Browse by Audience
Among postmenopausal women with estrogen receptor-positive breast cancer, more than 80% receive hormone therapy including aromatase inhibitors (AIs). Half of them develop chronic arthralgia – characterized by symmetric articular pain, carpal tunnel syndrome, morning stiffness, myalgia and a decrease in grip strength – which is associated with treatment discontinuation. Only a few animal studies have linked AI treatment to nociception, and none to arthralgia. Thus, we developed a new chronic AI-induced nociceptive disorder model mimicking clinical symptoms induced by AIs, using subcutaneous letrozole pellets in ovariectomized (OVX) rats. Following plasma letrozole dosage at the end of the experiment (day 73), only rats with at least 90 ng/mL of letrozole were considered significantly exposed to letrozole (OVX + high LTZ group), whereas treated animals with less than 90 ng/mL were pooled in the OVX + low LTZ group. Chronic nociceptive disorder set in rapidly and was maintained for more than 70 days in the OVX + high LTZ group. Furthermore, OVX + high LTZ rats saw no alteration in locomotion, myalgia or experimental anxiety during this period. Bone parameters of the femora were significantly altered in all OVX rats compared to Sham+vehicle pellet. A mechanistic analysis focused on TRPA1, receptor suspected to mediate AI-evoked pain, and showed no modification in its expression in the DRG. This new long-lasting chronic rat model, efficiently reproduces the symptoms of AI-induced nociceptive disorder affecting patients' daily activities and quality-of-life. It should help to study the pathophysiology of this disorder and to promote the development of new therapeutic strategies.
Learn More >Dysregulation of the protease-antiprotease balance in the gastrointestinal tract has been suggested as a mechanism underlying visceral hypersensitivity in conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). We aimed to study the potential therapeutic role of an intracolonically administered serine protease inhibitor for the treatment of abdominal pain in a post-inflammatory rat model for IBS. An enema containing 2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to induce colitis in male Sprague-Dawley rats, whereas controls received a saline solution. Colonoscopies were performed to confirm colitis and follow-up mucosal healing. In the post-inflammatory phase, the serine protease inhibitor UAMC-00050 (0.1-5 mg/kg) or its vehicle alone (5% DMSO in HO) was administered in the colon. Thirty minutes later, visceral mechanosensitivity to colorectal distensions was quantified by visceromotor responses (VMRs) and local effects on colonic compliance and inflammatory parameters were assessed. Specific proteolytic activities in fecal and colonic samples were measured using fluorogenic substrates. Pharmacokinetic parameters were evaluated using bioanalytical measurements with liquid chromatography-tandem mass spectrometry. Post-inflammatory rats had increased trypsin-like activity in colonic tissue and elevated elastase-like activity in fecal samples compared to controls. Treatment with UAMC-00050 decreased trypsin-like activity in colonic tissue of post-colitis animals. Pharmacokinetic experiments revealed that UAMC-00050 acted locally, being taken up in the bloodstream only minimally after administration. Local administration of UAMC-00050 normalized visceral hypersensitivity. These results support the role of serine proteases in the pathophysiology of visceral pain and the potential of locally administered serine protease inhibitors as clinically relevant therapeutics for the treatment of IBS patients with abdominal pain.
Learn More >Research has shown that opioid craving is one of the strongest determinants of opioid misuse in patients with chronic pain. To date, however, little is known on the factors that contribute to opioid craving in these patients. It is possible that patients' physical dependence to opioids, manifested by opioid withdrawal symptoms in between daily opioid doses, contribute to opioid craving. Physical dependence symptoms might also lead to psychological distress, which in turn might contribute to opioid craving. The first objective of this study was to examine the day-to-day association between opioid withdrawal symptoms and opioid craving among patients with chronic pain. We also examined whether negative affect and catastrophic thinking mediated this association.
Learn More >Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by inflammation and debilitating pain. CRPS patients with pain refractory to more conventional analgesics can be treated with subanesthetic doses of ketamine. Our previous studies found that poor responders to ketamine had a 22-fold downregulation of the miRNA hsa-miR-605 in blood prior to ketamine treatment. Hence, we sought to investigate the functional significance of miR-605 downregulation and its impact on target gene expression, as investigating target mRNAs of differentially expressed miRNAs can provide important insights on aberrant gene expression that may contribute to disease etiology. Using a bioinformatics prediction, we identified that miR-605 can target the proinflammatory chemokine CXCL5, which plays a role in leukocyte recruitment and activation. We hypothesized that downregulation of miR-605 in poor responders to ketamine could increase CXCL5 expression and thereby contribute to inflammation in these patients. We confirmed that miR-605 regulates CXCL5 by using a miRNA mimic and inhibitor in human primary endothelial cells. Inhibition of miR-605 increased CXCL5 secretion and migration of human monocytic cells, thereby demonstrating a functional impact of miR-605 on chemotaxis. Additionally, CXCL5 mRNA was upregulated in whole blood from poor responders to ketamine, and CXCL5 protein was increased in plasma from CRPS patients. Thus, our studies suggest that miR-605 regulation of CXCL5 can regulate inflammation.
Learn More >Mirogabalin besylate has been approved in several countries to treat peripheral neuropathic pain. This pooled analysis, using data from the two pivotal Phase III studies in Asian patients with diabetic peripheral neuropathic pain and post-herpetic neuralgia, aimed to provide clinicians with more detailed and precise information relating to mirogabalin's safety and efficacy.
Learn More >Patients with episodic migraine (EM) with a higher-frequency of migraine headache days (HFEM: 8-14 migraine headache days/month) have a greater disease burden and a higher risk of progressing to chronic migraine (CM) with associated acute treatment overuse versus those with low-frequency EM (LFEM: 4-7 migraine headache days/month). In this post hoc analysis, we assessed the proportions of patients who shifted from HFEM to LFEM and to very low-frequency EM (VLFEM: 0-3 migraine headache days/month) status following treatment with galcanezumab versus placebo.
Learn More >Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that exist in three isoforms: PPARα, PPARβ/δ and PPARγ. Studies suggest that the PPAR signalling system may modulate pain, anxiety and cognition. The aim of the present study was to investigate whether endogenous signalling via PPARs differentially modulates innate anxiety responses and mnemonic function in the presence and absence of inflammatory pain. We examined the effects of intraperitoneal administration of GW6471 (PPARα antagonist), GSK0660 (PPARβ/δ antagonist), GW9662 (PPARγ antagonist), and -palmitoylethanolamide (PEA) on rat behaviour in the elevated plus maze (EPM), open field (OF), light-dark box (LDB), and novel object recognition (NOR) tests in the presence or absence of chronic inflammatory pain. Complete Freund's Adjuvant (CFA)-injected rats exhibited impaired recognition and spatial mnemonic performance in the NOR test and pharmacological blockade of PPARα further impaired spatial memory in CFA-treated rats. -oleoylethanolamide (OEA) levels were higher in the dorsal hippocampus in CFA-injected animals compared to their counterparts. The results suggest a modulatory effect of CFA-induced chronic inflammatory pain on cognitive processing, but not on innate anxiety-related responses. Increased OEA-PPARα signalling may act as a compensatory mechanism to preserve spatial memory function following CFA injection.
Learn More >Functional abdominal pain disorders (FAPDs) are common in childhood, impacting quality of life and school attendance. There are several compounds available for the treatment of pediatric FAPDs, but their efficacy and safety are unclear because of a lack of head-to-head randomized controlled trials (RCTs).
Learn More >: Erenumab, a monoclonal antibody targeting the receptor of calcitonin gene related peptide (CGRP), is the first disease-specific and mechanism-based treatment approved for the prevention of migraine. Although the safety and tolerability data from randomized trials are clear, the physiological effects of CGRP rise reasonable concerns. We aimed to evaluate the current evidence for safety and tolerability related to erenumab use in migraine.: This review outlines the severe adverse events (AEs), common AEs, AEs leading to treatment discontinuation and AEs of special interest, reported in all phase 2, phase 3, open label and observational studies with erenumab in migraine. Individual safety reports were also included in the systematic review of evidence.: No safety and tolerability flags were detected in this review. The most common AE are local skin reactions and constipation. No severe AEs, or frequent AEs leading to treatment discontinuation were detected. Treatment is well tolerated. The only AE of interest that may play a role in decision making and treatment monitoring is constipation. These findings are in line with previous safety reports, further highlighting the substantial tolerability and safety profile of the modern anti-CGRP monoclonal antibodies for the prevention of migraine.
Learn More >Opioids play an important role in pain relief, but repeated exposure results in tolerance and dependence. To make opioids more effective and useful, research in the field has focused on reducing the tolerance and dependence for chronic pain relief. Here, we showed the effect of ABIN-1 in modulating morphine function. We used hotplate tests and CPP tests to show that overexpression of ABIN-1 in the mice brain attenuated morphine dependence. These effects of ABIN-1 are most likely mediated through the formation of ABIN-1-β-arrestin2 complexes, which accelerate β-arrestin2 degradation by ubiquitination. With the degradation of β-arrestin2, ABIN-1 overexpression also decreased MOR phosphorylation and internalization following opioid treatment, affecting the β-arrestin2-dependent signaling pathway to regulate morphine tolerance. Importantly, the effect of ABIN-1 on morphine tolerance was abolished in β-arrestin2 knockout mice. Taken together, these results suggest that the interaction between ABIN-1 and β-arrestin2 inhibits MOR internalization to attenuate morphine tolerance, revealing a novel mechanism for MOR regulation. Hence, ABIN-1 may be a therapeutic target to regulate MOR internalization, thus providing a foundation for a novel treatment strategy for alleviating morphine tolerance and dependence. ABIN-1 overexpression in mice brain attenuated morphine tolerance and dependence. The mechanism may be that ABIN-1-β-arrestin-2 complex formation facilitated β-arrestin-2 degradation by ubiquitination. ABIN-1 targeted β-arrestin2 to regulate morphine tolerance Therefore, inhibiting of ABIN-1 is an important strategy to prevent morphine tolerance and dependence.
Learn More >