Antinociception and anti-inflammation induced by simvastatin in algesiometric assays in mice

Rosuvastatin Synergistically Enhances the Antinociceptive Efficacy of Duloxetine in Paclitaxel-Induced Neuropathic Pain in Mice

Paclitaxel, a widely used cancer chemotherapeutic agent, has high incidence of neurotoxicity associated with the production of neuropathic pain, for which only duloxetine has shown significant but moderate analgesic effect. Since statins, classically used to reduce hypercholesterolemia, have shown antinociceptive effect in preclinical studies on neuropathic pain, we studied whether the antinociceptive efficacy of duloxetine could be synergistically potentiated by rosuvastatin in a model of paclitaxel-induced neuropathy in mice. The astrocytic and microglial responses in the spinal cord of paclitaxel-treated mice were also assessed by measuring GFAP and CD11b proteins, respectively. Paclitaxel treatment did not impair motor coordination and balance in rotarod testing. Rosuvastatin, duloxetine, and the rosuvastatin/duloxetine combination (combined at equieffective doses) dose-dependently decreased mechanical allodynia (ED₃₀, von Frey testing) and thermal hyperalgesia (ED₅₀, hot plate testing) in paclitaxel-treated mice. Isobolographic analysis showed a superadditive interaction for rosuvastatin and duloxetine, as both the ED₃₀ and ED₅₀ for the rosuvastatin/duloxetine combination contained only a quarter of each drug compared to the individual drugs. The rosuvastatin/duloxetine combination reversed paclitaxel-induced GFAP overexpression, indicating that such effects might depend in part on astrocyte inactivation. Results suggest that statins could be useful in synergistically enhancing the efficacy of duloxetine in some chemotherapy-induced neuropathic conditions.

Effect of Statins on Clinical Outcomes in Patients With Coronary Artery Spasm: A Meta-Analysis

PURPOSE

The purpose of this meta-analysis was to assess the effect of statins on major adverse cardiovascular events (MACE) related to coronary artery spasm (CAS) and to evaluate the effectiveness of statins in patients with CAS.

METHODS

A systematic search of electronic databases, including Google Scholar, the Cochrane Central Register of Controlled Trials, and PubMed, was conducted. These studies were all published in English, and the databases were searched from inception to July 2021. All articles were evaluated independently by 2 researchers on the basis of inclusion and exclusion criteria. In the research, data about the incidence of major adverse cardiovascular events in CAS patients undergoing statin therapy was included and divided into different subgroups. A random effects model was conducted to synthesize the data.

FINDINGS

Five cohort studies were included in the analysis. These results indicated that statins failed to reduce the incidence of stroke in patients with CAS in general. However, subgroup analysis revealed that statins were more effective in improving outcomes for CAS patients without severe coronary stenosis compared with those with severe coronary stenosis.

IMPLICATIONS

Statins may have a potential benefit in patients with CAS who do not have coronary stenosis. To investigate these findings further, future prospective, randomized controlled research will be required.

Synergistic interaction between B vitamins and statins to counter nociception in rats

Evidence suggests that the antinociceptive activity of various drugs can be increased when administered in combination with B vitamins (BVs). The aim of this study was to examine the potential interaction between statins and BVs to counter nociception, the latter measured by the formalin test. Rats were orally administered atorvastatin (1, 3, 10 and 30 mg/kg), pravastatin (1, 3, 10 and 30 mg/kg), rosuvastatin (1, 3, 10 and 30 mg/kg), BVs (31, 56, 100 and 180 mg/kg) or calculated combinations of BVs with each drug. The effective dose 30 (ED₃₀ ) was calculated for each statin and BVs and subjected to isobolographic analysis, thus finding the ED₃₀ of the combinations. The antinociceptive experimental ED₃₀ values for BVs administered with atorvastatin, pravastatin or rosuvastatin were 1.53 ± 0.38, 6.74 ± 0.04 and 4.26 ± 0.39, respectively, being lower (p < .05) than the corresponding theoretical ED₃₀ : 28.02 ± 2.20, 28.17 ± 2.20 and 29.86 ± 2.21. Since BVs likely boost the antinociceptive effect of statins, these combinations could possibly be advantageous in pain management.

Identification of novel analgesics through a drug repurposing strategy

The identification of new indications for approved or failed drugs is a process called drug repositioning or drug repurposing. The motivation includes overcoming the productivity gap that exists in drug development, which is a high-cost–high-risk process. Repositioning also includes rescuing drugs that have safely entered the market but have failed to demonstrate sufficient efficiency for the initial clinical indication. Considering the high prevalence of chronic pain, the lack of sufficient efficacy and the safety issues of current analgesics, repositioning seems to be an attractive approach. This review presents example of drugs that already have been repositioned and highlights new technologies that are available for the identification of additional compounds to stimulate the curiosity of readers for further exploration.

Are perioperative therapeutic doses of statins associated with postoperative pain and opioid consumption after hip surgery under spinal anaesthesia?

Background

The anti-inflammatory effects of statins have been suggested to relieve postoperative pain. This retrospective study tested the association between the perioperative routine use of statins in therapeutic doses, and opioid requirements and pain scores, after hip replacement surgery.

Methods

With IRB approval, data was obtained for adult patients who had elective hip replacement surgery under spinal anaesthesia at Cleveland Clinic between 2005 and 2015. Patients were compared using a joint hypothesis framework. We used the inverse probability of treatment weighting method to control for observed confounding factors (a total of 26).

Results

We included 611 statin users and 780 non-statin users. Pain score during the initial 72 h after surgery was 0.07 higher (95% CI: -0.02, 0.17) in statin users (noninferiority test in both directions P<0.001). The estimated ratio of geometric means in the cumulative i.v. morphine equivalent opioid consumption was 1.01 (95% CI: 0.93, 1.10) for statin vs non-statin users (noninferiority test P=0.001 in the hypothesized direction and<0.001 in the other direction) during the initial 72 h after surgery. The statin and non-statin patients were deemed equivalent on postoperative opioid consumption and pain score.

Conclusions

This is the first large retrospective clinical study that investigates the effects of statin use on postoperative pain and opioid consumption. We observed no difference between statin users and non-users during the initial 72 h after hip surgery. Our findings do not support the routine use of statins as part of an analgesic regimen.

Evaluation of cebranopadol, a dually acting nociceptin/orphanin FQ and opioid receptor agonist in mouse models of acute, tonic, and chemotherapy-induced neuropathic pain

BACKGROUND

Cebranopadol (a.k.a. GRT-6005) is a dually acting nociceptin/orphanin FQ and opioid receptor agonist that has been recently developed in Phase 2 clinical trials for painful diabetic neuropathy or cancer pain. It also showed analgesic properties in various rat models of pain and had a better safety profile as compared to equi-analgesic doses of morphine. Since antinociceptive properties of cebranopadol have been studied mainly in rat models, in the present study, we assessed analgesic activity of subcutaneous cebranopadol (10 mg/kg) in various mouse pain models.

METHODS

We used models of acute, tonic, and chronic pain induced by thermal and chemical stimuli, with a particular emphasis on pharmacoresistant chronic neuropathic pain evoked by oxaliplatin in which cebranopadol was used alone or in combination with simvastatin.

KEY RESULTS

As shown in the hot plate test, the analgesic activity of cebranopadol developed more slowly as compared to morphine (90-120 min vs. 60 min). Cebranopadol displayed a significant antinociceptive activity in acute pain models, i.e., the hot plate, writhing, and capsaicin tests. It attenuated nocifensive responses in both phases of the formalin test and reduced cold allodynia in oxaliplatin-induced neuropathic pain model. Its efficacy was similar to that of morphine. Used in combination and administered simultaneously, 4 or 6 h after simvastatin, cebranopadol did not potentiate antiallodynic activity of this cholesterol-lowering drug. Cebranopadol did not induce any motor deficits in the rotarod test.

CONCLUSION

Cebranopadol may have significant potential for the treatment of various pain types, including inflammatory and chemotherapy-induced neuropathic pain.

Effect of simvastatin on sensorial, motor, and morphological parameters in sciatic nerve crush induced-neuropathic pain in rats

The present study compares the effects of a low and high doses of simvastatin in a model of peripheral neuropathy by evaluating sensorial, motor, and morphological parameters. First, male Wistar rats were orally treated with vehicle (saline, 1 mL/kg), simvastatin (2 and 80 mg/kg) or morphine (2 mg/kg, s.c.), 1 h before 2.5% formalin injection. Neuropathic pain was induced by crushing the sciatic nerve, and mechanical and cold allodynia, nerve function, histology, MPO and NAG concentrations, as well as mevalonate induced-nociception were evaluated. Animals were orally treated with vehicle, simvastatin, or gabapentin (30 mg/kg) for 18 days. Simvastatin (2 and 80 mg/kg) reduced the inflammatory pain induced by formalin, but failed to decrease the paw edema. Mechanical allodynia was reduced by the simvastatin (2 mg/kg) until the 12th day after injury and until the 18th day by gabapentin. However, both simvastatin and gabapentin treatments failed in attenuated cold allodynia or improved motor function. Interestingly, both doses of simvastatin showed a neuroprotective effect and inhibited MPO activity without altering kidney and hepatic parameters. Additionally, only the higher dose of simvastatin reduced the cholesterol levels and the nociception induced by mevalonate. Our results reinforce the antinociceptive, antiallodynic, and anti-inflammatory effects of oral simvastatin administration, which can strongly contribute to the sciatic nerve morphology preservation. Furthermore, our data suggest that lower and higher doses of simvastatin present beneficial effects that are dependent and independent of the mevalonate pathway, respectively, without causing signs of nerve damage.

Antinociception induced by rosuvastatin in murine neuropathic pain

BACKGROUND

Neuropathic pain, and subsequent hypernociception, can be induced in mice by paclitaxel (PTX) administration and partial sciatic nerve ligation (PSNL). Its pharmacotherapy has been a clinical challenge, due to a lack of effective treatment. In two models of mouse neuropathic pain (PTX and PSNL) the antinociception induced by rosuvastatin and the participation of proinflammatory biomarkers, interleukin (IL)- 1β, TBARS and glutathione were evaluated.

METHODS

A dose-response curve for rosuvastatin ip was obtained on cold plate, hot plate and Von Frey assays. Changes on spinal cord levels of IL-1β, glutathione and lipid peroxidation were measured at 7 and 14days in PTX and PSNL murine models.

RESULTS

PTX or PSNL were able to induce in mice peripheral neuropathy with hypernociception, either to 7 and 14days. Rosuvastatin induced a dose dependent antinociception in hot plate, cold plate and Von Frey assays. The increased levels of IL-1β or TBARS induced by pretreatment with PTX or PSNL were reduced by rosuvastatin. The reduction of spinal cord glutathione, by PTX or PSNL, expressed as the ratio GSH/GSSG, were increased significantly in animals pretreated with rosuvastatin. The anti-inflammatory properties of statins could underlie their beneficial effects on neuropathic pain by reduction of proinflammatory biomarkers and activation of glia.

CONCLUSION

The findings of this study suggest a potential usefulness of rosuvastatin in the treatment of neuropathic pain.

Effects of Simvastatin Beyond Dyslipidemia: Exploring Its Antinociceptive Action in an Animal Model of Complex Regional Pain Syndrome-Type I

Simvastatin is a lipid-lowering agent that blocks the production of cholesterol through inhibition of 3-hydroxy-methyl-glutaryl coenzyme A (HMG-CoA) reductase. In addition, recent evidence has suggested its anti-inflammatory and antinociceptive actions during inflammatory and pain disorders. Herein, we investigated the effects of simvastatin in an animal model of complex regional pain syndrome-type I, and its underlying mechanisms. Chronic post-ischemia pain (CPIP) was induced by ischemia and reperfusion (IR) injury of the left hind paw. Our findings showed that simvastatin inhibited mechanical hyperalgesia induced by CPIP model in single and repeated treatment schedules, respectively; however simvastatin did not alter inflammatory signs during CPIP model. The mechanisms underlying those actions are related to modulation of transient receptor potential (TRP) channels, especially TRMP8. Moreover, simvastatin oral treatment was able to reduce the nociception induced by acidified saline [an acid-sensing ion channels (ASICs) activator] and bradykinin (BK) stimulus, but not by TRPA1, TRPV1 or prostaglandin-E2 (PGE2). Relevantly, the antinociceptive effects of simvastatin did not seem to be associated with modulation of the descending pain circuits, especially noradrenergic, serotoninergic and dopaminergic systems. These results indicate that simvastatin consistently inhibits mechanical hyperalgesia during neuropathic and inflammatory disorders, possibly by modulating the ascending pain signaling (TRPM8/ASIC/BK pathways expressed in the primary sensory neuron). Thus, simvastatin open-up new standpoint in the development of innovative analgesic drugs for treatment of persistent pain, including CRPS-I.

Simvastatin Attenuates Neuropathic Pain by Inhibiting the RhoA/LIMK/Cofilin Pathway

Neuropathic pain occurs due to deleterious changes in the nervous system caused by a lesion or dysfunction. Currently, neuropathic pain management is unsatisfactory and remains a challenge in clinical practice. Studies have suggested that actin cytoskeleton remodeling may be associated with neural plasticity and may involve a nociceptive mechanism. Here, we found that the RhoA/LIM kinase (LIMK)/cofilin pathway, which regulates actin dynamics, was activated after chronic constriction injury (CCI) of the sciatic nerve. Treatments that reduced RhoA/LIMK/cofilin pathway activity, including simvastatin, the Rho kinase inhibitor Y-27632, and the synthetic peptide Tat-S3, attenuated actin filament disruption in the dorsal root ganglion and CCI-induced neuropathic pain. Over-activation of the cytoskeleton caused by RhoA/LIMK/cofilin pathway activation may produce a scaffold for the trafficking of nociceptive signaling factors, leading to chronic neuropathic pain. Here, we found that simvastatin significantly decreased the ratio of membrane/cytosolic RhoA, which was significantly increased after CCI, by inhibiting the RhoA/LIMK/cofilin pathway. This effect was highly dependent on the function of the cytoskeleton as a scaffold for signal trafficking. We conclude that simvastatin attenuated neuropathic pain in rats subjected to CCI by inhibiting actin-mediated intracellular trafficking to suppress RhoA/LIMK/cofilin pathway activity.

Drug repositioning: playing dirty to kill pain

The number of approved new molecular entity drugs has been decreasing as the pharmaceutical company investment in research and development is increasing. As we face this painful crisis, called an innovation gap, there is increasing awareness that development of new uses of existing drugs may be a powerful tool to help overcome this obstacle because it takes too long, costs too much and can be risky to release drugs developed de novo. Consequently, drug repositioning is emerging in different therapeutic areas, including the pain research area. Worldwide, pain is the main reason for seeking healthcare, and pain relief represents an unmet global clinical need. Therefore, development of analgesics with better efficacy, safety and cost effectiveness is of paramount importance. Despite the remarkable advancement in research on cellular and molecular mechanisms underlying pain pathophysiology over the past three decades, target-based therapeutic opportunities have not been pursued to the same extent. Phenotypic screening remains a more powerful tool for drug development than target-based screening so far. It sounds somewhat heretical, but some multi-action drugs, rather than very selective ones, have been developed intentionally. In the present review, we first critically discuss the utility of drug repositioning for analgesic drug development and then show examples of 'old' drugs that have been successfully repositioned or that are under investigation for their analgesic actions. We conclude that drug repositioning should be more strongly encouraged to help build a bridge between basic research and pain relief worldwide.

Simvastatin ameliorates cauda equina compression injury in a rat model of lumbar spinal stenosis

Lumbar spinal stenosis (LSS) is the leading cause of morbidity and mortality worldwide. LSS pathology is associated with secondary injury caused by inflammation, oxidative damage and cell death. Apart from laminectomy, pharmacological therapy targeting secondary injury is limited. Statins are FDA-approved cholesterol-lowering drug. They also show pleiotropic anti-inflammatory, antioxidant and neuroprotective effects. To investigate the therapeutic efficacy of simvastatin in restoring normal locomotor function after cauda equina compression (CEC) in a rat model of LSS, CEC injury was induced in rats by implanting silicone gels into the epidural spaces of L4 and L6. Experimental group was treated with simvastatin (5 mg/kg body weight), while the injured (vehicle) and sham operated (sham) groups received vehicle solution. Locomotor function in terms of latency on rotarod was measured for 49 days and the threshold of pain was determined for 14 days. Rats were sacrificed on day 3 and 14 and the spinal cord and cauda equina fibers were extracted and studied by histology, immunofluorescence, electron microscopy (EM) and TUNEL assay. Simvastatin aided locomotor functional recovery and enhanced the threshold of pain after the CEC. Cellular Infiltration and demyelination decreased in the spinal cord from the simvastatin group. EM revealed enhanced myelination of cauda equina in the simvastatin group. TUNEL assay showed significantly decreased number of apoptotic neurons in spinal cord from the simvastatin group compared to the vehicle group. Simvastatin hastens the locomotor functional recovery and reduces pain after CEC. These outcomes are mediated through the neuroprotective and anti-inflammatory properties of simvastatin. The data indicate that simvastatin may be a promising drug candidate for LSS treatment in humans.

Ameliorative Effects of Scopoletin from Crossostephium chinensis against Inflammation Pain and Its Mechanisms in Mice

Scopoletin exists in nature as an anti-oxidant, hepatoprotective, and anti-inflammatory activities reagent. In this study, we have investigated the analgesic effects of the scopoletin using the models of acetic acid-induced writhing response and the formalin test, the anti-inflammatory effects of scopoletin using model of λ-carrageenan (Carr)-induced paw edema. The treatment of ICR mice with scopoletin inhibited the numbers of writhing response and the formalin-induced pain in the late phase. This study demonstrated that the administration of scopoletin resulted in the reduction of Carr-induced mice edema, and it increased the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) after Carr injection. We also demonstrated scopoletin significantly attenuated the malondialdehyde (MDA) level in the edema paw after Carr injection. Scopoletin decreased the NO, tumor necrosis factor (TNF-α) and prostaglandin E2 (PGE₂) levels on serum after Carr injection. Scopoletin decreased Carr-induced inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions in the edema paw. These anti-inflammatory mechanisms of scopoletin might be related to the decrease in the level of MDA via increasing the activities of SOD, CAT, and GPx in the edema paw. Also, scopoletin could affect the production of NO, TNF-α, and PGE₂, and therefore affect the anti-inflammatory effects.

Identification of novel APP/Abeta isoforms in human cerebrospinal fluid

BACKGROUND

Aggregation of beta-amyloid (Abeta) into oligomers and plaques is the central pathogenic mechanism in Alzheimer's disease (AD). Abeta is produced from the amyloid precursor protein (APP) by beta- and gamma-secretases, whereas, in the nonamyloidogenic pathway, alpha-secretase cleaves within the Abeta sequence, and thus precludes Abeta formation. A lot of research has focused on Abeta production and the neurotoxic 42-amino-acid form of Abeta (Abeta1-42), while less is known about the nonamyloidogenic pathway and how Abeta is degraded.

OBJECTIVE

To study the Abeta metabolism in man by searching for novel Abeta peptides in cerebrospinal fluid (CSF).

METHODS

Immunoprecipitation, using an anti-Abeta antibody, 6E10, was combined with either matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or nanoflow liquid chromatography and tandem mass spectrometry.

RESULTS

We identified 12 truncated APP/Abeta peptides in the CSF, all of which end at amino acid 15 in the Abeta sequence, i.e. 1 amino acid before the proposed alpha-secretase site. Of these 12 APP/Abeta peptides, 11 are novel peptides and start N-terminally of the beta-secretase site. The most abundant APP/Abeta peptide starts 25 amino acids before the beta-secretase site, APP/Abeta (-25 to 15), and had a concentration of approximately 80 pg/ml. The identity of all the APP/Abeta peptides was verified in a cohort of AD patients and controls. A first pilot study also showed that the intensity of several APP/Abeta peaks in CSF was higher in AD cases than in controls.

CONCLUSION

These data suggest an enzymatic activity that cleaves the precursor protein in a specific manner that may reflect a novel metabolic pathway for APP and Abeta.