A novel excisional wound pain model for evaluation of analgesics in rats.

BACKGROUND: Management of pain from open wounds is a growing unmet healthcare need. However, the models available to study pain from wounds or to develop analgesics for the patients suffering from them have primarily relied on incisional models. Here, we present the first characterized and validated model of open wound pain. METHODS: Unilateral full-skin excisional punch biopsy wounds on rat hind paws were evaluated for evoked pain using withdrawal responses to mechanical and thermal stimulation, and spontaneous pain was measured using hind paw weight distribution and guarding behavior. Evaluations were done before wounding (baseline) and 2-96 hours post-wounding. The model was validated by testing the effects of buprenorphine and carprofen. RESULTS: Pain responses to all tests increased within 2 hours post-wounding and were sustained for at least 4 days. Buprenorphine caused a reversal of all four pain responses at 1 and 4 hours post-treatment compared to 0.9% saline (P < 0.001). Carprofen decreased the pain response to thermal stimulation at 1 (P ≤ 0.049) and 4 hours (P < 0.011) post-treatment compared to 0.9% saline, but not to mechanical stimulation. CONCLUSIONS: This is the first well-characterized and validated model of pain from open wounds and will allow study of the pathophysiology of pain in open wounds and the development of wound-specific analgesics. Key Words.

The Sight Loss and Vision Priority Setting Partnership (SLV-PSP): overview and results of the research prioritisation survey process.

OBJECTIVES: The Sight Loss and Vision Priority Setting Partnership aimed to identify research priorities relating to sight loss and vision through consultation with patients, carers and clinicians. These priorities can be used to inform funding bodies' decisions and enhance the case for additional research funding. DESIGN: Prospective survey with support from the James Lind Alliance. SETTING: UK-wide National Health Service (NHS) and non-NHS. PARTICIPANTS: Patients, carers and eye health professionals. Academic researchers were excluded solely from the prioritisation process. The survey was disseminated by patient groups, professional bodies, at conferences and through the media, and was available for completion online, by phone, by post and by alternative formats (Braille and audio). OUTCOME MEASURE: People were asked to submit the questions about prevention, diagnosis and treatment of sight loss and eye conditions that they most wanted to see answered by research. Returned survey questions were reviewed by a data assessment group. Priorities were established across eye disease categories at final workshops. RESULTS: 2220 people responded generating 4461 submissions. Sixty-five per cent of respondents had sight loss and/or an eye condition. Following initial data analysis, 686 submissions remained which were circulated for interim prioritisation (excluding cataract and ocular cancer questions) to 446 patients/carers and 218 professionals. The remaining 346 questions were discussed at final prioritisation workshops to reach agreement of top questions per category. CONCLUSIONS: The exercise engaged a diverse community of stakeholders generating a wide range of conditions and research questions. Top priority questions were established across 12 eye disease categories.

For the love of paradox: from neurobiology to pharmacology.

The acute and chronic effects of certain drugs can often be opposite. For example, in congestive heart failure acute administration of ß-adrenoceptor agonists results in beneficial improvement in symptoms of the disease, but their chronic use increases mortality. Conversely, certain ß-adrenoceptor antagonists/inverse agonists (ß-blockers) initially cause a detrimental response by decreasing cardiac contractility in congestive heart failure, whereas chronic treatment with the same ß-blockers improves contractility and survival. Furthermore, this time-dependent reversal of outcomes occurs in nonpharmacological interventions, such as exercise, and can even be observed in the response of plants to pruning or other stressors, with the results being a different short-term versus long-term effect. Here, we review some of these phenomena with a special emphasis on the temporal dissociation of pharmacological effects. Although Francis Colpaert used this knowledge to lead a drug discovery project for an analgesic compound that initially produced hyperalgesia, we focused on examples outside the central nervous system.

GW627368X ((N-{2-[4-(4,9-diethoxy-1-oxo-1,3-dihydro-2H-benzo[f]isoindol-2-yl)phenyl]acetyl} benzene sulphonamide): a novel, potent and selective prostanoid EP4 receptor antagonist.

1. N-{2-[4-(4,9-diethoxy-1-oxo-1,3-dihydro-2H-benzo[f]isoindol-2-yl)phenyl]acetyl}benzene sulphonamide (GW627368X) is a novel, potent and selective competitive antagonist of prostanoid EP4 receptors with additional human TP receptor affinity. 2. At recombinant human prostanoid EP4 receptors expressed in HEK293 cells, GW627368X produced parallel rightward shifts of PGE2 concentration-effect (E/[A]) curves resulting in an affinity (pKb) estimate of 7.9 +/- 0.4 and a Schild slpoe not significantly different from unity. The affinity was independent of the agonist used. 4. In rings of phenylephrine precontracted piglet saphenous vein, GW627368X (30-300 nM) produced parallel rightward displacement of PGE2 E/[A] curves (pKb = 9.2 +/- 0.2; slope = 1). 4. GW627368X appears to bind to human prostanoid TP receptors but not the TP receptors of other species. In human washed platelets, GW627368X (10 microM) produced 100% inhibition of U-46619 (EC100)-induced aggregation (approximate pA2 approximately 7.0). However, in rings of rabbit and piglet saphenous vein and of guinea-pig aorta GW627368X (10 microM) did not displace U-46619 E/[A] curves indicating an affinity of < 5.0 for rabbit and guinea-pig prostanoid TP receptors. 5. In functional assays GW627368X is devoid of both agonism and antagonist affinity for prostanoid CRTH2, EP2, EP3, IP and FP receptors. At prostanoid EP1 receptors, GW627368X was an antagonist with a pA2 of 6.0, and at prostanoid IP receptors the compound increased the maximum effect of iloprost by 55%. At rabbit prostanoid EP2 receptors the pA2 of GW627368X was < 5.0. 6. In competition radioligand bioassays, GW627368X had affinity for human prostanoid EP4 and TP receptors (pKi = 7.0 +/- 0.2 (n = 10) and 6.8 (n = 2), respectively). Affinity for all other human prostanoid receptors was < 5.3. 7. GW627368X will be a valuable tool to explore the role of the prostanoid EP4 receptor in many physiological and pathological settings.

Piglet saphenous vein contains multiple relaxatory prostanoid receptors: evidence for EP4, EP2, DP and IP receptor subtypes.

Prostaglandin E(2) produced endothelium-independent relaxation of phenylephrine- and 5-HT-contracted piglet saphenous vein (PSV; pEC(50)=8.6+/-0.2; n=6). The prostanoid EP(4) receptor antagonist GW627368X (30-300 nM) produced parallel rightward displacement of PGE(2) concentration-effect (E/[A]) curves (pK(b)=9.2+/-0.2; slope=1). Higher concentrations of GW627368X did not produce further rightward shifts, revealing the presence of non-EP(4) prostanoid receptors. In all, 18 other prostanoid receptor agonists relaxed PSV in a concentration-related manner. Relative potencies of agonists most sensitive to 10 muM GW627368X (and therefore predominantly activating EP(4) receptors) correlated well with those at human recombinant EP(4) receptors in human embryonic kidney (HEK-293) cells (r(2)=0.74). In the presence of 10 microM GW627368X, the rank order of agonist relative potency matched that of the human recombinant EP(2) receptor in Chinese hamster ovary cells (r(2)=0.72). Iloprost, cicaprost and PGI(2) relaxed PSV maximally and were antagonised by 10 microM GW627368X, demonstrating that they were full EP(4) receptor agonists. Residual responses to these compounds in the presence of GW627368X suggested the presence of IP receptors.BW245C relaxed PSV maximally (pEC(50)=6.8+/-0.1). In the presence of 10 microM GW627368X, BW245C produced biphasic E/[A] curves (phase one pEC(50)=6.6; alpha=24%; phase two pEC(50)=5.1; alpha=112%). Phase two was antagonised by the DP receptor antagonist BW A868C (1 microM), demonstrating that BW245C is an agonist at DP and EP4 receptors. We conclude that PSV contains EP(4), EP(2), DP and IP receptors; IP receptor agonists are also porcine EP(4) receptor agonists.

Functional pharmacology of human prostanoid EP2 and EP4 receptors.

Prostanoid EP(2) and EP(4) receptor-mediated responses are difficult to distinguish pharmacologically because of the lack of potent, selective antagonists. We describe systematic agonist fingerprints for recombinant human prostanoid EP(2) and EP(4) receptors expressed in CHO and HEK293 cells, respectively. The rank orders of potency of endogenous prostaglandins were: prostanoid EP(2) receptors: prostaglandin E(2)>>prostaglandin D(2)=prostaglandin F(2alpha)>prostaglandin I(2); prostanoid EP(4) receptors: prostaglandin E(2)>>prostaglandin I(2)>prostaglandin D(2)=prostaglandin F(2alpha). Butaprost free acid (9-oxo-11alpha,16R-dihydroxy-17-cyclobutyl-prost-13E-en-1-oic acid) behaved as a highly selective partial agonist at prostanoid EP(2) receptors while butaprost methyl ester elicited small, low potency responses. The prostanoid EP(1) and EP(3) receptor agonists misoprostol (9-oxo-11alpha,16-dihydroxy-16-methyl-prost-13E-en-1-oic acid, methyl ester), sulprostone (N-(methylsulphonyl)-9-oxo-11alpha,15R-dihydroxy-16-phenoxy-17,18,19,20-tetranor-prosta-5Z,13E-dien-1-amide), and GR63799X ([1R-[1alpha(Z),2beta(R*),3alpha]-(-)-4-benzoylamino)phenyl-7-[3-hydroxy-3-phenoxy-propoxy)-5-oxocyclopentyl]-4-heptenoate), and the prostanoid DP receptor agonist BW245C ((4S)-(3-[(3R,S)-3-cyclohexyl-3-hydropropyl]-2,5-dioxo)-4-imidazolidineheptanoic acid), activated both prostanoid EP(2) and EP(4) receptors. Prostaglandin I(2), iloprost (6,9alpha-methylene-11alpha,15S-dihydroxy-16-methyl-prosta-5E,13E-dien-18-yn-1-oic acid, trometamol salt) and cicaprost (5-[(E)-(1S, 5S, 6S, 7R)-7-hydroxy-6-[(3S, 4S)-3-hydroxy-4-methylnona-1,6-diinyl]-bicyclo[3.3.0]octan-3-yliden]-3-oxapentanoic acid; ZK96480) were full agonists at prostanoid EP(4) receptors. Key differentiating agonists are: butaprost FA, 16,16-dimethyl-prostaglandin E(2), 19-(R)-hydroxy prostaglandin E(2), misoprostol, BW245C, prostaglandin F(2alpha) and prostaglandin D(2).

Effects of acute and chronic administration of beta-adrenoceptor ligands on airway function in a murine model of asthma.

The clinical effects of treatment with beta-adrenoceptor (beta-AR) agonists and antagonists in heart failure vary with duration of therapy, as do the effects of beta-AR agonists in asthma. Therefore, we hypothesized that chronic effects of "beta-blockers" in asthma may differ from those observed acutely. We tested this hypothesis in an antigen (ovalbumin)-driven murine model of asthma. Airway resistance responses (Raw) to the muscarinic agonist methacholine were measured by using the forced oscillation technique. In comparison with nontreated asthmatic mice, we observed that: (i) The beta-AR antagonists nadolol or carvedilol, given as a single i.v. injection (acute treatment) 15 min before methacholine, increased methacholine-elicited peak Raw values by 33.7% and 67.7% (P < 0.05), respectively; when either drug was administered for 28 days (chronic treatment), the peak Raw values were decreased by 43% (P < 0.05) and 22.9% (P < 0.05), respectively. (ii) Chronic treatment with nadolol or carvedilol significantly increased beta-AR densities in lung membranes by 719% and 828%, respectively. (iii) Alprenolol, a beta-blocker with partial agonist properties at beta-ARs, behaved as a beta-AR agonist, and acutely reduced peak Raw value by 75.7% (P < 0.05); chronically, it did not alter Raw. (iv) Salbutamol, a beta-AR partial agonist, acutely decreased peak Raw by 41.1%; chronically, it did not alter Raw. (v) None of the beta-blockers produced significant changes in eosinophil number recovered in bronchoalveolar lavage. These results suggest that beta-AR agonists and beta-blockers with inverse agonist properties may exert reciprocating effects on cellular signaling dependent on duration of administration.

Effects of different beta adrenoceptor ligands in mice with permanent occlusion of the left anterior descending coronary artery.

1. We have studied the effects of three betaAR ligands (carvedilol, alprenolol, and ICI-118551) with different pharmacological profiles and negative efficacy at the beta2AR on cardiac in vivo, in vitro, biochemical and gene expression parameters in mice with permanent occlusion of the left anterior descending coronary artery. 2. Cardiac in vivo parameters were determined using Doppler studies. Mitral-wave E peak velocity (EPV) and aortic peak velocity (AoPV) decreased in the first 2 weeks postocclusion. After 3 weeks of drug treatment, EPV was improved in the carvedilol group to preocclusion values; however, a further reduction in EPV in the alprenolol and control permanent occlusion group was measured and there was no change after ICI-118551 treatment. AoPV was unchanged between weeks 2 and 5 in all groups. 3. The left atria were isolated to record isometric tension responses to isoprenaline. Permanent occlusion significantly reduced the maximum isoprenaline response to 30% of control and carvedilol increased the maximum response to isoprenaline significantly to 60%. 4. The biochemical and gene expression studies revealed different effects of the three betaAR ligands. Most notably, carvedilol reduced gene expression of myosin heavy chain beta. 5. These results indicate that chronic treatment with carvedilol is beneficial in a mouse model of myocardial damage resulting from ischaemia. We hypothesise that these beneficial effects of the drug may be because of the negative efficacy at the beta2AR, combined with beta1AR antagonism.