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Each row shows the results for an exploratory endpoint with ANCOVA adjusted means on the left (error bars ± sem) and the ratios of adjusted means for oxycodone/saline on the right (error bars ±95%CI). Ratio graphs focus on 0, 30, 60 and 90 minutes, the time points at which a following cohort of animals was determined to have (mean±sem) 0±0 nM, 44±6 nM, 217±24 nM and 70±12 nM free plasma concentration of oxycodone respectively. The 90 minute time point is after a 30 minute infusion of 20 mg/kg/hr naloxone with no oxycodone infused. (A) tonic spike count during the six seconds following phasic spiking (B) phasic spiking during the first one second after rotation onset (C) ongoing activity quantified during the 120 seconds preceding each stimulus set (D) afterdischarge during the 120 seconds following the last rotation of each set.
Source publication
Sensory processing in the spinal cord during disease states can reveal mechanisms for novel treatments, yet very little is known about pain processing at this level in the most commonly used animal models of articular pain. Here we report a test of the prediction that two clinically effective compounds, naproxen (an NSAID) and oxycodone (an opiate)...
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Osteoarthritis (OA) remains one of the greatest healthcare burdens in western society, with chronic debilitating pain-dominating clinical presentation yet therapeutic strategies are inadequate in many patients. Development of better analgesics is contingent on improved understanding of the molecular mechanisms mediating OA pain. Voltage-gated calci...
Voltage gated sodium channel blockers are not traditionally recommended for osteoarthritis (OA) pain therapy, but given the large peripheral drive that follows OA development there is a rationale for their use. Using a rat model of monosodium iodoacetate (MIA) induced osteoarthritis we used in vivo electrophysiology to assess the effects of the Nav...
Citations
... The study specifically tested the effects of a single oral administration of naproxen on brain responses to painful pressure stimulation in patients with knee OA, at a dose previously shown to reduce spinal sensitization. 16,58 We hypothesized that naproxen would reduce activity in the NPS when contrasted with placebo because of its well-established analgesic effect and clear anti-inflammatory mechanism of action. ...
... The reduction became numerically stronger-numerically larger in magnitude-when the NPS response was tested specifically on nociceptive regions (NPSp), 24,50 which agrees with the observed reduction in subjective pain reports after naproxen. NPS reductions after naproxen-an anti-inflammatory drug with previously identified nociceptive effects at the peripheral and central nervous system levels 16,19,21,32,43,58 -argues in favor of the NPS and NPSp as good summary measures of drug effects (vs placebo) on nociceptive processing in the human brain. NPS and NPSp reductions during naproxen vs placebo align with findings from a neuroimaging placebo-controlled trial testing naproxen effects on brain activity. ...
Introduction:
Many drug trials for chronic pain fail because of high placebo response rates in primary endpoints. Neurophysiological measures can help identify pain-linked pathophysiology and treatment mechanisms. They can also help guide early stop/go decisions, particularly if they respond to verum treatment but not placebo. The neurologic pain signature (NPS), an fMRI-based measure that tracks evoked pain in 40 published samples and is insensitive to placebo in healthy adults, provides a potentially useful neurophysiological measure linked to nociceptive pain.
Objectives:
This study aims to validate the NPS in knee osteoarthritis (OA) patients and test the effects of naproxen on this signature.
Methods:
In 2 studies (50 patients, 64.6 years, 75% females), we (1) test the NPS and other control signatures related to negative emotion in knee OA pain patients; (2) test the effect of placebo treatments; and (3) test the effect of naproxen, a routinely prescribed nonsteroidal anti-inflammatory drug in OA.
Results:
The NPS was activated during knee pain in OA (d = 1.51, P < 0.001) and did not respond to placebo (d = 0.12, P = 0.23). A single dose of naproxen reduced NPS responses (vs placebo, NPS d = 0.34, P = 0.03 and pronociceptive NPS component d = 0.38, P = 0.02). Naproxen effects were specific for the NPS and did not appear in other control signatures.
Conclusion:
This study provides preliminary evidence that fMRI-based measures, validated for nociceptive pain, respond to acute OA pain, do not appear sensitive to placebo, and are mild-to-moderately sensitive to naproxen.
... There has been significant focus on the innervation of the articular tissues because of the ease of experimental access in animal models. Both the synovium and joint capsule are innervated by nociceptors that respond to noxious mechanical stimulation and known algesic substances, and that can be sensitized by inflammatory mediators in OA. 4,6,8,23,31,42,43,54,59,65 In studies of humans with OA, synovitis provokes pain via mediators of inflammation and there are reports of associations between knee pain and the degree of OA synovitis. 26,75 However, whereas radiographic evidence of joint damage predisposes to pain, the severity of the damage to the joint bears little relation to the severity of the pain experienced. ...
Whilst it is clear that osteoarthritis (OA) pain involves activation and/or sensitization of nociceptors that innervate knee joint articular tissues, much less is known about the role of the innervation of surrounding bone. In this study, we used mono-iodoacetate (MIA)-induced OA in male rats to test the idea that pain in OA is driven by differential contributions from nerves that innervate knee joint articular tissues vs the surrounding bone. The time-course of pain behavior was assayed using the advanced dynamic weight bearing device, and histopathology was examined using H&E histology. Extracellular electrophysiological recordings of knee joint and bone afferent neurons were made early (day 3) and late (day 28) in the pathogenesis of MIA-induced OA. We observed significant changes in the function of knee joint afferent neurons, but not bone afferent neurons, at day 3 when there was histological evidence of inflammation in the joint capsule, but no damage to the articular cartilage or subchondral bone. Changes in the function of bone afferent neurons were only observed at day 28, when there was histological evidence of damage to the articular cartilage and subchondral bone. Our findings suggest that pain early in MIA-induced OA involves activation and sensitization of nerves that innervate the joint capsule but not the underlying subchondral bone, and that pain in late MIA-induced OA involves the additional recruitment of nerves that innervate the subchondral bone. Thus, nerves that innervate bone should be considered important targets for development of mechanism-based therapies to treat pain in late OA.
... The antinociceptive effect of morphine for spontaneous pain at rest and during movement has previously been reported in rat models of osteoarthritis (Adães et al., 2014;Ishikawa et al., 2014), showing consistency with the efficacy observed in patients (Caldwell et al., 2002). However, no study, to our knowledge, has tested the effect of oxycodone in an animal model of osteoarthritic pain, with the exception of an in vivo electrophysiology assay reporting that oxycodone reduces the response of spinal dorsal horn neurons to noxious knee joint rotation in the MIA sensitised rat (Miranda et al., 2014). Therefore, this is the first study to compare the analgesic profiles of morphine and oxycodone in osteoarthritic rats. ...
Oxycodone and morphine are two opioid drugs commonly used for the treatment of moderate to severe pain. However, their use in the management of noncancer pain remains a controversial issue and, in this respect, the evidence on their effectiveness and safety, particularly in osteoarthritis, is being questioned. In order to analyse their analgesic profile, two different pain models in rats were used: the formalin-induced inflammatory pain and the monosodium iodoacetate (MIA)-induced knee osteoarthritic pain. Drugs were administered systemically (i.p.) and their antinociceptive effect and potency were assessed. In the formalin test, both morphine and oxycodone produced a dose-dependent antinociceptive effect, but oxycodone outdid morphine in terms of effectiveness and potency (nearly two times) in the early (acute nociceptive) as in the late phase (inflammatory). In the osteoarthritis model, both drugs reduced movement–evoked pain (knee-bend test), mechanical allodynia (von Frey test) and heat hyperalgesia (Plantar test). Pretreatment with naloxone and naloxone methiodide reduced morphine and oxycodone effects. Peripheral mu-opioid receptors play a crucial role in the antinociceptive effect of both drugs on movement-evoked pain and heat hyperalgesia, but not on tactile allodynia.
The main finding of our study is that oxycodone has a better antinociceptive profile in the inflammatory and osteoarthritic pain, being more effective than morphine at 14 days post-MIA injection (phase with neuropathic pain); it overcame the morphine effect by improving the movement-induced pain, tactile allodynia and heat hyperalgesia.
Therefore, oxycodone could be an interesting option to treat patients suffering from knee osteoarthritis when opioids are required.
... 22,23 Miranda et al, using in vivo electrophysiology, found that oxycodone reduced the response of spinal dorsal horn neurons to noxious knee joint rotation in monosodium iodoacetate-sensitized rats, suggesting a regulatory effect of oxycodone in the spinal cord. 24 A previous study by Hassan et al that involved microarray profiling and gene mapping analysis clarified that oxycodone indeed modulated gene expression and regulated many biological processes such as immune response and the transmembrane receptor tyrosine kinase signaling pathway in rats repeatedly treated with oxycodone. 25 A recent study used unbiased RNA sequencing to examine gene expression in a mouse model of 14-day oxycodone self-administration and found that oxycodone administration altered the expression of numerous inflammatory and immune-related genes in the striatum. ...
Background
Oxycodone, which is one of the most commonly used opiates in postoperative pain management, has a different affinity for μ-opioid receptors (MOR), κ-opioid receptors (KOR), and δ-opioid receptors (DOR). Accumulating research has suggested that neurotrophins (NTs) are involved in opioid analgesia. In the current exploratory study, we aimed to investigate the underlying mechanisms of the analgesic effects of oxycodone on post-surgery pain in rats and to determine whether neurotrophic factors and receptors were involved in these effects.
Methods
Mechanical and thermal sensitivity tests were used to evaluate the validity of the postoperative pain rat model and to determine the analgesic effect of oxycodone. Quantitative PCR and Western blot analysis were used to detect the changes in the expression of three types of opioid receptors and NTs and their high-affinity receptors in the spinal cord after surgery and oxycodone administration.
Results
Oxycodone showed an analgesic effect on plantar incision (PI)-induced hyperalgesia, especially thermal hyperalgesia. We detected an obvious increase in MOR expression levels but insignificant changes in KOR and DOR levels in the spinal cord after PI. Moreover, we found that oxycodone was able to reverse the increased expression of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor (TrK) A, and TrkB and the decreased expression of NT-3 and TrkC, after PI. Pretreatment with oxycodone also altered the expression of these mediators.
Conclusion
Based on the results, possible underlying mechanisms for the antinociceptive properties of oxycodone in acute postoperative pain include the activation of MOR downstream signaling and the regulation of NTs and receptor expression through attenuation of glial activation and fortification of antinociceptive mediators in the spinal cord. This study may provide new insights into the molecular mechanisms underlying the analgesic action of oxycodone.
... So far, however, they are virtually nonexistent in preclinical experiments. We performed text-mining of the complete PubMed Central Open Access subset (time frame: 2010-2014) and found only one article explicitly describing an original study evaluating a treatment in rats or mice using a sequential design [15] (S1 Text). ...
Despite the potential benefits of sequential designs, studies evaluating treatments or experimental manipulations in preclinical experimental biomedicine almost exclusively use classical block designs. Our aim with this article is to bring the existing methodology of group sequential designs to the attention of researchers in the preclinical field and to clearly illustrate its potential utility. Group sequential designs can offer higher efficiency than traditional methods and are increasingly used in clinical trials. Using simulation of data, we demonstrate that group sequential designs have the potential to improve the efficiency of experimental studies, even when sample sizes are very small, as is currently prevalent in preclinical experimental biomedicine. When simulating data with a large effect size of d = 1 and a sample size of n = 18 per group, sequential frequentist analysis consumes in the long run only around 80% of the planned number of experimental units. In larger trials (n = 36 per group), additional stopping rules for futility lead to the saving of resources of up to 30% compared to block designs. We argue that these savings should be invested to increase sample sizes and hence power, since the currently underpowered experiments in preclinical biomedicine are a major threat to the value and predictiveness in this research domain.
... Moreover, the development of urinary bladder cancer has been demonstrated to be inhibited by Nap treatment, but the detailed molecular mechanism as well as the binding targets remained unclear. [22][23][24][25][26][27][28][29] Recently, we designed and synthesized several types of Nap-modied peptide dendrimers with good drug-delivery properties. [30][31][32][33][34][35] In addition, the peptide dendrimers constituted by glutamic acid or aspartic acid exhibited potent selectivity to bone tissues. ...
The aim of the current study was to synthesize and prepare novel self-assembly micelles loaded with curcumin (Cur) based on naproxen (Nap)-conjugated amphiphilic dendrimers. The apoptosis-inducing capacity of Nap-conjugated dendrimers and curcumin, the efficiency of uptake and the potential molecular mechanism on human osteosarcoma cells were investigated. The Nap-conjugated amphiphilic dendrimers were successfully synthesized, and the corresponding Cur-loaded micelles were conventionally prepared via self-assembly. These micelles showed good drug-encapsulating capacity, physiochemical properties, and drug-release profiles. The cellular proliferation and uptake assay suggested that the Cur-M-Nap induced more apoptosis of MG-63 human osteosarcoma cells. The western blot results suggested that these Nap-modified micelles could enhance the Cur-inducing apoptosis, mainly via intrinsic pathways and inhibition of the inflammation pathway. In summary, the Cur-loaded amphiphilic dendrimer-based micelles were successfully developed and they enhanced drug delivery to MG-63 cells. Mechanistic experiments suggested that Cur loaded into amphiphilic dendrimer-based micelles had a higher proliferation-inhibiting ability than free Cur, and could induce more apoptosis.
... The value of the Assay Capability Tool is becoming recognized externally. It was first shared in a paper by Miranda et al. (2014) when describing the development of a preclinical physiological assay to test modulation of knee joint pain in the spinal cord. That paper contained a case study of its use and was a highlighted publication on the National Centre for the 3Rs September e-newsletter (http://www.nc3rs.org.uk/nc3rs-e-newsletter-september-2014). ...
Numerous articles in Nature, Science, Pharmacology Research and Perspectives, and other biomedical research journals over the past decade have highlighted that research is plagued by findings that are not reliable and cannot be reproduced. Poor experiments can occur, in part, as a consequence of inadequate statistical thinking in the experimental design, conduct and analysis. As it is not feasible for statisticians to be involved in every preclinical experiment many of the same journals have published guidelines on good statistical practice. Here, we outline a tool that addresses the root causes of irreproducibility in preclinical research in the pharmaceutical industry. The Assay Capability Tool uses 13 questions to guide scientists and statisticians during the development of in vitro and in vivo assays. It promotes the absolutely essential experimental design and analysis strategies and documents the strengths, weaknesses, and precision of an assay. However, what differentiates it from other proposed solutions is the emphasis on how the resulting data will be used. An assay can be assigned a low, medium, or high rating to indicate the level of confidence that can be afforded when making important decisions using data from that assay. This provides transparency on the appropriate interpretation of the assay's results in the light of its current capability. We suggest that following a well-defined process during assay development and use such as that laid out within the Assay Capability Tool means that whatever the results, positive or negative, a researcher can have confidence to make decisions upon and publish their findings.
Background and purpose:
Benzodiazepines (BZDs), non-selective positive allosteric modulators (PAMs) of GABAA receptors, have significant side-effects that limit their clinical utility. As many of these side-effects are mediated by the α1 subunit there has been a concerted effort to develop α2/3 subtype-selective PAMs.
Experimental approach:
In vitro screening assays were used to identify molecules with functional selectivity for receptors containing α2/3 subunits over those containing α1 subunits. In vivo receptor occupancy (RO) was conducted, prior to confirmation of in vivo α2/3 and α1 pharmacology through quantitative EEG (qEEG) beta frequency and zolpidem drug-discrimination in rats, respectively. PF-06372865 was then progressed to Phase 1 clinical trials.
Key results:
PF-06372865 exhibited functional selectivity for those containing α2/3/5 subunits, with significant positive allosteric modulation (90-140%), but negligible activity (≤20%) at GABAA receptors containing α1 subunits. PF-06372865 exhibited concentration-dependent occupancy of GABAA receptors in pre-clinical species. There was an occupancy-dependent increase in qEEG beta frequency and no generalisation to a GABAA α1 cue in the drug-discrimination assay, clearly demonstrating the lack of modulation at the GABAA receptors containing an α1 subtype. In a Phase 1 single ascending dose study in healthy volunteers, evaluation of the pharmacodynamics (PD) of PF-06372865 demonstrated a robust increase in saccadic peak velocity (SPV) (a marker of α2/3 pharmacology), increases in beta frequency qEEG and a slight saturating increase in body sway.
Conclusions and implications:
PF-06372865 has a unique clinical pharmacology profile and a highly predictive translational data package from preclinical species to the clinical setting.
We examine the antioxidant role of young and senescent human umbilical vein endothelial cells (HUVECs) and their microvesicles (MVs). Proteomic and Western blot studies have shown young HUVECs to have a complete and well-developed antioxidant system. Their MVs also contain antioxidant molecules, though of a smaller and more specific range, specialized in the degradation of hydrogen peroxide and the superoxide anion via the thioredoxin-peroxiredoxin system. Senescence was shown to be associated with a large increase in the size of the antioxidant machinery in both HUVECs and their MVs. These responses might help HUVECs and their MVs deal with the more oxidising conditions found in older cells. Functional analysis confirmed the antioxidant machinery of the MVs to be active and to increase in size with senescence. No glutathione or nonpeptide antioxidant (ascorbic acid and vitamin E) activity was detected in the MVs. Endothelial cells and MVs seem to adapt to higher ROS concentrations in senescence by increasing their antioxidant machinery, although this is not enough to recover completely from the senescence-induced ROS increase. Moreover, MVs could be involved in the regulation of the blood plasma redox status by functioning as ROS scavengers.
