Effect of intra-articular dexmedetomidine on experimental osteoarthritis in rats

Bone marrow mesenchymal stem cell exosome-derived lncRNA TUC339 influences the progression of osteoarthritis by regulating synovial macrophage polarization and chondrocyte apoptosis

Osteoarthritis (OA) is an extremely common type of chronic progressive disease in clinical practice. lncRNA TUC339 has a close association with bone marrow mesenchymal stem cell (BMSC) and an important impact on organismal inflammation. However, the mechanism of BMSC-derived lncRNA TUC339 on OA was poorly understood. In this study, we found that TUC339 was lower in the research group than in the control group and it was negatively correlated with IL-6, IL-8 and TNF-α. Prognosis TUC339 was lower in patients with recurrent OA than in those without recurrence, and ROC analysis manifested that TUC339 had a better predictive value for recurrence of OA. Phenotypic identification revealed elevated expression of CD29 and CD44 in BMSCs and TSG101, CD63 and CD81 in BMSCs-exosome (BMSCs-exo), with a stem cell versus exosome phenotype. Finally, animal experiments improved significantly in joint injury in the BMSCs-exo and TUC339-overexpression vector groups compared with control groups. Similarly, the activity of chondrocytes was enhanced, and apoptosis was reduced in the BMSCs-exo group versus the TUC339-overexpression vector group of rats. Study demonstrated that BMSCs-exo improves OA by elevating the expression of TUC339 to promote M1-type mø to M2-type polarization, suppressing inflammation and promoting chondrocyte activity, which provides a reliable basis for future transplantation therapy of MSCs for OA.

Evaluating the effects of rifampin in the prevention of neurogenic symptoms and cardiac arrhythmias caused by the systemic toxicity of lidocaine in rats

Lidocaine toxicity is caused by unintended intravascular injection or overdose. Lidocaine is metabolized in the liver by the CYP3A4 isoenzyme. The objective was to investigate if the administration of rifampin could accelerate animal recovery and reduce the symptoms of lidocaine toxicity by induction of the CYP3A4. Thirty-six male rats were divided into control and treatment groups, each containing three subgroups. The treatment group received oral rifampin suspension daily for 1 week. In all rats, 2.00% lidocaine was injected intravenously. The first subgroup was monitored for neurological symptoms. In the second subgroup, data were recorded after the electrode was placed in the right hippocampus. Electrocardiograms were taken from the third subgroup. CYP3A4 was measured using an ELISA kit. Neurological recovery was seen after 22 and 15 min in the control and treatment groups, respectively. Rifampin also caused a significant reduction in amplitude and number of field action potentials compared to the control group. Numerous cardiac arrhythmias were observed in the control group. The mean level of CYP3A4 in the treatment group was significantly higher than in the control group. In conclusion, oral rifampin could increase the synthesis of CYP3A4, therefore, the animal recovery from lidocaine toxicity was accelerated.

Dexmedetomidine alleviates osteoarthritis inflammation and pain through the CB2 pathway in rats

As a common joint disease, osteoarthritis (OA) is often associated with chronic pain. Synovial inflammation is correlated with OA progression and pain. Synovial inflammation can produce a series of destructive substances, such as inflammatory factors and pain mediators, which aggravate cartilage injury and further accelerate the progression of OA. Although many studies investigated the effects of synovial inflammation on the onset and progression of OA, there are limited reports regarding slowing the progression of OA and relieving pain by modulating synovial inflammation. Therefore, there is an urgent need to search for safe and effective drugs to alleviate synovial inflammation. Dexmedetomidine, a selective α₂ agonist, has been shown to have anti-inflammatory and analgesic effects. However, its role and mechanism in OA remain unclear. Here, the effects and mechanisms of dexmedetomidine in OA synovial inflammation were investigated both in vivo and in vitro. We observed that dexmedetomidine stunted LPS-induced migration and invasion of FLSs and the expression of inflammatory factors by upregulating cannabinoid receptor type 2 (CB₂) expression. Surprisingly, the application of AM630 (CB₂ antagonist) reversed this therapeutic effect. The results of the animal experiments showed that dexmedetomidine reduced synovial inflammation and increased the pain threshold in an OA rat model. These preliminary results imply that dexmedetomidine may be an effective compound for OA treatment.

Integrating mechanistic-based and classification-based concepts into perioperative pain management: an educational guide for acute pain physicians

Chronic pain begins with acute pain. Physicians tend to classify pain by duration (acute vs chronic) and mechanism (nociceptive, neuropathic and nociplastic). Although this taxonomy may facilitate diagnosis and documentation, such categories are to some degree arbitrary constructs, with significant overlap in terms of mechanisms and treatments. In clinical practice, there are myriad different definitions for chronic pain and a substantial portion of chronic pain involves mixed phenotypes. Classification of pain based on acuity and mechanisms informs management at all levels and constitutes a critical part of guidelines and treatment for chronic pain care. Yet specialty care is often siloed, with advances in understanding lagging years behind in some areas in which these developments should be at the forefront of clinical practice. For example, in perioperative pain management, enhanced recovery protocols are not standardized and tend to drive treatment without consideration of mechanisms, which in many cases may be incongruent with personalized medicine and mechanism-based treatment. In this educational document, we discuss mechanisms and classification of pain as it pertains to commonly performed surgical procedures. Our goal is to provide a clinical reference for the acute pain physician to facilitate pain management decision-making (both diagnosis and therapy) in the perioperative period.

Concentrations of dexmedetomidine and effect on biomarkers of cartilage toxicity following intra-articular administration in horses

OBJECTIVE

The goal of this study was to determine plasma, urine, and synovial fluid concentrations and describe the effects on biomarkers of cartilage toxicity following intra-articular dexmedetomidine administration to horses.

ANIMALS

12 research horses.

PROCEDURES

Horses received a single intra-articular administration of 1 μg/kg or 5 μg/kg dexmedetomidine or saline. Plasma, urine, and synovial fluid were collected prior to and up to 48 hours postadministration, and concentrations were determined. The effects on CS846 and C2C were determined in synovial fluid at 0, 12, and 24 hours postadministration using immunoassays.

RESULTS

Plasma concentrations of dexmedetomidine fell below the limit of quantification (LOQ) (0.005 ng/mL) by 2.5 and 8 hours postadministration of 1 and 5 μg/kg, respectively. Synovial fluid concentrations were above the LOQ (0.1 ng/mL) of the assay at 24 hours in both dose groups. Drug was not detected in urine samples at any time postdrug administration. CS846 concentrations were significantly decreased relative to baseline at 12 hours postadministration in the saline group and significantly increased in the 5-μg/kg-dose group at 24 hours. Concentrations of C2C were significantly decreased at 12 and 24 hours postadministration in the saline treatment group. There were no significant differences in CS846 or C2C concentrations between dose groups at any time.

CLINICAL RELEVANCE

Systemic concentrations of dexmedetomidine remained low, compared to synovial fluid concentrations. CS846, a marker of articular cartilage synthesis, increased in a dose-dependent fashion. Based on these findings, further dose titration and investigation of analgesic and adverse effects are warranted.

Dexmedetomidine Effectively Sedates Asian Elephants (Elephas maximus)

Simple Summary

Sedation in standing procedures is commonly performed in elephants. To successfully and safely initiate standing in elephants, chemical restraint drugs should provide sufficient sedation with minimal complications (i.e., recumbency, significant physiologic alterations, and prolonged recovery). This study investigated the sedative effects of dexmedetomidine in Asian elephants. Results suggest dexmedetomidine 1–2 µg/kg provides effective sedation. However, we suggest a single intramuscular dexmedetomidine injection of 2 µg/kg for approximately 70 min of sedation. This is the first study to demonstrate dexmedetomidine use in Asian elephants.

Abstract

This study investigated the sedative effects of dexmedetomidine in Asian elephants. We hypothesized that 2 µg/kg dexmedetomidine would provide sufficient standing sedation. A crossover design study was performed in three Asian elephants. Each elephant was assigned to 1 of 3 treatment groups—1 (D1), 1.5 (D1.5) or 2 (D2) µg/kg dexmedetomidine (intramuscular injection, IM) with a two-week ‘washout period’ between doses. Elephants were monitored for 120 min. At 120 min (Ta), atipamezole was administered IM. Sedation and responsiveness scores were evaluated. Physiological parameters (pulse rate, respiratory rate, and %SpO₂) and clinical observations were monitored during the study and for 3 days post drug administration. D2 provided the longest sedation (approximately 70 min), compared to D1 and D1.5. After Ta, each elephant’s sedative stage lessened within 10–15 min without complications. No significant abnormal clinical observations were noted throughout and during the 3-days post study period. These data suggest that a single 2 µg/kg IM dexmedetomidine injection provides sufficient standing sedation for approximately 70 min in Asian elephants.