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Based on the diverse array of anaesthetic structures, a single anaesthetic target site seems unlikely. With the knowledge that anaesthesia likely results from central nervous system depression, it can be hypothesized that anaesthesia results from either enhanced inhibitory transmission or reduced excitatory transmission. Two main targets have been extensively described: GABA A receptors and N-methyl-d-aspartate (NMDA) glutamate receptors. On γ-aminobutyric acid (GABA) binding to GABA A receptors, an influx of Cl − results to produce hyperpolarization. With the exception of ketamine, xenon and nitrous oxide, all anaesthetic agents potentiate GABA-mediated conductance. On binding of the main excitatory transmitter glutamate, NMDA receptors gate an influx of Ca 2+ and Na + . Ketamine, xenon and nitrous oxide inhibit this ion movement to depress excitatory transmission.

Opioids such as morphine—acting at the mu opioid receptor—are the mainstay for treatment of moderate to severe pain and have good efficacy in these indications. However, these drugs produce a plethora of unwanted adverse effects including respiratory depression, constipation, immune suppression and with prolonged treatment, tolerance, dependence and abuse liability. Studies in β-arrestin 2 gene knockout (βarr2(−/−)) animals indicate that morphine analgesia is potentiated while side effects are reduced, suggesting that drugs biased away from arrestin may manifest with a reduced-side-effect profile. However, there is controversy in this area with improvement of morphine-induced constipation and reduced respiratory effects in βarr2(−/−) mice. Moreover, studies performed with mice genetically engineered with G-protein-biased mu receptors suggested increased sensitivity of these animals to both analgesic actions and side effects of opioid drugs. Several new molecules have been identified as mu receptor G-protein-biased agonists, including oliceridine (TRV130), PZM21 and SR–17018. These compounds have provided preclinical data with apparent support for bias toward G proteins and the genetic premise of effective and safer analgesics. There are clinical data for oliceridine that have been very recently approved for short term intravenous use in hospitals and other controlled settings. While these data are compelling and provide a potential new pathway-based target for drug discovery, a simpler explanation for the behavior of these biased agonists revolves around differences in intrinsic activity. A highly detailed study comparing oliceridine, PZM21 and SR–17018 (among others) in a range of assays showed that these molecules behave as partial agonists. Moreover, there was a correlation between their therapeutic indices and their efficacies, but not their bias factors. If there is amplification of G-protein, but not arrestin pathways, then agonists with reduced efficacy would show high levels of activity at G-protein and low or absent activity at arrestin; offering analgesia with reduced side effects or ‘apparent bias’. Overall, the current data suggests—and we support—caution in ascribing biased agonism to reduced-side-effect profiles for mu-agonist analgesics.

Introduction The efficacy of preclinical ultrasound at providing a quantitative assessment of mouse models of vascular disease is relatively unknown. In this study, preclinical ultrasound was used in combination with a semi-automatic image processing method to track arterial distension alterations in mouse models of abdominal aortic aneurysm and atherosclerosis. Methods Longitudinal B-mode ultrasound images of the abdominal aorta were acquired using a preclinical ultrasound scanner. Arterial distension was assessed using a semi-automatic image processing algorithm to track vessel wall motion over the cardiac cycle. A standard, manual analysis method was applied for comparison. Results Mean arterial distension was significantly lower in abdominal aortic aneurysm mice between day 0 and day 7 post-onset of disease (p −/− (++/−−) mice fed high-fat western diet when compared with both wild type (++/++) mice and Ldlr−/− (++/−−) mice fed chow diet. The manual method did not detect a significant difference between these groups. Conclusions Arterial distension can be used as an early marker for the detection of arterial disease in murine models. The semi-automatic analysis method provided increased sensitivity to differences between experimental groups when compared to the manual analysis method.

The urotensin-II (U-II) receptor (UT, nomenclature as agreed by the NC-IUPHAR Subcommittee on the Urotensin receptor [26, 36, 89]) is activated by the endogenous dodecapeptide urotensin-II, originally isolated from the urophysis, the endocrine organ of the caudal neurosecretory system of teleost fish [7, 88]. Several structural forms of U-II exist in fish and amphibians. The goby orthologue was used to identify U-II as the cognate ligand for the predicted receptor encoded by the rat gene gpr14 [20, 62, 68, 70]. Human urotensin-II, an 11-amino-acid peptide [20], retains the cyclohexapeptide sequence of goby U-II that is thought to be important in ligand binding [53, 11]. This sequence is also conserved in the deduced amino-acid sequence of rat urotensin-II (14 amino-acids) and mouse urotensin-II (14 amino-acids), although the N-terminal is more divergent from the human sequence [19]. A second endogenous ligand for the UT has been discovered in rat [83]. This is the urotensin II-related peptide, an octapeptide that is derived from a different gene, but shares the C-terminal sequence (CFWKYCV) common to U-II from other species. Identical sequences to rat urotensin II-related peptide are predicted for the mature mouse and human peptides [32]. UT exhibits relatively high sequence identity with somatostatin, opioid and galanin receptors [89].

Background and Purpose There is evidence supporting a role for the nociceptin/orphanin FQ (N/OFQ; NOP) receptor and its endogenous ligand N/OFQ in the modulation of neurogenic inflammation, airway tone and calibre. We hypothesized that NOP receptor activation has beneficial effects upon asthma immunopathology and airway hyperresponsiveness. Therefore, the expression and function of N/OFQ and the NOP receptor were examined in healthy and asthmatic human airway tissues. The concept was further addressed in an animal model of allergic asthma. Experimental Approach NOP receptor expression was investigated by quantitative real-time PCR. Sputum N/OFQ was determined by RIA. N/OFQ function was tested using several assays including proliferation, migration, collagen gel contraction and wound healing. The effects of N/OFQ administration in vivo were studied in ovalbumin (OVA)-sensitized and challenged mice. Key Results NOP receptors were expressed on a wide range of human and mouse immune and airway cells. Eosinophils expressed N/OFQ-precursor mRNA and their number correlated with N/OFQ concentration. N/OFQ was found in human sputum and increased in asthma. Additionally, in asthmatic human lungs N/OFQ immunoreactivity was elevated. NOP receptor activation inhibited migration of immunocytes and increased wound healing in airway structural cells. Furthermore, N/OFQ relaxed spasmogen-stimulated gel contraction. Remarkably, these findings were mirrored in OVA-mice where N/OFQ treatment before or during sensitization substantially reduced airway constriction and immunocyte trafficking to the lung, in particular eosinophils. N/OFQ also reduced inflammatory mediators and mucin production. Conclusions and Implications We demonstrated a novel dual airway immunomodulator/bronchodilator role for N/OFQ and suggest targeting this system as an innovative treatment for asthma.

This study was designed to evaluate the effects of CP55,940 on normal bladder function in vivo and examine whether it suppresses urinary frequency induced by nociceptive stimuli in the bladder. Cannabinoid receptor (CBR) activity may be involved in the regulation of bladder function. However, the role of CBR subtypes in micturition has yet to be established. CP55,940 is a synthetic analogue of tetrahydrocannabidiol, which is a psychoactive ingredient of the Cannabis plant.Cystometry under urethane anaesthesia was performed to evaluate the effect of intravesical delivery of CP55,940 with or without administration of CB1 antagonist AM251 or CB2 antagonist AM630 on bladder function in female rats. The effects of CP55,940 were also examined in rats with urinary irritation induced by intravesical infusion of acetic acid.Infusion of CP55,940 significantly (p 0.05) increased micturition interval (MI) and bladder capacity (BC) by 52 % and decreased maximal voiding pressure (MP) by 25 %. Pretreatment with AM251 or AM630 before CP55,940 administration prevented CP55,940-induced increases in MI, BC and reduced MP. Acetic acid induced urinary frequency as evidenced by a reduction in MI and was suppressed by CP55,940.CP55,940 decreases bladder activity and urinary frequency induced by nociceptive stimuli, probably by suppression of bladder afferent activity. Effects of CP55,940 were abolished by both CBR antagonists. This data implicates a role for the endocannabinoid system in bladder mechanoafferent function in rats. In addition, our results show that CP55,940 reverses urinary frequency exemplified in an overactive bladder model, suggesting it could be an effective treatment for patients with lower urinary tract symptoms.

Background While it is well known that opioids depress the immune system, the site(s) of action for this depression is highly controversial. Immune modulation could occur directly at the immune cell or centrally via the hypothalamic-pituitary-adrenal axis. In a number of studies using individual enriched immune cell populations we have failed to detect classical µ (MOP), δ (DOP) and κ (KOP) receptors. The non-classical nociceptin/orphanin FQ (N/OFQ) receptor (NOP) is expressed on all cells examined thus far. Our hypothesis was that immune cells do not express classical opioid receptors and that using whole blood would definitively answer this question. Methods Whole blood (containing all immune cell types) was incubated with opioids (morphine and fentanyl) commonly encountered in anaesthesia and with agents mimicking sepsis [lipopolysaccharide (LPS) and peptidoglycan G (PepG)]. Opioid receptor mRNA expression was assessed by endpoint polymerase chain reaction (PCR) with gel visualisation and quantitative PCR. Results Classical MOP, DOP, and KOP receptors were not detected in any of the samples tested either at rest or when challenged with opioids, LPS or PepG. Commercial primers for DOP did not perform well in quantitative PCR, so the absence of expression was confirmed using a traditional gel-based approach. NOP receptors were detected in all samples; expression was unaffected by opioids and reduced by LPS/PepG combinations. Conclusions Classical opioid receptors are not expressed on circulating immune cells.

Summary Analgesic design and evaluation have been driven by the desire to create high-affinity high-selectivity mu (μ)-opioid peptide (MOP) receptor agonists. Such ligands are the mainstay of current clinical practice, and include morphine and fentanyl. Advances in this sphere have come from designing pharmacokinetic advantage, as in rapid metabolism for remifentanil. These produce analgesia, but also the adverse-effect profile that currently defines this drug class: ventilatory depression, tolerance, and abuse liability. The MOP receptor is part of a family, and there are significant functional interactions between other members of the family (delta [δ]-opioid peptide [DOP], kappa [κ]-opioid peptide [KOP], and nociceptin/orphanin FQ receptor [NOP]). Experimentally, MOP agonism and DOP antagonism produce anti-nociception (animals) with no tolerance, and low doses of MOP and NOP ligands synergise to antinociceptive advantage. In this latter context, the lack of effect of NOP agonists on ventilation is an additional advantage. Recent development has been to move towards low-selectivity multifunctional ‘mixed ligands', such as cebranopadol, or ligand mixtures, such as Targinact®. Moreover, the observation that β-arrestin coupling underlies the side-effect profile for MOP ligands (from knockout animal studies) led to the discovery of biased (to G-protein and away from β-arrestin intracellular signalling) MOP ligands, such as oliceridine. There is sufficient excitement in the opioid field to suggest that opioid analgesics without significant side-effects may be on the horizon, and the ‘opioid Holy Grail' might be in reach.

GLA is supported by British Journal of Anaesthesia/Royal College of Anaesthetists basic science Career Development award, British Oxygen Company research chair grant in anaesthesia from the Royal College of Anaesthetists and British Heart Foundation Programme Grant (RG/14/4/30736). HFG: funded by the Association of Anaesthetists of Great Britain and Ireland, the British Journal of Anaesthesia/Royal College of Anaesthetists and the Melville Trust. BGS: Chief Scientific Officer/NHS Research Scotland Career Research Fellow award. DGL: BBSRC; British Journal of Anaesthesia PhD studentship.

Deorphanization of ORL-1/LC132 in 1995 by reverse pharmacology in two simultaneously published landmark studies added a new member to the opioid family of G-protein coupled receptors. Meunier and Reinscheid used cells expressing recombinant ORL-1 (human) or LC132 (rat) and the presumed intracellular inhibition of cyclic AMP formation to ‘fish’ for endogenous peptide ligands in rat whole-brain and pig hypothalamic extracts. Both studies reported the isolation of a 17-amino-acid peptide, which was named nociceptin and orphanin FQ by the two authors, respectively. The behaviour of the isolated peptide was a complete surprise, as a general hyperalgesia was observed when the peptide was administered at supraspinal sites. We now know that this peptide has, in fact, anti-opioid action, particularly in the medulla. The endogenous peptide exerts a multitude of effects both in the nervous system and, unlike classical opioids, has efficacy in neuropathic pain.

Neuropathic pain is a common health problem that affects millions of people worldwide. Despite being studied extensively, the cellular and molecular events underlying the central immunomodulation and the pathophysiology of neuropathic pain is still controversial. The idea that 'glial cells are merely housekeepers' is incorrect and with respect to initiation and maintenance of neuropathic pain, microglia and astrocytes have important roles to play. Glial cells differentially express opioid receptors and are thought to be functionally modulated by the activation of these receptors. In this review, we discuss evidence for glia-opioid modulation of pain by focusing on the pattern of astrocyte and microglial activation throughout the progress of nerve injury/neuropathic pain. Activation of astrocytes and microglia is a key step in central immunomodulation in terms of releasing pro-inflammatory markers and propagation of a 'central immune response'. Inhibition of astrocytes before and after induction of neuropathic pain has been found to prevent and reverse neuropathic pain, respectively. Moreover, microglial inhibitors have been found to prevent (but not to reverse) neuropathic pain. As they are expressed by glia, opioid receptors are expected to have a role to play in neuropathic pain.

Opioids are characterised as classical (mu, delta, and kappa) along with the non-classical nociceptin/orphanin FQ (N/OFQ) receptor or NOP. Targeting NOP has therapeutic indications in control of the cardiovascular and respiratory systems and micturition, and a profile as an antidepressant. For all of these indications, there are translational human data. Opioids such as morphine and fentanyl (activating the mu receptor) are the mainstay of pain treatment in the perioperative period, despite a challenging side-effect profile. Opioids in general have poor efficacy in neuropathic pain. Moreover, longer term use is associated with tolerance. There is good evidence interactions between opioid receptors, and receptor co-activation can reduce side-effects without compromising analgesia; this is particularly true for mu and NOP co-activation. Recent pharmaceutical development has produced a mixed opioid/NOP agonist, cebranopadol. This new chemical entity is effective in animal models of nociceptive and neuropathic pain with greater efficacy in the latter. In animal models, there is little evidence for respiratory depression, and tolerance (compared with morphine) only develops after long treatment periods. There is now early phase clinical development in diabetic neuropathy, cancer pain, and low back pain where cebranopadol displays significant efficacy. In 1996, N/OFQ was formally identified with an innovative analgesic profile. Approximately 20 yr later, cebranopadol as a clinical ligand is advancing through the human trials process.

Biological age is a better measure of functional capacity than chronological age.1 One of the measures of biological age is telomere length. Telomeres are nucleoprotein complexes that protect chromosome ends from damage. The DNA component of telomeres progressively shortens as biological age increases and thus acts as a read out for ‘miles on the biological clock’. 2 Telomere length progressively shortens as biological age increases. Within health care, ageing is almost exclusively described in terms of chronological age. Recent studies explored using biological age to stratify patients and predict outcomes.3 This project acts as a pilot study to investigate whether biological age is related to intensive care unit (ICU) outcomes and whether ICU patients age biologically at an accelerated rate. This project used blood samples from a previous study where patients underwent cardiac surgery and were admitted to the ICU. Blood samples were obtained before surgery and on days 1, 2, and 3 after surgery. The database contained the following physiological parameters: haemoglobin, urea, creatinine, RIFLE score, length of ICU stay, and whether renal replacement therapy was required. Information on co-morbidities and medication was also provided. DNA was isolated using a Maxwell machine and telomere length determined via quantitative PCR. One hundred and fifty-five blood samples from 46 patients underwent analysis. Telomere length did not differ significantly over the 4 days (P=0.662). No relationship was found between telomere length and any physiological parameter, co-morbidity, or medication. There was a trend towards significance with RIFLE score at day 3 increasing as telomere length decreased, although this was not statistically significant (P=0.09). No relationship between telomere length and the available physiological parameters, comorbidities, or medication was found. Telomere length did not vary during ICU stay. This study was limited by its small sample size. Future studies would benefit from a larger sample size; in addition, blood samples could also be obtained at 6 months after discharge to allow gradual alterations in biological age to be determined. Recent studies give evidence that telomere length is a weak biomarker of ageing,3 and that more meaningful data might be obtained using superior markers, such as CDKN2A expression or expression levels of non-coding RNAs.3

Immunohistochemical (IHC) evidence shows that cannabinoid receptors (CB) are expressed in human bladders and cannabinoid agonists are known to inhibit detrusor contractility. However, the mechanism for this inhibition remains unknown. In addition, the role of CB in detrusor overactivity (DO) is under-investigated. The aim of this study was to compare CB expression in normal and DO human bladders and to further characterise these receptors. Polymer chain reaction (PCR) was used to detect differences in CB transcripts in bladder samples. Differences in CB protein expression was assessed by IHC. Immunofluorescence (IF) was used to evaluate co-localisation of CB with nerve fibres. Receptor density and binding affinity were measured using the cannabinoid radioligand [3H]-CP-55,940. There were higher levels of CB1 transcripts in the urothelium of patients with DO and lower levels in the detrusor, compared with normal bladders. Radioligand binding revealed CB density of 421 ± 104 fmol/mg protein in normal human bladders. IHC confirmed these findings at the protein level. IF staining demonstrated co-localisation of CB1 with choline acetyltransferase-(ChAT)-positive nerves in the detrusor and co-localisation with PGP9.5 in both urothelium and detrusor. CB2 was co-localised with both ChAT and PGP9.5 in the urothelium and the detrusor. Cannabinoid receptor expression is reduced in the detrusor of patients with DO, which may play a role in the pathophysiology of the disease. Co-localisation of CB receptors with cholinergic nerves may suggest that CB1, being localised on pre- and postsynaptic terminals, could influence neurotransmitter release. Our findings suggest the potential role of cannabinoid agonists in overactive bladder pharmacotherapy.

PURPOSE OF REVIEW This article aims to discuss the multitarget concept for opioid receptor ligands framed on early observations that activating MOP (mu:μ) receptor whilst simultaneously blocking DOP (delta:δ) receptors reduces the onset of morphine tolerance. The review period is ostensibly calendar year 2014 but the new work in 2013 is also covered. RECENT FINDINGS Two molecules of interest with MOP agonist/DOP agonist and MOP agonist/DOP antagonist profiles were described: Rv-Jim-C3 and 3-[(2R,6R,11R)-8-hydroxy-6,11-dimethyl-1,4,5,6-tetrahydro-2,6-methano-3-benzazocin-3(2H)-yl]-N-phenylpropanamide (LP1), respectively. Both were effective in neuropathic pain (wherein classical single target opioids have low efficacy) with the latter having a predicted reduced tolerance profile. BU0807 is a buprenorphine derivative with mixed MOP/NOP agonist activity and this was shown to be effective in abdominal pain. SR16435 and GRT6005 (cebranopadol) are mixed MOP/MOP agonists with varying degrees of partial agonism. Both displayed significant antinociceptive activity and reduced tolerance potential in preclinical models. SUMMARY There is growing evidence for and interest in the design and evaluation of mixed opioids that extend beyond the MOP/DOP pairing to now include NOP. Indeed, a mixed MOP/NOP ligand is close to the clinic; this will reinvigorate the search for other mixed molecules with reduced side-effect profiles.

Background Opioid tolerance is a limiting factor in chronic pain. Delta opioid peptide (DOP)(δ) receptor antagonism has been shown to reduce tolerance. Here, the common clinical mu opioid peptide (MOP)(µ) receptor agonist fentanyl has been linked to the DOP antagonist Dmt-Tic (2′,6′-dimethyl-L-tyrosyl-1,2,3,4-tetrahydrisoquinoline-3-carboxylic acid) to create new bivalent compounds. Methods Binding affinities of bivalents(#9, #10, #11, #12 and #13) were measured in Chinese hamster ovary (CHO) cells expressing recombinant human MOP, DOP, Kappa opioid peptide (KOP)(κ) and nociceptin/orphanin FQ opioid peptide (NOP) receptors. Functional studies, measuring GTPγ[35S] or β-arrestin recruitment, were performed in membranes or whole cells respectively expressing MOP and DOP. Results The new bivalents bound to MOP (pKi : #9:7.31; #10:7.58; #11:7.91; #12:7.94; #13:8.03) and DOP (#9:8.03; #10:8.16; #11:8.17; #12:9.67; #13:9.71). In GTPγ[35S] functional assays, compounds #9(pEC50:6.74; intrinsic activity:0.05) #10(7.13;0.34) and #11(7.52;0.27) showed weak partial agonist activity at MOP. Compounds #12 and #13, with longer linkers, showed no functional activity at MOP. In antagonist assays at MOP, compounds #9 (pKb:6.87), #10(7.55) #11(7.81) #12(6.91) and #13(7.05) all reversed the effects of fentanyl. At DOP, all compounds showed antagonist affinity (#9:6.85; #10:8.06; #11:8.11; #12:9.42; #13:9.00), reversing the effects of DPDPE ([D-Pen2,5]enkephalin). In β-arrestin assays, compared with fentanyl (with response at maximum concentration (RMC):13.62), all compounds showed reduced ability to activate β-arrestin (#9 RMC:1.58; #10:2.72; #11:2.40; #12:1.29; #13:1.58). Compared with fentanyl, the intrinsic activity was: #9:0.12; #10:0.20; #11:0.18; #12:0.09 and #13:0.12. Conclusions The addition of a linker between fentanyl and Dmt-Tic did not alter the ability to bind to MOP and DOP, however a substantial loss in MOP functional activity was apparent. This highlights the difficulty in multifunctional opioid development.

The ability to quantify the amount of a specific protein in a complex sample has been a valuable addition to laboratory science, allowing the development of diagnostic tests, allergen detection in the food industry,and screening for immunity. This is particularly important in anaesthesia, intensive care, and pain research for the quantification of mediators (cytokines, peptides, and analytes) involved in inflammation, pain, and other pathways. Immunoassays use the high specificity of antibodies, along with their enormous diversity, to target specific molecules of interest and analyse their concentration in a sample. The first immunoassay developed was described by Yalow and Berson in 1959. They used radiolabelled insulin to assess the concentration of insulin in human plasma, and thus developed the first radioimmunoassay (RIA). In 1971, Engvail and Perlman described a technique whereby antigens were immobilized on a microplate well, incubated with antiserum, and then the concentration of antibody in the antiserum was quantified using an enzyme-linked anti-immunoglobulin antibody. This method is the enzyme-linked immunosorbent assay (ELISA). Enzyme immunoassays (EIAs) are very similar to ELISAs, and as such, the terms are often used interchangeably. The EIA was developed by Van Weemen and Schuurs (independently of Engvail and Perlman) for the quantification of antigen rather than antibody. For the purpose of this article, EIA and ELISA should be considered interchangeable. The majority of RIA assay formats recommend sample cleaning and concentration (particularly when analyte concentration and assay sensitivity is low), although a large number of ELISA assays can cope with direct use of unprocessed plasma. The cleaning and concentration process usually involves ion exchange chromatography followed by some form of freeze drying/lyophilization. We would recommend users to determine if sample cleaning is required for their analyte. Often, there are differences in measured analyte concentration when comparing RIA and ELISA. This can result from specificity of the antibody (e.g. the cardiovascular peptide urotensin II) 6 or the fluid in which the analyte is suspended interfering with only one type of assay (e.g. the opioid-related peptide Nociceptin/Orphanin FQ). – 11 Discordance has also been demonstrated between RIAs and EIAs measuring cortisol and carcinoembryonic antigen. 13 The selection of assay format is therefore critical and the remainder of this article covers the main formats currently available.

non-classical member of the opioid family as it shares structural and transduction homology and anatomical localization with the classical m-opioid receptor (MOP), d-opioid receptor (DOP), and k-opioid receptor. However, its actions are not sensitive to the universal opioid antagonist naloxone. 2 This peptidereceptorsystemhasbeenimplicatedinthephysiology andpathophysiologyofanxiety/depression,learning/memory, feeding,airwaydisease,immunedysfunction,gastrointestinal motility,urologicaldisease,andpain. 1 Modulationofactivityat this receptor produces variable effects on the nociceptive (pain) response in laboratory animals, with N/OFQ and NOP agonists in general producing antinociception when given spinally and pro-nociceptive/anti-opioid actions when administered supraspinally in rodents. Spinal administration of N/OFQ or NOP agonists also produces antinociception in nonhuman primates. 13 The link to the clinic, as is often the case

Despite the development of effective chemotherapy and radiotherapy, surgery remains the mainstay treatment of many cancers, requiring anesthesia. Almost all cancer deaths after primary surgery are attributable to recurrence or metastases. Recently it has been hypothesized that the perioperative anesthetic management of cancer patients could potentially affect the risk of recurrence and metastases, which implies a key role for anesthesiologists in choosing anesthetic agents and techniques that optimize the balance between the metastatic potential of the tumor versus its elimination by antimetastatic immune defenses. This review summarizes available experimental information on the potential effects of common anesthetic agents and techniques on cancer metastases and the conflicting retrospective clinical data on regional anesthesia in various types of cancer. A number of prospective, randomized, multicenter, clinical trials are in progress, and their results are eagerly awaited.

There are a wide range of joint and muscle diseases. The main joint diseases covered in this article are osteoarthritis and gout. The former is treated with symptomatic pain relief and the latter with strategies to reduce uric acid deposition in the joint, especially allopurinol. Myasthenia gravis is an autoimmune disease targeted to muscle type nicotinic receptors. Treatment is based on improving neuromuscular function by (i) increasing acetylcholine concentrations with neostigmine and pyridostigmine, (ii) immunosuppression, (iii) thymectomy and (iv) plasmapheresis. General muscle spasticity can be caused by a wide range of conditions including multiple sclerosis, cerebral palsy, Parkinson's disease and secondary to stroke. This can be treated centrally with baclofen, tizanidine and benzodiazepines or peripherally with dantrolene. Botulinum toxin inhibits the exocytosis of acetylcholine-containing vesicles and can be used for cervical dystonia, strabismus, blepharospasm, severe axillary hyperhidrosis and cosmetic procedures.

summary There is growing evidence for an involvement of the cannabinoid system in the pathogenesis of sepsis. In vitro, immune cell activation increases endocannabinoid production and reduces metabolic breakdown. The net result of this increased endocannabinoid activity is likely to cause hypotension-often a characteristic of sepsis. In whole animals lacking the CB 2 cannabinoid receptor (found on immune cells) there was an increased incidence of multi-organ failure in a caecal ligation and puncture model of sepsis. In humans there is limited evidence for reduced metabolic activity in immune cells of patients with systemic sepsis; polymixin B haemofiltration (reducing endocannabinoids) may be beneficial in sepsis. Collectively these data suggest that strategies to modulate the endocannabinoid response in sepsis might represent a novel adjunctive strategy.

According to the World Health Organization about 450 million people suffer from mental and behavioural disorder worldwide whereas depression has a lifetime prevalence of between 10 and 20%. Antidepressants are broadly divided into four main groups: tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), atypical agents and monoamine oxidase inhibitors (MAOIs). Lithium is also occasionally used as an adjunct to treat refractive depression, but is more commonly used as a mood stabilizer in bipolar affective disorder. Antipsychotics are usually classified as ‘conventional’ antipsychotics or ‘atypical’ agents. The anaesthetist has to incorporate these agents in premedication and should anticipate their interactions with anaesthetic technique.

When it was first discovered in the 1500s, opium was heralded as the most potent analgesic. The Latin name for morphine tincture, laudanum (to praise), illustrates the high regard in which it was held. The many adverse effects associated with its use (now attributed to non-specific opioid receptor cross-activation between subtypes) necessitate caution in its use. Even today, the adverse effects still remain problematic and are clinically limiting, both in the acute setting and in chronic use, despite ample research into opioid receptor subtype specific agonists, antagonists and bifunctional molecules. The adverse effects, such as constipation, nausea, dysphoria, respiratory depression and itching, have necessitated the drive to develop non-opioid-related analgesics, both as sole agents and as part of multimodal, opioid-sparing regimens. For example, paracetamol has been shown to reduce patient-controlled analgesia (PCA) morphine doses by 20% when used as an adjunct for acute post-surgical pain. Additionally, whilst effective for acute pain, opiate analgesia is of limited effectiveness for chronic and neuropathic pain states, such as phantom limb pain. This is partly due to problems with chronic administration and pharmacologic tolerance although also relates to different mechanisms of acute (e.g. surgical) and chronic pain and involvement of additional neurotransmitters such as substance P, γ-aminobutyric acid and glutamate. This article will give an overview of the pain pathway relative to therapeutic targets, revisit some common non-opioid analgesic agents and highlight some novel targets and drugs in development.

Nociceptin/orphanin FQ, N/OFQ, and its receptor NOP represent a non-opioid branch of the opioid superfamily that were first studied for their effects on pain responses. Both N/OFQ and NOP are involved in a wide range of 'non-pain' responses including immunomodulation and cardiovascular control. There is now growing interest in this system in inflammation and sepsis, which is the focus of this review article. The N/OFQ-NOP system is present in immune cells and N/OFQ modifies immunocyte function. On the basis of various in vitro and in vivo studies, N/OFQ increases the inflammatory response in healthy anaesthetized animals and in those with a septic or inflammatory process. It affects tissue perfusion, increases capillary leakage and inflammatory markers, and leads to immune cell chemotaxis. Moreover, NOP activation produces bradycardia and hypotension. Systemic N/OFQ administration also increased mortality in an animal model of sepsis, and there is limited evidence for increased plasma N/OFQ concentrations in patients with sepsis who died compared with those who survived. There is a need for further observational and mechanistic studies in patients with established inflammatory processes or sepsis. These studies may facilitate the design of appropriate clinical studies to evaluate NOP ligands as modifiers of the inflammatory response.

Urotensin II (UII) and its receptor UT are involved in control of the cardiovascular system and are implicated in heart failure. We measured UT expression by quantitative PCR (Q-PCR) in atrial and aortic tissue, and plasma UII while simultaneously assessing cardiac function in 40 patients undergoing coronary artery bypass surgery.RNA extracted from atrial and aortic samples was probed with specific Q-PCR UT and housekeeper (glyceraldehyde-3-phosphate dehydrogenase, GAPDH) TaqMan primers. Plasma UII was measured using radioimmunoassay. Left ventricular ejection fraction (LVEF) was measured using preoperative trans-thoracic echocardiography and ventriculography, and intraoperatively using transoesophageal echocardiography. Q-PCR data are expressed as difference in cycle threshold (DeltaC(t)=C(tUT)-C(tGAPDH): high number indicates low expression).There was no difference in DeltaC(t) in either atrium or aorta between patients with normal (LVEF50%) or those with impaired (LVEF50%) preoperative systolic function. There was a weak negative correlation (r(2)=0.245, P=0.031) between intraoperative LVEF and DeltaC(t) in 19 patients possibly indicating down-regulation of UT with worsening LVEF. Atria expressed significantly more UT than aorta (P=0.011). In the absence of non-diseased controls, plasma UII was higher than a historical control group.This is the first study to simultaneously measure UT (mRNA), UII, and cardiovascular function. Collectively, these pilot data may suggest a down-regulation of UT within the right atrium of patients with heart failure.

Identification of the enigmatic nociceptin/orphanin FQ peptide (N/OFQ) in 1995 represented the first successful use of reverse pharmacology and led to deorphanization of the N/OFQ receptor (NOP). Subsequently, the N/OFQ-NOP system has been implicated in a wide range of biological functions, including pain, drug abuse, cardiovascular control and immunity. Although this could be considered a hurdle for the development of pharmaceuticals selective for a specific disease indication, NOP represents a viable drug target. This article describes potential clinical indications and highlights the current status of the very limited number of clinical trials.

Background. The systemic inflammatory response to infection (sepsis) involves widespread organ dysfunction, including changes in immune modulation, cardiovascular derangements, and neural activation. Two neuropeptide/receptor systems, nociceptin/orphanin FQ (N/OFQ) which acts at the non-classical opioid receptor NOP and urotensin-II (U-II) which acts at the urotensin receptor (UT), have been implicated in neural, immune, and cardiovascular system function. In this study, we make measurements of these peptides in critically ill patients. Methods. Plasma samples from 21 critically ill patients with sepsis were collected over four consecutive days. Plasma N/OFQ and U-II concentrations were determined by radioimmunoassay and compared with biochemical and clinical markers of illness severity, including serum creatinine, bilirubin, platelet and white cell counts, admission APACHE II and serial SOFA scores. Results. Median (inter-quartile range) admission plasma N/OFQ concentrations in sepsis were higher in patients who died within 30 days (n¼4) compared with survivors (n¼17); 3.0 (2.5‐5.0) vs 1.0 (1.0‐2.5) pg ml 21 (P¼0.028). Plasma N/OFQ concentrations were increased in a subgroup of five patients who had undergone major gastrointestinal surgery. There were no significant changes in plasma U-II concentrations. There were no correlations between plasma U-II and N/OFQ concentrations and markers of illness severity and organ system dysfunction. Conclusions. Plasma N/OFQ concentrations were increased in critically ill patients with sepsis who had undergone major gastrointestinal surgery and in patients who subsequently died. Further work is required to clarify the significance of plasma N/OFQ concentrations in sepsis. Br J Anaesth 2008; 100: 810‐14

Pain is a major cause of distress, both physical and psychological and is also associated with increased inpatient hospital stays, poor wound healing and prolonged rehabilitation. Opioids are a mainstay of treatment for acute pain, although they are associated with significant morbidity through adverse effects such as respiratory depression, psychosis, and nausea and vomiting. The non-opiate analgesics avoid some of these effects, although are not panaceas, non-steroidal anti-inflammatory drugs (NSAIDS), for example, are associated with renal and gastric damage, which precludes their use in elderly patients and those with renal impairment. This article reviews the underlying pain pathways and the ways in which these pathways may be modulated in the pursuit of side-effect-free analgesia. Existing medications target these pathways, although there are evolving targets for analgesics. The advantages and disadvantages of the current non-opioid mainstays of treatment are reviewed. Other centrally acting medications, both research (nociceptin, neuropeptides, cannabinoids) and clinical (gabapentin, carbamazepine) are also considered. Combinations of existing analgesics underlie the principles of multimodal analgesia; non-opioid adjuncts are known to reduce postsurgical opioid requirements and improve rehabilitation and discharge. The answer may lie in synergistic dual-acting medications, which are discussed with reference to the COX-inhibiting nitric oxide donors and dual lipoxygenase/cyclooxygenase inhibitors.

Urotensin II (U-II) is currently the most potent vasoconstrictor identified. This action is brought about via activation of a G(q/11)-protein coupled receptor (UT receptor). U-II activation of the UT receptor increases inositol phosphate turnover and intracellular Ca(2+). In addition to producing vasoconstriction, dilation and ionotropic effects have also been described. There is considerable variation in the responsiveness of particular vascular beds from the same and different species, including humans. Receptors for U-II are located peripherally on vascular smooth muscle (contractile responses) and endothelial cells (dilatory responses via nitric oxide). In humans, plasma U-II is elevated in heart failure, renal failure, liver disease, and diabetes. Iontophoresis of U-II in healthy volunteers produces vasodilation (of the forearm) while in patients with heart failure or hypertension a constriction is observed. To date there is only one clinical study using a UT receptor antagonist (palosuran) in diabetic patients with macroalbuminuria. This antagonist reduced albumin excretion, probably by increasing renal blood flow. Studies in other disease conditions are eagerly awaited. In summary, the U-II / UT receptor system has clinical potential, and for the anesthesiologist, this novel peptide-receptor system may be of use in the intensive care unit.

Properdin is a normal serum protein which increases the production of complement activation products by binding to C3b integral to convertase complexes and amplifying their activity at the site of activation. Thereby, it can aid in the resolution of infection but also contribute to tissue damage. In human sepsis, circulating complement C3 concentrations are decreased, though C3 is described as a positive acute phase reactant. However, properdin levels in human sepsis have not been reported. In this study, serum from 81 critically ill patients (predominately abdominal and respiratory sepsis) were analysed for properdin levels at defined points of their stay in the Intensive Care Unit (ICU) and compared with 61 age and sex-matched healthy volunteers. Properdin concentrations were significantly decreased in patients with sepsis on admission to ICU, but increased after clinical recovery to exceed levels observed in healthy volunteers. Properdin concentrations at ICU admission were decreased in non-survivors of sepsis compared to survivors, but this did not correlate with APACHE II score. However, pathologically low properdin levels (

Background Urotensin II (UII) is the most potent endogenous vasoconstrictor identified to date. Pre-eclampsia is associated with arteriolar vasospasm but the precise underlying mechanism is uncertain and we hypothesized that UII concentrations might also be elevated. In this study we measured UII concentrations in maternal plasma and cerebrospinal fluid (CSF), and umbilical vein plasma from pre-eclamptic (PET) and normotensive patients undergoing elective Caesarean section under spinal or combined spinal–epidural anaesthesia. Methods With LREC approval and informed consent we recruited two groups of 10 patients; control [mean (range) age, 29 (22–43) yr; BMI, 25 (20–32); gestation, 273 (267–281) days; mean arterial pressure (MAP) on day of delivery, 81 (75–96) mm Hg] and PET [age, 34 (22–40) yr; BMI, 25 (21–46); gestation, 253 (203–289) days; MAP on day of delivery, 106 (88–128) mm Hg]. Maternal blood and CSF samples and umbilical vein blood samples were taken. UII was extracted and concentrations measured using a radioimmunoassay. Results Two plasma and two CSF samples in the control and two CSF samples in the PET group were below the assay detection limits. There were no differences in maternal plasma or CSF or umbilical vein UII concentrations between the groups. However, there was a small (∼40%) but significant increase in cord UII concentrations when compared with paired plasma in the PET group. There was a weak but significant negative correlation (r=−0.4, P=0.049) between cord UII concentrations and gestation in the PET group. In addition, we observed a significant positive correlation between plasma and CSF (r2=+0.57, P=0.0009, n=16), plasma and cord (r2=+0.43, P=0.0031, n=18) and CSF and cord (r2=+0.32, P=0.022, n=16) UII concentrations for the whole data set. Conclusions Collectively the data indicate that UII concentrations do not increase in PET compared with controls but, in PET patients, cord UII concentrations are elevated relative to paired plasma samples. Elevated umbilical vein UII concentrations may simply indicate reduced placental viability and possibly UII metabolism as a result of reduced blood flow or possibly that the placenta is producing UII.

Background TRPV1 is a ligand-gated ion channel whose activation by capsaicin increases intracellular Ca2+ ([Ca2+]i). TRPV1 and cannabinoid CB1 receptor activation are capable of eliciting analgesia. In this study, using recombinant human (h) and rat (r) TRPV1 receptors expressed in HEK293 cells, we have performed a comparison of both TRPV1 species at 22 and 37°C and compared endo- and exocannabinoid activity at both receptors. Methods [Ca2+]i was measured in Fura-2-loaded HEK293hTRPV1 and HEK293rTRPV1 cells. To assess native CB1 receptor activity, [35S]GTPγS binding to membranes prepared from rat cerebellum was measured. Results Both capsaicin (pEC50 rat ∼6.9 and pEC50 human ∼6.8 at 37°C) and anandamide (pEC50 rat ∼5.3 and pEC50 human ∼5.8 at 37°C) produced a concentration-dependent increase in [Ca2+]i in rat and human systems and at 22 and 37°C. In HEK293rTRPV1 cells, anandamide appeared to be a partial agonist. Capsazepine demonstrated competitive antagonism at both human and rat TRPV1 receptors and at both temperatures studied. Capsazepine effects were not temperature dependent: pKB at rTRPV1 was 5.98 at 22°C and 6.02 at 37°C, and pKB at hTRPV1 was 6.76 at 22°C and 6.75 at 37°C. However, there was a consistent 6-fold increase in capsazepine potency for hTRPV1 relative to rTRPV1. The exocannabinoid Δ9-tetrahydrocannabinol failed to increase [Ca2+]i, although its solvent ethanol was an effective TRPV1 activator. In the [35S]GTPγS binding assay using rat cerebellar membranes, anandamide (pEC50 ∼5.8) and Δ9-tetrahydrocannabinol (pEC50 ∼7.1), but not capsaicin, stimulated binding. Δ9-tetrahydrocannabinol was a partial agonist. pEC50 values for anandamide at rTRPV1 and rCB1 were similar. Conclusions There were small differences in the pharmacology of rat and human TRPV1 receptors. Whilst capsaicin activated TRPV1 and Δ9-tetrahydrocannabinol activated CB1, anandamide is an endogenous agonist for both receptor systems.

Clinically opioids are immunomodulatory where a general depression is reported. In addition immune cells carry endogenous opioid peptides to sites of inflammation where opioid receptors on peripheral nerves are upregulated. Release of these endogenous opioids produces a degree of analgesia and completes the neuroimmune axis. The expression of opioid receptors on immune cells that deliver these opioid peptides is contentious and is the basis of this short review. There are several papers reporting expression of opioid receptors on peripheral blood mononuclear cells (PBMCs) using a variety of in vitro biochemical/pharmacological techniques. Equally there are studies failing to detect these receptors. We have recently undertaken a detailed volunteer study to determine the expression of classical naloxone sensitive MOP DOP and KOP and non‑classical naloxone insensitive NOP receptors. We initially focused our attention on the MOP receptor as the main clinical analgesic target. Using radioligand binding FACS with opioid receptor antibodies and PCR we have failed to detect all classical opioid receptors. In contrast using PCR techniques the non‑classical NOP receptor is present in all volunteer samples examined along with its endogenous peptide ligand nociceptin/orphanin F/Q (N/OFQ) . As both the peptide (N/OFQ) and receptor (NOP) are present we suggest that there may be a feedback loop such that peripherally delivered N/OFQ (to infl ammatory site) would produce both a classical analgesic response and then feedback to modulate PMBC function. The nature of that function remains to be determined but could include release of further N/OFQ activation of other immune cells or chemotaxis. Opioids have been used by man for centuries for the relief of pain. Morphine is the most widely used opioid in the clinic and is considered the gold standard to which all others are compared. In addition to producing analgesia opioid administration also produces other eff ects including; respiratory depression gastrointestinal‑inhibition tolerance and dependence and immunomodulation basic summaries see1‑4)

There are four principle protein targets with which drugs can interact: enzymes (e.g. neostigmine and acetyl cholinesterase), membrane carriers (e.g. tricyclic antidepressants and catecholamine uptake-1), ion channels (e.g. nimodipine and voltage-gated Ca2+ channels) and receptors. This article is concerned with the receptor and describes the dynamics of drug–receptor interaction, agonists, antagonists, partial agonists and inverse agonists, efficacy and potency. Key definitions are shown in Table 1 .

UNLABELLED Capsaicin, acting at the vanilloid 1 receptor (VR1), may potentiate local anesthetic activity, and as a ligand-gated ion channel of the transient receptor potential family, may also be a target for IV general anesthetics. We have examined whether local (lidocaine, prilocaine, and procaine 0.1-10 mM; 10 mM represents 0.25%-0.27% wt/vol) or IV anesthetics (propofol 10 micro M, thiopental 100 micro M, and ketamine 100 micro M) interact with recombinant rat VR1 expressed in human embryonic kidney (HEK293) cells (VR1-HEK293). We have assessed receptor interaction functionally by monitoring intracellular Ca(2+) ([Ca(2+)](i)) in Fura2-loaded cells at 37 degrees C. The addition of capsaicin (60 nM) produced a time-dependent biphasic increase in [Ca(2+)](i) amounting to 50-100 nM above than basal, which was inhibited by capsazepine 10 micro M and was absent in wild type HEK293 cells. Lidocaine and prilocaine alone (e.g., at 10 mM) significantly increased [Ca(2+)](i) by 67 +/- 6 nM and 33 +/- 7 nM, respectively, and concentration-dependently inhibited the capsaicin response. The effects of procaine were obscured by anesthetic-induced quenching of Fura2. In wild type HEK293 cells, lidocaine (10 mM) alone produced a small increase in [Ca(2+)](i). All IV anesthetics failed to modify capsaicin-increased [Ca(2+)](i). In conclusion, the present data suggest that local but not IV general anesthetics interact with recombinant rat VR1 receptors with the former anesthetics having antagonistic activity. IMPLICATIONS Vanilloid receptors (VR1) are activated by capsaicin, the pain-producing component of hot chili peppers. We suggest that local (but not IV general) anesthetics may have inhibitory actions on this receptor.