Development and characterization of a potent free fatty acid receptor 1 (FFA1) fluorescent tracer

The free fatty acid receptor 1 (FFA1/GPR40) is a potential target for treatment of type 2 diabetes. Although several potent agonists have been described, there remains a strong need for suitable tracers to interrogate ligand binding to this receptor. We address this by exploring fluorophore-tethering to known potent FFA1 agonists. This led to the development of 4, a high affinity FFA1 tracer with favorable and polarity-dependent fluorescent properties. A close to ideal overlap between the emission spectrum of the NanoLuciferase receptor tag and the excitation spectrum of 4 enabled the establishment of a homogenous BRET-based binding assay suitable for both detailed kinetic studies and high throughput competition binding studies. Using 4 as a tracer demonstrated that the compound acts fully competitively with selected synthetic agonists but not with lauric acid and allowed for the characterization of binding affinities of a diverse selection of known FFA1 agonists, indicating that 4 will be a valuable tool for future studies at FFA1

Carbachol and bradykinin elevate cyclic AMP and rapidly deplete ATP in cultured rat sympathetic neurons

The agonists carbachol (CCh) and bradykinin (BK) and 54 mM KCl (high K+) were among the most potent stimulants of cyclic AMP (cAMP) production in cultured rat sympathetic neurons, measured with the use of a high-fidelity assay developed for small samples. The rise in cAMP evoked by CCh (through muscarinic receptors), BK, and high K+ was inhibited in Ca2(+)-depleted medium (1.3 mM Ca2+ and 2 mM BAPTA or EGTA), which also prevented the sustained rise in [Ca2+]i evoked by each of these stimuli, showing that elevation of cAMP requires extracellular Ca2+ and, possibly, Ca2+ influx. Preliminary results obtained with the novel calmodulin inhibitor CGS 9343B, which blocked the elevation of cAMP, and with the cyclogenase inhibitor indomethacin, which partially blocked the actions of the agonists but not those of high K+, suggest that calmodulin and arachidonate metabolites may be two components of the signaling pathway. In addition to their effects on cAMP metabolism, CCh, muscarine, and BK, but not nicotine, caused a 30-40% decrease in ATP levels. This effect was much greater than that evoked by high K+ and was largely inhibited by CGS 9343B but slightly enhanced in the Ca(+)-depleted medium, showing that agonists are still active in the absence of [Ca2+]o. Thus, agonists that activate phosphoinositide metabolism can also increase cAMP production and substantially deplete cells of ATP. These novel actions may have to be taken into account when the mechanisms by which such agonists regulate cell function are being considered

Beta(2)-adrenergic receptor (ADRB2) gene polymorphisms and risk of COPD exacerbations : the Rotterdam study

The role of the beta(2)-adrenergic receptor (ADRB2) gene in patients with chronic obstructive pulmonary disease (COPD) is unclear. We investigated the association between ADRB2 variants and the risk of exacerbations in COPD patients treated with inhaled beta(2)-agonists. Within the Rotterdam Study, a population-based cohort study, we followed 1053 COPD patients until the first COPD exacerbation or end of follow-up and extracted rs1042713 (16Arg > Gly) and rs1042714 (27Gln > Glu) in ADRB2. Exposure to inhaled beta(2)-agonists was categorized into current, past, or non-use on the index date (date of COPD exacerbation for cases and on the same day of follow-up for controls). COPD exacerbations were defined as acute episodes of worsening symptoms requiring systemic corticosteroids and/or antibiotics (moderate exacerbations), or hospitalization (severe exacerbations). The associations between ADRB2 variants and COPD exacerbations were assessed using Cox proportional hazards models, adjusting for age, sex, use of inhaled corticosteroids, daily dose of beta(2)-agonists, and smoking. In current users of beta(2)-agonists, the risk of COPD exacerbation decreased by 30% (hazard ratio (HR); 0.70, 95% CI: 0.59-0.84) for each copy of the Arg allele of rs1042713 and by 20% (HR; 0.80, 95% CI: 0.69-0.94) for each copy of the Gln allele of rs1042714. Furthermore, current users carrying the Arg16/Gln27 haplotype had a significantly lower risk (HR; 0.70, 95% CI: 0.59-0.85) of COPD exacerbation compared to the Gly16/Glu27 haplotype. In conclusion, we observed that the Arg16/Gln27 haplotype in ADRB2 was associated with a reduced risk of COPD exacerbation in current users of inhaled beta(2)-agonists

Current and Future Issues in the Development of Spinal Agents for the Management of Pain.

Targeting analgesic drugs for spinal delivery reflects the fact that while the conscious experience of pain is mediated supraspinally, input initiated by high intensity stimuli, tissue injury and/or nerve injury is encoded at the level of the spinal dorsal horn and this output informs the brain as to the peripheral environment. This encoding process is subject to strong upregulation resulting in hyperesthetic states and downregulation reducing the ongoing processing of nociceptive stimuli reversing the hyperesthesia and pain processing. The present review addresses the biology of spinal nociceptive processing as relevant to the effects of intrathecally-delivered drugs in altering pain processing following acute stimulation, tissue inflammation/injury and nerve injury. The review covers i) the major classes of spinal agents currently employed as intrathecal analgesics (opioid agonists, alpha 2 agonists; sodium channel blockers; calcium channel blockers; NMDA blockers; GABA A/B agonists; COX inhibitors; ii) ongoing developments in the pharmacology of spinal therapeutics focusing on less studied agents/targets (cholinesterase inhibition; Adenosine agonists; iii) novel intrathecal targeting methodologies including gene-based approaches (viral vectors, plasmids, interfering RNAs); antisense, and toxins (botulinum toxins; resniferatoxin, substance P Saporin); and iv) issues relevant to intrathecal drug delivery (neuraxial drug distribution), infusate delivery profile, drug dosing, formulation and principals involved in the preclinical evaluation of intrathecal drug safety

Histamine stimulates the proliferation of small and large cholangiocytes by activation of both IP3/Ca2+ and cAMP-dependent signaling mechanisms

Although large cholangiocytes exert their functions by activation of cyclic adenosine 3',5'-monophosphate (cAMP), Ca(2+)-dependent signaling regulates the function of small cholangiocytes. Histamine interacts with four receptors, H1-H4HRs. H1HR acts by Gαq activating IP(3)/Ca(2+), whereas H2HR activates Gα(s) stimulating cAMP. We hypothesize that histamine increases biliary growth by activating H1HR on small and H2HR on large cholangiocytes. The expression of H1-H4HRs was evaluated in liver sections, isolated and cultured (normal rat intrahepatic cholangiocyte culture (NRIC)) cholangiocytes. In vivo, normal rats were treated with histamine or H1-H4HR agonists for 1 week. We evaluated: (1) intrahepatic bile duct mass (IBDM); (2) the effects of histamine, H1HR or H2HR agonists on NRIC proliferation, IP(3) and cAMP levels and PKCα and protein kinase A (PKA) phosphorylation; and (3) PKCα silencing on H1HR-stimulated NRIC proliferation. Small and large cholangiocytes express H1-H4HRs. Histamine and the H1HR agonist increased small IBDM, whereas histamine and the H2HR agonist increased large IBDM. H1HR agonists stimulated IP(3) levels, as well as PKCα phosphorylation and NRIC proliferation, whereas H2HR agonists increased cAMP levels, as well as PKA phosphorylation and NRIC proliferation. The H1HR agonist did not increase proliferation in PKCα siRNA-transfected NRICs. The activation of differential signaling mechanisms targeting small and large cholangiocytes is important for repopulation of the biliary epithelium during pathologies affecting different-sized bile ducts

The melanocortin receptors and their accessory proteins.

The five melanocortin receptors (MCRs) named MC1R-MC5R have diverse physiological roles encompassing pigmentation, steroidogenesis, energy homeostasis and feeding behavior as well as exocrine function. Since their identification almost 20 years ago much has been learnt about these receptors. As well as interacting with their endogenous ligands the melanocortin peptides, there is now a growing list of important peptides that can modulate the way these receptors signal, acting as agonists, antagonists, and inverse agonists. The discovery of melanocortin 2 receptor accessory proteins as a novel accessory factor to the MCRs provides further insight into the regulation of these important G protein-coupled receptor

Quinolones modulate ghrelin receptor signaling: potential for a novel small molecule scaffold in the treatment of cachexia

Cachexia is a metabolic wasting disorder characterized by progressive weight loss, muscle atrophy, fatigue, weakness, and appetite loss. Cachexia is associated with almost all major chronic illnesses including cancer, heart failure, obstructive pulmonary disease, and kidney disease and significantly impedes treatment outcome and therapy tolerance, reducing physical function and increasing mortality. Current cachexia treatments are limited and new pharmacological strategies are needed. Agonists for the growth hormone secretagogue (GHS-R1a), or ghrelin receptor, prospectively regulate the central regulation of appetite and growth hormone secretion, and therefore have tremendous potential as cachexia therapeutics. Non-peptide GHS-R1a agonists are of particular interest, especially given the high gastrointestinal degradation of peptide-based structures, including that of the endogenous ligand, ghrelin, which has a half-life of only 30 min. However, few compounds have been reported in the literature as non-peptide GHS-R1a agonists. In this paper, we investigate the in vitro potential of quinolone compounds to modulate the GHS-R1a in both transfected human cells and mouse hypothalamic cells. These chemically synthesized compounds demonstrate a promising potential as GHS-R1a agonists, shown by an increased intracellular calcium influx. Further studies are now warranted to substantiate and exploit the potential of these novel quinolone-based compounds as orexigenic therapeutics in conditions of cachexia and other metabolic and eating disorders.Irish Research Council for Science and Technology (IRCSET)Science Foundation Ireland (SFI/12/IP/1315)Science Foundation Ireland (SFI/12/RC/2275)Science Foundation Ireland (SFI/12/RC/2273)Universidad de Sevill

A meta-analysis and systematic review of randomized controlled trials with degarelix versus gonadotropin-releasing hormone agonists for advanced prostate cancer

Our aim was to systematically evaluate the benefits of degarelix as antagonist versus agonists of gonadotropin-releasing hormones (GnRH) for the treatment of advanced prostate cancer (PC). This comparison was performed either in terms of biochemical or oncological or safety profiles. To this end we, carried out a systematic review and meta-analysis of the literature.We selected only studies directly and prospectively analyzing the two treatments in the same population (randomized phase III studies). We followed the Preferred Reporting Items for Systematic Reviews and meta-analyses process for reporting studies.After we eliminated studies according to the exclusion criteria, 9 publications were considered relevant to this review. These articles described 5 clinical trials that were eligible for inclusion. The follow-up duration in all trials did not exceed 364 days. This meta-analysis and review comprised a total of 1719 men, 1061 randomized to degarelix versus 658 to GnRH agonists treatment for advanced PC. Oncological results were evaluated only in 1 trial (CS21:408 cases) and they were not the primary endpoints of the study. Treatment emerging adverse events were reported in 61.4% and 58.8% of patients in the degarelix and GnRH agonists group, respectively (odds ratio, OR = 1.17; 95% confidence interval, 95% CI: 0.78-1.77, P > 0.1). Treatment related severe cardiovascular side effects were reported (trial CS21-30-35) in 1.6% and 3.6% of patients in the degarelix and GnRH agonists group, respectively (OR = 0.55, 95% CI: 0.26-1.14, P > 0.1).Our analysis evidences relevant limitations in particular for the comparative evaluation of the efficacy and the oncological results related to degarelix

Nebulized PPARγ agonists: a novel approach to augment neonatal lung maturation and injury repair in rats.

BackgroundBy stimulating lipofibroblast maturation, parenterally administered peroxisome proliferator-activated receptor γ (PPARγ) agonists promote lung homeostasis and injury repair in the neonatal lung. In this study, we determined whether PPARγ agonists could be delivered effectively via nebulization to neonates, and whether this approach would also protect against hyperoxia-induced lung injury.MethodsOne-day old Sprague-Dawley rat pups were administered PPARγ agonists rosiglitazone (RGZ, 3 mg/kg), pioglitazone (PGZ, 3 mg/kg), or the diluent, via nebulization every 24 h; animals were exposed to 21% or 95% O2 for up to 72 h. Twenty-four and 72 h following initial nebulization, the pups were sacrificed for lung tissue and blood collection to determine markers of lung maturation, injury repair, and RGZ and PGZ plasma levels.ResultsNebulized RGZ and PGZ enhanced lung maturation in both males and females, as evidenced by the increased expression of markers of alveolar epithelial and mesenchymal maturation. This approach also protected against hyperoxia-induced lung injury, since hyperoxia-induced changes in bronchoalveolar lavage cell and protein contents and lung injury markers were all blocked by nebulized PGZ.ConclusionNebulized PPARγ agonist administration promotes lung maturation and prevents neonatal hyperoxia-induced lung injury in both males and females

Bitter Taste Receptors for Asthma Therapeutics.

Clinical management of asthma and chronic obstructive pulmonary disease (COPD) has primarily relied on the use of beta 2 adrenergic receptor agonists (bronchodilators) and corticosteroids, and more recently, monoclonal antibody therapies (biologics) targeting specific cytokines and their functions. Although these approaches provide relief from exacerbations, questions remain on their long-term efficacy and safety. Furthermore, current therapeutics do not address progressive airway remodeling (AR), a key pathological feature of severe obstructive lung disease. Strikingly, agonists of the bitter taste receptors (TAS2Rs) deliver robust bronchodilation, curtail allergen-induced inflammatory responses in the airways and regulate airway smooth muscle (ASM) cell proliferation and mitigate features of A