Radioprotective effects of cimetidine on rats irradiated by long-term, low-dose-rate neutrons and 60Co γ-rays.

PubMed

Jiang, Ding-Wen; Wang, Qing-Rong; Shen, Xian-Rong; He, Ying; Qian, Tian-Tian; Liu, Qiong; Hou, Deng-Yong; Liu, Yu-Ming; Chen, Wei; Ren, Xin; Li, Ke-Xian

2017-01-01

Cimetidine, an antagonist of histamine type II receptors, has shown protective effects against γ-rays or neutrons. However, there have been no reports on the effects of cimetidine against neutrons combined with γ-rays. This study was carried out to evaluate the protective effects of cimetidine on rats exposed to long-term, low-dose-rate neutron and γ-ray combined irradiation (n-γ LDR). Fifty male Sprague-Dawley (SD) rats were randomly divided into 5 groups: the normal control group, radiation model group, 20 mg/(kg · d) cimetidine group, 80 mg/(kg · d) cimetidine group and 160 mg/(kg · d) cimetidine group (10 rats per group). Except for the normal control group, 40 rats were simultaneously exposed to fission neutrons ( 252 Cf, 0.085 mGy/h) for 22 h every day and γ-rays ( 60 Co, 0.097 Gy/h) for 1.03 h once every three days, and the cimetidine groups were administered intragastrically with cimetidine at doses of 20, 80 and 160 mg/kg each day. Peripheral blood WBC of the rats was counted the day following exposure to γ-rays. The rats were anesthetized and sacrificed on the day following exposure to 252 Cf for 28 days. The spleen, thymus, testicle, liver and intestinal tract indexes were evaluated. The DNA content of bone marrow cells and concanavalin A (ConA)-induced lymphocyte proliferation were measured. The frequency of micronuclei in polychromatic erythrocytes (fMNPCEs), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in the serum and liver tissues were detected. The peripheral blood WBC in the cimetidine groups was increased significantly on the 8th day and the 26th day compared with those in the radiation model group. The spleen, thymus and testicle indexes of the cimetidine groups were higher than those of the radiation model group. The DNA content of bone marrow cells and lymphocyte proliferation in the cimetidine groups were increased significantly, and fMNPCE was reduced 1.41-1.77 fold in cimetidine treated groups. The activities of SOD and GSH-Px in the cimetidine groups were increased significantly, and the content of MDA in the cimetidine groups was decreased significantly. The results suggested that cimetidine alleviated damage induced by long-term, low-dose-rate neutron and γ combined irradiation via antioxidation and immunomodulation. Cimetidine might be useful as a potent radioprotector for radiotherapy patients as well as for occupational exposure workers.

Hepatoprotective, antinociceptive and antioxidant activities of cimetidine, ranitidine and famotidine as histamine H2 receptor antagonists.

PubMed

Ahmadi, Amirhossein; Ebrahimzadeh, Mohammad Ali; Ahmad-Ashrafi, Saeb; Karami, Mohammad; Mahdavi, Mohammad Reza; Saravi, Seyed Soheil Saeedi

2011-02-01

The antioxidant, antinociceptive and hepatoprotective effects of H(2) receptor blockers were examined with different experimental models. Antioxidant activities were determined by employing various in vitro assay systems such as 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical-scavenging activity assays, reducing power determination assays, nitric oxide-scavenging activity assays and hydrogen peroxide-scavenging activity assays. Antinociceptive effects were determined using the hot plate test in mice. The hepatoprotective effects of cimetidine, ranitidine and famotidine against hepatotoxicity induced by carbon tetrachloride (CCl(4) ) were determined by measuring the levels of serum enzymes alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) activities in mice. We found that the IC(50) values of cimetidine, ranitidine and famotidine on DPPH radical-scavenging activity were 671±28, 538±21 and 955±43 μg/mL, respectively. Famotidine showed very strong nitric oxide-scavenging activity. All three compounds showed very weak hydrogen peroxide-scavenging activity. Moreover, the compounds did not exhibit any reducing power activity until concentrations of 1.6 mg/mL. All compounds also showed a dose-dependent and marked analgesic activity in mice relative to controls. Pretreatment of mice with cimetidine, ranitidine or famotidine for three consecutive days reduced CCl(4)-induced hepatotoxicity in mice. Treatment with 200 mg/kg ranitidine reduced AST, AST and ALP serum levels, while 200 and 40 mg/kg of cimetidine and famotidine, respectively, reduced AST and ALP serum levels. H(2) blockers exhibited varying levels of antioxidant activities in various assays. Our results indicate that the antioxidant activities of H(2) blockers have an analgesic activity and protective effect on CCl(4)-induced hepatotoxicity in mice. These effects were greater with ranitidine than with the other compounds. © 2010 The Authors Fundamental and Clinical Pharmacology © 2010 Société Française de Pharmacologie et de Thérapeutique.

Histaminergic Receptors Modulate Spinal Cord Injury-Induced Neuronal Nitric Oxide Synthase Upregulation and Cord Pathology: New Roles of Nanowired Drug Delivery for Neuroprotection.

PubMed

Sharma, Hari S; Patnaik, Ranjana; Muresanu, Dafin F; Lafuente, José V; Ozkizilcik, Asya; Tian, Z Ryan; Nozari, Ala; Sharma, Aruna

2017-01-01

The possibility that histamine influences the spinal cord pathophysiology following trauma through specific receptor-mediated upregulation of neuronal nitric oxide synthase (nNOS) was examined in a rat model. A focal spinal cord injury (SCI) was inflicted by a longitudinal incision into the right dorsal horn of the T10-11 segments. The animals were allowed to survive 5h. The SCI significantly induced breakdown of the blood-spinal cord barrier to protein tracers, reduced the spinal cord blood flow at 5h, and increased the edema formation and massive upregulation of nNOS expression. Pretreatment with histamine H1 receptor antagonist mepyramine (1mg, 5mg, and 10mg/kg, i.p., 30min before injury) failed to attenuate nNOS expression and spinal cord pathology following SCI. On the other hand, blockade of histamine H2 receptors with cimetidine or ranitidine (1mg, 5mg, or 10mg/kg) significantly reduced these early pathophysiological events and attenuated nNOS expression in a dose-dependent manner. Interestingly, TiO 2 -naowire delivery of cimetidine or ranitidine (5mg doses) exerted superior neuroprotective effects on SCI-induced nNOS expression and cord pathology. It appears that effects of ranitidine were far superior than cimetidine at identical doses in SCI. On the other hand, pretreatment with histamine H3 receptor agonist α-methylhistamine (1mg, 2mg, or 5mg/kg, i.p.) that inhibits histamine synthesis and release in the central nervous system thwarted the spinal cord pathophysiology and nNOS expression when used in lower doses. Interestingly, histamine H3 receptor antagonist thioperamide (1mg, 2mg, or 5mg/kg, i.p.) exacerbated nNOS expression and cord pathology after SCI. These novel observations suggest that blockade of histamine H2 receptors or stimulation of histamine H3 receptors attenuates nNOS expression and induces neuroprotection in SCI. Taken together, our results are the first to demonstrate that histamine-induced pathophysiology of SCI is mediated via nNOS expression involving specific histamine receptors. © 2017 Elsevier Inc. All rights reserved.

FT-IR and FT-Raman spectra of cimetidine and its metallocomplexes

NASA Astrophysics Data System (ADS)

Barańska, M.; Proniewicz, L. M.

1999-11-01

We present vibrational spectra of three stable, well-reproducible, polymorphic forms of cimetidine ( cim), a drug which is a powerful histamine H 2-receptor antagonist used in the treatment of peptic ulcer and the Zollinger-Ellison syndrome. Assignments of Raman and IR bands are made using semiempirical methods: MNDO, AM1 and PM3. We also describe the synthesis of Me( cim) 2(ClO 4) 2, where Me=Cu(II), Cd(II), Co(II) and Ni(II), and present their vibrational data. We show that the obtained complexes are isostructural, however a metal ion that occupies a center of octahedral unit introduces some distortions that can be seen in the spectra. We also make tentative assignment of metal-ligand stretching modes observed in low frequency range.

Hypothermic and antipyretic effects of ACTH (1-24) and alpha-melanotropin in guinea-pigs

NASA Technical Reports Server (NTRS)

Kandasamy, S. B.; Williams, B. A.

1984-01-01

Intracerebroventricular administration of adrenocorticotropin (ACTH 1-24) and alpha-melanotropin (alpha-MSH), peptides which occur naturally in brain induced dose-related hypothermia in guinea-pigs at room temperature (21 C) and also produced greater hypothermia at low (10 C) ambient temperature. However, when the experiments were repeated in a warm (30 C) environment, no effect on body temperature was observed. These results indicate that the peptides did not reduce the central set-point of temperature control. The hypothermia induced by ACTH and alpha-MSH was not mediated via histamine H1- or H2-receptors and serotonin since the H1-receptor antagonist, mepyramine, the H2-receptor antagonist, cimetidine, and the serotonin antagonist, methysergide, had no antagonistic effects. The peptides were antipyretic since they reduced pyrogen-induced-fever and hyperthermia due to prostaglandin E2, norepinephrine and dibutyryl cAMP, at a dose which did not affect normal body temperature. The powerful central effects of these peptides on normal body temperature, fever and hyperthermia, together with their presence of the brain regions important to temperature control, suggest that they participate in thermoregulation.

Protective effect of lafutidine, a histamine H2 receptor antagonist, against loxoprofen-induced small intestinal lesions in rats.

PubMed

Amagase, Kikuko; Ochi, Akimu; Sugihara, Tetsuya; Kato, Shinichi; Takeuchi, Koji

2010-05-01

We examined the effect of lafutidine, a histamine H(2) receptor antagonist with a mucosal protective action mediated by capsaicin-sensitive sensory neurons (CSN), on intestinal lesions produced by loxoprofen administration in rats. Animals were given loxoprofen (10-100 mg/kg p.o.) and killed 24 h later. Lafutidine (10 and 30 mg/kg), cimetidine (100 mg/kg) or famotidine (30 mg/kg) was given twice p.o. at 0.5 h before and 6 h after loxoprofen. Omeprazole (100 mg/kg) was given p.o. once 0.5 h before. Ampicillin (800 mg/kg) was given p.o. twice at 24 h and 0.5 h before loxoprofen, while 16,16-dimethyl prostaglandin E(2) (dmPGE(2); 0.01 mg/kg) was given i.v. twice at 5 min before and 6 h after. Loxoprofen dose-dependently produced hemorrhagic lesions in the small intestine, accompanied by invasion of enterobacteria and increased inducible nitric oxide synthase (iNOS) expression as well as myeloperoxidase activity in the mucosa. The ulcerogenic response to loxoprofen (60 mg/kg) was significantly prevented by lafutidine (30 mg/kg), similar to dmPGE(2) and ampicillin, and the effect of lafutidine was totally attenuated by ablation of CSN. Neither cimetidine, famotidine nor omeprazole had a significant effect against these lesions. Lafutidine alone increased mucus secretion and reverted the decreased mucus response to loxoprofen, resulting in suppression of bacterial invasion and iNOS expression. In addition, loxoprofen downregulated Muc2 expression, and this response was totally reversed by lafutidine mediated by CSN. Lafutidine protects the small intestine against loxoprofen-induced lesions, essentially mediated by the CSN, and this effect may be functionally associated with increased Muc2 expression/mucus secretion, an important factor in the suppression of bacterial invasion.

Twice-daily cimetidine does not increase gastric bacterial flora.

PubMed Central

Bourne, J. T.; Mountford, R. A.; Barry, R. E.

1984-01-01

Thirty patients with peptic ulcer (20 duodenal, 10 gastric) underwent glucose-hydrogen (H2) breath tests before and after 6 weeks treatment with cimetidine, 400 mg twice daily. For the group as a whole, basal breath H2 and integrated H2 output over a 2.5 hr test period was unchanged by cimetidine treatment. We conclude that there was no evidence of significant gastric bacterial colonization following twice daily cimetidine treatment. PMID:6462995

Cimetidine (Tagamet) is a reproductive toxicant in male rats affecting peritubular cells.

PubMed

França, L R; Leal, M C; Sasso-Cerri, E; Vasconcelos, A; Debeljuk, L; Russell, L D

2000-11-01

Cimetidine (Tagamet) is a potent histaminic H2-receptor antagonist, extensively prescribed for ulcers and now available without prescription. Cimetidine is a known testicular toxicant, but its mechanism of action remains uncertain. Rats were treated i.p. with cimetidine either at 50 mg/kg or 250 mg/kg body weight for 59 days. Accessory sex organ weights, but not testis weight, were significantly reduced in the high dose treated groups. FSH levels were significantly elevated in both treated groups, but testosterone levels were unchanged. A high degree of variability characterized testis histology, with most tubules appearing normal and some tubules (15-17%) partially lacking or devoid of germ cells. Morphometry showed that although seminiferous tubule volume was not significantly changed, the volume of peritubular tissue was reduced in the high dose group. There was extensive duplication of the basal lamina, lamina densa in both apparently normal spermatogenic tubules and severely damaged tubules. Apoptotic peritubular myoid cells were also found. TUNEL labeling confirmed extensive apoptotic cell death in peritubular cells, but revealed apoptosis of vascular smooth muscle. Given that 1) peritubular myoid cell apoptosis occurs in apparently normal tubules, that 2) basal lamina disorders are found, and that 3) peritubular cells are lost from the testis, it is suggested that the primary event in cimetidine-related damage is targeted to testicular smooth muscle cells. This is the first in vivo-administered toxicant to be described that targets myoid cells, resulting in abnormal spermatogenesis.

Histamine type 2 receptor antagonists as adjuvant treatment for resected colorectal cancer.

PubMed

Deva, Sanjeev; Jameson, Michael

2012-08-15

Anecdotal reports of tumour regression with histamine type 2 receptor antagonists (H(2)RAs) have lead to a series of trials with this class of drug as adjuvant therapy to try and improve outcomes in patients with resected colorectal cancers. There was a plausible scientific rationale suggesting merit in this strategy. This included improved immune surveillance (by way of increasing tumour infiltrating lymphocytes), inhibiting the direct proliferative effect of histamine as a growth factor for colorectal cancer and, in the case of cimetidine, inhibiting endothelial expression of E-selectin (a cell adhesion molecule thought to be critical for metastatic spread). To determine if H(2)RAs improve overall survival when used as pre- and/or postoperative therapy in colorectal cancer patients who have had surgical resection with curative intent. We also stratified the results to see if there was an improvement in overall survival in terms of the specific H(2)RA used. Randomised controlled trials were identified using a sensitive search strategy in the following databases: MEDLINE (1964 to present), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2009), EMBASE (1980 to present) and Cancerlit (1983 to present). Criteria for study selection included: patients with colorectal cancer surgically resected with curative intent; H(2)RAs used i) at any dose, ii) for any length of time, iii) with any other treatment modality and iv) in the pre-, peri- or post-operative period. The results were stratified for the H(2)RA used. The literature search retrieved 142 articles. There were six studies included in the final analysis, published from 1995 to 2007, including a total of 1229 patients. All patients were analysed by intention to treat according to their initial allocation. Log hazard ratios and standard errors of treatment effects (on overall survival) were calculated using the Cochrane statistical package RevMan Version 5. Hazard ratios and standard errors were recorded from trial publications or, if not provided, were estimated from published actuarial survival curves using a spreadsheet designed for this purpose (http://www.biomedcentral.com/content/supplementary/1745-6215-8-16-S1.xls). Of the six identified trials, five used cimetidine as the experimental H(2)RA, whereas one used ranitidine. There was a trend towards improved survival when H(2)RAs were utilised as adjuvant therapy in patients having curative-intent surgery for colorectal cancer (HR 0.70; 95% CI 0.48-1.03, P = 0.07). Analysis of the five cimetidine trials (n = 421) revealed a statistically significant improvement in overall survival (HR 0.53; 95% CI 0.32 to 0.87). Of the H(2)RAs evaluated cimetidine appears to confer a survival benefit when given as an adjunct to curative surgical resection of colorectal cancers. The trial designs were heterogeneous and adjuvant therapy has evolved since these trials were performed. Further prospective randomised studies are warranted.

Dose related in vitro effects of ranitidine and cimetidine on basal and ACTH-stimulated steroidogenesis.

PubMed Central

Kenyon, C J; Fraser, R; Birnie, G G; Connell, J M; Lever, A F

1986-01-01

Isolated bovine adrenocortical cells were incubated with and without 3 ng/ml ACTH, with various concentrations (10-1000 micrograms/ml) of either cimetidine or ranitidine. Cortisol, corticosterone, and deoxycorticosterone outputs were measured. Cimetidine and ranitidine at 320 and 1000 micrograms/ml inhibited ACTH-stimulated corticosterone and cortisol synthesis and cimetidine decreased basal cortisol synthesis. The inhibitory effects of cimetidine on cortisol synthesis were approximately 10 times greater than those of ranitidine. Cimetidine (1000 micrograms/ml), but not ranitidine increased deoxycorticosterone synthesis by ACTH-stimulated cells, indicating inhibition of 11 beta-hydroxylation in the adrenal steroidogenic pathway. Although doses of cimetidine and ranitidine which produce these in vitro effects are much greater than plasma concentrations in normal clinical use, they might be important in acutely ill patients given intravenous bolus injections of cimetidine, or if either antagonist were accumulated by the adrenal to produce high intracellular concentrations. PMID:3023203

H1- and H2-receptor characterization in the tracheal circulation of sheep.

PubMed Central

Webber, S. E.; Salonen, R. O.; Widdicombe, J. G.

1988-01-01

1. The effects of histamine, the specific H1-agonist SKF 71481-A2 and the H2-agonist dimaprit were examined on tracheal vascular resistance in sheep anaesthetized with pentobarbitone. Tracheal vascular resistance was determined by perfusing the cranial tracheal arteries at constant flows and measuring inflow pressures. Changes in tracheal smooth muscle tone were also measured. 2. Histamine and SKF 71481-A2 contracted the tracheal smooth muscle and this effect was blocked by the H1-antagonist mepyramine. Stimulation of H2-receptors with dimaprit had no effect on tracheal smooth muscle tone. 3. Histamine had a complex action on the tracheal vasculature producing either a triphasic change (early dilatation then constriction followed by late dilatation) or just a constriction. SKF 71481-A2 always produced a biphasic change in vascular resistance (dilatation followed by constriction). Dimaprit dilated the tracheal vasculature. 4. The late dilatation produced by histamine in some sheep was blocked by bilateral cervical vagotomy but the mechanism for this effect is not known. No other responses to histamine, SKF 71481-A2 or dimaprit were affected by vagotomy. 5. The vasoconstriction produced by histamine and SKF 71481-A2 was antagonized by mepyramine indicating a H1-receptor-mediated effect. Cimetidine had no effect on the vasoconstriction to histamine suggesting a lack of involvement of H2-receptors. 6. The vasodilatation produced by histamine and SKF 71481-A2 was also antagonized by mepyramine, again suggesting a H1-receptor-mediated action. Cimetidine had no effect on the vasodilator response to histamine indicating no involvement of H2-receptors in this response. 7. The dilator effect of dimaprit was antagonized by cimetidine suggesting this effect was mediated by H2-receptors. 8. We conclude that H1-receptors in the various parts of the sheep tracheal vasculature can cause increases and decreases in total tracheal vascular resistance; that H2-receptors decrease resistance; and that the tracheal smooth muscle contracts on activation of H1-receptors but has no response to H2-agonists. PMID:2906559

Third compartment ulcers in the llama.

PubMed

Smith, B B; Pearson, E G; Timm, K I

1994-07-01

The diagnosis of third compartment ulcers in the llama and alpaca is largely one of exclusion. Clinical signs may include mild to severe colic, inappetence, decreased fecal output, bruxism, and depression. Abdominocentesis results are usually unremarkable if C3 perforation has not occurred but reflective of a generalized peritonitis if full thickness ulceration has occurred. The H-2 receptor antagonists cimetidine and ranitidine do not suppress C3 acid production for a significant period of time and are of questionable efficacy in the management of C3 ulcers.

Topical Histamine Stimulates Repigmentation of Nonsegmental Vitiligo by a Receptor-Dependent Mechanism.

PubMed

Liu, Jun; Xu, Yan; Lin, Tzu-Kai; Lv, Chengzhi; Elias, Peter M; Man, Mao-Qiang

2017-01-01

Though vitiligo is a common depigmentary disorder, it still represents a substantial therapeutic challenge. Therapeutic options are limited in part due to its uncertain etiology. Because recent studies suggest that histamine stimulates melanogenesis in vitro, we determined here whether topical histamine stimulates repigmentation in patients with stable, nonsegmental vitiligo. A total of 23 otherwise normal volunteers with vitiligo, including 14 males and 9 females aged 6-59 years (mean age 29.2 ± 2.8), were enrolled in this study. 1% histamine in distilled water was applied to the lesions twice daily for 5 weeks, while comparable lesions, treated with distilled water alone, served as the controls. The melanin index was measured on the uninvolved and lesional skin sites before and after 5 weeks of treatments using the melanin/erythema probe connected to a Courage-Khazaka MPA5 (Cologne, Germany). Changes in epidermal permeability barrier were also assessed at the same time point. To determine whether histamine-induced repigmentation is receptor-dependent, both ears of C57BL/6J mice were treated topically with 5% cimetidine, a histamine type 2 receptor (H2r) antagonist, twice daily for 10 days. One hour after each cimetidine application, the right ear was treated topically with 10% histamine, while vehicle alone was applied to the left ear. Changes in melanin index were measured 24 h after the last application of histamine and vehicle as described in the human study. In patients with vitiligo treated with vehicle alone for 5 weeks, the melanin index remained unchanged, while topical histamine treatment increased the melanin index by 38% (p < 0.001 vs. both vehicle and pretreatment), which was paralleled by a >60% reduction in lesion surface area. Moreover, topical histamine accelerated permeability barrier recovery. No adverse events were observed following histamine applications. In mice, topical histamine significantly increased the melanin index, while topical co-applications of the H2r antagonist (cimetidine) prevented the expected histamine-induced increase in melanin index. These studies indicate that topical histamine or an H2r agonist could be useful for treating nonsegmental vitiligo, but further clinical studies in large populations will be required to validate the efficacy and safety of this approach. © 2017 S. Karger AG, Basel.

Lack of inhibitory effect of cimetidine on caffeine metabolism in children using the caffeine breath test

PubMed Central

Parker, A.C.; Pritchard, P.; Preston, T.; Dalzell, A.M.; Choonara, I.

1997-01-01

Aims To study the potential drug interaction between cimetidine and caffeine in a group of children who received cimetidine for gastritis. Methods The caffeine breath test was carried out prior to the administration of cimetidine and after 2–3 weeks therapy. The children (n=1) received 300–800 mg cimetidine daily (11–36 mg kg−1 day−1 ). Results There was no significant change in the 2 h cumulative labelled CO2 following the administration of cimetidine (mean values 5.61% before and 4.87% during cimetidine; Student’s t-test P >0.2). Conclusions Cimetidine did not have an inhibitory effect on the metabolism of caffeine in this group of children studied. PMID:9159560

Application of vibrational spectroscopy, thermal analyses and X-ray diffraction in the rapid evaluation of the stability in solid-state of ranitidine, famotidine and cimetidine.

PubMed

Jamrógiewicz, Marzena; Ciesielski, Aleksander

2015-03-25

This paper reports the study on applicability of Fourier transform infrared (FTIR), near-infrared (NIR) and Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) for the estimation of the chemical stability and photostability of histamine H2-receptor antagonist substances. Ranitidine hydrochloride (RAN), famotidine (FAM) and cimetidine (CIM) were tested and differences in sensitivity were measured via soft independence modeling of class analogies (Simca) model. The low values of variations for FAM and CIM and high variations obtained for RAN using FTIR and NIR techniques indicated that these methods were suitable and applicable to classify the degradation of RAN. Examined methods are recommendable in the first technological stage of drug production, and the preclinical and clinical development of pharmaceuticals or their quality control. Copyright © 2015 Elsevier B.V. All rights reserved.

The histaminergic system is involved in psychological stress-induced hyperthermia in rats.

PubMed

Lkhagvasuren, Battuvshin; Oka, Takakazu

2017-04-01

The histaminergic system modulates numerous physiological functions such as wakefulness, circadian rhythm, feeding, and thermoregulation. However, it is not yet known if this system is also involved in psychological stress-induced hyperthermia (PSH) and, if so, which histamine (H) receptor subtype mediates the effect. Therefore, we investigated the effects of pretreatments with intraperitoneal injections of mepyramine (an H1 receptor inverse agonist), cimetidine (an H2 receptor antagonist), and ciproxifan (an H3 receptor inverse agonist) on cage-exchange stress-induced hyperthermia (a model of PSH) by monitoring core body temperature ( T c ) during both light (10:00 am-12:00 pm) and dark (10:00 pm-12:00 am) phases in conscious, freely moving rats. We also investigated the effects of these drugs on stress-induced changes in locomotor activity ( L a ) to rule out the possibility that effects on T c are achieved secondary to altered L a Cage-exchange stress increased T c within 20 min followed by a gradual decrease back to baseline T c during both phases. In the light phase, mepyramine and cimetidine markedly attenuated PSH, whereas ciproxifan did not affect it. In contrast, in the dark phase, mepyramine dropped T c by 1 °C without affecting cage-exchange stress-induced hyperthermia, whereas cimetidine and ciproxifan did not affect both postinjection T c and PSH Cage-exchange stress induced an increase in L a , especially in the light phase, but none of these drugs altered cage-exchange stress-induced L a in either circadian rhythm phase. These results suggest that the histaminergic system is involved in the physiological mechanisms underlying PSH, particularly through H1 and H2 receptors, without influencing locomotor activity. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

The effect of compound 48/80 on contractions induced by toluene diisocyanate in isolated guinea-pig bronchus.

PubMed

Mapp, C E; Boniotti, A; Papi, A; Chitano, P; Coser, E; Di Stefano, A; Saetta, M; Ciaccia, A; Fabbri, L M

1993-06-01

We have investigated the ability of compound 48/80 and of histamine H1 and H2 receptor antagonists to inhibit toluene diisocyanate-induced contractions in isolated guinea-pig bronchi. Compound 48/80 (100 micrograms/ml) significantly inhibited toluene diisocyanate-induced contractions. By contrast, the two histamine H1 and H2 receptor antagonists, chlorpheniramine (10 microM) and cimetidine, (10 microM) did not affect toluene diisocyanate-induced contractions, but significantly inhibited contractions induced by exogenously applied histamine (100 microM) and by 48/80. We investigated which mechanisms 48/80 used to inhibit toluene diisocyanate-induced contractions, paying particular attention to the possible involvement of capsaicin-sensitive primary afferents. In vitro capsaicin desensitization (10 microM for 30 min followed by washing) significantly reduced compound 48/80-induced contractions. A capsaicin-resistant component of contraction was also evident. Ruthenium red (3 microM), an inorganic dye which acts as a selective functional antagonist of capsaicin, did not affect 48/80-induced contraction. MEN 10,207 (Tyr5,D-Trp6,8,9,Arg10)-neurokinin A (4-10) (3 microM) a selective antagonist of NK2-tachykinin receptors significantly reduced 48/80-induced contractions. These results show that compound 48/80 inhibits toluene diisocyanate-induced contractions in isolated guinea-pig bronchi. It is likely that two mechanisms are involved in the inhibition: (1) the release of mediators other than histamine by mast cells, (2) an effect of 48/80 on sensory nerves.

Fenspiride inhibits histamine-induced responses in a lung epithelial cell line.

PubMed

Quartulli, F; Pinelli, E; Broué-Chabbert, A; Gossart, S; Girard, V; Pipy, B

1998-05-08

Using the human lung epithelial WI26VA4 cell line, we investigated the capacity of fenspiride, an anti-inflammatory drug with anti-bronchoconstrictor properties, to interfere with histamine-induced intracellular Ca2+ increase and eicosanoid formation. Histamine and a histamine H1 receptor agonist elicited a rapid and transient intracellular Ca2+ increase (0-60 s) in fluo 3-loaded WI26VA4 cells. This response was antagonized by the histamine H1 receptor antagonist, diphenhydramine, the histamine H2 receptor antagonist, cimetidine, having no effect. Fenspiride (10(-7)-10(-5) M) inhibited the histamine H1 receptor-induced Ca2+ increase. In addition, histamine induced a biphasic increase in arachidonic acid release. The initial rise (0-30 s), a rapid and transient arachidonic acid release, was responsible for the histamine-induced intracellular Ca2+ increase. In the second phase release (15-60 min), a sustained arachidonic acid release appeared to be associated with the formation of cyclooxygenase and lipoxygenase metabolites. Fenspiride (10(-5) M) abolished both phases of histamine-induced arachidonic acid release. These results suggest that anti-inflammatory and antibronchoconstrictor properties of fenspiride may result from the inhibition of these effects of histamine.

Therapeutic Options for Controlling Fluids in the Visual System

NASA Technical Reports Server (NTRS)

Curry, Kristina M.; Wotring, Virginia E.

2014-01-01

Visual Impairment/Intracranial Pressure (VIIP) is a newly recognized risk at NASA. The VIIP project examines the effect of long-term exposure to microgravity on vision of crewmembers before and after they return to Earth. Diamox (acetazolamide) is a medication which is used to decrease intraocular pressure; however, it carries a 3% risk of kidney stones. Astronauts are at a higher risk of kidney stones during spaceflight and the use Diamox would only increase the risk; therefore alternative therapies were investigated. Histamine 2 (H2) antagonist acid blockers such as cimetidine, ranitidine, famotidine and nizatidine are typically used to relieve the symptoms of gastroesophageal reflux disease (GERD). H2 receptors have been found in the human visual system, which has led to research on the use of H2 antagonist blockers to control fluid production in the human eye. Another potential therapeutic strategy is targeted at aquaporins, which are water channels that help maintain fluid homeostasis. Aquaporin antagonists are also known to affect intracranial pressure which can in turn alter intraocular pressure. Studies on aquaporin antagonists suggest high potential for effective treatment. The primary objective of this investigation is to review existing research on alternate medications or therapy to significantly reduce intracranial and intraocular pressure. A literature review was conducted. Even though we do not have all the answers quite yet, a considerable amount of information was discovered, and findings were narrowed, which should allow for more conclusive answers to be found in the near future.

Binding of Cimetidine to Balb/C Mouse Liver Catalase; Kinetics and Conformational Studies.

PubMed

Jahangirvand, Mahboubeh; Minai-Tehrani, Dariush; Yazdi, Fatemeh; Minai-Tehrani, Arash; Razmi, Nematollah

2016-01-01

Catalase is responsible for converting hydrogen peroxide (H2O2) into water and oxygen in cells. This enzyme has high affinity for hydrogen peroxide and can protect the cells from oxidative stress damage. Catalase is a tetramer protein and each monomer contains a heme group. Cimetidine is a histamine H2 receptor blocker which inhibits acid release from stomach and is used for gasterointestinal diseases. In this research, effect of cimetidine on the activity of liver catalase was studied and the kinetic parameters of this enzyme and its conformational changes were investigated. Cell free extract of mouse liver was used for the catalase assay. The activity of the catalase was detected in the absence and presence of cimetidine by monitoring hydrogen peroxide reduction absorbance at 240 nm. The purified enzyme was used for conformational studies by Fluorescence spectrophotometry. The data showed that cimetidine could inhibit the enzyme in a non-competitive manner. Ki and IC50 values of the drug were determined to be about 0.75 and 0.85 uM, respectively. The Arrhenius plot showed that activation energy was 6.68 and 4.77 kJ/mol in the presence and absence of the drug, respectively. Fluorescence spectrophotometry revealed that the binding of cimetidine to the purified enzyme induced hyperchromicity and red shift which determined the conformational change on the enzyme. Cimetidine could non-competitively inhibit the liver catalase with high affinity. Binding of cimetidine to the enzyme induced conformational alteration in the enzyme.

Histamine response and local cooling in the human skin: involvement of H1- and H2-receptors.

PubMed

Grossmann, M; Jamieson, M J; Kirch, W

1999-08-01

Histamine may contribute locally to cutaneous blood flow control under normal and pathologic conditions. The objective of this study was to observe the influence of skin temperature on histamine vasodilation, and the roles of H1-and H2-receptors using novel noninvasive methods. Eleven healthy subjects received, double-blind, single doses of the H1-receptor antagonist cetirizine (10 mg), cetirizine (10 mg) plus the H2-receptor antagonist cimetidine (400 mg), or placebo on separate occasions. Histamine was dosed cumulatively by iontophoresis to the forearm skin at 34 degrees C and 14 degrees C. Laser-Doppler flux (LDF) was measured at the same sites using customised probeholder/iontophoretic chambers with Peltier cooling elements. Finger mean arterial pressure (MAP) was measured and cutaneous vascular conductance calculated as LDF/MAP. Histamine vasodilation was reduced in cold skin. Cetirizine shifted the histamine dose-response at both temperatures: statistically significantly at 14 degrees C only. Combined H1- and H2-receptor antagonism shifted the response significantly at both temperatures. H1- and H2-receptors mediate histamine-induced skin vasodilation. The sensitivity of these receptors, particularly the H1- receptor, is attenuated at low skin temperature. Whether the reduced effect in cold skin represents specific receptor or postreceptor desensitization, or nonspecific attenuation of cutaneous vasodilation remains to be elucidated.

Effects of histamine and some related compounds on conditioned avoidance response in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasaka, K.; Kamei, C.; Akahori, H.

1985-11-25

When histamine (Hi) and other agonists were applied intraventricularly, Hi caused a dose-dependent inhibition of the avoidance response in rats; its ED50 was 3.60 ..mu..g. l-methylHi, l-methylimidazole acetic acid and imidazole acetic acid which are major metabolites of Hi produced no inhibitory effect even at 50 ..mu..g. H/sub 1/-agonists (2-methylHi and 2-thiazolylethylamine) also depressed the avoidance response; their dose-response lines run parallel to that of Hi. The depressant effects of H/sub 2/-agonists (4-methylHi and dimaprit) were relatively weak; their dose-response lines were not parallel to that of Hi. When antagonists were pretreated intravenously, Hi action was clearly antagonized by diphehydraminemore » and pyrilamine, but not by cimetidine or ranitidine. Intraventricular injection of Hi mixed with cimetidine or ranitidine did not change the effect induced by Hi alone. The avoidance response was not affected by noradrenaline, dopamine or 5-hydroxytryptamine. Although acetylcholine (ACh) suppressed the avoidance response dose-dependently, its effect was much weaker than that of Hi. Pretreatment with cholinergic blocking drugs (atropine and scopolamine) antagonized ACh action but not Hi action. From these results, it is assumed that the inhibitory effect of Hi on the avoidance response is preferentially linked to the H/sub 1/-receptor. After intraventricular application of /sup 3/H-Hi, the highest radioactivity was determined in the hypothalamus. 21 references, 4 figures, 4 tables.« less

Communication between mast cells and rat submucosal neurons.

PubMed

Bell, Anna; Althaus, Mike; Diener, Martin

2015-08-01

Histamine is a mast cell mediator released e.g. during food allergy. The aim of the project was to identify the effect of histamine on rat submucosal neurons and the mechanisms involved. Cultured submucosal neurons from rat colon express H1, H2 and H3 receptors as shown by immunocytochemical staining confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) with messenger RNA (mRNA) isolated from submucosal homogenates as starting material. Histamine evoked a biphasic rise of the cytosolic Ca(2+) concentration in cultured submucosal neurons, consisting in a release of intracellularly stored Ca(2+) followed by an influx from the extracellular space. Although agonists of all three receptor subtypes evoked an increase in the cytosolic Ca(2+) concentration, experiments with antagonists revealed that mainly H1 (and to a lesser degree H2) receptors mediate the response to histamine. In coculture experiments with RBL-2H3 cells, a mast cell equivalent, compound 48/80, evoked an increase in the cytosolic Ca(2+) concentration of neighbouring neurons. Like the response to native histamine, the neuronal response to the mast cell degranulator was strongly inhibited by the H1 receptor antagonist pyrilamine and reduced by the H2 receptor antagonist cimetidine. In rats sensitized against ovalbumin, exposure to the antigen induced a rise in short-circuit current (I sc) across colonic mucosa-submucosa preparations without a significant increase in paracellular fluorescein fluxes. Pyrilamine strongly inhibited the increase in I sc, a weaker inhibition was observed after blockade of protease receptors or 5-lipoxygenase. Consequently, H1 receptors on submucosal neurons seem to play a pivotal role in the communication between mast cells and the enteric nervous system.

Contribution of mast cells to the oedema induced by Bothrops moojeni snake venom and a pharmacological assessment of the inflammatory mediators involved.

PubMed

Galvão Nascimento, Neide; Sampaio, Marlos Cortez; Amaral Olivo, Renata; Teixeira, Catarina

2010-01-01

The ability of Bothrops moojeni venom (BmV) to induce oedema in mice, the involvement of principal inflammatory mediators and mast cells (MCs) were investigated. The intraplantar injection of BmV (0.3-6 microg/paw) caused a dose- and time-dependent oedema with a peak between 30 and 60 min after venom injection (0.3-1 microg/paw), disappearing within 24h. Either MCs granule inhibition or depletion by cromoglycate or C48/80, respectively, markedly reduced BmV-induced oedema. MCs depletion by imatinib also reduced oedema. Intraperitoneal BmV injection (2.5-10 microg/site) induced MCs degranulation and release of PGD(2). Treatment with promethazine, cimetidine or thioperamide, histamine H1, H2 and H3/H4 receptor antagonists, respectively, markedly reduced the initial phase of oedema. Combined treatment with these antagonists further reduced, but not abrogated oedema. Indomethacin or eterocoxib (cyclooxygenase inhibitors) reduced oedema until 180 min, whereas zileuton (lipoxygenase inhibitor) affected this event until 60 min. Dexamethazone caused a long lasting reduction of oedema. However, L-NAME and aminoguanidine (NO synthase inhibitors) significantly increased BmV-induced oedema. In conclusion, BmV induces oedema, mediated by MCs degranulation, histamine by H1, H2, H3/H4 receptors, prostaglandins and leukotrienes, and down-regulated by NO. Partial neutralization of oedema was observed even when polyspecific bothropic antivenom was injected immediately after venom. Copyright 2009 Elsevier Ltd. All rights reserved.

Randomized prospective evaluation of cimetidine and antacid control of gastric pH in the critically ill.

PubMed Central

Stothert, J C; Simonowitz, D A; Dellinger, E P; Farley, M; Edwards, W A; Blair, A D; Cutler, R; Carrico, C J

1980-01-01

One hundred forty-four critically ill patients admitted to an intensive care setting were randomly assigned to cimetidine or antacid treatament groups. Gastric pH was monitored hourly. One hundred twenty-three (85%) patients demonstrated a fall in pH to less than 4 and were considered to require prophylaxis. Prophylaxis was considered adequate if the measured pH could then be maintained at greater than or equal to 4. Fifty-eight patients received antacids alone, the average requirement being 41 cc/hour. Sixty-five patients received cimetidine. Seventeen (26%) of the cimetidine prophylaxis patients failed to raise their pH and were than placed on hourly administration of antacid with successful elevations of pH to greater than or equal to 4 in all cases on an average supplementary dose of 53 cc/hour. Risk factors, including sepsis, hypotension, head injury, respiratory failure, degree of trauma, and age, were not statistically different in the two treated groups. Using these same criteria, responders to cimetidine could not be differentiated from nonresponders. All patients were protected from significant stress bleeding while on this study. Significant complications of either treatment were minimal. Antacids offered consistent protection against gastric acidity and were 100% effective. A routine schedule of 300 mg every six hours of cimetidine was effective in only 47% of patients, and the maximum dose of cimetidine was effective in only 74% of patients. Hourly measurement of intragastric pH is required for monitoring the response to prophylaxis of stress bleeding in severely ill patients. PMID:7406571

Studies on the trigeminal antidromic vasodilatation and plasma extravasation in the rat.

PubMed Central

Couture, R; Cuello, A C

1984-01-01

Antidromic stimulation of sensory peripheral branches of the trigeminal system (mental nerve) led to cutaneous vasodilatation and increased vascular permeability in rats anaesthetized with urethane. The antidromic vasodilatation observed in intact animals was not altered by decentralization or sympathectomy. Both antidromic vasodilatation and neurogenic plasma extravasation remained unaffected by pre-treatment with cimetidine, indomethacin, baclofen, guanethidine plus phentolamine and propranolol, but were significantly reduced by cimetidine plus mepyramine and atropine, suggesting that cholinergic and histaminergic components might be involved in the sensory neurogenic responses. Methysergide reduced only the extravasation, suggesting that probably serotonin liberated by mast cells upon sensory stimulation can contribute to the neurogenic responses. In tests using substance P (SP) antagonists (D-pro4, D- trp 7, 9, 10)-SP (4-11) and (D-pro2, D-trp 7, 9)-SP it was found that they are more active in reducing the neurogenic extravasation than the vasodilatation. In addition it was observed that (D-pro 4, D-trp 7, 9, 10)-SP (4-11) was the most potent substance P antagonist in reducing the plasma extravasation and antidromic vasodilatation resulting from sensory stimulation. PMID:6199494

Transdermal Delivery of Cimetidine Across Microneedle-Treated Skin: Effect of Extent of Drug Ionization on the Permeation.

PubMed

Song, Yang; Herwadkar, Anushree; Patel, Meera G; Banga, Ajay K

2017-05-01

The objective of this work was to optimize a gel formulation of cimetidine to maximize its transdermal delivery across microporated skin. Specifically, the effect of extent of ionization in formulation on permeation of cimetidine across microporated skin was studied. Cimetidine was formulated into a gel using propylene glycol, water, and carbopol 980NF. Three strengths of gels (0.1% w/w, 0.5% w/w, and 0.8% w/w) were made and Tris base was used to adjust the pH of formulations to pH 5, pH 6.8, and pH 7.5. In vitro permeation testing was performed on vertical Franz cells with dermatomed porcine ear skin. Permeation studies suggested that pH 5 gels showed highest permeation through microchannels. This trend was more prominent with an increase in drug loading. The total amount of cimetidine delivered from 0.8% w/w gel at pH 5 at 24 h was 28.20 ± 4.63 μg, which was significantly higher than that from pH 6.8 (16.89 ± 3.56 μg) and pH 7.5 (12.03 ± 1.66 μg) gels. Cimetidine permeation across microporated skin was found to be pH dependent, with lower pH/highest ionization resulting in greatest permeation. The effect of ionization contributing to faster release was more pronounced when drug concentration was increased. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Functional involvement of the organic cation transporter 2 (rOct2) in the renal uptake of organic cations in rats.

PubMed

Umehara, K-I; Iwatsubo, T; Noguchi, K; Kamimura, H

2008-01-01

This study examined the contribution made by organic cation transporters (hOCT/rOct) to the saturable component of the renal uptake of 1-methyl-4-phenylpyridinium, tetraethylammonium (TEA), cimetidine and metformin into rOct2-expressing HEK293 cells and rat kidney slices. All the test compounds accumulated in the rat kidney slices in a carrier-mediated manner. The Michaelis- Menten constant (K(m)) values for saturable uptake of TEA, cimetidine and metformin into rat kidney slices were relatively comparable with those for the rOct2-expressing HEK293 cells. In addition, the relative uptake activity values of TEA, cimetidine and metformin in rat kidney slices were similar to those in rOct2-expressing HEK293 cells. This suggests that the saturable components involved in the renal uptake of TEA, cimetidine and metformin are mediated mainly by rOct2. The saturable uptake profile of cationic compounds into rat kidney can be evaluated in both cDNA-expressing cells and rat kidney slices, as well as the transporter expression pattern. This approach can also be used to estimate the saturable uptake mechanism of cationic compounds into the human kidney when human kidney slices and hOCT2-expressing cells are used.

Histamine paw edema of mice was increased and became H[sub 2]-antagonist sensitive by co-injection of nitric oxide forming agents, but serotonin paw edema was decreased

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oyanagui, Yoshihiko; Sato, Sachio

1993-01-01

Nitric oxide (NO) surprisingly caused the opposite effect on histamine and serotonin edema. The local injection of acidified nitrite (0.3-30 [mu]g/paw which correspond 10 [mu]g-1mg/kg) increased histamine edema of mice up to 45[plus minus]4% and suppressed serotonin edema to 90[plus minus]3%. Other NO-generators (nitroprusside sodium and hydroxylamine) showed similar effects. These results were in accordance with previous data on endogenous NO. Methylene blue (MB, 30ng/paw which corresponds to 1 [mu]g/kg) suppressed histamine edema (62[plus minus]3%) and increased serotonin edema (43[plus minus]3%) in normal mice, being reversed by acidified nitrite. This suggests the involvement of guanosine 3[prime], 5[prime]-cyclic monophosphate (cGMP) formationmore » for the action of NO. Histamine edema became sensitive to H[sub 2]-antagonist, cimetidine, by co-injection of 30 [mu]g/paw (which corresponds to 1mg/kg) acidified nitrite (ED[sub 50] = 30 [mu]g/kg versus [much gt] 1mg/kg). NO seemed to modify the histamine receptor(s) or tautomeric form of histamine. NO, O[sup [minus

Activation of adenosine low-affinity A3 receptors inhibits the enteric short interplexus neural circuit triggered by histamine.

PubMed

Bozarov, Andrey; Wang, Yu-Zhong; Yu, Jun Ge; Wunderlich, Jacqueline; Hassanain, Hamdy H; Alhaj, Mazin; Cooke, Helen J; Grants, Iveta; Ren, Tianhua; Christofi, Fievos L

2009-12-01

We tested the novel hypothesis that endogenous adenosine (eADO) activates low-affinity A3 receptors in a model of neurogenic diarrhea in the guinea pig colon. Dimaprit activation of H2 receptors was used to trigger a cyclic coordinated response of contraction and Cl(-) secretion. Contraction-relaxation was monitored by sonomicrometry (via intracrystal distance) simultaneously with short-circuit current (I(sc), Cl(-) secretion). The short interplexus reflex coordinated response was attenuated or abolished by antagonists at H2 (cimetidine), 5-hydroxytryptamine 4 receptor (RS39604), neurokinin-1 receptor (GR82334), or nicotinic (mecamylamine) receptors. The A1 agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) abolished coordinated responses, and A1 antagonists could restore normal responses. A1-selective antagonists alone [8-cyclopentyltheophylline (CPT), 1,3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX), or 8-cyclopentyl-N(3)-[3-(4-(fluorosulfonyl)benzoyloxy)propyl]-xanthine (FSCPX)] caused a concentration-dependent augmentation of crypt cell secretion or contraction and acted at nanomolar concentrations. The A3 agonist N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) abolished coordinated responses and the A3 antagonist 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS1191) could restore and further augment responses. The IB-MECA effect was resistant to knockdown of adenosine A1 receptor with the irreversible antagonist FSCPX; the IC(50) for IB-MECA was 0.8 microM. MRS1191 alone could augment or unmask coordinated responses to dimaprit, and IB-MECA suppressed them. MRS1191 augmented distension-evoked reflex I(sc) responses. Adenosine deaminase mimicked actions of adenosine receptor antagonists. A3 receptor immunoreactivity was differentially expressed in enteric neurons of different parts of colon. After tetrodotoxin, IB-MECA caused circular muscle relaxation. The data support the novel concept that eADO acts at low-affinity A3 receptors in addition to high-affinity A1 receptors to suppress coordinated responses triggered by immune-histamine H2 receptor activation. The short interplexus circuit activated by histamine involves adenosine, acetylcholine, substance P, and serotonin. We postulate that A3 receptor modulation may occur in gut inflammatory diseases or allergic responses involving mast cell and histamine release.

Activation of adenosine low-affinity A3 receptors inhibits the enteric short interplexus neural circuit triggered by histamine

PubMed Central

Bozarov, Andrey; Wang, Yu-Zhong; Yu, Jun Ge; Wunderlich, Jacqueline; Hassanain, Hamdy H.; Alhaj, Mazin; Cooke, Helen J.; Grants, Iveta; Ren, Tianhua

2009-01-01

We tested the novel hypothesis that endogenous adenosine (eADO) activates low-affinity A3 receptors in a model of neurogenic diarrhea in the guinea pig colon. Dimaprit activation of H2 receptors was used to trigger a cyclic coordinated response of contraction and Cl− secretion. Contraction-relaxation was monitored by sonomicrometry (via intracrystal distance) simultaneously with short-circuit current (Isc, Cl− secretion). The short interplexus reflex coordinated response was attenuated or abolished by antagonists at H2 (cimetidine), 5-hydroxytryptamine 4 receptor (RS39604), neurokinin-1 receptor (GR82334), or nicotinic (mecamylamine) receptors. The A1 agonist 2-chloro-N6-cyclopentyladenosine (CCPA) abolished coordinated responses, and A1 antagonists could restore normal responses. A1-selective antagonists alone [8-cyclopentyltheophylline (CPT), 1,3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX), or 8-cyclopentyl-N3-[3-(4-(fluorosulfonyl)benzoyloxy)propyl]-xanthine (FSCPX)] caused a concentration-dependent augmentation of crypt cell secretion or contraction and acted at nanomolar concentrations. The A3 agonist N6-(3-iodobenzyl)-adenosine-5′-N-methyluronamide (IB-MECA) abolished coordinated responses and the A3 antagonist 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS1191) could restore and further augment responses. The IB-MECA effect was resistant to knockdown of adenosine A1 receptor with the irreversible antagonist FSCPX; the IC50 for IB-MECA was 0.8 μM. MRS1191 alone could augment or unmask coordinated responses to dimaprit, and IB-MECA suppressed them. MRS1191 augmented distension-evoked reflex Isc responses. Adenosine deaminase mimicked actions of adenosine receptor antagonists. A3 receptor immunoreactivity was differentially expressed in enteric neurons of different parts of colon. After tetrodotoxin, IB-MECA caused circular muscle relaxation. The data support the novel concept that eADO acts at low-affinity A3 receptors in addition to high-affinity A1 receptors to suppress coordinated responses triggered by immune-histamine H2 receptor activation. The short interplexus circuit activated by histamine involves adenosine, acetylcholine, substance P, and serotonin. We postulate that A3 receptor modulation may occur in gut inflammatory diseases or allergic responses involving mast cell and histamine release. PMID:19808660

Recombinant neutral endopeptidase attenuates substance P-induced plasma extravasation in the guinea pig skin.

PubMed

Rubinstein, I; Iwamoto, I; Ueki, I F; Borson, D B; Nadel, J A

1990-01-01

To determine whether exogenously administered neutral endopeptidase (NEP; enkephalinase, EC 3.4.24.11) inhibits the substance P-induced increase in vascular permeability in the skin, we examined the effects of recombinant human NEP on plasma extravasation induced by intradermal injection of substance P in guinea pig skin. Injection of substance P (2.5 X 10(-8) M) induced significant plasma extravasation in the skin (53 +/- 4 mm2 of Evans blue extravasation; mean +/- 1 SEM). In vitro incubation of substance P with recombinant human NEP prior to injection prevented the substance P-induced plasma extravasation in the skin in a dose-dependent fashion. Intradermal preinjection of recombinant human NEP partially inhibited plasma extravasation induced by subsequent injection of substance P (52 +/- 9% of the control without NEP). The H1 and H2 histamine antagonists pyrilamine and cimetidine, and a muscarinic antagonist, atropine, had no effects on substance P-induced responses. Two products of substance P degradation by NEP containing the carboxy-terminal portion, substance P7-11 and substance P8-11, were also without effect. These findings suggest that recombinant human NEP can attenuate substance P-induced increases in vascular permeability in guinea pig skin and, therefore, may be useful in treating dermatologic disorders in which abnormal responses to substance P or other neuropeptides cleaved by NEP may occur.

Prevention of upper gastrointestinal bleeding in critically ill Chinese patients: a randomized, double-blind study evaluating esomeprazole and cimetidine.

PubMed

Lou, Wenhui; Xia, Ying; Xiang, Peng; Zhang, Liangqing; Yu, Xiangyou; Lim, Sam; Xu, Mo; Zhao, Lina; Rydholm, Hans; Traxler, Barry; Qin, Xinyu

2018-04-20

To assess the efficacy and safety of esomeprazole in preventing upper gastrointestinal (GI) bleeding in critically ill Chinese patients, using cimetidine as an active comparator. A pre-specified non-inferiority limit (5%) was used to compare rates of significant upper GI bleeding in this randomized, double-blind, parallel-group, phase 3 study across 27 intensive care units in China. Secondary endpoints included safety and tolerability measures. Patients required mechanical ventilation and had at least one additional risk factor for stress ulcer bleeding. Patients were randomized to receive either active esomeprazole 40 mg, as a 30-min intravenous (IV) infusion twice daily, and an IV placebo cimetidine infusion or active cimetidine 50 mg/h, as a continuous infusion following an initial bolus of 300 mg, and placebo esomeprazole injections, given up to 14 days. Patients were blinded using this double-dummy technique. Of 274 patients, 2.7% with esomeprazole and 4.6% with cimetidine had significant upper GI bleeding (bright red blood in the gastric tube not clearing after lavage or persistent Gastroccult-positive "coffee grounds" material). Non-inferiority of esomeprazole to cimetidine was demonstrated. The safety profiles of both drugs were similar and as expected in critically ill patients. Esomeprazole is effective in preventing upper GI bleeding in critically ill Chinese patients, as demonstrated by the non-inferiority analysis using cimetidine as an active control. ClinicalTrials.gov identifier NCT02157376.

Segmental dependent transport of low permeability compounds along the small intestine due to P-glycoprotein: the role of efflux transport in the oral absorption of BCS class III drugs.

PubMed

Dahan, Arik; Amidon, Gordon L

2009-01-01

The purpose of this study was to investigate the role of P-gp efflux in the in vivo intestinal absorption process of BCS class III P-gp substrates, i.e. high-solubility low-permeability drugs. The in vivo permeability of two H (2)-antagonists, cimetidine and famotidine, was determined by the single-pass intestinal perfusion model in different regions of the rat small intestine, in the presence or absence of the P-gp inhibitor verapamil. The apical to basolateral (AP-BL) and the BL-AP transport of the compounds in the presence or absence of various efflux transporters inhibitors (verapamil, erythromycin, quinidine, MK-571 and fumitremorgin C) was investigated across Caco-2 cell monolayers. P-gp expression levels in the different intestinal segments were confirmed by immunoblotting. Cimetidine and famotidine exhibited segmental dependent permeability through the gut wall, with decreased P(eff) in the distal ileum in comparison to the proximal regions of the intestine. Coperfusion of verapamil with the drugs significantly increased the permeability in the ileum, while no significant change in the jejunal permeability was observed. Both drugs exhibited significantly greater BL-AP than AP-BL Caco-2 permeability, indicative of net mucosal secretion. Concentration dependent decrease of this secretion was obtained by the P-gp inhibitors verapamil, erythromycin and quinidine, while no effect was evident by the MRP2 inhibitor MK-571 and the BCRP inhibitor FTC, indicating that P-gp is the transporter mediates the intestinal efflux of cimetidine and famotidine. P-gp levels throughout the intestine were inversely related to the in vivo permeability of the drugs from the different segments. The data demonstrate that for these high-solubility low-permeability P-gp substrates, P-gp limits in vivo intestinal absorption in the distal segments of the small intestine; however P-gp plays a minimal role in the proximal intestinal segments due to significant lower P-gp expression levels in this region.

Disseminated Scedosporium prolificans infection in an 'extensive metaboliser': navigating the minefield of drug interactions and pharmacogenomics.

PubMed

Trubiano, J A; Paratz, E; Wolf, M; Teh, B W; Todaro, M; Thursky, K A; Slavin, M A

2014-09-01

We report a case of non-fatal disseminated Scedosporium prolificans infection, including central nervous system disease and endophthalmitis, in a relapsed acute myeloid leukaemia patient with extensive CYP2C19 metabolism. Successful treatment required aggressive surgical debridement, three times daily voriconazole dosing and cimetidine CYP2C19 inhibition. In addition, the unique use of miltefosine was employed due to azole-chemotherapeutic drug interactions. Prolonged survival following disseminated S. prolificans, adjunctive miltefosine and augmentation of voriconazole exposure with cimetidine CYP2C19 inhibition has not been reported. © 2014 Blackwell Verlag GmbH.

Haloperidol-stomach lesions attenuation by pentadecapeptide BPC 157, omeprazole, bromocriptine, but not atropine, lansoprazole, pantoprazole, ranitidine, cimetidine and misoprostol in mice.

PubMed

Bilic, I; Zoricic, I; Anic, T; Separovic, J; Stancic-Rokotov, D; Mikus, D; Buljat, G; Ivankovic, D; Aralica, G; Prkacin, I; Perovic, D; Mise, S; Rotkvic, I; Petek, M; Rucman, R; Seiwerth, S; Sikiric, P

2001-03-09

The focus was on haloperidol (central dopamine antagonist)-stomach lesion, a longly described suitable counterpart of dopamine blocker cysteamine-duodenal lesion. In this, the contribution of blockade of central/peripheral dopamine receptors and prostaglandins synthesis, along with influence of antiulcer agents was evaluated in mice. Male NMRI Hannnover mice were sacrificed 24 h after haloperidol (25 mg/kg b.w. i.p., given alone or with saline (haloperidol+saline) (i) or in combination (ii,iii)). Supporting central dopamine predominance for haloperidol stomach lesion induction, co-administration of peripheral dopamine receptor antagonist domperidone (5 mg/kg i.p.) (haloperidol+ domperidone) (ii), or prostaglandin synthesis inhibitor indomethacin (10 mg/kg s.c.) (haloperidol+ indomethacin) (iii) did not aggravate this lesion. (i) In haloperidol+saline challenged mice the lesions were inhibited by co-administration (/kg i.p.) of a gastric pentadecapeptide BPC 157, GlyGluProProProGlyLysProAlaAspAspAlaGlyLeuVal, M.W. 1419 (10 microg, 10 ng, 10 pg, but not 1 pg, 100 fg, 10 fg), bromocriptine (10 mg), omeprazole (10 mg, 100 mg, but not 1 mg). Atropine (10, 100, 200 mg), pirenzepine (10, 100, 200 mg), misoprostol (10, 100, 200 microg), pantoprazole (1, 10, 100 mg), lansoprazole (0.1, 1, 10 mg), cimetidine (10, 100, 200 mg) and ranitidine (10, 100, 200 mg) were not effective. (ii) Dopamine peripheral blockade influence: in haloperidol+domperidone mice, previously effective bromocriptine, pentadecapeptide BPC 157 (10 microg) or omeprazole (10 mg) did not attenuate stomach lesions. (iii) Prostaglandins synthesis blockade effect: in haloperidol+indomethacin mice, previously effective agents, bromocriptine or omeprazole were not active, while BPC 157 effect was only lessened.

Emodin induces chloride secretion in rat distal colon through activation of mast cells and enteric neurons

PubMed Central

Xu, J-D; Liu, S; Wang, W; Li, L-S; Li, X-F; Li, Y; Guo, H; Ji, T; Feng, X-Y; Hou, X-L; Zhang, Y; Zhu, J-X

2012-01-01

BACKGROUND AND PURPOSE Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is an active component of many herb-based laxatives. However, its mechanism of action is unclear. The aim of the present study was to investigate the role of mast cells and enteric neurons in emodin-induced ion secretion in the rat colon. EXPERIMENTAL APPROACH Short-circuit current (ISC) recording was used to measure epithelial ion transport. A scanning ion-selective electrode technique was used to directly measure Cl- flux (JCl−) across the epithelium. RIA was used to measure emodin-induced histamine release. KEY RESULTS Basolateral addition of emodin induced a concentration-dependent increase in ISC in colonic mucosa/submucosa preparations, EC50 75 µM. The effect of emodin was blocked by apically applied glibenclamide, a Cl- channel blocker, and by basolateral application of bumetanide, an inhibitor of the Na+-K+-2Cl- cotransporter. Emodin-evoked JCl− in mucosa/submucosa preparations was measured by scanning ion-selective electrode technique, which correlated to the increase in ISC and was significantly suppressed by glibenclamide and bumetanide. Pretreatment with tetrodotoxin and the muscarinic receptor antagonist atropine had no effect on emodin-induced ΔISC in mucosa-only preparations, but significantly reduced emodin-induced ΔISC and JCl− in mucosa/submucosa preparations. The COX inhibitor indomethacin, the mast cell stabilizer ketotifen and H1 receptor antagonist pyrilamine significantly reduced emodin-induced ΔISC in mucosa and mucosa/submucosa preparations. The H2 receptor antagonist cimetidine inhibited emodin-induced ΔISC and JCl− only in the mucosa/submucosa preparations. Furthermore, emodin increased histamine release from the colonic mucosa/submucosa tissues. CONCLUSIONS AND IMPLICATIONS The results suggest that emodin-induced colonic Cl- secretion involves mast cell degranulation and activation of cholinergic and non-cholinergic submucosal neurons. PMID:21718311

Effects of oral cimetidine on the reproductive system of male rats

PubMed Central

Liu, Xu; Jia, Yuling; Chong, Liming; Jiang, Juan; Yang, Yang; Li, Lei; Ma, Aicui; Sun, Zuyue; Zhou, Li

2018-01-01

Cimetidine is widely used for the treatment of digestive tract ulcers, but it induces testis injury. To explore the mechanisms underlying cimetidine-induced toxicity towards the testis, the effects of oral cimetidine on the reproductive system of male rats were assessed. Cimetidine was orally administered to male rats at 20, 40 or 120 mg/kg/day for 9 weeks. The rats were then euthanized, and serum, testis, epididymis, prostate gland, seminal vesicle, preputial gland, levator ani muscle and sphincter ani samples were collected. Sperm parameters were obtained by computer-assisted sperm analysis. Serum hormone levels were measured by ELISA. Protein expression levels were detected by immunohistochemistry. Apoptosis was assessed with the DeadEnd™ Colorimetric Apoptosis Detection System. The results indicated that the sperm average path velocity, straight line velocity and curvilinear velocity were significantly decreased in the 120 mg/kg cimetidine group compared with the control group, while luteinizing hormone and testosterone levels were significantly higher compared with the control group. Testicular lesions were observed by histopathology in the 120 mg/kg cimetidine group. The amounts of cells positive for cyclooxygenase-2 (COX-2) and nuclear factor κB (NF-κB) were increased in the 120 mg/kg cimetidine group compared with the control group. The amounts of cells positive for iNOS were increased in all cimetidine treatment groups. In addition, apoptotic cells were significantly more abundant in the 120 mg/kg cimetidine group compared with the control group, as indicated by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling. Overall, 9 weeks of oral cimetidine induced pathological changes in the testicles and hormone secretion disorder in rats. COX-2, iNOS and NF-κB upregulation and induction of apoptosis may be associated with the reproductive toxicity caused by cimetidine.

Hypertensive response to stress: the role of histaminergic H1 and H2 receptors in the medial amygdala.

PubMed

de Almeida, Daniela Oliveira; Ferreira, Hilda Silva; Pereira, Luana Bomfim; Fregoneze, Josmara Bartolomei

2015-05-15

Different brain areas seem to be involved in the cardiovascular responses to stress. The medial amygdala (MeA) has been shown to participate in cardiovascular control, and acute stress activates the MeA to a greater extent than any of the other amygdaloid structures. It has been demonstrated that the brain histaminergic system may be involved in behavioral, autonomic and neuroendocrine responses to stressful situations. The aim of the present study was to investigate the role of the histaminergic receptors H1 and H2 in cardiovascular responses to acute restraint stress. Wistar rats (280-320g) received bilateral injections of cimetidine, mepyramine or saline into the MeA and were submitted to 45min of restraint stress. Mepyramine microinjections at doses of 200, 100 and 50nmol promoted a dose-dependent blockade of the hypertensive response induced by the restraint stress. Cimetidine (200 and 100nmol) promoted a partial blockade of the hypertensive response to stress only at the highest dose administered. Neither drugs altered the typical stress-evoked tachycardiac responses. Furthermore, mepyramine and cimetidine were unable to modify the mean arterial pressure or heart rate of freely moving rats under basal conditions (non-stressed rats). The data suggest that in the MeA the histaminergic H1 receptors appear to be more important than H2 receptors in the hypertensive response to stress. Furthermore, there appears to be no histaminergic tonus in the MeA controlling blood pressure during non-stress conditions. Copyright © 2015 Elsevier Inc. All rights reserved.

Gastric vagus mediates immobilization-induced hypocalcemia in rats.

PubMed

Ma, J; Aou, S; Matsui, H; Hori, T

1993-09-01

The involvement of the parasympathetic nervous system in the etiology of stress-induced hypocalcemia was investigated in the rat. Atropine methyl bromide (0.1 and 0.6 mg/kg ip) given 20 min before immobilization (IMB) was observed to suppress the induction of hypocalcemia in a dose-dependent manner. A vagotomy of the bilateral cervical trunks also abolished the IMB-induced hypocalcemia. A vagotomy on either the thyroid/parathyroid branches or the celiac branches had no effect on the IMB-induced hypocalcemia, but a vagotomy on the gastric branches completely abolished it. Pretreatment with either secretin (2 and 6 micrograms/kg ip), an inhibitor of gastrin release, or cimetidine (5 and 10 mg/kg ip), a histamine H2-receptor antagonist, diminished the IMB-induced hypocalcemia. The concentration of serum gastrin increased significantly during IMB. It is thus concluded that the decreased levels of plasma calcium caused by IMB are due to the activation of the vagus innervating the stomach. Gastrin and histamine are also involved as a consequence of the activation of the vagus.

Sensitive Indirect Spectrophotometric Method for Determination of H2-Receptor Antagonists in Pharmaceutical Formulations

PubMed Central

Darwish, Ibrahim A.; Hussein, Samiha A.; Mahmoud, Ashraf M.; Hassan, Ahmed I.

2007-01-01

A simple, accurate and sensitive spectrophotometric method has been developed and validated for determination of H2-receptor antagonists: cimetidine, famotidine, nizatidine, and ranitidine hydrochloride. The method was based on the oxidation of these drugs with cerium (IV) in presence of perchloric acid and subsequent measurement of the excess Ce (IV) by its reaction with p-dimethylaminocinnamaldehyde to give a red colored product (λmax at 464 nm). The decrease in the absorption intensity (ΔA) of the colored product, due to the presence of the drug was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9985-0.9994) were found between ΔA values and the concentrations of the drugs in a concentration range of 1-16 µg ml-1. The assay limits of detection and quantitation were 0.12-0.44 and 0.37-1.33 µg ml-1, respectively. The method was validated, in terms of accuracy, precision, ruggedness, and robustness; the results were satisfactory. The proposed method was successfully applied to the analysis of the investigated drugs in their pure and pharmaceutical dosage forms (recovery was 98.8-102.5 ± 0.79-1.72%) without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods. PMID:23675034

Intravenous Esomeprazole for Prevention of Peptic Ulcer Rebleeding: A Randomized Trial in Chinese Patients.

PubMed

Bai, Yu; Chen, Dong-Feng; Wang, Rong-Quan; Chen, You-Xiang; Shi, Rui-Hua; Tian, De-An; Chen, Huifang; Eklund, Stefan; Li, Zhao-Shen

2015-11-01

High-dose intravenous esomeprazole is the only approved pharmacological treatment for the prevention of peptic ulcer rebleeding (currently approved in over 100 countries worldwide), but has not yet been approved in China. This study aimed to evaluate a high-dose esomeprazole intravenous regimen vs. an active control (cimetidine) for the prevention of rebleeding in Chinese patients with a high risk of peptic ulcer rebleeding who had undergone primary endoscopic hemostatic treatment. This was a parallel-group study conducted at 20 centers in China. The study comprised a randomized, double-blind, intravenous treatment phase of 72 h in which 215 patients received either high-dose esomeprazole (80 mg + 8 mg/h) or cimetidine (200 mg + 60 mg/h), followed by an open-label oral treatment phase in which all patients received esomeprazole 40 mg tablets once daily for 27 days. The primary outcome was the rate of clinically significant rebleeding within the first 72 h after initial endoscopic hemostatic therapy. Secondary outcomes included the rates of clinically significant rebleeding within 7 and 30 days; proportions of patients who had endoscopic retreatment and other surgery due to rebleeding; and number of blood units transfused. The rate of clinically significant rebleeding within 72 h was low overall (3.3%) and numerically lower in patients treated with esomeprazole compared with cimetidine (0.9% vs. 5.6%). Overall, the results of the secondary outcomes also showed a numerical trend towards superiority of esomeprazole over cimetidine. All treatments were well tolerated. In this phase 3, multicenter, randomized trial conducted in China, esomeprazole showed a numerical trend towards superior clinical benefit over cimetidine in the prevention of rebleeding in patients who had successfully undergone initial hemostatic therapy of a bleeding peptic ulcer, with a similar safety and tolerability profile. These findings suggest that esomeprazole may be an alternative treatment option to cimetidine for this indication in China. AstraZeneca. ClinicalTrials.gov identifier, NCT01757275.

Active transport of cimetidine into human milk.

PubMed

Oo, C Y; Kuhn, R J; Desai, N; McNamara, P J

1995-11-01

Most xenobiotics are transferred from blood into breast milk by passive diffusion. However, an active transport mechanism has been speculated for cimetidine, and the purpose of this study was to characterize cimetidine transfer into human milk. Twelve healthy lactating volunteers received single oral doses of 100, 600, and 1200 mg cimetidine in a randomized, crossover design on 3 different days. Blood and milk specimens were collected and assayed for cimetidine. In vitro measurements, including skim to whole milk concentration ratio, milk pH, and free fractions in serum and milk were used for a diffusion model prediction of milk to serum concentration ratio of cimetidine; the mean milk/serum ratio (+/- SD) was 1.05 +/- 0.18. The observed milk/serum ratio (5.77 +/- 1.24) was 5.5 times higher than the milk/serum ratio predicted by diffusion. The observed milk/serum ratio for the three dosing regimens were not significantly different from one another. Time of peak concentration (tmax) in milk (3.3 +/- 0.7 hours) displayed a delay compared with serum tmax (1.7 +/- 0.6 hours). Oral clearance for 1200 mg cimetidine dose (0.47 +/- 0.11 L/hr/kg) was significantly lower compared with oral clearance values for 100 and 600 mg cimetidine doses (0.59 +/- 0.11 and 0.57 +/- 0.13 L/hr/kg, respectively). The maternal dose of cimetidine ingested by a suckling infant based on body weight was estimated to be 6.7%, which appears to be safe under normal conditions. This study provides the first definitive evidence of an active transport system for drug transfer into human milk, which may have broader consequences for the suckling infant.

Disposition of the anti-ulcer medications ranitidine, cimetidine, and omeprazole following administration of multiple doses to exercised Thoroughbred horses.

PubMed

Knych, H K; Stanley, S D; Arthur, R M; McKemie, D S

2017-01-01

The use of anti-ulcer medications, such as cimetidine, ranitidine, and omeprazole, is common in performance horses. The use of these drugs is regulated in performance horses, and as such a withdrawal time is necessary prior to competition to avoid a medication violation. To the authors' knowledge, there are no reports in the literature describing repeated oral administrations of these drugs in the horse to determine a regulatory threshold and related withdrawal time recommendations. Therefore, the objective of the current study was to describe the disposition and elimination pharmacokinetics of these anti-ulcer medications following oral administration to provide data upon which appropriate regulatory recommendations can be established. Nine exercised Thoroughbred horses were administered 20 mg/kg BID of cimetidine or 8 mg/kg BID of ranitidine, both for seven doses or 2.28 g of omeprazole SID for four doses. Blood samples were collected, serum drug concentrations were determined, and elimination pharmacokinetic parameters were calculated. The serum elimination half-life was 7.05 ± 1.02, 7.43 ± 0.851 and 3.94 ± 1.04 h for cimetidine, ranitidine, and omeprazole, respectively. Serum cimetidine and ranitidine concentrations were above the LOQ and omeprazole and omeprazole sulfide below the LOQ in all horses studied upon termination of sample collection. © 2016 John Wiley & Sons Ltd.

The evolution of anti-ulcer therapy with cimetidine. Is a single large nocturnal dose of cimetidine the right therapy for duodenal ulcer?

PubMed

Barbara, L; Corinaldesi, B; Stanghellini, V; Paternicò, A; Fabbri, L; Sacco, T

1986-01-01

Peptic ulcer results from the prevalence of agents causing endoluminal lesions over the defence mechanisms of the mucosa of the upper GI tract. Particularly, in the case of duodenal ulcer, the pathogenetic relevance of non-buffered acid secretion of the early nighttime period has been emphasized. This is indeed confirmed by the fact that a single night dose of 800 mg cimetidine has apparently been proved able--in numerous controlled clinical trials--to provide results that are similar to those obtained with the classic dose of 1 g daily or 400 mg twice daily. Our centre carried out a crossover double-blind controlled trial aimed at evaluating titrable acidity and pH during the 24-h period in seven patients with active duodenal ulcer. The single nighttime dose of cimetidine resulted in a significant and long-lasting inhibition of acid secretion during the entire night. During the day, secretory values returned to levels similar to those obtained with placebo, hence allowing normal digestive functions.

Specific cerebral heat shock proteins and histamine receptor cross-talking mechanisms promote distinct lead-dependent neurotoxic responses in teleosts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giusi, Giuseppina; Alo, Raffaella; Crudo, Michele

Recent interests are beginning to be directed towards toxic neurobiological dysfunctions caused by lead (Pb) in aquatic vertebrates. In the present work, treatment with a maximum acceptable toxic concentration of this heavy metal was responsible for highly significant (p < 0.01) abnormal motor behaviors such as hyperactive movements in the teleost Thalassoma pavo and the same treatment accounted for significantly (p < 0.05) enhanced hyperventilating states. On the other hand, greater abnormal motor behaviors were detected in the presence of the histamine (HA) receptor subtype 2 (H{sub 2}R) antagonist cimetidine (Cim), as shown by the very robust (p < 0.001)more » increases of the two behavioral states. Interestingly, elevated expression levels of stress-related factors, i.e. heat shock protein70/90 (HSP90/70) orthologs were reported for the first time in hypothalamic and mesencephalic areas of Pb-treated teleosts. In particular, an up-regulation of HSP70 was readily detected when this heavy metal was given concomitantly with Cim, while the histamine subtype 3 antagonist (H{sub 3}R) thioperamide (Thio), instead, blocked Pb-dependent up-regulatory trends of both chaperones in mostly hypothalamic areas. Moreover, intense neuronal damages of the above brain regions coincided with altered expressions of HSP70 and HSP90 when treated only with Cim. Overall these first results show that distinct H{sub n}R are able to exert a net neuroprotective role arising from their interaction with chaperones in fish exposed to Pb-dependent stressful conditions making this a potentially key interaction especially for T. pavo, aquatic species which plays an important ecological role towards the survival of other commercially vital fishes.« less

Human proximal tubule epithelial cells cultured on hollow fibers: living membranes that actively transport organic cations

PubMed Central

Jansen, J.; De Napoli, I. E; Fedecostante, M.; Schophuizen, C. M. S.; Chevtchik, N. V.; Wilmer, M. J.; van Asbeck, A. H.; Croes, H. J.; Pertijs, J. C.; Wetzels, J. F. M.; Hilbrands, L. B.; van den Heuvel, L. P.; Hoenderop, J. G.; Stamatialis, D.; Masereeuw, R.

2015-01-01

The bioartificial kidney (BAK) aims at improving dialysis by developing ‘living membranes’ for cells-aided removal of uremic metabolites. Here, unique human conditionally immortalized proximal tubule epithelial cell (ciPTEC) monolayers were cultured on biofunctionalized MicroPES (polyethersulfone) hollow fiber membranes (HFM) and functionally tested using microfluidics. Tight monolayer formation was demonstrated by abundant zonula occludens-1 (ZO-1) protein expression along the tight junctions of matured ciPTEC on HFM. A clear barrier function of the monolayer was confirmed by limited diffusion of FITC-inulin. The activity of the organic cation transporter 2 (OCT2) in ciPTEC was evaluated in real-time using a perfusion system by confocal microscopy using 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP+) as a fluorescent substrate. Initial ASP+ uptake was inhibited by a cationic uremic metabolites mixture and by the histamine H2-receptor antagonist, cimetidine. In conclusion, a ‘living membrane’ of renal epithelial cells on MicroPES HFM with demonstrated active organic cation transport was successfully established as a first step in BAK engineering. PMID:26567716

Simultaneous detection of pH changes and histamine release from oxyntic glands in isolated stomach.

PubMed

Bitziou, Eleni; O'Hare, Danny; Patel, Bhavik Anil

2008-11-15

Real-time simultaneous detection of changes in pH and levels of histamine over the oxyntic glands of guinea pig stomach have been investigated. An iridium oxide pH microelectrode was used in a potentiometric mode to record the pH decrease associated with acid secretion when the sensor approached the isolated tissue. A boron-doped diamond (BDD) microelectrode was used in an amperometric mode to detect histamine when the electrode was placed over the tissue. Both sensors provided stable and reproducible responses that were qualitatively consistent with the signaling mechanism for acid secretion at the stomach. Simultaneous measurements in the presence of pharmacological treatments produced significant variations in the signals obtained by both sensors. As the H2 receptor antagonist cimetidine was perfused to the tissue, histamine levels increased that produced an increase in the signal of the BDD electrode whereas the pH sensor recorded a decrease in acid secretion as expected. Addition of acetylcholine (ACh) stimulated additional acid secretion detected with the pH microelectrode whereas the BDD sensor recorded the histamine levels decreasing significantly. This result shows that the primary influence of ACh is directly on the parietal cell receptors rather then the ECL cell receptors of the oxyntic glands. These results highlight the power of this simultaneous detection technique in the monitoring and diagnosis of physiological significant signaling mechanisms and pathways.

Clinically important drug interactions with zopiclone, zolpidem and zaleplon.

PubMed

Hesse, Leah M; von Moltke, Lisa L; Greenblatt, David J

2003-01-01

Insomnia, an inability to initiate or maintain sleep, affects approximately one-third of the American population. Conventional benzodiazepines, such as triazolam and midazolam, were the treatment of choice for short-term insomnia for many years but are associated with adverse effects such as rebound insomnia, withdrawal and dependency. The newer hypnosedatives include zolpidem, zaleplon and zopiclone. These agents may be preferred over conventional benzodiazepines to treat short-term insomnia because they may be less likely to cause significant rebound insomnia or tolerance and are as efficacious as the conventional benzodiazepines. This review aims to summarise the published clinical drug interaction studies involving zolpidem, zaleplon and zopiclone. The pharmacokinetic and pharmacodynamic interactions that may be clinically important are highlighted. Clinical trials have studied potential interactions of zaleplon, zolpidem and zopiclone with the following types of drugs: cytochrome P450 (CYP) inducers (rifampicin), CYP inhibitors (azoles, ritonavir and erythromycin), histamine H(2) receptor antagonists (cimetidine and ranitidine), antidepressants, antipsychotics, antagonists of benzodiazepines and drugs causing sedation. Rifampicin significantly induced the metabolism of the newer hypnosedatives and decreased their sedative effects, indicating that a dose increase of these agents may be necessary when they are administered with rifampicin. Ketoconazole, erythromycin and cimetidine inhibited the metabolism of the newer hypnosedatives and enhanced their sedative effects, suggesting that a dose reduction may be required. Addition of ethanol to treatment with the newer hypnosedatives resulted in additive sedative effects without altering the pharmacokinetic parameters of the drugs. Compared with some of the conventional benzodiazepines, fewer clinically important interactions appear to have been reported in the literature with zaleplon, zolpidem and zopiclone. The fact that these drugs are newer to the market and have not been as extensively studied as the conventional benzodiazepines may be the reason for this. Another explanation may be a difference in CYP metabolism. While triazolam and midazolam are biotransformed almost entirely via CYP3A4, the newer hypnosedatives are biotransformed by several CYP isozymes in addition to CYP3A4, resulting in CYP3A4 inhibitors and inducers having a lesser effect on their biotransformation.

Pharmacokinetics of oral terbinafine in adult horses.

PubMed

Younkin, T J; Davis, E G; Kukanich, B

2017-08-01

The primary study objective was to compare the pharmacokinetics of p.o. terbinafine alone to p.o. terbinafine administered with p.o. cimetidine in healthy adult horses. The second objective was to assess the pharmacokinetics of terbinafine when administered per rectum in two different suspensions at 30 mg/kg to adult horses. Six healthy adult horses were included in this crossover study. Plasma terbinafine concentrations were quantified with liquid chromatography and mass spectrometry. The half-life (geometric mean) was 8.38 and 10.76 h, for p.o. alone and p.o. with cimetidine, respectively. The mean maximum plasma concentrations were 0.291 μg/mL at 1.54 h and 0.418 μg/mL at 1.28 h for p.o. alone and p.o. with cimetidine, respectively. Terbinafine with cimetidine had an average C MAX 44% higher and the relative F was 153% compared p.o. terbinafine alone, but was not statistically different (P > 0.05). Terbinafine was infrequently detected when administered per rectum in two different suspensions (water or olive oil). Minor adverse effects included oral irritation, fever, and colic. All resolved spontaneously. More pharmacokinetic studies are indicated assessing drug-drug interactions and using multiple dosing intervals to improve our knowledge of effective oral dosing, the potential for drug accumulation, and systemic adverse effect of terbinafine in horses. © 2016 John Wiley & Sons Ltd.

The role of the central histaminergic receptors in the exercise-induced improvements of the spatial learning and memory in rats.

PubMed

Taati, Majid; Moghaddasi, Mehrnoush; Esmaeili, Masoumeh; Pourkhodadad, Soheila; Nayebzadeh, Hassan

2014-10-31

While it is well known that exercise can improve cognitive performance, the underlying mechanisms are not fully understood. There is now evidence that histamine can modulate learning and memory in different types of behavioral tasks. The present study was designed to examine the possible role of central histamine H1 and H2 receptors in forced treadmill running-induced enhancement of learning and memory in rats. For this purpose the animals received intracerebroventricularly chlorpheniramine (H1 receptor blocker) and cimetidine (H2 receptor blocker) before each day of fifteen consecutive days of exercise. Then their learning and memory were tested on the water maze task using a four-trial-per-day for 4 consecutive days. A probe trial was performed after the last training day. Our data showed that cimetidine reversed the exercise-induced improvement in learning and memory in rats; however, this was not the case regarding chlorpheniramine. Our findings indicate that central histamine H2 receptors play an important role in mediating the beneficial effects of forced exercise on learning and memory. Copyright © 2014 Elsevier B.V. All rights reserved.

The role of organic cation transporter 2 inhibitor cimetidine, experimental diabetes mellitus and metformin on gabapentin pharmacokinetics in rats.

PubMed

Benzi, Jhohann Richard de Lima; Yamamoto, Priscila Akemi; Stevens, Jessica Hanna; Baviera, Amanda Martins; de Moraes, Natália Valadares

2018-05-01

We investigated the influence of diabetes mellitus (DM), glycemic control with insulin, cimetidine (Oct2 inhibitor) and metformin (Oct2 substrate) on the kinetic disposition of GAB in rats. Male Wistar rats were divided in five groups and all animals received an oral dose of 50 mg/kg GAB: (vehicle + GAB), cimetidine + GAB (single dose of cimetidine [100 mg/kg] intraperitoneally 1 h before GAB), metformin + GAB (single dose of metformin 100 mg/kg by gavage concomitantly with GAB), DM + GAB (single dose of 40 mg/kg streptozotocin (STZ) intravenously) and DM + GAB + insulin (single dose 40 mg/kg STZ intravenously and 2 IU insulin twice daily for 15 days). Pharmacokinetic analysis was based on plasma and urine data concentrations. No differences in pharmacokinetic parameters were observed between vehicle + GAB × cimetidine + GAB and vehicle + GAB × metformin + GAB groups. Diabetes increased the fraction of GAB excreted unchanged in urine (vehicle + GAB: 0.48 [0.38-0.58]; DM + GAB: 0.83 [0.62-1.04]; DM + GAB + insulin: 0.88 [0.77-0.93]) (mean [95% confidence interval]) without any changes in GAB exposure. Insulin treated diabetic animals showed higher renal clearance compared to control (vehicle + GAB: 0.25 [0.18-0.30] L/h·kg; DM + GAB + insulin: 0.55 [0.45-1.43] L/h·kg), which was attributed to the diabetes-induced glomerular hyperfiltration. Glomerular filtration is the main mechanism of renal excretion of GAB without significant contribution of Oct2 active transport. Copyright © 2018 Elsevier Inc. All rights reserved.

Duodenal pH in health and duodenal ulcer disease: effect of a meal, Coca-Cola, smoking, and cimetidine.

PubMed Central

McCloy, R F; Greenberg, G R; Baron, J H

1984-01-01

Intraluminal duodenal pH was recorded using a combined miniature electrode and logged digitally every 10 or 20 seconds for five hours (basal/meal/drink) in eight control subjects and 11 patients with duodenal ulcer (five on and off treatment with cimetidine). Over the whole test there were no significant differences in duodenal mean pH or log mean hydrogen ion activity (LMHa) between control subjects and patients with duodenal ulcer, but there were significantly longer periods of duodenal acidification (pH less than 4) and paradoxically more periods of duodenal alkalinisation (pH greater than 6) in the duodenal ulcer group compared with controls. After a meal duodenal mean pH and LMHa fell significantly in both controls and patients with duodenal ulcer, with more periods of duodenal acidification and alkalinisation in the duodenal ulcer group. An exogenous acid load (Coca-Cola) significantly increased the periods of duodenal acidification, and reduced alkalinisation, in both groups. Cimetidine significantly increased mean pH and LMHa and abolished the brief spikes of acidification in four of five patients with duodenal ulcer. Peak acid output (but not basal acid output) was significantly correlated with duodenal mean pH and LMHa but not with the periods of duodenal acidification. Smoking did not affect duodenal pH in either group. PMID:6706217

Mefloquine pharmacokinetics in healthy subjects and in peptic ulcer patients after cimetidine administration.

PubMed

Kolawole, J A; Mustapha, A; Abudu-Aguye, I; Ochekpe, N

2000-01-01

The pharmacokinetics of orally administered mefloquine were determined in six healthy male subjects and in six ulcer patients before and after a 3-day course of cimetidine (400 mg morning and evening). Peak plasma concentrations Cmax and AUC0-infinity were similarly and significantly (P < 0.05) increased after cimetidine pretreatement in both healthy subjects and peptic ulcer patients Cmax was increased by 42.4% and 20.5% while AUC0-infinity was increased by 37.5% in healthy and peptic ulcer subjects respectively. The values of t1/2ab absorption and t1/2 beta elimination, total crearance CLT/F and volume of distribution were altered to varying levels after cimetidine treatment but the changes were not statistically significant in both healthy and peptic ulcer subjects. The established long t1/2 beta and this apparent interaction between mefloquine and cimetidine which resulted in increased mefloquine plasma concentration might be of clinical significant in patients with neurological/psychiatric history.

Ranitidine-induced anaphylaxis: clinical features, cross-reactivity, and skin testing.

PubMed

Park, K H; Pai, J; Song, D-G; Sim, D W; Park, H J; Lee, J-H; Jeong, K Y; Pan, C-H; Shin, I; Park, J-W

2016-04-01

Histamine H2 receptor antagonists are commonly prescribed medications and are known to be well tolerated. However, 99 cases of ranitidine-induced anaphylaxis occurred in Korea from 2007 to 2014. The purpose of this study was to determine the incidence, clinical features, and diagnostic methods for ranitidine-induced anaphylaxis. Ranitidine-related pharmacovigilance data from 2007 to 2014 were reviewed. Adverse drug reactions with causal relationships were selected, and clinical manifestations, outcomes, and drug-related information were assessed. For further investigation, 8 years of pharmacovigilance data were collected at a single centre. Twenty-three patients participated in in vivo and in vitro studies. Skin tests, oral provocation tests, and laboratory tests were performed, including tests using other kinds of histamine H2 receptor antagonists. Over 7 years, 584 patients suffered adverse reactions to ranitidine. The most common manifestation was cutaneous symptoms. Among them, 99 patients (17.0%) experienced anaphylaxis. In a single-centre study, skin prick tests were positive in 91.7% of ranitidine-induced anaphylaxis patients (11/12); the optimal concentration was 20 mg/mL. Detection of ranitidine-specific immunoglobulin E failed. Cimetidine and proton pump inhibitors showed no cross-reactivity with ranitidine based on the skin prick test, oral provocation test, or clinical determination. Surprisingly, 82.6% of patients reintroduced ranitidine and re-experienced the same adverse reactions because ranitidine was not considered the culprit drug. Although ranitidine is known as a safe drug, it can also cause diverse adverse reactions, including anaphylaxis. This study demonstrates the need to pay attention to adverse reactions to ranitidine and consider ranitidine as a cause of anaphylaxis. © 2016 John Wiley & Sons Ltd.

Cimetidine-induced Leydig cell apoptosis and reduced EG-VEGF (PK-1) immunoexpression in rats: Evidence for the testicular vasculature atrophy.

PubMed

Beltrame, Flávia L; Cerri, Paulo S; Sasso-Cerri, Estela

2015-11-01

The antiulcer drug cimetidine has shown to cause changes in the testicular microvasculature of adult rats. Since Leydig cells (LCs) produce the pro-angiogenic factor, EG-VEGF (endocrine gland-derived vascular endothelial growth factor), also known as prokineticin 1 (PK-1), this study examined the effect that cimetidine might have on LCs in testes with damaged vasculature. Rats received intraperitoneal injections of 100mg/kg of cimetidine (cimetidine group) or saline vehicle (control group) for 50 days. Serum testosterone levels were measured by chemiluminescence immunoassay and testicular sections were subjected to TUNEL and immunohistochemical reactions for caspase-3, 17β-HSD6, CD163 (ED2 macrophage), PK-1 and androgen receptor (AR). LCs in the cimetidine group showed TUNEL and caspase-3 positive labeling and apoptotic ultrastructural features. Moreover, the presence of 17β-HSD6-positive inclusions inside macrophages and the reduced number of LCs, AR immunoreactivity and serum testosterone levels correlated with a decrease in either the number of PK-1-immunostained LCs or PK-1 immunoreactivity. Although it is not clear which cell type is the primary target of cimetidine in the testicular interstitial compartment, these findings support a direct link between cimetidine-induced testicular vascular atrophy and LCs damage. Copyright © 2015 Elsevier Inc. All rights reserved.

The effects of ketoconazole and cimetidine on the pharmacokinetics of oral tramadol in greyhound dogs.

PubMed

KuKanich, B; KuKanich, K; Black, J

2017-12-01

Tramadol is administered to dogs for analgesia but has variability in its extent of absorption, which may hinder its efficacy. Additionally, the active opioid metabolite (M1) occurs in low concentrations. The purpose of this study was to determine if administration of oral tramadol with suspected metabolism inhibitors (ketoconazole, cimetidine) would lead to improved bioavailability of tramadol and M1. Six healthy Greyhounds were included. They were administered tramadol orally and intravenously, M1 intravenously, oral tramadol with oral ketoconazole and oral tramadol with oral cimetidine. Oral tramadol bioavailability was low (2.6%). Ketoconazole and cimetidine significantly increased tramadol bioavailability to 18.2% and 20.3%, respectively. The mean maximum plasma concentration of tramadol alone was 22.9 ng/ml, and increased to 109.9 and 143.2 μg/ml with ketoconazole and cimetidine, respectively. However, measured tramadol plasma concentrations were below the minimum concentration considered effective in humans (228 μg/ml). In all treatment groups, measured M1 concentrations (<7 μg/ml) were below concentrations associated with efficacy in humans. To conclude, tramadol and M1 concentrations were low and variable in dogs after oral dosing of tramadol, even in combination with cimetidine or ketoconazole, but effective concentrations in dogs have not been defined. © 2017 John Wiley & Sons Ltd.

The effects of cimetidine and antacid on the pharmacokinetic profile of sildenafil citrate in healthy male volunteers

PubMed Central

Wilner, Keith; Laboy, Lucia; LeBel, Marc

2002-01-01

Aims To examine the effect of concomitant cimetidine or antacid administration on the pharmacokinetic profile of sildenafil citrate in healthy male volunteers in two open-label, randomized studies. Methods The first study was a parallel-group design in which 22 healthy male volunteers received sildenafil (50 mg) on days 1 and 5 and cimetidine (800 mg) or placebo on days 3, 4, 5, and 6. Blood samples were collected predose and at specified times up to 48 h postdose on days 1 and 5 to determine plasma levels of sildenafil and its metabolite, UK-103,320. The second study was a two-way crossover design in which 12 volunteers received sildenafil with or without a 30-ml dose of a magnesium hydroxide/aluminium hydroxide antacid. Blood samples were collected and analysed as in the first study. The two study periods were separated by at least 14 days. Results Coadministration of cimetidine had no statistically significant effect on the tmax or kel of sildenafil but caused a statistically significant increase in sildenafil AUCt and Cmax of 56% and 54%, respectively (P<0.01). Differences between the two treatment groups were smaller for the metabolite than for sildenafil, although cimetidine treatment did significantly (P<0.05) increase the AUCt for UK-103,320 by 30%. Antacid coadministration had no statistically significant effect on any pharmacokinetic parameter of sildenafil or UK-103,320. Whether taken alone, with cimetidine, or with an antacid, sildenafil was well tolerated. Most adverse events were mild in nature, and no subject withdrew from either study for any reason related to the drug. Conclusions Cimetidine co-administration produced an increase in sildenafil plasma levels; however, this increase is not sufficient to warrant dosage adjustment of either drug. Antacid coadministration had no effect on the pharmacokinetic profile of sildenafil. PMID:11879257

Omeprazole. A review of its use in Helicobacter pylori infection, gastro-oesophageal reflux disease and peptic ulcers induced by nonsteroidal anti-inflammatory drugs.

PubMed

Langtry, H D; Wilde, M I

1998-09-01

Omeprazole is a well studied proton pump inhibitor that reduces gastric acid secretion. This review examines its use in Helicobacter pylori infection, gastro-oesophageal reflux disease (GORD) with or without oesophagitis and gastrointestinal damage caused by nonsteroidal anti-inflammatory drugs (NSAIDs). Optimal omeprazole regimens for anti-H. pylori therapy are those that administer the drug at a dosage of 40 mg/day (in 1 or 2 divided doses) for 7, 10 or 14 days in combination with 2 antibacterial agents. As a component of 3-drug regimens in direct comparative studies, omeprazole was at least as effective as lansoprazole, pantoprazole, bismuth compounds and ranitidine. However, a meta-analysis suggests that triple therapies with omeprazole are more effective than comparable regimens containing ranitidine, lansoprazole or bismuth. Omeprazole also appears to be successful in triple therapy regimens used in children with H. pylori infection. In patients with acute GORD with oesophagitis, omeprazole is at least as effective as lansoprazole or pantoprazole in promoting healing, and superior to ranitidine, cimetidine or cisapride in oesophagitis healing and symptom relief. Omeprazole was similar to lansoprazole and superior to ranitidine in preventing oesophagitis relapse in patients with all grades of oesophagitis, but may be superior to lansoprazole or pantoprazole in patients with more severe disease. More patients with symptomatic GORD without oesophagitis experienced symptom relief after short term treatment with omeprazole than with ranitidine, cisapride or placebo, and symptoms were more readily prevented by omeprazole than by cimetidine or placebo. Omeprazole was effective in healing and relieving symptoms of reflux oesophagitis in children with oesophagitis refractory to histamine H2 receptor antagonists. Omeprazole is superior to placebo in preventing NSAID-induced gastrointestinal damage in patients who must continue to take NSAIDs. It is also similar to misoprostol and superior to ranitidine in its ability to heal NSAID-induced peptic ulcers and erosions, and superior to misoprostol, ranitidine or placebo in its ability to prevent relapse. In long and short term studies, omeprazole was well tolerated, with diarrhoea, headache, dizziness, flatulence, abdominal pain and constipation being the most commonly reported adverse events. Usual omeprazole dosages, alone or combined with other agents, are 10 to 40 mg/day for adults and 10 to 20 mg/day for children. Omeprazole is a well studied and well tolerated agent effective in adults or children as a component in regimens aimed at eradicating H. pylori infections or as monotherapy in the treatment and prophylaxis of GORD with or without oesophagitis or NSAID-induced gastrointestinal damage.

Clinical pharmacokinetic drug interaction studies of gabapentin enacarbil, a novel transported prodrug of gabapentin, with naproxen and cimetidine

PubMed Central

Lal, Ritu; Sukbuntherng, Juthamas; Luo, Wendy; Vicente, Virna; Blumenthal, Robin; Ho, Judy; Cundy, Kenneth C

2010-01-01

AIM Gabapentin enacarbil, a transported prodrug of gabapentin, provides sustained, dose-proportional exposure to gabapentin. Unlike gabapentin, the prodrug is absorbed throughout the intestinal tract by high-capacity nutrient transporters, including mono-carboxylate transporter-1 (MCT-1). Once absorbed, gabapentin enacarbil is rapidly hydrolyzed to gabapentin, which is subsequently excreted by renal elimination via organic cation transporters (OCT2). To examine the potential for drug–drug interactions at these two transporters, the pharmacokinetics of gabapentin enacarbil were evaluated in healthy adults after administration alone or in combination with either naproxen (an MCT-1 substrate) or cimetidine (an OCT2 substrate). METHODS Subjects (n= 12 in each study) received doses of study drug until steady state was achieved; 1200 mg gabapentin enacarbil each day, followed by either naproxen (500 mg twice daily) or cimetidine (400 mg four times daily) followed by the combination. RESULTS When gabapentin enacarbil was co-administered with naproxen, gabapentin Css,max increased by, on average, 8% and AUC by, on average, 13%. When gabapentin enacarbil was co-administered with cimetidine, gabapentin AUCss increased by 24% and renal clearance of gabapentin decreased. Co-administration with gabapentin enacarbil did not affect naproxen or cimetidine exposure. Gabapentin enacarbil was generally well tolerated. CONCLUSIONS No gabapentin enacarbil dose adjustment is needed with co-administration of naproxen or cimetidine. PMID:20573085

Effect of antacids on predicted steady-state cimetidine concentrations.

PubMed

Russell, W L; Lopez, L M; Normann, S A; Doering, P L; Guild, R T

1984-05-01

The purpose of this study was to evaluate effects of antacids on predicted steady-state concentrations of cimetidine. Ten healthy volunteers received in random order one week apart, cimetidine and cimetidine and antacid suspension. Blood was obtained at specified times and analyzed for cimetidine. Bioavailability was assessed by comparison of peak concentration, time to peak concentration, area under the curve, and time spent over 0.5 micrograms/ml. Single-dose data were extrapolated to steady-state using computer simulation. Concurrent administration of antacid suspension reduced parameters of bioavailability approximately 30%. When steady-state conditions were simulated, concentrations of cimetidine greater than or equal to 0.5 micrograms/ml were maintained for the entire dosing interval in seven of 10 subjects. These data suggest that temporal separation of cimetidine and antacid suspension may be unnecessary.

Cimetidine as a novel adjunctive treatment for early stage Lyme disease.

PubMed

Shemenski, Justin

2016-04-09

Lyme disease, caused by the spirochete Borrelia burgdorferi (Bb), is the most common vector-borne illness in the United States. It is a complex disease which may affect the skin, joints, heart, eyes, and central nervous system. Prompt diagnosis and treatment is curative in most instances. However, a significant percentage of patients experience ongoing symptoms after treatment. Currently, there is much controversy regarding the diagnosis, pathophysiology, and treatment of Lyme disease. Pathogen persistence despite treatment lies at the heart of this debate. Many believe that the ongoing symptoms are due to factors such as autoimmunity or permanent damage that is incurred during the active infection. However, there is an emerging school of thought that states that ongoing symptoms are due to a persistent infection that is able to survive both the immune response and antibiotic therapy. Numerous studies have shown that Bb can indeed persist within the host despite treatment and several mechanisms have been proposed to explain Bb's persistence capabilities. These include: polymorphism, antigenic variance, biofilm formation, persister cells, and immunomodulation. There is evidence that Bb is able to alter cytokine profiles within the host which may allow the organism to survive the immune response. This immunomodulation follows a pattern of T-helper 1 (TH1) suppression in favor of T-helper 2 (TH2) processes. In contrast, it has been shown that the optimal immune response to Bb infection involves an early, robust TH1 response and a later conversion to TH2 dominance once the infection is controlled or cleared. It has been proposed that a reconstitution of proper immune-competency in the infected host may improve clinical outcomes in Lyme disease. Cimetidine (CIM) is an over-the-counter histamine-2 (H2) antagonist that is primarily used to lower acid secretions in the stomach. T-regulatory (Treg) cells also possess the H2 receptor, which has spurred interest in CIM as a potential immunomodulator. CIM therapy has been shown to increase levels of the TH1 associated cytokines IL-12, TNF-α, and IFN-γ while decreasing levels of the TH2 associated cytokine IL-10. The author proposes a novel theory that CIM therapy during early Bb infection may promote a more appropriate immune response and increase the utility of antibiotic therapy during early stage Lyme disease, thus improving clinical outcomes of the disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evidence of anti-oxidant role of sucralfate in gastric mucosal protection.

PubMed

Laudanno, O M; Bedini, O A; Cesolari, J A; San Miguel, P

1990-02-01

Six percent hydrogen peroxide (H2O2) was used as a generator of the *OH free radical, and as an aggressor of gastric mucosa, in 100 Wistar rats. The mucosal cytoprotector effect of sucralfate, misoprostol, enprostil, cimetidine, ranitidine, famotidine and 10% aluminum sulphate yielded almost complete macroscopic and histological protection to the gastric mucosa. Misoprostol or enprostil gave partial protection whereas the H2 blockers aggravated the gastric necrotic lesions produced by the H2O2. We conclude that sucralfate is a true anti-oxidant that protects the gastric mucosa through its aluminum and sulphydril components, the increment of gastric mucins and endogenous PGs.

Substrate-immobilized electrospun TiO2 nanofibers for photocatalytic degradation of pharmaceuticals: The effects of pH and dissolved organic matter characteristics.

PubMed

Maeng, Sung Kyu; Cho, Kangwoo; Jeong, Boyoung; Lee, Jaesang; Lee, Yunho; Lee, Changha; Choi, Kyoung Jin; Hong, Seok Won

2015-12-01

A substrate-immobilized (SI) TiO2 nanofiber (NF) photocatalyst for multiple uses was prepared through electrospinning and hot pressing. The rate of furfuryl alcohol degradation under UV irradiation was found to be the highest when the anatase to rutile ratio was 70:30; the rate did not linearly increase as a function of the NF film thickness, mainly due to diffusion limitation. Even after eight repeated cycles, it showed only a marginal reduction in the photocatalytic activity for the degradation of cimetidine. The effects of pH and different organic matter characteristics on the photodegradation of cimetidine (CMT), propranolol (PRP), and carbamazepine (CBZ) were investigated. The pH-dependence of the photocatalytic degradation rates of PRP was explained by electrostatic interactions between the selected compounds and the surface of TiO2 NFs. The degradation rates of CMT showed the following order: deionized water > l-tyrosine > secondary wastewater effluent (effluent organic matter) > Suwannee River natural organic matter, demonstrating that the characteristics of the dissolved organic matter (DOM) can affect the photodegradation of CMT. Photodegradation of CBZ was affected by the presence of DOM, and no significant change was observed between different DOM characteristics. These findings suggest that the removal of CMT, PRP, and CBZ during photocatalytic oxidation using SI TiO2 NFs is affected by the presence of DOM and/or pH, which should be importantly considered for practical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

The use of cimetidine in hospitalized patients.

PubMed

Kopala, L

1984-01-01

Cimetidine is the most commonly prescribed drug in North America. A clinical review was conducted to identify physicians' prescribing habits. From September 1, 1981 to March 31, 1982, the charts were reviewed of 50 patients receiving cimetidine in an isolated coastal community hospital in British Columbia. It was discovered that physicians prescribed the drug for reasons approved by the Food and Drug Administration (FDA) only 14% of the time. The FDA guidelines approve cimetidine for duodenal ulcer, Zollinger-Ellison syndrome, and other hypersecretory states. A literature review was conducted, and guidelines on prescribing cimetidine were given to all members of the hospital's medical staff.

Cysteamine-colon and cysteamine-duodenum lesions in rats. Attenuation by gastric pentadecapeptide BPC 157, cimetidine, ranitidine, atropine, omeprazole, sulphasalazine and methylprednisolone.

PubMed

Sikiric, P; Seiwerth, S; Grabarevic, Z; Balen, I; Aralica, G; Gjurasin, M; Komericki, L; Perovic, D; Ziger, T; Anic, T; Prkacin, I; Separovic, J; Stancic-Rokotov, D; Lovric-Bencic, M; Mikus, D; Staresinic, M; Aralica, J; DiBiaggio, N; Simec, Z; Turkovic, B; Rotkvic, I; Mise, S; Rucman, R; Petek, M; Sebecic, B; Ivasovic, Z; Boban-Blagaic, A; Sjekavica, I

2001-01-01

Recently, we showed cysteamine-duodenal lesions without gastric acid, since they were induced also in gastrectomized rats, as in naive rats, and they were inhibited by the novel stomach pentadecapeptide BPC 157 as well as standard antiulcer drugs (i.e. cimetidine, ranitidine, omeprazole, bromocriptine, atropine). Therefore, as an advantage of considering cysteamine as a directly acting cytotoxic agent and mentioned agents as direct cytoprotective agents, the present focus was on the ulcerogenic effect of cysteamine and protective effect of gastroduodenal antiulcer agents outside upper gastrointestinal tract (i.e. in colon). Intrarectal administration of the cysteamine (200 or 400 mg/kg b.w) produced severe colon lesions (i.e. transmural inflammation with serosal involvement) in rats (30 min-72 h-experimental period), apparently distinctive from smaller lesions after non-specific irritant enema [diluted HCl solution, pH 3.8 (adjusted to pH of cysteamine solution (pH 3.8)]. All of the tested antiulcer agents were applied simultaneously with cysteamine enema (8 cm from the anus, in a volume of the 1.0 ml/rat) intraperitoneally (i.p.), intragastrically (i.g.) or intrarectally (i.r.). Pentadecapeptide BPC 157 (10 microg or 10 ng/kg b.w.), given in either regimen, previously shown to have, besides others, a particular beneficial activity just in the intestinal mucosa, inhibited these cysteamine colon lesions (assessed after 30 min, 60 min, 180 min, 24 h, 48 h, 72 h following cysteamine in a dose of either 200 or 400 mg/kg i.r.). Cysteamine-colon lesions were also attenuated by standard antiulcer agents (mg/kg b.w.), given i.p., i.g., or i.r., such as ranitidine (10), cimetidine (50), omeprazole (10), atropine (10), together with methylprednisolone (1), and sulphasalazine (50, i.r.), assessed 30 min following application of 200 mg of cysteamine. Finally, standard cysteamine duodenal lesions (assessed 24 h after a subcutaneous application of 400 mg/kg of cysteamine) were also attenuated by these agents application (given in the same doses, i.p., 1 h before cysteamine), with only exception to sulphasalazine. Thus, the extended cysteamine specific ulcerogenic effect, cysteamine colon/duodenum lesion-link and an extenuation of agents protection from upper to lower part of gastrointestinal tract (i.e. stomach pentadecapeptide BPC 157, standard antiulcer agents, cimetidine, ranitidine, atropine, omeprazole) and vice versa (remedies for inflammatory bowel disease) evidenced in the present study may be potentially important for both further experimental and clinical research.

Potential influence of tubular dysfunction on the difference between estimated and measured glomerular filtration rate after kidney transplantation.

PubMed

Lezaic, V; Mirkovic, D; Ristic, S; Radivojevic, D; Dajak, M; Naumovic, R; Marinkovic, J; Djukanovic, L J

2013-05-01

Because no consensus exists regarding the most accurate calculation to estimate glomerular filtration rate (GFR) based on serum creatinine concentrations (sCr) after kidney transplantation, this study sought to assess the potential role of tubular dysfunction on GFR estimates using various equations as well as the effect of pharmacologic blockades on tubular secretion of creatinine on creatinine clearance (ClCr). Iohexol GFR (mGFR) was performed in 17 stable kidney transplant recipients(R) at >24 months post-transplantation. Their mean age was 48.3 ± 11.3 years. All R were treated with a calcineurin inhibitor (CNI). At the time of study we measured sCr, 24 hour-ClCr, cystatin C, 24-hour proteinuria, microalbuminuria, FE Na, alfa1-microglobulinuria (alfa1-MG), and CNI concentrations. To block tubular secretion of Cr, recipients were prescribed cimetidine (2400 mg) 2 days before the sCr measurement. Additionally, to exclude dietary influences on sCr, R did not eat meat for 2 days before testing. GFR was estimated using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockroft-Gault (C&G), and Cystatin C (Cyst C) GFR equations. Mean kidney graft function over the previous 6 months was used as the control. Pearson correlation was determined between the differences between mGFR and estimatedGFR: Iohexol minus MDRD, EPI, Cyst C or C&G GFR for paired estimates. The diagnostic accuracy of the eGFRs to detect an mGFR of 60 mL/min/1.73 m(2) was examined by receiver operating characteristic curves. Mean mGFR was 75.2 ± 35.8 mL/min/1.73 m(2). The sCr increased but the 24-hour ClCr, MDRD, EPI, and C&G decreased after vs before cimetidine. The difference was significant for sCr (F = 12.933; P = .002) and MDRD GFR (F = 15.750; P = .001). mGFR was not significantly higher than all pair values of eGFRs, and not significantly lower than 24-hour ClCr before and after cimetidine. However, in comparison to all eGFRs, ClCr after cimetidine most approached mGFR. A significant positive correlation was observed between alfa1-MG and the difference between mGFR and MDRD (before, r = .543 [P = .045]; after cimetidine, 0.568 [P = .034]), EPI (before, r = 0.516 [P = .050]; after cimetidine, r = 0.562 [P = .036]), and ClCr (r = 0.633; P = .016), C&G (P = .581; P = .029) before cimetidine. Accuracy of eGFRs to detect mGFR of 60 mL/min/1.73 m(2) showed EPI GFR before cimetidine to show diagnostic accuracy for patients with GFR >60 mL/min/1.73 m(2) with a sensitivity of 81.8% and a specificity of 71.4%. Because mGFR is unavailable in many transplant centers, determination of ClCr after cimetidine may help to achieve a more accurate diagnosis of CKD among transplant patients. Copyright © 2013 Elsevier Inc. All rights reserved.

The effect of pentadecapeptide BPC 157, H2-blockers, omeprazole and sucralfate on new vessels and new granulation tissue formation.

PubMed

Sikiric, P; Separovic, J; Anic, T; Buljat, G; Mikus, D; Seiwerth, S; Grabarevic, Z; Stancic-Rokotov, D; Pigac, B; Hanzevacki, M; Marovic, A; Rucman, R; Petek, M; Zoricic, I; Ziger, T; Aralica, G; Konjevoda, P; Prkacin, I; Gjurasin, M; Miklic, P; Artukovic, B; Tisljar, M; Bratulic, M; Mise, S; Rotkvic, I

1999-12-01

A clear protection of the gastrointestinal tract and an evident anti-inflammatory effect were shown for a novel stomach pentadecapeptide BPC 157 (i.p./i.g.) in comparison with several reference standards in various ulcer models along with a protection of endothelium and particular interaction with the NO-system. Thus, we evaluated whether this pentadecapeptide along with other gastroprotective agents could affect angiogenesis and the healing process in vivo using a procedure initially described by Szabo and co-workers. In each rat, two sterile sponges (1 x 1 x 0.25 cm; V = 0.25 mL) with the same quantities of BPC 157 (10 ng x mL(-1), 10 microg x mL(-1), 50 microg x kg(-1)) or reference agents (cimetidine: 10, 100, 500 mg x mL(-1); ranitidine: 2.5, 25, 250 mg x mL(-1); famotidine: 10, 50, 100 mg x mL(-1); omeprazole: 10, 50, 100 mg x mL(-1); sucralfate: 1, 5, 10 mg x mL(-1) were implanted subcutaneously in the lumbar region. The sponges were removed after 3 or 7 d, fixed in formalin, and processed for histologic and histochemical evaluation and morphometry assessment. Compared with the control values, the number of newly formed endothelial spaces inside newly formed granulation tissue was markedly increased in all animals treated with BPC 157, cimetidine, ranitidine, famotidine, sucralfate and omeprazole, a consistent finding noted after either 3 or 7 d. Compared with control values, markedly more granulation tissue was noted in the rats in the groups of animals treated with BPC 157 (50 microg) and in the rats treated with sucralfate in all dosages used, euthanized after 3 d. In all groups treated with H2-blockers however, similar values to those of controls were noted. Thus, it could be concluded that an evident angiogenic property was consistently noted for the novel pentadecapeptide BPC 157, H2-blockers (cimetidine, famotidine and ranitidine) and omeprazole, besides the well known angiogenic effect of sucralfate. Furthermore, unlike H2-blockers and omeprazole, BPC 157 stimulates the formation of granulation tissue, suggesting a particular activity, similar to that previously noted for sucralfate.

The Use of Cimetidine in Hospitalized Patients

PubMed Central

Kopala, Lili

1984-01-01

Cimetidine is the most commonly prescribed drug in North America. A clinical review was conducted to identify physicians' prescribing habits. From September 1, 1981 to March 31, 1982, the charts were reviewed of 50 patients receiving cimetidine in an isolated coastal community hospital in British Columbia. It was discovered that physicians prescribed the drug for reasons approved by the Food and Drug Administration (FDA) only 14% of the time. The FDA guidelines approve cimetidine for duodenal ulcer, Zollinger-Ellison syndrome, and other hypersecretory states. A literature review was conducted, and guidelines on prescribing cimetidine were given to all members of the hospital's medical staff. PMID:21283494

Treatment of 'cimetidine-resistant' chronic duodenal ulcers with ranitidine or cimetidine: a randomised multicentre study.

PubMed Central

Quatrini, M; Basilisco, G; Bianchi, P A

1984-01-01

Forty patients with endoscopically proven persistent duodenal ulcer who had been treated for six weeks with cimetidine (1 g/day) were randomly allocated to receive a further six weeks' treatment with cimetidine (1 g/day) or ranitidine (300 mg/day). Ulcers healed in 12 of 19 patients given cimetidine (63%) and in 13 of 21 given ranitidine (62%); two patients on cimetidine and two on ranitidine dropped out. In the unhealed ulcer group the ulcer size was reduced in most patients. There was no change in basal acid output, peak acid output, plasma gastrin and pepsinogen I levels after either treatment. Clinical data, gastric function tests, and endoscopic features did not predict ulcer healing. Both treatments were effective in the relief of pain: 72% of patients with unhealed ulcers were asymptomatic at the end of the trial. PMID:6090280

Adverse effects reported in the use of gastroesophageal reflux disease treatments in children: a 10 years literature review

PubMed Central

Cohen, Shlomi; Bueno de Mesquita, Mirjam; Mimouni, Francis B

2015-01-01

Gastroesophageal reflux (GER) is commonly observed in children, particularly during the first year of life. Pharmacological therapy is mostly reserved for symptomatic infants diagnosed with GER disease (GERD), usually as defined in a recent consensus statement. The purpose of the present article was to review the reported adverse effects of pharmacological agents used in the treatment of paediatric GERD. We conducted this review using the electronic journal database Pubmed and Cochrane database systematic reviews using the latest 10-year period (1 January 2003 to 31 December 2012). Our search strategy included the following keywords: omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole, rantidine, cimetidine, famotidine, nizatidine, domperidone, metoclopramide, betanechol, erythromycin, baclofen, alginate. We used Pubmed’s own filter of: ’child: birth–18 years’. All full articles were reviewed and we only included randomized controlled trials retrieved from our search. We addressed a summary of our search on a drug-by-drug basis with regard to its mechanism of action and clinical applications, and reviewed all of the adverse effects reported and the safety profile of each drug. Adverse effects have been reported in at least 23% of patients treated with histamine H2 receptor antagonists (H2RAs) and 34% of those treated with proton pump inhibitors (PPIs), and mostly include headaches, diarrhoea, nausea (H2RAs and PPIs) and constipation (PPIs). Acid suppression may place immune-deficient infants and children, or those with indwelling catheters, at risk for the development of lower respiratory tract infections and nosocomial sepsis. Prokinetic agents have many adverse effects, without major benefits to support their routine use. PMID:25752807

Cimetidine attenuates vinorelbine-induced phlebitis in mice by militating E-selectin expression.

PubMed

Wang, Zhuo; Ma, Lijuan; Wang, Xuebin; Cai, Heping; Huang, Jin; Liu, Jiyong; Hu, Jinhong; Su, Dingfeng

2014-08-01

We investigated E-selectin expression in mice and rabbits with vinorelbine-induced phlebitis and the effect of cimetidine. To find the relationship between E-selectin expression and vinorelbine-induced phlebitis. Mouse and rabbit model of vinorelbine-induced phlebitis was established by intravenous infusion of vinorelbine. Pathological observation, molecular-biological determination of E-selectin and protein function of it was evaluated. Grossly, we observed swelling, edema and cord-like vessel changes in mice receiving vinorelbine but only mild edema in mice pretreated with cimetidine. Pathological scoring yielded a total score of 37 for vinorelbine-treated mice and 17 for mice pretreated with cimetidine (P < 0.05). ELISA revealed that rabbits treated with vinorelbine had markedly higher serum contents of E-selectin than normal saline (NS) controls (vinorelbine 1.534 ± 0.449 vs. NS 0.746 ± 0.170 ng/mL, P < 0.05), which was markedly attenuated by cimetidine (cimetidine 0.717 ± 0.468 vs. vinorelbine 1.534 ± 0.449 ng/mL, P < 0.05). Rose Bengal staining assays showed that vinorelbine markedly increased the adhesion rate of neutrophils for endothelial cells (vinorelbine 38.70 ± 8.34% vs. controls 8.93 ± 4.85%, P < 0.01), which, however, was significantly suppressed by cimetidine (9.93 ± 5.91%, P < 0.01 vs. vinorelbine). In E-selectin knockout mice, we found no apparent difference in tail swelling in mice receiving vinorelbine or cimetidine and vinorelbine. In conclusion, cimetidine attenuates vinorelbine-induced phlebitis in mice probably by suppressing increased expression of E-selectin.

Spectroscopic studies on the interaction of cimetidine drug with biologically significant σ- and π-acceptors

NASA Astrophysics Data System (ADS)

Pandeeswaran, M.; Elango, K. P.

2010-05-01

Spectroscopic studies revealed that the interaction of cimetidine drug with electron acceptors iodine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted through the initial formation of ionic intermediate to charge transfer (CT) complex. The CT-complexes of the interactions have been characterized using UV-vis, 1H NMR, FT-IR and GC-MS techniques. The formation of triiodide ion, I 3-, is further confirmed by the observation of the characteristic bands in the far IR spectrum for non-linear I 3- ion with C s symmetry at 156 and 131 cm -1 assigned to νas(I-I) and νs(I-I) of the I-I bond and at 73 cm -1 due to bending δ(I 3-). The rate of formation of the CT-complexes has been measured and discussed as a function of relative permittivity of solvent and temperature. The influence of relative permittivity of the medium on the rate indicated that the intermediate is more polar than the reactants and this observation was further supported by spectral studies. Based on the spectroscopic results plausible mechanisms for the interaction of the drug with the chosen acceptors were proposed and discussed and the point of attachment of the multifunctional cimetidine drug with these acceptors during the formation of CT-complex has been established.

Effect of grapefruit juice or cimetidine coadministration on albendazole bioavailability.

PubMed

Nagy, J; Schipper, H G; Koopmans, R P; Butter, J J; Van Boxtel, C J; Kager, P A

2002-03-01

The assumed metabolic breakdown of albendazole by mucosal CYP3A4 enzymes was studied by coadministering albendazole (10 mg/kg) with grapefruit juice. Concentrations of albendazole sulfoxide (ABZSX), the active metabolite of albendazole, were compared with those after albendazole was administered with water, a fatty meal, or grapefruit juice plus cimetidine (10 mg/kg). In comparison to water, maximum ABZSX concentration (Cmax) was enhanced 6.5-fold by a fatty meal (from 0.24 +/- 0.09 mg/l to 1.55 +/- 0.30 mg/l; mean +/- SD; P < 0.001) and 3.2-fold by grapefruit juice (from 0.24 +/- 0.09 mg/l to 0.76 +/- 0.37 mg/L; P = 0.031). When grapefruit juice was combined with cimetidine, Cmax was significantly lower than with grapefruit juice alone (0.41 +/- 0.29 mg/l and 0.76 +/- 0.37 mg/l, respectively; P = 0.022). The area under the concentration-time curve from 0 to infinity (AUC(0-omega)) followed a comparable pattern. Half-life (T(1/2)) was 8.8 +/- 4.2 hr and 8.2 +/- 4.3 hr after administration with water or a fatty meal (P = 1.000). Grapefruit juice shortened T(1/2) by 46% (P = 0.026). We hypothesize that albendazole is metabolized by CYP3A4 enzymes in the intestinal mucosa. This process can be inhibited by grapefruit juice. Cimetidine decreased albendazole bioavailability.

Severe ranitidine-induced anaphylaxis: a case report and literature review.

PubMed

Aouam, K; Bouida, W; Ben Fredj, N; Chaabane, A; Boubaker, H; Boukef, R; Boughattas, N A; Nouira, S

2012-08-01

Ranitidine is a generally well-tolerated drug, and serious side effects are rare. However, ranitidine-induced anaphylaxis has been reported on rare occasions. We report on such a case and review other cases reported in the literature. A 36-year-old man with no history of other medications, illnesses or allergic diseases, especially to drugs, consulted our emergency department because of renal colic and epigastric discomfort. He was given 50 mg of ranitidine as a slow intravenous bolus and 20 mg of piroxicam intramuscularly. Within the first minute, the patient developed a cold sweat, trembling, dyspnoea and deterioration of his consciousness. The condition was considered as an anaphylactic shock, and cardiopulmonary resuscitation and inotropic support were immediately commenced. Two days later, he was weaned off the ventilator as he was haemodynamically stable. He was discharged after 7 days. Four weeks later, skin prick tests to ranitidine and piroxicam were performed on the forearm of the patient. He reacted strongly to ranitidine about 10 min later but not to piroxicam. To assess cross-reactivity to other H2- and H1-receptor antagonists in our patient, we subsequently performed prick tests to famotidine, cimetidine and desloratadine and all were negative. We re-emphasize a potentially serious, albeit very rare, adverse effect of ranitidine and summarize other reported cases. This case demonstrates that commonly used, generally safe drugs may on occasions cause serious adverse effects. © 2011 Blackwell Publishing Ltd.

[Involvement of cross interaction between central cholinergic and histaminergic systems in the nucleus tractus solitarius in regulating carotid sinus baroreceptor reflex].

PubMed

Hu, Li-Xun; Zhang, Guo-Xing; Zhang, Yu-Ying; Zhao, Hong-Fen; Yu, Kang-Ying; Wang, Guo-Qing

2013-12-25

The carotid sinus baroreceptor reflex (CSR) is an important approach for regulating arterial blood pressure homeostasis instantaneously and physiologically. Activation of the central histaminergic or cholinergic systems results in CSR functional inhibitory resetting. However, it is unclear whether two systems at the nucleus tractus solitarius (NTS) level display cross interaction to regulate the CSR or not. In the present study, the left or right carotid sinus region was isolated from the systemic circulation in Sprague-Dawley rats (sinus nerve was reserved) anesthetized with pentobarbital sodium. Respective intubation was conducted into one side isolated carotid sinus and into the femoral artery for recording the intracarotid sinus pressure (ISP) and mean arterial pressure (MAP) simultaneously with pressure transducers connection in vivo. ISP was set at the level of 0 mmHg to eliminate the effect of initial internal pressure of the carotid sinus on the CSR function. To trigger CSR, the ISP was quickly elevated from 0 mmHg to 280 mmHg in a stepwise manner (40 mmHg) which was added at every step for over 4 s, and then ISP returned to 0 mmHg in similar steps. The original data of ISP and corresponding MAP were fitted to a modified logistic equation with five parameters to obtain the ISP-MAP, ISP-Gain relationship curves and the CSR characteristic parameters, which were statistically compared and analyzed separately. Under the precondition of no influence on the basic levels of the artery blood pressure, the effects and potential regulatory mechanism of preceding microinjection with different cholinoceptor antagonists, the selective cholinergic M1 receptor antagonist, i.e., pirenzepine (PRZ), the M2 receptor antagonist, i.e., methoctramine (MTR) or the N1 receptor antagonist, i.e., hexamethonium (HEX) into the NTS on the changes in function of CSR induced by intracerebroventricular injection (i.c.v.) of histamine (HA) in rats were observed. Meanwhile, the actions and possible modulatory mechanism of preceding microinjection with different histaminergic receptor antagonists, the selective histaminergic H1 receptor antagonist, i.e., chlorpheniramine (CHL) or the H2 receptor antagonist, i.e., cimetidine (CIM) into the NTS on the changes in function of CSR resulted from the i.c.v. cholinesterase inhibitor, physostigmine (PHY) were also examined in order to confirm and to analyze effects of cross interaction between central histaminergic and cholinergic systems on CSR. The main results obtained are as follows. (1) Standalone microinjection of different selective cholinergic receptor antagonists (PRZ, MTR or HEX) or different selective histaminergic receptor antagonists (CHL or CIM) into the NTS with each given dose had no effects on the CSR function and on the basic levels of the artery blood pressure, respectively (P > 0.05). (2) The pretreatment of PRZ or MTR into the NTS with each corresponding dose could attenuate CSR resetting resulted from i.c.v. HA in some degrees, which remarkably moved the posterior half range of ISP-MAP relationship curve downwards (P < 0.05), shifted the middle part of ISP-Gain relationship curve upwards (P < 0.05), and increased reflex parameters such as the MAP range and maximum gain (P < 0.05), but decreased parameters such as saturation pressure and intracarotid sinus pressure at maximum gain (P < 0.05). The catabatic effects of pretreatment with MTR into the NTS on CSR resetting induced by i.c.v. HA were more obvious than those with PRZ (P < 0.05), but pretreatment of HEX with given dose into the NTS had no effects on CSR resetting induced by i.c.v. HA (P > 0.05). (3) The effects of pretreatment of CHL or CIM into the NTS with each corresponding dose on CSR resetting made by i.c.v. PHY were similar to those of pretreatment of PRZ or MTR into the NTS on CSR resetting resulted from i.c.v. HA, and the decreasing effects of pretreatment with CHL into the NTS on CSR resetting induced by i.c.v. PHY were more remarkable than those with CIM (P < 0.05). These findings suggest that CSR resetting resulted from either HA or PHY into the lateral ventricle may partly involve the descending histaminergic or cholinergic pathway from the hypothalamus to NTS, which might evoke a cross activation of the cholinergic system in the NTS, via cholinergic M1 and M2 receptors mediation, especially the M2 receptors showing actions, or trigger another cross activation of the histaminergic system in the NTS, by histaminergic H1 and H2 receptors mediation, especially the H1 receptors displaying effects.

Protective Effect of Active Immunization with Purified Escherichia coli Heat-Labile Enterotoxin in Rats

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.

1979-01-01

The protective effect of active immunization by different routes with a purified preparation of the polymyxin-release form of Escherichia coli heat-labile toxin was evaluated in rats. Immunized animals were challenged by placing toxin into ligated ileal loops at dosages which produced either 50% or the maximum secretory response in unimmunized rats. Immunization exclusively by the parenteral route yielded significant protection. Rats were also protected when parenteral priming was followed by boosting given either directly into the duodenum or perorally 2 h after intragastric cimetidine, but not when the peroral boosts were given with bicarbonate. Immunization administered entirely by the peroral route with cimetidine yielded protection but only when the immunizing dosage was fivefold greater than that found effective in the parenteral-peroral approach. Rats immunized exclusively by the parenteral route and those boosted perorally with cimetidine were also tested, and found to be protected, against challenge with viable organisms of strains that produce either heat-labile toxin alone or both heat-labile and heat-stable toxin, but they were not protected against a strain which produces just heat-stable toxin. Geometric mean serum antibody titers were increased by 16-fold or more over control values in those groups of rats in which protection was achieved, with the exception of those immunized exclusively by the peroral route. These observations demonstrate that (i) active immunization with purified E. coli heat-labile toxin results in significant protection against both this toxin as well as viable organisms which produce it, but not against viable strains which produce heat-stable toxin only, and (ii) concomitant ablation of gastric secretion by the use of cimetidine renders the peroral route of immunization effective. They suggest that prophylactic immunization against diarrheal disease caused by heat-labile toxin-producing strains of E. coli may be feasible in humans. PMID:378831

Cimetidine and hepatic blood flow in polytrauma patients.

PubMed

Ivatury, R R; Khan, M B; Nallathambi, M; Davis, K; Stahl, W M

1985-05-01

Recent reports suggest that cimetidine acutely reduces liver blood flow in normal healthy subjects. To determine whether this finding is applicable to critically ill patients, we studied nine polytrauma patients admitted to a surgical ICU. All patients were being monitored with pulmonary artery catheters; all were stable with normal liver function. Liver blood flow was estimated by indocyanine green clearance, before and after administration of a single dose of 600 mg cimetidine. Hemodynamic variables were measured at the same times. Cimetidine did not significantly alter either hepatic blood flow or cardiovascular status in these critically ill patients.

Effect of cimetidine and antacid on gastric microbial flora.

PubMed Central

Snepar, R; Poporad, G A; Romano, J M; Kobasa, W D; Kaye, D

1982-01-01

The effect of a standard regimen of cimetidine on the gastric flora of 20 male volunteers was studied in a double-blind manner and compared with the effects of a standard antacid regimen. Postprandial microbial titers in gastric aspirates were significantly higher at 4, 8, and 16 weeks of therapy in subjects taking antacids and at 4 weeks in subjects taking cimetidine when compared with their pretreatment titers. Although not significant, there was a tendency for fasting microbial titers to be higher in subjects receiving cimetidine as compared with pretreatment titers. The higher titers were primarily related to increases in survival of mouth flora (viridans streptococci and Neisseria spp.); Enterobacteriaceae and other nitrate-reducing organisms were unusual isolates. There was no significant difference in the total titers or types of organisms isolated when subjects taking cimetidine were compared with those taking antacid. PMID:7085070

Influence of cimetidine and diethyldithiocarbamate on the metabolism of halothane and methoxyflurane in vitro.

PubMed

Loesch, J; Siegers, C P; Younes, M

1987-06-01

The metabolism of halothane and methoxyflurane was measured in vitro by the vial equilibration method using the S-9-fraction from rat liver as source of enzymes. Kinetic values were measured for halothane: Vmax = 11.6 nmol/g.min, KM = 19.6 mumol/l and methoxyflurane: Vmax = 12.0 nmol/g.min, KM = 17.5 mumol/l. Dithiocarb showed strong inhibitory activity on halothane and methoxyflurane metabolism; inhibition constants were calculated as Ki = 0.051 mmol/l and Ki = 0.004 mmol/l, respectively. Cimetidine inhibited the metabolism of both anesthetics to a lesser extent. Inhibition constants were calculated as Ki = 16.2 mmol/l and Ki = 8.2 mmol/l for halothane and methoxyflurane, respectively. The observed inhibitory properties of dithiocarb and cimetidine on the metabolism of halothane and methoxyflurane may be of interest in connection with the problem of toxic liver and kidney injury after anesthesia with these agents.

[Empirical studies on some drugs for patent lawsuits in the age of manufacturing patents].

PubMed

Yamakawa, Koji; Nishitani, Kiyoshi

2009-01-01

Empirical studies on patent lawsuits for some drugs by author (K.Y.) from 1953-1998, are described. Case 1: One of the authors (K.Y.) clarified that silylmethylation of a penicillin derivative gave either N, O-disilylmethylated product or O-monosilylmethylated product. However, only O-silylmethylated product was obtained after the usual work-up (Fig. 1). Case 2: A point under discussion of the trial is whether the reported manufacturing process of "metoclopramide" is possible or not. One of the authors (K. Y.) clarified the possibility by means of a careful synthetic experiment (Fig. 2). Case 3: The essential effective structure of herbicides, Roundup (Monsanto Co.) and Sulfosate (Stoph Co.), was the same in highly diluted solution (Fig. 3). Case 4: Cimetidine has been prepared by the Oxy procedure (SKB Co.), but another cimetidine (Fujimoto Co.) was prepared by the Lek procedure. Is it true? Experimental preparations of both cimetidines by the respective Oxy and Lek processes, were achieved by the authors. The cimetidine in the tablet named "Cylock" by Fujimoto Pharm. Co., Ltd. should be manufactured by the Oxy process on the basis of the by-products analysis (Fig. 4). Finally, a short history of patents in Japan from 1899-1975 is described.

Scombroid poisoning: prompt resolution of symptoms with cimetidine.

PubMed

Blakesley, M L

1983-02-01

Ingestion of tainted fish of the tuna class may result in the toxic erythema and histamine overload of scombroid poisoning. We report four cases in which prompt resolution of symptoms was achieved by administration of intravenous cimetidine, with minimal side effects. A search of the literature failed to locate previous reports of the efficacy of cimetidine in the treatment of this syndrome.

Evaluation of the transporter-mediated herb-drug interaction potential of DA-9801, a standardized dioscorea extract for diabetic neuropathy, in human in vitro and rat in vivo.

PubMed

Song, Im-Sook; Kong, Tae Yeon; Jeong, Hyeon-Uk; Kim, Eun Nam; Kwon, Soon-Sang; Kang, Hee Eun; Choi, Sang-Zin; Son, Miwon; Lee, Hye Suk

2014-07-17

Drug transporters play important roles in the absorption, distribution, and elimination of drugs and thereby, modulate drug efficacy and toxicity. With a growing use of poly pharmacy, concurrent administration of herbal extracts that modulate transporter activities with drugs can cause serious adverse reactions. Therefore, prediction and evaluation of drug-drug interaction potential is important in the clinic and in the drug development process. DA-9801, comprising a mixed extract of Dioscoreae rhizoma and Dioscorea nipponica Makino, is a new standardized extract currently being evaluated for diabetic peripheral neuropathy in a phase II clinical study. The inhibitory effects of DA-9801 on the transport functions of organic cation transporter (OCT)1, OCT2, organic anion transporter (OAT)1, OAT3, organic anion transporting polypeptide (OATP)1B1, OATP1B3, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP) were investigated in HEK293 or LLC-PK1 cells. The effects of DA-9801 on the pharmacokinetics of relevant substrate drugs of these transporters were also examined in vivo in rats. DA-9801 inhibited the in vitro transport activities of OCT1, OCT2, OAT3, and OATP1B1, with IC50 values of 106, 174, 48.1, and 273 μg/mL, respectively, while the other transporters were not inhibited by 300 μg/mL DA-9801. To investigate whether this inhibitory effect of DA-9801 on OCT1, OCT2, and OAT3 could change the pharmacokinetics of their substrates in vivo, we measured the pharmacokinetics of cimetidine, a substrate for OCT1, OCT2, and OAT3, and of furosemide, a substrate for OAT1 and OAT3, by co-administration of DA-9801 at a single oral dose of 1,000 mg/kg. Pre-dose of DA-9801 5 min or 2 h prior to cimetidine administration decreased the Cmax of cimetidine in rats. However, DA-9801 did not affect the elimination parameters such as half-life, clearance, or amount excreted in the urine, suggesting that it did not inhibit elimination process of cimetidine, which is governed by OCT1, OCT2, and OAT3. Moreover, DA-9801 did not affect the pharmacokinetic characteristics of furosemide, as evidenced by its unchanged pharmacokinetic parameters. Inhibitory effects of DA-9801 on OCT1, OCT2, and OAT3 observed in vitro may not necessarily translate into in vivo herb-drug interactions in rats even at its maximum effective dose.

Gastrointestinal medications and breastfeeding.

PubMed

Hagemann, T M

1998-09-01

Medications used to treat gastrointestinal symptoms are increasingly being used as more have been gained nonprescription status. Most of the gastrointestinal medications, such as laxatives, antacids, and antidiarrheal agents, are used short term. Women who breastfeed should be aware of the risks of taking any medications, whether prescription or nonprescription. There is little information describing transfer into breast milk for many of these products. Cimetidine, atropine, cascara, cisapride, loperamide, magnesium sulfate, and senna are the only products identified by the AAP as compatible with breast feeding. Metoclopramide is listed by the AAP as a drug whose effect on nursing infants is unknown but may be of potential concern, although studies published to date have not reported any adverse effects. The safest laxatives and antidiarrheals are those that are not absorbed and should be considered first-line therapy for conditions of constipation or loose stools. Famotidine and nizatidine are excreted into breast milk to a lesser extent than cimetidine or ranitidine and may be the preferred histamine antagonists. Despite the limited data on the use of cisapride in nursing women, it is considered safe by the AAP and may be preferred over metoclopramide for first-line prescription treatment of heartburn. Although most of these agents appear safe in the nursing infant, caretakers should be aware of the potential adverse reactions that may occur in infants whose mothers require these products.

Sodium ion modulates D2 receptor characteristics of dopamine agonist and antagonist binding sites in striatum and retina

PubMed Central

Makman, Maynard H.; Dvorkin, B.; Klein, Patrice N.

1982-01-01

Sodium ion (Na+) influences binding of both dopamine agonists and antagonists to D2 receptors in striatum and retina. Also, Na+ markedly potentiates the loss of high-affinity agonist binding due to the GTP analogue p[NH]ppG. 2-Amino-6, 7-dihydroxy-1,2,3,4-tetrahydro[5,8-3H]naphthalene ([3H]ADTN) binds exclusively to an agonist conformation of D2 receptor in both striatum and retina, distinct from the antagonist conformation labeled by [3H]spiroperidol or [3H]domperidone in striatum or by [3H]spiroperidol in retina. Na+ is not required for interaction of [3H]ADTN or antagonist radioligand sites with the selective D2 agonist LY-141865, the D2 antagonist domperidone, or nonselective dopamine agonists or antagonists; however, Na+ is necessary for high affinity interaction of those radioligand sites with the D2 antagonists molindone and metoclopramide. With Na+ present, striatal sites for [3H]ADTN, [3H]spiroperidol, and [3H]domperidone have similar affinities for antagonists but only [3H]ADTN sites have high affinity for agonists. Na+ further decreases the low affinity of dopamine agonists for [3H]spiroperidol binding sites. Also, Na+ enhances [3H]spiroperidol and decreases [3H]ADTN binding. Na+ alone causes bound [3H]ADTN to dissociate from at least 30% of striatal and 50% of retinal sites, and with Na+ present [3H]ADTN rapidly dissociates from the remaining sites upon addition of p[NH]ppG. It is proposed that D2 receptors in striatum and retina exist in distinct but interconvertible conformational states, with different properties depending on the presence or absence of Na+ and of guanine nucleotide. PMID:6213964

Role of iron in the pathogenesis of cysteamine-induced duodenal ulceration in rats

PubMed Central

Khomenko, Tetyana; Szabo, Sandor; Deng, Xiaoming; Ishikawa, Hideki; Anderson, Gregory J.; McLaren, Gordon D.

2009-01-01

Cysteamine induces perforating duodenal ulcers in rats within 24–48 h. This reducing aminothiol generates hydrogen peroxide in the presence of transition metals (e.g., ferric iron), producing oxidative stress, which may contribute to organ-specific tissue damage. Since most intestinal iron absorption takes place in the proximal duodenum, we hypothesized that cysteamine may disrupt regulation of mucosal iron transport, and iron may facilitate cysteamine-induced duodenal ulceration. We show here that cysteamine-induced ulceration was aggravated by pretreatment of rats with Fe3+ or Fe2+ compounds, which elevated iron concentration in the duodenal mucosa. In contrast, feeding rats an iron-deficient diet was associated with a 4.6-fold decrease in ulcer formation, accompanied by a 34% decrease (P < 0.05) in the duodenal mucosal iron concentration. Administration of deferoxamine inhibited ulceration by 65%. We also observed that the antiulcer effect of H2 receptor antagonist cimetidine included a 35% decrease in iron concentration in the duodenal mucosa. Cysteamine-induced duodenal ulcers were also decreased in iron-deficient Belgrade rats (P < 0.05). In normal rats, cysteamine administration increased the iron concentration in the proximal duodenal mucosa by 33% in the preulcerogenic stage but at the same time decreased serum iron (P < 0.05). Cysteamine also enhanced activation of mucosal iron regulatory protein 1 and increased the expression of divalent metal transporter 1 mRNA and protein. Transferrin receptor 1 protein expression was also increased, although mucosal ferroportin and ferritin remained almost unchanged. These results indicate an expansion of the intracellular labile iron pool in the duodenal mucosa, increasing its susceptibility to oxidative stress, and suggest a role for iron in the pathogenesis of organ-specific tissue injury such as duodenal ulcers. PMID:19342511

Intragastric nitrites, nitrosamines, and bacterial overgrowth during cimetidine treatment.

PubMed Central

Stockbrugger, R W; Cotton, P B; Eugenides, N; Bartholomew, B A; Hill, M J; Walters, C L

1982-01-01

A six week course of cimetidine (1 g/day) healed peptic ulcers in 20 of 23 patients (14 with duodenal ulcer, nine with gastric ulcer). Reduction of basal acid output by 73% and peak acid output by 36% led to a rise in concentrations of intragastric aerobic bacteria and nitrate-reducing bacteria. While the mean intragastric concentration of nitrate was unchanged by treatment, there were statistically significant rises in nitrite and N-nitrosamine concentrations. The conversion from nitrates to nitrites was closely related to the occurrence of nitrate-reducing bacteria. In three patients the intragastric milieu had returned to normal two months after cimetidine treatment had been discontinued. Mean nitrite and N-nitrosamine concentrations did not return to pre-treatment levels in the group of eight patients who remained on maintenance cimetidine (0.4 g at night-time) for three months after the full dose treatment. This study shows that cimetidine treatment can create an intragastric milieu resembling that of atrophic gastritis. Large scale and long-term studies are necessary to establish whether these findings have any clinical significance. PMID:7173716

Glomerular filtration rate estimation from plasma creatinine after inhibition of tubular secretion: relevance of the creatinine assay.

PubMed

Kemperman, F A; Silberbusch, J; Slaats, E H; van Zanten, A P; Weber, J A; Krediet, R T; Arisz, L

1999-05-01

Estimation of glomerular filtration rate (GFR) from plasma creatinine concentration after inhibition of tubular creatinine secretion with cimetidine provides a good assessment in patients with various nephropathies and with non-insulin-dependent diabetes mellitus (NIDDM). The aim of this study was to compare cimetidine-aided GFR estimations using various creatinine assays. In 30 outpatients with NIDDM GFR was measured as the urinary clearance of continuously infused [125I]iothalamate. Plasma creatinine concentration was analysed after oral cimetidine with an alkaline picrate (AP) method, with an enzymatic (PAP) assay and with HPLC. GFR estimations were calculated with the Cockcroft Gault formula (CG). AP creatinine concentrations were significantly higher than PAP or HPLC values. GFR estimations by AP (CG(AP) 66 +/- 19 ml/min/1.73 m2, mean SD) were significantly lower than GFR (89 +/- 30), whereas CG(PAP) (85 +/- 30) and CG(HPLC) (84 +/- 34 ml/min/1.73 m2) were not. Bland and Altman analysis showed a difference between CG(AP) and GFR of -22.4 +/- 17.7 ml/min/1.73 m2; this difference becomes larger when the GFR increases. The difference between CG and GFR was only -3.8 +/- 14.8 ml/min/1.73 m2 for PAP and -4.4 +/- 17.5 ml/min/1.73 m2 for HPLC, without any systematic difference. A good assessment of the GFR from plasma creatinine after cimetidine administration is possible when creatinine is measured with an enzymatic assay or with the less convenient HPLC method. The more widespread and cheaper alkaline picrate assay is not suitable for GFR-estimation.

Effect of mutation of Phe 2436.44 of the histamine H2 receptor on cimetidine and ranitidine mechanism of action.

PubMed

Granja-Galeano, Gina; Zappia, Carlos Daniel; Fabián, Lucas; Davio, Carlos; Shayo, Carina; Fernández, Natalia; Monczor, Federico

2017-12-15

Despite the pivotal role GPCRs play in cellular signaling, it is only in the recent years that structural biology has begun to elucidate how GPCRs function and to provide a platform for structure-based drug design. It is postulated that GPCR activation involves the movement of transmembrane helices. The finding that many residues, which have been shown to be critical for receptor activation and are highly conserved among different GPCRs, are clustered in particular positions of transmembrane helices suggests that activation of GPCRs may involve common molecular mechanisms. In particular, phenylalanine 6.44, located in the upper half of TMVI, is highly conserved among almost all GPCRs. We generated Phe 243 6.44 Ala/Ser mutants of histamine H 2 receptor and found that while the substitutions do not affect receptor expression or ligand signaling, are able to specifically alter cimetidine and ranitidine mechanisms of action from simply inactivating the receptor to produce a ligand-induced G-protein sequestering conformation, that interferes with the signaling of β2-adrenoceptor. Taking advantage of the cubic ternary complex model, and mathematically modeling our results, we hypothesize that this alteration in ligand mechanism of action is consequence of a change in ligand-induced conformational rearrangement of receptor and its effect on G-protein coupling. Our results show that receptor point mutations can not only alter receptor behavior, as shown for activating/inactivating mutations, but also can have more subtle effects changing ligand mechanism of action. Copyright © 2017 Elsevier Inc. All rights reserved.

Formulation and characterization of a compacted multiparticulate system for modified release of water-soluble drugs--Part II theophylline and cimetidine.

PubMed

Cantor, Stuart L; Hoag, Stephen W; Augsburger, Larry L

2009-05-01

The purpose was to investigate the effectiveness of an ethylcellulose (EC) bead matrix and different film-coating polymers in delaying drug release from compacted multiparticulate systems. Formulations containing theophylline or cimetidine granulated with Eudragit RS 30D were developed and beads were produced by extrusion-spheronization. Drug beads were coated using 15% wt/wt Surelease or Eudragit NE 30D and were evaluated for true density, particle size, and sphericity. Lipid-based placebo beads and drug beads were blended together and compacted on an instrumented Stokes B2 rotary tablet press. Although placebo beads were significantly less spherical, their true density of 1.21 g/cm(3) and size of 855 mum were quite close to Surelease-coated drug beads. Curing improved the crushing strength and friability values for theophylline tablets containing Surelease-coated beads; 5.7 +/- 1.0 kP and 0.26 +/- 0.07%, respectively. Dissolution profiles showed that the EC matrix only provided 3 h of drug release. Although tablets containing Surelease-coated theophylline beads released drug fastest overall (t(44.2%) = 8 h), profiles showed that coating damage was still minimal. Size and density differences indicated a minimal segregation potential during tableting for blends containing Surelease-coated drug beads. Although modified release profiles >8 h were achievable in tablets for both drugs using either coating polymer, Surelease-coated theophylline beads released drug fastest overall. This is likely because of the increased solubility of theophylline and the intrinsic properties of the Surelease films. Furthermore, the lipid-based placebos served as effective cushioning agents by protecting coating integrity of drug beads under a number of different conditions while tableting.

The influence of cimetidine on the pharmacokinetics of 5-fluorouracil.

PubMed Central

Harvey, V J; Slevin, M L; Dilloway, M R; Clark, P I; Johnston, A; Lant, A F

1984-01-01

The influence of cimetidine pretreatment on the pharmacokinetics of 5-fluorouracil (5FU) has been studied in 15 ambulant patients with carcinoma. Neither pretreatment with a single dose of cimetidine (400 mg) nor with daily treatment at 1000 mg for 1 week altered 5FU pharmacokinetics. Pretreatment with cimetidine for 4 weeks (1000 mg daily) led to increased peak plasma concentrations of 5FU and also area under the plasma concentration-time curve (AUC). The peak plasma concentration after oral 5FU was increased by 74% from 18.7 +/- 4.5 micrograms/ml (mean +/- s.e. mean) to 32.6 +/- 4.4 micrograms/ml (P less than 0.05) and AUC was increased by 72% from 528 +/- 133 micrograms/ml-1 min (mean +/- s.e. mean) to 911 +/- 152 micrograms ml-1 min (P less than 0.05). After intravenous 5FU, AUC was increased by 27% from 977 +/- 96 micrograms ml-1 min (mean +/- s.e. mean) to 1353 +/- 124 micrograms ml-1 min (P less than 0.01). Total body clearance for 5FU following intravenous administration was decreased by 28% from 987 +/- 116 ml/min (mean +/- s.e. mean) to 711 +/- 87 ml/min (P less than 0.01). The elimination half-life of 5FU was not altered by cimetidine. The basis of the interaction between 5FU and cimetidine is uncertain but probably a combination of inhibited drug metabolism and reduced liver blood flow. The therapeutic implications are considerable and additional care should be taken in patients receiving the two drugs concomitantly. PMID:6487480

Contrasting cardiovascular properties of the µ-opioid agonists morphine and methadone in the rat.

PubMed

Tung, Kenneth H; Angus, James A; Wright, Christine E

2015-09-05

Morphine and methadone share the property of μ-opioid receptor agonism yet have markedly different cardiovascular actions suggesting additional properties are at play. We investigated the i.v. dose-response relationships of the opioids on cardiovascular metameters in anaesthetised rats in the absence or presence of H1- and H2-receptor antagonism and the μ-opioid antagonist naloxone. In vitro tissue assays were employed to define more clearly cardiac and vascular mechanisms of action. Morphine (9, 30, 90mg/kg i.v.) decreased heart rate (HR) and mean arterial pressure (MAP) - responses that were blocked by naloxone pretreatment (10mg/kg i.v.). In contrast, methadone (3, 10, 30mg/kg i.v.) caused dramatic short-lived (1-3min) bradycardia, hypotension and lengthening of the QT interval before stabilising 5min after i.v. dosing. Only the steady-state responses of HR and MAP were blocked by naloxone. Mepyramine (10mg/kg i.v.) and cimetidine (100mg/kg i.v.) also blocked the naloxone-sensitive components. In isolated small mesenteric arteries precontracted by K(+) 62mM or endothelin-1, methadone (1-30μM) relaxed vessels while morphine (1-100μM) had no effect. Pretreatment with naloxone (10μM), indomethacin (30μM) or nitro-l-arginine (100μM) did not affect the relaxation to methadone. In rat isolated left atria, morphine and methadone inhibited inotropic responses at high concentrations (100μM). In rat papillary muscle and right atria, methadone was more than 30 times more potent at lengthening the refractory period and slowing the atrial rate than morphine. We conclude that methadone is a potent vasodilator agent, possibly through blocking L-type calcium channels. Copyright © 2015 Elsevier B.V. All rights reserved.

Conjunctival papilloma: features and outcomes based on age at initial examination.

PubMed

Kaliki, Swathi; Arepalli, Sruthi; Shields, Carol L; Klein, Kendra; Sun, Hong; Hysenj, Eralda; Lally, Sara E; Shields, Jerry A

2013-05-01

Conjunctival papilloma is a benign epithelial tumor occurring in both children and adults with varying clinical features and outcomes. In this article, we describe our experience regarding the difference in the clinical features and outcomes of conjunctival papilloma based on age at initial examination. To evaluate the clinical features, treatment, and outcomes in patients with conjunctival papilloma based on age at initial examination. Retrospective study. Ocular Oncology Service, Wills Eye Hospital, Philadelphia, Pennsylvania. Ten children and adolescents (aged ≤20 years) and 63 adults (aged >20 years) with conjunctival papilloma. Excisional biopsy, cryotherapy, oral cimetidine, topical or injection interferon alfa-2b, and photodynamic therapy. Tumor response. A comparison of conjunctival papillomas between age groups revealed significant differences in the mean number of tumors per eye (children and adolescents vs adults, 2 vs 1; P = .05), tumor basal dimension (8 vs 6 mm; P = .05), and associated feeder vessels (20% vs 47%; P = .05). Primary treatment included sole treatment with oral cimetidine (15% vs 5%), topical interferon alfa-2b (0% vs 1%), cryotherapy (0% vs 3%), photodynamic therapy (0% vs 1%), excisional biopsy and cryotherapy (38% vs 65%), excisional biopsy and cryotherapy with adjuvant oral cimetidine (8% vs 9%), and excisional biopsy and cryotherapy with adjuvant topical or injection interferon alfa-2b (38% vs 15%). Significant differences in age groups in treatment outcome during the follow-up period (mean, 24 vs 38 months) included complete regression with single treatment (38% vs 95%; P < .01) and tumor recurrence (15% vs 1%; P = .05). Conjunctival papillomas are larger and more likely to be multiple in children and adolescents than in adults. Excisional biopsy and cryotherapy with or without adjuvant oral cimetidine and/or topical interferon alfa-2b provide satisfactory tumor control. Papilloma recurrence is more common in children and adolescents than in adults.

Efficacy of cimetidin in the prevention of ulcer formation in the stomach during immobilization stress

NASA Technical Reports Server (NTRS)

Dorofeyev, G. I.; Litovskiy, I. A.; Gavrovskaya, L. K.; Ivashkin, V. T.

1982-01-01

The effect of stress on the formation of ulcers in the mucous membrane of the stomach, the increase in cyclic adenosine monophosphate level in the gastric tissues, and parietal cell structure alteration. Use of cimetidin prevents these effects

Gastroduodenal complications in kidney transplant recipients.

PubMed Central

Stuart, F P; Reckard, C R; Schulak, J A; Ketel, B L

1981-01-01

Oral antacids taken every two hours while awake provided the only prophylaxis against gastroduodenal ulceration for 167 kidney transplant recipients between 1968 and July 1978. Either perforation or major hemorrhage occurred in eight patients within 30 days after transplantation. Between July 1978 and January 1981, bleeding occurred within 30 days in two of 147 recipients who were treated with both antacids and cimetidine. Of the 147 patients, eleven with a history of ulcers had undergone pretransplant vagotomy; neither perforation nor hemorrhage occurred in any of the eleven patients. Despite reports that cimetidine enhances certain types of immune responses, we observed slightly greater graft survival in the group treated with cimetidine. PMID:7023396

Cell proliferation in dimethylhydrazine-induced colonic adenocarcinomata following cytotoxic drug treatment.

PubMed

Tutton, P J; Barkla, D H

1978-08-25

A stathmokinetic technique was used to study cell proliferation in dimethylhydrazine-induced adenocarcinomata of rat colon following treatment with cytotoxic drugs. The rate of cell division was significantly increased three days after treatment with 5,7-dihydroxytryptamine and seven days after treatment with 5-fluorouracil. Acceleration of tumour cell proliferation following 5,7-dihydroxytryptamine treatment was inhibited by treating animals with the antiseritoninergic drug Xylamidine Tosylate. Acceleration of tumour cell proliferation following 5-fluorouracil treatment was inhibited by treating animals either with the antiseritoninergic drug BW501 or with the histamine H2-receptor blocking drug Cimetidine.

[Effect of the association of inhibitors of the H 1 and H 2 histamine receptors in the mechanism of rupture of the gastric barrier in the dog in vivo].

PubMed

Ceriani, T; Moggio, R; Gnes, F; Ventura, U

1980-09-30

Two specific inhibitors of histamine receptors, H1 mepiramine (Mp) and H2 cimetidine (Cm), were used in combination to define the role of histamine in the mechanisms of gastric barrier rupture in the dog "in vivo". A gastrolesive substance butyric acid (Ac.B. 75 mM) in hydrocloric acid solution (HCl 75 mM) was perfused through Heidenhain pouches in the presence or absence of Mp (10 mg/Kg i.m.) and Cm (1 mg/Kg/h i.v.). The results obtained showed: 1) Ac.B. caused a remarkable increase in H+ and Na+ fluxes, enhanced K+ secretion and decreased transparietal potential difference (D.P.). 2) Histamine inhibitors in combination uneffected changes of the ionic fluxes and D.P. produced by Ac.B. 3) Reversal to normal of both ionic fluxes and D.P. was not accelerated by the combination of Mp and Cm. The conclusion was reached that in the initial phase of gastric barrier rupture damage of gastric mucosa occurs by mechanisms non histamine-dependent.

Comparison of the effect of the antacid Rennie versus low-dose H2-receptor antagonists (ranitidine, famotidine) on intragastric acidity.

PubMed

Netzer, P; Brabetz-Höfliger, A; Bründler, R; Flogerzi, B; Hüsler, J; Halter, F

1998-04-01

Symptoms of functional dyspepsia are common and patients often self-medicate with antacids, or with low-dose H2-antagonists which are available as over-the-counter medications. To date, there has been limited information available comparing the effects on intragastric acidity of these two types of over-the-counter medication. Therefore we studied the effect of the antacid Rennie and two H2-antagonists on the intragastric pH of fasting volunteers. Sixteen healthy, fasting volunteers were randomized into a double-blind, placebo-controlled, four-way crossover study comparing Rennie (calcium-magnesium carbonate) 1360 mg, ranitidine 75 mg, famotidine 10 mg and placebo. Their effect on gastric pH was monitored by a 4-h gastric pH-metry. The primary efficacy parameter was the time lag before an intragastric pH > 3.0 was reached after drug administration. The median time lag before pH > 3.0 was reached after drug administration was 5.8 min for Rennie, 64.9 min for ranitidine, 70.1 min for famotidine and 240.0 min for placebo. The percentage of time with values of pH > 3.0 was 10.4% for Rennie, 61.4% for ranitidine, 56.6% for famotidine and 1.4% for placebo. The onset of action in fasting volunteers was significantly faster with the antacid than with the two H2-antagonists. The duration of action was significantly longer with an H2-antagonist than with the antacid. This suggests that the two products should be used for different indications: antacids are superior for rapid pain relief, whereas H2-antagonists might be better for symptom prophylaxis--for example for nocturnal dyspepsia.

Antiviral activity of formyl peptide receptor 2 antagonists against influenza viruses.

PubMed

Courtin, Noémie; Fotso, Aurélien Fotso; Fautrad, Pierre; Mas, Floriane; Alessi, Marie-Christine; Riteau, Béatrice

2017-07-01

Influenza viruses are one of the most important respiratory pathogens worldwide, causing both epidemic and pandemic infections. The aim of the study was to evaluate the effect of FPR2 antagonists PBP10 and BOC2 on influenza virus replication. We determined that these molecules exhibit antiviral effects against influenza A (H1N1, H3N2, H6N2) and B viruses. FPR2 antagonists used in combination with oseltamivir showed additive antiviral effects. Mechanistically, the antiviral effect of PBP10 and BOC2 is mediated through early inhibition of virus-induced ERK activation. Finally, our preclinical studies showed that FPR2 antagonists protected mice from lethal infections induced by influenza, both in a prophylactic and therapeutic manner. Thus, FPR2 antagonists might be explored for novel treatments against influenza. Copyright © 2017 Elsevier B.V. All rights reserved.

Gynaecomastia associated with cimetidine.

PubMed Central

Spence, R W; Celestin, L R

1979-01-01

Gynaecomastia has occurred unilaterally or bilaterally in five out of 25 male duodenal ulcer patients after more than four months treatment with cimetidine 1.6 g daily. All elected to continue treatment to 12 months and their breast enlargement regressed rapidly and disappeared after stopping treatment. During treatment all patients were found to have normal concentrations of plasma testosterone and oestradiol, and serum prolactin was normal in the two patients measured. Excision biopsy of the subareolar tissue in one patient revealed histology typical of the florid stage of gynaecomastia. Blockade of androgen-responsive receptors receptors in the target organ appears to be the most likely mechanism involved. Images Fig. 1 Fig. 2 PMID:428828

Effects of central histamine receptors blockade on GABA(A) agonist-induced food intake in broiler cockerels.

PubMed

Morteza, Zendehdel; Vahhab, Babapour; Hossein, Jonaidi

2008-02-01

In this study, the effect of intracerebroventricular (i.c.v) injection of H1, H2 and H3 antagonists on feed intake induced by GABA(A) agonist was evaluated. In Experiment 1, the animals received chloropheniramine, a H1 antagonist and then muscimol, a GABA(A) agonist. In Experiment 2, chickens received famotidine, a H2 receptor antagonist, prior to injection of muscimol. Finally in Experiment 3, the birds were injected with thioperamide, a H3 receptor antagonist and muscimol. Cumulative food intake was measured 15, 30, 45, 60, 90, 120, 150 and 180 min after injections. The results of this study indicated that effects of muscimol on food intake inhibited by pretreatment with chloropheneramine maleate (p < or = 0.05), significantly, while the famotidine and thioperamide were ineffective. These results suggest the existence of H1-receptor mediated histamine-GABA(A) receptor interaction on food intake in broiler cockerels.

Antagonist interaction with the human 5-HT7 receptor mediates the rapid and potent inhibition of non-G-protein-stimulated adenylate cyclase activity: a novel GPCR effect

PubMed Central

Klein, MT; Teitler, M

2011-01-01

BACKGROUND AND PURPOSE The human 5-hydroxytryptamine7 (h5-HT7) receptor is Gs-coupled and stimulates the production of the intracellular signalling molecule cAMP. Previously, we reported a novel property of the h5-HT7 receptor: pseudo-irreversible antagonists irreversibly inhibit forskolin-stimulated (non-receptor-mediated) cAMP production. Herein, we sought to determine if competitive antagonists also affect forskolin-stimulated activity and if this effect is common among other Gs-coupled receptors. EXPERIMENTAL APPROACH Recombinant cell lines expressing h5-HT7 receptors or other receptors of interest were briefly exposed to antagonists; cAMP production was then stimulated by forskolin and quantified by an immunocompetitive assay. KEY RESULTS In human embryonic kidney 293 cells stably expressing h5-HT7 receptors, all competitive antagonists inhibited nearly 100% of forskolin-stimulated cAMP production. This effect was insensitive to pertussis toxin, that is, not Gi/o-mediated. Potency to inhibit forskolin-stimulated activity strongly correlated with h5-HT7 binding affinity (r2= 0.91), indicating that the antagonists acted through h5-HT7 receptors to inhibit forskolin. Potency and maximal effects of clozapine, a prototypical competitive h5-HT7 antagonist, were unaffected by varying forskolin concentration. Antagonist interaction with h5-HT6, human β1, β2, and β3 adrenoceptors did not inhibit forskolin's activity. CONCLUSIONS AND IMPLICATIONS The inhibition of adenylate cyclase, as measured by forskolin's activity, is an underlying property of antagonist interaction with h5-HT7 receptors; however, this is not a common property of other Gs-coupled receptors. This phenomenon may be involved in the roles played by h5-HT7 receptors in human physiology. Development of h5-HT7 antagonists that do not elicit this effect would aid in the elucidation of its mechanisms and shed light on its possible physiological relevance. PMID:21198551

Comparison between cimetidine and Caved-S in the treatment of gastric ulceration, and subsequent maintenance therapy.

PubMed Central

Morgan, A G; McAdam, W A; Pacsoo, C; Darnborough, A

1982-01-01

One hundred patients with benign gastric ulceration were treated in a single-blind, endoscopically controlled trial to assess the relative efficacy of cimetidine (1 g daily) and Caved-S (six tablets daily). Ulcer healing was assessed after six weeks' treatment, and, if incomplete, after a further six weeks. There was no significant difference between the two drug regimens (approximately 63% at six weeks and 91% at 12 weeks). If an ulcer remains unhealed after 10 weeks' treatment the patient should undergo surgery. There was no difference in the relief of day pain between the two drug regimens but cimetidine was more effective over the first two weeks of treatment relieving night pain, than was Caved-S (p less than 0 . 02). After ulcer healing, drug dosage was reduced (cimetidine to 400 mg at night and Caved-S to two tablets twice daily). So far, 56 patients, 28 in each group, have completed the first year's maintenance treatment, and there have been four ulcer recurrences in each group (14%). PMID:7042486

Estrogen Receptor α L543A,L544A Mutation Changes Antagonists to Agonists, Correlating with the Ligand Binding Domain Dimerization Associated with DNA Binding Activity*

PubMed Central

Arao, Yukitomo; Hamilton, Katherine J.; Coons, Laurel A.; Korach, Kenneth S.

2013-01-01

A ligand-dependent nuclear transcription factor, ERα has two transactivating functional domains (AF), AF-1 and AF-2. AF-1 is localized in the N-terminal region, and AF-2 is distributed in the C-terminal ligand-binding domain (LBD) of the ERα protein. Helix 12 (H12) in the LBD is a component of the AF-2, and the configuration of H12 is ligand-inducible to an active or inactive form. We demonstrated previously that the ERα mutant (AF2ER) possessing L543A,L544A mutations in H12 disrupts AF-2 function and reverses antagonists such as fulvestrant/ICI182780 (ICI) or 4-hydoxytamoxifen (OHT) into agonists in the AF2ER knock-in mouse. Our previous in vitro studies suggested that the mode of AF2ER activation is similar to the partial agonist activity of OHT for WT-ERα. However, it is still unclear how antagonists activate ERα. To understand the molecular mechanism of antagonist reversal activity, we analyzed the correlation between the ICI-dependent estrogen-responsive element-mediated transcription activity of AF2ER and AF2ER-LBD dimerization activity. We report here that ICI-dependent AF2ER activation correlated with the activity of AF2ER-LBD homodimerization. Prevention of dimerization impaired the ICI-dependent ERE binding and transcription activity of AF2ER. The dislocation of H12 caused ICI-dependent LBD homodimerization involving the F-domain, the adjoining region of H12. Furthermore, F-domain truncation also strongly depressed the dimerization of WT-ERα-LBD with antagonists but not with E2. AF2ER activation levels with ICI, OHT, and raloxifene were parallel with the degree of AF2ER-LBD homodimerization, supporting a mechanism that antagonist-dependent LBD homodimerization involving the F-domain results in antagonist reversal activity of H12-mutated ERα. PMID:23733188

Antihistamine effect on synaptosomal uptake of serotonin, norepinephrine and dopamine

NASA Technical Reports Server (NTRS)

Brown, P. A.; Vernikos, J.

1980-01-01

A study on the effects of five H1 and H2 antihistamines on the synaptosomal uptake of serotonin (5HT), norepinephrine (NE), and dopamine (DA) is presented. Brain homogenates from female rats were incubated in Krebs-Ringer phosphate buffer solution in the presence of one of three radioactive neurotransmitters, and one of the five antihistamines. Low concentrations of pyrilamine competitively inhibited 5HT uptake, had little effect on NE uptake, and no effect on DA uptake. Promethazine, diphenhydramine, metiamide, and cimetidine had no effect on 5HT or DA uptake at the same concentration. Diphenhydramine had a small inhibitory effect on NE uptake. It is concluded that pyrilamine is a selective and potent competitive inhibitor of 5HT uptake at concentrations between .05 and .5 micromolars.

Effect of lysine at C-terminus of the Dmt-Tic opioid pharmacophore.

PubMed

Balboni, Gianfranco; Onnis, Valentina; Congiu, Cenzo; Zotti, Margherita; Sasaki, Yusuke; Ambo, Akihiro; Bryant, Sharon D; Jinsmaa, Yunden; Lazarus, Lawrence H; Trapella, Claudio; Salvadori, Severo

2006-09-07

Substitution of Gly with side-chain-protected or unprotected Lys in lead compounds containing the opioid pharmacophore Dmt-Tic [H-Dmt-Tic-Gly-NH-CH(2)-Ph, mu agonist/delta antagonist; H-Dmt-Tic-Gly-NH-Ph, mu agonist/delta agonist; and H-Dmt-Tic-NH-CH(2)-Bid, delta agonist (Bid = 1H-benzimidazole-2-yl)] yielded a new series of compounds endowed with distinct pharmacological activities. Compounds (1-10) included high delta- (Ki(delta) = 0.068-0.64 nM) and mu-opioid affinities (Ki(mu) = 0.13-5.50 nM), with a bioactivity that ranged from mu-opioid agonism {10, H-Dmt-Tic-NH-CH[(CH2)4-NH2]-Bid (IC50 GPI = 39.7 nM)} to a selective mu-opioid antagonist [3, H-Dmt-Tic-Lys-NH-CH2-Ph (pA2(mu) = 7.96)] and a selective delta-opioid antagonist [5, H-Dmt-Tic-Lys(Ac)-NH-Ph (pA2(delta) = 12.0)]. The presence of a Lys linker provides new lead compounds in the formation of opioid peptidomimetics containing the Dmt-Tic pharmacophore with distinct agonist and/or antagonist properties.

Creatinine reabsorption by the aged kidney.

PubMed

Musso, Carlos G; Michelángelo, Hernán; Vilas, Manuel; Reynaldi, Juliana; Martinez, Bernardo; Algranati, Luis; Macías Núñez, Juan F

2009-01-01

The handling of renal creatinine in human beings has classically been described as the result of two particular physiological processes: glomerular filtration and proximal tubular secretion. However, there are particular physiological situations in which tubular creatinine reabsorption has been documented, such as in the case of healthy newborns and premature babies. We performed a prospective study in order to evaluate if there is tubular creatinine reabsorption in healthy elderly people. We studied prospectively nine healthy volunteers, four of them young (20-33 years old) and the remaining five, old (65-73 years old). Since creatinine is secreted in the proximal tubules, and its secretion can be completely blocked by cimetidine administration, a creatinine clearance with cimetidine reliably represents the glomerular filtration rate. Therefore, if the ratio creatinine clearance (Ccr)/creatinine clearance with cimetidine (CcrWC) is higher than one, this would indicate net creatinine secretion, whereas a ratio lower than one would indicate a net renal creatinine tubular reabsorption; a ratio equal to one indicates creatinine filtration. Finally, the Ccr, CcrWC, and Ccr/CcrWC ratios were compared between the young and old group. Mann-Whitney and Wilcoxon tests were used. As expected, creatinine clearance in the elderly was significantly lower than in the young [Ccr: 74.4 ml/min (47.9-100.9) (old) vs. 153.8 ml/min (108.3-199.2) (young), p = 0.014]. Similarly, the creatinine clearance with cimetidine (CcrWC) was significantly lower in the elderly compared to the young [CcrWC: 81.8 ml/min (69.2-94.5) (old) vs. 122.5 ml/min (82.6-162.4) (young), p = 0.028]. The ratio of Ccr/CcrWC was 0.9 in the elderly vs. 1.26 in the young (p = 0.014), indicating net creatinine reabsorption in the elderly and net creatinine secretion in the young. Our findings indicate that there seems to be a net reabsorption of creatinine in the renal tubules of healthy old persons.

Pharmacologic characterization of the oxytocin receptor in human uterine smooth muscle cells

PubMed Central

Tahara, Atsuo; Tsukada, Junko; Tomura, Yuichi; Wada, Koh-ichi; Kusayama, Toshiyuki; Ishii, Noe; Yatsu, Takeyuki; Uchida, Wataru; Tanaka, Akihiro

2000-01-01

[3H]-oxytocin was used to characterize the oxytocin receptor found in human uterine smooth muscle cells (USMC). Specific binding of [3H]-oxytocin to USMC plasma membranes was dependent upon time, temperature and membrane protein concentration. Scatchard plot analysis of equilibrium binding data revealed the existence of a single class of high-affinity binding sites with an apparent equilibrium dissociation constant (Kd) of 0.76 nM and a maximum receptor density (Bmax) of 153 fmol mg−1 protein. The Hill coefficient (nH) did not differ significantly from unity, suggesting binding to homogenous, non-interacting receptor populations. Competitive inhibition of [3H]-oxytocin binding showed that oxytocin and vasopressin (AVP) receptor agonists and antagonists displaced [3H]-oxytocin in a concentration-dependent manner. The order of potencies for peptide agonists and antagonists was: oxytocin>[Asu1,6]-oxytocin>AVP= atosiban>d(CH2)5Tyr(Me)AVP>[Thr4,Gly7]-oxytocin>dDAVP, and for nonpeptide antagonists was: L-371257>YM087>SR 49059>OPC-21268>SR 121463A>OPC-31260. Oxytocin significantly induced concentration-dependent increase in intracellular Ca2+ concentration ([Ca2+]i) and hyperplasia in USMC. The oxytocin receptor antagonists, atosiban and L-371257, potently and concentration-dependently inhibited oxytocin-induced [Ca2+]i increase and hyperplasia. In contrast, the V1A receptor selective antagonist, SR 49059, and the V2 receptor selective antagonist, SR 121463A, did not potently inhibit oxytocin-induced [Ca2+]i increase and hyperplasia. The potency order of antagonists in inhibiting oxytocin-induced [Ca2+]i increase and hyperplasia was similar to that observed in radioligand binding assays. In conclusion, these data provide evidence that the high-affinity [3H]-oxytocin binding site found in human USMC is a functional oxytocin receptor coupled to [Ca2+]i increase and cell growth. Thus human USMC may prove to be a valuable tool in further investigation of the physiologic and pathophysiologic roles of oxytocin in the uterus. PMID:10694212

H2O2 attenuates IGF-1R tyrosine phosphorylation and its survival signaling properties in neuronal cells via NR2B containing NMDA receptor.

PubMed

Zeng, Zhiwen; Wang, Dejun; Gaur, Uma; Rifang, Liao; Wang, Haitao; Zheng, Wenhua

2017-09-12

Impairment of insulin-like growth factor I (IGF-I) signaling plays an important role in the development of neurodegeneration. In the present study, we investigated the effect of H 2 O 2 on the survival signaling of IGF-1 and its underlying mechanisms in human neuronal cells SH-SY5Y. Our results showed that IGF-1 promoted cell survival and stimulated phosphorylation of IGF-1R as well as its downstream targets like AKT and ERK1/2 in these cells. Meanwhile, these effects of IGF-1 were abolished by H 2 O 2 at 200μM concentration which did not cause any significant toxicity to cells itself in our experiments. Moreover, studies using various glutamate receptor subtype antagonists displayed that N-methyl-D -aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) blocked the effects of H 2 O 2 , whereas other glutamate receptor subtype antagonists, such as non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), metabolic glutamate receptor antagonists LY341495 and CPCCOEt, had no effect. Further studies revealed that NR2B-containing NMDARs are responsible for these effects as its effects were blocked by pharmacological inhibitor Ro25-698 or specific siRNA for NR2B, but not NR2A. Finally, our data also showed that Ca 2+ influx contributes to the effects of H 2 O 2 . Similar results were obtained in primary cultured cortical neurons. Taken together, the results from the present study suggested that H 2 O 2 attenuated IGF-1R tyrosine phosphorylation and its survival signaling properties via NR2B containing NMDA receptors and Ca 2+ influx in SH-SY5Y cells. Therefore, NMDAR antagonists, especially NR2B-selective ones, combined with IGF-1 may serve as an alternative therapeutic agent for oxidative stress related neurodegenerative disease.

Identification and characterization of amino-piperidinequinolones and quinazolinones as MCHr1 antagonists.

PubMed

Blackburn, Christopher; LaMarche, Matthew J; Brown, James; Che, Jennifer Lee; Cullis, Courtney A; Lai, Sujen; Maguire, Martin; Marsilje, Thomas; Geddes, Bradley; Govek, Elizabeth; Kadambi, Vivek; Doherty, Colleen; Dayton, Brian; Brodjian, Sevan; Marsh, Kennan C; Collins, Christine A; Kym, Philip R

2006-05-15

Several potent, functionally active MCHr1 antagonists derived from quinolin-2(1H)-ones and quinazoline-2(1H)-ones have been synthesized and evaluated. Pyridylmethyl substitution at the quinolone 1-position results in derivatives with low-nM binding potency and good selectivity with respect to hERG binding.

Effects of preoperative medications on gastric pH, volume, and flora.

PubMed Central

Laws, H L; Bryant, J W; Palmer, M D; Boudreaux, A M; Donald, J M; Wheeler, A S

1986-01-01

Aspiration of acid gastric juice poses a potential threat during operations. Many anesthesiologists use a variety of agents aimed at decreasing gastric volume and/or acidity. The effect of three agents on gastric volume, pH, and flora, and the effect of cefazolin on gastric flora in morbidly obese patients were studied. Cefazolin did not sterilize the gastric lumen. Almost one-half of patients not treated with an H2 blocker had a pH below 2.5 and a gastric volume of 20 ml or more. Five had both a low pH and significant volume and, thus, the potential for lethal aspiration. Two doses of cimetidine, 300 mgm orally, or of ranitidine, 150 orally, the evening before and the morning of operation decreased gastric volume and raised pH reliably to a level that should be protective from fatal aspiration. However, gastric cultures after these drugs were positive 86% of the time with a larger variety of organisms than in the untreated stomachs. Metoclopramide failed to decrease gastric volume or raise pH. Transoperative cefazolin was used in all patients. Clinical infection was not a problem. PMID:3521506

Novel selective human melanocortin-3 receptor ligands: Use of the 4-amino-1,2,4,5-tetrahydro-2-benzazepin-3-one (Aba) scaffold

PubMed Central

Ballet, Steven; Mayorov, Alexander V.; Cai, Minying; Tymecka, Dagmara; Chandler, Kevin B.; Palmer, Erin S.; Van Rompaey, Karolien; Misicka, Aleksandra; Tourwé, Dirk; Hruby, Victor J.

2008-01-01

In search of new selective antagonists and/or agonists for the human melanocortin receptor subtypes hMC1R to hMC5R to elucidate the specific biological roles of each GPCR, we modified the structures of the superagonist MT-II (Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) and the hMC3R/hMC4R antagonist SHU9119 (Ac-Nle-c[Asp-His-D-Nal(2′)-Arg-Trp-Lys]-NH2) by replacing the His-D-Phe and His-D-Nal(2′) fragments in MT-II and SHU9119, respectively, with Aba-Xxx (4-amino-1,2,4,5-tetrahydro-2-benzazepin-3-one-Xxx) dipeptidomimetics (Xxx = D-Phe/pCl-D-Phe/D-Nal(2′)). Employment of the Aba mimetic yielded novel selective high affinity hMC3R and hMC3R/hMC5R antagonists. PMID:17314042

Hit-to-lead optimization of 2-(1H-pyrazol-1-yl)-thiazole derivatives as a novel class of EP1 receptor antagonists.

PubMed

Atobe, Masakazu; Naganuma, Kenji; Kawanishi, Masashi; Morimoto, Akifumi; Kasahara, Ken-ichi; Ohashi, Shigeki; Suzuki, Hiroko; Hayashi, Takahiko; Miyoshi, Shiro

2013-11-15

We describe a medicinal chemistry approach to generate a series of 2-(1H-pyrazol-1-yl)thiazole compounds that act as selective EP1 receptor antagonists. The obtained results suggest that compound 12 provides the best EP1 receptor antagonist activity and demonstrates good oral pharmacokinetics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Binding of [3H]MSX-2 (3-(3-hydroxypropyl)-7-methyl-8-(m-methoxystyryl)-1-propargylxanthine) to rat striatal membranes--a new, selective antagonist radioligand for A(2A) adenosine receptors.

PubMed

Müller, C E; Maurinsh, J; Sauer, R

2000-01-01

The present study describes the preparation and binding properties of a new, potent, and selective A(2A) adenosine receptor (AR) antagonist radioligand, [3H]3-(3-hydroxypropyl)-7-methyl-8-(m-methoxystyryl)-1-propargy lxanth ine ([3H]MSX-2). [3H]MSX-2 binding to rat striatal membranes was saturable and reversible. Saturation experiments showed that [3H]MSX-2 labeled a single class of binding sites with high affinity (K(d)=8.0 nM) and limited capacity (B(max)=1.16 fmol.mg(-1) of protein). The presence of 100 microM GTP, or 10 mM magnesium chloride, respectively, had no effect on [3H]MSX-2 binding. AR agonists competed with the binding of 1 nM [3H]MSX-2 with the following order of potency: 5'-N-ethylcarboxamidoadenosine (NECA)>2-[4-(carboxyethyl)phenylethylamino]-5'-N-ethylcarboxami doaden osine (CGS-21680)>2-chloroadenosine (2-CADO)>N(6)-cyclopentyladenosine (CPA). AR antagonists showed the following order of potency: 8-(m-bromostyryl)-3, 7-dimethyl-1-propargylxanthine (BS-DMPX)>1, 3-dipropyl-8-cyclopentylxanthine (DPCPX)>(R)-5, 6-dimethyl-7-(1-phenylethyl)-2-(4-pyridyl)-7H-pyrrolo[2, 3-d]pyrimidine-4-amine (SH-128)>3,7-dimethyl-1-propargylxanthine (DMPX)>caffeine. The K(i) values for antagonists were in accordance with data from binding studies with the agonist radioligand [3H]CGS21680, while agonist affinities were 3-7-fold lower. [3H]MSX-2 is a highly selective A(2A) AR antagonist radioligand exhibiting a selectivity of at least two orders of magnitude versus all other AR subtypes. The new radioligand shows high specific radioactivity (85 Ci/mmol, 3150 GBq/mmol) and acceptable nonspecific binding at rat striatal membranes of 20-30%, at 1 nM.

The modulatory role of spinally located histamine receptors in the regulation of the blood glucose level in d-glucose-fed mice.

PubMed

Sim, Yun-Beom; Park, Soo-Hyun; Kim, Sung-Su; Kim, Chea-Ha; Kim, Su-Jin; Lim, Su-Min; Jung, Jun-Sub; Ryu, Ohk-Hyun; Choi, Moon-Gi; Suh, Hong-Won

2014-02-01

The possible roles of spinal histamine receptors in the regulation of the blood glucose level were studied in ICR mice. Mice were intrathecally (i.t.) treated with histamine 1 (H1) receptor agonist (2-pyridylethylamine) or antagonist (cetirizine), histamine 2 (H2) receptor agonist (dimaprit) or antagonist (ranitidine), histamine 3 (H3) receptor agonist (α-methylhistamine) or antagonist (carcinine) and histamine 4 (H4) receptor agonist (VUF 8430) or antagonist (JNJ 7777120), and the blood glucose level was measured at 30, 60 and 120 min after i.t. administration. The i.t. injection with α-methylhistamine, but not carcinine slightly caused an elevation of the blood glucose level. In addition, histamine H1, H2, and H4 receptor agonists and antagonists did not affect the blood glucose level. In D-glucose-fed model, i.t. pretreatment with cetirizine enhanced the blood glucose level, whereas 2-pyridylethylamine did not affect. The i.t. pretreatment with dimaprit, but not ranitidine, enhanced the blood glucose level in D-glucose-fed model. In addition, α-methylhistamine, but not carcinine, slightly but significantly enhanced the blood glucose level D-glucose-fed model. Finally, i.t. pretreatment with JNJ 7777120, but not VUF 8430, slightly but significantly increased the blood glucose level. Although histamine receptors themselves located at the spinal cord do not exert any effect on the regulation of the blood glucose level, our results suggest that the activation of spinal histamine H2 receptors and the blockade of spinal histamine H1 or H3 receptors may play modulatory roles for up-regulation and down-regulation, respectively, of the blood glucose level in D-glucose fed model.

[(P)FAPA syndrome: value of cimetidine].

PubMed

Pillet, P; Ansoborlo, S; Carrère, A; Perel, Y; Guillard, J M

2000-01-01

The (P)FAPA syndrome (periodic fever, adenitidis, pharyngitis, aphthous stomatitis) was described in 1987. The etiology of this periodic syndrome remains unknown. We report three new cases. Three girls, aged from 23 months to eight years, developed (P)FAPA. The other causes of periodic fevers were eliminated and the various treatments (antibiotics, antipyretics, nonsteroidal anti-inflammatory agents) proved ineffective. The repetition of the periodic bouts resulted in depressive disorders, absenteeism from school and a drop in weight in the youngest patient. Two of them suffered a sinusal involvement (chronic sinusitis, polyp) and had an increase in the level of immunoglobulin A. In all three cases, cimetidine at a dose of 20 mg/kg/d was well tolerated and resulted in a disappearance of the periodic fevers. Cimetidine, as an immunomodulating agent, appears to be beneficial in the in-depth treatment of (P)FAPA syndrome.

Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes.

PubMed

Newman-Tancredi, Adrian; Cussac, Didier; Quentric, Yann; Touzard, Manuelle; Verrièle, Laurence; Carpentier, Nathalie; Millan, Mark J

2002-11-01

Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their functional profiles in vivo.

Ranitidine-Associated Sleep Disturbance: Case Report and Review of H2 Antihistamine-Related Central Nervous System Adverse Effects.

PubMed

Werbel, Tyler; Cohen, Philip R

2018-04-03

Ranitidine is an H2 antihistamine used as an off-label therapy for recalcitrant verruca vulgaris. We describe a man who developed a sleep disturbance after initiating therapy with ranitidine and review similar adverse effects associated with other drugs in this class. The patient was a 40-year-old man with an eight-year history of a wart on his right plantar foot that was recalcitrant to several topical therapies. Adjunctive treatment with ranitidine 150 mg twice daily was initiated. He developed sleep disturbance with bizarre dreams and gastrointestinal symptoms. All symptoms resolved after discontinuation of the medication and recurred when he restarted the drug. PubMed was searched for the following terms: disturbance, dream, ranitidine, verruca, wart, and Zantac. The papers containing these terms and their references were reviewed. Sleep disturbance caused by ranitidine is an uncommon adverse event in patients receiving the drug. However, similar reactions have been observed with other H2 antihistamines such as cimetidine and famotidine. Clinicians should be aware that sleep disturbance secondary to ranitidine is a potential side effect of this medication.

Effects of an orally active vasopressin V1 receptor antagonist.

PubMed

Burrell, L M; Phillips, P A; Stephenson, J; Risvanis, J; Hutchins, A M; Johnston, C I

1993-05-01

1. This paper reports on the in vitro and in vivo characteristics of a non-peptide vasopressin V1 receptor antagonist 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)-3,4-dihydro-2( 1H)- quinolinone (OPC-21268). 2. OPC-21268 caused a concentration-dependent displacement of the selective V1 receptor antagonist radioligand, [125I]-[d(CH2)5, sarcosine7]AVP from vasopressin V1 receptors in rat liver and kidney membranes, inhibitory concentration of 50% (IC50) 4 x 10(-8), 0.3 mol/L liver and 1.5 x 10(-8), 0.2 mol/L kidney. OPC-21268 had little effect on the selective V2 antagonist radioligand [3H]desGly-NH2(9)-d(CH2)5[D-Ileu2, Ileu4]AVP binding to V2 receptors in renal membranes (IC50 > 10(-4) mol/L). 3. After oral administration to rats, OPC-21268 was an effective V1 antagonist to both liver and kidney V1 receptors, in a dose-dependent manner. 4. These studies confirm that OPC-21268 is a potent non-peptide, orally effective V1 vasopressin receptor antagonist.

A randomized controlled study comparing omeprazole and cimetidine for the prophylaxis of stress-related upper gastrointestinal bleeding in patients with intracerebral hemorrhage.

PubMed

Liu, Bo-lin; Li, Bing; Zhang, Xiang; Fei, Zhou; Hu, Shi-jie; Lin, Wei; Gao, Da-kuan; Zhang, Li

2013-01-01

Patients with intracerebral hemorrhage (ICH) are at high risk for severe stress-related upper gastrointestinal (UGI) bleeding, which is predictive of higher mortality. The aim of this study was to evaluate the effectiveness of omeprazole and cimetidine compared with a placebo in the prevention and management of stress-related UGI bleeding in patients with ICH. In a single-center, randomized, placebo-controlled study, 184 surgically treated patients with CT-proven ICH within 72 hours of ictus and negative results for gastric occult blood testing were included. Of these patients, 165 who were qualified upon further evaluation were randomized into 3 groups: 58 patients received 40 mg intravenous omeprazole every 12 hours, 54 patients received 300 mg intravenous cimetidine every 6 hours, and 53 patients received a placebo. Patients whose gastric occult blood tests were positive at admission (n = 70) and during/after the prophylaxis procedure (n = 48) were treated with high-dose omeprazole at 80 mg bolus plus 8 mg/hr infusion for 3 days, followed by 40 mg intravenous omeprazole every 12 hours for 7 days. Of the 165 assessable patients, stress-related UGI bleeding occurred in 9 (15.5%) in the omeprazole group compared with 15 patients (27.8%) in the cimetidine group and 24 patients (45.3%) in the placebo group (p = 0.003). The occurrence of UGI bleeding was significantly related to death (p = 0.022). Nosocomial pneumonia occurred in 14 patients (24.1%) receiving omeprazole, 12 (22.2%) receiving cimetidine, and 8 (15.1%) receiving placebo (p > 0.05). In patients with UGI bleeding in which high-dose omeprazole was initiated, UGI bleeding arrested within the first 3 days in 103 patients (87.3%). Omeprazole significantly reduced the morbidity of stress-related UGI bleeding in patients with ICH due to its effective prophylactic effect without increasing the risk of nosocomial pneumonia, but it did not reduce the 1-month mortality or ICU stay. Further evaluation of high-dose omeprazole as the drug of choice for patients presenting with UGI bleeding is warranted. Clinical trial registration no.: ChiCTR-TRC-12001871, registered at the Chinese clinical trial registry (http://www.chictr.org/en/proj/show.aspx?proj=2384).

Pharmacology of JB-9315, a new selective histamine H2-receptor antagonist.

PubMed

Palacios, B; Montero, M J; Sevilla, M A; San Román, L

1998-02-01

1. The histamine H2-receptor antagonistic activity and antisecretory and antiulcer effects of JB-9315 were studied in comparison with the standard H2 blocker ranitidine. 2. In vitro, JB-9315 is a competitive antagonist of histamine H2 receptors in the isolated, spontaneously beating guinea-pig right atrium, with a pA2 value of 7.30 relative to a value of 7.36 for ranitidine. JB-9315 was specific for the histamine H2 receptor because, at high concentration, it did not affect histamine- or acetylcholine-induced contractions in guinea-pig isolated ileum or rat isolated duodenum, respectively. 3. JB-9315 dose dependently inhibited histamine-, pentagastrin- or carbachol-stimulated acid secretion and basal secretion in the perfused stomach preparation of the anesthetized rat. In the pylorus-ligated rat after intraperitoneal administration, total acid output over 4 h was inhibited by JB-9315 with an ID50 of 32.8 mg/kg, confirming its H2-receptor antagonist properties. 4. JB-9315 showed antiulcer activity against cold stress plus indomethacin-induced lesions with an ID50 of 6.8 mg/kg. 5. JB-9315, 50 and 100 mg/kg, inhibited macroscopic gastric hemorrhagic lesions induced by ethanol. In contrast, ranitidine (50 mg/kg) failed to reduce these lesions. 6. These results indicate that JB-9315 is a new antiulcer drug that exerts a cytoprotective effect in addition to its gastric antisecretory activity.

Novel spirotetracyclic zwitterionic dual H(1)/5-HT(2A) receptor antagonists for the treatment of sleep disorders.

PubMed

Gianotti, Massimo; Botta, Maurizio; Brough, Stephen; Carletti, Renzo; Castiglioni, Emiliano; Corti, Corrado; Dal-Cin, Michele; Delle Fratte, Sonia; Korajac, Denana; Lovric, Marija; Merlo, Giancarlo; Mesic, Milan; Pavone, Francesca; Piccoli, Laura; Rast, Slavko; Roscic, Maja; Sava, Anna; Smehil, Mario; Stasi, Luigi; Togninelli, Andrea; Wigglesworth, Mark J

2010-11-11

Histamine H(1) and serotonin 5-HT(2A) receptors mediate two different mechanisms involved in sleep regulation: H(1) antagonists are sleep inducers, while 5-HT(2A) antagonists are sleep maintainers. Starting from 9'a, a novel spirotetracyclic compound endowed with good H(1)/5-HT(2A) potency but poor selectivity, very high Cli, and a poor P450 profile, a specific optimization strategy was set up. In particular, we investigated the possibility of introducing appropriate amino acid moieties to optimize the developability profile of the series. Following this zwitterionic approach, we were able to identify several advanced leads (51, 65, and 73) with potent dual H(1)/5-HT(2A) activity and appropriate developability profiles. These compounds exhibited efficacy as hypnotic agents in a rat telemetric sleep model with minimal effective doses in the range 3-10 mg/kg po.

Open trial of cimetidine in the prevention of upper gastro-intestinal haemorrhage in patients with severe intracranial injury.

PubMed

Mouawad, E; Deloof, T; Genette, F; Vandesteene, A

1983-01-01

The present study evaluates the efficacy of Cimetidine in the prevention of clinically important gastro-intestinal haemorrhage in patients suffering from severe head injury. Fifty patients (39 males and 11 females) were included in the study. We excluded from the trial patients on anticoagulant therapy or concomitant non-steroid anti-inflammatory agents, pregnant and lactating women, and patients with previous histories of peptic ulcer disease.

Cimetidine: II. Adverse reactions and patterns of use.

PubMed

Freston, J W

1982-11-01

Numerous adverse reactions have been attributed to cimetidine, which is understandable in view of the attention and scrutiny the drug has received, its widespread use, and its systemic effects. The reported frequency of side effects has differed considerably but is surprisingly low in all studies. The drug has caused an array of central nervous system disturbances, gynecomastia, and, rarely, hepatotoxicity, interstitial nephritis, bradycardia, hypotension, and even cardiac arrest. The last complication has occurred with rapid-bolus intravenous injection. Blood dyscrasias have also been rare and usually associated with serious underlying disease or multiple drugs, making it difficult to establish cause and effect in most cases. The drug is used widely to treatment conditions for which it is not approved. Some of these conditions are now believed to respond to cimetidine (gastric ulcer); others are known not to respond (acute upper gastrointestinal bleeding and acute pancreatitis).

Pharmacologic characterization of the oxytocin receptor in human uterine smooth muscle cells.

PubMed

Tahara, A; Tsukada, J; Tomura, Y; Wada, K i; Kusayama, T; Ishii, N; Yatsu, T; Uchida, W; Tanaka, A

2000-01-01

[(3)H]-oxytocin was used to characterize the oxytocin receptor found in human uterine smooth muscle cells (USMC). Specific binding of [(3)H]-oxytocin to USMC plasma membranes was dependent upon time, temperature and membrane protein concentration. Scatchard plot analysis of equilibrium binding data revealed the existence of a single class of high-affinity binding sites with an apparent equilibrium dissociation constant (K(d)) of 0.76 nM and a maximum receptor density (B(max)) of 153 fmol mg(-1) protein. The Hill coefficient (n(H)) did not differ significantly from unity, suggesting binding to homogenous, non-interacting receptor populations. Competitive inhibition of [(3)H]-oxytocin binding showed that oxytocin and vasopressin (AVP) receptor agonists and antagonists displaced [(3)H]-oxytocin in a concentration-dependent manner. The order of potencies for peptide agonists and antagonists was: oxytocin>[Asu(1,6)]-oxytocin>AVP= atosiban>d(CH(2))(5)Tyr(Me)AVP>[Thr(4),Gly(7)]-oxytocin>dDAVP, and for nonpeptide antagonists was: L-371257>YM087>SR 49059>OPC-21268>SR 121463A>OPC-31260. Oxytocin significantly induced concentration-dependent increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) and hyperplasia in USMC. The oxytocin receptor antagonists, atosiban and L-371257, potently and concentration-dependently inhibited oxytocin-induced [Ca(2+)](i) increase and hyperplasia. In contrast, the V(1A) receptor selective antagonist, SR 49059, and the V(2) receptor selective antagonist, SR 121463A, did not potently inhibit oxytocin-induced [Ca(2+)](i) increase and hyperplasia. The potency order of antagonists in inhibiting oxytocin-induced [Ca(2+)](i) increase and hyperplasia was similar to that observed in radioligand binding assays. In conclusion, these data provide evidence that the high-affinity [(3)H]-oxytocin binding site found in human USMC is a functional oxytocin receptor coupled to [Ca(2+)](i) increase and cell growth. Thus human USMC may prove to be a valuable tool in further investigation of the physiologic and pathophysiologic roles of oxytocin in the uterus. British Journal of Pharmacology (2000) 129, 131 - 139

Heterogeneity of binding of muscarinic receptor antagonists in rat brain homogenates

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 (/supmore » 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.« less

Peroral Immunization of Rats with Escherichia coli Heat-Labile Enterotoxin Delivered by Microspheres

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.; Sherman, William T.

1983-01-01

The antigenicity of the Escherichia coli heat-labile enterotoxin was not protected against the adverse effect of gastric acidity when the toxin was given together with bicarbonate for peroral immunization to rats, but immunization with the heat-labile enterotoxin encapsulated in pH-dependent microspheres aroused the same strong degree of serum and mucosal antitoxin responses and of protection against challenge as was achieved by peroral immunization after ablation of gastric secretions by pretreatment with cimetidine. PMID:6339378

Antagonists for the orphan G-protein-coupled receptor GPR55 based on a coumarin scaffold.

PubMed

Rempel, Viktor; Volz, Nicole; Gläser, Franziska; Nieger, Martin; Bräse, Stefan; Müller, Christa E

2013-06-13

The orphan G-protein-coupled receptor GPR55, which is activated by 1-lysophosphatidylinositol and interacts with cannabinoid (CB) receptor ligands, has been proposed as a new potential drug target for the treatment of diabetes, Parkinson's disease, neuropathic pain, and cancer. We applied β-arrestin assays to identify 3-substituted coumarins as a novel class of antagonists and performed an extensive structure-activity relationship study for GPR55. Selectivity versus the related receptors CB1, CB2, and GPR18 was assessed. Among the 7-unsubstituted coumarins selective, competitive GPR55 antagonists were identified, such as 3-(2-hydroxybenzyl)-5-isopropyl-8-methyl-2H-chromen-2-one (12, PSB-SB-489, IC50 = 1.77 μM, pA2 = 0.547 μM). Derivatives with long alkyl chains in position 7 were potent, possibly allosteric GPR55 antagonists which showed ancillary CB receptor affinity. 7-(1,1-Dimethyloctyl)-5-hydroxy-3-(2-hydroxybenzyl)-2H-chromen-2-one (69, PSB-SB-487, IC50 = 0.113 μM, KB = 0.561 μM) and 7-(1,1-dimethylheptyl)-5-hydroxy-3-(2-hydroxybenzyl)-2H-chromen-2-one (67, PSB-SB-1203, IC50 = 0.261 μM) were the most potent GPR55 antagonists of the present series.

Agonist and antagonist actions of antipsychotic agents at 5-HT1A receptors: a [35S]GTPgammaS binding study.

PubMed

Newman-Tancredi, A; Gavaudan, S; Conte, C; Chaput, C; Touzard, M; Verrièle, L; Audinot, V; Millan, M J

1998-08-21

Recombinant human (h) 5-HT1A receptor-mediated G-protein activation was characterised in membranes of transfected Chinese hamster ovary (CHO) cells by use of guanosine-5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS binding). The potency and efficacy of 21 5-HT receptor agonists and antagonists was determined. The agonists, 5-CT (carboxamidotryptamine) and flesinoxan displayed high affinity (subnanomolar Ki values) and high efficacy (Emax > 90%, relative to 5-HT = 100%). In contrast, ipsapirone, zalospirone and buspirone displayed partial agonist activity. EC50s for agonist stimulation of [35S]GTPgammaS binding correlated well with Ki values from competition binding (r = +0.99). Among the compounds tested for antagonist activity, methiothepin and (+)butaclamol exhibited 'inverse agonist' behaviour, inhibiting basal [35S]GTPgammaS binding. The actions of 17 antipsychotic agents were investigated. Clozapine and several putatively 'atypical' antipsychotic agents, including ziprasidone, quetiapine and tiospirone, exhibited partial agonist activity and marked affinity at h5-HT1A receptors, similar to their affinity at hD2 dopamine receptors. In contrast, risperidone and sertindole displayed low affinity at h5-HT1A receptors and behaved as 'neutral' antagonists, inhibiting 5-HT-stimulated [35S]GTPgammaS binding. Likewise the 'typical' neuroleptics, haloperidol, pimozide, raclopride and chlorpromazine exhibited relatively low affinity and 'neutral' antagonist activity at h5-HT1A receptors with Ki values which correlated with their respective Kb values. The present data show that (i) [35S]GTPgammaS binding is an effective method to evaluate the efficacy and potency of agonists and antagonists at recombinant human 5-HT1A receptors. (ii) Like clozapine, several putatively 'atypical' antipsychotic drugs display balanced serotonin h5-HT1A/dopamine hD2 receptor affinity and partial agonist activity at h5-HT1A receptors. (iii) Several 'typical' and some putatively 'atypical' antipsychotic agents displayed antagonist properties at h5-HT1A sites with generally much lower affinity than at hD2 dopamine receptors. It is suggested that agonist activity at 5-HT1A receptors may be of utility for certain antipsychotic agents.

Scombroid fish poisoning: successful treatment with cimetidine.

PubMed

Guss, D A

1998-01-01

Reported is a patient with a clinical syndrome characteristic of scombroid fish poisoning after ingesting yellowfin tuna that may have been allowed to sit at room temperature for some time before preparation. The patient was treated with an intravenous infusion of cimetidine with prompt resolution of a diffuse, well demarcated, erythematous, pruritic rash. The treatment was without sequelae and permitted early discharge from the emergency department. A brief review of scombroid fish poisoning and its treatment is provided.

Involvement of histaminergic and noradrenergic receptors in the oxytocin-induced food intake in neonatal meat-type chicks.

PubMed

Mirnaghizadeh, Seyed Vahid; Zendehdel, Morteza; Babapour, Vahab

2017-03-01

Oxytocin neurons have a physiological role in food intake and energy balance. Several studies have shown that central histaminergic and adrenergic systems synapse on oxytocin neurons but there is no information for their interaction on food intake regulation in birds. The purpose of this study was to examine the effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H1 receptors antagonist), famotidine (histamine H2 receptors antagonist), thioperamide (histamine H3 receptors antagonist), prazosin (α1 receptor antagonist), yohimbine (α2 receptor antagonist), metoprolol (β1 adrenergic receptor antagonist), ICI 118,551 (β2 adrenergic receptor antagonist) and SR59230R (β3 adrenergic receptor antagonist) on oxytocin-induced hypophagia in 3-h food-deprived (FD 3 ) neonatal broiler chicken. In Experiment 1, 3 h-fasted chicks were given an ICV injection of saline, α-FMH (250 nmol), oxytocin (10 μg) and co-injection of α-FMH + oxytocin. Experiments 2-9 were similar to experiment 1 except birds were injected with chlorpheniramine (300 nmol), famotidine (82 nmol), thioperamide (300 nmol), prazosin (10 nmol), yohimbine (13 nmol), metoprolol (24 nmol), ICI 118,551(5 nmol) and SR59230R (20 nmol) instead of α-FMH, respectively. After injection cumulative food intake was measured until 120 min post injection. According to the results, ICV injection of oxytocin significantly decreased food intake in broiler chickens (P < 0.001). ICV injection of α-FMH significantly attenuated hypophagic effect of oxytocin (P < 0.001). Also, co-injection of chlorpheniramine plus oxytocin significantly decreased the effect of oxytocin on food intake (P < 0.001). Co-administration of thioperamide and oxytocin significantly amplified hypophagic effect of oxytocin in chickens (P < 0.001). In addition, ICI 118,551 attenuated hypophagic effect of oxytocin (P < 0.001); while famotidine, prazosin, yohimbine, metoprolol and SR59230R had no effect on oxytocin- induced food intake in FD3 broiler chickens. These results suggest that the effect of oxytocin on food intake is probably mediated by histaminergic (via H1 and H3 receptors) and noradrenergic (via β2 receptors) systems in broiler chickens.

ANTISECRETORY TREATMENT FOR PEDIATRIC GASTROESOPHAGEAL REFLUX DISEASE - A SYSTEMATIC REVIEW.

PubMed

Mattos, Ângelo Zambam de; Marchese, Gabriela Meirelles; Fonseca, Bárbara Brum; Kupski, Carlos; Machado, Marta Brenner

2017-12-01

Proton pump inhibitors and histamine H2 receptor antagonists are two of the most commonly prescribed drug classes for pediatric gastroesophageal reflux disease, but their efficacy is controversial. Many patients are treated with these drugs for atypical manifestations attributed to gastroesophageal reflux, even that causal relation is not proven. To evaluate the use of proton pump inhibitors and histamine H2 receptor antagonists in pediatric gastroesophageal reflux disease through a systematic review. A systematic review was performed, using MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials databases. The search was limited to studies published in English, Portuguese or Spanish. There was no limitation regarding date of publication. Studies were considered eligible if they were randomized-controlled trials, evaluating proton pump inhibitors and/or histamine H2 receptor antagonists for the treatment of pediatric gastroesophageal reflux disease. Studies published only as abstracts, studies evaluating only non-clinical outcomes and studies exclusively comparing different doses of the same drug were excluded. Data extraction was performed by independent investigators. The study protocol was registered at PROSPERO platform (CRD42016040156). After analyzing 735 retrieved references, 23 studies (1598 randomized patients) were included in the systematic review. Eight studies demonstrated that both proton pump inhibitors and histamine H2 receptor antagonists were effective against typical manifestations of gastroesophageal reflux disease, and that there was no evidence of benefit in combining the latter to the former or in routinely prescribing long-term maintenance treatments. Three studies evaluated the effect of treatments on children with asthma, and neither proton pump inhibitors nor histamine H2 receptor antagonists proved to be significantly better than placebo. One study compared different combinations of omeprazole, bethanechol and placebo for the treatment of children with cough, and there is no clear definition on the best strategy. Another study demonstrated that omeprazole performed better than ranitidine for the treatment of extraesophageal reflux manifestations. Ten studies failed to demonstrate significant benefits of proton pump inhibitors or histamine H2 receptor antagonists for the treatment of unspecific manifestations attributed to gastroesophageal reflux in infants. Proton pump inhibitors or histamine H2 receptor antagonists may be used to treat children with gastroesophageal reflux disease, but not to treat asthma or unspecific symptoms.

Supplementation with a recombinant human chorionic gonadotropin microdose leads to similar outcomes in ovarian stimulation with recombinant follicle-stimulating hormone using either a gonadotropin-releasing hormone agonist or antagonist for pituitary suppression.

PubMed

Cavagna, Mario; Maldonado, Luiz Guilherme Louzada; de Souza Bonetti, Tatiana Carvalho; de Almeida Ferreira Braga, Daniela Paes; Iaconelli, Assumpto; Borges, Edson

2010-06-01

To compare the outcomes of protocols for ovarian stimulation with recombinant hCG microdose, with GnRH agonists and antagonists for pituitary suppression. Prospective nonrandomized clinical trial. A private assisted reproduction center. We studied 182 patients undergoing intracytoplasmic sperm injection (ICSI) cycles, allocated into two groups: GnRH agonist group, in which patients received a GnRH agonist (n = 73), and a GnRH antagonist group, in which patients were administered a GnRH antagonist for pituitary suppression (n = 109). Pituitary suppression with GnRH agonist or GnRH antagonist. Ovarian stimulation carried out with recombinant FSH and supplemented with recombinant hCG microdose. Total dose of recombinant FSH and recombinant hCG administered; E(2) concentrations and endometrial width on the day of hCG trigger; number of follicles aspirated, oocytes and mature oocytes retrieved; fertilization, pregnancy (PR), implantation, and miscarriage rates. The total dose of recombinant FSH and recombinant hCG administered were similar between groups, as were the E(2) concentrations and endometrial width. The number of follicles aspirated, oocytes, and metaphase II oocytes collected were also comparable. There were no statistically significant differences in fertilization, PR, implantation, and miscarriage rates in the GnRH agonist and GnRH antagonist groups. When using recombinant hCG microdose supplementation for controlled ovarian stimulation (COS), there are no differences in laboratory or clinical outcomes with the use of either GnRH antagonist or agonist for pituitary suppression. Copyright (c) 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Discovery of sodium R-(+)-4-{2-[5-(2-fluoro-3-methoxyphenyl)-3-(2-fluoro-6-[trifluoromethyl]benzyl)-4-methyl-2,6-dioxo-3,6-dihydro-2H-pyrimidin-1-yl]-1-phenylethylamino}butyrate (elagolix), a potent and orally available nonpeptide antagonist of the human gonadotropin-releasing hormone receptor.

PubMed

Chen, Chen; Wu, Dongpei; Guo, Zhiqiang; Xie, Qiu; Reinhart, Greg J; Madan, Ajay; Wen, Jenny; Chen, Takung; Huang, Charles Q; Chen, Mi; Chen, Yongsheng; Tucci, Fabio C; Rowbottom, Martin; Pontillo, Joseph; Zhu, Yun-Fei; Wade, Warren; Saunders, John; Bozigian, Haig; Struthers, R Scott

2008-12-11

The discovery of novel uracil phenylethylamines bearing a butyric acid as potent human gonadotropin-releasing hormone receptor (hGnRH-R) antagonists is described. A major focus of this optimization was to improve the CYP3A4 inhibition liability of these uracils while maintaining their GnRH-R potency. R-4-{2-[5-(2-fluoro-3-methoxyphenyl)-3-(2-fluoro-6-[trifluoromethyl]benzyl)-4-methyl-2,6-dioxo-3,6-dihydro-2H-pyrimidin-1-yl]-1-phenylethylamino}butyric acid sodium salt, 10b (elagolix), was identified as a potent and selective hGnRH-R antagonist. Oral administration of 10b suppressed luteinizing hormone in castrated macaques. These efforts led to the identification of 10b as a clinical compound for the treatment of endometriosis.

Investigation on Quantitative Structure Activity Relationships and Pharmacophore Modeling of a Series of mGluR2 Antagonists

PubMed Central

Zhang, Meng-Qi; Zhang, Xiao-Le; Li, Yan; Fan, Wen-Jia; Wang, Yong-Hua; Hao, Ming; Zhang, Shu-Wei; Ai, Chun-Zhi

2011-01-01

MGluR2 is G protein-coupled receptor that is targeted for diseases like anxiety, depression, Parkinson’s disease and schizophrenia. Herein, we report the three-dimensional quantitative structure–activity relationship (3D-QSAR) studies of a series of 1,3-dihydrobenzo[ b][1,4]diazepin-2-one derivatives as mGluR2 antagonists. Two series of models using two different activities of the antagonists against rat mGluR2, which has been shown to be very similar to the human mGluR2, (activity I: inhibition of [3H]-LY354740; activity II: mGluR2 (1S,3R)-ACPD inhibition of forskolin stimulated cAMP.) were derived from datasets composed of 137 and 69 molecules respectively. For activity I study, the best predictive model obtained from CoMFA analysis yielded a Q2 of 0.513, R2 ncv of 0.868, R2 pred = 0.876, while the CoMSIA model yielded a Q2 of 0.450, R2 ncv = 0.899, R2 pred = 0.735. For activity II study, CoMFA model yielded statistics of Q2 = 0.5, R2 ncv = 0.715, R2 pred = 0.723. These results prove the high predictability of the models. Furthermore, a combined analysis between the CoMFA, CoMSIA contour maps shows that: (1) Bulky substituents in R7, R3 and position A benefit activity I of the antagonists, but decrease it when projected in R8 and position B; (2) Hydrophilic groups at position A and B increase both antagonistic activity I and II; (3) Electrostatic field plays an essential rule in the variance of activity II. In search for more potent mGluR2 antagonists, two pharmacophore models were developed separately for the two activities. The first model reveals six pharmacophoric features, namely an aromatic center, two hydrophobic centers, an H-donor atom, an H-acceptor atom and an H-donor site. The second model shares all features of the first one and has an additional acceptor site, a positive N and an aromatic center. These models can be used as guidance for the development of new mGluR2 antagonists of high activity and selectivity. This work is the first report on 3D-QSAR modeling of these mGluR2 antagonists. All the conclusions may lead to a better understanding of the mechanism of antagonism and be helpful in the design of new potent mGluR2 antagonists. PMID:22016641

Investigation on quantitative structure activity relationships and pharmacophore modeling of a series of mGluR2 antagonists.

PubMed

Zhang, Meng-Qi; Zhang, Xiao-Le; Li, Yan; Fan, Wen-Jia; Wang, Yong-Hua; Hao, Ming; Zhang, Shu-Wei; Ai, Chun-Zhi

2011-01-01

MGluR2 is G protein-coupled receptor that is targeted for diseases like anxiety, depression, Parkinson's disease and schizophrenia. Herein, we report the three-dimensional quantitative structure-activity relationship (3D-QSAR) studies of a series of 1,3-dihydrobenzo[ b][1,4]diazepin-2-one derivatives as mGluR2 antagonists. Two series of models using two different activities of the antagonists against rat mGluR2, which has been shown to be very similar to the human mGluR2, (activity I: inhibition of [(3)H]-LY354740; activity II: mGluR2 (1S,3R)-ACPD inhibition of forskolin stimulated cAMP.) were derived from datasets composed of 137 and 69 molecules respectively. For activity I study, the best predictive model obtained from CoMFA analysis yielded a Q(2) of 0.513, R(2) (ncv) of 0.868, R(2) (pred) = 0.876, while the CoMSIA model yielded a Q(2) of 0.450, R(2) (ncv) = 0.899, R(2) (pred) = 0.735. For activity II study, CoMFA model yielded statistics of Q(2) = 0.5, R(2) (ncv) = 0.715, R(2) (pred) = 0.723. These results prove the high predictability of the models. Furthermore, a combined analysis between the CoMFA, CoMSIA contour maps shows that: (1) Bulky substituents in R(7), R(3) and position A benefit activity I of the antagonists, but decrease it when projected in R(8) and position B; (2) Hydrophilic groups at position A and B increase both antagonistic activity I and II; (3) Electrostatic field plays an essential rule in the variance of activity II. In search for more potent mGluR2 antagonists, two pharmacophore models were developed separately for the two activities. The first model reveals six pharmacophoric features, namely an aromatic center, two hydrophobic centers, an H-donor atom, an H-acceptor atom and an H-donor site. The second model shares all features of the first one and has an additional acceptor site, a positive N and an aromatic center. These models can be used as guidance for the development of new mGluR2 antagonists of high activity and selectivity. This work is the first report on 3D-QSAR modeling of these mGluR2 antagonists. All the conclusions may lead to a better understanding of the mechanism of antagonism and be helpful in the design of new potent mGluR2 antagonists.

Evaluation of biological activities of new LH-RH antagonists (T-series) in male and female rats.

PubMed

Pinski, J; Yano, T; Janaky, T; Nagy, A; Juhasz, A; Bokser, L; Groot, K; Schally, A V

1993-01-01

A series of new highly potent LH-RH antagonists (T-series) has been synthesized in our laboratory. Among these analogs, antagonists [Ac-D-Nal(2), D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2pr(Car)2)6, D-Ala10]LH-RH (T-140); [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2pr(Ac)2)6, D-Ala10]LH-RH (T-148); [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2pr(For)2)6, D-Ala10]LH-RH (T-151) and [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2bu(For)2)6, D-Ala10]LH-RH (T-159) were the most powerful. Antagonists T-140, T-148 and T-151 produced a complete blockade of ovulation in normal cycling rats at a dose of 1.5 micrograms/rat and antagonist T-159 at a dose of only 0.75 micrograms/rat. The inhibitory effects of compounds T-148, T-151 and T-159 on gonadotropin and sex steroid secretion were investigated in male and female rats. To determine their effect on LH levels in castrated male and ovariectomized female rats, T-148, T-151 and T-159 were injected subcutaneously in doses of 0.625 and 2.5 micrograms/rat. Blood samples were taken at different intervals for 48 h. All three compounds at either dose caused a significant (P < 0.01) decrease in LH levels for more than 6 h. Significant (P < 0.01) inhibition of LH lasted for more than 24 h following a dose of 2.5 micrograms sc of all 3 antagonists in both male and female rats. Serum FSH levels were also suppressed significantly for more than 48 h in castrated male rats by all three antagonists at a dose of 5 micrograms/rat sc.(ABSTRACT TRUNCATED AT 250 WORDS)

Design and synthesis of novel sulfonamide-containing bradykinin hB2 receptor antagonists. 1. Synthesis and SAR of alpha,alpha-dimethylglycine sulfonamides.

PubMed

Fattori, Daniela; Rossi, Cristina; Fincham, Christopher I; Berettoni, Marco; Calvani, Federico; Catrambone, Fernando; Felicetti, Patrizia; Gensini, Martina; Terracciano, Rosa; Altamura, Maria; Bressan, Alessandro; Giuliani, Sandro; Maggi, Carlo A; Meini, Stefania; Valenti, Claudio; Quartara, Laura

2006-06-15

We recently published the extensive in vivo pharmacological characterization of MEN 16132 (J. Pharmacol. Exp. Ther. 2005, 616-623; Eur. J. Pharmacol. 2005, 528, 7), a member of the sulfonamide-containing human B(2) receptor (hB(2)R) antagonists. Here we report, in detail, how this family of compounds was designed, synthesized, and optimized to provide a group of products with subnanomolar affinity for the hB(2)R and high in vivo potency after topical administration to the respiratory tract. The series was designed on the basis of indications from the X-ray structures of the key structural motifs A and B present in known antagonists and is characterized by the presence of an alpha,alpha-dialkyl amino acid. The first lead (17) of the series was submitted to extensive chemical work to elucidate the structural requirements to increase hB(2) receptor affinity and antagonist potency in bioassays expressing the human B(2) receptor (hB(2)R). The following structural features were selected: a 2,4-dimethylquinoline moiety and a piperazine linker acylated with a basic amino acid. The representative lead compound 68 inhibited the specific binding of [(3)H]BK to hB(2)R with a pKi of 9.4 and antagonized the BK-induced inositolphosphate (IP) accumulation in recombinant cell systems expressing the hB(2)R with a pA(2) of 9.1. Moreover, compound 68 when administered (300 nmol/kg) intratracheally in the anesthetized guinea pig, was able to significantly inhibit BK-induced bronchoconstriction for up to 120 min after its administration, while having a lower and shorter lasting effect on hypotension.

A Novel Hydrogen Sulfide-releasing N-Methyl-d-Aspartate Receptor Antagonist Prevents Ischemic Neuronal Death*

PubMed Central

Marutani, Eizo; Kosugi, Shizuko; Tokuda, Kentaro; Khatri, Ashok; Nguyen, Rebecca; Atochin, Dmitriy N.; Kida, Kotaro; Van Leyen, Klaus; Arai, Ken; Ichinose, Fumito

2012-01-01

Physiological levels of H2S exert neuroprotective effects, whereas high concentrations of H2S may cause neurotoxicity in part via activation of NMDAR. To characterize the neuroprotective effects of combination of exogenous H2S and NMDAR antagonism, we synthesized a novel H2S-releasing NMDAR antagonist N-((1r,3R,5S,7r)-3,5-dimethyladamantan-1-yl)-4-(3-thioxo-3H-1,2-dithiol-4-yl)-benzamide (S-memantine) and examined its effects in vitro and in vivo. S-memantine was synthesized by chemically combining a slow releasing H2S donor 4-(3-thioxo-3H-1,2-dithiol-4-yl)-benzoic acid (ACS48) with a NMDAR antagonist memantine. S-memantine increased intracellular sulfide levels in human neuroblastoma cells (SH-SY5Y) 10-fold as high as that was achieved by ACS48. Incubation with S-memantine after reoxygenation following oxygen and glucose deprivation (OGD) protected SH-SY5Y cells and murine primary cortical neurons more markedly than did ACS48 or memantine. Glutamate-induced intracellular calcium accumulation in primary cortical neurons were aggravated by sodium sulfide (Na2S) or ACS48, but suppressed by memantine and S-memantine. S-memantine prevented glutamate-induced glutathione depletion in SH-SY5Y cells more markedly than did Na2S or ACS48. Administration of S-memantine after global cerebral ischemia and reperfusion more robustly decreased cerebral infarct volume and improved survival and neurological function of mice than did ACS48 or memantine. These results suggest that an H2S-releasing NMDAR antagonist derivative S-memantine prevents ischemic neuronal death, providing a novel therapeutic strategy for ischemic brain injury. PMID:22815476

Antagonism of Human Formyl Peptide Receptor 1 (FPR1) by Chromones and Related Isoflavones

PubMed Central

Schepetkin, Igor A.; Kirpotina, Liliya N.; Khlebnikov, Andrei I.; Cheng, Ni; Ye, Richard D.; Quinn, Mark T.

2014-01-01

Formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) expressed on a variety of cell types. Because FPRs play an important role in the regulation of inflammatory reactions implicated in disease pathogenesis, FPR antagonists may represent novel therapeutics for modulating innate immunity. Previously, 4H-chromones were reported to be potent and competitive FPR1 antagonists. In the present studies, 96 additional chromone analogs, including related synthetic and natural isoflavones were evaluated for FPR1 antagonist activity. We identified a number of novel competitive FPR1 antagonists that inhibited fMLF-induced intracellular Ca2+ mobilization in FPR1-HL60 cells and effectively competed with WKYMVm-FITC for binding to FPR1 in FPR1-HL60 and FPR1-RBL cells. Compound 10 (6-hexyl-2-methyl-3-(1-methyl-1H-benzimidazol-2-yl)-4-oxo-4H-chromen-7-yl acetate) was found to be the most potent FPR1-specific antagonist, with binding affinity Ki~100 nM. These chromones inhibited Ca2+ flux and chemotaxis in human neutrophils with nanomolar-micromolar IC50 values. In addition, the most potent novel FPR1 antagonists inhibited fMLF-induced phosphorylation of extracellular signal-regulated kinases (ERK1/2) in FPR1-RBL cells. These antagonists were specific for FPR1 and did not inhibit WKYMVM/WKYMVm-induced intracellular Ca2+ mobilization in FPR2-HL60 cells, FPR3-HL60 cells, RBL cells transfected with murine Fpr1, or interleukin 8-induced Ca2+ flux in human neutrophils and RBL cells transfected with CXC chemokine receptor 1 (CXCR1). Moreover, pharmacophore modeling showed that the active chromones had a significantly higher degree of similarity with the pharmacophore template as compared to inactive analogs. Thus, the chromone/isoflavone scaffold represents a relevant backbone for development of novel FPR1 antagonists. PMID:25450672

Molecular identification and functional characterization of rabbit MATE1 and MATE2-K.

PubMed

Zhang, Xiaohong; Cherrington, Nathan J; Wright, Stephen H

2007-07-01

An electroneutral organic cation (OC)/proton exchanger in the apical membrane of proximal tubules mediates the final step of renal OC excretion. Two members of the multidrug and toxin extrusion family, MATE1 and MATE2-K, were recently identified in human and rodent kidney and proposed to be the molecular basis of renal OC/H(+) exchange. To take advantage of the comparative value of the large database on the kinetic and selectivity characteristics of OC/H(+) exchange that exists for rabbit kidney, we cloned rbMATE1 and rbMATE2-K. The rabbit homologs have 75% (MATE1) and 74% (MATE2-K) amino acid identity to their human counterparts (and 51% identity with each other). rbMATE1 and rbMATE2-K exhibited H(+) gradient-dependent uptake and efflux of tetraethylammonium (TEA) when expressed in Chinese hamster ovary cells. Both transporters displayed similar affinities for selected compounds [IC(50) values within 2-fold for TEA, 1-methyl-4-phenylpyridinium, and quinidine] and very different affinities for others (IC(50) values differing by 8- to 80-fold for choline and cimetidine, respectively). These results indicate that rbMATE1 and rbMATE2-K are multispecific OC/H(+) exchangers with similar, but distinct, functional characteristics. Overall, the selectivity of MATE1 and MATE2-K correlated closely with that observed in rabbit renal brush-border membrane vesicles.

Effect of Premedications in a Murine Model of Asparaginase Hypersensitivity

PubMed Central

Fernandez, Christian A.; Smith, Colton; Karol, Seth E.; Ramsey, Laura B.; Liu, Chengcheng; Pui, Ching-Hon; Jeha, Sima; Evans, William E.; Finkelman, Fred D.

2015-01-01

A murine model was developed that recapitulates key features of clinical hypersensitivity to Escherichia coli asparaginase. Sensitized mice developed high levels of anti-asparaginase IgG antibodies and had immediate hypersensitivity reactions to asparaginase upon challenge. Sensitized mice had complete inhibition of plasma asparaginase activity (P = 4.2 × 10−13) and elevated levels of mouse mast cell protease 1 (P = 6.1 × 10−3) compared with nonsensitized mice. We investigated the influence of pretreatment with triprolidine, cimetidine, the platelet activating factor (PAF) receptor antagonist CV-6209 [2-(2-acetyl-6-methoxy-3,9-dioxo-4,8-dioxa-2,10-diazaoctacos-1-yl)-1-ethyl-pyridinium chloride], or dexamethasone on the severity of asparaginase-induced allergies. Combining triprolidine and CV-6209 was best for mitigating asparaginase-induced hypersensitivity compared with nonpretreated, sensitized mice (P = 1.2 × 10−5). However, pretreatment with oral dexamethasone was the only agent capable of mitigating the severity of the hypersensitivity (P = 0.03) and partially restoring asparaginase activity (P = 8.3 × 10−4). To rescue asparaginase activity in sensitized mice without requiring dexamethasone, a 5-fold greater dose of asparaginase was needed to restore enzyme activity to a similar concentration as in nonsensitized mice. Our results suggest a role of histamine and PAF in asparaginase-induced allergies and indicate that mast cell–derived proteases released during asparaginase allergy may be a useful marker of clinical hypersensitivity. PMID:25573198

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 Central

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

2010-01-01

N-Methyl-d-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca2+-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. PMID:20197375

The comparison of microdose flare-up and multiple dose antagonist protocols based on hCG day estradiol (E2), progesterone (P) and P/E2 ratio among poor responder patients in ICSI-ET cycles.

PubMed

Cicek, M N; Kahyaoglu, I; Kahyaoglu, S

2015-02-01

Elevated progesterone levels surpassing exact treshold values impede endometrial receptivity and decrease clinical pregnancy rates in different responder patients during assisted reproductive techniques. A progesterone (P): estradiol (E2) ratio of > 1 on the day of hCG administration has also been suggested to be a manifestation of low ovarian reserve. The clinical significance of P/E2 ratio on the day of hCG administration was investigated among poor responder patients. Based on the ESHRE Bologna consensus criteria related to poor ovarian response diagnosis, 48 poor responder patients were treated with the microdose flare-up regimen and 34 patients were treated with the multiple-dose GnRH antagonist protocol. All patients were destined to perform a ICSI-ET procedure at the end of the stimulation protocols. Progesterone levels and P/E2 ratios have been detected during controlled ovarian hyperstimulation. In the microdose flare-up group; the duration of stimulation, total gonadotropin dose used and hCG day E2 levels were significantly higher than the multiple dose antagonist group. However, the mean hCG day P/E2 rate in the microdose flare-up group was less than that in the multiple-dose antagonist group. The clinical pregnancy rates were non significantly higher in the multiple dose antagonist protocol group than in microdose flare-up group. Impaired endometrial receptivity caused by elevated P levels results with lower pregnancy rates. Regardless of the selected stimulation protocol, poor responder patients are not prone to exhibit high P and E2 secretion. Increased P/E2 ratio of > 1 on hCG day has limited value to predict cycle outcomes in poor responder patients because of ovarian follicle depletion.

Evidence that tachykinins relax the guinea-pig trachea via nitric oxide release and by stimulation of a septide-insensitive NK1 receptor.

PubMed Central

Figini, M.; Emanueli, C.; Bertrand, C.; Javdan, P.; Geppetti, P.

1996-01-01

1. This study investigated the possibility that tachykinins relax the guinea-pig isolated trachea by releasing nitric oxide (NO) from the epithelium. The types of tachykinin receptor mediating both relaxation and contraction of the trachea were also studied. Isometric tension was recorded in isolated tracheal tube preparations precontracted with acetylcholine (10 microM) in which compounds were administered intraluminally in the presence of phosphoramidon and indomethacin (both 1 microM) and the tachykinin NK2 receptor antagonist, SR 48,968 ((S)-N-methyl-N[4-(4-acetyl amino-4-phenylpiperidino)-2-(3,4-dichlorophenyl)butyl]benzamide), 0.1 microM). 2. In the presence of the inactive enantiomer of an NO-synthase inhibitor, NG-monomethyl-D-arginine (D-NMMA, 100 microM), substance P (SP), neurokinin A (NKA), neurokinin B (NKB) and the selective NK1 receptor agonist, [Sar9, Met(O2)11]-SP, (0.1-10 nM) relaxed tracheal tube preparations. This relaxation was changed into a contraction by pretreatment with the NO-synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA, 100 microM). The effect of L-NMMA on SP- and [Sar9, Met(O2)11]-SP-induced responses was reversed by L-arginine (L-Arg, 1 mM), but not by D-Arg (1 mM). After removal of the epithelium SP, NKA and NKB and [Sar9, Met(O2)11]-SP (0.1-10 nM) evoked contractile responses in the presence of either L-NMMA (100 microM) or D-NMMA (100 microM). The effects of SP and [Sar9, Met(O2)11]-SP obtained in the presence of another NO-synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) or its inactive enantiomer, NG-nitro-D-arginine methyl ester (D-NAME, 100 microM) were similar to those observed with L-NMMA or D-NMMA, respectively. 3. The selective NK1 receptor agonist, [pGlu6, Pro9]-SP(6-11) (septide, 0.1-10 nM) evoked contractile responses of tracheal tube preparations in the presence of either D-NMMA (100 microM) or L-NMMA (100 microM). The log concentration-response curve to septide obtained in the presence of L-NMMA was similar to that obtained in the presence of D-NMMA. [Sar9, Met(O2)11]-SP (0.1-10 nM) relaxed tracheal tube preparations precontracted with septide (1 microM), whereas septide (0.1 nM-1 microM) further contracted tracheal tube preparations precontracted with [Sar9, Met(O2)11]-SP (1 microM). 4. Relaxant and contractile responses evoked by SP, NKA, NKB and by [Sar9, Met(O2)11]-SP (0.1-10 nM) were not affected by a combination of the histamine H1 (pyrilamine, 1 microM) and H2 (cimetidine, 1 microM) receptor antagonists, but were abolished by the tachykinin NK1 receptor antagonist, CP-99,994 ((2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine, 1 microM), though not by its inactive enantiomer CP-100,263 (1 microM). Contractile responses evoked by septide (10 nM and 1 microM) were also abolished by CP-99,994 (1 microM) but not by CP-100,263 (1 microM). 5. These results demonstrate that tachykinins relax guinea-pig tracheal tube preparations by releasing NO via the stimulation of epithelial NK1 receptors by a mechanism independent of histamine release. The NK1 receptor type involved is sensitive to SP, NKA, NKB and [Sar9, Met(O2)11]-SP but not to septide, and is pharmacologically distinct from the NK1 receptor that mediates contraction, which is stimulated by all the agonists, including septide. PMID:8882625

Characteristics of recombinantly expressed rat and human histamine H3 receptors.

PubMed

Wulff, Birgitte S; Hastrup, Sven; Rimvall, Karin

2002-10-18

Human and rat histamine H(3) receptors were recombinantly expressed and characterized using receptor binding and a functional cAMP assay. Seven of nine agonists had similar affinities and potencies at the rat and human histamine H(3) receptor. S-alpha-methylhistamine had a significantly higher affinity and potency at the human than rat receptor, and for 4-[(1R*,2R*)-2-(5,5-dimethyl-1-hexynyl)cyclopropyl]-1H-imidazole (Perceptin) the preference was the reverse. Only two of six antagonists had similar affinities and potencies at the human and the rat histamine H(3) receptor. Ciproxifan, thioperamide and (1R*,2R*)-trans-2-imidazol-4 ylcyclopropyl) (cyclohexylmethoxy) carboxamide (GT2394) had significantly higher affinities and potencies at the rat than at the human histamine H(3) receptor, while for N-(4-chlorobenzyl)-N-(7-pyrrolodin-1-ylheptyl)guanidine (JB98064) the preference was the reverse. All antagonists also showed potent inverse agonism properties. Iodoproxyfan, Perceptin, proxyfan and GR175737, compounds previously described as histamine H(3) receptor antagonists, acted as full or partial agonists at both the rat and the human histamine H(3) receptor. Copyright 2002 Elsevier Science B.V.

Contribution of MATE1 to Renal Secretion of the NMDA Receptor Antagonist Memantine.

PubMed

Müller, Fabian; Weitz, Dietmar; Derdau, Volker; Sandvoss, Martin; Mertsch, Katharina; König, Jörg; Fromm, Martin F

2017-09-05

The weak base memantine is actively secreted into urine, however the underlying mechanisms are insufficiently understood. Potential candidates involved in memantine renal secretion are organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins (MATE1, MATE2-K). The aim of this in vitro study was the examination of the interaction of memantine with OCT2 and MATEs. Memantine transporter inhibition and transport were examined in HEK cells expressing human OCT2, MATE1, or MATE2-K. Monolayers of single- (MDCK-OCT2, MDCK-MATE1) and double-transfected MDCK cells (MDCK-OCT2-MATE1) were used for studies on vectorial, basal to apical memantine transport. Memantine inhibited OCT2-, MATE1-, and MATE2-K-mediated metformin transport with IC 50 values of 3.2, 40.9, and 315.3 μM, respectively. In HEK cells, no relevant memantine uptake by OCT2, MATE1, or MATE2-K was detected. Vectorial transport experiments, however, indicated a role of MATE1 for memantine export: After memantine administration to the basal side of the monolayers, memantine cellular accumulation was considerably lower (MDCK-MATE1 vs MDCK control cells, P < 0.01) and memantine transcellular, basal to apical transport was higher in MATE1 expressing cells (MDCK-MATE1 vs MDCK control cells, P < 0.001 at 60 and 180 min). Both effects were abolished upon addition of the MATE inhibitor cimetidine. These experiments suggest a relevant role of MATE1 for renal secretion of memantine. In the clinical setting, renal elimination of memantine could be impaired by coadministration of MATE inhibitors.

Dopamine receptor antagonists as new mode-of-action insecticide leads for control of Aedes and Culex mosquito vectors.

PubMed

Nuss, Andrew B; Ejendal, Karin F K; Doyle, Trevor B; Meyer, Jason M; Lang, Emma G; Watts, Val J; Hill, Catherine A

2015-03-01

New mode-of-action insecticides are sought to provide continued control of pesticide resistant arthropod vectors of neglected tropical diseases (NTDs). We previously identified antagonists of the AaDOP2 D1-like dopamine receptor (DAR) from the yellow fever mosquito, Aedes aegypti, with toxicity to Ae. aegypti larvae as leads for novel insecticides. To extend DAR-based insecticide discovery, we evaluated the molecular and pharmacological characteristics of an orthologous DAR target, CqDOP2, from Culex quinquefasciatus, the vector of lymphatic filariasis and West Nile virus. CqDOP2 has 94.7% amino acid identity to AaDOP2 and 28.3% identity to the human D1-like DAR, hD1. CqDOP2 and AaDOP2 exhibited similar pharmacological responses to biogenic amines and DAR antagonists in cell-based assays. The antagonists amitriptyline, amperozide, asenapine, chlorpromazine and doxepin were between 35 to 227-fold more selective at inhibiting the response of CqDOP2 and AaDOP2 in comparison to hD1. Antagonists were toxic to both C. quinquefasciatus and Ae. aegypti larvae, with LC50 values ranging from 41 to 208 μM 72 h post-exposure. Orthologous DOP2 receptors identified from the African malaria mosquito, Anopheles gambiae, the sand fly, Phlebotomus papatasi and the tsetse fly, Glossina morsitans, had high sequence similarity to CqDOP2 and AaDOP2. DAR antagonists represent a putative new insecticide class with activity against C. quinquefasciatus and Ae. aegypti, the two most important mosquito vectors of NTDs. There has been limited change in the sequence and pharmacological properties of the DOP2 DARs of these species since divergence of the tribes Culicini and Aedini. We identified antagonists selective for mosquito versus human DARs and observed a correlation between DAR pharmacology and the in vivo larval toxicity of antagonists. These data demonstrate that sequence similarity can be predictive of target potential. On this basis, we propose expanded insecticide discovery around orthologous DOP2 targets from additional dipteran vectors.

Beta-methyl substitution of cyclohexylalanine in Dmt-Tic-Cha-Phe peptides results in highly potent delta opioid antagonists.

PubMed

Tóth, Géza; Ioja, Eniko; Tömböly, Csaba; Ballet, Steven; Tourwé, Dirk; Péter, Antal; Martinek, Tamás; Chung, Nga N; Schiller, Peter W; Benyhe, Sándor; Borsodi, Anna

2007-01-25

The opioid peptide TIPP (H-Tyr-Tic-Phe-Phe-OH, Tic:1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) was substituted with Dmt (2',6'-dimethyltyrosine) and a new unnatural amino acid, beta-MeCha (beta-methyl-cyclohexylalanine). This double substitution led to a new series of opioid peptides displaying subnanomolar delta antagonist activity and mu agonist or antagonist properties depending on the configuration of the beta-MeCha residue. The most promising analog, H-Dmt-Tic-(2S,3S)-beta-MeCha-Phe-OH was a very selective delta antagonist both in the mouse vas deferens (MVD) assay (Ke = 0.241 +/- 0.05 nM) and in radioligand binding assay (K i delta = 0.48 +/- 0.05 nM, K i mu/K i delta = 2800). The epimeric peptide H-Dmt-Tic-(2S,3R)-beta-MeCha-Phe-OH and the corresponding peptide amide turned out to be mixed partial mu agonist/delta antagonists in the guinea pig ileum and MVD assays. Our results constitute further examples of the influence of Dmt and beta-methyl substitution as well as C-terminal amidation on the potency, selectivity, and signal transduction properties of TIPP related peptides. Some of these compounds represent valuable pharmacological tools for opioid research.

Inhibition of rabbit platelet activation in vitro by antagonists of platelet-activating factor (PAF)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cox, C.P.; Wood, K.L.

1986-03-05

The authors used washed, (/sup 3/H)serotonin-labeled rabbit platelets to study the in vitro aggregation and secretion responses induced by graded doses of PAF in the presence or absence of specific antagonists of PAF. These antagonists included CV-3988, L-652,731, triazolam and alprazolam. Platelets were pretreated with either an antagonist or the appropriate diluent for 60 sec prior to the addition of PAF (2 x 10/sup -10/ to 2 x 10/sup -7/ M). Aggregation was monitored continuously and recorded as the height of the aggregation tracing at 60 sec post-PAF. Secretion of (/sup 3/H)-serotonin was measured in a sample of the plateletsmore » removed at 60 sec post-PAF. When 2 x 10/sup -10/ M PAF was used as the stimulus, the concentration of antagonist needed for 50% inhibition (IC/sub 50/) of secretion was obtained at 0.05 ..mu..M, 0.15 ..mu..M, 0.6 ..mu..M and 2.5 ..mu..M, respectively, for L-652,731, CV-3988, triazolam and alprazolam. The corresponding IC/sub 50/ for aggregation was obtained at 0.2 ..mu..M, 0.1 ..mu..M, 1.5 ..mu..M and 6.5 ..mu..M, respectively. The inhibitory effects of these antagonists could be overcome by increasing the dose of PAF used. Although all of the antagonists were capable of completely inhibiting platelet aggregation and secretion, L-652,731 was the most potent PAF antagonist on a molar basis.« less

Synthesis and preliminary evaluation of [3H]PSB-0413, a selective antagonist radioligand for platelet P2Y12 receptors.

PubMed

El-Tayeb, Ali; Griessmeier, Kerstin J; Müller, Christa E

2005-12-15

The selective antagonist radioligand [(3)H]2-propylthioadenosine-5'-adenylic acid (1,1-dichloro-1-phosphonomethyl-1-phosphonyl) anhydride ([(3)H]PSB-0413) was prepared by catalytic hydrogenation of its propargyl precursor with a high specific radioactivity of 74Ci/mmol. In preliminary saturation binding studies, [(3)H]PSB-0413 showed high affinity for platelet P2Y(12) receptors with a K(D) value of 4.57nM. Human platelets had a high density of P2Y(12) receptors exhibiting a B(max) value of 7.66pmol/mg of protein.

Muscarinic receptor M1 and M2 subtypes in the human eye: QNB, pirenzipine, oxotremorine, and AFDX-116 in vitro autoradiography.

PubMed Central

Gupta, N; McAllister, R; Drance, S M; Rootman, J; Cynader, M S

1994-01-01

Muscarinic cholinergic agents are used to lower intraocular pressure in the medical management of glaucoma and subtypes of muscarinic receptors have now been recognised in many tissues including the eye. To localise muscarinic receptors and their M1 and M2 subtypes in the human eye, in vitro ligand binding and autoradiographic techniques with densitometric quantitation on postmortem eye sections were used. As ligands, [3H] quinuclydinyl benzylate (QNB) (non-subtype specific muscarinic antagonist), [3H]pirenzipine (M1 antagonist), [3H]oxotremorine (M2 muscarinic agonist), [3H]AFDX-116(11[(2[diethylaminomethyl]1-piperidinyl)acetyl]5 , 11dihydro-6H-pyrido [2,3b][1,4]benzodiazepine-6-one) (M2 antagonist) were studied. Specific binding sites for QNB, pirenzipine, and AFDX-116 were localised in the entire ciliary muscle, the iris, and ciliary epithelium. [3H]oxotremorine localised only in the longitudinal portion of the ciliary muscle, and additionally, was not localised in the iris or ciliary epithelium. These results suggest that oxotremorine, by binding selectively to receptors on the longitudinal ciliary muscle and inducing its contraction, may modulate outflow facility independently from accommodation and miosis. Images PMID:7918268

Characterization of a novel non-peptide vasopressin V1 receptor antagonist (OPC-21268) in the rat.

PubMed

Burrell, L M; Phillips, P A; Stephenson, J; Risvanis, J; Hutchins, A M; Johnston, C I

1993-08-01

A non-peptide, orally effective, vasopressin (AVP) V1 receptor antagonist 1-(1-[4-(3-acetylaminopropoxy) benzoyl]-4-piperidyl)-3,4-dihydro-2(1H)-quinolinone (OPC-21268) has recently been described. This paper reports the in-vitro and in-vivo characterization of OPC-21268 binding to vasopressin receptors in rat liver and kidney. OPC-21268 caused a concentration-dependent displacement of the selective V1 receptor antagonist radioligand, 125I-labelled [d(CH2)5,sarcosine7]AVP to V1 receptors in both rat liver and kidney medulla membranes. The concentration of OPC-21268 that displaced 50% of specific AVP binding (IC50) was 40 +/- 3 nmol/l for liver V1 and 15 +/- 2 nmol/l for kidney V1 receptors (mean +/- S.E.M.; n = 3). OPC-21268 had little effect on the selective V2 antagonist radioligand [3H]desGly-NH2(9)]d(CH2)5,D-Ile2,Ile4] AVP binding to V2 receptors in renal medulla membranes (IC50 > 0.1 mmol/l). After oral administration to rats, OPC-21268 was an effective V1 antagonist in a time- and dose-dependent manner. Binding kinetic studies showed that OPC-21268 acted as a competitive antagonist at the liver V1 receptor in vitro and in vivo, in addition to its in-vitro competitive effects at the renal V1 receptor. OPC-21268 shows promise as an orally active V1 antagonist.

Progress in the development of histamine H3 receptor antagonists/inverse agonists: a patent review (2013-2017).

PubMed

Łażewska, Dorota; Kieć-Kononowicz, Katarzyna

2018-03-01

Since years, ligands blocking histamine H 3 receptor (H 3 R) activity (antagonists/inverse agonists) are interesting targets in the search for new cures for CNS disorders. Intensive works done by academic and pharmaceutical company researchers have led to many potent and selective H 3 R antagonists/inverse agonists. Some of them have reached to clinical trials. Areas covered: Patent applications from January 2013 to September 2017 and the most important topics connected with H 3 R field are analysed. Espacenet, Patentscope, Pubmed, GoogleScholar or Cochrane Library online databases were principially used to collect all the materials. Expert opinion: The research interest in histamine H 3 R field is still high although the number of patent applications has decreased during the past 4 years (around 20 publications). Complexity of histamine H 3 R biology e.g. many isoforms, constitutive activity, heteromerization with other receptors (dopamine D 2 , D 1 , adenosine A 2A ) and pharmacology make not easy realization and evaluation of therapeutic potential of anti-H 3 R ligands. First results from clinical trials have verified potential utility of histamine H 3 R antagonist/inverse agonists in some diseases. However, more studies are necessary for better understanding of an involvement of the histaminergic system in CNS-related disorders and helping more ligands approach to clinical trials and the market. Lists of abbreviations: hAChEI - human acetylcholinesterase inhibitor; hBuChEI - human butyrylcholinesterase inhibitor; hMAO - human monoamine oxidase; MAO - monoamine oxidase.

Differential involvement of dopamine D-1 and D-2 receptors in the circling behaviour induced by apomorphine, SK & F 38393, pergolide and LY 171555 in 6-hydroxydopamine-lesioned rats.

PubMed

Arnt, J; Hyttel, J

1985-01-01

The antagonistic effect of dopamine (DA) D-1 and D-2 antagonists against circling behaviour induced by various DA agonists in 6-OHDA-lesioned rats has been investigated. DA D-1/D-2 selectivity of agonists in vitro was measured by the stimulatory effect on DA-sensitive adenylate cyclase in rat striatal homogenates (D-1), the inhibitory effect on electrically-induced release of 3H-DA in rabbit striatal slices (D-2) and the affinity to 3H-piflutixol (D-1) and 3H-spiroperidol (D-2) binding sites in rat striatal membranes. The contralateral circling behaviour induced by the DA D-1 agonist SK & F 38393 was blocked by the DA D-1 antagonist, SCH 23390, and by the mixed DA D-1/D-2 antagonist cis(Z)-flupentixol, but was not influenced by the DA D-2 antagonists spiroperidol and clebopride. In contrast, circling behaviour induced by the preferential DA D-2 agonists pergolide and LY 171555 was blocked by clebopride, spiroperidol, and cis(Z)-flupentixol, but weakly or not influenced by SCH 23390. Apomorphine-induced circling behaviour was blocked by cis(Z)-flupentixol, partially antagonized by SCH 23390 and clebopride but not inhibited by spiroperidol, although the time-course of circling was changed. Combinations of SCH 23390 with spiroperidol or clebopride in low doses completely blocked the effect of apomorphine. These results indicate that DA D-1 and D-2 receptors mediate circling behaviour through separate mechanisms which can be independently manipulated with respective agonists and antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Blocking Alcoholic Steatosis in Mice with a Peripherally Restricted Purine Antagonist of the Type 1 Cannabinoid Receptor.

PubMed

Amato, George S; Manke, Amruta; Harris, Danni L; Wiethe, Robert W; Vasukuttan, Vineetha; Snyder, Rodney W; Lefever, Timothy W; Cortes, Ricardo; Zhang, Yanan; Wang, Shaobin; Runyon, Scott P; Maitra, Rangan

2018-05-24

Type 1 cannabinoid receptor (CB1) antagonists have demonstrated promise for the treatment of obesity, liver disease, metabolic syndrome, and dyslipidemias. However, the inhibition of CB1 receptors in the central nervous system can produce adverse effects, including depression, anxiety, and suicidal ideation. Efforts are now underway to produce peripherally restricted CB1 antagonists to circumvent CNS-associated undesirable effects. In this study, a series of analogues were explored in which the 4-aminopiperidine group of compound 2 was replaced with aryl- and heteroaryl-substituted piperazine groups both with and without a spacer. This resulted in mildly basic, potent antagonists of human CB1 (hCB1). The 2-chlorobenzyl piperazine, 25, was found to be potent ( K i = 8 nM); to be >1000-fold selective for hCB1 over hCB2; to have no hERG liability; and to possess favorable ADME properties including high oral absorption and negligible CNS penetration. Compound 25 was tested in a mouse model of alcohol-induced liver steatosis and found to be efficacious. Taken together, 25 represents an exciting lead compound for further clinical development or refinement.

Identification of novel thiazolo[5,4-d]pyrimidine derivatives as human A1 and A2A adenosine receptor antagonists/inverse agonists.

PubMed

Varano, Flavia; Catarzi, Daniela; Falsini, Matteo; Vincenzi, Fabrizio; Pasquini, Silvia; Varani, Katia; Colotta, Vittoria

2018-07-23

In this study a new set of thiazolo[5,4-d]pyrimidine derivatives was synthesized. These derivatives bear different substituents at positions 2 and 5 of the thiazolopyrimidine core while maintaining a free amino group at position-7. The new compounds were tested for their affinity and potency at human (h) A 1 , A 2A , A 2B and A 3 adenosine receptors expressed in CHO cells. The results reveal that the higher affinity of these new set of thiazolopyrimidines is toward the hA 1 and hA 2A adenosine receptors subtypes and is tuned by the substitution pattern at both the 2 and 5 positions of the thiazolopyrimidine nucleus. Functional studies evidenced that the compounds behaved as dual A 1 /A 2A antagonists/inverse agonists. Compound 3, bearing a 5-((2-methoxyphenyl) methylamino) group and a phenyl moiety at position 2, displayed the highest affinity (hA 1 K i  = 10.2 nM; hA 2A K i  = 4.72 nM) and behaved as a potent A 1 /A 2A antagonist/inverse agonist (hA 1 IC 50  = 13.4 nM; hA 2A IC 50  = 5.34 nM). Copyright © 2018 Elsevier Ltd. All rights reserved.

Cost-effectiveness of treatment regimens for the eradication of Helicobacter pylori in duodenal ulcer.

PubMed

Vakil, N; Fennerty, M B

1996-02-01

Eradication of Helicobacter pylori with antimicrobials was recommended by a recent NIH consensus panel for all infected patients with peptic ulcer disease. The precise regimen that should be used for eradication of the infection remains uncertain because of the variety of regimens described, variable results with the regimens, and difficulties in predicting drug compliance outside clinical trials. A decision analysis tree was developed with three regimens that are widely used regimens for the eradication of H. pylori: 1) 2-wk triple drug therapy (metronidazole, bismuth, tetracycline with H2 receptor antagonist), 2) 2-wk omeprazole and amoxicillin, and 3) 2-wk omeprazole and clarithromycin. Traditional H2 receptor antagonist therapy was used for comparison. A 2-yr time period was chosen for study to allow sufficient time for relapse and to evaluate its effect on the treatment strategy. Probabilities for eradication, compliance, and metronidazole resistance were determined from published data, and assumptions were tested by sensitivity analysis. Standard 2-wk triple drug therapy was the least expensive strategy ($720), and conventional H2 receptor antagonist therapy was the most expensive ($1791). Costs with 2-wk therapy with omeprazole and clarithromycin ($768) were lower than with omeprazole and amoxicillin ($1028). Treatment to eradicate H. pylori in infected patients with duodenal ulcer is a less expensive strategy than traditional therapy with H2 receptor antagonists. Triple drug therapy is the optimal regimen in areas where metronidazole resistance rates are < 36% and compliance is > 53%. Omeprazole and amoxicillin is not cost-effective unless eradication rates are greater than 74%. Dual drug therapy with omeprazole and clarithromycin is effective in regions where metronidazole resistance is high or where it is anticipated that there would be poor compliance with the more complicated triple drug therapy regimen.

Evolution of the Bifunctional Lead μ Agonist / δ Antagonist Containing the Dmt-Tic Opioid Pharmacophore.

PubMed

Balboni, Gianfranco; Salvadori, Severo; Trapella, Claudio; Knapp, Brian I; Bidlack, Jean M; Lazarus, Lawrence H; Peng, Xuemei; Neumeyer, John L

2010-02-17

Based on a renewed importance recently attributed to bi- or multifunctional opioids, we report the synthesis and pharmacological evaluation of some analogues derived from our lead μ agonist / δ antagonist, H-Dmt-Tic-Gly-NH-Bzl. Our previous studies focused on the importance of the C-teminal benzyl function in the induction of such bifunctional activity. The introduction of some substituents in the para position of the phenyl ring (-Cl, -CH(3), partially -NO(2), inactive -NH(2)) was found to give a more potent μ agonist / antagonist effect associated with a relatively unmodified δ antagonist activity (pA(2) = 8.28-9.02). Increasing the steric hindrance of the benzyl group (using diphenylmethyl and tetrahydroisoquinoline functionalities) substantially maintained the μ agonist and δ antagonist activities of the lead compound. Finally and quite unexpectedly D-Tic2, considered as a wrong opioid message now; inserted into the reference compound in lieu of L-Tic, provided a μ agonist / δ agonist better than our reference ligand (H-Dmt-Tic-Gly-NH-Ph) and was endowed with the same pharmacological profile.

Amine-free melanin-concentrating hormone receptor 1 antagonists: Novel 1-(1H-benzimidazol-6-yl)pyridin-2(1H)-one derivatives and design to avoid CYP3A4 time-dependent inhibition.

PubMed

Igawa, Hideyuki; Takahashi, Masashi; Shirasaki, Mikio; Kakegawa, Keiko; Kina, Asato; Ikoma, Minoru; Aida, Jumpei; Yasuma, Tsuneo; Okuda, Shoki; Kawata, Yayoi; Noguchi, Toshihiro; Yamamoto, Syunsuke; Fujioka, Yasushi; Kundu, Mrinalkanti; Khamrai, Uttam; Nakayama, Masaharu; Nagisa, Yasutaka; Kasai, Shizuo; Maekawa, Tsuyoshi

2016-06-01

Melanin-concentrating hormone (MCH) is an attractive target for antiobesity agents, and numerous drug discovery programs are dedicated to finding small-molecule MCH receptor 1 (MCHR1) antagonists. We recently reported novel pyridine-2(1H)-ones as aliphatic amine-free MCHR1 antagonists that structurally featured an imidazo[1,2-a]pyridine-based bicyclic motif. To investigate imidazopyridine variants with lower basicity and less potential to inhibit cytochrome P450 3A4 (CYP3A4), we designed pyridine-2(1H)-ones bearing various less basic bicyclic motifs. Among these, a lead compound 6a bearing a 1H-benzimidazole motif showed comparable binding affinity to MCHR1 to the corresponding imidazopyridine derivative 1. Optimization of 6a afforded a series of potent thiophene derivatives (6q-u); however, most of these were found to cause time-dependent inhibition (TDI) of CYP3A4. As bioactivation of thiophenes to form sulfoxide or epoxide species was considered to be a major cause of CYP3A4 TDI, we introduced electron withdrawing groups on the thiophene and found that a CF3 group on the ring or a Cl adjacent to the sulfur atom helped prevent CYP3A4 TDI. Consequently, 4-[(5-chlorothiophen-2-yl)methoxy]-1-(2-cyclopropyl-1-methyl-1H-benzimidazol-6-yl)pyridin-2(1H)-one (6s) was identified as a potent MCHR1 antagonist without the risk of CYP3A4 TDI, which exhibited a promising safety profile including low CYP3A4 inhibition and exerted significant antiobesity effects in diet-induced obese F344 rats. Copyright © 2016 Elsevier Ltd. All rights reserved.

Actions of alpha2 adrenoceptor ligands at alpha2A and 5-HT1A receptors: the antagonist, atipamezole, and the agonist, dexmedetomidine, are highly selective for alpha2A adrenoceptors.

PubMed

Newman-Tancredi, A; Nicolas, J P; Audinot, V; Gavaudan, S; Verrièle, L; Touzard, M; Chaput, C; Richard, N; Millan, M J

1998-08-01

This study examined the activity of chemically diverse alpha2 adrenoceptor ligands at recombinant human (h) and native rat (r) alpha2A adrenoceptors compared with 5-HT1A receptors. First, in competition binding experiments at h alpha2A and h5-HT1A receptors expressed in CHO cells, several compounds, including the antagonists 1-(2-pyrimidinyl)piperazine (1-PP), (+/-)-idazoxan, benalfocin (SKF 86466), yohimbine and RX 821,002, displayed preference for h alpha2A versus h5-HT1A receptors of only 1.4-, 3.6-, 4-, 10- and 11-fold, respectively (based on differences in pKi values). Clonidine, brimonidine (UK 14304), the benzopyrrolidine fluparoxan and the guanidines guanfacine and guanabenz exhibited intermediate selectivity (22- to 31-fold) for h alpha2A receptors. Only the antagonist atipamezole and the agonist dexmedetomidine (DMT) displayed high preference for alpha2 adrenoceptors (1290- and 91-fold, respectively). Second, the compounds were tested for their ability to induce h5-HT1A receptor-mediated G-protein activation, as indicated by the stimulation of [35S]GTPgammaS binding. All except atipamezole and RX 821,002 exhibited agonist activity, with potencies which correlated with their affinity for h5-HT1A receptors. Relative efficacies (Emax values) were 25-35% for guanabenz, guanfacine, WB 4101 and benalfocin, 50-65% for 1-PP, (+/-)-idazoxan and clonidine, and over 70% for fluparoxan, oxymetazoline and yohimbine (relative to 5-HT = 100%). Yohimbine-induced [35S]GTPgammaS binding was inhibited by the selective 5-HT1A receptor antagonist WAY 100,635. In contrast, RX 821,002 was the only ligand which exhibited antagonist activity at h5-HT1A receptors, inhibiting 5-HT-stimulated [35S]GTPgammaS binding. Atipamezole, which exhibited negligeable affinity for 5-HT1A receptors, was inactive. Third, the affinities for r alpha2A differed considerably from the affinities for h alpha2A receptors whereas the affinities for r5-HT1A differed much less from the affinities for h5-HT1A receptors. This affected markedly the affinity ratios of certain compounds. For example, (+/-)-idazoxan was only 3.6-fold selective for h alpha2A versus h5-HT1A but 51-fold selective for r alpha2A versus r5-HT1A receptors. Conversely, yohimbine was tenfold selective for h alpha2A versus h5-HT1A adrenoceptors but 4.2-fold selective for r alpha2A versus r5-HT1A receptors. Nevertheless, both atipamezole and DMT were highly selective for both rat and human alpha2A versus rat or human 5-HT1A receptors. In conclusion, these data indicate that: (1) the agonist DMT and the antagonist atipamezole are the ligands of choice to distinguish alpha2-mediated from 5-HT1A-mediated actions, whilst several of the other compounds show only low or modest selectivity for alpha2A over 5-HT1A receptors; (2) caution should be exercised in experimental and clinical interpretation of the actions of traditionally employed alpha2 ligands, such as clonidine, yohimbine and (+/-)-idazoxan, which exhibit marked agonist activity at 5-HT1A receptors.

Orally active, nonpeptide vasopressin V1 antagonists. A novel series of 1-(1-substituted 4-piperidyl)-3,4-dihdyro-2(1H)-quinolinone.

PubMed

Ogawa, H; Yamamura, Y; Miyamoto, H; Kondo, K; Yamashita, H; Nakaya, K; Chihara, T; Mori, T; Tominaga, M; Yabuuchi, Y

1993-07-09

A series of compounds has been synthesized and demonstrated to be antagonists of V1 receptors both in vitro and in vivo. These compounds are structurally related to the 1-(4-piperidyl)-2(1H)-quinolinones, including OPC-21268, an orally bioavailable AVP V1 antagonist with high V1 specificity. It has been found that the introduction of an acetamide group on the terminal alkoxy chain of 41-44 leads to an increase in oral activity. Certain of these compounds may have efficacy in the study of AVP V1 receptors.

Sleep Homeostatic and Waking Behavioral Phenotypes in Egr3-Deficient Mice Associated with Serotonin Receptor 5-HT2 Deficits.

PubMed

Grønli, Janne; Clegern, William C; Schmidt, Michelle A; Nemri, Rahmi S; Rempe, Michael J; Gallitano, Amelia L; Wisor, Jonathan P

2016-12-01

The expression of the immediate early gene early growth response 3 ( Egr3 ) is a functional marker of brain activity including responses to novelty, sustained wakefulness, and sleep. We examined the role of this gene in regulating wakefulness and sleep. Electroencephalogram/electromyogram (EEG/EMG) were recorded in Egr3 -/- and wild-type (WT) mice during 24 h baseline, 6 h sleep disruption and 6 h recovery. Serotonergic signaling was assessed with 6 h EEG/EMG recordings after injections of nonselective 5-HT2 antagonist (clozapine), selective 5-HT2 antagonists (5-HT2A; MDL100907 and 5-HT2BC; SB206553) and a cocktail of both selective antagonists, administered in a randomized order to each animal. Egr3 -/- mice did not exhibit abnormalities in the timing of wakefulness and slow wave sleep (SWS); however, EEG dynamics in SWS (suppressed 1-3 Hz power) and in quiet wakefulness (elevated 3-8 Hz and 15-35 Hz power) differed in comparison to WT-mice. Egr3 -/- mice showed an exaggerated response to sleep disruption as measured by active wakefulness, but with a blunted increase in homeostatic sleep drive (elevated 1-4 Hz power) relative to WT-mice. Egr3 -/-mice exhibit greatly reduced sedative effects of clozapine at the electroencephalographic level. In addition, clozapine induced a previously undescribed dissociated state (low amplitude, low frequency EEG and a stable, low muscle tone) lasting up to 2 h in WT-mice. Egr3 -/- mice did not exhibit this phenomenon. Selective 5-HT2A antagonist, alone or in combination with selective 5-HT2BC antagonist, caused EEG slowing coincident with behavioral quiescence in WT-mice but not in Egr3 -/- mice. Egr3 has an essential role in regulating cortical arousal, wakefulness, and sleep, presumably by its regulation of 5-HT2 receptors. © 2016 Associated Professional Sleep Societies, LLC.

Melatonin partially protects 661W cells from H2O2-induced death by inhibiting Fas/FasL-caspase-3.

PubMed

Sánchez-Bretaño, Aída; Baba, Kenkichi; Janjua, Uzair; Piano, Ilaria; Gargini, Claudia; Tosini, Gianluca

2017-01-01

Previous studies have shown that melatonin (MEL) signaling is involved in the modulation of photoreceptor viability during aging. Recent work by our laboratory suggested that MEL may protect cones by modulating the Fas/FasL-caspase-3 pathway. In this study, we first investigated the presence of MEL receptors (MT 1 and MT 2 ) in 661W cells, then whether MEL can prevent H 2 O 2 -induced cell death, and last, through which pathway MEL confers protection. The mRNA and proteins of the MEL receptors were detected with quantitative PCR (q-PCR) and immunocytochemistry, respectively. To test the protective effect of MEL, 661W cells were treated with H 2 O 2 for 2 h in the presence or absence of MEL, a MEL agonist, and an antagonist. To study the pathways involved in H 2 O 2 -mediated cell death, a Fas/FasL antagonist was used before the exposure to H 2 O 2 . Finally, Fas/FasL and caspase-3 mRNA was analyzed with q-PCR and immunocytochemistry in cells treated with H 2 O 2 and/or MEL. Cell viability was analyzed by using Trypan Blue. Both MEL receptors (MT 1 and MT 2 ) were detected at the mRNA and protein levels in 661W cells. MEL partially prevented H 2 O 2 -mediated cell death (20-25%). This effect was replicated with IIK7 (a melatonin receptor agonist) when used at a concentration of 1 µM. Preincubation with luzindole (a melatonin receptor antagonist) blocked MEL protection. Kp7-6, an antagonist of Fas/FasL, blocked cell death caused by H 2 O 2 similarly to what was observed for MEL. Fas, FasL, and caspase-3 expression was increased in cells treated with H 2 O 2 , and this effect was prevented by MEL. Finally, MEL treatment partially prevented the activation of caspase-3 caused by H 2 O 2 . The results demonstrate that MEL receptors are present and functional in 661W cells. MEL can prevent photoreceptor cell death induced by H 2 O 2 via the inhibition of the proapoptotic pathway Fas/FasL-caspase-3.

Structure-based prediction of subtype selectivity of histamine H3 receptor selective antagonists in clinical trials.

PubMed

Kim, Soo-Kyung; Fristrup, Peter; Abrol, Ravinder; Goddard, William A

2011-12-27

Histamine receptors (HRs) are excellent drug targets for the treatment of diseases, such as schizophrenia, psychosis, depression, migraine, allergies, asthma, ulcers, and hypertension. Among them, the human H(3) histamine receptor (hH(3)HR) antagonists have been proposed for specific therapeutic applications, including treatment of Alzheimer's disease, attention deficit hyperactivity disorder (ADHD), epilepsy, and obesity. However, many of these drug candidates cause undesired side effects through the cross-reactivity with other histamine receptor subtypes. In order to develop improved selectivity and activity for such treatments, it would be useful to have the three-dimensional structures for all four HRs. We report here the predicted structures of four HR subtypes (H(1), H(2), H(3), and H(4)) using the GEnSeMBLE (GPCR ensemble of structures in membrane bilayer environment) Monte Carlo protocol, sampling ∼35 million combinations of helix packings to predict the 10 most stable packings for each of the four subtypes. Then we used these 10 best protein structures with the DarwinDock Monte Carlo protocol to sample ∼50 000 × 10(20) poses to predict the optimum ligand-protein structures for various agonists and antagonists. We find that E206(5.46) contributes most in binding H(3) selective agonists (5, 6, 7) in agreement with experimental mutation studies. We also find that conserved E5.46/S5.43 in both of hH(3)HR and hH(4)HR are involved in H(3)/ H(4) subtype selectivity. In addition, we find that M378(6.55) in hH(3)HR provides additional hydrophobic interactions different from hH(4)HR (the corresponding amino acid of T323(6.55) in hH(4)HR) to provide additional subtype bias. From these studies, we developed a pharmacophore model based on our predictions for known hH(3)HR selective antagonists in clinical study [ABT-239 1, GSK-189,254 2, PF-3654746 3, and BF2.649 (tiprolisant) 4] that suggests critical selectivity directing elements are: the basic proton interacting with D114(3.32), the spacer, the aromatic ring substituted with the hydrophilic or lipophilic groups interacting with lipophilic pockets in transmembranes (TMs) 3-5-6 and the aliphatic ring located in TMs 2-3-7. These 3D structures for all four HRs should help guide the rational design of novel drugs for the subtype selective antagonists and agonists with reduced side effects.

Discovery of 2-(3,5-difluoro-4-methylsulfonaminophenyl)propanamides as potent TRPV1 antagonists.

PubMed

Kim, Changhoon; Ann, Jihyae; Lee, Sunho; Sun, Wei; Blumberg, Peter M; Frank-Foltyn, Robert; Bahrenberg, Gregor; Stockhausen, Hannelore; Christoph, Thomas; Lee, Jeewoo

2018-05-23

A series of A-region analogues of 2-(3-fluoro-4-methylsufonamidophenyl) propanamide 1 were investigated as TRPV1 antagonists. The analysis of structure-activity relationship indicated that a fluoro group at the 3- (or/and) 5-position and a methylsulfonamido group at the 4-position were optimal for antagonism of TRPV1 activation by capsaicin. The most potent antagonist 6 not only exhibited potent antagonism of activation of hTRPV1 by capsaicin, low pH and elevated temperature but also displayed highly potent antagonism of activation of rTRPV1 by capsaicin. Further studies demonstrated that antagonist 6 blocked the hypothermic effect of capsaicin in vivo, consistent with its in vitro mechanism, and it showed promising analgesic activity in the formalin animal model. Copyright © 2018 Elsevier Ltd. All rights reserved.

Coordinated therapeutic effects of immune modulators and interferon.

PubMed Central

Cerutti, I; Chany, C

1983-01-01

Immune modulators injected 24 h before encephalomyocarditis virus significantly increase antiviral resistance in mice when interferon is administered 1 h after the virus. These immune modulators can be crude bacterial extracts or synthetic drugs. In some cases, the responses are additive; in others, they are clearly cooperative. To protect the mice against the development of 180 TG Crocker sarcomas, the association of bacterial extracts and interferon is highly effective under the condition that the drug concentrations and chronological order and number of injections are well defined. In contrast, the conjunction of interferon and synthetic immune modulators, in particular cimetidine, result in delayed tumor development with no significant change in the final survival rate in the experimental model described here. PMID:6315585

Dopamine D3 and D2 Receptor Mechanisms in the Abuse-Related Behavioral Effects of Cocaine: Studies with Preferential Antagonists in Squirrel Monkeys

PubMed Central

Grundt, Peter; Cao, Jianjing; Platt, Donna M.; Newman, Amy Hauck; Spealman, Roger D.

2010-01-01

Dopamine (DA) D3 and D2 receptor mechanisms are implicated in cocaine's abuse-related behavioral effects, but the relative contribution of the two receptor subtypes is only partially characterized. This study investigated the role of D3 and D2 subtype mechanisms by determining the degree to which the D3-preferring antagonist PG01037 [N-{4-[4-(2,3-dichlorophenyl)-piperazin- 1-yl]-trans-but-2-enyl}-4-pyridine-2-yl-benzamide HCl] and the D2-preferring antagonist L-741626 [3-[4-(4-chlorophenyl)-4- hydroxypiperidin-1-yl]methyl-1H-indole] attenuated several behavioral effects of cocaine in squirrel monkeys. Quantitative observational studies established doses of each antagonist that did not produce untoward effects, which were used in subsequent comparisons. In addition, the ability of the D3-preferring agonist PD128907 [(R-(+)-trans-3,4a,10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano[4,3-b]-1,4-oxazin-9-ol)] and the D2-preferring agonist sumanirole [(R)-5,6-dihydro-5-(methylamino)-4H- imidazo[4,5,1-ij]quinolin-2(1H)-one(Z)-2-butenedioate] to reproduce cocaine's discriminative stimulus (DS) and priming effects were compared. In monkeys trained to discriminate cocaine from vehicle, both DA antagonists attenuated and both DA agonists partially reproduced cocaine's DS effects. PG01037 also selectively attenuated the cocaine-like DS effects of PD128907, whereas L-741626 attenuated the cocaine-like DS effects of both agonists. In self-administration studies, L-741626 nonselectively reduced cocaine- and food-maintained responding, whereas PG01037 was ineffective against either reinforcer. In studies involving reinstatement of extinguished cocaine seeking, both antagonists attenuated cocaine-induced reinstatement of responding, and both agonists induced at least partial reinstatement of cocaine seeking. L-741626 also attenuated sumanirole-induced, but not PD128907-induced, reinstatement of responding, whereas PG01037 was ineffective against either DA agonist. The results are consistent with a role for D3 and D2 receptor mechanisms in cocaine's DS effects and cocaine-induced reinstatement of drug seeking, but provide no evidence for a major role of D3 receptors in the direct reinforcing effects of cocaine. PMID:20494958

An antagonistic monoclonal antibody (B-N6) specific for the human neurotensin receptor-1.

PubMed

Ovigne, J M; Vermot-Desroches, C; Lecron, J C; Portier, M; Lupker, J; Pecceu, F; Wijdenes, J

1998-06-01

The neuropeptide neurotensin (NT) interacts with two types of human receptors (hNTR) termed hNTR-1 and hNTR-2. This study describes a monoclonal antibody (MAb) specific for hNTR-1, B-N6. This MAb binds specifically to hNTR-1, but not to hNTR-2 transfected CHO cells. B-N6 and NT display a reciprocal competition and react in a similar way to trypsin, suggesting that the B-N6 epitope is at or close to the NT binding site on the third extracellular loop. Unlike B-N6, NT induces hNTR-1 internalization. Although neither NT-FITC nor B-N6 binding was detected by flow cytometry on different human cells, specific mRNA expression for hNTR-1 was detected in these cells. In CHO cells expressing hNTR-1 and a luciferase gene coupled to the krox24 reporter, B-N6 and the antagonist SR 48692 inhibited NT-induced intracellular activation of krox24 in a dose-dependent manner. From these results it is concluded that B-N6 is an antagonistic anti-hNTR-1 MAb.

The Affinity of D2-Like Dopamine Receptor Antagonists Determines the Time to Maximal Effect on Cocaine Self-Administration

PubMed Central

Tabet, Michael R.; Norman, Mantana K.; Fey, Brittney K.; Tsibulsky, Vladimir L.; Millard, Ronald W.

2011-01-01

Differences in the time to maximal effect (Tmax) of a series of dopamine receptor antagonists on the self-administration of cocaine are not consistent with their lipophilicity (octanol-water partition coefficients at pH 7.4) and expected rapid entry into the brain after intravenous injection. It was hypothesized that the Tmax reflects the time required for maximal occupancy of receptors, which would occur as equilibrium was approached. If so, the Tmax should be related to the affinity for the relevant receptor population. This hypothesis was tested using a series of nine antagonists having a 2500-fold range of Ki or Kd values for D2-like dopamine receptors. Rats self-administered cocaine at regular intervals and then were injected intravenously with a dose of antagonist, and the self-administration of cocaine was continued for 6 to 10 h. The level of cocaine at the time of every self-administration (satiety threshold) was calculated throughout the session. The satiety threshold was stable before the injection of antagonist and then increased approximately 3-fold over the baseline value at doses of antagonists selected to produce this approximately equivalent maximal magnitude of effect (maximum increase in the equiactive cocaine concentration, satiety threshold; Cmax). Despite the similar Cmax, the mean Tmax varied between 5 and 157 min across this series of antagonists. Furthermore, there was a strong and significant correlation between the in vivo Tmax values for each antagonist and the affinity for D2-like dopamine receptors measured in vitro. It is concluded that the cocaine self-administration paradigm offers a reliable and predictive bioassay for measuring the affinity of a competitive antagonist for D2-like dopamine receptors. PMID:21606176

Synthesis and SAR of highly potent and selective dopamine D3-receptor antagonists: variations on the 1H-pyrimidin-2-one theme.

PubMed

Geneste, Hervé; Amberg, Wilhelm; Backfisch, Gisela; Beyerbach, Armin; Braje, Wilfried M; Delzer, Jürgen; Haupt, Andreas; Hutchins, Charles W; King, Linda L; Sauer, Daryl R; Unger, Liliane; Wernet, Wolfgang

2006-04-01

In our efforts to further pursue one of the most selective dopamine D(3)-receptor antagonists reported to date, we now describe the synthesis and SAR of novel and highly selective dopamine D(3) antagonists based on a 1H-pyridin-2-one or on a urea scaffold. The most potent compounds exhibited K(i) values toward the D(3) receptor in the nano- to subnanomolar range and high selectivity versus the related D(2) dopamine receptor. Thus, 1H-pyridin-2-one 7b displays oral bioavailability (F=37%) as well as brain penetration (brain plasma ratio 3.7) in rat. Within the urea series, an excellent D(3) versus D(2) selectivity (>100-fold) could be achieved by removal of one NH group (compound 6), although bioavailability (rat) was suboptimal (F<10%). These data significantly enhance our understanding of the D(3) pharmacophore and are expected to lead to novel approaches for the treatment of schizophrenia.

International Union of Basic and Clinical Pharmacology. XCVIII. Histamine Receptors

PubMed Central

Chazot, Paul L.; Cowart, Marlon; Gutzmer, Ralf; Leurs, Rob; Liu, Wai L. S.; Stark, Holger; Thurmond, Robin L.; Haas, Helmut L.

2015-01-01

Histamine is a developmentally highly conserved autacoid found in most vertebrate tissues. Its physiological functions are mediated by four 7-transmembrane G protein–coupled receptors (H1R, H2R, H3R, H4R) that are all targets of pharmacological intervention. The receptors display molecular heterogeneity and constitutive activity. H1R antagonists are long known antiallergic and sedating drugs, whereas the H2R was identified in the 1970s and led to the development of H2R-antagonists that revolutionized stomach ulcer treatment. The crystal structure of ligand-bound H1R has rendered it possible to design new ligands with novel properties. The H3R is an autoreceptor and heteroreceptor providing negative feedback on histaminergic and inhibition on other neurons. A block of these actions promotes waking. The H4R occurs on immuncompetent cells and the development of anti-inflammatory drugs is anticipated. PMID:26084539

In vitro study of histamine and histamine receptor ligands influence on the adhesion of purified human eosinophils to endothelium.

PubMed

Grosicki, Marek; Wójcik, Tomasz; Chlopicki, Stefan; Kieć-Kononowicz, Katarzyna

2016-04-15

It is a well-known fact that histamine is involved in eosinophil-dependent inflammatory responses including cellular chemotaxis and migration. Nevertheless, the relative role of histamine receptors in the mechanisms of eosinophils adhesion to endothelial cells is not known. Therefore the aim of presented study was to examine the effect of selective histamine receptors ligands on eosinophils adhesion to endothelium. For that purpose the highly purified human eosinophils have been isolated from the peripheral blood. The viability and functional integrity of isolated eosinophils have been validated in several tests. Histamine as well as 4-methylhistamine (selective H4 agonist) in concentration-dependent manner significantly increased number of eosinophils that adhere to endothelium. Among the selective histamine receptors antagonist or H1 inverse agonist only JNJ7777120 (histamine H4 antagonist) and thioperamide (dual histamine H3/H4 antagonist) had direct effect on eosinophils adhesion to endothelial cells. Antagonists of H1 (diphenhydramine, mepyramine) H2 (ranitidine and famotidine) and H3 (pitolisant) histamine receptors were ineffective. To the best of our knowledge, this is the first study to demonstrate that histamine receptor H4 plays a dominant role in histamine-induced eosinophils adhesion to endothelium. Copyright © 2016 Elsevier B.V. All rights reserved.

Functional rescue of the constitutively internalized V2 vasopressin receptor mutant R137H by the pharmacological chaperone action of SR49059.

PubMed

Bernier, Virginie; Lagacé, Monique; Lonergan, Michèle; Arthus, Marie-Françoise; Bichet, Daniel G; Bouvier, Michel

2004-08-01

In most cases, nephrogenic diabetes insipidus results from mutations in the V2 vasopressin receptor (V2R) gene that cause intracellular retention of improperly folded receptors. We previously reported that cell permeable V2R antagonists act as pharmacological chaperones that rescue folding, trafficking, and function of several V2R mutants. More recently, the vasopressin antagonist, SR49059, was found to be therapeutically active in nephrogenic diabetes insipidus patients. Three of the patients with positive responses harbored the mutation R137H, previously reported to lead to constitutive endocytosis. This raises the possibility that, instead of acting as a pharmacological chaperone by favoring proper maturation of the receptors, SR49059 could mediate its action on R137H V2R by preventing its endocytosis. Here we report that the beta-arrestin-mediated constitutive endocytosis of R137H V2R is not affected by SR49059, indicating that the functional rescue observed does not result from a stabilization of the receptor at the cell surface. Moreover, metabolic labeling revealed that R137H V2R is also poorly processed to the mature form. SR49059 treatment significantly improved its maturation and cell surface targeting, indicating that the functional rescue of R137H V2Rs results from the pharmacological chaperone action of the antagonist.

Quantitative analysis of rat brain alpha 2-receptors discriminated by [3H]clonidine and [3H]rauwolscine.

PubMed

Asakura, M; Tsukamoto, T; Imafuku, J; Matsui, H; Ino, M; Hasegawa, K

1984-10-30

Quantitative analysis of direct ligand binding of both [3H]clonidine and [3H]rauwolscine to the rat cerebral cortex alpha 2-receptors indicates the existence of two affinity states of the same receptor populations. In the presence of Mn2+, the high affinity state of [3H]clonidine binding was increased, whereas the high affinity state of [3H]rauwolscine binding was reduced. By contrast, GTP in micromolar ranges caused a decrease of the agonist high affinity state and an increase of the antagonist high affinity state. The total receptor sites and the respective separate affinities for both radioligands were approximately equal to their control values under all conditions, indicating that Mn2+ and GTP modulate the proportion of the two affinity states of the receptor. These results can be incorporated into a two-step, ternary complex model involving a guanine nucleotide binding protein (N protein) for the agonist and antagonist interaction with the alpha 2-receptor. Furthermore, the effects of GTP on the interaction of both ligands with the two affinity states can be mimicked by EDTA. It is suggested that divalent cations induce the formation of the receptor-N protein binary complex showing high affinity for agonists and low affinity for antagonists.

Rational Design, Pharmacomodulation, and Synthesis of Dual 5-Hydroxytryptamine 7 (5-HT7)/5-Hydroxytryptamine 2A (5-HT2A) Receptor Antagonists and Evaluation by [(18)F]-PET Imaging in a Primate Brain.

PubMed

Deau, Emmanuel; Robin, Elodie; Voinea, Raluca; Percina, Nathalie; Satała, Grzegorz; Finaru, Adriana-Luminita; Chartier, Agnès; Tamagnan, Gilles; Alagille, David; Bojarski, Andrzej J; Morisset-Lopez, Séverine; Suzenet, Franck; Guillaumet, Gérald

2015-10-22

We report the synthesis of 46 tertiary amine-bearing N-alkylated benzo[d]imidazol-2(3H)-ones, imidazo[4,5-b]pyridin-2(3H)-ones, imidazo[4,5-c]pyridin-2(3H)-ones, benzo[d]oxazol-2(3H)-ones, oxazolo[4,5-b]pyridin-2(3H)-ones and N,N'-dialkylated benzo[d]imidazol-2(3H)-ones. These compounds were evaluated against 5-HT7R, 5-HT2AR, 5-HT1AR, and 5-HT6R as potent dual 5-HT7/5-HT2A serotonin receptors ligands. A thorough study of the structure-activity relationship of the aromatic rings and their substituents, the alkyl chain length and the tertiary amine was conducted. 1-(4-(4-(4-Fluorobenzoyl)piperidin-1-yl)butyl)-1H-benzo[d]imidazol-2(3H)-one (79) and 1-(6-(4-(4-fluorobenzoyl)piperidin-1-yl)hexyl)-1H-benzo[d]imidazol-2(3H)-one (81) were identified as full antagonist ligands on cyclic adenosine monophosphate (cAMP, KB = 4.9 and 5.9 nM, respectively) and inositol monophosphate (IP1, KB = 0.6 and 16 nM, respectively) signaling pathways of 5-HT7R and 5-HT2AR. Both antagonists crossed the blood-brain barrier as evaluated with [(18)F] radiolabeled compounds [(18)F]79 and [(18)F]81 in a primate's central nervous system using positron emission tomography. Both radioligands showed standard uptake values ranging from 0.8 to 1.1, a good plasmatic stability, and a distribution consistent with 5-HT7R and 5-HT2AR in the CNS.

Pharmacological and molecular characterization of muscarinic receptor subtypes in human esophageal smooth muscle.

PubMed

Preiksaitis, H G; Krysiak, P S; Chrones, T; Rajgopal, V; Laurier, L G

2000-12-01

Esophageal peristalsis is dependent on activation of muscarinic receptors, but little is known about the roles of specific receptor subtypes in the human esophagus. We examined muscarinic receptor expression and function in human esophageal smooth muscle obtained from patients undergoing resection for cancer. [(3)H]Quinuclidinyl benzylate (QNB)-specific binding was similar in longitudinal muscle (B(max) = 106 +/- 22 fmol/mg of protein, K(d) = 68 +/- 9 pM) and circular muscle (B(max) = 81 +/- 16 fmol/mg of protein, K(d) = 79 +/- 15 pM). Subtype-selective antagonists inhibited [(3)H]QNB similarly in muscle from both layers. Further analysis of antagonist inhibition of [(3)H]QNB binding showed a major site (60-70%) with antagonist affinity profile consistent with the M2 subtype and a second site that could not be classified. Reverse transcription-polymerase chain reaction and immunoblotting demonstrated the presence of all five known muscarinic receptor subtypes, and immunocytochemistry on acutely isolated smooth muscle cells confirmed the expression of each subtype on the muscle cells. Subtype-selective antagonists had similar inhibitory effects on carbachol-evoked contractions in longitudinal muscle and circular muscle strips with pA(2) values of 9.5 +/- 0.1 and 9.6 +/- 0.2 for 4-diphenylacetoxy-N-methylpiperidine methiodide, 7.1 +/- 0.1 and 7.0 +/- 0.2 for pirenzepine, and 6.2 +/- 0.2 and 6.4 +/- 0.2 for methoctramine, respectively. We conclude that human esophageal smooth muscle expresses muscarinic receptor subtypes M1 through M5. The antagonist sensitivity profile for muscle contraction is consistent with activation of the M3 subtype.

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.

Angiotensin AT1 and AT2 receptor antagonists modulate nicotine-evoked [³H]dopamine and [³H]norepinephrine release.

PubMed

Narayanaswami, Vidya; Somkuwar, Sucharita S; Horton, David B; Cassis, Lisa A; Dwoskin, Linda P

2013-09-01

Tobacco smoking is the leading preventable cause of death in the United States. A major negative health consequence of chronic smoking is hypertension. Untoward addictive and cardiovascular sequelae associated with chronic smoking are mediated by nicotine-induced activation of nicotinic receptors (nAChRs) within striatal dopaminergic and hypothalamic noradrenergic systems. Hypertension involves both brain and peripheral angiotensin systems. Activation of angiotensin type-1 receptors (AT1) release dopamine and norepinephrine. The current study determined the role of AT1 and angiotensin type-2 (AT2) receptors in mediating nicotine-evoked dopamine and norepinephrine release from striatal and hypothalamic slices, respectively. The potential involvement of nAChRs in mediating effects of AT1 antagonist losartan and AT2 antagonist, 1-[[4-(dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid (PD123319) was evaluated by determining their affinities for α4β2* and α7* nAChRs using [³H]nicotine and [³H]methyllycaconitine binding assays, respectively. Results show that losartan concentration-dependently inhibited nicotine-evoked [³H]dopamine and [³H]norepinephrine release (IC₅₀: 3.9 ± 1.2 and 2.2 ± 0.7 μM; Imax: 82 ± 3 and 89 ± 6%, respectively). In contrast, PD123319 did not alter nicotine-evoked norepinephrine release, and potentiated nicotine-evoked dopamine release. These results indicate that AT1 receptors modulate nicotine-evoked striatal dopamine and hypothalamic norepinephrine release. Furthermore, AT1 receptor activation appears to be counteracted by AT2 receptor activation in striatum. Losartan and PD123319 did not inhibit [³H]nicotine or [³H]methyllycaconitine binding, indicating that these AT1 and AT2 antagonists do not interact with the agonist recognition sites on α4β2* and α7* nAChRs to mediate these effects of nicotine. Thus, angiotensin receptors contribute to the effects of nicotine on dopamine and norepinephrine release in brain regions involved in nicotine reward and hypertension. Copyright © 2013 Elsevier Inc. All rights reserved.

Discovery of 5-Chloro-1-(5-chloro-2-(methylsulfonyl)benzyl)-2-imino-1,2-dihydropyridine-3-carboxamide (TAK-259) as a Novel, Selective, and Orally Active α1D Adrenoceptor Antagonist with Antiurinary Frequency Effects: Reducing Human Ether-a-go-go-Related Gene (hERG) Liabilities.

PubMed

Sakauchi, Nobuki; Kohara, Yasuhisa; Sato, Ayumu; Suzaki, Tomohiko; Imai, Yumi; Okabe, Yuichi; Imai, Shigemitsu; Saikawa, Reiko; Nagabukuro, Hiroshi; Kuno, Haruhiko; Fujita, Hisashi; Kamo, Izumi; Yoshida, Masato

2016-04-14

A novel structural class of iminopyridine derivative 1 was identified as a potent and selective human α1D adrenoceptor (α1D adrenergic receptor; α1D-AR) antagonist against α1A- and α1B-AR through screening of an in-house compound library. From initial structure-activity relationship studies, we found lead compound 9m with hERG K(+) channel liability. To develop analogues with reduced hERG K(+) channel inhibition, a combination of site-directed mutagenesis and docking studies was employed. Further optimization led to the discovery of (R)-9s and 9u, which showed antagonistic activity by a bladder strip test in rats with bladder outlet obstruction, as well as ameliorated cystitis-induced urinary frequency in rats. Ultimately, 9u was selected as a clinical candidate. This is the first study to show the utility of iminopyridine derivatives as selective α1D-AR antagonists and evaluate their effects in vivo.

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 ...

Structure-5-HT/D2 Receptor Affinity Relationship in a New Group of 1-Arylpiperazynylalkyl Derivatives of 8-Dialkylamino-3,7-dimethyl-1H-purine-2,6(3H,7H)-dione.

PubMed

Żmudzki, Paweł; Satała, Grzegorz; Chłoń-Rzepa, Grażyna; Bojarski, Andrzej J; Kazek, Grzegorz; Siwek, Agata; Gryboś, Anna; Głuch-Lutwin, Monika; Wesołowska, Anna; Pawłowski, Maciej

2016-10-01

In our previous papers, we have reported that some 8-amino-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione derivatives possessed high affinity and displayed agonistic, partial agonistic, or antagonistic activity for serotonin 5-HT 1A and dopamine D 2 receptors. In order to examine further the influence of the substituent in the position 8 of the purine moiety and the influence of the xanthine core on the affinity for serotonin 5-HT 1A , 5-HT 2A , 5-HT 6 , 5-HT 7 , and dopamine D 2 receptors, two series of 1-arylpiperazynylalkyl derivatives of 8-amino-3,7-dimethyl-1H-purine-2,6(3H,7H)-dione were synthesized. All the final compounds were investigated in in vitro competition binding experiments for the serotonin 5-HT 1A , 5-HT 2A , 5-HT 6 , 5-HT 7 , and dopamine D 2 receptors. The structure-affinity relationships for this group of compounds were discussed. For selected compounds, the functional assays for the 5-HT 1A and D 2 receptors were carried out. The results of the assays indicated that these groups of derivatives possessed antagonistic activity for 5-HT 1A receptors and agonistic, partial agonistic, or antagonistic activity for D 2 receptors. In total, 26 new compounds were synthesized, 20 of which were tested in in vitro binding experiments and 5 were tested in in vitro functional assays. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discovery of Tertiary Sulfonamides as Potent Liver X Receptor Antagonists

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuercher, William J.; Buckholz†, Richard G.; Campobasso, Nino

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.

Discovery of tertiary sulfonamides as potent liver X receptor antagonists.

PubMed

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

2010-04-22

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.

Bisquaternary dimers of strychnine and brucine. A new class of potent enhancers of antagonist binding to muscarinic M2 receptors.

PubMed

Zlotos, D P; Buller, S; Holzgrabe, U; Mohr, K

2003-06-12

Bisquaternary dimers of strychnine and brucine were synthesized and their allosteric effect on muscarinic acetylcholine M(2) receptors was examined. The compounds retarded the dissociation of the antagonist [(3)H]N-methylscopolamine ([(3)H]NMS) from porcine cardiac cholinoceptors. This action indicated ternary complex formation. All compounds exhibited higher affinity to the allosteric site of [(3)H]NMS-occupied M(2) receptors than the monomeric strychnine and brucine, while the positive cooperativity with NMS was fully maintained. SAR studies revealed the unchanged strychnine ring as an important structural feature for high allosteric potency.

Protective effect of histamine H2 receptor antagonist ranitidine against rotenone-induced apoptosis.

PubMed

Park, Hae Jeong; Kim, Hak Jae; Park, Hyun-Kyung; Chung, Joo-Ho

2009-11-01

Histamine H(2) receptor antagonists have been reported to improve the motor symptoms of Parkinson's disease (PD) patients and to exert neuroprotective effects. In this study, we investigated the protective effects of the H(2) receptor antagonist ranitidine on rotenone-induced apoptosis in human dopaminergic SH-SY5Y cells, focusing on mitogen-activated protein kinases (MAPKs) and caspases (CASPs)-mediated apoptotic events. Ranitidine blocked the rotenone-induced phosphorylation of c-Jun NH(2)-terminal protein kinase (JNK) and P38 MAPK (P38), and promoted the phosphorylation of extracellular signal-regulated protein kinase (ERK). Ranitidine also prevented the down-regulation of B-cell CLL/lymphoma 2 (BCL2) and the up-regulation of BCL2-associated X protein (BAX) by rotenone. Furthermore, ranitidine not only attenuated rotenone-induced cleavages of CASP9, poly(ADP-ribose) polymerase-1 (PARP) and CASP3, but also suppressed CASP3 enzyme activity. These results indicate that ranitidine protects against rotenone-induced apoptosis, inhibiting phosphorylation of JNK and P38, and activation of CASPs in human dopaminergic SH-SY5Y cells.

Sleep Homeostatic and Waking Behavioral Phenotypes in Egr3-Deficient Mice Associated with Serotonin Receptor 5-HT2 Deficits

PubMed Central

Grønli, Janne; Clegern, William C.; Schmidt, Michelle A.; Nemri, Rahmi S.; Rempe, Michael J.; Gallitano, Amelia L.; Wisor, Jonathan P.

2016-01-01

Study Objective: The expression of the immediate early gene early growth response 3 (Egr3) is a functional marker of brain activity including responses to novelty, sustained wakefulness, and sleep. We examined the role of this gene in regulating wakefulness and sleep. Methods: Electroencephalogram/electromyogram (EEG/EMG) were recorded in Egr3-/- and wild-type (WT) mice during 24 h baseline, 6 h sleep disruption and 6 h recovery. Serotonergic signaling was assessed with 6 h EEG/EMG recordings after injections of nonselective 5-HT2 antagonist (clozapine), selective 5-HT2 antagonists (5-HT2A; MDL100907 and 5-HT2BC; SB206553) and a cocktail of both selective antagonists, administered in a randomized order to each animal. Results: Egr3-/- mice did not exhibit abnormalities in the timing of wakefulness and slow wave sleep (SWS); however, EEG dynamics in SWS (suppressed 1–3 Hz power) and in quiet wakefulness (elevated 3–8 Hz and 15–35 Hz power) differed in comparison to WT-mice. Egr3-/- mice showed an exaggerated response to sleep disruption as measured by active wakefulness, but with a blunted increase in homeostatic sleep drive (elevated 1–4 Hz power) relative to WT-mice. Egr3-/-mice exhibit greatly reduced sedative effects of clozapine at the electroencephalographic level. In addition, clozapine induced a previously undescribed dissociated state (low amplitude, low frequency EEG and a stable, low muscle tone) lasting up to 2 h in WT-mice. Egr3-/- mice did not exhibit this phenomenon. Selective 5-HT2A antagonist, alone or in combination with selective 5-HT2BC antagonist, caused EEG slowing coincident with behavioral quiescence in WT-mice but not in Egr3-/- mice. Conclusion: Egr3 has an essential role in regulating cortical arousal, wakefulness, and sleep, presumably by its regulation of 5-HT2 receptors. Citation: Grønli J, Clegern WC, Schmidt MA, Nemri RS, Rempe MJ, Gallitano AL, Wisor JP. Sleep homeostatic and waking behavioral phenotypes in Egr3-deficient mice associated with serotonin receptor 5-HT2 deficits. SLEEP 2016;39(12):2189–2199. PMID:28057087

The antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine in the mouse forced swimming test is mediated by serotonergic and dopaminergic systems.

PubMed

Pesarico, Ana Paula; Sampaio, Tuane Bazanella; Stangherlin, Eluza Curte; Mantovani, Anderson C; Zeni, Gilson; Nogueira, Cristina Wayne

2014-10-03

The aim of the present study was to investigate the role of monoaminergic system in the antidepressant-like action of 7-fluoro-1,3-diphenylisoquinoline-1-amine (FDPI), a derivative of isoquinoline class, in Swiss mice. The antidepressant-like effect of FDPI was characterized in the modified forced swimming test (FST) and the possible mechanism of action was investigated by using serotonergic, dopaminergic and noradrenergic antagonists. Monoamine oxidase (MAO) activity and [(3)H]serotonin (5-HT) uptake were determined in prefrontal cortices of mice. The results showed that FDPI (1, 10 and 20mg/kg, i.g.) reduced the immobility time and increased the swimming time but did not alter climbing time in the modified FST. These effects were similar to those of paroxetine (8mg/kg, i.p.), a positive control. Pretreatments with p-chlorophenylalanine (100mg/kg, i.p., an inhibitor of 5-HT synthesis), WAY100635 (0.1mg/kg, s.c., 5-HT1A antagonist), ondansetron (1mg/kg, i.p., a 5-HT3 receptor antagonist), haloperidol (0.2mg/kg, i.p., a non-selective D2 receptor antagonist) and SCH23390 (0.05mg/kg, s.c., a D1 receptor antagonist) were effective to block the antidepressant-like effect of FDPI at a dose of 1mg/kg in the FST. Ritanserin (1mg/kg, i.p., a 5-HT2A/2C receptor antagonist), sulpiride (50mg/kg, i.p., a D2 and D3 receptor antagonist), prazosin (1mg/kg, i.p., an α1 receptor antagonist), yohimbine (1mg/kg, i.p., an α2 receptor antagonist) and propranolol (2mg/kg, i.p., a β receptor antagonist) did not modify the effect of FDPI in the FST. FDPI did not change synaptosomal [(3)H]5-HT uptake. At doses of 10 and 20mg/kg FDPI inhibited MAO-A and MAO-B activities. These results suggest that antidepressant-like effect of FDPI is mediated mostly by serotonergic and dopaminergic systems. Copyright © 2014 Elsevier Inc. All rights reserved.

Neurotransmitter-mediated anxiogenic action of PACAP-38 in rats.

PubMed

Telegdy, G; Adamik, A

2015-03-15

The action of PACAP-38 was studied by measuring the anxiogenic-anxiolytic behavior of rats in an elevated plus maze. PACAP-38 was administered into the lateral brain ventricle and the behavior of the animals was measured 3h later. The possible involvement of transmitters was measured by pretreating the animals with receptor blockers which alone did not influence the task, but in the doses used were effective with other neuropeptides. The receptor antagonist PACAP 6-38 (a PAC 1/VPAC2 receptor antagonist of PACAP-38 receptor), haloperidol (a non-selective dopamine receptor antagonist), phenoxybenzamine (an α1/α2β-adrenergic receptor antagonist), propranolol(a β-adrenergic receptor antagonist), bicuculline (a gamma-aminobutyric acid subunit A receptor antagonist), methysergide (a nonselective 5-HT2 serotonergic receptor antagonist), atropine (a nonselective muscarinic acetylcholine receptor antagonist), naloxone (a nonselective opioid receptor antagonist) and nitro-l-arginine which acts by blocking the enzyme nitric oxide synthase, thereby blocking the nitric oxide synthesis, were tested. The following parameters were measured: the time spent in open arms/the time spent in total entries. PACAP-38 decreased the ratio of time spent in open arms to the time spent in total entries, indicating anxiogenic action. The total number of entries was not altered significantly either by PACAP-38 or by the receptor blockers. The following receptor blockers diminished the action of PACAP-38: PACAP 6-38,haloperidol, methysergide, naloxone and nitro-l-arginine. Pretreatment with atropine, phenoxybenzamine, propranolol and bicuculline did not influence the action of PACAP-38 on the time spent in open arms. The results demonstrate that PACAP-38 administered into the lateral brain ventricle exerted anxiogenic action at 3 h following treatment. Pretreatment of the animals with various receptor blockers indicated that a nonselective dopaminergic receptor antagonist, 5HT2 serotonergic and opioid receptors, nitric oxide and PAC1 receptors are involved in the anxiogenic action induced by PACAP-38. Copyright © 2014 Elsevier B.V. All rights reserved.

Pentadecapeptide BPC 157 and anaphylactoid reaction in rats and mice after intravenous dextran and white egg administration.

PubMed

Duplancic, Bozidar; Stambolija, Vasilije; Holjevac, Jadranka; Zemba, Mladen; Balenovic, Igor; Drmic, Domagoj; Suran, Jelena; Radic, Bozo; Filipovic, Marinko; Blagaic, Alenka Boban; Brcic, Luka; Kolenc, Danijela; Grabarevic, Zeljko; Seiwerth, Sven; Sikiric, Predrag

2014-03-15

Anesthetized mice or rats received intravenously 6%, 10%, 20%, 40%, 60%, 80%, and 90% dextran and/or white egg (1ml/rat or 0.15ml/mouse) into their tails. Medication (/kg b.w., 5ml/kg) was given intraperitoneally (BPC 157 10µg, 1µg, 10ng, and 10pg/kg, chloropyramine 20mg/kg, and cimetidine 10mg/kg intraperitoneally, alone or in combination while controls received an equivolume of saline), immediately after challenge or, alternatively, at 5min after or 24 or 48h before challenge. The effect was assessed at 5, 10, 20 and 30min after dextran and/or white egg challenge. We commonly noted prominent edema involving the face, upper and lower lip, snout, paws and scrotum (presented with extreme cyanosis), poor respiration and the number of fatalities after dextran and/or white egg application. Contrary, BPC 157 regimens (10µg, 1µg, 10ng, and 10pg/kg) effectively, may both prevent anaphylactoid reactions that may arise from dextran and/or white egg application and furthermore, rescue already advanced reactions when given after the challenge. Chloropyramine and cimetidine given alone were only moderately effective. When given together with BPC 157, the observed effect correlates with the strong effect of BPC 157 given alone. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and SAR studies of novel 2-(6-aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide vasopressin V1b receptor antagonists.

PubMed

Napier, Susan E; Letourneau, Jeffrey J; Ansari, Nasrin; Auld, Douglas S; Baker, James; Best, Stuart; Campbell-Wan, Leigh; Chan, Ray; Craighead, Mark; Desai, Hema; Ho, Koc-Kan; MacSweeney, Cliona; Milne, Rachel; Richard Morphy, J; Neagu, Irina; Ohlmeyer, Michael H J; Pick, Jack; Presland, Jeremy; Riviello, Chris; Zanetakos, Heather A; Zhao, Jiuqiao; Webb, Maria L

2011-06-15

Synthesis and structure-activity relationships (SAR) of a novel series of vasopressin V(1b) antagonists are described. 2-(6-Aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide have been identified with low nanomolar affinity for the V(1b) receptor and good selectivity with respect to related receptors V(1a), V(2) and OT. Optimised compound 16 shows a good pharmacokinetic profile and activity in a mechanistic model of HPA dysfunction. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparison of the effects of histamine and tolazoline on adenylate cyclase activity from guinea pig heart.

PubMed

Weinryb, I; Michel, I M

1975-01-01

Both histamine and tolazoline (2-benzyl-2-imidazoline) stimulated particulate fractions of adenylate cyclase from guinea pig myocardium. Tolazoline was one-tenth as potent, and about two-thirds as active at maximally effective levels, as was histamine. Enhancement of cyclase activity by tolazoline was additive with that by isoproterenol, and the histamine and tolazoline concentration-response curves were parallel, suggesting that tolazoline acted at the same site as histamine. At maximally effective concentrations, tolazoline did not affect ATPase or cyclic AMP phosphodiesterase activities associated with the cyclase preparations. The H1-receptor antagonist mepyramine, and the H2 antagonist, burimamide, blocked stimulation of cyclase by tolazoline at one-tenth the molarity of agonist. Both antagonists were less effective vs. histamine stimulation of heart cyclase in particulate fractions or whole homogenates, with mepyramine being generally more potent. It is suggested that the molecular basis of the stimulatory effect of tolazoline on cardiac tissue may be histaminergic stimulation of adenylate cyclase. Furthermore, the lack of potency of burimamide as a histamine antagonist and its lack of specificity compared to mepyramine, at the subcellular level, indicate that histamine-responsive adenylate cyclase from heart may not be a satisfactory molecular model for the H2 receptor pharmacology of histamine in cardiac tissue.

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

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.

2-(3-Fluoro-4-methylsulfonylaminophenyl) Propanamides as Potent Transient Receptor Potential Vanilloid 1 (TRPV1) Antagonists: Structure Activity Relationships of 2-Amino Derivatives in the N-(6-trifluoromethyl-pyridin-3-ylmethyl) C-region

PubMed Central

Kim, Myeong Seop; Ryu, HyungChul; Kang, Dong Wook; Cho, Seong-Hee; Seo, Sejin; Park, Young Soo; Kim, Mi-Yeon; Kwak, Eun Joo; Kim, Yong Soo; Bhondwe, Rahul S.; Kim, Ho Shin; Park, Seul-gi; Son, Karam; Choi, Sun; DeAndrea-Lazarus, Ian; Pearce, Larry V.; Blumberg, Peter M.; Frank, Robert; Bahrenberg, Gregor; Stockhausen, Hannelore; Kögel, Babette Y.; Schiene, Klaus; Christoph, Thomas; Lee, Jeewoo

2012-01-01

A series of N-(2-amino-6-trifluoromethyl-pyridin-3-ylmethyl) 2-(3-fluoro-4-methylsulfonylaminophenyl) propanamides were designed combining previously identified pharmacophoric elements and evaluated as hTRPV1 antagonists. The SAR analysis indicated that specific hydrophobic interactions of the 2-amino substituents in the C-region of the ligand were critical for high hTRPV1binding potency. In particular, compound 49S was an excellent TRPV1 antagonist (Ki(CAP) = 0.2 nM; IC50(pH) = 6.3 nM) and was thus ca. 100- and 20-fold more potent, respectively, than the parent compounds 2 and 3 for capsaicin antagonism. Furthermore, it demonstrated strong analgesic activity in the rat neuropathic model superior to 2 with almost no side effects. Compound 49S antagonized capsaicin induced hypothermia in mice, but showed TRPV1-related hyperthermia. The basis for the high potency of 49S compared to 2 is suggested by docking analysis with our hTRPV1 homology model in which the 4-methylpiperidinyl group in the C-region of 49S made additional hydrophobic interactions with the hydrophobic region. PMID:22957803

Contribution of the organic anion transporter OAT2 to the renal active tubular secretion of creatinine and mechanism for serum creatinine elevations caused by cobicistat

PubMed Central

Lepist, Eve-Irene; Zhang, Xuexiang; Hao, Jia; Huang, Jane; Kosaka, Alan; Birkus, Gabriel; Murray, Bernard P; Bannister, Roy; Cihlar, Tomas; Huang, Yong; Ray, Adrian S

2014-01-01

Many xenobiotics including the pharmacoenhancer cobicistat increase serum creatinine by inhibiting its renal active tubular secretion without affecting the glomerular filtration rate. This study aimed to define the transporters involved in creatinine secretion, applying that knowledge to establish the mechanism for xenobiotic-induced effects. The basolateral uptake transporters organic anion transporter OAT2 and organic cation transporters OCT2 and OCT3 were found to transport creatinine. At physiologic creatinine concentrations, the specific activity of OAT2 transport was over twofold higher than OCT2 or OCT3, establishing OAT2 as a likely relevant creatinine transporter and further challenging the traditional view that creatinine is solely transported by a cationic pathway. The apical multidrug and toxin extrusion transporters MATE1 and MATE2-K demonstrated low-affinity and high-capacity transport. All drugs known to affect creatinine inhibited OCT2 and MATE1. Similar to cimetidine and ritonavir, cobicistat had the greatest effect on MATE1 with a 50% inhibition constant of 0.99 μM for creatinine transport. Trimethoprim potently inhibited MATE2-K, whereas dolutegravir preferentially inhibited OCT2. Cimetidine was unique, inhibiting all transporters that interact with creatinine. Thus, the clinical observation of elevated serum creatinine in patients taking cobicistat is likely a result of OCT2 transport, facilitating intracellular accumulation, and MATE1 inhibition. PMID:24646860

Contribution of the organic anion transporter OAT2 to the renal active tubular secretion of creatinine and mechanism for serum creatinine elevations caused by cobicistat.

PubMed

Lepist, Eve-Irene; Zhang, Xuexiang; Hao, Jia; Huang, Jane; Kosaka, Alan; Birkus, Gabriel; Murray, Bernard P; Bannister, Roy; Cihlar, Tomas; Huang, Yong; Ray, Adrian S

2014-08-01

Many xenobiotics including the pharmacoenhancer cobicistat increase serum creatinine by inhibiting its renal active tubular secretion without affecting the glomerular filtration rate. This study aimed to define the transporters involved in creatinine secretion, applying that knowledge to establish the mechanism for xenobiotic-induced effects. The basolateral uptake transporters organic anion transporter OAT2 and organic cation transporters OCT2 and OCT3 were found to transport creatinine. At physiologic creatinine concentrations, the specific activity of OAT2 transport was over twofold higher than OCT2 or OCT3, establishing OAT2 as a likely relevant creatinine transporter and further challenging the traditional view that creatinine is solely transported by a cationic pathway. The apical multidrug and toxin extrusion transporters MATE1 and MATE2-K demonstrated low-affinity and high-capacity transport. All drugs known to affect creatinine inhibited OCT2 and MATE1. Similar to cimetidine and ritonavir, cobicistat had the greatest effect on MATE1 with a 50% inhibition constant of 0.99 μM for creatinine transport. Trimethoprim potently inhibited MATE2-K, whereas dolutegravir preferentially inhibited OCT2. Cimetidine was unique, inhibiting all transporters that interact with creatinine. Thus, the clinical observation of elevated serum creatinine in patients taking cobicistat is likely a result of OCT2 transport, facilitating intracellular accumulation, and MATE1 inhibition.

Characterization of bradykinin receptors in human lung fibroblasts using the binding of 3[H][Des-Arg10,Leu9]kallidin and [3H]NPC17731.

PubMed

Zhang, S P; Codd, E E

1998-01-01

Bradykinin (BK) receptors are involved in pain and inflammation. Two BK receptor subtypes, B1 and B2, have been defined based on their pharmacological properties. Both B1 and B2 receptors are G-protein coupled membrane receptors. B1 receptors are present in smooth muscle tissue, whereas B2 receptors are found in both smooth muscle tissue and neurons. [Des-Arg10,Leu9]kallidin (DALKD) is a selective B1 receptor antagonist, and NPC17731 is a selective B2 receptor antagonist. To develop binding assays for the two known BK receptor subtypes, [3H]DALKD and [3H]NPC17731 were used as selective ligands for B1 and B2 receptors respectively. Both ligands bound to the CCD-16 human lung fibroblast membranes reaching equilibrium at 25 degrees C within 30 min. Binding was stable for at least 60 min. The Kd of [3H]DALKD was 0.33 nM and Bmax was 52 fmol/mg membrane protein. The Kd of [3H]NPC17731 was 0.39 nM and Bmax was 700 fmol/mg membrane protein. Competition for [3H]DALKD binding with BK receptor agonists was in the order: [des-Arg10]KD (DAKD) > KD > [des-Arg9]BK (DABK) > BK, and competition for [3H]DALKD binding with BK receptor antagonists was in the order: DALKD > [des-Arg10]Hoe 140 (DAHoe 140) > [des-Arg9,Leu8]BK (DALBK) > NPC17731 > Hoe 140 > DNMFBK, suggesting that [3H]DALKD bound selectively to B1 receptors. By contrast, competition for [3H]NPC17731 binding by BK agonists was in the order: BK > KD > DAKD > DABK, and competition for [3H]NPC17731 binding by BK antagonists was in the order: NPC17731 = Hoe 140 > DNMFBK > DAHoe 140 > DALBK > DALKD, indicating that [3H]NPC17731 labeled B2 receptors selectively. These results demonstrate that [3H]DALKD and [3H]NPC17731 can be used with CCD-16 human lung fibroblast membranes to provide a pair of binding assays for the simultaneous evaluation of B1 and B2 BK receptor subtypes.

Pregnancy complicated with PFAPA (periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis) syndrome: a case report.

PubMed

Ota, Kuniaki; Kwak-Kim, Joanne; Takahashi, Toshifumi; Mizunuma, Hideki

2018-06-04

Periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) syndrome has been considered as a childhood syndrome. The underlying etiology of PFAPA syndrome is unclear however, currently considered as auto-immune inflammatory disease. Recently, a few cases of adult-onset of PFAPA syndrome have been reported. However, there is no report about the successful management of pregnancy complicated with PFAPA syndrome. The patient was a 31-year-old woman who developed recurrent episodes of high fever associated with cervical adenitis, pharyngitis and vomiting started 9 months after a delivery. She was diagnosed with PFAPA syndrome and cimetidine 800 mg/day was initiated. Since then, these symptoms got better. Cimetidine treatment was discontinued since she became pregnant (6 weeks of pregnancy). Except one febrile episode at 8 weeks gestation, she did not develop a febrile episode during pregnancy. Peripheral blood Th1/Th2 ratio was decreased from the first trimester to the second trimester of pregnancy. Then again, the ratio was steadily elevated during the third trimester. At 38 weeks, she delivered a live born infant without any complication. Two months after delivery, she developed PFAPA syndrome again and cimetidine treatment was re-initiated. However, febrile episodes were not controlled well, and Th1/Th2 ratio was further elevated compared to pregnancy status. Colchicine 0.5 mg once a day was initiated. Symptoms were diminished and Th1/Th2 ratio was gradually decreased. There was no case report of pregnancy complicated with PFAPA syndrome, though there were several reports of adult-onset PFAPA cases without pregnancy. The current case may be the first case report of a successful pregnancy complicated with PFAPA. In this case, PFAPA symptoms were ameliorated during pregnancy, but reappeared after delivery. We speculate that PFAPA syndrome, a Th1 type immune disorder, might be improved due to the Th1 to Th2 shifting, which was induced by pregnancy. It is necessary to investigate further about PFAPA syndrome with pregnancy and Th1/Th2 immune responses in the future.

The novel non-imidazole histamine H3 receptor antagonist DL77 reduces voluntary alcohol intake and ethanol-induced conditioned place preference in mice.

PubMed

Bahi, Amine; Sadek, Bassem; Nurulain, Syed M; Łażewska, Dorota; Kieć-Kononowicz, Katarzyna

2015-11-01

It has become clear that histamine H3 receptors (H3R) have been implicated in modulating ethanol intake and preference in laboratory animals. The novel non-imidazole H3R antagonist DL77 with excellent selectivity profile shows high in-vivo potency as well as in-vitro antagonist affinity with ED50 of 2.1 ± 0.2 mg/kg and pKi=8.08, respectively. In the present study, and applying an unlimited access two-bottle choice procedure, the anti-alcohol effects of the H3R antagonist, DL77 (0, 3, 10 and 30 mg/kg; i.p.), were investigated in adult mice. In this C57BL/6 line, effects of DL77 on voluntary alcohol intake and preference, as well as on total fluid intake were evaluated. Results have shown that DL77, dose-dependently, reduced both ethanol intake and preference. These effects were very selective as both saccharin and quinine, used to control for taste sensitivity, and intakes were not affected following DL77 pre-application. More importantly, systemic administration of DL77 (10 mg/kg) during acquisition inhibited ethanol-induced conditioned-place preference (EtOH-CPP) as measured using an unbiased protocol. The anti-alcohol activity observed for DL77 was abrogated when mice were pretreated with the selective H3R agonist R-(α)-methyl-histamine (RAMH) (10 mg/kg), or with the CNS penetrant H1R antagonist pyrilamine (PYR) (10mg/kg). These results suggest that DL77 has a predominant role in two in vivo effects of ethanol. Therefore, signaling via H3R is essential for ethanol-related consumption and conditioned reward and may represent a novel therapeutic pharmacological target to tackle ethanol abuse and alcoholism. Copyright © 2015 Elsevier Inc. All rights reserved.

A pharmacokinetic evaluation of five H(1) antagonists after an oral and intravenous microdose to human subjects.

PubMed

Madan, Ajay; O'Brien, Zhihong; Wen, Jianyun; O'Brien, Chris; Farber, Robert H; Beaton, Graham; Crowe, Paul; Oosterhuis, Berend; Garner, R Colin; Lappin, Graham; Bozigian, Haig P

2009-03-01

To evaluate the pharmacokinetics (PK) of five H(1) receptor antagonists in human volunteers after a single oral and intravenous (i.v.) microdose (0.1 mg). Five H(1) receptor antagonists, namely NBI-1, NBI-2, NBI-3, NBI-4 and diphenhydramine, were administered to human volunteers as a single 0.1-mg oral and i.v. dose. Blood samples were collected up to 48 h, and the parent compound in the plasma extract was quantified by high-performance liquid chromatography and accelerator mass spectroscopy. The median clearance (CL), apparent volume of distribution (V(d)) and apparent terminal elimination half-life (t(1/2)) of diphenhydramine after an i.v. microdose were 24.7 l h(-1), 302 l and 9.3 h, and the oral C(max) and AUC(0-infinity) were 0.195 ng ml(-1) and 1.52 ng h ml(-1), respectively. These data were consistent with previously published diphenhydramine data at 500 times the microdose. The rank order of oral bioavailability of the five compounds was as follows: NBI-2 > NBI-1 > NBI-3 > diphenhydramine > NBI-4, whereas the rank order for CL was NBI-4 > diphenhydramine > NBI-1 > NBI-3 > NBI-2. Human microdosing provided estimates of clinical PK of four structurally related compounds, which were deemed useful for compound selection.

Ranitidine modifies myeloid cell populations and inhibits breast tumor development and spread in mice

PubMed Central

Vila-Leahey, Ava; Oldford, Sharon A.; Marignani, Paola A.; Wang, Jun; Haidl, Ian D.; Marshall, Jean S.

2016-01-01

ABSTRACT Histamine receptor 2 (H2) antagonists are widely used clinically for the control of gastrointestinal symptoms, but also impact immune function. They have been reported to reduce tumor growth in established colon and lung cancer models. Histamine has also been reported to modify populations of myeloid-derived suppressor cells (MDSCs). We have examined the impact of the widely used H2 antagonist ranitidine, on both myeloid cell populations and tumor development and spread, in three distinct models of breast cancer that highlight different stages of cancer progression. Oral ranitidine treatment significantly decreased the monocytic MDSC population in the spleen and bone marrow both alone and in the context of an orthotopic breast tumor model. H2 antagonists ranitidine and famotidine, but not H1 or H4 antagonists, significantly inhibited lung metastasis in the 4T1 model. In the E0771 model, ranitidine decreased primary tumor growth while omeprazole treatment had no impact on tumor development. Gemcitabine treatment prevented the tumor growth inhibition associated with ranitidine treatment. In keeping with ranitidine-induced changes in myeloid cell populations in non-tumor-bearing mice, ranitidine also delayed the onset of spontaneous tumor development, and decreased the number of tumors that developed in LKB1−/−/NIC mice. These results indicate that ranitidine alters monocyte populations associated with MDSC activity, and subsequently impacts breast tumor development and outcome. Ranitidine has potential as an adjuvant therapy or preventative agent in breast cancer and provides a novel and safe approach to the long-term reduction of tumor-associated immune suppression. PMID:27622015

Glycine betaine improves oxidative stress tolerance and biocontrol efficacy of antagonistic yeast Cystofilobasidium infirmominiatum

USDA-ARS?s Scientific Manuscript database

The effect of H2O2-induced oxidative stress on the viability of the yeast antagonist, Cystofilobasidium infirmominiatum, as well as the effect of exogenous glycine betaine (GB) on yeast viability under oxidative stress, was determined. GB treatment improved the tolerance of C. infirmominiatum to ox...

Sigma1 receptor antagonists determine the behavioral pattern of the methamphetamine-induced stereotypy in mice

PubMed Central

Kitanaka, J.; Kitanaka, N.; Tatsuta, T.; Hall, F.S.; Uhl, G.R.; Tanaka, K.; Nishiyama, N.; Morita, Y.; Takemura, M.

2011-01-01

Objective The effects of sigma receptor antagonists on methamphetamine (METH)-induced stereotypy have not been examined. We examined the effects of sigma antagonists on METH-induced stereotypy in mice. Results The administration of METH (10 mg/kg) to male ddY mice induced stereotyped behavior consisting of biting (90.1%), sniffing (4.2%), head bobbing (4.1%), and circling (1.7%) during an observation period of 1 h. Pretreatment of the mice with BMY 14802 (α-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinebutanol; 1, 5, and 10 mg/kg), a non-specific sigma receptor antagonist, significantly increased METH-induced sniffing (19.2, 30.5, and 43.8% of total stereotypical behavior) but decreased biting (76.6, 66.9, and 49.3% of total stereotypical behavior) in a dose-dependent manner. This response was completely abolished by (+)-SKF 10,047 ([2S-(2α,6α,11R)]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol; 4 and 10 mg/kg), a putative sigma1 receptor agonist, and partially by PB 28 (1-cyclohexyl-4-[3-(1,2,3,4-tetrahydro-5-methoxy-1-naphthalen-1-yl)-n-propyl]piperazine; 1 and 10 mg/kg), a putative sigma2 receptor agonist. The BMY 14802 action on METH-induced stereotypy was mimicked by BD 1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine; 10 mg/kg), a putative sigma1 receptor antagonist, but not by SM-21 ((±)-tropanyl 2-(4-chlorophenoxy)butanoate; 1 mg/kg), a putative sigma2 receptor antagonist. The BD 1047 effect on METH-induced stereotypy was also abolished completely by (+)-SKF 10,047 and partially by PB 28. The overall frequency of METH-induced stereotypical behavior was unchanged with these sigma receptor ligands, despite the alteration in particular behavioral patterns. The BMY 14802 action on METH-induced stereotypy was unaffected by pretreatment with centrally acting histamine H1 receptor antagonists (pyrilamine or ketotifen, 10 mg/kg), suggesting that these effects are independent of histamine H1 receptor signaling systems. Conclusion In summary, modulation of central sigma1 receptors alters the pattern of METH-induced stereotypy, producing a shift from stereotypical biting to stereotypical sniffing, without affecting the overall frequency of stereotypical behavior. PMID:19052726

The effects of corticotrophin-releasing factor and two antagonists on breathing movements in fetal sheep.

PubMed Central

Bennet, L; Johnston, B M; Vale, W W; Gluckman, P D

1990-01-01

1. The respiratory effects of corticotrophin-releasing factor (CRF) and the CRF antagonists alpha-helical CRF 9-41 (alpha hCRF) and [DPhe 12, Nle 21-38] rCRF (12-41) (DPhe CRF) have been studied in unanaesthetized fetal lambs of 125-140 days gestation. 2. CRF when given as a 10 micrograms bolus followed by a 5 micrograms h-1 infusion into a lateral cerebral ventricle caused prolonged continuous fetal breathing movements which were stimulated in both amplitude and frequency but which did not persist during hypoxia. 3. Lower doses of CRF (20 ng bolus followed by 10 ng h-1) increased the amplitude but not the frequency of fetal breathing movements which did not become continuous. 4. At higher doses (20 micrograms bolus followed by 10-15 micrograms h-1) CRF induced cerebral convulsions which were also associated with fetal breathing movements of increased amplitude and frequency. 5. The CRF antagonists alpha hCRF and DPhe CRF both inhibited fetal breathing movements and induced a prolonged apnoea which was resistant to the stimulatory effects of 5-6% hypercapnia. 6. We conclude that CRF stimulates breathing movements in the fetal lamb. The finding that administration of the CRF antagonists alone cause apnoea suggests that CRF may have a tonic role in the regulation of fetal breathing movements. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:2348387

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ga Eun; Lee, Won-Gil; Lee, Song-Yi

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 3-5more » 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« less

Antagonistic targeting of the histamine H3 receptor decreases caloric intake in higher mammalian species.

PubMed

Malmlöf, Kjell; Hastrup, Sven; Wulff, Birgitte Schellerup; Hansen, Barbara C; Peschke, Bernd; Jeppesen, Claus Bekker; Hohlweg, Rolf; Rimvall, Karin

2007-04-15

The main purpose of this study was to examine the effects of a selective histamine H(3) receptor antagonist, NNC 38-1202, on caloric intake in pigs and in rhesus monkeys. The compound was given intragastrically (5 or 15 mg/kg), to normal pigs (n=7) and subcutaneously (1 or 0.1mg/kg) to obese rhesus monkeys (n=9). The energy intake recorded following administration of vehicle to the same animals served as control for the effect of the compound. In addition, rhesus monkey and pig histamine H(3) receptors were cloned from hypothalamic tissues and expressed in mammalian cell lines. The in vitro antagonist potencies of NNC 38-1202 at the H(3) receptors were determined using a functional GTPgammaS binding assay. Porcine and human H(3) receptors were found to have 93.3% identity at the amino acid level and the close homology between the monkey and human H(3) receptors (98.4% identity) was confirmed. The antagonist potencies of NNC 38-1202 at the porcine, monkey and human histamine H(3) receptors were high as evidenced by K(i)-values being clearly below 20 nM, whereas the K(i)-value on the rat H(3) receptor was significantly higher (56+/-6.0 nM). NNC 38-1202, given to pigs in a dose of 15 mg/kg, produced a significant (p<0.05) reduction (55%) of calorie intake compared with vehicle alone, (132.6+/-10.0 kcal/kgday versus 59.7+/-10.2 kcal/kgday). In rhesus monkeys administration of 0.1 and 1mg/kg decreased (p<0.05) average calorie intakes by 40 and 75%, respectively. In conclusion, the present study demonstrates that antagonistic targeting of the histamine H(3) receptor decreases caloric intake in higher mammalian species.

Identification of two H3-histamine receptor subtypes

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, R.E. Jr.; Zweig, A.; Shih, N.Y.

The H3-histamine receptor provides feedback inhibition of histamine synthesis and release as well as inhibition of other neurotransmitter release. We have characterized this receptor by radioligand binding studies with the H3 agonist N alpha-(3H)methylhistamine ((3H)NAMHA). The results of (3H)NAMHA saturation binding and NAMHA inhibition of (3H)NAMHA binding were consistent with an apparently single class of receptors (KD = 0.37 nM, Bmax = 73 fmol/mg of protein) and competition assays with other agonists and the antagonists impromidine and dimaprit disclosed only a single class of sites. In contrast, inhibition of (3H)NAMHA binding by the specific high affinity H3 antagonist thioperamide revealedmore » two classes of sites (KiA = 5 nM, BmaxA = 30 fmol/mg of protein; KiB = 68 nM, BmaxB = 48 fmol/mg of protein). Burimamide, another antagonist that, like thioperamide, contains a thiourea group, likewise discriminated between two classes of sites. In addition to differences between some antagonist potencies for the two receptors, there is a differential guanine nucleotide sensitivity of the two. The affinity of the H3A receptor for (3H) NAMHA was reduced less than 2-fold, whereas (3H)NAMHA binding to the H3B receptor was undetectable in the presence of guanosine 5'-O-(3-thiotriphosphate). The distinction between H3A and H3B receptor subtypes, the former a high affinity and the latter a low affinity thioperamide site, draws support from published in vitro data.« less

Equivalence of litmus paper and intragastric pH probes for intragastric pH monitoring in the intensive care unit.

PubMed

Levine, R L; Fromm, R E; Mojtahedzadeh, M; Baghaie, A A; Opekun, A R

1994-06-01

To compare the accuracy of litmus paper-determined gastric pH to a nasogastric graphite antimony pH probe. A prospective clinical trial of gastric pH determination in patients enrolled in a study of histamine-2-receptor (H2) antagonists. The medical intensive care unit (ICU) of a 450-bed county hospital. Critically ill ICU patients requiring stress ulcer prophylaxis. Using a crossover design, the patients were randomized to initially receive an H2 antagonist by continuous infusion or intravenous bolus, and subsequently were crossed over to the other limb of the study. Gastric pH was determined using pH-sensitive litmus paper at the initiation of each limb of the study and at 1, 2, 4, and 8 hrs after the initiation of H2 receptor antagonist therapy. In addition, gastric pH was continuously determined over the same time period utilizing a graphite antimony pH probe. Gastric pH measurements determined with litmus paper and intragastric pH probes demonstrated an excellent correlation (r2 = .93, p < .001). McNemar's test of correlated proportions could not demonstrate a significant difference between the two monitoring methods (chi-square = 0.5, p > .47), and the kappa statistic (0.95, p < .001) demonstrated excellent concordance. Bias measurement was 0.01 (95% confidence interval = -0.155 to 0.176). Measurement of intragastric pH, using pH-sensitive litmus paper, is both sensitive and specific when utilizing a graphite antimony nasogastric pH probe as a reference standard. Litmus paper-determined gastric pH testing is both easy to perform and inexpensive. Therefore, based on the current data, we believe this technique (i.e., litmus paper determined gastric pH testing) to be the method of choice for determination of intragastric pH in patients at risk for stress gastric ulcers in the medical ICU.

Histamine-releasing properties of Polysorbate 80 in vitro and in vivo: correlation with its hypotensive action in the dog.

PubMed

Masini, E; Planchenault, J; Pezziardi, F; Gautier, P; Gagnol, J P

1985-09-01

The solvent of commercial amiodarone (Polysorbate 80) has been reported to produce haemodynamic responses in humans and in dogs similar to those produced by histamine infusion. We therefore evaluated the correlation between hypotension induced by the solvent of amiodarone and its histamine-releasing properties in the awake dog. The solvent of amiodarone administered to a dog, over 5 min in a dose of 10 mg/kg of Polysorbate 80, produced severe hypotension after the first administration; the second injection (24 h later) caused fewer hypotensive effects. Histamine release in the peripheral tissues was demonstrated by a marked increase in plasma histamine concentrations, with the maximum value 10 min after the solvent administration. H1- and H2-receptor blockade with mepyramine (5 mg/kg) and cimetidine (10 mg/kg) significantly reduced the cardiovascular effects of the solvent. Isolated peritoneal mast cells from rats also released histamine in response to Polysorbate 80. These studies show that Polysorbate 80 releases histamine both in vitro and in isolated mast cells from rats and in vivo in the dog, and that the plasma concentrations are correlated with the haemodynamic responses.

[Detection of Physiological Activity of Pharmaceuticals in Wastewater and River Water].

PubMed

Ihara, Masaru; Zhang, Han; Hanamoto, Seiya; Tanaka, Hiroaki

2018-01-01

　Pharmaceuticals are widely found in aquatic environments worldwide. Concern about their potential risks to aquatic species has been raised because they are designed to be biologically active. To address this concern, we must know whether biological activity of pharmaceuticals can be detected in waters. Nearly half of all marketed pharmaceuticals act by binding to the G protein-coupled receptor (GPCR). In this study, we measured the physiological activity of GPCR-acting pharmaceuticals in effluent from a wastewater treatment plant (WWTP) and upstream and downstream of its outfall in Japan during 2 years. We used the in vitro transforming growth factor-α (TGFα) shedding assay, which accurately and sensitively detects GPCR activation, to investigate the antagonistic activities of water extracts against receptors for dopamine (D2) and histamine (H1). Activities detected in waters were quantified as antagonist equivalent quantities (EQs). In WWTP effluent extracts, antagonistic activity was detected at several hundred ng/L of sulpiride-EQ (D2) and several μg/L of diphenhydramine (DIP)-EQ (H1). In downstream river water extracts, antagonistic activity against H1 was around several hundred ng/L of DIP-EQ, higher than that upstream owing to the WWTP effluent. This review discusses the research needed to resolve the concern about potential risks of pharmaceuticals in waters to aquatic species.

Inhibition of growth hormone-releasing factor suppresses both sleep and growth hormone secretion in the rat.

PubMed

Obál, F; Payne, L; Kapás, L; Opp, M; Krueger, J M

1991-08-23

To study the possible involvement of hypothalamic growth hormone-releasing factor (GRF) in sleep regulation, a competitive GRF-antagonist, the peptide (N-Ac-Tyr1,D-Arg2)-GRF(1-29)-NH2, was intracerebroventricularly injected into rats (0.003, 0.3, and 14 nmol), and the EEG and brain temperature were recorded for 12 h during the light cycle of the day. Growth hormone (GH) concentrations were determined from plasma samples taken at 20-min intervals for 3 h after 14 nmol GRF-antagonist. The onset of non-rapid eye movement sleep (NREMS) was delayed in response to 0.3 and 14 nmol GRF-antagonist, the duration of NREMS was decreased for one or more hours and after 14 nmol EEG slow wave amplitudes were decreased during NREMS in postinjection hour 1. The high dose of GRF-antagonist also suppressed REMS for 4 h, inhibited GH secretion, and elicited a slight biphasic variation in brain temperature. These findings, together with previous observations indicating a sleep-promoting effect for GRF, support the hypothesis that hypothalamic GRF is involved in sleep regulation and might be responsible for the correlation between NREMS and GH secretion reported in various species.

A pharmacokinetic evaluation of five H1 antagonists after an oral and intravenous microdose to human subjects

PubMed Central

Madan, Ajay; O'Brien, Zhihong; Wen, Jianyun; O'Brien, Chris; Farber, Robert H; Beaton, Graham; Crowe, Paul; Oosterhuis, Berend; Garner, R Colin; Lappin, Graham; Bozigian, Haig P

2009-01-01

AIMS To evaluate the pharmacokinetics (PK) of five H1 receptor antagonists in human volunteers after a single oral and intravenous (i.v.) microdose (0.1 mg). METHODS Five H1 receptor antagonists, namely NBI-1, NBI-2, NBI-3, NBI-4 and diphenhydramine, were administered to human volunteers as a single 0.1-mg oral and i.v. dose. Blood samples were collected up to 48 h, and the parent compound in the plasma extract was quantified by high-performance liquid chromatography and accelerator mass spectroscopy. RESULTS The median clearance (CL), apparent volume of distribution (Vd) and apparent terminal elimination half-life (t1/2) of diphenhydramine after an i.v. microdose were 24.7 l h−1, 302 l and 9.3 h, and the oral Cmax and AUC0–∞ were 0.195 ng ml−1 and 1.52 ng h ml−1, respectively. These data were consistent with previously published diphenhydramine data at 500 times the microdose. The rank order of oral bioavailability of the five compounds was as follows: NBI-2 > NBI-1 > NBI-3 > diphenhydramine > NBI-4, whereas the rank order for CL was NBI-4 > diphenhydramine > NBI-1 > NBI-3 > NBI-2. CONCLUSIONS Human microdosing provided estimates of clinical PK of four structurally related compounds, which were deemed useful for compound selection. PMID:19523012

Gastric emptying abnormal in duodenal ulcer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holt, S.; Heading, R.C.; Taylor, T.V.

1986-07-01

To investigate the possibility that an abnormality of gastric emptying exists in duodenal ulcer and to determine if such an abnormality persists after ulcer healing, scintigraphic gastric emptying measurements were undertaken in 16 duodenal ulcer patients before, during, and after therapy with cimetidine; in 12 patients with pernicious anemia, and in 12 control subjects. No difference was detected in the rate or pattern of gastric emptying in duodenal ulcer patients before and after ulcer healing with cimetidine compared with controls, but emptying of the solid component of the test meal was more rapid during treatment with the drug. Comparison ofmore » emptying patterns obtained in duodenal ulcer subjects during and after cimetidine treatment with those obtained in pernicious anemia patients and controls revealed a similar relationship that was characterized by a tendency for reduction in the normal differentiation between the emptying of solid and liquid from the stomach. The similarity in emptying patterns in these groups of subjects suggests that gastric emptying of solids may be influenced by changes in the volume of gastric secretion. The failure to detect an abnormality of gastric emptying in duodenal ulcer subjects before and after ulcer healing calls into question the widespread belief that abnormally rapid gastric emptying is a feature with pathogenetic significance in duodenal ulcer disease.« less

Melt Extrusion of High-Dose Co-Amorphous Drug-Drug Combinations : Theme: Formulation and Manufacturing of Solid Dosage Forms Guest Editors: Tony Zhou and Tonglei Li.

PubMed

Arnfast, Lærke; Kamruzzaman, Md; Löbmann, Korbinian; Aho, Johanna; Baldursdottir, Stefania; Rades, Thomas; Rantanen, Jukka

2017-12-01

Many future drug products will be based on innovative manufacturing solutions, which will increase the need for a thorough understanding of the interplay between drug material properties and processability. In this study, hot melt extrusion of a drug-drug mixture with minimal amount of polymeric excipient was investigated. Using indomethacin-cimetidine as a model drug-drug system, processability of physical mixtures with and without 5% (w/w) of polyethylene oxide (PEO) were studied using Differential Scanning Calorimetry (DSC) and Small Amplitude Oscillatory Shear (SAOS) rheometry. Extrudates containing a co-amorphous glass solution were produced and the solid-state composition of these was studied with DSC. Rheological analysis indicated that the studied systems display viscosities higher than expected for small molecule melts and addition of PEO decreased the viscosity of the melt. Extrudates of indomethacin-cimetidine alone displayed amorphous-amorphous phase separation after 4 weeks of storage, whereas no phase separation was observed during the 16 week storage of the indomethacin-cimetidine extrudates containing 5% (w/w) PEO. Melt extrusion of co-amorphous extrudates with low amounts of polymer was found to be a feasible manufacturing technique. Addition of 5% (w/w) polymer reduced melt viscosity and prevented phase separation.

[Stomach ulcers in the horse--clinical and gastroscopic findings in 12 horses (1989-1990)].

PubMed

Dieckmann, M; Deegen, E

1991-08-01

Twelve horses with clinical symptoms of a gastric disorder were studied by gastroscopy. Symptoms of gastric disorders were periprandial colic, bruxism, ructus and reflux. Preliminary to gastroscopy the horses were fasted for 24 h. Access to water was not restricted. The gastroscopy could be conducted easily using a fiberscope 2.5 m in length and 11 mm in outer diameter. While ulcers were present in the squamous fundus of all horses only one horse showed ulceration of the glandular fundus. Solitary ulcers near the margo plicatus were found in horses with mild clinical symptoms. In contrast, diffuse gastroesophageal ulceration was accompanied by severe clinical symptoms. Four horses were affected by an acute gastroesophageal ulceration with gastric reflux and subsequent aspiration pneumonia. Two of those horses suffered from acute gastric ulceration 3-4 days following laparatomy. All horses were treated with cimetidine (5 mg/kg bwt/q.i.d.) until clinical symptoms ceased.

Synthesis, spectral characterization and catalytic activity of Co(II) complexes of drugs: crystal structure of Co(II)-trimethoprim complex.

PubMed

Madhupriya, Selvaraj; Elango, Kuppanagounder P

2014-01-24

New Co(II) complexes with drugs such as trimethoprim (TMP), cimetidine (CTD), niacinamide (NAM) and ofloxacin (OFL) as ligands were synthesized. The complexes were characterized by analytical analysis, various spectral techniques such as FT-IR, UV-Vis, magnetic measurements and molar conductivity. The magnetic susceptibility results coupled with the electronic spectra suggested a tetrahedral geometry for the complexes. The coordination mode of trimethoprim ligand and geometry of the complex were confirmed by single crystal X-ray studies. In this complex the metal ion possesses a tetrahedral geometry with two nitrogen atom from two TMP ligands and two chloride ions coordinated to it. The catalytic activity of the complexes in aryl-aryl coupling reaction was screened and the results indicated that among the four complexes [Co(OFL)Cl(H2O)] exhibited excellent catalytic activity. Copyright © 2013 Elsevier B.V. All rights reserved.

Heteroreceptor Complexes Formed by Dopamine D1, Histamine H3, and N-Methyl-D-Aspartate Glutamate Receptors as Targets to Prevent Neuronal Death in Alzheimer's Disease.

PubMed

Rodríguez-Ruiz, Mar; Moreno, Estefanía; Moreno-Delgado, David; Navarro, Gemma; Mallol, Josefa; Cortés, Antonio; Lluís, Carme; Canela, Enric I; Casadó, Vicent; McCormick, Peter J; Franco, Rafael

2017-08-01

Alzheimer's disease (AD) is a neurodegenerative disorder causing progressive memory loss and cognitive dysfunction. Anti-AD strategies targeting cell receptors consider them as isolated units. However, many cell surface receptors cooperate and physically contact each other forming complexes having different biochemical properties than individual receptors. We here report the discovery of dopamine D 1 , histamine H 3 , and N-methyl-D-aspartate (NMDA) glutamate receptor heteromers in heterologous systems and in rodent brain cortex. Heteromers were detected by co-immunoprecipitation and in situ proximity ligation assays (PLA) in the rat cortex where H 3 receptor agonists, via negative cross-talk, and H 3 receptor antagonists, via cross-antagonism, decreased D 1 receptor agonist signaling determined by ERK1/2 or Akt phosphorylation, and counteracted D 1 receptor-mediated excitotoxic cell death. Both D 1 and H 3 receptor antagonists also counteracted NMDA toxicity suggesting a complex interaction between NMDA receptors and D 1 -H 3 receptor heteromer function. Likely due to heteromerization, H 3 receptors act as allosteric regulator for D 1 and NMDA receptors. By bioluminescence resonance energy transfer (BRET), we demonstrated that D 1 or H 3 receptors form heteromers with NR1A/NR2B NMDA receptor subunits. D 1 -H 3 -NMDA receptor complexes were confirmed by BRET combined with fluorescence complementation. The endogenous expression of complexes in mouse cortex was determined by PLA and similar expression was observed in wild-type and APP/PS1 mice. Consistent with allosteric receptor-receptor interactions within the complex, H 3 receptor antagonists reduced NMDA or D 1 receptor-mediated excitotoxic cell death in cortical organotypic cultures. Moreover, H 3 receptor antagonists reverted the toxicity induced by ß 1-42 -amyloid peptide. Thus, histamine H 3 receptors in D 1 -H 3 -NMDA heteroreceptor complexes arise as promising targets to prevent neurodegeneration.

3-(Fur-2-yl)-10-(2-phenylethyl)-[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one, a novel adenosine receptor antagonist with A(2A)-mediated neuroprotective effects.

PubMed

Scatena, Alessia; Fornai, Francesco; Trincavelli, Maria Letizia; Taliani, Sabrina; Daniele, Simona; Pugliesi, Isabella; Cosconati, Sandro; Martini, Claudia; Da Settimo, Federico

2011-09-21

In this study, compound FTBI (3-(2-furyl)-10-(2-phenylethyl)[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one) was selected from a small library of triazinobenzimidazole derivatives as a potent A(2A) adenosine receptor (AR) antagonist and tested for its neuroprotective effects against two different kinds of dopaminergic neurotoxins, 1-methyl-4-phenylpyridinium (MPP+) and methamphetamine (METH), in rat PC12 and in human neuroblastoma SH-SY5Y cell lines. FTBI, in a concentration range corresponding to its affinity for A(2A) AR subtype, significantly increased the number of viable PC12 cells after their exposure to METH and, to a similar extent, to MPP+, as demonstrated in both trypan blue exclusion assay and in cytological staining. These neuroprotective effects were also observed with a classical A(2A) AR antagonist, ZM241385, and appeared to be completely counteracted by the AR agonist, NECA, supporting A(2A) ARs are directly involved in FTBI-mediated effects. Similarly, in human SH-SY5Y cells, FTBI was able to prevent cell toxicity induced by MPP+ and METH, showing that this A(2A) AR antagonist has a neuroprotective effect independently by the specific cell model. Altogether these results demonstrate that the A(2A) AR blockade mediates cell protection against neurotoxicity induced by dopaminergic neurotoxins in dopamine containing cells, supporting the potential use of A(2A) AR antagonists in dopaminergic degenerative diseases including Parkinson's disease.

Antihistamines and birth defects: a systematic review of the literature.

PubMed

Gilboa, Suzanne M; Ailes, Elizabeth C; Rai, Ramona P; Anderson, Jaynia A; Honein, Margaret A

2014-12-01

Approximately 10 - 15% of women reportedly take an antihistamine during pregnancy for the relief of nausea and vomiting, allergy and asthma symptoms, or indigestion. Antihistamines include histamine H1-receptor and H2-receptor antagonists. This is a systematic evaluation of the peer-reviewed epidemiologic literature published through February 2014 on the association between prenatal exposure to antihistamines and birth defects. Papers addressing histamine H1- or H2-receptor antagonists are included. Papers addressing pyridoxine plus doxylamine (Bendectin in the United States, Debendox in the United Kingdom, Diclectin in Canada, Lenotan and Merbental in other countries) prior to the year 2001 were excluded post hoc because of several previously published meta-analyses and commentaries on this medication. The literature on the safety of antihistamine use during pregnancy with respect to birth defects is generally reassuring though the positive findings from a few large studies warrant corroboration in other populations. The findings in the literature are considered in light of three critical methodological issues: i) selection of appropriate study population; ii) ascertainment of antihistamine exposures; and iii) ascertainment of birth defect outcomes. Selected antihistamines have been very well studied (e.g., loratadine); others, especially H2-receptor antagonists, require additional study before an assessment of safety with respect to birth defect risk could be made.

Emerging drugs for neuropathic pain.

PubMed

Gilron, Ian; Dickenson, Anthony H

2014-09-01

Neuropathic pain is a costly and disabling condition, which affects up to 8% of the population. Available therapies often provide incomplete pain relief and treatment-related side effects are common. Preclinical neuropathic pain models have facilitated identification of several promising targets, which have progressed to human clinical phases of evaluation. A systematic database search yielded 25 new molecular entities with specified pharmacological mechanisms that have reached Phase II or III clinical trials. These include calcium channel antagonists, vanilloid receptor antagonists, potassium channel agonists, NMDA antagonists, novel opioid receptor agonists, histamine H3 receptor antagonists, a novel sodium channel antagonist, serotonin modulators, a novel acetylcholine receptor agonist, α-2b adrenoreceptor agonist, cannabinoid CB2 receptor agonist, nitric oxide synthase inhibitor, orexin receptor antagonist, angiotensin II 2 antagonist, imidazoline I2 receptor agonist, apoptosis inhibitor and fatty acid amide hydrolase inhibitor. Although the diversity of pharmacological mechanisms of interest emphasise the complexity of neuropathic pain transmission, the considerable number of agents under development reflect a continued enthusiasm in drug development for neuropathic pain. Ongoing enhancements in methodology of both preclinical and clinical research and closer translation in both directions are expected to more efficiently identify new agents, which will improve the management of neuropathic pain.

Synthesis and biological evaluation of cyclopropyl analogues of 2-amino-5-phosphonopentanoic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dappen, M.S.; Pellicciari, R.; Natalini, B.

1991-01-01

A series of cyclopropyl analogues related to 2-amino-5-phosphonopentanoic acid (AP5) were synthesized and their biological activity was assessed as competitive antagonists for the N-methyl-D-aspartate (NMDA) receptor. In vitro receptor binding using (3H)-L-glutamate as the radioligand provided affinity data, while modulation of (3H)MK-801 binding was used as a functional assay. The analogues were also evaluated in (3H)kainate binding to assess selectivity over non-NMDA glutamate receptors. Of the compounds tested, 4,5-methano-AP5 analogue 26 was the most potent selective NMDA antagonist; however, potency was lower than that for (((+/-)-2-carboxypiperidin-4-yl)methyl)phosphonic acid (CGS 19755, 5).

Hypersensitivity reaction to ranitidine: description of a case and review of the literature.

PubMed

Foti, Caterina; Cassano, Nicoletta; Panebianco, Rosanna; Calogiuri, Gian Franco; Vena, Gino A

2009-01-01

Ranitidine is an H2-receptor antagonist which is usually well tolerated. Hypersensitivity reactions to ranitidine, as well as other H2 antihistamines, have been rarely described. We report the case of a 47-year-old woman who developed an anaphylactic reaction to ranitidine used as intravenous premedication before anesthesia induction. The patient's history revealed that previous use of oral ranitidine for a peptic ulcer disease did not cause any adverse reaction. Intradermal test with ranitidine at a dilution of 1:100 gave an intense positive reaction. The protective role of H2-receptor antagonists as premedication is still unclear and should be carefully reconsidered on the basis of the available controversial evidence and the possible risk of hypersensitivity reactions.

Investigation of the mechanisms underlying the hypophagic effects of the 5-HT and noradrenaline reuptake inhibitor, sibutramine, in the rat

PubMed Central

Jackson, Helen C; Bearham, M Clair; Hutchins, Lisa J; Mazurkiewicz, Sarah E; Needham, Andrew M; Heal, David J

1997-01-01

Sibutramine is a novel 5-hydroxytryptamine (5-HT) and noradrenaline reuptake inhibitor (serotonin- noradrenaline reuptake inhibitor, SNRI) which is currently being developed as a treatment for obesity. Sibutramine has been shown to decrease food intake in the rat. In this study we have used a variety of monoamine receptor antagonists to examine the pharmacological mechanisms underlying sibutramine-induced hypophagia. Individually-housed male Sprague-Dawley rats were maintained on reversed phase lighting with free access to food and water. Drugs were administered at 09 h 00 min and food intake was monitored over the following 8 h dark period. Sibutramine (10 mg kg−1, p.o.) produced a significant decrease in food intake during the 8 h following drug administration. This hypophagic response was fully antagonized by the α1-adrenoceptor antagonist, prazosin (0.3 and 1 mg kg−1, i.p.), and partially antagonized by the β1-adrenoceptor antagonist, metoprolol (3 and 10 mg kg−1, i.p.) and the 5-HT receptor antagonists, metergoline (non-selective; 0.3 mg kg−1, i.p.); ritanserin (5-HT2A/2C; 0.1 and 0.5 mg kg−1, i.p.) and SB200646 (5-HT2B/2C; 20 and 40 mg kg−1, p.o.). By contrast, the α2-adrenoceptor antagonist, RX821002 (0.3 and 1 mg kg−1, i.p.) and the β2-adrenoceptor antagonist, ICI 118,551 (3 and 10 mg kg−1, i.p.) did not reduce the decrease in food intake induced by sibutramine. These results demonstrate that β1-adrenoceptors, 5-HT2A/2C-receptors and particularly α1-adrenoceptors, are involved in the effects of sibutramine on food intake and are consistent with the hypothesis that sibutramine-induced hypophagia is related to its ability to inhibit the reuptake of both noradrenaline and 5-HT, with the subsequent activation of a variety of noradrenaline and 5-HT receptor systems. PMID:9283694

Blockers for excitatory effects of achatin-I, a tetrapeptide having a D-phenylalanine residue, on a snail neurone.

PubMed

Santos, D E; Liu, G J; Takeuchi, H

1995-01-16

Some histamine H1 receptor antagonists suppressed the inward current (Iin) of an Achatina identifiable neurone type, PON (periodically oscillating neurone), caused by an Achatina endogenous tetrapeptide having a D-phenylalanine residue, achatin-I (Gly-D-Phe-Ala-Asp), under voltage clamp. Achatin-I was applied locally to the neurone by brief pneumatic pressure ejection and antagonists were administered by perfusion. The dose-response curves of the effective histamine H1 antagonists indicated their potency order to suppress the Iin as follows: chlorcyclizine, promethazine, triprolidine and homochlorcyclizine > trimeprazine and clemastine > diphenylpyraline. The potent drugs were mostly piperazine and phenothiazine types. The effects of chlorcyclizine, promethazine and triprolidine on the dose (the duration of the pressure ejection)-response curve of achatin-I indicated that these drugs affected the Iin caused by achatin-I in a non-competitive manner. The antagonists for the receptors of the small-molecule neurotransmitters other than histamine H1, such as histamine H2, acetylcholine, gamma-aminobutyric acid (GABA), L-glutamic acid, dopamine, alpha- and beta-adrenalin and 5-hydroxytryptamine, had no effect on the Iin caused by achatin-I.

Dopamine Transporter-Dependent and -Independent Striatal Binding of the Benztropine Analog JHW 007, a Cocaine Antagonist with Low Abuse Liability

PubMed Central

Kopajtic, Theresa A.; Liu, Yi; Surratt, Christopher K.; Donovan, David M.; Newman, Amy H.; Katz, Jonathan L.

2010-01-01

The benztropine analog N-(n-butyl)-3α-[bis(4′-fluorophenyl)methoxy]-tropane (JHW 007) displays high affinity for the dopamine transporter (DAT), but unlike typical DAT ligands, has relatively low abuse liability and blocks the effects of cocaine, including its self-administration. To determine sites responsible for the cocaine antagonist effects of JHW 007, its in vitro binding was compared with that of methyl (1R,2S,3S,5S)-3-(4-fluorophenyl)-8-methyl-8-azabicyclo[3.2.1]octane-2-carboxylate (WIN 35428) in rats, mice, and human DAT (hDAT)-transfected cells. A one-site model, with Kd values of 4.21 (rat) and 8.99 nM (mouse) best fit the [3H]WIN 35428 data. [3H]JHW 007 binding best fit a two-site model (rat, 7.40/4400 nM; mouse, 8.18/2750 nM), although a one-site fit was observed with hDAT membranes (43.7 nM). Drugs selective for the norepinephrine and serotonin transporters had relatively low affinity in competition with [3H]JHW 007 binding, as did drugs selective for other sites identified previously as potential JHW 007 binding sites. The association of [3H]WIN 35428 best fit a one-phase model, whereas the association of [3H]JHW 007 best fit a two-phase model in all tissues. Because cocaine antagonist effects of JHW 007 have been observed previously soon after injection, its rapid association observed here may contribute to those effects. Multiple [3H]JHW 007 binding sites were obtained in tissue from mice lacking the DAT, suggesting these as yet unidentified sites as potential contributors to the cocaine antagonist effects of JHW 007. Unlike WIN 35428, the binding of JHW 007 was Na+-independent. This feature of JHW 007 has been linked to the conformational status of the DAT, which in turn may contribute to the antagonism of cocaine. PMID:20855444

Effect of glutamate receptor antagonists and antirheumatic drugs on proliferation of synoviocytes in vitro.

PubMed

Parada-Turska, Jolanta; Rzeski, Wojciech; Majdan, Maria; Kandefer-Szerszeń, Martyna; Turski, Waldemar A

2006-03-27

One of the most striking features of inflammatory arthritis is the hyperplasia of synovial fibroblasts. It is not known whether the massive synovial hyperplasia characteristic of rheumatoid arthritis is due to the proliferation of synovial fibroblasts or to defective apoptosis. It has been found that glutamate receptor antagonists inhibit proliferation of different human tumour cells and the anticancer potential of glutamate receptor antagonists was suggested. Here, we investigated the effect of glutamate receptor antagonists and selected antirheumatic drugs on proliferation of synoviocytes in vitro. Experiments were conducted on rabbit synoviocytes cell line HIG-82 obtained from American Type Culture Collection (Menassas, VA, USA). Cell proliferation was assessed by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC50 value (the concentration of drug necessary to induce 50% inhibition) together with confidence limits was calculated. Glutamate receptor antagonists, 1-(4-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one (CFM-2), riluzole, memantine, 1-4-aminophenyl-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466), dizocilpine, ketamine and 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(f)quinoxaline (NBQX), inhibited proliferation of synoviocytes with the following IC50 values (in mM): 0.014, 0.017, 0.065, 0.102, 0.15, 0.435 and 1.16, respectively. Antirheumatic drugs, celecoxib, diclofenac, nimesulide, sulfasalazine, naproxen and methotrexate, inhibited proliferation of synoviocytes with the following IC50 values (in mM): 0.0043, 0.034, 0.044, 0.096, 0.385 and 1.123, respectively. Thus, the antiproliferative potential of glutamate receptor antagonists is comparable to that of antirheumatic drugs.

Differences in muscarinic acetylcholine receptor subtypes in the central nervous system of long sleep and short sleep mice. [Ethanol effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, M.; Ming, X.; McArdle, J.J.

Differences in voluntary ethanol consumption have been noted in various inbred strains of mice and pharmacogenetic approaches have been used to study the mechanisms of action of many drugs such as ethanol. Long-sleep (LS) and short-sleep (SS) mice, selectively bred for differences in ethanol induced narcosis, provide a method by which a relationship between the differential responsiveness of these geno-types and muscarinic acetylcholine receptors (mAChR) may be evaluated. Sleep times after injection of 3ml ethanol/kg (i.p.) verified the higher sensitivity of LS vs. SS. Mean body weights of LS (26.5g) vs. SS (22g) were also significantly (p<.01) greater. Binding assaysmore » for ({sup 3}H)(-) quinuclidinylbenzilate (({sup 3}H)(-)QNB), a specific but nonsubtype selective mAChR antagonist, ({sup 3}H)pirenzepine (({sup 3}H)PZ), a specific M1 mAChR antagonist and ({sup 3}H)11-2-((2-((diethylamino) methyl)-1-piperidinyl) acetyl)-5,11-dihydro-6H-pyrido (2,3-b) (1,4) benzodiazepine-6-one, (({sup 3}H)AF-DX 116), an M2 selective antagonist were performed to determine mAChR affinity (K{sub d}) and density (B{sub max}) in CNS regions such as the cerebral cortex, hippocampus, corpus striatum and other areas. Significantly lower (30-40%) ({sup 3}H)(-)QNB binding suggests that SS have fewer mAChR's than LS in many areas. These differences may relate to their differential ethanol sensitivity.« less

Antihistamines and Birth Defects: A Systematic Review of the Literature

PubMed Central

Gilboa, Suzanne M.; Ailes, Elizabeth C.; Rai, Ramona P.; Anderson, Jaynia A.; Honein, Margaret A.

2015-01-01

Introduction Approximately 10-15% of women reportedly take an antihistamine during pregnancy for the relief of nausea and vomiting, allergy and asthma symptoms, or indigestion. Antihistamines include histamine H1-receptor and H2-receptor antagonists. Areas covered This is a systematic evaluation of the peer-reviewed epidemiologic literature published through February 2014 on the association between prenatal exposure to antihistamines and birth defects. Papers addressing histamine H1- or H2-receptor antagonists are included. Papers addressing pyridoxine plus doxylamine (Bendectin in the United States, Debendox in the United Kingdom, Diclectin in Canada, Lenotan and Merbental in other countries) prior to the year 2001 were excluded post-hoc because of several previously published meta-analyses and commentaries on this medication. Expert opinion The literature on the safety of antihistamine use during pregnancy with respect to birth defects is generally reassuring though the positive findings from a few large studies warrant corroboration in other populations. The findings in the literature are considered in light of three critical methodological issues: (1) selection of appropriate study population; (2) ascertainment of antihistamine exposures; and (3) ascertainment of birth defects outcomes. Selected antihistamines have been very well-studied (e.g. loratadine); others, especially H2- receptor antagonists, require additional study before an assessment of safety with respect to birth defects risk could be made. PMID:25307228

Hit-to-lead optimization of pyrrolo[1,2-a]quinoxalines as novel cannabinoid type 1 receptor antagonists.

PubMed

Szabó, György; Kiss, Róbert; Páyer-Lengyel, Dóra; Vukics, Krisztina; Szikra, Judit; Baki, Andrea; Molnár, László; Fischer, János; Keseru, György M

2009-07-01

Hit-to-lead optimization of a novel series of N-alkyl-N-[2-oxo-2-(4-aryl-4H-pyrrolo[1,2-a]quinoxaline-5-yl)-ethyl]-carboxylic acid amides, derived from a high throughput screening (HTS) hit, are described. Subsequent optimization led to identification of in vitro potent cannabinoid 1 receptor (CB1R) antagonists representing a new class of compounds in this area.

[(3)H]8-Ethyl-4-methyl-2-phenyl-(8R)-4,5,7,8-tetrahydro-1H-imidazo[2,1-i]-purin-5-one ([(3)H]PSB-11), a novel high-affinity antagonist radioligand for human A(3) adenosine receptors.

PubMed

Müller, Christa E; Diekmann, Martina; Thorand, Mark; Ozola, Vita

2002-02-11

This study describes the preparation and binding properties of [(3)H]PSB-11, a novel, potent, and selective antagonist radioligand for human A(3) adenosine receptors (ARs). [(3)H]PSB-11 binding to membranes of Chinese hamster ovary (CHO) cells expressing the human A(3) AR was saturable and reversible. Saturation experiments showed that [(3)H]PSB-11 labeled a single class of binding sites with high affinity (K(D)=4.9 nM) and limited capacity (B(max)=3500 fmol/mg of protein). PSB-11 is highly selective versus the other adenosine receptor subtypes. The new radioligand shows an extraordinarily low degree of non-specific binding rendering it a very useful tool for studying the (patho)physiological roles of A(3 )ARs.

Neurogenic mediators contribute to local edema induced by Micrurus lemniscatus venom

PubMed Central

2017-01-01

Background/Aims Micrurus is one of the four snake genera of medical importance in Brazil. Coral snakes have a broad geographic distribution from the southern United States to Argentina. Micrurine envenomation is characterized by neurotoxic symptoms leading to dyspnea and death. Moreover, various local manifestations, including edema formation, have been described in patients bitten by different species of Micrurus. Thus, we investigated the ability of Micrurus lemniscatus venom (MLV) to induce local edema. We also explored mechanisms underlying this effect, focusing on participation of neuropeptides and mast cells. Methodology/Principal findings Intraplantar injection of MLV (1–10 μg/paw) in rats caused dose- and time-dependent edema with a peak between 15 min and 1 h after injection. MLV also induced degranulation of peritoneal mast cells (MCs). MC depletion by compound 48/80 markedly reduced MLV-induced edema. Pre-treatment (30 min) of rats with either promethazine a histamine H1 receptor antagonist or methysergide, a nonselective 5-HT receptor antagonist, reduced MLV-induced edema. However, neither thioperamide, a histamine H3/H4 receptor antagonist, nor co-injection of MLV with HOE-140, a BK2 receptor antagonist, altered the response. Depletion of neuropeptides by capsaicin or treatment of animals with NK1- and NK2-receptor antagonists (SR 140333 and SR 48968, respectively) markedly reduced MLV-induced edema. Conclusions/Significance In conclusion, MLV induces paw edema in rats by mechanisms involving activation of mast cells and substance P-releasing sensory C-fibers. Tachykinins NKA and NKB, histamine, and serotonin are major mediators of the MLV-induced edematogenic response. Targeting mast cell- and sensory C-fiber-derived mediators should be considered as potential therapeutic approaches to interrupt development of local edema induced by Micrurus venoms. PMID:29161255

Molecular mechanism of R-bicalutamide switching from androgen receptor antagonist to agonist induced by amino acid mutations using molecular dynamics simulations and free energy calculation

NASA Astrophysics Data System (ADS)

Liu, Hongli; Han, Rui; Li, Jiazhong; Liu, Huanxiang; Zheng, Lifang

2016-12-01

R-bicalutamide, a first generation antiandrogen, was used to treat prostate cancer for decades. Although it is very effective at the beginning, resistance appears after 2-3 years of treatment. Mutation of androgen receptor (AR) is considered a main reason for drug resistance. It is reported that AR W741C, W741L, W741C_T877A, T877A, F876L, F876L_T877A and L701H mutations can convert R-bicalutamide from AR antagonist to agonist, but the switching mechanisms are not clear. In this study, molecular dynamics simulations and molecular mechanics generalized Born surface area (MM-GBSA) calculations were performed to analyze the interaction mechanisms between R-bicalutamide and wild type/mutant ARs. The results indicate that helix H12, which lies on the top of AR LBD like a cover, plays a vital role in R-bicalutamide binding. When interacting with AR, the B-ring of R-bicalutamide pushes H12 aside, distorting the coactivator binding site (AF2) resulting in the inactivation of transcription. Several residue mutations appear to enlarge the distance between the B-ring of R-bicalutamide and H12, reducing steric clash, which is conducive to a closed H12 conformation, leading to the formation of the coactivator binding site AF2 and increased transcription. Hydrogen bond and per-residue free energy decomposition analyses are also investigated to explore the interacting mechanisms, and M895 is found to be a key residue in the antagonist mechanism. The obtained molecular mechanisms will aid rational screening and design of novel AR antagonists, even to mutant AR.

Molecular mechanism of R-bicalutamide switching from androgen receptor antagonist to agonist induced by amino acid mutations using molecular dynamics simulations and free energy calculation.

PubMed

Liu, Hongli; Han, Rui; Li, Jiazhong; Liu, Huanxiang; Zheng, Lifang

2016-12-01

R-bicalutamide, a first generation antiandrogen, was used to treat prostate cancer for decades. Although it is very effective at the beginning, resistance appears after 2-3 years of treatment. Mutation of androgen receptor (AR) is considered a main reason for drug resistance. It is reported that AR W741C, W741L, W741C_T877A, T877A, F876L, F876L_T877A and L701H mutations can convert R-bicalutamide from AR antagonist to agonist, but the switching mechanisms are not clear. In this study, molecular dynamics simulations and molecular mechanics generalized Born surface area (MM-GBSA) calculations were performed to analyze the interaction mechanisms between R-bicalutamide and wild type/mutant ARs. The results indicate that helix H12, which lies on the top of AR LBD like a cover, plays a vital role in R-bicalutamide binding. When interacting with AR, the B-ring of R-bicalutamide pushes H12 aside, distorting the coactivator binding site (AF2) resulting in the inactivation of transcription. Several residue mutations appear to enlarge the distance between the B-ring of R-bicalutamide and H12, reducing steric clash, which is conducive to a closed H12 conformation, leading to the formation of the coactivator binding site AF2 and increased transcription. Hydrogen bond and per-residue free energy decomposition analyses are also investigated to explore the interacting mechanisms, and M895 is found to be a key residue in the antagonist mechanism. The obtained molecular mechanisms will aid rational screening and design of novel AR antagonists, even to mutant AR.

Bexarotene

MedlinePlus

... gets on your skin, wash the area with soap and water immediately and call your doctor.Your ... the following: amiodarone (Cordarone); certain antifungals such as ketoconazole (Nizoral) and itraconazole (Sporanox); cimetidine (Tagamet); clarithromycin (Biaxin); ...

Cimetidine

MedlinePlus

... GERD), a condition in which backward flow of acid from the stomach causes heartburn and injury of ... and conditions where the stomach produces too much acid, such as Zollinger-Ellison syndrome. Over-the-counter ...

Histamine-induced vasodilatation in the human forearm vasculature

PubMed Central

Sandilands, Euan A; Crowe, Jane; Cuthbert, Hayley; Jenkins, Paul J; Johnston, Neil R; Eddleston, Michael; Bateman, D Nicholas; Webb, David J

2013-01-01

Aim To investigate the mechanism of action of intra-arterial histamine in the human forearm vasculature. Methods Three studies were conducted to assess changes in forearm blood flow (FBF) using venous occlusion plethysmography in response to intra-brachial histamine. First, the dose–response was investigated by assessing FBF throughout a dose-escalating histamine infusion. Next, histamine was infused at a constant dose to assess acute tolerance. Finally, a four way, double-blind, randomized, placebo-controlled crossover study was conducted to assess FBF response to histamine in the presence of H1- and H2-receptor antagonists. Flare and itch were assessed in all studies. Results Histamine caused a dose-dependent increase in FBF, greatest with the highest dose (30 nmol min−1) infused [mean (SEM) infused arm vs. control: 26.8 (5.3) vs. 2.6 ml min−1 100 ml−1; P < 0.0001]. Dose-dependent flare and itch were demonstrated. Acute tolerance was not observed, with an increased FBF persisting throughout the infusion period. H2-receptor antagonism significantly reduced FBF (mean (95% CI) difference from placebo at 30 nmol min−1 histamine: −11.9 ml min−1 100 ml−1 (−4.0, −19.8), P < 0.0001) and flare (mean (95% CI) difference from placebo: −403.7 cm2 (−231.4, 576.0), P < 0.0001). No reduction in FBF or flare was observed in response to the H1-receptor antagonist. Itch was unaffected by the treatments. Histamine did not stimulate vascular release of tissue plasminogen activator or von Willebrand factor. Conclusion Histamine causes dose-dependent vasodilatation, flare and itch in the human forearm. H2-receptors are important in this process. Our results support further exploration of combined H1- and H2-receptor antagonist therapy in acute allergic syndromes. PMID:23488545

Antivirulence Isoquinolone Mannosides: Optimization of the Biaryl Aglycone for FimH Lectin Binding Affinity and Efficacy in the Treatment of Chronic UTI.

PubMed

Jarvis, Cassie; Han, Zhenfu; Kalas, Vasilios; Klein, Roger; Pinkner, Jerome S; Ford, Bradley; Binkley, Jana; Cusumano, Corinne K; Cusumano, Zachary; Mydock-McGrane, Laurel; Hultgren, Scott J; Janetka, James W

2016-02-17

Uropathogenic E. coli (UPEC) employ the mannose-binding adhesin FimH to colonize the bladder epithelium during urinary tract infection (UTI). Previously reported FimH antagonists exhibit good potency and efficacy, but low bioavailability and a short half-life in vivo. In a rational design strategy, we obtained an X-ray structure of lead mannosides and then designed mannosides with improved drug-like properties. We show that cyclizing the carboxamide onto the biphenyl B-ring aglycone of biphenyl mannosides into a fused heterocyclic ring, generates new biaryl mannosides such as isoquinolone 22 (2-methyl-4-(1-oxo-1,2-dihydroisoquinolin-7-yl)phenyl α-d-mannopyranoside) with enhanced potency and in vivo efficacy resulting from increased oral bioavailability. N-Substitution of the isoquinolone aglycone with various functionalities produced a new potent subseries of FimH antagonists. All analogues of the subseries have higher FimH binding affinity than unsubstituted lead 22, as determined by thermal shift differential scanning fluorimetry assay. Mannosides with pyridyl substitution on the isoquinolone group inhibit bacteria-mediated hemagglutination and prevent biofilm formation by UPEC with single-digit nanomolar potency, which is unprecedented for any FimH antagonists or any other antivirulence compounds reported to date. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interaction of ligands with the opiate receptors of brain membranes: Regulation by ions and nucleotides

PubMed Central

Blume, Arthur J.

1978-01-01

This study shows that nucleotides, as well as ions, regulate the opiate receptors of brain. GMP-P(NH)P and Na+ reduce the amount of steady-state specific [3H]dihydromorphine binding and increase the rate of dissociation of the ligand from the opiate receptor. In contrast, Mn2+ decreases the rate of ligand dissociation and antagonizes the ability of Na+ to increase dissociation. The effects of GMP-P(NH)P on steady-state binding and dissociation are not reversed by washing. Only GTP, GDP, ITP, and IMP-P(NH)P, in addition to GMP-P(NH)P, increase the rate of dihydromorphine dissociation. The site of nucleotide action appears to have high affinity: <1 μM GMP-P(NH)P produces half-maximal increases in ligand dissociation. GMP-P(NH)P- and Na+-directed increases in dissociation have also been found for the opiate agonists [3H]etorphine, [3H]Leu-enkephalin, and [3H]Met-enkephalin and the opiate antagonist [3H]naltrexone. Mn2+-directed decreases in dissociation have been found for the agonist [3H]-etorphine and the antagonist [3H]naltrexone. Although the plasma membrane receptors for a number of other neuro-transmitters and hormones are also regulated by guanine nucleotides, the opiate receptors appear unique because only they show nucleotide regulation of both agonist and antagonist binding. PMID:205867

Vismodegib

MedlinePlus

... cimetidine (Tagamet), famotidine (Pepcid), and ranitidine (Zantac); and proton-pump inhibitors such as dexlansoprazole (Dexilant), lansoprazole (Prevacid, in Prevpac), omeprazole (Prilosec, Zegerid), pantoprazole (Protonix), and rabeprazole (AcipHex). Your doctor may need to change the ...

AHR-16303B, a novel antagonist of 5-HT2 receptors and voltage-sensitive calcium channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, R.J.; Appell, K.C.; Kilpatrick, B.F.

1991-01-01

In vivo and in vitro methods were used to characterize AHR-16303B, a novel compound with antagonistic action at 5-HT2 receptors and voltage-sensitive calcium channels. The 5-HT2 receptor-antagonistic properties of AHR-16303B were demonstrated by inhibition of (a) (3H)ketanserin binding to rat cerebral cortical membranes (IC50 = 165 nM); (b) 5-hydroxytryptamine (5-HT)-induced foot edema in rats (minimum effective dose, (MED) = 0.32 mg/kg orally, p.o.); (c) 5-HT-induced vasopressor responses in spontaneously hypertensive rats (SHR) (ID50 = 0.18 mg/kg intravenously (i.v.), 1.8 mg/kg p.o.), (d) 5-HT-induced antidiuresis in rats (MED = 1 mg/kg p.o.), and (e) platelet aggregation induced by 5-HT + ADPmore » (IC50 = 1.5 mM). The calcium antagonist properties of AHR-16303B were demonstrated by inhibition of (a) (3H)nimodipine binding to voltage-sensitive calcium channels on rabbit skeletal muscle membranes (IC50 = 15 nM), (b) KCl-stimulated calcium flux into cultured PC12 cells (IC50 = 81 nM), and (c) CaCl2-induced contractions of rabbit thoracic aortic strips (pA2 = 8.84). AHR-16303B had little or no effect on binding of radioligands to dopamine2 (DA2) alpha 1, alpha 2, H1, 5-HT1 alpha, beta 2, muscarinic M1, or sigma opioid receptors; had no effect on 5-HT3 receptor-mediated vagal bradycardia; and had only minor negative inotropic, chronotropic, and dromotropic effects on isolated guinea pig atria. In conscious SHR, 30 mg/kg p.o. AHR-16303B completely prevented the vasopressor responses to i.v. 5-HT, and decreased blood pressure (BP) by 24% 3 h after dosing.« less

Antitumor effects of cannabidiol, a nonpsychoactive cannabinoid, on human glioma cell lines.

PubMed

Massi, Paola; Vaccani, Angelo; Ceruti, Stefania; Colombo, Arianna; Abbracchio, Maria P; Parolaro, Daniela

2004-03-01

Recently, cannabinoids (CBs) have been shown to possess antitumor properties. Because the psychoactivity of cannabinoid compounds limits their medicinal usage, we undertook the present study to evaluate the in vitro antiproliferative ability of cannabidiol (CBD), a nonpsychoactive cannabinoid compound, on U87 and U373 human glioma cell lines. The addition of CBD to the culture medium led to a dramatic drop of mitochondrial oxidative metabolism [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide test] and viability in glioma cells, in a concentration-dependent manner that was already evident 24 h after CBD exposure, with an apparent IC(50) of 25 microM. The antiproliferative effect of CBD was partially prevented by the CB2 receptor antagonist N-[(1S)-endo-1,3,3-trimethylbicyclo[2,2,1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528; SR2) and alpha-tocopherol. By contrast, the CB1 cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboximide hydrochloride (SR141716; SR1), capsazepine (vanilloid receptor antagonist), the inhibitors of ceramide generation, or pertussis toxin did not counteract CBD effects. We also show, for the first time, that the antiproliferative effect of CBD was correlated to induction of apoptosis, as determined by cytofluorimetric analysis and single-strand DNA staining, which was not reverted by cannabinoid antagonists. Finally, CBD, administered s.c. to nude mice at the dose of 0.5 mg/mouse, significantly inhibited the growth of subcutaneously implanted U87 human glioma cells. In conclusion, the nonpsychoactive CBD was able to produce a significant antitumor activity both in vitro and in vivo, thus suggesting a possible application of CBD as an antineoplastic agent.

Design of novel neurokinin 1 receptor antagonists based on conformationally constrained aromatic amino acids and discovery of a potent chimeric opioid agonist-neurokinin 1 receptor antagonist.

PubMed

Ballet, Steven; Feytens, Debby; Buysse, Koen; Chung, Nga N; Lemieux, Carole; Tumati, Suneeta; Keresztes, Attila; Van Duppen, Joost; Lai, Josephine; Varga, Eva; Porreca, Frank; Schiller, Peter W; Vanden Broeck, Jozef; Tourwé, Dirk

2011-04-14

A screening of conformationally constrained aromatic amino acids as base cores for the preparation of new NK1 receptor antagonists resulted in the discovery of three new NK1 receptor antagonists, 19 [Ac-Aba-Gly-NH-3',5'-(CF(3))(2)-Bn], 20 [Ac-Aba-Gly-NMe-3',5'-(CF(3))(2)-Bn], and 23 [Ac-Tic-NMe-3',5'-(CF(3))(2)-Bn], which were able to counteract the agonist effect of substance P, the endogenous ligand of NK1R. The most active NK1 antagonist of the series, 20 [Ac-Aba-Gly-NMe-3',5'-(CF(3))(2)-Bn], was then used in the design of a novel, potent chimeric opioid agonist-NK1 receptor antagonist, 35 [Dmt-D-Arg-Aba-Gly-NMe-3',5'-(CF(3))(2)-Bn], which combines the N terminus of the established Dmt(1)-DALDA agonist opioid pharmacophore (H-Dmt-D-Arg-Phe-Lys-NH(2)) and 20, the NK1R ligand. The opioid component of the chimeric compound 35, that is, Dmt-D-Arg-Aba-Gly-NH(2) (36), also proved to be an extremely potent and balanced μ and δ opioid receptor agonist with subnanomolar binding and in vitro functional activity.

Novel long‐acting antagonists of muscarinic ACh receptors

PubMed Central

Randáková, Alena; Rudajev, Vladimír; Doležal, Vladimír; Boulos, John

2018-01-01

Background and Purpose The aim of this study was to develop potent and long‐acting antagonists of muscarinic ACh receptors. The 4‐hexyloxy and 4‐butyloxy derivatives of 1‐[2‐(4‐oxidobenzoyloxy)ethyl]‐1,2,3,6‐tetrahydropyridin‐1‐ium were synthesized and tested for biological activity. Antagonists with long‐residence time at receptors are therapeutic targets for the treatment of several neurological and psychiatric human diseases. Their long‐acting effects allow for reduced daily doses and adverse effects. Experimental Approach The binding and antagonism of functional responses to the agonist carbachol mediated by 4‐hexyloxy compounds were investigated in CHO cells expressing individual subtypes of muscarinic receptors and compared with 4‐butyloxy analogues. Key Results The 4‐hexyloxy derivatives were found to bind muscarinic receptors with micromolar affinity and antagonized the functional response to carbachol with a potency ranging from 30 nM at M1 to 4 μM at M3 receptors. Under washing conditions to reverse antagonism, the half‐life of their antagonistic action ranged from 1.7 h at M2 to 5 h at M5 receptors. Conclusions and Implications The 4‐hexyloxy derivatives were found to be potent long‐acting M1‐preferring antagonists. In view of current literature, M1‐selective antagonists may have therapeutic potential for striatal cholinergic dystonia, delaying epileptic seizure after organophosphate intoxication or relieving depression. These compounds may also serve as a tool for research into cognitive deficits. PMID:29498041

Validation and pharmacological characterisation of MK-801-induced locomotor hyperactivity in BALB/C mice as an assay for detection of novel antipsychotics.

PubMed

Bradford, Andrea M; Savage, Kevin M; Jones, Declan N C; Kalinichev, Mikhail

2010-10-01

We evaluated locomotor hyperactivity induced in BALB/C mice by an N-methyl-D-aspartate receptor antagonist MK-801 as an assay for the detection of antipsychotic drugs. We assessed the effects of antipsychotic drugs to validate the assay (study 1), selective dopamine and serotonin ligands for pharmacological characterisation of the model (study 2) and a number of compounds with efficacy in models of schizophrenia to understand the predictive validity of the model (study 3). Adult males (n  = 9/group) were pretreated with a test compound, habituated to locomotor activity cages before receiving MK-801 (0.32 mg/kg) and activity recorded for a further 75 or 120 min. In study 1, we tested haloperidol, clozapine, olanzapine, risperidone, ziprasidone, aripiprazole, sertindole and quetiapine. In study 2, we tested SCH23390 (D(1) antagonist), sulpiride (D(2)/D(3) antagonist), raclopride (D(2)/D(3) antagonist), SB-277011 (D(3) antagonist), L-745,870 (D(4) antagonist), WAY100635 (5-HT(1A) antagonist), 8-OH-DPAT (5-HT(1A) agonist), ketanserin (5-HT(2A)/5-HT(2C) antagonist) and SB-242084 (5-HT(2C) antagonist). In study 3, we tested xanomeline (M(1)/M(4) receptor agonist), LY379268 (mGluR2/3 receptor agonist), diazepam (GABA(A) modulator) and thioperamide (H(3) receptor antagonist). All antipsychotics suppressed MK-801-induced hyperactivity in a dose-dependent and specific manner. The effects of antipsychotics appear to be mediated via dopamine D(1), D(2) and 5-HT(2) receptors. Xanomeline, LY379268 and diazepam were active in this assay while thioperamide was not. MK-801-induced hyperactivity in BALB/C mice model of positive symptoms has shown predictive validity with novel compounds acing at M(1)/M(4), mGluR2/3 and GABA(A) receptors and can be used as a screening assay for detection of novel pharmacotherapies targeting those receptors.

Estrogen Metabolism and Prostate Cancer Risk: A Prospective Study

DTIC Science & Technology

2007-05-01

cimetidine, soy products , or flaxseed supplements within 2 months of participation. Of 422 women inquiring about participation, 122 (29%) declined...until consumption, and participants were given suggestions as to how to incorporate it 14 into their usual diets (e.g., in yogurt , stirred into...enterolactone production by food group used to consume the flax and observed no differences. To assess compliance, the participants were asked to record

High pH-Sensitive TRPA1 Activation in Odontoblasts Regulates Mineralization.

PubMed

Kimura, M; Sase, T; Higashikawa, A; Sato, M; Sato, T; Tazaki, M; Shibukawa, Y

2016-08-01

Calcium hydroxide and mineral trioxide aggregate are widely used for indirect and direct pulp capping and root canal filling. Their dissociation into Ca(2+) and OH(-) in dental pulp creates an alkaline environment, which activates reparative/reactionary dentinogenesis. However, the mechanisms by which odontoblasts detect the pH of the extracellular environment remain unclear. We examined the alkali-sensitive intracellular Ca(2+) signaling pathway in rat odontoblasts. In the presence or absence of extracellular Ca(2+), application of alkaline solution increased intracellular Ca(2+) concentration, or [Ca(2+)]i Alkaline solution-induced [Ca(2+)]i increases depended on extracellular pH (8.5 to 10.5) in both the absence and the presence of extracellular Ca(2+) The amplitude was smaller in the absence than in the presence of extracellular Ca(2+) Each increase in [Ca(2+)]i, activated by pH 7.5, 8.5, or 9.5, depended on extracellular Ca(2+) concentration; the equilibrium binding constant for extracellular Ca(2+) concentration decreased as extracellular pH increased (1.04 mM at pH 7.5 to 0.11 mM at pH 9.5). Repeated applications of alkaline solution did not have a desensitizing effect on alkali-induced [Ca(2+)]i increases and inward currents. In the presence of extracellular Ca(2+), alkaline solution-induced [Ca(2+)]i increases were suppressed by application of an antagonist of transient receptor potential ankyrin subfamily member 1 (TRPA1) channels. Ca(2+) exclusion efficiency during alkaline solution-induced [Ca(2+)]i increases was reduced by a Na(+)-Ca(2+) exchanger antagonist. Alizarin red and von Kossa staining revealed increased mineralization levels under repeated high pH stimulation, whereas the TRPA1 antagonist strongly reduced this effect. These findings indicate that alkaline stimuli-such as the alkaline environment inside dental pulp treated with calcium hydroxide or mineral trioxide aggregate-activate Ca(2+) mobilization via Ca(2+) influx mediated by TRPA1 channels and intracellular Ca(2+) release in odontoblasts. High pH-sensing mechanisms in odontoblasts are important for activating dentinogenesis induced by an alkaline environment. © International & American Associations for Dental Research 2016.

Opposing effects of AMPA and 5-HT1A receptor blockade on passive avoidance and object recognition performance: correlation with AMPA receptor subunit expression in rat hippocampus.

PubMed

Schiapparelli, L; Simón, A M; Del Río, J; Frechilla, D

2006-06-01

It has been suggested that antagonists at serotonin 5-HT1A receptors may exert a procognitive effect by facilitating glutamatergic neurotransmission. Here we further explored this issue by looking for the ability of a 5-HT1A antagonist to prevent the learning deficit induced by AMPA receptor blockade in two behavioural procedures in rats, and for concomitant molecular changes presumably involved in memory formation in the hippocampus. Pretraining administration of the competitive AMPA receptor antagonist, NBQX, produced a dose-related retention impairment in a passive avoidance task 24h later, and also impaired retention in a novel object recognition test when an intertrial interval of 3h was selected. Pretreatment with the selective 5-HT1A receptor antagonist, WAY-100635, prevented the learning deficit induced by NBQX in the two behavioural procedures. In biochemical studies performed on rat hippocampus after the retention tests, we found that learning increased the membrane levels of AMPA receptor GluR1 and GluR2/3 subunits, as well as the phosphorylated forms of GluR1, effects that were abolished by NBQX administration before the training session. Pretreatment with WAY-100635 counteracted the NBQX effects and restored the initial learning-specific increase in Ca2+/calmodulin-dependent protein kinase II (CaMKII) function and the later increase in GluR2/3 and phosphorylated GluR1 surface expression. Moreover, administration of WAY-100635 before object recognition training improved recognition memory 24h later and potentiated the learning-associated increase in AMPA receptor subunits. The results support the proposed utility of 5-HT1A antagonists in the treatment of cognitive disorders.

Hydrogen peroxide preferentially activates capsaicin-sensitive high threshold afferents via TRPA1 channels in the guinea pig bladder.

PubMed

Nicholas, S; Yuan, S Y; Brookes, S J H; Spencer, N J; Zagorodnyuk, V P

2017-01-01

There is increasing evidence suggesting that ROS play a major pathological role in bladder dysfunction induced by bladder inflammation and/or obstruction. The aim of this study was to determine the effect of H 2 O 2 on different types of bladder afferents and its mechanism of action on sensory neurons in the guinea pig bladder. 'Close-to-target' single unit extracellular recordings were made from fine branches of pelvic nerves entering the guinea pig bladder, in flat sheet preparations, in vitro. H 2 O 2 (300-1000 μM) preferentially and potently activated capsaicin-sensitive high threshold afferents but not low threshold stretch-sensitive afferents, which were only activated by significantly higher concentrations of hydrogen peroxide. The TRPV1 channel agonist, capsaicin, excited 86% of high threshold afferents. The TRPA1 channel agonist, allyl isothiocyanate and the TRPM8 channel agonist, icilin activated 72% and 47% of capsaicin-sensitive high threshold afferents respectively. The TRPA1 channel antagonist, HC-030031, but not the TRPV1 channel antagonist, capsazepine or the TRPM8 channel antagonist, N-(2-aminoethyl)-N-[[3-methoxy-4-(phenylmethoxy)phenyl]methyl]thiophene-2-carboxamide, significantly inhibited the H 2 O 2 -induced activation of high threshold afferents. Dimethylthiourea and deferoxamine did not significantly change the effect of H 2 O 2 on high threshold afferents. The findings show that H 2 O 2 , in the concentration range detected in inflammation or reperfusion after ischaemia, evoked long-lasting activation of the majority of capsaicin-sensitive high threshold afferents, but not low threshold stretch-sensitive afferents. The data suggest that the TRPA1 channels located on these capsaicin-sensitive afferent fibres are probable targets of ROS released during oxidative stress. © 2016 The British Pharmacological Society.

Binding of [3H] SR 49059, a potent nonpeptide vasopressin V1a antagonist, to rat and human liver membranes.

PubMed

Serradeil-Le Gal, C; Raufaste, D; Marty, E; Garcia, C; Maffrand, J P; Le Fur, G

1994-02-28

The new potent and selective nonpeptide vasopressin V1a antagonist, SR 49059, was tritiated and used for the characterization of rat and human liver AVP V1a receptors. Binding of [3H] SR 49059 was time-dependent, reversible and saturable. A single class of high affinity binding sites was identified with Kd values of 0.63 +/- 0.13 and 2.95 +/- 0.64 nM, in rat and human liver membranes, respectively. The maximal binding capacity (Bmax) was about 7 times higher in rat than in human liver preparations. The relative potencies of several AVP/oxytocin agonists or antagonists to inhibit [3H] SR 49059 binding confirmed that this ligand labeled a homogeneous population of sites with the expected AVP V1a profile. Furthermore, [3H] SR 49059 or unlabeled SR 49059 displayed only slight species differences between rat and human V1a receptors, whereas OPC-21268, another nonpeptide V1a antagonist, exhibited a high species-related potency with more than 500 fold higher affinity for rat than for human liver V1a receptors. Thus, [3H] SR 49059 is the first nonpeptide AVP V1a ligand reported having highly specific activity, stability, specificity and affinity. This makes it a suitable probe for labeling AVP V1a receptors in rat and also in human tissues.

Nucleus accumbens acetylcholine and food intake: decreased muscarinic tone reduces feeding but not food-seeking.

PubMed

Pratt, Wayne E; Blackstone, Kaitlin

2009-03-02

Separate groups of food-deprived rats were given 2h access to food after receiving bilateral nucleus accumbens infusions of the muscarinic antagonist scopolamine methyl bromide (at 0, 1.0, and 10.0 microg/side), the M2-preferring agonist oxotremorine sesquifumarate (Oxo-S; at 0, 1.0, or 10.0 microg/side) or the M2 antagonist AFDX-116 (at 0, 0.2, or 1.0 microg/side). Injections of scopolamine or Oxo-S, but not AFDX-116, reduced food consumption across the 2h. These experiments confirm a critical role for Acb acetylcholine in promoting food ingestion, and suggest that decreased acetylcholine tone at post-synaptic muscarinic receptors disrupts normal consummatory behavior.

Exploiting Free-Energy Minima to Design Novel EphA2 Protein-Protein Antagonists: From Simulation to Experiment and Return.

PubMed

Russo, Simonetta; Callegari, Donatella; Incerti, Matteo; Pala, Daniele; Giorgio, Carmine; Brunetti, Jlenia; Bracci, Luisa; Vicini, Paola; Barocelli, Elisabetta; Capoferri, Luigi; Rivara, Silvia; Tognolini, Massimiliano; Mor, Marco; Lodola, Alessio

2016-06-06

The free-energy surface (FES) of protein-ligand binding contains information useful for drug design. Here we show how to exploit a free-energy minimum of a protein-ligand complex identified by metadynamics simulations to design a new EphA2 antagonist with improved inhibitory potency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Guanidine-acylguanidine bioisosteric approach in the design of radioligands: synthesis of a tritium-labeled N(G)-propionylargininamide ([3H]-UR-MK114) as a highly potent and selective neuropeptide Y Y1 receptor antagonist.

PubMed

Keller, Max; Pop, Nathalie; Hutzler, Christoph; Beck-Sickinger, Annette G; Bernhardt, Günther; Buschauer, Armin

2008-12-25

Synthesis and characterization of (R)-N(alpha)-(2,2-diphenylacetyl)-N-(4-hydroxybenzyl)-N(omega)-([2,3-(3)H]-propanoyl)argininamide ([(3)H]-UR-MK114), an easily accessible tritium-labeled NPY Y(1) receptor (Y(1)R) antagonist (K(B): 0.8 nM, calcium assay, HEL cells) derived from the (R)-argininamide BIBP 3226, is reported. The radioligand binds with high affinity (K(D), saturation: 1.2 nM, kinetic experiments: 1.1 nM, SK-N-MC cells) and selectivity for Y(1)R over Y(2), Y(4), and Y(5) receptors. The title compound is a useful pharmacological tool for the determination of Y(1)R ligand affinities, quantification of Y(1)R binding sites, and autoradiography.

Jak2 and Ca2+/calmodulin are key intermediates for bradykinin B2 receptor-mediated activation of Na+/H+ exchange in KNRK and CHO cells.

PubMed

Lefler, David; Mukhin, Yurii V; Pettus, Tobiah; Leeb-Lundberg, L M Fredrik; Garnovskaya, Maria N; Raymond, John R

2003-04-01

Na(+)/H(+) exchangers are ubiquitous in mammalian cells, carrying out key functions, such as cell volume defense, acid-base homeostasis, and regulation of the cytoskeleton. We used two screening technologies (FLIPR and microphysiometry) to characterize the signal transduction pathway used by the bradykinin B(2) receptor to activate Na(+)/H(+) exchange in two cell lines, KNRK and CHO. In both cell types, B(2) receptor activation resulted in rapid increases in the rate of proton extrusion that were sodium-dependent and could be blocked by the Na(+)/H(+) exchange inhibitors EIPA and MIA or by replacing extracellular sodium with TMA. Activation of Na(+)/H(+) exchange by bradykinin was concentration-dependent and could be blocked by the selective B(2) receptor antagonist HOE140, but not by the B(1) receptor antagonist des-Arg10-HOE140. Inhibitors of Jak2 tyrosine kinase (genistein and AG490) and of CAM (W-7 and calmidazolium) attenuated bradykinin-induced activation of Na(+)/H(+) exchange. Bradykinin induced formation of a complex between CAM and Jak2, supporting a regulatory role for Jak2 and CAM in the activation of Na(+)/H(+) exchange in KNRK and CHO cells. We propose that this pathway (B(2) receptor --> Jak2 --> CAM --> Na(+)/H(+) exchanger) is a fundamental regulator of Na(+)/H(+) exchange activity.

Use of molecular modeling aided design to dial out hERG liability in adenosine A(2A) receptor antagonists.

PubMed

Deng, Qiaolin; Lim, Yeon-Hee; Anand, Rajan; Yu, Younong; Kim, Jae-hun; Zhou, Wei; Zheng, Junying; Tempest, Paul; Levorse, Dorothy; Zhang, Xiaoping; Greene, Scott; Mullins, Deborra; Culberson, Chris; Sherborne, Brad; Parker, Eric M; Stamford, Andrew; Ali, Amjad

2015-08-01

Molecular modeling was performed on a triazolo quinazoline lead compound to help develop a series of adenosine A2A receptor antagonists with improved hERG profile. Superposition of the lead compound onto MK-499, a benchmark hERG inhibitor, combined with pKa calculations and measurement, identified terminal fluorobenzene to be responsible for hERG activity. Docking of the lead compound into an A2A crystal structure suggested that this group is located at a flexible, spacious, and solvent-exposed opening of the binding pocket, making it possible to tolerate various functional groups. Transformation analysis (MMP, matched molecular pair) of in-house available experimental data on hERG provided suggestions for modifications in order to mitigate this liability. This led to the synthesis of a series of compounds with significantly reduced hERG activity. The strategy used in the modeling work can be applied to other medicinal chemistry programs to help improve hERG profile. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thoracic vagal efferent nerve stimulation evokes substance P-induced early airway bronchonstriction and late proinflammatory and oxidative injury in the rat respiratory tract.

PubMed

Li, Ping-Chia; Li, Sheng-Chung; Lin, Yuan-Ju; Liang, Jin-Tung; Chien, Chiang-Ting; Shaw, Chen-Fu

2005-01-01

Electrical stimulation of efferent thoracic vagus nerve (TVN) evoked neurogenic inflammation in respiratory tract of atropine-treated rats by an undefined mechanism. We explored whether efferent TVN stimulation via substance P facilitates neurogenic inflammation via action of nuclear factor-kappaB (NF-kappaB) activation and reactive oxygen species (ROS) production. Our results showed that increased frequency of TVN stimulation concomitantly increased substance P-enhanced hypotension, and bronchoconstriction (increases in smooth muscle electromyographic activity and total pulmonary resistance). The enhanced SP release evoked the appearance of endothelial gap in silver-stained leaky venules, India-ink labeled extravasation, and accumulations of inflammatory cells in the respiratory tract, contributing to trachea plasma extravasation as well as increases in blood O (2)(-) and H(2)O(2) ROS amount. L-732138 (NK(1) receptor antagonist), SR-48968 (NK(2) receptor antagonist), dimethylthiourea (H(2)O(2) scavenger) or catechins (O (2)(-) and H(2)O(2) scavenger) pretreatment reduced efferent TVN stimulation-enhanced hypotension, bronchoconstriction, and plasma extravasation. Increased frequency of TVN stimulation significantly upregulated the expression of nuclear factor-kappaB (NF-kappaB) in nuclear protein and intercellular adhesion molecule-1 (ICAM-1) in total protein of the lower respiratory tract tissue. The upregulation of NF-kappaB and ICAM-1 was attenuated by NK receptor antagonist and antioxidants. In conclusion, TVN efferent stimulation increases substance P release to trigger NF-kappaB mediated ICAM-1 expression and O (2)(-) and H(2)O(2) ROS production in the respiratory tract.

Effect of alpha-adrenoceptor antagonists (phentolamine, nicergoline and prazosin) on reperfusion arrhythmias and noradrenaline release in perfused rat heart.

PubMed Central

Bralet, J.; Didier, J.; Moreau, D.; Opie, L. H.; Rochette, L.

1985-01-01

Rat isolated hearts were perfused through the left atrium with a modified Krebs-Henseleit solution or mounted on a Langendorff perfusion system. The hearts were prelabelled with [3H]-noradrenaline [( 3H]-NA) and the left main coronary artery was ligated for 10 min after which reperfusion followed. The liberation of [3H]-NA and the development of ventricular tachycardia and fibrillation were monitored throughout. During the occlusion period, ventricular arrhythmias did not occur and heart rate was not significantly altered in the control series. In contrast, reperfusion was followed by ventricular fibrillation and ventricular tachycardia in all the hearts in the control series (Langendorff or 'working' models). The alpha-adrenoceptor antagonists phentolamine (7.1 X 10(-6) M and 7.1 X 10(-5) M) and nicergoline (3.1 X 10(-6) M) diminished or prevented reperfusion arrhythmias. However, prazosin (5.2 X 10(-6) M) was not effective. The lower concentration of phentolamine did not alter the pattern of [3H]-NA release, whereas, high doses of phentolamine and nicergoline increased the release of [3H]-NA. Prazosin (5.2 X 10(-6) M) caused a very marked increase in release of [3H]-NA but was not antiarrhythmic. A 'membrane-stabilizing' effect seems the most appropriate explanation for these antiarrhythmic effects of alpha-antagonist agents. PMID:2858234

Histamine H2 receptor - Involvement in gastric ulceration

NASA Technical Reports Server (NTRS)

Brown, P. A.; Vernikos-Danellis, J.; Brown, T. H.

1976-01-01

The involvement of the H1 and H2 receptors for histamine in the pathogenesis of gastric ulcers was investigated in rats. Metiamide, an H2 receptor antagonist, reliably reduced ulceration produced by stress alone or by a combination of stress and aspirin. In contrast, pyrilamine, which blocks only the H1 receptor, was without effect under these same conditions. The results support the hypothesis that histamine mediates both stress and stress plus aspirin induced ulceration by a mechanism involving the H2 receptor.

Multidrug and toxin extrusion proteins mediate cellular transport of cadmium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Hong; Guo, Dong; Obianom, Obinna N.

Cadmium (Cd) is an environmentally prevalent toxicant posing increasing risk to human health worldwide. As compared to the extensive research in Cd tissue accumulation, little was known about the elimination of Cd, particularly its toxic form, Cd ion (Cd{sup 2+}). In this study, we aimed to examine whether Cd{sup 2+} is a substrate of multidrug and toxin extrusion proteins (MATEs) that are important in renal xenobiotic elimination. HEK-293 cells overexpressing the human MATE1 (HEK-hMATE1), human MATE2-K (HEK-hMATE2-K) and mouse Mate1 (HEK-mMate1) were used to study the cellular transport and toxicity of Cd{sup 2+}. The cells overexpressing MATEs showed a 2–4more » fold increase of Cd{sup 2+} uptake that could be blocked by the MATE inhibitor cimetidine. A saturable transport profile was observed with the Michaelis-Menten constant (K{sub m}) of 130 ± 15.8 μM for HEK-hMATE1; 139 ± 21.3 μM for HEK-hMATE2-K; and 88.7 ± 13.5 μM for HEK-mMate1, respectively. Cd{sup 2+} could inhibit the uptake of metformin, a substrate of MATE transporters, with the half maximal inhibitory concentration (IC{sub 50}) of 97.5 ± 6.0 μM, 20.2 ± 2.6 μM, and 49.9 ± 6.9 μM in HEK-hMATE1, HEK-hMATE2-K, and HEK-mMate1 cells, respectively. In addition, hMATE1 could transport preloaded Cd{sup 2+} out of the HEK-hMATE1 cells, thus resulting in a significant decrease of Cd{sup 2+}-induced cytotoxicity. The present study has provided the first evidence supporting that MATEs transport Cd{sup 2+} and may function as cellular elimination machinery in Cd intoxication. - Highlights: • Cadmium is an environmentally prevalent toxicant. • Little was known regarding the elimination and detoxification of cadmium. • Cadmium ion is here demonstrated as a substrate of MATE transporters. • MATEs may function as cellular elimination machinery in cadmium detoxification.« less

6-Methoxyflavanones as Bitter Taste Receptor Blockers for hTAS2R39

PubMed Central

Roland, Wibke S. U.; Gouka, Robin J.; Gruppen, Harry; Driesse, Marianne; van Buren, Leo; Smit, Gerrit; Vincken, Jean-Paul

2014-01-01

Many (dietary) bitter compounds, e.g. flavonoids, activate bitter receptor hTAS2R39 in cell-based assays. Several flavonoids, amongst which some flavanones, are known not to activate this receptor. As certain flavanones are known to mask bitter taste sensorially, flavanones might act as bitter receptor antagonists. Fourteen flavanones were investigated for their potential to reduce activation of hTAS2R39 by epicatechin gallate (ECG), one of the main bitter compounds occurring in green tea. Three flavanones showed inhibitory behavior towards the activation of hTAS2R39 by ECG: 4′-fluoro-6-methoxyflavanone, 6,3′-dimethoxyflavanone, and 6-methoxyflavanone (in order of decreasing potency). The 6-methoxyflavanones also inhibited activation of hTAS2R14 (another bitter receptor activated by ECG), though to a lesser extent. Dose-response curves of ECG at various concentrations of the full antagonist 4′-fluoro-6-methoxyflavanone and wash-out experiments indicated reversible insurmountable antagonism. The same effect was observed for the structurally different agonist denatonium benzoate. PMID:24722342

The H(2)-receptor antagonist ranitidine interferes with clopidogrel-mediated P2Y(12) inhibition in platelets.

PubMed

Schäfer, Andreas; Flierl, Ulrike; Pförtsch, Stephanie; Seydelmann, Nora; Micka, Jan; Bauersachs, Johann

2010-10-01

Use of proton-pump inhibitors (PPIs) is common in patients on dual antiplatelet therapy (DAT). Recent warnings about potential interactions of PPIs with clopidogrel metabolism leading to impaired DAT efficacy has prompted the recommendation of substituting PPIs with H(2)-receptor antagonists such as ranitidine. We investigated whether ranitidine interacts with P2Y(12) inhibition on the platelet level. Blood was collected from 15 patients with stable coronary artery disease, who had undergone elective coronary intervention. Clopidogrel responsiveness was assessed 24h after the administration of a 600mg loading dose using the P2Y(12) specific platelet-reactivity-index (PRI) and light-transmittance aggregometry in the presence and absence of a pharmacologically relevant concentration of the H(2)-receptor antagonist ranitidine (400ng/ml). Adding ranitidine enhanced P2Y(12)-mediated platelet reactivity to ADP assessed by the PRI (mean PRI+/-SEM: before ranitidine 28+/-5%; after ranitidine 37+/-5%, p=0.0025). Similarly, prostaglandin E1 (PGE(1))-mediated inhibition of ADP-induced aggregation was abrogated in the presence of ranitidine (Agg(max)+/-SEM: before PGE(1) 41+/-2%; after PGE(1) 29+/-2%, p<0.01 vs. before PGE(1); after PGE(1)+ranitidine 42+/-2%, p<0.01 vs. after PGE(1)). Exposition of platelets with ranitidine significantly enhanced their responsiveness to ADP and contributed to impaired P2Y(12) inhibition suggesting that ranitidine interacts with clopidogrel efficacy through adenylyl cyclase inhibition on the platelet level. Copyright 2010 Elsevier Ltd. All rights reserved.

Comparative gastroprotective effects of natural honey, Nigella sativa and cimetidine against acetylsalicylic acid induced gastric ulcer in albino rats.

PubMed

Bukhari, Mulazim Hussain; Khalil, Javed; Qamar, Samina; Qamar, Zahid; Zahid, Muhammad; Ansari, Navid; Bakhshi, Irfan Manzoor

2011-03-01

Natural honey (NH) and Nigella sativa (NS) seeds have been in use as a natural remedy for over thousands of years in various parts of the world. The aim of this study was to assess the protective effects of NS (Nigella sativa) and NH (natural honey) on acetylsalicylic acid induced gastric ulcer in an experimental model with comparison to Cimetidine (CD). Experimental, case control study. Pharmacology and Pathology Department of King Edward Medical University, Lahore, from June to August 2007. The study was conducted on 100 male albino rats, divided into 5 groups, with 20 animals in each group. Group A was used as a control and treated with Gum Tragacanth (GT). Eighty animals of the other groups were given acetylsalicylic acid (0.2 gm/kg body weight for 3 days) to produce ulcers by gavage. Two animals from each group were sacrificed for the detection of gastric ulcers. The remaining 72 animals were equally divided in four groups (B, C, D and E). The rats in group B, C and D were given NS, NH, and CD respectively while those in E were kept as such. No gastric lesions were seen in control group A while all the animals in group E revealed gastric ulcers. The animals of group B, C and D showed healing effects in 15/18 (83%), 14/18 (78%) and 17/18 (94%) animals grossly; 13/18 (72%), 14/18 (78%) and 16/18 (89%) rats showed recovery on microscopic examination respectively. The healing effects were almost the same in all three groups therefore, the statistical difference was not significant among them (p =0.40 and 0.65) while significant from group E (p=0.0000075, 0.0000016 and 0.0000012 respectively). NS and NH are equally effective in healing of gastric ulcer similar to cimetidine. Further broad spectrum studies as well as clinical trials should be conducted before the use of these products as routine medicines.

One pot synthesis of some new substituted hexahydro 2H-1,3-benzoxazine derivatives.

PubMed

Safak, C; Simsek, R; Altas, Y; Erol, K; Boydag, S

1996-09-01

In this paper, we synthesized nineteen new compounds having 2,4-diaryl-5-oxohexahydro-2H-1,3-benzoxazine structure by the reaction of 1,3-cyclohexanedione, aromatic aldehyde and ammonium acetate. In addition, we evaluated calcium antagonistic activity of these compounds versus nicardipine.

Anti-ulcerogenic effect of cavidine against ethanol-induced acute gastric ulcer in mice and possible underlying mechanism.

PubMed

Li, Weifeng; Wang, Xiumei; Zhang, Hailin; He, Zehong; Zhi, Wenbing; Liu, Fang; Wang, Yu; Niu, Xiaofeng

2016-09-01

Cavidine, a major alkaloid compound isolated from Corydalis impatiens, has various pharmacological effects but its effect on gastric ulcer has not been previously explored. The current study aimed to investigate the possible anti-ulcerogenic potential of cavidine in the model of ethanol-induced gastric ulcer. Mice received cavidine (1, 5 or 10mg/kg, ig), cimetidine (CMD, 100mg/kg, ig) or vehicle at 12h and 1h before absolute ethanol administration (0.5mL/100g), and animals were euthanized 3h after ethanol ingestion. Gross and histological gastric lesions, biochemical, immunological and Western blot parameters were taken into consideration. The results showed that ethanol administration produced apparent mucosal injuries with morphological and histological damage, whereas cavidine pre-treatment reduced the gastric injuries. Cavidine pre-treatment also ameliorated the contents of malonaldehyde (MDA) and myeloperoxidase (MPO) activity, and increased the mucosa levels of glutathione (GSH), superoxide dismutase (SOD) and prostaglandin E2 (PGE2), relative to the model group. Also cavidine was able to decrease the levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), inhibit the up-regulation of cyclo-oxygenase-2 (COX-2) expression and activation of Nuclear factor-kappa B (NF-κB) pathway. Taken together, these results indicated that cavidine exerts a gastroprotective effect against gastric ulceration, and the underlying mechanism might be associated with the stimulation of PGE2, reduction of oxidative stress, suppression of NF-κB expression and subsequent reduced COX-2 and pro-inflammatory cytokines. Copyright © 2016 Elsevier B.V. All rights reserved.

Lead identification of acetylcholinesterase inhibitors-histamine H3 receptor antagonists from molecular modeling.

PubMed

Bembenek, Scott D; Keith, John M; Letavic, Michael A; Apodaca, Richard; Barbier, Ann J; Dvorak, Lisa; Aluisio, Leah; Miller, Kirsten L; Lovenberg, Timothy W; Carruthers, Nicholas I

2008-03-15

Currently, the only clinically effective treatment for Alzheimer's disease (AD) is the use of acetylcholinesterase (AChE) inhibitors. These inhibitors have limited efficacy in that they only treat the symptoms and not the disease itself. Additionally, they often have unpleasant side effects. Here we consider the viability of a single molecule having the actions of both an AChE inhibitor and histamine H(3) receptor antagonist. Both histamine H(3) receptor antagonists and AChE inhibitors improve and augment cholinergic neurotransmission in the cortex. However, whereas an AChE inhibitor will impart its effect everywhere, a histamine H(3) antagonist will raise acetylcholine levels mostly in the brain as its mode of action will primarily be on the central nervous system. Therefore, the combination of both activities in a single molecule could be advantageous. Indeed, studies suggest an appropriate dual-acting compound may offer the desired therapeutic effect with fewer unpleasant side effects [CNS Drugs2004, 18, 827]. Further, recent studies(2) indicate the peripheral anionic site (PAS) of AChE interacts with the beta-amyloid (betaA) peptide. Consequently, a molecule capable of disrupting this interaction may have a significant impact on the production of or the aggregation of betaA. This may result in slowing down the progression of the disease rather than only treating the symptoms as current therapies do. Here, we detail how the use of the available crystal structure information, pharmacophore modeling and docking (automated, manual, classical, and QM/MM) lead to the identification of an AChE inhibitor-histamine H(3) receptor antagonist. Further, based on our models we speculate that this dual-acting compound may interact with the PAS. Such a dual-acting compound may be able to affect the pathology of AD in addition to providing symptomatic relief.

Synthesis, radiolabeling, and preliminary biological evaluation of [3H]-1-[(S)-N,O-bis-(isoquinolinesulfonyl)-N-methyl-tyrosyl]-4-(o-tolyl)-piperazine, a potent antagonist radioligand for the P2X7 receptor.

PubMed

Romagnoli, Romeo; Baraldi, Pier Giovanni; Pavani, Maria Giovanna; Tabrizi, Mojgan Aghazadeh; Moorman, Allan R; Di Virgilio, Francesco; Cattabriga, Elena; Pancaldi, Cecilia; Gessi, Stefania; Borea, Pier Andrea

2004-11-15

The design, synthesis, and preliminary biological evaluation of the first potent radioligand antagonist for the P2X(7) receptor, named [(3)H]-1-[(S)-N,O-bis-(isoquinolinesulfonyl)-N-methyl-tyrosyl]-4-(o-tolyl)-piperazine (compound 13), are reported. This compound bound to human P2X(7) receptors expressed in HEK transfected cells with K(D) and B(max) value of 3.46+/-0.1 nM and 727+/-73 fmol/mg of protein, respectively. The high affinity and facile labeling makes it a promising radioligand for a further characterization of P2X(7) receptor subtype.

Preclinical pharmacology of bilastine, a new selective histamine H1 receptor antagonist: receptor selectivity and in vitro antihistaminic activity.

PubMed

Corcóstegui, Reyes; Labeaga, Luis; Innerárity, Ana; Berisa, Agustin; Orjales, Aurelio

2005-01-01

This study aimed to establish the receptor selectivity and antihistaminic activity of bilastine, a new selective antihistamine receptor antagonist. In vitro experiments were conducted using a receptor binding screening panel and guinea-pig and rat tissues. Antihistaminic activity was determined using H1 receptor binding studies and in vitro H1 antagonism studies conducted in guinea-pig tissues and human cell lines. Receptor selectivity was established using a receptor binding screening panel and a receptor antagonism screening conducted in guinea-pig, rat and rabbit tissues. Inhibition of inflammatory mediators was determined through the Schultz-Dale reaction in sensitised guinea-pig ileum. Bilastine binds to histamine H1-receptors as indicated by its displacement of [3H]-pyrilamine from H1-receptors expressed in guinea-pig cerebellum and human embryonic kidney (HEK) cell lines. The studies conducted on guinea-pig smooth muscle demonstrated the capability of bilastine to antagonise H1-receptors. Bilastine is selective for histamine H1-receptors as shown in receptor-binding screening conducted to determine the binding capacity of bilastine to 30 different receptors. The specificity of its H1-receptor antagonistic activity was also demonstrated in a series of in vitro experiments conducted on guinea-pig and rat tissues. The results of these studies confirmed the lack of significant antagonism against serotonin, bradykinin, leukotriene D4, calcium, muscarinic M3-receptors, alpha1-adrenoceptors, beta2-adrenoceptors, and H2- and H3-receptors. The results of the in vitro Schultz-Dale reaction demonstrated that bilastine also has anti-inflammatory activity. These preclinical studies provide evidence that bilastine has H1- antihistamine activity, with high specificity for H1-receptors, and poor or no affinity for other receptors. Bilastine has also been shown to have anti-inflammatory properties.

Discovery of Fevipiprant (NVP-QAW039), a Potent and Selective DP2 Receptor Antagonist for Treatment of Asthma

PubMed Central

2017-01-01

Further optimization of an initial DP2 receptor antagonist clinical candidate NVP-QAV680 led to the discovery of a follow-up molecule 2-(2-methyl-1-(4-(methylsulfonyl)-2-(trifluoromethyl)benzyl)-1H-pyrrolo[2,3-b]pyridin-3-yl)acetic acid (compound 11, NVP-QAW039, fevipiprant), which exhibits improved potency on human eosinophils and Th2 cells, together with a longer receptor residence time, and is currently in clinical trials for severe asthma. PMID:28523115

MEN16132, a novel potent and selective nonpeptide antagonist for the human bradykinin B2 receptor. In vitro pharmacology and molecular characterization.

PubMed

Cucchi, Paola; Meini, Stefania; Bressan, Alessandro; Catalani, Claudio; Bellucci, Francesca; Santicioli, Paolo; Lecci, Alessandro; Faiella, Angela; Rotondaro, Luigi; Giuliani, Sandro; Giolitti, Alessandro; Quartara, Laura; Maggi, Carlo Alberto

2005-12-28

The pharmacological characterization of the novel nonpeptide antagonist for the B2 receptor, namely MEN16132 (4-(S)-Amino-5-(4-{4-[2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido]-tetrahydro-2H-4-pyranylcarbonyl}piperazino)-5-oxopentyl](trimethyl)ammonium chloride hydrochloride) is presented. The affinity of MEN16132 for the bradykinin B2 receptor has been investigated by means of competition studies at [3H]bradykinin binding to membranes prepared from Chinese Hamster Ovary (CHO) cells expressing the human bradykinin B2 receptor (pKi 10.5), human lung fibroblasts (pKi 10.5), guinea pig airways (pKi 10.0), guinea pig ileum longitudinal smooth muscle (pKi 10.2), or guinea pig cultured colonic myocytes (pKi 10.3). In all assays MEN16132 was as potent as the peptide antagonist Icatibant, and from 3- to 100-fold more potent than the reference nonpeptide antagonists FR173657 or LF16-0687. The selectivity for the bradykinin B2 receptor was checked at the human bradykinin B1 receptor (pKi<5), and at a panel of 26 different receptors and channels. The antagonist potency was measured in functional assays, i.e., in blocking the bradykinin induced inositolphosphates (IP) accumulation at the human (CHO: pKB 10.3) and guinea pig (colonic myocytes: pKB 10.3) B2 receptor, or in antagonizing the bradykinin induced contractile responses in human (detrusor smooth muscle: pKB 9.9) and guinea pig (ileum longitudinal smooth muscle: pKB 10.1) tissues. In both functional assay types MEN16132 exerted a different antagonist pattern, i.e., surmountable at the human and insurmountable at the guinea pig bradykinin B2 receptors. Moreover, the receptor determinants important for the high affinity interaction of MEN16132 with the human bradykinin B2 receptor were investigated by means of radioligand binding studies performed at 24 point-mutated receptors. The results obtained revealed that residues in transmembrane segment 2 (W86A), 3 (I110A), 6 (W256A), and 7 (Y295A, Y295F but not much Y295W), were crucial for the high affinity of MEN16132. In conclusion, MEN16132 is a new, potent, and selective nonpeptide bradykinin B2 receptor antagonist.

Synthesis, biological evaluation, and computational studies of Tri- and tetracyclic nitrogen-bridgehead compounds as potent dual-acting AChE inhibitors and hH3 receptor antagonists.

PubMed

Darras, Fouad H; Pockes, Steffen; Huang, Guozheng; Wehle, Sarah; Strasser, Andrea; Wittmann, Hans-Joachim; Nimczick, Martin; Sotriffer, Christoph A; Decker, Michael

2014-03-19

Combination of AChE inhibiting and histamine H3 receptor antagonizing properties in a single molecule might show synergistic effects to improve cognitive deficits in Alzheimer's disease, since both pharmacological actions are able to enhance cholinergic neurotransmission in the cortex. However, whereas AChE inhibitors prevent hydrolysis of acetylcholine also peripherally, histamine H3 antagonists will raise acetylcholine levels mostly in the brain due to predominant occurrence of the receptor in the central nervous system. In this work, we designed and synthesized two novel classes of tri- and tetracyclic nitrogen-bridgehead compounds acting as dual AChE inhibitors and histamine H3 antagonists by combining the nitrogen-bridgehead moiety of novel AChE inhibitors with a second N-basic fragment based on the piperidinylpropoxy pharmacophore with different spacer lengths. Intensive structure-activity relationships (SARs) with regard to both biological targets led to compound 41 which showed balanced affinities as hAChE inhibitor with IC50 = 33.9 nM, and hH3R antagonism with Ki = 76.2 nM with greater than 200-fold selectivity over the other histamine receptor subtypes. Molecular docking studies were performed to explain the potent AChE inhibition of the target compounds and molecular dynamics studies to explain high affinity at the hH3R.

Unsurmountable antagonism of brain 5-hydroxytryptamine2 receptors by (+)-lysergic acid diethylamide and bromo-lysergic acid diethylamide.

PubMed

Burris, K D; Sanders-Bush, E

1992-11-01

Lysergic acid diethylamide (LSD) and its structural analogue 2-bromo-lysergic acid diethylamide (BOL) act as unsurmountable antagonists of serotonin-elicited contractions in smooth muscle preparations. Two different models, allosteric and kinetic, have been invoked to explain these findings. The present studies investigate the mechanism of antagonism of brain 5-hydroxytryptamine (5HT)2 receptors, utilizing cells transfected with 5HT2 receptor cDNA cloned from rat brain. A proximal cellular response, phosphoinositide hydrolysis, was examined in order to minimize possible postreceptor effects. Even though LSD behaved as a partial agonist and BOL as a pure antagonist, both drugs blocked the effect of serotonin in an unsurmountable manner, i.e., increasing concentrations of serotonin could not overcome the blocking effect of LSD or BOL. Radioligand binding studies showed that preincubation of membranes with either LSD or BOL reduced the density of [3H]ketanserin binding sites, suggesting that the drugs bind tightly to the 5HT2 receptor and are not displaced during the binding assay. Two additional experiments supported this hypothesis. First, the off-rate of [3H] LSD was slow (20 min), relative to that of [3H]ketanserin (approximately 4 min). Second, when the length of incubation with [3H]ketanserin was increased to 60 min, the LSD-induced decrease in Bmax was essentially eliminated. The possibility that LSD and BOL decrease [3H]ketanserin binding by interacting with an allosteric site was rejected, because neither drug altered the rate of dissociation of [3H]ketanserin. The most parsimonious interpretation of these results is that unsurmountable antagonism reflects prolonged occupancy of the receptor by slowly reversible antagonists.

The protective effects of ascorbic acid, cimetidine, and nifedipine on diethyldithiocarbamate-induced hepatic toxicity in albino rats.

PubMed

Gaafa, Khadiga Mohammed; Badawy, Mohammed M; Hamza, Alaaeldin A

2011-10-01

The aim of the present work was to clarify the involvement of free radicals, cytochrome P450 toxic metabolites, and deregulation of calcium homeostasis in the mechanism of diethyldithiocarbamate (DDC) hepatotoxicity. This was elucidated through the preadministration of ascorbic acid (a free radical scavenger), cimetidine (an inhibitor of cytochrome P450 enzymes), or nifedipine (a calcium-blocking agent) before DDC treatment to male albino rats. DDC was administered either as a single dose [800 mg/kg body weight (b.w.), subcutaneously, s.c.] or daily repeated doses for 30 days (400 mg/kg b.w., s.c.). Oxidative stress indicators [e.g., malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase enzyme (SOD)] showed that single or repeated DDC doses induce an increase in MDA level and a decrease in SOD activity in the liver, whereas it causes depletion in hepatic GSH after a single dose and an elevation in its value after repeated doses. Severe histopathological changes were also observed in the livers of rats treated with single or repeated DDC doses. Ascorbic acid, cimetidine, and nifedipine pretreatments were found to induce highly protective effects against the evinced DDC hepatotoxicity, manifesting that free radical, cytochrome P450, and calcium-dependent processes contribute to DDC liver toxicity. Finally, although multiple mechanisms may be involved in the hepatotoxic changes induced by DDC, calcium disarrangement and free radical formation play a more critical role than cytochrome P450 in metabolic events leading to toxic effects of DDC.

Design and Synthesis of Benzimidazoles As Novel Corticotropin-Releasing Factor 1 Receptor Antagonists.

PubMed

Mochizuki, Michiyo; Kori, Masakuni; Kobayashi, Katsumi; Yano, Takahiko; Sako, Yuu; Tanaka, Maiko; Kanzaki, Naoyuki; Gyorkos, Albert C; Corrette, Christopher P; Cho, Suk Young; Pratt, Scott A; Aso, Kazuyoshi

2016-03-24

Benzazole derivatives with a flexible aryl group bonded through a one-atom linker as a new scaffold for a corticotropin-releasing factor 1 (CRF1) receptor antagonist were designed, synthesized, and evaluated. We expected that structural diversity could be expanded beyond that of reported CRF1 receptor antagonists. In a structure-activity relationship study, 4-chloro-N(2)-(4-chloro-2-methoxy-6-methylphenyl)-1-methyl-N(7),N(7)-dipropyl-1H-benzimidazole-2,7-diamine 29g had the most potent binding activity against a human CRF1 receptor and the antagonistic activity (IC50 = 9.5 and 88 nM, respectively) without concerns regarding cytotoxicity at 30 μM. Potent CRF1 receptor-binding activity in brain in an ex vivo test and suppression of stress-induced activation of the hypothalamus-pituitary-adrenocortical (HPA) axis were also observed at 138 μmol/kg of compound 29g after oral administration in mice. Thus, the newly designed benzimidazole 29g showed in vivo CRF1 receptor antagonistic activity and good brain penetration, indicating that it is a promising lead for CRF1 receptor antagonist drug discovery research.

Transcription of the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase type 3 gene, ATP2A3, is regulated by the calcineurin/NFAT pathway in endothelial cells

PubMed Central

Hadri, Lahouaria; Pavoine, Catherine; Lipskaia, Larissa; Yacoubi, Sabrina; Lompré, Anne-Marie

2005-01-01

Histamine, known to induce Ca2+ oscillations in endothelial cells, was used to alter Ca2+ cycling. Treatment of HUVEC (human umbilical-vein endothelial cell)-derived EA.hy926 cells with histamine for 1–3 days increased the levels of SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) 3, but not of SERCA 2b, transcripts and proteins. Promoter-reporter gene assays demonstrated that this increase in expression was due to activation of SERCA 3 gene transcription. The effect of histamine was abolished by mepyramine, but not by cimetidine, indicating that the H1 receptor, but not the H2 receptor, was involved. The histamine-induced up-regulation of SERCA 3 was abolished by cyclosporin A and by VIVIT, a peptide that prevents calcineurin and NFAT (nuclear factor of activated T-cells) from interacting, indicating involvement of the calcineurin/NFAT pathway. Histamine also induced the nuclear translocation of NFAT. NFAT did not directly bind to the SERCA 3 promoter, but activated Ets-1 (E twenty-six-1), which drives the expression of the SERCA 3 gene. Finally, cells treated with histamine and loaded with fura 2 exhibited an improved capacity in eliminating high cytosolic Ca2+ concentrations, in accordance with an increase in activity of a low-affinity Ca2+-ATPase, like SERCA 3. Thus chronic treatment of endothelial cells with histamine up-regulates SERCA 3 transcription. The effect of histamine is mediated by the H1R (histamine 1 receptor) and involves activation of the calcineurin/NFAT pathway. By increasing the rate of Ca2+ sequestration, up-regulation of SERCA 3 counteracts the cytosolic increase in Ca2+ concentration. PMID:16250893

The EED protein–protein interaction inhibitor A-395 inactivates the PRC2 complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Yupeng; Selvaraju, Sujatha; Curtin, Michael L.

Polycomb repressive complex 2 (PRC2) is a regulator of epigenetic states required for development and homeostasis. PRC2 trimethylates histone H3 at lysine 27 (H3K27me3), which leads to gene silencing, and is dysregulated in many cancers. The embryonic ectoderm development (EED) protein is an essential subunit of PRC2 that has both a scaffolding function and an H3K27me3-binding function. Here we report the identification of A-395, a potent antagonist of the H3K27me3 binding functions of EED. Structural studies demonstrate that A-395 binds to EED in the H3K27me3-binding pocket, thereby preventing allosteric activation of the catalytic activity of PRC2. Phenotypic effects observed inmore » vitro and in vivo are similar to those of known PRC2 enzymatic inhibitors; however, A-395 retains potent activity against cell lines resistant to the catalytic inhibitors. A-395 represents a first-in-class antagonist of PRC2 protein–protein interactions (PPI) for use as a chemical probe to investigate the roles of EED-containing protein complexes.« less

The EED protein-protein interaction inhibitor A-395 inactivates the PRC2 complex.

PubMed

He, Yupeng; Selvaraju, Sujatha; Curtin, Michael L; Jakob, Clarissa G; Zhu, Haizhong; Comess, Kenneth M; Shaw, Bailin; The, Juliana; Lima-Fernandes, Evelyne; Szewczyk, Magdalena M; Cheng, Dong; Klinge, Kelly L; Li, Huan-Qiu; Pliushchev, Marina; Algire, Mikkel A; Maag, David; Guo, Jun; Dietrich, Justin; Panchal, Sanjay C; Petros, Andrew M; Sweis, Ramzi F; Torrent, Maricel; Bigelow, Lance J; Senisterra, Guillermo; Li, Fengling; Kennedy, Steven; Wu, Qin; Osterling, Donald J; Lindley, David J; Gao, Wenqing; Galasinski, Scott; Barsyte-Lovejoy, Dalia; Vedadi, Masoud; Buchanan, Fritz G; Arrowsmith, Cheryl H; Chiang, Gary G; Sun, Chaohong; Pappano, William N

2017-04-01

Polycomb repressive complex 2 (PRC2) is a regulator of epigenetic states required for development and homeostasis. PRC2 trimethylates histone H3 at lysine 27 (H3K27me3), which leads to gene silencing, and is dysregulated in many cancers. The embryonic ectoderm development (EED) protein is an essential subunit of PRC2 that has both a scaffolding function and an H3K27me3-binding function. Here we report the identification of A-395, a potent antagonist of the H3K27me3 binding functions of EED. Structural studies demonstrate that A-395 binds to EED in the H3K27me3-binding pocket, thereby preventing allosteric activation of the catalytic activity of PRC2. Phenotypic effects observed in vitro and in vivo are similar to those of known PRC2 enzymatic inhibitors; however, A-395 retains potent activity against cell lines resistant to the catalytic inhibitors. A-395 represents a first-in-class antagonist of PRC2 protein-protein interactions (PPI) for use as a chemical probe to investigate the roles of EED-containing protein complexes.

Potent and selective CC chemokine receptor 1 antagonists labeled with carbon-13, carbon-14, and tritium.

PubMed

Latli, Bachir; Hrapchak, Matt; Cheveliakov, Maxim; Reeves, Jonathan T; Marsini, Maurice; Busacca, Carl A; Senanayake, Chris H

2018-05-15

1-(4-Fluorophenyl)-1H-pyrazolo[3,4-c]pyridine-4-carboxylic acid (2-methanesulfonyl-pyridin-4-ylmethyl)-amide (1) and its analogs (2) and (3) are potent CCR1 antagonists intended for the treatment of rheumatoid arthritis. The detailed syntheses of these 3 compounds labeled with carbon-13 as well as the preparation of (1) and (2) labeled with carbon-14, and (1) labeled with tritium, are described. Copyright © 2018 John Wiley & Sons, Ltd.

Engineering endomorphin drugs: state of the art

PubMed Central

Lazarus, Lawrence H; Okada, Yoshio

2011-01-01

Importance of the field Although EM-1 (H-Tyr-Pro-Phe-Trp-NH2) and EM-2 (H-Tyr-Pro-Phe-Phe-NH2) are primarily considered agonists for the μ-opioid receptor (MOR), systematic alterations to specific residues provided antagonists and ligands with mixed μ/δ-opioid properties suitable for application to health related topics. Areas covered in this review This review attempts to succinctly provide insight on the development and bioactivity of endomorphin analogues during the past decade. Rational design approaches will focus on the engineering of endomorphin agonists, antagonists and mixed ligands for their application as a multi-target ligand. What the reader will gain While the application of endomorphins as antinociceptive agents and numerous biological endpoints were experimental delineated in laboratory animals and in vitro, clinical use is currently absent. However, structural alterations provide enhanced stability, formation of MOR antagonists or mixed and dual μ/δ-acting ligands could find considerable therapeutic potential. Take home message Aside from alleviating pain, EM analogues open new horizons in the treatment of medical syndromes involving neural reward mechanisms and extraneural regulation effects on homeostasis. Highly selective MOR antagonists may be promising to reduce inflammation, attenuate addiction to drugs and excess consumption of high caloric food, ameliorate alcoholism, affect the immune system and combat opioid bowel dysfunction. PMID:22214283

Design of novel neurokinin 1 receptor antagonists based on conformationally constrained aromatic amino acids and discovery of a potent chimeric opioid agonist-neurokinin 1 receptor antagonist

PubMed Central

Ballet, Steven; Feytens, Debby; Buysse, Koen; Chung, Nga N.; Lemieux, Carole; Tumati, Suneeta; Keresztes, Attila; Van Duppen, Joost; Lai, Josephine; Varga, Eva; Porreca, Frank; Schiller, Peter W.; Broeck, Jozef Vanden; Tourwé, Dirk

2011-01-01

A screening of conformationally constrained aromatic amino acids as base cores for the preparation of new NK1 receptor antagonists resulted in the discovery of three new NK1 receptor antagonists, 19 [Ac-Aba-Gly-NH-3′,5′-(CF3)2-Bn], 20 [Ac-Aba-Gly-NMe-3′,5′-(CF3)2-Bn] and 23 [Ac-Tic-NMe-3′,5′-(CF3)2-Bn], which were able to counteract the agonist effect of substance P, the endogenous ligand of NK1R. The most active NK1 antagonist of the series, 20 [Ac-Aba-Gly-NMe-3′,5′-(CF3)2-Bn], was then used in the design of a novel, potent chimeric opioid agonist-NK1 receptor antagonist, 35 [Dmt-D-Arg-Aba-Gly-NMe-3′,5′-(CF3)2-Bn], which combines the N-terminus of the established Dmt1-DALDA agonist opioid pharmacophore (H-Dmt-D-Arg-Phe-Lys-NH2) and 20, the NK1R ligand. The opioid component of the chimeric compound 35, i.e. Dmt-D-Arg-Aba-Gly-NH2 36, also proved to be an extremely potent and balanced μ- and δ opioid receptor agonist with subnanomolar binding and in vitro functional activity. PMID:21413804

Effects of the NMDA receptor antagonist, D-CPPene, on sensitization to the operant decrement produced by naloxone in morphine-treated rats.

PubMed

Bespalov, A Y; Medvedev, I O; Sukhotina, I A; Zvartau, E E

2001-04-01

Sensitization to the rate-decreasing effects of opioid antagonists induced by acute pretreatment with opioid agonists has been suggested to reflect initial changes in opioid systems that underlie physical dependence. Glutamate receptors are implicated in the development and expression of opioid dependence, and antagonists acting at the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors have been shown repeatedly to attenuate the severity of opioid withdrawal. The present study evaluated the ability of a competitive NMDA receptor antagonist, D-CPPene (SDZ EAA 494; 3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid), to affect morphine-induced sensitization to naloxone in rats trained to lever-press on a multiple-trial, fixed-ratio 10 schedule of food reinforcement. D-CPPene (0.3-3 mg/kg) was administered either 4 h or 30 min prior to the test session. Morphine (10 mg/kg) or its vehicle was administered 4 h before naloxone challenge (0.3-3 mg/kg). D-CPPene failed to prevent morphine-induced potentiation of the naloxone-produced decrement in operant performance. Thus, these results suggest that agonist-induced sensitization to behavioral effects of opioid antagonists may be insensitive to NMDA receptor blockade.

Inhibition of partially purified K+/H+-ATPase from guinea-pig isolated and enriched parietal cells by substituted benzimidazoles.

PubMed Central

Beil, W.; Sewing, K. F.

1984-01-01

The cellular and subcellular distributions of adenosinetriphosphatases (ATPases) were examined in guinea-pig gastric mucosal cells. All cell types displayed Mg2+-ATPase and bicarbonate (HCO3-)-stimulated ATPase activity. K+-ATPase was located only in fractions derived from parietal cells. Differential and density-gradient centrifugation of material prepared from parietal cells revealed that K+-ATPase activity was located in a tubulo-vesicular membrane fraction. Enzyme activity was ten fold greater in this fraction than in a crude parietal cell homogenate. The substituted benzimidazoles, omeprazole and picoprazole, inhibited K+-ATPase (IC50 1.8 +/- 0.5 mumol l-1 and 3.1 +/- 0.4 mumol l-1, respectively). Detailed kinetic analysis indicated that these compounds were non-competitive and reversible inhibitors of the enzyme. In contrast cimetidine and verapamil were without effect on the enzyme. The relevance of the inhibition of K+-ATPase to the antisecretory activity of the benzimidazoles, in experimental animals and man, is discussed. PMID:6146367

The effects of endomorphins on striatal [3H]GABA release induced by electrical stimulation: an in vitro superfusion study in rats.

PubMed

Bagosi, Zsolt; Jászberényi, Miklós; Telegdy, Gyula

2009-05-01

The endomorphins (EM1 and EM2) are selective endogenous ligands for mu-opioid receptors (MOR1 and MOR2) with neurotransmitter and neuromodulator roles in mammals. In the present study we investigated the potential actions of EMs on striatal GABA release and the implication of different MORs in these processes. Rat striatal slices were preincubated with tritium-labelled GABA ([(3)H]GABA), pretreated with selective MOR1 and MOR2 antagonist beta-funaltrexamine and selective MOR1 antagonist naloxonazine and then superfused with the selective MOR agonists, EM1 and EM2. EM1 significantly decreased the striatal [(3)H]GABA release induced by electrical stimulation. Beta-funaltrexamine antagonized the inhibitory action of EM1, but naloxonazine did not affect it considerably. EM2 was ineffective, even in case of specific enzyme inhibitor diprotin A pretreatment. The results demonstrate that EM1 decreases GABA release in the basal ganglia through MOR2, while EM2 does not influence it.

Effects of melanocortin-4 receptor agonists and antagonists on expression of genes related to reproduction in spotted scat, Scatophagus argus.

PubMed

Jiang, Dong-Neng; Li, Jian-Tao; Tao, Ya-Xiong; Chen, Hua-Pu; Deng, Si-Ping; Zhu, Chun-Hua; Li, Guang-Li

2017-05-01

Melanocortin-4 receptor (Mc4r) function related to reproduction in fish has not been extensively investigated. Here, we report on gene expression changes by real-time PCR following treatment with Mc4r agonists and antagonists in the spotted scat (Scatophagus argus). Using in vitro incubated hypothalamus, the Mc4r nonselective agonist NDP-MSH ([Nle 4 , D-Phe 7 ]-α-melanocyte stimulating hormone; 10 -6 M) and selective agonist THIQ (N-[(3R)-1, 2, 3, 4-Tetrahydroisoquinolinium-3-ylcarbonyl]- (1R)-1-(4-chlorobenzyl)-2-[4-cyclohexyl-4-(1H-1,2,4-triazol-1-ylmethyl) piperidin-1-yl]-2-oxoethylamine; 10 -7 M) significantly increased the expression of gnrh (Gonadotropin releasing hormone), while the Mc4r nonselective antagonist SHU9119 (Ac-Nle-[Asp-His-DPhe/DNal(2')-Arg-Trp-Lys]-NH2; 10 -6 M) and selective antagonist Ipsen 5i (compound 5i synthesized in Ipsen Research Laboratories; 10 -6 M) significantly inhibited gnrh expression after 3 h of incubation. In incubated pituitary tissue, NDP-MSH and THIQ significantly increased the expression of fshb (Follicle-stimulating hormone beta subunit) and lhb (Luteinizing hormone beta subunit), while SHU9119 and Ipsen 5i significantly decreased fshb and lhb expression after 3 h of incubation. During the in vivo experiment, THIQ (1 mg/kg bw) significantly increased gnrh expression in hypothalamic tissue, as well as the fshb and lhb expression in pituitary tissue 12 h after abdominal injection. Furthermore, Ipsen 5i (1 mg/kg bw) significantly inhibited gnrh expression in hypothalamic tissue, as well as fshb and lhb gene expression in pituitary tissue 12 h after abdominal injection. In summary, Mc4r singling appears to stimulate gnrh expression in the hypothalamus, thereby modulating the synthesis of Fsh and Lh in the pituitary. In addition, Mc4r also appears to directly regulate fshb and lhb levels in the pituitary in spotted scat. Our study suggests that Mc4r, through the hypothalamus and pituitary, participates in reproductive regulation in fish.

Amine dependence of proliferative activity in two transplantable lines of mouse colonic carcinoma.

PubMed

Tutton, P J; Barkla, D H

1987-01-01

Serotonin, histamine and their antagonists have previously been shown to influence both the cell proliferation rate and the volumetric growth rate of colonic tumours. Of these earlier studies, those on cell proliferation could not distinguish between direct effects on tumour cells and indirect effects on the host, whereas those on the volumetric growth rate of tumours, whilst suggesting an outcome related to the individual properties of the tumour rather than the host, could not distinguish between influences on cell gain, cell loss or stromal changes. In an attempt to distinguish between these possibilities the current experiments on the mitotic rate in two lines of transplantable mouse colonic carcinoma were undertaken. One line of tumour proved to be sensitive to inhibition by a histamine H2 receptor antagonist and a dopamine D2 antagonist but resistant to serotonin antagonists; the inhibition by histamine antagonists was surmountable by co-administration of histamine. The other line proved to be highly sensitive to the inhibitory effects of serotonin antagonist and less so to antagonists of the other two amines and in this case the effect of serotonin antagonists was surmountable by serotonin. These results suggest that the variations between different colonic tumours in the response to amine antagonists is due to differences in the extent of inhibition of cell proliferation rather than differences in cell loss or stromal effects. Thus it appears likely that amine antagonists are able to directly interfere with the proliferation of some colonic tumour cells.

Androgen Receptor Antagonists and Anti-Prostate Cancer Activities of Some Newly Synthesized Substituted Fused Pyrazolo-, Triazolo- and Thiazolo-Pyrimidine Derivatives

PubMed Central

Bahashwan, Saleh A.; Fayed, Ahmed A.; Ramadan, Mohamed A.; Amr, Abd El-Galil E.; Al-Harbi, Naif O.

2014-01-01

A series of substituted pyrazole, triazole and thiazole derivatives (2–13) were synthesized from 1-(naphtho[1,2-d]thiazol-2-yl)hydrazine as starting material and evaluated as androgen receptor antagonists and anti-prostate cancer agents. The newly synthesized compounds showed potent androgen receptor antagonists and anti-prostate cancer activities with low toxicity (lethal dose 50 (LD50)) comparable to Bicalutamide as reference drug. The structures of newly synthesized compounds were confirmed by IR, 1H-NMR, 13C-NMR, and MS spectral data and elemental analysis. The detailed synthesis, spectroscopic data, LD50 values and pharmacological activities of the synthesized compounds are reported. PMID:25421248

Ticlopidine

MedlinePlus

... a stroke and who cannot be treated with aspirin. Ticlopidine is also used along with aspirin to prevent blood clots from forming in coronary ... antacids, anticoagulants ('blood thinners') such as warfarin (Coumadin), aspirin, cimetidine (Tagamet), clopidogrel (Plavix), digoxin (Lanoxin), and theophylline ( ...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkes, J.M.; Kajimura, M.; Scott, D.R.

Isolated rabbit gastric glands were used to study the nature of the muscarinic cholinergic responses of parietal cells. Carbachol stimulation of acid secretion, as measured by the accumulation of aminopyrine, was inhibited by the M1 antagonist, pirenzepine, with an IC50 of 13 microM; by the M2 antagonist, 11,2-(diethylamino)methyl-1 piperidinyl acetyl-5,11-dihydro-6H-pyrido 2,3-b 1,4 benzodiazepin-6-one (AF-DX 116), with an IC50 of 110 microM; and by the M1/M3 antagonist, diphenyl-acetoxy-4-methylpiperidinemethiodide, with an IC50 of 35 nM. The three antagonists displayed equivalent IC50 values for the inhibition of carbachol-stimulated production of 14CO2 from radiolabeled glucose, which is a measure of the turnover of themore » H,K-ATPase, the final step of acid secretion. Intracellular calcium levels were measured in gastric glands loaded with FURA 2. Carbachol was shown to both release calcium from an intracellular pool and to promote calcium entry across the plasma membrane. The calcium entry was inhibitable by 20 microM La3+. The relative potency of the three muscarinic antagonists for inhibition of calcium entry was essentially the same as for inhibition of acid secretion or pump related glucose oxidation. Image analysis of the glands showed the effects of carbachol, and of the antagonists, on intracellular calcium were occurring largely in the parietal cell. The rise in cell calcium due to release of calcium from intracellular stores was inhibited by 4-DAMP with an IC50 of 1.7 nM, suggesting that the release pathway was regulated by a low affinity M3 muscarinic receptor or state; Ca entry and acid secretion are regulated by a high affinity M3 muscarinic receptor or state, inhibited by higher 4-DAMP concentrations, suggesting that it is the steady-state elevation of Ca that is related to parietal cell function rather than the (Ca)i transient.« less

Discovery and characterization of ACT-335827, an orally available, brain penetrant orexin receptor type 1 selective antagonist.

PubMed

Steiner, Michel A; Gatfield, John; Brisbare-Roch, Catherine; Dietrich, Hendrik; Treiber, Alexander; Jenck, Francois; Boss, Christoph

2013-06-01

Stress relief: Orexin neuropeptides regulate arousal and stress processing through orexin receptor type 1 (OXR-1) and 2 (OXR-2) signaling. A selective OXR-1 antagonist, represented by a phenylglycine-amide substituted tetrahydropapaverine derivative (ACT-335827), is described that is orally available, penetrates the brain, and decreases fear, compulsive behaviors and autonomic stress reactions in rats. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a Rapid Throughput Assay for Identification of hNav1.7 Antagonist Using Unique Efficacious Sodium Channel Agonist, Antillatoxin.

PubMed

Zhao, Fang; Li, Xichun; Jin, Liang; Zhang, Fan; Inoue, Masayuki; Yu, Boyang; Cao, Zhengyu

2016-02-16

Voltage-gated sodium channels (VGSCs) are responsible for the generation of the action potential. Among nine classified VGSC subtypes (Nav1.1-Nav1.9), Nav1.7 is primarily expressed in the sensory neurons, contributing to the nociception transmission. Therefore Nav1.7 becomes a promising target for analgesic drug development. In this study, we compared the influence of an array of VGSC agonists including veratridine, BmK NT1, brevetoxin-2, deltamethrin and antillatoxin (ATX) on membrane depolarization which was detected by Fluorescence Imaging Plate Reader (FLIPR) membrane potential (FMP) blue dye. In HEK-293 cells heterologously expressing hNav1.7 α-subunit, ATX produced a robust membrane depolarization with an EC50 value of 7.8 ± 2.9 nM whereas veratridine, BmK NT1, and deltamethrin produced marginal response. Brevetoxin-2 was without effect on membrane potential change. The ATX response was completely inhibited by tetrodotoxin suggesting that the ATX response was solely derived from hNav1.7 activation, which was consistent with the results where ATX produced a negligible response in null HEK-293 cells. Six VGSC antagonists including lidocaine, lamotrigine, phenytoin, carbamazepine, riluzole, and 2-amino-6-trifluoromethylthiobenzothiazole all concentration-dependently inhibited ATX response with IC50 values comparable to that reported from patch-clamp experiments. Considered together, we demonstrate that ATX is a unique efficacious hNav1.7 activator which offers a useful probe to develop a rapid throughput screening assay to identify hNav1.7 antagonists.

Development of a Rapid Throughput Assay for Identification of hNav1.7 Antagonist Using Unique Efficacious Sodium Channel Agonist, Antillatoxin

PubMed Central

Zhao, Fang; Li, Xichun; Jin, Liang; Zhang, Fan; Inoue, Masayuki; Yu, Boyang; Cao, Zhengyu

2016-01-01

Voltage-gated sodium channels (VGSCs) are responsible for the generation of the action potential. Among nine classified VGSC subtypes (Nav1.1–Nav1.9), Nav1.7 is primarily expressed in the sensory neurons, contributing to the nociception transmission. Therefore Nav1.7 becomes a promising target for analgesic drug development. In this study, we compared the influence of an array of VGSC agonists including veratridine, BmK NT1, brevetoxin-2, deltamethrin and antillatoxin (ATX) on membrane depolarization which was detected by Fluorescence Imaging Plate Reader (FLIPR) membrane potential (FMP) blue dye. In HEK-293 cells heterologously expressing hNav1.7 α-subunit, ATX produced a robust membrane depolarization with an EC50 value of 7.8 ± 2.9 nM whereas veratridine, BmK NT1, and deltamethrin produced marginal response. Brevetoxin-2 was without effect on membrane potential change. The ATX response was completely inhibited by tetrodotoxin suggesting that the ATX response was solely derived from hNav1.7 activation, which was consistent with the results where ATX produced a negligible response in null HEK-293 cells. Six VGSC antagonists including lidocaine, lamotrigine, phenytoin, carbamazepine, riluzole, and 2-amino-6-trifluoromethylthiobenzothiazole all concentration-dependently inhibited ATX response with IC50 values comparable to that reported from patch-clamp experiments. Considered together, we demonstrate that ATX is a unique efficacious hNav1.7 activator which offers a useful probe to develop a rapid throughput screening assay to identify hNav1.7 antagonists. PMID:26891306

Down-regulation of pituitary receptors for luteinizing hormone-releasing hormone (LH-RH) in rats by LH-RH antagonist Cetrorelix.

PubMed Central

Halmos, G; Schally, A V; Pinski, J; Vadillo-Buenfil, M; Groot, K

1996-01-01

Antagonists of luteinizing hormone-releasing hormone (LH-RH), unlike the LH-RH agonists, suppress gonadotropins and sex steroid secretion immediately after administration, without initial stimulatory effects. [Ac-D-Nal(2)1,D-Ph(4Cl)2,D-Pal(3)3,D-Cit6,D-Ala10]LH-R H (SB-75; Cetrorelix) is a modern, potent antagonistic analog of LH-RH. In this study, the binding characteristics of receptors for LH-RH in membrane fractions from rat anterior pituitaries were investigated after a single injection of Cetrorelix at a dose of 100 microg per rat. To determine whether the treatment with Cetrorelix can affect the concentration of measurable LH-RH binding sites, we applied an in vitro method to desaturate LH-RH receptors by chaotropic agents such as manganous chloride (MnCl2) and ammonium thiocyanate (NH4SCN). Our results show that the percentages of occupied LH-RH receptors at 1, 3, and 6 h after administration of Cetrorelix were approximately 28%, 14%, and 10%, respectively, of total receptors. At later time intervals, we could not detect occupied LH-RH binding sites. Ligand competition assays, following in vitro desaturation, demonstrated that rat pituitary LH-RH receptors were significantly (P < 0.01) down-regulated for at least 72 h after administration of Cetrorelix. The lowest receptor concentration was found 3-6 h after Cetrorelix treatment and a recovery in receptor number began within approximately 24 h. The down-regulation of LH-RH binding sites induced by Cetrorelix was accompanied by serum LH and testosterone suppression. Higher LH-RH receptor concentrations coincided with elevated serum hormone levels at later time intervals. Our results indicate that administration of LH-RH antagonist Cetrorelix produces a marked down-regulation of pituitary receptors for LH-RH and not merely an occupancy of binding sites. PMID:8637885

Design and synthesis of novel sulfonamide-containing bradykinin hB2 receptor antagonists. 2. Synthesis and structure-activity relationships of alpha,alpha-cycloalkylglycine sulfonamides.

PubMed

Fattori, Daniela; Rossi, Cristina; Fincham, Christopher I; Caciagli, Valerio; Catrambone, Fernando; D'Andrea, Piero; Felicetti, Patrizia; Gensini, Martina; Marastoni, Elena; Nannicini, Rossano; Paris, Marielle; Terracciano, Rosa; Bressan, Alessandro; Giuliani, Sandro; Maggi, Carlo A; Meini, Stefania; Valenti, Claudio; Quartara, Laura

2007-02-08

Recently we reported on the design and synthesis of a novel class of selective nonpeptide bradykinin (BK) B2 receptor antagonists (J. Med. Chem. 2006, 3602-3613). This work led to the discovery of MEN 15442, an antagonist with subnanomolar affinity for the human B2 receptor (hB2R), which also displayed significant and prolonged activity in vivo (for up to 210 min) against BK-induced bronchoconstriction in the guinea-pig at a dose of 300 nmol/kg (it), while demonstrating only a slight effect on BK-induced hypotension. Here we describe the further optimization of this series of compounds aimed at maximizing the effect on bronchoconstriction and minimizing the effect on hypotension, with a view to developing topically delivered drugs for airway diseases. The work led to the discovery of MEN 16132, a compound which, after intratracheal or aerosol administration, inhibited, in a dose-dependent manner, BK-induced bronchoconstricton in the airways, while showing minimal systemic activity. This compound was selected as a preclinical candidate for the topical treatment of airway diseases involving kinin B2 receptor stimulation.

Novel quinolinone-phosphonic acid AMPA antagonists devoid of nephrotoxicity.

PubMed

Cordi, Alex A; Desos, Patrice; Ruano, Elisabeth; Al-Badri, Hashim; Fugier, Claude; Chapman, Astrid G; Meldrum, Brian S; Thomas, Jean-Yves; Roger, Anita; Lestage, Pierre

2002-10-01

We reported previously the synthesis and structure-activity relationships (SAR) in a series of 2-(1H)-oxoquinolines bearing different acidic functions in the 3-position. Exploiting these SAR, we were able to identify 6,7-dichloro-2-(1H)-oxoquinoline-3-phosphonic acid compound 3 (S 17625) as a potent, in vivo active AMPA antagonist. Unfortunately, during the course of the development, nephrotoxicity was manifest at therapeutically effective doses. Considering that some similitude exists between S 17625 and probenecid, a compound known to protect against the nephrotoxicity and/or slow the clearance of different drugs, we decided to synthesise some new analogues of S 17625 incorporating some of the salient features of probenecid. Replacement of the chlorine in position 6 by a sulfonylamine led to very potent AMPA antagonists endowed with good in vivo activity and lacking nephrotoxicity potential. Amongst the compounds evaluated, derivatives 7a and 7s appear to be the most promising and are currently evaluated in therapeutically relevant stroke models.

Novel 5-HT6 receptor antagonists/D2 receptor partial agonists targeting behavioral and psychological symptoms of dementia.

PubMed

Kołaczkowski, Marcin; Marcinkowska, Monika; Bucki, Adam; Śniecikowska, Joanna; Pawłowski, Maciej; Kazek, Grzegorz; Siwek, Agata; Jastrzębska-Więsek, Magdalena; Partyka, Anna; Wasik, Anna; Wesołowska, Anna; Mierzejewski, Paweł; Bienkowski, Przemyslaw

2015-03-06

We describe a novel class of designed multiple ligands (DMLs) combining serotonin 5-HT6 receptor (5-HT6R) antagonism with dopamine D2 receptor (D2R) partial agonism. Prototype hybrid molecules were designed using docking to receptor homology models. Diverse pharmacophore moieties yielded 3 series of hybrids with varying in vitro properties at 5-HT6R and D2R, and at M1 receptor and hERG channel antitargets. 4-(piperazin-1-yl)-1H-indole derivatives showed highest antagonist potency at 5-HT6R, with 7-butoxy-3,4-dihydroquinolin-2(1H)-one and 2-propoxybenzamide derivatives having promising D2R partial agonism. 2-(3-(4-(1-(phenylsulfonyl)-1H-indol-4-yl)piperazin-1-yl)propoxy)benzamide (47) exhibited nanomolar affinity at both 5-HT6R and D2R and was evaluated in rat models. It displayed potent antidepressant-like and anxiolytic-like activity in the Porsolt and Vogel tests, respectively, more pronounced than that of a reference selective 5-HT6R antagonist or D2R partial agonist. In addition, 47 also showed antidepressant-like activity (Porsolt's test) and anxiolytic-like activity (open field test) in aged (>18-month old) rats. In operant conditioning tests, 47 enhanced responding for sweet reward in the saccharin self-administration test, consistent with anti-anhedonic properties. Further, 47 facilitated extinction of non-reinforced responding for sweet reward, suggesting potential procognitive activity. Taken together, these studies suggest that DMLs combining 5-HT6R antagonism and D2R partial agonism may successfully target affective disorders in patients from different age groups without a risk of cognitive deficits. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Circadian-dependent effect of melatonin on dopaminergic D2 antagonist-induced hypokinesia and agonist-induced stereotypies in rats.

PubMed

Sumaya, I C; Byers, D M; Irwin, L N; Del Val, S; Moss, D E

2004-08-01

Although a melatonin/dopamine relationship has been well established in nonmotor systems wherein dopamine and melatonin share an antagonist relationship, less clear is the role melatonin may play in extrapyramidal dopaminergic function. Therefore, the purpose of the present experiments was to examine the relationship between melatonin and the dopaminergic D2 receptor system and behavior. Hypokinesia was induced in male Sprague-Dawley rats with fluphenazine (D2 antagonist, 0.4 mg/kg ip) and stereotypies with apomorphine (D2 agonist, 0.6 mg/kg sc) during the light (1200 h) and dark (2200 h) phases. As expected, fluphenazine induced severe hypokinesia during the light phase (482 +/- 176 s); however, unexpectedly, fluphenazine-induced hypokinesia during the dark was almost nonexistent (25 +/- 6 s). Furthermore, melatonin treatment (30 mg/kg ip) produced a strong interaction with fluphenazine in that it reduced fluphenazine-induced hypokinesia by nearly 80% in the light (112 +/- 45 s) but paradoxically increased the minimal fluphenazine-induced hypokinesia in the dark by more than 60% (70 +/- 17 s). Melatonin also reduced apomorphine-induced stereotypies by nearly 40% in the light but had no effect in the dark. Taken together, these data show (1) a strong and unexpected nocturnal effect of fluphenazine on hypokinesia and (2) provide support for an antagonistic melatonin/dopaminergic interaction in the context of motor behavior and D2 receptor function which appears to be critically dependent on the light/dark status of the dopaminergic system. Copyright 2004 Elsevier Inc.

Structure-based virtual screening and characterization of a novel IL-6 antagonistic compound from synthetic compound database.

PubMed

Wang, Jing; Qiao, Chunxia; Xiao, He; Lin, Zhou; Li, Yan; Zhang, Jiyan; Shen, Beifen; Fu, Tinghuan; Feng, Jiannan

2016-01-01

According to the three-dimensional (3D) complex structure of (hIL-6⋅hIL-6R⋅gp 130) 2 and the binding orientation of hIL-6, three compounds with high affinity to hIL-6R and bioactivity to block hIL-6 in vitro were screened theoretically from the chemical databases, including 3D-Available Chemicals Directory (ACD) and MDL Drug Data Report (MDDR), by means of the computer-guided virtual screening method. Using distance geometry, molecular modeling and molecular dynamics trajectory analysis methods, the binding mode and binding energy of the three compounds were evaluated theoretically. Enzyme-linked immunosorbent assay analysis demonstrated that all the three compounds could block IL-6 binding to IL-6R specifically. However, only compound 1 could effectively antagonize the function of hIL-6 and inhibit the proliferation of XG-7 cells in a dose-dependent manner, whereas it showed no cytotoxicity to SP2/0 or L929 cells. These data demonstrated that the compound 1 could be a promising candidate of hIL-6 antagonist.

The comparision of effect of microdose GnRH-a flare-up, GnRH antagonist/aromatase inhibitor letrozole and GnRH antagonist/clomiphene citrate protocols on IVF outcomes in poor responder patients.

PubMed

Ozcan Cenksoy, Pinar; Ficicioglu, Cem; Kizilkale, Ozge; Suhha Bostanci, Mehmet; Bakacak, Murat; Yesiladali, Mert; Kaspar, Cigdem

2014-07-01

To compare the effects of microdose GnRH-a flare-up, GnRH antagonist/aromatase inhibitor letrozole and GnRH antagonist/clomiphene citrate protocols on IVF outcomes in poor responder patients. Of 225 patients, 83 patients were in microdose flare-up group (Group 1), 70 patients were in GnRH antagonist/letrozole group (Group 2) and 72 patients were in GnRH antagonist/clomiphene citrate group (Group 3). Demographic and endocrine characteristics, the total number of oocytes retrieved, cancellation rate and clinical pregnancy rate were collected Results: Total dosage of gonadotropins (p=0.002) and serum E2 levels on the day of hCG administration (p=0.010) were significantly higher and duration of stimulations (p=0.03) was significantly longer in group 1. The number of oocytes retrieved was significantly greater in group 1 and 2 when compare to those of group 3 (p=0,000). There was a trend towards increasing cycle cancellation rates with GnRH antagonist/clomiphene citrate and GnRH antagonist/letrozole. Our finding suggest that the results of microdose flare-up protocol are better than other two used treatment protocols, in terms of maximum estradiol levels, number of mature oocytes retrieved, and cancellation rate and it still seems to be superior the ovarian stimulation regime for the poor responder patients.

New H1/H3 antagonists for treating allergic rhinitis: WO2010094643.

PubMed

Norman, Peter

2011-03-01

This application claims dual receptor specificity antihistamines, active as H(1) and H(3) antagonists, which additionally have a long duration of action that renders them suitable for once daily administration via inhalation for the treatment of allergic rhinitis. The compounds lack CNS penetration and have a high affinity for both histamine receptors.

Pharmacological characterization of the cysteinyl-leukotriene antagonists CGP 45715A (iralukast) and CGP 57698 in human airways in vitro

PubMed Central

Capra, Valérie; Bolla, Manlio; Angelo Belloni, Pier; Mezzetti, Maurizio; Carlo Folco, G; Nicosia, Simonetta; Enrico Rovati, G

1998-01-01

Cysteinyl-leukotrienes (cysteinyl-LTs) are important mediators in the pathogenesis of asthma. They cause bronchoconstriction, mucus hypersecretion, increase in microvascular permeability, plasma extravasation and eosinophil recruitment. We investigated the pharmacological profile of the cysteinyl-LT antagonists CGP 45715A (iralukast), a structural analogue of LTD4 and CGP 57698, a quinoline type antagonist, in human airways in vitro, by performing binding studies on human lung parenchyma membranes and functional studies on human isolated bronchial strips. Competition curves vs [3H]-LTD4 on human lung parenchyma membranes demonstrated that: (a) both antagonists were able to compete for the two sites labelled by [3H]-LTD4; (b) as in all the G-protein coupled receptors, iralukast and CGP 57698 did not discriminate between the high and the low affinity states of the CysLT receptor labelled by LTD4 (Ki1=Ki2=16.6 nM±36% CV and Ki1= Ki2=5.7 nM±19% CV, respectively); (c) iralukast, but not CGP 57698, displayed a slow binding kinetic, because preincubation (15 min) increased its antagonist potency. In functional studies: (a) iralukast and CGP 57698 antagonized LTD4-induced contraction of human bronchi, with pA2 values of 7.77±4.3% CV and 8.51±1.6% CV, respectively, and slopes not significantly different from unity; (b) the maximal LTD4 response in the presence of CGP 57698 was actually increased, thus clearly deviating from apparent simple competition. Both antagonists significantly inhibited antigen-induced contraction of human isolated bronchial strips in a concentration-dependent manner, lowering the upper plateau of the anti-IgE curves. In conclusion, the results of the present in vitro investigation indicate that iralukast and CGP 57698 are potent antagonists of LTD4 in human airways, with affinities in the nanomolar range, similar to those obtained for ICI 204,219 and ONO 1078, two of the most clinically advanced CysLT receptor antagonists. Thus, these compounds might be useful drugs for the therapy of asthma and other allergic diseases. PMID:9504401

Involvement of substance P present in primary afferent neurones in modulation of cutaneous blood flow in the instep of rat hind paw.

PubMed Central

Yonehara, N.; Chen, J. Q.; Imai, Y.; Inoki, R.

1992-01-01

1. The participation of small-diameter afferent fibres in the microcirculatory haemodynamics of cutaneous tissue was examined by studies on the effects of antidromic stimulation of primary afferent neurones on cutaneous blood flow (CBF) and tachykinin release into the subcutaneous space in the instep of the hind paw of rats. 2. Antidromic stimulation of the sectioned sciatic nerve induced a biphasic flow response, an initial transient decrease followed by an increase, with no alteration in the blood pressure. 3. Neither phase was affected by pretreatment with phentolamine (0.1 mg kg-1, i.a.), propranolol (0.5 mg kg-1, i.a.), atropine (0.5 mg kg-1, i.a.), methysergide (0.5 mg kg-1, i.a.) or mepyramine (10 mg kg-1, i.a.) plus cimetidine (10 mg kg-1, i.a.), but both were significantly inhibited by pretreatment with capsaicin (50 mg kg-1, s.c.). 4. Spantide (1-2 mumol kg-1, i.a.), a substance P (SP) antagonist, reduced the basal CBF, and also inhibited both phases of the biphasic flow response evoked by antidromic stimulation of the sectioned sciatic nerve. 5. Intra-arterial infusion of SP (0.5 mumol kg-1, i.a.) induced a biphasic flow response similar to that elicited by antidromic stimulation of the sectioned sciatic nerve. 6. Antidromic stimulation of the sectioned sciatic nerve caused a marked increase in SP release into the subcutaneous perfusate of the instep of the rat hind paw, but no detectable increase in neurokinin A release.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1382777

[Inter- and intraindividual pharmacokinetic variations in the treatment of Parkinson's disease].

PubMed

Nomoto, Masahiro; Nakatsuka, Akiko; Nagai, Masahiro; Yabe, Hayato; Moritoyo, Takashi; Moritoyo, Hiroyoko; Nisikawa, Noriko

2005-11-01

In the treatment of Parkinson's disease, levodopa, DCI, MAO-B inhibitor, COMT inhibitors, dopamine receptor agonists, amantadine, anticholinergics have been applied and new drugs are being developed. Levodopa is still the golden standard in the treatment of Parkinson's disease. The study on levodopa bioavailability showed 3-4 times differences in individual patients. Drug-food interactions are prominent in levodopa. Low protein food increased levodopa bioavailability and improved no ON or delayed ON in the treatment of Parkinson's disease. Vitamine C or magnesium did not alter the bioavailability of levodopa. The bioavailability of levodopa between the levodopa/carbidioa (100/12.5) group and the levodopa/benserazide (100/25) group was studied in patients with Parkinson's disease by population PK study. C(max) of levodopa in levodeopa/benserazide group was twice as high as in levodopa/carbidopa group. Domperidone, a dopamine receptor antagonist applied as an antiemetic inceases vowel movement. The effect of domperidone on levodopa bioavailability was studied, and the combination of domperidone with levodopa increased AUC of levodopa. Clarythromycin or grape fruit juice inhibits both of CYP3A4 and P-glycoprotein which work on metabolism and absorption of drugs. Coadministration of clarythromycin with ergot alkaloids such as cabergoline or bromocriptine increased the AUC up to 2-3 times. Amantadine is excreted through kidney without being metabolized and renal function is the most important factor in the blood concentration of amantadine. In elder women with the body weight of 50 kg or less, creatinine clearance is less than 50 ml/min even though the serum creatinine is within the normal range. Selegiline is metabolized through CYP2D6 and 3A4. Coadministration of qunidine, cimetidine, maclorides, antifungals, grape fruit juice increase the bioavailability of selegiline and may augment the antiparkinsonian effect.

Cimetidine enhancement of cyclophosphamide antitumour activity.

PubMed Central

Dorr, R. T.; Alberts, D. S.

1982-01-01

Male DBA2 mice were given 10(6) P-388 leukaemic cells i.p. and cimetidine (CMT) at 100 mg/kg 1 day for 10 days, or as a single 100 mg/kg injection 30 min before cyclophosphamide (CTX). CMT significantly prolonged the survival of groups of mice receiving 50, 100 and 200 mg/kg of CTX 3 days after tumour inoculation. Median survival increased by 5.5 days (P less than 0.05), 10 days (P less than 0.05) and 13 days (P less than 0.05) respectively. The addition of CMT had the effect of roughly doubling the CTX dose, without increasing the lethality. CMT produced the only long-term survival seen in the study (1-2/10) CMT alone had no apparent antitumour activity. CMT significantly prolonged mean pentobarbital sleep to 28.6-60 min vs only 10 min for phenobarbital treated mice. Both CMT regimens increased the plasma concentration time products for CTX-induced metabolites (NBP) by about 1.3 fold (in contrast to a 33% reduction with phenobarbital). On average the single-dose CMT regimen produced the greatest effect on survival, on pentobarbital sleep duration and on total NBP reactive species. Probable mechanisms for the CMT-CTX interaction include competitive microsomal enzyme inhibition and/or acutely depressed hepatic blood flow. Caution should be used in combining CMT with full doses of CTX and any other highly metabolized antineoplastic agents in man. PMID:7059463

Comparing the cardiovascular therapeutic indices of glycopyrronium and tiotropium in an integrated rat pharmacokinetic, pharmacodynamic and safety model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trifilieff, Alexandre; Ethell, Brian T.; Sykes, David A.

Long acting inhaled muscarinic receptor antagonists, such as tiotropium, are widely used as bronchodilator therapy for chronic obstructive pulmonary disease (COPD). Although this class of compounds is generally considered to be safe and well tolerated in COPD patients the cardiovascular safety of tiotropium has recently been questioned. We describe a rat in vivo model that allows the concurrent assessment of muscarinic antagonist potency, bronchodilator efficacy and a potential for side effects, and we use this model to compare tiotropium with NVA237 (glycopyrronium bromide), a recently approved inhaled muscarinic antagonist for COPD. Anaesthetized Brown Norway rats were dosed intratracheally at 1more » or 6 h prior to receiving increasing doses of intravenous methacholine. Changes in airway resistance and cardiovascular function were recorded and therapeutic indices were calculated against the ED{sub 50} values for the inhibition of methacholine-induced bronchoconstriction. At both time points studied, greater therapeutic indices for hypotension and bradycardia were observed with glycopyrronium (19.5 and 28.5 fold at 1 h; > 200 fold at 6 h) than with tiotropium (1.5 and 4.2 fold at 1 h; 4.6 and 5.5 fold at 6 h). Pharmacokinetic, protein plasma binding and rat muscarinic receptor binding properties for both compounds were determined and used to generate an integrated model of systemic M{sub 2} muscarinic receptor occupancy, which predicted significantly higher M{sub 2} receptor blockade at ED{sub 50} doses with tiotropium than with glycopyrronium. In our preclinical model there was an improved safety profile for glycopyrronium when compared with tiotropium. - Highlights: • We use an in vivo rat model to study CV safety of inhaled muscarinic antagonists. • We integrate protein and receptor binding and PK of tiotropium and glycopyrrolate. • At ED{sub 50} doses for bronchoprotection we model systemic M{sub 2} receptor occupancy. • Glycopyrrolate demonstrates lower M{sub 2} occupancy at bronchoprotective doses. • Glycopyrrolate demonstrates an improved CV safety profile, versus tiotropium.« less

Dopamine induces inhibitory effects on the circular muscle contractility of mouse distal colon via D1- and D2-like receptors.

PubMed

Auteri, Michelangelo; Zizzo, Maria Grazia; Amato, Antonella; Serio, Rosa

2016-08-01

Dopamine (DA) acts as gut motility modulator, via D1- and D2-like receptors, but its effective role is far from being clear. Since alterations of the dopaminergic system could lead to gastrointestinal dysfunctions, a characterization of the enteric dopaminergic system is mandatory. In this study, we investigated the role of DA and D1- and D2-like receptors in the contractility of the circular muscle of mouse distal colon by organ-bath technique. DA caused relaxation in carbachol-precontracted circular muscle strips, sensitive to domperidone, D2-like receptor antagonist, and mimicked by bromocriptine, D2-like receptor agonist. 7-Chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH-23390), D1-like receptor antagonist, neural toxins, L-NAME (nitric oxide (NO) synthase inhibitor), 2'-deoxy-N 6 -methyl adenosine 3',5'-diphosphate diammonium salt (MRS 2179), purinergic P2Y1 antagonist, or adrenergic antagonists were ineffective. DA also reduced the amplitude of neurally evoked cholinergic contractions. The effect was mimicked by (±)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrobromide (SKF-38393), D1-like receptor agonist and antagonized by SCH-23390, MRS 2179, or L-NAME. Western blotting analysis determined the expression of DA receptor proteins in mouse distal colon. Notably, SCH-23390 per se induced an increase in amplitude of spontaneous and neurally evoked cholinergic contractions, unaffected by neural blockers, L-NAME, MRS 2179, muscarinic, adrenergic, or D2-like receptor antagonists. Indeed, SCH-23390-induced effects were antagonized by an adenylyl cyclase blocker. In conclusion, DA inhibits colonic motility in mice via D2- and D1-like receptors, the latter reducing acetylcholine release from enteric neurons, involving nitrergic and purinergic systems. Whether constitutively active D1-like receptors, linked to adenylyl cyclase pathway, are involved in a tonic inhibitory control of colonic contractility is questioned.

Evaluation of the antiulcerogenic activity of Maytenus robusta (Celastraceae) in different experimental ulcer models.

PubMed

de Andrade, Sérgio Faloni; Lemos, Marivane; Comunello, Eros; Noldin, Vânia Floriani; Filho, Valdir Cechinel; Niero, Rivaldo

2007-09-05

Maytenus robusta (Celastraceae) is used in folk medicine for the treatment of stomach ulcers and is very well adapted to the South of Brazil. Maytenus ilicifolia is the main species of the Celastraceae family, and is used in the treatment of gastric ulcers. However, Maytenus ilicifolia is presently at the stage of extinction, due to indiscriminate use in Brazil. Thus, the use of Maytenus robusta in phytotherapeutic preparations, instead of Maytenus ilicifolia, is suggested. However, there have been no reports regarding the antiulcer activity of Maytenus robusta extract. Therefore, this study was carried out to evaluate the antiulcerogenic property of the hydroalcoholic extract of aerial parts of Maytenus robusta. The antiulcer assays were performed using the following protocols: nonsteroidal anti-inflammatory drug (NSAID)-induced ulcer, ethanol-induced ulcer, and stress-induced ulcer. The effects of the extract on gastric content volume, pH and total acidity, using the pylorus ligated model, were also evaluated. In the ethanol-induced ulcer model, it was observed that the treatment with Maytenus robusta extract significantly reduced the lesion index in 75.1 +/- 8.6, 85.0 +/- 9.2, 86.6 +/- 7.4 and 75.5 +/- 5.3 for the groups treated with 50, 250 and 500 mg/kg of Maytenus robusta and positive control (omeprazole 30 mg/kg), respectively. Also were observed significant inhibition in lesion index in the indomethacin-induced ulcer model, being the decrease of the 62.5 +/- 7.1, 62.5 +/- 6.1, 63.6 +/- 5.5 and 96.2 +/- 3.6 for groups treated with 50, 250 and 500 mg/kg of Maytenus robusta and positive control (cimetidine 100 mg/kg), respectively. Results similar were observed in the stress-induced ulcer model, where the inhibition of ulcer lesions were 71.3 +/- 5.5, 72.7 +/- 6.3, 76.5 +/- 7.1 and 92.3 +/- 7.5 for the groups treated with 50, 250 and 500 mg/kg of Maytenus robusta and positive control (cimetidine 100 mg/kg), respectively. Regarding the model of gastric secretion, a reduction in the volume of gastric juice volume and total acidity was observed, as well as an increase in gastric pH. The results of the present study showed that Maytenus robusta hydroalcoholic extract displays gastroprotective activity. These results were similar to those obtained in studies carried out with Maytenus ilicifolia, which indicate that this species could be used in phytotherapeutic preparations as a substitute for Maytenus ilicifolia. This work also corroborates the traditional indication of Maytenus robusta, contributing to its pharmacological validation.

Further studies on lead compounds containing the opioid pharmacophore Dmt-Tic.

PubMed

Balboni, Gianfranco; Fiorini, Stella; Baldisserotto, Anna; Trapella, Claudio; Sasaki, Yusuke; Ambo, Akihiro; Marczak, Ewa D; Lazarus, Lawrence H; Salvadori, Severo

2008-08-28

Some reference opioids containing the Dmt-Tic pharmacophore, especially the delta agonists H-Dmt-Tic-Gly-NH-Ph (1) and H-Dmt-Tic-NH-(S)CH(CH2-COOH)-Bid (4) (UFP-512) were evaluated for the influence of the substitution of Gly with aspartic acid, its chirality, and the importance of the -NH-Ph and N(1)H-Bid hydrogens in the inductions of delta agonism. The results provide the following conclusions: (i) Asp increases delta selectivity by lowering the mu affinity; (ii) -NH-Ph and N(1)H-Bid nitrogens methylation transforms the delta agonists into delta antagonists; (iii) the substitution of Gly with L-Asp/D-Asp in the delta agonist H-Dmt-Tic-Gly-NH-Ph gave delta antagonists; the same substitution in the delta agonist H-Dmt-Tic-NH-CH2-Bid yielded more selective agonists, H-Dmt-Tic-NH-(S)CH(CH2-COOH)-Bid and H-Dmt-Tic-NH-(R)CH(CH2-COOH)-Bid; (iv) L-Asp seems important only in functional bioactivity, not in receptor affinity; (v) H-Dmt-Tic-NH-(S)CH(CH2-COOH)-Bid(N(1)-Me) (10) evidenced analgesia similar to 4, which was reversed by naltrindole only in the tail flick. 4 and 10 had opposite behaviours in mice; 4 caused agitation, 10 gave sedation and convulsions.

Contribution of the central histaminergic transmission in the cataleptic and neuroleptic effects of haloperidol.

PubMed

Jain, Nishant S; Tandi, Lakshyapati; Verma, Lokesh

2015-12-01

The antipsychotic properties of haloperidol are primarily attributed to its ability to block dopamine D2 receptors. Histaminergic transmission modulates some of the behavioral effects of haloperidol. Hence, the present study investigated the contribution of central histaminergic transmission in the cataleptic and neuroleptic effect of haloperidol respectively, using bar test and conditioned avoidance response (CAR) in a two-way shuttle box. The studies revealed that haloperidol (0.50 or 1 mg/kg, i.p.) exhibited cataleptic behavior and inhibited conditioned avoidance response (CAR) in the doses 0.25 or 0.50 mg in rats. The rats, pretreated centrally (i.c.v.) with histamine precursor, L-histidine (1, 2.5 μg) or histamine neuronal inducer (H3 receptor antagonist), thioperamide (20, 50 μg/rat), showed an enhanced cataleptic effect with sub-maximal dose of haloperidol (0.5 mg/kg, i.p.). Similarly, the neuroleptic effect of haloperidol (0.25 mg/kg, i.p.) in CAR was also potentiated in the rats pretreated with L-histidine (2.5 μg) or thioperamide (50 μg/rat). Further, the cataleptic effect of haloperidol (1 mg/kg, i.p.) was attenuated in rats pretreated with the H1 receptor antagonist, chlorpheniramine (60, 80 μg/rat, i.c.v.) or H2 receptor antagonist, ranitidine (60 μg/rat, i.c.v.). However, the neuroleptic effect of haloperidol (0.5 mg/kg, i.p.) was completely reversed by pretreatment with ranitidine (60 μg/rat, i.c.v.), and partially attenuated by chlorpheniramine (80 μg/rat, i.c.v.). These findings suggest the possible involvement of histaminergic transmission in the cataleptic and neuroleptic effects of haloperidol probably via H1 or H2 receptor stimulation. Copyright © 2015 Elsevier Inc. All rights reserved.

Association between Kinin B1 Receptor Expression and Leukocyte Trafficking across Mouse Mesenteric Postcapillary Venules

PubMed Central

McLean, Peter G.; Ahluwalia, Amrita; Perretti, Mauro

2000-01-01

Using intravital microscopy, we examined the role played by B1 receptors in leukocyte trafficking across mouse mesenteric postcapillary venules in vivo. B1 receptor blockade attenuated interleukin (IL)-1β–induced (5 ng intraperitoneally, 2 h) leukocyte–endothelial cell interactions and leukocyte emigration (∼50% reduction). The B1 receptor agonist des-Arg9bradykinin (DABK), although inactive in saline- or IL-8–treated mice, caused marked neutrophil rolling, adhesion, and emigration 24 h after challenge with IL-1β (when the cellular response to IL-1β had subsided). Reverse transcriptase polymerase chain reaction and Western blot revealed a temporal association between the DABK-induced response and upregulation of mesenteric B1 receptor mRNA and de novo protein expression after IL-1β treatment. DABK-induced leukocyte trafficking was antagonized by the B1 receptor antagonist des-arg10HOE 140 but not by the B2 receptor antagonist HOE 140. Similarly, DABK effects were maintained in B2 receptor knockout mice. The DABK-induced responses involved the release of neuropeptides from C fibers, as capsaicin treatment inhibited the responses. Treatment with the neurokinin (NK)1 and NK3 receptor antagonists attenuated the responses, whereas NK2, calcitonin gene-related peptide, or platelet-activating factor receptor antagonists had no effect. Substance P caused leukocyte recruitment that, similar to DABK, was inhibited by NK1 and NK3 receptor blockade. Mast cell depletion using compound 48/80 reduced DABK-induced leukocyte trafficking, and DABK treatment was shown histologically to induce mast cell degranulation. DABK-induced trafficking was inhibited by histamine H1 receptor blockade. Our findings provide clear evidence that B1 receptors play an important role in the mediation of leukocyte–endothelial cell interactions in postcapillary venules, leading to leukocyte recruitment during an inflammatory response. This involves activation of C fibers and mast cells, release of substance P and histamine, and stimulation of NK1, NK3, and H1 receptors. PMID:10934225

Vasopressin and a nonpeptide antidiuretic hormone receptor antagonist (OPC-31260).

PubMed

Burrell, L M; Phillips, P A; Stephenson, J M; Risvanis, J; Johnston, C I

1994-03-01

The development of nonpeptide orally active AVP analogues has provided a new tool with which to assess the physiological and pathophysiological role of vasopressin (AVP). We have previously characterised the nonpeptide vasopressin V1 receptor antagonist OPC-21268, and now report the in vitro characterisation of the nonpeptide V2 receptor antagonist OPC-31260 in the rat. OPC-31260 caused a concentration-dependent displacement of the selective AVP V2 receptor antagonist radioligand, [3H]desGly-NH2(9)[d(CH2)5, D-Ile2,Ile4]AVP from V2 receptors in rat kidney medulla membranes. The concentration of OPC-31260 that displaced 50% of specific AVP binding (IC50) was 20 +/- 2 nmol/l for renal V2 receptors. OPC-31260 also caused a concentration-dependent displacement of the selective AVP V1 receptor antagonist radioligand, [125I]-[d(CH2)5,sarcosine7]AVP from V1 receptors in both rat liver and kidney medulla membranes. The IC50 was 500 +/- 30 nmol/l for both renal and liver V1 receptors. After oral administration to rats, OPC-31260 was an effective inhibitor of AVP at renal V2 and liver V1 receptors in a time-dependent manner. In vitro binding kinetic studies showed that OPC-31260 was a competitive antagonist at both the renal V2 receptor and the hepatic V1 receptor. OPC-31260 is a nonpeptide, orally effective competitive inhibitor of AVP with a V2:V1 receptor selectivity ratio of 25:1 indicating relative V2 receptor selectivity.

Hydrogen peroxide preferentially activates capsaicin‐sensitive high threshold afferents via TRPA1 channels in the guinea pig bladder

PubMed Central

Nicholas, S; Yuan, S Y; Brookes, S J H; Spencer, N J

2016-01-01

Background and Purpose There is increasing evidence suggesting that ROS play a major pathological role in bladder dysfunction induced by bladder inflammation and/or obstruction. The aim of this study was to determine the effect of H2O2 on different types of bladder afferents and its mechanism of action on sensory neurons in the guinea pig bladder. Experimental Approach ‘Close‐to‐target’ single unit extracellular recordings were made from fine branches of pelvic nerves entering the guinea pig bladder, in flat sheet preparations, in vitro. Key Results H2O2 (300–1000 μM) preferentially and potently activated capsaicin‐sensitive high threshold afferents but not low threshold stretch‐sensitive afferents, which were only activated by significantly higher concentrations of hydrogen peroxide. The TRPV1 channel agonist, capsaicin, excited 86% of high threshold afferents. The TRPA1 channel agonist, allyl isothiocyanate and the TRPM8 channel agonist, icilin activated 72% and 47% of capsaicin‐sensitive high threshold afferents respectively. The TRPA1 channel antagonist, HC‐030031, but not the TRPV1 channel antagonist, capsazepine or the TRPM8 channel antagonist, N‐(2‐aminoethyl)‐N‐[[3‐methoxy‐4‐(phenylmethoxy)phenyl]methyl]thiophene‐2‐carboxamide, significantly inhibited the H2O2‐induced activation of high threshold afferents. Dimethylthiourea and deferoxamine did not significantly change the effect of H2O2 on high threshold afferents. Conclusions and Implications The findings show that H2O2, in the concentration range detected in inflammation or reperfusion after ischaemia, evoked long‐lasting activation of the majority of capsaicin‐sensitive high threshold afferents, but not low threshold stretch‐sensitive afferents. The data suggest that the TRPA1 channels located on these capsaicin‐sensitive afferent fibres are probable targets of ROS released during oxidative stress. PMID:27792844

Dopamine antagonists during parturition disrupt maternal care and the retention of maternal behavior in rats.

PubMed

Byrnes, Elizabeth M; Rigero, Beth A; Bridges, Robert S

2002-11-01

Brief contact with pups at parturition enables the female rat to establish and retain the full repertoire of maternal behaviors, allowing her to respond rapidly to pups in the future. To determine whether the dopamine system is involved in the retention of maternal behavior, females were continuously infused with dopamine antagonists during the periparturitional period and then allowed either a brief interaction period with pups (3 h) or no interaction with pups (pups removed as they were born). Females were exposed to either the D1-like antagonist SCH 23390 (0.1 or 1.0 mg/kg/day) or the D2-like antagonist clebopride (0.5 or 1.0 mg/kg/day). The high dose of either DA antagonist resulted in significant attenuation of maternal care immediately postpartum. When tested for the retention of maternal behavior 7 days later, however, only the females exposed to the D2 antagonist displayed a delayed response to shown full maternal behavior (FMB) towards donor pups. Thus, while both dopamine receptor subtypes appear necessary for the full and rapid expression of maternal behavior during the early postpartum period, only the D2 receptor subtype appears to be involved in the retention of this behavior.

Differential regulation of smooth muscle contraction in rabbit internal anal sphincter by substance P and bombesin.

PubMed

Bitar, K N; Hillemeier, C; Biancani, P

1990-01-01

Substance P and bombesin induce contraction of isolated IAS smooth muscle cells by different intracellular mechanisms. The cells contracted in a dose dependent manner to both peptides. The kinetics of contraction were different. Substance P induced contraction peaked at 30 seconds and declined in a time dependent manner while bombesin induced contraction peaked at 30 seconds and was maintained for up to 8 minutes. The absence of extracellular calcium in the medium (0 calcium and 2 mM EGTA) had no affect on substance P induced contraction while it blocked bombesin induced contraction. Substance P induced contraction was blocked by the calmodulin antagonist W7 (10(-9)M) and was not affected by the PKC antagonist H7 (10(-6)M). Bombesin induced contraction was blocked by the PKC antagonist H7 and was not affected by the calmodulin antagonist W7. Our data indicate that substance P induces a transient contraction utilizing intracellular calcium and a calmodulin dependent pathway, while bombesin induces a sustained contraction utilizing calcium from extracellular sources and a calmodulin independent pathway.

Pharmacological Characterization of H05, a Novel Serotonin and Noradrenaline Reuptake Inhibitor with Moderate 5-HT2A Antagonist Activity for the Treatment of Depression.

PubMed

Xu, Xiangqing; Wei, Yaqin; Guo, Qiang; Zhao, Song; Liu, Zhiqiang; Xiao, Ting; Liu, Yani; Qiu, Yinli; Hou, Yuanyuan; Zhang, Guisen; Wang, KeWei

2018-06-01

Multitarget antidepressants selectively inhibiting monoaminergic transporters and 5-hydroxytryptamine (5-HT) 2A receptor have demonstrated higher efficacy and fewer side effects than selective serotonin reuptake inhibitors. In the present study, we synthesized a series of novel 3-(benzo[d][1,3]dioxol-4-yloxy)-3-arylpropyl amine derivatives, among which compound H05 was identified as a lead, exhibiting potent inhibitory effects on both serotonin ( K i = 4.81 nM) and norepinephrine (NE) ( K i = 6.72 nM) transporters and moderate 5-HT 2A antagonist activity (IC 50 = 60.37 nM). H05 was able to dose-dependently reduce the immobility duration in mouse forced swimming test and tail suspension test, with the minimal effective doses lower than those of duloxetine, and showed no stimulatory effect on locomotor activity. The administration of H05 (5, 10, and 20 mg/kg, by mouth) significantly shortened the immobility time of adrenocorticotropin-treated rats that serve as a model of treatment-resistant depression, whereas imipramine (30 mg/kg, by mouth) and duloxetine (30 mg/kg, by mouth) showed no obvious effects. Chronic treatment with H05 reversed the depressive-like behaviors in a rat model of chronic unpredictable mild stress and a mouse model of corticosterone-induced depression. Microdialysis analysis revealed that the administration of H05 at either 10 or 20 mg/kg increased the release of 5-HT and NE from the frontal cortex. The pharmacokinetic (PK) and brain penetration analyses suggest that H05 has favorable PK properties with good blood-brain penetration ability. Therefore, it can be concluded that H05, a novel serotonin and NE reuptake inhibitor with 5-HT 2A antagonist activity, possesses efficacious activity in the preclinical models of depression and treatment-resistant depression, and it may warrant further evaluation for clinical development. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

A prostaglandin E2 receptor antagonist prevents pregnancies during a preclinical contraceptive trial with female macaques.

PubMed

Peluffo, M C; Stanley, J; Braeuer, N; Rotgeri, A; Fritzemeier, K-H; Fuhrmann, U; Buchmann, B; Adevai, T; Murphy, M J; Zelinski, M B; Lindenthal, B; Hennebold, J D; Stouffer, R L

2014-07-01

Can administration of a prostaglandin (PG) E2 receptor 2 (PTGER2) antagonist prevent pregnancy in adult female monkeys by blocking periovulatory events in the follicle without altering menstrual cyclicity or general health? This is the first study to demonstrate that a PTGER2 antagonist can serve as an effective non-hormonal contraceptive in primates. The requirement for PGE2 in ovulation and the release of an oocyte surrounded by expanded cumulus cells (cumulus-oocyte expansion; C-OE) was established through the generation of PTGS2 and PTGER2 null-mutant mice. A critical role for PGE2 in primate ovulation is supported by evidence that intrafollicular injection of indomethacin in rhesus monkeys suppressed follicle rupture, whereas co-injection of PGE2 with indomethacin resulted in ovulation. First, controlled ovulation protocols were performed in adult, female rhesus monkeys to analyze the mRNA levels for genes encoding PGE2 synthesis and signaling components in the naturally selected pre-ovulatory follicle at different times after the ovulatory hCG stimulus (0, 12, 24, 36 h pre-ovulation; 36 h post-ovulation, n = 3-4/time point). Second, controlled ovarian stimulation cycles were utilized to obtain multiple cumulus-oocyte complexes (COCs) from rhesus monkeys to evaluate the role of PGE2 in C-OE in vitro (n = 3-4 animals/treatment; ≥3 COCs/animal/treatment). Third, adult cycling female cynomolgus macaques were randomly assigned (n = 10/group) to vehicle (control) or PTGER2 antagonist (BAY06) groups to perform a contraceptive trial. After the first treatment cycle, a male of proven fertility was introduced into each group and they remained housed together for the duration of the 5-month contraceptive trial that was followed by a post-treatment reversibility trial. Quantitative real-time PCR, COC culture and expansion, immunofluorescence/confocal microscopy, enzyme immunoassay, contraceptive trial, ultrasonography, complete blood counts, serum biochemistry tests and blood lipid profiles. Several mRNAs encoding proteins involved in PGE2 synthesis, metabolism and signaling increase (P < 0.05) in the periovulatory follicle after administration of an ovulatory hCG bolus. PGE2 signaling through PTGER2 induces cumulus cell expansion and production of hyaluronic acid, which are critical events for fertilization. Moreover, chronic administration of a selective PTGER2 antagonist resulted in a significant (P < 0.05 versus vehicle-treated controls) contraceptive effect without altering steroid hormone patterns or menstrual cyclicity during a 5-months contraceptive trial. Fertility recovered as early as 1 month after ending treatment. This is a proof-of-concept study in a non-human primate model. Further investigations are warranted to elucidate the mechanism(s) of PTGER2 antagonist action in the primate ovary. Although PTGER2 antagonist treatment did not produce any obvious undesirable effects, improvements in the mode of administration, as well as the efficacy of these compounds, are necessary to consider such a contraceptive for women. Monitoring as well as improving the efficacy and safety of female contraceptives is an important public health activity. Even though hormonal contraceptives are effective for women, concerns remain regarding their side-effects and long-term use because of the widespread actions of such steroidal products in many tissues. Moreover, some women cannot take hormones for medical reasons. Thus, development of non-hormonal contraceptives for women is warranted. Supported by Bayer HealthCare Pharmaceuticals, The Eunice Kennedy Shriver NICHD Contraceptive Development and Research Center (U54 HD055744), NIH Office of the Director (Oregon National Primate Research Center P51 OD011092), and a Lalor Foundation Postdoctoral Basic Research Fellowship (MCP). The use of the Leica confocal was supported by grant number S10RR024585. Some of the authors (N.B., A.R., K.-H.F., U.F., B.B. and B.L.) are employees of Bayer Healthcare Pharma.

[Antagonistic interaction between Clostridium butyricum and enterohemorrhagic Escherichia coli O157:H7].

PubMed

Takahashi, M; Taguchi, H; Yamaguchi, H; Osaki, T; Sakazaki, R; Kamiya, S

1999-01-01

Antagonistic interaction between Clostridium butyricum strain MIYAIRI 588 and enterohemorrhagic Esherichia coli (EHEC) strain O157:H7 006 was examined using streptomycin-treated SPF mice and germ free mice. All SPF mice pretreated with streptomycin were colonized with EHEC O157:H7. On the other hand, only 20% of the SPF mice pretreated with streptomycin and C. butyricum were colonized with EHEC O157:H7. In addition, germ free mice died within 4-7 days after infection with EHEC O157:H7. In contrast, all gnotobiotic mice mono-associated with C. butyricum survived after the challenge with EHEC O157:H7. Both the number of EHEC and the amounts of shiga-like cytotoxin (SLT, type 1 and type 2) in fecal contents of gnotobiotic mice treated with C. butyricum were less than those of mice infected with only EHEC O157:H7. In conclusion, the probiotic bacterium, C. butyricum strain MIYAIRI 588, has a preventive effect against EHEC O157:H7 infection.

In Vitro Binding of [³H]PSB-0413 to P2Y₁₂ Receptors.

PubMed

Dupuis, Arnaud; Heim, Véronique; Ohlmann, Philippe; Gachet, Christian

2015-12-08

The P2Y₁₂/ADP receptor plays a central role in platelet activation. Characterization of this receptor is mandatory for studying disorders associated with a P2Y₁₂ receptor defect and for evaluating P2Y₁₂ receptor agonists and antagonists. In the absence of suitable anti-P2Y₁₂ antibodies, radioligand binding assays are the only way to conduct such studies. While various radioligands were employed in the past for this purpose, none were found to be suitable for routine use. Described in this unit are protocols for quantitatively and qualitatively assessing P2Y₁₂ receptors with [³H]PSB-0413, a selective antagonist for this site. The saturation and competition assays described herein make possible the determination of P2Y₁₂ receptor density on cells, as well as the potencies and affinities of test agents at this site. Copyright © 2015 John Wiley & Sons, Inc.

Orally active vasopressin V1a receptor antagonist, SRX251, selectively blocks aggressive behavior.

PubMed

Ferris, Craig F; Lu, Shi-Fang; Messenger, Tara; Guillon, Christophe D; Heindel, Ned; Miller, Marvin; Koppel, Gary; Robert Bruns, F; Simon, Neal G

2006-02-01

Arginine vasopressin functions as a neurochemical signal in the brain to affect social behavior. There is an expanding literature from animal and human studies showing that vasopressin, through the vasopressin 1A receptor (V1A), can stimulate aggressive behavior. Using a novel monocylic beta lactam platform, a series of orally active vasopressin V1a antagonists was developed with high affinity for the human receptor. SRX251 was chosen from this series of V1a antagonists to screen for effects on serenic activity in a resident-intruder model of offensive aggression. Resident, male Syrian golden hamsters were given oral doses of SRX251 or intraperitoneal Manning compound, a selective V1a receptor antagonist with reduced brain penetrance, at doses of 0.2 microg, 20 microg, 2 mg/kg or vehicle. When tested 90-120 min later, SRX251, but not Manning compound, caused a significant dose-dependent reduction in offensive aggression toward intruders as measured by latency to bite and number of bites. The reduction in aggression persisted for over 6 h and was no longer present 12 h post treatment. SRX251 did not alter the amount of time the resident investigated the intruder, olfactory communication, general motor activity, or sexual motivation. These data corroborate previous studies showing a role for vasopressin neurotransmission in aggression and suggest that V1a receptor antagonists may be used to treat interpersonal violence co-occurring with such illness as ADHD, autism, bipolar disorder, and substance abuse.

Advances in the Diagnosis of Sepsis: Hydrogen Sulfide as a Prognostic Marker of Septic Shock Severity

PubMed Central

Košir, Miha

2017-01-01

Hydrogen sulfide (H2S) is a third known gasotransmitter. Most of the time it was knows as a poisonous gas. In last 30 years, we are seeing change in its perception. Scientists have discovered its major role in different organ systems. It is endogenously produced in various tissues and its production is influenced by many factors. In normal, physiological conditions only 20% of H2S is in its free form. The role of H2S is very wide. It acts as a signaling molecule, has influence on vascular tone, inflammatory response, scavenges reactive oxygen species, can be cytoprotective and can even reduce the extent of myocardial ischemia. Different studies have shown H2S has considerable influence in pathology of sepsis and its outcome. High free plasma levels of H2S are predictor of unfavorable outcome. Findings show that moderate free plasma levels of H2S have protective effect. Paradoxical very low free plasma levels of H2S, seen in patients with chronic heart failure, are also predictor of severity of disease and poor outcome. We presume that relationship between morbidity/mortality and concentration of H2S has a wide U-shape curve dependence. New researches with discovery of H2S agonists and antagonists could open new ways in understanding different pathologies and ability to treat them. Recent advances in the identification of H2S agonists and antagonists may help in forwarding our understanding of pathomechanisms and hence their treatment. PMID:28757821

Head-to-head comparison of H2-receptor antagonists and proton pump inhibitors in the treatment of erosive esophagitis: A meta-analysis

PubMed Central

Wang, Wei-Hong; Huang, Jia-Qing; Zheng, Ge-Fan; Xia, Harry Hua-Xiang; Wong, Wai-Man; Lam, Shiu-Kum; Wong, Benjamin Chun-Yu

2005-01-01

AIM: To systematically evaluate the efficacy of H2-receptor antagonists (H2RAs) and proton pump inhibitors in healing erosive esophagitis (EE). METHODS: A meta-analysis was performed. A literature search was conducted in PubMed, Medline, Embase, and Cochrane databases to include randomized controlled head-to-head comparative trials evaluating the efficacy of H2RAs or proton pump inhibitors in healing EE. Relative risk (RR) and 95% confidence interval (CI) were calculated under a random-effects model. RESULTS: RRs of cumulative healing rates for each comparison at 8 wk were: high dose vs standard dose H2RAs, 1.17 (95%CI, 1.02-1.33); standard dose proton pump inhibitors vs standard dose H2RAs, 1.59 (95%CI, 1.44-1.75); standard dose other proton pump inhibitors vs standard dose omeprazole, 1.06 (95%CI, 0.98-1.06). Proton pump inhibitors produced consistently greater healing rates than H2RAs of all doses across all grades of esophagitis, including patients refractory to H2RAs. Healing rates achieved with standard dose omeprazole were similar to those with other proton pump inhibitors in all grades of esophagitis. CONCLUSION: H2RAs are less effective for treating patients with erosive esophagitis, especially in those with severe forms of esophagitis. Standard dose proton pump inhibitors are significantly more effective than H2RAs in healing esophagitis of all grades. Proton pump inhibitors given at the recommended dose are equally effective for healing esophagitis. PMID:15996033

The use of H2 antagonists in treating and preventing NSAID-induced mucosal damage.

PubMed

Tuskey, Anne; Peura, David

2013-01-01

Pain affects the quality of life for millions of individuals and is a major reason for healthcare utilization. As populations age, medical personnel will need to manage more and more patients suffering from pain associated with degenerative and inflammatory musculoskeletal disorders. Nonsteroidal anti-inflammatory drugs (NSAIDs) are an effective treatment for both acute and chronic musculoskeletal pain; however, their use is associated with potentially significant gastrointestinal (GI) toxicity. Guidelines suggest various strategies to prevent problems in those at risk for NSAID-associated GI complications. In this article, we review the data supporting one such strategy - the use of histamine type-2 receptor antagonists (H2RAs) - for the prevention of GI adverse events in NSAID users. Older studies suggest that high-dose H2RAs are effective in preventing upper GI ulcers and dyspepsia. This suggestion was recently confirmed during clinical trials with a new ibuprofen/famotidine combination that reduced the risk of ulcers by 50% compared with ibuprofen alone.

The use of H2 antagonists in treating and preventing NSAID-induced mucosal damage

PubMed Central

2013-01-01

Pain affects the quality of life for millions of individuals and is a major reason for healthcare utilization. As populations age, medical personnel will need to manage more and more patients suffering from pain associated with degenerative and inflammatory musculoskeletal disorders. Nonsteroidal anti-inflammatory drugs (NSAIDs) are an effective treatment for both acute and chronic musculoskeletal pain; however, their use is associated with potentially significant gastrointestinal (GI) toxicity. Guidelines suggest various strategies to prevent problems in those at risk for NSAID-associated GI complications. In this article, we review the data supporting one such strategy - the use of histamine type-2 receptor antagonists (H2RAs) - for the prevention of GI adverse events in NSAID users. Older studies suggest that high-dose H2RAs are effective in preventing upper GI ulcers and dyspepsia. This suggestion was recently confirmed during clinical trials with a new ibuprofen/famotidine combination that reduced the risk of ulcers by 50% compared with ibuprofen alone. PMID:24267478

Histamine H{sub 3} receptor antagonist OUP-186 attenuates the proliferation of cultured human breast cancer cell lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Satoshi; Sakaguchi, Minoru; Yoneyama, Hiroki

Histamine is involved in various physiological functions, including its neurotransmitter actions in the central nervous system and its action as a causative agent of inflammation, allergic reactions, and gastric acid secretions. Histamine expression and biosynthesis have been detected in breast cancer cells. It was recently suggested that the histamine H{sub 3} receptor (H{sub 3}R) plays a role in the proliferation of breast cancer cells. We recently developed the non-imidazole H{sub 3}R antagonist OUP-186 which exhibited a potent and selective human H{sub 3}R antagonistic activity as well as no activity against the human histamine H{sub 4} receptor (H{sub 4}R). In thismore » study, we compared the effects of OUP-186 on the proliferation of estrogen receptor negative (ER−) breast cancer cells (MDA-MB-231) and ER+ breast cancer cells (MCF7) to the effects of clobenpropit (potent imidazole-containing H{sub 3}R antagonist). OUP-186 and clobenpropit suppressed the proliferation of breast cancer cells. The IC{sub 50} values at 48 h for OUP-186 and clobenpropit were approximately 10 μM and 50 μM, respectively. Furthermore, OUP-186 potently induced cell death by activating caspase-3/7, whereas cell death was only slightly induced by clobenpropit. In addition, OUP-186 treatment blocked the proliferation increase triggered by 100 μM (R)-(-)-α-methylhistamine (H{sub 3}R agonist). The use of 4-methylhistamine (H{sub 4}R agonist) and JNJ10191584 (selective H{sub 4}R antagonist) did not affect breast cancer proliferation. These results indicate that OUP-186 potently suppresses proliferation and induces caspase-dependent apoptotic death in both ER+ and ER-breast cancer cells. - Highlights: • OUP-186, a histamine H{sub 3} receptor antagonist, effects breast cancer cell growth. • OUP-186 potently suppressed proliferation and induced caspase-dependent apoptosis. • OUP-186 may be an effective drug against ER+ and ER− breast cancers.« less

A transfected cell model for the renal toxin transporter, rOCT2.

PubMed

Pan, B F; Sweet, D H; Pritchard, J B; Chen, R; Nelson, J A

1999-02-01

A cDNA for the organic cation transporter (rOCT2) of the rat kidney was inserted into the retroviral plasmid pLXSN. This plasmid was used to stably transfect NIH3T3 cells. The transfected cell line exhibited an enhanced rate of tetraethylammonium (TEA) uptake and efflux compared to wild-type NIH3T3 cells. Uptake of TEA by the transfected cells was markedly reduced upon incubation at 4 degrees C. When the extracellular pH was lowered from 8.1 to 5.9, uptake was also reduced, suggesting inhibition of rOCT2 by extracellular protons. The apparent K(m) for TEA in the transfected cells was 141 microM. The classical organic cation transport inhibitors, cyanine 863 and cimetidine, produced noncompetitive inhibition with apparent Ki values of 0.81 and 198 microM, respectively. Daunomycin, vinblastine, and the deoxyadenosine analogs, 2'-deoxytubercidin and 2-chlorodeoxyadenosine, did not appear to be substrates for rOCT2. However, the anticancer drug, cisplatin, competitively inhibited TEA uptake by rOCT2 with an apparent Ki value of 925 microM, suggesting that rOCT2 may play a role in its renal secretion. In summary, transfected NIH3T3 cells provide a facile system by which this and other organic ion transporters can be studied.

Activation helix orientation of the estrogen receptor is mediated by receptor dimerization: evidence from molecular dynamics simulations.

PubMed

Fratev, Filip

2015-05-28

In recent years, the nuclear receptors (NR) dynamics have been studied extensively by various approaches. However, the transition path of helix 12 (H12) to an agonist or an antagonist conformation and the exchange pathway between these states is not clear yet. A number of accelerated molecular dynamics (aMD) runs were performed on both an ERα monomer and a homodimer with a total length of 2.2 μs. We have been able to sample reasonably well the H12 conformational landscape to reproduce precisely both the agonist and the antagonist conformations, starting from an unfolded position, and to describe the transition path between them, even in the presence of an agonist ligand. These conformations were the most prevalent, suggesting that the extended H12 state is not likely to exist and that the natural ERα H12 position might exist in both the agonist and antagonist states. Remarkably, the H12 transition occurs and is regulated only in a dimer form and the proper agonist or antagonist H12 conformation can be achieved solely in one of the dimer subunits. These results clearly demonstrate that clusters of the two well-known H12 states exist by themselves in the protein free energy landscape, i.e. they are not constituted directly by the ligands, and dimerization favors the switch between them. Conversely, in a monomer, no transitions have been observed. Thus, the dimer formation helps the constitution of populations of discrete H12 conformational states and reshapes the conformational landscape. Further analyses have shown that these observations can be explained by specific interface and long range protein-protein interactions, resulting in conformational fluctuations in helices 5 and 11. Based on these results, a new ERα activation/deactivation mechanism and a sequence of binding events during receptor activity modulation have been suggested according to which ligands control the H12 conformation via alterations of the inter-dimer interactions. These findings agree with the HDX and fluorescence experiments and provide an explanation on a structural basis of these data, demonstrating that the dynamics of H12 are not altered greatly upon ligand binding and large fluctuations at the end of H11 are present.

Proton pump inhibitors therapy vs H2 receptor antagonists therapy for upper gastrointestinal bleeding after endoscopy: A meta-analysis

PubMed Central

Zhang, Ying-Shi; Li, Qing; He, Bo-Sai; Liu, Ran; Li, Zuo-Jing

2015-01-01

AIM: To compare the therapeutic effects of proton pump inhibitors vs H2 receptor antagonists for upper gastrointestinal bleeding in patients after successful endoscopy. METHODS: We searched the Cochrane library, MEDLINE, EMBASE and PubMed for randomized controlled trials until July 2014 for this study. The risk of bias was evaluated by the Cochrane Collaboration’s tool and all of the studies had acceptable quality. The main outcomes included mortality, re-bleeding, received surgery rate, blood transfusion units and hospital stay time. These outcomes were estimated using odds ratios (OR) and mean difference with 95% confidence interval (CI). RevMan 5.3.3 software and Stata 12.0 software were used for data analyses. RESULTS: Ten randomized controlled trials involving 1283 patients were included in this review; 678 subjects were in the proton pump inhibitors (PPI) group and the remaining 605 subjects were in the H2 receptor antagonists (H2RA) group. The meta-analysis results revealed that after successful endoscopic therapy, compared with H2RA, PPI therapy had statistically significantly decreased the recurrent bleeding rate (OR = 0.36; 95%CI: 0.25-0.51) and receiving surgery rate (OR = 0.29; 95%CI: 0.09-0.96). There were no statistically significant differences in mortality (OR = 0.46; 95%CI: 0.17-1.23). However, significant heterogeneity was present in both the numbers of patients requiring blood transfusion after treatment [weighted mean difference (WMD), -0.70 unit; 95%CI: -1.64 - 0.25] and the time that patients remained hospitalized [WMD, -0.77 d; 95%CI: -1.87 - 0.34]. The Begg’s test (P = 0.283) and Egger’s test (P = 0.339) demonstrated that there was no publication bias in our meta-analysis. CONCLUSION: In patients with upper gastrointestinal bleeding after successful endoscopic therapy, compared with H2RA, PPI may be a more effective therapy. PMID:26034370

Antidepressant and anxiolytic properties of the methanolic extract of Momordica charantia Linn (Cucurbitaceae) and its mechanism of action.

PubMed

Ishola, I O; Akinyede, A A; Sholarin, A M

2014-07-01

The whole plant of Momordica charantia Linn (Cucurbitaceae) is used in traditional African medicine in the management of depressive illness. Momordica charantia (MC) (50-400 mg/kg, p.o.) was administered 1 h before behavioural studies using the forced swimming test (FST) and tail suspension test (TST) to investigate antidepressant-like effect while the anxiolytic-like effect was evaluated with elevated plus maze test (EPM), hole-board test (HBT), and light-dark test (LDT). Acute treatment with MC (50-400 mg/kg) significantly increased swimming time (86.51%) and reduced the duration of immobility (52.35%) in FST and TST with peak effects observed at 200 mg/kg, respectively, in comparison to control. The pretreatment of mice with either sulpiride (dopamine D2 receptor antagonist), or metergoline (5-HT2 receptor antagonist), or cyproheptadine (5-HT2 receptor antagonist), or prazosin (α1-adrenoceptor antagonist), or yohimbine (α2-adrenoceptor antagonist), and atropine (muscarinic cholinergic receptor antagonist) 15 min before oral administration of MC (200 mg/kg) significantly blocked its anti-immobility effect. Similarly, MC (200 mg/kg) significantly reduced anxiety by increasing the open arm exploration (64.27%) in EPM, number of head-dips in HBT (34.38%), and time spent in light compartment (29.38%) in the LDT. However, pretreatment with flumazenil (GABAA receptor antagonist) 15 min before MC (200 mg/kg) significantly blocked (54.76%) its anxiolytic effect. The findings in this study showed that MC possesses antidepressant-like effect that is dependent on the serotonergic (5-HT2 receptor), noradrenergic (α1- and α2-adrenoceptors), dopaminergic (D2 receptor), and muscarinic cholinergic systems and an anxiolytic-like effect that might involve an action on benzodiazepine-type receptor. © Georg Thieme Verlag KG Stuttgart · New York.

Pharmacological Studies of NOP Receptor Agonists as Novel Analgesics

DTIC Science & Technology

2010-05-01

hydroxymethyl-4-piperidyl]-3-ethyl-1, 3-dihydro- 2H- benzimidazol -2-one (J-113397). J Med Chem 42: 5061–5063. Ko MC, Butelman ER, Traynor JR, Woods JH (1998a...ethyl-1,3-dihydro-2H- benzimidazol -2-one) was used to compare their antagonist effects against both morphine (100 nmol)- and UFP-112 (10 nmol)-induced...3S,4S)-1- (Cyclooctylmethyl)-3-(hydroxymethyl)-4-piperidinyl]-3-ethyl- 1,3-dihydro-2H- benzimidazol -2-one) (Tocris Bioscience, Ellisville, MO), and

A selective antagonist reveals a potential role of G protein-coupled receptor 55 in platelet and endothelial cell function.

PubMed

Kargl, Julia; Brown, Andrew J; Andersen, Liisa; Dorn, Georg; Schicho, Rudolf; Waldhoer, Maria; Heinemann, Akos

2013-07-01

The G protein-coupled receptor 55 (GPR55) is a lysophosphatidylinositol (LPI) receptor that is also responsive to certain cannabinoids. Although GPR55 has been implicated in several (patho)physiologic functions, its role remains enigmatic owing mainly to the lack of selective GPR55 antagonists. Here we show that the compound CID16020046 ((4-[4-(3-hydroxyphenyl)-3-(4-methylphenyl)-6-oxo-1H,4H,5H,6H-pyrrolo[3,4-c]pyrazol-5-yl] benzoic acid) is a selective GPR55 antagonist. In yeast cells expressing human GPR55, CID16020046 antagonized agonist-induced receptor activation. In human embryonic kidney (HEK293) cells stably expressing human GPR55, the compound behaved as an antagonist on LPI-mediated Ca²⁺ release and extracellular signal-regulated kinases activation, but not in HEK293 cells expressing cannabinoid receptor 1 or 2 (CB₁ or CB₂). CID16020046 concentration dependently inhibited LPI-induced activation of nuclear factor of activated T-cells (NFAT), nuclear factor κ of activated B cells (NF-κB) and serum response element, translocation of NFAT and NF-κB, and GPR55 internalization. It reduced LPI-induced wound healing in primary human lung microvascular endothelial cells and reversed LPI-inhibited platelet aggregation, suggesting a novel role for GPR55 in platelet and endothelial cell function. CID16020046 is therefore a valuable tool to study GPR55-mediated mechanisms in primary cells and tissues.

Anti-ulcerogenic activity of aqueous extract of Carica papaya seed on indomethacin-induced peptic ulcer in male albino rats.

PubMed

Oloyede, Hussein O B; Adaja, Matthew C; Ajiboye, Taofeek O; Salawu, Musa O

2015-03-01

Carica papaya is an important fruit with its seeds used in the treatment of ulcer in Nigeria. This study investigated the anti-ulcerogenic and antioxidant activities of aqueous extract of Carica papaya seed against indomethacin-induced peptic ulcer in male rats. Thirty male rats were separated into 6 groups (A-F) of five rats each. For 14 d before ulcer induction with indomethacin, groups received once daily oral doses of vehicle (distilled water), cimetidine 200 mg/kg body weight (BW), or aqueous extract of C. papaya seed at doses of 100, 150 or 200 mg/kg BW (groups A, B, C, D, E and F, respectively). Twenty-four hours after the last treatment, groups B, C, D, E and F were treated with 100 mg/kg BW of indomethacin to induce ulcer formation. Carica papaya seed extract significantly (P< 0.05) increased gastric pH and percentage of ulcer inhibition relative to indomethacin-induced ulcer rats. The extract significantly (P< 0.05) decreased gastric acidity, gastric acid output, gastric pepsin secretion, ulcer index and gastric secretion volume relative to group B. These results were similar to that achieved by pretreatment with cimetidine. Specific activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase in the extract-treated groups (D, E and F) were increased significantly over the group B (P< 0.05). Pretreatment with the seed extract protected rats from the indomethacin-mediated decrease in enzyme function experienced by the group B. Similarly, indomethacin-mediated decrease in reduced glutathione level and indomethacin-mediated increase in malondialdehyde were reversed by Carica papaya extract. In this study, pretreatment with aqueous extract of Carica papaya seed exhibited anti-ulcerogenic and antioxidant effects, which may be due to the enhanced antioxidant enzymes.

Pharmacological characterization of the inhibitory activity of beta h-endorphin (beta h-EP), [Arg9,19,24,28,29]-beta h-EP, [Gln8,Gly31]-beta h-EP-Gly-Gly-NH2, in the neuroeffector junction of the mouse vas deferens.

PubMed

Valenzuela, R; Li, C H; Huidobro-Toro, J P

1991-08-01

The inhibitory opioid activities of beta h-endorphin (beta h-EP), its structurally related peptide analogues [Gln8,Gly31]-beta h-EP-Gly-Gly-NH2 (Gly-Gly-beta h-EP), [Arg9,19,24,28,29]-beta h-EP (Arg-beta h-EP) and methionine enkephalin have been examined in the electrically stimulated mouse vas deferens bioassay. All four peptides behaved as full agonists; methionine enkephalin was the most potent followed by Arg-beta h-EP, beta h-EP and Gly-Gly-beta h-EP. Neither Gly-Gly-beta h-EP nor Arg-beta h-EP antagonized the inhibitory action of beta h-EP or methionine enkephalin. An hour of tissue exposure to 30 nM beta-funaltrexamine followed by thorough washing, displaced to the right, in a parallel fashion, the concentration-response curves of beta h-EP and analogues. Whereas the displacement of the concentration response curves was 8 to 10-fold for beta h-EP and Arg-beta h-EP, it was only about 3-fold for Gly-Gly-beta h-EP and methionine enkephalin. Naltrindole was the most potent antagonist of methionine enkephalin with an apparent pA2 of 9.4; its potency as an antagonist of beta h-EP and related analogues was approximately one-tenth of this with pA2 values approximately 8.5. Norbinaltorphimine also antagonized the action of the opioid peptides with pA2 values close to 7.8.

Effect of gastric pH on erlotinib pharmacokinetics in healthy individuals: omeprazole and ranitidine.

PubMed

Kletzl, Heidemarie; Giraudon, Mylene; Ducray, Patricia Sanwald; Abt, Markus; Hamilton, Marta; Lum, Bert L

2015-06-01

The aim of this study was to evaluate the effect of coadministration of acid-reducing agents on the pharmacokinetic exposure of orally administered epidermal growth factor receptor inhibitor erlotinib, a drug that displays pH-dependent solubility. Two studies were conducted, the first with the proton pump inhibitor omeprazole and the second with the H2-receptor antagonist ranitidine. Twenty-four healthy male and female volunteers were enrolled in each study. Erlotinib was administered as a single oral 150 mg dose on day 1. After the washout a subsequent study period evaluated 150 mg erlotinib administered with the acid-reducing agent. Omeprazole (40 mg once daily) was given on days 11-14, concomitantly with erlotinib on day 15, and for two additional days (days 16-17). In the ranitidine study, on day 13, participants were randomized to either concomitant dosing (treatment B) or staggered administration (treatment C) of erlotinib and ranitidine and crossed over to the other treatment starting on day 27. For treatment B, ranitidine (300 mg once daily) was administered in the morning for 5 days, 2 h before erlotinib. For treatment C, ranitidine was administered as a divided dose (150 mg twice daily) for 5 days, with erlotinib given 10 h after the previous evening dose and 2 h before the next ranitidine morning dose. Plasma samples were obtained for determination of the concentrations of erlotinib and its metabolite OSI-420, following each erlotinib dose. All participants were monitored for safety and tolerability. The geometric mean ratios of AUC0-∞ and Cmax for erlotinib and AUC0-last and Cmax for OSI-420 were substantially decreased when erlotinib was dosed with omeprazole. The estimated mean ratio (90% confidence interval) for erlotinib was 0.54 (0.49-0.59) for AUC0-∞ and 0.39 (0.32-0.48) for Cmax. For OSI-420, the estimated mean ratio was 0.42 (0.37-0.48) for AUC0-last and 0.31 (0.24-0.41) for Cmax. AUC0-∞ and Cmax for erlotinib were substantially decreased by 33 and 54%, respectively, upon coadministration with ranitidine, but the decrease was only 15 and 17% when ranitidine and erlotinib were given staggered. Similar results were observed for the metabolite OSI-420. Erlotinib was generally well-tolerated alone or in combination with omeprazole or ranitidine. Erlotinib pharmacokinetic exposure was substantially reduced upon coadministration with omeprazole and ranitidine, but not when administered with a staggered dosing approach to ranitidine. Therefore, it is recommended that the concomitant use of erlotinib with proton pump inhibitors be avoided. If treatment with an H2-receptor antagonist such as ranitidine is required, erlotinib must be administered 10 h after the H2-receptor antagonist dosing and at least 2 h before the next dose of the H2-receptor antagonist.

Use of histamine H2 receptor antagonists and outcomes in patients with heart failure: a nationwide population-based cohort study.

PubMed

Adelborg, Kasper; Sundbøll, Jens; Schmidt, Morten; Bøtker, Hans Erik; Weiss, Noel S; Pedersen, Lars; Sørensen, Henrik Toft

2018-01-01

Histamine H 2 receptor activation promotes cardiac fibrosis and apoptosis in mice. However, the potential effectiveness of histamine H 2 receptor antagonists (H2RAs) in humans with heart failure is largely unknown. We examined the association between H2RA initiation and all-cause mortality among patients with heart failure. Using Danish medical registries, we conducted a nationwide population-based active-comparator cohort study of new users of H2RAs and proton pump inhibitors (PPIs) after first-time hospitalization for heart failure during the period 1995-2014. Hazard ratios (HRs) for all-cause mortality and hospitalization due to worsening of heart failure, adjusting for age, sex, and time between heart failure diagnosis and initiation of PPI or H2RA therapy, index year, comorbidity, cardiac surgery, comedications, and socioeconomic status were computed based on Cox regression analysis. Our analysis included 42,902 PPI initiators (median age 78 years, 46% female) and 3,296 H2RA initiators (median age 76 years, 48% female). Mortality risk was lower among H2RA initiators than PPI initiators after 1 year (26% vs 31%) and 5 years (60% vs 66%). In multivariable analyses, the 1-year HR was 0.80 (95% CI, 0.74-0.86) and the 5-year HR was 0.85 (95% CI, 0.80-0.89). These findings were consistent after propensity score matching and for ischemic and nonischemic heart failure, as for sex and age groups. The rate of hospitalization due to worsening of heart failure was lower among H2RA initiators than PPI initiators. In patients with heart failure, H2RA initiation was associated with 15%-20% lower mortality than PPI initiation.

8-Substituted 1,3-dimethyltetrahydropyrazino[2,1-f]purinediones: Water-soluble adenosine receptor antagonists and monoamine oxidase B inhibitors.

PubMed

Brunschweiger, Andreas; Koch, Pierre; Schlenk, Miriam; Rafehi, Muhammad; Radjainia, Hamid; Küppers, Petra; Hinz, Sonja; Pineda, Felipe; Wiese, Michael; Hockemeyer, Jörg; Heer, Jag; Denonne, Frédéric; Müller, Christa E

2016-11-01

Multitarget approaches, i.e., addressing two or more targets simultaneously with a therapeutic agent, are hypothesized to offer additive therapeutic benefit for the treatment of neurodegenerative diseases. Validated targets for the treatment of Parkinson's disease are, among others, the A 2A adenosine receptor (AR) and the enzyme monoamine oxidase B (MAO-B). Additional blockade of brain A 1 ARs may also be beneficial. We recently described 8-benzyl-substituted tetrahydropyrazino[2,1-f]purinediones as a new lead structure for the development of such multi-target drugs. We have now designed a new series of tetrahydropyrazino[2,1-f]purinediones to extensively explore their structure-activity-relationships. Several compounds blocked human and rat A 1 and A 2A ARs at similar concentrations representing dual A 1 /A 2A antagonists with high selectivity versus the other AR subtypes. Among the best dual A 1 /A 2A AR antagonists were 8-(3-(4-chlorophenyl)propyl)-1,3-dimethyl-6,7,8,9-tetrahydropyrazino[2,1-f]purine-2,4(1H,3H)-dione (41, K i human A 1 : 65.5nM, A 2A : 230nM; K i rat A 1 : 352nM, A 2A : 316nM) and 1,3-dimethyl-8-((2-(thiophen-2-yl)thiazol-4-yl)methyl)-6,7,8,9-tetrahydropyrazino[2,1-f]purine-2,4(1H,3H)-dione (57, K i human A 1 : 642nM, A 2A : 203nM; K i rat A 1 : 166nM, A 2A : 121nM). Compound 57 was found to be well water-soluble (0.7mg/mL) at a physiological pH value of 7.4. One of the new compounds showed triple-target inhibition: (R)-1,3-dimethyl-8-(2,1,3,4-tetrahydronaphthalen-1-yl)-6,7,8,9-tetrahydropyrazino[2,1-f]purine-2,4(1H,3H)-dione (49) was about equipotent at A 1 and A 2A ARs and at MAO-B (K i human A 1 : 393nM, human A 2A : 595nM, IC 50 human MAO-B: 210nM) thus allowing future in vivo explorations of the intended multi-target approach. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modulation of 3H-noradrenaline release by presynaptic opioid, cannabinoid and bradykinin receptors and β-adrenoceptors in mouse tissues

PubMed Central

Trendelenburg, A U; Cox, S L; Schelb, V; Klebroff, W; Khairallah, L; Starke, K

2000-01-01

Release-modulating opioid and cannabinoid (CB) receptors, β-adrenoceptors and bradykinin receptors at noradrenergic axons were studied in mouse tissues (occipito-parietal cortex, heart atria, vas deferens and spleen) preincubated with 3H-noradrenaline. Experiments using the OP1 receptor-selective agonists DPDPE and DSLET, the OP2-selective agonists U50488H and U69593, the OP3-selective agonist DAMGO, the ORL1 receptor-selective agonist nociceptin, and a number of selective antagonists showed that the noradrenergic axons innervating the occipito-parietal cortex possess release-inhibiting OP3 and ORL1 receptors, those innervating atria OP1, ORL1 and possibly OP3 receptors, and those innervating the vas deferens all four opioid receptor types. Experiments using the non-selective CB agonists WIN 55,212-2 and CP 55,940 and the CB1-selective antagonist SR 141716A indicated that the noradrenergic axons of the vas deferens possess release-inhibiting CB1 receptors. Presynaptic CB receptors were not found in the occipito-parietal cortex, in atria or in the spleen. Experiments using the non-selective β-adrenoceptor agonist isoprenaline and the β2-selective agonist salbutamol, as well as subtype-selective antagonists, demonstrated the occurrence of release-enhancing β2-adrenoceptors at the sympathetic axons of atria and the spleen, but demonstrated their absence in the occipito-parietal cortex and the vas deferens. Experiments with bradykinin and the B2-selective antagonist Hoe 140 showed the operation of release-enhancing B2 receptors at the sympathetic axons of atria, the vas deferens and the spleen, but showed their absence in the occipito-parietal cortex. The experiments document a number of new presynaptic receptor locations. They confirm and extend the existence of marked tissue and species differences in presynaptic receptors at noradrenergic neurons. PMID:10807669

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.

Inhibition of /sup 3/H-leukotriene D4 binding to guinea pig lung receptors by the novel leukotriene antagonist ICI 198,615

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aharony, D.; Falcone, R.C.; Krell, R.D.

1987-12-01

The specific binding of (/sup 3/H)5(S)hydroxy-6(R)-S-cysteinylglycyl -7(E),9(E),11(Z),14(Z)-eicosatetraenoic acid ((/sup 3/H)LTD4) to receptors on guinea pig lung parenchymal membranes and its inhibition by ICI 198,615, a representative example of a new class of leukotriene antagonists, was characterized by a receptor-ligand binding assay. (/sup 3/H)LTD4 bound specifically and rapidly (Kon = 0.29 +/- 0.6 nM-1.min-1) reaching equilibrium within 15 min. The rate of binding was greatly inhibited in the presence of ICI 198,615. Excess LTD4 or ICI 198,615 slowly (t1/2 = 20 min) dissociated about 70% of the receptor-bound (/sup 3/H)LTD4, whereas in combination with GTP analogs, both induced a rapid (t1/2more » less than 5 min) and full dissociation. Equilibrium saturation analysis of (/sup 3/H)LTD4 binding demonstrated a saturable (Bmax = 1014 +/- 174 fmol/mg) and high affinity (Kd = 0.43 +/- 0.09 nM) binding site. A high degree of stereoselectivity was demonstrated with inhibition of binding by the stereoisomers of LTD4: S,R much greater than R,R greater than R,S much greater than S,S. The rank order for inhibition of binding by peptide leukotriene was: LTD4 greater than 5(S)-hydroxy-6(R)-S-cysteinyl-7(E),9(E),11(Z),14(Z)-eicosatetraenoic acid much greater than 5(S)hydroxy-6(R)-S-glutathionyl-7(E),9(E),11(Z),14(Z)-eicosatetraenoic acid (potency ratios were: 1:4:590). In competition assays, ICI 198,615 competitively inhibited binding of (/sup 3/H)LTD4 (Ki = 0.27 +/- 0.16 nM) and was 2300-fold and 3100-fold more potent than LY171883 or FPL55712. These data, together with results obtained previously in functional receptor assays, illustrate that this new class of leukotriene antagonists are the most potent and selective competitive antagonists of LTD4 receptors yet described.« less

Antinociceptive synergism of MD-354 and clonidine. Part II. The alpha-adrenoceptor component.

PubMed

Young, Shawquia; Vainio, Minna; Scheinin, Mika; Dukat, Małgorzata

2010-08-01

Previously, we reported that antinociceptive synergism of a 5-HT(3)/alpha(2)-adrenoceptor ligand MD-354 (m-chlorophenylguanidine) and clonidine combination occurs, in part, through a 5-HT(3) receptor antagonist mechanism. In the present investigation, a possible role for alpha(2)-adrenoceptors was examined. Mechanistic studies using yohimbine (a subtype non-selective alpha(2)-adrenoceptor antagonist), BRL 44408 (a preferential alpha(2A)-adrenoceptor antagonist) and imiloxan (a preferential alpha(2B/C)-adrenoceptor antagonist) on the antinociceptive actions of a MD-354/clonidine combination were conducted. Subcutaneous pre-treatment with all three antagonists inhibited the antinociceptive synergism of MD-354 and clonidine in the mouse tail-flick assay in a dose-dependent manner (AD(50) = 0.33, 2.1, and 0.17 mg/kg, respectively). Enhancement of clonidine antinociception by MD-354 did not potentiate clonidine's locomotor suppressant activity in a mouse locomotor assay. When [ethyl-3H]RS-79948-197 was used as radioligand, MD-354 displayed almost equal affinity to alpha(2A)- and alpha(2B)-adrenoceptors (K(i) = 110 and 220 nM) and showed lower affinity at alpha(2C)-adrenoceptors (K(i) = 4,700 nM). MD-354 had no subtype-selectivity for the alpha(2)-adrenoceptor subtypes as an antagonist in functional [35S]GTPgammaS binding assays. MD-354 was a weak partial agonist at alpha(2A)-adrenoceptors. Overall, in addition to the 5-HT(3) receptor component, the present investigation found MD-354 to be a weak partial alpha(2A)-adrenoceptor agonist that enhances clonidine's thermal antinociceptive actions through an alpha(2)-adrenoceptor-mediated mechanism without augmenting sedation.

Multiple elements of the allergic arm of the immune response modulate autoimmune demyelination

PubMed Central

Pedotti, Rosetta; DeVoss, Jason J.; Youssef, Sawsan; Mitchell, Dennis; Wedemeyer, Jochen; Madanat, Rami; Garren, Hideki; Fontoura, Paulo; Tsai, Mindy; Galli, Stephen J.; Sobel, Raymond A.; Steinman, Lawrence

2003-01-01

Analysis of mRNA from multiple sclerosis lesions revealed increased amounts of transcripts for several genes encoding molecules traditionally associated with allergic responses, including prostaglandin D synthase, histamine receptor type 1 (H1R), platelet activating factor receptor, Ig Fc ɛ receptor 1 (FcɛRI), and tryptase. We now demonstrate that, in the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), mediated by T helper 1 (Th1) T cells, histamine receptor 1 and 2 (H1R and H2R) are present on inflammatory cells in brain lesions. Th1 cells reactive to myelin proteolipid protein expressed more H1R and less H2R than Th2 cells. Pyrilamine, an H1R antagonist, blocked EAE, and the platelet activating factor receptor antagonist CV6209 reduced the severity of EAE. EAE severity was also decreased in mice with disruption of the genes encoding Ig FcγRIII or both FcγRIII and FcɛRI. Prostaglandin D synthase and tryptase transcripts were elevated in EAE brain. Taken together, these data reveal extensive involvement of elements of the immune response associated with allergy in autoimmune demyelination. The pathogenesis of demyelination must now be viewed as encompassing elements of both Th1 responses and “allergic” responses. PMID:12576552

4-Benzothiazole-7-hydroxyindolinyl diaryl ureas are potent P2Y1 antagonists with favorable pharmacokinetics: low clearance and small volume of distribution.

PubMed

Qiao, Jennifer X; Wang, Tammy C; Hiebert, Sheldon; Hu, Carol H; Schumacher, William A; Spronk, Steven A; Clark, Charles G; Han, Ying; Hua, Ji; Price, Laura A; Shen, Hong; Chacko, Silvi A; Everlof, Gerry; Bostwick, Jeffrey S; Steinbacher, Thomas E; Li, Yi-Xin; Huang, Christine S; Seiffert, Dietmar A; Rehfuss, Robert; Wexler, Ruth R; Lam, Patrick Y S

2014-10-01

Current antithrombotic discovery efforts target compounds that are highly efficacious in thrombus reduction with less bleeding liability than the standard of care. Preclinical data suggest that P2Y1 antagonists may have lower bleeding liabilities than P2Y12 antagonists while providing similar antithrombotic efficacy. This article describes our continuous SAR efforts in a series of 7-hydroxyindolinyl diaryl ureas. When dosed orally, 4-trifluoromethyl-7-hydroxy-3,3-dimethylindolinyl analogue 4 was highly efficacious in a model of arterial thrombosis in rats with limited bleeding. The chemically labile CF3 group in 4 was then transformed to various groups via a novel one-step synthesis, yielding a series of potent P2Y1 antagonists. Among them, the 4-benzothiazole-substituted indolines had desirable PK properties in rats, specifically, low clearance and small volume of distribution. In addition, compound 40 had high i.v. exposure and modest bioavailability, giving it the best overall profile. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fevipiprant (QAW039), a Slowly Dissociating CRTh2 Antagonist with the Potential for Improved Clinical Efficacy.

PubMed

Sykes, David A; Bradley, Michelle E; Riddy, Darren M; Willard, Elizabeth; Reilly, John; Miah, Asadh; Bauer, Carsten; Watson, Simon J; Sandham, David A; Dubois, Gerald; Charlton, Steven J

2016-05-01

Here we describe the pharmacologic properties of a series of clinically relevant chemoattractant receptor-homologous molecules expressed on T-helper type 2 (CRTh2) receptor antagonists, including fevipiprant (NVP-QAW039 or QAW039), which is currently in development for the treatment of allergic diseases. [(3)H]-QAW039 displayed high affinity for the human CRTh2 receptor (1.14 ± 0.44 nM) expressed in Chinese hamster ovary cells, the binding being reversible and competitive with the native agonist prostaglandin D2(PGD2). The binding kinetics of QAW039 determined directly using [(3)H]-QAW039 revealed mean kinetic on (kon) and off (koff) values for QAW039 of 4.5 × 10(7)M(-1)min(-1)and 0.048 minute(-1), respectively. Importantly, thekoffof QAW039 (half-life = 14.4 minutes) was >7-fold slower than the slowest reference compound tested, AZD-1981. In functional studies, QAW039 behaved as an insurmountable antagonist of PGD2-stimulated [(35)S]-GTPγS activation, and its effects were not fully reversed by increasing concentrations of PGD2after an initial 15-minute incubation period. This behavior is consistent with its relatively slow dissociation from the human CRTh2 receptor. In contrast for the other ligands tested this time-dependent effect on maximal stimulation was fully reversed by the 15-minute time point, whereas QAW039's effects persisted for >180 minutes. All CRTh2 antagonists tested inhibited PGD2-stimulated human eosinophil shape change, but importantly QAW039 retained its potency in the whole-blood shape-change assay relative to the isolated shape change assay, potentially reflective of its relatively slower off rate from the CRTh2 receptor. QAW039 was also a potent inhibitor of PGD2-induced cytokine release in human Th2 cells. Slow CRTh2 antagonist dissociation could provide increased receptor coverage in the face of pathologic PGD2concentrations, which may be clinically relevant. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Ibudilast attenuates astrocyte apoptosis via cyclic GMP signalling pathway in an in vitro reperfusion model

PubMed Central

Takuma, K; Lee, E; Enomoto, R; Mori, K; Baba, A; Matsuda, T

2001-01-01

We examined the effect of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine (ibudilast), which has been clinically used for bronchial asthma and cerebrovascular disorders, on cell viability induced in a model of reperfusion injury. Ibudilast at 10 – 100 μM significantly attenuated the H2O2-induced decrease in cell viability. Ibudilast inhibited the H2O2-induced cytochrome c release, caspase-3 activation, DNA ladder formation and nuclear condensation, suggesting its anti-apoptotic effect. Phosphodiesterase inhibitors such as theophylline, pentoxyfylline, vinpocetine, dipyridamole and zaprinast, which increased the guanosine-3′,5′-cyclic monophosphate (cyclic GMP) level, and dibutyryl cyclic GMP attenuated the H2O2-induced injury in astrocytes. Ibudilast increased the cyclic GMP level in astrocytes. The cyclic GMP-dependent protein kinase inhibitor KT5823 blocked the protective effects of ibudilast and dipyridamole on the H2O2-induced decrease in cell viability, while the cyclic AMP-dependent protein kinase inhibitor KT5720, the cyclic AMP antagonist Rp-cyclic AMPS, the mitogen-activated protein/extracellular signal-regulated kinase inhibitor PD98059 and the leukotriene D4 antagonist LY 171883 did not. KT5823 also blocked the effect of ibudilast on the H2O2-induced cytochrome c release and caspase-3-like protease activation. These findings suggest that ibudilast prevents the H2O2-induced delayed apoptosis of astrocytes via a cyclic GMP, but not cyclic AMP, signalling pathway. PMID:11454657

Interaction of a vasopressin antagonist with vasopressin receptors in the septum of the rat brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorsa, D.M.; Brot, M.D.; Shewey, L.M.

1988-01-01

The ability of d(CH2)5-Tyr(Me)-arginine-8-vasopressin, an antagonist of peripheral pressoric (V1-type) vasopressin receptors, to label vasopressin binding sites in the septum of the rat brain was evaluated. Using crude membrane preparations from the septum, /sup 3/H-arginine-8-vasopressin (AVP) specifically labels a single class of binding sites with a Kd of 2.9 nM and maximum binding site concentration of 19.8 fmole/mg protein. /sup 3/H-Antag also labels a single class of membrane sites but with higher affinity (Kd = 0.47 nM) and lower capacity (10.1 fmole/mg protein) than /sup 3/H-AVP. The rank order of potency of various competitor peptides for /sup 3/H-AVP and /supmore » 3/H-Antag binding was similar. Oxytocin was 100-1,000 fold less potent than AVP in competing for binding with both ligands. /sup 3/H-AVP and /sup 3/H-Antag showed similar labeling patterns when incubated with septal tissue slices. Unlabeled Antag also effectively antagonized vasopressin-stimulated phosphatidylinositol hydrolysis in septal tissue slices.« less

Potent and long-acting corticotropin releasing factor (CRF) receptor 2 selective peptide competitive antagonists.

PubMed

Rivier, J; Gulyas, J; Kirby, D; Low, W; Perrin, M H; Kunitake, K; DiGruccio, M; Vaughan, J; Reubi, J C; Waser, B; Koerber, S C; Martinez, V; Wang, L; Taché, Y; Vale, W

2002-10-10

We present evidence that members of the corticotropin releasing factor (CRF) family assume distinct structures when interacting with the CRF(1) and CRF(2) receptors. Predictive methods, physicochemical measurements, and structure-activity relationship studies have suggested that CRF, its family members, and competitive antagonists such as astressin [cyclo(30-33)[DPhe(12),Nle(21),Glu(30),Lys(33),Nle(38)]hCRF((12-41))] assume an alpha-helical conformation when interacting with their receptors. We had shown that alpha-helical CRF((9-41)) and sauvagine showed some selectivity for CRF receptors other than that responsible for ACTH secretion(1) and later for CRF2.(2) More recently, we suggested the possibility of a helix-turn-helix motif around a turn encompassing residues 30-33(3) that would confer high affinity for both CRF(1) and CRF(2)(2,4) in agonists and antagonists of all members of the CRF family.(3) On the other hand, the substitutions that conferred ca. 100-fold CRF(2) selectivity to the antagonist antisauvagine-30 [[DPhe(11),His(12)]sauvagine((11-40))] did not confer such property to the corresponding N-terminally extended agonists. We find here that a Glu(32)-Lys(35) side chain to side chain covalent lactam constraint in hCRF and the corresponding Glu(31)-Lys(34) side chain to side chain covalent lactam constraint in sauvagine yield potent ligands that are selective for CRF(2). Additionally, we introduced deletions and substitutions known to increase duration of action to yield antagonists such as cyclo(31-34)[DPhe(11),His(12),C(alpha)MeLeu(13,39),Nle(17),Glu(31),Lys(34)]Ac-sauvagine((8-40)) (astressin(2)-B) with CRF(2) selectivities greater than 100-fold. CRF receptor autoradiography was performed in rat tissue known to express CRF(2) and CRF(1) in order to confirm that astressin(2)-B could indeed bind to established CRF(2) but not CRF(1) receptor-expressing tissues. Extended duration of action of astressin(2)-B vs that of antisauvagine-30 is demonstrated in the CRF(2)-mediated animal model whereby the inhibition of gastric emptying of a solid meal in mice by urocortin administered intraperitoneally at time zero is antagonized by the administration of astressin(2)-B but not by antisauvagine-30 at times -3 and -6 h while both peptides are effective when given 10 min before urocortin.

3-Arylpiperazinylethyl-1H-pyrrolo[2,3-d]pyrimidine-2,4(3H,7H)-dione derivatives as novel, high-affinity and selective alpha(1)-adrenoceptor ligands.

PubMed

Pittalà, Valeria; Romeo, Giuseppe; Salerno, Loredana; Siracusa, Maria Angela; Modica, Maria; Materia, Luisa; Mereghetti, Ilario; Cagnotto, Alfredo; Mennini, Tiziana; Marucci, Gabriella; Angeli, Piero; Russo, Filippo

2006-01-01

The discovery of a new series of selective and high-affinity alpha(1)-adrenoceptor (alpha(1)-AR) ligands, characterized by a 1H-pyrrolo[2,3-d]-pyrimidine-2,4(3H,7H)-dione system, is described in this paper. Some synthesized compounds, including 20, 22, and 30, displayed affinity in the nanomolar range for alpha(1)-ARs and substantial selectivity with respect to 5-HT(1A) and dopaminergic D(1) and D(2) receptors. Functional assays, performed on selected derivatives, showed antagonistic properties.

A predictive in vitro model of the impact of drugs with anticholinergic properties on human neuronal and astrocytic systems.

PubMed

Woehrling, Elizabeth K; Parri, H Rheinallt; Tse, Erin H Y; Hill, Eric J; Maidment, Ian D; Fox, G Christopher; Coleman, Michael D

2015-01-01

The link between off-target anticholinergic effects of medications and acute cognitive impairment in older adults requires urgent investigation. We aimed to determine whether a relevant in vitro model may aid the identification of anticholinergic responses to drugs and the prediction of anticholinergic risk during polypharmacy. In this preliminary study we employed a co-culture of human-derived neurons and astrocytes (NT2.N/A) derived from the NT2 cell line. NT2.N/A cells possess much of the functionality of mature neurons and astrocytes, key cholinergic phenotypic markers and muscarinic acetylcholine receptors (mAChRs). The cholinergic response of NT2 astrocytes to the mAChR agonist oxotremorine was examined using the fluorescent dye fluo-4 to quantitate increases in intracellular calcium [Ca2+]i. Inhibition of this response by drugs classified as severe (dicycloverine, amitriptyline), moderate (cyclobenzaprine) and possible (cimetidine) on the Anticholinergic Cognitive Burden (ACB) scale, was examined after exposure to individual and pairs of compounds. Individually, dicycloverine had the most significant effect regarding inhibition of the astrocytic cholinergic response to oxotremorine, followed by amitriptyline then cyclobenzaprine and cimetidine, in agreement with the ACB scale. In combination, dicycloverine with cyclobenzaprine had the most significant effect, followed by dicycloverine with amitriptyline. The order of potency of the drugs in combination frequently disagreed with predicted ACB scores derived from summation of the individual drug scores, suggesting current scales may underestimate the effect of polypharmacy. Overall, this NT2.N/A model may be appropriate for further investigation of adverse anticholinergic effects of multiple medications, in order to inform clinical choices of suitable drug use in the elderly.

A Predictive In Vitro Model of the Impact of Drugs with Anticholinergic Properties on Human Neuronal and Astrocytic Systems

PubMed Central

Woehrling, Elizabeth K.; Parri, H. Rheinallt; Tse, Erin H. Y.; Hill, Eric J.; Maidment, Ian D.; Fox, G. Christopher; Coleman, Michael D.

2015-01-01

The link between off-target anticholinergic effects of medications and acute cognitive impairment in older adults requires urgent investigation. We aimed to determine whether a relevant in vitro model may aid the identification of anticholinergic responses to drugs and the prediction of anticholinergic risk during polypharmacy. In this preliminary study we employed a co-culture of human-derived neurons and astrocytes (NT2.N/A) derived from the NT2 cell line. NT2.N/A cells possess much of the functionality of mature neurons and astrocytes, key cholinergic phenotypic markers and muscarinic acetylcholine receptors (mAChRs). The cholinergic response of NT2 astrocytes to the mAChR agonist oxotremorine was examined using the fluorescent dye fluo-4 to quantitate increases in intracellular calcium [Ca2+]i. Inhibition of this response by drugs classified as severe (dicycloverine, amitriptyline), moderate (cyclobenzaprine) and possible (cimetidine) on the Anticholinergic Cognitive Burden (ACB) scale, was examined after exposure to individual and pairs of compounds. Individually, dicycloverine had the most significant effect regarding inhibition of the astrocytic cholinergic response to oxotremorine, followed by amitriptyline then cyclobenzaprine and cimetidine, in agreement with the ACB scale. In combination, dicycloverine with cyclobenzaprine had the most significant effect, followed by dicycloverine with amitriptyline. The order of potency of the drugs in combination frequently disagreed with predicted ACB scores derived from summation of the individual drug scores, suggesting current scales may underestimate the effect of polypharmacy. Overall, this NT2.N/A model may be appropriate for further investigation of adverse anticholinergic effects of multiple medications, in order to inform clinical choices of suitable drug use in the elderly. PMID:25738989

Characterization of the slow calcium channel binding sites for ( sup 3 H)SR 33557 in rat heart sarcolemmal membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatelain, P.; Beaufort, P.; Meysmans, L.

1991-01-01

SR 33557 represents a new class of compounds (indolizine sulfone) that inhibit L-type Ca2+ channels. ({sup 3}H)SR 33557 has been shown to bind with high affinity (Kd congruent to 0.36 nM, calculated from saturation isotherms and association/dissociation kinetics) to a single class of sites in a purified preparation of rat cardiac sarcolemmal membranes. The binding was found to be saturable and reversible. The maximal binding capacity was in approximately 1:1 stoichiometry with that of other Ca2+ channel antagonists. Various divalent cations (Mg2+, Mn2+, Ca2+, Ba2+, and Cd2+) were shown to inhibit specific ({sup 3}H)SR 33557 binding, with Cd2+ being themore » most potent. Among several receptor or channel ligands (including omega-conotoxin and Na+ and K+ channel modulators), only the L-type Ca2+ channel antagonists were found to displace ({sup 3}H)SR 33557. However, dihydropyridines, phenylalkylamines, benzothiazepines, and diphenylbutylpiperidines were found to inhibit ({sup 3}H)SR 33557 in a noncompetitive manner as demonstrated by displacement and saturation experiments in addition to dissociation kinetics. From these results, we suggest that SR 33557 binds with high affinity to a unique site on the L-type Ca2+ channel found in rat cardiac sarcolemmal membranes.« less

Comparison of the ultrashort gonadotropin-releasing hormone agonist-antagonist protocol with microdose flare -up protocol in poor responders: a preliminary study.

PubMed

Berker, Bülent; Duvan, Candan İltemir; Kaya, Cemil; Aytaç, Ruşen; Satıroğlu, Hakan

2010-01-01

To determine the potential effect of the ultrashort gonadotropin-releasing hormone (GnRH) agonist/GnRH antagonist protocol versus the microdose GnRH agonist protocol in poor responders undergoing intracytoplasmic sperm injection (ICSI). The patients in the Agonist-Antagonist Group (n=41) were administered the ultrashort GnRH-agonist/ antagonist protocol, while the patients in the Microdose Group (n=41) were stimulated according to the microdose flare-up protocol. The mean number of mature oocytes retrieved was the primary outcome measure. Fertilization rate, implantation rate per embryo and clinical pregnancy rates were secondary outcome measures. There was no differenc between the mean number of mature oocytes retrieved in the two groups. There were also no statistical differences between the two groups in terms of peak serum E2 level, canceled cycles, endometrial thickness on hCG day, number of 2 pronucleus and number of embryos transferred. However, the total gonadotropin consumption and duration of stimulation were significantly higher with the Agonist-Antagonist Group compared with the Microdose Group. The implantation and clinical pregnancy rates were similar between the two groups. Despite the high dose of gonadotropin consumption and longer duration of stimulation with the ultrashort GnRH agonist/ antagonist protocol, it seems that the Agonist-Antagonist Protocol is not inferior to the microdose protocol in poor responders undergoing ICSI.

Human trabecular meshwork cells express BMP antagonist mRNAs and proteins.

PubMed

Tovar-Vidales, Tara; Fitzgerald, Ashley M; Clark, Abbot F

2016-06-01

Glaucoma patients have elevated aqueous humor and trabecular meshwork (TM) levels of transforming growth factor-beta2 (TGF-β2). TGF-β2 has been associated with increased extracellular matrix (ECM) deposition (i.e. fibronectin), which is attributed to the increased resistance of aqueous humor outflow through the TM. We have previously demonstrated that bone morphogenetic protein (BMP) 4 selectively counteracts the profibrotic effect of TGF-β2 with respect to ECM synthesis in the TM, and this action is reversed by the BMP antagonist gremlin. Thus, the BMP and TGF-β signaling pathways antagonize each other's antifibrotic and profibrotic roles. The purpose of this study was to determine whether cultured human TM cells: (a) express other BMP antagonists including noggin, chordin, BMPER, BAMBI, Smurf1 and 2, and (b) whether expression of these proteins is regulated by exogenous TGF-β2 treatment. Primary human trabecular meshwork (TM) cells were grown to confluency and treated with TGF-β2 (5 ng/ml) for 24 or 48 h in serum-free medium. Untreated cell served as controls. qPCR and Western immunoblots (WB) determined that human TM cells expressed mRNAs and proteins for the BMP antagonist proteins: noggin, chordin, BMPER, BAMBI, and Smurf1/2. Exogenous TGF-β2 decreased chordin, BMPER, BAMBI, and Smurf1 mRNA and protein expression. In contrast, TGF-β2 increased secreted noggin and Smurf2 mRNA and protein levels. BMP antagonist members are expressed in the human TM. These molecules may be involved in the normal function of the TM as well as TM pathogenesis. Altered expression of BMP antagonist members may lead to functional changes in the human TM. Copyright © 2016 Elsevier Ltd. All rights reserved.

A selective estrogen receptor modulator for the treatment of hot flushes.

PubMed

Wallace, Owen B; Lauwers, Kenneth S; Dodge, Jeffrey A; May, Scott A; Calvin, Joel R; Hinklin, Ronald; Bryant, Henry U; Shetler, Pamela K; Adrian, Mary D; Geiser, Andrew G; Sato, Masahiko; Burris, Thomas P

2006-02-09

A selective estrogen receptor modulator (SERM) for the potential treatment of hot flushes is described. (R)-(+)-7,9-difluoro-5-[4-(2-piperidin-1-ylethoxy)phenyl]-5H-6-oxachrysen-2-ol, LSN2120310, potently binds ERalpha and ERbeta and is an antagonist in MCF-7 breast adenocarcinoma and Ishikawa uterine cancer cell lines. The compound is a potent estrogen antagonist in the rat uterus. In ovariectomized rats, the compound lowers cholesterol, maintains bone mineral density, and is efficacious in a morphine dependent rat model of hot flush efficacy.

Involvement of Cannabinoid Signaling in Vincristine-Induced Gastrointestinal Dysmotility in the Rat.

PubMed

Vera, Gema; López-Pérez, Ana E; Uranga, José A; Girón, Rocío; Martín-Fontelles, Ma Isabel; Abalo, Raquel

2017-01-01

Background: In different models of paralytic ileus, cannabinoid receptors are overexpressed and endogenous cannabinoids are massively released, contributing to gastrointestinal dysmotility. The antitumoral drug vincristine depresses gastrointestinal motility and a similar mechanism could participate in this effect. Therefore, our aim was to determine, using CB 1 and CB 2 antagonists, whether an increased endocannabinoid tone is involved in vincristine-induced gastrointestinal ileus. Methods: First, we confirmed the effects of vincristine on the gut mucosa, by conventional histological techniques, and characterized its effects on motility, by radiographic means. Conscious male Wistar rats received an intraperitoneal injection of vincristine (0.1-0.5 mg/kg), and barium sulfate (2.5 ml; 2 g/ml) was intragastrically administered 0, 24, or 48 h later. Serial X-rays were obtained at different time-points (0-8 h) after contrast. X-rays were used to build motility curves for each gastrointestinal region and determine the size of stomach and caecum. Tissue samples were taken for histology 48 h after saline or vincristine (0.5 mg/kg). Second, AM251 (a CB 1 receptor antagonist) and AM630 (a CB 2 receptor antagonist) were used to determine if CB 1 and/or CB 2 receptors are involved in vincristine-induced gastrointestinal dysmotility. Key results: Vincristine induced damage to the mucosa of ileum and colon and reduced gastrointestinal motor function at 0.5 mg/kg. The effect on motor function was particularly evident when the study started 24 h after administration. AM251, but not AM630, significantly prevented vincristine effect, particularly in the small intestine, when administered thrice. AM251 alone did not significantly alter gastrointestinal motility. Conclusions: The fact that AM251, but not AM630, is capable of reducing the effect of vincristine suggests that, like in other experimental models of paralytic ileus, an increased cannabinoid tone develops and is at least partially responsible for the alterations induced by the antitumoral drug on gastrointestinal motor function. Thus, CB 1 antagonists might be useful to prevent/treat ileus induced by vincristine.

Involvement of Cannabinoid Signaling in Vincristine-Induced Gastrointestinal Dysmotility in the Rat

PubMed Central

Vera, Gema; López-Pérez, Ana E.; Uranga, José A.; Girón, Rocío; Martín-Fontelles, Ma Isabel; Abalo, Raquel

2017-01-01

Background: In different models of paralytic ileus, cannabinoid receptors are overexpressed and endogenous cannabinoids are massively released, contributing to gastrointestinal dysmotility. The antitumoral drug vincristine depresses gastrointestinal motility and a similar mechanism could participate in this effect. Therefore, our aim was to determine, using CB1 and CB2 antagonists, whether an increased endocannabinoid tone is involved in vincristine-induced gastrointestinal ileus. Methods: First, we confirmed the effects of vincristine on the gut mucosa, by conventional histological techniques, and characterized its effects on motility, by radiographic means. Conscious male Wistar rats received an intraperitoneal injection of vincristine (0.1–0.5 mg/kg), and barium sulfate (2.5 ml; 2 g/ml) was intragastrically administered 0, 24, or 48 h later. Serial X-rays were obtained at different time-points (0–8 h) after contrast. X-rays were used to build motility curves for each gastrointestinal region and determine the size of stomach and caecum. Tissue samples were taken for histology 48 h after saline or vincristine (0.5 mg/kg). Second, AM251 (a CB1 receptor antagonist) and AM630 (a CB2 receptor antagonist) were used to determine if CB1 and/or CB2 receptors are involved in vincristine-induced gastrointestinal dysmotility. Key results: Vincristine induced damage to the mucosa of ileum and colon and reduced gastrointestinal motor function at 0.5 mg/kg. The effect on motor function was particularly evident when the study started 24 h after administration. AM251, but not AM630, significantly prevented vincristine effect, particularly in the small intestine, when administered thrice. AM251 alone did not significantly alter gastrointestinal motility. Conclusions: The fact that AM251, but not AM630, is capable of reducing the effect of vincristine suggests that, like in other experimental models of paralytic ileus, an increased cannabinoid tone develops and is at least partially responsible for the alterations induced by the antitumoral drug on gastrointestinal motor function. Thus, CB1 antagonists might be useful to prevent/treat ileus induced by vincristine. PMID:28220074

Activation of the Chemosensory Ion Channels TRPA1 and TRPV1 by Hydroalcohol Extract of Kalopanax pictus Leaves.

PubMed

Son, Hee Jin; Kim, Yiseul; Misaka, Takumi; Noh, Bong Soo; Rhyu, Mee-Ra

2012-11-01

TRPA1 and TRPV1 are members of the TRP superfamily of structurally related, nonselective cation channels. TRPA1 and TRPV1 are often co-expressed in sensory neurons and play an important role in somatosense such as cold, pain, and irritants. The first leaves of Kalopanax pictus Nakai (Araliaceae) have long been used as a culinary ingredient in Korea because of their unique chemesthetic flavor. In this study, we observed the intracellular Ca(2+) response to cultured cells expressing human TRPA1 (hTRPA1) and human TRPV1 (hTRPV1) by Ca(2+) imaging analysis to investigate the ability of the first leaves of K. pictus to activate the hTRPA1 and hTRPV1. An 80% ethanol extract of K. pictus (KPEx) increased intracellular Ca(2+) influx in a response time- and concentration-dependent manner via either hTRPA1 or hTRPV1. KPEx-induced response to hTRPA1 was markedly attenuated by ruthenium red, a general blocker of TRP channels, and HC-030031, a specific antagonist of TRPA1. In addition, the intracellular Ca(2+) influx attained with KPEx to hTRPV1 was mostly blocked by ruthenium red, and capsazepine, a specific antagonist of TRPV1. These results indicate that KPEx selectively activates both hTRPA1 and hTRPV1, which may provide evidence that the first leaves of K. pictus primarily activate TRPA1 and TRPV1 to induce their unique chemesthetic sense.

Three-dimensional quantitative structure-activity relationship CoMSIA/CoMFA and LeapFrog studies on novel series of bicyclo [4.1.0] heptanes derivatives as melanin-concentrating hormone receptor R1 antagonists.

PubMed

Morales-Bayuelo, Alejandro; Ayazo, Hernan; Vivas-Reyes, Ricardo

2010-10-01

Comparative molecular similarity indices analysis (CoMSIA) and comparative molecular field analysis (CoMFA) were performed on a series of bicyclo [4.1.0] heptanes derivatives as melanin-concentrating hormone receptor R1 antagonists (MCHR1 antagonists). Molecular superimposition of antagonists on the template structure was performed by database alignment method. The statistically significant model was established on sixty five molecules, which were validated by a test set of ten molecules. The CoMSIA model yielded the best predictive model with a q(2) = 0.639, non cross-validated R(2) of 0.953, F value of 92.802, bootstrapped R(2) of 0.971, standard error of prediction = 0.402, and standard error of estimate = 0.146 while the CoMFA model yielded a q(2) = 0.680, non cross-validated R(2) of 0.922, F value of 114.351, bootstrapped R(2) of 0.925, standard error of prediction = 0.364, and standard error of estimate = 0.180. CoMFA analysis maps were employed for generating a pseudo cavity for LeapFrog calculation. The contour maps obtained from 3D-QSAR studies were appraised for activity trends for the molecules analyzed. The results show the variability of steric and electrostatic contributions that determine the activity of the MCHR1 antagonist, with these results we proposed new antagonists that may be more potent than previously reported, these novel antagonists were designed from the addition of highly electronegative groups in the substituent di(i-C(3)H(7))N- of the bicycle [4.1.0] heptanes, using the model CoMFA which also was used for the molecular design using the technique LeapFrog. The data generated from the present study will further help to design novel, potent, and selective MCHR1 antagonists. Copyright (c) 2010 Elsevier Masson SAS. All rights reserved.

Effects of cetrorelix, a GnRH-receptor antagonist, on gonadal axis in women with functional hypothalamic amenorrhea.

PubMed

Berardelli, Rita; Gianotti, Laura; Karamouzis, Ioannis; Picu, Andreea; Giordano, Roberta; D'Angelo, Valentina; Zinnà, Domenico; Lanfranco, Fabio; Ghigo, Ezio; Arvat, Emanuela

2011-10-01

Gonadotropin Releasing Hormone (GnRH) antagonists (GnRHa) suppress gonadotropin and sex-steroid secretion. In normal women, acute GnRHa administration induces inhibitory effect on pituitary-gonadal axis, followed by Luteinizing Hormone (LH) rebound. Functional hypothalamic amenorrhea (HA) is characterised by impaired gonadotropin secretion and hypogonadism secondary to blunted GnRH pulsatility. We studied the effects of a GnRHa, cetrorelix (CTX 3.0 mg), in six women with HA (age 30.7 ± 3.2 years; BMI 21.5 ± 1.7 kg/m(2)) and six control subjects (CS, 28.2 ± 0.6 years; 22.6 ± 0.9 kg/m(2)) on LH, Follicle-Stimulating Hormone (FSH) and oestradiol levels over 4 h (08.00-12.00 am) before, +24 h and +96 h after CTX; LH, FSH, and oestradiol were also evaluated at +6, +8, +12, +48, +72 h after CTX. CS: CTX reduced (p < 0.05) LH, FSH, and oestradiol (nadir at +12 h, +24 h, and +24 h); LH rebounded at +96 h, FSH and oestradiol recovered at +48 h and +72 h. The 4-h evaluation showed LH and FSH reduction (p < 0.05) at +24 h, with LH rebound at +96 h. HA: CTX reduced (p < 0.05) LH, FSH, and oestradiol, (nadir at +24 h, +48 h, and +48 h, recovery at +48 h, +72 h, and +96 h). The 4-h evaluation showed gonadotropin reduction (p < 0.05) 24 h after CTX, without any rebound effect. One single CTX dose still modulates gonadotropin secretion in HA. Its 'paradoxical' stimulatory effect on gonadotropins needs to be verified after prolonged administration.

Roles of affinity and lipophilicity in the slow kinetics of prostanoid receptor antagonists on isolated smooth muscle preparations

PubMed Central

Jones, RL; Woodward, DF; Wang, JW; Clark, RL

2011-01-01

BACKGROUND AND PURPOSE The highly lipophilic acyl-sulphonamides L-798106 and L-826266 showed surprisingly slow antagonism of the prostanoid EP3 receptor system in guinea-pig aorta. Roles of affinity and lipophilicity in the onset kinetics of these and other prostanoid ligands were investigated. EXPERIMENTAL APPROACH Antagonist selectivity was assessed using a panel of human recombinant prostanoid receptor-fluorimetric imaging plate reader assays. Potencies/affinities and onset half-times of agonists and antagonists were obtained on guinea-pig-isolated aorta and vas deferens. n-Octanol-water partition coefficients were predicted. KEY RESULTS L-798106, L-826266 and the less lipophilic congener (DG)-3ap appear to behave as selective, competitive-reversible EP3 antagonists. For ligands of low to moderate lipophilicity, potency increments for EP3 and TP (thromboxane-like) agonism on guinea-pig aorta (above pEC50 of 8.0) were associated with progressively longer onset half-times; similar trends were found for TP and histamine H1 antagonism above a pA2 limit of 8.0. In contrast, L-798106 (EP3), L-826266 (EP3, TP) and the lipophilic H1 antagonists astemizole and terfenadine exhibited very slow onset rates despite their moderate affinities; (DG)-3ap (EP3) had a faster onset. Agonism and antagonism on the vas deferens EP3 system were overall much faster, although trends were similar. CONCLUSIONS AND IMPLICATIONS High affinity and high liphophilicity may contribute to the slow onsets of prostanoid ligands in some isolated smooth muscle preparations. Both relationships are explicable by tissue disposition under the limited diffusion model. EP3 antagonists used as research tools should have moderate lipophilicity. The influence of lipophilicity on the potential clinical use of EP3 antagonists is discussed. PMID:20973775

Synthesis, Modeling, and Pharmacological Evaluation of UMB 425, a Mixed μ Agonist/δ Antagonist Opioid Analgesic with Reduced Tolerance Liabilities

PubMed Central

2013-01-01

Opioid narcotics are used for the treatment of moderate-to-severe pain and primarily exert their analgesic effects through μ receptors. Although traditional μ agonists can cause undesired side effects, including tolerance, addition of δ antagonists can attenuate said side effects. Herein, we report 4a,9-dihydroxy-7a-(hydroxymethyl)-3-methyl-2,3,4,4a,5,6-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one (UMB 425) a 5,14-bridged morphinan-based orvinol precursor synthesized from thebaine. Although UMB 425 lacks δ-specific motifs, conformationally sampled pharmacophore models for μ and δ receptors predict it to have efficacy similar to morphine at μ receptors and similar to naltrexone at δ receptors, due to the compound sampling conformations in which the hydroxyl moiety interacts with the receptors similar to orvinols. As predicted, UMB 425 exhibits a mixed μ agonist/δ antagonist profile as determined in receptor binding and [35S]GTPγS functional assays in CHO cells. In vivo studies in mice show that UMB 425 displays potent antinociception in the hot plate and tail-flick assays. The antinociceptive effects of UMB 425 are blocked by naloxone, but not by the κ-selective antagonist norbinaltorphimine. During a 6-day tolerance paradigm, UMB 425 maintains significantly greater antinociception compared to morphine. These studies thus indicate that, even in the absence of δ-specific motifs fused to the C-ring, UMB 425 has mixed μ agonist/δ antagonist properties in vitro that translate to reduced tolerance liabilities in vivo. PMID:23713721

Gastro-protective effect of methanol extract of Vernonia amygdalina (del.) leaf on aspirin-induced gastric ulcer in Wistar rats.

PubMed

Adefisayo, Modinat A; Akomolafe, Rufus O; Akinsomisoye, Stephen O; Alabi, Quadri K; Ogundipe, Olaofe L; Omole, Joseph G; Olamilosoye, Kehinde P

2017-01-01

This study investigated the protective effects of methanol extract of Vernonia amygdalina leaf (MEVA) on aspirin induced gastric ulcer in rats. Thirty Wistar rats, 150-200 g were divided into six groups as follows: Group 1 (control) rats received 2 mL/kg of propylene glycol for 28 consecutive days. Group 2 (Ulcer Control) received 150 mg/kg/day of aspirin suspended in 3 mL of 1% carboxymethylcellulose in water orally for 3 consecutive days during which the rats were fasted for the induction of ulcer. Group 3 received cimetidine at 100 mg/kg/day orally for 28 consecutive days and thereafter treated as group 2. Groups 4, 5 and 6 received MEVA orally at 200, 300 and 400 mg/kg/day respectively for 28 consecutive days and thereafter were treated with aspirin as group 2. All the animals were sacrifice at the end of the study to determine the gastric pH, gastric acidity, gastric ulcer score, haematological indices, superoxide dismutase (SOD) activity, reduced glutathione (GSH) and Lipid peroxidation (LPO) levels. The result showed that aspirin significantly (p < 0.05) increased gastric ulcer score and index, decreased gastric pH, gastric acidity, SOD activity, GSH level as well as increased LPO level. It induced significant necrosis of the stomach tissue. Administration of MEVA significantly (p < 0.05) increased gastric pH, but decreased gastric acid secretion and reversed alteration of haematological parameters. It also significantly (p < 0.05) increased SOD activity, GSH level and decreased LPO level. The results suggest that Vernonia amygdalina possesses gastro-protective properties against aspirin-induced gastric ulcer.

[Japanese epidemiologic investigation for non-steroidal anti-inflammatory drugs-induced ulcers].

PubMed

Miyake, Kazumasa; Sakamoto, Choitsu

2011-06-01

This review summaried epidemiologic investigation for non-steroidal anti-inflammatory drugs (NSAIDs)-induced ulcers to focus on the Japanese evidence. In Japan, national health insurance does not cover procedures that prevent or lower the risk for NSAIDs-induced ulcer. In NSAIDs treatment to patients with risk factors, it is desirable to administer antiulcer agents. However, in Japan, there are no large-scale studies on the efficacy of co-medication such as proton pump inhibitors, prostaglandin analogs (misoprostol) or histamine-H2 receptor antagonists or on the effectiveness of H. pylori eradication or selective COX-2 antagonists. In the future, large-scale clinical studies should be conducted to accumulate high quality evidence including cost-effectiveness and overall safety including cardiovascular events, because Japanese differ from Westerners in several genetical or acquired factors.

Pentadecapeptide BPC 157, cimetidine, ranitidine, bromocriptine, and atropine effect in cysteamine lesions in totally gastrectromized rats: a model for cytoprotective studies.

PubMed

Sikirić, P; Mikus, D; Seiwerth, S; Grabarević, Z; Rucman, R; Petek, M; Jagić, V; Turković, B; Rotkvić, I; Mise, S; Zoricić, I; Perić, J; Konjevoda, P; Perović, D; Jurina, L; Hanzevacki, M; Separović, J; Gjurasin, M; Jadrijević, S; Jelovac, N; Miklić, P; Buljat, G; Marović, A

1997-05-01

A superior effectiveness in various lesion assays was noted for the novel pentadecapeptide BPC 157, originated from human gastric juice protein (BPC) and claimed to be a cytoprotective agent. From this viewpoint, as a previously untreated experimental improvement to create an acid-free environmental for cytoprotection studies, total gastrectomy was done 24 hr before the ulcerogenic procedure. In the absence of stomach and gastric acid, the damaging effects of cysteamine (400 mg/kg subcutaneously, death 24 hr thereafter), to date thought to be an acid-related duodenal ulcerogen, and the BPC 157 cytoprotective effect (10 microg or 10 ng/kg intraperitoneally) were further challenged. BPC 157 was compared with reference agents [cimetidine (50), ranitidine (10), omeprazole (10), bromocriptine (10) and atropine (10) (mg/kg intraperitoneally, 1 hr before cysteamine] known to be also cytoprotective. In naive rats, with intact stomach, all of them showed a strong beneficial effect. Interestingly, in gastrectomized animals, the application of BPC 157 or the reference agents before cysteamine significantly prevented the otherwise severe duodenal lesion development noted in the control gastrectomized cysteamine rats. In groups without cysteamine, no lesions were noted (laparotomy, gastrectomy only, 24 or 48 hr postsurgical period), nor was lesion potentiation seen in cysteamine-treated laparotomized animals. In summary, these findings--equal damaging effect of cysteamine and equal protection of pentadecapeptide BPC 157 and reference agents in gastrectomized and rats with intact stomach--seem to be particularly relevant for a cytoprotective viewpoint. Without a stomach, the cysteamine damaging effect was convincingly defined as an essential gastric acid-independent injury (analogous to ethanol gastric lesions). Likewise, a high "cytoprotective capacity," apparently acid independent, common for all tested agents (novel pentadecapeptide BPC 157, cimetidine, ranitidine, omeprazole and atropine) could be clearly stressed.

Structural Insights into Selective Ligand-Receptor Interactions Leading to Receptor Inactivation Utilizing Selective Melanocortin 3 Receptor Antagonists.

PubMed

Cai, Minying; Marelli, Udaya Kiran; Mertz, Blake; Beck, Johannes G; Opperer, Florian; Rechenmacher, Florian; Kessler, Horst; Hruby, Victor J

2017-08-15

Systematic N-methylated derivatives of the melanocortin receptor ligand, SHU9119, lead to multiple binding and functional selectivity toward melanocortin receptors. However, the relationship between N-methylation-induced conformational changes in the peptide backbone and side chains and melanocortin receptor selectivity is still unknown. We conducted comprehensive conformational studies in solution of two selective antagonists of the third isoform of the melanocortin receptor (hMC3R), namely, Ac-Nle-c[Asp-NMe-His 6 -d-Nal(2') 7 -NMe-Arg 8 -Trp 9 -Lys]-NH 2 (15) and Ac-Nle-c[Asp-His 6 -d-Nal(2') 7 -NMe-Arg 8 -NMe-Trp 9 -NMe-Lys]-NH 2 (17). It is known that the pharmacophore (His 6 -DNal 7 -Arg 8 -Trp 9 ) of the SHU-9119 peptides occupies a β II-turn-like region with the turn centered about DNal 7 -Arg 8 . The analogues with hMC3R selectivity showed distinct differences in the spatial arrangement of the Trp 9 side chains. In addition to our NMR studies, we also carried out molecular-level interaction studies of these two peptides at the homology model of hMC3R. Earlier chimeric human melanocortin 3 receptor studies revealed insights regarding the binding and functional sites of hMC3R selectivity. Upon docking of peptides 15 and 17 to the binding pocket of hMC3R, it was revealed that Arg 8 and Trp 9 side chains are involved in a majority of the interactions with the receptor. While Arg 8 forms polar contacts with D154 and D158 of hMC3R, Trp 9 utilizes π-π stacking interactions with F295 and F298, located on the transmembrane domain of hMC3R. It is hypothesized that as the frequency of Trp 9 -hMC3R interactions decrease, antagonistic activity increases. The absence of any interactions of the N-methyl groups with hMC3R suggests that their primary function is to modulate backbone conformations of the ligands.

New antagonists of LHRH. II. Inhibition and potentiation of LHRH by closely related analogues.

PubMed

Bajusz, S; Csernus, V J; Janaky, T; Bokser, L; Fekete, M; Schally, A V

1988-12-01

Modifications of the previously described LHRH antagonists, [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Trp3, D-Cit6, D-Ala10]LHRH and the corresponding D-Hci6 analogue, have been made to alter the hydrophobicity of the N-terminal acetyl-tripeptide portion. Substitution of D-Trp3 with the less hydrophobic D-Pal(3) had only marginal effects on the antagonistic activities and receptor binding potencies of the D-Cit/D-Hci6 analogues, but it appeared to further improve the toxicity lowering effect of D-Cit/D-Hci6 substitution. Antagonists containing D-Pal(3)3 and D-Cit/D-Hci6 residues, i.e. [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10]LHRH (SB-75) and [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Hci6, D-Ala10]LHRH (SB-88), were completely free of the toxic effects, such as cyanosis and respiratory depression leading to death, which have been observed in rats with the D-Trp3, D-Arg6 antagonist and related antagonists. Replacement of the N-acetyl group with the hydrophilic carbamoyl group caused a slight decrease in antagonistic activities, particularly in vitro. Introduction of urethane type acyl group such as methoxycarbonyl (Moc) or t-butoxycarbonyl (Boc) led to analogues that showed LHRH-potentiating effect. The increase in potency induced by these analogues, e.g. [Moc-D-Nal(2)1, D-Phe(4Cl)2, D-Trp3, D-Cit6, D-Ala10]LHRH and [Boc-D-Phe1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10]LHRH, was 170-260% and persisted for more than 2 h when studied in a superfused rat pituitary system.

TRPV1 and PLC Participate in Histamine H4 Receptor-Induced Itch.

PubMed

Jian, Tunyu; Yang, Niuniu; Yang, Yan; Zhu, Chan; Yuan, Xiaolin; Yu, Guang; Wang, Changming; Wang, Zhongli; Shi, Hao; Tang, Min; He, Qian; Lan, Lei; Wu, Guanyi; Tang, Zongxiang

2016-01-01

Histamine H4 receptor has been confirmed to play a role in evoking peripheral pruritus. However, the ionic and intracellular signaling mechanism of activation of H4 receptor on the dorsal root ganglion (DRG) neurons is still unknown. By using cell culture and calcium imaging, we studied the underlying mechanism of activation of H4 receptor on the DRG neuron. Immepip dihydrobromide (immepip)-a histamine H4 receptor special agonist under cutaneous injection-obviously induced itch behavior of mice. Immepip-induced scratching behavior could be blocked by TRPV1 antagonist AMG9810 and PLC pathway inhibitor U73122. Application of immepip (8.3-50 μM) could also induce a dose-dependent increase in intracellular Ca(2+) ([Ca(2+)]i) of DRG neurons. We found that 77.8% of the immepip-sensitized DRG neurons respond to the TRPV1 selective agonist capsaicin. U73122 could inhibit immepip-induced Ca(2+) responses. In addition, immepip-induced [Ca(2+)]i increase could be blocked by ruthenium red, capsazepine, and AMG9810; however it could not be blocked by TRPA1 antagonist HC-030031. These results indicate that TRPV1 but not TRPA1 is the important ion channel to induce the DRG neurons' responses in the downstream signaling pathway of histamine H4 receptor and suggest that TRPV1 may be involved in the mechanism of histamine-induced itch response by H4 receptor activation.

Receptor stimulated formation of inositol phosphates in cultures of bovine adrenal medullary cells: the effects of bradykinin, bombesin and neurotensin.

PubMed

Bunn, S J; Marley, P D; Livett, B G

1990-04-01

The ability of a number of drugs and neuropeptides to stimulate phosphoinositide metabolism in cultured bovine adrenal medullary cells has been assessed. Low concentrations (10 nM) of angiotensin II, bradykinin, histamine, arginine-vasopressin, and bombesin, and high (10 microM) concentrations of oxytocin, prostaglandins E1, and E2, beta-endorphin, and neurotensin stimulated significant accumulation of [3H]inositol phosphates in adrenal medullary cells preloaded with [3H)]inositol. Bradykinin stimulated a significant response at concentration as low as 10pM, with an EC50 of approximately 0.5 nM. The response was markedly inhibited by the bradykinin B2 antagonist [Thi5,8,D-Phe7] bradykinin but not the B1 antagonist [Des-Arg9,Leu8] bradykinin. Higher concentrations of bombesin and neurotensin were required to elicit a response (10 nM and 10 microM respectively). The bombesin response was sensitive to inhibition by the bombesin antagonist [D-Arg1,D-Pro2,D-Trp7,9Leu11]-substance P. In contrast, the neurotensin response was not reduced by the NT1 antagonist [D-Trp11]-neurotensin. These results indicate there are a number of agents that can stimulate phosphatidylinositide hydrolysis in the adrenal medullary cells by acting on different classes of receptors. Such a range of diverse agonists that stimulate inositol phosphate formation will facilitate further analysis of the phosphatidylinositide breakdown in chromaffin cell function.

Discovery and evaluation of a series of 3-acylindole imidazopyridine platelet-activating factor antagonists.

PubMed

Curtin, M L; Davidsen, S K; Heyman, H R; Garland, R B; Sheppard, G S; Florjancic, A S; Xu, L; Carrera, G M; Steinman, D H; Trautmann, J A; Albert, D H; Magoc, T J; Tapang, P; Rhein, D A; Conway, R G; Luo, G; Denissen, J F; Marsh, K C; Morgan, D W; Summers, J B

1998-01-01

Studies conducted with the goal of discovering a second-generation platelet-activating factor (PAF) antagonist have identified a novel class of potent and orally active antagonists which have high aqueous solubility and long duration of action in animal models. The compounds arose from the combination of the lipophilic indole portion of Abbott's first-generation PAF antagonist ABT-299 (2) with the methylimidazopyridine heterocycle moiety of British Biotechnology's BB-882 (1) and possess the positive attributes of both of these clinical candidates. Structure-activity relationship (SAR) studies indicated that modification of the indole and benzoyl spacer of lead compound 7b gave analogues that were more potent, longer-lived, and bioavailable and resulted in the identification of 1-(N, N-dimethylcarbamoyl)-4-ethynyl-3-[3-fluoro-4-[(1H-2-methylimidazo[4,5-c] pyrid-1-yl)methyl]benzoyl]indole hydrochloride (ABT-491, 22 m.HCl) which has been evaluated extensively and is currently in clinical development.

Muscarinic acetylcholine receptor subtype 4 is essential for cholinergic stimulation of duodenal bicarbonate secretion in mice - relationship to D cell/somatostatin.

PubMed

Takeuchi, K; Kita, K; Takahashi, K; Aihara, E; Hayashi, S

2015-06-01

We investigated the roles of muscarinic (M) acetylcholine receptor subtype in the cholinergic stimulation of duodenal HCO3(-) secretion using knockout (KO) mice. Wild-type and M1-M5 KO C57BL/6J mice were used. The duodenal mucosa was mounted on an Ussing chamber, and HCO3(-) secretion was measured at pH 7.0 using a pH-stat method in vitro. Carbachol (CCh) or other agents were added to the serosal side. CCh dose-dependently stimulated HCO3(-) secretion in wild-type mice, and this effect was completely inhibited in the presence of atropine. The HCO3(-) response to CCh in wild-type mice was also inhibited by pirenzepine (M1 antagonist), 4DAMP (M3 antagonist), and tropicamide (M4 antagonist), but not by methoctramine (M2 antagonist). CCh stimulated HCO3(-) secretion in M2 and M5 KO animals as effectively as in WT mice; however, this stimulatory effect was significantly attenuated in M1, M3, and M4 KO mice. The decrease observed in the CCh-stimulated HCO3(-) response in M4 KO mice was reversed by the co-application of CYN154806, a somatostatin receptor type 2 (SST2) antagonist. Octreotide (a somatostatin analogue) decreased the basal and CCh-stimulated secretion of HCO3(-) in wild-type mice. The co-localized expression of somatostatin and M4 receptors was confirmed immunohistologically in the duodenum. We concluded that the duodenal HCO3(-) response to CCh was directly mediated by M1/M3 receptors and indirectly modified by M4 receptors. The activation of M4 receptors was assumed to inhibit the release of somatostatin from D cells and potentiate the HCO3(-) response by removing the negative influence of somatostatin via the activation of SST2 receptors.

Several down, a few to go: histamine H3 receptor ligands making the final push towards the market?

PubMed

Kuhne, Sebastiaan; Wijtmans, Maikel; Lim, Herman D; Leurs, Rob; de Esch, Iwan J P

2011-12-01

The histamine H(3) receptor (H(3)R) plays a pivotal role in a plethora of therapeutic areas. Blocking the H(3)R with antagonists/inverse agonists has been postulated to be of broad therapeutic use. Indeed, H(3)R antagonists/inverse agonists have been extensively evaluated in the clinic. Here, we address new developments, insights obtained and challenges encountered in the clinical evaluations. For recent H(3)R clinical candidates, the status and results of the corresponding clinical trial(s) will be discussed along with preclinical data. In all, it becomes evident that clinical evaluation of H(3)R antagonists/inverse agonists is characterized by mixed results. On one hand, Pitolisant has successfully passed several Phase II trials and seems to be the most advanced compound in the clinic now, being in Phase III. On the other hand, some compounds (e.g., PF-03654647 and MK-0249) failed at Phase II clinical level for several indications. A challenging feature in H(3)R research is the multifaceted role of the receptor at a molecular/biochemical level, which can complicate targeting by small molecules at several (pre)clinical levels. Accordingly, H(3)R antagonists/inverse agonists require further testing to pinpoint the determinants for clinical efficacy and to aid in the final push towards the market.

Pharmacological characterization of the bradykinin B2 receptor: inter-species variability and dissociation between binding and functional responses

PubMed Central

Paquet, J -L; Luccarini, J -M; Fouchet, C; Defrêne, E; Loillier, B; Robert, C; Bélichard, P; Cremers, B; Pruneau, D

1999-01-01

The present study addresses the differences in binding profiles and functional properties of the human and rat bradykinin (BK) B2 receptor using various kinin receptor peptide derivatives as well as the non-peptide receptor antagonists WIN 64338 (phosphonium, [[4-[[2-[[bis(cyclohexylamino)methylene]amino]-3-(2-naphtalenyl)1-oxopropyl]amino]-phenyl]-methyl]tributyl, chloride, monohydro-chloride), and FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[-N-[2,4-dichloro-3-[(2-methyl-8-quinolinyl)oxymethyl]-phenyl]N-methylamino carbonyl methyl] acrylamide. [3H]-BK bound with a similar affinity to membranes of Chinese hamster ovary cells (CHO-K1) expressing the cloned human (hB2-CHO) or rat (rB2-CHO) B2 receptor, human embryonic intestine cells (INT407) expressing the native B2 receptor, human umbilical vein (HUV) and rat uterus (RU). WIN 64338 and FR173657 bound with a 3.8–6.6 fold and 7.0–16.3 fold higher affinity the rat than the human B2 receptor, respectively. The affinity values of BK derivatives as well as non-peptide antagonists were reduced by 6–23 fold in physiological HBSS compared to low ionic strength TES binding buffer. BK (0.01–3000 nM) increased inositol triphosphates (IP3) levels in hB2-CHO, rB2-CHO and INT407 cells. The B2 receptor antagonist, Hoe 140 (D-Arg0-[ Hyp3, Thi5, D-Tic7, Oic8]-BK) at 10−7 M, significantly shifted to the right the IP3 response curves to BK giving apparent pKB values of 8.56, 9.79 and 8.84 for hB2-CHO, rB2-CHO and INT407 cells, respectively. In human isolated umbilical vein, Hoe 140, D-Arg0-[Hyp3, D-Phe7, Leu8]-BK and NPC 567 had a lower potency in functional assays (pKB 8.18, 5.77 and 5.60, respectively) than expected from their affinity in binding studies (pKi 10.52, 8.64 and 8.27, respectively). FR173657 behaved as a high affinity ligand with pKi values of 8.59 and 9.81 and potent competitive antagonist with pKB values of 7.80 and 8.17 in HUV and RU, respectively. FR173657 bound with a similar affinity the cloned and native bradykinin B2 receptor in human (pKi of 8.66 and 8.59, respectively) and in rat (pKi 9.67 and 9.81, respectively). In conclusion, we suggest that the binding buffer composition has to be taken into account when screening new compounds and that inter-species differences should be considered when setting up animal models with the aim of developing bradykinin B2 receptor antagonists as therapeutic agents. PMID:10204994

Effects of polyphenol substances derived from Theobroma cacao on gastric mucosal lesion induced by ethanol.

PubMed

Osakabe, N; Sanbongi, C; Yamagishi, M; Takizawa, T; Osawa, T

1998-08-01

The antiulcer activity of cacao liquor water-soluble crude polyphenols (CWSP) was examined. CWSP, alpha-tocopherol, sucralfate (500 mg/kg), and cimetidine (250 mg/kg) were orally administered to male SD rats 30 minutes before ethanol treatment. 5 ml/kg of ethanol given intragastrically caused lesions in mucosa of the glandular stomach. CWSP caused a reduction of such hemorrhagic lesions as well as cimetidine and sucralfate which are typical antiulcer drugs, but alpha-tocopherol was less effective. Thiobarbituric acid reactive substances in gastric mucosa significantly increased with ethanol administration. CWSP treatment significantly reduced this change. The administration of ethanol extensively increased myeloperoxidase (MPO) but not xanthine oxidase (XOD) activity. CWSP reduced the activities of both enzymes; they were considered the main sources of oxygen radicals. According to an in vitro study, CWSP directly reducted XOD but not MPO. These results suggest that the antiulcer mechanism of CWSP was not only radical scavenging but also modulation of leukocyte function.

The Cannabinoids Δ8THC, CBD, and HU-308 Act via Distinct Receptors to Reduce Corneal Pain and Inflammation.

PubMed

Thapa, Dinesh; Cairns, Elizabeth A; Szczesniak, Anna-Maria; Toguri, James T; Caldwell, Meggie D; Kelly, Melanie E M

2018-01-01

Background and Purpose: Corneal injury can result in dysfunction of corneal nociceptive signaling and corneal sensitization. Activation of the endocannabinoid system has been reported to be analgesic and anti-inflammatory. The purpose of this research was to investigate the antinociceptive and anti-inflammatory effects of cannabinoids with reported actions at cannabinoid 1 (CB 1 R) and cannabinoid 2 (CB 2 R) receptors and/or noncannabinoid receptors in an experimental model of corneal hyperalgesia. Methods: Corneal hyperalgesia (increased pain response) was generated using chemical cauterization of the corneal epithelium in wild-type (WT) and CB 2 R knockout (CB 2 R -/- ) mice. Cauterized eyes were treated topically with the phytocannabinoids Δ 8 -tetrahydrocannabinol (Δ 8 THC) or cannabidiol (CBD), or the CBD derivative HU-308, in the presence or absence of the CB 1 R antagonist AM251 (2.0 mg/kg i.p.), or the 5-HT 1A receptor antagonist WAY100635 (1 mg/kg i.p.). Behavioral pain responses to a topical capsaicin challenge at 6 h postinjury were quantified from video recordings. Mice were euthanized at 6 and 12 h postcorneal injury for immunohistochemical analysis to quantify corneal neutrophil infiltration. Results: Corneal cauterization resulted in hyperalgesia to capsaicin at 6 h postinjury compared to sham control eyes. Neutrophil infiltration, indicative of inflammation, was apparent at 6 and 12 h postinjury in WT mice. Application of Δ 8 THC, CBD, and HU-308 reduced the pain score and neutrophil infiltration in WT mice. The antinociceptive and anti-inflammatory actions of Δ 8 THC, but not CBD, were blocked by the CB 1 R antagonist AM251, but were still apparent, for both cannabinoids, in CB 2 R -/- mice. However, the antinociceptive and anti-inflammatory actions of HU-308 were absent in the CB 2 R -/- mice. The antinociceptive and anti-inflammatory effects of CBD were blocked by the 5-HT 1A antagonist WAY100635. Conclusion: Topical cannabinoids reduce corneal hyperalgesia and inflammation. The antinociceptive and anti-inflammatory effects of Δ 8 THC are mediated primarily via CB 1 R, whereas that of the cannabinoids CBD and HU-308, involve activation of 5-HT 1A receptors and CB 2 Rs, respectively. Cannabinoids could be a novel clinical therapy for corneal pain and inflammation resulting from ocular surface injury.

Structure-based identification and characterisation of structurally novel human P2X7 receptor antagonists.

PubMed

Caseley, Emily A; Muench, Stephen P; Fishwick, Colin W; Jiang, Lin-Hua

2016-09-15

The P2X7 receptor (P2X7R) plays an important role in diverse conditions associated with tissue damage and inflammation, meaning that the human P2X7R (hP2X7R) is an attractive therapeutic target. The crystal structures of the zebrafish P2X4R in the closed and ATP-bound open states provide an unprecedented opportunity for structure-guided identification of new ligands. The present study performed virtual screening of ∼100,000 structurally diverse compounds against the ATP-binding pocket in the hP2X7R. This identified three compounds (C23, C40 and C60) out of 73 top-ranked compounds by testing against hP2X7R-mediated Ca(2+) responses. These compounds were further characterised using Ca(2+) imaging, patch-clamp current recording, YO-PRO-1 uptake and propidium iodide cell death assays. All three compounds inhibited BzATP-induced Ca(2+) responses concentration-dependently with IC50s of 5.1±0.3μM, 4.8±0.8μM and 3.2±0.2μM, respectively. C23 and C40 inhibited BzATP-induced currents in a reversible and concentration-dependent manner, with IC50s of 0.35±0.3μM and 1.2±0.1μM, respectively, but surprisingly C60 did not affect BzATP-induced currents up to 100μM. They suppressed BzATP-induced YO-PRO-1 uptake with IC50s of 1.8±0.9μM, 1.0±0.1μM and 0.8±0.2μM, respectively. Furthermore, these three compounds strongly protected against ATP-induced cell death. Among them, C40 and C60 exhibited strong specificity towards the hP2X7R over the hP2X4R and rP2X3R. In conclusion, our study reports the identification of three novel hP2X7R antagonists with micromolar potency for the first time using a structure-based approach, including the first P2X7R antagonist with preferential inhibition of large pore formation. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Characteristics of children and adolescents first prescribed proton pump inhibitors or histamine-2-receptor antagonists: an observational cohort study.

PubMed

Ruigómez, Ana; Kool-Houweling, Leanne M A; García Rodríguez, Luis A; Penning-van Beest, Fernie J A; Herings, Ron M C

2017-12-01

To describe the characteristics of pediatric patients prescribed proton pump inhibitors (PPIs) vs those of pediatric patients prescribed histamine-2-receptor antagonists (H 2 RAs). Observational studies were conducted using The Health Improvement Network (THIN) and the PHARMO Database Network. Patients aged 0-18 years who were first prescribed a PPI or H 2 RA between October 1, 2009 and September 30, 2012 (THIN) or between September 1, 2008 and August 31, 2011 (PHARMO) were included. Patient characteristics were identified and compared between the PPI and H 2 RA cohorts using odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for age and sex. The mean age (years) was higher in the PPI than in the H 2 RA cohorts (THIN 12.3 [n = 8204] vs 5.4 [n = 7937], PHARMO 11.0 [n = 15 362] vs 7.1 [n = 6168]). Previous respiratory disease was more common in the PPI than in the H 2 RA cohort in THIN (OR = 1.19, 95% CI = 1.08-1.30), as were asthma and respiratory medication use in PHARMO (OR = 1.27, 95% CI = 1.12-1.45 and OR = 1.23, 95% CI = 1.10-1.38, respectively) and oral corticosteroid use in both databases (OR = 1.45, 95% CI = 1.10-1.92 [THIN]; OR = 2.80, 95% CI = 2.11-3.71 [PHARMO]). Non-steroidal anti-inflammatory drugs, antibiotics, and oral contraceptives were also more common in PPI than in H 2 RA cohorts in both databases. Pediatric patients receiving PPIs and those receiving H 2 RAs may represent different patient populations. PPIs may be more commonly prescribed than H 2 RAs among patients with respiratory diseases.

MF498 [N-{[4-(5,9-Diethoxy-6-oxo-6,8-dihydro-7H-pyrrolo[3,4-g]quinolin-7-yl)-3-methylbenzyl]sulfonyl}-2-(2-methoxyphenyl)acetamide], a selective E prostanoid receptor 4 antagonist, relieves joint inflammation and pain in rodent models of rheumatoid and osteoarthritis.

PubMed

Clark, Patsy; Rowland, Steven E; Denis, Danielle; Mathieu, Marie-Claude; Stocco, Rino; Poirier, Hugo; Burch, Jason; Han, Yongxin; Audoly, Laurent; Therien, Alex G; Xu, Daigen

2008-05-01

Previous evidence has implicated E prostanoid receptor 4 (EP4) in mechanical hyperalgesia induced by subplantar inflammation. However, its role in chronic arthritis remains to be further defined because previous attempts have generated two conflicting lines of evidence, with one showing a marked reduction of arthritis induced by a collagen antibody in mice lacking EP4, but not EP1-EP3, and the other showing no impact of EP4 antagonism on arthritis induced by collagen. Here, we assessed the effect of a novel and selective EP4 antagonist MF498 [N-{[4-(5,9-diethoxy-6-oxo-6,8-dihydro-7H-pyrrolo[3,4-g]quinolin-7-yl)-3-methylbenzyl]sulfonyl}-2-(2-methoxyphenyl)acetamide] on inflammation in adjuvant-induced arthritis (AIA), a rat model for rheumatoid arthritis (RA), and joint pain in a guinea pig model of iodoacetate-induced osteoarthritis (OA). In the AIA model, MF498, but not the antagonist for EP1, MF266-1 [1-(5-{3-[2-(benzyloxy)-5-chlorophenyl]-2-thienyl}pyridin-3-yl)-2,2,2-trifluoroethane-1,1-diol] or EP3 MF266-3 [(2E)-N-[(5-bromo-2-methoxyphenyl)sulfonyl]-3-[5-chloro-2-(2-naphthylmethyl)phenyl]acrylamide], inhibited inflammation, with a similar efficacy as a selective cyclooxygenase 2 (COX-2) inhibitor MF-tricyclic. In addition, MF498 was as effective as an nonsteroidal anti-inflammatory drug, diclofenac, or a selective microsomal prostaglandin E synthase-1 inhibitor, MF63 [2-(6-chloro-1H-phenanthro[9,10-d]imidazol-2-yl)isophthalonitrile], in relieving OA-like pain in guinea pigs. When tested in rat models of gastrointestinal toxicity, the EP4 antagonist was well tolerated, causing no mucosal leakage or erosions. Lastly, we evaluated the renal effect of MF498 in a furosemide-induced diuresis model and demonstrated that the compound displayed a similar renal effect as MF-tricyclic [3-(3,4-difluorophenyl)-4-(4-(methylsulfonyl)phenyl)-2-(5H)-furanone], reducing furosemide-induced natriuresis by approximately 50%. These results not only suggest that EP4 is the major EP receptor in both RA and OA but also provide a proof of principle to the concept that antagonism of EP4 may be useful for treatment of arthritis.

Adenosine signaling in reserpine-induced depression in rats.

PubMed

Minor, Thomas R; Hanff, Thomas C

2015-06-01

A single, 6 mg/kg intraperitoneal injection of reserpine increased floating time during forced swim testing 24h after administration in rats in five experiments. Although such behavioral depression traditionally is attributed to drug-induced depletion of brain monoamines, we examined the potential contribution of adenosine signaling, which is plausibly activated by reserpine treatment and contributes to behavioral depression in other paradigms. Whereas peripheral administration of the highly selective A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (0.5, 1.0, or 5.0mg/kg i.p.) 15 min before swim testing failed to improve performance in reserpine-treated rats, swim deficits were completely reversed by 7 mg/kg of the nonselective receptor antagonist caffeine. Performance deficits were also reversed by the nonselective A2 antagonist 3,7-dimethylxanthine (0, 0.5, 1.0mg/kg i.p.), and the highly selective A2A receptor antagonist (CSC: 8-(3 chlorostyral)caffeine) (0.01, 0.1, or 1.0mg/kg i.p.) in a dose-dependent manner. The highly selective A2B antagonist alloxazine had no beneficial effect on swim performance at any dose under study (0.1, 1.0, and 5.0mg/kg i.p.). Copyright © 2015 Elsevier B.V. All rights reserved.

Calcium-calmodulin is required for abscisic acid-induced antioxidant defense and functions both upstream and downstream of H2O2 production in leaves of maize (Zea mays) plants.

PubMed

Hu, Xiuli; Jiang, Mingyi; Zhang, Jianhua; Zhang, Aying; Lin, Fan; Tan, Mingpu

2007-01-01

* Using pharmacological and biochemical approaches, the role of calmodulin (CaM) and the relationship between CaM and hydrogen peroxide (H(2)O(2)) in abscisic acid (ABA)-induced antioxidant defense in leaves of maize (Zea mays) plants were investigated. * Treatment with ABA or H(2)O(2) led to significant increases in the concentration of cytosolic Ca(2+) in the protoplasts of mesophyll cells and in the expression of the calmodulin 1 (CaM1) gene and the content of CaM in leaves of maize plants, and enhanced the expression of the antioxidant genes superoxide dismutase 4 (SOD4), cytosolic ascorbate peroxidase (cAPX), and glutathione reductase 1 (GR1) and the activities of the chloroplastic and cytosolic antioxidant enzymes. The up-regulation of the antioxidant enzymes was almost completely blocked by pretreatments with two CaM antagonists. * Pretreatments with CaM antagonists almost completely inhibited ABA-induced H(2)O(2) production throughout ABA treatment, but pretreatment with an inhibitor or scavenger of reactive oxygen species (ROS) did not affect the initial increase in the contents of CaM induced by ABA. * Our results suggest that Ca(2+)-CaM is involved in ABA-induced antioxidant defense, and that cross-talk between Ca(2+)-CaM and H(2)O(2) plays a pivotal role in ABA signaling.

Pharmacological characterization of the human histamine H2 receptor stably expressed in Chinese hamster ovary cells.

PubMed Central

Leurs, R.; Smit, M. J.; Menge, W. M.; Timmerman, H.

1994-01-01

1. The gene for the human histamine H2 receptor was stably expressed in Chinese hamster ovary (CHO) cells and characterized by [125I]-iodoaminopotentidine binding studies. In addition, the coupling of the expressed receptor protein to a variety of signal transduction pathways was investigated. 2. After cotransfection of CHO cells with pCMVhumH2 and pUT626, a phleomycine-resistant clonal cell line (CHOhumH2) was isolated that expressed 565 +/- 35 fmol kg-1 protein binding sites with high affinity (0.21 +/- 0.02 nM) for the H2 antagonist, [125I]-iodoaminopotentidine. 3. Displacement studies with a variety of H2 antagonists indicated that the encoded protein was indistinguishable from the H2 receptor identified in human brain membranes and guinea-pig right atrium. The Ki-values observed in the various preparations correlated very well (r2 = 0.996-0.920). 4. Displacement studies with histamine showed that a limited fraction (32 +/- 6%) of the binding sites showed a high affinity for histamine (2 +/- 1.2 microM); the shallow displacement curves were reflected by a Hill-coefficient significantly different from unity (nH = 0.58 +/- 0.09). The addition of 100 microM Gpp(NH)p resulted in a steepening of the displacement curve (nH = 0.79 +/- 0.02) and a loss of high affinity sites for histamine. 5. Displacement studies with other agonists indicated that the recently developed specific H2 agonists, amthamine and amselamine, showed an approximately 4-5 fold higher affinity for the human H2 receptor than histamine. 6. Stimulation of CHOhumH2 cells with histamine resulted in a rapid rise of the intracellular cyclic AMP levels. After 10 min an approximately 10 fold increase in cyclic AMP could be measured.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 4 PMID:7921611

Glutamate Increases In Vitro Survival and Proliferation and Attenuates Oxidative Stress-Induced Cell Death in Adult Spinal Cord-Derived Neural Stem/Progenitor Cells via Non-NMDA Ionotropic Glutamate Receptors.

PubMed

Hachem, Laureen D; Mothe, Andrea J; Tator, Charles H

2016-08-15

Traumatic spinal cord injury (SCI) leads to a cascade of secondary chemical insults, including oxidative stress and glutamate excitotoxicity, which damage host neurons and glia. Transplantation of exogenous neural stem/progenitor cells (NSPCs) has shown promise in enhancing regeneration after SCI, although survival of transplanted cells remains poor. Understanding the response of NSPCs to the chemical mediators of secondary injury is essential in finding therapies to enhance survival. We examined the in vitro effects of glutamate and glutamate receptor agonists on adult rat spinal cord-derived NSPCs. NSPCs isolated from the periventricular region of the adult rat spinal cord were exposed to various concentrations of glutamate for 96 h. We found that glutamate treatment (500 μM) for 96 h significantly increased live cell numbers, reduced cell death, and increased proliferation, but did not significantly alter cell phenotype. Concurrent glutamate treatment (500 μM) in the setting of H2O2 exposure (500 μM) for 10 h increased NSPC survival compared to H2O2 exposure alone. The effects of glutamate on NSPCs were blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist GYKI-52466, but not by the N-methyl-D-aspartic acid receptor antagonist MK-801 or DL-AP5, or the mGluR3 antagonist LY-341495. Furthermore, treatment of NSPCs with AMPA, kainic acid, or the kainate receptor-specific agonist (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid mimicked the responses seen with glutamate both alone and in the setting of oxidative stress. These findings offer important insights into potential mechanisms to enhance NSPC survival and implicate a potential role for glutamate in promoting NSPC survival and proliferation after traumatic SCI.

Further Optimization and Evaluation of Bioavailable, Mixed-Efficacy μ-Opioid Receptor (MOR) Agonists/δ-Opioid Receptor (DOR) Antagonists: Balancing MOR and DOR Affinities.

PubMed

Harland, Aubrie A; Yeomans, Larisa; Griggs, Nicholas W; Anand, Jessica P; Pogozheva, Irina D; Jutkiewicz, Emily M; Traynor, John R; Mosberg, Henry I

2015-11-25

In a previously described peptidomimetic series, we reported the development of bifunctional μ-opioid receptor (MOR) agonist and δ-opioid receptor (DOR) antagonist ligands with a lead compound that produced antinociception for 1 h after intraperitoneal administration in mice. In this paper, we expand on our original series by presenting two modifications, both of which were designed with the following objectives: (1) probing bioavailability and improving metabolic stability, (2) balancing affinities between MOR and DOR while reducing affinity and efficacy at the κ-opioid receptor (KOR), and (3) improving in vivo efficacy. Here, we establish that, through N-acetylation of our original peptidomimetic series, we are able to improve DOR affinity and increase selectivity relative to KOR while maintaining the desired MOR agonist/DOR antagonist profile. From initial in vivo studies, one compound (14a) was found to produce dose-dependent antinociception after peripheral administration with an improved duration of action of longer than 3 h.

Antiaggregant and antivasospastic properties of the new thromboxane A2 receptor antagonist sodium 4-[[1-[[[(4-chlorophenyl)sulfonyl]amino]methyl]cyclopentyl] methyl]benzeneacetate.

PubMed

Lardy, C; Rousselot, C; Chavernac, G; Depin, J C; Guerrier, D

1994-11-01

LCB 2853 (sodium 4-[[1-[[[(4-chlorophenyl)sulfonyl]amino]methyl]cyclopentyl] methyl]benzeneacetate, CAS 141335-11-7) was demonstrated to be a potent thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor antagonist in in vitro, ex vivo and in vivo experiments. The specific mechanism of action was studied in [3H]SQ 29548 receptor binding studies (pKi = 7.93) and was shown to be of competitive nature in U 46619-induced platelet aggregation (pA2 = 6.82). TXA2-dependent platelet rich plasma (PRP) aggregation (U 46619, arachidonic acid (AA), collagen, ADP or serotonin second phase) was inhibited in vitro in humans (IC50:0.037-0.65 mumol/l) and different animal species, as well as ex vivo i.v. rat and p.o. guinea-pig AA-induced aggregation (ED50 = 48 and 57 micrograms/kg). The U 46619-induced contractions of aorta, caudal artery and trachea were inhibited in a dose-dependent way (IC50 = 0.07, 0.02 and 0.5 mumol/l respectively). In vivo, both against platelet aggregation and vasoconstriction, LCB 2853 showed an ED50 lower than 1 mg/kg i.v. in rat AA-induced thrombocytopenia or U 46619-induced hypertension (ED50 = 0.25 and 0.16 mg/kg) as well as in AA-induced sudden death in the mouse (ED50 = 0.44 mg/kg). The U 46619-induced bronchoconstriction was blocked after i.v. administration of LCB 2853 (ED50 = 18.4 micrograms/kg). The duration of action observed in different models was 6 h by oral route and between 3 and 5 h by intravenous route. These properties in TXA2-dependent models led to further investigations of the antithrombotic activity of this novel TXA2 antagonist.

Synthesis of carbon-11-labeled 5-HT6R antagonists as new candidate PET radioligands for imaging of Alzheimer's disease.

PubMed

Wang, Xiaohong; Dong, Fugui; Miao, Caihong; Li, Wei; Wang, Min; Gao, Mingzhang; Zheng, Qi-Huang; Xu, Zhidong

2018-06-01

Carbon-11-labeled serotonin (5-hydroxytryptamine) 6 receptor (5-HT 6 R) antagonists, 1-[(2-bromophenyl)sulfonyl]-5-[ 11 C]methoxy-3-[(4-methyl-1-piperazinyl)methyl]-1H-indole (O-[ 11 C]2a) and 1-[(2-bromophenyl)sulfonyl]-5-methoxy-3-[(4-[ 11 C]methyl-1-piperazinyl)methyl]-1H-indole (N-[ 11 C]2a), 5-[ 11 C]methoxy-3-((4-methylpiperazin-1-yl)methyl)-1-(phenylsulfonyl)-1H-indole (O-[ 11 C]2b) and 5-methoxy-3-((4-[ 11 C]methylpiperazin-1-yl)methyl)-1-(phenylsulfonyl)-1H-indole (N-[ 11 C]2b), 1-((4-isopropylphenyl)sulfonyl)-5-[ 11 C]methoxy-3-((4-methylpiperazin-1-yl)methyl)-1H-indole (O-[ 11 C]2c) and 1-((4-isopropylphenyl)sulfonyl)-5-methoxy-3-((4-[ 11 C]methylpiperazin-1-yl)methyl)-1H-indole (N-[ 11 C]2c), 1-((4-fluorophenyl)sulfonyl)-5-[ 11 C]methoxy-3-((4-methylpiperazin-1-yl)methyl)-1H-indole (O-[ 11 C]2d) and 1-((4-fluorophenyl)sulfonyl)-5-methoxy-3-((4-[ 11 C]methylpiperazin-1-yl)methyl)-1H-indole (N-[ 11 C]2d), were prepared from their O- or N-desmethylated precursors with [ 11 C]CH 3 OTf through O- or N-[ 11 C]methylation and isolated by HPLC combined with SPE in 40-50% radiochemical yield, based on [ 11 C]CO 2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the molar activity (MA) at EOB was 370-740 GBq/μmol with a total synthesis time of ∼40-min from EOB. Copyright © 2018 Elsevier Ltd. All rights reserved.

Differential binding of /sup 3/H-imipramine and /sup 3/H-mianserin in rat cerebral cortex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumbrille-Ross, A.; Tang, S.W.; Coscina, D.V.

1981-11-16

Drug competition profiles, effect of raphe lesion, and sodium dependency of the binding of two antidepressant drugs /sup 3/H-imipramine and /sup 3/H-mianserin to rat cerebral cortex homogenate were compared to examine whether the drugs bound to a common ''antidepressant receptor.'' Of the neurotransmitters tested, only serotonin displaced binding of both /sup 3/H-imipramine and /sup 3/H-mianserin. /sup 3/H-Mianserin binding was potently displaced by serotonin S/sub 2/ antagonists and exhibited a profile similar to that of /sup 3/H-spiperone binding. In the presence of the serotonin S/sub 2/ antagonist spiperone, antihistamines (H/sub 1/) potently displaced /sup 3/H-mianserin binding. /sup 3/H-Imipramine binding was displacedmore » potently by serotonin uptake inhibitors. The order of potency of serotonergic drugs in displacing /sup 3/H-imipramine binding was not similar to their order in displacing /sup 3/H-spiperone or -3H-serotonin binding. Prior midbrain raphe lesions greatly decreased the binding of /sup 3/H-imipramine but did not alter binding of /sup 3/H-mianserin. Binding of /sup 3/H-imipramine but not /sup 3/H-mianserin was sodium dependent. These results show that /sup 3/H-imipramine and /sup 3/H-mianserin bind to different receptors. /sup 3/H-Imipramine binds to a presynaptic serotonin receptor which is probably related to a serotonin uptake recognition site, the binding of which is sodium dependent. /sup 3/H-Mianserin binds to postsynaptic receptors, possibly both serotonin S/sub 2/ and histamine H/sub 1/ receptors, the binding of which is sodium independent.« less

Structure--activity studies for alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid receptors: acidic hydroxyphenylalanines.

PubMed

Hill, R A; Wallace, L J; Miller, D D; Weinstein, D M; Shams, G; Tai, H; Layer, R T; Willins, D; Uretsky, N J; Danthi, S N

1997-09-26

Antagonists of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid (AMPA) receptors may have therapeutic potential as psychotropic agents. A series of mononitro- and dinitro-2- and 3-hydroxyphenylalanines was prepared, and their activity compared with willardiine, 5-nitrowillardiine, AMPA, and 2,4,5-trihydroxyphenylalanine (6-hydroxydopa) as inhibitors of specific [3H]AMPA and [3H]kainate binding in rat brain homogenates. The most active compounds were highly acidic (pKa 3-4), namely, 2-hydroxy-3,5-dinitro-DL-phenylalanine (13; [3H]AMPA IC50 approximately equal to 25 microM) and 3-hydroxy-2,4-dinitro-DL-phenylalanine (19; [3H]AMPA IC50 approximately equal to 5 microM). Two other dinitro-3-hydroxyphenylalanines, and 3,5-dinitro-DL-tyrosine, were considerably less active. Various mononitrohydroxyphenylalanines, which are less acidic, were also less active or inactive, and 2- and 3-hydroxyphenylalanine (o- and m-tyrosine) were inactive. Compounds 13 and 19, DL-willardiine (pKa 9.3, [3H]AMPA IC50 = 2 microM), and 5-nitro-DL-willardiine (pKa 6.4, [3H]AMPA IC50 = 0.2 microM) displayed AMPA > kainate selectivity in binding studies. Compound 19 was an AMPA-like agonist, but 13 was an antagonist in an AMPA-evoked norepinephrine release assay in rat hippocampal nerve endings. Also, compound 13 injected into the rat ventral pallidum antagonized the locomotor activity elicited by systemic amphetamine.

[Influence of corynebacteria metabolites on antagonistic activity of H2O2 producing lactobacilli].

PubMed

Bukharin, O V; Sgibnev, A V

2012-01-01

Study combined influence of Corynebacterium genus bacteria metabolites and H2O2 producing lactobacilli on survival rate of Staphylococcus aureus, Escherichia coli and Lactobacillus acidophilus. The ability to inhibit catalase of the test strains used and to reduce bactericidal effect of hydroxyl radical were determined in corynebacteria. H2O2 containing metabolites were obtained by cultivating lactobacilli in mineral medium, the amount of H2O2 was determined by oxidation of TMB by peroxidase. Bactericidal effect of lactobacilli metabolites for test strains treated by corynebacteria metabolites was evaluated by seeding results. Results. Inhibitio by corynebacteria metabolites of S. aureus catalase activity by 30-40% and E. coli catalase activ ity by 40-70% was shown. A reduction of bactericidal effect of hydroxyl radicals by corynebacteria metabolites by 30-35% for S. aureus, 38-42% for E. coli and 70-73% for L. acidophilus was noted. The enchantment of bactericidal effect of lactobacilli after treatment of the test strain by corynebacteria metabolites against S. aureus and E. coli manifested by reduction of the numbe of viable cells by 2-3 lg CFU. For L. acidophilus the bactericidal effect oflactobacilli metabolite in the same conditions reduced, and that led to the increase ofviability by 2-4 lg PFU. A conclusion on the possibility of regulation by associative bacteria the manifestations of antagonistic activity of H2O2 producing dominant microorganisms is made based on the data obtained.

7-tert-Butyl-6-(4-chloro-phenyl)-2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one, a classic polymodal inhibitor of transient receptor potential vanilloid type 1 with a reduced liability for hyperthermia, is analgesic and ameliorates visceral hypersensitivity.

PubMed

Nash, Mark S; McIntyre, Peter; Groarke, Alex; Lilley, Elliot; Culshaw, Andrew; Hallett, Allan; Panesar, Moh; Fox, Alyson; Bevan, Stuart

2012-08-01

The therapeutic potential of transient receptor potential vanilloid type 1 (TRPV1) antagonists for chronic pain has been recognized for more than a decade. However, preclinical and clinical data revealed that acute pharmacological blockade of TRPV1 perturbs thermoregulation, resulting in hyperthermia, which is a major hurdle for the clinical development of these drugs. Here, we describe the properties of 7-tert-butyl-6-(4-chloro-phenyl)-2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one (BCTP), a TRPV1 antagonist with excellent analgesic properties that does not induce significant hyperthermia in rodents at doses providing maximal analgesia. BCTP is a classic polymodal inhibitor of TRPV1, blocking activation of the human channel by capsaicin and low pH with IC(50) values of 65.4 and 26.4 nM, respectively. Similar activity was observed with rat TRPV1, and the inhibition by BCTP was competitive and reversible. BCTP also blocked heat-induced activation of TRPV1. In rats, the inhibition of capsaicin-induced mechanical hyperalgesia was observed with a D(50) value of 2 mg/kg p.o. BCTP also reversed visceral hypersensitivity and somatic inflammatory pain, and using a model of neuropathic pain in TRPV1 null mice we confirmed that its analgesic properties were solely through the inhibition of TRPV1. We were surprised to find that BCTP administered orally induced only a maximal 0.6°C increase in core body temperature at the highest tested doses (30 and 100 mg/kg), contrasting markedly with N-[4-({6-[4-(trifluoromethyl)phenyl]pyrimidin-4-yl}oxy)-1,3-benzothiazol-2-yl]acetamide (AMG517), a clinically tested TRPV1 antagonist, which induced marked hyperthermia (>1°C) at doses eliciting submaximal reversal of capsaicin-induced hyperalgesia. The combined data indicate that TRPV1 antagonists with a classic polymodal inhibition profile can be identified where the analgesic action is separated from the effects on body temperature.

Effect of the C3a-receptor antagonist SB 290157 on anti-OVA polyclonal antibody-induced arthritis.

PubMed

Hutamekalin, Pilaiwanwadee; Takeda, Kohei; Tani, Mitsuhiro; Tsuga, Yuko; Ogawa, Naoki; Mizutani, Nobuaki; Yoshino, Shin

2010-01-01

It was investigated whether the C3a-receptor antagonist (C3aRA) SB 290157 was involved in the suppression of anti-OVA pAb-induced arthritis because it is well known that anaphylatoxin C3a plays a crucial role in the development of an effective inflammatory response during complement activation. Anti-OVA pAb-induced arthritis was induced in DBA/1J mice by administration of anti-OVA pAb 0.5 h prior to intra-articular (i.a.) injection of OVA (0 h). Two peaks of joint swelling were observed at 0.5 and 3 h. The role of C3aRA in arthritis was investigated by injection of SB 290157 at concentrations of 10 and 30 mg/kg at 0 and 2 h. The antagonist was able to reduce joint swelling only at 3 h, and about 50% inhibition of joint swelling was observed with the concentration of 30 mg/kg. The C3 level was significantly decreased at 3 h compared with naïve mice showing complement consumption. Furthermore, the C3 activation was observed and increased corresponding to the graded concentration of anti-OVA pAb. The results also revealed that the C3aRA was able to reduce the expression of IL-1beta in synovial tissue. Taken together, the results suggested that C3aRA may be effective in the inhibition of arthritis.

Evidence of CCR2-independent transmigration of Ly6C(hi) monocytes into the brain after permanent cerebral ischemia in mice.

PubMed

Chu, Hannah X; Kim, Hyun Ah; Lee, Seyoung; Broughton, Brad R S; Drummond, Grant R; Sobey, Christopher G

2016-04-15

Previously we showed that INCB3344, a CCR2 antagonist, inhibits transmigration of Ly6C(hi) monocytes into the brain after ischemia-reperfusion. Here we tested the effect of CCR2 inhibition during permanent cerebral ischemia. Mice were administered either vehicle (dimethyl sulfoxide/carboxymethylcellulose) or INCB3344 (30 or 100mg/kg IP) 1h before middle cerebral artery occlusion and at 2 and 6h after the initiation of ischemia. After 24h, we assessed functional outcome, infarct volume and quantified immune cells in blood and brain. The increase in circulating bone marrow-derived Ly6C(hi) monocytes, but not the infiltration of those cells into the brain, was blocked by the CCR2 antagonist. INCB3344 had no effect on either neurological deficit or infarct volume. Our data confirm that cerebral ischemia triggers a CCR2-dependent increase in circulating Ly6C(hi) monocytes, but suggest that in the absence of reperfusion these cells may transmigrate into the ischemic brain in a CCR2-independent manner. Copyright © 2016 Elsevier B.V. All rights reserved.

Histamine H3 receptors aggravate cerebral ischaemic injury by histamine-independent mechanisms

PubMed Central

Yan, Haijing; Zhang, Xiangnan; Hu, Weiwei; Ma, Jing; Hou, Weiwei; Zhang, Xingzhou; Wang, Xiaofen; Gao, Jieqiong; Shen, Yao; Lv, Jianxin; Ohtsu, Hiroshi; Han, Feng; Wang, Guanghui; Chen, Zhong

2014-01-01

The role of the histamine H3 receptor (H3R) in cerebral ischaemia/reperfusion (I/R) injury remains unknown. Here we show that H3R expression is upregulated after I/R in two mouse models. H3R antagonists and H3R knockout attenuate I/R injury, which is reversed by an H3R-selective agonist. Interestingly, H1R and H2R antagonists, a histidine decarboxylase (HDC) inhibitor and HDC knockout all fail to compromise the protection by H3R blockade. H3R blockade inhibits mTOR phosphorylation and reinforces autophagy. The neuroprotection by H3R antagonism is reversed by 3-methyladenine and siRNA for Atg7, and is diminished in Atg5−/− mouse embryonic fibroblasts. Furthermore, the peptide Tat-H3RCT414-436, which blocks CLIC4 binding with H3Rs, or siRNA for CLIC4, further increases I/R-induced autophagy and protects against I/R injury. Therefore, H3R promotes I/R injury while its antagonism protects against ischaemic injury via histamine-independent mechanisms that involve suppressing H3R/CLIC4 binding-activated autophagy, suggesting that H3R inhibition is a therapeutic target for cerebral ischaemia. PMID:24566390

Comparison of the ultrashort gonadotropin-releasing hormone agonist-antagonist protocol with microdose flare -up protocol in poor responders: a preliminary study

PubMed Central

Berker, Bülent; Duvan, Candan İltemir; Kaya, Cemil; Aytaç, Ruşen; Şatıroğlu, Hakan

2010-01-01

Objective To determine the potential effect of the ultrashort gonadotropin-releasing hormone (GnRH) agonist/GnRH antagonist protocol versus the microdose GnRH agonist protocol in poor responders undergoing intracytoplasmic sperm injection (ICSI). Material and Methods The patients in the Agonist-Antagonist Group (n=41) were administered the ultrashort GnRH-agonist/ antagonist protocol, while the patients in the Microdose Group (n=41) were stimulated according to the microdose flare-up protocol. The mean number of mature oocytes retrieved was the primary outcome measure. Fertilization rate, implantation rate per embryo and clinical pregnancy rates were secondary outcome measures. Results There was no differenc between the mean number of mature oocytes retrieved in the two groups. There were also no statistical differences between the two groups in terms of peak serum E2 level, canceled cycles, endometrial thickness on hCG day, number of 2 pronucleus and number of embryos transferred. However, the total gonadotropin consumption and duration of stimulation were significantly higher with the Agonist-Antagonist Group compared with the Microdose Group. The implantation and clinical pregnancy rates were similar between the two groups. Conclusion Despite the high dose of gonadotropin consumption and longer duration of stimulation with the ultrashort GnRH agonist/ antagonist protocol, it seems that the Agonist-Antagonist Protocol is not inferior to the microdose protocol in poor responders undergoing ICSI. PMID:24591934

A prostaglandin E2 receptor antagonist prevents pregnancies during a preclinical contraceptive trial with female macaques

PubMed Central

Peluffo, M.C.; Stanley, J.; Braeuer, N.; Rotgeri, A.; Fritzemeier, K.-H.; Fuhrmann, U.; Buchmann, B.; Adevai, T.; Murphy, M.J.; Zelinski, M.B.; Lindenthal, B.; Hennebold, J.D.; Stouffer, R.L.

2014-01-01

STUDY QUESTION Can administration of a prostaglandin (PG) E2 receptor 2 (PTGER2) antagonist prevent pregnancy in adult female monkeys by blocking periovulatory events in the follicle without altering menstrual cyclicity or general health? SUMMARY ANSWER This is the first study to demonstrate that a PTGER2 antagonist can serve as an effective non-hormonal contraceptive in primates. WHAT IS KNOWN ALREADY The requirement for PGE2 in ovulation and the release of an oocyte surrounded by expanded cumulus cells (cumulus–oocyte expansion; C-OE) was established through the generation of PTGS2 and PTGER2 null-mutant mice. A critical role for PGE2 in primate ovulation is supported by evidence that intrafollicular injection of indomethacin in rhesus monkeys suppressed follicle rupture, whereas co-injection of PGE2 with indomethacin resulted in ovulation. STUDY DESIGN, SIZE, DURATION First, controlled ovulation protocols were performed in adult, female rhesus monkeys to analyze the mRNA levels for genes encoding PGE2 synthesis and signaling components in the naturally selected pre-ovulatory follicle at different times after the ovulatory hCG stimulus (0, 12, 24, 36 h pre-ovulation; 36 h post-ovulation, n = 3–4/time point). Second, controlled ovarian stimulation cycles were utilized to obtain multiple cumulus–oocyte complexes (COCs) from rhesus monkeys to evaluate the role of PGE2 in C-OE in vitro (n = 3–4 animals/treatment; ≥3 COCs/animal/treatment). Third, adult cycling female cynomolgus macaques were randomly assigned (n = 10/group) to vehicle (control) or PTGER2 antagonist (BAY06) groups to perform a contraceptive trial. After the first treatment cycle, a male of proven fertility was introduced into each group and they remained housed together for the duration of the 5-month contraceptive trial that was followed by a post-treatment reversibility trial. PARTICIPANTS/MATERIALS, SETTING, METHODS Quantitative real-time PCR, COC culture and expansion, immunofluorescence/confocal microscopy, enzyme immunoassay, contraceptive trial, ultrasonography, complete blood counts, serum biochemistry tests and blood lipid profiles. MAIN RESULTS AND THE ROLE OF CHANCE Several mRNAs encoding proteins involved in PGE2 synthesis, metabolism and signaling increase (P < 0.05) in the periovulatory follicle after administration of an ovulatory hCG bolus. PGE2 signaling through PTGER2 induces cumulus cell expansion and production of hyaluronic acid, which are critical events for fertilization. Moreover, chronic administration of a selective PTGER2 antagonist resulted in a significant (P < 0.05 versus vehicle-treated controls) contraceptive effect without altering steroid hormone patterns or menstrual cyclicity during a 5-months contraceptive trial. Fertility recovered as early as 1 month after ending treatment. LIMITATIONS, REASONS FOR CAUTION This is a proof-of-concept study in a non-human primate model. Further investigations are warranted to elucidate the mechanism(s) of PTGER2 antagonist action in the primate ovary. Although PTGER2 antagonist treatment did not produce any obvious undesirable effects, improvements in the mode of administration, as well as the efficacy of these compounds, are necessary to consider such a contraceptive for women. WIDER IMPLICATIONS OF THE FINDINGS Monitoring as well as improving the efficacy and safety of female contraceptives is an important public health activity. Even though hormonal contraceptives are effective for women, concerns remain regarding their side-effects and long-term use because of the widespread actions of such steroidal products in many tissues. Moreover, some women cannot take hormones for medical reasons. Thus, development of non-hormonal contraceptives for women is warranted. STUDY FUNDING/COMPETING INTEREST(S) Supported by Bayer HealthCare Pharmaceuticals, The Eunice Kennedy Shriver NICHD Contraceptive Development and Research Center (U54 HD055744), NIH Office of the Director (Oregon National Primate Research Center P51 OD011092), and a Lalor Foundation Postdoctoral Basic Research Fellowship (MCP). The use of the Leica confocal was supported by grant number S10RR024585. Some of the authors (N.B., A.R., K.-H.F., U.F., B.B. and B.L.) are employees of Bayer Healthcare Pharma. PMID:24781425

Purinoceptor modulation of noradrenaline release in rat tail artery: tonic modulation mediated by inhibitory P2Y- and facilitatory A2A-purinoceptors.

PubMed Central

Gonçalves, J.; Queiroz, G.

1996-01-01

1. The effects of analogues of adenosine and ATP on noradrenaline release elicited by electrical stimulation (5 Hz, 2700 pulses) were studied in superfused preparations of rat tail artery. The effects of purinoceptor antagonists, of adenosine deaminase and of adenosine uptake blockade were also examined. Noradrenaline was measured by h.p.l.c. electrochemical detection. 2. The A1-adenosine receptor agonist, N6-cyclopentyladenosine (CPA; 0.1-100 nM) reduced, whereas the A2A-receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680; 3-30 nM) increased evoked noradrenaline overflow. These effects were antagonized by the A1-adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 20 nM) and the A2-adenosine receptor antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX; 100 nM), respectively. The P2Y-purinoceptor agonist, 2-methylthio-ATP (1-100 microM) reduced noradrenaline overflow, an effect prevented by the P2-purinoceptor antagonist, cibacron blue 3GA (100 microM) and suramin (100 microM). 3. Adenosine deaminase (2 u ml-1), DMPX (100 nM) and inhibition of adenosine uptake with S-(p-nitrobenzyl)-6-thioinosine (NBTI; 50 nM) decreased evoked noradrenaline overflow. DPCPX alone did not change noradrenaline overflow but prevented the inhibition caused by NBTI. The P2Y-purinoceptor antagonist, cibacron blue 3GA (100 microM) increased evoked noradrenaline overflow as did suramin, a non-selective P2-antagonist. 4. It is concluded that, in rat tail artery, inhibitory (A1 and P2Y) and facilitatory (A2A) purinoceptors are present and modulate noradrenaline release evoked by electrical stimulation. Endogenous purines tonically modulate noradrenaline release through activation of inhibitory P2Y and facilitatory A2A purinoceptors, whereas a tonic activation of inhibitory A1 purinoceptors seems to be prevented by adenosine uptake. PMID:8825357

The steroidogenic response and corpus luteum expression of the steroidogenic acute regulatory protein after human chorionic gonadotropin administration at different times in the human luteal phase.

PubMed

Kohen, Paulina; Castro, Olga; Palomino, Alberto; Muñoz, Alex; Christenson, Lane K; Sierralta, Walter; Carvallo, Pilar; Strauss, Jerome F; Devoto, Luigi

2003-07-01

This study was designed 1) to assess corpus luteum (CL) steroidogenesis in response to exogenous human chorionic gonadotropin (hCG) at different times during the luteal phase, 2) to examine the effect of hCG on steroidogenic acute regulatory protein (StAR) expression within the CL, 3) to correlate StAR expression and luteal steroidogenic responses to hCG, and 4) to determine whether endogenous LH regulates ovarian steroidogenesis in the early luteal phase. Blood was collected before and after hCG treatment for steroid and hCGbeta determinations. CL were obtained at the time of surgery to assess StAR gene and protein expression. During the early luteal phase various women received the GnRH antagonist for 24-48 h; some of them also received hCG 24 h after the GnRH antagonist. A slight steroidogenic response to hCG was observed in early luteal phase; 17alpha-hydroxyprogesterone, but not progesterone (P4), levels were significantly increased 8 h post-hCG, indicating a differential response by the granulosa and theca-lutein cells. The 1.6- and 4.4-kb StAR transcripts and the 37-kDa preprotein and 30-kDa mature StAR protein did not change post-hCG administration in early luteal phase CL. In contrast, the StAR 4.4- and 1.6-kb transcripts diminished significantly (P < 0.05) after the antagonist treatment. Immunohistochemical staining for StAR protein was weak, particularly in granulosa-lutein cells. Treatment with hCG restored StAR mRNA and protein and plasma P4 levels within 24 h in antagonist-treated women. hCG stimulated the highest plasma concentrations of P4 and estradiol in the midluteal phase, indicating its greatest steroidogenic capacity. Midluteal tissue StAR gene and protein expression increased by 1.6- and 1.4-fold after 24 h of hCG treatment, respectively. Administration of hCG resulted in the greatest increment in plasma P4 (4-fold) and 17alpha-hydroxyprogesterone (3-fold) levels over baseline in the late luteal phase. This was associated with an increase in StAR mRNA (3.5-fold) and protein (1.8-fold). Collectively, these data indicate that 1) the hCG-stimulated steroidogenic response is dependent on the age of the CL; 2) the early luteal phase CL is relatively insensitive to exogenous hCG in the presence of normal pituitary gonadotropin support, but becomes responsive when the latter is withdrawn; 3) the hCG-stimulated steroidogenic response in the mid- and late luteal phase is correlated with increased StAR mRNA and protein abundance; and 4) there are differential responses of small and large luteal cells to hCG stimulation that depend upon the age of the CL.

Aspirin- and Indomethacin-Induced Ulcers and their Antagonism by Anthihistamines

NASA Technical Reports Server (NTRS)

Brown, Patricia A.; Sawrey, James M.; Vernikos, Joan

1978-01-01

Gastric ulceration produced by aspirin and indomethacin was compared in acutely stressed and non-stressed rats. We found a synergism between these anti-inflammatory agents and acute stress in the production of gastric ulcers. Even at relatively high doses, neither agent caused appreciable gastric damage in non-stressed rats, whereas moderate doses of both agents produced massive ulceration in stressed rats. The synergism appears unrelated to the effect of these agents on the pituitary-adrenal response. The size and regional distribution of ulcers produced by aspirin and indomethacin in stressed rats were comparable. However, the dose--response curves of the two drugs were markedly dissimilar. Furthermore, the ulceration produced by indomethacin was attenuated by both H(sub 1) and H(sub 2) histamine receptor antagonists, whereas ulceration produced by aspirin was attenuated only by an H(sub 2) antagonist. The results suggest that the ulcerogenic mechanism of indomethacin may differ from that of aspirin and add to the growing evidence on the importance of endogenous histamine in various forms of gastric ulceration.

Associations of Proton-Pump Inhibitors and H2 Receptor Antagonists with Chronic Kidney Disease: A Meta-Analysis.

PubMed

Wijarnpreecha, Karn; Thongprayoon, Charat; Chesdachai, Supavit; Panjawatanana, Panadeekarn; Ungprasert, Patompong; Cheungpasitporn, Wisit

2017-10-01

The aim of this meta-analysis was to assess the risks of chronic kidney disease (CKD) and/or end-stage kidney disease (ESRD) in patients who are taking proton-pump inhibitors (PPIs) and/or H2 receptor antagonists (H2RAs). Comprehensive literature review was conducted utilizing MEDLINE and EMBASE databases through April 2017 to identify all studies that investigated the risks of CKD or ESRD in patients taking PPIs/H2RAs versus those without PPIs/H2RAs. Pooled risk ratios (RR) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method of DerSimonian and Laird. The protocol for this study is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017067252). Five studies with 536,902 participants were patients were identified and included in the data analysis. When compared with non-PPIs users, the pooled risk ratio (RR) of CKD or ESRD in patients with PPI use was 1.33 (95% CI 1.18-1.51). Pre-specified subgroup analysis (stratified by CKD or ESRD status) demonstrated pooled RRs of 1.22 (95% CI 1.14-1.30) for association between PPI use and CKD and 1.88 (95% CI 1.71-2.06) for association between PPI use and ESRD, respectively. However, there was no association between the use of H2RAs and CKD with a pooled RR of 1.02 (95% CI 0.83-1.25). When compared with the use of H2RAs, the pooled RR of CKD in patients with PPI use was 1.29 (95% CI 1.22-1.36). Our study demonstrates statistically significant 1.3-fold increased risks of CKD and ESRD in patients using PPIs, but not in patients using H2RAs.

Intestinal alkaline phosphatase regulates protective surface microclimate pH in rat duodenum.

PubMed

Mizumori, Misa; Ham, Maggie; Guth, Paul H; Engel, Eli; Kaunitz, Jonathan D; Akiba, Yasutada

2009-07-15

Regulation of localized extracellular pH (pH(o)) maintains normal organ function. An alkaline microclimate overlying the duodenal enterocyte brush border protects the mucosa from luminal acid. We hypothesized that intestinal alkaline phosphatase (IAP) regulates pH(o) due to pH-sensitive ATP hydrolysis as part of an ecto-purinergic pH regulatory system, comprised of cell-surface P2Y receptors and ATP-stimulated duodenal bicarbonate secretion (DBS). To test this hypothesis, we measured DBS in a perfused rat duodenal loop, examining the effect of the competitive alkaline phosphatase inhibitor glycerol phosphate (GP), the ecto-nucleoside triphosphate diphosphohydrolase inhibitor ARL67156, and exogenous nucleotides or P2 receptor agonists on DBS. Furthermore, we measured perfusate ATP concentration with a luciferin-luciferase bioassay. IAP inhibition increased DBS and luminal ATP output. Increased luminal ATP output was partially CFTR dependent, but was not due to cellular injury. Immunofluorescence localized the P2Y(1) receptor to the brush border membrane of duodenal villi. The P2Y(1) agonist 2-methylthio-ADP increased DBS, whereas the P2Y(1) antagonist MRS2179 reduced ATP- or GP-induced DBS. Acid perfusion augmented DBS and ATP release, further enhanced by the IAP inhibitor l-cysteine, and reduced by the exogenous ATPase apyrase. Furthermore, MRS2179 or the highly selective P2Y(1) antagonist MRS2500 co-perfused with acid induced epithelial injury, suggesting that IAP/ATP/P2Y signalling protects the mucosa from acid injury. Increased DBS augments IAP activity presumably by raising pH(o), increasing the rate of ATP degradation, decreasing ATP-mediated DBS, forming a negative feedback loop. The duodenal epithelial brush border IAP-P2Y-HCO(3-) surface microclimate pH regulatory system effectively protects the mucosa from acid injury.

Cardioprotective effects of calcitonin gene-related peptide in isolated rat heart and in H9c2 cells via redox signaling.

PubMed

Tullio, Francesca; Penna, Claudia; Cabiale, Karine; Femminò, Saveria; Galloni, Marco; Pagliaro, Pasquale

2017-06-01

The calcitonin-gene-related-peptide (CGRP) release is coupled to the signaling of Angeli's salt in determining vasodilator effects. However, it is unknown whether CGRP is involved in Angeli's salt cardioprotective effects and which are the mechanisms of protection. We aimed to determine whether CGRP is involved in myocardial protection induced by Angeli's salt. We also analyzed the intracellular signaling pathway activated by CGRP. Isolated rat hearts were pre-treated with Angeli's salt or Angeli's salt plus CGRP 8-37 , a specific CGRP-receptor antagonist, and subjected to ischemia (30-min) and reperfusion (120-min). Moreover, we studied CGRP-induced protection during oxidative stress (H 2 O 2 ) and hypoxia/reoxygenation protocols in H9c2 cardiomyocytes. Cell vitality and mitochondrial membrane potential (ΔYm, MMP) were measured using MTT and JC-1 dyes. Angeli's salt reduced infarct size and ameliorated post-ischemic cardiac function via a CGRP-receptor-dependent mechanism. Pre-treatment with CGRP increased H9c2 survival upon challenging with either H 2 O 2 (redox stress) or hypoxia/reoxygenation (H/R stress). Under these stress conditions, reduction in MMP and cell death were partly prevented by CGRP. These CGRP beneficial effects were blocked by CGRP 8-37. During H/R stress, pre-treatment with either CGRP-receptor, protein kinase C (PKC) or mitochondrial K ATP channel antagonists, and pre-treatment with an antioxidant (2-mercaptopropionylglycine) blocked the protection mediated by CGRP. In conclusion, CGRP is involved in the cardioprotective effects of Angeli's salt. In H9c2 cardiomyocytes, CGRP elicits PKC-dependent and mitochondrial-K ATP -redox-dependent mechanisms. Hence, CGRP is an important factor in the redox-sensible cardioprotective effects of Angeli's salt. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The rate of high ovarian response in women identified at risk by a high serum AMH level is influenced by the type of gonadotropin.

PubMed

Arce, Joan-Carles; Klein, Bjarke M; La Marca, Antonio

2014-06-01

The aim was to compare ovarian response and clinical outcome of potential high-responders after stimulation with highly purified menotropin (HP-hMG) or recombinant follicle-stimulating hormone (rFSH) for in vitro fertilisation/intracytoplasmic sperm injection. Retrospective analysis was performed on data collected in two randomized controlled trials, one conducted following a long GnRH agonist protocol and the other with an antagonist protocol. Potential high-responders (n = 155 and n = 188 in the agonist and antagonist protocol, respectively) were defined as having an initial anti-Müllerian hormone (AMH) value >75th percentile (5.2 ng/ml). In both protocols, HP-hMG stimulation in women in the high AMH category was associated with a significantly lower occurrence of high response (≥15 oocytes retrieved) than rFSH stimulation; 33% versus 51% (p = 0.025) and 31% versus 49% (p = 0.015) in the long agonist and antagonist protocol, respectively. In the potential high-responder women, trends for improved live birth rate were observed with HP-hMG compared with rFSH (long agonist protocol: 33% versus 20%, p = 0.074; antagonist protocol: 34% versus 23%, p = 0.075; overall population: 34% versus 22%, p = 0.012). In conclusion, the type of gonadotropin used for ovarian stimulation influences high-response rates and potentially clinical outcome in women identified as potential high-responders.

Multiple target of hAmylin on rat primary hippocampal neurons.

PubMed

Zhang, Nan; Yang, Shengchang; Wang, Chang; Zhang, Jianghua; Huo, Lifang; Cheng, Yiru; Wang, Chuan; Jia, Zhanfeng; Ren, Leiming; Kang, Lin; Zhang, Wei

2017-02-01

Alzheimer's disease (AD) and type II diabetes mellitus (DM2) are the most common aging-related diseases and are characterized by β-amyloid and amylin accumulation, respectively. Multiple studies have indicated a strong correlation between these two diseases. Amylin oligomerization in the brain appears to be a novel risk factor for developing AD. Although amylin aggregation has been demonstrated to induce cytotoxicity in neurons through altering Ca 2+ homeostasis, the underlying mechanisms have not been fully explored. In this study, we investigated the effects of amylin on rat hippocampal neurons using calcium imaging and whole-cell patch clamp recordings. We demonstrated that the amylin receptor antagonist AC187 abolished the Ca 2+ response induced by low concentrations of human amylin (hAmylin). However, the Ca 2+ response induced by higher concentrations of hAmylin was independent of the amylin receptor. This effect was dependent on extracellular Ca 2+ . Additionally, blockade of L-type Ca 2+ channels partially reduced hAmylin-induced Ca 2+ response. In whole-cell recordings, hAmylin depolarized the membrane potential. Moreover, application of the transient receptor potential (TRP) channel antagonist ruthenium red (RR) attenuated the hAmylin-induced increase in Ca 2+ . Single-cell RT-PCR demonstrated that transient receptor potential vanilloid 4 (TRPV4) mRNA was expressed in most of the hAmylin-responsive neurons. In addition, selective knockdown of TRPV4 channels inhibited the hAmylin-evoked Ca 2+ response. These results indicated that different concentrations of hAmylin act through different pathways. The amylin receptor mediates the excitatory effects of low concentrations of hAmylin. In contrast, for high concentrations of hAmylin, hAmylin aggregates precipitated on the neuronal membrane, activated TRPV4 channels and subsequently triggered membrane voltage-gated calcium channel opening followed by membrane depolarization. Therefore, our data suggest that TRPV4 is a key molecular mediator for the cytotoxic effects of hAmylin on hippocampal neurons. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ciproxifan, an H3 receptor antagonist, improves short-term recognition memory impaired by isoflurane anesthesia.

PubMed

Ding, Fang; Zheng, Limin; Liu, Min; Chen, Rongfa; Leung, L Stan; Luo, Tao

2016-08-01

Exposure to volatile anesthetics has been reported to cause temporary or sustained impairments in learning and memory in pre-clinical studies. The selective antagonists of the histamine H3 receptors (H3R) are considered to be a promising group of novel therapeutic agents for the treatment of cognitive disorders. The aim of this study was to evaluate the effect of H3R antagonist ciproxifan on isoflurane-induced deficits in an object recognition task. Adult C57BL/6 J mice were exposed to isoflurane (1.3 %) or vehicle gas for 2 h. The object recognition tests were carried at 24 h or 7 days after exposure to anesthesia to exploit the tendency of mice to prefer exploring novel objects in an environment when a familiar object is also present. During the training phase, two identical objects were placed in two defined sites of the chamber. During the test phase, performed 1 or 24 h after the training phase, one of the objects was replaced by a new object with a different shape. The time spent exploring each object was recorded. A robust deficit in object recognition memory occurred 1 day after exposure to isoflurane anesthesia. Isoflurane-treated mice spent significantly less time exploring a novel object at 1 h but not at 24 h after the training phase. The deficit in short-term memory was reversed by the administration of ciproxifan 30 min before behavioral training. Isoflurane exposure induces reversible deficits in object recognition memory. Ciproxifan appears to be a potential therapeutic agent for improving post-anesthesia cognitive memory performance.

Effects of muscarinic receptor agonists and antagonists on alpha 2-adrenoceptors in rat brain.

PubMed

Hollingsworth, P J; Smith, C B

1989-09-13

The specific binding of [3H]clonidine to alpha 2-adrenoceptors on neural membranes isolated from six brain areas was determined with rats treated for various periods of time with the muscarinic agonists, oxotremorine or pilocarpine, or with the muscarinic antagonists atropine, atropine methyl nitrate, scopolamine and scopolamine methyl bromide. Administration of pilocarpine, 10 mg/kg, twice daily i.p. for 1 and 14 days increased markedly the number of alpha 2-adrenoceptors on neural membranes from all six brain areas. In contrast, oxotremorine, 0.3 mg/kg, twice daily i.p., for 7 days decreased the number of alpha 2-adrenoceptors on membranes from all brain areas except the brainstem and caudate nucleus. Both atropine and scopolamine increased the density of alpha 2-adrenoceptors in specific brain areas. Neither atropine methyl nitrate nor scopolamine methyl bromide had an appreciable effect upon the specific binding of [3H]clonidine to neural membranes from most brain areas.

The relevance of kalikrein-kinin system via activation of B2 receptor in LPS-induced fever in rats.

PubMed

Soares, Denis de Melo; Santos, Danielle R; Rummel, Christoph; Ott, Daniela; Melo, Míriam C C; Roth, Joachim; Calixto, João B; Souza, Glória E P

2017-11-01

This study evaluated the involvement of endogenous kallikrein-kinin system and the bradykinin (BK) B 1 and B 2 receptors on LPS- induced fever and the POA cells involved in this response. Male Wistar rats received either i.v. (1 mg/kg), i.c.v. (20 nmol) or i.h. (2 nmol) injections of icatibant (B 2 receptor antagonist) 30 or 60 min, respectively, before the stimuli. DALBK (B 1 receptor antagonist) was given either 15min before BK (i.c.v.) or 30 min before LPS (i.v.). Captopril (5 mg/kg, sc.,) was given 1 h prior LPS or BK. Concentrations of BK and total kininogenon CSF, plasma and tissue kallikrein were evaluated. Rectal temperatures (rT) were assessed by telethermometry. Ca ++ signaling in POA cells was performed in rat pup brain tissue microcultures. Icatibant reduced LPS fever while, captopril exacerbated that response, an effect abolished by icatibant. Icatibant (i.h.) reduced fever to BK (i.h.) but not that induced by LPS (i.v.). BK increased intracellular calcium concentration in neurons and astrocytes. LPS increased levels of bradykinin, tissue kallikrein and total kininogen. BK (i.c.v.) increased rT and decreased tail skin temperature. Captopril potentiated BK-induced fever an effect abolished by icatibant. DALBK reduced the fever induced by BK. BK (i.c.v.) increased the CSF PGE 2 concentration. Effect abolished by indomethacin (i.p.). LPS activates endogenous kalikrein-kinin system leading to production of BK, which by acting on B 2 -receptors of POA cells causes prostaglandin synthesis that in turn produces fever. Thus, a kinin B 2 -receptor antagonist that enters into the brain could constitute a new and interesting strategy to treat fever. Copyright © 2017 Elsevier Ltd. All rights reserved.

A long-lasting oral preformulation of the angiotensin II AT1 receptor antagonist losartan.

PubMed

De Paula, Washington X; Denadai, Ângelo M L; Braga, Aline N G; Shastri, V Prasad; Pinheiro, Sérgio V B; Frezard, Frederic; Santos, Robson A S; Sinisterra, Ruben D

2018-05-10

Losartan (Los), a non-peptidic orally active agent, reduces arterial pressure through specific and selective blockade of angiotensin II receptor AT1. However, this widely used AT1 antagonist presents low bioavailability and needs once or twice a day dosage. In order to improve its bioavailability, we used the host: guest strategy based on β-cyclodextrin (βCD). The results suggest that Los included in βCD showed a typical pulsatile release pattern after oral administration to rats, with increasing the levels of plasma of Los. In addition, the inclusion compound presented oral efficacy for 72 h, in contrast to Los alone, which shows antagonist effect for only 6 h. In transgenic (mREN2)L27 rats, the Los/βCD complex reduced blood pressure for about 6 d, whereas Los alone reduced blood pressure for only 2 d. More importantly, using this host: guest strategy, sustained release of Los for over a week via the oral route can be achieved without the need for encapsulation in a polymeric carrier. The proposed preformulation increased the efficacy reducing the dose or spacing between each dose intake.

Antagonistic effect of chosen lactic acid bacteria strains on Salmonella species in meat and fermented sausages.

PubMed

Gomółka-Pawlicka, M; Uradziński, J

2003-01-01

The aim of this study was to determine of influence of 15 strains of lactic acid bacteria on the growth of 7 Salmonella spp. strains in model set-ups, and in meat and ripened fermented sausages. The investigations were performed within the framework of three alternate stages which differed in respect to the products studied, the number of Lactobacillus spp. strains and, partly, methodological approach. The ratio between lactic acid bacteria and Salmonella strains studied was, depending on the alternate, 1:1, 1:2 and 2:1, respectively. The investigations also covered the water activity (a(w)) and pH of the tested products. The results obtained are shown in 12 figures and suggest that all the lactic acid bacteria strains used within the framework of the model set-ups showed antagonistic effect on all the Salmonella spp. strains. However, these abilities were not observed with respect to some lactic acid bacteria strains in meat and fermented sausage. The temperature and length of the incubation period of sausages, but not a(w) and pH, were found to have a distinct influence on the antagonistic interaction between the bacteria.

High-Resolution Solid-State NMR Spectroscopy: Characterization of Polymorphism in Cimetidine, a Pharmaceutical Compound

ERIC Educational Resources Information Center

Pacilio, Julia E.; Tokarski, John T.; Quiñones, Rosalynn; Iuliucci, Robbie J.

2014-01-01

High-resolution solid-state NMR (SSNMR) spectroscopy has many advantages as a tool to characterize solid-phase material that finds applications in polymer chemistry, nanotechnology, materials science, biomolecular structure determination, and others, including the pharmaceutical industry. The technology associated with achieving high resolution…

Central endogenous histamine modulates sympathetic outflow through H3 receptors in the conscious rabbit

PubMed Central

Charles, Julian; Angus, James A; Wright, Christine E

2003-01-01

This study examined the role of histamine H3 receptors in vagal and sympathetic autonomic reflexes in the conscious rabbit, and in rabbit and guinea-pig isolated right atria. The baroreceptor-heart rate reflex (baroreflex), Bezold-Jarisch-like and nasopharyngeal reflexes were assessed after these treatments (i.v.; with H1 and H2 receptor block): (i) vehicle (saline; n=11); (ii) H3 receptor agonist, (R)-α-methylhistamine (R-α-MH) 100 μg kg−1+100 μg kg−1 h−1 (n=9); (iii) H3 receptor antagonist, thioperamide 1 mg kg−1+1 mg kg−1 h−1 (n=11); (iv) R-α-MH and thioperamide (n=6); and (v) H2 and H3 antagonist, burimamide 6.3 mg kg−1+6.3 mg kg−1 h−1 (n=4). R-α-MH caused a thioperamide-sensitive fall in mean arterial pressure (MAP) of 8±1 mmHg and tachycardia of 18±2 bpm (P<0.0005). Burimamide was without effect, however thioperamide elicited an increase in MAP of 4±1 mmHg (P<0.01), but no change in heart rate (HR). R-α-MH caused a 44% decrease in the average gain of the baroreflex (P=0.0001); this effect was antagonised by thioperamide. Thioperamide caused a parallel rightward shift in the barocurve with an increase in MAP of 5 mmHg (P<0.05). Burimamide had no effect on the baroreflex. The vagally mediated bradycardia elicited by the Bezold-Jarisch and nasopharyngeal reflexes was unaffected by H3 receptor ligand administration. R-α-MH (⩽10 μM) caused a thioperamide-sensitive depression of both sympathetic and vagal responses in guinea-pig atria, but had no effect in rabbit atria. As H3 receptor activation caused a significant decrease in baroreflex gain without affecting HR range, the former is unlikely to be simply due to peripheral sympatholysis (supported by the lack of effect in isolated atria). Central H3 receptors may have a tonic role in the baroreflex as thioperamide caused a rightward resetting of the barocurve. In contrast, the peripherally acting H3 antagonist burimamide was without effect. These findings suggest a role for central histamine H3 receptors in cardiovascular homeostasis in the rabbit. PMID:12839877

H89 dihydrochloride hydrate and calphostin C lower the body temperature through TRPV1.

PubMed

Bao, Dongyan; Zhao, Wenqing; Dai, Congcong; Wan, Hongmei; Cao, Yu

2018-01-01

The transient receptor potential vanilloid (TRPV1) serves as a negative regulator of body temperature, and during fever conditions its expression can lead to a decrease in temperature. TRPV1 is regulated by a variety of enzymes; however, it is currently unclear whether the regulation of TRPV1 phosphorylation may serve a role in the increase in TRPV1 expression during fever. In the present study, using an in vivo experimental method, rat brain ventricles were injected with the protein kinase A (PKA) antagonist, H89, and the protein kinase C (PKC) antagonist, calphostin C, and fever was induced using lipopolysaccharide (LPS) in order to detect the expression of TRPV1 and phosphorylated (p‑)TRPV1, the intracellular Ca2+ concentration [(Ca2+)i] of hypothalami and rat body temperature. The results demonstrated that following the generation of fever using LPS, the expressions of TRPV1 and p‑TRPV1, and hypothalamic [Ca2+]i markedly increased. In addition, following an injection with the PKA or PKC antagonist, the temperature increased further due to the inhibition of p‑TRPV1. Thus, it was hypothesized that PKA and PKC may be involved in TRPV1 phosphorylation, resulting in a temperature reduction during LPS‑induced fever conditions.

H89 dihydrochloride hydrate and calphostin C lower the body temperature through TRPV1

PubMed Central

Bao, Dongyan; Zhao, Wenqing; Dai, Congcong; Wan, Hongmei; Cao, Yu

2018-01-01

The transient receptor potential vanilloid (TRPV1) serves as a negative regulator of body temperature, and during fever conditions its expression can lead to a decrease in temperature. TRPV1 is regulated by a variety of enzymes; however, it is currently unclear whether the regulation of TRPV1 phosphorylation may serve a role in the increase in TRPV1 expression during fever. In the present study, using an in vivo experimental method, rat brain ventricles were injected with the protein kinase A (PKA) antagonist, H89, and the protein kinase C (PKC) antagonist, calphostin C, and fever was induced using lipopolysaccharide (LPS) in order to detect the expression of TRPV1 and phosphorylated (p-)TRPV1, the intracellular Ca2+ concentration [(Ca2+)i] of hypothalami and rat body temperature. The results demonstrated that following the generation of fever using LPS, the expressions of TRPV1 and p-TRPV1, and hypothalamic [Ca2+]i markedly increased. In addition, following an injection with the PKA or PKC antagonist, the temperature increased further due to the inhibition of p-TRPV1. Thus, it was hypothesized that PKA and PKC may be involved in TRPV1 phosphorylation, resulting in a temperature reduction during LPS-induced fever conditions. PMID:29257197

Modulation of food consumption and sleep-wake cycle in mice by the neutral CB1 antagonist ABD459.

PubMed

Goonawardena, Anushka V; Plano, Andrea; Robinson, Lianne; Ross, Ruth; Greig, Iain; Pertwee, Roger G; Hampson, Robert E; Platt, Bettina; Riedel, Gernot

2015-04-01

The brain endocannabinoid system is a potential target for the treatment of psychiatric and metabolic conditions. Here, a novel CB1 receptor antagonist (ABD459) was synthesized and assayed for pharmacological efficacy in vitro and for modulation of food consumption, vigilance staging and cortical electroencephalography in the mouse. ABD459 completely displaced the CB1 agonist CP99540 at a Ki of 8.6 nmol/l, and did not affect basal, but antagonized CP55940-induced GTPγS binding with a KB of 7.7 nmol/l. Acute ABD459 (3-20 mg/kg) reliably inhibited food consumption in nonfasted mice, without affecting motor activity. Active food seeking was reduced for 5-6 h postdrug, with no rebound after washout. Epidural recording of electroencephalogram confirmed that ABD459 (3 mg/kg) robustly reduced rapid eye movement (REM) sleep, with no alterations of wakefulness or non-REM sleep. Effects were strongest during 3 h postdrug, followed by a progressive washout period. The CB1 antagonist AM251 (3 mg/kg) and agonist WIN-55,212-2 (WIN-2: 3 mg/kg) also reduced REM, but variously affected other vigilance stages. WIN-2 caused a global suppression of normalized spectral power. AM251 and ABD459 lowered delta power and increased power in the theta band in the hippocampus, but not the prefrontal cortex. The neutral antagonist ABD459 thus showed a specific role of endocannabinoid release in attention and arousal, possibly through modulation of cholinergic activity.

Pretreatment of liver grafts in vivo by γ-aminobutyric acid receptor regulation reduces cold ischemia/warm reperfusion injury in rat

PubMed Central

Hori, Tomohide; Gardner, Lindsay B.; Hata, Toshiyuki; Chen, Feng; Baine, Ann-Marie T.; Uemoto, Shinji; Nguyen, Justin H.

2014-01-01

Summary Background: Gamma-aminobutyric acid (GABA) is found throughout the body. The regulation of GABA receptor (GABAR) reduces oxidative stress (OS). Ischemia/reperfusion injury after orthotopic liver transplantation (OLT) causes OS-induced graft damage. The effects of GABAR regulation in donors in vivo were investigated. Material/Methods: Donor rats received saline, a GABAR agonist or GABAR antagonist 4 h before surgery. Recipient rats were divided into four groups according to the donor treatments: laparotomy, OLT with saline, OLT with GABAR agonist and OLT with GABAR antagonist. Histopathological, biochemical and immunohistological examinations were performed at 6, 12 and 24 h after OLT. Protein assays were performed at 6 h after OLT. The 4-hydroxynonenal (4-HNE), ataxia-telangiectasia mutated kinase (ATM), phosphorylated histone H2AX (γH2AX), phosphatidylinositol-3 kinase (PI3K), Akt and superoxide dismutase (SOD) were assessed by western blot analysis. Results: In the univariate analysis, histopathological and biochemical profiles verified that the GABAR agonist reduced graft damage. Immunohistology revealed that the GABAR agonist prevented the induction of apoptosis. Measurement of 4-4-HNE levels confirmed OS-induced damage after OLT, and the GABAR agonist improved this damage. In the γH2AX, PI3K, Akt and antioxidant enzymes (SODs), ATM and H2AX were greatly increased after OLT, and were reduced by the GABAR agonist. In the multivariate analyses between multiple groups, histopathological assessment, aspartate aminotransferase level, immunohistological examinations for apoptotic induction and γH2AX showed statistical differences. Conclusions: A specific agonist demonstrated regulation of GABAR in vivo in the liver. This activation in vivo reduced OS after OLT via the ATM/H2AX pathway. PMID:23792534

Synthesis and antidepressant properties of novel 2-substituted 4,5-dihydro-1H-imidazole derivatives.

PubMed

Wentland, M P; Bailey, D M; Alexander, E J; Castaldi, M J; Ferrari, R A; Haubrich, D R; Luttinger, D A; Perrone, M H

1987-08-01

A unique combination of alpha 2-adrenoreceptor antagonist and serotonin-selective reuptake inhibitory activities has been identified in a series of 2-substituted 4,5-dihydro-1H-imidazole derivatives. This combination of blocking activities has provided one of these derivatives, napamezole hydrochloride (2), with potential as an antidepressant. A discussion of the syntheses of these compounds includes a convenient method for the conversion of nitriles to imidazolines with ethylenediamine and trimethylaluminum.

Use of the mouse jumping test for estimating antagonistic potencies of morphine antagonists.

PubMed

Cowan, A

1976-03-01

The potencies of 19 reference morphine antagonists have been compared in a modified version of the mouse jumping test. Mice were each implanted subcutaneously with one 75 mg pellet of morphine. Antagonist challenge took place 72 h later and the incidence of repetitive vertical-jumping was monitored over 1 h. A high Pearson correlation coefficient (r = 0.997) was found between quantitative assays based on the total number of jumps per mouse and quantal assays based on mice jumping at least 6 times. A comparison of relative potencies obtained with the mouse test and with non-withdrawn morphine-dependent monkeys gave a Spearman rank order coefficient of 0.91 while a similar comparison with values obtained with the guinea-pig isolated ileum preparation also gave a high correlation coefficient (r= 0.92). Whereas it is difficult to assess the antagonistic component of buprenorphine and cyclorphan with the ileum preparation, both compounds can be satisfactorily assayed in the mouse jumping test. The reported antagonistic properties of ketocyclazocine and profadol could not be confirmed in the mouse model.

Characterization of a Novel Small Molecule Subtype Specific Estrogen-Related Receptor α Antagonist in MCF-7 Breast Cancer Cells

PubMed Central

Chisamore, Michael J.; Cunningham, Michael E.; Flores, Osvaldo; Wilkinson, Hilary A.; Chen, J. Don

2009-01-01

Background The orphan nuclear receptor estrogen-related receptor α (ERRα) is a member of the nuclear receptor superfamily. It was identified through a search for genes encoding proteins related to estrogen receptor α (ERα). An endogenous ligand has not been found. Novel ERRα antagonists that are highly specific for binding to the ligand binding domain (LBD) of ERRα have been recently reported. Research suggests that ERRα may be a novel drug target to treat breast cancer and/or metabolic disorders and this has led to an effort to characterize the mechanisms of action of N-[(2Z)-3-(4,5-dihydro-1,3-thiazol-2-yl)-1,3-thiazolidin-2-yl idene]-5H dibenzo[a,d][7]annulen-5-amine, a novel ERRα specific antagonist. Methodology/Principal Findings We demonstrate this ERRα ligand inhibits ERRα transcriptional activity in MCF-7 cells by luciferase assay but does not affect mRNA levels measured by real-time RT-PCR. Also, ERα (ESR1) mRNA levels were not affected upon treatment with the ERRα antagonist, but other ERRα (ESRRA) target genes such as pS2 (TFF1), osteopontin (SPP1), and aromatase (CYP19A1) mRNA levels decreased. In vitro, the ERRα antagonist prevents the constitutive interaction between ERRα and nuclear receptor coactivators. Furthermore, we use Western blots to demonstrate ERRα protein degradation via the ubiquitin proteasome pathway is increased by the ERRα-subtype specific antagonist. We demonstrate by chromatin immunoprecipitation (ChIP) that the interaction between ACADM, ESRRA, and TFF1 endogenous gene promoters and ERRα protein is decreased when cells are treated with the ligand. Knocking-down ERRα (shRNA) led to similar genomic effects seen when MCF-7 cells were treated with our ERRα antagonist. Conclusions/Significance We report the mechanism of action of a novel ERRα specific antagonist that inhibits transcriptional activity of ERRα, disrupts the constitutive interaction between ERRα and nuclear coactivators, and induces proteasome-dependent ERRα protein degradation. Additionally, we confirmed that knocking-down ERRα lead to similar genomic effects demonstrated in vitro when treated with the ERRα specific antagonist. PMID:19462000

Similar Efficacy of Proton-Pump Inhibitors vs H2-Receptor Antagonists in Reducing Risk of Upper Gastrointestinal Bleeding or Ulcers in High-Risk Users of Low-Dose Aspirin.

PubMed

Chan, Francis K L; Kyaw, Moe; Tanigawa, Tetsuya; Higuchi, Kazuhide; Fujimoto, Kazuma; Cheong, Pui Kuan; Lee, Vivian; Kinoshita, Yoshikazu; Naito, Yuji; Watanabe, Toshio; Ching, Jessica Y L; Lam, Kelvin; Lo, Angeline; Chan, Heyson; Lui, Rashid; Tang, Raymond S Y; Sakata, Yasuhisa; Tse, Yee Kit; Takeuchi, Toshihisa; Handa, Osamu; Nebiki, Hiroko; Wu, Justin C Y; Abe, Takashi; Mishiro, Tsuyoshi; Ng, Siew C; Arakawa, Tetsuo

2017-01-01

It is not clear whether H 2 -receptor antagonists (H2RAs) reduce the risk of gastrointestinal (GI) bleeding in aspirin users at high risk. We performed a double-blind randomized trial to compare the effects of a proton pump inhibitor (PPI) vs a H2RA antagonist in preventing recurrent upper GI bleeding and ulcers in high-risk aspirin users. We studied 270 users of low-dose aspirin (≤325 mg/day) with a history of endoscopically confirmed ulcer bleeding at 8 sites in Hong Kong and Japan. After healing of ulcers, subjects with negative results from tests for Helicobacter pylori resumed aspirin (80 mg) daily and were assigned randomly to groups given a once-daily PPI (rabeprazole, 20 mg; n = 138) or H2RA (famotidine, 40 mg; n = 132) for up to 12 months. Subjects were evaluated every 2 months; endoscopy was repeated if they developed symptoms of upper GI bleeding or had a reduction in hemoglobin level greater than 2 g/dL and after 12 months of follow-up evaluation. The adequacy of upper GI protection was assessed by end points of recurrent upper GI bleeding and a composite of recurrent upper GI bleeding or recurrent endoscopic ulcers at month 12. During the 12-month study period, upper GI bleeding recurred in 1 patient receiving rabeprazole (0.7%; 95% confidence interval [CI], 0.1%-5.1%) and in 4 patients receiving famotidine (3.1%; 95% CI, 1.2%-8.1%) (P = .16). The composite end point of recurrent bleeding or endoscopic ulcers at month 12 was reached by 9 patients receiving rabeprazole (7.9%; 95% CI, 4.2%-14.7%) and 13 patients receiving famotidine (12.4%; 95% CI, 7.4%-20.4%) (P = .26). In a randomized controlled trial of users of low-dose aspirin at risk for recurrent GI bleeding, a slightly lower proportion of patients receiving a PPI along with aspirin developed recurrent bleeding or ulcer than of patients receiving an H2RA with the aspirin, although this difference was not statistically significant. ClincialTrials.gov no: NCT01408186. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

Antagonistic potential against pathogenic microorganisms and hydrogen peroxide production of indigenous lactobacilli isolated from vagina of Chinese pregnant women.

PubMed

Xu, Heng-Yi; Tian, Wan-Hong; Wan, Cui-Xiang; Jia, Li-Jun; Wang, Lan-Yin; Yuan, Jing; Liu, Chun-Mei; Zeng, Ming; Wei, Hua

2008-10-01

To investigate the indigenous lactobacilli from the vagina of pregnant women and to screen the isolates with antagonistic potential against pathogenic microorganisms. The strains were isolated from pregnant women's vagina and identified using the API50CH system. The ability of the isolates to produce hydrogen peroxide was analyzed semi-quantitatively using the TMB-HRP-MRS agar. The antagonistic effects of the isolates on pathogenic microorganisms were determined with a double layer agar plate. One hundred and three lactobacilli strains were isolated from 60 samples of vaginal secretion from healthy pregnant women. Among them, 78 strains could produce hydrogen peroxide, in which 68%, 80%, 80%, and 88% had antagonistic effects against Candida albicans CMCC98001, Staphylococcus aureus CMCC26003, Escherichia coli CMCC44113, and Pseudomonas aeruginosa CMCC10110, respectively. The recovery of hydrogen peroxide-producing lactobacilli decreases with the increasing pregnant age and time. The most commonly isolated species from vagina of Chinese pregnant women are Lactobacillus acidophilus and Lactobacillus crispatus. Most of L. acidophilus and L. crispatus produce a high H2O2 level.

SSR126768A (4-chloro-3-[(3R)-(+)-5-chloro-1-(2,4-dimethoxybenzyl)-3-methyl-2-oxo-2,3-dihydro-1H-indol-3-yl]-N-ethyl-N-(3-pyridylmethyl)-benzamide, hydrochloride): a new selective and orally active oxytocin receptor antagonist for the prevention of preterm labor.

PubMed

Serradeil-Le Gal, Claudine; Valette, Gérard; Foulon, Loïc; Germain, Guy; Advenier, Charles; Naline, Emmanuel; Bardou, Marc; Martinolle, Jean-Pierre; Pouzet, Brigitte; Raufaste, Danielle; Garcia, Corinne; Double-Cazanave, Eléonore; Pauly, Maxime; Pascal, Marc; Barbier, Alain; Scatton, Bernard; Maffrand, Jean-Pierre; Le Fur, Gérard

2004-04-01

4-chloro-3-[(3R)-(+)-5-chloro-1-(2,4-dimethoxybenzyl)-3-methyl-2-oxo-2,3-dihydro-1H-indol-3-yl]-N-ethyl-N-(3-pyridylmethyl)benzamide, hydrochloride (SSR126768A), a new potent and selective, orally active oxytocin (OT) receptor antagonist was characterized in several biochemical and pharmacological models. In binding studies, SSR126768A showed nanomolar affinity for rat and human recombinant and native OT receptors (K(i) = 0.44 nM) and exhibited much lower affinity for V(1a), V(1b), and V(2) receptors. In addition, it did not interact with a large number of other receptors, enzymes, and ion channels (1 microM). In autoradiographic experiments performed on at-term human pregnant uterus sections, SSR126768A dose dependently displaced [I(125)]d(CH(2))(5)[Tyr(Me)(2), Thr(4), Orn(8) (125)I-Tyr-NH(2)(9)]VT in situ labeling to OT receptors highly expressed in these tissues. In functional studies, SSR126768A behaved as a full antagonist and potently antagonized OT-induced intracellular Ca(2+) increase (K(i) = 0.50 nM) and prostaglandin release (K(i) = 0.45 nM) in human uterine smooth muscle cells. In rat isolated myometrium, OT-induced uterine contractions were competitively antagonized by SSR126768A (pA(2) = 8.47). Similarly, in human pregnant myometrial strips, SSR126768A inhibited the contractile uterine response to OT. In conscious telemetrated rats, oral administration of SSR126768A (1-10 mg/kg) produced a competitive inhibition of the dose response to OT on uterine contractions up to 24 h at 3 mg/kg p.o.; no tachyphylaxis was observed after 4-day repeated treatment. Finally, SSR126768A (30 mg/kg p.o.) significantly delayed parturition in pregnant rats in labor similar to ritodrine (10 mg/kg p.o.). Thus, SSR126768A is a potent, highly selective, orally active OT receptor antagonist with a long duration of action. This molecule could find therapeutic application as a tocolytic agent for acute and chronic oral management of preterm labor.

Selective Activation of Cannabinoid CB2 Receptors Suppresses Neuropathic Nociception Induced by Treatment with the Chemotherapeutic Agent Paclitaxel in Rats

PubMed Central

Rahn, Elizabeth J.; Zvonok, Alexander M.; Thakur, Ganesh A.; Khanolkar, Atmaram D.; Makriyannis, Alexandros; Hohmann, Andrea G.

2009-01-01

Activation of cannabinoid CB2 receptors suppresses neuropathic pain induced by traumatic nerve injury. The present studies were conducted to evaluate the efficacy of cannabinoid CB2 receptor activation in suppressing painful peripheral neuropathy evoked by chemotherapeutic treatment with the anti-tumor agent paclitaxel. Rats received paclitaxel (2 mg/kg i.p. per day) on four alternate days to induce mechanical hypersensitivity (mechanical allodynia). Mechanical allodynia was defined as a lowering of the threshold for paw withdrawal to stimulation of the plantar hind paw surface with an electronic von Frey stimulator. Mechanical allodynia developed in paclitaxel-treated animals relative to groups receiving the cremophor: ethanol: saline vehicle at the same times. Two structurally distinct cannabinoid CB2 agonists—the aminoalkylindole (R,S)-AM1241 ((R,S)-(2-iodo-5-nitrophenyl)-[1-((1-methyl-piperidin-2-yl)methyl)-1H-indol-3-yl]-methanone) and the cannabilactone AM1714 (1,9-dihydroxy-3-(1′,1′-dimethylheptyl)-6H-benzo[c]chromene-6-one)—produced a dose-related suppression of established paclitaxel-evoked mechanical allodynia following systemic administration. Pretreatment with the CB2 antagonist SR144528 (5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-N-(1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl)-1H-pyrazole-3-carboxamide), but not the CB1 antagonist SR141716 (5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide), blocked the anti-allodynic effects of both (R,S)-AM1241 and AM1714. Moreover, (R)-AM1241, but not (S)-AM1241, suppressed paclitaxel-evoked mechanical allodynia relative to either vehicle treatment or pre-injection thresholds, consistent with mediation by CB2. Administration of either the CB1 or CB2 antagonist alone failed to alter paclitaxel-evoked mechanical allodynia. Moreover, (R,S)-AM1241 did not alter paw withdrawal thresholds in rats that received the cremophor vehicle in lieu of paclitaxel whereas AM1714 induced a modest antinociceptive effect. Our data suggest that cannabinoid CB2 receptors may be important therapeutic targets for the treatment of chemotherapy-evoked neuropathy. PMID:18664590

Selective activation of cannabinoid CB2 receptors suppresses neuropathic nociception induced by treatment with the chemotherapeutic agent paclitaxel in rats.

PubMed

Rahn, Elizabeth J; Zvonok, Alexander M; Thakur, Ganesh A; Khanolkar, Atmaram D; Makriyannis, Alexandros; Hohmann, Andrea G

2008-11-01

Activation of cannabinoid CB(2) receptors suppresses neuropathic pain induced by traumatic nerve injury. The present studies were conducted to evaluate the efficacy of cannabinoid CB(2) receptor activation in suppressing painful peripheral neuropathy evoked by chemotherapeutic treatment with the antitumor agent paclitaxel. Rats received paclitaxel (2 mg/kg i.p./day) on 4 alternate days to induce mechanical hypersensitivity (mechanical allodynia). Mechanical allodynia was defined as a lowering of the threshold for paw withdrawal to stimulation of the plantar hind paw surface with an electronic von Frey stimulator. Mechanical allodynia developed in paclitaxel-treated animals relative to groups receiving the Cremophor EL/ethanol/saline vehicle at the same times. Two structurally distinct cannabinoid CB(2) agonists, the aminoalkylindole (R,S)-AM1241 [(R,S)-(2-iodo-5-nitrophenyl)-[1-((1-methyl-piperidin-2-yl)methyl)-1H-indol-3-yl]-methanone] and the cannabilactone AM1714 (1,9-dihydroxy-3-(1',1'-dimethylheptyl)-6H-benzo[c]chromene-6-one), produced a dose-related suppression of established paclitaxel-evoked mechanical allodynia after systemic administration. Pretreatment with the CB(2) antagonist SR144528 [5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-N-(1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl)-1H-pyrazole-3-carboxamide], but not the CB(1) antagonist SR141716 [5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide], blocked the antiallodynic effects of both (R,S)-AM1241 and AM1714. Moreover, (R)-AM1241, but not (S)-AM1241, suppressed paclitaxel-evoked mechanical allodynia relative to either vehicle treatment or preinjection thresholds, consistent with mediation by CB(2). Administration of either the CB(1) or CB(2) antagonist alone failed to alter paclitaxel-evoked mechanical allodynia. Moreover, (R,S)-AM1241 did not alter paw withdrawal thresholds in rats that received the Cremophor EL vehicle in lieu of paclitaxel, whereas AM1714 induced a modest antinociceptive effect. Our data suggest that cannabinoid CB(2) receptors may be important therapeutic targets for the treatment of chemotherapy-evoked neuropathy.

Discovery of Natural Products as Novel and Potent FXR Antagonists by Virtual Screening

NASA Astrophysics Data System (ADS)

Diao, Yanyan; Jiang, Jing; Zhang, Shoude; Li, Shiliang; Shan, Lei; Huang, Jin; Zhang, Weidong; Li, Honglin

2018-04-01

Farnesoid X receptor (FXR) is a member of nuclear receptor family involved in multiple physiological processes through regulating specific target genes. The critical role of FXR as a transcriptional regulator makes it a promising target for diverse diseases, especially those related to metabolic disorders such as diabetes and cholestasis. However, the underlying activation mechanism of FXR is still a blur owing to the absence of proper FXR modulators. To identify potential FXR modulators, an in-house natural product database (NPD) containing over 4000 compounds was screened by structure-based virtual screening strategy and subsequent hit-based similarity searching method. After the yeast two-hybrid (Y2H) assay, six natural products were identified as FXR antagonists which blocked the CDCA-induced SRC-1 association. The IC50 values of compounds 2a, a diterpene bearing polycyclic skeleton, and 3a, named daphneone with chain scaffold, are as low as 1.29 μM and 1.79 μM, respectively. Compared to the control compound guggulsterone (IC50 = 6.47 μM), compounds 2a and 3a displayed 5-fold and 3-fold higher antagonistic activities against FXR, respectively. Remarkably, the two representative compounds shared low topological similarities with other reported FXR antagonists. According to the putative binding poses, the molecular basis of these antagonists against FXR was also elucidated in this report.

Isolation and identification of a novel bacterium, Lactobacillus sakei subsp. dgh strain 5, and optimization of growth condition for highest antagonistic activity.

PubMed

Tashakor, Amin; Hosseinzadehdehkordi, Mahshid; Emruzi, Zeynab; Gholami, Dariush

2017-05-01

In the present study, we isolated Lactobacillus sakei strain DGH5 from raw beef meat. This bacterium plays an inhibitory effect against food-spoiling bacteria and food-borne pathogens, including Listeria monocytogenes, a gram-positive and pathogenic bacterium. Lactobacillus sakei strain DGH5 was identified through both phenotypical and biochemical tests accompanied with 16S rRNA sequence analysis. Among all the sources of carbon, nitrogen and phosphorous forms, we selected the most potent compounds to optimize the condition for the highest antagonistic activity. Among the sugars, polygalacturonic acid demonstrated to improve the antagonistic activity. Ammonium nitrate demonstrated to be suitable nitrogen sources. Amongst phosphorous sources, disodium hydrogen phosphate had the greatest antagonistic effect. According to Taguchi's orthogonal array, temperature, disodium hydrogen phosphate and soy Peptone had significant effect on antagonistic activity. Furthermore, mean comparisons showed that the optimum conditions achieved at pH 6.0, 25 °C temperature, 1.5% (w/v) Na 2 HPO 4 and 0.5% (w/v) peptone. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantitative autoradiographic analysis of muscarinic receptor subtypes and their role in representational memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Messer, W.S.

1986-01-01

Autoradiographic techniques were used to examine the distribution of muscarinic receptors in rat brain slices. Agonist and selective antagonist binding were examined by measuring the ability for unlabeled ligands to inhibit (/sup 3/H)-1-QNB labeling of muscarinic receptors. The distribution of high affinity pirenzepine binding sites (M/sub 1/ subtype) was distinct from the distribution of high affinity carbamylcholine sites, which corresponded to the M/sub 2/ subtype. In a separate assay, the binding profile for pirenzepine was shown to differ from the profile for scopolamine, a classical muscarinic antagonist. Muscarinic antagonists, when injected into the Hippocampus, impaired performance of a representational memorymore » task. Pirenzepine, the M/sub 1/ selective antagonist, produced representational memory deficits. Scopolamine, a less selective muscarinic antagonist, caused increases in running times in some animals which prevented a definitive interpretation of the nature of the impairment. Pirenzepine displayed a higher affinity for the hippocampus and was more effective in producing a selective impairment of representational memory than scopolamine. The data indicated that cholinergic activity in the hippocampus was necessary for representation memory function.« less

[Analgesic effects of ionotropic glutamate receptor antagonists MK-801 and NBQX on collagen-induced arthritis rats].

PubMed

Zhu, H; Zhu, R; Deng, Z D; Feng, Y C; Shen, H L

2016-12-18

The ionotropic glutamate receptorantagonists include two types: MK-801, antagonist of N-methyl-D-asparticacid (NMDA) receptor, and NBQX, antagonist of non-NMDA receptor.The above-mentioned ionotropic antagonists can block the glutamate and its corresponding receptor binding to produce analgesic effect. The objective of this research was to study two antagonists in analgesic effect on rat behavior,as well as to investigate the down-regulation and up-regulation of cyclooxygenase-2 (COX-2) and Janus-activated kinase (Jak3) in collagen-induced arthritis (CIA) rat serum and tissue fluid after the application of these antagonists, that is, the effect on molecular biology. This study used the ionotropic glutamate receptors as the target and established CIA rat model. Vivo studies were used to observe changes in behavior and molecular biology of the CIA rat.Behavioral assessment includedmechanical allodynia and joint swelling in the CIA rat,where themechanical allodynia was measured using the paw-withdrawal threshold (PWT) with VonFrey filaments according to the "Up-Down" method,and the drainage volume was used to assess joint swelling. Then the blood samples taken from the heart of the rat and the tissue homogenate were collected to detect the down-regulation and up-regulation of COX-2 and Jak3 in the serum and tissue fluid after the antagonists wereused. Using MK-801, NBQX alone or using the combination of these two antagonists,these three methods all could alleviate pain(P<0.01).The analgesic effect lasted more than 24 h.Both antagonists reached the peak of analgesia at the end of 4 hours post-injection. NBQX had stronger analgesic effect than MK-801 (P<0.05).Whether alone or combined use of these two antagonists,could not change the CIA rats' swelling of the joint (P>0.05). MK-801 could decrease the expression of COX-2 (P<0.01).At the same time, NBQX did not have this effect (P>0.05). Using MK-801, NBQX alone or combination of these two antagonists could not affect the increased expression of Jak3 caused by the CIA (P>0.05). MK-801 and NBQX could both alleviate pain, NBQX was much better than MK-801. Neither MK-801 nor NBQX had the effect on the swelling of the joint. NMDA receptor and COX-2 inflammatory pathways had certain interactions. For Jak3, it could not be found to have cross-function with ionotropic glutamate signaling pathways by this experiment.

Effect of a kinin B2 receptor antagonist on LPS- and cytokine-induced neutrophil migration in rats

PubMed Central

Santos, Danielle R; Calixto, João B; Souza, Glória E P

2003-01-01

This study examines the involvement of kinins in neutrophil migration into rat subcutaneous air pouches triggered by lipopolysaccharide (LPS), as well as the putative roles played by kinin B1 and B2 receptors, tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and selectins in this response. LPS (5 ng to 10 μg cavity−1) injected into the 6-day-old pouch induced a dose- and time-dependent neutrophil migration which peaked between 4 and 6 h, and was maximal following the dose of 100 ng cavity−1 (saline: 0.46±0.1; LPS: 43±3.70 × 106 cells cavity−1 at 6 h). Bradykinin (BK) (600 nmol) injected into the pouch of saline-treated rats induced only modest neutrophil migration (0.73±0.16 × 106 cells cavity−1). A more robust response to BK (3.2±0.25 × 106 cells cavity−1) was seen in animals pretreated with captopril, but this was still smaller than the responses to IL-1β or TNF-α (15 pmol: 23±2.2 × 106 and 75 pmol: 29.5±2 × 106 cells cavity−1, respectively). Nevertheless, the B1 agonist des-Arg9-BK (600 nmol) failed to induce neutrophil migration. HOE-140 (1 and 2 mg kg−1), a B2 receptor antagonist, reduced LPS-induced neutrophil migration. HOE-140 also reduced the neutrophil migration induced by BK, but had no effect on the migration promoted by IL-1β or TNF-α. des-Arg9-[Leu8]-BK, B1 receptor antagonist was ineffective in changing neutrophil migration caused by any of these stimuli. Neutrophil migration induced by LPS or BK was reduced by interleukin-1 receptor antagonist (IL-1ra) (1 mg kg−1), sheep anti-rat TNF serum (anti-TNF serum) (0.3 ml cavity−1), and the nonspecific selectin inhibitor fucoidin (10 mg kg−1). TNF-α levels in the pouch fluid were increased by LPS or BK injection, peaking at 0.5–1 h and gradually declining thereafter up to 6 h. IL-1β levels increased steadily throughout the 6 h period. HOE-140 markedly inhibited the rise in IL-1β and TNF-α levels in pouch fluid triggered by both stimuli. These results indicate that BK participates importantly in selectin-dependent neutrophil migration into the air pouch triggered by LPS in the rat, by stimulating B2 receptors coupled to synthesis/release of TNF-α and IL-1β. PMID:12770932

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

Isolation and characterization of antagonistic fungi against potato scab pathogens from potato field soils.

PubMed

Tagawa, Masahiro; Tamaki, Hideyuki; Manome, Akira; Koyama, Osamu; Kamagata, Yoichi

2010-04-01

Potato scab is a serious plant disease caused by several Streptomyces sp., and effective control methods remain unavailable. Although antagonistic bacteria and phages against potato scab pathogens have been reported, to the best of our knowledge, there is no information about fungi that are antagonistic to the pathogens. The aim of this study was to isolate fungal antagonists, characterize their phylogenetic positions, determine their antagonistic activities against potato scab pathogens, and highlight their potential use as control agents under lower pH conditions. Fifteen fungal stains isolated from potato field soils were found to have antagonistic activity against three well-known potato scab pathogens: Streptomyces scabiei, Streptomyces acidiscabiei, and Streptomyces turgidiscabiei. These 15 fungal strains were phylogenetically classified into at least six orders and nine genera based on 18S rRNA gene sequencing analysis. These fungal isolates were related to members of the genera Penicillium, Eupenicillium, Chaetomium, Fusarium, Cladosporium, Mortierella, Kionochaeta, Pseudogymnoascus, and Lecythophora. The antagonistic activities of most of the fungal isolates were highly strengthened under the lower pH conditions, suggesting the advantage of combining their use with a traditional method such as soil acidification. This is the first report to demonstrate that phylogenetically diverse fungi show antagonistic activity against major potato scab pathogens. These fungal strains could be used as potential agents to control potato scab disease.

5-HT6 receptor agonists and antagonists enhance learning and memory in a conditioned emotion response paradigm by modulation of cholinergic and glutamatergic mechanisms

PubMed Central

Woods, S; Clarke, NN; Layfield, R; Fone, KCF

2012-01-01

BACKGROUND AND PURPOSE 5-HT6 receptors are abundant in the hippocampus, nucleus accumbens and striatum, supporting their role in learning and memory. Selective 5-HT6 receptor antagonists produce pro-cognitive effects in several learning and memory paradigms while 5-HT6 receptor agonists have been found to enhance and impair memory. EXPERIMENTAL APPROACH The conditioned emotion response (CER) paradigm was validated in rats. Then we examined the effect of the 5-HT6 receptor antagonist, EMD 386088 (10 mg·kg−1, i.p.), and agonists, E-6801 (2.5 mg·kg−1, i.p.) and EMD 386088 (5 mg·kg−1, i.p.) on CER-induced behaviour either alone or after induction of memory impairment by the muscarinic receptor antagonist, scopolamine (0.3 mg·kg−1, i.p) or the NMDA receptor antagonist, MK-801 (0.1 mg·kg−1, i.p). KEY RESULTS Pairing unavoidable foot shocks with a light and tone cue during CER training induced a robust freezing response, providing a quantitative index of contextual memory when the rat was returned to the shock chamber 24 h later. Pretreatment (−20 min pre-training) with scopolamine or MK-801 reduced contextual freezing 24 h after CER training, showing production of memory impairment. Immediate post-training administration of 5-HT6 receptor antagonist, SB-270146, and agonists, EMD 386088 and E-6801, had little effect on CER freezing when given alone, but all significantly reversed scopolamine- and MK-801-induced reduction in freezing. CONCLUSION AND IMPLICATIONS Both the 5-HT6 receptor agonists and antagonist reversed cholinergic- and glutamatergic-induced deficits in associative learning. These findings support the therapeutic potential of 5-HT6 receptor compounds in the treatment of cognitive dysfunction, such as seen in Alzheimer's disease and schizophrenia. PMID:22568655

Comparative Analysis of Virtual Screening Approaches in the Search for Novel EphA2 Receptor Antagonists.

PubMed

Callegari, Donatella; Pala, Daniele; Scalvini, Laura; Tognolini, Massimiliano; Incerti, Matteo; Rivara, Silvia; Mor, Marco; Lodola, Alessio

2015-09-17

The EphA2 receptor and its ephrin-A1 ligand form a key cell communication system, which has been found overexpressed in many cancer types and involved in tumor growth. Recent medicinal chemistry efforts have identified bile acid derivatives as low micromolar binders of the EphA2 receptor. However, these compounds suffer from poor physicochemical properties, hampering their use in vivo. The identification of compounds able to disrupt the EphA2-ephrin-A1 complex lacking the bile acid scaffold may lead to new pharmacological tools suitable for in vivo studies. To identify the most promising virtual screening (VS) protocol aimed at finding novel EphA2 antagonists, we investigated the ability of both ligand-based and structure-based approaches to retrieve known EphA2 antagonists from libraries of decoys with similar molecular properties. While ligand-based VSs were conducted using UniPR129 and ephrin-A1 ligand as reference structures, structure-based VSs were performed with Glide, using the X-ray structure of the EphA2 receptor/ephrin-A1 complex. A comparison of enrichment factors showed that ligand-based approaches outperformed the structure-based ones, suggesting ligand-based methods using the G-H loop of ephrin-A1 ligand as template as the most promising protocols to search for novel EphA2 antagonists.

Structural Diversity of Ligand-Binding Androgen Receptors Revealed by Microsecond Long Molecular Dynamics Simulations and Enhanced Sampling.

PubMed

Duan, Mojie; Liu, Na; Zhou, Wenfang; Li, Dan; Yang, Minghui; Hou, Tingjun

2016-09-13

Androgen receptor (AR) plays important roles in the development of prostate cancer (PCa). The antagonistic drugs, which suppress the activity of AR, are widely used in the treatment of PCa. However, the molecular mechanism of antagonism about how ligands affect the structures of AR remains elusive. To better understand the conformational variability of ARs bound with agonists or antagonists, we performed long time unbiased molecular dynamics (MD) simulations and enhanced sampling simulations for the ligand binding domain of AR (AR-LBD) in complex with various ligands. Based on the simulation results, we proposed an allosteric pathway linking ligands and helix 12 (H12) of AR-LBD, which involves the interactions among the ligands and the residues W741, H874, and I899. The interaction pathway provides an atomistic explanation of how ligands affect the structure of AR-LBD. A repositioning of H12 was observed, but it is facilitated by the C-terminal of H12, instead of by the loop between helix 11 (H11) and H12. The bias-exchange metadynamics simulations further demonstrated the above observations. More importantly, the free energy profiles constructed by the enhanced sampling simulations revealed the transition process between the antagonistic form and agonistic form of AR-LBD. Our results would be helpful for the design of more efficient antagonists of AR to combat PCa.

Pellitorine, an extract of Tetradium daniellii, is an antagonist of the ion channel TRPV1.

PubMed

Oláh, Zoltán; Rédei, Dóra; Pecze, László; Vizler, Csaba; Jósvay, Katalin; Forgó, Péter; Winter, Zoltán; Dombi, György; Szakonyi, Gerda; Hohmann, Judit

2017-10-15

Transient Receptor Potential Vanilloid 1 (TRPV1) confers noxious heat and inflammatory pain signals in the peripheral nervous system. Clinical trial of resiniferatoxin from Euphorbia species is successfully aimed at TRPV1 in cancer pain management and heading toward new selective painkiller status that further validates this target for drug discovery efforts. Evodia species, used in traditional medicine for hundreds of years, are a recognised source of different TRPV1 agonists, but no antagonist has yet been reported. In a search for painkiller leads, we noted for the first time a TRPV1 antagonist activity in the fresh fruits of Tetradium daniellii (Benn.) T.G. Hartley (syn. Evodia hupehensis Dode). Through a combination of extraction and purification methods with functional TRPV1-specific Ca 2+ uptake assays (bioactivity-guided fractionation/isolation/purification); we isolated a new painkiller candidate that is a distant structural homologue of capsiate exovanilloids and endovanilloids such as anandamide, but a putative competitive inhibitor of the TRPV1. Four additional inactive compounds (N-isobutyl-4,5-epoxy-2E-decadienamide, geranylpsoralen, 8-(7',8'-epoxygeranyloxy)psoralen, and xanthotoxol) were also co-purified with pellitorine. Their structures were established by extensive 1D- and 2D-NMR spectroscopic analysis. 1 H- and 13 C NMR determination of the chemical structure revealed it to be pellitorine, (2E,4E)-N-(2-methylpropyl)deca-2,4-dienamide, which can compete structurally with algesics released in inflammation. In contrast to previous isolates from Evodia species, pellitorine blocked capsaicin-evoked Ca 2+ uptake with an IC 50 of 154 µg/ml (0.69 mM/l). N-Isobutyl-4,5-epoxy-2E-decadienamide and geranylpsoralen, 8-(7',8'-epoxygeranyloxy)psoralen, and xanthotoxol did not affect the TRPV1. This is the first evidence that pellitorine, an aliphatic alkylamide analogue of capsaicin, can serve as an antagonist of the TRPV1 and may inhibit exovanilloid-induced pain. Copyright © 2017 Elsevier GmbH. All rights reserved.

Identification of putative agouti-related protein(87-132)-melanocortin-4 receptor interactions by homology molecular modeling and validation using chimeric peptide ligands.

PubMed

Wilczynski, Andrzej; Wang, Xiang S; Joseph, Christine G; Xiang, Zhimin; Bauzo, Rayna M; Scott, Joseph W; Sorensen, Nicholas B; Shaw, Amanda M; Millard, William J; Richards, Nigel G; Haskell-Luevano, Carrie

2004-04-22

Agouti-related protein (AGRP) is one of only two naturally known antagonists of G-protein-coupled receptors (GPCRs) identified to date. Specifically, AGRP antagonizes the brain melanocortin-3 and -4 receptors involved in energy homeostasis. Alpha-melanocyte stimulating hormone (alpha-MSH) is one of the known endogenous agonists for these melanocortin receptors. Insight into putative interactions between the antagonist AGRP amino acids with the melanocortin-4 receptor (MC4R) may be important for the design of unique ligands for the treatment of obesity related diseases and is currently lacking in the literature. A three-dimensional homology molecular model of the mouse MC4 receptor complex with the hAGRP(87-132) ligand docked into the receptor has been developed to identify putative antagonist ligand-receptor interactions. Key putative AGRP-MC4R interactions include the Arg111 of hAGRP(87-132) interacting in a negatively charged pocket located in a cavity formed by transmembrane spanning (TM) helices 1, 2, 3, and 7, capped by the acidic first extracellular loop (EL1) and specifically with the conserved melanocortin receptor residues mMC4R Glu92 (TM2), mMC4R Asp114 (TM3), and mMC4R Asp118 (TM3). Additionally, Phe112 and Phe113 of hAGRP(87-132) putatively interact with an aromatic hydrophobic pocket formed by the mMC4 receptor residues Phe176 (TM4), Phe193 (TM5), Phe253 (TM6), and Phe254 (TM6). To validate the AGRP-mMC4R model complex presented herein from a ligand perspective, we generated nine chimeric peptide ligands based on a modified antagonist template of the hAGRP(109-118) (Tyr-c[Asp-Arg-Phe-Phe-Asn-Ala-Phe-Dpr]-Tyr-NH(2)). In these chimeric ligands, the antagonist AGRP Arg-Phe-Phe residues were replaced by the melanocortin agonist His/D-Phe-Arg-Trp amino acids. These peptides resulted in agonist activity at the mouse melanocortin receptors (mMC1R and mMC3-5Rs). The most notable results include the identification of a novel subnanomolar melanocortin peptide template Tyr-c[Asp-His-DPhe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) that is equipotent to alpha-MSH at the mMC1, mMC3, and mMC5 receptors but is 30-fold more potent than alpha-MSH at the mMC4R. Additionally, these studies identified a new and novel >200-fold MC4R versus MC3R selective peptide Tyr-c[Asp-D-Phe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) template. Furthermore, when the His-DPhe-Arg-Trp sequence is used to replace the hAGRP Arg-Phe-Phe residues in the "mini"-AGRP (hAGRP87-120, C105A) template, a potent nanomolar agonist resulted at the mMC1R and MC3-5Rs.

Effects of 5-HT5A receptor blockade on amnesia or forgetting.

PubMed

Aparicio-Nava, L; Márquez-García, L A; Meneses, A

2018-01-09

Previously the effects (0.01-3.0 mg/kg) of post-training SB-699551 (a 5-HT 5A receptor antagonist) were reported in the associative learning task of autoshaping, showing that SB-699551 (0.1 mg/kg) decreased lever-press conditioned responses (CR) during short-term (STM; 1.5-h) or (3.0 mg/kg) long-term memory (LTM; 24-h); relative to the vehicle animals. Moreover, as pro-cognitive efficacy of SB-699551 was reported in the ketamine-model of schizophrenia. Hence, firstly aiming improving performance (conditioned response, CR), in this work autoshaping lever-press vs. nose-poke response was compared; secondly, new set of animals were randomly assigned to SB-699551 plus forgetting or amnesia protocols. Results show that the nose-poke operandum reduced inter-individual variance, increased CR and produced a progressive CR until 48-h. After one week of no training/testing sessions (i.e., interruption of 216 h), the forgetting was observed; i.e., the CR% of control-saline group significantly decreased. In contrast, SB-699551 at 0.3 and 3.0 mg/kg prevents forgetting. Additionally, as previously reported the non-competitive NMDA receptor antagonist dizocilpine (0.2 mg/kg) or the non-selective cholinergic antagonist scopolamine (0.3 mg/kg) decreased CR in STM. SB-699551 (0.3 mg/kg) alone also produced amnesia-like effect. Co-administration of SB-699551-dizocilpine or SB-699551-scopolamine reversed the SB-699551 induced-amnesic effects in LTM (24-h). Nose-poke seems to be a reliable operandum. The anti-amnesic and anti-forgetting mechanisms of amnesic SB-699551-dose remain unclear. The present findings are consistent with the notion that low doses of 5-HT 5A receptor antagonists might be useful for reversing memory deficits associated to forgetting and amnesia. Of course, further experiments are necessary. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of the adenosine receptor in cultured embryonic chick atrial myocytes: Coupling to modulation of contractility and adenylate cyclase activity and identification by direct radioligand binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, B.T.

1989-06-01

Adenosine receptors in a spontaneously contracting atrial myocyte culture from 14-day chick embryos were characterized by radioligand binding studies and by examining the involvement of G-protein in coupling these receptors to a high-affinity state and to the adenylate cyclase and the myocyte contractility. Binding of the antagonist radioligand (3H)-8-cyclopentyl-1,3-diproylxanthine ((3H)CPX) was rapid, reversible and saturable and was to a homogeneous population of sites with a Kd value of 2.1 +/- 0.2 nM and an apparent maximum binding of 26.2 +/- 3 fmol/mg of protein (n = 10, +/- S.E.). Guanyl-5-yl-(beta, gamma-imido)diphosphate had no effect on either the Kd or themore » maximum binding and CPX reversed the N6-R-phenyl-2-propyladenosine-induced inhibition of adenylate cyclase activity and contractility, indicating that (3H) CPX is an antagonist radioligand. Competition curves for (3H) CPX binding by a series of reference adenosine agonists were consistent with labeling of an A1 adenosine receptor and were better fit by a two-site model than by a one-site model. ADP-ribosylation of the G-protein by the endogenous NAD+ in the presence of pertussis toxin shifted the competition curves from bi to monophasic with Ki values similar to those of the KL observed in the absence of prior pertussis intoxication. The adenosine agonists were capable of inhibiting both the adenylate cyclase activity and myocyte contractility in either the absence or the presence of isoproterenol. The A1 adenosine receptor-selective antagonist CPX reversed these agonist effects. The order of ability of the reference adenosine receptor agonists in causing these inhibitory effects was similar to the order of potency of the same agonists in inhibiting the specific (3H)CPX binding (N6-R-phenyl-2-propyladenosine greater than N6-S-phenyl-2-propyladenosine or N-ethyladenosine-5'-uronic acid).« less

Efficacy and safety of herbal medicines in treating gastric ulcer: a review.

PubMed

Bi, Wei-Ping; Man, Hui-Bin; Man, Mao-Qiang

2014-12-07

Gastric ulcer is a common disorder of the digestive system. Current therapeutic regimens largely rely on Western medicine. However, numerous studies have demonstrated that herbal medicines can effectively treat gastric ulcer in humans and various animal models via divergent mechanisms. This review updates the efficacy and safety of herbal medicines in treating gastric ulcer, and the mechanisms of their action in humans and animal models. Studies have demonstrated that the efficacy of herbal medicines is comparable or superior to that of drugs such as omeprazole or cimetidine in humans and animal models, and herbal medicines display fewer adverse effects. The mechanisms by which herbal medicines benefit gastric ulcer include stimulation of mucous cell proliferation, anti-oxidation, and inhibition of gastric acid secretion and H(+)/K(+)-ATPase activity. Some herbal medicines also exhibit antimicrobial properties. Utilization of herbal medicines could be a valuable alternative to treat gastric ulcer in humans effectively, with few adverse effects.

Decreased agonist sensitivity of human GABA(A) receptors by an amino acid variant, isoleucine to valine, in the alpha1 subunit.

PubMed

Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nabekura, J; Noguchi, K; Akaike, N; Witt, M R; Nielsen, M

1997-06-25

Recombinant human GABA(A) receptors were investigated in vitro by coexpression of cDNAs coding for alpha1, beta2, and gamma2 subunits in the baculovirus/Sf-9 insect cell system. We report that a single amino acid exchange (isoleucine 121 to valine 121) in the N-terminal, extracellular part of the alpha1 subunit induces a marked decrease in agonist GABA(A) receptor ligand sensitivity. The potency of muscimol and GABA to inhibit the binding of the GABA(A) receptor antagonist [3H]SR 95531 (2-(3-carboxypropyl)-3-amino-6-(4-methoxyphenyl)pyridazinium bromide) was higher in receptor complexes of alpha1(ile 121) beta2gamma2 than in those of alpha1(val 121) beta2gamma2 (IC50 values were 32-fold and 26-fold lower for muscimol and GABA, respectively). The apparent affinity of the GABA(A) receptor antagonist bicuculline methiodide to inhibit the binding of [3H]SR 95531 did not differ between the two receptor complex variants. Electrophysiological measurements of GABA induced whole-cell Cl- currents showed a ten-fold decrease in the GABA(A) receptor sensitivity of alpha1 (val 121) beta2gamma2 as compared to alpha1(ile 121) beta2gamma2 receptor complexes. Thus, a relatively small change in the primary structure of the alpha1 subunit leads to a decrease selective for GABA(A) receptor sensitivity to agonist ligands, since no changes were observed in a GABA(A) receptor antagonist affinity and benzodiazepine receptor binding.

The Cannabinoids Δ8THC, CBD, and HU-308 Act via Distinct Receptors to Reduce Corneal Pain and Inflammation

PubMed Central

Thapa, Dinesh; Cairns, Elizabeth A.; Szczesniak, Anna-Maria; Toguri, James T.; Caldwell, Meggie D.; Kelly, Melanie E. M.

2018-01-01

Abstract Background and Purpose: Corneal injury can result in dysfunction of corneal nociceptive signaling and corneal sensitization. Activation of the endocannabinoid system has been reported to be analgesic and anti-inflammatory. The purpose of this research was to investigate the antinociceptive and anti-inflammatory effects of cannabinoids with reported actions at cannabinoid 1 (CB1R) and cannabinoid 2 (CB2R) receptors and/or noncannabinoid receptors in an experimental model of corneal hyperalgesia. Methods: Corneal hyperalgesia (increased pain response) was generated using chemical cauterization of the corneal epithelium in wild-type (WT) and CB2R knockout (CB2R−/−) mice. Cauterized eyes were treated topically with the phytocannabinoids Δ8-tetrahydrocannabinol (Δ8THC) or cannabidiol (CBD), or the CBD derivative HU-308, in the presence or absence of the CB1R antagonist AM251 (2.0 mg/kg i.p.), or the 5-HT1A receptor antagonist WAY100635 (1 mg/kg i.p.). Behavioral pain responses to a topical capsaicin challenge at 6 h postinjury were quantified from video recordings. Mice were euthanized at 6 and 12 h postcorneal injury for immunohistochemical analysis to quantify corneal neutrophil infiltration. Results: Corneal cauterization resulted in hyperalgesia to capsaicin at 6 h postinjury compared to sham control eyes. Neutrophil infiltration, indicative of inflammation, was apparent at 6 and 12 h postinjury in WT mice. Application of Δ8THC, CBD, and HU-308 reduced the pain score and neutrophil infiltration in WT mice. The antinociceptive and anti-inflammatory actions of Δ8THC, but not CBD, were blocked by the CB1R antagonist AM251, but were still apparent, for both cannabinoids, in CB2R−/− mice. However, the antinociceptive and anti-inflammatory actions of HU-308 were absent in the CB2R−/− mice. The antinociceptive and anti-inflammatory effects of CBD were blocked by the 5-HT1A antagonist WAY100635. Conclusion: Topical cannabinoids reduce corneal hyperalgesia and inflammation. The antinociceptive and anti-inflammatory effects of Δ8THC are mediated primarily via CB1R, whereas that of the cannabinoids CBD and HU-308, involve activation of 5-HT1A receptors and CB2Rs, respectively. Cannabinoids could be a novel clinical therapy for corneal pain and inflammation resulting from ocular surface injury. PMID:29450258

PSNCBAM-1, a novel allosteric antagonist at cannabinoid CB1 receptors with hypophagic effects in rats.

PubMed

Horswill, J G; Bali, U; Shaaban, S; Keily, J F; Jeevaratnam, P; Babbs, A J; Reynet, C; Wong Kai In, P

2007-11-01

Rimonabant (Acomplia, SR141716A), a cannabinoid CB1 receptor inverse agonist, has recently been approved for the treatment of obesity. There are, however, concerns regarding its side effect profile. Developing a CB1 antagonist with a different pharmacological mechanism may lead to a safer alternative. To this end we have screened a proprietary small molecule library and have discovered a novel class of allosteric antagonist at CB1 receptors. Herein, we have characterized an optimized prototypical molecule, PSNCBAM-1, and its hypophagic effects in vivo. A CB1 yeast reporter assay was used as a primary screen. PSNCBAM-1 was additionally characterized in [35S]-GTPgammaS, cAMP and radioligand binding assays. An acute rat feeding model was used to evaluate its effects on food intake and body weight in vivo. In CB1 receptor yeast reporter assays, PSNCBAM-1 blocked the effects induced by agonists such as CP55,940, WIN55212-2, anandamide (AEA) or 2-arachidonoyl glycerol (2-AG). The antagonist characteristics of PSNCBAM-1 were confirmed in [35S]-GTPgammaS binding and cAMP assays and was shown to be non-competitive by Schild analyses. PSNCBAM-1 did not affect CB2 receptors. In radioligand binding assays, PSNCBAM-1 increased the binding of [3H]CP55,940 despite its antagonist effects. In an acute rat feeding model, PSNCBAM-1 decreased food intake and body weight. PSNCBAM-1 exerted its effects through selective allosteric modulation of the CB1 receptor. The acute effects on food intake and body weight induced in rats provide a first report of in vivo activity for an allosteric CB1 receptor antagonist.

PSNCBAM-1, a novel allosteric antagonist at cannabinoid CB1 receptors with hypophagic effects in rats

PubMed Central

Horswill, J G; Bali, U; Shaaban, S; Keily, J F; Jeevaratnam, P; Babbs, A J; Reynet, C; Wong Kai In, P

2007-01-01

Background and purpose: Rimonabant (AcompliaTM, SR141716A), a cannabinoid CB1 receptor inverse agonist, has recently been approved for the treatment of obesity. There are, however, concerns regarding its side effect profile. Developing a CB1 antagonist with a different pharmacological mechanism may lead to a safer alternative. To this end we have screened a proprietary small molecule library and have discovered a novel class of allosteric antagonist at CB1 receptors. Herein, we have characterized an optimized prototypical molecule, PSNCBAM-1, and its hypophagic effects in vivo. Experimental approach: A CB1 yeast reporter assay was used as a primary screen. PSNCBAM-1 was additionally characterized in [35S]-GTPγS, cAMP and radioligand binding assays. An acute rat feeding model was used to evaluate its effects on food intake and body weight in vivo. Key results: In CB1 receptor yeast reporter assays, PSNCBAM-1 blocked the effects induced by agonists such as CP55,940, WIN55212-2, anandamide (AEA) or 2-arachidonoyl glycerol (2-AG). The antagonist characteristics of PSNCBAM-1 were confirmed in [35S]-GTPγS binding and cAMP assays and was shown to be non-competitive by Schild analyses. PSNCBAM-1 did not affect CB2 receptors. In radioligand binding assays, PSNCBAM-1 increased the binding of [3H]CP55,940 despite its antagonist effects. In an acute rat feeding model, PSNCBAM-1 decreased food intake and body weight. Conclusions and implications: PSNCBAM-1 exerted its effects through selective allosteric modulation of the CB1 receptor. The acute effects on food intake and body weight induced in rats provide a first report of in vivo activity for an allosteric CB1 receptor antagonist. PMID:17592509

Potential Antagonist of Folic Acid Metabolism as Malarial Drugs,

DTIC Science & Technology

1982-09-01

which sen.irited from the hydrocloric acid was filtered and then washed with water (25 ml). The reaction gave 2.3 g of the product which melted be...neutralized with cold dilute hydrocloric acid and evaporated to dryness. The residue was then extracted with methylene chloride filtered, and again...FhGh6/15hEE 1281 12.5 ~I1.50 IIA 132ii MJCRc)tll I’RE SOLU i UN ltIS CHiARI AD FINAL REPORT POTENTIAL ANTAGONIST OF FOLIC ACID METABOLISM AS MALARIAL

Effect of antisecretory agents and vagotomy on healing of chronic cysteamine-induced duodenal ulcers in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poulsen, S.S.; Raaberg, L.; Therkelsen, K.

1986-07-01

Penetrated cysteamine-induced duodenal ulcers in rats have a very prolonged course of healing. In this study, it was investigated how much the healing of these ulcers is accelerated by some treatments. The treatments included omeprazole, cimetidine, and truncal vagotomy. In addition, the effect of omeprazole and cimetidine on gastric acid secretion was investigated in chronic gastric fistula rats. After 25 days of treatment, significantly more rats in the treated groups had healed ulcers than in the control group. There was little further improvement up to 100 days of treatment, and the difference between treated and untreated groups decreased. The morphologymore » of healing ulcers in treated and untreated rats was also compared. In controls, there was a simultaneous regeneration of mucosa and the submucosal Brunner's glands from the edges of the ulcer, the slow proliferation rate of the latter probably being decisive for the prolonged healing. In the treated rats, the mucosa first regenerated with formation of crypts and low villi and subsequently, the Brunner's glands were formed by proliferation from the bottom of the crypts.« less

Viridepyronone, a new antifungal 6-substituted 2H-pyran-2-one produced by Trichoderma viride.

PubMed

Evidente, Antonio; Cabras, Annalisa; Maddau, Lucia; Serra, Salvatorica; Andolfi, Anna; Motta, Andrea

2003-11-19

A new antifungal 6-substituted 2H-pyran-2-one, named viridepyronone, has been isolated from a cultural filtrate of a strain of Trichoderma viride showing antagonistic activity in vitro toward Sclerotium rolfsii, which is the causal agent of crown and stem rot of artichoke. Viridepyronone was characterized as 6-(4-oxopentyl)-2H-pyran-2-one 2 with spectroscopic methods. Bioassays showed that viridepyronone had a good antifungal activity against S. rolfsii, and its minimum inhibitory concentration (over 90% inhibition) was found to be 196 microg/mL. This is the first report of viridepyronone produced by any species of fungi.

Opposing actions of dibutyryl cyclic AMP and GMP on temperature in conscious guinea-pigs

NASA Technical Reports Server (NTRS)

Kandasamy, S. B.; Williaes, B. A.

1983-01-01

It is shown that the intracerebroventricular administration of dibutyryl cyclic AMP (Db-cAMP) induced hyperthermia in guinea pigs which was not mediated through prostaglandins or norepinephrine since a prostaglandin synthesis inhibitor and an alpha-adrenergic receptor blocking agent did not antagonize the hyperthermia. However, the hyperthermic response to Db-cAMP was attenuated by the central administration of a beta-adrenergic receptor antagonist, which indicates that cAMP may be involved, through beta-adrenergic receptors, in the central regulation of heat production and conservation. The central administration of Db-cGMP produced hypothermia which was not mediated via histamine H1 or H2 receptors and serotonin. The antagonism of hypothermia induced by Db-cGMP and acetylcholine + physostigmine by central administration of a cholinergic muscarine receptor antagonist and not by a cholinergic nicotinic receptor antagonist suggests that cholinoceptive neurons and endogenous cGMP may regulate heat loss through cholinergic muscarine receptors. It is concluded that these results indicate a regulatory role in thermoregulation provided by a balance between opposing actions of cAMP and cGMP in guinea pigs.

Antagonism of corticotrophin-releasing factor receptors in the fourth ventricle modifies responses to mild but not restraint stress.

PubMed

Miragaya, Joanna R; Harris, Ruth B S

2008-08-01

Repeated restraint stress (RRS; 3 h of restraint on 3 consecutive days) in rodents produces temporary hypophagia, but a long-term downregulation of body weight. The mild stress (MS) of an intraperitoneal injection of saline and housing in a novel room for 2 h also inhibits food intake and weight gain, but the effects are smaller than for RRS. Previous exposure to RRS exaggerates hypophagia, glucocorticoid release, and anxiety-type behavior caused by MS. Here we tested the involvement of brain stem corticotrophin-releasing factor receptors (CRFR) in mediating energetic and glucocorticoid responses to RRS or MS and in promoting stress hyperresponsiveness in RRS rats. Administration of 1.3 nmol alphahCRF(9-41), a nonspecific CRFR antagonist, exaggerated hypophagia and weight loss in both RRS and MS rats, whereas 0.26 nmol had no effect in RRS or MS rats. In contrast, 2 nmol of the nonspecific antagonist astressin had no effect on weight loss or hypersensitivity to subsequent MS in RRS rats, but blocked weight loss and inhibition of food intake caused by MS alone. MS rats infused with 3 nmol antisauvagine-30, a CRFR2 antagonist, did not lose weight in the 48 h after MS, but 0.3 nmol did not prevent weight loss in MS rats. These data suggest that inhibition of food intake and weight loss induced by RRS or by MS involve different pathways, with hindbrain CRFR mediating the effect of MS on body weight and food intake. Hindbrain CRFR do not appear to influence stress-induced corticosterone release in RRS rats.

5-HT1A receptor antagonists reduce food intake and body weight by reducing total meals with no conditioned taste aversion.

PubMed

Dill, M Joelle; Shaw, Janice; Cramer, Jeff; Sindelar, Dana K

2013-11-01

Serotonin acts through receptors controlling several physiological functions, including energy homeostasis regulation and food intake. Recent experiments demonstrated that 5-HT1A receptor antagonists reduce food intake. We sought to examine the microstructure of feeding with 5-HT1A receptor antagonists using a food intake monitoring system. We also examined the relationship between food intake, inhibition of binding and pharmacokinetic (PK) profiles of the antagonists. Ex vivo binding revealed that, at doses used in this study to reduce food intake, inhibition of binding of a 5-HT1A agonist by ~40% was reached in diet-induced obese (DIO) mice with a trend for higher binding in DIO vs. lean animals. Additionally, PK analysis detected levels from 2 to 24h post-compound administration. Male DIO mice were administered 5-HT1A receptor antagonists LY439934 (10 or 30 mg/kg, p.o.), WAY100635 (3 or 10mg/kg, s.c.), SRA-333 (10 or 30 mg/kg, p.o.), or NAD-299 (3 or 10mg/kg, s.c.) for 3 days and meal patterns were measured. Analyses revealed that for each antagonist, 24-h food intake was reduced through a specific decrease in the total number of meals. Compared to controls, meal number was decreased 14-35% in the high dose. Average meal size was not changed by any of the compounds. The reduction in food intake reduced body weight 1-4% compared to Vehicle controls. Subsequently, a conditioned taste aversion (CTA) assay was used to determine whether the feeding decrease might be an indicator of aversion, nausea, or visceral illness caused by the antagonists. Using a two bottle preference test, it was found that none of the compounds produced a CTA. The decrease in food intake does not appear to be a response to nausea or malaise. These results indicate that 5-HT1A receptor antagonist suppresses feeding, specifically by decreasing the number of meals, and induce weight loss without an aversive side effect. © 2013 Elsevier Inc. All rights reserved.

Structure-activity relationship of 5-chloro-2-methyl-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole analogues as 5-HT(6) receptor agonists.

PubMed

Mattsson, Cecilia; Svensson, Peder; Boettcher, Henning; Sonesson, Clas

2013-05-01

To further investigate the structure-activity relationship (SAR) of the 5-hydroxytryptamine type 6 (5-HT6) receptor agonist 5-chloro-2-methyl-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole (EMD386088, 6), a series of 2-methyl-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indoles were synthesized, and in vitro affinity to, and functional activity at 5-HT6 receptors was tested. We focused on substituents made at the indole N(1)-, 2- and 5-positions and these were found to not only influence the affinity at 5-HT6 receptors but also the intrinsic activity leading to antagonists, partial agonists and full agonists. In order for a compound to demonstrate potent 5-HT6 receptor agonist properties, the indole N(1) should be unsubstituted, an alkyl group such as 2-methyl is needed and finally halogen substituents in the indole 5-position (fluoro, chloro or, bromo) were essential requirements. However, the introduction of a benzenesulfonyl group at N(1)-position switched the full agonist 6 to be a 5-HT6 receptor antagonist (30). A few compounds within the 2-methyl-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indoles were also screened for off-targets and generally they displayed low affinity for other 5-HT subtypes and serotonin transporter protein (SERT). Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Structural basis of subunit selectivity for competitive NMDA receptor antagonists with preference for GluN2A over GluN2B subunits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lind, Genevieve E.; Mou, Tung-Chung; Tamborini, Lucia

NMDA-type glutamate receptors are ligand-gated ion channels that contribute to excitatory neurotransmission in the central nervous system (CNS). Most NMDA receptors comprise two glycine-binding GluN1 and two glutamate-binding GluN2 subunits (GluN2A–D). We describe highly potent (S)-5-[(R)-2-amino-2-carboxyethyl]-4,5-dihydro-1H-pyrazole-3-carboxylic acid (ACEPC) competitive GluN2 antagonists, of which ST3 has a binding affinity of 52 nM at GluN1/2A and 782 nM at GluN1/2B receptors. This 15-fold preference of ST3 for GluN1/2A over GluN1/2B is improved compared with NVP-AAM077, a widely used GluN2A-selective antagonist, which we show has 11-fold preference for GluN1/2A over GluN1/2B. Crystal structures of the GluN1/2A agonist binding domain (ABD) heterodimer with boundmore » ACEPC antagonists reveal a binding mode in which the ligands occupy a cavity that extends toward the subunit interface between GluN1 and GluN2A ABDs. Mutational analyses show that the GluN2A preference of ST3 is primarily mediated by four nonconserved residues that are not directly contacting the ligand, but positioned within 12 Å of the glutamate binding site. Two of these residues influence the cavity occupied by ST3 in a manner that results in favorable binding to GluN2A, but occludes binding to GluN2B. Thus, we reveal opportunities for the design of subunit-selective competitive NMDA receptor antagonists by identifying a cavity for ligand binding in which variations exist between GluN2A and GluN2B subunits. This structural insight suggests that subunit selectivity of glutamate-site antagonists can be mediated by mechanisms in addition to direct contributions of contact residues to binding affinity.« less

Structural basis of subunit selectivity for competitive NMDA receptor antagonists with preference for GluN2A over GluN2B subunits

PubMed Central

Lind, Genevieve E.; Mou, Tung-Chung; Tamborini, Lucia; Pomper, Martin G.; De Micheli, Carlo; Conti, Paola; Pinto, Andrea

2017-01-01

NMDA-type glutamate receptors are ligand-gated ion channels that contribute to excitatory neurotransmission in the central nervous system (CNS). Most NMDA receptors comprise two glycine-binding GluN1 and two glutamate-binding GluN2 subunits (GluN2A–D). We describe highly potent (S)-5-[(R)-2-amino-2-carboxyethyl]-4,5-dihydro-1H-pyrazole-3-carboxylic acid (ACEPC) competitive GluN2 antagonists, of which ST3 has a binding affinity of 52 nM at GluN1/2A and 782 nM at GluN1/2B receptors. This 15-fold preference of ST3 for GluN1/2A over GluN1/2B is improved compared with NVP-AAM077, a widely used GluN2A-selective antagonist, which we show has 11-fold preference for GluN1/2A over GluN1/2B. Crystal structures of the GluN1/2A agonist binding domain (ABD) heterodimer with bound ACEPC antagonists reveal a binding mode in which the ligands occupy a cavity that extends toward the subunit interface between GluN1 and GluN2A ABDs. Mutational analyses show that the GluN2A preference of ST3 is primarily mediated by four nonconserved residues that are not directly contacting the ligand, but positioned within 12 Å of the glutamate binding site. Two of these residues influence the cavity occupied by ST3 in a manner that results in favorable binding to GluN2A, but occludes binding to GluN2B. Thus, we reveal opportunities for the design of subunit-selective competitive NMDA receptor antagonists by identifying a cavity for ligand binding in which variations exist between GluN2A and GluN2B subunits. This structural insight suggests that subunit selectivity of glutamate-site antagonists can be mediated by mechanisms in addition to direct contributions of contact residues to binding affinity. PMID:28760974

Studies on molecular properties prediction and histamine H3 receptor affinities of novel ligands with uracil-based motifs.

PubMed

Lipani, Luca; Odadzic, Dalibor; Weizel, Lilia; Schwed, Johannes-Stephan; Sadek, Bassem; Stark, Holger

2014-10-30

The histamine H3 receptor (H3R) plays a role in cognitive and memory processes and is involved in different neurological disorders, including Alzheimer's disease, schizophrenia, and narcolepsy. Therefore, several hH3R antagonists/inverse agonists entered clinical phases for a broad spectrum of mainly centrally occurring diseases. However, many other promising candidates failed due to their pharmacokinetic profile, mostly because of their strong lipophilicity accompanied with low solubility. Analysis of previous potential H3R selective antagonists/inverse agonists, e.g. pitolisant, revealed promising results concerning physicochemical properties and drug-likeness. Herein, a series of new hH3R ligands 8-20 consisting of piperidin-1-yl or piperidin-1-yl-propoxyphenyl coupled to different uracil, thymine, and 5,6-dimethyluracil related moieties, were synthesized, evaluated on their binding properties at the hH3R and the estimation of different physicochemical and drug-likeness properties. Due to the coupling to various positions at pyrimidine-2,4-(1H,3H)-dione, affinity at hH3Rs and drug-likeness parameters have been improved. For instance, compound 9 showed in addition to high affinity at the hH3R (pKi (hH3R) = 8.14) clog S, clog P, LE, LipE, and drug-likeness score values of -4.36, 3.47, 0.34, 4.63, and 1.54, respectively. Also, the methyl substituted analog 17 (pKi (hH3R) = 8.15) revealed LE, LipE and drug-likeness score values of -3.29, 2.47, 0.49, 5.52, and 1.76, respectively. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Tc-labeling of Peptidomimetic Antagonist to Selectively Target alpha(v)beta(3) Receptor-Positive Tumor: Comparison of PDA and EDDA as co-Ligands.

PubMed

Shin, In Soo; Maeng, Jin Soo; Jang, Beom-Su; You, Eric; Cheng, Kenneth; Li, King C P; Wood, Bradford; Carrasquillo, Jorge A; Danthi, S Narasimhan; Paik, Chang H

2010-01-01

OBJECTIVES: The aim of this research was to synthesize radiolabeled peptidomimetic integrin alpha(v)beta(3) antagonist with (99m)Tc for rapid targeting of integrin alpha(v)beta(3) receptors in tumor to produce a high tumor to background ratio. METHODS: The amino terminus of 4-[2-(3,4,5,6-tetra-hydropyrimidin-2-ylamino)-ethyloxy]benzoyl-2-(S)-[N-(3-amino-neopenta-1-carbamyl)]-aminoethylsulfonyl-amino-beta-alanine hydrochloride (IAC) was conjugated with N-hydroxysuccinimide ester of HYNIC and labeled with (99m)Tc using tricine with either 1,5-pyridinedicarboxylic acid (PDA) or ethylenediamine-N,N'-diacetic acid (EDDA) as the co-ligand. The products, (99m)Tc EDDA(2)/HYNIC-IAC (P1) and (99m)Tc PDA (tricin)/HYNIC-IAC (P2) were subjected to in vitro serum stability, receptor-binding, biodistribution and imaging studies. RESULTS: P1 and P2 were synthesized with an overall yield of >80%. P1 was slightly more stable than P2 when incubated in serum at 37 degrees C for 18 hrs (84 vs 77% intact). The In vitro receptor-binding of P1 was higher than that of P2 (78.02 +/- 13.48 vs 51.05 +/- 14.05%) when incubated with alpha(v)beta(3) at a molar excess (0.8 muM). This receptor binding was completely blocked by a molar excess of an unlabeled peptidomimetic antagonist. Their differences shown in serum stability and the receptor-binding appeared to be related to their biological behaviors in tumor uptake and retention; the 1 h tumor uptakes of P1 and P2 were 3.17+/-0.52 and 2.13+/-0.17 % ID/g, respectively. P1 was retained in the tumor longer than P2. P1 was excreted primarily through the renal system whereas P2 complex was excreted equally via both renal and hepatobiliary systems. Thus, P1 was retained in the whole-body with 27.25 +/- 3.67% ID at 4 h whereas 54.04 +/- 3.57% ID of P2 remained in the whole-body at 4 h. This higher whole-body retention of P2 appeared to be resulted from a higher amount of radioactivity retained in liver and intestine. These findings were supported by imaging studies showing higher tumor-to-abdominal contrast for P1 than for P2 at 3 h postinjection. CONCLUSIONS: P1 showed good tumor targeting properties with a rapid tumor uptake, prolonged tumor retention and fast whole-body clearance kinetics. These findings warrant further investigation of the HYNIC method of (99m)Tc labeling of other peptidomimetic antagonists using EDDA as a coligand.

Development of a Small Molecule P2X7R Antagonist as a Treatment for Acute SCI

DTIC Science & Technology

2012-10-01

neurons. Nat Neurosci 10:615–622. Nagele RG, D’Andrea MR, Lee H, Venkataraman V, Wang HY (2003) Astrocytes accumulate Ab 42 and give rise to astrocytic...amyloid plaques in Alzheimer disease brains. Brain Res 971:197–209. Nagele RG, Wegiel J, Venkataraman V, Imaki H, Wang KC (2004) Contribution of glial

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 reversed when rats were pretreated with the selective H3R agonist R-(α)-methyl-histamine. Comparisons of the observed antagonistic in vitro affinities among the ligands 1–6 revealed profound stereoselectivity at human H3Rs with varying preferences for this receptor subtype. Moreover, the in vivo anticonvulsant effects observed in this study for ligands 1–6 showed stereoselectivity in different convulsion models in male adult rats. PMID:27853355

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 H 3 receptors (H 3 Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H 3 Rs 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 H 3 R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and reversed when rats were pretreated with the selective H 3 R agonist R -(α)-methyl-histamine. Comparisons of the observed antagonistic in vitro affinities among the ligands 1 - 6 revealed profound stereoselectivity at human H 3 Rs with varying preferences for this receptor subtype. Moreover, the in vivo anticonvulsant effects observed in this study for ligands 1 - 6 showed stereoselectivity in different convulsion models in male adult rats.

Alpha-2 adrenergic activity of bromocriptine and quinpirole in chicken pineal gland. Effects on melatonin synthesis and ( sup 3 H)rauwolscine binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zawilska, J.; Iuvone, P.M.

In the pineal gland and retina of chickens, serotonin N-acetyl-transferase (NAT) activity and melatonin content are modulated by different receptors, alpha-2 adrenergic receptors in pineal gland and D2-dopamine receptors in retina. The effect of two D2-dopamine receptor agonists, bromocriptine and quinpirole (LY 171555), on melatonin synthesis in these tissues was investigated. Systemic administrations of bromocriptine and quinpirole decreased nocturnal NAT activity and melatonin content of both pineal gland and retina. Bromocriptine was equipotent in the two tissues, whereas quinpirole was approximately 100-fold more potent in retina than in pineal gland. In pineal gland, the suppressive effects of bromocriptine and quinpirolemore » on NAT activity were blocked by yohimbine, a selective alpha-2 adrenergic receptor antagonist, but not by spiperone, a D2-dopamine receptor antagonist. In contrast, bromocriptine- and quinpirole-induced decreases of the enzyme activity in retina were antagonized by spiperone, and not affected by yohimbine. The nocturnal increase of NAT activity of pineal glands in vitro was inhibited with an order of potency clonidine greater than bromocriptine greater than quinpirole. Additionally, bromocriptine and quinpirole displaced the specific binding of (3H)rauwolscine, an alpha-2 adrenergic receptor antagonist, to membranes from chicken pineal gland, with potencies comparable to those observed for inhibition of NAT activity in vitro. It is suggested that bromocriptine and quinpirole, in addition to their D2-dopaminergic activity, can stimulate alpha-2 adrenergic receptors in pineal gland of chicken.« less

Antidepressant-like effect of the organoselenium compound ebselen in mice: evidence for the involvement of the monoaminergic system.

PubMed

Posser, Thaís; Kaster, Manuella P; Baraúna, Sara Cristiane; Rocha, João B T; Rodrigues, Ana Lúcia S; Leal, Rodrigo B

2009-01-05

Ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one] is a seleno-organic compound which possesses a potent antioxidant activity and has been shown to exert neuroprotective effects in vitro and in vivo in a variety of pro-oxidative insults. The present study investigates a possible antidepressant activity of ebselen using two predictive tests for antidepressant activity in rodents: the forced swimming test and tail suspension test. Additionally, the mechanisms involved in the antidepressant-like effect of ebselen in mice were also assessed. Ebselen (10 mg/kg, s.c.) decreased the immobility time in the forced swimming test without accompanying changes in ambulation in the open-field test. In contrast, the administration of ebselen (10-30 mg/kg) did not produce any effect in the tail suspension test. The anti-immobility effect of ebselen (10 mg/kg, s.c.) was not prevented by pre-treatment of mice with p-chlorophenylalanine (PCPA, 100 mg/kg, i.p., an inhibitor of serotonin synthesis, 4 consecutive days), NAN-190 (0.5 mg/kg, i.p., a serotonin 5-HT(1A) receptor antagonist) or ketanserin (5 mg/kg, i.p., a serotonin 5-HT(2A/2C) receptor antagonist). On the other hand, the pre-treatment of mice with prazosin (1 mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., a dopamine D(1) receptor antagonist) or sulpiride (50 mg/kg, i.p., a dopamine D(2) receptor antagonist) completely blocked the antidepressant-like effect of ebselen (10 mg/kg, s.c.) in the forced swimming test. It may be concluded that ebselen produces an antidepressant-like effect in the forced swimming test that seems to be dependent on its interaction with the noradrenergic and dopaminergic systems, but not with the serotonergic system.

Extraction of ranitidine and nizatidine with using imidazolium ionic liquids prior spectrophotometric and chromatographic detection.

PubMed

Kiszkiel, Ilona; Starczewska, Barbara; Leśniewska, Barbara; Późniak, Patrycja

2015-03-15

A new extraction medium was proposed for liquid-liquid extraction of the histamine H2 receptor antagonists ranitidine (RNT) and nizatidine (NZT). The ionic liquids with low vapor pressure and favorable solvating properties for a range of compounds such as 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4mim][Tf2N] were tested for isolation of analytes. The extraction parameters of RNT and NZT, namely, amount of ionic liquid, pH of sample solution, shaking and centrifugation time were optimized. The isolation processes were performed with 1 mL of the ionic liquids. The extracted samples (pH values near 4) were shaken at 1750 rpm. The influence of interfering substances on the efficiency of extraction process was also studied. Methods for the histamine H2 receptor antagonists (ranitidine and nizatidine) determination after their separation using imidazolium ionic liquids by high performance liquid chromatography (HPLC) combined with UV spectrophotometry were developed. The application of ionic liquids in extraction step allows for selective isolation of analytes from aqueous matrices and their preconcentration. The above methods were applied to the determination of RNT and NZT in environmental samples (river water and wastewater after treatment). Copyright © 2014 Elsevier B.V. All rights reserved.

Cyproheptadine Enhances the I K of Mouse Cortical Neurons through Sigma-1 Receptor-Mediated Intracellular Signal Pathway

PubMed Central

He, Yan-Lin; Zhang, Chun-Lei; Gao, Xiao-Fei; Yao, Jin-Jing; Hu, Chang-Long; Mei, Yan-Ai

2012-01-01

Cyproheptadine (CPH) is a histamine- and serotonin-receptor antagonist, and its effects are observed recently in the modulation of multiple intracellular signals. In this study, we used cortical neurons and HEK-293 cells transfected with Kv2.1 α-subunit to address whether CPH modify neural voltage-gated K+ channels by a mechanism independent of its serotonergic and histaminergic properties. Our results demonstrate that intracellularly delivered CPH increased the I K by reducing the activity of protein kinas A (PKA). Inhibition of Gi eliminated the CPH-induced effect on both the I K and PKA. Blocking of 5-HT-, M-, D2-, H1- or H2- type GPCR receptors with relevant antagonists did not eliminate the CPH-induced effect on the I K. Antagonists of the sigma-1 receptor, however, blocked the effect of CPH. Moreover, the inhibition of sigma-1 by siRNA knockdown significantly reduced the CPH-induced effect on the I K. On the contrary, sigma-1 receptor agonist mimicked the effects of CPH on the induction of I K. A ligand-receptor binding assay indicated that CPH bound to the sigma-1 receptor. Similar effect of CPH were obtained from HEK-293 cells transfected with the α-subunit of Kv2.1. In overall, we reveal for the first time that CPH enhances the I K by modulating activity of PKA, and that the associated activation of the sigma-1 receptor/Gi-protein pathway might be involved. Our findings illustrate an uncharacterized effect of CPH on neuron excitability through the I K, which is independent of histamine H1 and serotonin receptors. PMID:22844454

JS-K, an arylating nitric oxide (NO) donor, has synergistic anti-leukemic activity with cytarabine (ARA-C).

PubMed

Shami, Paul J; Maciag, Anna E; Eddington, Jordan K; Udupi, Vidya; Kosak, Ken M; Saavedra, Joseph E; Keefer, Larry K

2009-11-01

We have designed prodrugs that release nitric oxide (NO) on metabolism by glutathione S-transferases (GST). This design exploits the upregulation of GST in acute myeloid leukemia (AML) cells. O(2)-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K, a member of this class) has potent anti-leukemic activity. HL-60 myeloid leukemia cells were used for in vitro studies of the combination of JS-K with daunorubicin (DAUNO), cytarabine (ARA-C) or etoposide (ETOP) using the median effect method to determine synergistic, antagonistic, or additive effects. Combinations of JS-K added simultaneously, 2h before or 2h after the other compounds were used. JS-K and DAUNO were antagonistic in all three drug sequences. JS-K and ETOP were also antagonistic but to a lesser degree. JS-K and ARA-C showed strong synergy. The combination index at the 50% fraction affected was 0.37+/-0.23, 0.24+/-0.27, and 0.15+/-0.11 for simultaneous, JS-K first and ARA-C first additions, respectively. JS-K by itself induced DNA strand breaks at relatively high concentrations. However, at submicromolar concentrations, it significantly augmented ARA-C-induced DNA strand breaks. NMR spectroscopy revealed no evidence of chemical interaction between JS-K and the other chemotherapeutic agents. We conclude that ARA-C and JS-K have synergistic anti-leukemic activity and warrant further exploration in combination.

D-Cycloserine improves functional outcome after traumatic brain injury with wide therapeutic window

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adeleye, A.; Biegon, A.; Adeleye, A.

It has been long thought that hyperactivation of N-methyl-D-aspartate (NMDA) receptors underlies neurological decline after traumatic brain injury. However, all clinical trials with NMDA receptor antagonists failed. Since NMDA receptors are down-regulated from 4 h to 2 weeks after brain injury, activation at 24 h, rather than inhibition, of these receptors, was previously shown to be beneficial in mice. Here, we tested the therapeutic window, dose regimen and mechanism of action of the NMDA receptor partial agonist d-cycloserine (DCS) in traumatic brain injury. Male mice were subjected to trauma using a weight-drop model, and administered 10 mg/kg (i.p.) DCS ormore » vehicle once (8, 16, 24, or 72 h) twice (24 and 48 h) or three times (24, 48 and 72 h). Functional recovery was assessed for up to 60 days, using a Neurological Severity Score that measures neurobehavioral parameters. In all groups in which treatment was begun at 24 or 72 h neurobehavioral function was significantly better than in the vehicle-treated groups. Additional doses, on days 2 and 3 did not further improve recovery. Mice treated at 8 h or 16 h post injury did not differ from the vehicle-treated controls. Co-administration of the NMDA receptor antagonist MK-801 completely blocked the protective effect of DCS given at 24 h. Infarct volume measured by 2,3,5-triphenyltetrazolium chloride staining at 48 h or by cresyl violet at 28 days was not affected by DCS treatment. Since DCS is used clinically for other indications, the present study offers a novel approach for treating human traumatic brain injury with a therapeutic window of at least 24 h.« less

Pharmacologic properties of KT2-962 (6-isopropyl-3-[4-(p- chlorobenzenesulfonylamino)-butyl]-azulene-1-sulfonic acid sodium salt); a new TXA2/prostaglandin endoperoxide receptor antagonist.

PubMed

Kosakai, K; Wakabayashi, S; Sato, T; Mochizuki, S; Tomiyama, A; Zhou, Q; Satake, N; Shibata, S

1993-03-01

Pharmacologic properties of KT2-962 (6-isopropyl-3-[4-(p-chlorobenzenesulfonylamino)butyl]-azulene+ ++-1-sulfonic acid sodium salt, KT) were studied in isolated rat aorta, rat tail artery, rabbit aorta, rabbit renal artery, and pig coronary artery. KT competitively inhibited the contractions induced by thromboxane A2 (TXA2) mimetic, U46619 (pA2 values 9.95, 8.85, 7.87, 8.49, and 9.12, respectively). KT also inhibited the contraction of rabbit aorta induced by prostaglandin2 alpha (PGF2 alpha, pA2 value 7.85) and the contraction of guinea pig ileum induced by LTD4 (pA2 value 5.48) but did not alter the contractions induced by norepinephrine (NE), Ca2+, serotonin, and histamine. KT did not alter the contractions of guinea pig ileum, which did not contract with U46619, induced by PGE2 and PGF2 alpha. KT inhibited the aggregations of rabbit platelets induced by U46619, arachidonic acid, and collagen (IC50 values 7.9, 140, and 16 microM, respectively) but not those induced by ADP. It also inhibited the specific binding of TXA2/PGH2 receptor antagonist, [3H]SQ29,548, to rabbit gel-filtered platelets with an IC50 value of 1.5 x 10(-8) M. In in vivo experiments with mice, oral administration of KT protected the U46619-induced sudden death with the minimum effective dose of 0.3 mg/kg and provided such protection for > 8 h at 1.0 mg/kg. These results indicate that KT is a new nonprostanoid type TXA2/PGH2 receptor antagonist that is orally effective and long acting.

Antagonistic effect of chosen lactic acid bacteria strains on Yersinia enterocolitica species in model set-ups, meat and fermented sausages.

PubMed

Gomółka-Pawlicka, M; Uradziński, J

2003-01-01

The present study was aimed at determining the influence of 15 strains of lactic acid bacteria on the growth of 8 Yersinia enterocolitica strains in model set-ups, and in meat and ageing fermented sausages. The investigations were performed within the framework of three alternate stages which differed in respect to the products studied, the number of Lactobacillus sp. strains and, partly, methodological approach. The ratio between lactic acid bacteria and Yersinia enterocolitica strains studied was, depending on the variant of experiment, 1:1, 1:2 and 2:1, respectively. The study also considered water activity (aw) and pH of the products investigated. The results suggest that all the lactic acid bacteria strains used within the framework of the model set-ups had antagonistic effect on all the Salmonella sp. strains. However, this ability was not observed with respect to of tested lactic acid bacteria strains in meat and fermented sausage. This ability was possessed by one of the strains investigated--Lactobacillus helveticus T 78. The temperature and time of the incubation of sausages, but not aw and pH, were found to have a distinct influence on the antagonistic interaction between the bacteria tested.

Bioprospecting marine actinomycetes for multidrug-resistant pathogen control from Rameswaram coastal area, Tamil Nadu, India.

PubMed

Wahaab, Femina; Subramaniam, Kalidass

2018-01-01

A potent Streptomyces bacillaris strain RAM25C4 was isolated for controlling methicillin-resistant Staphylococcus aureus and multidrug-resistant bacteria such as Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa. A total of 131 actinomycetes were isolated from the Rameswaram coastal region, Tamil Nadu, India. Among 131 actinomycetes, maximum number of actinomycetes (55%) isolated at the distance of 3-6 m from seashore. Out of 131 actinomycetes, 85% of the actinomycetes exhibited different degree of antagonistic activity against test pathogens. The antagonistic activity evaluated using actinomycetes direct culture filtrate and culture filtrate extracts. Among these culture filtrate, extracts had supreme antagonistic activity against multidrug-resistant bacteria and the solvent ethyl acetate was the best for extracting secondary metabolites from actinomycetes. In HPTLC analysis, the presence of macrolides, terpenoids, and quinolones was identified in RAM25C4 extract. In GC-MS analysis, various potent compounds such as phenolic compound-2,6-di-tert-butylphenol, alkaloid compound-1H, 5H, pyrrolo (1' 2':3, 4) imidazo, and quinolone compound-1,4-benzenediol, 2,5-bis(1,1-dimethylethyl) were identified in the ethyl acetate extract of RAM25C4. The phylogenetic analysis of 16S rRNA gene sequence of RAM25C4 isolate was deposited in NCBI with name Streptomyces bacillaris strain RAM25C4 and accession number KM513543.

Short-term treatment with proton pump inhibitors, H2-receptor antagonists and prokinetics for gastro-oesophageal reflux disease-like symptoms and endoscopy negative reflux disease.

PubMed

Sigterman, Kirsten E; van Pinxteren, Bart; Bonis, Peter A; Lau, Joseph; Numans, Mattijs E

2013-05-31

Approximately 25% of adults regularly experience heartburn, a symptom of gastro-oesophageal reflux disease (GORD). Most patients are treated empirically (without specific diagnostic evaluation e.g. endoscopy. Among patients who have an upper endoscopy, findings range from a normal appearance, mild erythema to severe oesophagitis with stricture formation. Patients without visible damage to the oesophagus have endoscopy negative reflux disease (ENRD). The pathogenesis of ENRD, and its response to treatment may differ from GORD with oesophagitis. Summarise, quantify and compare the efficacy of short-term use of proton pump inhibitors (PPI), H2-receptor antagonists (H2RA) and prokinetics in adults with GORD, treated empirically and in those with endoscopy negative reflux disease (ENRD). We searched MEDLINE (January 1966 to November 2011), EMBASE (January 1988 to November 2011), and EBMR in November 2011. Randomised controlled trials reporting symptomatic outcome after short-term treatment for GORD using proton pump inhibitors, H2-receptor antagonists or prokinetic agents. Participants had to be either from an empirical treatment group (no endoscopy used in treatment allocation) or from an endoscopy negative reflux disease group (no signs of erosive oesophagitis). Two authors independently assessed trial quality and extracted data. Thirty-four trials (1314 participants) were included: fifteen in the empirical treatment group, fifteen in the ENRD group and four in both. In empirical treatment of GORD the risk ratio (RR) for heartburn remission (the primary efficacy variable) in placebo-controlled trials for PPI was 0.37 (two trials, 95% confidence interval (CI) 0.32 to 0.44), for H2RAs 0.77 (two trials, 95% CI 0.60 to 0.99) and for prokinetics 0.86 (one trial, 95% CI 0.73 to 1.01). In a direct comparison PPIs were more effective than H2RAs (seven trials, RR 0.66, 95% CI 0.60 to 0.73) and prokinetics (two trials, RR 0.53, 95% CI 0.32 to 0.87).In treatment of ENRD, the RR for heartburn remission for PPI versus placebo was 0.71 (ten trials, 95% CI 0.65 to 0.78) and for H2RA versus placebo was 0.84 (two trials, 95% CI 0.74 to 0.95). The RR for PPI versus H2RA was 0.78 (three trials, 95% CI 0.62 to 0.97) and for PPI versus prokinetic 0.72 (one trial, 95% CI 0.56 to 0.92). PPIs are more effective than H2RAs in relieving heartburn in patients with GORD who are treated empirically and in those with ENRD, although the magnitude of benefit is greater for those treated empirically.

Short-term treatment with proton pump inhibitors, H2-receptor antagonists and prokinetics for gastro-oesophageal reflux disease-like symptoms and endoscopy negative reflux disease.

PubMed

van Pinxteren, Bart; Sigterman, Kirsten E; Bonis, Peter; Lau, Joseph; Numans, Mattijs E

2010-11-10

Approximately 25% of adults regularly experience heartburn, a symptom of gastro-oesophageal reflux disease (GORD). Most patients are treated empirically (without specific diagnostic evaluation e.g. endoscopy. Among patients who have an upper endoscopy, findings range from a normal appearance, mild erythema to severe oesophagitis with stricture formation. Patients without visible damage to the oesophagus have endoscopy negative reflux disease (ENRD). The pathogenesis of ENRD, and its response to treatment may differ from GORD with oesophagitis. Summarise, quantify and compare the efficacy of short-term use of proton pump inhibitors (PPI), H2-receptor antagonists (H2RA) and prokinetics in adults with GORD, treated empirically and in those with endoscopy negative reflux disease (ENRD). We searched MEDLINE (January 1966 to November 2008), EMBASE (January 1988 to November 2008), and EBMR in November 2008. Randomised controlled trials reporting symptomatic outcome after short-term treatment for GORD using proton pump inhibitors, H2-receptor antagonists or prokinetic agents. Participants had to be either from an empirical treatment group (no endoscopy used in treatment allocation) or from an endoscopy negative reflux disease group (no signs of erosive oesophagitis). Two authors independently assessed trial quality and extracted data. Thirty-two trials (9738 participants) were included: fifteen in the empirical treatment group, thirteen in the ENRD group and four in both. In empirical treatment of GORD the relative risk (RR) for heartburn remission (the primary efficacy variable) in placebo-controlled trials for PPI was 0.37 (two trials, 95% confidence interval (CI) 0.32 to 0.44), for H2RAs 0.77 (two trials, 95% CI 0.60 to 0.99) and for prokinetics 0.86 (one trial, 95% CI 0.73 to 1.01). In a direct comparison PPIs were more effective than H2RAs (seven trials, RR 0.66, 95% CI 0.60 to 0.73) and prokinetics (two trials, RR 0.53, 95% CI 0.32 to 0.87). In treatment of ENRD, the RR for heartburn remission for PPI versus placebo was 0.73 (eight trials, 95% CI 0.67 to 0.78) and for H2RA versus placebo was 0.84 (two trials, 95% CI 0.74 to 0.95). The RR for PPI versus H2RA was 0.78 (three trials, 95% CI 0.62 to 0.97) and for PPI versus prokinetic 0.72 (one trial, 95% CI 0.56 to 0.92). PPIs are more effective than H2RAs in relieving heartburn in patients with GORD who are treated empirically and in those with ENRD, although the magnitude of benefit is greater for those treated empirically.

Dosage effects of histamine-2 receptor antagonist on the primary prophylaxis of non-steroidal anti-inflammatory drug (NSAID)-associated peptic ulcers: a retrospective cohort study.

PubMed

He, Ying; Chan, Esther W; Man, Kenneth K C; Lau, Wallis C Y; Leung, Wai K; Ho, Lai M; Wong, Ian C K

2014-09-01

A histamine-2 receptor antagonist (H2RA) is one of the common gastroprotective co-therapies used with non-steroidal anti-inflammatory drugs (NSAIDs) for the prevention or treatment of peptic ulcers (PUs). To date, no study has directly compared the prophylactic effectiveness between high-dose and low-dose H2RA. Our objective was to compare the effectiveness of high-dose versus low-dose H2RAs in the primary prophylaxis of PUs among short-term NSAID users. A retrospective cohort study was conducted using the Clinical Data Analysis and Reporting System (CDARS) in Hong Kong. Patients aged 18 years or above who received a single prescription of oral NSAID with oral H2RA were identified within the study period (1 January 2009-31 December 2012). Patients with a history of or risk factors for PU in the corresponding 2 years prior to the index date (of the first NSAID prescription) were excluded. Log binomial regression analysis was used to calculate the relative risk of PU among NSAID users with high-dose H2RA versus low-dose H2RA exposure. Among the NSAID cohort (n = 102,042), 77,509 (76 %) were on low-dose H2RA and 24,533 (24 %) were on high-dose H2RA. Of the total 69 PU cases identified during the drug exposure period, 64 (0.08 %) received low-dose-H2RA and five (0.02 %) received high-dose H2RA. The overall absolute risk of PUs for NSAID users whilst on H2RA was approximately 1 per 1,479 patients. The adjusted relative risk for NSAID users receiving high-dose H2RA versus low-dose H2RA was 0.32 (95 % confidence interval [CI] 0.13-0.79). Patients aged ≥65 years, receiving a longer duration of treatment, or with concomitant use of antiplatelet agents were found to be at higher risk of PU. High-dose H2RA showed greater effectiveness than low-dose H2RA in the primary prophylaxis of NSAID-associated PUs in short-term new users.

Glucose-independent inhibition of yeast plasma-membrane H+-ATPase by calmodulin antagonists.

PubMed

Romero, I; Maldonado, A M; Eraso, P

1997-03-15

Glucose metabolism causes activation of the yeast plasma-membrane H+-ATPase. The molecular mechanism of this regulation is not known, but it is probably mediated by phosphorylation of the enzyme. The involvement in this process of several kinases has been suggested but their actual role has not been proved. The physiological role of a calmodulin-dependent protein kinase in glucose-induced activation was investigated by studying the effect of specific calmodulin antagonists on the glucose-induced ATPase kinetic changes in wild-type and two mutant strains affected in the glucose regulation of the enzyme. Preincubation of the cells with calmidazolium or compound 48/80 impeded the increase in ATPase activity by reducing the Vmax of the enzyme without modifying the apparent affinity for ATP in the three strains. In one mutant, pma1-T912A, the putative calmodulin-dependent protein kinase-phosphorylatable Thr-912 was eliminated, and in the other, pma1-P536L, H+-ATPase was constitutively activated, suggesting that the antagonistic effect was not mediated by a calmodulin-dependent protein kinase and not related to glucose regulation. This was corroborated when the in vitro effect of the calmodulin antagonists on H+-ATPase activity was tested. Purified plasma membranes from glucose-starved or glucose-fermenting cells from both pma1-P890X, another constitutively activated ATPase mutant, and wild-type strains were preincubated with calmidazolium or melittin. In all cases, ATP hydrolysis was inhibited with an IC50 of approximately 1 microM. This inhibition was reversed by calmodulin. Analysis of the calmodulin-binding protein pattern in the plasma-membrane fraction eliminates ATPase as the calmodulin target protein. We conclude that H+-ATPase inhibition by calmodulin antagonists is mediated by an as yet unidentified calmodulin-dependent membrane protein.

Altered mental status in older adults with histamine2-receptor antagonists: a population-based study.

PubMed

Tawadrous, Davy; Dixon, Stephanie; Shariff, Salimah Z; Fleet, Jamie; Gandhi, Sonja; Jain, Arsh K; Weir, Matthew A; Gomes, Tara; Garg, Amit X

2014-10-01

Standard doses of histamine2-receptor antagonists (H2RAs) may induce altered mental status in older adults, especially in those with chronic kidney disease (CKD). Population-based cohort study of older adults who started a new H2RA between 2002 and 2011 was conducted. Ninety percent received the current standard H2RA dose in routine care. There was no significant difference in 27 baseline patient characteristics. The primary outcome was hospitalization with an urgent head computed tomography (CT) scan (proxy for altered mental status), and the secondary outcome was all-cause mortality also within 30days of a new H2RA prescription. Standard vs. low H2RA dose was associated with a higher risk of hospitalization with an urgent head CT scan (0.98% vs. 0.74%, absolute risk difference 0.24% [95% CI 0.11% to 0.36%], relative risk 1.33 [95% CI 1.12 to 1.58]). This risk was not modified by the presence of CKD (interaction P value=0.71). Standard vs. low H2RA dose was associated with a higher risk of mortality (1.07% vs.0.74%; absolute risk difference 0.34% [95% CI 0.20% to 0.46%], relative risk 1.46 [95% CI 1.23 to 1.73]). Compared to a lower dose, initiation of the current standard dose of H2RA in older adults is associated with a small absolute increase in the 30-day risk of altered mental status (using neuroimaging as a proxy), even in the absence of CKD. This risk may be avoided by initiating older adults on low doses of H2RAs for gastroesophogeal reflux disease, and increasing dosing as necessary for symptom control. Copyright © 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Effects of rhynchophylline on GluN1 and GluN2B expressions in primary cultured hippocampal neurons.

PubMed

He, Yan; Zeng, Sheng-Ya; Zhou, Shi-Wen; Qian, Gui-Sheng; Peng, Kang; Mo, Zhi-Xian; Zhou, Ji-Yin

2014-10-01

N-methyl-d-aspartate (NMDA) receptor subunits GluN1 and GluN2B in hippocampal neurons play key roles in anxiety. Our previous studies show that rhynchophylline, an active component of the Uncaria species, down-regulates GluN2B expression in the hippocampal CA1 area of amphetamine-induced rat. The effects of rhynchophylline on expressions of GluN1 and GluN2B in primary hippocampal neurons in neonatal rats in vitro were investigated. Neonatal hippocampal neurons were cultured with neurobasal-A medium. After incubation for 6h or 48 h with rhynchophylline (non-competitive NMDAR antagonist) and MK-801 (non-competitive NMDAR antagonist with anxiolytic effect, as the control drug) from day 6, neuron toxicity, mRNA and protein expressions of GluN1 and GluN2B were analyzed. GluN1 is mainly distributed on neuronal axons and dendritic trunks, cytoplasm and cell membrane near axons and dendrites. GluN2B is mainly distributed on the membrane, dendrites, and axon membranes. GluN1 and GluN2B are codistributed on dendritic trunks and dendritic spines. After 48 h incubation, a lower concentration of rhynchophylline (lower than 400 μmol/L) and MK-801 (lower than 200 μmol/L) have no toxicity on neonatal hippocampal neurons. Rhynchophylline up-regulated GluN1 mRNA expression at 6h and mRNA and protein expressions at 48h, but down-regulated GluN2B mRNA and protein expressions at 48 h. However, GluN1 and GluN2B mRNA expressions were down-regulated at 6h, and mRNA and protein expressions were both up-regulated by MK-801 at 48h. These findings show that rhynchophylline reciprocally regulates GluN1 and GluN2B expressions in hippocampal neurons, indicating a potential anxiolytic property for rhynchophylline. Copyright © 2014 Elsevier B.V. All rights reserved.

Mrz 2/579, a fast kinetic NMDA channel blocker, reduces the development of morphine tolerance in awake rats.

PubMed

Houghton, A K; Parsons, C G; Headley, P M

2001-04-01

The purpose of the present study was to investigate whether uncompetitive NMDA antagonists with fast channel blocking kinetics, which show fewer side effects in man than compounds such as ketamine, affect the development of tolerance to continuous exposure to morphine. Rats were trained on the Randall--Selitto apparatus before being implanted, under halothane anaesthesia, with primed mini-osmotic pumps (240 microl/day). Six rats were implanted with a vehicle filled pump, seven with a morphine filled pump (28.8 mg/kg/day), and eight with a pair of pumps, one containing morphine and the other Mrz 2/579, a new NMDA antagonist (40 mg/kg/day). A fourth group was implanted with a morphine filled pump followed 25 h later by a Mrz 2/579 filled pump. Paw withdrawal tests were undertaken immediately before, and at 2, 4, 6, 8, 10, 12, 24, 48 and 72 h after the first pump was implanted. Before pump implantation, withdrawal thresholds were 120+/-7 g (mean+/-SEM, n=30). Vehicle infusion had no effect on withdrawal thresholds, whereas morphine infusion increased them significantly at 2 and 4 h after pump implantation (+2 h: 208+/-14 g; P<0.001 vs. control). From 6 h the antinociception elicited by morphine declined progressively; at 10 h withdrawal thresholds were significantly lower than the 2 h post-treatment value (P<0.001). In rats treated with morphine plus Mrz 2/579, thresholds remained significantly higher between 10--72 h post-implantation than with morphine alone (P<0.05). In contrast, infusion of the same level of Mrz 2/579 once tolerance had developed did not reverse tolerance. These results indicate that fast NMDA channel blockers such as Mrz 2/579 may prove to be useful in enhancing analgesia to continuous morphine administration.

δ opioid receptor antagonist, ICI 174,864, is suitable for the early treatment of uncontrolled hemorrhagic shock in rats.

PubMed

Liu, Liangming; Tian, Kunlun; Zhu, Yu; Ding, Xiaoli; Li, Tao

2013-08-01

Fluid resuscitation is the essential step for early treatment of traumatic hemorrhagic shock. However, its implementation is greatly limited before hospital or during evacuation. The authors investigated whether δ opioid receptor antagonist ICI 174,864 was suitable for the early treatment of traumatic hemorrhagic shock. With uncontrolled hemorrhagic-shock rats, the antishock effects of six dosages of ICI 174,864 (0.1, 0.3, 0.5, 1, 3, and 5 mg/kg) infused with or without a small volume of lactated Ringer's solution (LR) before bleeding controlled or bleeding cessation at different times were observed. ICI 174,864 (0.1-3 mg/kg) with or without 1/4 volume of LR infusion showed dose-dependent increase in the mean arterial blood pressure, and significantly prolonged the survival time and 8-h survival rate, as compared with ICI 174,864 plus 1/2 volume of LR infusion. The best effect was shown with 3 mg/kg of ICI 174,864. Bleeding cessation at 1, 2, or 3 h during infusion of ICI 174,864 (3 mg/kg) plus 1/4 volume of LR improved subsequent treatment (70% 24-h survival rate vs. 50 and 10% 24-h survival rate in hypotensive resuscitation and LR group, respectively). There was significant improvement in hemodynamic parameters, oxygen delivery, and tissue perfusion of hemorrhagic-shock rats with 3 mg/kg of ICI 174,864 plus 1/4 volume of LR infusion. δ Opioid receptor antagonist ICI 174,864 alone or with small volume of fluid infusion has good beneficial effect on uncontrolled hemorrhagic shock. Its early application can "buy" time for subsequent treatment of traumatic shock.

Divergent Effects of Anandamide Transporter Inhibitors with Different Target Selectivity on Social Play Behavior in Adolescent Rats

PubMed Central

Trezza, Viviana; Vanderschuren, Louk J. M. J.

2009-01-01

The endocannabinoid system plays an important role in the modulation of affect, motivation, and emotion. Social play behavior is a natural reinforcer in adolescent rats, and we have recently shown that interacting endocannabinoid, opioid, and dopamine systems modulate social play. In the present study, we tested the hypothesis that, in contrast to administration of exogenous cannabinoid agonists, increasing local endocannabinoid signaling through anandamide transporter inhibition enhances social play. To this aim, we tested the effects of two anandamide transporter inhibitors with different target selectivity on social play behavior in adolescent rats. Interestingly, we found that the prototypical anandamide transporter inhibitor N-(4-hydroxyphenyl)-arachidonamide (AM404) reduced social play, whereas its more selective analog N-arachidonoyl-(2-methyl-4-hydroxyphenyl)amine (VDM11) enhanced it. The effects of AM404 were not mediated through its known pharmacological targets, since they were not blocked by the CB1 cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A), the CB2 cannabinoid receptor antagonist N-(1,3,3-trimethylbicyclo(2.2.1)heptan-2-yl)-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide (SR144528), or by the transient receptor potential vanilloid 1 receptor antagonist capsazepine. In contrast, the increase in social play induced by VDM11 was dependent on cannabinoid, opioid, and dopaminergic neurotransmission, since it was blocked by the CB1 cannabinoid receptor antagonist SR141716A, the opioid receptor antagonist naloxone, and the dopamine receptor antagonist α-flupenthixol. These findings support the notion that anandamide plays an important role in the modulation of social interaction in adolescent rats, and they suggest that selective anandamide transporter inhibitors might be useful for the treatment of social dysfunctions. Furthermore, these results suggest that off-target effects may be responsible for some of the conflicting effects of anandamide transporter inhibitors on behavior. PMID:18948500

Microdose gonadotropin-releasing hormone agonist flare-up protocol versus multiple dose gonadotropin-releasing hormone antagonist protocol in poor responders undergoing intracytoplasmic sperm injection-embryo transfer cycle.

PubMed

Kahraman, Korhan; Berker, Bulent; Atabekoglu, Cem Somer; Sonmezer, Murat; Cetinkaya, Esra; Aytac, Rusen; Satiroglu, Hakan

2009-06-01

To compare the efficacy of microdose GnRH agonist (GnRH-a) flare-up and multiple dose GnRH antagonist protocols in patients who have a poor response to a long luteal GnRH-a protocol. Prospective, randomized, clinical study. University hospital. Forty-two poor responder patients undergoing intracytoplasmic sperm injection (ICSI)-embryo transfer cycle. Twenty-one patients received microdose leuprolide acetate (LA) (50 microg twice daily) starting on the second day of withdrawal bleeding. The other 21 patients received 0.25 mg of cetrorelix daily when the leading follicle reached 14 mm in diameter. Serum E(2) levels, number of growing follicles and mature oocytes, embryo quality, dose of gonadotropin used, cancellation, fertilization, implantation rate and pregnancy rate (PR). The mean serum E(2) concentration on the day of hCG administration was significantly higher in the microdose GnRH-a group than in the GnRH antagonist group (1,904 vs. 1,362 pg/mL). The clinical PRs per started cycle of microdose GnRH-a and GnRH antagonist groups were 14.2% and 9.5%, respectively. There were no statistically significant differences in the other ovulation induction characteristics, fertilization and implantation rates. Microdose GnRH-a flare-up protocol and multiple dose GnRH antagonist protocol seem to have similar efficacy in improving treatment outcomes of poor responder patients.

A randomized clinical trial of histamine 2 receptor antagonism in treatment-resistant schizophrenia.

PubMed

Meskanen, Katarina; Ekelund, Heidi; Laitinen, Jarmo; Neuvonen, Pertti J; Haukka, Jari; Panula, Pertti; Ekelund, Jesper

2013-08-01

Histamine has important functions as regulator of several other key neurotransmitters. Patients with schizophrenia have lower histamine H1 receptor levels. Since a case report in 1990 of an effect of the H2 antagonist famotidine on negative symptoms in schizophrenia, some open-label trials have been performed, but no randomized controlled trial. Recently, it was shown that clozapine is a full inverse agonist at the H2 receptor. We performed a researcher-initiated, academically financed, double-blind, placebo-controlled, parallel-group, randomized trial with the histamine H2 antagonist famotidine in treatment-resistant schizophrenia. Thirty subjects with schizophrenia were randomized to have either famotidine (100 mg twice daily, n = 16) or placebo (n = 14) orally, added to their normal treatment regimen for 4 weeks. They were followed up weekly with the Scale for the Assessment of Negative Symptoms (SANS), the PANSS (Positive and Negative Syndrome Scale), and Clinical Global Impression (CGI) Scale. In the famotidine group, the SANS score was reduced by 5.3 (SD, 13.1) points, whereas in the placebo group the SANS score was virtually unchanged (mean change, +0.2 [SD, 9.5]). The difference did not reach statistical significance (P = 0.134) in Mann-Whitney U analysis. However, the PANSS Total score and the General subscore as well as the CGI showed significantly (P < 0.05) greater change in the famotidine group than in the placebo group. No significant adverse effects were observed. This is the first placebo-controlled, randomized clinical trial showing a beneficial effect of histamine H2 antagonism in schizophrenia. H2 receptor antagonism may provide a new alternative for the treatment of schizophrenia.

The impact of ranitidine on monocyte responses in the context of solid tumors

PubMed Central

Vila-Leahey, Ava; Rogers, Dakota; Marshall, Jean S.

2016-01-01

Monocytes and myeloid derived suppressor cells (MDSC) have been implicated on the regulation of tumor growth. Histamine is also important for regulating MDSC responses. Oral administration of the H2 receptor antagonist ranitidine can inhibit breast tumor growth and metastasis. In the current study, we examined the impact of oral ranitidine treatment, at a clinically relevant dose, on multiple murine tumor models. The impact of ranitidine on monocyte responses and the role of CCR2 in ranitidine-induced tumor growth inhibition were also investigated. Oral ranitidine treatment did not reduce tumor growth in the B16-F10 melanoma, LLC1 lung cancer and EL4 thymoma models. However, it consistently reduced E0771 primary tumor growth and metastasis in the 4T1 model. Ranitidine had no impact on E0771 tumor growth in mice deficient in CCR2, where monocyte recruitment to tumors was limited. Analysis of splenic monocytes also revealed an elevated ratio of H2 versus H1 expression from tumor-bearing compared with naïve mice. More detailed examination of the role of ranitidine on monocyte development demonstrated a decrease in monocyte progenitor cells following ranitidine treatment. Taken together, these results reveal that H2 signaling may be a novel target to alter the monocyte population in breast tumor models, and that targeting H2 on monocytes via oral ranitidine treatment impacts effective tumor immunity. Ranitidine is widely used for control of gastrointestinal disorders. The potential role of ranitidine as an adjunct to immunotherapies for breast cancer and the potential impact of H2 antagonists on breast cancer outcomes should be considered. PMID:26863636

The impact of ranitidine on monocyte responses in the context of solid tumors.

PubMed

Vila-Leahey, Ava; Rogers, Dakota; Marshall, Jean S

2016-03-08

Monocytes and myeloid derived suppressor cells (MDSC) have been implicated on the regulation of tumor growth. Histamine is also important for regulating MDSC responses. Oral administration of the H2 receptor antagonist ranitidine can inhibit breast tumor growth and metastasis. In the current study, we examined the impact of oral ranitidine treatment, at a clinically relevant dose, on multiple murine tumor models. The impact of ranitidine on monocyte responses and the role of CCR2 in ranitidine-induced tumor growth inhibition were also investigated. Oral ranitidine treatment did not reduce tumor growth in the B16-F10 melanoma, LLC1 lung cancer and EL4 thymoma models. However, it consistently reduced E0771 primary tumor growth and metastasis in the 4T1 model. Ranitidine had no impact on E0771 tumor growth in mice deficient in CCR2, where monocyte recruitment to tumors was limited. Analysis of splenic monocytes also revealed an elevated ratio of H2 versus H1 expression from tumor-bearing compared with naïve mice. More detailed examination of the role of ranitidine on monocyte development demonstrated a decrease in monocyte progenitor cells following ranitidine treatment. Taken together, these results reveal that H2 signaling may be a novel target to alter the monocyte population in breast tumor models, and that targeting H2 on monocytes via oral ranitidine treatment impacts effective tumor immunity. Ranitidine is widely used for control of gastrointestinal disorders. The potential role of ranitidine as an adjunct to immunotherapies for breast cancer and the potential impact of H2 antagonists on breast cancer outcomes should be considered.

JB-9322, a new selective histamine H2-receptor antagonist with potent gastric mucosal protective properties.

PubMed

Palacios, B; Montero, M J; Sevilla, M A; Román, L S

1995-05-01

1. JB-9322 is a selective histamine H2-receptor antagonist with gastric antisecretory activity and mucosal protective properties. 2. The affinity of JB-9322 for the guinea-pig atria histamine H2-receptor was approximately 2 times greater than that of ranitidine. 3. In vivo, the ID50 value for the inhibition of gastric acid secretion in pylorus-ligated rats was 5.28 mg kg-1 intraperitoneally. JB-9322 also dose-dependently inhibited gastric juice volume and pepsin secretion. In gastric lumen-perfused rats, intravenous injection of JB-9322 dose-dependently reduced histamine-, pentagastrin- and carbachol-stimulated gastric acid secretion. 4. JB-9322 showed antiulcer activity against aspirin and indomethacin-induced gastric lesions and was more potent than ranitidine. 5. JB-9322 effectively inhibited macroscopic gastric haemorrhagic lesions induced by ethanol. Intraperitoneal injection was effective in preventing the lesions as well as oral treatment. The oral ID50 value for these lesions was 1.33 mg kg-1. By contrast, ranitidine (50 mg kg-1) failed to reduce these lesions. In addition, the protective effect of JB-9322 was independent of prostaglandin synthesis. 6. These results indicate that JB-9322 is a new antiulcer drug that exerts a potent cytoprotective effect in addition to its gastric antisecretory activity.

Radioligand binding characterization of the bradykinin B(2) receptor in the rabbit and pig ileal smooth muscle.

PubMed

Meini, Stefania; Cucchi, Paola; Catalani, Claudio; Bellucci, Francesca; Santicioli, Paolo; Giuliani, Sandro; Maggi, Carlo Alberto

2010-06-10

Several species-related differences have been reported in kinin B(2) receptor pharmacology. The present study aimed to evaluate the affinity of the bradykinin B(2) receptor antagonist MEN16132 for the rabbit and pig B(2) receptor, and radioligand binding experiments using [(3)H]bradykinin and membranes of rabbit and pig ileum smooth muscle were conducted. The [(3)H]bradykinin binding was characterized by homologous displacement curves indicating K(d) values of 0.65 and 0.33nM in rabbit and pig, respectively. The B(2) receptor specificity of [(3)H]bradykinin binding was shown by the low affinity (>microM) displayed by agonists ([desArg(9)]bradykinin and Lys[desArg(9)]bradykinin) and antagonists [Leu(8),desArg(9)]bradykinin and Lys[Leu(8),desArg(9)]bradykinin) selective for the B(1) receptor. The affinity of MEN16132 and other antagonists was determined by inhibition curves (pK(i) values in the rabbit and pig assay, respectively): MEN16132 (10.4 and 10.3) and peptide compounds such as icatibant (10.1 and 9.9) and MEN11270 (10.3 and 10.1) displayed subnanomolar potency in both assays; the nonpeptide LF16-0687 (8.4 and 8.5) and FR173657 (8.2 and 9.1) exhibited a different affinity pattern, whereas WIN64338 displayed low affinity (5.7 and

beta-Endorphin-induced analgesia is inhibited by synthetic analogs of beta-endorphin.

PubMed

Nicolas, P; Hammonds, R G; Li, C H

1984-05-01

Competitive antagonism of human beta-endorphin (beta h-EP)-induced analgesia by synthetic beta h-EP analogs with high in vitro opiate receptor binding to in vivo analgesic potency ratio has been demonstrated. A parallel shift of the dose-response curve for analgesia to the right was observed when either beta h-EP or [ Trp27 ] -beta h-EP was coinjected with various doses of [Gln8, Gly31 ]-beta h-EP-Gly-Gly-NH2, [Arg9,19,24,28,29]-beta h-EP, or [ Cys11 ,26, Phe27 , Gly31 ]-beta h-EP. It was estimated that the most potent antagonist, [Gln8, Gly31 ]-beta h-EP-Gly-NH2, is at least 200 times more potent than naloxone.

Time-dependent impact of glutamatergic modulators on the promnesiant effect of 5-HT6R blockade on mice recognition memory.

PubMed

Asselot, Rachel; Simon-O'Brien, Emmanuelle; Lebourgeois, Sophie; Nee, Gérald; Delaunay, Virgile; Duchatelle, Pascal; Bouet, Valentine; Dauphin, François

2017-04-01

Selective antagonists at serotonin 5-HT 6 receptors (5-HT 6 R) improve memory performance in rodents and are currently under clinical investigations. If blockade of 5-HT 6 R is known to increase glutamate release, only two studies have so far demonstrated an interaction between 5-HT 6 R and glutamate transmission, but both, using the non-competitive NMDA antagonist MK-801, insensitive to variations of glutamate concentrations. In a place recognition task, we investigated here in mice the role of glutamate transmission in the beneficial effects of 5-HT 6 R blockade (SB-271046). Through the use of increasing intervals (2, 4 and 6h) between acquisition and retrieval, we investigated the time-dependent impact of two different glutamatergic modulators. NMDAR-dependant glutamate transmission (NMDA Receptors) was either blocked by the competitive antagonist at NMDAR, CGS 19755, or potentiated by the glycine transporter type 1 (GlyT1) inhibitor, NFPS. Results showed that neither SB-271046, nor CGS 19755, nor NFPS, alter behavioural performances after short intervals, i.e. when control mice displayed significant memory performances (2h and 4h) (respectively 10, 3, and 0.625mg.kg -1 ). Conversely, with the 6h-interval, a situation in which spontaneous forgetting is observed in control mice, SB-271046 improved recognition memory performances. This beneficial effect was prevented when co-administered with either CGS 19755 or NFPS, which themselves had no effect. Interestingly, a dose-dependent effect was observed with NFPS, with promnesic effect observed at lower dose (0.156mg.kg -1 ) when administrated alone, whereas it did no modify promnesic effect of SB-271046. These results demonstrate that promnesiant effect induced by 5-HT 6 R blockade is sensitive to the competitive blockade of NMDAR and underline the need of a fine adjustment of the inhibition of GlyT1. Overall, our findings support the idea of a complex crosstalk between serotonergic and glutamatergic systems in the promnesic properties of 5-HT 6 R antagonists. Copyright © 2016 Elsevier Ltd. All rights reserved.

Role of effluent organic matter in the photochemical degradation of compounds of wastewater origin.

PubMed

Bodhipaksha, Laleen C; Sharpless, Charles M; Chin, Yu-Ping; MacKay, Allison A

2017-03-01

The photoreactivity of treated wastewater effluent organic matter differs from that of natural organic matter, and the indirect phototransformation rates of micropollutants originating in wastewater are expected to depend on the fractional contribution of wastewater to total stream flow. Photodegradation rates of four common compounds of wastewater origin (sulfamethoxazole, sulfadimethoxine, cimetidine and caffeine) were measured in river water, treated municipal wastewater effluent and mixtures of both to simulate various effluent-stream water mixing conditions that could occur in environmental systems. Compounds were chosen for their unique photodegradation pathways with the photochemically produced reactive intermediates, triplet-state excited organic matter ( 3 OM*), singlet oxygen ( 1 O 2 ), and hydroxyl radicals (OH). For all compounds, higher rates of photodegradation were observed in effluent relative to upstream river water. Sulfamethoxazole degraded primarily via direct photolysis, with some contribution from OH and possibly from carbonate radicals and other unidentified reactive intermediates in effluent-containing samples. Sulfadimethoxine also degraded mainly by direct photolysis, and natural organic matter appeared to inhibit this process to a greater extent than predicted by light screening. In the presence of effluent organic matter, sulfadimethoxine showed additional reactions with OH and 1 O 2 . In all water samples, cimetidine degraded by reaction with 1 O 2 (>95%) and caffeine by reaction with OH (>95%). In river water mixtures, photodegradation rate constants for all compounds increased with increasing fractions of effluent. A conservative mixing model was able to predict reaction rate constants in the case of hydroxyl radical reactions, but it overestimated rate constants in the case of 3 OM* and 1 O 2 pathways. Finally, compound degradation rate constants normalized to the rate of light absorption by water correlated with E 2 /E 3 ratios (sample absorbance at 254 nm divided by sample absorbance at 365 nm), suggesting that organic matter optical properties may hold promise to predict indirect compound photodegradation rates for various effluent mixing ratios. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure of Gremlin-2 in Complex with GDF5 Gives Insight into DAN-Family-Mediated BMP Antagonism.

PubMed

Nolan, Kristof; Kattamuri, Chandramohan; Rankin, Scott A; Read, Randy J; Zorn, Aaron M; Thompson, Thomas B

2016-08-23

The DAN family, including Gremlin-1 and Gremlin-2 (Grem1 and Grem2), represents a large family of secreted BMP (bone morphogenetic protein) antagonists. However, how DAN proteins specifically inhibit BMP signaling has remained elusive. Here, we report the structure of Grem2 bound to GDF5 at 2.9-Å resolution. The structure reveals two Grem2 dimers binding perpendicularly to each GDF5 monomer, resembling an H-like structure. Comparison to the unbound Grem2 structure reveals a dynamic N terminus that undergoes significant transition upon complex formation, leading to simultaneous interaction with the type I and type II receptor motifs on GDF5. Binding studies show that DAN-family members can interact with BMP-type I receptor complexes, whereas Noggin outcompetes the type I receptor for ligand binding. Interestingly, Grem2-GDF5 forms a stable aggregate-like structure in vitro that is not clearly observed for other antagonists, including Noggin and Follistatin. These findings exemplify the structural and functional diversity across the various BMP antagonist families. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Role of 2',6'-dimethyl-l-tyrosine (Dmt) in some opioid lead compounds.

PubMed

Balboni, Gianfranco; Marzola, Erika; Sasaki, Yusuke; Ambo, Akihiro; Marczak, Ewa D; Lazarus, Lawrence H; Salvadori, Severo

2010-08-15

Here we evaluated how the interchange of the amino acids 2',6'-dimethyl-L-tyrosine (Dmt), 2',6'-difluoro-L-tyrosine (Dft), and tyrosine in position 1 can affect the pharmacological characterization of some reference opioid peptides and pseudopeptides. Generally, Dft and Tyr provide analogues with a similar pharmacological profile, despite different pK(a) values. Dmt/Tyr(Dft) replacement gives activity changes depending on the reference opioid in which the modification was made. Whereas, H-Dmt-Tic-Asp *-Bid is a potent and selective delta agonist (MVD, IC(50)=0.12nM); H-Dft-Tic-Asp *-Bid and H-Tyr-Tic-Asp *-Bid are potent and selective delta antagonists (pA(2)=8.95 and 8.85, respectively). When these amino acids are employed in the synthesis of deltorphin B and its Dmt(1) and Dft(1) analogues, the three compounds maintain a very similar delta agonism (MVD, IC(50) 0.32-0.53 nM) with a decrease in selectivity relative to the Dmt(1) analogue. In the less selective H-Dmt-Tic-Gly *-Bid the replacement of Dmt with Dft and Tyr retains the delta agonism but with a decrease in potency. Antagonists containing the Dmt-Tic pharmacophore do not support the exchange of Dmt with Dft or Tyr. Copyright 2010 Elsevier Ltd. All rights reserved.

Structure-activity relationships studies on weakly basic N-arylsulfonylindoles with an antagonistic profile in the 5-HT6 receptor

NASA Astrophysics Data System (ADS)

Mella, Jaime; Villegas, Francisco; Morales-Verdejo, César; Lagos, Carlos F.; Recabarren-Gajardo, Gonzalo

2017-07-01

We recently reported a series of 39 weakly basic N-arylsulfonylindoles as novel 5-HT6 antagonists. Eight of the compounds exhibited moderate to high binding affinities, with 2-(4-(2-Methoxyphenyl)piperazin-1-yl)-1-(1-tosyl-1H-indol-3-yl)ethanol 16 showing the highest binding affinity (pKi = 7.87). Given these encouraging results and as a continuation of our research, we performed an extensive step-by-step search for the best 3D-QSAR model that allows us to rationally propose novel molecules with improved 5-HT6 affinity based on our previously reported series. A comparative molecular similarity indices analysis (CoMSIA) model built on a docking-based alignment was developed, wherein steric, electrostatic, hydrophobic and hydrogen bond properties are correlated with biological activity. The model was validated internally and externally (q2 = 0.721; r2pred = 0.938), and identified the sulfonyl and hydroxyl groups and the piperazine ring among the main regions of the molecules that can be modified to create new 5-HT6 antagonists.

Design, synthesis, and action of oxotremorine-related hybrid-type allosteric modulators of muscarinic acetylcholine receptors.

PubMed

Disingrini, Teresa; Muth, Mathias; Dallanoce, Clelia; Barocelli, Elisabetta; Bertoni, Simona; Kellershohn, Kerstin; Mohr, Klaus; De Amici, Marco; Holzgrabe, Ulrike

2006-01-12

A novel series of muscarinic receptor ligands of the hexamethonio-type was prepared which contained, on one side, the phthalimidopropane or 1,8-naphthalimido-2,2-dimethylpropane moiety typical for subtype selective allosteric antagonists and, on the other, the acetylenic fragment typical for the nonselective orthosteric muscarinic agonists oxotremorine, oxotremorine-M, and related muscarinic agonists. Binding experiments in M(2) receptors using [(3)H]N-methylscopolamine as an orthosteric probe proved an allosteric action of both groups of hybrids, 7a-10a and 8b-10b. The difference in activity between a-group and b-group hybrids corresponded with the activity difference between the allosteric parent compounds. In M(1)-M(3) muscarinic isolated organ preparations, most of the hybrids behaved as subtype selective antagonists. [(35)S]GTPgammaS binding assays using human M(2) receptors overexpressed in CHO cells revealed that a weak intrinsic efficacy was preserved in 8b-10b. Thus, attaching muscarinic allosteric antagonist moieties to orthosteric muscarinic agonists may lead to hybrid compounds in which functions of both components are mixed.