Analgesic Effect Research Articles

Vertebral osteoporotic fractures: differential diagnosis, therapeutic approaches

Osteoporotic vertebral fractures (OVF) are a severe complication of osteoporosis associated adverse outcomes, acute and chronic pain syndrome. If vertebral fractures (deformities) are detected, osteoporosis is diagnosed regardless of bone mineral density and the 10-year absolute fracture risk scale of the Fracture Risk Assessment Tool, but subject to the exclusion of other metabolic osteopathies. The article presents differential diagnosis of OVF with osteopathies such as osteomalacia, tumors or metastatic lesions of the spine, Paget»s disease, myeloma, hyper parathyroid osteodystrophy, post-traumatic vertebral deformities, Scheuermann-Mau disease. Differential diagnosis between different types of osteopathies is based on features of the clinical picture, history, changes in laboratory parameters (calcium, phosphorus, alkaline phosphatase, parathyroid hormone, vitamin D3 and on data from X-ray of the skeleton examination. It is necessary to take into account conditions under which the vertebral fracture occurred, its localization, prevalence, peculiarities of changes in bone structures, presence or absence of osteoporotic background, degenerative-dystrophic changes in the spine. The tactics of managing the patients with OVF is determined by the time after the fracture, its severity, nature of the pain syndrome and includes non-drug and medical measures. Among non-pharmaceutical measures in the acute period of OVF, there are unloading of the spinal column, use of a corset, and physical therapy. Medical measures are aimed at pain relief using injectable and oral forms of nonsteroidal anti-inflammatory drugs, central acting muscle relaxants and anti-osteoporotic therapy. Dexketoprofen (Dexalgin) is the first-line drug for relief of acute pain in OVF which has a rapid and pronounced analgesic effect. For the anti-osteoporotic therapy, the drugs of choice are parenteral bisphosphonates, denosumab and teriparatide.

Herbal extracts in orofacial pain: a systematic review and direct and indirect meta-analysis

The pharmaceutical industry has been primarily focused on developing synthetic drugs to address orofacial pain (OFP)-related conditions. There is limited knowledge regarding the efficacy of the use of herbal extracts in treating OFP. A systematic review and a meta-analysis of 62 randomized controlled trials assessing the analgesic effects of herbal extracts on pain intensity in various orofacial conditions was conducted. The intervention comprised the use of herbal extracts compared with a placebo and/or standard treatment. The primary outcome was pain intensity assessed before and after the intervention. The pain scores were compared with the baseline scores in each treatment. When compared with standard therapy, the pooled results of the patients who received herbal extracts revealed lower pain intensity in periodontal pain (MD = -0.92[-6.69, 4.85]), oral surgery pain (MD = 18.80[8.80, 28.79]), oral neuropathic pain (MD = 20.34[6.16, 34.52]), endodontic pain (MD = -8.04[-11.72, -4.37]), oral mucosal pain (MD = 8.74[2.76, 14.73]), and temporomandibular pain (MD = 30.94[6.04, 55.83]). The findings indicated a pain-attenuating effect of herbal extracts such as cannabis, turmeric, capsaicin, licorice, ginger, chamomile, clove, Hypericum perforatum, and Arnica montana. These findings revindicate that herbal extracts may be valuable alternatives to traditional pain medications and promising source for the development of new active ingredients for pharmaceuticals.

Validity evaluation of a rat model of monoiodoacetate-induced osteoarthritis with clinically effective drugs

BackgroundKnee osteoarthritis (KOA) is the most common type of joint disease in elderly people and is characterized by pain and dysfunction. Although the monoiodoacetate (MIA)-induced model is widely used as a rodent KOA model, it is important to acknowledge the inherent limitations of this model, as the MIA model develops complex pathological phases on a daily basis. An accurate understanding of this model and the selection of an appropriate time point according to the target for drug candidates can lead to the development of clinically effective drugs.MethodsChanges in the pathological state of the MIA model were assessed via histopathological evaluation. Clodronate, a bisphosphonate, and diclofenac, a nonsteroidal anti-inflammatory drug (NSAID), were selected as models of clinically effective drugs due to their different mechanisms of action. The analgesic effects of both drugs on the MIA model were evaluated. The long-term effect of clodronate on subchondral bone osteoclasts was also evaluated.ResultsHistopathological evaluation revealed that MIA-induced symptomatic behavior occurred in the early and late phases and was accompanied by synovial inflammation and osteoclast-related joint degeneration, respectively. Although clodronate inhibited symptomatic behavior and prevented cartilage degeneration from the early to late phases, diclofenac inhibited symptomatic behavior only in the early phase. Clodronate acted locally and inhibited the activation of subchondral osteoclasts.ConclusionsPathological changes, such as synovial changes in the early phase and knee joint degeneration in the late phase, in the MIA model are similar to those in human KOA. Our results indicate that the early phase in the MIA model is appropriate for evaluating the effects of anti-inflammatory agents such as NSAIDs and corticosteroids. The late phase in the MIA model is appropriate for evaluating the effects of drugs that act on cartilage and subchondral bone.

Unveiling the anxiolytic and analgesic effects of citronellal in Swiss mice: in vivo and in silico insights into COX and GABAA receptor pathways.

This study aims to evaluate the analgesic and anxiolytic effects of citronellal (CTL) in Swiss mice using two new sensitive and economic mouse models along with possible molecular mechanisms through in silico studies. For this, we employed marble displacement and spiked-field apparatus to check the anxiolytic and analgesic effects, respectively. In silico studies were done against cyclooxygenase (COX) enzymes and GABAA receptor subunits. Findings suggest that the test sample CTL significantly reduced the number of marbles displaces (NMD), square crosses (NSC), paw massages (NPM), and escaping attempts (NEA) in animals than the control group. CTL exhibited better effects in the perforated-field study compared to the reference drug diclofenac sodium. In both cases, CTL (200mg/kg) significantly reduced the test parameters when combined with the standard drugs (diazepam or diclofenac sodium). In in silico studies, CTL showed binding affinities of - 5.5, - 5.2, - 4.8, and - 4.8kcal/mol with the COX1, COX2, and GABAA receptors (α2 and α3 subunits), respectively. Taken together, CTL may exert anxiolytic- analgesic-like effects on mice, possibly through the GABAA receptor and COXs interaction pathways. These new tools might be used to check the anxiolytic and analgesic properties of a wide variety of test substances.

Interaction of meloxicam derivatives with phosphatidylcholine bilayers: A calorimetric study.

The drug interactions with the lipid membranes are crucial in many biochemical processes. Phospholipid model membranes are often used to assess such interactions. Our team has been researching new compounds with anti-inflammatory and analgesic effects for many years. Such compounds are derivatives of the well-known non-steroidal anti-inflammatory drug (NSAID) - meloxicam (MLX). Their biological target is cyclooxygenase (COX) - a membrane protein. The NSAIDs are mainly taken orally; therefore, drug-membrane interaction is a preliminary stage in the body. The purpose of the present work was to investigate the ability of 2 new MLX derivatives (compound PR51 and PR52) to interact with model membranes, in comparison to known NSAIDs medicine - MLX. The differential scanning calorimetry (DSC) method was used to study those interactions. As a model membrane, bilayers obtained from a phospholipid (1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC)) were used. Calorimetric measurements were performed using a differential scanning calorimeter DSC 214 Polyma equipped with an intracooler IC70. All examined compounds decreased the main transition temperature of DPPC in a concentration-dependent manner. The addition of studied compounds to DPPC also resulted in broadening of the transition peaks. Moreover, all examined compounds decreased the enthalpy of the DPPC main phase transition. For all DPPC gel-liquid crystalline phase transition parameters, the most pronounced effects were found for PR51 compound. We have shown that the above interactions depend on the chemical structure of individual compound. All studied compounds alter biophysical properties of phospholipid bilayer.

Systemic quinpirole enhances tramadol analgesia in inflammatory pain, but not in neuropathic pain in male rats.

Pain is a morbidity or comorbidity with a high incidence that significantly impacts the well-being of patients. In this study, we evaluated the effects of systemic administration of tramadol, a weak mu-opioid receptor (MOR) agonist, plus quinpirole (a D2-like receptor agonist). The study was performed in naïve rats and in rats with induced inflammatory and neuropathic pain. To measure the antinociceptive effect of the drugs, thermonociceptive and mechanonociceptive stimuli were applied and the emotional aspects of pain were evaluated using conditional place preference (CPP) experiments. Systemic quinpirole produced an antinociceptive effect only in naïve male rats. In naïve female animals, a small but significant pronociceptive effect was observed following quinpirole application. Tramadol plus quinpirole in male animals reversed allodynia and hyperalgesia induced by inflammatory and neuropathic insults, which were not alleviated by either drug alone. CPP experiments revealed that systemic quinpirole plus tramadol treatment was effective only in an inflammatory pain model. To evaluate whether tolerance to the antinociceptive effect was prevented by the combination of the drugs, a repeated administration five-day trial of tramadol plus quinpirole was evaluated under inflammatory pain conditions; quinpirole only slightly prevented the antinociceptive tolerance of MOR agonists. D2-like agonists are effective adjuvants for treating painful conditions in combination with a low dose of MOR agonists. Our results could lead to an investigation of whether these dopaminergic drugs in combination with opioids might reduce the MOR agonist dose while obtaining a higher analgesic effect with fewer side effects in humans.

Analgesic effects of high-frequency rTMS on pain anticipation and perception

Previous studies suggest that pain perception is greatly shaped by anticipation, with M1 and DLPFC involved in this process. We hypothesized that high-frequency rTMS targeting these regions could alter pain anticipation and thereby reduce pain perception. In a double-blind, sham-controlled study, healthy participants received 10 Hz rTMS to M1, DLPFC, or a sham treatment. Assessments were conducted before, immediately after, and 60 min after stimulation, including laser-evoked potentials, pain ratings, and anticipatory EEG. M1-rTMS immediately reduced laser-evoked P2 amplitude, increased sensorimotor high-frequency α-oscillation power, and accelerated peak alpha frequency in the midfrontal region during pain anticipation. In contrast, DLPFC-rTMS reduced the N2-P2 complex and pain ratings 60 min post-stimulation, an effect associated with prolonged microstate C duration during pain anticipation—a microstate linked to default mode network activity. Thus, M1-rTMS immediately modulates anticipatory α-oscillations and laser-evoked potentials, while DLPFC-rTMS induces delayed analgesic effects partially by modulating default mode network activity.

Identification and pharmacological properties of 2-(1H-indazole-3-carboxamido)-3,3-dimethylbutanoate (MDMB-INACA), N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1H-indazole-3-carboxamide (ADB-INACA), and N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-hexyl-1H-indazole-3-carboxamide (ADB-HINACA)

Synthetic cannabinoids (SCs) are an evolving class of new psychoactive substances (NPS) with structurally various compounds that are increasing over the past few years. Therefore, they are initially hard to identify because of the lack of analytical information. Moreover, there is little to no information regarding the pharmacology of these compounds despite human abuse. In the present study, gas chromatography-mass spectrometry (GC-MS), ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS), and nuclear magnetic resonance (NMR) spectroscopy were used to identify the structure of three compounds obtained from seized materials. The pharmacological properties of these compounds were evaluated by subsequent behavioral testing, including von Frey and cold allodynia tests. The results indicated that these compounds were determined to be 2-(1H-indazole-3-carboxamido)-3,3-dimethylbutanoate (MDMB-INACA), N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1H-indazole-3-carboxamide (ADB-INACA), and N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-hexyl-1H-indazole-3-carboxamide (ADB-HINACA) via GC-MS, UPLC-Q-TOF MS and NMR analysis, and they can attenuate mechanical and cold allodynia induced by paclitaxel in rats with peripheral neuropathy. Compared with MDMB-INACA and ADB-HINACA, ADB-INACA showed better analgesic effects on paclitaxel-induced peripheral neuropathy (PIPN) in rats, and its effect was similar to that of the positive drug N′-(1-hexyl-2-oxoindolin-3-ylidene) benzohydrazide (MDA-19).

Effects of Transcutaneous Electrical Nerve Stimulation (TENS) During Functional Activities or Exercise: A Systematic Review.

TENS is a non-pharmacological adjunctive treatment commonly recommended for analgesic purposes, with widespread use and acceptance in clinical practice; however, its effects simultaneously with exercise are controversial, and there are gaps regarding its effectiveness and applicability, especially regarding the parameters and protocols used to treat pain. In view of this, the aim of this study was to systematically review the effects of TENS applied simultaneously with functional activities or exercises in the treatment of individuals with pain. A bibliographic search was performed in electronic databases, including EMBASE, PubMED, Scopus, Web of Science, PEDro, SPORTDiscus, and the grey literature. The search yielded a total of 634 articles, of which only six met the inclusion criteria and were analysed individually. Of the selected studies, four evaluated the simultaneous use of TENS in patients with chronic pain, one in patients with fatigue-induced injury, and one in healthy subjects. The articles selected for synthesis of the review were assessed using the RoB 2.0 risk of bias tool, which found that three of the included studies had a low risk of bias, while two studies were analysed as high risk and only one with some concern. It is concluded that the use of TENS in conjunction with functional activities and exercises may benefit people with pain. The studies showed that the use of TENS with high frequency and intensity at the sensory threshold and applied simultaneously with exercise produced more significant analgesic effects, but new clinical trials with robust methodological designs should be carried out.

Cannabis combined with oxycodone for pain relief in fibromyalgia pain: a randomized clinical self-titration trial with focus on adverse events.

We determined whether adding cannabis to oxycodone for chronic non-cancer pain management could reduce treatment-related adverse effects (AEs) while maintaining effective analgesia. In this open-label study, fibromyalgia patients aged ≥18 years were randomized to receive 5 mg oxycodone tablets (max. four times/day), 150 mg of inhaled cannabis containing 6.3% Δ9-tetrahydrocannabinol and 8% cannabidiol (max. times inhalation sessions/day), or a combination of both for 6 weeks. The primary endpoint was treatment-related adverse events, assessed using a 10-point composite adverse event (cAE) score; additionally, we recorded daily reported pain relief and daily tablet and cannabis consumption. In total, 23 patients were treated with oxycodone, 29 with cannabis, and 29 with the oxycodone/cannabis combination. Three patients from the oxycodone group (13%) and 18 patients from the cannabis groups (31%, 9 in each group) withdrew from the trial within 2-3 weeks because of the severity of AEs. There were no differences in treatment-related cAE scores among the three groups that completed the study (p = 0.70). The analgesic responder rate showed a ≥1- point reduction in pain in 50% and a ≥2-point reduction in 20% of patients, while 50% of patients experienced no treatment benefit. The combination treatment reduced oxycodone tablet consumption by 35% (p = 0.02), but it did not affect the number of cannabis inhalation sessions. Cannabis combined with oxycodone offered no advantage over either treatment alone, except for a reduction in opioid tablet intake; however, the overall drug load was the highest in the combination group. Moreover, cannabis was poorly tolerated and led to treatment discontinuation in one-third of participants treated with cannabis. The trial was registered at the WHO International Clinical Trials Registry Platform (trialsearch.who.int) on July 26, 2019, identifier NL7902.

Analgesic and anti-inflammatory potential of Verbesina encelioides in rodents

Background: Verbesina encelioides, a plant with a rich history in traditional medicine, is the focus of our novel research. Commonly known as golden crownbeard or cowpen daisy, this plant has been used in various cultures for its medicinal properties. However, despite its widespread use, scientific validation of its therapeutic potential, particularly its analgesic and anti-inflammatory effects, remains limited. Objectives: Our study is designed to comprehensively evaluate the analgesic and anti-inflammatory effects of methanol extracts from various parts (leaves, stems, flowers, and roots) of Verbesina encelioides. We aim to achieve this by using established animal models. Our objectives include assessing pain-relieving properties through the Hot Plate and Tail Flick tests, investigating anti-inflammatory effects via the carrageenan-induced paw edema model, and determining safe dosage ranges through acute toxicity assays. Furthermore, our goals are to validate traditional medicinal uses, assess the effectiveness of various plant sections, and find probable bioactive chemicals that could be responsible for the observed pharmacological actions. This will provide Verbesina encelioides's medicinal use with a strong scientific foundation. Techniques: The study was carried out with great care and attention to detail. Methanol was used to collect, identify, and extract Verbesina encelioides. Acute toxicity, analgesic effects (heat plate and tail flick tests), and anti-inflammatory activity (carrageenan-induced inflammation) were tested in Swiss albino mice and Wistar albino rats. Findings: The acute toxicity assay showed no adverse effects in mice up to 1000 mg/kg, a highly encouraging result. In analgesic studies, Verbesina encelioides extracts showed dose-dependent increases in reaction times similar to aspirin. Different extracts had different effects on paw edema in anti-inflammatory testing; some at first increased inflammation but eventually showed significant decreases, especially at higher dosages. These results offer a positive perspective on Verbesina encelioides' possible medicinal use. Conclusion: These results provide a positive perspective on Verbesina encelioides' possible therapeutic use. The results imply that extracts from Verbesina encelioides, which are abundant in bioactive substances such as flavonoids, phenolics, and alkaloids, may have applications in treating pain and inflammation. Prospects for the future: These results highlight the plant's medicinal potential and suggest that more research and development could help address pain and inflammation naturally.

Incidence of side effects associated with acetaminophen in people aged 65 years or more: a prospective cohort study using data from the Clinical Practice Research Datalink.

The main objective of this study is to examine the safety of oral acetaminophen at its therapeutic dose in adults aged 65 years or more. This population-based cohort study used the Clinical Practice Research Datalink-Gold data. Participants were aged ≥65 years registered with a UK general practice for at least 12 months between 1998 and 2018. Acetaminophen exposure was defined as at-least two acetaminophen prescriptions within six-months of the first acetaminophen prescription, the first prescription date being the index-date. Acetaminophen non-exposure was defined as the absence of two acetaminophen prescriptions within six-months over the study period. We calculated propensity-score (PS) for acetaminophen prescription and undertook inverse probability treatment weighted (IPTW) using PS and PS-matched analyses to account for confounding. Missing data were handled using multiple imputation. The adjusted hazard-ratio (aHR) and 95% confidence-interval (CI) were calculated using the Cox-proportional hazards regression model. In total, 180,483 acetaminophen-users and 402,478 non-users were included in this study. Acetaminophen use was associated with an increased risk of peptic ulcer bleeding (aHR 1.24; 95% CI 1.16, 1.34), uncomplicated peptic-ulcers (aHR 1.20; 95% CI 1.10, 1.31), lower gastrointestinal-bleeding (aHR 1.36; 95% CI 1.29, 1.46), heart-failure (aHR 1.09; 95% CI 1.06, 1.13), hypertension (aHR 1.07; 95% CI 1.04, 1.11), and chronic kidney disease (aHR 1.19; 95% CI 1.13, 1.24). Despite its perceived safety, acetaminophen is associated with several serious complications. Given its minimal analgesic effectiveness, the use of acetaminophen as the first-line oral analgesic for long-term conditions in older people requires careful reconsideration.

Marine Peptides: Potential Basic Structures for the Development of Hybrid Compounds as Multitarget Therapeutics for the Treatment of Multifactorial Diseases

Marine-derived peptides display potent antihypertensive, antioxidant, analgesic and antimicrobial biological effects. Some of them have also been found to have anticancer activity via various mechanisms differing from those of continental organisms. This diversity of properties—together with the peptides’ efficacy, which has been confirmed in several in vitro and in vivo studies—make these compounds attractive as functional ingredients in pharmacy, especially in regard to multitarget drugs known as hybrids. Given the possibilities offered by chimeric structures, it is expected that a hybridization strategy based on a marine-derived compound could result in a long-awaited success in the development of new effective compounds to combat a range of complex diseases. However, despite the fact that the biological activity of such new hybrids may exceed that of their parent compounds, there is still an urgent need to carefully determine their potential off-targets and thus possible clinically important side effects. Given the above, the aim of this paper is to provide information on compounds of marine origin with peptide structures and to verify the occurrence and usage of hybrid compounds built from these structures. Furthermore, the authors believe that information presented here will serve to increase public awareness of the new opportunities arising from the combination of hybridization strategies with marine molecules with known structures and biological properties, thereby accelerating the development of effective drug candidates.

Efficacy of diclofenac transdermal patch versus injection as post-cesarean analgesia: A clinical, comparative, single-blind randomized control trial

Objectives: Post-operative pain is a common problem following cesarean delivery. The efficacy of topical application of diclofenac in alleviating pain has not been well established. We aim to evaluate the analgesic effect of transdermal diclofenac patch and compare it with the injectable form. Material and Methods: This is a prospective, randomized, single-blind, and placebo-controlled study. The study protocols and ethical considerations were adhered fully. Parturient women (n = 90) undergoing cesarean section were randomized into two equal groups: the transdermal diclofenac patch (Group A) and the injectable diclofenac (Group B). The surgery was performed under spinal anesthesia. The participant’s demographic data, clinical data, pain relief data collected, compiled, and analyzed using the Statistical Package for the Social Sciences 20. The post-operative pain was scored using Visual Analog Scale. Pain relief scores were compared between the groups using Mann–Whitney U-test and Wilcoxon matched-pair test. Results: The participants match in demographic and clinical characters. The pain relief scores at 12 h was – 3.10 ± 0.74 and 3.04 ± 0.21 respectively while at 24 hours was – 2.48 ± 0.51 and 2.09 ± 0.29 respectively in Group A and Group B. The difference between Group A and Group B was statistically significant (P = 0.0022). The pain relief scores in both groups match was statistically significant at 6–24 h and 6–48 h (P = 0.0001, 0.0001). Conclusion: Diclofenac transdermal patch gives equal pain relief as that of routine injectable formulation.

Erector spinae plane block versus quadratus lumborum block for abdominal surgery: A systematic review and meta-analysis.

The erector spinae plane block (ESPB) and quadratus lumborum block (QLB) are two novel interfascial plane block techniques with possible analgesic effects for both incisional and visceral pain. However, the results of the intercomparison of the two techniques for analgesia after abdominal surgery remain controversial. A systematic literature search was performed on five databases for randomized controlled trials comparing the analgesic efficacy of ESPB and QLB in abdominal surgery. The primary outcome was the 24 h postoperative intravenous IV morphine-equivalent consumption. A meta-analysis was performed using a random-effects model, with subgroup analyses based on the types of surgery and approaches of QLB. The 24 h postoperative IV morphine-equivalent consumption was lower in patients receiving ESPB than in those receiving QLB (MD -2.307mg; 95% CI ‒4.577 to -0.038; p=0.046; and I2=96.5%), though the reduction did not reach clinically meaningful difference. Static and dynamic pain at different postoperative time points, the time to first rescue analgesia, and the incidence of PONV showed no significant difference between the two groups. However, the QLB group demonstrated a significantly prolonged time in performing the block compared to the ESPB group (MD -2.985min; 95% CI -4.608 to -1.363; p<0.001; and I2=97.5%). Based on the available evidence from a systematic search of databases, the single-shot ESPB exhibits similar analgesic effects as QLB in abdominal surgery. The incidence of PONV was similar between the two techniques, with no block-related complications identified though QLB might be a more technically challenging approach than ESPB.

Discovery of novel cyclopentane carboxylic acids as potent and selective inhibitors of NaV1.7

Discovery efforts leading to the identification of cyclopentane carboxylic acid 31, a potent inhibitor of NaV1.7 that showed high selectivity over NaV1.5 and exhibited robust analgesic effects in an inherited erythromelalgia (IEM) transgenic mouse assay, are described herein. Key design elements that culminated in the discovery of 31 include exploration of proline substituents, replacement of the proline warhead with cyclopentane carboxylic acid, that led to significantly boosted NaV1.7 potency, and replacement of the metabolically labile adamantane motif with the 2,6-dichlorobenzyl substituted piperidine system, that addressed metabolic instability and led to a significant improvement in PK.

Botulinum toxin A dampened inflammatory response in BV-2 microglial cells

Our previous studies have demonstrated the analgesic effects of botulinum toxin type A (BoNT/A) in a pre-clinical model of rheumatoid arthritis of the temporomandibular joint, where we proposed that BoNT/A decreases the neurogenic milieu after reaching the subnucleus caudalis. However, it is unknown whether BoNT/A directly regulates microglial cell activity. Therefore, the present study investigates the effects of BoNT/A on a microglial murine cell lineage (BV-2) in different inflammatory conditions. Cellular viability and proliferation were carried out with different concentrations of BoNT/A (ranging from 0.3125 to 20 U/mL) for 24 h. Cells were primed with carrageenan (300 μg/mL) or Lipopolysaccharides (LPS) (20 ng/mL). The gene expression of IL-1β, IL-6, IL-18, TNF-α, Ikkβ, p65, Iba1 were quantified using PCR-RT. The supernatant was used to determine IL-1β, IL-6, and TNF-α levels. For all data, the significance level was set at 5%. Overall, data analysis revealed that BoNT/A 1.25 U/mL exhibited the greatest effect cell viability and proliferation. In addition, genes associated with inflammatory response in both stimuli (carrageenan and LPS) were downregulated in the presence of BoNT/A. Lastly, BoNT/A mitigates the protein levels of IL-1β and TNF-α in a time and dose-dependent manner. In conclusion, our results revealed that BoNT/A directly modulates the microglial cells' activities in an inflammatory context, opening new perspectives for using BoNT/A, considering its potential immunomodulatory effect.

Signal profiles and spatial regulation of β-arrestin recruitment through Gβ5 and GRK3 at the μ-opioid receptor

The μ-opioid receptor (MOR) is a G-protein-coupled receptor (GPCR) that mediates both analgesic effects and adverse effects of opioid drugs. Despite extensive efforts to develop a signal-biased drug, drugs with sufficiently reduced side effects have not been established, in part owing to lack of comprehensive signal transducer profiles of MOR. In this study, by profiling the activity of signal transducers including G proteins and GPCR kinases (GRKs), we revealed an unprecedented mechanism of selective GRK3 activation by Gβ5, leading to β-arrestin recruitment. By utilizing multiple genome-edited cell lines and functional assays, we found that oliceridine, an FDA-approved G-protein-biased agonist, selectively activates Gαz- and GRK3-mediated signaling. Notably, among the five Gβ subtypes, only Gβ5 distinguishes GRK3 from GRK2. Using single-molecule imaging, we found that GRK3 is recruited to the plasma membrane upon MOR agonist stimulation by Gβ1 and Gβ5, yet their interaction dynamics with GRK3 and mechanisms of action are different. Furthermore, particle diffusion analysis suggests that Gβ5 is enriched in confined membrane domains, through which GRK3 is recruited to the plasma membrane in a freely diffusible state, thereby allowing GRK3 to efficiently interact with MOR. These findings provide a mechanism by which MOR agonists rely on a specific Gα–Gβ–GRK axis to induce β-arrestin recruitment.

Sodium Carboxymethylcellulose Serves as Sustained-Release Agents for Providing Analgesia at the Donor Site After Costal Cartilage Harvesting in Ear Reconstruction.

The postoperative pain experienced at the donor site following ear reconstruction using autologous costal cartilage significantly impacts patients' quality of life. Sodium carboxymethylcellulose demonstrates a favorable sustained release property, and its potential to prolong the analgesic effect of ropivacaine remains unexplored. The present study aimed to investigate the analgesic efficacy of ropivacaine gel formulated with sodium carboxymethylcellulose as a sustained-release agent on the donor site of costalcartilage. A retrospective analysis was conducted on a total of 75 patients who underwent costal cartilage ear reconstruction. The patients were divided into three groups based on the different analgesic methods applied to the cartilage donor site: ropivacaine solution group, ropivacaine gel group, and ropivacaine solution combined with gel group. The visual analog scale (VAS) and patient-controlled analgesia (PCA) were used to evaluate the severity of chest pain. The study included a total of 60 patients undergoing ear reconstruction, with 20 patients in each group. The VAS chest pain score and the frequency of PCA application were lower in both the ropivacaine gel group and the ropivacaine solution combined with gel group compared to the ropivacaine solution group. There was no significant difference observed between the ropivacaine gel group and the ropivacaine solution combined with gel group. The utilization of sodium carboxymethyl cellulose as a sustained-release agent in the formulation of ropivacaine gel has been found to effectively prolong the duration of pain relief and alleviate postoperative discomfort at the donor site following ear reconstruction with costal cartilage harvesting. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Sex differences in the antinociceptive effect of codeine and its peripheral but not central metabolism in adult mice

Codeine is a natural opiate extracted from opium poppy (Papaver somniferum) and used to alleviate mild to moderate pain. The analgesic effect of this molecule results from its metabolism into morphine which is an agonist of the mu opioid receptor. Morphine's major metabolite morphine-3-glucuronide induces both thermal and mechanical hypersensitivies while codeine-6-glucuronide has been proposed to be antinociceptive. However, sex differences in codeine antinociceptive effect and pharmacokinetics were barely studied. To this purpose, we injected male and female mice with codeine (2.5, 5, 10, 20 and 40 mg/kg) and thermal hypersensitivity was assessed 30 min after injection using the Tail Immersion Test. Moreover, both peripheral and central metabolism of codeine were evaluated respectively in the blood or pain-related brain structures in the central nervous system. The amounts of codeine and its metabolites were quantified using the isotopic dilution method by liquid chromatography coupled to a mass spectrometer. Our results show that codeine induces a greater antinociceptive effect in males than females mice independently of the estrous cycle. Moreover, major sex differences were found in the peripheral metabolism of this molecule, with higher amounts of pronociceptive morphine-3-glucuronide and less antinociceptive codeine-6-glucuronide in females than in males. Concerning the central metabolism of codeine, we did not find significant sex differences in pain-related brain structures. Collectively, these findings support a greater codeine antinociceptive effect in males than females in mice. These sex differences could be influenced by a higher peripheral metabolism of this molecule in female mice rather than central metabolism.