition of Aliskiren to this combination suppresses the RAAS at the earliest stage and can offset many of these limitations. Aim This study was conducted to assess the safety and efficacy of complete RAAS blockade by the addition of Aliskiren in those patients with refractory proteinuria who were already on triple blockade with ACE inhibitor, ARB and Aldosterone antagonist. Settings This study was conducted in Nephrology Department, Calicut Medical College. Materials and Methods A total of 36 patients with refractory proteinuria who were already on ACE inhibitor, ARB and Aldosterone antagonist were divided in to two groups A and B. Group A received Aliskiren in addition to the above combination whereas group B continued the same treatment for 12 weeks. Efficacy of the treatment was assessed by recording 24hr urine protein and safety by S.Creatinine, S.Potassium every 2 weeks of the treatment period. Statistical Analysis Statistical analysis of the lab values was done using SPSS software. Unpaired t-test, Paired t-test and Chi-square test were done for data analysis. Results Statistical analysis revealed that addition of Aliskiren to the combination therapy with ACE inhibitor+ ARB+ Aldosterone antagonist offers no advantage. But mean reduction in proteinuria was more with Group A than Group B. There is no statistically significant change in S.Creatinine and S.Potassium at the end of treatment. Conclusion As proteinuria is a strong risk factor for

  9. The PGE(2)-EP4 receptor is necessary for stimulation of the renin-angiotensin-aldosterone system in response to low dietary salt intake in vivo.

    PubMed

    Pöschke, Antje; Kern, Niklas; Maruyama, Takayuki; Pavenstädt, Hermann; Narumiya, Shuh; Jensen, Boye L; Nüsing, Rolf M

    2012-11-15

    Increased cyclooxygenase-2 (COX-2) expression and PGE(2) synthesis have been shown to be prerequisites for renal renin release after Na(+) deprivation. To answer the question of whether EP4 receptor type of PGE(2) mediates renin regulation under a low-salt diet, we examined renin regulation in EP4(+/+), EP4(-/-), and in wild-type mice treated with EP4 receptor antagonist. After 2 wk of a low-salt diet (0.02% wt/wt NaCl), EP4(+/+) mice showed diminished Na(+) excretion, unchanged K(+) excretion, and reduced Ca(2+) excretion. Diuresis and plasma electrolytes remained unchanged. EP4(-/-) exhibited a similar attenuation of Na(+) excretion; however, diuresis and K(+) excretion were enhanced, and plasma Na(+) concentration was higher, whereas plasma K(+) concentration was lower compared with control diet. There were no significant differences between EP4(+/+) and EP4(-/-) mice in blood pressure, creatinine clearance, and plasma antidiuretic hormone (ADH) concentration. Following salt restriction, plasma renin and aldosterone concentrations and kidney renin mRNA level rose significantly in EP4(+/+) but not in EP4(-/-) and in wild-type mice treated with EP4 antagonist ONO-AE3-208. In the latter two groups, the low-salt diet caused a significantly greater rise in PGE(2) excretion. Furthermore, mRNA expression for COX-2 and PGE(2) synthetic activity was significantly greater in EP4(-/-) than in EP4(+/+) mice. We conclude that low dietary salt intake induces expression of COX-2 followed by enhanced renal PGE(2) synthesis, which stimulates the renin-angiotensin-aldosterone system by activation of EP4 receptor. Most likely, defects at the step of EP4 receptor block negative feedback mechanisms on the renal COX system, leading to persistently high PGE(2) levels, diuresis, and K(+) loss.

  10. The path to an angiotensin receptor antagonist-neprilysin inhibitor in the treatment of heart failure.

    PubMed

    Braunwald, Eugene

    2015-03-17

    The PARADIGM-HF (Prospective comparison of ARNi with ACEi to Determine Impact on Global Mortality and Morbidity in Heart Failure) trial demonstrated that a new angiotensin receptor antagonist-neprilysin inhibitor was superior to an angiotensin-converting enzyme inhibitor in reducing mortality in patients with heart failure and reduced ejection fraction. This paper traces the research path that culminated in the development of this drug. The first phase, elucidation of the renin-angiotensin-aldosterone system, began with Tigerstedt's discovery of renin, followed by isolation of angiotensin, isolation of angiotensin-converting enzyme, and synthesis of its inhibitors and of angiotensin receptor blockers. Phase 2 began with de Bold's discovery of atrial natriuretic peptide, followed by isolation of the enzyme that degrades it (neprilysin) and its inhibitors. Phase 3 consists of blocking both the renin-angiotensin-aldosterone and atrial natriuretic peptide-degrading systems simultaneously. A molecular complex, LCZ696, developed by scientists at Novartis, combines an angiotensin receptor blocker with a neprilysin inhibitor, is well tolerated, and represents an important step in the management of heart failure and reduced ejection fraction.

  11. Mineralocorticoid receptor is involved in the aldosterone pathway in human red blood cells

    PubMed Central

    Bordin, Luciana; Saccardi, Carlo; Donà, Gabriella; Sabbadin, Chiara; Andrisani, Alessandra; Ambrosini, Guido; Plebani, Mario; Brunati, Anna Maria; Ragazzi, Eugenio; Gizzo, Salvatore; Armanini, Decio

    2016-01-01

    We have recently demonstrated that excessive aldosterone (Aldo) secretion in primary aldosteronism (PA) is associated with red blood cells (RBC) senescence. These alterations were prevented/inhibited by cortisol (Cort) or canrenone (Can) raising the hypothesis that Aldo effects in RBC may be mediated by mineralocorticoid receptor (MR), though to date MR has never been demonstrated in human RBC. The aim of this multicenter comparative study was to investigate whether Aldo effects were mediated by MR in these a-nucleated cells. We included 12 healthy controls (HC) and 22 patients with PA. MR presence and activation were evaluated in RBC cytosol by glycerol gradient sedimentation, Western blotting, immuno-precipitation and radioimmunoassay. We demonstrated that RBC contained cytosolic MR, aggregated with HSP90 and other proteins to form multiprotein complex. Aldo induced MR to release from the complex and to form MR dimers which were quickly proteolyzed. Cort induced MR release but not dimers formation while Can was not able to induce MR release. In addition, RBC cytosol from PA patients contained significantly higher amounts of both MR fragments (p<0.0001) and Aldo (p<0.0001) concentrations. In conclusion, in RBC a genomic-like Aldo pathway is proposed involving MR activation, dimerization and proteolysis, but lacking nuclear transcription. In addition, dimers proteolysis may ensure a sort of Aldo scavenging from circulation by entrapping Aldo in MR fragments. PMID:27158328

  12. Primary aldosteronism and pregnancy.

    PubMed

    Morton, Adam

    2015-10-01

    Primary aldosteronism is the most common cause of secondary hypertension. Less than 50 cases of pregnancy in women with primary aldosteronism have been reported, suggesting the disorder is significantly underdiagnosed in confinement. Accurate diagnosis is complicated by physiological changes in the renin-angiotensin-aldosterone axis in pregnancy, leading to a risk of false negative results on screening tests. The course of primary aldosteronism during pregnancy is highly variable, although overall it is associated with a very high risk of fetal and maternal morbidity and mortality. The optimal management of primary aldosteronism during pregnancy is unclear, with uncertainty regarding the safety of mineralocorticoid antagonists and amiloride, their relative efficacy compared with the antihypertensive medications commonly used during pregnancy, and as to whether prognosis is improved by laparoscopic adrenalectomy where an adrenal adenoma can be demonstrated.

  13. Effects of aldosterone on insulin sensitivity and secretion.

    PubMed

    Luther, James M

    2014-12-01

    Dr. Conn originally reported an increased risk of diabetes in patients with hyperaldosteronism in the 1950s, although the mechanism remains unclear. Aldosterone-induced hypokalemia was initially described to impair glucose tolerance by impairing insulin secretion. Correction of hypokalemia by potassium supplementation only partially restored insulin secretion and glucose tolerance, however. Aldosterone also impairs glucose-stimulated insulin secretion in isolated pancreatic islets via reactive oxygen species in a mineralocorticoid receptor-independent manner. Aldosterone-induced mineralocorticoid receptor activation also impairs insulin sensitivity in adipocytes and skeletal muscle. Aldosterone may produce insulin resistance secondarily by altering potassium, increasing inflammatory cytokines, and reducing beneficial adipokines such as adiponectin. Renin-angiotensin system antagonists reduce circulating aldosterone concentrations and also the risk of type 2 diabetes in clinical trials. These data suggest that primary and secondary hyperaldosteronism may contribute to worsening glucose tolerance by impairing insulin sensitivity or insulin secretion in humans. Future studies should define the effects of MR antagonists and aldosterone on insulin secretion and sensitivity in humans.

  14. Aldosterone and the cardiovascular system: a dangerous association.

    PubMed

    Cachofeiro, Victoria; López-Andrés, Natalia; Miana, Maria; Martín-Fernández, Beatriz; de Las Heras, Natalia; Martínez, Ernesto; Lahera, Vicente; Fortuño, María Antonia

    2010-12-01

    Initial studies have focussed on the actions of aldosterone in renal electrolyte handling and, as a consequence, blood pressure control. More recently, attention has primarily been focussed on its actions on the heart and vascular system, where it is locally produced. Aldosterone by binding mineralocorticoid receptors causes oxidative stress, fibrosis and triggers an inflammatory response in the cardiovascular system. All these effects could be underlying the role of aldo-sterone on cardiac and vascular remodelling associated with different pathological situations. At the vascular level, aldo-sterone affects endothelial function because administration of aldosterone to rats impaired endothelium-dependent relaxations. In addition, the administration of mineralocorticoid receptor antagonists ameliorates endothelium-dependent relaxation in models of both hypertension and atherosclerosis, and in patients with heart failure. Several mechanisms can participate in this effect, including production of vasoconstrictor factors and a reduction in nitric oxide levels. This reduction can involve both a decrease in its production as well as an increase in its degradation by reactive oxygen species. Aldosterone can produce oxidative stress by the activation of transcription factors such as the NF-κB system, which can also trigger an inflammatory process through the production of different cytokines. At cardiac level, high levels of aldosterone can also adversely impact heart function by producing cardiac hypertrophy, diastolic dysfunction and electrical remodelling through changes in ionic channels. All these effects can explain the beneficial effect of mineralocorticoid blockade in the cardiovascular system.

  15. Mineralocorticoid Receptor Antagonists in End-Stage Renal Disease: Efficacy and Safety.

    PubMed

    Bomback, Andrew S

    2016-01-01

    Mineralocorticoid receptor antagonists (MRAs) that block aldosterone's effects on both epithelial and non-epithelial receptors have become a mainstay of therapy for chronic heart failure. Given that cardiovascular events remain the leading cause of death for patients with end-stage renal disease (ESRD), the question of whether these MRAs can be employed in dialysis patients arises. This review summarizes the rationale for blocking aldosterone in patients with chronic and end-stage kidney disease and surveys the data on both the efficacy and safety of using MRAs in the ESRD population. A small but growing body of literature suggests that use of MRAs by ESRD patients is associated with lower blood pressure, reduced left ventricular (LV) mass, and improved LV ejection fraction. Recently, a large randomized trial found an overall 3-year mortality rate of 6.4% in ESRD patients on spironolactone 25 mg daily vs. 19.7% in ESRD patients on no MRA therapy (p = 0.002), without a significantly increased risk of hyperkalemia.

  16. An update on non-peptide angiotensin receptor antagonists and related RAAS modulators.

    PubMed

    Aulakh, G K; Sodhi, R K; Singh, M

    2007-08-02

    The renin-angiotensin-aldosterone-system (RAAS) is an important regulator of blood pressure and fluid-electrolyte homeostasis. RAAS has been implicated in pathogenesis of hypertension, congestive heart failure, and chronic renal failure. Aliskiren is the first non-peptide orally active renin inhibitor approved by FDA. Angiotensin Converting Enzyme (ACE) Inhibitors are associated with frequent side effects such as cough and angio-oedema. Recently, the role of ACE2 and neutral endopeptidase (NEP) in the formation of an important active metabolite/mediator of RAAS, ang 1-7, has initiated attempts towards development of ACE2 inhibitors and combined ACE/NEP inhibitors. Furukawa and colleagues developed a series of low molecular weight nonpeptide imidazole analogues that possess weak but selective, competitive AT1 receptor blocking property. Till date, many compounds have exhibited promising AT1 blocking activity which cause a more complete RAAS blockade than ACE inhibitors. Many have reached the market for alternative treatment of hypertension, heart failure and diabetic nephropathy in ACE inhibitor intolerant patients and still more are waiting in the queue. But, the hallmark of this area of drug research is marked by a progress in understanding molecular interaction of these blockers at the AT1 receptor and unraveling the enigmatic influence of AT2 receptors on growth/anti-growth, differentiation and the regeneration of neuronal tissue. Different modeling strategies are underway to develop tailor made molecules with the best of properties like Dual Action (Angiotensin And Endothelin) Receptor Antagonists (DARA), ACE/NEP inhibitors, triple inhibitors, AT2 agonists, AT1/TxA2 antagonists, balanced AT1/AT2 antagonists, and nonpeptide renin inhibitors. This abstract gives an overview of these various angiotensin receptor antagonists.

  17. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists

    PubMed Central

    Khanfar, Mohammad A.; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures. PMID:27303254

  18. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists.

    PubMed

    Khanfar, Mohammad A; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures.

  19. The role of angiotensin II type 1 receptor antagonists in elderly patients with hypertension.

    PubMed

    Thomas, G Neil; Chan, Paul; Tomlinson, Brian

    2006-01-01

    Hypertension is a major risk factor for stroke and coronary events in elderly people and clinical trials have shown that treatment of hypertension with various drugs can result in a substantial reduction in cerebrovascular and cardiovascular events. The angiotensin II type 1 (AT1) receptor antagonists are the newest class of antihypertensive agents to be used widely in clinical practice. AT1 receptor antagonists can generally be given once-daily. They are also extremely well tolerated with minimal first-dose hypotension and an incidence of adverse effects similar to that seen with placebo. Adverse event rates are significantly lower than with other classes of antihypertensive drugs including ACE inhibitors. These factors result in improved compliance and increased rates of continuance on therapy. AT1 receptor antagonists show similar efficacy in lowering blood pressure to other classes of antihypertensive agents and their antihypertensive effect is potentiated when they are given concomitantly with low-dose thiazide diuretics. AT1 receptor antagonists are eliminated predominantly by the hepatic route but most are not subject to extensive metabolism and interactions with other drugs are uncommon. This is an advantage in the elderly, who are often receiving multiple medications which increases the risk for adverse drug interactions. Dose adjustments are not usually required in the elderly unless there is plasma volume depletion. Although plasma AT1 receptor antagonist concentrations are generally higher in the elderly than in younger subjects, this pharmacokinetic difference may be balanced by decreased activation of the circulating renin-angiotensin-aldosterone system in the elderly. Recent clinical studies in high-risk hypertensive patients with left ventricular hypertrophy or in patients with diabetic nephropathy or heart failure have demonstrated that AT1 receptor antagonists can improve clinical outcomes to a similar or sometimes greater extent than other

  20. Discovery of Novel Triazole-Based Opioid Receptor Antagonists

    PubMed Central

    Zhang, Qiang; Keenan, Susan M.; Peng, Youyi; Nair, Anil C.; Yu, Seong Jae; Howells, Richard D.; Welsh, William J.

    2009-01-01

    We report the computer-aided design, chemical synthesis, and biological evaluation of a novel family of δ opioid receptor (DOR) antagonists containing a 1,2,4-triazole core structure that are structurally distinct from other known opioid receptor active ligands. Among those δ antagonists sharing this core structure, 8 exhibited strong binding affinity (Ki = 50 nM) for the DOR and appreciable selectivity for δ over μ and opioid receptors (δ/μ = 80; δ/κ > 200). PMID:16821764

  1. Aldosterone and volume management in hypertensive heart disease.

    PubMed

    Sica, Domenic A

    2014-05-01

    Aldosterone-receptor antagonists dose-dependently reduce both the epithelial and nonepithelial actions of aldosterone. These compounds are used commonly in the treatment of hypertension, with or without aldosteronism, and in the volume-overload periods of various forms of heart failure, cirrhosis, and renal failure. In this regard, the relevant site of action for these compounds is compartmentalized to the distal nephron. The cardiac benefits of aldosterone-receptor blockade now are sufficiently well established to warrant routine use of these compounds for their survival benefits in moderate to advanced stages of heart failure. Aldosterone-receptor antagonists spironolactone and eplerenone commonly are used in the treatment of resistant forms of hypertension. Spironolactone, but not eplerenone, is a commonly used add-on diuretic that provides incremental benefit for salt-and-water excretion in excess of what may be seen with a loop diuretic given together with a thiazide-type diuretic. The dose-response relationship for natriuresis with spironolactone has not been explored completely as to its combination therapy responses. The quite high doses of spironolactone used in patients with cirrhosis and ascites would infer that the overall treatment effect with this compound exceeds simple receptor blockade and may include a nervous system effect that operationally reduces renal sympathetic nerve traffic. The adverse electrolyte and renal function side effects with aldosterone-receptor antagonists are not uncommon in at-risk patients, such as those with chronic kidney disease, and require that dosing be mindful of the tendency of these drugs to importantly increase serum potassium levels.

  2. Aldosterone-reversible decrease in the density of renal peripheral benzodiazepine receptors in the rat after adrenalectomy

    SciTech Connect

    Basile, A.S.; Ostrowski, N.L.; Skolnick, P.

    1987-03-01

    A statistically significant decrease in the density of peripheral benzodiazepine receptors was observed in renal membranes of rats beginning 2 weeks after adrenalectomy when compared with sham-operated controls. This decrease in peripheral benzodiazepine receptor density was manifest as a decrease in the maximum binding of two ligands, (/sup 3/H)Ro 5-4864 and (/sup 3/H)PK 11195, without accompanying changes in their Kd for this site. Similar changes were not seen in another aldosterone-sensitive organ, the submandibular salivary gland. The decrease in peripheral benzodiazepine receptor density observed in adrenalectomized rat renal membranes was restored to control levels after 1 week of aldosterone administration using a dose (12.5 micrograms/kg/day) that had no effect on peripheral benzodiazepine receptor density in sham-operated animals. In contrast, dexamethasone administration (50 micrograms/kg/day, 1 week) had no effect on renal peripheral benzodiazepine receptor density when administered to either adrenalectomized or sham-operated rats. Further, adrenal demedullation had no effect on renal peripheral benzodiazepine receptor density or affinity. The decrease in peripheral benzodiazepine receptor density was localized to the renal cortex and the outer stripe of the medulla by gross dissection of renal slices and renal tissue section autoradiography. The specific effect of adrenalectomy on renal peripheral benzodiazepine receptor density, the lack of direct effect of aldosterone on (/sup 3/H) Ro 5-4864 binding and the localization of the change in peripheral benzodiazepine receptor density to the renal cortex and outer stripe suggest that these changes may reflect an adaptation of the renal nephron (possibly the distal convoluted tubule, intermediate tubule and/or the collecting duct) to the loss of mineralocorticoid hormones.

  3. Prostanoid receptor antagonists: development strategies and therapeutic applications

    PubMed Central

    Jones, RL; Giembycz, MA; Woodward, DF

    2009-01-01

    Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP1, EP2 …) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP1, TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP2). While some antagonists are structurally related to the natural agonist, most recent compounds are ‘non-prostanoid’ (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD2 (acting on DP1 and DP2 receptors) and PGE2 (on EP1 and EP4 receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage. PMID:19624532

  4. CXCR2 receptor antagonists: a medicinal chemistry perspective.

    PubMed

    Dwyer, Michael P; Yu, Younong

    2014-01-01

    Dysregulated leukocyte recruitment is believed to be a key contributor to various acute and chronic inflammatory disorders which can lead to serious pathological consequences. Chemokines are small molecular weight proteins that have been shown to be imperative in the direction of leukocytes to the sites of inflammation. In humans, several of these chemokines (CXCL8 and CXCL1) are elevated in inflammatory disorders such as asthma, arthritis, and chronic obstructive pulmonary disease (COPD). These chemokines modulate their downstream effects thru G-protein coupled receptors, such as CXCR2, making the identification of small-molecule antagonists of this receptor attractive towards developing novel therapies to treat inflammatory conditions. Since the first report of a CXCR2 receptor antagonist in 1998, there has been a considerable effort conducted mainly in the pharmaceutical industry to identify novel classes of CXCR2 receptor antagonists. Over a dozen distinct classes of CXCR2 receptor antagonists have been reported in the literature to date with a number of these compounds having reached mid-stage clinical trials. This review will provide a broad overview the medicinal chemistry efforts over the past 15 years towards the identification of CXCR2 receptor antagonists. The discussion will focus upon the early preclinical space covering the structure activity relationships (SAR), pharmacology, as well in preclinical in vivo evaluation for the different series of CXCR2 receptor antagonists. In addition, the available clinical data for the most advanced compounds in the clinic will be discussed and along with a perspective of the area moving forward.

  5. Vasopressin-receptor antagonist therapy in patients with hyponatraemia.

    PubMed

    Vachharajani, Tushar; Vachharajani, Vidula

    2007-07-01

    Hyponatraemia often complicates the treatment of underlying conditions in patients who are seriously ill. Arginine vasopressin receptor antagonists block the action of arginine vasopressin and correct sodium and water imbalance in patients with euvolaemic or hypervolaemic hyponatraemia.

  6. [Angiotensin II receptor antagonists: different or equivalent?].

    PubMed

    Mounier-Vehier, C; Devos, P

    ARA-II: Angiotensin II receptor antagonists (ARA-II) belong to a recent class of antihypertensive drugs whose mechanism of action is similar to converting enzyme inhibitors (CEI). ARA-II are particularly interesting due to the excellent clinical and biological tolerance, similar to placebo, and their antihypertensive efficacy, comparable with classical drug classes. PUBLISHED TRIALS: A meta-analysis, published by Conlin in the American Journal of Hypertension, suggests that ARA-II, specifically losartan, valsartan, irbesartan and candesartan, have an equipotent blood pressure lowering effect. The careful lecture of this meta-analysis however discloses a faulty methodology from which no valid conclusion can be drawn. Since this early publication, several other comparative studies have been published. These multicentric, randomized double-blind studies enrolled a sufficient number of patients and demonstrated a clinical difference between certain ARA-II at usual dosages. CLINICAL PRACTICE: These studies do have an impact on everyday practice. For the practitioner, the goal is to obtain and then maintain a long-term and optimal reduction in the blood pressure level (reduction or prevention of target-organ disorders and cardiovascular complications of high blood pressure). This reduction in the cardiovascular risk will also depend directly on tolerance and compliance to the antihypertensive treatment. This element must also be considered in assessing treatment efficacy, independent of the blood pressure lowering effect. The results of several other studies will be published in 2001-2003. These large-scale studies on ARA-II related morbidity and mortality will be most useful in determining the role of these drugs in different therapeutic strategies compared with other drug classes.

  7. Moderate inappropriately high aldosterone/NaCl constellation in mice: cardiovascular effects and the role of cardiovascular epidermal growth factor receptor.

    PubMed

    Schreier, Barbara; Rabe, Sindy; Winter, Sabrina; Ruhs, Stefanie; Mildenberger, Sigrid; Schneider, Bettina; Sibilia, Maria; Gotthardt, Michael; Kempe, Sabine; Mäder, Karsten; Grossmann, Claudia; Gekle, Michael

    2014-12-11

    Non-physiological activation of the mineralocorticoid receptor (MR), e.g. by aldosterone under conditions of high salt intake, contributes to the pathogenesis of cardiovascular diseases, although beneficial effects of aldosterone also have been described. The epidermal growth factor receptor (EGFR) contributes to cardiovascular alterations and mediates part of the MR effects. Recently, we showed that EGFR is required for physiological homeostasis and function of heart and arteries in adult animals. We hypothesize that moderate high aldosterone/NaCl, at normal blood pressure, affects the cardiovascular system depending on cardiovascular EGFR. Therefore we performed an experimental series in male and female animals each, using a recently established mouse model with EGFR knockout in vascular smooth muscle cells and cardiomyocytes and determined the effects of a mild-high aldosterone-to-NaCl constellation on a.o. marker gene expression, heart size, systolic blood pressure, impulse conduction and heart rate. Our data show that (i) cardiac tissue of male but not of female mice is sensitive to mild aldosterone/NaCl treatment, (ii) EGFR knockout induces stronger cardiac disturbances in male as compared to female animals and (iii) mild aldosterone/NaCl treatment requires the EGFR in order to disturb cardiac tissue homeostasis whereas beneficial effects of aldosterone seem to be independent of EGFR.

  8. Antagonists of the kappa opioid receptor.

    PubMed

    Urbano, Mariangela; Guerrero, Miguel; Rosen, Hugh; Roberts, Edward

    2014-05-01

    The research community has increasingly focused on the development of OPRK antagonists as pharmacotherapies for the treatment of depression, anxiety, addictive disorders and other psychiatric conditions produced or exacerbated by stress. Short-acting OPRK antagonists have been recently developed as a potential improvement over long-acting prototypic ligands including nor-BNI and JDTic. Remarkably the short-acting LY2456302 is undergoing phase II clinical trials for the augmentation of the antidepressant therapy in treatment-resistant depression. This Letter reviews relevant chemical and pharmacological advances in the identification and development of OPRK antagonists.

  9. Primary Aldosteronism

    MedlinePlus

    ... Endocrinology Find an Endocrinologist Value of an Endocrinologist Learn About Clinical Trials Keep Your Body in Balance › Primary Aldosteronism Fact Sheet Primary Aldosteronism March 2012 Download PDFs English Espanol Editors Paul Stewart, MD, FRCP William Young, ...

  10. Solution structures and molecular interactions of selective melanocortin receptor antagonists.

    PubMed

    Lee, Chul-Jin; Yun, Ji-Hye; Lim, Sung-Kil; Lee, Weontae

    2010-12-01

    The solution structures and inter-molecular interaction of the cyclic melanocortin antagonists SHU9119, JKC363, HS014, and HS024 with receptor molecules have been determined by NMR spectroscopy and molecular modeling. While SHU9119 is known as a nonselective antagonist, JKC363, HS014, and HS024 are selective for the melanocortin subtype-4 receptor (MC4R) involved in modulation of food intake. Data from NMR and molecular dynamics suggest that the conformation of the Trp9 sidechain in the three MC4R-selective antagonists is quite different from that of SHU9119. This result strongly supports the concept that the spatial orientation of the hydrophobic aromatic residue is more important for determining selectivity than the presence of a basic, "arginine-like" moiety responsible for biological activity. We propose that the conformation of hydrophobic residues of MCR antagonists is critical for receptor-specific selectivity.

  11. Aldosterone induces rapid sodium intake by a nongenomic mechanism in the nucleus tractus solitarius

    PubMed Central

    Qiao, Hu; Hu, Bo; Zhou, Hong; Yan, Jianqun; Jia, Ru; Lu, Bo; Sun, Bo; Luo, Xiao; Fan, Yuanyuan; Wang, Nan

    2016-01-01

    The purpose of this study was to determine whether aldosterone has a rapid action in the nucleus tractus solitarius (NTS) that increases sodium intake, and to examine whether this effect of aldosterone, if present, is mediated by G protein-coupled estrogen receptor (GPER). Adult male Sprague-Dawley rats with a stainless-steel cannula in the NTS were used. Aldosterone was injected into the NTS at the doses of 1, 5, 10 and 20 ng 0.1 μl−1. A rapid dose-related increase of 0.3 M NaCl intake was induced within 30 min and this increase was not suppressed by the mineralocorticoid receptor (MR) antagonist spironolactone (10 ng 0.1 μl−1). Water intake was not affected by aldosterone. The GPER agonist G-1 produced a parallel and significant increase in sodium intake, while pre-treatment with GPER antagonist G15 (10 ng 0.1 μl−1) blocked the G-1 or aldosterone-induced rapid sodium intake. In addition, sodium intake induced by sodium depletion or low-sodium diet fell within 30 min after injection into the NTS of the MR antagonist spironolactone, while G15 had no effect. Our results confirm previous reports, and support the hypothesis that aldosterone evokes rapid sodium intake through a non-genomic mechanism involving GPER in NTS. PMID:27934887

  12. Pharmacophore development for antagonists at α1 adrenergic receptor subtypes

    NASA Astrophysics Data System (ADS)

    Bremner, J. B.; Coban, B.; Griffith, R.

    1996-12-01

    Many receptors, including α1 adrenergic receptors, have a range of subtypes. This offers possibilities for the development of highly selective antagonists with potentially fewer detrimental effects. Antagonists developed for α1A receptors, for example, would have potential in the treatment of benign prostatic hyperplasia. As part of the molecular design process, structural features necessary for the selective affinity for α1A and α1B adrenergic receptors have been investigated. The molecular modelling software (particularly the Apex module) of Molecular Simulations, Inc. was used to develop pharmacophore models for these two subtypes. Low-energy conformations of a set of known antagonists were used as input, together with a classification of the receptor affinity data. The biophores proposed by the program were evaluated and pharmacophores were proposed. The pharmacophore models were validated by testing the fit of known antagonists, not included in the training set. The critical structural feature for selectivity between the α1A and α1B adrenergic receptor sites is the distance between the basic nitrogen atom and the centre of an aromatic ring system. This will be exploited in the design and synthesis of structurally new selective antagonists for these sites.

  13. Histone deacetylase inhibition, but not a mineralocorticoid receptor antagonist spironolactone, attenuates atypical transcription by an activating mutant MR (MRS 810L ).

    PubMed

    Kang, Seol-Hee; Lee, Hae-Ahm; Lee, Eunjo; Kim, Mina; Kim, Inkyeom

    2016-10-01

    A mutation in the mineralocorticoid receptor (MRS 810L ) leads to early-onset hypertension, which is markedly exacerbated during pregnancy. The mutation causes progesterone and even the MR antagonist spironolactone to become potent agonists. Thus, it is hard to control hypertension in patients harbouring this mutation. We hypothesized that histone deacetylase inhibition (HDACi), but not the MR antagonist spironolactone, attenuates atypical transcriptional activity of activating mutant MR (MRS 810L ). We established HEK293T cells overexpressing wild-type MR (MRWT ) or MRS 810L and determined their transcriptional activities by luciferase assay. Expression of MR target genes was measured by quantitative real-time PCR (qRT-PCR). Treatment with aldosterone increased the expression of MR target genes as well as the transcriptional activities in HEK293T cells transfected either with MRWT or MRS 810L . Treatment with either spironolactone or progesterone also increased the expression of MR target genes as well as transcriptional activity, but only in HEK293T cells transfected with MRS 810L . Spironolactone abolished the promoter activity stimulated by aldosterone in HEK293T cells transfected with MRWT . Treatment with HDAC inhibitors attenuated the transcriptional activity as well as the expression of MR target genes induced by aldosterone, spironolactone, or progesterone whether HEK293T cells were transfected with either MRWT or MRS 810L . These results indicate that HDACi, but not an MR antagonist spironolactone, attenuates atypical transcriptional activity of an activating mutant MR (MRS 810L ).

  14. Aldosterone induces fibrosis, oxidative stress and DNA damage in livers of male rats independent of blood pressure changes

    SciTech Connect

    Queisser, Nina; Happ, Kathrin; Link, Samuel; Jahn, Daniel; Zimnol, Anna; Geier, Andreas; Schupp, Nicole

    2014-11-01

    Mineralocorticoid receptor blockers show antifibrotic potential in hepatic fibrosis. The mechanism of this protective effect is not known yet, although reactive oxygen species seem to play an important role. Here, we investigated the effects of elevated levels of aldosterone (Ald), the primary ligand of the mineralocorticoid receptor, on livers of rats in a hyperaldosteronism model: aldosterone-induced hypertension. Male Sprague–Dawley rats were treated for 4 weeks with aldosterone. To distinguish if damage caused in the liver depended on increased blood pressure or on increased Ald levels, the mineralocorticoid receptor antagonist spironolactone was given in a subtherapeutic dose, not normalizing blood pressure. To investigate the impact of oxidative stress, the antioxidant tempol was administered. Aldosterone induced fibrosis, detected histopathologically, and by expression analysis of the fibrosis marker, α-smooth muscle actin. Further, the mRNA amount of the profibrotic cytokine TGF-β was increased significantly. Fibrosis could be reduced by scavenging reactive oxygen species, and also by blocking the mineralocorticoid receptor. Furthermore, aldosterone treatment caused oxidative stress and DNA double strand breaks in livers, as well as the elevation of DNA repair activity. An increase of the transcription factor Nrf2, the main regulator of the antioxidative response could be observed, and of its target genes heme oxygenase-1 and γ-glutamylcysteine synthetase. All these effects of aldosterone were prevented by spironolactone and tempol. Already after 4 weeks of treatment, aldosteroneinfusion induced fibrosis in the liver. This effect was independent of elevated blood pressure. DNA damage caused by aldosterone might contribute to fibrosis progression when aldosterone is chronically increased. - Highlights: • Aldosterone has direct profibrotic effects on the liver independent of blood pressure. • Fibrosis is mediated by the mineralocorticoid receptor and

  15. Non-NMDA receptor antagonist-induced drinking in rat

    NASA Technical Reports Server (NTRS)

    Xu, Z.; Johnson, A. K.

    1998-01-01

    Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

  16. Oxidative DNA Damage in Kidneys and Heart of Hypertensive Mice Is Prevented by Blocking Angiotensin II and Aldosterone Receptors

    PubMed Central

    Brand, Susanne; Amann, Kerstin; Mandel, Philipp; Zimnol, Anna; Schupp, Nicole

    2014-01-01

    Introduction Recently, we could show that angiotensin II, the reactive peptide of the blood pressure-regulating renin-angiotensin-aldosterone-system, causes the formation of reactive oxygen species and DNA damage in kidneys and hearts of hypertensive mice. To further investigate on the one hand the mechanism of DNA damage caused by angiotensin II, and on the other hand possible intervention strategies against end-organ damage, the effects of substances interfering with the renin-angiotensin-aldosterone-system on angiotensin II-induced genomic damage were studied. Methods In C57BL/6-mice, hypertension was induced by infusion of 600 ng/kg • min angiotensin II. The animals were additionally treated with the angiotensin II type 1 receptor blocker candesartan, the mineralocorticoid receptor blocker eplerenone and the antioxidant tempol. DNA damage and the activation of transcription factors were studied by immunohistochemistry and protein expression analysis. Results Administration of angiotensin II led to a significant increase of blood pressure, decreased only by candesartan. In kidneys and hearts of angiotensin II-treated animals, significant oxidative stress could be detected (1.5-fold over control). The redox-sensitive transcription factors Nrf2 and NF-κB were activated in the kidney by angiotensin II-treatment (4- and 3-fold over control, respectively) and reduced by all interventions. In kidneys and hearts an increase of DNA damage (3- and 2-fold over control, respectively) and of DNA repair (3-fold over control) was found. These effects were ameliorated by all interventions in both organs. Consistently, candesartan and tempol were more effective than eplerenone. Conclusion Angiotensin II-induced DNA damage is caused by angiotensin II type 1 receptor-mediated formation of oxidative stress in vivo. The angiotensin II-mediated physiological increase of aldosterone adds to the DNA-damaging effects. Blocking angiotensin II and mineralocorticoid receptors therefore

  17. Plasma soluble (pro)renin receptor is independent of plasma renin, prorenin, and aldosterone concentrations but is affected by ethnicity.

    PubMed

    Nguyen, Geneviève; Blanchard, Anne; Curis, Emmanuel; Bergerot, Damien; Chambon, Yann; Hirose, Takuo; Caumont-Prim, Aurore; Tabard, Sylvie Brailly; Baron, Stéphanie; Frank, Michael; Totsune, Kazuhito; Azizi, Michel

    2014-02-01

    A soluble (pro)renin receptor (sPRR) circulates in plasma and is able to bind renin and prorenin. It is not known whether plasma sPRR concentrations vary with the activity of the renin-angiotensin system. We measured plasma sPRR, renin, prorenin, and aldosterone concentrations in 121 white and 9 black healthy subjects, 40 patients with diabetes mellitus, 41 hypertensive patients with or without renin-angiotensin system blockers, 9 patients with primary aldosteronism, and 10 patients with Gitelman syndrome. Median physiological plasma sPRR concentration was 23.5 ng/mL (interquartile range, 20.9-26.5) under usual uncontrolled sodium diet. sPRR concentration in healthy subjects, unlike renin and prorenin, did not display circadian variation or dependence on age, sex, posture, or hormonal status. sPRR concentrations were ≈25% lower in black than in white subjects, whereas renin concentrations were ≈40% lower. Patients with diabetes mellitus (average renin-high prorenin levels) and with hypertension only (average renin-average prorenin levels) had sPRR concentrations similar to healthy subjects. Renin-angiotensin system blockade was associated with increase of sPRR concentration by ≈12%. sPRR in patients with primary aldosteronism (low renin-low prorenin) and Gitelman syndrome (high renin-high prorenin) were similar and ≈10% higher than in healthy subjects. There was no correlation between sPRR and renin or prorenin. In conclusion, our results show that plasma sPRR concentrations are dependent on ethnicity and independent of renin, prorenin, and aldosterone concentrations in healthy subjects and in patients with contrasted degrees of renin-angiotensin system activity.

  18. Thermodynamic analysis of antagonist and agonist interactions with dopamine receptors.

    PubMed

    Duarte, E P; Oliveira, C R; Carvalho, A P

    1988-03-01

    The binding of [3H]spiperone to dopamine D-2 receptors and its inhibition by antagonists and agonists were examined in microsomes derived from the sheep caudate nucleus, at temperatures between 37 and 1 degree C, and the thermodynamic parameters of the binding were evaluated. The affinity of the receptor for the antagonists, spiperone and (+)-butaclamol, decreased as the incubation temperature decreased; the affinity for haloperidol did not further decrease at temperatures below 15 degrees C. The binding of the antagonists was associated with very large increases in entropy, as expected for hydrophobic interactions. The enthalpy and entropy changes associated with haloperidol binding were dependent on temperature, in contrast to those associated with spiperone and (+)-butaclamol. The magnitude of the entropy increase associated with the specific binding of the antagonists did not correlate with the degree of lipophilicity of these drugs. The data suggest that, in addition to hydrophobic forces, other forces are also involved in the antagonist-dopamine receptor interactions, and that a conformational change of the receptor could occur when the antagonist binds. Agonist binding data are consistent with a two-state model of the receptor, a high-affinity state (RH) and a low-affinity state (RL). The affinity of dopamine binding to the RH decreased with decreasing temperatures below 20 degrees C, whereas the affinity for the RL increased at low temperatures. In contrast, the affinity of apomorphine for both states of receptor decreased as the temperature decreased from 30 to 8 degrees C. A clear distinction between the energetics of high-affinity and low-affinity agonist binding was observed. The formation of the high-affinity complex was associated with larger increases in enthalpy and entropy than the interaction with the low-affinity state was. The results suggest that the interaction of the receptor with the G-proteins, induced or stabilized by the binding of

  19. Mixed antagonistic effects of bilobalide at rho1 GABAC receptor.

    PubMed

    Huang, S H; Duke, R K; Chebib, M; Sasaki, K; Wada, K; Johnston, G A R

    2006-01-01

    Bilobalide was found to be a moderately potent antagonist with a weak use-dependent effect at recombinant human rho(1) GABA(C) receptors expressed in Xenopus oocytes using two-electrode voltage clamp methodology. Antagonism of bilobalide at homomeric rho(1) GABA(C) receptors appeared to be mixed. At low concentration, bilobalide (3 microM) caused a parallel right shift and surmountable GABA maximal response of the GABA dose-response curve characteristic of a competitive antagonist. At high concentrations, bilobalide (10-100 microM) caused nonparallel right shifts and reduced maximal GABA responses of GABA dose-response curves characteristic of a noncompetitive antagonist. The potency of bilobalide appears to be dependent on the concentrations of GABA and was more potent at lower GABA concentrations. The mechanism of action of bilobalide at rho(1) GABA(C) receptors appears to be similar to that of the chloride channel blocker picrotoxinin.

  20. Aldosterone Inactivates the Endothelin-B Receptor via a Cysteinyl Thiol Redox Switch to Decrease Pulmonary Endothelial Nitric Oxide Levels and Modulate Pulmonary Arterial Hypertension

    PubMed Central

    Maron, Bradley A.; Zhang, Ying-Yi; White, Kevin; Chan, Stephen Y.; Handy, Diane E.; Mahoney, Christopher E.; Loscalzo, Joseph; Leopold, Jane A.

    2012-01-01

    Background Pulmonary arterial hypertension (PAH) is characterized, in part, by decreased endothelial nitric oxide (NO•) production and elevated levels of endothelin-1. Endothelin-1 is known to stimulate endothelial nitric oxide synthase (eNOS) via the endothelin-B receptor (ETB), suggesting that this signaling pathway is perturbed in PAH. Endothelin-1 also stimulates adrenal aldosterone synthesis; in systemic blood vessels, hyperaldosteronism induces vascular dysfunction by increasing endothelial reactive oxygen species (ROS) generation and decreasing NO• levels. We hypothesized that aldosterone modulates PAH by disrupting ETB-eNOS signaling through a mechanism involving increased pulmonary endothelial oxidant stress. Methods and Results In rats with PAH, elevated endothelin-1 levels were associated with elevated aldosterone levels in plasma and lung tissue and decreased lung NO• metabolites in the absence of left heart failure. In human pulmonary artery endothelial cells (HPAECs), endothelin-1 increased aldosterone levels via PGC-1α/steroidogenesis factor-1-dependent upregulation of aldosterone synthase. Aldosterone also increased ROS production, which oxidatively modified cysteinyl thiols in the eNOS-activating region of ETB to decrease endothelin-1-stimulated eNOS activity. Substitution of ETB-Cys405 with alanine improved ETB-dependent NO• synthesis under conditions of oxidant stress, confirming that Cys405 is a redox sensitive thiol that is necessary for ETB-eNOS signaling. In HPAECs, mineralocorticoid receptor antagonism with spironolactone decreased aldosterone-mediated ROS generation and restored ETB-dependent NO• production. Spironolactone or eplerenone prevented or reversed pulmonary vascular remodeling and improved cardiopulmonary hemodynamics in two animal models of PAH in vivo. Conclusions Our findings demonstrate that aldosterone modulates an ETB cysteinyl thiol redox switch to decrease pulmonary endothelium-derived NO• and promote PAH

  1. Discovery of Tertiary Sulfonamides as Potent Liver X Receptor Antagonists

    SciTech Connect

    Zuercher, William J.; Buckholz†, Richard G.; Campobasso, Nino; Collins, Jon L.; Galardi, Cristin M.; Gampe, Robert T.; Hyatt, Stephen M.; Merrihew, Susan L.; Moore, John T.; Oplinger, Jeffrey A.; Reid, Paul R.; Spearing, Paul K.; Stanley, Thomas B.; Stewart, Eugene L.; Willson, Timothy M.

    2010-08-12

    Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

  2. Antiadipogenic effects of the mineralocorticoid receptor antagonist drospirenone: potential implications for the treatment of metabolic syndrome.

    PubMed

    Caprio, Massimiliano; Antelmi, Antonella; Chetrite, Gérard; Muscat, Adeline; Mammi, Caterina; Marzolla, Vincenzo; Fabbri, Andrea; Zennaro, Maria-Christina; Fève, Bruno

    2011-01-01

    The mineralocorticoid receptor (MR) mediates aldosterone- and glucocorticoid-induced adipocyte differentiation. Drospirenone (DRSP) is a potent synthetic antimineralocorticoid with progestogenic and antiandrogenic properties, which is widely used for contraception and hormone replacement therapy. We investigated its potential role on adipocyte differentiation. The effects of DRSP were studied in murine preadipocyte cell lines and primary cultures of human preadipocytes. Differentiation markers and mechanisms underlying phenotypic variations in response to DRSP were explored. Early exposure to DRSP during differentiation led to a marked dose-dependent inhibition of adipose differentiation and triglyceride accumulation in 3T3-L1 and 3T3-F442A cells. DRSP also markedly inhibited adipose conversion of human primary preadipocytes derived from visceral (mesenteric and epicardial) and subcutaneous fat. This effect was MR-dependent and did not involve the glucocorticoid, androgen, or progesterone receptors. DRSP inhibited clonal expansion of preadipocytes and decreased expression of PPARγ, a key transcriptional mediator of adipogenesis, but had no effect on lipolysis, glucose uptake, and PPARγ binding to its ligands. DRSP exerts a potent antiadipogenic effect that is related to an alteration of the transcriptional control of adipogenesis via an antagonistic effect on the MR. Selective MR blockade therefore has promise as a novel therapeutic option for the control of excessive adipose tissue deposition and its related metabolic complications.

  3. Endothelin receptor antagonists and cardiovascular diseases of aging.

    PubMed

    Love, M P; McMurray, J J

    2001-01-01

    Our understanding of the role of the endothelin system in human cardiovascular physiology and pathophysiology has evolved very rapidly since the initial description of its constituent parts in 1988. Endothelin-1 (ET-1) is the predominant endothelin isoform in the human cardiovascular system and has potent vasoconstrictor, mitogenic and antinatriuretic properties which have implicated it in the pathophysiology of a number of cardiovascular diseases. The effects of ET-1 have been shown to be mediated by 2 principal endothelin receptor subtypes: ET(A) and ET(B). The development of a range of peptidic and nonpeptidic endothelin receptor antagonists represents an exciting breakthrough in human cardiovascular therapeutics. Two main classes of endothelin receptor antagonist have been developed for possible human therapeutic use: ET(A)-selective and nonselective antagonists. Extensive laboratory and clinical research with these agents has highlighted their promise in various cardiovascular diseases. Randomised, placebo-controlled clinical trials have yielded very encouraging results in patients with hypertension and chronic heart failure with more preliminary data suggesting a possible role in the treatment and prevention of atherosclerosis and stroke. Much more research is needed, however, before endothelin receptor antagonists can be considered for clinical use.

  4. Novel benzopolycyclic amines with NMDA receptor antagonist activity.

    PubMed

    Valverde, Elena; Sureda, Francesc X; Vázquez, Santiago

    2014-05-01

    A new series of benzopolycyclic amines active as NMDA receptor antagonists were synthesized. Most of them exhibited increased activity compared with related analogues previously published. All the tested compounds were more potent than clinically approved amantadine and one of them displayed a lower IC50 value than memantine, an anti-Alzheimer's approved drug.

  5. [Medical economics evaluation of 5-HT3 receptor antagonist drugs].

    PubMed

    Utsunomiya, Junpei; Hirano, Shigeki; Fukui, Aiko; Funabashi, Kazuaki; Deguchi, Yuko; Yamada, Susumu; Naito, Kazuyuki

    2010-10-01

    At Komaki City Hospital, the drug cost in connection with cancer chemotherapy was re-examined as part of improved management along with the introduction of DPC in July 2008. With due attention to the 5-HT3 receptor antagonists, both the change from injections to oral drugs and the change from brand-name drugs to generic drugs were tried between July 2008 and June 2009. After that, in order to examine the economic impact of these changes, we investigated and analyzed the number of medications, the cost of medicine purchased, and the average drug cost per medication of the 5-HT3 receptor antagonists between April 2008 and September 2009. As a result, the cost of 5-HT3 receptor antagonists purchased decreased greatly, and the impact of the improvement was mainly due to the change to oral drugs, and partially to the change to generic drugs. Therefore, from the viewpoint of hospital economic improvement in DPC, it was thought that the change to oral drugs(5-HT3 receptor antagonists)is given top priority.

  6. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2016-09-01

    Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects.

  7. Small molecule antagonists for chemokine CCR3 receptors.

    PubMed

    Willems, Lianne I; Ijzerman, Ad P

    2010-09-01

    The chemokine receptor CCR3 is believed to play a role in the development of allergic diseases such as asthma, atopic dermatitis, and allergic rhinitis. Despite the conflicting results that have been reported regarding the importance of eosinophils and CCR3 in allergic inflammation, inhibition of this receptor with small molecule antagonists is thought to provide a valuable approach for the treatment of these diseases. This review describes the structure-activity relationships (SAR) of small molecule CCR3 antagonists as reported in the scientific and patent literature. Various chemical classes of small molecule CCR3 antagonists have been described so far, including (bi)piperidine and piperazine derivatives, N-arylalkylpiperidine urea derivatives and (N-ureidoalkyl)benzylpiperidines, phenylalanine derivatives, morpholinyl derivatives, pyrrolidinohydroquinazolines, arylsulfonamides, amino-alkyl amides, imidazole- and pyrimidine-based antagonists, and bicyclic diamines. The (N-ureidoalkyl)benzylpiperidines are the best studied class in view of their generally high affinity and antagonizing potential. For many of these antagonists subnanomolar IC(50) values were reported for binding to CCR3 along with the ability to effectively inhibit intracellular calcium mobilization and eosinophil chemotaxis induced by CCR3 agonist ligands in vitro.

  8. Progress towards clinically useful aldosterone synthase inhibitors.

    PubMed

    Cerny, Matthew A

    2013-01-01

    Owing to the high degree of similarity between aldosterone synthase (CYP11B2) and cortisol synthase (CYP11B1), the design of selective inhibitors of one or the other of these two enzymes was, at one time, thought to be impossible. Through development of novel enzyme screening assays and significant medicinal chemistry efforts, highly potent inhibitors of CYP11B2 have been identified with selectivities approaching 1000-fold between the two enzymes. Many of these molecules also possess selectivity against other steroidogenic cytochromes P450 (e.g. CYP17A1 and CYP19A1) as well as hepatic drug metabolizing P450s. Though not as well developed or explored, inhibitors of CYP11B1, with selectivities approaching 50-fold, have also been identified. The therapeutic benefits of affecting the renin-angiotensin-aldosterone system have been well established with the therapeutically useful angiotensin-converting enzymes inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor antagonists. Data regarding the additional benefits of an aldosterone synthase inhibitor (ASi) are beginning to emerge from animal models and human clinical trials. Despite great promise and much progress, additional challenges still exist in the path towards development of a therapeutically useful ASi.

  9. Scaffold variations in amine warhead of histamine H₃ receptor antagonists.

    PubMed

    Wingen, Kerstin; Stark, Holger

    2013-12-01

    The histamine H₃ receptor (H₃R) is involved in numerous regulatory neurotransmission processes and there-fore, is a prominent target for centrally occurring disease with some promising clinical candidates. Previous research resulted in the identification of a core pharmacophore blueprint for H₃R antagonists/inverse agonists, which when inserted in a molecule, mostly ensures acceptable affinity. Nevertheless, variations of scaffold and peripheral areas can increase potency and pharmacokinetic profile of drug candidates. The variations in amine scaffolds of antagonists for this aminergic GPCR are of special importance.

  10. The functional c.-2G>C variant of the mineralocorticoid receptor modulates blood pressure, renin, and aldosterone levels.

    PubMed

    van Leeuwen, Nienke; Caprio, Massimiliano; Blaya, Carolina; Fumeron, Frédéric; Sartorato, Paola; Ronconi, Vanessa; Giacchetti, Gilberta; Mantero, Franco; Fernandes-Rosa, Fabio L; Simian, Christophe; Peyrard, Sévrine; Zitman, Frans G; Penninx, Brenda W J H; de Kloet, E Ron; Azizi, Michel; Jeunemaitre, Xavier; Derijk, Roel H; Zennaro, Maria-Christina

    2010-11-01

    The mineralocorticoid receptor (MR) is essential in the regulation of volemia and blood pressure. Rare mutations in the MR gene cause type 1 pseudohypoaldosteronism and hypertension. In this study we characterized the common MR polymorphism c.-2G>C (rs2070951) in vitro and tested its influence on parameters related to blood pressure regulation and the renin-angiotensin system. In vitro studies showed that the G allele was associated with decreased MR protein levels and reduced transcriptional activation compared with the C allele. Association studies were performed with several outcome variables in 3 independent cohorts: a mild hypertensive group subjected to a salt-sensitivity test, a healthy normotensive group included in a crossover study to receive both a high and low Na/K diet, and a large cohort (The Netherlands Study of Depression and Anxiety), in which blood pressure was measured. Subjects with the GG genotype had significantly higher plasma renin levels both in the mild hypertensive group and in normal volunteers compared with homozygous C carriers. The GG genotype was also correlated with higher plasma aldosterone levels in healthy subjects. In both the mild hypertensive group and The Netherlands Study of Depression and Anxiety cohort the genotype GG was associated with higher systolic blood pressure in males. In conclusion, the G allele of the common functional genetic polymorphism c.-2G>C in the MR gene associates with increased activation of the renin-angiotensin-aldosterone axis and with increased blood pressure, probably related to decreased MR expression.

  11. μ Opioid receptor: novel antagonists and structural modeling

    PubMed Central

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-01-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates. PMID:26888328

  12. μ Opioid receptor: novel antagonists and structural modeling

    NASA Astrophysics Data System (ADS)

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-02-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.

  13. Antagonistic action of pitrazepin on human and rat GABAA receptors

    PubMed Central

    Demuro, Angelo; Martinez-Torres, Ataulfo; Francesconi, Walter; Miledi, Ricardo

    1999-01-01

    Pitrazepin, 3-(piperazinyl-1)-9H-dibenz(c,f) triazolo(4,5-a)azepin is a piperazine antagonist of GABA in a variety of electrophysiological and in vitro binding studies involving GABA and glycine receptors. In the present study we have investigated the effects of pitrazepin, and the GABAA antagonist bicuculline, on membrane currents elicited by GABA in Xenopus oocytes injected with rat cerebral cortex mRNA or cDNAs encoding α1β2 or α1β2γ2S human GABAA receptor subunits.The three types of GABAA receptors expressed were reversibly antagonized by bicuculline and pitrazepin in a concentration-dependent manner. GABA dose-current response curves for the three types of receptors were shifted to the right, in a parallel manner, by increasing concentrations of pitrazepin.Schild analyses gave pA2 values of 6.42±0.62, n=4, 6.41±1.2, n=5 and 6.21±1.24, n=6, in oocytes expressing rat cerebral cortex, α1β2 or α1β2γ2S human GABAA receptors respectively (values are given as means±s.e.mean), and the Hill coefficients were all close to unity. All this is consistent with the notion that pitrazepin acts as a competitive antagonist of these GABAA receptors; and that their antagonism by pitrazepin is not strongly dependent on the subunit composition of the receptors here studied.Since pitrazepin has been reported to act also at the benzodiazepine binding site, we studied the effect of the benzodiazepine antagonist Ro 15-1788 (flumazenil) on the inhibition of α1β2γ2S receptors by pitrazepin. Co-application of Ro 15-1788 did not alter the inhibiting effect of pitrazepin. Moreover, pitrazepin did not antagonize the potentiation of GABA-currents by flunitrazepam. All this suggests that pitrazepin does not affect the GABA receptor-chloride channel by interacting with the benzodiazepine receptor site. PMID:10369456

  14. Aryl biphenyl-3-ylmethylpiperazines as 5-HT7 receptor antagonists.

    PubMed

    Kim, Jeeyeon; Kim, Youngjae; Tae, Jinsung; Yeom, Miyoung; Moon, Bongjin; Huang, Xi-Ping; Roth, Bryan L; Lee, Kangho; Rhim, Hyewhon; Choo, Il Han; Chong, Youhoon; Keum, Gyochang; Nam, Ghilsoo; Choo, Hyunah

    2013-11-01

    The 5-HT7 receptor (5-HT7 R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5-HT7 R antagonist SB-269970 exhibited antidepressant-like activity, whereas systemic administration of the 5-HT7 R agonist AS-19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5-HT7 R antagonists or agonists, aryl biphenyl-3-ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5-HT7 R. Among the synthesized compounds, 1-([2'-methoxy-(1,1'-biphenyl)-3-yl]methyl)-4-(2-methoxyphenyl)piperazine (28) was the best binder to the 5-HT7 R (pKi =7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5-HT7 R over other serotonin receptor subtypes, such as 5-HT1 R, 5-HT2 R, 5-HT3 R, and 5-HT6 R. In a molecular modeling study, the 2-methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function.

  15. The role of the renin-angiotensin-aldosterone system in the pathobiology of pulmonary arterial hypertension (2013 Grover Conference series).

    PubMed

    Maron, Bradley A; Leopold, Jane A

    2014-06-01

    Pulmonary arterial hypertension (PAH) is associated with aberrant pulmonary vascular remodeling that leads to increased pulmonary artery pressure, pulmonary vascular resistance, and right ventricular dysfunction. There is now accumulating evidence that the renin-angiotensin-aldosterone system is activated and contributes to cardiopulmonary remodeling that occurs in PAH. Increased plasma and lung tissue levels of angiotensin and aldosterone have been detected in experimental models of PAH and shown to correlate with cardiopulmonary hemodynamics and pulmonary vascular remodeling. These processes are abrogated by treatment with angiotensin receptor or mineralocorticoid receptor antagonists. At a cellular level, angiotensin and aldosterone activate oxidant stress signaling pathways that decrease levels of bioavailable nitric oxide, increase inflammation, and promote cell proliferation, migration, extracellular matrix remodeling, and fibrosis. Clinically, enhanced renin-angiotensin activity and elevated levels of aldosterone have been detected in patients with PAH, which suggests a role for angiotensin and mineralocorticoid receptor antagonists in the treatment of PAH. This review will examine the current evidence linking renin-angiotensin-aldosterone system activation to PAH with an emphasis on the cellular and molecular mechanisms that are modulated by aldosterone and may be of importance for the pathobiology of PAH.

  16. Therapeutic perspectives in hypertension: novel means for renin-angiotensin-aldosterone system modulation and emerging device-based approaches.

    PubMed

    Unger, Thomas; Paulis, Ludovit; Sica, Domenic A

    2011-11-01

    The conventional antihypertensive therapies including renin-angiotensin-aldosterone system antagonists (converting enzyme inhibitors, receptor blockers, renin inhibitors, and mineralocorticoid receptor blockers), diuretics, β-blockers, and calcium channel blockers are variably successful in achieving the challenging target blood pressure values in hypertensive patients. Difficult to treat hypertension is still a commonly observed problem world-wide. A number of drugs are considered to be used as novel therapies for hypertension. Renalase supplementation, vasopeptidase inhibitors, endothelin antagonists, and especially aldosterone antagonists (aldosterone synthase inhibitors and novel selective mineralocorticoid receptor blockers) are considered an option in resistant hypertension. In addition, the aldosterone antagonists as well as (pro)renin receptor blockers or AT(2) receptor agonists might attenuate end-organ damage. This array of medications has now been complemented by a number of new approaches of non-pharmacological strategies including vaccination, genomic interference, controlled breathing, baroreflex activation, and probably most successfully renal denervation techniques. However, the progress on innovative therapies seems to be slow and the problem of resistant hypertension and proper blood pressure control appears to be still persisting. Therefore the regimens of currently available drugs are being fine-tuned, resulting in the establishment of several novel fixed-dose combinations including triple combinations with the aim to facilitate proper blood pressure control. It remains an exciting question which approach will confer the best blood pressure control and risk reduction in this tricky disease.

  17. Activation of peroxisome proliferator-activated receptor-γ coactivator 1α ameliorates mitochondrial dysfunction and protects podocytes from aldosterone-induced injury.

    PubMed

    Yuan, Yanggang; Huang, Songming; Wang, Wenyan; Wang, Yingying; Zhang, Ping; Zhu, Chunhua; Ding, Guixia; Liu, Bicheng; Yang, Tianxin; Zhang, Aihua

    2012-10-01

    Glomerular podocytes are highly specialized epithelial cells whose injury in glomerular diseases causes proteinuria. Since mitochondrial dysfunction is an early event in podocyte injury, we tested whether a major regulator of oxidative metabolism and mitochondrial function, the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), affects podocyte damage. Aldosterone-induced injury decreased PGC-1α expression, and induced mitochondrial and podocyte damage in dose- and time-dependent manners. The suppression of endogenous PGC-1α by RNAi caused podocyte mitochondrial damage and apoptosis while its increase by infection with an adenoviral vector prevented aldosterone-induced mitochondrial malfunction and inhibited injury. Overexpression of the silent mating type information regulation 2 homolog 1, a gene upstream of PGC-1α, prevented aldosterone-induced mitochondrial damage and podocyte injury by upregulating PGC-1α at both the transcriptional and post-translational levels. Resveratrol, a SIRT1 activator, attenuated aldosterone-induced mitochondrial malfunction and podocyte injury in vitro and in aldosterone-infused mice in vivo. Hence, endogenous PGC-1α may be important for maintenance of mitochondrial function in podocytes under normal conditions. Activators of SIRT1, such as resveratol, may be therapeutically useful in glomerular diseases to promote and maintain PGC-1α expression and, consequently, podocyte integrity.

  18. Optimization of amide-based EP3 receptor antagonists.

    PubMed

    Lee, Esther C Y; Futatsugi, Kentaro; Arcari, Joel T; Bahnck, Kevin; Coffey, Steven B; Derksen, David R; Kalgutkar, Amit S; Loria, Paula M; Sharma, Raman

    2016-06-01

    Prostaglandin E receptor subtype 3 (EP3) antagonism may treat a variety of symptoms from inflammation to cardiovascular and metabolic diseases. Previously, most EP3 antagonists were large acidic ligands that mimic the substrate, prostaglandin E2 (PGE2). This manuscript describes the optimization of a neutral small molecule amide series with improved lipophilic efficiency (LipE) also known as lipophilic ligand efficiency (LLE) ((a) Nat. Rev. Drug Disc.2007, 6, 881; (b) Annu. Rep. Med. Chem.2010, 45, 380).

  19. Human glucagon receptor antagonists based on alkylidene hydrazides.

    PubMed

    Ling, Anthony; Plewe, Michael; Gonzalez, Javier; Madsen, Peter; Sams, Christian K; Lau, Jesper; Gregor, Vlad; Murphy, Doug; Teston, Kimberly; Kuki, Atsuo; Shi, Shenghua; Truesdale, Larry; Kiel, Dan; May, John; Lakis, James; Anderes, Kenna; Iatsimirskaia, Eugenia; Sidelmann, Ulla G; Knudsen, Lotte B; Brand, Christian L; Polinsky, Alex

    2002-02-25

    A series of alkylidene hydrazide derivatives containing an alkoxyaryl moiety was optimized. The resulting hydrazide-ethers were competitive antagonists at the human glucagon receptor. Pharmacokinetic experiments showed fast clearance of most of the compounds tested. A representative compound [4-hydroxy-3-cyanobenzoic acid (4-isopropylbenzyloxy-3,5-dimethoxymethylene)hydrazide] with an IC50 value of 20 nM was shown to reduce blood glucose levels in fasted rats.

  20. [Primary aldosteronism].

    PubMed

    Amar, Laurence

    2015-06-01

    Primary aldosteronism affects 6% of hypertensive patients. The diagnosis should be suspected in any patient with severe or resistant hypertension or hypertension associated with hypokalemia. The screening test consists on the assessment of the aldosterone to renin ratio. In case of an elevated ratio, the diagnosis of primary aldosteronism is confirmed by either elevated concentrations of basal plasma and/or urinary aldosterone or absence of suppression of aldosterone during dynamic test (including the saline infusion test). CT aims to ensure the absence of adrenal carcinoma and to study the morphology of the adrenals. The unilateral or bilateral type of aldosterone secretion is based on the realization of an adrenal venous sampling. When the hypersecretion is unilateral, the treatment consists of adrenalectomy leading to cure of hypertension in 42% of cases, improvement in 40% of cases. For patient with bilateral disease or who don't want to undergo surgery, treatment is based on spironolactone usually at doses of 25 or 50 mg in combination with other antihypertensives drugs such as diuretics or calcium channel blockers.

  1. Discovery of new muscarinic acetylcholine receptor antagonists from Scopolia tangutica

    PubMed Central

    Du, Nana; Liu, Yanfang; Zhang, Xiuli; Wang, Jixia; Zhao, Jianqiang; He, Jian; Zhou, Han; Mei, Lijuan; Liang, Xinmiao

    2017-01-01

    Scopolia tangutica (S. tangutica) is a traditional Chinese medicinal plant used for antispasmodics, anesthesia, analgesia and sedation. Its pharmacological activities are mostly associated with the antagonistic activity at muscarinic acetylcholine receptors (mAchRs) of several known alkaloids such as atropine and scopolamine. With our recent identification of four hydroxycinnamic acid amides from S. tangutica, we hypothesized that this plant may contain previously unidentified alkaloids that may also contribute to its in vivo effect. Herein, we used a bioassay-guided multi-dimension separation strategy to discover novel mAchR antagonists from S. tangutica. The core of this approach is to use label-free cell phenotypic assay to first identify active fractions, and then to guide purification of active ligands. Besides four tropanes and six cinnamic acid amides that have been previously isolated from S. tangutica, we recently identified two new tropanes, one new cinnamic acid amide, and nine other compounds. Six tropane compounds purified from S. tangutica for the first time were confirmed to be competitive antagonists of muscarinic receptor 3 (M3), including the two new ones 8 and 12 with IC50 values of 1.97 μM and 4.47 μM, respectively. Furthermore, the cinnamic acid amide 17 displayed 15-fold selectivity for M1 over M3 receptors. These findings will be useful in designing lead compounds for mAchRs and elucidating mechanisms of action of S. tangutica. PMID:28387362

  2. [5-HT3 receptor antagonist als analgetics in rheumatic diseases].

    PubMed

    Müller, W; Fiebich, B L; Stratz, T

    2006-10-01

    Various rheumatic diseases like fibromyalgia, systemic inflammatory rheumatic disorders and localized diseases, such as arthritides and activated arthroses, tendinopathies and periarthropathies, as well as trigger points can be improved considerably by treatment with the 5-HT3 receptor antagonist tropisetron. Particularly in the latter group of diseases, local injections have done surprisingly rapid analgesic action. This effect matches that of local anesthetics, but lasts considerably longer and is comparable to local injections of local anesthetics combined with corticosteroids. The action of the 5-HT3 receptor antagonists can be attributed to an antinociceptive effect that occurs at the same time as an antiphlogistic and probably also an immunosuppressive effect. Whereas an inhibited release of substance P from the nociceptors, and possibly some other neurokins as well, seems to be the most likely explanation for the antinociceptive action, the antiphlogistic effect is primarily due to an inhibited formation of various different phlogistic substances; in some conditions, like systemic inflammatory rheumatic diseases, for example, the 5-HT3 receptor antagonists may exert an immunosuppressive effect in addition to this.

  3. A prototypical Sigma-1 receptor antagonist protects against brain ischemia.

    PubMed

    Schetz, John A; Perez, Evelyn; Liu, Ran; Chen, Shiuhwei; Lee, Ivan; Simpkins, James W

    2007-11-21

    Previous studies indicate that the Sigma-1 ligand 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) protects the brain from ischemia. Less clear is whether protection is mediated by agonism or antagonism of the Sigma-1 receptor, and whether drugs already in use for other indications and that interact with the Sigma-1 receptor might also prevent oxidative damage due to conditions such as cerebral ischemic stroke. The antipsychotic drug haloperidol is an antagonist of Sigma-1 receptors and in this study it potently protects against oxidative stress-related cell death in vitro at low concentrations. The protective potency of haloperidol and a number of other butyrophenone compounds positively correlate with their affinity for a cloned Sigma-1 receptor, and the protection is mimicked by a Sigma-1 receptor-selective antagonist (BD1063), but not an agonist (PRE-084). In vivo, an acute low dose (0.05 mg/kg s.c.) of haloperidol reduces by half the ischemic lesion volume induced by a transient middle cerebral artery occlusion. These in vitro and in vivo pre-clinical results suggest that a low dose of acutely administered haloperidol might have a novel application as a protective agent against ischemic cerebral stroke and other types of brain injury with an ischemic component.

  4. Functionalized Congeners of P2Y1 Receptor Antagonists:

    SciTech Connect

    de Castro, Sonia; Maruoka, Hiroshi; Hong, Kunlun; Kilbey, II, S Michael; Costanzi, Stefano; Hechler, Béatrice; Gachet, Christian; Harden, T. Kendall; Jacobson, Kenneth A.

    2010-01-01

    The P2Y{sub 1} receptor is a prothrombotic G protein-coupled receptor (GPCR) activated by ADP. Preference for the North (N) ring conformation of the ribose moiety of adenine nucleotide 3',5'-bisphosphate antagonists of the P2Y{sub 1} receptor was established by using a ring-constrained methanocarba (a bicyclo[3.1.0]hexane) ring as a ribose substitute. A series of covalently linkable N{sup 6}-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphates containing extended 2-alkynyl chains was designed, and binding affinity at the human (h) P2Y{sub 1} receptor determined. The chain of these functionalized congeners contained hydrophilic moieties, a reactive substituent, or biotin, linked via an amide. Variation of the chain length and position of an intermediate amide group revealed high affinity of carboxylic congener 8 (K{sub i} 23 nM) and extended amine congener 15 (K{sub i} 132 nM), both having a 2-(1-pentynoyl) group. A biotin conjugate 18 containing an extended {epsilon}-aminocaproyl spacer chain exhibited higher affinity than a shorter biotinylated analogue. Alternatively, click coupling of terminal alkynes of homologous 2-dialkynyl nucleotide derivatives to alkyl azido groups produced triazole derivatives that bound to the P2Y{sub 1} receptor following deprotection of the bisphosphate groups. The preservation of receptor affinity of the functionalized congeners was consistent with new P2Y{sub 1} receptor modeling and ligand docking. Attempted P2Y{sub 1} antagonist conjugation to PAMAM dendrimer carriers by amide formation or palladium-catalyzed reaction between an alkyne on the dendrimer and a 2-iodopurine-derivatized nucleotide was unsuccessful. A dialkynyl intermediate containing the chain length favored in receptor binding was conjugated to an azide-derivatized dendrimer, and the conjugate inhibited ADP-promoted human platelet aggregation. This is the first example of attaching a strategically functionalized P2Y receptor antagonist to a PAMAM dendrimer to

  5. Characterization of a novel non-steroidal glucocorticoid receptor antagonist

    SciTech Connect

    Li, Qun-Yi; Zhang, Meng; Hallis, Tina M.; DeRosier, Therese A.; Yue, Jian-Min; Ye, Yang; Mais, Dale E.; Wang, Ming-Wei

    2010-01-15

    Selective antagonists of the glucocorticoid receptor (GR) are desirable for the treatment of hypercortisolemia associated with Cushing's syndrome, psychic depression, obesity, diabetes, neurodegenerative diseases, and glaucoma. NC3327, a non-steroidal small molecule with potent binding affinity to GR (K{sub i} = 13.2 nM), was identified in a high-throughput screening effort. As a full GR antagonist, NC3327 greatly inhibits the dexamethasone (Dex) induction of marker genes involved in hepatic gluconeogenesis, but has a minimal effect on matrix metalloproteinase 9 (MMP-9), a GR responsive pro-inflammatory gene. Interestingly, the compound recruits neither coactivators nor corepressors to the GR complex but competes with glucocorticoids for the interaction between GR and a coactivator peptide. Moreover, NC3327 does not trigger GR nuclear translocation, but significantly blocks Dex-induced GR transportation to the nucleus, and thus appears to be a 'competitive' GR antagonist. Therefore, the non-steroidal compound, NC3327, may represent a new class of GR antagonists as potential therapeutics for a variety of cortisol-related endocrine disorders.

  6. NMDA receptor antagonists extend the sensitive period for imprinting.

    PubMed

    Parsons, C H; Rogers, L J

    2000-03-01

    Filial imprinting in the domestic chick occurs during a sensitive period of development. The exact timing of this period can vary according to the methods used to measure imprinting. Using our imprinting paradigm, we have shown that normal, dark-reared chicks lose the ability to imprint after the second day post-hatching. Further, we reported that chicks treated 10 h after hatching with a mixture of the noncompetitive NMDA receptor antagonist ketamine (55 mg/kg) and the alpha(2)-adrenergic receptor agonist xylazine (6 mg/kg) were able to imprint on day 8 after hatching, whereas controls treated with saline did not imprint. We now show that the effect of the ketamine-xylazine mixture can be mimicked by treating chicks with ketamine alone or with another noncompetitive NMDA receptor antagonist, MK-801 (5 mg/kg). Treating chicks with a single dose of ketamine (55 mg/kg) or with a single dose of xylazine (6 mg/kg) failed to produce the effect on the sensitive period. However, prolonging the action of ketamine by treating chicks with two doses of ketamine (at 10 and 12 h after hatching) did allow imprinting on day 8. In contrast, prolonging the action of xylazine had no effect on the sensitive period for imprinting. Chicks treated with MK-801 were also able to imprint on day 8. Thus, we have evidence that the NMDA receptor system is involved in the mechanisms that control the sensitive period for imprinting.

  7. [Aldosterone and kidney diseases: an emergent paradigm with important clinical implications].

    PubMed

    Bertocchio, Jean-Philippe; Jaisser, Frédéric

    2011-06-01

    Slowing the progression of chronic kidney diseases needs new efficient treatments. Aldosterone classically acts on the distal nephron: it allows sodium reabsorption, potassium secretion and participates to blood volume control. Recently, new targets of aldosterone have been described including the heart and the vasculature but also non-epithelial kidney cells such as mesangial cells, podocytes and renal fibroblasts. The pathophysiological implication of aldosterone and its receptor, the mineralocorticoid receptor has been demonstrated ex vivo in cell culture and in vivo in experimental animal models with kidney damages such as diabetic and hypertensive kidney nephropathies, chronic kidney disease and glomerulopathies. The beneficial effects of the pharmacological antagonists of the mineralocorticoid receptor are independent of the hypertensive effect of aldosterone, indicating that blocking the activation of the mineralocorticoid receptor in these non-classical renal targets may be of clinical importance. Several clinical studies now report benefit and safety when using spironolactone or eplerenone, the currently available mineralocorticoid receptor antagonists, in patients with kidney diseases. In this review, we discuss the recent results reported in experimental and clinical research in this domain.

  8. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    PubMed Central

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  9. Vasopressin receptor antagonists, heart failure, and polycystic kidney disease.

    PubMed

    Torres, Vicente E

    2015-01-01

    The synthesis of nonpeptide orally bioavailable vasopressin antagonists devoid of agonistic activity (vaptans) has made possible the selective blockade of vasopressin receptor subtypes for therapeutic purposes. Vaptans acting on the vasopressin V2 receptors (aquaretics) have attracted attention as a possible therapy for heart failure and polycystic kidney disease. Despite a solid rationale and encouraging preclinical testing, aquaretics have not improved clinical outcomes in randomized clinical trials for heart failure. Additional clinical trials with select population targets, more flexible dosing schedules, and possibly a different drug type or combination (balanced V1a/V2 receptor antagonism) may be warranted. Aquaretics are promising for the treatment of autosomal dominant polycystic kidney disease and have been approved in Japan for this indication. More studies are needed to better define their long-term safety and efficacy and optimize their utilization.

  10. Osmotic stress regulates mineralocorticoid receptor expression in a novel aldosterone-sensitive cortical collecting duct cell line.

    PubMed

    Viengchareun, Say; Kamenicky, Peter; Teixeira, Marie; Butlen, Daniel; Meduri, Geri; Blanchard-Gutton, Nicolas; Kurschat, Christine; Lanel, Aurélie; Martinerie, Laetitia; Sztal-Mazer, Shoshana; Blot-Chabaud, Marcel; Ferrary, Evelyne; Cherradi, Nadia; Lombès, Marc

    2009-12-01

    Aldosterone effects are mediated by the mineralocorticoid receptor (MR), a transcription factor highly expressed in the distal nephron. Given that MR expression level constitutes a key element controlling hormone responsiveness, there is much interest in elucidating the molecular mechanisms governing MR expression. To investigate whether hyper- or hypotonicity could affect MR abundance, we established by targeted oncogenesis a novel immortalized cortical collecting duct (CCD) cell line and examined the impact of osmotic stress on MR expression. KC3AC1 cells form domes, exhibit a high transepithelial resistance, express 11beta-hydroxysteroid dehydrogenase 2 and functional endogenous MR, which mediates aldosterone-stimulated Na(+) reabsorption through the epithelial sodium channel activation. MR expression is tightly regulated by osmotic stress. Hypertonic conditions induce expression of tonicity-responsive enhancer binding protein, an osmoregulatory transcription factor capable of binding tonicity-responsive enhancer response elements located in MR regulatory sequences. Surprisingly, hypertonicity leads to a severe reduction in MR transcript and protein levels. This is accompanied by a concomitant tonicity-induced expression of Tis11b, a mRNA-destabilizing protein that, by binding to the AU-rich sequences of the 3'-untranslated region of MR mRNA, may favor hypertonicity-dependent degradation of labile MR transcripts. In sharp contrast, hypotonicity causes a strong increase in MR transcript and protein levels. Collectively, we demonstrate for the first time that optimal adaptation of CCD cells to changes in extracellular fluid composition is accompanied by drastic modification in MR abundance via transcriptional and posttranscriptional mechanisms. Osmotic stress-regulated MR expression may represent an important molecular determinant for cell-specific MR action, most notably in renal failure, hypertension, or mineralocorticoid resistance.

  11. Aldosterone Receptor Antagonism Reduces Urinary C-Reactive Protein Excretion in Angiotensin II-Infused, Hypertensive Rats

    PubMed Central

    Ortiz, Rudy M.; Mamalis, Andrew; Navar, L. Gabriel

    2009-01-01

    Background Elevated C-reactive protein (CRP) may contribute to elevated arterial pressure in Ang II-dependent hypertension. However, the in vivo effects of Ang II and of mineralocorticoid receptor (MR) antagonism on CRP during Ang II-dependent hypertension have not been examined. In addition, urinary CRP excretion as a method to monitor the progression of Ang II-induced inflammation has not been evaluated. Methods Urine samples were collected from three groups (n = 10/group) of rats: 1) normotensive control, 2) angiotensin II infused (Ang II; 60 ng/min), and 3) Ang II + eplerenone (epl; 25 mg/d). A diet containing epl (0.1 %) was provided after 1 week of Ang II infusion. Results After 28 d, Ang II increased SBP from 136 ± 5 to 207 ± 8 mmHg; this response in SBP was not altered following MR antagonism (215 ± 6 mmHg). Ang II-infusion increased plasma CRP from 14 ± 2 to 26 ± 3 μg/mL and increased urinary CRP excretion nearly 8-fold (143 ± 26 vs 1102 ± 115 ng/d). Treatment with eplerenone reduced plasma CRP by 25 % and urinary immunoreactive CRP (irCRP) by 34 % in Ang II-infused rats suggesting that aldosterone contributes to the CRP-associated inflammatory response in Ang II-dependent hypertension. Conclusions The increase in SBP preceded the increase in irCRP excretion by at least 4 days suggesting that CRP does not significantly contribute to increased arterial blood pressure in Ang II-dependent hypertension. The blockade of MR reduced plasma CRP and urinary irCRP excretion demonstrating the contribution of aldosterone to the Ang II-induced generation of CRP. Furthermore, urinary CRP may serve as a non-invasive index for monitoring cardiovascular inflammation during hypertension. PMID:20161115

  12. Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity

    SciTech Connect

    Maton, P.N.; Sutliff, V.E.; Jensen, R.T.; Gardner, J.D.

    1985-04-01

    The authors used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ- lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of /sup 125/I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain.

  13. Factors affecting the aldosterone/renin ratio.

    PubMed

    Stowasser, M; Ahmed, A H; Pimenta, E; Taylor, P J; Gordon, R D

    2012-03-01

    Although the aldosterone/renin ratio (ARR) is the most reliable screening test for primary aldo-steronism, false positives and negatives occur. Dietary salt restriction, concomitant malignant or renovascular hypertension, pregnancy and treatment with diuretics (including spironolactone), dihydropyridine calcium blockers, angiotensin converting enzyme inhibitors, and angiotensin receptor antagonists can produce false negatives by stimulating renin. We recently reported selective serotonin reuptake inhibitors lower the ratio. Because potassium regulates aldosterone, uncorrected hypokalemia can lead to false negatives. Beta-blockers, alpha-methyldopa, clonidine, and nonsteroidal anti-inflammatory drugs suppress renin, raising the ARR with potential for false positives. False positives may occur in patients with renal dysfunction or advancing age. We recently showed that (1) females have higher ratios than males, and (2) false positive ratios can occur during the luteal menstrual phase and while taking an oral ethynylestradiol/drospirenone (but not implanted subdermal etonogestrel) contraceptive, but only if calculated using direct renin concentration and not plasma renin activity. Where feasible, diuretics should be ceased at least 6 weeks and other interfering medications at least 2 before ARR measurement, substituting noninterfering agents (e. g., verapamil slow-release±hydralazine and prazosin or doxazosin) were required. Hypokalemia should be corrected and a liberal salt diet encouraged. Collecting blood midmorning from seated patients following 2-4 h upright posture improves sensitivity. The ARR is a screening test only and should be repeated once or more before deciding whether to proceed to confirmatory suppression testing. Liquid chromatography-tandem mass spectrometry aldosterone assays represent a major advance towards addressing inaccuracies inherent in other available methods.

  14. Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists.

    PubMed

    Ajram, Laura; Begg, Malcolm; Slack, Robert; Cryan, Jenni; Hall, David; Hodgson, Simon; Ford, Alison; Barnes, Ashley; Swieboda, Dawid; Mousnier, Aurelie; Solari, Roberto

    2014-04-15

    The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

  15. Substituted Tetrahydroisoquinolines as Selective Antagonists for the Orexin 1 Receptor

    PubMed Central

    Perrey, David A.; German, Nadezhda A.; Gilmour, Brian P.; Li, Jun-Xu; Harris, Danni L.; Thomas, Brian F.; Zhang, Yanan

    2013-01-01

    Increasing evidence implicates the orexin 1 (OX1) receptor in reward processes, suggesting OX1 antagonism could be therapeutic in drug addiction. In a program to develop an OX1 selective antagonist, we designed and synthesized a series of substituted tetrahydroisoquinolines and determined their potency in OX1 and OX2 calcium mobilization assays. Structure-activity relationship (SAR) studies revealed limited steric tolerance and preference for electron deficiency at the 7-position. Pyridylmethyl groups were shown to be optimal for activity at the acetamide position. Computational studies resulted in a pharmacophore model and confirmed the SAR results. Compound 72 significantly attenuated the development of place preference for cocaine in rats. PMID:23941044

  16. Aberrant gonadotropin-releasing hormone receptor (GnRHR) expression and its regulation of CYP11B2 expression and aldosterone production in adrenal aldosterone-producing adenoma (APA).

    PubMed

    Nakamura, Yasuhiro; Hattangady, Namita G; Ye, Ping; Satoh, Fumitoshi; Morimoto, Ryo; Ito-Saito, Takako; Sugawara, Akira; Ohba, Koji; Takahashi, Kazuhiro; Rainey, William E; Sasano, Hironobu

    2014-03-25

    Aberrant expression of gonadotropin-releasing hormone receptor (GnRHR) has been reported in human adrenal tissues including aldosterone-producing adenoma (APA). However, the details of its expression and functional role in adrenals are still not clear. In this study, quantitative RT-PCR analysis revealed the mean level of GnRHR mRNA was significantly higher in APAs than in human normal adrenal (NA) (P=0.004). GnRHR protein expression was detected in human NA and neoplastic adrenal tissues. In H295R cells transfected with GnRHR, treatment with GnRH resulted in a concentration-dependent increase in CYP11B2 reporter activity. Chronic activation of GnRHR with GnRH (100nM), in a cell line with doxycycline-inducible GnRHR (H295R-TR/GnRHR), increased CYP11B2 expression and aldosterone production. These agonistic effects were inhibited by blockers for the calcium signaling pathway, KN93 and calmidazolium. These results suggest GnRH, through heterotopic expression of its receptor, may be a potential regulator of CYP11B2 expression levels in some cases of APA.

  17. Serum aldosterone and death, end-stage renal disease, and cardiovascular events in blacks and whites: findings from the Chronic Renal Insufficiency Cohort (CRIC) Study.

    PubMed

    Deo, Rajat; Yang, Wei; Khan, Abigail M; Bansal, Nisha; Zhang, Xiaoming; Leonard, Mary B; Keane, Martin G; Soliman, Elsayed Z; Steigerwalt, Susan; Townsend, Raymond R; Shlipak, Michael G; Feldman, Harold I

    2014-07-01

    Prior studies have demonstrated that elevated aldosterone concentrations are an independent risk factor for death in patients with cardiovascular disease. Limited studies, however, have evaluated systematically the association between serum aldosterone and adverse events in the setting of chronic kidney disease. We investigated the association between serum aldosterone and death and end-stage renal disease in 3866 participants from the Chronic Renal Insufficiency Cohort. We also evaluated the association between aldosterone and incident congestive heart failure and atherosclerotic events in participants without baseline cardiovascular disease. Cox proportional hazards models were used to evaluate independent associations between elevated aldosterone concentrations and each outcome. Interactions were hypothesized and explored between aldosterone and sex, race, and the use of loop diuretics and renin-angiotensin-aldosterone system inhibitors. During a median follow-up period of 5.4 years, 587 participants died, 743 developed end-stage renal disease, 187 developed congestive heart failure, and 177 experienced an atherosclerotic event. Aldosterone concentrations (per SD of the log-transformed aldosterone) were not an independent risk factor for death (adjusted hazard ratio, 1.00; 95% confidence interval, 0.93-1.12), end-stage renal disease (adjusted hazard ratio, 1.07; 95% confidence interval, 0.99-1.17), or atherosclerotic events (adjusted hazard ratio, 1.04; 95% confidence interval, 0.85-1.18). Aldosterone was associated with congestive heart failure (adjusted hazard ratio, 1.21; 95% confidence interval, 1.02-1.35). Among participants with chronic kidney disease, higher aldosterone concentrations were independently associated with the development of congestive heart failure but not for death, end-stage renal disease, or atherosclerotic events. Further studies should evaluate whether mineralocorticoid receptor antagonists may reduce adverse events in individuals with

  18. Cangrelor: a novel P2Y12 receptor antagonist.

    PubMed

    Norgard, Nicholas B

    2009-08-01

    Antiplatelet therapy is critical in the prevention of thrombotic complications of acute coronary syndrome and percutaneous coronary interventions. Current antiplatelet agents (aspirin, clopidogrel and glycoprotein IIb/IIIa antagonists) have demonstrated the capacity to reduce major adverse cardiac events. However, these agents have limitations that compromise their clinical utility. The platelet P2Y12 receptor plays a central role in platelet function and is a focus in the development of antiplatelet therapies. Cangrelor is a potent, competitive inhibitor of the P2Y12 receptor that is administered by intravenous infusion and rapidly achieves near complete inhibition of ADP-induced platelet aggregation. This investigational drug has been studied for use during coronary procedures and the management of patients experiencing acute coronary syndrome and is undergoing evaluation for use in the prevention of perioperative stent thrombosis.

  19. Is All Radiation-Induced Emesis Ameliorated by 5-HT3 Receptor Antagonists

    DTIC Science & Technology

    1992-01-01

    5 - HT3 receptor antagonists ;~// 9-72 Bernard M.I Rabin 0’) and Gregory L. Kingt2) -) Behavioral Sciences and 2 PhYSzo~o~y Dcpiarlrnvni . Arm,. ii - R...RY Exposing ferrets to gamuma rays or X-rays produces vomiting that can be attenuated by 5 - HT3 receptor antagonists and by subdiaphraqmatic vagotomy...Pretreating ferrets with serotonin type-3 ( 5 - HT3 ) receptor antagonists or performing bilateral subdiaphragmatic vagotomy reliably attenuates the

  20. Interaction of Pyridostigmine with the 5-HT(3) Receptor Antagonist Ondansetron in Guinea Pigs

    DTIC Science & Technology

    1993-05-13

    5 - HT3 RECEPTOR - ANTAGONIST .ONDANSETRON IN GUINEA PIGS BR. Capacio, CE. Byers...apart. REFERENCES 1. Fozard JR. 5 -HT; The Enigma Variations. =JE, 8, 501-506 (December 1987). 2. Watling KJ. 5 - HT3 Receptor Agonists and Antagonists . In... 5 -HT receptor subtype three antagonists (5HT 3 ) such as the compound ondansetron (OND) have been identified as useful in the treatment of

  1. Translational Success Stories: Role of Mineralocorticoid Receptor Antagonists in Cardiovascular Disease

    PubMed Central

    Ferrario, Carlos M; Schiffrin, Ernesto L

    2014-01-01

    Aldosterone exerts its best known sodium homeostasis actions by controlling sodium excretion at the level of the distal tubules via activation of the apical epithelial sodium channel (ENaC) and the basolateral Na+/K+ ATPase pump. Recently, this mineralocorticoid hormone has been demonstrated to act on the heart and blood vessels. Excess release of aldosterone in relation to the salt status induces both genomic and non-genomic effects that by promoting endothelial dysfunction, and vascular and cardio-renal adverse remodeling, contribute to the target organ damage found in hypertension, heart failure, myocardial infarction and chronic renal failure. Mineralocorticoid receptor blockers have been shown to be highly effective in resistant hypertension and to slow down heart failure progression, and in experimental animals, the development of atherosclerosis. Blockade of the action of aldosterone and potentially other mineralocorticoid steroids has been increasingly demonstrated to be an extremely beneficial therapy in different forms of cardiovascular disease. This review provides a summary of the knowledge that exists regarding aldosterone actions in the cardiovascular system and, in providing the translational impact of this knowledge to the clinical arena, illustrates how much more needs to be achieved in exploring the use of mineralocorticoid receptor blockers in less advanced stages of heart, renal, and vascular disease. PMID:25552697

  2. Evodiamine as a novel antagonist of aryl hydrocarbon receptor

    SciTech Connect

    Yu, Hui; Tu, Yongjiu; Zhang, Chun; Fan, Xia; Wang, Xi; Wang, Zhanli; Liang, Huaping

    2010-11-05

    Research highlights: {yields} Evodiamine interacted with the AhR. {yields} Evodiamine inhibited the specific binding of [{sup 3}H]-TCDD to the AhR. {yields} Evodiamine acts as an antagonist of the AhR. -- Abstract: Evodiamine, the major bioactive alkaloid isolated from Wu-Chu-Yu, has been shown to interact with a wide variety of proteins and modify their expression and activities. In this study, we investigated the interaction between evodiamine and the aryl hydrocarbon receptor (AhR). Molecular modeling results revealed that evodiamine directly interacted with the AhR. Cytosolic receptor binding assay also provided the evidence that evodiamine could interact with the AhR with the K{sub i} value of 28.4 {+-} 4.9 nM. In addition, we observed that evodiamine suppressed the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced nuclear translocation of the AhR and the expression of CYP1A1 dose-dependently. These results suggested that evodiamine was able to bind to the AhR as ligand and exhibit antagonistic effects.

  3. Classification and virtual screening of androgen receptor antagonists.

    PubMed

    Li, Jiazhong; Gramatica, Paola

    2010-05-24

    Computational tools, such as quantitative structure-activity relationship (QSAR), are highly useful as screening support for prioritization of substances of very high concern (SVHC). From the practical point of view, QSAR models should be effective to pick out more active rather than inactive compounds, expressed as sensitivity in classification works. This research investigates the classification of a big data set of endocrine-disrupting chemicals (EDCs)-androgen receptor (AR) antagonists, mainly aiming to improve the external sensitivity and to screen for potential AR binders. The kNN, lazy IB1, and ADTree methods and the consensus approach were used to build different models, which improve the sensitivity on external chemicals from 57.1% (literature) to 76.4%. Additionally, the models' predictive abilities were further validated on a blind collected data set (sensitivity: 85.7%). Then the proposed classifiers were used: (i) to distinguish a set of AR binders into antagonists and agonists; (ii) to screen a combined estrogen receptor binder database to find out possible chemicals that can bind to both AR and ER; and (iii) to virtually screen our in-house environmental chemical database. The in silico screening results suggest: (i) that some compounds can affect the normal endocrine system through a complex mechanism binding both to ER and AR; (ii) new EDCs, which are nonER binders, but can in silico bind to AR, are recognized; and (iii) about 20% of compounds in a big data set of environmental chemicals are predicted as new AR antagonists. The priority should be given to them to experimentally test the binding activities with AR.

  4. Guanidinoethyl sulphonate is a glycine receptor antagonist in striatum.

    PubMed

    Sergeeva, Olga A; Chepkova, Aisa N; Haas, Helmut L

    2002-11-01

    1. Guanidinoethyl sulphonate (GES) is an analogue of taurine and an inhibitor of taurine transport. Interactions of GES with GABA(A) and glycine receptors are studied by whole cell recording and fast drug application in isolated striatal neurons of the mouse. 2. We confirm that GES is a weak agonist at GABA(A) receptors, and is able to antagonize GABA-evoked responses. GES did not gate GlyR. 3. GES antagonized glycine responses in a concentration-dependent and surmountable manner. Glycine dose-response curves were shifted to the right by GES (0.5 mM), yielding EC(50)s and Hill coefficients of 62 micro M and 2.5 in control, 154 micro M and 1.3 in the presence of GES. 4. GlyR-mediated taurine responses were competitively antagonized by GES. Taurine dose-response curves, in contrast to the glycine dose-response curves were shifted by GES to the right in a parallel manner. 5. The GlyR-block by GES was not voltage-dependent. 6. In contrast to our findings in the mouse, in rat striatal neurons which lack expression of the alpha3 GlyR subunit, GES shifted the glycine dose-response curve to the right in a parallel way without affecting the maximal response. Subtype-specificity of the GES action at GlyR must await further investigation in artificial expression systems. 7. We conclude that GES is a competitive antagonist at GlyR. The antagonistic action of GES at inhibitory ionotropic receptors can explain its epileptogenic action. Care must be taken with the interpretation of data on GES evoked taurine release.

  5. Dopaminergic Inhibition of Metoclopramide-induced Aldosterone Secretion in Man

    PubMed Central

    Carey, Robert M.; Thorner, Michael O.; Ortt, Elizabeth M.

    1980-01-01

    prolactin levels and completely inhibited the prolactin responses to metoclopramide. In contrast, bromocriptine did not alter basal plasma aldosterone concentrations or the aldosterone responses to metoclopramide. Plasma renin activity, plasma cortisol, and serum potassium concentrations were unchanged by metoclopramide, dopamine, or bromocriptine. The results of this study suggest that the aldosterone response to metoclopramide is mediated by metoclopramide's antagonist activity at the dopamine receptor level. The results further suggest dissociation of the responses to the dopamine agonists, dopamine and bromocriptine, and indicate that a new type of dopamine receptor may inhibit aldosterone secretion. PMID:7400305

  6. Aldosterone induces fibrosis, oxidative stress and DNA damage in livers of male rats independent of blood pressure changes.

    PubMed

    Queisser, Nina; Happ, Kathrin; Link, Samuel; Jahn, Daniel; Zimnol, Anna; Geier, Andreas; Schupp, Nicole

    2014-11-01

    Mineralocorticoid receptor blockers show antifibrotic potential in hepatic fibrosis. The mechanism of this protective effect is not known yet, although reactive oxygen species seem to play an important role. Here, we investigated the effects of elevated levels of aldosterone (Ald), the primary ligand of the mineralocorticoid receptor, on livers of rats in a hyperaldosteronism model: aldosterone-induced hypertension. Male Sprague-Dawley rats were treated for 4 weeks with aldosterone. To distinguish if damage caused in the liver depended on increased blood pressure or on increased Ald levels, the mineralocorticoid receptor antagonist spironolactone was given in a subtherapeutic dose, not normalizing blood pressure. To investigate the impact of oxidative stress, the antioxidant tempol was administered. Aldosterone induced fibrosis, detected histopathologically, and by expression analysis of the fibrosis marker, α-smooth muscle actin. Further, the mRNA amount of the profibrotic cytokine TGF-β was increased significantly. Fibrosis could be reduced by scavenging reactive oxygen species, and also by blocking the mineralocorticoid receptor. Furthermore, aldosterone treatment caused oxidative stress and DNA double strand breaks in livers, as well as the elevation of DNA repair activity. An increase of the transcription factor Nrf2, the main regulator of the antioxidative response could be observed, and of its target genes heme oxygenase-1 and γ-glutamylcysteine synthetase. All these effects of aldosterone were prevented by spironolactone and tempol. Already after 4 weeks of treatment, aldosteroneinfusion induced fibrosis in the liver. This effect was independent of elevated blood pressure. DNA damage caused by aldosterone might contribute to fibrosis progression when aldosterone is chronically increased.

  7. Aldosterone decreases glucose-stimulated insulin secretion in vivo in mice and in murine islets

    PubMed Central

    Luo, P.; Kreger, M. T.; Brissova, M.; Dai, C.; Whitfield, T. T.; Kim, H. S.; Wasserman, D. H.; Powers, A. C.; Brown, N. J.

    2011-01-01

    Aims/hypothesis Aldosterone concentrations increase in obesity and predict the onset of diabetes. We investigated the effects of aldosterone on glucose homeostasis and insulin secretion in vivo and in vitro. Methods We assessed insulin sensitivity and insulin secretion in aldosterone synthase-deficient (As [also known as Cyp11b2]−/−)and wild-type mice using euglycaemic-hyperinsulinaemic and hyperglycaemic clamps, respectively. We also conducted studies during high sodium intake to normalise renin activity and potassium concentration in As−/− mice. We subsequently assessed the effect of aldosterone on insulin secretion in vitro in the presence or absence of mineralocorticoid receptor antagonists in isolated C57BL/6J islets and in the MIN6 beta cell line. Results Fasting glucose concentrations were reduced in As−/−mice compared with wild-type. During hyperglycaemic clamps, insulin and C-peptide concentrations increased to a greater extent in As−/− than in wild-type mice. This was not attributable to differences in potassium or angiotensin II, as glucose-stimulated insulin secretion was enhanced in As−/− mice even during high sodium intake. There was no difference in insulin sensitivity between As−/− and wild-type mice in euglycaemic-hyperinsulinaemic clamp studies. In islet and MIN6 beta cell studies, aldosterone inhibited glucose and isobutylmethylxanthine-stimulated insulin secretion, an effect that was not blocked by mineralocorticoid receptor antagonism, but was prevented by the superoxide dismutase mimetic tempol. Conclusions/interpretation We demonstrated that aldosterone deficiency or excess modulates insulin secretion in vivo and in vitro via reactive oxygen species and in a manner that is independent of mineralocorticoid receptors. These findings provide insight into the mechanism of glucose intolerance in conditions of relative aldosterone excess. PMID:21519965

  8. Identification of New Agonists and Antagonists of the Insect Odorant Receptor Co-Receptor Subunit

    PubMed Central

    Chen, Sisi; Luetje, Charles W.

    2012-01-01

    Background Insects detect attractive and aversive chemicals using several families of chemosensory receptors, including the OR family of olfactory receptors, making these receptors appealing targets for the control of insects. Insect ORs are odorant-gated ion channels, comprised of at least one common subunit (the odorant receptor co-receptor subunit, Orco) and at least one variable odorant specificity subunit. Each of the many ORs of an insect species is activated or inhibited by an unique set of odorants that interact with the variable odorant specificity subunits, making the development of OR directed insect control agents complex and laborious. However, several N-,2-substituted triazolothioacetamide compounds (VUAA1, VU0450667 and VU0183254) were recently shown to act directly on the highly conserved Orco subunit, suggesting that broadly active compounds can be developed. We have explored the chemical space around the VUAA1 structure in order to identify new Orco ligands. Principal Findings We screened ORs from several insect species, using heterologous expression in Xenopus oocytes and an electrophysiological assay, with a panel of 22 compounds structurally related to VUAA1. By varying the nitrogen position in the pyridine ring and altering the moieties decorating the phenyl ring, we identified two new agonists and a series of competitive antagonists. Screening smaller compounds, similar to portions of the VUAA1 structure, also yielded competitive antagonists. Importantly, we show that Orco antagonists inhibit odorant activation of ORs from several insect species. Detailed examination of one antagonist demonstrated inhibition to be through a non-competitive mechanism. Conclusions A similar pattern of agonist and antagonist sensitivity displayed by Orco subunits from different species suggests a highly conserved binding site structure. The susceptibility to inhibition of odorant activation by Orco antagonism is conserved across disparate insect species

  9. Aldosterone blood test

    MedlinePlus

    ... hypotension) Aldosterone is a hormone released by the adrenal glands . It helps the body regulate blood pressure. Aldosterone ... may be due to Bartter syndrome (extremely rare) Adrenal glands release too much aldosterone hormone ( primary hyperaldosteronism - usually ...

  10. Orexin receptor antagonists as therapeutic agents for insomnia

    PubMed Central

    Equihua, Ana C.; De La Herrán-Arita, Alberto K.; Drucker-Colin, Rene

    2013-01-01

    Insomnia is a common clinical condition characterized by difficulty initiating or maintaining sleep, or non-restorative sleep with impairment of daytime functioning. Currently, treatment for insomnia involves a combination of cognitive behavioral therapy (CBTi) and pharmacological therapy. Among pharmacological interventions, the most evidence exists for benzodiazepine (BZD) receptor agonist drugs (GABAA receptor), although concerns persist regarding their safety and their limited efficacy. The use of these hypnotic medications must be carefully monitored for adverse effects. Orexin (hypocretin) neuropeptides have been shown to regulate transitions between wakefulness and sleep by promoting cholinergic/monoaminergic neural pathways. This has led to the development of a new class of pharmacological agents that antagonize the physiological effects of orexin. The development of these agents may lead to novel therapies for insomnia without the side effect profile of hypnotics (e.g., impaired cognition, disturbed arousal, and motor balance difficulties). However, antagonizing a system that regulates the sleep-wake cycle may create an entirely different side effect profile. In this review, we discuss the role of orexin and its receptors on the sleep-wake cycle and that of orexin antagonists in the treatment of insomnia. PMID:24416019

  11. Orexin receptor antagonists as therapeutic agents for insomnia.

    PubMed

    Equihua, Ana C; De La Herrán-Arita, Alberto K; Drucker-Colin, Rene

    2013-12-25

    Insomnia is a common clinical condition characterized by difficulty initiating or maintaining sleep, or non-restorative sleep with impairment of daytime functioning. Currently, treatment for insomnia involves a combination of cognitive behavioral therapy (CBTi) and pharmacological therapy. Among pharmacological interventions, the most evidence exists for benzodiazepine (BZD) receptor agonist drugs (GABAA receptor), although concerns persist regarding their safety and their limited efficacy. The use of these hypnotic medications must be carefully monitored for adverse effects. Orexin (hypocretin) neuropeptides have been shown to regulate transitions between wakefulness and sleep by promoting cholinergic/monoaminergic neural pathways. This has led to the development of a new class of pharmacological agents that antagonize the physiological effects of orexin. The development of these agents may lead to novel therapies for insomnia without the side effect profile of hypnotics (e.g., impaired cognition, disturbed arousal, and motor balance difficulties). However, antagonizing a system that regulates the sleep-wake cycle may create an entirely different side effect profile. In this review, we discuss the role of orexin and its receptors on the sleep-wake cycle and that of orexin antagonists in the treatment of insomnia.

  12. Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise.

    PubMed

    Casey, Darren P; Madery, Brandon D; Pike, Tasha L; Eisenach, John H; Dietz, Niki M; Joyner, Michael J; Wilkins, Brad W

    2009-10-01

    We tested the hypothesis that adenosine contributes to augmented skeletal muscle vasodilation during hypoxic exercise. In separate protocols, subjects performed incremental rhythmic forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O2 saturation). In protocol 1 (n = 8), subjects received an intra-arterial administration of saline (control) and aminophylline (adenosine receptor antagonist). In protocol 2 (n = 10), subjects received intra-arterial phentolamine (alpha-adrenoceptor antagonist) and combined phentolamine and aminophylline administration. Forearm vascular conductance (FVC; in ml x min(-1).100 mmHg(-1)) was calculated from forearm blood flow (in ml/min) and blood pressure (in mmHg). In protocol 1, the change in FVC (DeltaFVC; change from normoxic baseline) during hypoxic exercise with saline was 172 +/- 29 and 314 +/- 34 ml x min(-1) x 100 mmHg(-1) (10% and 20%, respectively). Aminophylline administration did not affect DeltaFVC during hypoxic exercise at 10% (190 +/- 29 ml x min(-1)x100 mmHg(-1), P = 0.4) or 20% (287 +/- 48 ml x min(-1) x 100 mmHg(-1), P = 0.3). In protocol 2, DeltaFVC due to hypoxic exercise with phentolamine infusion was 313 +/- 30 and 453 +/- 41 ml x min(-1) x 100 mmHg(-1) (10% and 20% respectively). DeltaFVC was similar at 10% (352 +/- 39 ml min(-1) x 100 mmHg(-1), P = 0.8) and 20% (528 +/- 45 ml x min(-1) x 100 mmHg(-1), P = 0.2) hypoxic exercise with combined phentolamine and aminophylline. In contrast, DeltaFVC to exogenous adenosine was reduced by aminophylline administration in both protocols (P < 0.05 for both). These observations suggest that adenosine receptor activation is not obligatory for the augmented hyperemia during hypoxic exercise in humans.

  13. Implementation of a fluorescence-based screening assay identifies histamine H3 receptor antagonists clobenpropit and iodophenpropit as subunit-selective N-methyl-D-aspartate receptor antagonists.

    PubMed

    Hansen, Kasper B; Mullasseril, Praseeda; Dawit, Sara; Kurtkaya, Natalie L; Yuan, Hongjie; Vance, Katie M; Orr, Anna G; Kvist, Trine; Ogden, Kevin K; Le, Phuong; Vellano, Kimberly M; Lewis, Iestyn; Kurtkaya, Serdar; Du, Yuhong; Qui, Min; Murphy, T J; Snyder, James P; Bräuner-Osborne, Hans; Traynelis, Stephen F

    2010-06-01

    N-Methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca(2+)-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal concentrations of glutamate and glycine to minimize detection of competitive antagonists. The assay is validated by successfully identifying known noncompetitive, but not competitive NMDA receptor antagonists among 1800 screened compounds from two small focused libraries, including the commercially available library of pharmacologically active compounds. Hits from the primary screen are validated through a secondary screen that used two-electrode voltage-clamp recordings on recombinant NMDA receptors expressed in Xenopus laevis oocytes. This strategy identified several novel modulators of NMDA receptor function, including the histamine H3 receptor antagonists clobenpropit and iodophenpropit, as well as the vanilloid receptor transient receptor potential cation channel, subfamily V, member 1 (TRPV1) antagonist capsazepine. These compounds are noncompetitive antagonists and the histamine H3 receptor ligand showed submicromolar potency at NR1/NR2B NMDA receptors, which raises the possibility that compounds can be developed that act with high potency on both glutamate and histamine receptor systems simultaneously. Furthermore, it is possible that some actions attributed to histamine H3 receptor inhibition in vivo may also involve NMDA receptor antagonism.

  14. Straub tail reaction in mice treated with σ(1) receptor antagonist in combination with methamphetamine.

    PubMed

    Kitanaka, Junichi; Kitanaka, Nobue; Hall, F Scott; Uhl, George R; Tanaka, Koh-Ichi; Nishiyama, Nobuyoshi; Takemura, Motohiko

    2012-10-30

    Straub tail reaction (STR) was observed in male ddY mice after simultaneous administration with BMY 14802 (a non-specific σ receptor antagonist) and methamphetamine (METH). The intensity and duration of STR depended on the dose of BMY 14802. The tail reaction was inhibited completely by (+)-SKF 10,047 (a putative σ(1) receptor agonist) and partially by PB 28 (a putative σ(2) receptor agonist). The STR was mimicked in mice treated with BD 1047 (a putative σ(1) receptor antagonist), but not SM-21, a putative σ(2) receptor antagonist, in combination with METH. STR evoked with BD 1047 plus METH was inhibited by (+)-SKF 10,047. STR induced by BMY 14802 and METH was abolished by naloxone (a relatively non-selective opioid receptor antagonist) or U-50,488H (a selective κ-agonist), suggesting that the STR may be mediated by activation of opioid receptor system.

  15. Interfering with mineralocorticoid receptor activation: the past, present, and future

    PubMed Central

    2014-01-01

    Aldosterone is a potent mineralocorticoid produced by the adrenal gland. Aldosterone binds to and activates the mineralocorticoid receptor (MR) in a plethora of tissues, but the cardiovascular actions of aldosterone are of primary interest clinically. Although MR antagonists were developed as antihypertensive agents, they are now considered to be important therapeutic options for patients with heart failure. Specifically, blocking only the MR has proven to be a difficult task because of its similarity to other steroid receptors, including the androgen and progesterone receptors. This lack of specificity caused the use of the first-generation mineralocorticoid receptor antagonists to be fraught with difficulty because of the side effects produced by drug administration. However, in recent years, several advances have been made that could potentially increase the clinical use of agents that inhibit the actions of aldosterone. These will be discussed here along with some examples of the beneficial effects of these new therapeutic agents. PMID:25165560

  16. Dihydromorphine-peptide hybrids with delta receptor agonistic and mu receptor antagonistic actions

    SciTech Connect

    Smith, C.B.; Medzihradsky, F.; Woods, J.H.

    1986-03-05

    The actions of two morphine derivatives with short peptide side chains were evaluated upon the contraction of the isolated mouse vas deferens and upon displacement of /sup 3/H-etorphine from rat brain membranes. NIH-9833 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-phenylalanyl-L-leucine ethyl ester HCl) was a potent agonist upon the vas deferens. Its EC50 for inhibition of the twitch was 1.2 +/- 0.1 nM. Both naltrexone (10/sup -7/ M) a relatively nonselective opioid antagonist, and ICI-174864 (10/sup -/' M) a highly selective delta receptor antagonist, blocked the actions of NIH-9833 which indicates that this drug is a delta receptor agonist. In contrast, NIH-9835 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-glycyl-L-phenylalanyl-L-leucine ethyl ester HCl), which differs from NIH-9835 by the presence of a single amino acid residue, was devoid of opioid agonistic activity but was a potent antagonist of the inhibitory actions on the vas deferens of morphine and sufentanil. NIH-9833 and NIH-9835 were potent displacers of /sup 3/H-etorphine from rat cerebral membranes with EC50's of 0.58 nM and 1.7 nM, respectively. The observation that addition of a single glycyl group changes a dihydromorphine-peptide analog from a potent delta receptor agonist to an equally potent mu receptor antagonist suggests that the two receptor sites might be structurally quite similar.

  17. Inhibition of radiation-induced polyuria by histamine receptor antagonists

    SciTech Connect

    Donlon, M.A.; Melia, J.A.; Helgeson, E.A.; Wolfe, W.W.

    1986-03-01

    In previous studies the authors have demonstrated that gamma radiation results in polyuria, which is preceded by polydypsia. This suggests that the increased thirst elicited by radiation causes increased urinary volume (UV). Histamine, which is released following radiation exposure, also elicits drinking by nonirradiated rats when administered exogenously. In this study the authors have investigated both the role of water deprivation and the effect of histamine receptor antagonists (HRA) on radiation-induced polyuria. Sprague-Dawley rats were housed individually in metabolic cages. Water was allowed ad libitum except in deprivation experiments where water was removed for 24 hr immediately following radiation. Cimetidine (CIM), an H2 HRA, and dexbromopheniramine (DXB), an H1 HRA, were administered i.p. (16 and 1 mg/kg, respectively) 30 min prior to irradiation (950 rads from a cobalt source). UV was determined at 24-hr intervals for 3 days preceding irradiation and 24 hr postirradiation. UV in DXB treated rats was significantly reduced 24 hr postirradiation (CON = 427 +/- 54%; DXB = 247 +/- 39% of preirradiated CON) compared to postirradiation control values. CIM did not affect postirradiation UV. These data suggest that radiation-induced polyuria is caused by polydypsia which is, in part, mediated by histamine induced by an H1 receptor.

  18. Vasopressin receptor antagonists and their role in clinical medicine

    PubMed Central

    Narayen, Girish; Mandal, Surya Narayan

    2012-01-01

    Hyponatremia is the most common electrolyte abnormality in hospitalized patients. Its treatment is based not only on extracellular fluid volume status of patients but also on its pathogenetic mechanisms. Conventional treatment of hyponatremia like fluid restriction, which is useful in euvolemic and hypervolemic hyponatremia, has very poor patient compliance over long term. Vasopressin receptor antagonists (Vaptans) are a new group of nonpeptide drugs which have been used in various clinical conditions with limited success. Whereas conivaptan is to be administered intravenously, the other vaptans like tolvaptan, lixivaptan, and satavaptan are effective as oral medication. They produce aquaresis by their action on vasopressin type 2 (V2R) receptors in the collecting duct and thus increase solute free water excretion. Vaptans are being used as an alternative to fluid restriction in euvolemic and hypervolemic hyponatremic patients. Efficacy of vaptans is now well accepted for management of correction of hyponatremia over a short period. However, its efficacy in improving the long-term morbidity and mortality in patients with chronic hyponatremia due to cirrhosis and heart failure is yet to be established. Vaptans have not become the mainstay treatment of hyponatremia yet. PMID:22470853

  19. Histamine and histamine receptor antagonists in cancer biology.

    PubMed

    Blaya, Bruno; Nicolau-Galmés, Francesca; Jangi, Shawkat M; Ortega-Martínez, Idoia; Alonso-Tejerina, Erika; Burgos-Bretones, Juan; Pérez-Yarza, Gorka; Asumendi, Aintzane; Boyano, María D

    2010-07-01

    Histamine has been demonstrated to be involved in cell proliferation, embryonic development, and tumour growth. These various biological effects are mediated through the activation of specific histamine receptors (H1, H2, H3, and H4) that differ in their tissue expression patterns and functions. Although many in vitro and in vivo studies of the modulatory roles of histamine in tumour development and metastasis have been reported, the effect of histamine in the progression of some types of tumours remains controversial; however, recent findings on the role of histamine in the immune system have shed new light on this question. This review focuses on the recent advances in understanding the roles of histamine and its receptors in tumour biology. We report our recent observations of the anti-tumoural effect of H1 histamine antagonists on experimental and human melanomas. We have found that in spite of exogenous histamine stimulated human melanoma cell proliferation, clonogenic ability and migration activity in a dose-dependent manner, the melanoma tumour growth was not modulated by in vivo histamine treatment. On the contrary, terfenadine-treatment in vitro induced melanoma cell death by apoptosis and in vivo terfenadine treatment significantly inhibited tumour growth in murine models. These observations increase our understanding of cancer biology and may inspire novel anticancer therapeutic strategies.

  20. Use of Enterally Delivered Angiotensin II Type Ia Receptor Antagonists to Reduce the Severity of Colitis

    PubMed Central

    Okawada, Manabu; Koga, Hiroyuki; Larsen, Scott D.; Showalter, Hollis D.; Turbiak, Anjanette J.; Jin, Xiaohong; Lucas, Peter C.; Lipka, Elke; Hillfinger, John; Kim, Jae Seung

    2011-01-01

    Background Renin-angiotensin system blockade reduces inflammation in several organ systems. Having found a fourfold increase in angiotensin II type Ia receptor expression in a dextran sodium sulfate colitis model, we targeted blockade with angiotensin II type Ia receptor antagonists to prevent colitis development. Because hypotension is a major complication of angiotensin II type Ia receptor antagonists use, we hypothesized that use of angiotensin II type Ia receptor antagonists compounds which lack cell membrane permeability, and thus enteric absorption, would allow for direct enteral delivery at far higher concentrations than would be tolerated systemically, yet retain efficacy. Methods Based on the structure of the angiotensin II type Ia receptor antagonist losartan, deschloro-losartan was synthesized, which has extremely poor cell membrane permeability. Angiotensin II type Ia receptor antagonist efficacy was evaluated by determining the ability to block NF-κB activation in vitro. Dextran sodium sulfate colitis was induced in mice and angiotensin II type Ia receptor antagonist efficacy delivered transanally was assessed. Results In vitro, deschloro-losartan demonstrated near equal angiotensin II type Ia receptor blockade compared to losartan as well as another angiotensin II type Ia receptor antagonist, candesartan. In the dextran sodium sulfate model, each compound significantly improved clinical and histologic scores and epithelial cell apoptosis. Abundance of TNF-α, IL-1β, and IL6 mRNA were significantly decreased with each compound. In vitro and in vivo intestinal drug absorption, as well as measures of blood pressure and mucosal and colonic blood flow, showed significantly lower uptake of deschloro-losartan compared to losartan and candesartan. Conclusions This study demonstrated efficacy of high-dose angiotensin II type Ia receptor antagonists in this colitis model. We postulate that a specially designed angiotensin II type Ia receptor antagonist with

  1. SFE/SFHTA/AFCE consensus on primary aldosteronism, part 7: Medical treatment of primary aldosteronism.

    PubMed

    Pechère-Bertschi, Antoinette; Herpin, Daniel; Lefebvre, Hervé

    2016-07-01

    Spironolactone, which is a potent mineralocorticoid receptor antagonist, represents the first line medical treatment of primary aldosteronism (PA). As spironolactone is also an antagonist of the androgen and progesterone receptor, it may present side effects, especially in male patients. In case of intolerance to spironolactone, amiloride may be used to control hypokaliemia and we suggest that eplerenone, which is a more selective but less powerful antagonist of the mineralocorticoid receptor, be used in case of intolerance to spironolactone and insufficient control of hypertension by amiloride. Specific calcic inhibitors and thiazide diuretics may be used as second or third line therapy. Medical treatment of bilateral forms of PA seem to be as efficient as surgical treatment of lateralized PA for the control of hypertension and the prevention of cardiovascular and renal morbidities. This allows to propose medical treatment of PA to patients with lateralized forms of PA who refuse surgery or to patients with PA who do not want to be explored by adrenal venous sampling to determine whether they have a bilateral or lateralized form.

  2. Anticonvulsive effect of nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Kuder, Kamil; Subramanian, Dhanasekaran; Shafiullah, Mohamed; Stark, Holger; Lażewska, Dorota; Adem, Abdu; Kieć-Kononowicz, Katarzyna

    2014-06-01

    To determine the potential of histamine H3 receptor (H3R) ligands as new antiepileptic drugs (AEDs), aromatic ether, and diether derivatives (1-12) belonging to the nonimidazole class of ligands, with high in-vitro binding affinity at human H3R, were tested for their in-vivo anticonvulsive activity in the maximal electroshock (MES)-induced and pentylenetetrazole (PTZ)-kindled seizure models in rats. The anticonvulsive effects of a systemic injection of 1-12 on MES-induced and PTZ-kindled seizures were evaluated against the reference AED phenytoin (PHT) and the structurally related H3R antagonist/inverse agonist pitolisant (PIT). Among the most promising ligands 2, 4, 5, and 11, there was a significant and dose-dependent reduction in the duration of tonic hind limb extension (THLE) in MES-induced seizure subsequent to administration of 4 and 5 [(5, 10, and 15 mg/kg, intraperitoneally (i.p.)]. The protective effects observed for the 1-(3-(3-(4-chlorophenyl)propoxy)propyl)-3-methylpiperidine derivative 11 at 10 mg/kg, i.p. were significantly greater than those of PIT, and were reversed by pretreatment with the central nervous system penetrant H1R antagonist pyrilamine (PYR) (10 mg/kg). Moreover, the protective action of the reference AED PHT, at a dose of 5 mg/kg (without considerable protection in the MES model), was significantly augmented when coadministered with derivative 11 (5 mg/kg, i.p.). Surprisingly, pretreatment with derivative 7 (10 mg/kg, i.p.), an ethylphenoxyhexyl-piperidine derivative without considerable protection in the MES model, potently altered PTZ-kindled seizure, significantly prolonged myoclonic latency time, and clearly shortened the total seizure time when compared with control, PHT, and PIT. These interesting results highlight the potential of H3R ligands as new AEDs or as adjuvants to available AED therapeutics.

  3. Heterocyclic 1,7-disubstituted indole sulfonamides are potent and selective human EP3 receptor antagonists.

    PubMed

    Hategan, Georgeta; Polozov, Alexandre M; Zeller, Wayne; Cao, Hua; Mishra, Rama K; Kiselyov, Alex S; Ramirez, Jose; Halldorsdottir, Gudrún; Andrésson, Thornorkell; Gurney, Mark E; Singh, Jasbir

    2009-12-01

    We have developed a pharmacophore model for the EP(3) receptor antagonists based on its endogenous ligand PGE(2). This ligand-based design yielded a series of novel peri-substituted [4.3.0] bicyclic aromatics featuring 1-alklyaryl 7-heterocyclic sulfonamide substituents. The synthesized molecules are potent antagonists of human EP(3) receptor in vitro and show inhibition of rat platelets aggregation. Optimized derivatives display high selectivity over IP, FP, and other EP receptor panels.

  4. Mechanisms of Radiosensitization by the Neurotensin Receptor Antagonist SR48692 in Prostate Cancer Models

    DTIC Science & Technology

    2009-04-01

    Neurotensin Receptor Antagonist SR48692 in Prostate Cancer Models PRINCIPAL INVESTIGATOR: Jaroslaw Dziegielewski, Ph.D...Receptor Antagonist 5a. CONTRACT NUMBER SR48692 in Prostate Cancer Models 5b. GRANT NUMBER W81XWH-08-1-0114 5c. PROGRAM ELEMENT NUMBER 6...neurotensin receptor by SR48692 drug could sensitize cancer cells to radiation. SR48692 activity was measured in PC3, C42 and LNCaP prostate cancer

  5. The effects of histamine H3-receptor antagonists on amygdaloid kindled seizures in rats.

    PubMed

    Kakinoki, H; Ishizawa, K; Fukunaga, M; Fujii, Y; Kamei, C

    1998-07-15

    The effects of histamine H3-receptor antagonists, thioperamide, and clobenpropit on amygdaloid kindled seizures were investigated in rats. Both intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) injections of H3-antagonists resulted in a dose-related inhibition of amygdaloid kindled seizures. An inhibition induced by thioperamide was antagonized by an H3-agonist [(R)-alpha-methylhistamine] and H1-antagonists (diphenhydramine and chlorpheniramine). On the other hand, an H2-antagonist (cimetidine and ranitidine) caused no antagonistic effect. Metoprine, an inhibitor of N-methyltransferase was also effective in inhibiting amygdaloid kindled seizure, and this effect was augmented by thioperamide treatment.

  6. Development of selective agonists and antagonists of P2Y receptors

    PubMed Central

    Ivanov, Andrei A.; de Castro, Sonia; Harden, T. Kendall; Ko, Hyojin

    2008-01-01

    Although elucidation of the medicinal chemistry of agonists and antagonists of the P2Y receptors has lagged behind that of many other members of group A G protein-coupled receptors, detailed qualitative and quantitative structure–activity relationships (SARs) were recently constructed for several of the subtypes. Agonists selective for P2Y1, P2Y2, and P2Y6 receptors and nucleotide antagonists selective for P2Y1 and P2Y12 receptors are now known. Selective nonnucleotide antagonists were reported for P2Y1, P2Y2, P2Y6, P2Y11, P2Y12, and P2Y13 receptors. At the P2Y1 and P2Y12 receptors, nucleotide agonists (5′-diphosphate derivatives) were converted into antagonists of nanomolar affinity by altering the phosphate moieties, with a focus particularly on the ribose conformation and substitution pattern. Nucleotide analogues with conformationally constrained ribose-like rings were introduced as selective receptor probes for P2Y1 and P2Y6 receptors. Screening chemically diverse compound libraries has begun to yield new lead compounds for the development of P2Y receptor antagonists, such as competitive P2Y12 receptor antagonists with antithrombotic activity. Selective agonists for the P2Y4, P2Y11, and P2Y13 receptors and selective antagonists for P2Y4 and P2Y14 receptors have not yet been identified. The P2Y14 receptor appears to be the most restrictive of the class with respect to modification of the nucleobase, ribose, and phosphate moieties. The continuing process of ligand design for the P2Y receptors will aid in the identification of new clinical targets. PMID:18600475

  7. Mineralcorticoid antagonists in heart failure.

    PubMed

    D'Elia, Emilia; Krum, Henry

    2014-10-01

    Mineralocorticoid receptor antagonists (MRAs) have become mandated therapy in patients with reduced ejection fraction (systolic) heart failure (HF) across all symptom classes. These agents should also be prescribed in the early post-myocardial infarction setting in those with reduced ejection fraction and either HF symptoms or diabetes. This article explores the pathophysiological role of aldosterone, an endogenous ligand for the mineralcorticoid receptor (MR), and summarizes the clinical data supporting guideline recommendations for these agents in systolic HF. The use of MRAs in novel areas beyond systolic HF ejection is also explored. Finally, the current status of newer agents will be examined.

  8. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%-80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  9. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists

    PubMed Central

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%–80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  10. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

    PubMed

    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

  11. Peripheral 5-HT2-like receptors. Can they be classified with the available antagonists?

    PubMed Central

    Leff, P.; Martin, G. R.

    1986-01-01

    Interactions between 5-hydroxytryptamine (5-HT) and the so-called 5-HT2 receptor antagonists ketanserin, spiperone, trazodone and methysergide were studied in isolated preparations of the rabbit aorta, rat jugular vein, and rat caudal artery. Trazodone and spiperone were apparently simple competitive antagonists since they produced antagonism that was surmountable over the concentration range studied and, in each tissue, their apparent affinity appeared to be independent of the antagonist concentration. Furthermore, concentration-ratios obtained with the two antagonists in combination suggested that antagonism was additive, implying mutual competition with a single population of 5-HT receptors. Ketanserin was a non-surmountable antagonist of 5-HT in the rat caudal artery and methysergide demonstrated surmountable, competitive antagonism only in the rabbit aorta. Antagonist dissociation constants estimated for apparently competitive interactions showed that ketanserin, spiperone and trazodone expressed affinities which differed according to the tissue used. In the case of trazodone, affinity estimates differed by as much as 12 fold. These discrepancies were independent of the 5-HT receptor agonist used and could not be attributed to an inadequate equilibration of the antagonist. These results can be interpreted in two ways: either the receptors in the different tissues are heterogeneous or the antagonists used here must be considered as unreliable probes for the classification of 5-HT2-like receptors. PMID:2943354

  12. Side Effects of Leukotriene Receptor Antagonists in Asthmatic Children

    PubMed Central

    Erdem, Semiha Bahceci; Nacaroglu, Hikmet Tekin; Unsal Karkiner, Canan Sule; Gunay, Ilker; Can, Demet

    2015-01-01

    Background: Leukotriene receptor antagonists (LTRAs) are drugs which have been widely used more than ten years. As the use of LTRAs increases, our knowledge with respect to their side effects increases as well. Objectives: The objective of our study was to evaluat the observed side effects of LTRAs used in patients with astma. Patients and Methods: 1024 patients treated only with LTRAs owing to asthma or early wheezing were included in the study for a five-year period. The observed side effects of LTRAs in these patients were retrospectively investigated. The side effects were divided into two parts as psychiatric and non-psychiatric. Results: Among the 1024 cases included in the study, 67.5% of the patients out of 41 with side effects were male, 32.5% were female and the average age was 6.5 years. The rate of patients with asthma was 63.41% and 36.58% of the patients had early wheezing. It was determined that sex, age and diagnosis (early wheezing or asthma) of the patients were ineffective in the emergence of side effects. The average period for the emergence of side effects was the first month. It was observed that hyperactivity was the most frequently observed psychiatric side effect and that abdominal pain was the non-psychiatric side effect. Conclusions: The side effects of LTRAs were common in children. Therefore, patients must be informed at the beginning of the treatment and they must be evaluated at certain intervals. PMID:26495098

  13. Effects of cholecystokinin receptor antagonist loxiglumide on rat exocrine pancreas.

    PubMed

    Nakano, S; Tachibana, I; Otsuki, M

    1994-07-01

    Effects of long-term administration of the cholecystokinin receptor antagonist loxiglumide on exocrine pancreas were studied in adult rats. Plasma concentrations of loxiglumide at 8 h after a single subcutaneous injection of 50 mg/kg body weight of loxiglumide were 3.2 +/- 0.8 microgram/ml, which were comparable to those at 12 h after oral administration of the same dose (3.7 +/- 0.9 microgram/ml). Eight hours' prior subcutaneous injection of loxiglumide (50 mg/kg body weight) significantly suppressed pancreatic exocrine secretion stimulated by an intravenous bolus injection of 50 ng/kg body weight caerulein compared with the control rats. Based on these results, in the first experiment, loxiglumide at a dose of 50 mg/kg body weight was given subcutaneously three times a day (low dose) for 6 days to adult rats fed a standard laboratory diet. Low dose of loxiglumide significantly decreased pancreatic wet weight (-14%) and pancreatic contents of protein (-26%), trypsin (-38%), and lipase (-68%), while having no significant effect on pancreatic contents of DNA and amylase. In the second experiment, three times higher dose of loxiglumide (150 mg/kg body weight) was given by an orogastric tube twice daily for 6 days. High dose of loxiglumide significantly decreased pancreatic weight (-11%) and contents of protein (-20%) and DNA (-22%), whereas it significantly increased amylase (+92%) and trypsin content (+20%).(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Alvimopan: a peripherally acting mu-opioid receptor antagonist.

    PubMed

    Leslie, John B

    2007-09-01

    Postoperative ileus (POI), a transient cessation of coordinated bowel motility after surgery, is an important factor in extending the length of hospital stay. The etiology of POI is multifactorial, and related to both the surgical and anesthetic pathways chosen. Additionally, opioids used to manage non-cancer-related and cancer-related chronic pain may also decrease gastrointestinal (GI) motility resulting in opioid-induced bowel dysfunction (OBD). Postoperative ileus has been associated with prolonged hospital stay and readmission, and thus may increase the overall hospital costs per patient with POI. Alvimopan, a peripherally acting mu-opioid receptor antagonist, accelerated time to GI recovery and reduced postoperative hospital length of stay in phase III POI clinical trials and improved symptoms of OBD compared with placebo in phase II/III clinical trials. The U.S. Food and Drug Administration is currently evaluating alvimopan for the management of POI after bowel resection. Alvimopan may provide clinically meaningful benefits to patients and may lower the economic burden of POI to the healthcare system.

  15. Applicability of DPI formulations for novel neurokinin receptor antagonist.

    PubMed

    Kumon, M; Yabe, Y; Kasuya, Y; Suzuki, M; Kusai, A; Yonemochi, E; Terada, K

    2008-05-22

    A novel triple neurokinin receptor antagonist (TNRA) could have pharmaceutical efficacy for asthma and/or chronic obstructive pulmonary disease. TNRA is potentially developed as inhalation medicine. The aim of this investigation was to evaluate the applicability of dry powder inhaler (DPI) formulation for TNRA. DPI formulation containing lactose was used for this feasibility study. Mechanofusion process for surface modification was applied on lactose particles to prepare four different DPI formulations. The mixture of TNRA and lactose was administered to rats intratracheally using an insufflator. The deposition pattern and blood concentration profile of TNRA were evaluated. Although there was no significant difference in deposition on deep lungs between the four formulations, DPI formulations containing mechanofusion-processed lactose showed longer T(max) and t(1/2) and higher AUC(0-infinity) and MRT compared to that containing intact lactose. On the other hand, the contact angle measurement showed that the mechanofusion process decreased the polar part of the surface energy of the lactose. Therefore, the prolongation of the wetting of the formulated powder mixture seemed to delay the dissolution of TNRA deposited in respiratory tract. It was concluded that DPI formulation containing mechanofusion-processed lactose could be suitable for inhalation of TNRA.

  16. Receptors and Channels Targeted by Synthetic Cannabinoid Receptor Agonists and Antagonists

    PubMed Central

    Pertwee, R.G.

    2010-01-01

    It is widely accepted that non-endogenous compounds that target CB1 and/or CB2 receptors possess therapeutic potential for the clinical management of an ever growing number of disorders. Just a few of these disorders are already treated with Δ9-tetrahydrocannabinol or nabilone, both CB1/CB2 receptor agonists, and there is now considerable interest in expanding the clinical applications of such agonists and also in exploiting CB2-selective agonists, peripherally restricted CB1/CB2 receptor agonists and CB1/CB2 antagonists and inverse agonists as medicines. Already, numerous cannabinoid receptor ligands have been developed and their interactions with CB1 and CB2 receptors well characterized. This review describes what is currently known about the ability of such compounds to bind to, activate, inhibit or block non-CB1, non-CB2 G protein-coupled receptors such as GPR55, transmitter gated channels, ion channels and nuclear receptors in an orthosteric or allosteric manner. It begins with a brief description of how each of these ligands interacts with CB1 and/or CB2 receptors. PMID:20166927

  17. Tamoxifen resistant breast cancer: coregulators determine the direction of transcription by antagonist-occupied steroid receptors.

    PubMed

    Takimoto, G S; Graham, J D; Jackson, T A; Tung, L; Powell, R L; Horwitz, L D; Horwitz, K B

    1999-01-01

    Pharmacological antagonists of steroid receptor action had been thought to exert their effects by a passive mechanism driven principally by the ability of the antagonist to compete with agonist for the ligand binding site. However, recent analyses of antagonist-occupied receptor function suggest a more complex picture. Antagonists can be subdivided into two groups, type I, or pure antagonists, and type II, or mixed antagonists that can have variable transcriptional activity based upon differential dimerization and DNA binding properties. This led us to propose that receptor antagonism may not simply be a passive competition for the ligand binding site, but may, in some cases, involve active recruitment of corepressor or coactivator proteins to produce a mixed transcriptional phenotype. We used a yeast two-hybrid screen to identify proteins that interact specifically with antagonist-occupied receptors. Two proteins have been characterized: L7/SPA, a ribosome-associated protein that is localized in both the cytoplasm and nucleus, but with no known extranucleolar nuclear function; and hN-CoR, the human homolog of the mouse thyroid receptor corepressor mN-CoR. In in vivo transcription assays we show that L7/SPA enhances the partial agonist activity of type II mixed antagonists, and that N-CoR and the related corepressor, SMRT, suppresses it. The coregulators do not affect agonists or pure antagonists. Moreover, the net agonist activity seen with mixed antagonists is a function of the ratio of coactivator to corepressor. Based upon these results, we proposed that in breast tumors the inappropriate agonist activity seen with therapeutic antagonists such as tamoxifen is responsible for the hormone-resistant state. To confirm this, we are quantitating coactivator/corepressor ratios in breast tumor cells lines and clinical breast cancers. Results should provide new insights into the mechanisms underlying the progression of breast cancer to hormone resistance, and may

  18. CGS 8216: receptor binding characteristics of a potent benzodiazepine antagonist.

    PubMed

    Czernik, A J; Petrack, B; Kalinsky, H J; Psychoyos, S; Cash, W D; Tsai, C; Rinehart, R K; Granat, F R; Lovell, R A; Brundish, D E; Wade, R

    1982-01-25

    CGS 8216 is a novel nonbenzodiazepine that inhibited 3H-flunitrazepam (3H-FLU) binding to rat synaptosomal membranes in vitro at subnanomolar concentrations. It prevented the in vivo labeling of brain benzodiazepine receptors by 3H-FLU with the same potency as diazepam when given orally to mice. Pharmacologic tests showed that it was devoid of benzodiazepine-like activity but it antagonized the actions of diazepam in these tests. It did not interact with alpha- or beta- adrenergic, H1-histaminergic or GABA receptors but it inhibited adenosine-activation of cyclic AMP formation. Studies with 3H-CGS 8216 demonstrated that it bound specifically and with high affinity to rat forebrain membranes and was displaced by drugs with an order of potencies similar to that observed when 3H-diazepam and 3H-FLU were used as radioligands. The regional distribution of 3H-CGS 8216 binding sites in the brain was also similar to that of 3H-FLU. Dissociation of 3H-CGS 8216 binding was slow at 0 degrees C but increased with temperature and was almost complete within 1 min at 37 degrees C. Scatchard analyses were linear, yielding KD values of 0.044, 0.11 and 0.18 nM at 0, 25 and 37 degrees C, respectively; the Bmax value did not change appreciably with temperature and was approximately 1000 fmoles/mg protein. Using 3H-FLU, the value for Bmax as well as for the KD increased with temperature. The total number of binding sites determined for 3H-FLU was greater than that for 3H-CGS 8216 at each temperature. CGS 8216 exhibited mixed-type inhibition of 3H-FLU binding. GABA did not stimulate 3H-CGS 8216 binding whereas it enhanced 3H-FLU binding. CGS 8216 may be a useful ligand for probing the antagonist properties of the benzodiazepine receptor and is likely to exhibit interesting therapeutic effects.

  19. The NK1 receptor antagonist L822429 reduces heroin reinforcement.

    PubMed

    Barbier, Estelle; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Juergens, Nathan; Park, Paula E; Misra, Kaushik K; Cheng, Kejun; Rice, Kenner C; Schank, Jesse; Schulteis, Gery; Koob, George F; Heilig, Markus

    2013-05-01

    Genetic deletion of the neurokinin 1 receptor (NK1R) has been shown to decrease the reinforcing properties of opioids, but it is unknown whether pharmacological NK1R blockade has the same effect. Here, we examined the effect of L822429, a rat-specific NK1R antagonist, on the reinforcing properties of heroin in rats on short (1 h: ShA) or long (12 h: LgA) access to intravenous heroin self-administration. ShA produces heroin self-administration rates that are stable over time, whereas LgA leads to an escalation of heroin intake thought to model important dependence-related aspects of addiction. L822429 reduced heroin self-administration and the motivation to consume heroin, measured using a progressive-ratio schedule, in both ShA and LgA rats. L822429 also decreased anxiety-like behavior in both groups, measured on the elevated plus maze, but did not affect mechanical hypersensitivity observed in LgA rats. Expression of TacR1 (the gene encoding NK1R) was decreased in reward- and stress-related brain areas both in ShA and LgA rats compared with heroin-naïve rats, but did not differ between the two heroin-experienced groups. In contrast, passive exposure to heroin produced increases in TacR1 expression in the prefrontal cortex and nucleus accumbens. Taken together, these results show that pharmacological NK1R blockade attenuates heroin reinforcement. The observation that animals with ShA and LgA to heroin were similarly affected by L822429 indicates that the SP/NK1R system is not specifically involved in neuroadaptations that underlie escalation resulting from LgA self-administration. Instead, the NK1R antagonist appears to attenuate acute, positively reinforcing properties of heroin and may be useful as an adjunct to relapse prevention in detoxified opioid-dependent subjects.

  20. Transition strategies from cangrelor to oral platelet P2Y12 receptor antagonists.

    PubMed

    Schneider, David J

    2016-01-01

    Cangrelor is the first parenteral antagonist of the platelet P2Y12 receptor. This direct-acting antagonist of the platelet P2Y12 receptor should be considered an adjunct to a percutaneous coronary intervention in patients who have not been adequately pretreated with platelet P2Y12 receptor antagonists at the time of the procedure. The use of cangrelor requires transition to an oral platelet P2Y12 receptor antagonist. Transition strategies have been developed on the basis of pharmacologic characteristics of platelet P2Y12 receptor antagonists, results of pharmacodynamic studies, and results from clinical trials. Cangrelor blocks the binding to the platelet P2Y12 receptor of the active metabolite of the thienopyridines, clopidogrel and prasugrel. The active metabolite of thienopyridines is present in blood for a short interval after administration. For this reason, clopidogrel should be administered after cangrelor is stopped. Prasugrel can be administered at the end of the cangrelor infusion or up to 30 min before cangrelor is stopped. Ticagrelor is also a reversible direct-acting antagonist of the platelet P2Y12 receptor. Because there is no interaction between ticagrelor and cangrelor, ticagrelor can be administered before or during the infusion of cangrelor.

  1. Anti-idiotypic antibody: A new strategy for the development of a growth hormone receptor antagonist.

    PubMed

    Lan, Hainan; Zheng, Xin; Khan, Muhammad Akram; Li, Steven

    2015-11-01

    In general, traditional growth hormone receptor antagonist can be divided into two major classes: growth hormone (GH) analogues and anti-growth hormone receptor (GHR) antibodies. Herein, we tried to explore a new class of growth hormone receptor (GHR) antagonist that may have potential advantages over the traditional antagonists. For this, we developed a monoclonal anti-idiotypic antibody growth hormone, termed CG-86. A series of experiments were conducted to characterize and evaluate this antibody, and the results from a competitive receptor-binding assay, Enzyme Linked Immunosorbent Assays (ELISA) and epitope mapping demonstrate that CG-86 behaved as a typical Ab2β. Next, we examined its antagonistic activity using in vitro cell models, and the results showed that CG-86 could effectively inhibit growth hormone receptor-mediated signalling and effectively inhibit growth hormone-induced Ba/F3-GHR638 proliferation. In summary, these studies show that an anti-idiotypic antibody (CG-86) has promise as a novel growth hormone receptor antagonist. Furthermore, the current findings also suggest that anti-idiotypic antibody may represent a novel strategy to produce a new class of growth hormone receptor antagonist, and this strategy may be applied with other cytokines or growth factors.

  2. Sphingosine-1-Phosphate Receptor-2 Antagonists: Therapeutic Potential and Potential Risks

    PubMed Central

    Blankenbach, Kira V.; Schwalm, Stephanie; Pfeilschifter, Josef; Meyer zu Heringdorf, Dagmar

    2016-01-01

    The sphingosine-1-phosphate (S1P) signaling system with its specific G-protein-coupled S1P receptors, the enzymes of S1P metabolism and the S1P transporters, offers a multitude of promising targets for drug development. Until today, drug development in this area has nearly exclusively focused on (functional) antagonists at the S1P1 receptor, which cause a unique phenotype of immunomodulation. Accordingly, the first-in class S1P1 receptor modulator, fingolimod, has been approved for the treatment of relapsing-remitting multiple sclerosis, and novel S1P1 receptor (functional) antagonists are being developed for autoimmune and inflammatory diseases such as psoriasis, inflammatory bowel disease, lupus erythematodes, or polymyositis. Besides the S1P1 receptor, also S1P2 and S1P3 are widely expressed and regulate many diverse functions throughout the body. The S1P2 receptor, in particular, often exerts cellular functions which are opposed to the functions of the S1P1 receptor. As a consequence, antagonists at the S1P2 receptor have the potential to be useful in a contrasting context and different areas of indication compared to S1P1 antagonists. The present review will focus on the therapeutic potential of S1P2 receptor antagonists and discuss their opportunities as well as their potential risks. Open questions and areas which require further investigations will be emphasized in particular. PMID:27445808

  3. An expedient route to a potent gastrin/CCK-B receptor antagonist (+)-AG-041R.

    PubMed

    Sato, Shigeki; Shibuya, Masatoshi; Kanoh, Naoki; Iwabuchi, Yoshiharu

    2009-10-02

    An enantiocontrolled synthesis of (+)-AG-041R (1), a potent gastrin/CCK-B receptor antagonist, has been achieved employing a chiral rhodium(II)-catalyzed, oxidative intramolecular aza-spiroannulation as the key step.

  4. Neuroprotection Profile of the High Affinity NMDA Receptor Antagonist Conantokin-G

    DTIC Science & Technology

    2002-01-01

    ABSTRACT Conantokin-G (Con-G or CGX-1007), a potent NR2B subunit selective NMDA receptor antagonist, was evaluated for its neuroprotective properties...protection against staurosporine-induced apoptotic injury (Pɘ.01, n = 12/group), which was linked to the NR2B subunit. For in vivo brain injury...CGX-1007), a potent NR2B subunit selective NMDA receptor antagonist, was evaluated for its neuroprotective properties in experimental models of

  5. The discovery of the benzazepine class of histamine H3 receptor antagonists.

    PubMed

    Wilson, David M; Apps, James; Bailey, Nicholas; Bamford, Mark J; Beresford, Isabel J; Briggs, Michael A; Calver, Andrew R; Crook, Barry; Davis, Robert P; Davis, Susannah; Dean, David K; Harris, Leanne; Heightman, Tom D; Panchal, Terry; Parr, Christopher A; Quashie, Nigel; Steadman, Jon G A; Schogger, Joanne; Sehmi, Sanjeet S; Stean, Tania O; Takle, Andrew K; Trail, Brenda K; White, Trevor; Witherington, Jason; Worby, Angela; Medhurst, Andrew D

    2013-12-15

    This Letter describes the discovery of a novel series of H3 receptor antagonists. The initial medicinal chemistry strategy focused on deconstructing and simplifying an early screening hit which rapidly led to the discovery of a novel series of H3 receptor antagonists based on the benzazepine core. Employing an H3 driven pharmacodynamic model, the series was then further optimised through to a lead compound that showed robust in vivo functional activity and possessed overall excellent developability properties.

  6. Update on leukotriene receptor antagonists in preschool children wheezing disorders

    PubMed Central

    2012-01-01

    Asthma is the most common chronic disease in young children. About 40% of all preschool children regularly wheeze during common cold infections. The heterogeneity of wheezing phenotypes early in life and various anatomical and emotional factors unique to young children present significant challenges in the clinical management of this problem. Anti-inflammatory therapy, mainly consisting of inhaled corticosteroids (ICS), is the cornerstone of asthma management. Since Leukotrienes (LTs) are chemical mediators of airway inflammation in asthma, the leukotriene receptor antagonists (LTRAs) are traditionally used as potent anti-inflammatory drugs in the long-term treatment of asthma in adults, adolescents, and school-age children. In particular, montelukast decreases airway inflammation, and has also a bronchoprotective effect. The main guidelines on asthma management have confirmed the clinical utility of LTRAs in children older than five years. In the present review we describe the most recent advances on the use of LTRAs in the treatment of preschool wheezing disorders. LTRAs are effective in young children with virus-induced wheeze and with multiple-trigger disease. Conflicting data do not allow to reach definitive conclusions on LTRAs efficacy in bronchiolitis or post-bronchiolitis wheeze, and in acute asthma. The excellent safety profile of montelukast and the possibility of oral administration, that entails better compliance from young children, represent the main strengths of its use in preschool children. Montelukast is a valid alternative to ICS especially in poorly compliant preschool children, or in subjects who show adverse effects related to long-term steroid therapy. PMID:22734451

  7. Discovery of antagonists of tick dopamine receptors via chemical library screening and comparative pharmacological analyses.

    PubMed

    Ejendal, Karin F K; Meyer, Jason M; Brust, Tarsis F; Avramova, Larisa V; Hill, Catherine A; Watts, Val J

    2012-11-01

    Ticks transmit a wide variety of disease causing pathogens to humans and animals. Considering the global health impact of tick-borne diseases, there is a pressing need to develop new methods for vector control. We are exploring arthropod dopamine receptors as novel targets for insecticide/acaricide development because of their integral roles in neurobiology. Herein, we developed a screening assay for dopamine receptor antagonists to further characterize the pharmacological properties of the two D₁-like dopamine receptors (Isdop1 and Isdop2) identified in the Lyme disease vector, Ixodes scapularis, and develop a screening assay for receptor antagonists. A cell-based, cyclic AMP luciferase reporter assay platform was implemented to screen the LOPAC(1280) small molecule library for Isdop2 receptor antagonists, representing the first reported chemical library screen for any tick G protein-coupled receptor. Screening resulted in the identification of 85 "hit" compounds with antagonist activity at the Isdop2 receptor. Eight of these chemistries were selected for confirmation assays using a direct measurement of cAMP, and the effects on both Isdop1 and Isdop2 were studied for comparison. Each of these eight compounds showed antagonistic activity at both Isdop1 and Isdop2, although differences were observed regarding their relative potencies. Furthermore, comparison of the pharmacological properties of the tick dopamine receptors with that of the AaDOP2 receptor from the yellow fever mosquito and the human dopamine D₁ receptor (hD₁) revealed species-specific pharmacological profiles of these receptors. Compounds influencing dopaminergic functioning, such as the dopamine receptor antagonists discovered here, may provide lead chemistries for discovery of novel acaricides useful for vector control

  8. The cannabinoid CB1 receptor antagonists rimonabant (SR141716) and AM251 directly potentiate GABAA receptors

    PubMed Central

    Baur, R; Gertsch, J; Sigel, E

    2012-01-01

    BACKGROUND AND PURPOSE Rimonabant (SR141716) and the structurally related AM251 are widely used in pharmacological experiments as selective cannabinoid receptor CB1 antagonists / inverse agonists. Concentrations of 0.5–10 µM are usually applied in in vitro experiments. We intended to show that these drugs did not act at GABAA receptors but found a significant positive allosteric modulation instead. EXPERIMENTAL APPROACH Recombinant GABAA receptors were expressed in Xenopus oocytes. Receptors were exposed to AM251 or rimonabant in the absence and presence of GABA. Standard electrophysiological techniques were used to monitor the elicited ionic currents. KEY RESULTS AM251 dose-dependently potentiated responses to 0.5 µM GABA at the recombinant α1β2γ2 GABAA receptor with an EC50 below 1 µM and a maximal potentiation of about eightfold. The Hill coefficient indicated that more than one binding site for AM251 was located in this receptor. Rimonabant had a lower affinity, but a fourfold higher efficacy. AM251 potentiated also currents mediated by α1β2, αxβ2γ2 (x = 2,3,5,6), α1β3γ2 and α4β2δ GABAA receptors, but not those mediated by α1β1γ2. Interestingly, the CB1 receptor antagonists LY320135 and O-2050 did not significantly affect α1β2γ2 GABAA receptor-mediated currents at concentrations of 1 µM. CONCLUSIONS AND IMPLICATIONS This study identified rimonabant and AM251 as positive allosteric modulators of GABAA receptors. Thus, potential GABAergic effects of commonly used concentrations of these compounds should be considered in in vitro experiments, especially at extrasynaptic sites where GABA concentrations are low. LINKED ARTICLES This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7 PMID:21470203

  9. Unsaturated phosphinic analogues of gamma-aminobutyric acid as GABA(C) receptor antagonists.

    PubMed

    Chebib, M; Vandenberg, R J; Froestl, W; Johnston, G A

    1997-06-25

    The phosphinic and methylphosphinic analogues of gamma-aminobutyric acid (GABA) are potent GABA(C) receptor antagonists but are even more potent as GABA(B) receptor agonists. Conformationally restricted unsaturated phosphinic and methylphosphinic analogues of GABA and some potent GABA(B) receptor phosphonoamino acid antagonists were tested on GABA(C) receptors in Xenopus oocytes expressing human retinal rho1 mRNA. 3-Aminopropyl-n-butyl-phosphinic acid (CGP36742), an orally active GABA(B) receptor antagonist, was found to be a moderately potent GABA(C) receptor antagonist (IC50 = 62 microM). The unsaturated methylphosphinic and phosphinic analogues of GABA were competitive antagonists of the GABA(C) receptors, the order of potency being [(E)-3-aminopropen-1-yl]methylphosphinic acid (CGP44530, IC50 = 5.53 microM) > [(E)-3-aminopropen-1-yl]phosphinic acid (CGP38593, IC50 = 7.68 microM) > [(Z)-3-aminopropen-1-yl]methylphosphinic acid (CGP70523, IC50 = 38.94 microM) > [(Z)-3-aminopropen-1-yl]phosphinic acid (CGP70522, IC50 > 100 microM). This order of potency differs from that reported for these compounds as GABA(B) receptor agonists, where the phosphinic acids are more potent than the corresponding methylphosphinic acids.

  10. Morphine in combination with metabotropic glutamate receptor antagonists on schedule-controlled responding and thermal nociception.

    PubMed

    Fischer, Bradford D; Zimmerman, Eric I; Picker, Mitchell J; Dykstra, Linda A

    2008-02-01

    The present study examined the interactive effects of morphine in combination with metabotropic glutamate (mGlu) receptor antagonists on schedule-controlled responding and thermal nociception. Drug interaction data were examined with isobolographic and dose-addition analysis. Morphine, the mGlu1 receptor antagonist JNJ16259685 [(3,4-dihydro-2H-pyrano-[2,3-b]quinolin-7-yl)-(cis-4-methoxycyclohexyl)-methanone], the mGlu5 receptor antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine hydrochloride], and the mGlu2/3 receptor antagonist LY341495 [(2S)-2-amino-2-[(1S,2S-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid] all decreased rates of schedule-controlled responding. JNJ16259685/morphine, MPEP/morphine, and LY341495/morphine mixtures produced additive effects on this endpoint. Morphine also produced dose-dependent antinociception in the assay of thermal nociception, whereas JNJ16259685, MPEP, and LY341495 failed to produce an effect. In this assay, JNJ16259685 and LY341495 potentiated the antinociceptive effects of morphine, whereas MPEP/morphine mixtures produced additive effects. These results suggest that an mGlu1 and an mGlu2/3 receptor antagonist, but not an mGlu5 receptor antagonist, selectively enhance the antinociceptive effects of morphine. In addition, these data confirm that the behavioral effects of drug mixtures depend on the endpoint under study.

  11. Aldosterone alters the participation of endothelial factors in noradrenaline vasoconstriction differently in resistance arteries from normotensive and hypertensive rats.

    PubMed

    Xavier, Fabiano E; Blanco-Rivero, Javier; Avendaño, María Soledad; Sastre, Esther; Yela, Rubén; Velázquez, Kyra; Salaíces, Mercedes; Balfagón, Gloria

    2011-03-11

    This study analyzed the effect of aldosterone (0.05mg/kg per day, 3 weeks) on vasoconstriction induced by noradrenaline in mesenteric resistance arteries from WKY rats and SHR. Contraction to noradrenaline was measured in mesenteric resistance arteries from untreated and aldosterone-treatedrats from both strains. Participation of nitric oxide (NO), superoxide anions, thromboxane A(2) (TxA(2)) and prostacyclin in this response was determined. 6-keto-prostaglandin (PG)F1alpha and thromboxane B(2) (TxB(2)) releases were determined by enzyme immunoassay. NO and superoxide anion release were also determined by fluorescence and chemiluminiscence, respectively. Aldosterone did not modify noradrenaline-induced contraction in either strain. In mesenteric resistance arteries from both aldosterone-treated groups, endothelium removal or preincubation with NO synthesis inhibitor L-NAME increased the noradrenaline-induced contraction, while incubation with the superoxide anion scavenger tempol decreased it. Preincubation with either the COX-1/2 or COX-2 inhibitor (indomethacin and NS-398, respectively) decreased the noradrenaline contraction in aldosterone-treated animals, while this response was not modified by COX-1 inhibitor SC-560. TxA(2) synthesis inhibitor (furegrelate), or TxA2 receptor antagonist (SQ 29 548) also decreased the noradrenaline contraction in aldosterone-treated animals. In untreated SHR, but not WKY rats, this response was increased by L-NAME, and reduced by tempol, indomethacin, NS-398 or SQ 29 548. Aldosterone treatment did not modify NO or TxB(2) release, but it did increase superoxide anion and 6-keto-PGF(1alpha) release in mesenteric resistance arteries from both strains. In conclusion, chronic aldosterone treatment reduces smooth muscle contraction to alpha-adrenergic stimuli, producing a new balance in the release of endothelium-derived prostanoids and NO.

  12. Effect of ghrelin receptor antagonist on meal patterns in cholecystokinin type 1 receptor null mice.

    PubMed

    Lee, Jennifer; Martin, Elizabeth; Paulino, Gabriel; de Lartigue, Guillaume; Raybould, Helen E

    2011-05-03

    Vagal afferent neurons (VAN) express the cholecystokinin (CCK) type 1 receptor (CCK₁R) and, as predicted by the role of CCK in inducing satiation, CCK₁R⁻/⁻ mice ingest larger and longer meals. However, after a short fast, CCK₁R⁻/⁻ mice ingesting high fat (HF) diets initiate feeding earlier than wild-type mice. We hypothesized that the increased drive to eat in CCK₁R⁻/⁻ mice eating HF diet is mediated by ghrelin, a gut peptide that stimulates food intake. The decrease in time to first meal, and the increase in meal size and duration in CCK₁R⁻/⁻ compared to wild-type mice ingesting high fat (HF) diet were reversed by administration of GHSR1a antagonist D-(Lys3)-GHRP-6 (p<0.05). Administration of the GHSR1a antagonist significantly increased expression of the neuropeptide cocaine and amphetamine-regulated transcript (CART) in VAN of HF-fed CCK₁R⁻/⁻ but not wild-type mice. Administration of the GHSR1a antagonist decreased neuronal activity measured by immunoreactivity for fos protein in the nucleus of the solitary tract (NTS) and the arcuate nucleus of both HF-fed wild-type and CCK₁R⁻/⁻ mice. The data show that hyperphagia in CCK₁R⁻/⁻ mice ingesting HF diet is reversed by blockade of the ghrelin receptor, suggesting that in the absence of the CCK₁R, there is an increased ghrelin-dependent drive to feed. The site of action of ghrelin receptors is unclear, but may involve an increase in expression of CART peptide in VAN in HF-fed CCK₁R⁻/⁻ mice.

  13. From Chemotherapy-Induced Emesis to Neuroprotection: Therapeutic Opportunities for 5-HT3 Receptor Antagonists.

    PubMed

    Fakhfouri, Gohar; Mousavizadeh, Kazem; Mehr, Sharam Ejtemaei; Dehpour, Ahmad Reza; Zirak, Mohammad Reza; Ghia, Jean-Eric; Rahimian, Reza

    2015-12-01

    5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to Aβ-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-α level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against Aβ-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-κB, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications.

  14. High antagonist potency of GT-2227 and GT-2331, new histamine H3 receptor antagonists, in two functional models.

    PubMed

    Tedford, C E; Hoffmann, M; Seyedi, N; Maruyama, R; Levi, R; Yates, S L; Ali, S M; Phillips, J G

    1998-06-26

    GT-2227 (4-(6-cyclohexylhex-cis-3-enyl)imidazole) and GT-2331 ((1R,2R)-4-(2-(5,5-dimethylhex-1-ynyl)cyclopropyl)imidazole) were developed as new potent histamine H3 receptor antagonists. The functional activity of these ligands on the histamine H3 receptor-mediated inhibition of neurogenic contraction of the guinea-pig jejunum and histamine H3 receptor-mediated inhibition of norepinephrine release from guinea-pig heart synaptosomes were investigated. GT-2227 and GT-2331 both antagonized the inhibitory effects of (R)-alpha-methylhistamine on the contraction induced by electrical field stimulation in the guinea-pig jejunum with pA2 values of 7.9+/-0.1 and 8.5+/-0.03, respectively. In addition, GT-2227 and GT-2331 antagonized the inhibition of norepinephrine release in cardiac synaptosomes by GT-2203 ((1R,2R)-trans-2-(1H-imidazol-4-yl)cyclopropylamine), a histamine H3 receptor agonist. The current results demonstrate the antagonist activity for both GT-2227 and GT-2331 in two functional assays for histamine H3 receptors.

  15. Mechanism of action of species-selective P2X7 receptor antagonists

    PubMed Central

    Michel, Anton D; Ng, Sin-Wei; Roman, Shilina; Clay, William C; Dean, David K; Walter, Daryl S

    2009-01-01

    Background and purpose: AZ11645373 and N-{2-methyl-5-[(1R, 5S)-9-oxa-3,7-diazabicyclo[3.3.1]non-3-ylcarbonyl]phenyl}-2-tricyclo[3.3.1.13,7]dec-1-ylacetamide hydrochloride (compound-22) are recently described P2X7 receptor antagonists. In this study we have further characterized these compounds to determine their mechanism of action and interaction with other species orthologues. Experimental approach: Antagonist effects at recombinant and chimeric P2X7 receptors were assessed by ethidium accumulation and radioligand-binding studies. Key results: AZ11645373 and compound-22 were confirmed as selective non-competitive antagonists of human or rat P2X7 receptors respectively. Both compounds were weak antagonists of the mouse and guinea-pig P2X7 receptors and, for each compound, their potency estimates at human and dog P2X7 receptors were similar. The potency of compound-22 was moderately temperature-dependent while that of AZ11645373 was not. The antagonist effects of both compounds were slowly reversible and were not prevented by decavanadate, suggesting that they were allosteric antagonists. Indeed, the compounds competed for binding sites labelled by an allosteric radio-labelled P2X7 receptor antagonist. The species selectivity of AZ11645373, but not compound-22, was influenced by the nature of the amino acid at position 95 of the P2X7 receptor. N2-(3,4-difluorophenyl)-N1-[2-methyl-5-(1-piperazinylmethyl)phenyl]glycinamide dihydrochloride, a positive allosteric modulator of the rat receptor, reduced the potency of compound-22 at the rat receptor but had little effect on the actions of AZ11645373. Conclusions: AZ11645373 and compound-22 are allosteric antagonists of human and rat P2X7 receptors respectively. The differential interaction of the two compounds with the receptor suggests there may be more than one allosteric regulatory site on the P2X7 receptor at which antagonists can bind and affect receptor function. PMID:19309360

  16. NOP Receptor Mediates Anti-analgesia Induced by Agonist-Antagonist Opioids

    PubMed Central

    Gear, Robert W.; Bogen, Oliver; Ferrari, Luiz F.; Green, Paul G.; Levine, Jon D.

    2014-01-01

    Clinical studies have shown that agonist-antagonist opioid analgesics that produce their analgesic effect via action on the kappa-opioid receptor, produce a delayed-onset anti-analgesia in men but not women, an effect blocked by co-administration of a low dose of naloxone. We now report the same time-dependent anti-analgesia and its underlying mechanism in an animal model. Using the Randall-Selitto paw-withdrawal assay in male rats, we found that nalbuphine, pentazocine, and butorphanol each produced analgesia during the first hour followed by anti-analgesia starting at ~90 minutes after administration in males but not females, closely mimicking its clinical effects. As observed in humans, co-administration of nalbuphine with naloxone in a dose ratio of 12.5:1 blocked anti-analgesia but not analgesia. Administration of the highly selective kappa-opioid receptor agonist U69,593 produced analgesia without subsequent anti-analgesia, and confirmed by the failure of the selective kappa antagonist nor-binaltorphimine to block nalbuphine-induced anti-analgesia, indicating that anti-analgesia is not mediated by kappa-opioid receptors. We therefore tested the role of other receptors in nalbuphine anti-analgesia. Nociceptin/orphanin FQ (NOP) and sigma-1 and sigma-2 receptors were chosen on the basis of their known anti-analgesic effects and receptor binding studies. The selective NOP receptor antagonists, JTC801, and J113397, but not the sigma receptor antagonist, BD 1047, antagonized nalbuphine anti-analgesia. Furthermore, the NOP receptor agonist NNC 63-0532 produced anti-analgesia with the same delay in onset observed with the three agonist-antagonists, but without producing preceding analgesia and this anti-analgesia was also blocked by naloxone. These results strongly support the suggestion that clinically used agonist-antagonists act at the NOP receptor to produce anti-analgesia. PMID:24188792

  17. The identification of a series of novel, soluble non-peptidic neuropeptide Y Y2 receptor antagonists.

    PubMed

    Lunniss, Gillian E; Barnes, Ashley A; Barton, Nick; Biagetti, Matteo; Bianchi, Federica; Blowers, Stephen M; Caberlotto, Laura L; Emmons, Amanda; Holmes, Ian P; Montanari, Dino; Norris, Roz; Puckey, Gemma V; Walters, Dewi J; Watson, Steve P; Willis, John

    2010-12-15

    The identification and subsequent optimisation of a selective non-peptidic NPY Y2 antagonist series is described. This led to the development of amine 2, a selective, soluble NPY Y2 receptor antagonist with enhanced CNS exposure.

  18. Blockade of Cocaine or σ Receptor Agonist Self Administration by Subtype-Selective σ Receptor Antagonists

    PubMed Central

    Hiranita, Takato; Kopajtic, Theresa A.; Rice, Kenner C.; Mesangeau, Christophe; Narayanan, Sanju; Abdelazeem, Ahmed H.; McCurdy, Christopher R.

    2016-01-01

    The identification of sigma receptor (σR) subtypes has been based on radioligand binding and, despite progress with σ1R cellular function, less is known about σR subtype functions in vivo. Recent findings that cocaine self administration experience will trigger σR agonist self administration was used in this study to assess the in vivo receptor subtype specificity of the agonists (+)-pentazocine, PRE-084 [2-(4-morpholinethyl) 1-phenylcyclohexanecarboxylate hydrochloride], and 1,3-di-o-tolylguanidine (DTG) and several novel putative σR antagonists. Radioligand binding studies determined in vitro σR selectivity of the novel compounds, which were subsequently studied for self administration and antagonism of cocaine, (+)-pentazocine, PRE-084, or DTG self administration. Across the dose ranges studied, none of the novel compounds were self administered, nor did they alter cocaine self administration. All compounds blocked DTG self administration, with a subset also blocking (+)-pentazocine and PRE-084 self administration. The most selective of the compounds in binding σ1Rs blocked cocaine self administration when combined with a dopamine transport inhibitor, either methylphenidate or nomifensine. These drug combinations did not decrease rates of responding maintained by food reinforcement. In contrast, the most selective of the compounds in binding σ2Rs had no effect on cocaine self administration in combination with either dopamine transport inhibitor. Thus, these results identify subtype-specific in vivo antagonists, and the utility of σR agonist substitution for cocaine self administration as an assay capable of distinguishing σR subtype selectivity in vivo. These results further suggest that effectiveness of dual σR antagonism and dopamine transport inhibition in blocking cocaine self administration is specific for σ1Rs and further support this dual targeting approach to development of cocaine antagonists. PMID:27189970

  19. Functional Mineralocorticoid Receptors in Human Vascular Endothelial Cells Regulate ICAM-1 Expression and Promote Leukocyte Adhesion

    PubMed Central

    Caprio, Massimiliano; Newfell, Brenna G.; la Sala, Andrea; Baur, Wendy; Fabbri, Andrea; Rosano, Giuseppe; Mendelsohn, Michael E.; Jaffe, Iris Z.

    2008-01-01

    In clinical trials, aldosterone antagonists decrease cardiovascular mortality and ischemia by unknown mechanisms. The steroid hormone aldosterone acts by binding to the mineralocorticoid receptor (MR), a ligand-activated transcription factor. In humans, aldosterone causes MR-dependent endothelial cell (EC) dysfunction and in animal models, aldosterone increases vascular macrophage infiltration and atherosclerosis. MR antagonists inhibit these effects without changing blood pressure, suggesting a direct role for vascular MR in EC function and atherosclerosis. Whether human vascular EC express functional MR is not known. Here we show that human coronary artery and aortic EC express MR mRNA and protein and that EC MR mediates aldosterone-dependent gene transcription. Human EC also express the enzyme 11-beta hydroxysteroid dehydrogenase-2(11βHSD2) and inhibition of 11βHSD2 in aortic EC enhances gene transactivation by cortisol, supporting that EC 11βHSD2 is functional. Furthermore, aldosterone stimulates transcription of the proatherogenic leukocyte-EC adhesion molecule Intercellular Adhesion Molecule-1(ICAM1) gene and protein expression on human coronary artery EC, an effect inhibited by the MR antagonist spironolactone and by MR knock-down with siRNA. Cell adhesion assays demonstrate that aldosterone promotes leukocyte-EC adhesion, an effect that is inhibited by spironolactone and ICAM1 blocking antibody, supporting that aldosterone induction of EC ICAM1 surface expression via MR mediates leukocyte-EC adhesion. These data show that aldosterone activates endogenous EC MR and proatherogenic gene expression in clinically important human EC. These studies describe a novel mechanism by which aldosterone may influence ischemic cardiovascular events and support a new explanation for the decrease in ischemic events in patients treated with aldosterone antagonists. PMID:18467630

  20. Heterogeneity of binding of muscarinic receptor antagonists in rat brain homogenates

    SciTech Connect

    Lee, J.H.; el-Fakahany, E.E.

    1985-06-01

    The binding properties of (-)-(/sup 3/H)quinuclidinyl benzilate and (/sup 3/H) N-methylscopolamine to muscarinic acetylcholine receptors have been investigated in rat brain homogenates. The binding of both antagonists demonstrated high affinity and saturability. Analysis of the binding data resulted in linear Scatchard plots. However, (-)-(/sup 3/H)quinuclidinyl benzilate showed a significantly higher maximal binding capacity than that of (/sup 3/H)N-methylscopolamine. Displacement of both ligands with several muscarinic receptor antagonists resulted in competition curves in accordance with the law of mass-action for quinuclidinyl benzilate, atropine and scopolamine. A similar profile was found for the quaternary ammonium analogs of atropine and scopolamine when (/sup 3/H)N-methylscopolamine was used to label the receptors. However, when these hydrophilic antagonists were used to displace (-)-(/sup 3/H) quinuclidinyl benzilate binding, they showed interaction with high- and low-affinity binding sites. On the other hand, the nonclassical muscarinic receptor antagonist, pirenzepine, was able to displace both ligands from two binding sites. The present data are discussed in terms of the relationship of this anomalous heterogenity of binding of these hydrophilic muscarinic receptor antagonists and the proposed M1 and M2 receptor subtypes.

  1. Effects of sigma(1) receptor ligand MS-377 on D(2) antagonists-induced behaviors.

    PubMed

    Karasawa, Jun-ichi; Takahashi, Shinji; Takagi, Kaori; Horikomi, Kazutoshi

    2002-10-01

    (R)-(+)-1-(4-Chlorophenyl)-3-[4-(2-methoxyethyl)piperazin-1-yl]methyl-2-pyrrolidinone L-tartrate (MS-377) is a novel antipsychotic agent with selective and high affinity for sigma(1) receptor. The present study was carried out to clarify the interaction of MS-377 with dopamine D(2) receptor antagonists (D(2) antagonists) in concurrent administration, and then the involvement of sigma receptors in the interaction. The effects of MS-377 on haloperidol- or sultopride-induced inhibition of apomorphine-induced climbing behavior and catalepsy were investigated in mice and rats, respectively. In addition, the effects of (+)-SKF-10,047 and SA4503, both of which are sigma receptor agonists, and WAY-100,635, which is a 5-HT(1A) receptor antagonist, on the interaction due to the concurrent use were also investigated. MS-377 potentiated the inhibitory effects of haloperidol or sultopride on apomorphine-induced climbing behavior in a dose-dependent manner. In contrast, MS-377 did not affect the catalepsy induction by these drugs. The potentiation of the inhibitory effects of haloperidol or sultopride on apomorphine-induced climbing behavior by MS-377 was not inhibited by WAY-100,635, but was inhibited by (+)-SKF-10,047 and SA4503. These findings showed that MS-377 potentiates the efficacy of D(2) antagonists, but it does not deteriorate the adverse effect. Moreover, sigma(1) receptors are involved in this potentiation of the efficacy of D(2) antagonists by MS-377.

  2. Impact of Aldosterone Antagonists on Sudden Cardiac Death Prevention in Heart Failure and Post-Myocardial Infarction Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

    PubMed Central

    Le, Hai-Ha; El-Khatib, Chadia; Mombled, Margaux; Guitarian, Frédéric; Al-Gobari, Muaamar; Fall, Mor; Janiaud, Perrine; Marchant, Ivanny; Cucherat, Michel; Bejan-Angoulvant, Théodora; Gueyffier, François

    2016-01-01

    Background and Objectives Sudden cardiac death (SCD) is a severe burden of modern medicine. Aldosterone antagonist is publicized as effective in reducing mortality in patients with heart failure (HF) or post myocardial infarction (MI). Our study aimed to assess the efficacy of AAs on mortality including SCD, hospitalization admission and several common adverse effects. Methods We searched Embase, PubMed, Web of Science, Cochrane library and clinicaltrial.gov for randomized controlled trials (RCTs) assigning AAs in patients with HF or post MI through May 2015. The comparator included standard medication or placebo, or both. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Event rates were compared using a random effects model. Prospective RCTs of AAs with durations of at least 8 weeks were selected if they included at least one of the following outcomes: SCD, all-cause/cardiovascular mortality, all-cause/cardiovascular hospitalization and common side effects (hyperkalemia, renal function degradation and gynecomastia). Results Data from 19,333 patients enrolled in 25 trials were included. In patients with HF, this treatment significantly reduced the risk of SCD by 19% (RR 0.81; 95% CI, 0.67–0.98; p = 0.03); all-cause mortality by 19% (RR 0.81; 95% CI, 0.74–0.88, p<0.00001) and cardiovascular death by 21% (RR 0.79; 95% CI, 0.70–0.89, p<0.00001). In patients with post-MI, the matching reduced risks were 20% (RR 0.80; 95% CI, 0.66–0.98; p = 0.03), 15% (RR 0.85; 95% CI, 0.76–0.95, p = 0.003) and 17% (RR 0.83; 95% CI, 0.74–0.94, p = 0.003), respectively. Concerning both subgroups, the relative risks respectively decreased by 19% (RR 0.81; 95% CI, 0.71–0.92; p = 0.002) for SCD, 18% (RR 0.82; 95% CI, 0.77–0.88, p < 0.0001) for all-cause mortality and 20% (RR 0.80; 95% CI, 0.74–0.87, p < 0.0001) for cardiovascular mortality in patients treated with AAs. As well, hospitalizations were significantly reduced

  3. Functions of 5-HT2A receptor and its antagonists in the cardiovascular system.

    PubMed

    Nagatomo, Takafumi; Rashid, Mamunur; Abul Muntasir, Habib; Komiyama, Tadazumi

    2004-10-01

    The serotonin (5-hydroxytryptamine, 5-HT) receptors have conventionally been divided into seven subfamilies, most of which have several subtypes. Among them, 5-HT(2A) receptor is associated with the contraction of vascular smooth muscle, platelet aggregation and thrombus formation and coronary artery spasms. Accordingly, selective 5-HT(2A) antagonists may have potential in the treatment of cardiovascular diseases. Sarpogrelate, a selective 5-HT(2A) antagonist, has been introduced clinically as a therapeutic agent for the treatment of ischemic diseases associated with thrombosis. Molecular modeling studies also suggest that sarpogrelate is a 5-HT(2A) selective antagonist and is likely to have pharmacological effects beneficial in the treatment of cardiovascular diseases. This review describes the above findings as well as the signaling linkages of the 5-HT(2A) receptors and the mode of agonist binding to 5-HT(2A) receptor using data derived from molecular modeling and site-directed mutagenesis.

  4. Anti free radical action of calcium antagonists and H1 and H2 receptors antagonists in neoplastic disease.

    PubMed

    della Rovere, F; Broccio, M; Granata, A; Zirilli, A; Brugnano, L; Artemisia, A; Broccio, G

    1996-01-01

    The blood of the subjects suffering from Neoplastic Disease (ND) shows phenomena of membrane peroxidation due to the presence of Free Radicals (FRs), in a quantity much greater than the one observed in the blood of healthy subjects. This can be detected either by calculating the time necessary for the formation of "Heinz bodies" (Hbs), (p < 0.00001) after oxidative stress of the blood in vitro with acetylphenylidrazine (APH), or by calculating the methemoglobin (metHb) quantity that forms after the same treatment (P < 0.00001). The statistical analyses we carried out showed that metHb formation was not affected by age, sex, smoking habits, red blood cell number, Hb, Ht or tumor staging. In this study, by using equal parameters of investigation, we noted that the blood of the subjects with ND who were previously treated with calcium-antagonists drugs and with antagonists of H1 and H2 receptors, gave results completely superimposable on the results obtained from healthy subjects, implying that the treatment had avoided the increase of FRs. Therefore we concluded that calcium-antagonists and the antagonists of the H1 and H2 receptors behave as antioxidant substances, having decreased the FRs damaging activity on the cellular membranes, thus controlling, although to a limited degree, the pejorative evolution of the disease. It is also important to remember that investigations into the ND, even possible screenings, must take into account the above said data, submitting the subjects under investigation to a pharmacological wash out, particularly with those substances which, are considered to be scavengers of FRs. Some of these substances are investigated in this work.

  5. The pharmacological properties of a novel MCH1 receptor antagonist isolated from combinatorial libraries

    PubMed Central

    Nagasaki, Hiroshi; Chung, Shinjae; Dooley, Colette T.; Wang, Zhiwei; Li, Chunying; Saito, Yumiko; Clark, Stewart D; Houghten, Richard A.; Civelli, Olivier

    2009-01-01

    Melanin-concentrating hormone (MCH) is a neuropeptide that exhibits potent orexigenic activity. In rodents, it exerts its actions by interacting with one receptor, MCH1 receptor which is expressed in many parts of the central nervous system (CNS). To study the physiological implications of the MCH system, we need to be able to block it locally and acutely. This necessitates the use of MCH1 receptor antagonists. While MCH1 receptor antagonists have been previously reported, they are mainly not accessible to academic research. We apply here a strategy that leads to the isolation of a high affinity and selective MCH1 receptor antagonist amenable to in vivo analyses without further chemical modifications. This antagonist, TPI 1361-17, was identified through the screening of multiple non-peptide positional scanning synthetic combinatorial libraries (PS-SCL) totaling more than eight hundred thousand compounds in conditions that allow for the identification of only high-affinity compounds. TPI 1361-17 exhibited an IC50 value of 6.1 nM for inhibition of 1 nM MCH-induced Ca2+ mobilization and completely displaced the binding of [125I] MCH to rat MCH1 receptor. TPI 1361-17 was found specific, having no affinity for a variety of other G-protein coupled receptors and channels. TPI 1361-17 was found active in vivo since it blocked MCH-induced food intake by 75 %. Our results indicate that TPI 1361-17 is a novel and selective MCH1 receptor antagonist and is an effective tool to study the physiological functions of the MCH system. These results also illustrate the successful application of combinatorial library screening to identify specific surrogate antagonists in an academic setting. PMID:19041642

  6. 3,4-Disubstituted indole acylsulfonamides: a novel series of potent and selective human EP3 receptor antagonists.

    PubMed

    Zhou, Nian; Zeller, Wayne; Krohn, Michael; Anderson, Herb; Zhang, Jun; Onua, Emmanuel; Kiselyov, Alex S; Ramirez, Jose; Halldorsdottir, Gułrún; Andrésson, Thornorkell; Gurney, Mark E; Singh, Jasbir

    2009-01-01

    A series of potent and selective EP(3) receptor antagonists are described. Utilizing a pharmacophore model developed for the EP(3) receptor, a series of 3,4-disubstituted indoles were shown to be high affinity ligands for this target. These compounds showed high selectivity over IP, FP and other EP receptors and are potent antagonists in functional assays.

  7. Identification of Receptor Ligands and Receptor Subtypes Using Antagonists in a Capillary Electrophoresis Single-Cell Biosensor Separation System

    NASA Astrophysics Data System (ADS)

    Fishman, Harvey A.; Orwar, Owe; Scheller, Richard H.; Zare, Richard N.

    1995-08-01

    A capillary electrophoresis system with single-cell biosensors as a detector has been used to separate and identify ligands in complex biological samples. The power of this procedure was significantly increased by introducing antagonists that inhibited the cellular response from selected ligand-receptor interactions. The single-cell biosensor was based on the ligand-receptor binding and G-protein-mediated signal transduction pathways in PC12 and NG108-15 cell lines. Receptor activation was measured as increases in cytosolic free calcium ion concentration by using fluorescence microscopy with the intracellular calcium ion indicator fluo-3 acetoxymethyl ester. Specifically, a mixture of bradykinin (BK) and acetylcholine (ACh) was fractionated and the components were identified by inhibiting the cellular response with icatibant (HOE 140), a selective antagonist to the BK B_2 receptor subtype (B_2BK), and atropine, an antagonist to muscarinic ACh receptor subtypes. Structurally related forms of BK were also identified based on inhibiting B_2BK receptors. Applications of this technique include identification of endogenous BK in a lysate of human hepatocellular carcinoma cells (Hep G2) and screening for bioactivity of BK degradation products in human blood plasma. The data demonstrate that the use of antagonists with a single-cell biosensor separation system aids identification of separated components and receptor subtypes.

  8. 5-HT2B Receptor Antagonists Inhibit Fibrosis and Protect from RV Heart Failure

    PubMed Central

    Janssen, Wiebke; Schymura, Yves; Novoyatleva, Tatyana; Luitel, Himal; Tretyn, Aleksandra; Pullamsetti, Soni Savai; Weissmann, Norbert; Seeger, Werner; Ghofrani, Hossein Ardeschir; Schermuly, Ralph Theo

    2015-01-01

    Objective. The serotonin (5-HT) pathway was shown to play a role in pulmonary hypertension (PH), but its functions in right ventricular failure (RVF) remain poorly understood. The aim of the current study was to investigate the effects of Terguride (5-HT2A and 2B receptor antagonist) or SB204741 (5-HT2B receptor antagonist) on right heart function and structure upon pulmonary artery banding (PAB) in mice. Methods. Seven days after PAB, mice were treated for 14 days with Terguride (0.2 mg/kg bid) or SB204741 (5 mg/kg day). Right heart function and remodeling were assessed by right heart catheterization, magnetic resonance imaging (MRI), and histomorphometric methods. Total secreted collagen content was determined in mouse cardiac fibroblasts isolated from RV tissues. Results. Chronic treatment with Terguride or SB204741 reduced right ventricular fibrosis and showed improved heart function in mice after PAB. Moreover, 5-HT2B receptor antagonists diminished TGF-beta1 induced collagen synthesis of RV cardiac fibroblasts in vitro. Conclusion. 5-HT2B receptor antagonists reduce collagen deposition, thereby inhibiting right ventricular fibrosis. Chronic treatment prevented the development and progression of pressure overload-induced RVF in mice. Thus, 5-HT2B receptor antagonists represent a valuable novel therapeutic approach for RVF. PMID:25667920

  9. Coptis extracts enhance the anticancer effect of estrogen receptor antagonists on human breast cancer cells.

    PubMed

    Liu, Jing; He, Chengwei; Zhou, Keyuan; Wang, Jingdong; Kang, Jing X

    2009-01-09

    Estrogen receptor (ER) antagonists have been widely used for breast cancer treatment, but the efficacy and drug resistance remain to be clinical concerns. The purpose of this study was to determine whether the extracts of coptis, an anti-inflammatory herb, improve the anticancer efficacy of ER antagonists. The results showed that the combined treatment of ER antagonists and the crude extract of coptis or its purified compound berberine conferred synergistic growth inhibitory effect on MCF-7 cells (ER+), but not on MDA-MB-231 cells (ER-). Similar results were observed in the combined treatment of fulvestrant, a specific aromatase antagonist. Analysis of the expression of breast cancer related genes indicated that EGFR, HER2, bcl-2, and COX-2 were significantly downregulated, while IFN-beta and p21 were remarkably upregulated by berberine. Our results suggest that coptis extracts could be promising adjuvant to ER antagonists in ER positive breast cancer treatment through regulating expression of multiple genes.

  10. Molecular modeling of histamine H3 receptor and QSAR studies on arylbenzofuran derived H3 antagonists.

    PubMed

    Dastmalchi, Siavoush; Hamzeh-Mivehroud, Maryam; Ghafourian, Taravat; Hamzeiy, Hossain

    2008-01-01

    Histamine H3 receptors are presynaptic autoreceptors found in both central and peripheral nervous systems of many species. The central effects of these receptors suggest a potential therapeutic role for their antagonists in treatment of several neurological disorders such as epilepsy, schizophrenia, Alzheimer's and Parkinson's diseases. The purpose of this study was to identify the structural requirements for H3 antagonistic activity via quantitative structure-activity relationship (QSAR) studies and receptor modeling/docking techniques. A combination of partial least squares (PLS) and genetic algorithm (GA) was used in the QSAR approach to select the structural descriptors relevant to the receptor binding affinity of a series of 58 H3 antagonists. The descriptors were selected out of a pool of >1000 descriptors calculated by DRAGON, Hyperchem and ACD labs suite of programs. The resulting QSAR models for rat and human H3 binding affinities were validated using different strategies. QSAR models generated in the current work suggested the role of charge transfer interactions in the ligand-receptor interaction verified using the molecular modeling of the receptor and docking two antagonists to the binding site. The 3D model of human H3 receptor was built based on bovine rhodopsin structure and evaluated by molecular dynamics (MD) simulation in a mixed water-vacuum-water environment. The results were indicative of the stability of the model relating the observed structural changes during the MD simulation to the suggested ligand-receptor interactions. The results of this investigation are expected to be useful in the process of design and development of new potent H3 receptor antagonists.

  11. Neurokinin-1 Receptor Antagonists as Antitumor Drugs in Gastrointestinal Cancer: A New Approach

    PubMed Central

    Muñoz, Miguel; Coveñas, Rafael

    2016-01-01

    Gastrointestinal (GI) cancer is the term for a group of cancers affecting the digestive system. After binding to the neurokinin-1 (NK-1) receptor, the undecapeptide substance P (SP) regulates GI cancer cell proliferation and migration for invasion and metastasis, and controls endothelial cell proliferation for angiogenesis. SP also exerts an antiapoptotic effect. Both SP and the NK-1 receptor are located in GI tumor cells, the NK-1 receptor being overexpressed. By contrast, after binding to the NK-1 receptor, NK-1 receptor antagonists elicit the inhibition (epidermal growth factor receptor inhibition) of the proliferation of GI cancer cells in a concentration-dependent manner, induce the death of GI cancer cells by apoptosis, counteract the Warburg effect, inhibit cancer cell migration (counteracting invasion and metastasis), and inhibit angiogenesis (vascular endothelial growth factor inhibition). NK-1 receptor antagonists are safe and well tolerated. Thus, the NK-1 receptor could be considered as a new target in GI cancer and NK-1 receptor antagonists (eg, aprepitant) could be a new promising approach for the treatment of GI cancer. PMID:27488320

  12. N-Arylpiperazine-1-carboxamide derivatives: a novel series of orally active nonsteroidal androgen receptor antagonists.

    PubMed

    Kinoyama, Isao; Taniguchi, Nobuaki; Kawaminami, Eiji; Nozawa, Eisuke; Koutoku, Hiroshi; Furutani, Takashi; Kudoh, Masafumi; Okada, Minoru

    2005-04-01

    A novel series of N-arylpiperazine-1-carboxamide derivatives was synthesized and their androgen receptor (AR) antagonist activities and in vivo antiandrogenic properties were evaluated. Reporter assays indicated that trans-2,5-dimethylpiperazine derivatives are potent AR antagonists, and in this series trans-N-4-[4-cyano-3-(trifluoromethyl)phenyl]-N-(2,4-difluorophenyl)-2,5-dimethylpiperazine-1-carboxamide (18 g, YM-175735) exhibited the most potent antiandrogenic activity. Compared to bicalutamide, YM-175735 is an approximately 4-fold stronger AR antagonist and has slightly increased antiandrogenic activity, suggesting that YM-175735 may be useful in the treatment of prostate cancer.

  13. A novel aldosterone synthase inhibitor ameliorates mortality in pressure-overload mice with heart failure.

    PubMed

    Furuzono, Shinji; Meguro, Masaki; Miyauchi, Satoru; Inoue, Shinichi; Homma, Tsuyoshi; Yamada, Keisuke; Tagawa, Yoh-Ichi; Nara, Futoshi; Nagayama, Takahiro

    2017-01-15

    It has been elucidated that mineralocorticoid receptor antagonists reduce mortality in patients with congestive heart failure and post-acute myocardial infarction. A direct inhibition of aldosterone synthase (CYP11B2) is also expected to have therapeutic benefits equal in quality to mineralocorticoid receptor antagonists in terms of reducing mineralocorticoid receptor signaling. Therefore, we have screened our chemical libraries and identified a novel and potent aldosterone synthase inhibitor, 2,2,2-trifluoro-1-{4-[(4-fluorophenyl)amino]pyrimidin-5-y}-1-[1-(methylsulfonyl)piperidin-4-yl]ethanol (compound 1), by lead optimization. Pharmacological properties of compound 1 were examined in in vitro cell-based assays and an in vivo mouse model of pressure-overload hypertrophy by transverse aortic constriction (TAC). Compound 1 showed potent CYP11B2 inhibition against human and mouse enzymes (IC50; 0.003μM and 0.096μM, respectively) in a cell-based assay. The oral administration of 0.06% compound 1 in the food mixture of a mouse TAC model significantly reduced the plasma aldosterone level and ameliorated mortality rate. This study is the first to demonstrate that a CYP11B2 inhibitor improved survival rates of heart failure induced by pressure-overload in mice. The treatment of 0.06% compound 1 did not elevate plasma potassium level in this model, although further evaluation of hyperkalemia is needed. These results suggest that compound 1 can be developed as a promising oral CYP11B2 inhibitor for pharmaceutical applications. Compound 1 could also be a useful compound for clarifying the role of aldosterone in cardiac hypertrophy.

  14. Role of ACTH and Other Hormones in the Regulation of Aldosterone Production in Primary Aldosteronism

    PubMed Central

    El Ghorayeb, Nada; Bourdeau, Isabelle; Lacroix, André

    2016-01-01

    The major physiological regulators of aldosterone production from the adrenal zona glomerulosa are potassium and angiotensin II; other acute regulators include adrenocorticotropic hormone (ACTH) and serotonin. Their interactions with G-protein coupled hormone receptors activate cAMP/PKA pathway thereby regulating intracellular calcium flux and CYP11B2 transcription, which is the specific steroidogenic enzyme of aldosterone synthesis. In primary aldosteronism (PA), the increased production of aldosterone and resultant relative hypervolemia inhibits the renin and angiotensin system; aldosterone secretion is mostly independent from the suppressed renin–angiotensin system, but is not autonomous, as it is regulated by a diversity of other ligands of various eutopic or ectopic receptors, in addition to activation of calcium flux resulting from mutations of various ion channels. Among the abnormalities in various hormone receptors, an overexpression of the melanocortin type 2 receptor (MC2R) could be responsible for aldosterone hypersecretion in aldosteronomas. An exaggerated increase in plasma aldosterone concentration (PAC) is found in patients with PA secondary either to unilateral aldosteronomas or bilateral adrenal hyperplasia (BAH) following acute ACTH administration compared to normal individuals. A diurnal increase in PAC in early morning and its suppression by dexamethasone confirms the increased role of endogenous ACTH as an important aldosterone secretagogue in PA. Screening using a combination of dexamethasone and fludrocortisone test reveals a higher prevalence of PA in hypertensive populations compared to the aldosterone to renin ratio. The variable level of MC2R overexpression in each aldosteronomas or in the adjacent zona glomerulosa hyperplasia may explain the inconsistent results of adrenal vein sampling between basal levels and post ACTH administration in the determination of source of aldosterone excess. In the rare cases of glucocorticoid remediable

  15. The Multifaceted Mineralocorticoid Receptor

    PubMed Central

    Gomez-Sanchez, Elise; Gomez-Sanchez, Celso E.

    2015-01-01

    The primary adrenal cortical steroid hormones, aldosterone, and the glucocorticoids cortisol and corticosterone, act through the structurally similar mineralocorticoid (MR) and glucocorticoid receptors (GRs). Aldosterone is crucial for fluid, electrolyte, and hemodynamic homeostasis and tissue repair; the significantly more abundant glucocorticoids are indispensable for energy homeostasis, appropriate responses to stress, and limiting inflammation. Steroid receptors initiate gene transcription for proteins that effect their actions as well as rapid non-genomic effects through classical cell signaling pathways. GR and MR are expressed in many tissues types, often in the same cells, where they interact at molecular and functional levels, at times in synergy, others in opposition. Thus the appropriate balance of MR and GR activation is crucial for homeostasis. MR has the same binding affinity for aldosterone, cortisol, and corticosterone. Glucocorticoids activate MR in most tissues at basal levels and GR at stress levels. Inactivation of cortisol and corticosterone by 11β-HSD2 allows aldosterone to activate MR within aldosterone target cells and limits activation of the GR. Under most conditions, 11β-HSD1 acts as a reductase and activates cortisol/corticosterone, amplifying circulating levels. 11β-HSD1 and MR antagonists mitigate inappropriate activation of MR under conditions of oxidative stress that contributes to the pathophysiology of the cardiometabolic syndrome; however, MR antagonists decrease normal MR/GR functional interactions, a particular concern for neurons mediating cognition, memory, and affect. PMID:24944027

  16. Bismuth increases hydroxyl radical-scavenging activity of histamine H2-receptor antagonists.

    PubMed

    Kirkova, Margarita; Alexandrova, Albena; Yordanova, Neli

    2006-01-01

    The effects of histamine H2-receptor antagonists, alone or in a combination with bismuth, on *OH-provoked degradation of deoxyribose were studied. The histamine H2-receptor antagonists (cimetidine, ranitidine and roxatidine), themselves decreased the deoxyribose damage in Fenton-type systems. In combinations with bismuth, their inhibitory effect in Fenton system (Fe(III)/ascorbic acid + H2O2 was stronger. Moreover, unlike F(III) and Cu(II), which in the presence of ascorbic acid + H2O2 led to an increase in the *OH formation (deoxyribose damage), Bi(III) showed an opposite effect. The present results are interpreted in view of a better ( )OH scavenging activity of bismuth complexes of histamine H2-receptor antagonists as compared to that of the corresponding drugs. These findings might be one more explanation why bismuth salts, in combination with acid-reducing agents, are more effective anti-ulcer agents.

  17. A long-acting GH receptor antagonist through fusion to GH binding protein

    PubMed Central

    Wilkinson, Ian R.; Pradhananga, Sarbendra L.; Speak, Rowena; Artymiuk, Peter J.; Sayers, Jon R.; Ross, Richard J.

    2016-01-01

    Acromegaly is a human disease of growth hormone (GH) excess with considerable morbidity and increased mortality. Somatostatin analogues are first line medical treatment but the disease remains uncontrolled in up to 40% of patients. GH receptor (GHR) antagonist therapy is more effective but requires frequent high-dose injections. We have developed an alternative technology for generating a long acting potent GHR antagonist through translational fusion of a mutated GH linked to GH binding protein and tested three candidate molecules. All molecules had the amino acid change (G120R), creating a competitive GHR antagonist and we tested the hypothesis that an amino acid change in the GH binding domain (W104A) would increase biological activity. All were antagonists in bioassays. In rats all antagonists had terminal half-lives >20 hours. After subcutaneous administration in rabbits one variant displayed a terminal half-life of 40.5 hours. A single subcutaneous injection of the same variant in rabbits resulted in a 14% fall in IGF-I over 7 days. In conclusion: we provide proof of concept that a fusion of GHR antagonist to its binding protein generates a long acting GHR antagonist and we confirmed that introducing the W104A amino acid change in the GH binding domain enhances antagonist activity. PMID:27731358

  18. Kinetic properties of "dual" orexin receptor antagonists at OX1R and OX2R orexin receptors.

    PubMed

    Callander, Gabrielle E; Olorunda, Morenike; Monna, Dominique; Schuepbach, Edi; Langenegger, Daniel; Betschart, Claudia; Hintermann, Samuel; Behnke, Dirk; Cotesta, Simona; Fendt, Markus; Laue, Grit; Ofner, Silvio; Briard, Emmanuelle; Gee, Christine E; Jacobson, Laura H; Hoyer, Daniel

    2013-01-01

    Orexin receptor antagonists represent attractive targets for the development of drugs for the treatment of insomnia. Both efficacy and safety are crucial in clinical settings and thorough investigations of pharmacokinetics and pharmacodynamics can predict contributing factors such as duration of action and undesirable effects. To this end, we studied the interactions between various "dual" orexin receptor antagonists and the orexin receptors, OX1R and OX2R, over time using saturation and competition radioligand binding with [(3)H]-BBAC ((S)-N-([1,1'-biphenyl]-2-yl)-1-(2-((1-methyl-1H-benzo[d]imidazol-2-yl)thio)acetyl)pyrrolidine-2-carboxamide). In addition, the kinetics of these compounds were investigated in cells expressing human, mouse and rat OX1R and OX2R using FLIPR® assays for calcium accumulation. We demonstrate that almorexant reaches equilibrium very slowly at OX2R, whereas SB-649868, suvorexant, and filorexant may take hours to reach steady state at both orexin receptors. By contrast, compounds such as BBAC or the selective OX2R antagonist IPSU ((2-((1H-Indol-3-yl)methyl)-9-(4-methoxypyrimidin-2-yl)-2,9-diazaspiro[5.5]undecan-1-one) bind rapidly and reach equilibrium very quickly in binding and/or functional assays. Overall, the "dual" antagonists tested here tend to be rather unselective under non-equilibrium conditions and reach equilibrium very slowly. Once equilibrium is reached, each ligand demonstrates a selectivity profile that is however, distinct from the non-equilibrium condition. The slow kinetics of the "dual" antagonists tested suggest that in vitro receptor occupancy may be longer lasting than would be predicted. This raises questions as to whether pharmacokinetic studies measuring plasma or brain levels of these antagonists are accurate reflections of receptor occupancy in vivo.

  19. LH, progesterone, and TSH can stimulate aldosterone in vitro: a study on normal adrenal cortex and aldosterone producing adenoma.

    PubMed

    Nicolini, G; Balzan, S; Morelli, L; Iacconi, P; Sabatino, L; Ripoli, A; Fommei, E

    2014-05-01

    Endocrine factors different from ACTH or angiotensin II can stimulate aldosterone secretion and have a role in the pathophysiology of hyperaldosteronism. Aldosterone may increase in luteotropic/progestogenic and in hypothyroid states; LH and, occasionally, TSH receptors have been detected in normal adrenal cortex and aldosterone-producing adenoma. The aim of the study was to compare adrenal contents of LH and TSH receptors between normal cortex and aldosterone-producing adenoma and to evaluate the ability of LH, its product progesterone, and TSH to stimulate aldosterone secretion in vitro from primary adrenocortical cells. Surgical aldosterone-producing adenoma fragments from 19 patients and adrenal cortex fragments from 10 kidney donors were used for Western blotting and cell cultures. LH (n=26), TSH (n=19) and progesterone (n=8) receptor proteins were investigated; LH receptor-mRNA was also tested in 8 samples. Aldosterone responses in vitro to LH, progesterone, and TSH stimulation were assayed. LH and TSH receptors were more expressed in adenoma than normal cortex (p<0.01, p<0.05, respectively); progesterone receptor was observed in 6/8 samples. Aldosterone increased after in vitro stimulation with LH (5/12 adenoma, 1/7 normal cells), progesterone (4/5 adenoma, 5/6 normal cells), and TSH (3/5 adenoma and 3/5 normal cells). LH and TSH receptors were more expressed in aldosterone producing adenoma than normal adrenal cortex. LH, progesterone, and TSH can stimulate aldosterone in vitro. Similar mechanisms could participate in vivo in the aldosterone increase in lutheotropic, progestogenic, or hypothyroid states and may exist in both normal adrenal cortex and adenoma in responsive individuals.

  20. Aldosterone increases the apical Na sup + permeability of toad bladder by two different mechanisms

    SciTech Connect

    Asher, C.; Garty, H. )

    1988-10-01

    The aldosterone-induced augmentation of Na{sup +} transport in toad bladder was analyzed by comparing the hormonal actions on the transepithelial short-circuit current and on the amiloride-sensitive {sup 22}Na{sup +} uptake in isolated membrane vesicles. Incubating bladders with 0.5 {mu}M aldosterone for 3 hr evoked more than a 2-fold increase of the short-circuit current but had no effect on the amiloride-sensitive Na{sup +} transport in apical vesicles derived from the treated tissue. A longer incubation produced an additional augmentation of the short-circuit current, which was accompanied by about a 3-fold increase of the channel activity in isolated membranes. The stimulatory effect of aldosterone sustained in vesicles was inhibited by the antagonist spironolactone and the protein synthesis inhibitor cycloheximide. It is suggested that aldosterone elevates the apical Na{sup +} permeability of target epithelia by two different mechanisms: a relatively fast effect which is insensitive to triiodothyronine or butyrate and is not sustained by the isolated membrane, and a slower or later response blocked by these reagents, which is preserved by the isolated membrane. The data also indicate that these processes are mediated by different nuclear receptors.

  1. Characterization of PCS1055, a novel muscarinic M4 receptor antagonist.

    PubMed

    Croy, Carrie H; Chan, Wai Y; Castetter, Andrea M; Watt, Marla L; Quets, Anne T; Felder, Christian C

    2016-07-05

    Identification of synthetic ligands selective for muscarinic receptor subtypes has been challenging due to the high sequence identity and structural homology among the five muscarinic acetylcholine receptors. Here, we report the pharmacological characterization of PCS1055, a novel muscarinic M4 receptor antagonist. PCS1055 inhibited radioligand [(3)H]-NMS binding to the M4 receptor with a Ki=6.5nM. Though the potency of PCS1055 is lower than that of pan-muscarinic antagonist atropine, it has better subtype selectivity over previously reported M4-selective reagents such as the muscarinic-peptide toxins (Karlsson et al., 1994; Santiago and Potter, 2001a) at the M1 subtype, and benzoxazine ligand PD102807 at the M3-subtype (Bohme et al., 2002). A detailed head-to-head comparison study using [(3)H]-NMS competitive binding assays characterizes the selectivity profiles of PCS1055 to that of other potent muscarinic-antagonist compounds PD102807, tropicamide, AF-DX-384, pirenzapine, and atropine. In addition to binding studies, the subtype specificity of PCS1055 is also demonstrated by functional receptor activation as readout by GTP-γ-[(35)S] binding. These GTP-γ-[(35)S] binding studies showed that PCS1055 exhibited 255-, 69.1-, 342- and >1000-fold greater inhibition of Oxo-M activity at the M4 versus the M1-, M2(-), M3-or M5 receptor subtypes, respectively. Schild analyses indicates that PCS1055 acts as a competitive antagonist to muscarinic M4 receptor, and confirms the affinity of the ligand to be low nanomolar, Kb=5.72nM. Therefore, PCS1055 represents a new M4-preferring antagonist that may be useful in elucidating the roles of M4 receptor signaling.

  2. Tranylcypromine Substituted cis-Hydroxycyclobutylnaphthamides as Potent and Selective Dopamine D3 Receptor Antagonists

    PubMed Central

    2015-01-01

    We report a class of potent and selective dopamine D3 receptor antagonists based upon tranylcypromine. Although tranylcypromine has a low affinity for the rat D3 receptor (Ki = 12.8 μM), our efforts have yielded (1R,2S)-11 (CJ-1882), which has Ki values of 2.7 and 2.8 nM at the rat and human dopamine D3 receptors, respectively, and displays respective selectivities of >10000-fold and 223-fold over the rat and human D2 receptors. Evaluation in a β-arrestin functional assay showed that (1R,2S)-11 is a potent and competitive antagonist at the human D3 receptor. PMID:24848155

  3. Topical interleukin-1 receptor antagonist inhibits inflammatory cell infiltration into the cornea.

    PubMed

    Stapleton, W Michael; Chaurasia, Shyam S; Medeiros, Fabricio W; Mohan, Rajiv R; Sinha, Sunilima; Wilson, Steven E

    2008-05-01

    Interleukin (IL)-1alpha and beta are important modulators of many functions of corneal epithelial and stromal cells that occur following injury to the cornea, including the influx of bone marrow-derived inflammatory cells into the stroma attracted by chemokines released from the stroma and epithelium. In this study, we examined the effect of topical soluble IL-1 receptor antagonist on bone marrow-derived cell influx following corneal epithelial scrape injury in a mouse model. C57BL/6 mice underwent corneal epithelial scrape followed by application of IL-1 receptor antagonist (Amgen, Thousand Oaks, CA) at a concentration of 20 mg/ml or vehicle for 24 h prior to immunocytochemical detection of marker CD11b-positive cells into the stroma. In two experiments, topical IL-1 receptor antagonist had a marked effect in blocking cell influx. For example, in experiment 1, topical IL-1 receptor antagonist markedly reduced detectible CD11b-positive cells into the corneal stroma at 24h after epithelial injury compared with the vehicle control (3.5+/-0.5 (standard error of the mean) cells/400x field and 13.9+/-1.2 cells/400x field, respectively, p<0.01). A second experiment with a different observer performing cell counting had the same result. Thus, the data demonstrate conclusively that topical IL-1 receptor antagonist markedly down-regulates CD-11b-positive monocytic cell appearance in the corneal stroma. Topical IL-1 receptor antagonist could be an effective adjuvant for clinical treatment of corneal conditions in which unwanted inflammation has a role in the pathophysiology of the disorder.

  4. [Effects of agonists and antagonists of benzodiazepine, GABA and NMDA receptors, on caffeine-induced seizures in mice].

    PubMed

    Inano, S

    1992-08-01

    In mice, tonic convulsive seizure induced by intravenous administration of caffeine (adenosine A1, A2 receptors antagonist) was significantly potentiated by any one of L-PIA (adenosine A1 receptor agonist), NECA (adenosine A2 receptor agonist) and 2-ClAd (adenosine A1, A2 receptors agonist). The caffeine-induced seizure was unaffected by diazepam (benzodiazepine receptor agonist), but was inhibited by Ro 15-1788 (antagonist or partial agonist). beta-DMCM (antagonist or inverse agonist) increased the seizure. Muscimol (GABA-a receptor agonist), baclofen (GABA-b receptor agonist) and AOAA (GABA transaminase inhibitor) did not show significant effect on caffeine-induced convulsion. Bicuculline (GABA-a receptor antagonist) and picrotoxin (chloride channel blocker) significantly potentiated the convulsion at the doses which did not induce it. Caffeine-induced convulsion was potentiated by NMDA with its non-convulsive dose. CPP (competitive NMDA receptor antagonist) and MK-801 (non-competitive NMDA receptor antagonist) significantly inhibited the seizures. These results suggest that caffeine-induced seizure is not caused by blockade of adenosine receptors. Caffeine may act to beta-carboline sensitive benzodiazepine receptor (Type 1) which has no linkage with GABA-a receptor. Furthermore, it is implied that caffeine plays some role at NMDA receptor calcium ion channel complex.

  5. CGRP receptor antagonists: A new frontier of anti-migraine medications

    PubMed Central

    de Prado, Blanca Marquez; Russo, Andrew F.

    2009-01-01

    Migraine is a chronic pain condition that affects 12% of the population. Currently, the most effective treatments are the triptans, but they are limited in their efficacy and have potentially deleterious cardiovascular complications. Based on basic science studies over the past decade, a new generation of anti-migraine drugs is now being developed. At the forefront of these studies is a new calcitonin gene-related peptide (CGRP) receptor antagonist that is as effective as triptans in the acute treatment of migraines, without the cardiovascular effects. This review will address the likely mechanisms and therapeutic potential of CGRP receptor antagonists. PMID:19784396

  6. Synthesis and biological evaluations of chalcones, flavones and chromenes as farnesoid x receptor (FXR) antagonists.

    PubMed

    Zhang, Guoning; Liu, Shuainan; Tan, Wenjuan; Verma, Ruchi; Chen, Yuan; Sun, Deyang; Huan, Yi; Jiang, Qian; Wang, Xing; Wang, Na; Xu, Yang; Wong, Chiwai; Shen, Zhufang; Deng, Ruitang; Liu, Jinsong; Zhang, Yanqiao; Fang, Weishuo

    2017-03-31

    Farnesoid X receptor (FXR), a nuclear receptor mainly distributed in liver and intestine, has been regarded as a potential target for the treatment of various metabolic diseases, cancer and infectious diseases related to liver. Starting from two previously identified chalcone-based FXR antagonists, we tried to increase the activity through the design and synthesis of a library containing chalcones, flavones and chromenes, based on substitution manipulation and conformation (ring closure) restriction strategy. Many chalcones and four chromenes were identified as microM potent FXR antagonists, among which chromene 11c significantly decreased the plasma and hepatic triglyceride level in KKay mice.

  7. Molecular determinants of the species selectivity of neurokinin type 1 receptor antagonists.

    PubMed

    Pradier, L; Habert-Ortoli, E; Emile, L; Le Guern, J; Loquet, I; Bock, M D; Clot, J; Mercken, L; Fardin, V; Garret, C

    1995-02-01

    Most nonpeptide neurokinin (NK)1 antagonists display a marked difference in affinity for rat versus human NK1 receptors. The molecular basis for the species selectivity of RP67580 and CP96,345 has been previously addressed [J. Biol. Chem. 267:25668-25671 (1992); J. Biol. Chem. 268:2319-2323 (1993)]. We are extending these previous results to additional NK1 antagonists, which are members of different chemical families. Included is a new perhydroisoindolol, RPR100893, which unlike its parent compound (RP67580) is human receptor selective. Chimeric rat/human NK1 receptors, as well as rat and human mutant NK1 receptors, were constructed and expressed in COS-1 cells, and affinities for substance P and the various antagonists were determined in binding studies. With human receptor-selective antagonists, the rat R290(S-->I) mutation was the most effective in increasing antagonist affinity (from 7- to 23-fold). Combination with the R116(L-->V) mutation led to an additional increase in affinity for trans-4-hydroxy-1-(1H-indol-3-ylcarbonyl)-L-prolyl-N- methyl-N-(phenylmethyl)-L-tyrosineamide (a derivative of FK888) and to nearly full human receptor affinity for RPR100893 and (+/-)-CP99,994. Based on the gains in affinities, these results confirm and extend the role of residues 116 and 290 of the NK1 receptor in the species selectivity of these three new human receptor-selective NK1 antagonists. In comparison, the affinity of RP67580, the least selective molecule, was most affected by changes at position 116, and combination with mutations at either position 97 (V-->E) or position 290 led to the human receptor phenotype. For the heterosteroid KAN610857, modifications of the rat receptor at positions 97 and 290, and to a lesser degree position 116, were the most effective in reducing affinity. Two double-mutants [R(97,290) and R(116,290)], although different from those identified for RP67580, also displayed human receptor-like affinity. Therefore, the molecular determinants of

  8. Pharmacological analysis of CCK2 receptor antagonists using isolated rat stomach ECL cells

    PubMed Central

    Lindström, Erik; Björkqvist, Maria; Håkanson, Rolf

    1999-01-01

    Gastrin stimulates rat stomach ECL cells to secrete histamine and pacreastatin, a chromogranin A (CGA)-derived peptide. The present report describes the effect of nine cholecystokinin2 (CCK2) receptor antagonists and one CCK1 receptor antagonist on the gastrin-evoked secretion of pancreastatin from isolated ECL cells.The CCK2 receptor antagonists comprised three benzodiazepine derivatives L-740,093, YM022 and YF476, one ureidoacetamide compound RP73870, one benzimidazole compound JB 93182, one ureidoindoline compound AG041R and three tryptophan dipeptoids PD 134308 (CI988), PD135158 and PD 136450. The CCK1 receptor antagonist was devazepide.A preparation of well-functioning ECL cells (∼80% purity) was prepared from rat oxyntic mucosa using counter-flow elutriation. The cells were cultured for 48 h in the presence of 0.1 nM gastrin; they were then washed and incubated with antagonist alone or with various concentrations of antagonist plus 10 nM gastrin (a maximally effective concentration) for 30 min. Gastrin dose-response curves were constructed in the absence or presence of increasing concentrations of antagonist. The amount of pancreastatin secreted was determined by radioimmunoassay.The gastrin-evoked secretion of pancreastatin was inhibited in a dose-dependent manner. YM022, AG041R and YF476 had IC50 values of 0.5, 2.2 and 2.7 nM respectively. L-740,093, JB93182 and RP73870 had IC50 values of 7.8, 9.3 and 9.8 nM, while PD135158, PD136450 and PD134308 had IC50 values of 76, 135 and 145 nM. The CCK1 receptor antagonist devazepide was a poor CCK2 receptor antagonist with an IC50 of about 800 nM.YM022, YF476 and AG041R were chosen for further analysis. YM022 and YF476 shifted the gastrin dose-response curve to the right in a manner suggesting competitive antagonism, while the effects of AG041R could not be explained by simple competitive antagonism. pKB values were 11.3 for YM022, 10.8 for YF476 and the apparent pKB for AG041R was 10.4. PMID

  9. Inverse agonism of histamine H2 antagonist accounts for upregulation of spontaneously active histamine H2 receptors.

    PubMed Central

    Smit, M J; Leurs, R; Alewijnse, A E; Blauw, J; Van Nieuw Amerongen, G P; Van De Vrede, Y; Roovers, E; Timmerman, H

    1996-01-01

    Histamine H2 receptors transfected in Chinese hamster ovary (CHO) cells are time- and dose-dependently upregulated upon exposure to the H2 antagonists cimetidine and ranitidine. This effect appears to be H2 receptor-mediated as no change in receptor density was observed after H1 or H3 antagonist treatment or after incubation with the structural analogue of cimetidine, VUF 8299, which has no H2 antagonistic effects. By using transfected CHO cells expressing different densities of wild-type H2 receptors or an uncoupled H2Leu124Ala receptor, the histamine H2 receptor was found to display considerable agonist-independent H2 receptor activity. Cimetidine and ranitidine, which both induce H2 receptor upregulation, actually functioned as inverse agonists in those cell lines displaying spontaneous agonist-independent H2 receptor activity. Burimamide, on the other hand, was shown to act as a neutral antagonist and did as expected not induce H2 receptor upregulation after long-term exposure. The displayed inverse agonism of H2 antagonists appears to be a mechanistic basis for the observed H2 antagonist-induced H2 receptor upregulation in transfected CHO cells. These observations shed new light on the pharmacological classification of the H2 antagonists and may offer a plausible explanation for the observed development of tolerance after prolonged clinical use. Images Fig. 3 PMID:8692899

  10. The dual orexin receptor antagonist TCS1102 does not affect reinstatement of nicotine-seeking

    PubMed Central

    McNally, Gavan P.; Clemens, Kelly J.

    2017-01-01

    The orexin/hypocretin system is important for appetitive motivation towards multiple drugs of abuse, including nicotine. Both OX1 and OX2 receptors individually have been shown to influence nicotine self-administration and reinstatement. Due to the increasing clinical use of dual orexin receptor antagonists in the treatment of disorders such as insomnia, we examined whether a dual orexin receptor antagonist may also be effective in reducing nicotine seeking. We tested the effect of intracerebroventricular (i.c.v.) administration of the potent and selective dual orexin receptor antagonist TCS1102 on orexin-A-induced food self-administration, nicotine self-administration and reinstatement of nicotine-seeking in rats. Our results show that 30 μg of TCS1102 i.c.v. abolishes orexin-A-induced increases in food self-administration but does not reduce nicotine self-administration. Neither i.c.v. 10 μg nor 30 μg of TCS1102 reduced compound reinstatement after short-term (15 days) self-administration nicotine, but 30 μg transiently reduced cue/nicotine compound reinstatement after chronic self-administration (29 days). These results indicate that TCS1102 has no substantial effect on motivation for nicotine seeking following chronic self-administration and no effect after shorter periods of intake. Orexin receptor antagonists may therefore have little clinical utility against nicotine addiction. PMID:28296947

  11. A mechanistic basis for converting a receptor tyrosine kinase agonist to an antagonist

    SciTech Connect

    Tolbert, W. David; Daugherty, Jennifer; Gao, ChongFeng; Xie, Qian; Miranti, Cindy; Gherardi, Ermanno; Vande Woude, George; Xu, H. Eric

    2010-03-08

    Hepatocyte growth factor (HGF) activates the Met receptor tyrosine kinase by binding and promoting receptor dimerization. Here we describe a mechanistic basis for designing Met antagonists based on NK1, a natural variant of HGF containing the N-terminal and the first kringle domain. Through detailed biochemical and structural analyses, we demonstrate that both mouse and human NK1 induce Met dimerization via a conserved NK1 dimer interface. Mutations designed to alter the NK1 dimer interface abolish its ability to promote Met dimerization but retain full Met-binding activity. Importantly, these NK1 mutants act as Met antagonists by inhibiting HGF-mediated cell scattering, proliferation, branching, and invasion. The ability to separate the Met-binding activity of NK1 from its Met dimerization activity thus provides a rational basis for designing Met antagonists. This strategy of antagonist design may be applicable for other growth factor receptors by selectively abolishing the receptor activation ability but not the receptor binding of the growth factors.

  12. Modification of formalin-induced nociception by different histamine receptor agonists and antagonists.

    PubMed

    Farzin, Davood; Nosrati, Farnaz

    2007-01-15

    The present study evaluated the effects of different histamine receptor agonists and antagonists on the nociceptive response in the mouse formalin test. Intracerebroventricular (20-40 microg/mouse i.c.v.) or subcutaneous (1-10 mg/kg s.c.) injection of HTMT (H(1) receptor agonist) elicited a dose-related hyperalgesia in the early and late phases. Conversely, intraperitoneal (20 and 30 mg/kg i.p.) injection of dexchlorpheniramine (H(1) receptor antagonist) was antinociceptive in both phases. At a dose ineffective per se, dexchlorpheniramine (10 mg/kg i.p.) antagonized the hyperalgesia induced by HTMT (40 mug/mouse i.c.v. or 10 mg/kg s.c.). Dimaprit (H(2) receptor agonist, 30 mg/kg i.p.) and ranitidine (H(2) receptor antagonist, 20 and 40 mg/kg i.p.) reduced the nociceptive responses in the early and late phases. No significant change in the antinociceptive activity was found following the combination of dimaprit (30 mg/kg i.p.) with ranitidine (10 mg/kg i.p.). The antinociceptive effect of dimaprit (30 mg/kg i.p.) was prevented by naloxone (5 mg/kg i.p.) in the early phase or by imetit (H(3) receptor agonist, 25 mg/kg i.p.) in both early and late phases. The histamine H(3) receptor agonist imetit was hyperalgesic following i.p. administration of 50 mg/kg. Imetit-induced hyperalgesia was completely prevented by treatment with a dose ineffective per se of thioperamide (H(3) receptor antagonist, 5 mg/kg i.p.). The results suggest that histamine H(1) and H(3) receptor activations increase sensitivity to nociceptive stimulus in the formalin test.

  13. Identification of three muscarinic receptor subtypes in rat lung using binding studies with selective antagonists

    SciTech Connect

    Fryer, A.D.; El-Fakahany, E.E. )

    1990-01-01

    Heterogeneity of the muscarinic receptor population in the rat central and peripheral lung was found in competition binding experiments against ({sup 3}H)quinuclidinyl benzilate (({sup 3}H)QNB) using the selective antagonists pirenzepine, AF-DX 116 and hexahydrosiladifenidol (HHSiD). Pirenzepine displaced ({sup 3}H)QNB with low affinity from preparations of central airways indicating the absence of M{sub 1} receptors in the trachea and bronchi. Muscarinic receptors in the central airways are comprised of both M{sub 2} and M{sub 3} receptors since AF-DX 116, an M{sub 2}-selective antagonist, bound with high affinity to 70% of the available sites while HHSiD, an M{sub 3}-selective antagonist bound with high affinity to the remaining binding sites. In the peripheral lung, pirenzepine bound with high affinity to 14% of the receptor population, AF-DX 116 bound with high affinity 79% of the binding sites while HHSiD bound with high affinity to 18% of the binding sites. The presence of M{sub 1} receptors in the peripheral airways but not in the central airways was confirmed using ({sup 3}H)telenzepine, an M{sub 1} receptor ligand. ({sup 3}H)Telenzepine showed specific saturable binding to 8% of ({sup 3}H)QNB labeled binding sites in homogenates of rat peripheral lung, while there was no detectable specific binding in homogenates of rat trachea or heart.

  14. Rational Design of Potent Antagonists to the Human Growth Hormone Receptor

    NASA Astrophysics Data System (ADS)

    Fuh, Germaine; Cunningham, Brian C.; Fukunaga, Rikiro; Nagata, Shigekazu; Goeddel, David V.; Wells, James A.

    1992-06-01

    A hybrid receptor was constructed that contained the extracellular binding domain of the human growth hormone (hGH) receptor linked to the transmembrane and intracellular domains of the murine granulocyte colony-stimulating factor receptor. Addition of hGH to a myeloid leukemia cell line (FDC-P1) that expressed the hybrid receptor caused proliferation of these cells. The mechanism for signal transduction of the hybrid receptor required dimerization because monoclonal antibodies to the hGH receptor were agonists whereas their monovalent fragments were not. Receptor dimerization occurs sequentially-a receptor binds to site 1 on hGH, and then a second receptor molecule binds to site 2 on hGH. On the basis of this sequential mechanism, which may occur in many other cytokine receptors, inactive hGH analogs were designed that were potent antagonists to hGH-induced cell proliferation. Such antagonists could be useful for treating clinical conditions of hGH excess, such as acromegaly.

  15. (-) Arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β.

    PubMed

    Ogungbe, Ifedayo Victor; Crouch, Rebecca A; Demeritte, Teresa

    2014-11-24

    Lignans are important biologically active dietary polyphenolic compounds. Consumption of foods that are rich in lignans is associated with positive health effects. Using modeling tools to probe the ligand-binding pockets of molecular receptors, we found that lignans have high docking affinity for the human thyroid hormone receptor β. Follow-up experimental results show that lignans (-) arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β. The modeled complexes show key plausible interactions between the two ligands and important amino acid residues of the receptor.

  16. (−) Arctigenin and (+) Pinoresinol Are Antagonists of the Human Thyroid Hormone Receptor β

    PubMed Central

    2015-01-01

    Lignans are important biologically active dietary polyphenolic compounds. Consumption of foods that are rich in lignans is associated with positive health effects. Using modeling tools to probe the ligand-binding pockets of molecular receptors, we found that lignans have high docking affinity for the human thyroid hormone receptor β. Follow-up experimental results show that lignans (−) arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β. The modeled complexes show key plausible interactions between the two ligands and important amino acid residues of the receptor. PMID:25383984

  17. Inhibition of Morphine Tolerance and Dependence by the NMDA Receptor Antagonist MK-801

    NASA Astrophysics Data System (ADS)

    Trujillo, Keith A.; Akil, Huda

    1991-01-01

    The N-methyl-D-aspartate (NMDA) subtype of the glutamate receptor is an important mediator of several forms of neural and behavioral plasticity. The present studies examined whether NMDA receptors might be involved in the development of opiate tolerance and dependence, two examples of behavioral plasticity. The noncompetitive NMDA receptor antagonist MK-801 attenuated the development of tolerance to the analgesic effect of morphine without affecting acute morphine analgesia. In addition, MK-801 attenuated the development of morphine dependence as assessed by naloxone-precipitated withdrawal. These results suggest that NMDA receptors may be important in the development of opiate tolerance and dependence.

  18. Identification of Trisubstituted-pyrazol Carboxamide Analogs as Novel and Potent Antagonists of Farnesoid X Receptor

    PubMed Central

    Yu, Donna D.; Lin, Wenwei; Forman, Barry M.; Chen, Taosheng

    2014-01-01

    Farnesoid X receptor (FXR, NRIH4) plays a major role in the control of cholesterol metabolism. This suggests that antagonizing the transcriptional activity of FXR is a potential means to treat cholestasis and related metabolic disorders. Here we describe the synthesis, biological evaluation, and structure-activity relationship (SAR) studies of trisubstituted-pyrazol carboxamides as novel and potent FXR antagonists. One of these novel FXR antagonists, 4j has an IC50 of 7.5 nM in an FXR binding assay and 468.5 nM in a cell-based FXR antagonistic assay. Compound 4j has no detectable FXR agonistic activity or cytotoxicity. Notably, 4j is the most potent FXR antagonist identified to date; it has a promising in vitro profile and could serve as an excellent chemical tool to elucidate the biological function of FXR. PMID:24775917

  19. [Prothrombotic aldosterone action--a new side of the hormone].

    PubMed

    Gromotowicz, Anna; Osmólska, Urszula; Mantur, Maria; Szoka, Piotr; Zakrzeska, Agnieszka; Szemraj, Janusz; Chabielska, Ewa

    2010-10-18

    Recent studies have focused on a new wave of interest in aldosterone due mainly to its growing profile as a local messenger in pathology of the cardiovascular system, rather than its hormonal action. In the last few years strong evidence for a correlation between raised aldosterone level and haemostasis disturbances leading to increased risk of cardiovascular events has been provided. It has been demonstrated that aldosterone contributes to endothelial dysfunction, fibrinolytic disorders and oxidative stress augmentation. It was also shown that chronic aldosterone treatment results in enhanced experimental arterial thrombosis. Our study in a venous model of thrombosis in normotensive rats confirmed that even a short-lasting increase in aldosterone level intensified thrombus formation. One-hour aldosterone infusion shortened bleeding time; increased platelet adhesion to collagen; reduced tissue factor, thrombin activatable fibrinolysis inhibitor, and plasminogen activator inhibitor; and increased plasminogen activator plasma level. A fall in plasma nitric oxide metabolite concentration with a decrease in aortic nitric oxide synthase mRNA level was also observed. Moreover, aldosterone increased hydrogen peroxide and malonyl dialdehyde plasma concentration and augmented NADPH oxidase and superoxide dismutase aortic expression. Therefore, the mechanism of aldosterone prothrombotic action is multiple and involves primary haemostasis activation, procoagulative and antifibrinolytic action, NO bioavailability impairment and oxidative stress augmentation. The effects of aldosterone were not fully abolished by mineralocorticoid receptor blockade, suggesting the involvement of alternative mechanisms in the prothrombotic aldosterone action.

  20. Synthesis and dual histamine H₁ and H₂ receptor antagonist activity of cyanoguanidine derivatives.

    PubMed

    Sadek, Bassem; Alisch, Rudi; Buschauer, Armin; Elz, Sigurd

    2013-11-15

    Premedication with a combination of histamine H₁ receptor (H₁R) and H₂ receptor (H₂R) antagonists has been suggested as a prophylactic principle, for instance, in anaesthesia and surgery. Aiming at pharmacological hybrids combining H₁R and H₂R antagonistic activity, a series of cyanoguanidines 14-35 was synthesized by linking mepyramine-type H₁R antagonist substructures with roxatidine-, tiotidine-, or ranitidine-type H₂R antagonist moieties. N-desmethylmepyramine was connected via a poly-methylene spacer to a cyanoguanidine group as the "urea equivalent" of the H₂R antagonist moiety. The title compounds were screened for histamine antagonistic activity at the isolated ileum (H₁R) and the isolated spontaneously beating right atrium (H₂R) of the guinea pig. The results indicate that, depending on the nature of the H₂R antagonist partial structure, the highest H₁R antagonist potency resided in roxatidine-type compounds with spacers of six methylene groups in length (compound 21), and tiotidine-type compounds irrespective of the alkyl chain length (compounds 28, 32, 33), N-cyano-N'-[2-[[(2-guanidino-4-thiazolyl)methyl]thio]ethyl]-N″-[2-[N-[2-[N-(4-methoxybenzyl)-N-(pyridyl)-amino] ethyl]-N-methylamino]ethyl] guanidine (25, pKB values: 8.05 (H₁R, ileum) and 7.73 (H₂R, atrium) and the homologue with the mepyramine moiety connected by a six-membered chain to the tiotidine-like partial structure (compound 32, pKB values: 8.61 (H₁R) and 6.61 (H₂R) were among the most potent hybrid compounds. With respect to the development of a potential pharmacotherapeutic agent, structural optimization seems possible through selection of other H₁R and H₂R pharmacophoric moieties with mutually affinity-enhancing properties.

  1. Histamine H3 receptor antagonist decreases cue-induced alcohol reinstatement in mice.

    PubMed

    Nuutinen, Saara; Mäki, Tiia; Rozov, Stanislav; Bäckström, Pia; Hyytiä, Petri; Piepponen, Petteri; Panula, Pertti

    2016-07-01

    We have earlier found that the histamine H3 receptor (H3R) antagonism diminishes motivational aspects of alcohol reinforcement in mice. Here we studied the role of H3Rs in cue-induced reinstatement of alcohol seeking in C57BL/6J mice using two different H3R antagonists. Systemic administration of H3R antagonists attenuated cue-induced alcohol seeking suggesting that H3R antagonists may reduce alcohol craving. To understand how alcohol affects dopamine and histamine release, a microdialysis study was performed on C57BL/6J mice and the levels of histamine, dopamine and dopamine metabolites were measured in the nucleus accumbens. Alcohol administration was combined with an H3R antagonist pretreatment to reveal whether modulation of H3R affects the effects of alcohol on neurotransmitter release. Alcohol significantly increased the release of dopamine in the nucleus accumbens but did not affect histamine release. Pretreatment with H3R antagonist ciproxifan did not modify the effect of alcohol on dopamine release. However, histamine release was markedly increased with ciproxifan. In conclusion, our findings demonstrate that H3R antagonism attenuates cue-induced reinstatement of alcohol seeking in mice. Alcohol alone does not affect histamine release in the nucleus accumbens but H3R antagonist instead increases histamine release significantly suggesting that the mechanism by which H3R antagonist inhibits alcohol seeking found in the present study and the decreased alcohol reinforcement, reward and consumption found earlier might include alterations in the histaminergic neurotransmission in the nucleus accumbens. These findings imply that selective antagonists of H3Rs could be a therapeutic strategy to prevent relapse and possibly diminish craving to alcohol use. This article is part of the Special Issue entitled 'Histamine Receptors'.

  2. Orexin Receptor Antagonists: New Therapeutic Agents for the Treatment of Insomnia.

    PubMed

    Roecker, Anthony J; Cox, Christopher D; Coleman, Paul J

    2016-01-28

    Since its discovery in 1998, the orexin system, composed of two G-protein coupled receptors, orexins 1 and 2, and two neuropeptide agonists, orexins A and B, has captured the attention of the scientific community as a potential therapeutic target for the treatment of obesity, anxiety, and sleep/wake disorders. Genetic evidence in rodents, dogs, and humans was revealed between 1999 and 2000, demonstrating a causal link between dysfunction or deletion of the orexin system and narcolepsy, a disorder characterized by hypersomnolence during normal wakefulness. These findings encouraged efforts to discover agonists to treat narcolepsy and, alternatively, antagonists to treat insomnia. This perspective will focus on the discovery and development of structurally diverse orexin antagonists suitable for preclinical pharmacology studies and human clinical trials. The work described herein culminated in the 2014 FDA approval of suvorexant as a first-in-class dual orexin receptor antagonist for the treatment of insomnia.

  3. Bradykinin as a pain mediator: receptors are localized to sensory neurons, and antagonists have analgesic actions

    SciTech Connect

    Steranka, L.R.; Manning, D.C.; DeHaas, C.J.; Ferkany, J.W.; Borosky, S.A.; Connor, J.R.; Vavrek, R.J.; Stewart, J.M.; Snyder, S.H.

    1988-05-01

    Autoradiographic studies localize (/sup 3/H)bradykinin receptor binding sites to the substantia gelatinosa, dorsal root, and a subset of small cells in both the dorsal root and trigeminal ganglia of the guinea pig. (/sup 3/H)Bradykinin labeling is also observed over myocardinal/coronary visceral afferent fibers. The localization of (/sup 3/H)bradykinin receptors to nociceptive pathways supports a role for bradykinin in pain mediation. Several bradkykinin antagonists block bradykinin-induced acute vascular pain in the rat. The bradykinin antagonists also relieve bradykinin- and urate-induced hyperalgesia in the rat paw. These results indicate that bradykinin is a physiologic mediator of pain and that bradykinin antagonists have analgesic activity in both acute and chronic pain models.

  4. 1,7-Disubstituted oxyindoles are potent and selective EP(3) receptor antagonists.

    PubMed

    Zhou, Nian; Polozov, Alexandre M; O'Connell, Matthew; Burgeson, James; Yu, Peng; Zeller, Wayne; Zhang, Jun; Onua, Emmanuel; Ramirez, Jose; Palsdottir, Gudrun A; Halldorsdottir, Gudrun V; Andresson, Thorkell; Kiselyov, Alex S; Gurney, Mark; Singh, Jasbir

    2010-04-15

    A series of novel 1,7-disubstituted oxyindoles were shown to be potent and selective EP(3) receptor antagonists. Variation of substitution pattern at the C-3 position of indole enhanced in vitro metabolic stability of the resulting derivatives. Series 27a-c showed >1000-fold selectivity over a panel of prostanoid receptors including IP, FP, EP(1), EP(2) and EP(4). These agents also featured low CYP inhibition and good activity in the functional rat platelet aggregation assay.

  5. Synthesis and SAR studies of benzimidazolone derivatives as histamine H3-receptor antagonists.

    PubMed

    Zeng, Qingbei; Rosenblum, Stuart B; Yang, Zhaoxia; Jiang, Yueheng; McCormick, Kevin D; Aslanian, Robert G; Duguma, Luli; Kozlowski, Joseph A; Shih, Neng-Yang; Hey, John A; West, Robert E; Korfmacher, Walter A; Berlin, Michael; Boyce, Christopher W

    2013-11-01

    A novel series of benzimidazolone-containing histamine H3-receptor antagonists were prepared and their structure-activity relationship was explored. These benzimidazolone analogs demonstrate potent H3-receptor binding affinities, no P450 enzyme inhibition, and strong H3 functional activity. Compound 1o exhibits the best overall profile with H3Ki=0.95nM and rat AUC=12.9μMh.

  6. I. Effects of a Dopamine Receptor Antagonist on Fathead Minnow, Pimephales promelas ,Reproduction

    EPA Science Inventory

    This study used a 21 d fathead minnow (Pimephales promelas) reproduction assay to test the hypothesis that exposure to the dopamine 2 receptor (D2R) antagonist, haloperidol, would impair fish reproduction. Additionally, a 96 h experiment with fathead minnows and zebrafish (Danio ...

  7. Tetrahydroisoquinoline Phenols: Selective Estrogen Receptor Downregulator Antagonists with Oral Bioavailability in Rat

    PubMed Central

    2015-01-01

    A series of tetrahydroisoquinoline phenols was modified to give an estrogen receptor downregulator-antagonist profile. Optimization around the core, alkyl side chain, and pendant aryl ring resulted in compounds with subnanomolar levels of potency. The phenol functionality was shown to be required to achieve highly potent compounds, but unusually this was compatible with obtaining high oral bioavailabilities in rat. PMID:26819673

  8. A Time-course Study with the Androgen Receptor Antagonist Flutamide in Fish

    EPA Science Inventory

    Flutamide, a drug registered to treat some types of prostate cancer in humans, has been used for many years as a model androgen receptor (AR) antagonist in studies aimed at characterizing disruption of the vertebrate hypothalamic-pituitary-gonadal (HPG) axis. Various studies hav...

  9. Structure of the human M2 muscarinic acetylcholine receptor bound to an antagonist.

    PubMed

    Haga, Kazuko; Kruse, Andrew C; Asada, Hidetsugu; Yurugi-Kobayashi, Takami; Shiroishi, Mitsunori; Zhang, Cheng; Weis, William I; Okada, Tetsuji; Kobilka, Brian K; Haga, Tatsuya; Kobayashi, Takuya

    2012-01-25

    The parasympathetic branch of the autonomic nervous system regulates the activity of multiple organ systems. Muscarinic receptors are G-protein-coupled receptors that mediate the response to acetylcholine released from parasympathetic nerves. Their role in the unconscious regulation of organ and central nervous system function makes them potential therapeutic targets for a broad spectrum of diseases. The M2 muscarinic acetylcholine receptor (M2 receptor) is essential for the physiological control of cardiovascular function through activation of G-protein-coupled inwardly rectifying potassium channels, and is of particular interest because of its extensive pharmacological characterization with both orthosteric and allosteric ligands. Here we report the structure of the antagonist-bound human M2 receptor, the first human acetylcholine receptor to be characterized structurally, to our knowledge. The antagonist 3-quinuclidinyl-benzilate binds in the middle of a long aqueous channel extending approximately two-thirds through the membrane. The orthosteric binding pocket is formed by amino acids that are identical in all five muscarinic receptor subtypes, and shares structural homology with other functionally unrelated acetylcholine binding proteins from different species. A layer of tyrosine residues forms an aromatic cap restricting dissociation of the bound ligand. A binding site for allosteric ligands has been mapped to residues at the entrance to the binding pocket near this aromatic cap. The structure of the M2 receptor provides insights into the challenges of developing subtype-selective ligands for muscarinic receptors and their propensity for allosteric regulation.

  10. Structure of the human M2 muscarinic acetylcholine receptor bound to an antagonist

    SciTech Connect

    Haga, Kazuko; Kruse, Andrew C.; Asada, Hidetsugu; Yurugi-Kobayashi, Takami; Shiroishi, Mitsunori; Zhang, Cheng; Weis, William I.; Okada, Tetsuji; Kobilka, Brian K.; Haga, Tatsuya; Kobayashi, Takuya

    2012-03-15

    The parasympathetic branch of the autonomic nervous system regulates the activity of multiple organ systems. Muscarinic receptors are G-protein-coupled receptors that mediate the response to acetylcholine released from parasympathetic nerves. Their role in the unconscious regulation of organ and central nervous system function makes them potential therapeutic targets for a broad spectrum of diseases. The M2 muscarinic acetylcholine receptor (M2 receptor) is essential for the physiological control of cardiovascular function through activation of G-protein-coupled inwardly rectifying potassium channels, and is of particular interest because of its extensive pharmacological characterization with both orthosteric and allosteric ligands. Here we report the structure of the antagonist-bound human M2 receptor, the first human acetylcholine receptor to be characterized structurally, to our knowledge. The antagonist 3-quinuclidinyl-benzilate binds in the middle of a long aqueous channel extending approximately two-thirds through the membrane. The orthosteric binding pocket is formed by amino acids that are identical in all five muscarinic receptor subtypes, and shares structural homology with other functionally unrelated acetylcholine binding proteins from different species. A layer of tyrosine residues forms an aromatic cap restricting dissociation of the bound ligand. A binding site for allosteric ligands has been mapped to residues at the entrance to the binding pocket near this aromatic cap. The structure of the M2 receptor provides insights into the challenges of developing subtype-selective ligands for muscarinic receptors and their propensity for allosteric regulation.

  11. Generation of a highly diverse panel of antagonistic chicken monoclonal antibodies against the GIP receptor

    PubMed Central

    Könitzer, Jennifer D.; Pan, Qi; Augustin, Robert; Bandholtz, Sebastian; Harriman, William; Izquierdo, Shelley

    2017-01-01

    ABSTRACT Raising functional antibodies against G protein-coupled receptors (GPCRs) is challenging due to their low density expression, instability in the absence of the cell membrane's lipid bilayer and frequently short extracellular domains that can serve as antigens. In addition, a particular therapeutic concept may require an antibody to not just bind the receptor, but also act as a functional receptor agonist or antagonist. Antagonizing the glucose-dependent insulinotropic polypeptide (GIP) receptor may open up new therapeutic modalities in the treatment of diabetes and obesity. As such, a panel of monoclonal antagonistic antibodies would be a useful tool for in vitro and in vivo proof of concept studies. The receptor is highly conserved between rodents and humans, which has contributed to previous mouse and rat immunization campaigns generating very few usable antibodies. Switching the immunization host to chicken, which is phylogenetically distant from mammals, enabled the generation of a large and diverse panel of monoclonal antibodies containing 172 unique sequences. Three-quarters of all chicken-derived antibodies were functional antagonists, exhibited high-affinities to the receptor extracellular domain and sampled a broad epitope repertoire. For difficult targets, including GPCRs such as GIPR, chickens are emerging as valuable immunization hosts for therapeutic antibody discovery. PMID:28055305

  12. Evaluation of adenine as scaffold for the development of novel P2X3 receptor antagonists.

    PubMed

    Lambertucci, Catia; Sundukova, Mayya; Kachare, Dhuldeo D; Panmand, Deepak S; Dal Ben, Diego; Buccioni, Michela; Marucci, Gabriella; Marchenkova, Anna; Thomas, Ajiroghene; Nistri, Andrea; Cristalli, Gloria; Volpini, Rosaria

    2013-07-01

    Ligands that selectively block P2X3 receptors localized on nociceptive sensory fibres may be useful for the treatment of chronic pain conditions including neuropathic pain, migraine, and inflammatory pain. With the aim at exploring the suitability of adenine moiety as a scaffold for the development of antagonists of this receptor, a series of 9-benzyl-2-aminoadenine derivatives were designed and synthesized. These new compounds were functionally evaluated at rat or human P2X3 receptors expressed in human embryonic kidney (HEK) cells and on native P2X3 receptors from mouse trigeminal ganglion sensory neurons using patch clamp recording under voltage clamp configuration. The new molecules behaved as P2X3 antagonists, as they rapidly and reversibly inhibited (IC50 in the low micromolar range) the membrane currents induced via P2X3 receptor activation by the full agonist α,β-methyleneATP. Introduction of a small lipophilic methyl substituent at the 6-amino group enhanced the activity, in comparison to the corresponding unsubstituted derivative, resulting in the 9-(5-iodo-2-isopropyl-4-methoxybenzyl)-N(6)-methyl-9H-purine-2,6-diamine (24), which appears to be a good antagonist on recombinant and native P2X3 receptors with IC50 = 1.74 ± 0.21 μM.

  13. Generation of a highly diverse panel of antagonistic chicken monoclonal antibodies against the GIP receptor.

    PubMed

    Könitzer, Jennifer D; Pramanick, Shreya; Pan, Qi; Augustin, Robert; Bandholtz, Sebastian; Harriman, William; Izquierdo, Shelley

    2017-01-05

    Raising functional antibodies against G protein-coupled receptors (GPCRs) is challenging due to their low density expression, instability in the absence of the cell membrane's lipid bilayer and frequently short extracellular domains that can serve as antigens. In addition, a particular therapeutic concept may require an antibody to not just bind the receptor, but also act as a functional receptor agonist or antagonist. Antagonizing the glucose-dependent insulinotropic polypeptide (GIP) receptor may open up new therapeutic modalities in the treatment of diabetes and obesity. As such, a panel of monoclonal antagonistic antibodies would be a useful tool for in vitro and in vivo proof of concept studies. The receptor is highly conserved between rodents and humans, which has contributed to previous mouse and rat immunization campaigns generating very few usable antibodies. Switching the immunization host to chicken, which is phylogenetically distant from mammals, enabled the generation of a large and diverse panel of monoclonal antibodies containing 172 unique sequences. Three-quarters of all chicken-derived antibodies were functional antagonists, exhibited high-affinities to the receptor extracellular domain and sampled a broad epitope repertoire. For difficult targets, including GPCRs such as GIPR, chickens are emerging as valuable immunization hosts for therapeutic antibody discovery.

  14. Agonist and antagonist protect sulfhydrals in the binding site of the D-1 dopamine receptor

    SciTech Connect

    Sidhu, A.; Kebabian, J.W.; Fishman, P.H.

    1986-05-01

    An iodinated compound (/sup 125/I)-SCH 23982 (8-iodo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol) has been characterized as a specific, high affinity (Kd = 0.7 nM) ligand for the D-1 dopamine receptor. The ligand binding site of the D-1 receptor in rat striatum was inactivated by N-ethylmaleimide (NEM) in a time and concentration dependent manner. The inactivation was rapid and irreversible with a 70% net loss of binding sites. Scatchard analysis of binding to NEM-treated tissue showed a decrease both in receptor number and in radioligand affinity. The remaining receptors retained their selectivity for stereoisomers of both agonist and antagonist. Receptor occupancy by either a D-1 specific agonist or antagonist protected in a dose dependent manner the binding sites from inactivation by NEM; the agonist was more effective than the antagonist. The agonist high affinity site, however, was abolished in the absence or presence of protective compound, presumably because of inactivation of the GTP-binding component of adenylate cyclase. In this regard, there was a total loss of agonist- and forskolin-stimulated adenylate cyclase activity after NEM treatment. The authors conclude that the D-1 dopamine receptor contains NEM-sensitive sulfhydral group(s) at or near the vicinity of the ligand binding site.

  15. Theoretical analysis of somatostatin receptor 5 with antagonists and agonists for the treatment of neuroendocrine tumors.

    PubMed

    Nagarajan, Santhosh Kumar; Babu, Sathya; Madhavan, Thirumurthy

    2017-02-02

    We report on SSTR5 receptor modeling and its interaction with reported antagonist and agonist molecules. Modeling of the SSTR5 receptor was carried out using multiple templates with the aim of improving the precision of the generated models. The selective SSTR5 antagonists, agonists and native somatostatin SRIF-14 were employed to propose the binding site of SSTR5 and to identify the critical residues involved in the interaction of the receptor with other molecules. Residues Q2.63, D3.32, Q3.36, C186, Y7.34 and Y7.42 were found to be highly significant for their strong interaction with the receptor. SSTR5 antagonists were utilized to perform a 3D quantitative structure-activity relationship study. A comparative molecular field analysis (CoMFA) was conducted using two different alignment schemes, namely the ligand-based and receptor-based alignment methods. The best statistical results were obtained for ligand-based ([Formula: see text], [Formula: see text] = 0.988, noc = 4) and receptor-guided methods (docked mode 1:[Formula: see text], [Formula: see text], noc = 5), (docked mode 2:[Formula: see text] = 0.555, [Formula: see text], noc = 5). Based on CoMFA contour maps, an electropositive substitution at [Formula: see text], [Formula: see text] and [Formula: see text] position and bulky group at [Formula: see text] position are important in enhancing molecular activity.

  16. Mesenteric vascular reactivity to histamine receptor agonists and antagonists. [Dogs

    SciTech Connect

    Walus, K.M.; Fondacaro, J.D.; Jacobson, E.D.

    1981-05-01

    Response patterns of intestinal blood flow, oxygen extraction and consumption, blood flow distribution, and motility were assessed during intraarterial infusions of histamine, histamine after H1 or H2 blockade, dimaprit or dimaprit after H2 blockade. Histamine produced an initial peak response of blood flow with a slow decrease thereafter. Oxygen extraction was evenly depressed throughout the infusion, and oxygen consumption increased at the beginning. All initial responses were blocked by tripelennamine. Ranitidine, a new H2 antagonist, accelerated the decay of all responses. Dimaprit produced effects identical to those of histamine after tripelennamine. Distribution of blood flow was unchanged at the beginning of histamine infusion, but subsequently showed a shift to muscularis which was blocked by tripelennamine. Histamine usually stimulated intestinal contractions and this effect was abolished by tripelennamine. Thus, H1 stimulation, besides producing an initial vasodilation, increases oxygen uptake and redistributes flow to the muscularis.

  17. Oxycodone with an opioid receptor antagonist: A review.

    PubMed

    Davis, Mellar P; Goforth, Harold W

    2016-01-01

    The rationale for putting opioid antagonists with an agonist is to improve pain control, to reduce side effects, and/or to reduce abuse. The combination of prolonged release (PR) oxycodone and naloxone reduces constipation as demonstrated in multiple studies and has been designated a tamper-resistant opioid by the Food and Drug Administration. Bioequivalence of the combination product compared with PR oxycodone has not been established. Several of the pivotal studies provided suboptimal laxative support in the control arm of the randomized trials. Two noninferiority trials have demonstrated equivalent analgesia between PR oxycodone and the combination product at doses of less than 120 mg of oxycodone per day. There appears to be an analgesic ceiling above 80-120 mg of oxycodone per day. Safety monitoring during randomized trials was not been well described in published manuscripts. Benefits appear to be better for those with chronic noncancer pain compared with individuals with cancer when constipation was the primary outcome.

  18. In silico modelling of prostacyclin and other lipid mediators to nuclear receptors reveal novel thyroid hormone receptor antagonist properties.

    PubMed

    Perez Diaz, Noelia; Zloh, Mire; Patel, Pryank; Mackenzie, Louise S

    2016-01-01

    Prostacyclin (PGI2) is a key mediator involved in cardiovascular homeostasis, acting predominantly on two receptor types; cell surface IP receptor and cytosolic peroxisome proliferator activated receptor (PPAR) β/δ. Having a very short half-life, direct methods to determine its long term effects on cells is difficult, and little is known of its interactions with nuclear receptors. Here we used computational chemistry methods to investigate the potential for PGI2, beraprost (IP receptor agonist), and GW0742 (PPARβ/δ agonist), to bind to nuclear receptors, confirmed with pharmacological methods. In silico screening predicted that PGI2, beraprost, and GW0742 have the potential to bind to different nuclear receptors, in particular thyroid hormone β receptor (TRβ) and thyroid hormone α receptor (TRα). Docking analysis predicts a binding profile to residues thought to have allosteric control on the TR ligand binding site. Luciferase reporter assays confirmed that beraprost and GW0742 display TRβ and TRα antagonistic properties; beraprost IC50 6.3 × 10(-5)mol/L and GW0742 IC50 4.9 × 10(-6) mol/L. Changes to triiodothyronine (T3) induced vasodilation of rat mesenteric arteries measured on the wire myograph were measured in the presence of the TR antagonist MLS000389544 (10(-5) mol/L), beraprost (10(-5) mol/L) and GW0742 (10(-5) mol/L); all significantly inhibited T3 induced vasodilation compared to controls. We have shown that both beraprost and GW0742 exhibit TRβ and TRα antagonist behaviour, and suggests that PGI2 has the ability to affect the long term function of cells through binding to and inactivating thyroid hormone receptors.

  19. TNF-α receptor antagonist attenuates isoflurane-induced cognitive impairment in aged rats

    PubMed Central

    YANG, NENGLI; LIANG, YAFENG; YANG, PEI; WANG, WEIJIAN; ZHANG, XUEZHENG; WANG, JUNLU

    2016-01-01

    Postoperative cognitive dysfunction (POCD), a common clinical in aged patients, is characterized by deficits in cognitive functions in patients following anesthesia and surgery. It has been demonstrated that isoflurane may lead to cognitive impairment in aged rats; however, effective clinical interventions for preventing this disorder are limited. Tumor necrosis factor (TNF)-α has been suggested to be involved in neuroinflammation as well as the development of POCD. Accordingly, the present study aimed to investigate whether TNF-α signaling is involved in the isoflurane-induced cognitive impairment in aged rats, and whether TNF-α receptor antagonist are able to attenuate isoflurane-induced cognitive impairment in aged rats. A population of 20-month-old rats were administered TNF-α receptor antagonist R-7050 or an equal volume of saline by intraperitoneal injection 12 h prior to exposure to isoflurane to model cognitive impairment following anesthesia in old patients. Then the rats were exposed to 1.3% isoflurane for 4 h. In the control group, rats showed impaired cognitive functions evaluated by Morris water maze assay after isoflurane exposure. Furthermore, isoflurane exposure induced marked upregulation of proinflammatory cytokines, including interleukin (IL)-1β, TNF-α, IL-6 and IL-8 in the hippocampus tissue. In the experimental group, intracisternal administration of TNF-α receptor antagonist R-7050 significantly attenuated isoflurane-induced cognitive impairment and upregulation of proinflammatory cytokines. Further investigation revealed that intracisternal administration of TNF-α receptor antagonist R-7050 notably suppressed isoflurane-induced activation of NF-κB and MAPK signaling. Collectively, the present results suggest that TNF-α receptor antagonist may serve as a potential agent for the prevention of anesthesia-induced cognitive decline in aged patients. PMID:27347079

  20. Therapeutic potential of the chemokine receptor CXCR4 antagonists as multifunctional agents.

    PubMed

    Tsutsumi, Hiroshi; Tanaka, Tomohiro; Ohashi, Nami; Masuno, Hiroyuki; Tamamura, Hirokazu; Hiramatsu, Kenichi; Araki, Takanobu; Ueda, Satoshi; Oishi, Shinya; Fujii, Nobutaka

    2007-01-01

    The chemokine receptor CXCR4 possesses multiple critical functions in normal and pathologic physiology. CXCR4 is a G-protein-coupled receptor that transduces signals of its endogenous ligand, the chemokine CXCL12 (stromal cell-derived factor-1, SDF-1). The interaction between CXCL12 and CXCR4 plays an important role in the migration of progenitors during embryologic development of the cardiovascular, hemopoietic, central nervous systems, and so on. This interaction is also known to be involved in several intractable disease processes, including HIV infection, cancer cell metastasis, leukemia cell progression, rheumatoid arthritis (RA), and pulmonary fibrosis. It is conjectured that this interaction may be a critical therapeutic target in all of these diseases, and several CXCR4 antagonists have been proposed as potential drugs. Fourteen-mer peptides, T140 and its analogues, were previously developed in our laboratory as specific CXCR4 antagonists that were identified as HIV-entry inhibitors, anti-cancer-metastatic agents, anti-chronic lymphocytic/acute lymphoblastic leukemia agents, and anti-RA agents. Cyclic pentapeptides, such as FC131 [cyclo(D-Tyr-Arg-Arg-L-3-(2-naphthyl)alanine-Gly)], were also previously found as CXCR4 antagonist leads based on pharmacophores of T140. This review article describes the elucidation of multiple functions of CXCR4 antagonists and the development of a number of low-molecular weight CXCR4 antagonists involving FC131 analogues and other compounds with different scaffolds including linear-type structures.

  1. Radiosensitizing Effect of P2X7 Receptor Antagonist on Melanoma in vitro and in vivo.

    PubMed

    Tanamachi, Keisuke; Nishino, Keisuke; Mori, Natsuki; Suzuki, Toshihiro; Tanuma, Sei-Ichi; Abe, Ryo; Tsukimoto, Mitsutoshi

    2017-03-24

    Melanoma is highly malignant, and generally exhibits radioresistance, responding poorly to radiation therapy. We previously reported that activation of P2X7, P2Y6, and P2Y12 receptors is involved in the DNA damage response after γ-irradiation of human lung adenocarcinoma A549 cells. However, it is not clear whether these receptors are also involved in the case of melanoma cells, although P2X7 receptor is highly expressed in various cancers, including melanoma. Here, we show that P2X7 receptor antagonist enhances radiation-induced cytotoxicity in B16 melanoma cells in vitro and in vivo. We confirmed that these cells express P2X7 receptor mRNA and exhibit P2X7 receptor-mediated activities, such as ATP-induced pore formation and cytotoxicity. We further examined the radiosensitizing effect of P2X7 receptor antagonist Brilliant Blue G (BBG) in vitro by colony formation assay of B16 cells. γ-Irradiation dose-dependently reduced cell survival, and pretreatment with BBG enhanced the radiation-induced cytotoxicity. BBG pretreatment also decreased the number of DNA repair foci in nuclei, supporting involvement of P2X7 receptor in the DNA damage response. Finally, we investigated the radiosensitizing effect of BBG on B16 melanoma cells inoculated into the hind footpad of C57BL/6 mice. Neither 1 Gy γ-irradiation alone nor BBG alone suppressed the increase of tumor volume, but the combination of irradiation and BBG significantly suppressed tumor growth. Our results suggest that P2X7 receptor antagonist BBG has a radiosensitizing effect in melanoma in vitro and in vivo. BBG, which is used as a food coloring agent, appears to be a promising candidate as a radiosensitizer.

  2. Mixed antagonistic effects of the ginkgolides at recombinant human ρ1 GABAC receptors.

    PubMed

    Huang, Shelley H; Lewis, Trevor M; Lummis, Sarah C R; Thompson, Andrew J; Chebib, Mary; Johnston, Graham A R; Duke, Rujee K

    2012-11-01

    The diterpene lactones of Ginkgo biloba, ginkgolides A, B and C are antagonists at a range of Cys-loop receptors. This study examined the effects of the ginkgolides at recombinant human ρ(1) GABA(C) receptors expressed in Xenopus oocytes using two-electrode voltage clamp. The ginkgolides were moderately potent antagonists with IC(50)s in the μM range. At 10 μM, 30 μM and 100 μM, the ginkgolides caused rightward shifts of GABA dose-response curves and reduced maximal GABA responses, characteristic of noncompetitive antagonists, while the potencies showed a clear dependence on GABA concentration, indicating apparent competitive antagonism. This suggests that the ginkgolides exert a mixed-type antagonism at the ρ(1) GABA(C) receptors. The ginkgolides did not exhibit any obvious use-dependent inhibition. Fitting of the data to a number of kinetic schemes suggests an allosteric inhibition as a possible mechanism of action of the ginkgolides which accounts for their inhibition of the responses without channel block or use-dependent inhibition. Kinetic modelling predicts that the ginkgolides exhibit saturation of antagonism at high concentrations of GABA, but this was only partially observed for ginkgolide B. It also suggests that there may be different binding sites in the closed and open states of the receptor, with a higher affinity for the receptor in the closed state.

  3. Central administration of GPR55 receptor agonist and antagonist modulates anxiety-related behaviors in rats.

    PubMed

    Rahimi, Abbasali; Hajizadeh Moghaddam, Akbar; Roohbakhsh, Ali

    2015-04-01

    G-protein-coupled receptor 55 (GPR55) has been proposed as an atypical cannabinoid receptor, which is activated by lysophosphatidylinositols and some synthetic or endogenous cannabinoid molecules. The exact role of GPR55 receptors in the central nervous system especially in anxiety needs to be evaluated. In this study, the effects of intracerebroventricular (i.c.v.) administration of agonist and antagonist of GPR55 receptor on anxiety-related behaviors in rats were investigated. Here, O-1602 (GPR55 agonist) at the doses of 0.2, 1, and 5 μg/rat increased %OAT and %OAE but not the locomotor activity, showing an anxiolytic response, whereas i.c.v. injection of ML193 (GPR55 antagonist) at the doses of 0.1 and 1 μg/rat increased anxiety-like behaviors while causing locomotor impairment. The antagonistic effect of ML193 on the anxiolytic-like effect of O-1602 was also evaluated. The results showed that ML193 decreased the anxiolytic-like effect of O-1602. Based on these results, it may be concluded that central GPR55 may have a role in modulation of anxiety-like behaviors in rats. Further experiments are needed to elucidate the exact role of these receptors in anxiety.

  4. Rodent antinociception following acute treatment with different histamine receptor agonists and antagonists.

    PubMed

    Farzin, Davood; Asghari, Ladan; Nowrouzi, Mahvash

    2002-06-01

    The effects of different histamine receptor agonists and antagonists on the nociceptive threshold were investigated in mice by two different kinds of noxious stimuli: thermal (hot plate) and chemical (acetic acid-induced abdominal writhing). Intracerebroventricular (icv) injection of the histamine H(1) receptor agonist, HTMT (6-[2-(4-imidazolyl)ethylamino]-N-(4-trifluoromethylphenyl) heptanecarboxamide) (50 microg/mouse), produced a hypernociception in the hot plate and writhing tests. Conversely, intraperitoneal (ip) injection of dexchlorpheniramine (30 and 40 mg/kg) and diphenhydramine (20 and 40 mg/kg) increased the pain threshold in both tests. The histamine H(2) receptor agonist, dimaprit (50 and 100 microg/mouse icv), or antagonist, ranitidine (50 and 100 microg/mouse icv), raised the pain threshold in both hot plate and writhing tests. In the mouse hot plate test, the histamine H(3) receptor agonist, imetit (50 mg/kg ip), reduced the pain threshold, while the histamine H(3) receptor antagonist, thioperamide (10 and 20 mg/kg ip), produced an antinociception. The hypernociceptive effects of HTMT and imetit were antagonized by dexchlorpheniramine (20 mg/kg ip) and thioperamide (5 mg/kg ip), respectively. The results suggest that histaminergic mechanisms may be involved in the modulation of nociceptive stimuli.

  5. Dopamine D3 Receptor Antagonists as Potential Therapeutics for the Treatment of Neurological Diseases

    PubMed Central

    Maramai, Samuele; Gemma, Sandra; Brogi, Simone; Campiani, Giuseppe; Butini, Stefania; Stark, Holger; Brindisi, Margherita

    2016-01-01

    D3 receptors represent a major focus of current drug design and development of therapeutics for dopamine-related pathological states. Their close homology with the D2 receptor subtype makes the development of D3 selective antagonists a challenging task. In this review, we explore the relevance and therapeutic utility of D3 antagonists or partial agonists endowed with multireceptor affinity profile in the field of central nervous system disorders such as schizophrenia and drug abuse. In fact, the peculiar distribution and low brain abundance of D3 receptors make them a valuable target for the development of drugs devoid of motor side effects classically elicited by D2 antagonists. Recent research efforts were devoted to the conception of chemical templates possibly endowed with a multi-target profile, especially with regards to other G-protein-coupled receptors (GPCRs). A comprehensive overview of the recent literature in the field is herein provided. In particular, the evolution of the chemical templates has been tracked, according to the growing advancements in both the structural information and the refinement of the key pharmacophoric elements. The receptor/multireceptor affinity and functional profiles for the examined compounds have been covered, together with their most significant pharmacological applications. PMID:27761108

  6. N-Methyl-d-aspartate Receptor Antagonists Have Variable Affect in 3-Nitropropionic Acid Toxicity

    PubMed Central

    Carbery, Timothy; Geddes, James W.

    2013-01-01

    There is accumulating evidence that excitotoxicity and oxidative stress resulting from excessive activation of glutamate (N-methyl-d-aspartate) NMDA receptors are major participants in striatal degeneration associated with 3-nitropropionic acid (3NP) administration. Although excitotoxic and oxidative mechanisms are implicated in 3NP toxicity, there are conflicting reports as to whether NMDA receptor antagonists attenuate or exacerbate the 3NP-induced neurodegeneration. In the present study, we investigated the involvement of NMDA receptors in striatal degeneration, protein oxidation and motor impairment following systemic 3NP administration. We examined whether NMDA receptor antagonists, memantine and ifenprodil, influence the neurotoxicity of 3NP. The development of striatal lesion and protein oxidation following 3NP administration is delayed by memantine but not affected by ifenprodil. However, in behavioral experiments, memantine failed to improve and ifenprodil exacerbated the motor deficits associated with 3NP toxicity. Together, these findings suggest caution in the application of NMDA receptor antagonists as a neuroprotective agent in neurodegenerative disorders associated with metabolic impairment. PMID:18688711

  7. N-methyl-D-aspartate receptor antagonists have variable affect in 3-nitropropionic acid toxicity.

    PubMed

    Nasr, Payman; Carbery, Timothy; Geddes, James W

    2009-03-01

    There is accumulating evidence that excitotoxicity and oxidative stress resulting from excessive activation of glutamate (N-methyl-D-aspartate) NMDA receptors are major participants in striatal degeneration associated with 3-nitropropionic acid (3NP) administration. Although excitotoxic and oxidative mechanisms are implicated in 3NP toxicity, there are conflicting reports as to whether NMDA receptor antagonists attenuate or exacerbate the 3NP-induced neurodegeneration. In the present study, we investigated the involvement of NMDA receptors in striatal degeneration, protein oxidation and motor impairment following systemic 3NP administration. We examined whether NMDA receptor antagonists, memantine and ifenprodil, influence the neurotoxicity of 3NP. The development of striatal lesion and protein oxidation following 3NP administration is delayed by memantine but not affected by ifenprodil. However, in behavioral experiments, memantine failed to improve and ifenprodil exacerbated the motor deficits associated with 3NP toxicity. Together, these findings suggest caution in the application of NMDA receptor antagonists as a neuroprotective agent in neurodegenerative disorders associated with metabolic impairment.

  8. In dermographic urticaria H2 receptor antagonists have a small but therapeutically irrelevant additional effect compared with H1 antagonists alone.

    PubMed

    Sharpe, G R; Shuster, S

    1993-11-01

    Two studies of the additional effect of an H2 receptor antagonist when given in combination with an H1 antagonist were undertaken in dermographic urticaria. Using a randomized, double-blind, crossover design in 19 patients, a combination of cetirizine (10 mg at night) and ranitidine (150 mg twice daily) was compared with a combination of cetirizine (10 mg at night) and placebo. The addition of ranitidine did not produce any significant difference in linear analogue scores for weal, itch or sleep disturbance. There was a significant depression of the frictional force/wealing response curve with an increase in wealing threshold (P < 0.0001) following the addition of H2 blockade. The wealing threshold was 54.7 +/- 4.4 (mean +/- SEM) g/mm2 for the H1 antagonist alone, and 73.2 +/- 5.7 for the combination of H1 and H2 antagonists. In a second similar study involving nine different patients, comparing terfenadine (120 mg twice daily) with a combination of terfenadine and ranitidine (150 mg twice daily), the weal threshold was 59.8 +/- 6.6 for the H1 antagonist alone, and 73.0 +/- 6.4 for the combination of H1 and H2 antagonists. Thus, in dermographic urticaria, adding an H2 antagonist to treatment with a potent H1 antagonist gives a small, significant reduction in wealing response, but no symptomatic benefit. We conclude that involvement of the H2 receptor in this urticarial disease is minimal, and does not justify the use of H2 receptor antagonists.

  9. Identification of a GPER/GPR30 Antagonist with Improved Estrogen Receptor Counterselectivity

    PubMed Central

    Dennis, Megan K.; Field, Angela S.; Burai, Ritwik; Ramesh, Chinnasamy; Petrie, Whitney K.; Bologa, Cristian G.; Oprea, Tudor I.; Yamaguchi, Yuri; Hayashi, Shin-ichi; Sklar, S. Larry A.; Hathaway, Helen J.; Arterburn, Jeffrey B.; Prossnitz, Eric R.

    2011-01-01

    GPER/GPR30 is a seven-transmembrane G protein-coupled estrogen receptor that regulates many aspects of mammalian biology and physiology. We have previously described both a GPER-selective agonist G-1 and antagonist G15 based on a tetrahydro-3H-cyclopenta[c]quinoline scaffold. The antagonist lacks an ethanone moiety that likely forms important hydrogen bonds involved in receptor activation. Computational docking studies suggested that the lack of the ethanone substituent in G15 could minimize key steric conflicts, present in G-1, that limit binding within the ERα ligand binding pocket. In this report, we identify low-affinity cross-reactivity of the GPER antagonist G15 to the classical estrogen receptor ERα. To generate an antagonist with enhanced selectivity, we therefore synthesized an isosteric G-1 derivative, G36, containing an isopropyl moiety in place of the ethanone moiety. We demonstrate that G36 shows decreased binding and activation of ERα, while maintaining its antagonist profile towards GPER. G36 selectively inhibits estrogen-mediated activation of PI3K by GPER but not ERα. It also inhibits estrogen- and G-1-mediated calcium mobilization as well as ERK1/2 activation, with no effect on EGF-mediated ERK1/2 activation. Similar to G15, G36 inhibits estrogen- and G-1-stimulated proliferation of uterine epithelial cells in vivo. The identification of G36 as a GPER antagonist with improved ER counterselectivity represents a significant step towards the development of new highly selective therapeutics for cancer and other diseases. PMID:21782022

  10. Histamine H3 receptor antagonists: from target identification to drug leads.

    PubMed

    Bonaventure, P; Letavic, M; Dugovic, C; Wilson, S; Aluisio, L; Pudiak, C; Lord, B; Mazur, C; Kamme, F; Nishino, S; Carruthers, N; Lovenberg, T

    2007-04-15

    The successful cloning and functional expression of the histamine H(3) receptor in the late 1990 s has greatly facilitated our efforts to identify small molecule, non-imidazole based compounds to permit the evaluation of H(3) antagonists in models of CNS disorders. High-throughput screening identified several series of lead compounds, including a series of imidazopyridines, which led to JNJ-6379490, a compound with high affinity for the human H(3) receptor. Analysis of structural features common to several series of non-imidazole H(3) receptor ligands resulted in a pharmacophore model. This model led to the design of JNJ-5207852, a diamine-based H(3) antagonist with good in vitro and in vivo efficacy but with an undesirable long half-life. However, further modifications of the template provided an understanding of the effect of structural modifications on pharmacokinetic properties, ultimately affording several additional series of compounds including JNJ-10181457, a compound with an improved pharmacokinetic profile. These compounds allowed in vivo pharmacological evaluation to show that H(3) antagonists promote wakefulness, but unlike modafinil and classical psychostimultants, they do not increase locomotor activity or produce any alteration of the EEG power spectral activity in rats. H(3) antagonists also increase extracellular acetylcholine and norepinephrine but not dopamine in rat frontal cortex and show efficacy in various models of learning-memory deficit. In addition, cFos immunoreactivity studies show H(3) antagonists activate neuronal cells in restricted rat brain regions in contrast to widespread activation after modafinil or amphetamine treatment. Therefore, H(3) antagonists are promising clinical candidates for the treatment of excessive day time sleepiness and/or cognitive disorders.

  11. Therapeutic Opportunities for Caffeine and A2A Receptor Antagonists in Retinal Diseases.

    PubMed

    Boia, Raquel; Ambrósio, António Francisco; Santiago, Ana Raquel

    2016-01-01

    Caffeine, the major component of coffee, is the most consumed psychostimulant in the world. Caffeine is an adenosine analog and acts as a nonselective adenosine receptor antagonist. The majority of the effects of caffeine are mainly mediated by the blockade of adenosine receptors, and the proved neuroprotective effects of caffeine in brain disorders have been mimicked by the blockade of adenosine A2A receptor (A2AR). A growing body of evidence demonstrates that microglia-mediated neuroinflammation plays a key role in the pathophysiology of brain and retinal diseases. Moreover, the control of microglia reactivity by blocking A2AR has been proposed to be the mechanism underlying the observed protective effects of caffeine. Hence, it is conceivable that caffeine and A2AR antagonists offer therapeutic value for the treatment of retinal diseases, mainly those involving microglia-mediated neuroinflammation.

  12. Neurokinin-1 receptor antagonists for chemotherapy-induced nausea and vomiting.

    PubMed

    Aziz, Fahad

    2012-07-01

    Chemotherapy can be a life-prolonging treatment for many cancer patients, but it is often associated with profound nausea and vomiting that is so distressing that patients may delay or decline treatment to avoid these side effects. The discovery of several NK1 receptor antagonists is a big revolution to dealt this problem. NK1 receptor antagonists prevent both acute and delayed chemotherapy-induced nausea and vomiting (CINV). These agents act centrally at NK-1 receptors in vomiting centers within the central nervous system to block their activation by substance P released as an unwanted consequence of chemotherapy. By controlling nausea and vomiting, these agents help improve patients' daily living and their ability to complete multiple cycles of chemotherapy. They are effective for both moderately and highly emetogenic chemotherapy regimens. Their use might be associated with increased infection rates; however, additional appraisal of specific data from RCTs is needed.

  13. Major Depressive Disorder and Kappa Opioid Receptor Antagonists

    PubMed Central

    Li, Wei; Sun, Huijiao; Chen, Hao; Yang, Xicheng; Xiao, Li; Liu, Renyu; Shao, Liming; Qiu, Zhuibai

    2016-01-01

    Major depressive disorder (MDD) is a common psychiatric disease worldwide. The clinical use of tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs)/serotonin–norepinephrine reuptake inhibitor (SNRIs) for this condition have been widely accepted, but they were challenged by unacceptable side-effects, potential drug-drug interactions (DDIs) or slow onset/lack of efficacy. The endogenous opioid system is involved in stress and emotion regulatory processes and its role in MDD has been implicated. Although several KOR antagonists including JDTic and PF-04455242 were discontinued in early clinical trials, ALKS 5461 and CERC-501(LY-2456302) survived and entered into Phase-III and Phase-II trials, respectively. Considering the efficacy and safety of early off-label use of buprenorphine in the management of the treatment-resistant depression (TRD), it will be not surprising to predict the potential success of ALKS 5461 (a combination of buprenorphine and ALKS-33) in the near future. Moreover, CERC-501 will be expected to be available as monotherapy or adjuvant therapy with other first-line antidepressants in the treatment of TRD, if ongoing clinical trials continue to provide positive benefit-risk profiles. Emerging new researches might bring more drug candidates targeting the endogenous opioid system to clinical trials to address current challenges in MDD treatment in clinical practice. PMID:27213169

  14. Two affinities for a single antagonist at the neuronal NK1 tachykinin receptor: evidence from quantitation of receptor endocytosis

    PubMed Central

    Jenkinson, Karl M; Southwell, Bridget R; Furness, John B

    1999-01-01

    In smooth muscle contractility assays, many NK1 receptor (NK1r) antagonists inhibit responses to the neurotransmitter, substance P (SP), and its analogue, septide, with markedly different potency, leading to the proposal that there is a septide-preferring receptor related to the NK1r.We used fluorescence immunohistochemistry and confocal microscopy to visualize agonist-induced NK1r endocytosis and analyse agonist/antagonist interactions at native NK1r in neurons of the myenteric plexus of guinea-pig ileum.SP and septide gave sigmoid log concentration-response curves and were equipotent in inducing NK1r endocytosis.The NK1r antagonists, CP-99994 (2S,3S)-3-(2-methoxybenzyl)amino-2-phenylpiperidine dihydrochloride and MEN-10581, cyclo(Leuψ[CH2NH]Lys(benzyloxycarbonyl)-Gln-Trp-Phe-βAla) were both more potent in inhibiting endocytosis (50× and 8× greater respectively) against septide than against SP.The results suggest that SP and septide interact differently with the NK1r, and that a single antagonist can exhibit different affinities at a single NK1r population, depending on the agonist with which it competes. Thus it may not be necessary to posit a separate septide-preferring tachykinin receptor. PMID:10051129

  15. Methylnaltrexone, a novel peripheral opioid receptor antagonist for the treatment of opioid side effects.

    PubMed

    Yuan, Chun-Su; Israel, Robert J

    2006-05-01

    Methylnaltrexone is an investigational peripheral opioid receptor antagonist, a quaternary derivative of naltrexone. Methylnaltrexone has greater polarity and lower lipid solubility, thus it does not cross the blood-brain barrier in humans. Methylnaltrexone offers the therapeutic potential to block or reverse the undesired side effects of opioids that are mediated by receptors located in the periphery (e.g., in the gastrointestinal tract), without affecting analgesia or precipitating the opioid withdrawal symptoms that are predominantly mediated by receptors in the CNS. This article reviews preclinical studies and clinical opioid bowel dysfunction trial data, and briefly discusses other potential roles of this compound in clinical practice.

  16. Effect of iontophoretical application of NK1 receptor antagonists on pulpal blood flow in cats.

    PubMed

    Kim, Young-Kyung; Chu, Wan-sik; Lee, Ho-Jeong; Ahn, Dong-Kuk; Kim, Sung Kyo

    2005-09-01

    The influence of NK1 receptor antagonists applied iontophoretically on pulpal blood flow (PBF) was investigated. Along with substance P (SP, 0.8 approximately 20.0 ng/kg) administration to the canine pulp through the catheterized lingual artery, two NK1 receptor antagonists, [D-Pro2,D-Trp7,9]-SP and [D-Pro2,D-Phe7,D-Trp9]-SP (0.2 approximately 3.4 mM) were applied iontophoretically (cathodal current, 0.02 approximately 0.1 mA, 1 min) to the prepared class V dentinal cavity of ipsilateral teeth in 11 generally anesthetized cats. A paired t-test showed that SP administration caused significant increases of PBF (p < 0.05) without changing systemic blood pressure, and that SP and SP antagonist administration caused significantly less increase of PBF than in control of SP and 0.9% saline administration (p < 0.05). These data provide evidence that the iontophoretic application of NK1 receptor antagonists effectively attenuates SP-induced vasodilatation and show the possibility of their use in the control of neurogenic inflammation in the dental pulp.

  17. Structure-based discovery of antagonists of nuclear receptor LRH-1.

    PubMed

    Benod, Cindy; Carlsson, Jens; Uthayaruban, Rubatharshini; Hwang, Peter; Irwin, John J; Doak, Allison K; Shoichet, Brian K; Sablin, Elena P; Fletterick, Robert J

    2013-07-05

    Liver receptor homolog 1 (nuclear receptor LRH-1, NR5A2) is an essential regulator of gene transcription, critical for maintenance of cell pluripotency in early development and imperative for the proper functions of the liver, pancreas, and intestines during the adult life. Although physiological hormones of LRH-1 have not yet been identified, crystallographic and biochemical studies demonstrated that LRH-1 could bind regulatory ligands and suggested phosphatidylinositols as potential hormone candidates for this receptor. No synthetic antagonists of LRH-1 are known to date. Here, we identify the first small molecule antagonists of LRH-1 activity. Our search for LRH-1 modulators was empowered by screening of 5.2 million commercially available compounds via molecular docking followed by verification of the top-ranked molecules using in vitro direct binding and transcriptional assays. Experimental evaluation of the predicted ligands identified two compounds that inhibit the transcriptional activity of LRH-1 and diminish the expression of the receptor's target genes. Among the affected transcriptional targets are co-repressor SHP (small heterodimer partner) as well as cyclin E1 (CCNE1) and G0S2 genes that are known to regulate cell growth and proliferation. Treatments of human pancreatic (AsPC-1), colon (HT29), and breast adenocarcinoma cells T47D and MDA-MB-468 with the LRH-1 antagonists resulted in the receptor-mediated inhibition of cancer cell proliferation. Our data suggest that specific antagonists of LRH-1 could be used as specific molecular probes for elucidating the roles of the receptor in different types of malignancies.

  18. Development of β-amino-carbonyl compounds as androgen receptor antagonists

    PubMed Central

    Zhang, Zhi-yun; Zhu, Yan-hui; Zhou, Cai-hong; Liu, Qing; Lu, Hui-li; Ge, Yun-jun; Wang, Ming-wei

    2014-01-01

    Aim: Androgen receptor (AR) antagonists have proven to be useful in the early control of prostate cancer. The aim of this study was to identify and characterize a novel β-amino-carbonyl-based androgen receptor antagonist. Methods: Different isomers of the β-amino-carbonyl compounds were obtained by chiral separation. The bioactivities of the isomers were evaluated by AR nuclear translocation, mammalian two-hybrid, competitive receptor binding and cell proliferation assays. The expression of genes downstream of AR was analyzed with real-time PCR. The therapeutic effects on tumor growth in vivo were observed in male SCID mice bearing LNCaP xenografts. Results: Compound 21 was previously identified as an AR modulator by the high-throughput screening of a diverse compound library. In the present study, the two isomers of compound 21, termed compounds 21-1 and 21-2, were characterized as partial AR agonists in terms of androgen-induced AR nuclear translocation, prostate-specific antigen expression and cell proliferation. Further structural modifications led to the discovery of a androgen receptor antagonist (compound 6012), which blocked androgen receptor nuclear translocation, androgen-responsive gene expression and androgen-dependent LNCaP cell proliferation. Four stereoisomers of compound 6012 were isolated, and their bioactivities were assessed. The pharmacological effects of 6012, including AR binding, androgen-induced AR translocation, NH2- and COOH-terminal interaction, growth inhibition of LNCaP cells in vitro and LNCaP xenograft growth in nude mice, were mainly restricted to isomer 6012-4 (1R, 3S). Conclusion: Compound 6012-4 was determined to be a novel androgen receptor antagonist with prostate cancer inhibitory activities comparable to bicalutamide both in vitro and in vivo. PMID:24786235

  19. Serotonin receptor antagonists discriminate between PKA- and PKC-mediated plasticity in aplysia sensory neurons.

    PubMed

    Dumitriu, Bogdan; Cohen, Jonathan E; Wan, Qin; Negroiu, Andreea M; Abrams, Thomas W

    2006-04-01

    Highly selective serotonin (5-hydroxytryptamine, 5-HT) receptor antagonists developed for mammals are ineffective in Aplysia due to the evolutionary divergence of neurotransmitter receptors and because the higher ionic strength of physiological saline for marine invertebrates reduces antagonist affinity. It has therefore been difficult to identify antagonists that specifically block individual signaling cascades initiated by 5-HT. We studied two broad-spectrum 5-HT receptor antagonists that have been characterized biochemically in Aplysia CNS: methiothepin and spiperone. Methiothepin is highly effective in inhibiting adenylyl cyclase (AC)-coupled 5-HT receptors in Aplysia. Spiperone, which blocks phospholipase C (PLC)-coupled 5-HT receptors in mammals, does not block AC-coupled 5-HT receptors in Aplysia. In electrophysiological studies, we explored whether methiothepin and spiperone can be used in parallel to distinguish between the AC-cAMP and PLC-protein kinase C (PKC) modulatory cascades that are initiated by 5-HT. 5-HT-induced broadening of the sensory neuron action potential in the presence of tetraethylammonium/nifedipine, which is mediated by modulation of the S-K+ currents, was used an assay for the AC-cAMP cascade. Spike broadening initiated by 5 microM 5-HT was unaffected by 100 microM spiperone, whereas it was effectively blocked by 100 microM methiothepin. Facilitation of highly depressed sensory neuron-to-motor neuron synapses by 5-HT was used as an assay for the PLC-PKC cascade. Spiperone completely blocked facilitation of highly depressed synapses by 5 microM 5-HT. In contrast, methiothepin produced a modest, nonsignificant, reduction in the facilitation of depressed synapses. Interestingly, these experiments revealed that the PLC-PKC cascade undergoes desensitization during exposure to 5-HT.

  20. Correlation between the plasma concentration of mepirodipine and its occupancy of Ca2+ antagonist receptors in rats.

    PubMed

    Yamada, S; Matsuoka, Y; Kimura, R

    1993-09-01

    The relationship between the plasma concentration of mepirodipine (1,4-dihydropyridine Ca2+ antagonist) and its occupancy of cardiac and cerebral Ca2+ antagonist receptors in rats has been characterized by a radioreceptor assay technique using (+)-[3H]PN 200-110. Oral administration of mepirodipine in rats produced a dose-dependent and sustained decrease in the number of specific (+)-[3H]PN 200-110 binding sites in both tissues, and the effect was more pronounced in the cardiac tissue than in the cerebral cortex. The occupancy of cardiac and cerebral Ca2+ antagonist receptors by mepirodipine correlated well with its plasma concentration, whereas a 20-fold higher plasma concentration of this drug was necessary to occupy Ca2+ antagonist receptors in the cerebral cortex. Thus, these data suggest that mepirodipine occupies Ca2+ antagonist receptors in cardiovascular tissue selectively over those in brain tissue.

  1. Aldosterone does not modify gene expression in human endothelial cells.

    PubMed

    Verhovez, A; Williams, T A; Morello, F; Monticone, S; Brizzi, M F; Dentelli, P; Fallo, F; Fabris, B; Amenta, F; Gomez-Sanchez, C; Veglio, F; Mulatero, P

    2012-03-01

    The toxic effects of aldosterone on the vasculature, and in particular on the endothelial layer, have been proposed as having an important role in the cardiovascular pathology observed in mineralocorticoid-excess states. In order to characterize the genomic molecular mechanisms driving the aldosterone-induced endothelial dysfunction, we performed an expression microarray on transcripts obtained from both human umbilical vein endothelial cells and human coronary artery endothelial cells stimulated with 10 - 7 M aldosterone for 18 h. The results were then subjected to qRT-PCR confirmation, also including a group of genes known to be involved in the control of the endothelial function or previously described as regulated by aldosterone. The state of activation of the mineralocorticoid receptor was investigated by means of a luciferase-reporter assay using a plasmid encoding a mineralocorticoid and glucocorticoid-sensitive promoter. Aldosterone did not determine any significant change in gene expression in either cell type both in the microarray and in the qRT-PCR analysis. The luciferase-reporter assay showed no activation of the mineralocorticoid receptor following aldosterone stimulation. The status of nonfunctionality of the mineralocorticoid receptor expressed in cultured human umbilical and coronary artery endothelial cells does not allow aldosterone to modify gene expression and provides evidence against either a beneficial or harmful genomic effect of aldosterone on healthy endothelial cells.

  2. Antagonist pharmacology of desensitizing and non-desensitizing nicotinic acetylcholine receptors in cockroach neurons.

    PubMed

    Salgado, Vincent L

    2016-09-01

    Two α-bungarotoxin-sensitive nicotinic acetylcholine (ACh) receptor subtypes in neurons of the American cockroach have been identified as desensitizing (nAChD) and selectively inhibitable with 100nM imidacloprid, and non-desensitizing (nAChN) and selectively inhibitable with 100pM methyllycaconitine. In this paper, the single-electrode voltage-clamp technique was used to measure concentration-response relations for the action of ACh and five antagonists on pharmacologically separated nAChD and nAChN receptors of acutely dissociated neurons from thoracic ganglia of the American cockroach. A dual bath and U-tube perfusion system was used to achieve rapid application of ACh in the continued presence of antagonists, which was essential to accurately measure inhibition by rapidly-reversible antagonists. ACh activated both receptors with an EC50 of 7μM and the antagonist potencies were (nAChD/nAChN in nM): dihydro-β-erythroidine: 1.0/5.6, d-tubocurarine: 1000/34, condelphine: 0.39/0.65, phencyclidine: 74/980 and mecamylamine 47/1150. While each of these antagonists displayed some subtype selectivity, none are selective enough to be used as subtype-selective tools. These results bring to a total of 16 the number of nicotinic compounds that have been measured on nAChD and nAChN currents. Characterization of these receptors is important for understanding the role of nAChRs in the insect nervous system and the mechanism of action of insecticides.

  3. Halogenation of a capsaicin analogue leads to novel vanilloid TRPV1 receptor antagonists

    PubMed Central

    Appendino, Giovanni; Harrison, Selena; De Petrocellis, Luciano; Daddario, Nives; Bianchi, Federica; Schiano Moriello, Aniello; Trevisani, Marcello; Benvenuti, Francesca; Geppetti, Pierangelo; Di Marzo, Vincenzo

    2003-01-01

    The C-5 halogenation of the vanillyl moiety of resiniferatoxin, an ultrapotent agonist of vanilloid TRPV1 receptors, results in a potent antagonist for these receptors. Here, we have synthesized a series of halogenated derivatives of ‘synthetic capsaicin' (nonanoyl vanillamide=nordihydrocapsaicin) differing for the nature (iodine, bromine–chlorine) and the regiochemistry (C-5, C-6) of the halogenation.The activity of these compounds was investigated on recombinant human TRPV1 receptors overexpressed in HEK-293 cells. None of the six compounds exerted any significant agonist activity, as assessed by measuring their effect on TRPV1-mediated calcium mobilization. Instead, all compounds antagonized, to various extents, the effect of capsaicin in this assay.All 6-halo-nordihydrocapsaicins behaved as competitive antagonists against human TRPV1 according to the corresponding Schild's plots, and were more potent than the corresponding 5-halogenated analogues. The iodo-derivatives were more potent than the bromo- and chloro-derivatives.Using human recombinant TRPV1, 6-iodo-nordihydrocapsaicin (IC50=10 nM against 100 nM capsaicin) was about four times more potent than the prototypical TRPV1 antagonist, capsazepine, and was tested against capsaicin also on native TRPV1 in: (i) rat dorsal root ganglion neurons in culture; (ii) guinea-pig urinary bladder; and (iii) guinea-pig bronchi. In all cases, except for the guinea-pig bronchi, the compound was significantly more potent than capsazepine as a TRPV1 antagonist.In conclusion, 6-iodo-nordihydrocapsaicin, a stable and easily prepared compound, is a potent TRPV1 antagonist and a convenient replacement for capsazepine in most of the in vitro preparations currently used to assess the activity of putative vanilloid receptor agonists. PMID:12922928

  4. Species differences in the effects of the κ-opioid receptor antagonist zyklophin

    PubMed Central

    Sirohi, Sunil; Aldrich, Jane V.; Walker, Brendan M.

    2016-01-01

    We have shown that dysregulation of the dynorphin/kappa-opioid receptor (DYN/KOR) system contributes to escalated alcohol self-administration in alcohol dependence and that KOR antagonists with extended durations of action selectively reduce escalated alcohol consumption in alcohol-dependent animals. As KOR antagonism has gained widespread attention as a potential therapeutic target to treat alcoholism and multiple neuropsychiatric disorders, we tested the effect of zyklophin (a short-acting KOR antagonist) on escalated alcohol self-administration in rats made alcohol-dependent using intermittent alcohol vapor exposure. Following dependence induction, zyklophin was infused centrally prior to alcohol self-administration sessions and locomotor activity tests during acute withdrawal. Zyklophin did not impact alcohol self-administration or locomotor activity in either exposure condition. To investigate the neurobiological basis of this atypical effect for a KOR antagonist, we utilized a κ-, μ-, and δ-opioid receptor agonist-stimulated GTPyS coupling assay to examine the opioid receptor specificity of zyklophin in the rat brain and mouse brain. In rats, zyklophin did not affect U50488-, DAMGO-, or DADLE-stimulated GTPyS coupling, whereas the prototypical KOR antagonist nor-binaltorphimine (norBNI) attenuated U50488-induced stimulation in the rat brain tissue at concentrations that did not impact μ- and δ-receptor function. To reconcile the discrepancy between the present rat data and published mouse data, comparable GTPyS assays were conducted using mouse brain tissue; zyklophin effects were consistent with KOR antagonism in mice. Moreover, at higher concentrations, zyklophin exhibited agonist properties in rat and mouse brains. These results identify species differences in zyklophin efficacy that, given the rising interest in the development of short-duration KOR antagonists, should provide valuable information for therapeutic development efforts. PMID:26992699

  5. Effect of dopamine and serotonin receptor antagonists on fencamfamine-induced abolition of latent inhibition.

    PubMed

    de Aguiar, Cilene Rejane Ramos Alves; de Aguiar, Marlison José Lima; DeLucia, Roberto; Silva, Maria Teresa Araujo

    2013-01-05

    The purpose of this investigation was to verify the role of dopamine and serotonin receptors in the effect of fencamfamine (FCF) on latent inhibition. FCF is a psychomotor stimulant with an indirect dopaminergic action. Latent inhibition is a model of attention. Latent inhibition is blocked by dopaminergic agents and facilitated by dopamine receptor agonists. FCF has been shown to abolish latent inhibition. The serotonergic system may also participate in the neurochemical mediation of latent inhibition. The selective dopamine D(1) receptor antagonist SCH 23390 (7-chloro-3-methyl-1-phenyl-1,2,4,5-tetrahydro-3-benzazepin-8-ol), D(2) receptor antagonists pimozide (PIM) and methoclopramide (METH), and serotonin 5-HT(2A/C) receptor antagonist ritanserin (RIT) were used in the present study. Latent inhibition was evaluated using a conditioned emotional response procedure. Male Wistar rats that were water-restricted were subjected to a three-phase procedure: preexposure to a tone, tone-shock conditioning, and a test of the effect of the tone on licking frequency. All of the drugs were administered before the preexposure and conditioning phases. The results showed that FCF abolished latent inhibition, and this effect was clearly antagonized by PIM and METH and moderately attenuated by SCH 23390. At the doses used in the present study, RIT pretreatment did not affect latent inhibition and did not eliminate the effect of FCF, suggesting that the FCF-induced abolition of latent inhibition is not mediated by serotonin 5-HT(2A/C) receptors. These results suggest that the effect of FCF on latent inhibition is predominantly related to dopamine D(2) receptors and that dopamine D(2) receptors participate in attention processes.

  6. Long term outcome of Aldosteronism after target treatments

    PubMed Central

    Wu, Vin-Cent; Wang, Shuo-Meng; Chang, Chia-Hui; Hu, Ya-Hui; Lin, Lian-Yu; Lin, Yen-Hung; Chueh, Shih-Chieh Jeff; Chen, Likwang; Wu, Kwan-Dun

    2016-01-01

    There exists a great knowledge gap in terms of long-term effects of various surgical and pharmacological treatments on outcomes among primary aldosteronism (PA) patients. Using a validated algorithm, we extracted longitudinal data for all PA patients diagnosed in 1997–2010 and treated in the Taiwan National Health Insurance. We identified 3362 PA patients for whom the mean length of follow-up was 5.75 years. PA has higher major cardiovascular events (MACE) than essential hypertension (23.3% vs 19.3%, p = 0.015). Results from the Cox model suggest a strong effect of adrenalectomy on lowering mortality (HR = 0.23 with residual hypertension and 0.21 with resolved hypertension). While need for receptor antagonist (MRA) MRA after diagnosis suggests that a defined daily dose (DDD) of MRA between 12.5 and 50 mg may alleviate risk of death in a U-shape pattern. A specificity test identified patients who has aldosterone producing adenoma (HR = 0.50, p = 0.005) also confirmed adrenalectomy attenuated all-cause mortality. Adrenalectomy decreases long-term all-cause mortality independently from PA cure from hypertension. Prescription corresponding to a DDD between 12.5 and 50 mg may decrease mortality for patients needing MRA. It calls for more attention on early diagnosis, early treatment and prescription of appropriate dosage of MRA for PA patients. PMID:27586402

  7. 5-HT2 Receptor Regulation of Mitochondrial Genes: Unexpected Pharmacological Effects of Agonists and Antagonists.

    PubMed

    Harmon, Jennifer L; Wills, Lauren P; McOmish, Caitlin E; Demireva, Elena Y; Gingrich, Jay A; Beeson, Craig C; Schnellmann, Rick G

    2016-04-01

    In acute organ injuries, mitochondria are often dysfunctional, and recent research has revealed that recovery of mitochondrial and renal functions is accelerated by induction of mitochondrial biogenesis (MB). We previously reported that the nonselective 5-HT2 receptor agonist DOI [1-(4-iodo-2,5-dimethoxyphenyl)propan-2-amine] induced MB in renal proximal tubular cells (RPTCs). The goal of this study was to determine the role of 5-HT2 receptors in the regulation of mitochondrial genes and oxidative metabolism in the kidney. The 5-HT2C receptor agonist CP-809,101 [2-[(3-chlorophenyl)methoxy]-6-(1-piperazinyl)pyrazine] and antagonist SB-242,084 [6-chloro-2,3-dihydro-5-methyl-N-[6-[(2-methyl-3-pyridinyl)oxy]-3-pyridinyl]-1H-indole-1-carboxyamide dihydrochloride] were used to examine the induction of renal mitochondrial genes and oxidative metabolism in RPTCs and in mouse kidneys in the presence and absence of the 5-HT2C receptor. Unexpectedly, both CP-809,101 and SB-242,084 increased RPTC respiration and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) mRNA expression in RPTCs at 1-10 nM. In addition, CP-809,101 and SB-242,084 increased mRNA expression of PGC-1α and the mitochondrial proteins NADH dehydrogenase subunit 1 and NADH dehydrogenase (ubiquinone) β subcomplex 8 in mice. These compounds increased mitochondrial genes in RPTCs in which the 5-HT2C receptor was downregulated with small interfering RNA and in the renal cortex of mice lacking the 5-HT2C receptor. By contrast, the ability of these compounds to increase PGC-1α mRNA and respiration was blocked in RPTCs treated with 5-HT2A receptor small interfering RNA or the 5-HT2A receptor antagonist eplivanserin. In addition, the 5-HT2A receptor agonist NBOH-2C-CN [4-[2-[[(2-hydroxyphenyl)methyl]amino]ethyl]-2,5-dimethoxybenzonitrile] increased RPTC respiration at 1-100 nM. These results suggest that agonism of the 5-HT2A receptor induces MB and that the classic 5-HT2C receptor agonist CP

  8. Allosteric antagonist binding sites in class B GPCRs: corticotropin receptor 1

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Supriyo; Subramanian, Govindan; Hall, Spencer; Lin, Jianping; Laoui, Abdelazize; Vaidehi, Nagarajan

    2010-08-01

    The 41 amino acid neuropeptide, corticotropin-releasing factor (CRF) and its associated receptors CRF1-R and CRF2-R have been targeted for treating stress related disorders. Both CRF1-R and CRF2-R belong to the class B G-protein coupled receptors for which little information is known regarding the small molecule antagonist binding characteristics. However, it has been shown recently that different non-peptide allosteric ligands stabilize different receptor conformations for CRF1-R and hence an understanding of the ligand induced receptor conformational changes is important in the pharmacology of ligand binding. In this study, we modeled the receptor and identified the binding sites of representative small molecule allosteric antagonists for CRF1-R. The predicted binding sites of the investigated compounds are located within the transmembrane (TM) domain encompassing TM helices 3, 5 and 6. The docked compounds show strong interactions with H228 on TM3 and M305 on TM5 that have also been implicated in the binding by site directed mutation studies. H228 forms a hydrogen bond of varied strengths with all the antagonists in this study and this is in agreement with the decreased binding affinity of several compounds with H228F mutation. Also mutating M305 to Ile showed a sharp decrease in the calculated binding energy whereas the binding energy loss on M305 to Leu was less significant. These results are in qualitative agreement with the decrease in binding affinities observed experimentally. We further predicted the conformational changes in CRF1-R induced by the allosteric antagonist NBI-27914. Movement of TM helices 3 and 5 are dominant and generates three degenerate conformational states two of which are separated by an energy barrier from the third, when bound to NBI-27914. Binding of NBI-27914 was predicted to improve the interaction of the ligand with M305 and also enhanced the aromatic stacking between the ligand and F232 on TM3. A virtual ligand screening of 13

  9. Opioid Receptor Antagonists in the Treatment of Alcoholism.

    PubMed

    Serecigni, Josep Guardia

    2015-09-29

    Objetivos: A partir de los recientes progresos en la farmacoterapia del alcoholismo, hemos efectuado una revisión sobre los fármacos antagonistas de los receptores opioides, que tienen aprobada la indicación para el tratamiento del alcoholismo, como son naltrexona y nalmefeno. Metodología: Hemos revisado más de 100 publicaciones sobre péptidos y receptores opioides, el efecto de los fármacos antagonistas de los receptores opioides sobre el consumo de alcohol, tanto en animales como en humanos, tanto en el laboratorio como para el tratamiento del alcoholismo. También se describen las características farmacológicas de naltrexona y de nalmefeno y su utilidad en la práctica clínica. Resultados: Múltiples evidencias han demostrado la eficacia de naltrexona y nalmefeno para reducir el consumo de alcohol, tanto en animales de laboratorio como también en personas estudiadas en situación de bar experimental, aunque debido al diferente perfil receptorial, nalmefeno ha sido relacionado con una mayor eficacia para la reducción del consumo de alcohol, en ratas que presentan dependencia del alcohol. Además, un gran número de ensayos clínicos controlados han demostrado la eficacia de naltrexona para la prevención de recaídas, en personas que presentan un trastorno por dependencia del alcohol. Ensayos clínicos controlados recientes han demostrado la eficacia de nalmefeno “a demanda” para reducir el consumo de alcohol, en personas que presentan un trastorno por dependencia del alcohol de baja gravedad. Conclusiones: Tanto naltrexona como nalmefeno han demostrado ser fármacos seguros, bien tolerados, de manejo sencillo, y eficaces para el tratamiento del trastorno por dependencia del alcohol, (actualmente llamado trastorno por consumo de alcohol). A partir de recientes ensayos clínicos controlados se ha comprobado que nalmefeno produce una reducción significativa del consumo de alcohol, lo cual supone un nuevo objetivo que amplía las posibilidades de

  10. Interactions of tachykinin receptor antagonists with lipopolysaccharide-induced airway inflammation in mice.

    PubMed

    Veron, M; Guenon, I; Nenan, S; Emonds-Alt, X; Advenier, C; Lagente, V; Boichot, E

    2004-09-01

    1. Several observations suggest that tachykinins are involved in the pathogenesis of bronchopulmonary alterations. We have investigated the effect of antagonists for tachykinin NK1 (SR 140333), NK2 (SR 48968) or NK3 (SR 142801) receptors on inflammatory cell recruitment, tumour necrosis factor (TNF)-alpha and interleukin (IL)-6 release and matrix metalloproteinase (MMP)-9 activity in the bronchoalveolar lavage fluid (BALF) of mice exposed to lipopolysaccharide (LPS; 100 microg/mL aerosol for 30 min). 2. Treatment of mice with a combination of SR 140333 and SR 48968 (10(-6) mol/L, aerosol) significantly reduced the increase in the number of total cells and neutrophils and MMP-9 activity in the BALF of mice 2.5 h after LPS exposure. Treatment with the NK3 antagonist SR 142801 (10(-6) mol/L, aerosol) did not inhibit the influx of neutrophils, but markedly reduced the increase in TNF-alpha and IL-6 levels at 2.5 h and MMP-9 activity at 20 h. 3. These results show that the three tachykinin receptor antagonists may interfere with the development of airway inflammation, namely neutrophilia, TNF-alpha release or MMP-9 activity in the BALF of mice exposed to LPS and suggest that not only NK1 and NK2 receptors, but also NK3 receptors are involved in the modulation of the inflammatory response and airway remodelling.

  11. Modulation of a 40-kDa catecholamine regulated protein by dopamine receptor antagonists.

    PubMed

    Sharan, N; Nair, V D; Mishra, R K

    2001-02-09

    Previous reports have shown that catecholamine regulated proteins (CRP) are central nervous system specific and covalently bind to catecholamines. In the present study, we report the subcellular localization and differential modulation of a 40-kDa catecholamine regulated protein (CRP40) by dopamine D1 and D2 receptor antagonists. CRP40 was found to be localized with nuclear and synaptosomal/mitochondrial and fractions. Chronic treatment with dopamine D2 receptor antagonist haloperidol in rats significantly increased the levels of CRP40 in the striatum, whereas, chronic R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH 23390) dopamine D1 receptor antagonist administration significantly decreased striatal CRP40 levels. Moreover, acute haloperidol treatment did not alter the levels of CRP40 in any of the brain regions. Despite a sequence homology with the heat shock protein 70 (HSP70), levels of HSP70 remained unchanged after either drug treatment, suggesting a distinct function of CRP40 than HSP70. These results further suggest that CRP40 play an important role in dopaminergic neuronal function and the dopamine D1 receptor-mediated signaling pathway may be involved in the regulation of CRP40.

  12. The histamine H1-receptor antagonist binding site. Part I: Active conformation of cyproheptadine

    NASA Astrophysics Data System (ADS)

    van Drooge, Marc J.; Donné-op den Kelder, Gabriëlle M.; Timmerman, Hendrik

    1991-08-01

    The active conformation of several histamine H1-antagonists is investigated. As a template molecule we used the antagonist cyproheptadine, which consists of a piperidylene ring connected to a tricyclic system. The piperidylene moiety is shown to be flexible. The global minimum is a chair conformation but, additionally, a second chair and various boat conformations have to be considered, as their energies are less than 5 kcal/mol above the energy of the global minimum. Two semi-rigid histamine H1-antagonists, phenindamine and triprolidine, were fitted onto the various conformations of cyproheptadine in order to derive the pharmacologically active conformation of cyproheptadine. At the same time, the active conformation of both phenindamine and triprolidine was derived. It is demonstrated that, within the receptor-bound conformation of cyproheptadine, the piperidylene ring most probably exists in a boat form.

  13. Discovery of novel 6,6-heterocycles as transient receptor potential vanilloid (TRPV1) antagonists.

    PubMed

    Blum, Charles A; Caldwell, Timothy; Zheng, Xiaozhang; Bakthavatchalam, Rajagopal; Capitosti, Scott; Brielmann, Harry; De Lombaert, Stéphane; Kershaw, Mark T; Matson, David; Krause, James E; Cortright, Daniel; Crandall, Marci; Martin, William J; Murphy, Beth Ann; Boyce, Susan; Jones, A Brian; Mason, Glenn; Rycroft, Wayne; Perrett, Helen; Conley, Rachael; Burnaby-Davies, Nicola; Chenard, Bertrand L; Hodgetts, Kevin J

    2010-04-22

    The transient receptor potential cation channel, subfamily V, member 1 (TRPV1) is a nonselective cation channel that can be activated by a wide range of noxious stimuli, including capsaicin, acid, and heat. Blockade of TRPV1 activation by selective antagonists is under investigation in an attempt to identify novel agents for pain treatment. The design and synthesis of a series of novel TRPV1 antagonists with a variety of different 6,6-heterocyclic cores is described, and an extensive evaluation of the pharmacological and pharmacokinetic properties of a number of these compounds is reported. For example, the 1,8-naphthyridine 52 was characterized as an orally bioavailable and brain penetrant TRPV1 antagonist. In vivo, 52 fully reversed carrageenan-induced thermal hyperalgesia (CITH) in rats and dose-dependently potently reduced complete Freund's adjuvant (CFA) induced chronic inflammatory pain after oral administration.

  14. Evidence for allosteric interactions of antagonist binding to the smoothened receptor.

    PubMed

    Rominger, Cynthia M; Bee, Wei-Lin Tiger; Copeland, Robert A; Davenport, Elizabeth A; Gilmartin, Aidan; Gontarek, Richard; Hornberger, Keith R; Kallal, Lorena A; Lai, Zhihong; Lawrie, Kenneth; Lu, Quinn; McMillan, Lynette; Truong, Maggie; Tummino, Peter J; Turunen, Brandon; Will, Matthew; Zuercher, William J; Rominger, David H

    2009-06-01

    The Smoothened receptor (Smo) mediates hedgehog (Hh) signaling critical for development, cell growth, and migration, as well as stem cell maintenance. Aberrant Hh signaling pathway activation has been implicated in a variety of cancers, and small-molecule antagonists of Smo have entered human clinical trials for the treatment of cancer. Here, we report the biochemical characterization of allosteric interactions of agonists and antagonists for Smo. Binding of two radioligands, [(3)H]3-chloro-N-[trans-4-(methylamino)cyclohexyl]-N-{[3-(4-pyridinyl)-phenyl]methyl}-1-benzothiophene-2-carboxamide (SAG-1.3) (agonist) and [(3)H]cyclopamine (antagonist), was characterized using human Smo expressed in human embryonic kidney 293F membranes. We observed full displacement of [(3)H]cyclopamine by all Smo agonist and antagonist ligands examined. N-[(1E)-(3,5-Dimethyl-1-phenyl-1H-pyrazol-4-yl)methylidene]-4-(phenylmethyl)-1-piperazinamine (SANT-1), an antagonist, did not fully inhibit the binding of [(3)H]SAG-1.3. In a functional cell-based beta-lactamase reporter gene assay, SANT-1 and N-[3-(1H-benzimidazol-2-yl)-4-chlorophenyl]-3,4,5-tris(ethyloxy)-benzamide (SANT-2) fully inhibited 3-chloro-4,7-difluoro-N-[trans-4-(methylamino)cyclohexyl]-N-{[3-(4-pyridinyl)phenyl]methyl}-1-benzothiophene-2-carboxamide (SAG-1.5)-induced Hh pathway activation. Detailed "Schild-type" radioligand binding analysis with [(3)H]SAG-1.3 revealed that two structurally distinct Smoothened receptor antagonists, SANT-1 and SANT-2, bound in a manner consistent with that of allosteric modulation. Our mechanism of action characterization of radioligand binding to Smo combined with functional data provides a better understanding of small-molecule interactions with Smo and their influence on the Hh pathway.

  15. A PET study comparing receptor occupancy by five selective cannabinoid 1 receptor antagonists in non-human primates

    PubMed Central

    Hjorth, Stephan; Karlsson, Cecilia; Jucaite, Aurelija; Varnäs, Katarina; Hamrén, Ulrika Wählby; Johnström, Peter; Gulyás, Balázs; Donohue, Sean R; Pike, Victor W; Halldin, Christer; Farde, Lars

    2015-01-01

    There is a medical need for safe and efficacious anti-obesity drugs with acceptable side effect profiles. To mitigate the challenge posed by translating target interaction across species and balancing beneficial vs. adverse effects, a positron emission tomography (PET) approach could help guide clinical dose optimization. Thus, as part of a compound differentiation effort, three novel selective CB1 receptor (CB1R) antagonists, developed by AstraZeneca (AZ) for the treatment of obesity, were compared with two clinically tested reference compounds, rimonabant and taranabant, with regard to receptor occupancy relative to dose and exposure. A total of 42 PET measurements were performed in 6 non-human primates using the novel CB1R antagonist radioligand [11C]SD5024. The AZ CB1R antagonists bound in a saturable manner to brain CB1R with in vivo affinities similar to that of rimonabant and taranabant, compounds with proven weight loss efficacy in clinical trials. Interestingly, it was found that exposures corresponding to those needed for optimal clinical efficacy of rimonabant and taranabant resulted in a CB1R occupancy typically around ~20–30%, thus much lower than what would be expected for classical G-protein coupled receptor (GPCR) antagonists in other therapeutic contexts. These findings are also discussed in relation to emerging literature on the potential usefulness of ‘neutral’ vs. ‘classical’ CB1R (inverse agonist) antagonists. The study additionally highlighted the usefulness of the radioligand [11C]SD5024 as a specific tracer for CB1R in the primate brain, though an arterial input function would ideally be required in future studies to further assure accurate quantitative analysis of specific binding. PMID:25791528

  16. A PET study comparing receptor occupancy by five selective cannabinoid 1 receptor antagonists in non-human primates.

    PubMed

    Hjorth, Stephan; Karlsson, Cecilia; Jucaite, Aurelija; Varnäs, Katarina; Wählby Hamrén, Ulrika; Johnström, Peter; Gulyás, Balázs; Donohue, Sean R; Pike, Victor W; Halldin, Christer; Farde, Lars

    2016-02-01

    There is a medical need for safe and efficacious anti-obesity drugs with acceptable side effect profiles. To mitigate the challenge posed by translating target interaction across species and balancing beneficial vs. adverse effects, a positron emission tomography (PET) approach could help guide clinical dose optimization. Thus, as part of a compound differentiation effort, three novel selective CB1 receptor (CB1R) antagonists, developed by AstraZeneca (AZ) for the treatment of obesity, were compared with two clinically tested reference compounds, rimonabant and taranabant, with regard to receptor occupancy relative to dose and exposure. A total of 42 PET measurements were performed in 6 non-human primates using the novel CB1R antagonist radioligand [(11)C]SD5024. The AZ CB1R antagonists bound in a saturable manner to brain CB1R with in vivo affinities similar to that of rimonabant and taranabant, compounds with proven weight loss efficacy in clinical trials. Interestingly, it was found that exposures corresponding to those needed for optimal clinical efficacy of rimonabant and taranabant resulted in a CB1R occupancy typically around ∼20-30%, thus much lower than what would be expected for classical G-protein coupled receptor (GPCR) antagonists in other therapeutic contexts. These findings are also discussed in relation to emerging literature on the potential usefulness of 'neutral' vs. 'classical' CB1R (inverse agonist) antagonists. The study additionally highlighted the usefulness of the radioligand [(11)C]SD5024 as a specific tracer for CB1R in the primate brain, though an arterial input function would ideally be required in future studies to further assure accurate quantitative analysis of specific binding.

  17. Felbamate displays in vitro antiepileptic effects as a broad spectrum excitatory amino acid receptor antagonist.

    PubMed

    Domenici, M R; Sagratella, S; Ongini, E; Longo, R; Scotti de Carolis, A

    1994-12-27

    The in vitro antiepileptic activity of the novel anticonvulsant drug felbamate was tested in rat hippocampal slices on the CA1 epileptiform bursting induced by different chemical epileptogenic agents. The effects of felbamate were compared with those of the anticonvulsant drugs diphenylhydantoin and pentobarbitone and with the effects of excitatory amino acid antagonists acting at both N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Like the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), felbamate at a minimum effective concentration of 1 mM induced a significant (P < 0.01) reduction of the duration of the CA1 epileptiform bursting due to the K+ channel blocker, 4-aminopyridine, and the excitatory amino acids, kainate and quisqualate. Like the NMDA receptor antagonist ketamine, felbamate (1.6 mM) significantly (P < 0.01) decreased the duration of the CA1 epileptiform bursting caused by 'Mg(2+)-free' solutions. Conversely, felbamate (1.6 mM), CNQX (100 microM) and ketamine (100 microM) failed to affect the epileptiform bursting induced by the GABA antagonist penicillin. Pentobarbitone (100 microM) significantly (P < 0.01) decreased the duration of the CA1 epileptiform bursting caused by 'Mg(2+)-free' solutions, 4-aminopyridine or penicillin, while diphenylhydantoin (up to concentrations of 100 microM) failed to have an effect. The results indicate that felbamate displays a unique profile of in vitro antiepileptic effects as a broad spectrum antagonist of excitatory amino acid transmission.

  18. Darifenacin: a novel M3 muscarinic selective receptor antagonist for the treatment of overactive bladder.

    PubMed

    Chapple, Christopher R

    2004-11-01

    Darifenacin is a novel M3 muscarinic selective receptor antagonist for once-daily treatment of overactive bladder (OAB), a highly prevalent, chronic and debilitating disease defined by urinary urgency with or without urge incontinence, usually with increased frequency of micturition and nocturia. In vitro, darifenacin is a potent and specific muscarinic receptor antagonist with receptors relative to other muscarinic receptor subtypes. This profile may, therefore, confer clinical efficacy in the treatment of OAB, with a lower propensity for adverse effects and safety issues related to blockade of other muscarinic receptor subtypes. Indeed, consistent with its low relative affinity for M1 and M2 receptors, no effects on cognitive function and heart-rate variability, respectively, have been observed with darifenacin. Subsequent large-scale clinical trials have confirmed that darifenacin (at doses of 7.5 and 15 mg/day) results in central nervous system and cardiac adverse events comparable to placebo, and provides early and meaningful improvement across a range of OAB symptoms including incontinence episodes, urgency and urinary frequency. On the basis of such findings, darifenacin would appear to meet the current need for an effective OAB pharmacotherapy that is efficacious, well-tolerated and, more importantly, minimises the risk of safety-related adverse effects.

  19. Serotonergic 5-HT6 Receptor Antagonists: Heterocyclic Chemistry and Potential Therapeutic Significance.

    PubMed

    Bali, Alka; Singh, Shalu

    2015-01-01

    The serotonin 5-HT(6) receptor (5- HT(6)R) is amongst the recently discovered serotonergic receptors with almost exclusive localization in the brain. Hence, this receptor is fast emerging as a promising target for cognition enhancement in central nervous system (CNS) diseases such as Alzheimer's disease (cognitive function), obesity, schizophrenia and anxiety. The last decade has seen a surge of literature reports on the functional role of this receptor in learning and memory processes and investigations related to the chemistry and pharmacology of 5-HT(6) receptor ligands, especially 5- HT(6) receptor antagonists. Studies show the involvement of multiple neurotransmitter systems in cognitive enhancement by 5-HT(6)R antagonists including cholinergic, glutamatergic, and GABAergic systems. Several of the 5-HT(6)R ligands are indole based agents bearing structural similarity to the endogenous neurotransmitter serotonin. Based on the pharmacophoric models proposed for these agents, drug designing has been carried out incorporating various heterocyclic replacements for the indole nucleus. In this review, we have broadly summarized the medicinal chemistry and current status of this fairly recent class of drugs along with their potential therapeutic applications.

  20. A rational approach to the design and synthesis of a new bradykinin B(1) receptor antagonist.

    PubMed

    Bedos, P; Amblard, M; Subra, G; Dodey, P; Luccarini, J M; Paquet, J L; Pruneau, D; Aumelas, A; Martinez, J

    2000-06-15

    We have previously synthesized a potent and selective B(1) bradykinin receptor antagonist, JMV1645 (H-Lys-Arg-Pro-Hyp-Gly-Igl-Ser-D-BT-OH), containing a dipeptide mimetic ((3S)-amino-5-carbonylmethyl-2,3-dihydro-1, 5-benzothiazepin-4(5H)-one (D-BT) moiety) at the C-terminal. Analogues of this potent B(1) bradykinin receptor antagonist in which the central Pro(2)-Hyp(3)-Gly(4)-Igl(5) tetrapeptide has been replaced by constrained N-1-substituted-1,3,8-triazaspiro¿4. 5decan-4-one ring system were synthesized. Among these analogues, compound JMV1640 (1) was found to have an affinity of 24.10 +/- 9.48 nM for the human cloned B(1) receptor. It antagonized the ¿des-Arg(10)-kallidin-induced contraction of the human umbilical vein (pA(2) = 6.1 +/- 0.1). Compound 1 was devoid of agonist activity at the kinin B(1) receptor. Moreover, it did not bind to the human cloned B(2) receptor. Therefore, JMV1640 constitutes a lead compound for the rational search of nonpeptide B(1) receptor analogues based on the BK sequence.

  1. X-ray structures define human P2X3 receptor gating cycle and antagonist action

    NASA Astrophysics Data System (ADS)

    Mansoor, Steven E.; Lü, Wei; Oosterheert, Wout; Shekhar, Mrinal; Tajkhorshid, Emad; Gouaux, Eric

    2016-10-01

    P2X receptors are trimeric, non-selective cation channels activated by ATP that have important roles in the cardiovascular, neuronal and immune systems. Despite their central function in human physiology and although they are potential targets of therapeutic agents, there are no structures of human P2X receptors. The mechanisms of receptor desensitization and ion permeation, principles of antagonism, and complete structures of the pore-forming transmembrane domains of these receptors remain unclear. Here we report X-ray crystal structures of the human P2X3 receptor in apo/resting, agonist-bound/open-pore, agonist-bound/closed-pore/desensitized and antagonist-bound/closed states. The open state structure harbours an intracellular motif we term the ‘cytoplasmic cap’, which stabilizes the open state of the ion channel pore and creates lateral, phospholipid-lined cytoplasmic fenestrations for water and ion egress. The competitive antagonists TNP-ATP and A-317491 stabilize the apo/resting state and reveal the interactions responsible for competitive inhibition. These structures illuminate the conformational rearrangements that underlie P2X receptor gating and provide a foundation for the development of new pharmacological agents.

  2. MIBE acts as antagonist ligand of both estrogen receptor α and GPER in breast cancer cells

    PubMed Central

    2012-01-01

    Introduction The multiple biological responses to estrogens are mainly mediated by the classical estrogen receptors ERα and ERβ, which act as ligand-activated transcription factors. ERα exerts a main role in the development of breast cancer; therefore, the ER antagonist tamoxifen has been widely used although its effectiveness is limited by de novo and acquired resistance. Recently, GPR30/GPER, a member of the seven-transmembrane G protein-coupled receptor family, has been implicated in mediating the effects of estrogens in various normal and cancer cells. In particular, GPER triggered gene expression and proliferative responses induced by estrogens and even ER antagonists in hormone-sensitive tumor cells. Likewise, additional ER ligands showed the ability to bind to GPER eliciting promiscuous and, in some cases, opposite actions through the two receptors. We synthesized a novel compound (ethyl 3-[5-(2-ethoxycarbonyl-1-methylvinyloxy)-1-methyl-1H-indol-3-yl]but-2-enoate), referred to as MIBE, and investigated its properties elicited through ERα and GPER in breast cancer cells. Methods Molecular modeling, binding experiments and functional assays were performed in order to evaluate the biological action exerted by MIBE through ERα and GPER in MCF7 and SkBr3 breast cancer cells. Results MIBE displayed the ability to act as an antagonist ligand for ERα and GPER as it elicited inhibitory effects on gene transcription and growth effects by binding to both receptors in breast cancer cells. Moreover, GPER was required for epidermal growth factor receptor (EGFR) and ERK activation by EGF as ascertained by using MIBE and performing gene silencing experiments. Conclusions Our findings provide novel insights on the functional cross-talk between GPER and EGFR signaling. Furthermore, the exclusive antagonistic activity exerted by MIBE on ERα and GPER could represent an innovative pharmacological approach targeting breast carcinomas which express one or both receptors at

  3. 2-Aminothienopyridazines as Novel Adenosine A1 Receptor Allosteric Modulators and Antagonists

    PubMed Central

    Ferguson, Gemma N.; Valant, Celine; Horne, James; Figler, Heidi; Flynn, Bernard L.; Linden, Joel; Chalmers, David K.; Sexton, Patrick M.; Christopoulos, Arthur; Scammells, Peter J.

    2008-01-01

    A pharmacophore-based screen identified 32 compounds including ethyl 5-amino-3-(4-tert-butylphenyl)-4-oxo-3,4-dihydrothieno[3,4-d]pyridazine-1-carboxylate (8) as a new allosteric modulator of the adenosine A1 receptor (A1AR). On the basis of this lead, various derivatives were prepared and evaluated for activity at the human A1AR. A number of the test compounds allosterically stabilized agonist-receptor-G protein ternary complexes in dissociation kinetic assays, but were found to be more potent as antagonists in subsequent functional assays of ERK1/2 phosphorylation. Additional experiments on the most potent antagonist, 13b, investigating A1AR-mediated [35S]GTPγS binding and [3H]CCPA equilibrium binding confirmed its antagonistic mode of action and also identified inverse agonism. This study has thus identified a new class of A1AR antagonists that can also recognize the receptor’s allosteric site with lower potency. PMID:18771255

  4. Exploratory studies on development of the chemokine receptor CXCR4 antagonists toward downsizing.

    PubMed

    Tamamura, Hirokazu; Tsutsumi, Hiroshi; Nomura, Wataru; Fujii, Nobutaka

    2008-02-10

    Seven transmembrane (7TM) G-protein-coupled receptor (GPCR) families are important targets for drug discovery, and specific antagonists for GPCR can accelerate research in the field of medicinal chemistry. The chemokine receptor CXCR4 is a GPCR that possesses a unique ligand CXCL12/stromal cell-derived factor-1 (SDF-1). The interaction between CXCL12 and CXCR4 is essential for the migration of progenitor cells during embryonic development of the cardiovascular, hemopoietic and central nervous systems, and also involved in several intractable disease processes, including HIV infection, cancer cell metastasis, progression of acute and chronic leukemias, rheumatoid arthritis and pulmonary fibrosis. Thus, CXCR4 may be an important therapeutic target in all of these diseases, and various CXCR4 antagonists have been proposed as potential drugs. Fourteen-mer peptides, T140 and its analogs, and downsized cyclic pentapeptides have been developed by us as potent CXCR4 antagonists. This article describes the development of a number of specific CXCR4 antagonists in our laboratory, including downsizing.

  5. Cannabinoid CB1 receptor antagonists as potential pharmacotherapies for drug abuse disorders.

    PubMed

    Beardsley, Patrick M; Thomas, Brian F; McMahon, Lance R

    2009-04-01

    Since the discovery of the cannabinoid CB1 receptor (CB1R) in 1988, and subsequently of the CB2 receptor (CB2R) in 1993, there has been an exponential growth of research investigating the functions of the endocannabinoid system. The roles of CB1Rs have been of particular interest to psychiatry because of their selective presence within the CNS and because of their association with brain-reward circuits involving mesocorticolimbic dopamine systems. One potential role that has become of considerable focus is the ability of CB1Rs to modulate the effects of the drugs of abuse. Many drugs of abuse elevate dopamine levels, and the ability of CB1R antagonists or inverse agonists to modulate these elevations has suggested their potential application as pharmacotherapies for treating drug abuse disorders. With the identification of the selective CB1R antagonist, rimonabant, in 1994, and subsequently of other CB1R antagonists, there has been a rapid expansion of research investigating their ability to modulate the effects of the drugs of abuse. This review highlights some of the preclinical and clinical studies that have examined the effects of CB1R antagonists under conditions potentially predictive of their therapeutic efficacy as treatments for drug abuse disorders.

  6. [N-allyl-Dmt1]-endomorphins are micro-opioid receptor antagonists lacking inverse agonist properties.

    PubMed

    Marczak, Ewa D; Jinsmaa, Yunden; Li, Tingyou; Bryant, Sharon D; Tsuda, Yuko; Okada, Yoshio; Lazarus, Lawrence H

    2007-10-01

    [N-allyl-Dmt1]-endomorphin-1 and -2 ([N-allyl-Dmt1]-EM-1 and -2) are new selective micro-opioid receptor antagonists obtained by N-alkylation with an allyl group on the amino terminus of 2',6'-dimethyl-L-tyrosine (Dmt) derivatives. To further characterize properties of these compounds, their intrinsic activities were assessed by functional guanosine 5'-O-(3-[35S]thiotriphosphate) binding assays and forskolin-stimulated cyclic AMP accumulation in cell membranes obtained from vehicle, morphine, and ethanol-treated SK-N-SH cells and brain membranes isolated from naive and morphine-dependent mice; their mode of action was compared with naloxone or naltrexone, which both are standard nonspecific opioid-receptor antagonists. [N-allyl-Dmt1]-EM-1 and -2 were neutral antagonists under all of the experimental conditions examined, in contrast to naloxone and naltrexone, which behave as neutral antagonists only in membranes from vehicle-treated cells and mice but act as inverse agonists in membranes from morphine- and ethanol-treated cells as well as morphine-treated mice. Both endomorphin analogs inhibited the naloxone- and naltrexone-elicited withdrawal syndromes from acute morphine dependence in mice. This suggests their potential therapeutic application in the treatment of drug addiction and alcohol abuse without the adverse effects observed with inverse agonist alkaloid-derived compounds that produce severe withdrawal symptoms.

  7. Effect of the 5-hydroxytryptamine type 2 receptor antagonist, ketanserin, on blood pressure, the renin-angiotensin system and sympatho-adrenal function in patients with essential hypertension.

    PubMed Central

    Zabludowski, J R; Zoccali, C; Isles, C G; Murray, G D; Robertson, J I; Inglis, G C; Fraser, R; Ball, S G

    1984-01-01

    Ketanserin, a 5-HT type 2 receptor antagonist, was administered intravenously to nine patients with essential hypertension in a double-blind placebo controlled study to investigate the drug's effects on blood pressure, heart rate, the renin-angiotensin system and sympatho-adrenal function. Average blood-pressure for the group prior to injection of the drug was 150 +/- 7/94 +/- 4 (s.e. mean) mm Hg and decreased significantly (P less than 0.01) to 137 +/- 8/88 +/- 5 mm Hg during the 2 h after injection; heart rate increased immediately after injection of ketanserin, reaching a maximum of 81 +/- 4 beats/min. After drug administration systolic and diastolic blood pressure decreased on tilting, but the heart rate response was not different from that with placebo. Ketanserin did not affect the blood pressure response to graded infusion of the alpha 1-adrenoceptor agonist phenylephrine. Plasma active renin, angiotensin II and aldosterone concentrations increased slightly but not significantly after the drug; plasma noradrenaline increased transiently. 5-HT may be important in the maintenance of blood pressure but alternative mechanisms for the action of ketanserin in reducing blood pressure require investigation. PMID:6712863

  8. A long-acting GH receptor antagonist through fusion to GH binding protein.

    PubMed

    Wilkinson, Ian R; Pradhananga, Sarbendra L; Speak, Rowena; Artymiuk, Peter J; Sayers, Jon R; Ross, Richard J

    2016-10-12

    Acromegaly is a human disease of growth hormone (GH) excess with considerable morbidity and increased mortality. Somatostatin analogues are first line medical treatment but the disease remains uncontrolled in up to 40% of patients. GH receptor (GHR) antagonist therapy is more effective but requires frequent high-dose injections. We have developed an alternative technology for generating a long acting potent GHR antagonist through translational fusion of a mutated GH linked to GH binding protein and tested three candidate molecules. All molecules had the amino acid change (G120R), creating a competitive GHR antagonist and we tested the hypothesis that an amino acid change in the GH binding domain (W104A) would increase biological activity. All were antagonists in bioassays. In rats all antagonists had terminal half-lives >20 hours. After subcutaneous administration in rabbits one variant displayed a terminal half-life of 40.5 hours. A single subcutaneous injection of the same variant in rabbits resulted in a 14% fall in IGF-I over 7 days.

  9. Coptis extracts enhance the anticancer effect of estrogen receptor antagonists on human breast cancer cells

    PubMed Central

    Liu, Jing; He, Chengwei; Zhou, Keyuan; Wang, Jingdong; Kang, Jing X.

    2008-01-01

    Estrogen receptor (ER) antagonists have been widely used for breast cancer treatment, but the efficacy and drug resistance remain to be clinical concerns. The purpose of this study was to determine whether the extracts of coptis, an anti-inflammatory herb, improve the anticancer efficacy of ER antagonists. The results showed that the combined treatment of ER antagonists and the crude extract of coptis or its purified compound berberine conferred synergistic growth inhibitory effect on MCF-7 cells (ER+), but not on MDA-MB-231 cells (ER-). The similar results were observed in the combined treatment of fulvestrant, a specific aromatase antagonist. Analysis of the expression of breast cancer related genes indicated that EGFR, HER2, bcl-2 and COX-2 were significantly downregulated, while IFN-β and p21 were remarkably upregulated by berberine. Our results suggest that coptis extracts could be promising adjuvant to ER antagonists in ER positive breast cancer treatment through regulating expression of multiple genes. PMID:19000652

  10. NMDA Receptor Antagonist Attenuates Bleomycin-Induced Acute Lung Injury

    PubMed Central

    Li, Yang; Liu, Yong; Peng, XiangPing; Liu, Wei; Zhao, FeiYan; Feng, DanDan; Han, JianZhong; Huang, YanHong; Luo, SiWei; Li, Lian; Yue, Shao Jie; Cheng, QingMei; Huang, XiaoTing; Luo, ZiQiang

    2015-01-01

    Background Glutamate is a major neurotransmitter in the central nervous system (CNS). Large amount of glutamate can overstimulate N-methyl-D-aspartate receptor (NMDAR), causing neuronal injury and death. Recently, NMDAR has been reported to be found in the lungs. The aim of this study is to examine the effects of memantine, a NMDAR channel blocker, on bleomycin-induced lung injury mice. Methods C57BL/6 mice were intratracheally injected with bleomycin (BLM) to induce lung injury. Mice were randomized to receive saline, memantine (Me), BLM, BLM plus Me. Lungs and BALF were harvested on day 3 or 7 for further evaluation. Results BLM caused leukocyte infiltration, pulmonary edema and increase in cytokines, and imposed significant oxidative stress (MDA as a marker) in lungs. Memantine significantly mitigated the oxidative stress, lung inflammatory response and acute lung injury caused by BLM. Moreover, activation of NMDAR enhances CD11b expression on neutrophils. Conclusions Memantine mitigates oxidative stress, lung inflammatory response and acute lung injury in BLM challenged mice. PMID:25942563

  11. Aldosterone and the conquest of land.

    PubMed

    Colombo, L; Dalla Valle, L; Fiore, C; Armanini, D; Belvedere, P

    2006-04-01

    The sequence of the phylogenetic events that preceded the appearance of aldosterone in vertebrates is described, starting from the ancestral conversion of cytochrome P450s from oxygen detoxification to xenobiotic detoxification and synthesis of oxygenated endobiotics with useful functions in intercellular signalling, such as steroid hormones. At the end of the Silurian period [438-408 million yr ago, (Mya)], a complete set of cytochrome P450s for corticoid synthesis was presumably already available, except for mitochondrial cytochrome P450c18 or aldosterone synthase encoded by CYP11B2. This gene arose by duplication of the CYP11B gene in the sarcopterygian or lobe-finned fish/tetrapod line after its divergence from the actinopterygian or ray-finned fish line 420 Mya, but before the beginning of the colonization of land by tetrapods in the late Devonian period, around 370 Mya. The fact that aldosterone is already present in Dipnoi, which occupy an evolutionary transition between water- and air-breathing but are fully aquatic, suggests that the role of this steroid was to potentiate the corticoid response to hypoxia, rather than to prevent dehydration out of the water. In terrestrial amphibians, there is no differentiation between the secretion rates and gluco- and mineralocorticoid effects of aldosterone and corticosterone. In sauropsids, plasma aldosterone concentrations are much lower than in amphibians, but regulation of salt/water balance is dependent upon both aldosterone and corticosterone, though sometimes with opposed actions. In terrestrial mammals, aldosterone acquires a specific mineralocorticoid function, because its interaction with the mineralocorticoid receptor is protected by the coexpression of the enzyme 11beta-hydroxysteroid dehydrogenase type 2, which inactivates both cortisol and corticosterone. There is evidence that aldosterone can be also synthesized extra-adrenally in brain neurons and cardiac myocytes, which lack this protection and where

  12. The antiparkinsonian drugs budipine and biperiden are use-dependent (uncompetitive) NMDA receptor antagonists.

    PubMed

    Jackisch, R; Kruchen, A; Sauermann, W; Hertting, G; Feuerstein, T J

    1994-10-24

    N-Methyl-D-aspartate- (NMDA-) evoked [3H]acetylcholine release in rabbit caudate nucleus slices was inhibited by the antiparkinsonian drugs budipine (1-tert-butyl-4,4-diphenylpiperidine) and biperiden (1-bicyclo[2.2.1.]hept-5-en-2-yl-1-phenyl-3-piperidino propanol) yielding functional Ki values of 4.6 and 8.8 microM. In contrast to the competitive antagonist 2-amino-5-phosphonopentaonate, budipine and biperidene significantly reduced both the apparent KD and the Emax value of NMDA. Moreover, they displaced [3H]MK-801 specifically bound to membranes of the same tissue, although with low affinity (IC50: 38 and 92 microM). It is concluded that budipine and biperiden are use-dependent (uncompetitive) antagonists at the NMDA receptor, binding to the receptor-linked ion channel, but probably not to the MK-801 binding site. NMDA antagonism may contribute to the antiparkinsonian effects of budipine.

  13. Biaryls as potent, tunable dual neurokinin 1 receptor antagonists and serotonin transporter inhibitors.

    PubMed

    Degnan, Andrew P; Tora, George O; Han, Ying; Rajamani, Ramkumar; Bertekap, Robert; Krause, Rudolph; Davis, Carl D; Hu, Joanna; Morgan, Daniel; Taylor, Sarah J; Krause, Kelly; Li, Yu-Wen; Mattson, Gail; Cunningham, Melissa A; Taber, Matthew T; Lodge, Nicholas J; Bronson, Joanne J; Gillman, Kevin W; Macor, John E

    2015-08-01

    Depression is a serious illness that affects millions of patients. Current treatments are associated with a number of undesirable side effects. Neurokinin 1 receptor (NK1R) antagonists have recently been shown to potentiate the antidepressant effects of serotonin-selective reuptake inhibitors (SSRIs) in a number of animal models. Herein we describe the optimization of a biaryl chemotype to provide a series of potent dual NK1R antagonists/serotonin transporter (SERT) inhibitors. Through the choice of appropriate substituents, the SERT/NK1R ratio could be tuned to afford a range of target selectivity profiles. This effort culminated in the identification of an analog that demonstrated oral bioavailability, favorable brain uptake, and efficacy in the gerbil foot tap model. Ex vivo occupancy studies with compound 58 demonstrated the ability to maintain NK1 receptor saturation (>88% occupancy) while titrating the desired level of SERT occupancy (11-84%) via dose selection.

  14. Synthesis of Arylpiperazine Derivatives As Protease Activated Receptor 1 Antagonists And Their Evaluation As Antiproliferative Agents.

    PubMed

    Zotti, Andrea Ilaria; Di Gennaro, Elena; Corvino, Angela; Frecentese, Francesco; Magli, Elisa; Perissutti, Elisa; Cirino, Giuseppe; Roviezzo, Fiorentina; Terranova-Barberio, Manuela; Iannelli, Federica; Caliendo, Giuseppe; Santagada, Vincenzo; Fiorino, Ferdinando; Budillon, Alfredo; Severino, Beatrice

    2016-09-26

    Protease activated receptor-1 (PAR1) is a G-coupled receptor activated by α-thrombin and other proteases. Several reports demonstrate PAR1 involvement in tumorigenesis and tumor progression. In order to investigate on potential use of PAR1 antagonists as antiproliferative agents, we have identified a series of arylpiperazine derivatives acting as PAR1 antagonists; the selected molecules have been evaluated for their antiproliferative properties. All the compounds inhibited the growth of a panel of cell lines expressing PAR1; two of them, compounds 13 and 15, were able to inhibit, in a dose dependent manner, the growth of the selected cell lines with the lowest IC50 values, and were further characterized to define the mechanism responsible for the observed antiproliferative effect. This study directed us to the identification of two interesting leads that may help to further validate PAR1 as an important therapeutic target for cancer treatment.

  15. Immunoactive effects of cannabinoids: considerations for the therapeutic use of cannabinoid receptor agonists and antagonists.

    PubMed

    Greineisen, William E; Turner, Helen

    2010-05-01

    The active constituents of Cannabis sativa have been used for centuries as recreational drugs and medicinal agents. Today, marijuana is the most prevalent drug of abuse in the United States and, conversely, therapeutic use of marijuana constituents are gaining mainstream clinical and political acceptance. Given the documented contributions of endocannabinoid signaling to a range of physiological systems, including cognitive function, and the control of eating behaviors, it is unsurprising that cannabinoid receptor agonists and antagonists are showing significant clinical potential. In addition to the neuroactive effects of cannabinoids, an emerging body of data suggests that both endogenous and exogenous cannabinoids are potently immunoactive. The central premise of this review article is that the immunological effects of cannabinoids should be considered in the context of each prescribing decision. We present evidence that the immunological effects of cannabinoid receptor agonists and antagonists are highly relevant to the spectrum of disorders for which cannabinoid therapeutics are currently offered.

  16. Ether derivatives of 3-piperidinopropan-1-ol as non-imidazole histamine H3 receptor antagonists.

    PubMed

    Łazewska, Dorota; Ligneau, Xavier; Schwartz, Jean-Charles; Schunack, Walter; Stark, Holger; Kieć-Kononowicz, Katarzyna

    2006-05-15

    A series of aliphatic and aromatic ether derivatives of 3-piperidinopropan-1-ol has been prepared by four different methods. The ethers obtained were evaluated for their affinities at recombinant human histamine H3 receptor, stably expressed in CHO-K1 or HEK 293 cells. All compounds investigated show from moderate to high in vitro affinities in the nanomolar concentration range. Selected compounds were investigated under in vivo conditions after oral administration to mice. Some proved to be highly potent and orally available histamine H3 receptor antagonists. The most potent antagonists in this series have been in vitro the 4-(1,1-dimethylpropyl)phenyl ether 19 (hH3R K(i) = 8.4 nM) and in vivo the simple ethyl ether 2 (ED50 = 1.0mg/kg).

  17. Characterization of protoberberine analogs employed as novel human P2X{sub 7} receptor antagonists

    SciTech Connect

    Lee, Ga Eun; Lee, Won-Gil; Lee, Song-Yi; Lee, Cho-Rong; Park, Chul-Seung; Chang, Sunghoe; Park, Sung-Gyoo; Song, Mi-Ryoung; Kim, Yong-Chul

    2011-04-15

    The P2X{sub 7} receptor (P2X{sub 7}R), a member of the ATP-gated ion channel family, is regarded as a promising target for therapy of immune-related diseases including rheumatoid arthritis and chronic pain. A group of novel protoberberine analogs (compounds 3-5), discovered by screening of chemical libraries, was here investigated with respect to their function as P2X{sub 7}R antagonists. Compounds 3-5 non-competitively inhibited BzATP-induced ethidium ion influx into hP2X{sub 7}-expressing HEK293 cells, with IC{sub 50} values of 100-300 nM. This antagonistic action on the channel further confirmed that both BzATP-induced inward currents and Ca{sup 2+} influx were strongly inhibited by compounds 3-5 in patch-clamp and Ca{sup 2+} influx assays. The antagonists also effectively suppressed downstream signaling of P2X{sub 7} receptors including IL-1{beta} release and phosphorylation of ERK1/2 and p38 proteins in hP2X{sub 7}-expressing HEK293 cells or in differentiated human monocytes (THP-1 cells). Moreover, IL-2 secretion from CD3/CD28-stimulated Jurkat T cell was also dramatically inhibited by the antagonist. These results imply that novel protoberberine analogs may modulate P2X{sub 7} receptor-mediated immune responses by allosteric inhibition of the receptor. - Graphical abstract: Display Omitted

  18. Discovery of AAT-008, a novel, potent, and selective prostaglandin EP4 receptor antagonist.

    PubMed

    Okumura, Yoshiyuki; Yamagishi, Tatsuya; Nukui, Seiji; Nakao, Kazunari

    2017-03-01

    Starting from acylsufonamide HTS hit 2, a novel series of para-N-acylaminomethylbenzoic acids was identified and developed as selective prostaglandin EP4 receptor antagonists. Structural modifications on lead compound 4a were explored with the aim of improving potency, physicochemical properties, and animal PK predictive of QD (once a day) dosing regimen in human. These efforts led to the discovery of the clinical candidate AAT-008 (4j), which exhibited significantly improved pharmacological profiles over grapiprant (1).

  19. A novel DP2 receptor antagonist (AM-461): a patent evaluation of WO2011085033.

    PubMed

    Norman, Peter

    2011-12-01

    This application claims salts and crystalline forms of a previously disclosed DP2 receptor antagonist (2-[3-[2-(tert-butylsulfanylmethyl)-4-(2,2-dimethylpropanoylamino)phenoxy]-4-methoxy-phenyl]acetic acid (1)). It also claims compositions containing the free acid and its salts, especially the sodium salt and their use in the treatment of inflammatory and respiratory diseases, especially asthma. Notably, the application presents Phase I clinical data on compound (1).

  20. Cardiovascular effects of selective agonists and antagonists of histamine H3 receptors in the anaesthetized rat.

    PubMed

    Coruzzi, G; Gambarelli, E; Bertaccini, G; Timmerman, H

    1995-06-01

    The cardiovascular responses to a series of selective histamine H3 receptor agonists, (R) alpha-methylhistamine, imetit and immepip and selective antagonists, thioperamide, clobenpropit and clophenpropit, were studied in anaesthetized rats. At 0.003-1 mumol/kg i.v. doses, H3 agonists failed to produce any significant change in the basal blood pressure and heart rate. Larger doses of (R) alpha-methylhistamine increased the blood pressure and heart rate and higher doses of imetit caused vasodepressor responses and reduced heart rate, whereas immepip proved virtually inactive. While (R) alpha-methylhistamine-induced effects were not blocked by histamine H1-, H2- and H3-receptor antagonists, they were however reduced by idazoxan and propranolol, which indicates that the mechanisms involved are adrenergic. The effects induced by imetit are not related to histamine H3 receptors but are mediated by indirect (via 5HT3 receptors) cholinergic mechanisms, since these effects were prevented by 1 mg/kg i.v. atropine and by 0.1 mg/kg i.v. ondansetron. Similarly, the H3 antagonists per se failed to change basal cardiovascular function up to 10 mumol/kg i.v. and only at 30 mumol/kg i.v. were marked decreases observed in the blood pressure and heart rate with a significant reduction in the effects of noradrenaline. These data indicate that in anaesthetized rats, histamine H3 receptor activation or blockade has no effect on basal cardiovascular function. The effects recorded after the administration of large doses of (R) alpha-methylhistamine and imetit are clearly unrelated to histamine H3 receptors and should be taken into account when using these compounds as H3 ligands for "in vivo" experiments.

  1. The Prognostic Value of Plasma Galectin-3 in Chronic Heart Failure Patients Is Maintained when Treated with Mineralocorticoid Receptor Antagonists

    PubMed Central

    Koukoui, François; Desmoulin, Franck; Galinier, Michel; Barutaut, Manon; Caubère, Celine; Evaristi, Maria Francesca; Murat, Gurbuz; De Boer, Rudolf; Berry, Matthieu; Smih, Fatima; Rouet, Philippe

    2015-01-01

    Objective Galectin-3 (Gal-3) is considered as a myocardial fibrosis biomarker with prognostic value in heart failure (HF). Since aldosterone is a neurohormone with established fibrotic properties, we aimed to investigate if mineralocorticoid receptor antagonists (MRAs) would modulate the prognostic value of Gal-3. Methods The IBLOMAVED cohort comprised 427 eligible chronic HF patients (CHF) with echocardiography and heart failure biomarkers assessments (BNP). After propensity score matching CHF patients for cardiovascular risk factors, to form balanced groups, Gal-3 levels were measured at baseline in plasma from patients treated with MRAs (MRA-Plus, n=101) or not (MRA-Neg, n=101). The primary end point was all-cause mortality with a follow-up of 3 years. Results Gal-3 in plasma from these patients were similar with median values of 14.0 ng/mL [IQR, 9.9–19.3] and 14.4 ng/mL [IQR, 12.3–19.8] (P = 0.132) in MRA-Neg and MRA-Plus, respectively. Patients with Gal-3 ≤17.8 ng/mL had an HR of 1 (reference group) and 1.5 [0.4–5.7] in MRA-Neg and MRA-Plus, respectively (p=0.509). Patients with Gal-3 ≥ 17.8 ng/mL had an HR of 7.4 [2.2–24.6] and 9.0 [2.9–27.8] in MRA-Plus and MRA-Neg, respectively (p=0.539) and a median survival time of 2.4 years [95%CI,1.8–2.4]. Multivariate Cox proportional hazard analysis confirmed that MRA and the interaction term between MRA treatment and Gal-3 >17.8 ng/mL were not factors associated with survival. Conclusions MRA treatment did not impair the prognostic value of Gal-3 assessed with a 17.8 ng/mL cut off. Gal-3 levels maintained its strong prognostic value in CHF also in patients treated with MRAs. The significance of the observed lack of an interaction between Gal-3 and treatment effect of MRAs remains to be elucidated. PMID:25786035

  2. 2-Aminoethyl Methylphosphonate, a Potent and Rapidly Acting Antagonist of GABAA-ρ1 Receptors

    DOE PAGES

    Xie, A.; Yan, J.; Yue, L.; ...

    2011-08-02

    All three classes of receptors for the inhibitory neurotransmitter GABA (GABAR) are expressed in the retina. This study investigated roles of GABAR, especially GABA(C)R (GABA(A)-rho), in retinal signaling in vivo by studying effects on the mouse electroretinogram (ERG) of genetic deletion of GABA(C)R versus pharmacological blockade using receptor antagonists. Brief full-field flash ERGs were recorded from anesthetized GABA(C)R(-/-) mice, and WT C57BL/6 (B6) mice, before and after intravitreal injection of GABA(C)R antagonists, TPMPA, 3-APMPA, or the more recently developed 2-AEMP; GABA(A)R antagonist, SR95531; GABA(B)R antagonist, CGP, and agonist, baclofen. Intravitreal injections of TPMPA and SR95531 were also made in Brownmore » Norway rats. The effect of 2-AEMP on GABA-induced current was tested directly in isolated rat rod bipolar cells, and 2-AEMP was found to preferentially block GABA(C)R in those cells. Maximum amplitudes of dark (DA) and light-adapted (LA) ERG b-waves were reduced in GABA(C)R(-/-) mice, compared to B6 mice, by 30-60%; a-waves were unaltered and oscillatory potential amplitudes were increased. In B6 mice, after injection of TPMPA (also in rats), 3-APMPA or 2-AEMP, ERGs became similar to ERGs of GABA(C)R(-/-) mice. Blockade of GABA(A)Rs and GABA(B)Rs, or agonism of GABA(B)Rs did not alter B6 DA b-wave amplitude. The negative scotopic threshold response (nSTR) was slightly less sensitive in GABA(C)R(-/-) than in B6 mice, and unaltered by 2-AEMP. However, amplitudes of nSTR and photopic negative response (PhNR), both of which originate from inner retina, were enhanced by TPMPA and 3-APMPA, each of which has GABA(B) agonist properties, and further increased by baclofen. The finding that genetic deletion of GABA(C)R, the GABA(C)R antagonist 2-AEMP, and other antagonists all reduced ERG b-wave amplitude, supports a role for CABA(C)R in determining the maximum response amplitude of bipolar cells contributing to the b-wave. GABA(C)R antagonists

  3. Evidence that Argos is an antagonistic ligand of the EGF receptor.

    PubMed

    Vinós, J; Freeman, M

    2000-07-20

    Argos, the inhibitor of the Drosophila epidermal growth factor (EGF) receptor, remains the only known extracellular inhibitor of this family of receptors in any organism. The functional domain of Argos includes an atypical EGF domain and it is not clear whether it binds to the EGF receptor or if it acts via a distinct receptor to reduce Egfr activity indirectly. Here we present two lines of evidence that strongly suggest that Argos directly interacts with the EGF receptor. First, Argos is unable to inhibit a chimeric receptor that contains an extracellular domain from an unrelated RTK, indicating the need for the EGF receptor extracellular domain. Second, Argos can inhibit the Drosophila EGF receptor even when expressed in human cells, implying that no other Drosophila protein is necessary for inhibition. We also report that Argos and the Drosophila activating ligand, Spitz, can influence mammalian RTK activation, albeit in a cell-type specific manner. This includes the first evidence that Argos can inhibit signalling in mammalian cells, raising the possibility of engineering an effective human EGF receptor/ErbB antagonist. Oncogene (2000) 19, 3560 - 3562

  4. Dynamics of the Development of Amnesia Caused by Disruption of Memory Reconsolidation by Neurotransmitter Receptors Antagonists.

    PubMed

    Nikitin, V P; Solntseva, S V; Kozyrev, S A

    2016-03-01

    The dynamics of amnesia development under conditions of memory reconsolidation disruption by serotonin receptor antagonist methiothepin or NMDA glutamate receptor antagonist MK-801 was studied in snails trained in conventional food aversion. In 2 days after training, injection of methiothepin or MK-801 before reminder induced amnesia development. During repeated training in 3 days after amnesia induction, the skill was formed more rapidly than during the initial training. During repeated training in 10 days after administration of methiothepin and reminder, the dynamics of habit formation was similar to that during initial learning. At the same time, repeated training in 10 days after MK-801 administration and reminder did not result in long-term memory formation. Disruption of reconsolidation of conditioned food aversion memory by antagonists of serotonin or NMDA glutamate receptors led to the development of different types of amnesia that had similar strengthening gradient at the early stages, but differed by the possibility of memory formation during re-training at the late stage.

  5. Indole-3-piperazinyl derivatives: novel chemical class of 5-HT(6) receptor antagonists.

    PubMed

    Nirogi, Ramakrishna V S; Deshpande, Amol D; Kambhampati, Ramasastri; Badange, Rajesh Kumar; Kota, Laxman; Daulatabad, Anand V; Shinde, Anil K; Ahmad, Ishtiyaque; Kandikere, Vishwottam; Jayarajan, Pradeep; Dubey, P K

    2011-01-01

    N(1)-Arylsulfonyl-3-piperazinyl indole derivatives were designed and identified as a novel class of 5-HT(6) receptors ligands. All the compounds have high affinity and antagonist activity towards 5-HT(6) receptor. The compound 7a (K(i) = 3.4 nM, functional assay IC(50) = 310 nM) shows enhanced cognitive effect when tested in NORT and Morris water maze models. Synthesis, SAR and PK profile of these novel compounds constitute the subject matter of this Letter.

  6. New insights into the stereochemical requirements of the bradykinin B2 receptor antagonists binding

    NASA Astrophysics Data System (ADS)

    Lupala, Cecylia S.; Gomez-Gutierrez, Patricia; Perez, Juan J.

    2016-01-01

    Bradykinin (BK) is a member of the kinin family, released in response to inflammation, trauma, burns, shock, allergy and some cardiovascular diseases, provoking vasodilatation and increased vascular permeability among other effects. Their actions are mediated through at least two G-protein coupled receptors, B1 a receptor up-regulated during inflammation episodes or tissue trauma and B2 that is constitutively expressed in a variety of cell types. The goal of the present work is to carry out a structure-activity study of BK B2 antagonism, taking into account the stereochemical features of diverse non-peptide antagonists and the way these features translate into ligand anchoring points to complementary regions of the receptor, through the analysis of the respective ligand-receptor complex. For this purpose an atomistic model of the BK B2 receptor was built by homology modeling and subsequently refined embedded in a lipid bilayer by means of a 600 ns molecular dynamics trajectory. The average structure from the last hundred nanoseconds of the molecular dynamics trajectory was energy minimized and used as model of the receptor for docking studies. For this purpose, a set of compounds with antagonistic profile, covering maximal diversity were selected from the literature. Specifically, the set of compounds include Fasitibant, FR173657, Anatibant, WIN64338, Bradyzide, CHEMBL442294, and JSM10292. Molecules were docked into the BK B2 receptor model and the corresponding complexes analyzed to understand ligand-receptor interactions. The outcome of this study is summarized in a 3D pharmacophore that explains the observed structure-activity results and provides insight into the design of novel molecules with antagonistic profile. To prove the validity of the pharmacophore hypothesized a virtual screening process was also carried out. The pharmacophore was used as query to identify new hits using diverse databases of molecules. The results of this study revealed a set of new

  7. Naphthalene/quinoline amides and sulfonylureas as potent and selective antagonists of the EP4 receptor.

    PubMed

    Burch, Jason D; Farand, Julie; Colucci, John; Sturino, Claudio; Ducharme, Yves; Friesen, Richard W; Lévesque, Jean-François; Gagné, Sébastien; Wrona, Mark; Therien, Alex G; Mathieu, Marie-Claude; Denis, Danielle; Vigneault, Erika; Xu, Daigen; Clark, Patsy; Rowland, Steve; Han, Yongxin

    2011-02-01

    Two new series of EP(4) antagonists based on naphthalene/quinoline scaffolds have been identified as part of our on-going efforts to develop treatments for inflammatory pain. One series contains an acidic sulfonylurea pharmacophore, whereas the other is a neutral amide. Both series show subnanomolar intrinsic binding potency towards the EP(4) receptor, and excellent selectivity towards other prostanoid receptors. While the amide series generally displays poor pharmacokinetic parameters, the sulfonylureas exhibit greatly improved profile. MF-592, the optimal compound from the sulfonylurea series, has a desirable overall preclinical profile that suggests it is suitable for further development.

  8. Aldosterone and Renin Test

    MedlinePlus

    ... the kidney (renal vein renin levels). If the value is significantly higher in one side, this indicates where the narrowing of the artery is present. Low aldosterone (hypoaldosteronism) usually occurs as part of ...

  9. Effects of iodoproxyfan, a potent and selective histamine H3 receptor antagonist, on alpha 2 and 5-HT3 receptors.

    PubMed

    Schlicker, E; Pertz, H; Bitschnau, H; Purand, K; Kathmann, M; Elz, S; Schunack, W

    1995-07-01

    We determined the affinity and/or potency of the novel H3 receptor antagonist iodoproxyfan at alpha 2 and 5-HT3 receptors. Iodoproxyfan and rauwolscine (a reference alpha 2 ligand) (i) monophasically displaced 3H-rauwolscine binding to rat brain cortex membranes (pKi 6.79 and 8.59); (ii) facilitated the electrically evoked tritium overflow from superfused mouse brain cortex slices preincubated with 3H-noradrenaline (pEC50 6.46 and 7.91) and (iii) produced rightward shifts of the concentration-response curve (CRC) of (unlabelled) noradrenaline for its inhibitory effect on the evoked overflow (pA2 6.65 and 7.88). In the guinea-pig ileum, iodoproxyfan 6.3 mumol/l failed to evoke a contraction by itself but depressed the maximum of the CRC of 5-hydroxytryptamine (pD'2 5.24). Tropisetron (a reference 5-HT3 antagonist) produced rightward shifts of the CRC of 5-hydroxytryptamine (pA2 7.84). In conclusion, the affinity/potency of iodoproxyfan at H3 receptors (range 8.3-9.7 [1]) exceeds that at alpha 2 receptors by at least 1.5 log units and that at 5-HT3 receptors by at least 3 log units.

  10. Activity of 2-substituted lysophosphatidic acid (LPA) analogs at LPA receptors: discovery of a LPA1/LPA3 receptor antagonist.

    PubMed

    Heise, C E; Santos, W L; Schreihofer, A M; Heasley, B H; Mukhin, Y V; Macdonald, T L; Lynch, K R

    2001-12-01

    The physiological implications of lysophosphatidic acid occupancy of individual receptors are largely unknown because selective agonists/antagonists are unavailable currently. The molecular cloning of three high-affinity lysophosphatidic acid receptors, LPA1, LPA2, and LPA3, provides a platform for developing receptor type-selective ligands. Starting with an N-acyl ethanolamide phosphate LPA analog, we made a series of substitutions at the second carbon to generate compounds with varying spatial, stereochemical, and electronic characteristics. Analysis of this series at each recombinant LPA receptor using a guanosine 5'-O-(3-[35S]thio)triphosphate (GTP[gamma35S]) binding assay revealed sharp differences in activity. Our results suggest that these receptors have one spatially restrictive binding pocket that interacts with the 2-substituted moieties and prefers small hydrophobic groups and hydrogen bonding functionalities. The agonist activity predicted by the GTP[gamma35S] binding assay was reflected in the activity of a subset of compounds in increasing arterial pressure in anesthetized rats. One compound with a bulky hydrophobic group (VPC12249) was a dual LPA1/LPA3 competitive antagonist. Several compounds that had smaller side chains were found to be LPA1-selective agonists.

  11. Hypersensitivity of dopamine transmission in the rat striatum after treatment with the NMDA receptor antagonist amantadine.

    PubMed

    Peeters, Magali; Page, Guylène; Maloteaux, Jean-Marie; Hermans, Emmanuel

    2002-09-13

    Amantadine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist known to increase dopamine synthesis and release in the striatum, is frequently associated with L-DOPA in the treatment of Parkinson's disease. However, the biochemical mechanisms involved in the effect of amantadine and the consequences of its repetitive administration on the modulation of striatal dopamine transmission still need to be clarified. We have investigated the effects of short-term amantadine treatments on the expression of dopamine receptors and the functional coupling to G proteins in rat striatal membranes. Dopamine-induced stimulation of guanosine 5'-[gamma-35S]triphosphate ([35S]GTPgammaS) binding was significantly enhanced (40%) in striatum homogenates from rats treated for 4 days with amantadine (40 mg/kg, i.p.) compared to vehicle-treated animals. This effect was specific for dopamine receptors and was transient as no significant modifications were observed when animals were treated for either 2 or 7 days. Administration of amantadine did not directly affect the animal behaviour. However, treated animals exhibited hypersensitive dopamine transmission since rats treated for 4 days showed exacerbated responses to a single apomorphine administration (enhanced locomotor activity and reduced stereotypy). Since the effects of amantadine administration differ from those usually observed with direct dopamine receptor agonists or other NMDA receptor antagonists, we suggest that multiple biochemical mechanisms contribute to the modulation of dopamine transmission by amantadine.

  12. X-ray structures define human P2X3 receptor gating cycle and antagonist action

    PubMed Central

    Mansoor, Steven E.; Lü, Wei; Oosterheert, Wout; Shekhar, Mrinal; Tajkhorshid, Emad; Gouaux, Eric

    2016-01-01

    Summary P2X receptors are trimeric, non-selective cation channels activated by ATP that play important roles in cardiovascular, neuronal and immune systems. Despite their central function in human physiology and as potential targets of therapeutic agents, there are no structures of human P2X receptors. Mechanisms of receptor desensitization and ion permeation, principles of antagonism, and complete structure of the pore-forming transmembrane domains remain unclear. We report x-ray crystal structures of human P2X3 receptor in apo/resting, agonist-bound/open-pore, agonist-bound/desensitized and antagonist-bound closed states. The open state structure harbors an intracellular motif we term the “cytoplasmic cap”, that stabilizes the open state of the ion channel pore and creates lateral, phospholipid-lined cytoplasmic fenestrations for water and ion egress. Competitive antagonists TNP-ATP and A-317491 stabilize the apo/resting state and reveal the interactions responsible for competitive inhibition. These structures illuminate the conformational rearrangements underpinning P2X receptor gating and provide a foundation for development of new pharmacologic agents. PMID:27626375

  13. Different antagonist binding properties of rat pancreatic and cardiac muscarinic receptors

    SciTech Connect

    Waelbroeck, M.; Camus, J.; Winand, J.; Christophe, J.

    1987-11-09

    The antagonist binding properties of rat pancreatic and cardiac muscarinic receptors were compared. In both tissues pirenzepine (PZ) had a low affinity for muscarinic receptors labelled by (/sup 3/H)N-methylscopolamine ((/sup 3/)NMS) (K/sub D/ values of 140 and 280nM, respectively, in pancreatic and cardiac homogenates). The binding properties of pancreatic and cardiac receptors were, however, markedly different. This was indicated by different affinities for dicyclomine, (11-(/(2-((diethylamino)-methyl)-1-piperidinyl/acetyl)-5, 11-dihydro-6H-pyrido(2,3-b)(1,4) benzodiazepin-6-on)(AFDX-116), 4-diphenylacetoxy-N-methyl-piperidine methobromide (4-DAMP) and hexahydrosiladifenidol (HHSiD). Pancreatic and cardiac muscarinic receptros also showed different (/sup 3/H)NMS association and dissociation rates. These results support the concept of M2 receptor subtypes have different binding kinetic properties. 20 references, 3 figures, 1 table.

  14. 5{alpha}-Bile alcohols function as farnesoid X receptor antagonists

    SciTech Connect

    Nishimaki-Mogami, Tomoko . E-mail: mogami@nihs.go.jp; Kawahara, Yosuke; Tamehiro, Norimasa; Yoshida, Takemi; Inoue, Kazuhide; Ohno, Yasuo; Nagao, Taku; Une, Mizuho

    2006-01-06

    The farnesoid X receptor (FXR) is a bile acid/alcohol-activated nuclear receptor that regulates lipid homeostasis. Unlike other steroid receptors, FXR binds bile acids in an orientation that allows the steroid nucleus A to face helix 12 in the receptor, a crucial domain for coactivator-recruitment. Because most naturally occurring bile acids and alcohols contain a cis-oriented A, which is distinct from that of other steroids and cholesterol metabolites, we investigated the role of this 5{beta}-configuration in FXR activation. The results showed that the 5{beta}-(A/B cis) bile alcohols 5{beta}-cyprinol and bufol are potent FXR agonists, whereas their 5{alpha}-(A/B trans) counterparts antagonize FXR transactivation and target gene expression. Both isomers bound to FXR, but their ability to induce coactivator-recruitment and thereby induce transactivation differed. These findings suggest a critical role for the A orientation of bile salts in agonist/antagonist function.

  15. Flavonoids as aryl hydrocarbon receptor agonists/antagonists: effects of structure and cell context.

    PubMed Central

    Zhang, Shu; Qin, Chunhua; Safe, Stephen H

    2003-01-01

    Chemoprotective phytochemicals exhibit multiple activities and interact with several cellular receptors, including the aryl hydrocarbon (Ah) receptor (AhR). In this study we investigated the AhR agonist/antagonist activities of the following flavonoids: chrysin, phloretin, kaempferol, galangin, naringenin, genistein, quercetin, myricetin, luteolin, baicalein, daidzein, apigenin, and diosmin. We also investigated the AhR-dependent activities of cantharidin and emodin (in herbal extracts) in Ah-responsive MCF-7 human breast cells, HepG2 human liver cancer cells, and mouse Hepa-1 cells transiently or stably transfected with plasmids expressing a luciferase reporter gene linked to multiple copies of a consensus dioxin-responsive element. The AhR agonist activities of the compounds (1 and 10 micro M) were as high as 25% of the maximal response induced by 5 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and their potencies were dependent on cell context. Galangin, genistein, daidzein, and diosmin were active only in Hepa-1 cells, and cantharidin induced activity only in human HepG2 and MCF-7 cells. Western blot analysis confirmed that baicalein and emodin also induced CYP1A1 protein in the human cancer cell lines. The AhR antagonist activities of four compounds inactive as agonists in MCF-7 and HepG2 cells (kaempferol, quercetin, myricetin, and luteolin) were also investigated. Luteolin was an AhR antagonist in both cell lines, and the inhibitory effects of the other compound were dependent on cell context. These data suggest that dietary phytochemicals exhibit substantial cell context-dependent AhR agonist as well as antagonist activities. Moreover, because phytochemicals and other AhR-active compounds in food are present in the diet at relatively high concentrations, risk assessment of dietary toxic equivalents of TCDD and related compounds should also take into account AhR agonist/antagonist activities of phytochemicals. PMID:14644660

  16. Chemical function based pharmacophore generation of endothelin-A selective receptor antagonists.

    PubMed

    Funk, Oliver F; Kettmann, Viktor; Drimal, Jan; Langer, Thierry

    2004-05-20

    Both quantitative and qualitative chemical function based pharmacophore models of endothelin-A (ET(A)) selective receptor antagonists were generated by using the two algorithms HypoGen and HipHop, respectively, which are implemented in the Catalyst molecular modeling software. The input for HypoGen is a training set of 18 ET(A) antagonists exhibiting IC(50) values ranging between 0.19 nM and 67 microM. The best output hypothesis consists of five features: two hydrophobic (HY), one ring aromatic (RA), one hydrogen bond acceptor (HBA), and one negative ionizable (NI) function. The highest scoring Hip Hop model consists of six features: three hydrophobic (HY), one ring aromatic (RA), one hydrogen bond acceptor (HBA), and one negative ionizable (NI). It is the result of an input of three highly active, selective, and structurally diverse ET(A) antagonists. The predictive power of the quantitative model could be approved by using a test set of 30 compounds, whose activity values spread over 6 orders of magnitude. The two pharmacophores were tested according to their ability to extract known endothelin antagonists from the 3D molecular structure database of Derwent's World Drug Index. Thereby the main part of selective ET(A) antagonistic entries was detected by the two hypotheses. Furthermore, the pharmacophores were used to screen the Maybridge database. Six compounds were chosen from the output hit lists for in vitro testing of their ability to displace endothelin-1 from its receptor. Two of these are new potential lead compounds because they are structurally novel and exhibit satisfactory activity in the binding assay.

  17. Serotonin (5-HT3) receptor antagonists for the reduction of symptoms of low anterior resection syndrome

    PubMed Central

    Itagaki, Ryohei; Koda, Keiji; Yamazaki, Masato; Shuto, Kiyohiko; Kosugi, Chihiro; Hirano, Atsushi; Arimitsu, Hidehito; Shiragami, Risa; Yoshimura, Yukino; Suzuki, Masato

    2014-01-01

    Purpose Serotonin (5-hydroxytryptamine [5-HT])3 receptor antagonists are effective for the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D), in which exaggerated intestinal/colonic hypermotility is often observed. Recent studies have suggested that the motility disorder, especially spastic hypermotility, seen in the neorectum following sphincter-preserving operations for rectal cancer may be the basis of the postoperative defecatory malfunction seen in these patients. We investigated the efficacy of 5-HT3 receptor antagonists in patients suffering from severe low anterior resection syndrome. Patients and methods A total of 25 male patients with complaints of uncontrollable urgency or fecal incontinence following sphincter-preserving operations were enrolled in this study. Defecatory status, assessed on the basis of incontinence score (0–20), urgency grade (0–3), and number of toilet visits per day, was evaluated using a questionnaire before and 1 month after the administration of the 5-HT3 antagonist ramosetron. Results All the parameters assessed improved significantly after taking ramosetron for 1 month. The effect was more prominent in cases whose anastomotic line was lower, ie, inside the anal canal. Defecatory function was better in patients who commenced ramosetron therapy within 6 months postoperatively, as compared to those who were not prescribed ramosetron for more than 7 months postoperatively. Conclusion These results suggest that 5-HT3 antagonists are effective for the treatment of low anterior resection syndrome, as in diarrhea-predominant irritable bowel syndrome. The improvement in symptoms is not merely time dependent, but it is related to treatment with 5-HT3 antagonists. PMID:24648748

  18. Ciproxifan and chemically related compounds are highly potent and selective histamine H3-receptor antagonists.

    PubMed

    Kathmann, M; Schlicker, E; Marr, I; Werthwein, S; Stark, H; Schunack, W

    1998-12-01

    We determined the affinities of five newly synthesized histamine H3-receptor antagonists in an H3-receptor binding assay and their potencies in a functional H3-receptor model. Furthermore, we determined their potencies in a histamine H2- and H1-receptor model. The compounds differ from histamine in that the ethylamine side chain is replaced by an aryl-substituted propyloxy chain and they differ from one another by varying substituents of the aryl rest. Iodoproxyfan, a highly potent and selective antagonist at H3 receptors, is structurally related to these five compounds. The specific binding of [3H]-Nalpha-methylhistamine to rat brain cortex membranes was monophasically displaced by each of the five compounds at pKi values ranging from 8.24 to 9.27. Inhibition by histamine of the electrically evoked tritium overflow from mouse brain cortex slices preincubated with [3H]noradrenaline was antagonized by all compounds and the concentration-response curve was shifted to the right with apparent pA2 values ranging from 7.78 to 9.39. The five compounds under study possess negligible potencies at histamine H2 and H1 receptors studied in the guinea-pig right atrium and ileum, respectively (pD'2 or pKp values < or = 5.2). The present paper shows that the five compounds under study possess high affinities and potencies at histamine H3 receptors, four out of the five compounds in this respect being equipotent with iodoproxyfan. Like iodoproxyfan, the five compounds show an at least 1000-fold selectivity for H3 as compared to H2 and H1 receptors.

  19. Biochemical characterization of desloratadine, a potent antagonist of the human histamine H(1) receptor.

    PubMed

    Anthes, John C; Gilchrest, Helen; Richard, Christian; Eckel, Stephen; Hesk, Dave; West, Robert E; Williams, Shirley M; Greenfeder, Scott; Billah, Motasim; Kreutner, William; Egan, Robert E

    2002-08-09

    We have characterized desloratadine (5H-benzo[5,6]cyclohepta[1,2-b]pyridine, 8-chloro-6,11-dihydro-11-(4-piperidinylidene), CAS 100643-71-8) as a potent antagonist of the human histamine H(1) receptor. [3H]Desloratadine bound to membranes expressing the recombinant human histamine H(1) receptor in Chinese hamster ovary cells (CHO-H(1)) in a specific and saturable manner with a K(d) of 1.1+/-0.2 nM, a B(max) of 7.9+/-2.0 pmol/mg protein, and an association rate constant of 0.011 nM(-1) x min(-1). The K(d) calculated from the kinetic measurements was 1.5 nM. Dissociation of [3H]desloratadine from the human histamine H(1) receptor was slow, with only 37% of the binding reversed at 6 h in the presence of 5 microM unlabeled desloratadine. Seventeen histamine H(1)-receptor antagonists were evaluated in competition-binding studies. Desloratadine had a K(i) of 0.9+/-0.1 nM in these competition studies. In CHO-H(1) cells, histamine stimulation resulted in a concentration-dependent increase in [Ca(2+)](i) with an EC(50) of 170+/-30 nM. After a 90-min preincubation with desloratadine, the histamine-stimulated increase in [Ca(2+)](i) was shifted to the right, with a depression of the maximal response at higher concentrations of antagonist. The apparent K(b) value was 0.2+/-0.14 nM with a slope of 1.6+/-0.1. The slow dissociation from the receptor and noncompetitive antagonism suggests that desloratadine may be a pseudoirreversible antagonist of the human histamine H(1) receptor. The mechanism of desloratadine antagonism of the human histamine H(1) receptor may help to explain the high potency and 24-h duration of action observed in clinical studies.

  20. Actions of picrodendrin antagonists on dieldrin-sensitive and -resistant Drosophila GABA receptors.

    PubMed Central

    Hosie, A. M.; Ozoe, Y.; Koike, K.; Ohmoto, T.; Nikaido, T.; Sattelle, D. B.

    1996-01-01

    1. A series of terpenoid compounds, recently isolated from Picrodendron baccatum, share a picrotoxane skeleton with picrotoxinin, an antagonist of ionotropic GABA receptors. Referred to as picrodendrins, they inhibit the binding of [35S]-tert-butylbicyclophosphorothionate (TBPS) to rat GABAA receptors. Hitherto, their effects on GABA receptors have not been investigated electrophysiologically. Under two-electrode voltage-clamp, the actions of picrodendrins and related terpenoids have been assayed on homooligomeric GABA receptors formed by the expression of a Drosophila GABA receptor subunit (RDLac) in Xenopus oocytes. 2. All the terpenoids tested, dose-dependently antagonized currents induced by 30 microM (EC50) GABA. 3. Tutin and its analogues (dihydrotutin and isohyenanchin) differ in the structure of their axial C4 substituents. Of these compounds, tutin, which bears an isopropenyl group at this carbon atom, was the most potent antagonist of RDLac homo-oligomers, whereas isohyenanchin, which bears a hydroxyisopropyl group, was the least potent antagonist tested. 4. Picrodendrins differ mainly in the structure of their C9 substituents. The IC50s of picrodendrins ranged from 17 +/- 1.3 nM (picrodendrin-Q) to 1006 +/- 1.3 nM (picrodendrin-O). As such, the most potent picrodendrins (Q, A and B) were approximately equipotent with picrotoxinin as antagonists of RDLac homo-oligomers. 5. Certain picrodendrin compounds effected a use-dependent blockade of RDLac homo-oligomers. Such a biphasic block was not observed with tutin analogues. 6. Picrotoxin-resistant RDLacA3025 homo-oligomers, which have a single amino acid substitution (A302S) in the 2nd transmembrane region, were markedly less sensitive to picrodendrin-O than the wild-type, dieldrin-sensitive, homo-oligomers. 7. The relative potency of tutin analogues demonstrates that the structure-activity relationship of the C4 substituent of picrotoxane-based compounds is conserved in vertebrates and insects. However, the

  1. Novel class of medications, orexin receptor antagonists, in the treatment of insomnia - critical appraisal of suvorexant.

    PubMed

    Norman, Jessica L; Anderson, Sarah L

    2016-01-01

    Insomnia, a highly prevalent disorder, can be detrimental to patients' overall health and worsen existing comorbidities. Patients may have acute episodes of insomnia related to a traumatic event, but more commonly insomnia occurs chronically. While proper sleep hygiene and behavioral therapy play important roles in the nonpharmacologic management of short-term and chronic insomnia, medications may also be required. Historically, insomnia has been treated with agents such as benzodiazepines, nonbenzodiazepine receptor agonists, and melatonin agonists. Dual orexin receptor antagonists represent a new class of medications for the treatment of insomnia, which block the binding of wakefulness-promoting neuropeptides orexin A and orexin B to their respective receptor sites. Suvorexant (Belsomra) is the first dual orexin receptor antagonist to be approved in the US and Japan and has demonstrated efficacy in decreasing time to sleep onset and increasing total sleep time. Its unique mechanism of action, data to support efficacy and safety over 12 months of use, and relative lack of withdrawal effects when discontinued may represent an alternative for patients with chronic insomnia who cannot tolerate or do not receive benefit from more traditional sleep agents. Suvorexant is effective and well tolerated, but precautions exist for certain patient populations, including females, obese patients, and those with respiratory disease. Suvorexant has only been studied vs placebo, and hence it is unknown how it directly compares with other medications approved by the US Food and Drug Administration for insomnia. Suvorexant is not likely to replace benzodiazepines or nonbenzodiazepine receptor antagonists as a first-line sleep agent but does represent a novel option for the treatment of patients with chronic insomnia.

  2. A covalent antagonist for the human adenosine A2A receptor.

    PubMed

    Yang, Xue; Dong, Guo; Michiels, Thomas J M; Lenselink, Eelke B; Heitman, Laura; Louvel, Julien; IJzerman, Ad P

    2016-12-03

    The structure of the human A2A adenosine receptor has been elucidated by X-ray crystallography with a high affinity non-xanthine antagonist, ZM241385, bound to it. This template molecule served as a starting point for the incorporation of reactive moieties that cause the ligand to covalently bind to the receptor. In particular, we incorporated a fluorosulfonyl moiety onto ZM241385, which yielded LUF7445 (4-((3-((7-amino-2-(furan-2-yl)-[1, 2, 4]triazolo[1,5-a][1, 3, 5]triazin-5-yl)amino)propyl)carbamoyl)benzene sulfonyl fluoride). In a radioligand binding assay, LUF7445 acted as a potent antagonist, with an apparent affinity for the hA2A receptor in the nanomolar range. Its apparent affinity increased with longer incubation time, suggesting an increasing level of covalent binding over time. An in silico A2A-structure-based docking model was used to study the binding mode of LUF7445. This led us to perform site-directed mutagenesis of the A2A receptor to probe and validate the target lysine amino acid K153 for covalent binding. Meanwhile, a functional assay combined with wash-out experiments was set up to investigate the efficacy of covalent binding of LUF7445. All these experiments led us to conclude LUF7445 is a valuable molecular tool for further investigating covalent interactions at this receptor. It may also serve as a prototype for a therapeutic approach in which a covalent antagonist may be needed to counteract prolonged and persistent presence of the endogenous ligand adenosine.

  3. A neutral CB1 receptor antagonist reduces weight gain in rat.

    PubMed

    Chambers, Adam P; Vemuri, V Kiran; Peng, Yan; Wood, Jodianne T; Olszewska, Teresa; Pittman, Quentin J; Makriyannis, Alexandros; Sharkey, Keith A

    2007-12-01

    Cannabinoid (CB)1 receptor inverse agonists inhibit food intake in animals and humans but also potentiate emesis. It is not clear whether these effects result from inverse agonist properties or from the blockade of endogenous cannabinoid signaling. Here, we examine the effect of a neutral CB1 antagonist, AM4113, on food intake, weight gain, and emesis. Neutral antagonist and binding properties were confirmed in HEK-293 cells transfected with human CB1 or CB2 receptors. AM4113 had no effect on forskolin-stimulated cAMP production at concentrations up to 630 nM. The Ki value of AM4113 (0.80 +/- 0.44 nM) in competitive binding assays with the CB1/2 agonist [3H]CP55,940 was 100-fold more selective for CB1 over CB2 receptors. We determined that AM4113 antagonized CB1 receptors in brain by blocking hypothermia induced by CP55,940. AM4113 (0-20 mg/kg) significantly reduced food intake and weight gain in rat. Compared with AM251, higher doses of AM4113 were needed to produce similar effects on food intake and body weight. Unlike AM251 (5 mg/kg), a highly anorectic dose of AM4113 (10 mg/kg) did not significantly potentiate vomiting induced by the emetic morphine-6-glucoronide. We show that a centrally active neutral CB1 receptor antagonist shares the appetite suppressant and weight loss effects of inverse agonists. If these compounds display similar properties in humans, they could be developed into a new class of antiobesity agents.

  4. IL-1 receptor antagonist improves morphine and buprenorphine efficacy in a rat neuropathic pain model.

    PubMed

    Pilat, Dominika; Rojewska, Ewelina; Jurga, Agnieszka M; Piotrowska, Anna; Makuch, Wioletta; Przewlocka, Barbara; Mika, Joanna

    2015-10-05

    An interesting research and therapeutic problem is the reduced beneficial efficacy of opioids in the treatment of neuropathic pain. The present study sought to investigate the potential role of IL-1 family members in this phenomenon. We studied the time course of changes in IL-1alpha, IL-1beta, IL-1 receptor type I and IL-1 receptor antagonist mRNA and protein levels experienced by rats after chronic constriction injury (CCI) of the sciatic nerve using qRT-PCR and Western blot analysis. In CCI-exposed rats, spinal levels of IL-1alpha mRNA were slightly downregulated on the 7th day, and protein levels were not changed on the 7th and 14th days. Levels of IL-1 receptor antagonist and IL-1 receptor type I were slightly upregulated in the ipsilateral part of the spinal cord on the 7th and 14th days; however, protein levels were not changed at those time points. Interestingly, we observed that IL-1beta mRNA and protein levels were strongly elevated in the ipsilateral part of the dorsal spinal cord on the 7th and 14th days following CCI. Moreover, in rats exposed to a single intrathecal administration of an IL-1 receptor antagonist (100 ng i.t.) on the 7th and 14th day following CCI, symptoms of neuropathic pain were attenuated, and the analgesic effects of morphine (2.5 µg i.t.) and buprenorphine (2.5 µg i.t.) were enhanced. In summary, restoration of the analgesic activity of morphine and buprenorphine by blockade of IL-1 signaling suggests that increased IL-1beta responses may account for the decreased analgesic efficacy of opioids observed in the treatment of neuropathy.

  5. Discovery of novel dihydrobenzofuran cyclopropane carboxylic acid based calcium sensing receptor antagonists for the treatment of osteoporosis.

    PubMed

    Liang, Gui-Bai; Zhou, Changyou; Huo, Xianghong; Wang, Hank; Yang, Xuelin; Huang, Shaoqiang; Wang, Haisheng; Wilkinson, Hilary; Luo, Lusong; Tang, Wei; Sutton, David; Li, Hong; Zaller, Dennis; Meinke, Peter T

    2016-08-15

    In a search for novel small molecule calcium-sensing receptor (CaSR) antagonists as oral bone anabolic agents, we discovered dihydrobenzofuran cyclopropane carboxylic acid derivatives, such as 12f (IC50=27.6nM), are highly potent calcium-sensing receptor antagonists. Studies in rats established that compound 12f stimulates parathyroid hormone (PTH) release in a fast-acting, pulsatile manner.

  6. Responding for a conditioned reinforcer, and its enhancement by nicotine, is blocked by dopamine receptor antagonists and a 5-HT(2C) receptor agonist but not by a 5-HT(2A) receptor antagonist.

    PubMed

    Guy, Elizabeth Glenn; Fletcher, Paul J

    2014-10-01

    An aspect of nicotine reinforcement that may contribute to tobacco addiction is the effect of nicotine to enhance the motivational properties of reward-associated cues, or conditioned stimuli (CSs). Several studies have now shown that nicotine enhances responding for a stimulus that has been paired with a natural reinforcer. This effect of nicotine to enhance responding for a conditioned reinforcer is likely due to nicotine-induced enhancements in mesolimbic dopaminergic activity, but this has not been directly assessed. In this study, we assessed roles for dopamine (DA) D1 or D2 receptors, and two serotonin (5-HT) receptor subtypes known to modulate DA activity, the 5-HT2C or 5-HT2A subtypes, on nicotine-enhanced responding for a conditioned reinforcer. Water-restricted rats were exposed to Pavlovian conditioning sessions, where a CS was paired with water delivery. Then, in a second phase, animals were required to perform a novel, lever-pressing response for presentations of the CS as a conditioned reinforcer. Nicotine (0.4 mg/kg) enhanced responding for the conditioned reinforcer. To examine potential roles for dopamine (DA) and serotonin (5-HT) receptors in this effect, separate groups of animals were used to assess the impact of administering the D1 receptor antagonist SCH 23390, D2 receptor antagonist eticlopride, 5-HT2C receptor agonist Ro 60-0175, or 5-HT2A receptor antagonist M100907 on nicotine-enhanced responding for conditioned reinforcement. SCH 23390, eticlopride, and Ro 60-0175 all reduced responding for conditioned reinforcement, and the ability of nicotine to enhance this effect. M100907 did not alter this behavior. Together, these studies indicate that DA D1 and D2 receptors, but not 5-HT2A receptors, contribute to the effect of nicotine to enhance responding for a conditioned reinforcer. This effect can also be modulated by 5-HT2C receptor activation.

  7. A cannabinoid CB(1) receptor antagonist ameliorates impairment of recognition memory on withdrawal from MDMA (Ecstasy).

    PubMed

    Nawata, Yoko; Hiranita, Takato; Yamamoto, Tsuneyuki

    2010-01-01

    (+/-)-3,4-Methylenedioxymethamphetamine (MDMA, 'Ecstasy') abusers have persistent neuropsychiatric deficits including memory impairments after the cessation of abuse. On the other hand, cannabinoid CB(1) receptors have been implicated in learning/memory, and are highly expressed in the hippocampus, a region of the brain believed to have an important function in certain forms of learning and memory. In this study, we clarified the mechanism underlying the cognitive impairment that develops during MDMA withdrawal from the standpoint of the cannabinoid CB(1) receptors. Mice were administered MDMA (10 mg/kg, i.p.) once a day for 7 days. On the 7th day of withdrawal, a novel object recognition task was performed and the amount of cannabinoid CB(1) receptor protein was measured with western blotting. Recognition performance was impaired on the 7th day of withdrawal. This impairment was blocked by AM251, a cannabinoid CB(1) receptor antagonist, administered 30 min before the training trial or co-administered with MDMA. At this time, the level of cannabinoid CB(1) receptor protein increased significantly in the hippocampus but not the prefrontal cortex or striatum. This increase of CB(1) receptor protein in the hippocampus was also blocked by the co-administration of AM251. Furthermore, CB(1) receptor knockout mice showed no impairment of recognition performance on the withdrawal from MDMA. The impairment of recognition memory during withdrawal from MDMA may result from the activation of cannabinoid CB(1) receptors in the hippocampus.

  8. Central interactions of aldosterone and angiotensin II in aldosterone- and angiotensin II-induced hypertension.

    PubMed

    Xue, Baojian; Beltz, Terry G; Yu, Yang; Guo, Fang; Gomez-Sanchez, Celso E; Hay, Meredith; Johnson, Alan Kim

    2011-02-01

    Many studies have implicated both angiotensin II (ANG II) and aldosterone (Aldo) in the pathogenesis of hypertension, the progression of renal injury, and cardiac remodeling after myocardial infarction. In several cases, ANG II and Aldo have been shown to have synergistic interactions in the periphery. In the present studies, we tested the hypothesis that ANG II and Aldo interact centrally in Aldo- and ANG II-induced hypertension in male rats. In rats with blood pressure (BP) and heart rate (HR) measured by DSI telemetry, intracerebroventricular (icv) infusions of the mineralocorticoid receptor (MR) antagonists spironolactone and RU28318 or the angiotensin type 1 receptor (AT1R) antagonist irbesartan significantly inhibited Aldo-induced hypertension. In ANG II-induced hypertension, icv infusion of RU28318 significantly reduced the increase in BP. Moreover, icv infusions of the reactive oxygen species (ROS) scavenger tempol or the NADPH oxidase inhibitor apocynin attenuated Aldo-induced hypertension. To confirm these effects of pharmacological antagonists, icv injections of either recombinant adeno-associated virus carrying siRNA silencers of AT1aR (AT1aR-siRNA) or MR (MR-siRNA) significantly attenuated the development of Aldo-induced hypertension. The immunohistochemical and Western blot analyses of AT1aR-siRNA- or MR-siRNA-injected rats showed a marked reduction in the expression of AT1R or MR in the paraventricular nucleus compared with scrambled siRNA rats. When animals from all studies underwent ganglionic blockade with hexamethonium, there was a smaller reduction in the fall of BP in animals receiving icv AT1R or MR antagonists. These results suggest that ANG II and Aldo interact in the brain in a mutually cooperative manner such that the functional integrity of both brain AT1R and MR are necessary for hypertension to be induced by either systemic ANG II or Aldo. The pressor effects produced by systemic ANG II or Aldo involve increased central ROS and

  9. First pharmacophore model of CCR3 receptor antagonists and its homology model-assisted, stepwise virtual screening.

    PubMed

    Jain, Vaibhav; Saravanan, Parameswaran; Arvind, Akanksha; Mohan, Chethampadi Gopi

    2011-05-01

    CCR3, a G protein-coupled receptor, plays a central role in allergic inflammation and is an important drug target for inflammatory diseases. To understand the structure-function relationship of CCR3 receptor, different computational techniques were employed, which mainly include: (i) homology modeling of CCR3 receptor, (ii) 3D-quantitative pharmacophore model of CCR3 antagonists, (iii) virtual screening of small compound databases, and (iv) finally, molecular docking at the binding site of the CCR3 receptor homology model. Pharmacophore model was developed for the first time, on a training data set of 22 CCR3 antagonists, using CATALYST HypoRefine program. Best hypothesis (Hypo1) has three different chemical features: two hydrogen-bond acceptors, one hydrophobic, and one ring aromatic. Hypo1 model was further validated using (i) 87 test set CCR3 antagonists, (ii) Cat Scramble randomization technique, and (iii) Decoy data set. Molecular docking studies were performed on modeled CCR3 receptor using 303 virtually screened hits, obtained from small compound database virtual screening. Finally, five hits were identified as potential leads against CCR3 receptor, which exhibited good estimated activities, favorable binding interactions, and high docking scores. These studies provided useful information on the structurally vital residues of CCR3 receptor involved in the antagonist binding, and their unexplored potential for the future development of potent CCR3 receptor antagonists.

  10. (±)-Nantenine analogs as antagonists at human 5-HT2A receptors: C1 and flexible congeners

    PubMed Central

    Chaudhary, Sandeep; Pecic, Stevan; LeGendre, Onica; Navarro, Hérnan A.; Harding, Wayne W.

    2009-01-01

    C1 and flexible analogs of (±)-nantenine were synthesized and evaluated for antagonist activity at human 5-HT2A receptors in a calcium mobilization assay. This work has resulted in the identification of the most potent 5-HT2A antagonist known based on an aporphine. Our results also suggest that the C1 position may be a key site for increasing 5-HT2A antagonist activity in this compound series. In addition, the structural rigidity of the aporphine core appears to be required for nantenine to function as a 5-HT2A antagonist. PMID:19328689

  11. Label-Free Kinetics: Exploiting Functional Hemi-Equilibrium to Derive Rate Constants for Muscarinic Receptor Antagonists.

    PubMed

    Riddy, Darren M; Valant, Celine; Rueda, Patricia; Charman, William N; Sexton, Patrick M; Summers, Roger J; Christopoulos, Arthur; Langmead, Christopher J

    2015-10-01

    Drug receptor kinetics is as a key component in drug discovery, development, and efficacy; however, determining kinetic parameters has historically required direct radiolabeling or competition with a labeled tracer. Here we present a simple approach to determining the kinetics of competitive antagonists of G protein-coupled receptors by exploiting the phenomenon of hemi-equilibrium, the state of partial re-equilibration of agonist, antagonist, and receptor in some functional assays. Using functional [Ca(2+)]i-flux and extracellular kinases 1 and 2 phosphorylation assays that have short incubation times and therefore are prone to hemi-equilibrium "behaviors," we investigated a wide range of structurally and physicochemically distinct muscarinic acetylcholine receptor antagonists. Using a combined operational and hemi-equilibrium model of antagonism to both simulate and analyze data, we derived estimates of association and dissociation rates for the test set of antagonists, identifying both rapidly dissociating (4-DAMP, himbacine) and slowly dissociating (tiotropium, glycopyrrolate) ligands. The results demonstrate the importance of assay incubation time and the degree of receptor reserve in applying the analytical model. There was an excellent correlation between estimates of antagonist pK(B), k(on), and k(off) from functional assays and those determined by competition kinetics using whole-cell [(3)H]N-methylscopolamine binding, validating this approach as a rapid and simple method to functionally profile receptor kinetics of competitive antagonists in the absence of a labeled tracer.

  12. Recent Patents on Novel P2X7 Receptor Antagonists and Their Potential for Reducing Central Nervous System Inflammation

    PubMed Central

    Friedle, Scott A.; Curet, Marjorie A.; Watters, Jyoti J.

    2009-01-01

    Inflammation arises in the CNS from a number of neurodegenerative and oncogenic disorders, as well as from ischemic and traumatic brain injuries. These pathologies give rise to increased levels of extracellular adenine nucleotides which, via activation of a variety of cell surface P2 purinergic receptors, influence the inflammatory activities of responding immune cells. One P2 receptor subtype in particular, the P2X7 receptor, potentiates the release of pro-inflammatory cytokines, such as interleukin-1β (IL-1β) from macrophage-like cells. It is also thought to contribute to secondary brain injury by inducing neuronal cell death. Therefore, antagonism of this receptor could have significant therapeutic impact on all disorders, not just CNS, to which excessive inflammatory activities contribute. The use of currently available P2X7 receptor antagonists for the treatment of CNS inflammation has been limited to the generally non-selective antagonists PPADS, oxidized ATP, Brilliant Blue G, suramin, calmidizolium, and KN-62. However, the recent patents and development of novel P2X7 receptor antagonists, as discussed in this review, will provide new tools both for clinical and research purposes. Here we discuss compounds for which patents have been applied since 2006, from the following categories: benzamide inhibitors, bicycloheteroaryl compounds, acylhdranzine antagonists, biaromatic P2X7 antagonists, heterocyclic compounds and amide derivatives, and aromatic amine antagonists. PMID:19705995

  13. Nonpeptidic urotensin-II receptor antagonists I: in vitro pharmacological characterization of SB-706375

    PubMed Central

    Douglas, Stephen A; Behm, David J; Aiyar, Nambi V; Naselsky, Diane; Disa, Jyoti; Brooks, David P; Ohlstein, Eliot H; Gleason, John G; Sarau, Henry M; Foley, James J; Buckley, Peter T; Schmidt, Dulcie B; Wixted, William E; Widdowson, Katherine; Riley, Graham; Jin, Jian; Gallagher, Timothy F; Schmidt, Stanley J; Ridgers, Lance; Christmann, Lisa T; Keenan, Richard M; Knight, Steven D; Dhanak, Dashyant

    2005-01-01

    SB-706375 potently inhibited [125I]hU-II binding to both mammalian recombinant and ‘native' UT receptors (Ki 4.7±1.5 to 20.7±3.6 nM at rodent, feline and primate recombinant UT receptors and Ki 5.4±0.4 nM at the endogenous UT receptor in SJRH30 cells). Prior exposure to SB-706375 (1 μM, 30 min) did not alter [125I]hU-II binding affinity or density in recombinant cells (KD 3.1±0.4 vs 5.8±0.9 nM and Bmax 3.1±1.0 vs 2.8±0.8 pmol mg−1) consistent with a reversible mode of action. The novel, nonpeptidic radioligand [3H]SB-657510, a close analogue of SB-706375, bound to the monkey UT receptor (KD 2.6±0.4 nM, Bmax 0.86±0.12 pmol mg−1) in a manner that was inhibited by both U-II isopeptides and SB-706375 (Ki 4.6±1.4 to 17.6±5.4 nM) consistent with the sulphonamides and native U-II ligands sharing a common UT receptor binding domain. SB-706375 was a potent, competitive hU-II antagonist across species with pKb 7.29–8.00 in HEK293-UT receptor cells (inhibition of [Ca2+]i-mobilization) and pKb 7.47 in rat isolated aorta (inhibition of contraction). SB-706375 also reversed tone established in the rat aorta by prior exposure to hU-II (Kapp∼20 nM). SB-706375 was a selective U-II antagonist with ⩾100-fold selectivity for the human UT receptor compared to 86 distinct receptors, ion channels, enzymes, transporters and nuclear hormones (Ki/IC50>1 μM). Accordingly, the contractile responses induced in isolated aortae by KCl, phenylephrine, angiotensin II and endothelin-1 were unaltered by SB-706375 (1 μM). In summary, SB-706375 is a high-affinity, surmountable, reversible and selective nonpeptide UT receptor antagonist with cross-species activity that will assist in delineating the pathophysiological actions of U-II in mammals. PMID:15852036

  14. Lack of NMDA-AMPA interaction in antidepressant-like effect of CGP 37849, an antagonist of NMDA receptor, in the forced swim test.

    PubMed

    Dybała, Małgorzata; Siwek, Agata; Poleszak, Ewa; Pilc, Andrzej; Nowak, Gabriel

    2008-11-01

    The NMDA receptor antagonist, CGP 37849-induced reduction in immobility time in the forced swim test in mice was not antagonized by pre-treatment with the AMPA receptor antagonist NBQX. This is the first demonstration of the antidepressant effect of the NMDA antagonist not being dependent on the AMPA transmission.

  15. Interactions of antagonists with subtypes of inositol 1,4,5-trisphosphate (IP3) receptor

    PubMed Central

    Saleem, Huma; Tovey, Stephen C; Molinski, Tedeusz F; Taylor, Colin W

    2014-01-01

    BACKGROUND AND PURPOSE Inositol 1,4,5-trisphosphate receptors (IP3Rs) are intracellular Ca2+ channels. Interactions of the commonly used antagonists of IP3Rs with IP3R subtypes are poorly understood. EXPERIMENTAL APPROACH IP3-evoked Ca2+ release from permeabilized DT40 cells stably expressing single subtypes of mammalian IP3R was measured using a luminal Ca2+ indicator. The effects of commonly used antagonists on IP3-evoked Ca2+ release and 3H-IP3 binding were characterized. KEY RESULTS Functional analyses showed that heparin was a competitive antagonist of all IP3R subtypes with different affinities for each (IP3R3 > IP3R1 ≥ IP3R2). This sequence did not match the affinities for heparin binding to the isolated N-terminal from each IP3R subtype. 2-aminoethoxydiphenyl borate (2-APB) and high concentrations of caffeine selectively inhibited IP3R1 without affecting IP3 binding. Neither Xestospongin C nor Xestospongin D effectively inhibited IP3-evoked Ca2+ release via any IP3R subtype. CONCLUSIONS AND IMPLICATIONS Heparin competes with IP3, but its access to the IP3-binding core is substantially hindered by additional IP3R residues. These interactions may contribute to its modest selectivity for IP3R3. Practicable concentrations of caffeine and 2-APB inhibit only IP3R1. Xestospongins do not appear to be effective antagonists of IP3Rs. PMID:24628114

  16. Devazepide, a nonpeptide antagonist of CCK receptors, induces apoptosis and inhibits Ewing tumor growth.

    PubMed

    Carrillo, Jaime; Agra, Noelia; Fernández, Noemí; Pestaña, Angel; Alonso, Javier

    2009-08-01

    The Ewing family of tumors is a group of highly malignant tumors that mainly arise in bone and most often affect children and young adults in the first two decades of life. Despite the use of multimodal therapy, the long-term disease-free survival rate of patients with Ewing tumors is still disappointingly low, making the discovery of innovative therapeutic strategies all the more necessary. We have recently shown that cholecystokinin (CCK), a neuroendocrine peptide, involved in many biological functions, including cell growth and proliferation, is a relevant target of the EWS/FLI1 oncoprotein characteristic of Ewing tumors. CCK silencing inhibits cell proliferation and tumor growth in vivo, suggesting that CCK acts as an autocrine growth factor for Ewing cells. Here, we analyzed the impact of two CCK receptor antagonists, devazepide (a CCK1-R antagonist) and L365 260 (a CCK2-R antagonist), on the growth of Ewing tumor cells. Devazepide (10 micromol/l) inhibited cell growth of four different Ewing tumor cells in vitro (range 85-88%), whereas the effect of the CCK2-R antagonist on cell growth was negligible. In a mouse tumor xenograft model, devazepide reduced tumor growth by 40%. Flow cytometry experiments showed that devazepide, but not L365 260, induced apoptosis of Ewing tumor cells. In summary, devazepide induces cell death of Ewing tumor cells, suggesting that it could represent a new therapeutic approach in the management of Ewing's tumor patients.

  17. Simulations reveal increased fluctuations in estrogen receptor-alpha conformation upon antagonist binding.

    PubMed

    Ng, Ho Leung

    2016-09-01

    Molecular dynamics (MD) simulations have been used to model dynamic fluctuations in the structure of estrogen receptor-alpha (ER-α) upon binding to the natural agonist 17β-estradiol (E2) and to the active metabolite of the breast cancer drug and antagonist, 4-hydroxytamoxifen (OHT). We present the most extensive MD simulations to date of ER-α, with over 1μs of combined simulations for the monomer and dimer forms. Simulations reveal that the antagonist-bound complex includes significant fluctuations while the agonist-bound complex is tightly restrained. OHT increases dynamic disorder in the loops located to either side of the tail H12 helix; H12 has been associated with the activation status of ER-α. We also report that fluctuations near H12 lead to greater conformational variation in the binding mode of the ethylamine tail of OHT. Both the agonist and antagonist conformations are stable throughout the 240ns simulations, supporting the hypothesis that there are no transitions between these two states or into intermediate states. The stable position of H12 in the OHT-bound conformation suggests that OHT stabilizes a well-defined antagonist conformational ensemble rather than merely blocking the agonist-driven activation of ER-α. Simultaneously, the increased dynamic properties of the OHT-bound complex is a potential source of binding entropy.

  18. Monovalent mannose-based DC-SIGN antagonists: targeting the hydrophobic groove of the receptor.

    PubMed

    Tomašić, Tihomir; Hajšek, David; Švajger, Urban; Luzar, Jernej; Obermajer, Nataša; Petit-Haertlein, Isabelle; Fieschi, Franck; Anderluh, Marko

    2014-03-21

    Dendritic cell-specific, intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is a C-type lectin expressed specifically on dendritic cells. It is a primary site for recognition and binding of various pathogens and thus a promising therapeutic target for inhibition of pathogen entry and subsequent prevention of immune defense cell infection. We report the design and synthesis of d-mannose-based DC-SIGN antagonists bearing diaryl substituted 1,3-diaminopropanol or glycerol moieties incorporated to target the hydrophobic groove of the receptor. The designed glycomimetics were evaluated by in vitro assay of the isolated DC-SIGN extracellular domain for their ability to compete with HIV-1 gp120 for binding to the DC-SIGN carbohydrate recognition domain. Compounds 14d and 14e, that display IC50 values of 40 μM and 50 μM, are among the most potent monovalent DC-SIGN antagonists reported. The antagonistic effect of all the synthesized compounds was further evaluated by a one-point in vitro assay that measures DC adhesion. Compounds 14d, 14e, 18d and 18e were shown to act as functional antagonists of DC-SIGN-mediated DC adhesion. The binding mode of 14d was also studied by molecular docking and molecular dynamics simulation, which revealed flexibility of 14d in the binding site and provides a basis for further optimization.

  19. Novel endomorphin analogues with antagonist activity at the mu-opioid receptor in the gastrointestinal tract.

    PubMed

    Fichna, Jakub; Gach, Katarzyna; Perlikowska, Renata; Cravezic, Aurore; Bonnet, Jean Jacques; do-Rego, Jean-Claude; Janecka, Anna; Storr, Martin A

    2010-06-08

    Opioid bowel dysfunction (OBD) summarizes common adverse side effects of opiate-based management of pain. A promising therapeutic approach to prevent OBD and other opioid-related disorders of the gastrointestinal (GI) tract is the co-administration of opiates with peripherally-restricted mu-opioid receptor (MOR)-selective antagonists. The aim of this study was to investigate the selectivity and efficacy of three novel peptide antagonists: antanal-1, antanal-2, and antanal-2A at MOR in the GI tract in vitro and in vivo. The effects of the antanals on GI motility were studied in vitro, using isolated preparations of mouse ileum and colon and in vivo, by measuring colonic propulsion in mice. Additionally, in vitro stability against enzymatic degradation and blood-brain barrier (BBB) permeability using the hot plate test in mice were examined. The antanals significantly reduced the inhibitory effect of the MOR agonists endomorphin-2, morphine, and loperamide on mouse ileum and colon contractions in vitro and blocked morphine-induced decrease of colonic bead expulsion in vivo. The hot plate test in mice showed that the antagonist activity of all antanals was restricted to the periphery. Antanal-1, antanal-2, and antanal-2A are promising MOR antagonists with limited BBB permeability, which may be developed into future therapeutics of opioid-related GI dysfunction.

  20. Receptor binding and selectivity of three 11C-labelled dopamine receptor antagonists in the brain of rhesus monkeys studied with positron emission tomography.

    PubMed

    Hartvig, P; Eckernäs, S A; Ekblom, B; Lindström, L; Lundqvist, H; Axelsson, S; Fasth, K J; Gullberg, P; Långström, B

    1988-04-01

    The regional distribution of 3 11C-labelled dopamine receptor antagonists, N-methyl spiperone, raclopride and clozapine, in the brain of Rhesus monkeys was studied by positron emission tomography (PET). The measured radioactivities in the striatal area were similar for the 3 antagonists, although the highest selectivity as compared to cerebellum was found for 11C-raclopride 60 min after administration. The selectivity of the radiotracers for the serotonin and D2-dopamine receptors was evaluated after pretreatment of the monkeys with serotonin and dopamine receptor antagonists. 11C-N-methylspiperone and 11C-clozapine both bound to serotonin receptors in the frontal cortex and to D2-dopamine receptors in the striatal area. Raclopride was selectively bound to the D2-dopamine receptors. The radioactivities measured in the striatal area with cerebellum as reference were fitted to a 3-compartment model which made possible evaluation of receptor binding characteristics. The rate proportional to the association rate constant for the receptor, kon and number of receptors, Bmax, varied from 0.02-0.07 min-1 between the studied radiolabelled drugs, whereas the apparent dissociation rate was highest for clozapine. This means that clozapine had the lowest affinity for the receptors in the striatum, assuming that the Bmax values are identical. The observed difference in selective receptor binding and binding characteristics of the 3 tracers may have an influence both on the clinical efficacy and side effects of the studied dopamine receptor antagonists.

  1. Structure of CC chemokine receptor 2 with orthosteric and allosteric antagonists

    SciTech Connect

    Zheng, Yi; Qin, Ling; Zacarías, Natalia V. Ortiz; de Vries, Henk; Han, Gye Won; Gustavsson, Martin; Dabros, Marta; Zhao, Chunxia; Cherney, Robert J.; Carter, Percy; Stamos, Dean; Abagyan, Ruben; Cherezov, Vadim; Stevens, Raymond C.; IJzerman, Adriaan P.; Heitman, Laura H.; Tebben, Andrew; Kufareva, Irina; Handel, Tracy M.

    2016-12-07

    CC chemokine receptor 2 (CCR2) is one of 19 members of the chemokine receptor subfamily of human class A G-protein-coupled receptors. CCR2 is expressed on monocytes, immature dendritic cells, and T-cell subpopulations, and mediates their migration towards endogenous CC chemokine ligands such as CCL2 (ref. 1). CCR2 and its ligands are implicated in numerous inflammatory and neurodegenerative diseases2 including atherosclerosis, multiple sclerosis, asthma, neuropathic pain, and diabetic nephropathy, as well as cancer3. These disease associations have motivated numerous preclinical studies and clinical trials4 (see http://www.clinicaltrials.gov) in search of therapies that target the CCR2–chemokine axis. To aid drug discovery efforts5, here we solve a structure of CCR2 in a ternary complex with an orthosteric (BMS-681 (ref. 6)) and allosteric (CCR2-RA-[R]7) antagonist. BMS-681 inhibits chemokine binding by occupying the orthosteric pocket of the receptor in a previously unseen binding mode. CCR2-RA-[R] binds in a novel, highly druggable pocket that is the most intracellular allosteric site observed in class A G-protein-coupled receptors so far; this site spatially overlaps the G-protein-binding site in homologous receptors. CCR2-RA-[R] inhibits CCR2 non-competitively by blocking activation-associated conformational changes and formation of the G-protein-binding interface. The conformational signature of the conserved microswitch residues observed in double-antagonist-bound CCR2 resembles the most inactive G-protein-coupled receptor structures solved so far. Like other protein–protein interactions, receptor–chemokine complexes are considered challenging therapeutic targets for small molecules, and the present structure suggests diverse pocket epitopes that can be exploited to overcome obstacles in drug design.

  2. Selective 5-hydroxytryptamine2 receptor antagonists protect against the neurotoxicity of methylenedioxymethamphetamine in rats.

    PubMed

    Schmidt, C J; Abbate, G M; Black, C K; Taylor, V L

    1990-11-01

    The serotonergic deficits resulting from methylenedioxymethamphetamine (MDMA)-induced neurotoxicity were prevented by the simultaneous administration of 5-hydroxytryptamine2 (5-HT2) receptor antagonists such as MDL 11,939 or ritanserin. This effect was not region specific as protection was observed in the cortex, hippocampus and striatum 1 week after the administration of a single dose of MDMA. MDL 11,939 also showed some efficacy at reducing the deficits in 5-HT concentrations and tryptophan hydroxylase activity produced by multiple administrations of MDMA. Protection against the neurotoxicity required the administration of MDL 11,939 within 1 hr of MDMA indicating 5-HT2 receptor activation was an early event in the process leading to terminal damage. Examination of the effect of the 5-HT2 receptor blockade on the early neurochemical alterations induced by MDMA revealed an inhibitory effect on MDMA-stimulated dopamine synthesis. Analysis of these data and the associated changes in dopamine metabolites indicates that 5-HT2 receptor antagonists block MDMA-induced neurotoxicity by interfering with the ability of the dopamine neuron to maintain its cytoplasmic pool of transmitter and thereby sustain carrier-mediated dopamine release.

  3. Guanidino acids act as rho1 GABA(C) receptor antagonists.

    PubMed

    Chebib, Mary; Gavande, Navnath; Wong, Kit Yee; Park, Anna; Premoli, Isabella; Mewett, Kenneth N; Allan, Robin D; Duke, Rujee K; Johnston, Graham A R; Hanrahan, Jane R

    2009-10-01

    GABA(C) receptors play a role in myopia, memory-related disorders and circadian rhythms signifying a need to develop potent and selective agents for this class of receptors. Guanidino analogs related to glycine, beta-alanine and taurine were evaluated at human rho(1)GABA(C) receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. Of the 12 analogs tested, 8 analogs were active as antagonists and the remaining were inactive. (S)-2-guanidinopropionic acid (IC(50) = 2.2 microM) and guanidinoacetic acid (IC(50) = 5.4 microM; K (B) = 7.75 microM [pK (B) = 5.11 +/- 0.06]) were the most potent being competitive antagonists at this receptor. In contrast, the beta-alanine and GABA guanidino analogs showed reduced activity, indicating the distance between the carboxyl carbon and terminal nitrogen of the guanidino group is critical for activity. Substituting the C2-position of guanidinoacetic acid with various alkyl groups reduced activity indicating that steric effects may impact on activity. The results of this study contribute to the structure-activity-relationship profile required in developing novel therapeutic agents.

  4. Synthesis and pharmacological evaluation of dimer derivatives of the bradykinin receptor antagonist HOE-140.

    PubMed

    Daffix, I; Amblard, M; Bergé, G; Dodey, P; Pruneau, D; Paquet, J L; Fouchet, C; Franck, R M; Defrêne, E; Luccarini, J M; Bélichard, P; Martinez, J

    1998-07-01

    The synthesis and pharmacological evaluation of dimer derivatives of the C-terminal fragments of the potent bradykinin antagonist HOE-140, linked through their N-termini, were performed. The influence of peptide moiety length was studied using the succinyl moiety as a linker. Our attention focused on the dimer of the C-terminal tetrapeptide of HOE-140 (compound JMV 980), which displayed some inhibiting activity (IC50 = 247 nM) for bradykinin B2 receptors. Unexpectedly, it was orally active in inhibiting bradykinin-induced hypotension in the rat. Based on this tetrapeptide dimer model, we synthesized pseudotetrapeptide dimer bradykinin antagonists 29 and 33, which exhibited high affinity (Ki = 76 and 61 nM, respectively) for the human cloned B2 receptor. In addition, compound 29 inhibited bradykinin-induced contraction of the human umbilical vein giving a pKB value of 6.45. Compounds 29 and 33 were selective toward B2 receptors because they did not bind to the cloned human B1 receptor up to 10 microM.

  5. Novel antagonists of serotonin-4 receptors: synthesis and biological evaluation of pyrrolothienopyrazines.

    PubMed

    Lemaître, Stéphane; Lepailleur, Alban; Bureau, Ronan; Butt-Gueulle, Sabrina; Lelong-Boulouard, Véronique; Duchatelle, Pascal; Boulouard, Michel; Dumuis, Aline; Daveu, Cyril; Lezoualc'h, Frank; Pfeiffer, Bruno; Dauphin, François; Rault, Sylvain

    2009-03-15

    Based on the definition of a 5-HT(4) receptor antagonist pharmacophore, a series of pyrrolo[1,2-a]thieno[3,2-e] and pyrrolo[1,2-a]thieno[2,3-e] pyrazine derivatives were designed, prepared, and evaluated to determine the properties necessary for high-affinity binding to 5-HT(4) receptors. The compounds were synthesized by substituting the chlorine atom of the pyrazine ring with various N-alkyl-4-piperidinylmethanolates. They were evaluated in binding assays with [(3)H]GR113808 (1) as the 5-HT(4) receptor radioligand. The affinity values (K(i) or inhibition percentages) were affected by both the substituent on the aromatic ring and the substituent on the lateral piperidine chain. A methyl group on the tricyclic ring produced a marked increase in affinity while an N-propyl or N-butyl group gave compounds with nanomolar affinities. Among the most potent ligands, 34d was selected for further pharmacological studies and evaluated in vivo. This compound acts as an antagonist/weak partial agonist in COS-7 cells stably expressing the 5-HT(4(a)) receptor and is of great interest as a peripheral antinociceptive agent.

  6. Synthesis and evaluation of novel angiotensin II receptor 1 antagonists as anti-hypertension drugs.

    PubMed

    Bao, Xiaolu; Zhu, Weibo; Zhang, Ruijing; Wen, Caihong; Wang, Li; Yan, Yijia; Tang, Hesheng; Chen, Zhilong

    2016-05-01

    Three new angiotensin II receptor 1 antagonists, 1, 2 and 3 were designed, synthesized and evaluated. The AT1 receptor-binding assays in vitro showed that all the synthesized compounds had nanomolar affinity for the AT1 receptor. From which compound 3 was found to be the most potent ligands with an IC50 value of 2.67±0.23 nM. Biological evaluation in vivo revealed that all the compounds could cause significant decrease on MBP in a dose dependent manner in spontaneously hypertensive rats, and compound 3 especially showed an efficient and long-lasting effect in reducing blood pressure, whose maximal response lowered 41 mmHg of MBP at 10mg/kg and 62 mmHg at 15 mg/kg after oral administration, the significant anti-hypertensive effect lasted beyond 12 h, which is better than the reference compound losartan. The pharmacokinetic experiments showed that compound 3 could be absorbed efficiently and metabolized smoothly both in blood and in tissues in Wistar rats. The acute toxicity assay suggested that it has low toxicity with the LD50 value of 2974.35 mg/kg. These results demonstrate that compound 3 is a potent angiotensin AT1 receptor antagonist which could be considered as a novel anti-hypertension candidate and deserved for further investigation.

  7. Discovery and characterization of novel small-molecule CXCR4 receptor agonists and antagonists

    PubMed Central

    Mishra, Rama K.; Shum, Andrew K.; Platanias, Leonidas C.; Miller, Richard J.; Schiltz, Gary E.

    2016-01-01

    The chemokine CXCL12 (SDF-1) and its cognate receptor CXCR4 are involved in a large number of physiological processes including HIV-1 infectivity, inflammation, tumorigenesis, stem cell migration, and autoimmune diseases. While previous efforts have identified a number of CXCR4 antagonists, there have been no small molecule agonists reported. Herein, we describe the identification of a novel series of CXCR4 modulators, including the first small molecules to display agonist behavior against this receptor, using a combination of structure- and ligand-based virtual screening. These agonists produce robust calcium mobilization in human melanoma cell lines which can be blocked by the CXCR4-selective antagonist AMD3100. We also demonstrate the ability of these new agonists to induce receptor internalization, ERK activation, and chemotaxis, all hallmarks of CXCR4 activation. Our results describe a new series of biologically relevant small molecules that will enable further study of the CXCR4 receptor and may contribute to the development of new therapeutics. PMID:27456816

  8. Estrogen receptor (ER) agonists and androgen receptor (AR) antagonists in effluents from Norwegian North Sea oil production platforms.

    PubMed

    Tollefsen, Knut-Erik; Harman, Christopher; Smith, Andy; Thomas, Kevin V

    2007-03-01

    The in vitro estrogen receptor (ER) agonist and androgen receptor (AR) antagonist potencies of offshore produced water effluents collected from the Norwegian Sector were determined using recombinant yeast estrogen and androgen screens. Solid phase extraction (SPE) concentrates of the effluents showed E2 agonist activities similar to those previously reported for the United Kingdom (UK) Continental Shelf (<0.1-4 ng E2 L(-1)). No activity was detected in the filtered oil droplets suggesting that produced water ER activity is primarily associated with the dissolved phase. Targeted analysis for methyl- to nonyl-substituted alkylphenol isomers show the occurrence of known ER agonists in the analysed samples. For the first time, AR antagonists were detected in both the dissolved and oil associated phase at concentrations of between 20 and 8000 microg of flutamide equivalents L(-1). The identity of the AR antagonists is unknown, however this represents a significant input into the marine environment of unknown compounds that exert a known biological effect. It is recommended that further analysis using techniques such as bioassay-directed analysis is performed to identify the compounds/groups of compounds that are responsible in order to improve the assessment of the risk posed by produced water discharges to the marine environment.

  9. Natural variants of cytotoxic epitopes are T-cell receptor antagonists for antiviral cytotoxic T cells

    NASA Astrophysics Data System (ADS)

    Bertoletti, Antonio; Sette, Alessandro; Chisari, Francis V.; Penna, Amalia; Levrero, Massimo; Carli, Marco De; Fiaccadori, Franco; Ferrari, Carlo

    1994-06-01

    IT has been suggested that mutations within immunodominant cytotoxic T-lymphocyte (CTL) epitopes may be exploited by viruses to evade protective immune responses critical for clearance1-4. Viral escape could originate from passive mechanisms, such as mutations within crucial CTL epitopes, either affecting major histocompatibility complex binding or T-cell antigen receptor (TCR) recognition. Additionally, it has recently been shown that substitutions of TCR contact sites can yield analogue peptides that can still interact with the T-cell receptor but be unable to deliver a full stimulatory signal, thus inducing anergy5 or acting as an antagonist for the TCR6-8. We report here that hepatitis B virus isolates derived from two chronically infected patients display variant epitopes that act as natural TCR antagonists with the capacity to inhibit the CTL response to the wild-type epitope. During natural infection, TCR antagonist mutations of CTL epitopes could contribute to the development of viral persistence, especially if the antiviral CTL response is monospecific or the epitope is strongly immunodominant.

  10. Novel Toll-like receptor-4 antagonist (+)-naloxone protects mice from inflammation-induced preterm birth

    PubMed Central

    Chin, Peck Yin; Dorian, Camilla L.; Hutchinson, Mark R.; Olson, David M.; Rice, Kenner C.; Moldenhauer, Lachlan M.; Robertson, Sarah A.

    2016-01-01

    Toll-like receptor 4 (TLR4) activation by bacterial infection, or by sterile inflammatory insult is a primary trigger of spontaneous preterm birth. Here we utilize mouse models to investigate the efficacy of a novel small molecule TLR4 antagonist, (+)-naloxone, the non-opioid isomer of the opioid receptor antagonist (−)-naloxone, in infection-associated preterm birth. Treatment with (+)-naloxone prevented preterm delivery and alleviated fetal demise in utero elicited by i.p. LPS administration in late gestation. A similar effect with protection from preterm birth and perinatal death, and partial correction of reduced birth weight and postnatal mortality, was conferred by (+)-naloxone administration after intrauterine administration of heat-killed E. coli. Local induction by E. coli of inflammatory cytokine genes Il1b, Il6, Tnf and Il10 in fetal membranes was suppressed by (+)-naloxone, and cytokine expression in the placenta, and uterine myometrium and decidua, was also attenuated. These data demonstrate that inhibition of TLR4 signaling with the novel TLR4 antagonist (+)-naloxone can suppress the inflammatory cascade of preterm parturition, to prevent preterm birth and perinatal death. Further studies are warranted to investigate the utility of small molecule inhibition of TLR-driven inflammation as a component of strategies for fetal protection and delaying preterm birth in the clinical setting. PMID:27819333

  11. Synthesis and pharmacological evaluation of indolinone derivatives as novel ghrelin receptor antagonists.

    PubMed

    Puleo, Letizia; Marini, Pietro; Avallone, Roberta; Zanchet, Marco; Bandiera, Silvio; Baroni, Marco; Croci, Tiziano

    2012-09-15

    The ghrelin receptor is a G-protein-coupled receptor (GPCR) widely expressed in the brain, stomach and the intestine. It was firstly identified during studies aimed to find synthetic modulators of growth hormone (GH) secretion. GHSR and its endogenous ligand ghrelin were found to be involved in hunger response. Through food intake regulation, they could affect body weight and adiposity. Thus GHSR antagonists rapidly became an attractive target to treat obesity and feeding disorders. In this study we describe the biological properties of new indolinone derivatives identified as a new, chiral class of ghrelin antagonists. Their synthesis as well as the structure-activity relationship will be discussed herein. The in vitro identified compound 14f was a potent GHSR1a antagonist (IC(50) = 7 nM). When tested in vivo, on gastric emptying model, 14f showed an inhibitory intrinsic effect when given alone and it dose dependently inhibited ghrelin stimulation. Compound 14f also reduced food intake stimulated both by fasting condition (high level of endogenous ghrelin) and by icv ghrelin. Moreover this compound improved glucose tolerance in ipGTT test.

  12. Estrogen receptor-β in the paraventricular nucleus and rostroventrolateral medulla plays an essential protective role in aldosterone/salt-induced hypertension in female rats.

    PubMed

    Xue, Baojian; Zhang, Zhongming; Beltz, Terry G; Johnson, Ralph F; Guo, Fang; Hay, Meredith; Johnson, Alan Kim

    2013-06-01

    The identification of the specific estrogen receptor (ER) subtypes that are involved in estrogen protection from hypertension and their specific locations in the central nervous system is critical to our understanding and design of effective estrogen replacement therapies in women. Using selective ER agonists and recombinant adeno-associated virus (AAV) carrying small interference (si) RNA to silence either ERα (AAV-siRNA-ERα) or ERβ (AAV-siRNA-ERβ), the present study investigated regional specificity of different ER subtypes in the protective actions of estrogen in aldosterone (Aldo)-induced hypertension. Intracerebroventricular infusions of either diarylpropionitrile, a selective ERβ agonist, or propyl-pyrazole-triol, a selective ERα agonist, attenuated Aldo/NaCl-induced hypertension in ovariectomized rats. In contrast, intracerebroventricular injections of siRNA-ERα or siRNA-ERβ augmented Aldo-induced hypertension in intact females. Site-specific paraventricular nucleus (PVN) or rostroventrolateral medulla (RVLM) injections of siRNA-ERβ augmented Aldo-induced hypertension. However, rats with PVN or RVLM injections of siRNA-ERα did not significantly increase blood pressure induced by Aldo. Real-time polymerase chain reaction analyses of the PVN and RVLM of siRNA-injected rat confirmed a marked reduction in the expression of ERα and ERβ. In cultured PVN neurons, silencing either ERα or ERβ by culturing PVN neurons with siRNA-ERα or siRNA-ERβ enhanced Aldo-induced reactive oxygen species production. Ganglionic blockade after Aldo infusion showed an increase in sympathetic activity in ERβ knockdown rats. These results indicate that both PVN and RVLM ERβ, but not ERα in these nuclei, contribute to the protective effects of estrogen against Aldo-induced hypertension. The brain regions responsible for the protective effects of estrogen interaction with ERα in Aldo-induced hypertension still need to be determined.

  13. Piperazine-2,3-dicarboxylic acid Derivatives as Dual Antagonists of NMDA and GluK1-Containing Kainate Receptors

    PubMed Central

    Irvine, Mark W.; Costa, Blaise M.; Dlaboga, Daniel; Culley, Georgia; Hulse, Richard; Scholefield, Caroline L.; Atlason, Palmi; Fang, Guangyu; Eaves, Richard; Morley, Richard; Mayo-Martin, Maria B.; Amici, Mascia; Bortolotto, Zuner A.; Donaldson, Lucy; Collingridge, Graham L.; Molnár, Elek; Monaghan, Daniel T.; Jane, David E.

    2011-01-01

    Competitive N-methyl-D-aspartate receptor (NMDAR) antagonists bind to the GluN2 subunit, of which there are four types (GluN2A-D). We report that some N1-substituted derivatives of cis-piperazine-2,3-dicarboxylic acid display improved relative affinity for GluN2C and GluN2D versus GluN2A and GluN2B. These derivatives also display subtype-selectivity among the more distantly related kainate receptor family. Compounds 18i and (−)-4 were the most potent kainate receptor antagonists and 18i was selective for GluK1 versus GluK2, GluK3 and AMPA receptors. Modeling studies revealed structural features required for activity at GluK1 subunits and suggested that S674 was vital for antagonist activity. Consistent with this hypothesis, replacing the equivalent residue in GluK3 (alanine) with a serine imparts 18i antagonist activity. Antagonists with dual GluN2D and GluK1 antagonist activity may have beneficial effects in various neurological disorders. Consistent with this idea, antagonist 18i (30 mg/Kg i.p.) showed antinociceptive effects in an animal model of mild nerve injury. PMID:22111545

  14. Effects of ionotropic glutamate receptor antagonists on rat dural artery diameter in an intravital microscopy model

    PubMed Central

    Chan, KY; Gupta, S; de Vries, R; Danser, AHJ; Villalón, CM; Muñoz-Islas, E; Maassen Van Den Brink, A

    2010-01-01

    Background and purpose: During migraine, trigeminal nerves may release calcitonin gene-related peptide (CGRP), inducing cranial vasodilatation and central nociception; hence, trigeminal inhibition or blockade of craniovascular CGRP receptors may prevent this vasodilatation and abort migraine headache. Several preclinical studies have shown that glutamate receptor antagonists affect the pathophysiology of migraine. This study investigated whether antagonists of NMDA (ketamine and MK801), AMPA (GYKI52466) and kainate (LY466195) glutamate receptors affected dural vasodilatation induced by α-CGRP, capsaicin and periarterial electrical stimulation in rats, using intravital microscopy. Experimental approach: Male Sprague-Dawley rats were anaesthetized and the overlying bone was thinned to visualize the dural artery. Then, vasodilator responses to exogenous (i.v. α-CGRP) and endogenous (released by i.v. capsaicin and periarterial electrical stimulation) CGRP were elicited in the absence or presence of the above antagonists. Key results: α-CGRP, capsaicin and periarterial electrical stimulation increased dural artery diameter. Ketamine and MK801 inhibited the vasodilator responses to capsaicin and electrical stimulation, while only ketamine attenuated those to α-CGRP. In contrast, GYKI52466 only attenuated the vasodilatation to exogenous α-CGRP, while LY466195 did not affect the vasodilator responses to endogenous or exogenous CGRP. Conclusions and implications: Although GYKI52466 has not been tested clinically, our data suggest that it would not inhibit migraine via vascular mechanisms. Similarly, the antimigraine efficacy of LY466195 seems unrelated to vascular CGRP-mediated pathways and/or receptors. In contrast, the cranial vascular effects of ketamine and MK801 may represent a therapeutic mechanism, although the same mechanism might contribute, peripherally, to cardiovascular side effects. PMID:20590623

  15. Selective 5HT2A and 5HT6 Receptor Antagonists Promote Sleep in Rats

    PubMed Central

    Morairty, Stephen R.; Hedley, Linda; Flores, Judith; Martin, Renee; Kilduff, Thomas S.

    2008-01-01

    Study Objectives: Serotonin (5-HT) has long been implicated in the control of sleep and wakefulness. This study evaluated the hypnotic efficacy of the 5-HT6 antagonist RO4368554 (RO) and the 5-HT2A receptor antagonist MDL100907 (MDL) relative to zolpidem. Design: A randomized, repeated-measures design was utilized in which Wistar rats received intraperitoneal injections of RO (1.0, 3.0, and 10 mg/kg), MDL (0.1, 1.0 and 3.0 mg/kg), zolpidem (10 mg/kg), or vehicle in the middle of the dark (active) period. Electroencephalogram, electromyogram, body temperature (Tb) and locomotor activity were analyzed for 6 hours after injection. Measurements and Results: RO, MDL, and zolpidem all produced significant increases in sleep and decreases in waking, compared with vehicle control. All 3 doses of MDL produced more consolidated sleep, increased non-rapid eye movement sleep (NREM) sleep, and increased electroencephalographic delta power during NREM sleep. The highest dose of RO (10.0 mg/kg) produced significant increases in sleep and decreases in waking during hour 2 following dosing. These increases in sleep duration were associated with greater delta power during NREM sleep. ZO Zolpidem induced sleep with the shortest latency and significantly increased NREM sleep and delta power but also suppressed rapid eye movement sleep sleep; in contrast, neither RO nor MDL affected rapid eye movement sleep. Whereas RO did not affect Tb, both zolpidem and MDL reduced Tb relative to vehicle-injected controls. Conclusions: These results support a role for 5-HT2A receptor modulation in NREM sleep and suggest a previously unrecognized role for 5-HT6 receptors in sleep-wake regulation. Citation: Morairty SR; Hedley L; Flores J; Martin R; Kilduff TS. Selective 5HT2A and 5HT6 receptor antagonists promote sleep in rats. SLEEP 2008;31(1):34-44. PMID:18220076

  16. Dopamine Receptor Antagonists Enhance Proliferation and Neurogenesis of Midbrain Lmx1a-expressing Progenitors.

    PubMed

    Hedlund, Eva; Belnoue, Laure; Theofilopoulos, Spyridon; Salto, Carmen; Bye, Chris; Parish, Clare; Deng, Qiaolin; Kadkhodaei, Banafsheh; Ericson, Johan; Arenas, Ernest; Perlmann, Thomas; Simon, András

    2016-06-01

    Degeneration of dopamine neurons in the midbrain causes symptoms of the movement disorder, Parkinson disease. Dopamine neurons are generated from proliferating progenitor cells localized in the embryonic ventral midbrain. However, it remains unclear for how long cells with dopamine progenitor character are retained and if there is any potential for reactivation of such cells after cessation of normal dopamine neurogenesis. We show here that cells expressing Lmx1a and other progenitor markers remain in the midbrain aqueductal zone beyond the major dopamine neurogenic period. These cells express dopamine receptors, are located in regions heavily innervated by midbrain dopamine fibres and their proliferation can be stimulated by antagonizing dopamine receptors, ultimately leading to increased neurogenesis in vivo. Furthermore, treatment with dopamine receptor antagonists enhances neurogenesis in vitro, both from embryonic midbrain progenitors as well as from embryonic stem cells. Altogether our results indicate a potential for reactivation of resident midbrain cells with dopamine progenitor potential beyond the normal period of dopamine neurogenesis.

  17. Epigenetic regulation of antagonistic receptors confers rice blast resistance with yield balance.

    PubMed

    Deng, Yiwen; Zhai, Keran; Xie, Zhen; Yang, Dongyong; Zhu, Xudong; Liu, Junzhong; Wang, Xin; Qin, Peng; Yang, Yuanzhu; Zhang, Guomin; Li, Qun; Zhang, Jianfu; Wu, Shuangqing; Milazzo, Joëlle; Mao, Bizeng; Wang, Ertao; Xie, Huaan; Tharreau, Didier; He, Zuhua

    2017-03-03

    Crop breeding aims to balance disease resistance with yield; however, single resistance (R) genes can lead to resistance breakdown, and R gene pyramiding may affect growth fitness. Here we report that the rice Pigm locus contains a cluster of genes encoding nucleotide-binding leucine-rich repeat (NLR) receptors that confer durable resistance to the fungus Magnaporthe oryzae without yield penalty. Among these NLR receptors, PigmR confers broad-spectrum resistance, whereas PigmS competitively attenuates PigmR homodimerization to suppress resistance. PigmS expression, and thus PigmR-mediated resistance, are subjected to tight epigenetic regulation. PigmS increases seed production to counteract the yield cost induced by PigmR Therefore, our study reveals a mechanism balancing high disease resistance and yield through epigenetic regulation of paired antagonistic NLR receptors, providing a tool to develop elite crop varieties.

  18. Modification of Anxious Behavior after Psychogenic Trauma and Treatment with Galanin Receptor Antagonist.

    PubMed

    Lyudyno, V I; Tsikunov, S G; Abdurasulova, I N; Kusov, A G; Klimenko, V M

    2015-07-01

    Effects of blockage of central galanin receptors on anxiety manifestations were studied in rats with psychogenic trauma. Psychogenic trauma was modeled by exposure of a group of rats to the situation when the partner was killed by a predator. Antagonist of galanin receptors was intranasally administered before stress exposure. Animal behavior was evaluated using the elevated-plus maze test, free exploratory paradigm, and open-field test. Psychogenic trauma was followed by an increase in anxiety level and appearance of agitated behavior. Blockage of galanin receptors aggravated behavioral impairment, which manifested in the pathological anxious reactions - manifestations of hypervigilance and hyperawareness. The results suggest that endogenous pool of galanin is involved into prevention of excessive CNS response to stressful stimuli typical of posttraumatic stress disorder.

  19. An opioid receptor antagonist, naltrexone, does not alter taste and smell responses in humans.

    PubMed

    Scińska, A; Koroś, E; Polanowska, E; Kukwa, A; Bogucka-Bonikowska, A; Kostowski, W; Habrat, B; Bieńkowski, P

    2000-01-01

    Several studies have shown that an opioid receptor antagonist, naltrexone, decreases palatable food consumption. Naltrexone has also been reported to reduce ethanol intake in alcohol-preferring rodents and human alcoholics. The aim of the present study was to assess the effects of naltrexone on taste and smell responses in healthy male volunteers. Naltrexone did not alter intensity and pleasantness of sucrose, quinine, citric acid, sodium chloride, and ethanol taste. Similarly, ratings of olfactory stimuli (orange extract and ethanol) and Coca-Cola flavor were not influenced by the opioid antagonist. Our findings may indicate that: (i) naltrexone exerts marginal, if any, effects on gustatory and olfactory responses in humans; (ii) the drug does not alter orosensory responses to ethanol.

  20. Metabolism-guided design of short-acting calcium-sensing receptor antagonists.

    PubMed

    Southers, James A; Bauman, Jonathan N; Price, David A; Humphries, Paul S; Balan, Gayatri; Sagal, John F; Maurer, Tristan S; Zhang, Yan; Oliver, Robert; Herr, Michael; Healy, David R; Li, Mei; Kapinos, Brendon; Fate, Gwendolyn D; Riccardi, Keith A; Paralkar, Vishwas M; Brown, Thomas A; Kalgutkar, Amit S

    2010-08-12

    As part of a strategy to deliver short-acting calcium-sensing receptor (CaSR) antagonists, the metabolically labile thiomethyl functionality was incorporated into the zwitterionic amino alcohol derivative 3 with the hope of increasing human clearance through oxidative metabolism, while delivering a pharmacologically inactive sulfoxide metabolite. The effort led to the identification of thioanisoles 22 and 23 as potent and orally active CaSR antagonists with a rapid onset of action and short pharmacokinetic half-lives, which led to a rapid and transient stimulation of parathyroid hormone in a dose-dependent fashion following oral administration to rats. On the basis of the balance between target pharmacology, safety, and human disposition profiles, 22 and 23 were advanced as clinical candidates for the treatment of osteoporosis.

  1. G protein antagonists. A novel hydrophobic peptide competes with receptor for G protein binding.

    PubMed

    Mukai, H; Munekata, E; Higashijima, T

    1992-08-15

    A substance P (SP) analog, [D-Pro4,D-Trp7,9,10] SP4-11, is known to inhibit the actions of various structurally unrelated messenger molecules as well as SP. Our studies on the effects of this peptide on the regulation of purified G proteins by receptor showed that at least some of the biological effects of the peptide can be explained by the ability of the peptide to block the activation of G proteins by receptors. Here we report that a novel truncated SP-related peptide, pGlu-Gln-D-Trp-Phe-D-Trp-D-Trp-Met-NH2, inhibited the activation of G(i) or G(o) by M2 muscarinic cholinergic receptor (M2 mAChR) or of Gs by beta-adrenergic receptor in the reconstituted phospholipid vesicles, assayed by receptor-promoted GTP hydrolysis. The inhibition by the peptide was apparently reversible and competitive with respect to receptor binding to G proteins; the inhibition could be overcome by increasing the concentration of receptor in the vesicles and was not altered by changes in the concentration of G protein. The competing effects of the peptide were used to analyze the effect of agonist on receptor-G protein interaction. The concentration change of muscarinic agonist did not alter the inhibitory effects of the peptide on M2 mAChR-promoted GTPase by G(o), which is consistent with the idea that agonist increases the regulatory efficiency of the receptor but does not alter its affinity for G proteins. This new group of compounds (G protein antagonists) is a promising tool to study receptor-G protein interaction quantitatively.

  2. Pharmacological profile of valsartan: a potent, orally active, nonpeptide antagonist of the angiotensin II AT1-receptor subtype.

    PubMed Central

    Criscione, L.; de Gasparo, M.; Bühlmayer, P.; Whitebread, S.; Ramjoué, H. P.; Wood, J.

    1993-01-01

    1. The pharmacological profile of valsartan, (S)-N-valeryl-N-([2'-(1H-tetrazol-5-yl)biphenyl-4-yl]-methyl)-vali ne, a potent, highly selective, and orally active antagonist at the angiotensin II (AII) AT1-receptor, was studied in vitro and in vivo. 2. Valsartan competed with [125I]-AII at its specific binding sites in rat aortic smooth muscle cell membranes (AT1-receptor subtype) with a Ki of 2.38 nM, but was about 30,000 times less active in human myometrial membranes (AT2-receptor subtype). 3. In rabbit aortic rings incubated for 5 min with valsartan, at concentrations of 2, 20 and 200 nM, the concentration-response curve of AII was displaced to the right and the maximum response was reduced by 33%, 36% and 40%, respectively. Prolongation of the incubation time with valsartan to 1 h or 3 h, further reduced the maximum response by 48% or 59% (after 20 nM) and by 59% or 60% (after 200 nM) respectively. After 3 h incubation an apparent pKb value of 9.26 was calculated. Contractions induced by noradrenaline, 5-hydroxytryptamine, or potassium chloride were not affected by valsartan. No agonistic effects were observed in the rabbit aorta at concentrations of valsartan up to 2 microM. 4. In bovine adrenal glomerulosa, valsartan inhibited AII-stimulated aldosterone release without affecting the maximum response (pA2 8.4). 5. In the pithed rat, oral administration of valsartan (10 mg kg-1) shifted the AII-induced pressor response curves to the right, without affecting responses induced by the electrical stimulation of the sympathetic outflow or by noradrenaline. Animals treated with valsartan 24 h before pithing also showed significant inhibition of the response to AII. 6. In conscious, two-kidney, one-clip renal hypertensive rats (2K1C), valsartan decreased blood pressure in a dose-dependent manner after single i.v. or oral administration. The respective ED30 values were 0.06 mg kg-1 (i.v.) and 1.4 mg kg-1 (p.o.). The antihypertensive effect lasted for at least 24 h

  3. Arginine Vasopressin V1a Receptor Antagonist Impairs Maternal Memory in Rats

    PubMed Central

    Nephew, Benjamin C.; Bridges, Robert S.

    2008-01-01

    Primiparous female rats rapidly respond to foster pups following an extended separation from pups after an initial maternal experience. This consolidation of maternal behavior has been referred to as maternal memory. The neurochemical regulation of maternal memory is not clearly understood. One neuropeptide that may mediate maternal memory is arginine vasopressin (AVP), a neuropeptide which is modulated around the time of parturition and has an established role in learning and memory processes. Thus, the present studies examine the possible involvement of AVP in the establishment of maternal memory in female rats. Pregnant rats were implanted with chronic cannulae connected to subcutaneous osmotic minipumps filled with a V1a receptor antagonist [d(CH2)5Tyr(Me)AVP, 0.1–12.5 ng/hr] or saline vehicle which were chronically infused either into the lateral ventricles or bilaterally into the medial amygdala beginning on day 18 of gestation. Both the osmotic pumps and the newborn pups were removed 24 hours following parturition. The effects of the V1a antagonist treatments on social recognition and maternal behavior were measured following parturition and maternal memory was assessed following a ten day separation from pups. Whereas none of the AVP treatments affected the initial establishment of maternal behavior postpartum, maternal memory was impaired in rats infused into the amygdala with the AVP antagonist (1.25 and 12.5 ng/hr). Social recognition was not impaired by intracerebroventricular infusion of either the 0.1 or 1.0 ng/hr dose of the V1a antagonist. The present results suggest a role for medial amygdaloid V1a receptors in the establishment of maternal memory. PMID:18620713

  4. Predicting the relative binding affinity of mineralocorticoid receptor antagonists by density functional methods

    NASA Astrophysics Data System (ADS)

    Roos, Katarina; Hogner, Anders; Ogg, Derek; Packer, Martin J.; Hansson, Eva; Granberg, Kenneth L.; Evertsson, Emma; Nordqvist, Anneli

    2015-12-01

    In drug discovery, prediction of binding affinity ahead of synthesis to aid compound prioritization is still hampered by the low throughput of the more accurate methods and the lack of general pertinence of one method that fits all systems. Here we show the applicability of a method based on density functional theory using core fragments and a protein model with only the first shell residues surrounding the core, to predict relative binding affinity of a matched series of mineralocorticoid receptor (MR) antagonists. Antagonists of MR are used for treatment of chronic heart failure and hypertension. Marketed MR antagonists, spironolactone and eplerenone, are also believed to be highly efficacious in treatment of chronic kidney disease in diabetes patients, but is contra-indicated due to the increased risk for hyperkalemia. These findings and a significant unmet medical need among patients with chronic kidney disease continues to stimulate efforts in the discovery of new MR antagonist with maintained efficacy but low or no risk for hyperkalemia. Applied on a matched series of MR antagonists the quantum mechanical based method gave an R2 = 0.76 for the experimental lipophilic ligand efficiency versus relative predicted binding affinity calculated with the M06-2X functional in gas phase and an R2 = 0.64 for experimental binding affinity versus relative predicted binding affinity calculated with the M06-2X functional including an implicit solvation model. The quantum mechanical approach using core fragments was compared to free energy perturbation calculations using the full sized compound structures.

  5. Aldosterone Activates NF-κB in the Collecting Duct

    PubMed Central

    Leroy, Valérie; De Seigneux, Sophie; Agassiz, Victor; Hasler, Udo; Rafestin-Oblin, Marie-Edith; Vinciguerra, Manlio; Martin, Pierre-Yves; Féraille, Eric

    2009-01-01

    Besides its classical effects on salt homeostasis in renal epithelial cells, aldosterone promotes inflammation and fibrosis and modulates cell proliferation. The proinflammatory transcription factor NF-κB has been implicated in cell proliferation, apoptosis, and regulation of transepithelial sodium transport. The effect of aldosterone on the NF-κB pathway in principal cells of the cortical collecting duct, a major physiologic target of aldosterone, is unknown. Here, in both cultured cells and freshly isolated rat cortical collecting duct, aldosterone activated the canonical NF-κB signaling pathway, leading to increased expression of several NF-κB–targeted genes (IκBα, plasminogen activator inhibitor 1, monocyte chemoattractant protein 1, IL-1β, and IL-6). Small interfering RNA–mediated knockdown of the serum and glucocorticoid-inducible kinase SGK1, a gene induced early in the response to aldosterone, but not pharmacologic inhibition of extracellular signal–regulated kinase and p38 kinase, attenuated aldosterone-induced NF-κB activation. Pharmacologic antagonism or knockdown of the mineralocorticoid receptor prevented aldosterone-induced NF-κB activity. In addition, activation of the glucocorticoid receptor inhibited the transactivation of NF-κB by aldosterone. In agreement with these in vitro findings, spironolactone prevented NF-κB–induced transcriptional activation observed in cortical collecting ducts of salt-restricted rats. In summary, aldosterone activates the canonical NF-κB pathway in principal cells of the cortical collecting duct by activating the mineralocorticoid receptor and by inducing SGK1. PMID:18987305

  6. Decavanadate, a P2X receptor antagonist, and its use to study ligand interactions with P2X7 receptors.

    PubMed

    Michel, Anton D; Xing, Mengle; Thompson, Kyla M; Jones, Clare A; Humphrey, Patrick P A

    2006-03-18

    In this study we have studied decavanadate effects at P2X receptors. Decavanadate competitively blocked 2'- and 3'-O-(4benzoylbenzoyl) ATP (BzATP) stimulated ethidium accumulation in HEK293 cells expressing human recombinant P2X7 receptors (pK(B) 7.5). The effects of decavanadate were rapid (minutes) in both onset and offset and contrasted with the much slower kinetics of pyridoxal 5-phosphate (P5P), Coomassie brilliant blue (CBB) and 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN62). Decavanadate competitively blocked the slowly reversible, or irreversible, blockade of the P2X7 receptor produced by P5P and oxidised ATP suggesting competition for a common binding site. However, the interaction between decavanadate and KN62 was non-competitive. Decavanadate also blocked P2X2 and P2X4 receptors but with slightly lower potency. These data demonstrate that decavanadate is the first reversible and competitive antagonist of the P2X7 receptor and is a useful tool for studying the mechanism of interaction of ligands with the P2X7 receptor.

  7. The effects of sigma (σ1) receptor-selective ligands on muscarinic receptor antagonist-induced cognitive deficits in mice

    PubMed Central

    Malik, Maninder; Rangel-Barajas, Claudia; Sumien, Nathalie; Su, Chang; Singh, Meharvan; Chen, Zhenglan; Huang, Ren-Qi; Meunier, Johann; Maurice, Tangui; Mach, Robert H; Luedtke, Robert R

    2015-01-01

    Background and Purpose Cognitive deficits in patients with Alzheimer's disease, Parkinson's disease, traumatic brain injury and stroke often involve alterations in cholinergic signalling. Currently available therapeutic drugs provide only symptomatic relief. Therefore, novel therapeutic strategies are needed to retard and/or arrest the progressive loss of memory. Experimental Approach Scopolamine-induced memory impairment provides a rapid and reversible phenotypic screening paradigm for cognition enhancement drug discovery. Male C57BL/6J mice given scopolamine (1 mg·kg−1) were used to evaluate the ability of LS-1–137, a novel sigma (σ1) receptor-selective agonist, to improve the cognitive deficits associated with muscarinic antagonist administration. Key Results LS-1–137 is a high-affinity (Ki = 3.2 nM) σ1 receptor agonist that is 80-fold selective for σ1, compared with σ2 receptors. LS-1–137 binds with low affinity at D2-like (D2, D3 and D4) dopamine and muscarinic receptors. LS-1–137 was found to partially reverse the learning deficits associated with scopolamine administration using a water maze test and an active avoidance task. LS-1–137 treatment was also found to trigger the release of brain-derived neurotrophic factor from rat astrocytes. Conclusions and Implications The σ1 receptor-selective compound LS-1–137 may represent a novel candidate cognitive enhancer for the treatment of muscarinic receptor-dependent cognitive deficits. PMID:25573298

  8. Identification of ghrelin receptor blocker, D-[Lys3] GHRP-6 as a CXCR4 receptor antagonist.

    PubMed

    Patel, Kalpesh; Dixit, Vishwa Deep; Lee, Jun Ho; Kim, Jie Wan; Schaffer, Eric M; Nguyen, Dzung; Taub, Dennis D

    2012-01-01

    [D-Lys3]-Growth Hormone Releasing Peptide-6 (DLS) is widely utilized in vivo and in vitro as a selective ghrelin receptor (GHS-R) antagonist. Unexpectedly, we identified that DLS also has the ability to block CXCL12 binding and activity through CXCR4 on T cells and peripheral blood mononuclear cells (PBMCs). Moreover, as CXCR4 has been shown to act as a major co-receptor for HIV-1 entry into CD4 positive host cells, we have also found that DLS partially blocks CXCR4-mediated HIV-1 entry and propagation in activated human PBMCs. These data demonstrate that DLS is not the specific and selective antagonist as thought for GHS-R1a and appears to have additional effects on the CXCR4 chemokine receptor. Our findings also suggest that structural analogues that mimic DLS binding properties may also have properties of blocking HIV infectivity, CXCR4 dependent cancer cell migration and attenuating chemokine-mediated immune cell trafficking in inflammatory disorders.

  9. Synthesis and biological evaluation of bradykinin B(1)/B(2) and selective B(1) receptor antagonists.

    PubMed

    Amblard, M; Bedos, P; Olivier, C; Daffix, I; Luccarini, J M; Dodey, P; Pruneau, D; Paquet, J L; Martinez, J

    2000-06-15

    We recently described a potent bradykinin B(2) receptor agonist (JMV1116) obtained by replacing the D-Tic-Oic dipeptide moiety of HOE140 by a (3S)-amino-5-(carbonylmethyl)-2,3-dihydro-1, 5-benzothiazepin-4(5H)-one (D-BT) moiety. This compound inhibited the specific binding of [(3)H]BK on membranes of CHO cells expressing the human cloned B(2) receptor with nanomolar affinity and contracted both isolated rat uterus and human umbilical vein. These data demonstrated that D-BT could be a good mimic of the Pro-Phe dipeptide. In the present study we characterized B(1) receptor antagonists containing the D-BT moiety. We prepared an analogue of compound JMV1116 deleting the C-terminal arginine residue. The resulting compound (1) had an affinity of 83 nM for the human cloned B(1) receptor. The most remarkable property of 1 is its ability to bind also the B(2) receptor with an affinity of 4.4 nM despite the absence of the C-terminal arginine residue. Modifications at the N-terminal part of 1 associated with the substitution of the thienylalanine residue by alpha-(2-indanyl)glycine resulted in analogues selectively binding to the B(1) receptor with an affinity in the picomolar range.

  10. Discovery of novel protease activated receptors 1 antagonists with potent antithrombotic activity in vivo.

    PubMed

    Perez, Michel; Lamothe, Marie; Maraval, Catherine; Mirabel, Etienne; Loubat, Chantal; Planty, Bruno; Horn, Clemens; Michaux, Julien; Marrot, Sebastien; Letienne, Robert; Pignier, Christophe; Bocquet, Arnaud; Nadal-Wollbold, Florence; Cussac, Didier; de Vries, Luc; Le Grand, Bruno

    2009-10-08

    Protease activated receptors (PARs) or thrombin receptors constitute a class of G-protein-coupled receptors (GPCRs) implicated in the activation of many physiological mechanisms. Thus, thrombin activates many cell types such as vascular smooth muscle cells, leukocytes, endothelial cells, and platelets via activation of these receptors. In humans, thrombin-induced platelet aggregation is mediated by one subtype of these receptors, termed PAR1. This article describes the discovery of new antagonists of these receptors and more specifically two compounds: 2-[5-oxo-5-(4-pyridin-2-ylpiperazin-1-yl)penta-1,3-dienyl]benzonitrile 36 (F 16618) and 3-(2-chlorophenyl)-1-[4-(4-fluorobenzyl)piperazin-1-yl]propenone 39 (F 16357), obtained after optimization. Both compounds are able to inhibit SFLLR-induced human platelet aggregation and display antithrombotic activity in an arteriovenous shunt model in the rat after iv or oral administration. Furthermore, these compounds are devoid of bleeding side effects often observed with other types of antiplatelet drugs, which constitutes a promising advantage for this new class of antithrombotic agents.

  11. Endocannabinoid release from midbrain dopamine neurons: a potential substrate for cannabinoid receptor antagonist treatment of addiction.

    PubMed

    Lupica, Carl R; Riegel, Arthur C

    2005-06-01

    Substantial evidence suggests that all commonly abused drugs act upon the brain reward circuitry to ultimately increase extracellular concentrations of the neurotransmitter dopamine in the nucleus accumbens and other forebrain areas. Many drugs of abuse appear to increase dopamine levels by dramatically increase the firing and bursting rates of dopamine neurons located in the ventral mesencephalon. Recent clinical evidence in humans and behavioral evidence in animals indicate that cannabinoid receptor antagonists such as SR141716A (Rimonabant) can reduce the self-administration of, and craving for, several commonly addictive drugs. However, the mechanism of this potentially beneficial effect has not yet been identified. We propose, on the basis of recent studies in our laboratory and others, that these antagonists may act by blocking the effects of endogenously released cannabinoid molecules (endocannabinoids) that are released in an activity- and calcium-dependent manner from mesencephalic dopamine neurons. It is hypothesized that, through the antagonism of cannabinoid CB1 receptors located on inhibitory and excitatory axon terminals targeting the midbrain dopamine neurons, the effects of the endocannabinoids are occluded. The data from these studies therefore suggest that the endocannabinoid system and the CB1 receptors located in the ventral mesencephalon may play an important role in regulating drug reward processes, and that this substrate is recruited whenever dopamine neuron activity is increased.

  12. Effect of inhaled H1 and H2 receptor antagonist in normal and asthmatic subjects.

    PubMed Central

    Thomson, N C; Kerr, J W

    1980-01-01

    The effects on airflow resistance of an inhaled H1 receptor antagonist, clemastine, and an H2 receptor antagonist, cimetidine, have been investigated in normal and asthmatic subjects. No significant changes in specific conductance (sGaw) were seen in six normal subjects. In eight asthmatic subjects a significant increase in forced expiratory volume in one second (FEV1) occurred at 60 min (< 0.02), and 120 (< 0.05) after the inhalation of clemastine, whereas inhaled cimetidine had no effect on airflow resistance. Clemastine and cimetidine were tested on histamine-induced bronchoconstriction in eight normal and eight asthmatic subjects. Clemastine significantly reduced the fall in sGaw in normal subjects and the fall in FEV1 in asthmatic subjects, whereas cimetidine had no protective effect. Clemastine and ipratropium bromide were tested on methacholine-induced bronchoconstriction in eight normal subjects. Ipratropium bromide, but not clemastine, significantly reduced the fall in sGaw after methacholine. These results suggest that in normal and asthmatic subjects histamine-induced bronchoconstriction is mediated predominantly via H1 rather than H2 receptors in the airways. PMID:6449094

  13. Selective small molecule angiotensin II type 2 receptor antagonists for neuropathic pain: preclinical and clinical studies.

    PubMed

    Smith, Maree T; Anand, Praveen; Rice, Andrew S C

    2016-02-01

    Neuropathic pain affects up to 10% of the general population, but drug treatments recommended for the treatment of neuropathic pain are associated with modest efficacy and/or produce dose-limiting side effects. Hence, neuropathic pain is an unmet medical need. In the past 2 decades, research on the pathobiology of neuropathic pain has revealed many novel pain targets for use in analgesic drug discovery programs. However, these efforts have been largely unsuccessful as molecules that showed promising pain relief in rodent models of neuropathic pain generally failed to produce analgesia in early phase clinical trials in patients with neuropathic pain. One notable exception is the angiotensin II type 2 (AT2) receptor that has clinical validity on the basis of a successful double-blind, randomized, placebo-controlled, clinical trial of EMA401, a highly selective, orally active, peripherally restricted AT2 receptor antagonist in patients with postherpetic neuralgia. In this study, we review research to date on target validation, efficacy, and mode of action of small molecule AT2 receptor antagonists in rodent models of peripheral neuropathic pain and in cultured human sensory neurons, the preclinical pharmacokinetics of these compounds, and the outcome of the above clinical trial.

  14. Design, synthesis, and structure-activity relationships of acetylene-based histamine H3 receptor antagonists.

    PubMed

    Ali, S M; Tedford, C E; Gregory, R; Handley, M K; Yates, S L; Hirth, W W; Phillips, J G

    1999-03-11

    New, potent, and selective histamine H3 receptor antagonists have been synthesized by employing the use of (1) an appropriately positioned nonpolar acetylene spacer group, (2) either a two-carbon straight chain linker or a conformationally restricting trans-cyclopropane ring between the C-4 position of an imidazole headgroup and the acetylene spacer, and (3) a Topliss operational scheme for side-chain substitution for optimizing the hydrophobic domain. Compounds 9-18 are examples synthesized with the two-carbon straight chain linker, whereas 26-31 are analogues prepared by incorporation of the trans-(+/-)-cyclopropane at the C-4 position of an imidazole headgroup. Synthesis of both the (1R,2R)- and (1S, 2S)-cyclopropyl enantiomers of the most potent racemic compound 31 (Ki = 0.33 +/- 0.13 nM) demonstrated a stereopreference in H3 receptor binding affinity for the (1R,2R) enantiomer 32 (Ki = 0.18 +/- 0.04 nM) versus the (1S,2S) enantiomer 33 (Ki = 5.3 +/- 0.5 nM). (1R,2R)-4-(2-(5,5-Dimethylhex-1-ynyl)cyclopropyl)imidazole (32) is one of the most potent histamine H3 receptor antagonists reported to date.

  15. Salvianolic Acid A, as a Novel ETA Receptor Antagonist, Shows Inhibitory Effects on Tumor in Vitro.

    PubMed

    Zhang, Qiao; Wang, Shifeng; Yu, Yangyang; Sun, Shengnan; Zhang, Yuxin; Zhang, Yanling; Yang, Wei; Li, Shiyou; Qiao, Yanjiang

    2016-08-02

    Endothelin-1 (ET-1) autocrine and paracrine signaling modulate cell proliferation of tumor cells by activating its receptors, endothelin A receptor (ETAR) and endothelin B receptor (ETBR). Dysregulation of ETAR activation promotes tumor development and progression. The potential of ETAR antagonists and the dual-ETAR and ETBR antagonists as therapeutic approaches are under preclinical and clinical studies. Salvianolic acid A (Sal A) is a hydrophilic polyphenolic derivative isolated from Salvia miltiorrhiza Bunge (Danshen), which has been reported as an anti-cancer and cardio-protective herbal medicine. In this study, we demonstrate that Sal A inhibits ETAR activation induced by ET-1 in both recombinant and endogenous ETAR expression cell lines. The IC50 values were determined as 5.7 µM in the HEK293/ETAR cell line and 3.14 µM in HeLa cells, respectively. Furthermore, our results showed that Sal A suppressed cell proliferation and extended the doubling times of multiple cancer cells, including HeLa, DU145, H1975, and A549 cell lines. In addition, Sal A inhibited proliferation of DU145 cell lines stimulated by exogenous ET-1 treatment. Moreover, the cytotoxicity and cardio-toxicity of Sal A were assessed in human umbilical vein endothelial cells (HUVEC) and Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), which proved that Sal A demonstrates no cytotoxicity or cardiotoxicity. Collectively, our findings indicate that Sal A is a novel anti-cancer candidate through targeting ETAR.

  16. SKF-83566, a D1-dopamine receptor antagonist, inhibits the dopamine transporter.

    PubMed

    Stouffer, Melissa A; Ali, Solav; Reith, Maarten E A; Patel, Jyoti C; Sarti, Federica; Carr, Kenneth D; Rice, Margaret E

    2011-09-01

    Dopamine (DA) is an important transmitter in both motor and limbic pathways. We sought to investigate the role of D(1)-receptor activation in axonal DA release regulation in dorsal striatum using a D(1)-receptor antagonist, SKF-83566. Evoked DA release was monitored in rat striatal slices using fast-scan cyclic voltammetry. SKF-83566 caused a concentration-dependent increase in peak single-pulse evoked extracellular DA concentration, with a maximum increase of ∼ 65% in 5 μM SKF-83566. This was accompanied by a concentration-dependent increase in extracellular DA concentration clearance time. Both effects were occluded by nomifensine (1 μM), a dopamine transporter (DAT) inhibitor, suggesting that SKF-83566 acted via the DAT. We tested this by examining [(3)H]DA uptake into LLc-PK cells expressing rat DAT, and confirmed that SKF-83566 is a competitive DAT inhibitor with an IC(50) of 5.7 μM. Binding studies with [(3)H]CFT, a cocaine analog, showed even more potent action of SKF-83566 at the DAT cocaine binding site (IC(50) = 0.51 μM). Thus, data obtained using SKF-83566 as a D(1) DA-receptor antagonist may be confounded by concurrent DAT inhibition. More positively, however, SKF-83566 might be a candidate to attenuate cocaine effects in vivo because of the greater potency of this drug at the cocaine versus DA binding site of the DAT.

  17. Postnatal treatment of rats with adrenergic receptor agonists or antagonists influences differentiation of sexual behavior.

    PubMed

    Jarzab, B; Sickmöller, P M; Geerlings, H; Döhler, K D

    1987-12-01

    The aim of the study was to investigate the possible role of the adrenergic system in development and differentiation of neural centers controlling sexual behavior in adulthood. For this purpose normal and androgenized female rats were treated with the alpha 1-receptor antagonist prazosin, the alpha 2-receptor agonist clonidine, or the alpha 2-receptor antagonist yohimbine-HCl throughout the first week of life. In adulthood all animals were ovariectomized and, after appropriate hormone-priming, they were tested for the capacity to display female and male sexual behavior patterns. Alteration of adrenergic transmission during the critical postnatal period for sexual differentiation of neural centers resulted in significant changes in the capacity to express female lordosis behavior in adulthood. In nonandrogenized animals clonidine significantly reduced the capacity for lordosis behavior. In androgenized animals clonidine had the opposite effect; it attenuated the inhibitory effect of testosterone propionate (TP) on differentiation of lordosis behavior. Prazosin, which was without effect in nonandrogenized animals, also attenuated the inhibitory effect of TP on differentiation of lordosis behavior. Yohimbine was without effect in androgenized and nonandrogenized animals. There was no influence of any of the adrenergic drugs on differentiation of male sexual behavior. In conclusion, differentiation of lordosis behavior seems to be mediated or modulated via adrenergic transmission. The defeminizing effect of testosterone postnatally on the differentiation of lordosis behavior seems to be expressed via alpha 1-adrenergic transmission, and diminished adrenergic activity during the postnatal period seems to protect the developing brain against this effect of testosterone.

  18. Action of adenosine receptor antagonists on the cardiovascular response to defence area stimulation in the rat.

    PubMed Central

    St Lambert, J H; Dawid-Milner, M S; Silva-Carvalho, L; Spyer, K M

    1994-01-01

    1. The action of adenosine in the mediation of the cardiovascular changes associated with the defence reaction has been investigated in the rat using two A1 receptor antagonists. 2. Cumulative doses of 1,3 dipropyl-cyclopentylxanthine (DPCPX) (0.3-3 mg kg-1) and ethanol (0.03-0.25 ml) and bolus doses of DPCPX (3 mg kg-1) and 8-sulphophenyltheophylline (8-SPT) (20 mg kg-1) were given into alpha-chloralose, paralysed and artificially ventilated rats. Recordings were made of arterial blood pressure and heart rate. 3. Ethanol, the vehicle for DPCPX, failed to modify the magnitude of the defence response; however, cumulative doses of DPCPX produced a dose-dependent decrease in the HDA (hypothalamic defence area)-evoked increase in arterial blood pressure, accompanied by a similar fall in the magnitude of the evoked heart rate response. 4. The evoked rise in arterial blood pressure was reduced significantly by intravenous injection of DPCPX (3 mg kg-1) but not 8-SPT (20 mg kg-1), a purely peripherally acting adenosine antagonist. 5. These results suggest that adenosine acting at A1 receptors located in the central nervous system, is involved in the HDA-evoked pressor response. Whilst the site of action of the A1 receptors is not known, possible locations are discussed. PMID:7812606

  19. Stilbene derivatives as human 5-HT(6) receptor antagonists from the root of Caragana sinica.

    PubMed

    Kim, Dong Hyuk; Kim, Soon-Hee; Kim, Hyoung Ja; Jin, Changbae; Chung, Kwang Chul; Rhim, Hyewhon

    2010-01-01

    The 5-HT₆ receptor (5-HT₆R) is a member of the class of recently discovered 5-hydroxytryptamine (5-HT) receptors. Due to the lack of selective 5-HT₆R ligands, the cellular signaling mechanisms of the 5-HT₆R are poorly understood. We previously developed a cell-based high-throughput screening (HTS) method for the 5-HT₆R and screened synthetic chemical compounds. In the present study, we expanded our screening into natural products to find novel 5-HT₆R ligands. We found that the ethyl acetate fraction from the root of Caragana sinica (537-18BE) produced the most potent antagonistic activity. After further isolation of 537-18BE, we found that three stilbene derivatives, (+)-α-viniferin, miyabenol C and pallidol, are active constituents of 537-18BE inhibiting the 5-HT₆R. Among them, (+)-α-viniferin showed the most potent inhibition, and miyabenol C also produced a considerable inhibition. When examined effects on other neurotransmitters for selectivity, 537-18BE and three stilbene derivatives did not produce any notable effects on 5-HT₄, 5-HT₇, or muscarinic acetylcholine M1 (M(1)) receptors. Furthermore, 5-HT₆R antagonistic effects of (+)-α-viniferin, miyabenol C and pallidol were confirmed on extracellular signal-regulated kinase 1 and 2 (ERK1/2) which exerts effects in downstream pathways of 5-HT₆R activation.

  20. Past, present and future of A(2A) adenosine receptor antagonists in the therapy of Parkinson's disease.

    PubMed

    Armentero, Marie Therese; Pinna, Annalisa; Ferré, Sergi; Lanciego, José Luis; Müller, Christa E; Franco, Rafael

    2011-12-01

    Several selective antagonists for adenosine A(2A) receptors (A(2A)R) are currently under evaluation in clinical trials (phases I to III) to treat Parkinson's disease, and they will probably soon reach the market. The usefulness of these antagonists has been deduced from studies demonstrating functional interactions between dopamine D₂ and adenosine A(2A) receptors in the basal ganglia. At present it is believed that A(2A)R antagonists can be used in combination with the dopamine precursor L-DOPA to minimize the motor symptoms of Parkinson's patients. However, a considerable body of data indicates that in addition to ameliorating motor symptoms, adenosine A(2A)R antagonists may also prevent neurodegeneration. Despite these promising indications, one further issue must be considered in order to develop fully optimized antiparkinsonian drug therapy, namely the existence of (hetero)dimers/oligomers of G protein-coupled receptors, a topic that is currently the focus of intense debate within the scientific community. Dopamine D₂ receptors (D₂Rs) expressed in the striatum are known to form heteromers with A(2A) adenosine receptors. Thus, the development of heteromer-specific A(2A) receptor antagonists represents a promising strategy for the identification of more selective and safer drugs.

  1. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    PubMed Central

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-01-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1–3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents. PMID:27094554

  2. Antagonistic effects of extracts from Artemisia rupetris L. and Leontopodium leontopodioides to CC chemokine receptor 2b (CCR2b).

    PubMed

    Yu, Qin-Wei; Hu, Jie; Wang, Hao; Chen, Xin; Zhao, Fang; Gao, Peng; Yang, Qiu-Bin; Sun, Dan-Dan; Zhang, Lu-Yong; Yan, Ming

    2016-05-01

    The present study was designed to establish a suitable assay to explore CCR2b receptor antagonists from the natural products of Artemisia rupetris and Leontopodium leontopodioides. An aequorin assay was developed as a cell-based assay suitable for 384-well microplate and used for screening CCR2b receptor antagonists from natural products. Through establishing suitable conditions, the assay was shown to be suitable for screening of CCR2b receptor antagonists. Seven compounds were identified in preliminary screening. Five of them showed evident dose-response relationship in secondary screening. The structure-activity relationship study suggested that 7-position hydroxyl group of flavonoids was necessary, a polar group should be introduced on the 3-position, and the substituents on 2-position benzene ring of flavonoids have little influence on the potentency of the inhibition activity on CCR2b receptor. The ortho-position dihydroxyl structure in quinic acid compounds may be important. In conclusion, Compounds HR-1, 5, 7, and AR-20, 35 showed activity as antagonist of CCR2b receptor, which shed lights on the development of novel drugs as CCR2b receptor antagonists for preventing inflammation related diseases.

  3. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    NASA Astrophysics Data System (ADS)

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-04-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1–3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents.

  4. KW-3902, a selective high affinity antagonist for adenosine A1 receptors.

    PubMed Central

    Nonaka, H.; Ichimura, M.; Takeda, M.; Kanda, T.; Shimada, J.; Suzuki, F.; Kase, H.

    1996-01-01

    1. We demonstrate that 8-(noradamantan-3-yl)-1,3-dipropylxanthine (KW-3902) is a very potent and selective adenosine A1 receptor antagonist, assessed by radioligand binding and cyclic AMP response in cells. 2. In rat forebrain adenosine A1 receptors labelled with [3H]-cyclohexyladenosine (CHA), KW-3902 had a Ki value of 0.19 nM, whereas it showed a Ki value of 170 nM in rat striatal A2A receptors labelled with [3H]-2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoad enosine (CGS21680), indicating 890 fold A1 receptor selectivity versus the A2A receptor. KW-3902 at 10 microM showed no effect on recombinant rat A3 receptors expressed on CHO cells. 3. Saturation studies with [3H]-KW-3902 revealed that it bound with high affinity (Kd = 77 pM) and limited capacity (Bmax = 470 fmol mg-1 of protein) to a single class of recognition sites. A high positive correlation was observed between the pharmacological profile of adenosine ligands inhibiting the binding of [3H]-KW-3902 and that of [3H]-CHA. 4. KW-3902 showed potent A1 antagonism against the inhibition of forskolin-induced cyclic AMP accumulation in DDT1 MF-2 cells by the A1-selective agonist, cyclopentyladenosine with a dissociation constant (KB value) of 0.34 nM. KW-3902 antagonized 5'-N-ethylcarboxamidoadenosine-elicited cyclic AMP accumulation via A2B receptors with a KB value of 52 nM. 5. KW-3902 exhibited marked species-dependent differences in the binding affinities. The highest affinity was for the rat A1 receptor (ki = 0.19 nM) and these values for guinea-pig and dog A1 receptors were 1.3 and 10 nM, respectively. PMID:8732272

  5. Novel triple neurokinin receptor antagonist CS-003 inhibits respiratory disease models in guinea pigs.

    PubMed

    Tsuchida, Hiroshi; Takahashi, Sakiko; Nosaka, Emi; Kuraya, Takako; Yamashita, Makoto; Morimoto, Kiyoshi

    2008-10-31

    Neurokinins are known to induce neurogenic inflammation related to respiratory diseases. The effects of CS-003 ([1-{2-[(2R)-(3,4-dichlorophenyl)-4-(3,4,5-trimethoxybenzoyl)morpholin-2-yl]ethyl}spiro[benzo[c]thiophene-1(3H),4'-piperidine]-(2S)-oxide hydrochloride]), a novel triple neurokinin receptor antagonist, on several respiratory disease models were evaluated in guinea pigs. As we have already shown that CS-003 is intravenously effective, we first determined if CS-003 was orally effective. CS-003 dose-dependently inhibited substance P-induced tracheal vascular hyperpermeability, neurokinin A- and neurokinin B-induced bronchoconstriction with ID(50) values of 3.6, 1.3 and 0.89 mg/kg (p.o.), respectively. CS-003 (10 mg/kg, p.o.) inhibited the number of coughs induced by capsaicin aerosol (P<0.01) and the antitussive effect was comparable to that of codeine. CS-003 (10 mg/kg, p.o.) also inhibited airway hyperresponsiveness to methacholine chloride in ovalbumin-induced asthma models (P<0.01), a milder one and a severer one. On the other hand, montelukast (10 mg/kg, p.o.), a leukotriene receptor antagonist, significantly inhibited the hyperresponsiveness only in the milder model (P<0.05). In an ovalbumin-induced rhinitis model, oral administration of CS-003 inhibited nasal blockade in a dose-dependent manner and the inhibitory effect was comparable to that of dexamethasone (10 mg/kg, p.o.). CS-003 (i.v.) also dose-dependently inhibited cigarette smoke-induced bronchoconstriction, tracheal vascular hyperpermeability and mucus secretion. These data show that CS-003, a potent orally active triple neurokinin receptor antagonist, may be useful for the treatment of respiratory diseases associated with neurokinins, such as allergic asthma, allergic rhinitis, chronic obstructive pulmonary disease and cough.

  6. 2-Aminoethyl Methylphosphonate, a Potent and Rapidly Acting Antagonist of GABAA-ρ1 Receptors

    PubMed Central

    Xie, An; Yan, Jun; Yue, Lan; Feng, Feng; Mir, Fozia; Abdel-Halim, Heba; Chebib, Mary; Le Breton, Guy C.; Standaert, Robert F.; Qian, Haohua

    2011-01-01

    2-Aminoethyl methylphosphonate (2-AEMP), an analog of GABA, has been found to exhibit antagonist activity at GABAA-ρ1 (also known as ρ1 GABAC) receptors. The present study was undertaken to elucidate 2-AEMP's action and to test the activities of 2-AEMP analogs. Whole-cell patch-clamp techniques were used to record membrane currents in neuroblastoma cells stably transfected with human GABAA-ρ1 receptors. The action of 2-AEMP was compared with that of 1,2,5,6-tetrahydropyridin-4-yl methylphosphinic acid (TPMPA), a commonly used GABAA-ρ1 antagonist. With 10 μM GABA, 2-AEMP's IC50 (18 μM) differed by less than 2.5-fold from that of TPMPA (7 μM), and results obtained were consistent with a primarily competitive mode of inhibition by 2-AEMP. Terminating the presentation of 2-AEMP or TPMPA in the presence of GABA produced a release from inhibition. However, the rate of inhibition release upon the termination of 2-AEMP considerably exceeded that determined with termination of TPMPA. Moreover, when presented at concentrations near their respective IC50 values, the preincubation period associated with 2-AEMP's onset of inhibition was much shorter than that for TPMPA. Analogs of 2-AEMP possessing a benzyl or n-butyl rather than a methyl substituent at the phosphorus atom, as well as analogs bearing a C-methyl substituent on the aminoethyl side chain, exhibited reduced potency relative to 2-AEMP. Of these analogs, only (R)-2-aminopropyl methylphosphonate significantly diminished the response to 10 μM GABA. Structure-activity relationships are discussed in the context of molecular modeling of ligand binding to the antagonist binding site of the GABAA-ρ1 receptor. PMID:21810922

  7. [Cost-effectiveness analysis of 5-HT3 receptor antagonist drugs in cancer chemotherapy].

    PubMed

    Ishimaru, Hiromasa; Takayama, Shinji; Shiokawa, Mitsuru; Inoue, Tadao

    2008-04-01

    Recently, ambulatory treatment centers (ATC) are markedly increasingboth in number and scale. It is therefore important to consolidate an efficient therapeutic system. A decrease in both treatment time and waitingtime leads to not only the improvement of the quality of life (QOL) for patients but also the efficient use of personnel and running costs for medical institutions by reducingthe bed occupation rate. In ATC, 5-HT3 receptor antagonists are extensively used for high emetic risk patients. However, their high cost and prolonged treatment causes one of the problems in improvingthe efficiency of the therapeutic system when they are administered by intravenous infusion. Amongthe 4 types of 5-HT3 receptor antagonists (injections) currently available in Japan, azasetron is the only drugthat is not designated as a powerful drug and that can be administered by bolus intravenous infusion. In this study, we investigated azasetron and granisetron from the standpoint of pharmacoeconomics with a simulation model using the results of clinical studies in Japan. Accordingto the results of cost-effectiveness analysis, therapeutic and time costs per patient for azasetron 10 mgand granisetron 2 mg (calculated in consideration of both medical institutions and patients) was 8,219 and 10,193 yen, respectively. This gap was attributable to the time loss due to the difference in administration methods. The result suggests that this time loss is more significant not only for patients but also for medical staff than the loss attributable to the drugcost. Furthermore, the bolus intravenous infusion of azasetron is considered superior to the non-bolus intravenous infusion of granisetron from a pharmacoeconomic standpoint. It is desirable to choose the appropriate administration method of 5-HT3 receptor antagonists in various chemotherapy regimens for the purpose of reducingthe treatment time and promotingthe efficiency of the therapeutic system at ATCs.

  8. Galanin receptor antagonists : a potential novel pharmacological treatment for mood disorders.

    PubMed

    Ogren, Sven Ove; Kuteeva, Eugenia; Hökfelt, Tomas; Kehr, Jan

    2006-01-01

    functional activity. In addition, galanin produces a functional blockade of postsynaptic 5-HT1A receptor-mediated responses. Both pharmacological and genetic studies suggest a role for galanin in depression-like behaviour in rodent models. Transgenic mice overexpressing galanin under the control of the platelet-derived growth factor-beta promoter display increased immobility in the forced swim test. Intracerebroventricular administration of galanin in the rat increases depression-like behaviour, and this is fully blocked by the nonselective peptide galanin receptor antagonist M35. Importantly, M35 alone administered intracerebroventricularly produces an antidepressant-like effect. Recently, newly developed receptor-specific nonpeptidergic galanin GAL3 receptor antagonists (SNAP-37889 and SNAP-398299), which cross the blood-brain barrier after systemic administration, have shown antidepressant-like activity in several animal models. On the other hand, stimulation of the GAL2 receptor at the raphe level by local application of the GAL2 receptor agonist galanin (2-11) has been shown to increase serotonin levels in the hippocampus and dorsal raphe. These results indicate an important (mainly inhibitory) role of galanin as a regulator of brain serotonin and 5-HT1A receptor-mediated transmission, which may be of potential importance for understanding mood disorders and for the development of antidepressant drugs. Taken together, the present evidence suggests that antidepressant efficacy may be associated with compounds acting as antagonists at the GAL3 and/or possibly GAL1 receptors, and/or agonists at the GAL2 receptor.

  9. Comparative, general pharmacology of SDZ NKT 343, a novel, selective NK1 receptor antagonist

    PubMed Central

    Walpole, C S J; Brown, M C S; James, I F; Campbell, E A; McIntyre, P; Docherty, R; Ko, S; Hedley, L; Ewan, S; Buchheit, K-H; Urban, L A

    1998-01-01

    The in vitro and in vivo pharmacology of SDZ NKT 343 (2-nitrophenyl-carbamoyl-(S)-prolyl-(S)-3-(2-naphthyl)alanyl-N-benzyl-N-methylamide), a novel tachykinin NK1 receptor antagonist was investigated.SDZ NKT 343 inhibited [3H]-substance P binding to the human NK1 receptor in transfected Cos-7 cell membranes (IC50=0.62±0.11 nM). In comparison, in the same assay Ki values for FK888, CP 99,994, SR 140,333 and RPR 100,893 were 2.13±0.04 nM, 0.96±0.20 nM, 0.15±0.06 nM and 1.77±0.41 nM, respectively. SDZ NKT 343 showed a markedly lower affinity at rat NK1 receptors in whole forebrain membranes (IC50=451±139 nM).SDZ NKT 343 caused an increase in EC50 as well as reduction in the number of binding sites (Bmax) determined for [3H]-substance P, suggesting a non-competitive interaction at the human NK1 receptor. SDZ NKT 343 also caused a reduction in the maximum elevation of [Ca2+]i evoked by substance P (SP) in human U373MG cells and depressed the maximum [Sar9]SP sulphone-induced contraction of the guinea-pig isolated ileum. The antagonism of SP effects on U373MG cells by SDZ NKT 343 was reversible.SDZ NKT 343 showed weak affinity to human NK2 and NK3 receptors in transfected Cos-7 cells (Ki of 0.52±0.04 μM and 3.4±1.2 μM, respectively). SDZ NKT 343 was inactive in a broad array of binding assays including the bradykinin B2 receptor the histamine H1 receptor, opiate receptors and adrenoceptors. SDZ NKT 343 only weakly inhibited the voltage-activated Ca2+ and Na+currents in guinea-pig dorsal root ganglion neurones. The enantiomer of SDZ NKT 343, (R,R)-SDZ NKT 343 was about 1000 times less active at human NK1 receptors expressed in Cos-7 cell membranes.Contractions of the guinea-pig ileum by [Sar9]SP sulphone were inhibited by SDZ NKT 343 in a concentration-dependent manner, with an IC50=1.60±0.94 nM, while the enantiomer (R,R)-SDZ NKT 343 was 100 times less active (IC50=162±26 nM). In comparison, in the same assay IC50 values for other NK1

  10. The Dual Orexin Receptor Antagonist Almorexant Induces Sleep and Decreases Orexin-Induced Locomotion by Blocking Orexin 2 Receptors

    PubMed Central

    Mang, Géraldine M.; Dürst, Thomas; Bürki, Hugo; Imobersteg, Stefan; Abramowski, Dorothee; Schuepbach, Edi; Hoyer, Daniel; Fendt, Markus; Gee, Christine E.

    2012-01-01

    Study Objectives: Orexin peptides activate orexin 1 and orexin 2 receptors (OX1R and OX2R), regulate locomotion and sleep-wake. The dual OX1R/OX2R antagonist almorexant reduces activity and promotes sleep in multiple species, including man. The relative contributions of the two receptors in locomotion and sleep/wake regulation were investigated in mice. Design: Mice lacking orexin receptors were used to determine the contribution of OX1R and OX2R to orexin A-induced locomotion and to almorexant-induced sleep. Setting: N/A. Patients or Participants: C57BL/6J mice and OX1R+/+, OX1R-/-, OX2R+/+, OX2R-/- and OX1R-/-/OX2R-/- mice. Interventions: Intracerebroventricular orexin A; oral dosing of almorexant. Measurements and Results: Almorexant attenuated orexin A-induced locomotion. As in other species, almorexant dose-dependently increased rapid eye movement sleep (REM) and nonREM sleep in mice. Almorexant and orexin A were ineffective in OX1R-/-/OX2R-/- mice. Both orexin A-induced locomotion and sleep induction by almorexant were absent in OX2R-/- mice. Interestingly, almorexant did not induce cataplexy in wild-type mice under conditions where cataplexy was seen in mice lacking orexins and in OX1R-/-/OX2R-/- mice. Almorexant dissociates very slowly from OX2R as measured functionally and in radioligand binding. Under non equilibrium conditions in vitro, almorexant was a dual antagonist whereas at equilibrium, almorexant became OX2R selective. Conclusions: In vivo, almorexant specifically inhibits the actions of orexin A. The two known orexin receptors mediate sleep induction by almorexant and orexin A-induced locomotion. However, OX2R activation mediates locomotion induction by orexin A and antagonism of OX2R is sufficient to promote sleep in mice. Citation: Mang GM; Dürst T; Bürki H; Imobersteg S; Abramowski D; Schuepbach E; Hoyer D; Fendt M; Gee CE. The dual orexin receptor antagonist almorexant induces sleep and decreases orexin-induced locomotion by blocking orexin

  11. Discovery of histamine H3 receptor antagonistic property of simple imidazole-free derivatives: Preliminary pharmacological investigation.

    PubMed

    Barocelli, Elisabetta; Ballabeni, Vigilio; Manenti, Veronica; Flammini, Lisa; Bertoni, Simona; Morini, Giovanni; Comini, Mara; Impicciatore, Mariannina

    2006-03-01

    The histamine H3 receptor subtype negatively modulates the release of various neurotransmitters such as histamine, glutamate, norepinephrine, acetylcholine and many others mainly in the CNS and H3 antagonists have been developed to treat central diseases characterized by neurotransmission disturbance such as schizophrenia, memory/learning and sleep disorders. In search for non-imidazole histamine H3 receptor antagonists, currently indicated as a promising class of H3 blockers, a series of simple alkylpiperidine derivatives has been studied to attain a preliminary pharmacological profile. The compounds were characterized in vitro in terms of binding affinity, antagonistic potency and selectivity at rodent H3 receptors. The imidazole-free derivatives possessed moderate to pronounced antagonistic potency at guinea-pig ileal H3 receptor consistent with binding affinity at rat brain H3 receptors and showed a favourable receptor selectivity profile. For the compound 5, with the highest affinity at rat H3 receptors, comparable values were calculated in binding (pKi = 8.35) and functional (pA2 = 8.22) assays in SK-N-MC cells stably expressing human H3 receptors. These findings indicate to extend the investigation to pharmacokinetic property and central effects to gain deeper knowledge on the pharmacological potential of this compound.

  12. Design and optimization of quinazoline derivatives as melanin concentrating hormone receptor 1 (MCHR1) antagonists.

    PubMed

    Sasmal, Sanjita; Balaji, Gade; Kanna Reddy, Hariprasada R; Balasubrahmanyam, D; Srinivas, Gujjary; Kyasa, Shivakumar; Sasmal, Pradip K; Khanna, Ish; Talwar, Rashmi; Suresh, J; Jadhav, Vikram P; Muzeeb, Syed; Shashikumar, Dhanya; Harinder Reddy, K; Sebastian, V J; Frimurer, Thomas M; Rist, Øystein; Elster, Lisbeth; Högberg, Thomas

    2012-05-01

    Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays a role in metabolic and CNS disorders. The modeling-supported design, synthesis and multi-parameter optimization (biological activity, solubility, metabolic stability, hERG) of novel quinazoline derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified. Clusters of refined hMCHR1 homology models derived from the X-ray structure of the β2-adrenergic receptor, including extracellular loops, were developed and used to guide the design.

  13. Synthesis of benzopolycyclic cage amines: NMDA receptor antagonist, trypanocidal and antiviral activities

    PubMed Central

    Torres, Eva; Duque, María D.; López-Querol, Marta; Taylor, Martin C.; Naesens, Lieve; Ma, Chunlong; Pinto, Lawrence H.; Sureda, Francesc X.; Kelly, John M.; Vázquez, Santiago

    2012-01-01

    The synthesis of several 6,7,8,9,10,11-hexahydro-9-methyl-5,7:9,11-dimethano-5H-benzocyclononen-7-amines is reported. Several of them display low micromolar NMDA receptor antagonist and/or trypanocidal activities. Two compounds are endowed with micromolar anti vesicular stomatitis virus activity, while only one compound shows micromolar anti-influenza activity. The anti-influenza activity of this compound does not seem to be mediated by blocking of the M2 protein. PMID:22178660

  14. The discovery of quinoline based single-ligand human H1 and H3 receptor antagonists.

    PubMed

    Procopiou, Panayiotis A; Ancliff, Rachael A; Gore, Paul M; Hancock, Ashley P; Hodgson, Simon T; Holmes, Duncan S; Keeling, Steven P; Looker, Brian E; Parr, Nigel A; Rowedder, James E; Slack, Robert J

    2016-12-15

    A novel series of potent quinoline-based human H1 and H3 bivalent histamine receptor antagonists, suitable for intranasal administration for the potential treatment of allergic rhinitis associated nasal congestion, were identified. Compound 18b had slightly lower H1 potency (pA2 8.8 vs 9.7 for the clinical goldstandard azelastine), and H3 potency (pKi 9.1vs 6.8 for azelastine), better selectivity over α1A, α1B and hERG, similar duration of action, making 18b a good back-up compound to our previous candidate, but with a more desirable profile.

  15. Characterization of a Sphingosine 1-Phosphate Receptor Antagonist ProdrugS⃞

    PubMed Central

    Kennedy, Perry C.; Zhu, Ran; Huang, Tao; Tomsig, Jose L.; Mathews, Thomas P.; David, Marion; Peyruchaud, Olivier; Macdonald, Timothy L.

    2011-01-01

    Sphingosine 1-phosphate (S1P) is a phospholipid that binds to a set of G protein-coupled receptors (S1P1–S1P5) to initiate an array of signaling cascades that affect cell survival, differentiation, proliferation, and migration. On a larger physiological scale, the effects of S1P on immune cell trafficking, vascular barrier integrity, angiogenesis, and heart rate have also been observed. An impetus for the characterization of S1P-initiated signaling effects came with the discovery that FTY720 [fingolimod; 2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol] modulates the immune system by acting as an agonist at S1P1. In the course of structure-activity relationship studies to better understand the functional chemical space around FTY720, we discovered conformationally constrained FTY720 analogs that behave as S1P receptor type-selective antagonists. Here, we present a pharmacological profile of a lead S1P1/3 antagonist prodrug, 1-(hydroxymethyl)-3-(3-octylphenyl)cyclobutane (VPC03090). VPC03090 is phosphorylated by sphingosine kinase 2 to form the competitive antagonist species 3-(3-octylphenyl)-1-(phosphonooxymethyl)cyclobutane (VPC03090-P) as observed in guanosine 5′-O-(3-[35S]thio)triphosphate binding assays, with effects on downstream S1P receptor signaling confirmed by Western blot and calcium mobilization assays. Oral dosing of VPC03090 results in an approximate 1:1 phosphorylated/alcohol species ratio with a half-life of 30 h in mice. Because aberrant S1P signaling has been implicated in carcinogenesis, we applied VPC03090 in an immunocompetent mouse mammary cancer model to assess its antineoplastic potential. Treatment with VPC03090 significantly inhibited the growth of 4T1 primary tumors in mice. This result calls to attention the value of S1P receptor antagonists as not only research tools but also potential therapeutic agents. PMID:21632869

  16. Simultaneous determination of hydrochlorothiazide and several angiotensin-II-receptor antagonists by capillary electrophoresis.

    PubMed

    Hillaert, S; Van den Bossche, W

    2003-02-26

    We have investigated the capability of the capillary zone electrophoretic (CZE) and micellar electrokinetic capillary chromatographic (MEKC) methods to simultaneously separate hydrochlorothiazide and six angiotensin-II-receptor antagonists (ARA-IIs): candesartan, eprosartan mesylate, irbesartan, losartan potassium, telmisartan, and valsartan. The CZE and MEKC methods are suitable for the qualitative and quantitative determination of combined HCT/ARA-IIs in pharmaceutical formulations. Depending on the ARA-II, at least one of the two methods can be used for each combination. The two methods have been validated in terms of their linearity of response, reproducibility, and accuracy.

  17. 2-Amino-6-chloro-3,4-dihydroquinazoline: A novel 5-HT3 receptor antagonist with antidepressant character.

    PubMed

    Dukat, Małgorzata; Alix, Katie; Worsham, Jessica; Khatri, Shailesh; Schulte, Marvin K

    2013-11-01

    2-Amino-6-chloro-3,4-dihydroquinazoline HCl (A6CDQ, 4) binds at 5-HT3 serotonin receptors and displays antidepressant-like action in the mouse tail suspension test (TST). Empirically, 4 was demonstrated to be a 5-HT3 receptor antagonist (two-electrode voltage clamp recordings using frog oocytes; IC50=0.26μM), and one that should readily penetrate the blood-brain barrier (logP=1.86). 5-HT3 receptor antagonists represent a potential approach to the development of new antidepressants, and 4 is an example of a structurally novel 5-HT3 receptor antagonist that is active in a preclinical antidepressant model (i.e., the mouse TST).

  18. 5-HT2A receptor antagonists improve motor impairments in the MPTP mouse model of Parkinson's disease.

    PubMed

    Ferguson, Marcus C; Nayyar, Tultul; Deutch, Ariel Y; Ansah, Twum A

    2010-01-01

    Clinical observations have suggested that ritanserin, a 5-HT(2A/C) receptor antagonist may reduce motor deficits in persons with Parkinson's Disease (PD). To better understand the potential antiparkinsonian actions of ritanserin, we compared the effects of ritanserin with the selective 5-HT(2A) receptor antagonist M100907 and the selective 5-HT(2C) receptor antagonist SB 206553 on motor impairments in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP-treated mice exhibited decreased performance on the beam-walking apparatus. These motor deficits were reversed by acute treatment with L-3,4-dihydroxyphenylalanine (levodopa). Both the mixed 5-HT(2A/C) antagonist ritanserin and the selective 5-HT(2A) antagonist M100907 improved motor performance on the beam-walking apparatus. In contrast, SB 206553 was ineffective in improving the motor deficits in MPTP-treated mice. These data suggest that 5-HT(2A) receptor antagonists may represent a novel approach to ameliorate motor symptoms of Parkinson's disease.

  19. Renal sodium transporter/channel expression and sodium excretion in P2Y2 receptor knockout mice fed a high-NaCl diet with/without aldosterone infusion.

    PubMed

    Zhang, Yue; Listhrop, Raelene; Ecelbarger, Carolyn M; Kishore, Bellamkonda K

    2011-03-01

    The P2Y(2) receptor (P2Y2-R) antagonizes sodium reabsorption in the kidney. Apart from its effect in distal nephron, hypothetically, P2Y(2)-R may modulate activity/abundances of sodium transporters/channel subunits along the nephron via antagonism of aldosterone or vasopressin or interaction with mediators such as nitric oxide (NO), and prostaglandin E(2) (PGE(2)) or oxidative stress (OS). To determine the extent of the regulatory role of P2Y(2)-R in renal sodium reabsorption, in study 1, we fed P2Y(2)-R knockout (KO; n = 5) and wild-type (WT; n = 5) mice a high (3.15%)-sodium diet (HSD) for 14 days. Western blotting revealed significantly higher protein abundances for cortical and medullary bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2), medullary α-1-subunit of Na-K-ATPase, and medullary α-subunit of the epithelial sodium channel (ENaC) in KO vs. WT mice. Molecular analysis of urine showed increased excretion of nitrates plus nitrites (NOx), PGE(2), and 8-isoprostane in the KO, relative to WT mice, supporting a putative role for these molecules in determining alterations of proteins involved in sodium transport along the nephron. To determine whether genotype differences in response to aldosterone might have played a role in these differences due to HSD, in study 2 aldosterone levels were clamped (by osmotic minipump infusion). Clamping aldosterone (with HSD) led to significantly impaired natriuresis with elevated Na/H exchanger isoform 3 in the cortex, and NKCC2 in the medulla, and modest but significantly lower levels of NKCC2, and α- and β-ENaC in the cortex of KO vs. WT mice. This was associated with significantly reduced urinary NOx in the KO, although PGE(2) and 8-isoprostane remained significantly elevated vs. WT mice. Taken together, our results suggest that P2Y(2)-R is an important regulator of sodium transporters along the nephron. Pre- or postreceptor differences in the response to aldosterone, perhaps mediated via prostaglandins or changes in

  20. Pharmacology of modality-specific transient receptor potential vanilloid-1 antagonists that do not alter body temperature.

    PubMed

    Reilly, Regina M; McDonald, Heath A; Puttfarcken, Pamela S; Joshi, Shailen K; Lewis, LaGeisha; Pai, Madhavi; Franklin, Pamela H; Segreti, Jason A; Neelands, Torben R; Han, Ping; Chen, Jun; Mantyh, Patrick W; Ghilardi, Joseph R; Turner, Teresa M; Voight, Eric A; Daanen, Jerome F; Schmidt, Robert G; Gomtsyan, Arthur; Kort, Michael E; Faltynek, Connie R; Kym, Philip R

    2012-08-01

    The transient receptor potential vanilloid-1 (TRPV1) channel is involved in the development and maintenance of pain and participates in the regulation of temperature. The channel is activated by diverse agents, including capsaicin, noxious heat (≥ 43°C), acidic pH (< 6), and endogenous lipids including N-arachidonoyl dopamine (NADA). Antagonists that block all modes of TRPV1 activation elicit hyperthermia. To identify efficacious TRPV1 antagonists that do not affect temperature antagonists representing multiple TRPV1 pharmacophores were evaluated at recombinant rat and human TRPV1 channels with Ca(2+) flux assays, and two classes of antagonists were identified based on their differential ability to inhibit acid activation. Although both classes of antagonists completely blocked capsaicin- and NADA-induced activation of TRPV1, select compounds only partially inhibited activation of the channel by protons. Electrophysiology and calcitonin gene-related peptide release studies confirmed the differential pharmacology of these antagonists at native TRPV1 channels in the rat. Comparison of the in vitro pharmacological properties of these TRPV1 antagonists with their in vivo effects on core body temperature confirms and expands earlier observations that acid-sparing TRPV1 antagonists do not significantly increase core body temperature. Although both classes of compounds elicit equivalent analgesia in a rat model of knee joint pain, the acid-sparing antagonist tested is not effective in a mouse model of bone cancer pain.

  1. A representative retinoid X receptor antagonist UVI3003 induced teratogenesis in zebrafish embryos.

    PubMed

    Zheng, Liang; Xu, Ting; Li, Daoji; Zhou, Junliang

    2015-03-01

    Retinoid X receptor (RXR) interfering activity has been detected in different water resources. To study RXR disruptor-induced toxicological effects on vertebrates, embryos of zebrafish (Danio rerio) were exposed to a representative RXR antagonist UVI3003. Results showed that the teratogenic index (LC50 /EC50 ) of UVI3003 was as high as 5.4. UVI3003 induced multiple malformations of embryos, including deformed fins, reduced brains, small jaws, bent tails and edema in hearts, the degree of which became more severe with increasing exposure concentration. Although no significant difference was observed in the hatching rates between the exposure group and control, the whole body length was significantly reduced by 6.5% and 8.9% when exposed to 200 and 300 µg l(-1) of UVI3003, respectively. The heart rate also significantly decreased by 8.8-50.2% during exposure. Further experiments revealed that the pharyngula stage was the most sensitive development phase in terms of embryo response to UVI3003. The results demonstrated severe teratogenicity of RXR antagonist in zebrafish embryos and provided important data for ecotoxicological evaluation of RXR antagonists.

  2. Dibutyl phthalate contributes to the thyroid receptor antagonistic activity in drinking water processes.

    PubMed

    Li, Na; Wang, Donghong; Zhou, Yiqi; Ma, Mei; Li, Jian; Wang, Zijian

    2010-09-01

    It has long been recognized that thyroid hormone (TH) is essential for normal brain development in both humans and animals, and there is growing evidence that environmental chemicals can disrupt the thyroid system. In the present work, we used a two-hybrid yeast assay to screen for agonistic or antagonistic thyroid receptor (TR) mediated effects in drinking waters. We found no TR agonistic, but TR antagonistic activities in all samples from the drinking water processes. The TR antagonistic activities in organic extracts of water samples were then calibrated regarding to a known TR-inhibitor, NH3, and were expressed as the NH3 equivalents (TEQbio). The observed TEQbio in waters ranged from 180.8+/-24.8 to 280.2+/-48.2 microg/L NH3. To identify the specific compounds responsible for TR disrupting activities, the concentrations of potentially thyroid-disrupting chemicals including organochlorine pesticides (OCPs), phenols, and phthalates in organic extracts were quantitatively determined and their toxic equivalents with respect to NH3 (TEQcal) were estimated from their concentration-dependent relationships, respectively, using the same set of bioassays. Based on the TEQ approach, it was revealed that dibutyl phthalate (DBP) accounted for 53.7+/-8.2% to 105.5+/-16.7% of TEQbio. There was no effective removal of these potential thyroid disrupting substances throughout drinking water treatment processes.

  3. Identification of a pepducin acting as S1P3 receptor antagonist.

    PubMed

    Severino, Beatrice; Incisivo, Giuseppina Maria; Fiorino, Ferdinando; Bertolino, Antonio; Frecentese, Francesco; Barbato, Francesco; Manganelli, Serena; Maggioni, Giada; Capasso, Domenica; Caliendo, Giuseppe; Santagada, Vincenzo; Sorrentino, Raffaella; Roviezzo, Fiorentina; Perissutti, Elisa

    2013-11-01

    Sphingosine-1-phosphate (S1P) is a bioactive lipid with key functions in the immune, inflammatory, and cardiovascular systems. S1P exerts its action through the interaction with a family of five known G protein-coupled receptors, named S1P(1-5). Among them, S1P(3) has been implicated in the pathological processes of a number of diseases, including sepsis and cancer. KRX-725 (compound 1) is a pepducin that mimics the effects of S1P by triggering specifically S1P(3). Here, aiming to identify novel S1P(3) antagonists, we carried out an alanine scanning analysis to address the contribution of the side chains of each amino acid residue to the peptide function. Then, deleted peptides from both the C- and N-terminus were prepared in order to determine the minimal sequence for activity and to identify the structural requirements for agonistic and, possibly, antagonistic behaviors. The pharmacological results of the Ala-scan derived compounds (2-10) suggested a high tolerance of the pepducin 1 to amino acid substitutions. Importantly, the deleted peptide 16 has the ability to inhibit, in a dose-dependent manner, both pepducin 1-induced vasorelaxation and fibroblast proliferation. Finally, a computational analysis was performed on the prepared compounds, showing that the supposed antagonists 16 and 17 appeared to be aligned with each other but not with the others. These results suggested a correlation between specific conformations and activities.

  4. Procognitive properties of drugs with single and multitargeting H3 receptor antagonist activities.

    PubMed

    Nikolic, Katarina; Filipic, Slavica; Agbaba, Danica; Stark, Holger

    2014-07-01

    The histamine H3 receptor (H3 R) is an important modulator of numerous central control mechanisms. Novel lead optimizations for H3 R antagonists/inverse agonists involved studies of structure-activity relationships, cross-affinities, and pharmacokinetic properties of promising ligands. Blockade of inhibitory histamine H3 autoreceptors reinforces histaminergic transmission, while antagonism of H3 heteroreceptors accelerates the corticolimbic liberation of acetylcholine, norepinephrine, glutamate, dopamine, serotonin and gamma-aminobutyric acid (GABA). The H3 R positioned at numerous neurotransmission crossroads indicates therapeutic applications of small-molecule H3 R modulators in a number of psychiatric and neurodegenerative diseases with various clinical candidates available. Dual target drugs displaying H3 R antagonism/inverse agonism with inhibition of acetylcholine esterase (AChE), histamine N-methyltransferase (HMT), or serotonin transporter (SERT) are novel class of procognitive agents. Main chemical diversities, pharmacophores, and pharmacological profiles of procognitive agents acting as H3 R antagonists/inverse agonists and dual H3 R antagonists/inverse agonists with inhibiting activity on AChE, HMT, or SERT are highlighted here.

  5. Structure-Activity Relationships of the Peptide Kappa Opioid Receptor Antagonist Zyklophin

    PubMed Central

    Joshi, Anand A.; Murray, Thomas F.; Aldrich, Jane V.

    2016-01-01

    The dynorphin (Dyn) A analog zyklophin ([N-benzyl-Tyr1-cyclo(D-Asp5,Dap8)]dynorphin A(1-11)NH2) is a kappa opioid receptor (KOR) selective antagonist in vitro, is active in vivo and antagonizes KOR in the CNS after systemic administration. Hence, we synthesized zyklophin analogs to explore the structure-activity relationships of this peptide. The synthesis of selected analogs required modification to introduce the N-terminal amino acid due to poor solubility and/or to avoid epimerization of this residue. Among the N-terminal modifications the N-phenethyl and the N-cyclopropylmethyl substitutions resulted in the analogs with the highest KOR affinities. Pharmacological results for the alanine-substituted analogs indicated that Phe4 and Arg6, but interestingly not the Tyr1, phenol are important for zyklophin’s KOR affinity, and Arg7 was important for KOR antagonist activity. In the GTPγS assay while all of the cyclic analogs exhibited negligible KOR efficacy, the N-phenethyl-Tyr1, N-CPM-Tyr1 and the N-benzyl-Phe1 analogs were 8- to 24-fold more potent KOR antagonists than zyklophin. PMID:26491810

  6. Theoretical evaluation of antiemetic effects of 5-HT3 receptor antagonists for prevention of vomiting induced by cisplatin.

    PubMed

    Nakamura, Hironori; Yokoyama, Haruko; Takayanagi, Risa; Yoshimoto, Koichi; Nakajima, Akihiro; Okuyama, Kiyoshi; Iwase, Osamu; Yamada, Yasuhiko

    2015-03-01

    5-HT(3) receptor antagonists are widely used as antiemetic agents in clinical setting, of which palonosetron, with a long elimination half life (t(1/2)), has recently become available. It is important to evaluate the concentration of serotonin when investigating the antiemetic effects of 5-HT(3) receptor antagonists, as those effects are not based solely on the t(1/2) value. We theoretically evaluated the antiemetic effects of three 5-HT(3) receptor antagonists (granisetron, azasetron, palonosetron) on cisplatin-induced nausea and vomiting by estimating the time course of the 5-HT(3) receptor occupancy of serotonin. We estimated the 5-HT(3) receptor occupancy of serotonin in the small intestine, based on the time course of plasma concentration of each 5-HT(3) receptor antagonist and the time course of concentration of serotonin near the 5-HT(3) receptor in the small intestine after administration of cisplatin. The antiemetic effect of each 5-HT(3) receptor antagonist was evaluated based on the normal level of 5-HT(3) receptor occupancy of serotonin. Our results suggest that an adequate antiemetic effect will be provided when a dose of 75 mg/m(2) of cisplatin is given to patients along with any single administration of granisetron, azasetron, or palonosetron at a usual dose. On the other hand, the 5-HT(3) receptor occupancy of serotonin was found to be significantly lower than normal for several days after administration of palonosetron, as compared to granisetron and azasetron, indicating that constipation may be induced. Our results show that granisetron, azasetron, and palonosetron each have an adequate antiemetic effect after administration of 75 mg/m(2) of cisplatin.

  7. (3-Aminocyclopentyl)methylphosphinic acids: novel GABA(C) receptor antagonists.

    PubMed

    Chebib, Mary; Hanrahan, Jane R; Kumar, Rohan J; Mewett, Kenneth N; Morriss, Gwendolyn; Wooller, Soraya; Johnston, Graham A R

    2007-03-01

    Our understanding of the role GABA(C) receptors play in the central nervous system is limited due to a lack of specific ligands. Here we describe the pharmacological effects of (+/-)-cis-3- and (+/-)-trans-3-(aminocyclopentyl)methylphosphinic acids ((+/-)-cis- and (+/-)-trans-3-ACPMPA) as novel ligands for the GABA(C) receptor showing little activity at GABA(A) or GABA(B) receptors. (+/-)-cis-3-ACPMPA has similar potency to (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) at human recombinant rho1 (K(B)=1.0+/-0.2microM) and rat rho3 (K(B)=5.4+/-0.8microM) but is 15 times more potent than TPMPA on human recombinant rho2 (K(B)=1.0+/-0.3microM) GABA(C) receptors expressed in Xenopus oocytes. (+/-)-cis- and (+/-)-trans-3-ACPMPA are novel lead compounds for developing into more potent and selective GABA(C) receptor antagonists with increased lipophilicity for in vivo studies.

  8. Analysis of hydrophobic interactions of antagonists with the beta2-adrenergic receptor.

    PubMed

    Novoseletsky, V N; Pyrkov, T V; Efremov, R G

    2010-01-01

    The adrenergic receptors mediate a wide variety of physiological responses, including vasodilatation and vasoconstriction, heart rate modulation, and others. Beta-adrenergic antagonists ('beta-blockers') thus constitute a widely used class of drugs in cardiovascular medicine as well as in management of anxiety, migraine, and glaucoma. The importance of the hydrophobic effect has been evidenced for a wide range of beta-blocker properties. To better understand the role of the hydrophobic effect in recognition of beta-blockers by their receptor, we carried out a molecular docking study combined with an original approach to estimate receptor-ligand hydrophobic interactions. The proposed method is based on automatic detection of molecular fragments in ligands and the analysis of their interactions with receptors separately. A series of beta-blockers, based on phenylethanolamines and phenoxypropanolamines, were docked to the beta2-adrenoceptor binding site in the crystal structure. Hydrophobic complementarity between the ligand and the receptor was calculated using the PLATINUM web-server (http://model.nmr.ru/platinum). Based on the analysis of the hydrophobic match for molecular fragments of beta-blockers, we have developed a new scoring function which efficiently predicts dissociation constant (pKd) with strong correlations (r(2) approximately 0.8) with experimental data.

  9. Effects of the 5-HT(6) receptor antagonist Ro 04-6790 on learning consolidation.

    PubMed

    Meneses, A

    2001-01-08

    The 5-HT(6) receptor antagonist Ro-04-6790 or 8-OH-DPAT injection improved learning consolidation on an autoshaping task, while mCPP, scopolamine and dizocilpine decreased the performance. The effect induced by scopolamine, but not that induced by mCPP, was reversed completely by Ro-04-6790, while dizocilpine effect was antagonized partially. Nevertheless, ritanserin or WAY 100635, but not Ro 04-6790, antagonized the 8-OH-DPAT facilitatory effects on learning consolidation. As WAY 100635 did not modify the Ro 04-6790 facilitatory effect, hence 5-HT(1A), and/or 5-HT(7), but not 5-HT(6), receptors might mediate the 8-OH-DPAT facilitatory effect on learning consolidation. Since, the Ro 04-6790 facilitatory effect was unaffected by 5-HT(1A), 5-HT(2A)/(2B)/(2C), 5-HT(3) or 5-HT(4) receptor blockade, thereby, the facilitatory effect induced by Ro 04-6790 involved specifically 5-HT(6) receptors. Indeed, the present data provide further support to the notion that, 5-HT(6) receptors play a significant part in the learning consolidation under normal and dysfunctional memory conditions.

  10. Sulfur-Containing 1,3-Dialkylxanthine Derivatives as Selective Antagonists at A1-Adenosine Receptors

    PubMed Central

    Kiriasis, Leonidas; Barone, Suzanne; Bradbury, Barton J.; Kammula, Udai; Campagne, Jean Michel; Secunda, Sherrie; Daly, John W.; Neumeyer, John L.; Pfleiderer, Wolfgang

    2012-01-01

    Sulfur-containing analogues of 8-substituted xanthines were prepared in an effort to increase selectivity or potency as antagonists at adenosine receptors. Either cyclopentyl or various aryl substituents were utilized at the 8-position, because of the association of these groups with high potency at A1-adenosine receptors. Sulfur was incorporated on the purine ring at positions 2 and/or 6, in the 8-position substituent in the form of 2- or 3-thienyl groups, or via thienyl groups separated from an 8-aryl substituent through an amide-containing chain. The feasibility of using the thienyl group as a prosthetic group for selective iodination via its Hg2+ derivative was explored. Receptor selectivity was determined in binding assays using membrane homogenates from rat cortex [[3H]-N6-(phenylisopropyl) adenosine as radioligand] or striatum [[3H]-5′-(N-ethylcarbamoyl)adenosine as radioligand] for A1- and A2-adenosine receptors, respectively. Generally, 2-thio-8-cycloalkylxanthines were at least as A1 selective as the corresponding oxygen analogue. 2-Thio-8-aryl derivatives tended to be more potent at A2 receptors than the oxygen analogue. 8-[4-[(Carboxymethyl)oxy]phenyl]-1,3-dipropyl-2-thioxanthine ethyl ester was >740-fold A1 selective. PMID:2754711

  11. Estrogen receptor agonists/antagonists in breast cancer therapy: A critical review.

    PubMed

    Jameera Begam, A; Jubie, S; Nanjan, M J

    2017-04-01

    Estrogens display intriguing tissue selective action that is of great biomedical importance in the development of optimal therapeutics for the prevention and treatment of breast cancer. There are also strong evidences to show that both endogenous and exogenous estrogens are involved in the pathogenesis of breast cancer. Tamoxifen has been the only drug of choice for more than 30years to treat patients with estrogen related (ER) positive breast tumors. There is a need therefore, for identifying newer, potential and novel candidates for breast cancer. Keeping this in view, the present review focuses on selective estrogen receptor modulators and estrogen antagonists such as sulfatase and aromatase inhibitors involved in breast cancer therapy. A succinct and critical overview of the structure of estrogen receptors, their signaling and involvement in breast carcinogenesis are herein described.

  12. Recent advances in the development of dopamine D3 receptor antagonists: a medicinal chemistry perspective.

    PubMed

    Micheli, Fabrizio

    2011-07-04

    Dopamine (DA) D(3) receptor antagonism might play a significant role in different therapeutic areas. A high number of preclinical studies on DA D(3) receptor antagonists have shown efficacy in animal models of Parkinson's disease, schizophrenia and drug dependence. This Review covers the activities of medicinal chemists in this field over the last ten years towards the identification of truly selective compounds. Both primary and patent literature is reviewed here. Since the original discoveries, a clear trend towards the optimization of the developability properties of the new scaffold has clearly emerged with time, from both academic and industrial researchers. Examples of advanced leads from academia and industry are described. The latest potential therapeutic applications are reported too.

  13. Comparative Pharmacology and Guide to the Use of the Serotonin 5-HT3 Receptor Antagonists for Postoperative Nausea and Vomiting.

    PubMed

    Kovac, Anthony L

    2016-12-01

    Since the introduction of the serotonin 5-hydroxy tryptamine 3 (5-HT3) receptor antagonists in the early 1990s, the incidence of postoperative nausea and vomiting (PONV) and post-discharge nausea and vomiting (PDNV) has decreased, yet continues to be a problem for the surgical patient. The clinical application of the 5-HT3 receptor antagonists has helped define the approach and role of these antiemetics in the prevention and treatment of PONV and PDNV. Pharmacological and clinical differences exist among these medications resulting in corresponding differences in effectiveness, safety, optimal dosage, time of administration, and use as combination and rescue antiemetic therapy. The clinical application of the 5-HT3 receptor antagonist antiemetics has improved the prevention and treatment of PONV and PDNV. The most recent consensus guidelines for PONV published in 2014 outline the use of these antiemetics. The 5-HT3 receptor antagonists play an important role to help prevent PONV and PDNV in perioperative care pathways such as Enhanced Recovery After Surgery (ERAS). Comparisons and guidelines for use of the 5-HT3 receptor antagonists in relation to the risk for PONV and PDNV are reviewed.

  14. Pharmacological characterization of JNJ-28583867, a histamine H(3) receptor antagonist and serotonin reuptake inhibitor.

    PubMed

    Barbier, Ann J; Aluisio, Leah; Lord, Brian; Qu, Ying; Wilson, Sandy J; Boggs, Jamin D; Bonaventure, Pascal; Miller, Kirsten; Fraser, Ian; Dvorak, Lisa; Pudiak, Cindy; Dugovic, Christine; Shelton, Jonathan; Mazur, Curt; Letavic, Michael A; Carruthers, Nicholas I; Lovenberg, Timothy W

    2007-12-08

    Wake-promoting agents such as modafinil are used in the clinic as adjuncts to antidepressant therapy in order to alleviate lethargy. The wake-promoting action of histamine H(3) receptor antagonists has been evidenced in numerous animal studies. They may therefore be a viable strategy for use as an antidepressant therapy in conjunction with selective serotonin reuptake inhibitors. JNJ-28583867 (2-Methyl-4-(4-methylsulfanyl-phenyl)-7-(3-morpholin-4-yl-propoxy)-1,2,3,4-tetrahydro-isoquinoline) is a selective and potent histamine H(3) receptor antagonist (K(i)=10.6 nM) and inhibitor of the serotonin transporter (SERT) (K(i)=3.7 nM), with 30-fold selectivity for SERT over the dopamine and norepinephrine transporters. After subcutaneous administration, JNJ-28583867 occupied both the histamine H(3) receptor and the SERT in rat brain at low doses (<1 mg/kg). JNJ-28583867 blocked imetit-induced drinking (3-10 mg/kg i.p.), confirming in vivo functional activity at the histamine H(3) receptor and also significantly increased cortical extracellular levels of serotonin at doses of 0.3 mg/kg (s.c.) and higher. Smaller increases in cortical extracellular levels of norepinephrine and dopamine were also observed. JNJ-28583867 (3-30 mg/kg p.o.) showed antidepressant-like activity in the mouse tail suspension test. JNJ-28583867 (1-3 mg/kg s.c.) caused a dose-dependent increase in the time spent awake mirrored by a decrease in NREM. Concomitantly, JNJ-28583867 produced a potent suppression of REM sleep from the dose of 1 mg/kg onwards. JNJ-28583867 has good oral bioavailability in the rat (32%), a half-life of 6.9 h and a C(max) of 260 ng/ml after 10 mg/kg p.o. In summary, JNJ-28583867 is a combined histamine H(3) receptor antagonist-SERT inhibitor with in vivo efficacy in biochemical and behavioral models of depression and wakefulness.

  15. Development of interleukin-1 receptor antagonist mutants with enhanced antagonistic activity in vitro and improved therapeutic efficacy in collagen-induced arthritis.

    PubMed

    Dahlén, Eva; Barchan, Karin; Herrlander, Daniel; Höjman, Patrik; Karlsson, Marie; Ljung, Lill; Andersson, Mats; Bäckman, Eva; Hager, Ann-Christin Malmborg; Walse, Björn; Joosten, Leo; van den Berg, Wim

    2008-04-01

    Interleukin-1 receptor antagonist (IL-1Ra) is a naturally occurring inhibitor of the pro-inflammatory interleukin-1-mediated activation of the interleukin-1 receptor (IL-1R). Although wild-type IL-1Ra is used for treatment of inflammatory diseases, its effect is moderate and/or short-lived. The objective of this study was to generate IL-1Ra mutants with enhanced antagonistic activity for potential therapeutic use. Using a directed evolution approach in which libraries of IL-1Ra gene mutants were generated and screened in functional assays, mutants with desired properties were identified. Initially, diversity was introduced into the IL-1Ra using random mutagenesis. Mutations resulting in enhanced antagonistic activity were identified by screening in a reporter cell assay. To further enhance the antagonistic activity, selected mutations were recombined using the DNA recombination technology Fragment-INduced Diversity (FIND). Following three rounds of FIND recombination, several mutants with up to nine times enhanced antagonistic activity (mean IC50 +/- SEM value: 0.78 +/- 0.050 vs. 6.8 +/- 1.1 ng/ml for mutant and wild-type, respectively) were identified. Sequence analysis identified the mutations D47N, E52R and E90Y as being most important for this effect, however, the mutations P38Y, H54R, Q129L and M136N further enhanced the antagonistic function. Analysis of identified mutations in protein models based on the crystal structure of the IL-1Ra/IL-1R complex suggested that mutations found to enhance the antagonistic activity had a stabilizing effect on the IL-1Ra mutants or increased the affinity for the IL-1R. Finally, the therapeutic effect of one mutant was compared to that of wild-type IL-1Ra in collagen-induced arthritis in mice. Indeed, the enhanced antagonistic effect of the mutants observed in vitro was also seen in vivo. In conclusion, these results demonstrate that directed evolution of IL-1Ra is an effective means of generating highly potent therapeutic

  16. Mineralocorticoid receptor antagonist spironolactone prevents chronic corticosterone induced depression-like behavior.

    PubMed

    Wu, Ting-Ching; Chen, Han-Ting; Chang, Han-Ying; Yang, Ching-Yao; Hsiao, Mei-Chun; Cheng, Mei-Ling; Chen, Jin-Chung

    2013-06-01

    High level of serum corticosteroid is frequently associated with depression, in which a notable HPA (hypothalamus-pituitary-adrenal) axis hyperactivity is often observed. There are two types of corticosteroid receptors expressed in the hippocampus that provide potent negative feedback regulation on the HPA axis but dysfunction during depression, i.e. the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR). The balance between hippocampal MR and GR during chronic stress plays an important role in the occurrence of depression. The aim of this study is to explore if chronic corticosterone administration would induce depression-like behavior and affect the expression and function of hippocampal MR and GR, in addition to assess whether manipulation of corticosteroid receptors would modulate depressive behaviors. Hence, mice were treated with corticosterone (40 mg/kg) for 21 days followed by assessment in a battery of depression-like behaviors. The results show that chronic corticosterone-treated animals displayed an increased immobility time in a forced-swimming test, decreased preference to sucrose solution and novel object recognition performance, and enhanced hippocampal serotonin but decreased MR expression in both hippocampus and hypothalamus. On the other hand, co-administration of MR antagonist, spironolactone (25mg/kg, i.p. × 7 days) in corticosteroid-treated animals reduced immobility time in a forced-swimming test and improved performance in a novel object recognition test. In conclusion, we demonstrate that chronic corticosterone treatment triggers several depression-like behaviors, and in parallel, down-regulates MR expression in the hippocampus and hypothalamus. Administration of an MR antagonist confers an anti-depressant effect in chronic corticosterone-treated animals.

  17. Influence of different histamine receptor agonists and antagonists on apomorphine-induced licking behavior in rat.

    PubMed

    Farzin, D; Attarzadeh, M

    2000-09-15

    The effects of different histamine receptor agonists and antagonists on apomorphine-induced licking behavior in rats were investigated. Subcutaneous (s.c.) injection of various doses of apomorphine (0. 125-1.25 mg/kg) induced licking. The licking response was counted by direct observation and recorded for a 75-min period. Intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) injection of the histamine H(1) or H(2) receptor agonist, HTMT (6-[2-(4-imidazolyl)ethylamino]-N-(4-trifluoromethylphenyl) heptanecarboxamide) (50 and 100 microg per rat), or dimaprit (10 and 15 mg/kg, i.p.), respectively, potentiated apomorphine-induced licking, while the histamine H(3) receptor agonist, imetit (5 and 10 mg/kg, i.p.), reduced the licking response induced by apomorphine. Pretreatment with various histamine receptor antagonists, dexchlorpheniramine (30 and 40 mg/kg, i.p.), diphenhydramine (20, 30 and 40 mg/kg, i.p.), famotidine (30 and 40 mg/kg, s.c.) and ranitidine (20, 30 and 40 mg/kg), reduced apomorphine-induced licking, while thioperamide (5 and 10 mg/kg, i.p.) potentiated the apomorphine effect. The effects of HTMT and dimaprit were blocked by dexchlorpheniramine (20 mg/kg, i.p.) and famotidine (20 mg/kg, s.c.), respectively. The inhibitory effect elicited by imetit on apomorphine-induced licking behavior was also abolished in animals treated with thioperamide (2.5 mg/kg, i.p.). The results suggest that histaminergic mechanisms may be involved in the modulation of apomorphine-induced licking behavior.

  18. Structural modification of H/sub 2/-receptor antagonists provide post-H/sub 2/-receptor gastric antisecretory activity

    SciTech Connect

    Nielsen, S.T.; Dove, P.A.; Strike, D.P.; Schiehser, G.A.

    1986-03-01

    In the course of investigations into the gastric antisecretory activity of potential H/sub 2/-receptor antagonists, examples were discovered in which structural modification of the molecule altered a) antisecretory activity in the pylorus-ligated rat and b) the response to various stimulants of (/sup 14/C)aminopyrine (AP) uptake in isolated rat gastric mucosal cell preparations. Wy-45,662 (N-(3-(3-(1-piperidinylmethyl)phenoxy)propyl)thieno(3,4-d) isothiazol-3-amine 1, 1-dioxide)), a very potent histamine H/sub 2/-antagonist and antisecretory agent in the rat (ED/sub 50/ (approx.) 0.3 mg/kg), had no effect in vitro at 1 ..mu..M on forskolin-induced (/sup 14/C)AP uptake while 10 nM Wy-45,662 completely suppressed histamine-stimulated (/sup 14/C)AP uptake. In contrast, the N-benzylated form of Wy-45,662, Wy-46,499 dose-dependently (10/sup -7/-10/sup -6/M) suppressed forskolin-stimulated (/sup 14/C)AP uptake while retaining modest antisecretory activity (ED/sub 50/approx.8 mg/kg) in vivo. Wy-46,499's modest antisecretory activity was thus attributable to inhibition via a post-histamine H/sub 2/-receptor mechanism.

  19. 3-Acrylamide-4-aryloxyindoles: synthesis, biological evaluation and metabolic stability of potent and selective EP3 receptor antagonists.

    PubMed

    Zhou, Nian; Zeller, Wayne; Zhang, Jun; Onua, Emmanuel; Kiselyov, Alex S; Ramirez, Jose; Palsdottir, Gudrún; Halldorsdottir, Gudrún; Andrésson, Thornorkell; Gurney, Mark E; Singh, Jasbir

    2009-03-01

    A series of potent and selective EP(3) receptor antagonists are described. Utilizing a pharmacophore model developed for the EP(3) receptor, a series of 3,4-disubstituted indoles were found to be efficient ligands for this target. These compounds showed high selectivity over IP, FP and other EP receptors. An optimized molecule 7c featured a sound profile and potency in the functional rat and human platelet aggregation assays.

  20. In vitro metabolism studies of new adenosine A 2A receptor antagonists.

    PubMed

    Marucci, Gabriella; Finaurini, Sara; Buccioni, Michela; Lammi, Carmen; Kandhavelu, Meenakshisundaram; Volpini, Rosaria; Ricciutelli, Massimo; Angeli, Piero; Commandeur, Jan N M; Cristalli, Gloria

    2008-12-01

    Evidence, obtained in rodent and primate models of Parkinson's disease (PD) and in preliminary clinical trials, indicates that adenosine A(2A) receptor antagonists might represent a promising non-dopaminergic therapeutic tool for the treatment of PD. Recently, we have reported the biological evaluation of 8-substituted 9-ethyladenines (ANR) as new A(2A) receptor antagonists, three of which (ANR 82, ANR 94, and ANR 152) showed high efficacy in in vivo models for Parkinson's. Understanding the metabolic pathways of new drug candidates is an important aspect of drug discovery. The ANR compounds have been investigated in order to clarify their activity on rat liver microsomes, and more specifically on recombinant human cytochrome P450 2D6 (CYP2D6). The metabolites of all three compounds were detected by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The results indicate that this class of 9-ethyladenines is metabolized only to a fraction of 1.5-5%. These compounds also act as potent mechanism-based inhibitors of CYP450 and in particular of human isoform CYP2D6. Kinetic-analysis of enzyme inactivation was used to describe the effect of these time-dependent inhibitors and to derive the inhibition parameters K(inact) and K(i) defined with respect to the O-demethylation of dextromethorphan.

  1. New adenosine A2A receptor antagonists: actions on Parkinson's disease models.

    PubMed

    Pinna, Annalisa; Volpini, Rosaria; Cristalli, Gloria; Morelli, Micaela

    2005-04-11

    The 8-substituted 9-ethyladenine derivatives: 8-bromo-9-ethyladenine (ANR 82), 8-ethoxy- 9-ethyladenine (ANR 94), and 8-furyl-9-ethyladenine (ANR 152) have been characterized in vitro as adenosine receptor antagonists. Adenosine is deeply involved in the control of motor behaviour and substantial evidences indicate that adenosine A(2A) receptor antagonists improve motor deficits in animal models of Parkinson's disease. On this basis, the efficacy of ANR 82, ANR 94, and ANR 152 in rat models of Parkinson's disease was evaluated. All compounds tested reversed the catalepsy induced by haloperidol. However, in unilaterally 6-hydroxydopamine-lesioned rats, only ANR 94 and ANR 152 potentiated l-dihydroxy-phenylalanine (l-DOPA) effect on turning behaviour and induced contralateral turning behaviour in rats sensitised to l-DOPA. Taken together the results of this study indicate that some 8-substituted 9-ethyladenine derivatives ameliorate motor deficits in rat models of Parkinson's disease, suggesting a potential therapeutic role of these compounds.

  2. The dopamine D3 receptor antagonist, SR 21502, facilitates extinction of cocaine conditioned place preference

    PubMed Central

    Galaj, E.; Haynes, J.; Nisanov, R.; Ananthan, S.; Ranaldi, R.

    2015-01-01

    Background Pharmacotherapeutic agents that could facilitate extinction of cocaine cues would be useful in the treatment of cocaine addiction. We tested whether SR 21502, selective dopamine (DA) D3 receptor antagonist, can facilitate extinction of cocaine conditioned place preference (CPP) in rats. Methods In experiment 1, cocaine (10 mg/kg) CPP was first established and then extinguished. During the extinction phase the rats were injected with SR 21502 and placed in the previously cocaine-paired compartment for four sessions and vehicle in the other compartment on four alternating sessions. The rats were then tested again for cocaine CPP. In experiment 2, different groups of rats were trained to associate SR 21502 to one compartment and saline to the other. Results In Experiment 1, the animals spent significantly more time in the cocainepaired compartment after cocaine conditioning than they did before conditioning. Subsequently, the animals treated with SR 21502 during the extinction phase spent significantly less time in the cocaine-paired compartment than the vehicle group. In experiment 2, animals conditioned with SR 21502 preferred neither side of the CPP apparatus, indicating that SR 21502 produced no effects of its own. Conclusions These findings suggest that treatment with SR 21502, a DA D3 receptor antagonist, in the presence of cocaine cues can facilitate extinction of cocaine CPP and further suggest that this compound might be an effective cocaine addiction treatment. PMID:26710978

  3. Cysteinyl leukotriene receptor-1 antagonists as modulators of innate immune cell function.

    PubMed

    Theron, A J; Steel, H C; Tintinger, G R; Gravett, C M; Anderson, R; Feldman, C

    2014-01-01

    Cysteinyl leukotrienes (cysLTs) are produced predominantly by cells of the innate immune system, especially basophils, eosinophils, mast cells, and monocytes/macrophages. Notwithstanding potent bronchoconstrictor activity, cysLTs are also proinflammatory consequent to their autocrine and paracrine interactions with G-protein-coupled receptors expressed not only on the aforementioned cell types, but also on Th2 lymphocytes, as well as structural cells, and to a lesser extent neutrophils and CD8(+) cells. Recognition of the involvement of cysLTs in the immunopathogenesis of various types of acute and chronic inflammatory disorders, especially bronchial asthma, prompted the development of selective cysLT receptor-1 (cysLTR1) antagonists, specifically montelukast, pranlukast, and zafirlukast. More recently these agents have also been reported to possess secondary anti-inflammatory activities, distinct from cysLTR1 antagonism, which appear to be particularly effective in targeting neutrophils and monocytes/macrophages. Underlying mechanisms include interference with cyclic nucleotide phosphodiesterases, 5'-lipoxygenase, and the proinflammatory transcription factor, nuclear factor kappa B. These and other secondary anti-inflammatory mechanisms of the commonly used cysLTR1 antagonists are the major focus of the current review, which also includes a comparison of the anti-inflammatory effects of montelukast, pranlukast, and zafirlukast on human neutrophils in vitro, as well as an overview of both the current clinical applications of these agents and potential future applications based on preclinical and early clinical studies.

  4. Antagonist of GH-releasing hormone receptors alleviates experimental ocular inflammation

    PubMed Central

    Qin, Yong Jie; Chan, Sun On; Chong, Kelvin Kam Lung; Li, Benjamin Fuk Loi; Ng, Tsz Kin; Yip, Yolanda Wong Ying; Chen, Haoyu; Zhang, Mingzhi; Block, Norman L.; Cheung, Herman S.; Schally, Andrew V.; Pang, Chi Pui

    2014-01-01

    Disruptions in immunity and occurrence of inflammation cause many eye diseases. The growth hormone-releasing hormone–growth hormone–insulin-like growth factor-1 (GHRH–GH–IGF1) axis exerts regulatory effects on the immune system. Its involvement in ocular inflammation remains to be investigated. Here we studied this signaling in endotoxin-induced uveitis (EIU) generated by LPS. The increase in GHRH receptor (GHRH-R) protein levels was parallel to the increase in mRNA levels of pituitary-specific transcription factor-1, GHRH-R splice variant 1, GHRH, and GH following LPS insult. Elevation of GHRH-R and GH receptor was localized on the epithelium of the iris and ciliary body, and GHRH-R was confined to the infiltrating macrophages and leukocytes in aqueous humor but not to those in stroma. Treatment with GHRH-R antagonist decreased LPS-stimulated surges of GH and IGF1 in aqueous humor and alleviated inflammation by reducing the infiltration of macrophages and leukocytes and the production of TNF-α, IL-1β, and monocyte chemotactic protein-1. Our results indicate that inflammation in the iris and ciliary body involves the activation of GHRH signaling, which affects the recruitment of immune cells and the production of proinflammatory mediators that contribute to EIU pathogenesis. Moreover, the results suggest that GHRH-R antagonists are potential therapeutic agents for the treatment of acute ocular inflammation. PMID:25489106

  5. A novel calcium-sensing receptor antagonist transiently stimulates parathyroid hormone secretion in vivo.

    PubMed

    Arey, Brian J; Seethala, Ramakrishna; Ma, Zhengping; Fura, Aberra; Morin, Jennifer; Swartz, Joann; Vyas, Viral; Yang, Wu; Dickson, John K; Feyen, Jean H M

    2005-04-01

    Circulating calcium (Ca(2+)) is a primary regulator of bone homeostasis through its action on PTH secretion. Extracellular Ca(2+) modulates PTH secretion through a cell surface G protein-coupled receptor, the calcium-sensing receptor (CaR). The expression of the CaR suggests a critical role in cellular regulation by calcium in various organs, including parathyroid gland, bone, and kidney. Despite an obvious pharmacological utility for CaR antagonists in the treatment of disease, only a limited number of such classes of compounds exist. We have identified a novel class of small molecules with specific activity at the CaR. This class of compounds is represented by compound 1. It possesses potent antagonist activity at the human CaR with IC(50) values of 64 nm and 230 nm in inhibiting intracellular Ca(2+) flux and inositol phosphate generation in vitro, respectively. When administered to male rats in vivo, compound 1 robustly increased serum PTH levels. The stimulation of PTH secretion was rapid and transient when administered either iv or orally. The pharmacokinetic profile of compound 1 after oral administration revealed that maximal plasma levels of compound were reached within 1 h and the half-life of the compound to be approximately 2 h in rats. These data describe a representative compound of a novel chemical class than previously described allosteric modulators that offer a new avenue for the development of improved treatments of osteoporosis.

  6. JMV641: a potent bombesin receptor antagonist that inhibits Swiss 3T3 cell proliferation.

    PubMed

    Azay, J; Gagne, D; Devin, C; Llinares, M; Fehrentz, J A; Martinez, J

    1996-08-27

    The peptides of the bombesin family are involved in stimulation of mitogenesis in various cell lines, including cancerous cell lines. Bombesin receptor antagonists are of great interest to inhibit this proliferation. We have synthesized a potent bombesin receptor antagonist, e.g., compound JMV641 [H-DPhe-Gln-Trp-Ala-Val-Gly-His-NH-*CH[CH2-CH(CH3)2]-**CHOH- (CH2)3-CH3 [*(S); **92% of (S) isomer], in which a pseudopeptide bond mimicking the transition state analogue replaced the peptide bond between the two C-terminal residues. This compound was highly potent to dose-dependently inhibit binding of 125I-GRP to Swiss 3T3 cells (IC50 = 0.85 +/- 0.15 nM) and bombesin-stimulated Swiss 3T3 proliferation (pA2 = 8.78). However, compound JMV641 can inhibit bombesin-induced AP-1 regulated genes that are nuclear messengers mediating the actions of signal transduction pathways stimulated by growth factors.

  7. Identification of Darmstoff analogs as selective agonists and antagonists of lysophosphatidic acid receptors.

    PubMed

    Gududuru, Veeresa; Zeng, Kui; Tsukahara, Ryoko; Makarova, Natalia; Fujiwara, Yuko; Pigg, Kathryn R; Baker, Daniel L; Tigyi, Gabor; Miller, Duane D

    2006-01-15

    Darmstoff describes a family of gut smooth muscle-stimulating acetal phosphatidic acids initially isolated and characterized from the bath fluid of stimulated gut over 50 years ago. Despite similar structural and biological profiles, Darmstoff analogs have not previously been examined as potential LPA mimetics. Here, we report a facile method for the synthesis of potassium salts of Darmstoff analogs. To understand the effect of stereochemistry on lysophosphatidic acid mimetic activity, synthesis of optically pure stereoisomers of selected Darmstoff analogs was achieved starting with chiral methyl glycerates. Each Darmstoff analog was evaluated for subtype-specific LPA receptor agonist/antagonist activity, PPARgamma activation, and autotaxin inhibition. From this study we identified compound 12 as a pan-antagonist and several pan-agonists for the LPA(1-3) receptors. Introduction of an aromatic ring in the lipid chain such as analog 22 produced a subtype-specific LPA(3) agonist with an EC(50) of 692 nM. Interestingly, regardless of their LPA(1/2/3) ligand properties all of the Darmstoff analogs tested activated PPARgamma. However, these compounds are weak inhibitors of autotaxin. The results indicate that Darmstoff analogs constitute a novel class of lysophosphatidic acid mimetics.

  8. Reversal of trauma-induced amnesia in mice by a thrombin receptor antagonist.

    PubMed

    Itzekson, Zeev; Maggio, Nicola; Milman, Anat; Shavit, Efrat; Pick, Chaim G; Chapman, Joab

    2014-05-01

    Minimal traumatic brain injury (mTBI) is associated with the existence of retrograde amnesia and microscopic bleeds containing activated coagulation factors. In an mTBI model, we report that thrombin induces amnesia through its receptor protease-activated receptor 1 (PAR-1). Thrombin activity was significantly elevated (32 %, p < 0.05) 5 min following mTBI compared to controls. Amnesia was assessed by the novel object recognition test in mTBI animals and in animals injected intracerebroventricularly (ICV) with either thrombin or a PAR-1 agonist 1 h after the acquisition phase. Saline-injected controls had a preference index of over 0.3 while mTBI animals and those injected with thrombin or the PAR-1 agonist spent equal time with both objects indicating no recall of the object presented to them 24 h previously (p < 0.05). Co-injecting a PAR-1 antagonist (SCH79797) completely blocked the amnestic effects of mTBI, thrombin, and the PAR-1 agonist. Long-term potentiation, measured in hippocampal slices 24 h after mTBI, ICV thrombin or the PAR-1 agonist, was significantly impaired and this effect was completely reversed by the PAR-1 antagonist. The results support a crucial role for PAR-1 in the generation of amnesia following mTBI, revealing a novel therapeutic target for the cognitive effects of brain trauma.

  9. GLP-1 receptor antagonist as a potential probe for pancreatic {beta}-cell imaging

    SciTech Connect

    Mukai, Eri; Toyoda, Kentaro; Kimura, Hiroyuki; Kawashima, Hidekazu; Fujimoto, Hiroyuki; Ueda, Masashi; Temma, Takashi; Hirao, Konomu; Nagakawa, Kenji; Saji, Hideo; Inagaki, Nobuya

    2009-11-20

    We examined exendin(9-39), an antagonist of glucagon-like peptide-1 (GLP-1) receptor (GLP-1R), as a potential probe for imaging of pancreatic {beta}-cells. To evaluate in vitro receptor specificity, binding assay was performed using dispersed mouse islet cells. Binding assay showed competitive inhibition of [{sup 125}I]BH-exendin(9-39) binding by non-radioactive exendin(9-39). To assess in vivo selectivity, the biodistribution was evaluated by intravenous administration of [{sup 125}I]BH-exendin(9-39) to mice. Radioactivity of harvested pancreas reached highest levels at 60 and 120 min among organs examined except lung. Pre-administration of excess non-radioactive exendin(9-39) remarkably and specifically blocked the radioactivity of pancreas. After [{sup 125}I]BH-exendin(9-39) injection into transgenic mice with pancreatic {beta}-cells expressing GFP, fluorescent and radioactive signals of sections of pancreas were evaluated with an image analyzer. Imaging analysis showed that the fluorescent GFP signals and the radioactive signals were correspondingly located. Thus, the GLP-1R antagonist exendin(9-39) may serve as a useful probe for pancreatic {beta}-cell imaging.

  10. Interleukin-1 receptor antagonist gene polymorphism and mortality in patients with severe sepsis

    PubMed Central

    ARNALICH, F; LÓPEZ-MADERUELO, D; CODOCEO, R; LOPEZ, J; SOLIS-GARRIDO, L M; CAPISCOL, C; FERNANDEZ-CAPITÁN, C; MADERO, R; MONTIEL, C

    2002-01-01

    This study aims to determine the influence of the polymorphism within the intron 2 of the interleukin-1 receptor antagonist gene (IL-1RN*) on the outcome of severe sepsis, and to assess its functional significance by correlating this polymorphism with the total production of interleukin-1 receptor antagonist (IL-1Ra) protein determined in stimulated peripheral blood mononuclear cells (PBMC). A group of 78 patients with severe sepsis (51 survivors and 27 nonsurvivors) was compared with a healthy control group of 130 blood donors, and 56 patients with uncomplicated pneumonia. We found a significant association between IL-1RN* polymorphism and survival. Thus, after adjusting for age and APACHE II score, multiple logistic regression analysis showed that patients homozygotes for the allele *2 had a 6·47-fold increased risk of death (95% CI 1·01–41·47, P = 0·04). Besides, compared with patients homozygous or heterozygous for the allele *1, IL-1RN*2 homozygotes produced significantly lower levels of IL-1Ra from their PBMC. Our results suggest that insufficient production of this cytokine might contribute, among other factors, to the higher mortality rate found in severe sepsis patients with the IL-1RN*2 homozygous genotype. PMID:11876758

  11. Response to IL-1-receptor antagonist in a child with familial cold autoinflammatory syndrome.

    PubMed

    O'Connell, Susan M; O'Regan, Grainne M; Bolger, Turlough; Hoffman, Hal M; Cant, Andrew; Irvine, Alan D; Watson, Rosemarie M

    2007-01-01

    Familial cold auto-inflammatory syndrome, Muckle-Wells syndrome and chronic infantile neurologic, cutaneous, articular syndrome are related disorders associated with mutations in the CIAS1 gene. They appear to represent a continuum of one disease characterized by IL-1-mediated inflammation. Until recently, these conditions have been difficult to treat; however, with the advent of IL-1-receptor antagonist therapy, many reports of successful treatment of patients with these autoinflammatory diseases have emerged in the past 2 years. We describe an 8-year-old girl, diagnosed with Familial cold auto-inflammatory syndrome, confirmed by presence of a novel CIAS1 mutation, who was refractory to symptomatic treatment. As frequent attacks of urticaria and associated arthralgia had a debilitating effect on the child's lifestyle, a trial of IL-1-receptor antagonist (anakinra) was instituted. Dramatic sustained clinical improvement was evident within days and serum amyloid and C-reactive protein levels normalized within a month. Although several authors have reported successful use of this agent in children with chronic infantile neurologic, cutaneous, articular syndrome, we believe ours is the first report of successful treatment with anakinra in a young child with familial cold auto-inflammatory syndrome.

  12. Enhancement of alcohol-induced hypoglycaemia by H2-receptor antagonists.

    PubMed

    Czyzyk, A; Lao, B; Szutowski, M; Szczepanik, Z; Muszyński, J

    1997-06-01

    The oral ethanol loading test (0.5 g/kg body mass) was carried out in 3 groups with 10 healthy male volunteers each before and after 7 days of administration of either cimetidine (CAS 51481-61-9), ranitidine (CAS 66357-59-3), or famotidine (CAS 76824-35-6). The parameters determined during 6 h comprised the blood levels of ethanol, acetaldehyde, glucose, lactate, pyruvate and bicarbonates, as well as blood pH, PCO2 and PO2. Only ranitidine significantly increased the mean blood ethanol concentration and none of the drugs modified the blood acetaldehyde concentration. Hypoglycaemia following alcohol ingestion was significantly enhanced by all H2-receptor antagonists, but was most pronounced after famotidine. The alcohol-induced rise in blood pyruvate and lactate rather had a tendency to decrease during the second test. The presented results suggest that the evident enhancement of alcohol-induced hypoglycaemia by H2-receptor antagonists is not dependent on the increase of ethanol absorption from the gastrointestinal tract, but represents rather a specific effect of these drugs on glucose metabolism.

  13. Studying the binding interactions of allosteric agonists and antagonists of the CXCR4 receptor.

    PubMed

    Planesas, Jesús M; Pérez-Nueno, Violeta I; Borrell, José I; Teixidó, Jordi

    2015-07-01

    Several examples of allosteric modulators of GPCRs have been reported recently in the literature, but understanding their molecular mechanism presents a new challenge for medicinal chemistry. For the specific case of the cellular receptor CXCR4, it is known that pepducins (lipidated fragments of intracellular GPCR loops) such as ATI-2341 modulate CXCR4 activity agonistically via an allosteric mechanism. Moreover, there are also examples of small organic molecules such as AMD11070 and GSK812397 which may also act as allosteric antagonists. However, incomplete knowledge of the ligand-binding sites has hampered a detailed molecular understanding of how these inhibitors work. Here, we attempt to answer this question by analysing the binding interactions between the CXCR4 receptor and the above-mentioned allosteric modulators. We propose two different allosteric binding sites, one located in the intracellular loops 1, 2 and 3 (ICL1, ICL2 and ICL3) which binds the pepducin agonist ATI-2341, and the other at a subsite of the main extracellular orthosteric binding pocket between extracellular loops 1 and 2 and the N-terminus, which binds the antagonists AMD11070 and GSK812397. Allosteric interactions between the CXCR4 and ATI-2341 were predicted by combining different modeling approaches. First, a rotational blind docking search was applied and the best poses were subsequently refined using flexible docking methods and molecular dynamic simulations. For the AMD11070 and GSK812397 antagonists, the entire CXCR4 protein surface was explored by blind docking in order to define the binding region. A second docking analysis by subsites was then performed to refine the allosteric interactions. Finally, we identified the binding residues that appear to be essential for CXCR4 allosteric modulators.

  14. Decreasing nicotinic receptor activity and the spatial learning impairment caused by the NMDA glutamate antagonist dizocilpine in rats

    PubMed Central

    Burke, Dennis A.; Heshmati, Pooneh; Kholdebarin, Ehsan; Levin, Edward D.

    2014-01-01

    Nicotinic systems have been shown by a variety of studies to be involved in cognitive function. Nicotinic receptors have an inherent property to become desensitized after activation. The relative role of nicotinic receptor activation vs. net receptor inactivation by desensitization in the cognitive effects of nicotinic drugs remains to be fully understood. In these studies, we tested the effects of the α7 nicotinic receptor antagonist methyllycaconitine (MLA), the α4β2 nicotinic receptor antagonist dihydro-β-erythroidine (DHβE), the nonspecific nicotinic channel blocker mecamylamine and the α4β2 nicotinic receptor desensitizing agent sazetidine-A on learning in a repeated acquisition test. Adult female Sprague-Dawley rats were trained on a repeated acquisition learning procedure in an 8-arm radial maze. MLA (1–4 mg/kg), DHβE (1–4 mg/kg), mecamylamine (0.125–0.5 mg/kg) or sazetidine-A (1 and 3 mg/kg) were administered in four different studies either alone or together with the NMDA glutamate antagonist dizocilpine (0.05 and 0.10 mg/kg). MLA significantly counteracted the learning impairment caused by dizocilpine. The overall choice accuracy impairment caused by dizocilpine was significantly attenuated by co-administration of DHβE. Low doses of the non-specific nicotinic antagonist mecamylamine also reduced dizocilpine-induced repeated acquisition impairment. Sazetidine-A reversed the accuracy impairment caused by dizocilpine. These studies provide evidence that a net decrease in nicotinic receptor activity can improve learning by attenuating learning impairment induced by NMDA glutamate blockade. This adds to evidence in cognitive tests that nicotinic antagonists can improve cognitive function. Further research characterizing the efficacy and mechanisms underlying nicotinic antagonist and desensitization induced cognitive improvement is warranted. PMID:25064338

  15. A2A receptor antagonists do not induce dyskinesias in drug-naive or L-dopa sensitized rats.

    PubMed

    Jones, N; Bleickardt, C; Mullins, D; Parker, E; Hodgson, R

    2013-09-01

    L-dopa, the precursor to dopamine, is currently the gold standard treatment for Parkinson's disease (PD). However, chronic exposure is associated with L-dopa-induced dyskinesias (LIDs), a serious side effect characterized by involuntary movements. Adenosine A2A receptor antagonists have been studied as a novel non-dopaminergic PD treatment. Because A2A receptor antagonists do not act on dopamine receptors, it has been hypothesized that they will not induce dyskinesias characteristic of L-dopa. To test this hypothesis in a rodent model, the A2A receptor antagonists SCH 412348 (3 mg/kg), vipadenant (10 mg/kg), caffeine (30 mg/kg), or istradefylline (3 mg/kg) were chronically (19-22 days) administered to Sprague Dawley rats, and dyskinetic behaviors were scored across this chronic dosing paradigm. Unlike L-dopa, there was no evidence of dyskinetic activity resulting from any of the four A2A receptor antagonists tested. When delivered to animals previously sensitized with L-dopa (6 mg/kg), SCH 412348, vipadenant, caffeine or istradefylline treatment produced no dyskinesias. When administered in combination with L-dopa (6 mg/kg), SCH 412348 (3 mg/kg) neither exacerbated nor prevented the induction of LIDs over the course of 19 days of treatment. Collectively, our data indicate that A2A receptor antagonists are likely to have a reduced dyskinetic liability relative to L-dopa but do not block dyskinesias when coadministered with L-dopa. Clinical studies are required to fully understand the dyskinesia profiles of A2A receptor antagonists.

  16. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs.

    PubMed

    Pediani, John D; Ward, Richard J; Godin, Antoine G; Marsango, Sara; Milligan, Graeme

    2016-06-17

    Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm(-2) human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior.

  17. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs*

    PubMed Central

    Pediani, John D.; Ward, Richard J.; Godin, Antoine G.; Marsango, Sara

    2016-01-01

    Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm−2 human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior. PMID:27080256

  18. Synergistic antiemetic interactions between serotonergic 5-HT3 and tachykininergic NK1-receptor antagonists in the least shrew (Cryptotis parva).

    PubMed

    Darmani, Nissar A; Chebolu, Seetha; Amos, Barry; Alkam, Tursun

    2011-10-01

    Significant electrophysiological and biochemical findings suggest that receptor cross-talk occurs between serotonergic 5-HT(3)- and tachykininergic NK(1)-receptors in which co-activation of either receptor by ineffective doses of their corresponding agonists (serotonin (5-HT) or substance P (SP), respectively) potentiates the activity of the other receptor to produce a response. In contrast, selective blockade of any one of these receptors attenuates the increase in abdominal vagal afferent activity caused by either 5-HT or SP. This interaction has important implications in chemotherapy-induced nausea and vomiting (CINV) since 5-HT(3)- and NK(1)-receptor antagonists are the major classes of antiemetics used in cancer patients receiving chemotherapy. The purpose of this study was to demonstrate whether the discussed interaction produces effects at the behavioral leve