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Heterocycle-fused azepines are discussed as potent 5-HT 2C receptor agonists with excellent selectivity over 5-HT 2B agonism. Synthesis and structure activity relationships are outlined for a series of bicyclic pyridazino[3,4- d ]azepines. By comparison with earlier published work, in vitro assays predict a high probability for achieving CNS penetration for a potent and selective compound 15a , a pre-requisite to achieve in vivo efficacy. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: In patients with detrusor hyperreflexia, intravesical instillation of ice-cold water results in the development of involuntary bladder contractions at volumes less than normal cystometric capacity. This is referred to as a positive ice-water test (+IWT) and can be reversed by vanilloid receptor agonists and potentiated by menthol. The present study was designed to investigate the existence of an analogous cooling reflex in the guinea-pig bladder that could be used as a small animal model in order to test the effects of drugs on the reflex. Methods: Bladder pressure and external urethral sphincter electromyogram (EUS EMG) were recorded in α-chloralose/urethane anaesthetised guinea-pigs during rapid infusion of cold or warm saline into the bladder with or without prior intravesical exposure to menthol or resiniferatoxin (RTX). Results: The mean control micturition threshold volume (TV) of 2.58 ml at 38 °C was reduced to 1.52 ml in response to saline infusion at 3 °C (P =0.001). The cold-induced reduction in TV was reproducible during several subsequent repeat infusions at 38 °C and 3 °C and was accompanied by decreases in bladder voiding pressure. The duration of the micturition reflex was markedly increased following cold compared with warm saline infusion (mean 24.5 s at 3 °C, 10.2 s at 38 °C, P =0.001) and was associated with oscillations in bladder pressure and concomitant bursting activity in the EUS EMG. During step-wise decreases in infusate temperature from 38 °C to 23 °C, 15 °C, 7 °C and 3 °C, the threshold infusate temperature to elicit a significant reduction in TV was 15 °C. The reduction in TV at 3 °C was potentiated by intravesical infusion of 0.6 mM menthol whilst intravesical infusion of 500 nM RTX reversed the reduction in TV at 3 °C. Discussion: These data suggest that a bladder-cooling reflex is present in the anaesthetised guinea-pig and represents a useful small animal model of the clinical +IWT. [Copyright &y& Elsevier]

Abstract: Central and peripheral 5-hydroxytryptamine (5-HT) receptors play a critical role in the regulation of micturition. Bolus doses of 5-HT2A/2C receptor agonists have been shown to activate the external urethral sphincter (EUS) and to inhibit micturition. This study was designed to determine the contribution of these two 5-HT receptor subtypes to activation of the EUS and inhibition of micturition utilising pharmacokinetic knowledge to better control drug exposure. Recordings of urethral and bladder pressure, EUS-Electromyogram (EMG), the micturition reflex induced by bladder filling, blood pressure and heart rate were made in anaesthetized female rats. The effects of intravenous (i.v.) infusions of the 5-HT2 receptor agonist (2S)-1-(6-chloro-5-fluoroindol-1-yl)propan-2-amine fumarate (Ro 60-0175) in the absence or presence of the selective 5-HT2C receptor antagonist 6-chloro-5-methyl-N-[6-(2-methylpyridin-3-yl)oxypyridin-3-yl]-2,3-dihydroindole-1-carboxamide dihydrochloride (SB 242084) or 5-HT2A receptor antagonist (R)-(2,3-dimethoxyphenyl)-[1-[2-(4-fluorophenyl)ethyl]piperidin-4-yl]methanol (MDL-100,907) were studied on these variables. Continuous infusion of increasing concentrations of Ro 60-0175 only evoked EUS-EMG activity at the highest concentration, which was blocked by co-infusion of MDL-100,907 but not SB 242084. Urethral pressure was unaffected by any drug infusion. Ro 60-0175 at the lowest concentration inhibited the micturition reflex but as the concentration increased this was reversed to facilitation. SB 242084 blocked the inhibition while MDL-100,907 blocked the excitation. Activation of 5-HT2A not 5-HT2C receptors evoked EUS-EMG activity. In conclusion, 5-HT2A receptor activation facilitated the micturition reflex and evoked EUS-EMG while 5-HT2C receptor activation only inhibited the micturition reflex. [Copyright &y& Elsevier]

Abstract: Novel 2-imidazoles have been identified as potent partial agonists of the α1A adrenergic receptor, with good selectivity over the α1B, α1D and α2A receptor sub-types. Sulfonamide 23 possessed attractive drug-like properties with respect to physicochemical and ADME properties and wide ligand selectivity. [Copyright &y& Elsevier]

Abstract: Micturition is largely controlled by Barrington''s nucleus in the dorsolateral tegmentum of the pons. This nucleus coordinates simultaneous bladder contraction and external urethral sphincter relaxation, by means of a specific pattern of projections to the lumbosacral spinal cord. The most widely used small animal model in neurourological research is the rat. However, urodynamic studies suggest that, in sharp comparison to rat, guinea pig micturition is very similar to human micturition. Therefore, the present study, using retrograde and anterograde tracing and double immunofluorescence, was designed to investigate the location of Barrington''s nucleus in the guinea pig, to identify Barrington''s nucleus projections to the spinal cord and to clarify the relationship of Barrington''s nucleus to pontine noradrenergic cell groups. Results show that Barrington''s nucleus is located in the dorsolateral pons, projects to the intermediolateral and intermediomedial cell groups of the lumbosacral spinal cord and is clearly distinct from the pontine noradrenergic cell groups. These results show that the neuroanatomical circuitry in the spinal cord and brainstem that controls micturition in the guinea pig is similar to that in rat. This means that the differences between rat and guinea pig micturition on a behavioral level are not the result of different neuroanatomical connections in these parts of the central nervous system. These results provide a neuroanatomical basis for further neurourological studies in guinea pig. [Copyright &y& Elsevier]

The development of G protein-biased agonists for the μ-opioid receptor (MOR) offers a clear drug discovery rationale for improved analgesia and reduced side-effects of opiate pharmacotherapy. However, our understanding of the molecular mechanisms governing ligand bias is limited, which hinders our ability to rationally design biased compounds. We have investigated the role of MOR binding site residues W320 and Y328 in controlling bias, by receptor mutagenesis. The pharmacology of a panel of ligands in a cAMP and a β-arrestin2 assay were compared between the wildtype and mutated receptors, with bias factors calculated by operational analysis using ΔΔlog(τ/K A ) values. [ 3 H]diprenorphine competition binding was used to estimate affinity changes. Introducing the mutations W320A and Y328F caused changes in pathway bias, with different patterns of change between ligands. For example, DAMGO increased relative β-arrestin2 activity at the W320A mutant, whilst its β-arrestin2 response was completely lost at Y328F. In contrast, endomorphin-1 gained activity with Y328F but lost activity at W320A, in both pathways. For endomorphin-2 there was a directional shift from cAMP bias at the wildtype towards more β-arrestin2 bias at W320A. We also observe clear uncoupling between mutation-driven changes in function and binding affinity. These findings suggest that the mutations influenced the balance of pathway activation in a ligand-specific manner, thus identifying residues in the MOR binding pocket that govern ligand bias. This increases our understanding of how ligand/receptor binding interactions can be translated into agonist-specific pathway activation. [ABSTRACT FROM AUTHOR]

Patients with overactive bladder often exhibit abnormal bladder contractions in response to intravesical cold saline (positive ice-water test). The molecular entity involved in cold sensation within the urinary bladder is unknown, but a potential candidate is the ion channel, transient receptor potential (melastatin)-8 (TRPM8). The objective of the present study was to investigate the role of TRPM8 in a bladder-cooling reflex evoked in anaesthetised guinea-pigs that is comparable to the positive ice-water test seen in patients. Guinea-pig TRPM8 was cloned from L6 dorsal root ganglia (DRG) and expressed in HEK293 cells. Functional agonist- and cold-induced Ca 2+ influx and electrophysiology assays were performed in these cells, and for comparison in HEK293 cells expressing human TRPM8, using a novel TRPM8 antagonist, the S-enantiomer of 1-phenylethyl 4-(benzyloxy)-3-methoxybenzyl (2-aminoethyl) carbamate hydrochloride (PBMC). Potency data from these assays was used to calculate intravenous infusion protocols for targeted plasma concentrations of PBMC in studies on micturition reflexes evoked by intravesical infusion of menthol or cold saline in anaesthetised guinea-pigs. Tissue expression of TRPM8 in guinea-pig bladder, urethra and in dorsal root ganglia neurones traced from the bladder was also investigated. TRPM8 mRNA and protein were detected in L6 dorsal root ganglia, bladder urothelium and smooth muscle. PBMC antagonised in vitro activation of human and guinea-pig TRPM8 and reversed menthol and cold-induced facilitation of the micturition reflex at plasma concentrations consistent with in vitro potencies. The present data suggest that the bladder-cooling reflex in the guinea-pig involves TRPM8. The potential significance of TRPM8 in bladder disease states deserves future investigation. [ABSTRACT FROM AUTHOR]

Abstract: A new series of 2-(benzyloxy)benzamides are presented that are potent functional antagonists of TRPM8 and possess improved LipE and LE compared to the original lead. They were discovered through a series of compound libraries and we present a powerful visualization method for the chemical space explored with each library. Remarkably this new series originated from the highest risk design strategy where compounds were synthesised with the least degree of similarity to the lead structure. [Copyright &y& Elsevier]

Abstract: Small peptidic kappa agonists were covalently linked to the reactive lysine of the CovX antibody to create compounds having potent activity at the kappa receptor with greatly extended half-life when compared to the parent peptide as exemplified by compound 20. [Copyright &y& Elsevier]

Abstract: New pyrimido[4,5-d]azepines 7 are disclosed as potent 5-HT2C receptor agonists. A preferred example, 7b had minimal activation at either the 5-HT2A or 5-HT2B receptors combined with robust efficacy in a preclinical canine model of stress urinary incontinence (SUI) and attractive pharmacokinetic and safety properties. Based on this profile, 7b (PF-3246799) was identified as a candidate for clinical development for the treatment of SUI. In addition, it proved to be critical to build an understanding of the translation between recombinant cell-based systems, native tissue preparations and in vivo preclinical models. This was a significant undertaking and proved to be crucial in compound selection. [Copyright &y& Elsevier]

Abstract: The SAR of a series of pyridazinone derived 5-HT2C agonists has been explored and resulted in identification of a compound with excellent levels of 5-HT2C functional agonism and selectivity over 5-HT2A and 5-HT2B. This compound displayed good in vivo efficacy in pre-clinical models of stress urinary incontinence, despite having physiochemical properties commensurate with impaired CNS penetration. [Copyright &y& Elsevier]

Abstract: This Letter reports the design and synthesis of several novel series of piperazinyl pyrimidinones as 5-HT2C agonists. Several of the compounds presented exhibit good in vitro potency and selectivity over the closely related 5-HT2A and 5-HT2B receptors. Compound 11 was active in in vivo models of stress urinary incontinence. [Copyright &y& Elsevier]

Abstract: A range of heterocycle fused azepines were synthesized in order to find a CNS penetrant, selective 5-HT2C agonist for the treatment of incontinence. The pyridazo-azepines such as compound 11 were shown to be potent 5-HT2C agonists and have potential for CNS penetration and good in vitro ADME properties but lacked selectivity against 5-HT2B. Fusing a further heterocycle gave the selective triazolopyrimido-azepines. An example of this series, compound 36, was shown to be potent, selective, metabolically stable in vitro and efficacious in an in vivo model of stress urinary incontinence. [Copyright &y& Elsevier]

Abstract: A novel series of central nervous system (CNS) penetrant indane 2-imidazoles have been identified as potent, partial agonists of the α1A adrenergic receptor, having good selectivity over the α1B, α1D and α2 sub-types. A key structural motif to impart selectivity is a methylene spacer between the indane and a pendant substituent, which includes heterocycles, sulphones and ethers. Introduction of an ortho-halogen to this group led to a lowering of intrinsic efficacy (E max). [Copyright &y& Elsevier]