Dexmedetomidine attenuates myocardial ischemia-reperfusion injury in vitro by inhibiting NLRP3 Inflammasome activation.

BACKGROUND: Myocardial ischemia-reperfusion injury (MIRI) is the most common cause of death worldwide. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome plays an important role in the inflammatory response to MIRI. Dexmedetomidine (DEX), a specific agonist of α2-adrenergic receptor, is commonly used for sedation and analgesia in anesthesia and critically ill patients. Several studies have shown that dexmedetomidine has a strong anti-inflammatory effect in many diseases. Here, we investigated whether dexmedetomidine protects against MIRI by inhibiting the activation of the NLRP3 inflammasome in vitro. METHODS: We established an MIRI model in cardiomyocytes (CMs) alone and in coculture with cardiac fibroblasts (CFs) by hypoxia/reoxygenation (H/R) in vitro. The cells were treated with dexmedetomidine with or without MCC950 (a potent selective NLRP3 inhibitor). The beating rate and cell viability of cardiomyocytes, NLRP3 localization, the expression of inflammatory cytokines and NLRP3 inflammasome-related proteins, and the expression of apoptosis-related proteins, including Bcl2 and BAX, were determined. RESULTS: Dexmedetomidine treatment increased the beating rates and viability of cardiomyocytes cocultured with cardiac fibroblasts. The expression of the NLRP3 protein was significantly upregulated in cardiac fibroblasts but not in cardiomyocytes after H/R and was significantly attenuated by dexmedetomidine treatment. Expression of the inflammatory cytokines IL-1ß, IL-18 and TNF-α was significantly increased in cardiac fibroblasts after H/R and was attenuated by dexmedetomidine treatment. NLRP3 inflammasome activation induced the increased expression of cleaved caspase1, mature IL-1ß and IL-18, while dexmedetomidine suppressed H/R-induced NLRP3 inflammasome activation in cardiac fibroblasts. In addition, dexmedetomidine reduced the expression of Bcl2 and BAX in cocultured cardiomyocytes by suppressing H/R-induced NLRP3 inflammasome activation in cardiac fibroblasts. CONCLUSION: Dexmedetomidine treatment can suppress H/R-induced NLRP3 inflammasome activation in cardiac fibroblasts, thereby alleviating MIRI by inhibiting the inflammatory response.

Propofol pretreatment inhibits ferroptosis and alleviates myocardial ischemia-reperfusion injury through the SLC16A13-AMPK-GPX4 pathway.

This study investigates the protective effects of propofol on the myocardium by inhibiting the expression of SLC16A13 through in vivo animal experiments, while also exploring its mechanism in ferroptosis to provide new strategies for preventing perioperative myocardial ischemia-reperfusion injury. We randomly divided 30 rats into three groups (n=10 each): sham surgery group, ischemia-reperfusion (I/R) group, and propofol pretreatment group. The results showed that compared with the sham surgery group, the I/R group had a significant decrease in cardiac function and an increase in infarct size. Propofol pretreatment effectively alleviated the damage caused by ischemia-reperfusion (I/R). In the next phase of the study, we administered the PPARα agonist GW7647 to artificially increase the expression of SLC16A13. Fifty rats were randomly divided into five groups (n=10 each), with the GW7647 pretreatment group and propofol+GW7647 pretreatment group added based on the previous three groups. Afterwards, we validated the in vivo results using H9C2 and further explored the mechanism by which propofol inhibits ferroptosis. The study found that L-lactic acid in myocardial tissue of the GW7647 group was further increased compared to the I/R group, and the degree of ferroptosis was aggravated. In addition, upregulation of SLC16A13 significantly inhibited the phosphorylation of AMPK, weakened the protective mechanism of AMPK, and exacerbated cardiac damage. However, propofol pretreatment can effectively inhibit the expression of SLC16A13, maintain normal myocardial cell morphology, and protect cardiac function. These results indicate that propofol inhibits the expression of SLC16A13, alleviates myocardial cell ferroptosis via the AMPK/GPX4 pathway, and reverses damage caused by myocardial ischemia-reperfusion.

Sedation with a 1:1 mixture of etomidate and propofol for gastroscopy in hypertensive elderly patients.

We hypothesized that the combined use of etomidate and propofol for endoscopic sedation in elderly hypertensive patients could reduce adverse reactions while providing ideal sedation. To validate our hypothesis, we conducted a prospective, randomized, controlled, double-blinded study. A total of 360 elderly hypertensive patients scheduled for gastroscopy at our hospital were enrolled in the study, of whom 328 completed the trial. The patients were randomly assigned to one of three groups: the propofol group (group P), the etomidate group (group E), or the propofol-etomidate combination group (mixed at a ratio of 1:1, group PE). We collected and analyzed the cardiopulmonary effects and side effects in each group. Regardless of the sedation drug used, the systolic blood pressure, mean blood pressure, and heart rate of involved patients were significantly affected. Oxygen desaturation and injection pain were more common in group P compared to groups E (33.6% vs. 14.8%, 31.8% vs. 2.7%, both P < 0.01) and group PE (33.6% vs. 13.6%, 31.8% vs. 6.4%, both P < 0.01). The incidence of myoclonus in the PE group was lower than that in the E group (10.9% vs. 61.2%, P < 0.01). Our results indeed demonstrated that the combined use of etomidate and propofol appeared to maintain cardiopulmonary stability with minimal side effects in older hypertensive patients scheduled for gastroscopy, which further implied that this sedation strategy could be a safe and pain-free option for managing patients undergoing gastroscopy, particularly those at a higher risk of adverse cardiovascular events.

Electroacupuncture Alleviates Thalamic Pain in Rats by Suppressing ADCY1 Protein Upregulation.

BACKGROUND: Thalamic pain (TP), also known as central post-stroke pain, is a chronic neuropathic pain syndrome that follows a stroke and is a severe pain that is usually intractable. No universally applicable and effective therapies have been proposed. Emerging studies have reported that electroacupuncture (EA) can potentially be used as an effective therapy for the treatment of neuropathic pain. However, whether EA influences TP and if so, by what potential mechanism, remains poorly understood. OBJECTIVE: The aim of this study was to detect the efficacy of EA and explore possible mechanisms for treating TP. STUDY DESIGN: Controlled animal study. SETTING: The laboratory at the Aviation General Hospital of China Medical University and Beijing Institute of Translational Medicine. METHODS: Male Sprague Dawley rats were randomly divided into 3 groups (n = 15 / group): sham-operated (SH) group, thalamic pain model (TP) group, EA treatment (EA) group. After the TP rat model was successfully established, EA was used for intervention. During the experiment, the mechanical pain thresholds of rats were detected among the groups. The right thalamus of the rats was extracted on postoperative day 28 for RNA-sequencing (RNA-Seq) analysis to find the changes in gene expression in different groups of rats. The key genes were screened using reverse transcription-polymerase chain reaction (RT-PCR) detection and subsequently identified with western blotting and immunofluorescence. RESULTS: The mechanical withdrawal threshold (MWT) value of the right facial skin in the TP group and the EA group decreased significantly on the 3rd day after surgery, compared to the SH group (P < 0.01). From 7 to 28 days, the MWT value increased continually in the EA group; however, there was no significant change in the TP group. The results of RNA-seq showed that compared to the TP group, 377 genes changed in the EA group. Moreover, ADCY1 expression increased significantly in the TP group as compared to the SH group, while EA treatment reversed the expression of ADCY1. LIMITATIONS: In addition to ADCY1, the mechanism(s) of other signaling pathways in TP need to be explored in future research. CONCLUSIONS: EA treatment may promote the recovery of TP model rat by regulating ADCY1 expression.

Clemastine Fumarate Attenuates Myocardial Ischemia Reperfusion Injury Through Inhibition of Mast Cell Degranulation.

Mast cell (MC) activation is associated with myocardial ischemia reperfusion injury (MIRI). Suppression of MC degranulation might be a target of anti-MIRI. This study aimed to determine whether clemastine fumarate (CLE) could attenuate MIRI by inhibiting MC degranulation. A rat ischemia and reperfusion (I/R) model was established by ligating the left anterior descending coronary artery for 30 min followed by reperfusion for 120 min. Compound 48/80 (C48/80) was used to promote MC degranulation. The protective effect of CLE by inhibiting MC degranulation on I/R injury was detected by cardiac function, 2,3,5-triphenyl tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, arrhythmia, and myocardial enzyme detection. Inflammatory factor mRNA levels, such as TNF-α, interleukin (IL)-1ß, and IL-6, were detected. Cultured RBL-2H3 mast cells were pretreated with CLE and subjected to C48/80 treatment to determine whether CLE suppressed MC degranulation. Degranulation of MCs was visualized using tryptase release, Cell Counting Kit-8 (CCK-8), and cell toluidine blue (TB) staining. RBL cells were conditionally cultured with H9C2 cells to explore whether CLE could reverse the apoptosis of cardiomyocytes induced by MC degranulation. Apoptosis of H9C2 cells was detected by CCK-8, the LDH Cytotoxicity Assay Kit (LDH), TUNEL staining, and protein expression of BAX and Bcl-2. We found that CLE pretreatment further inhibited cardiac injury manifested by decreased infarct size, histopathological changes, arrhythmias, MC degranulation, and myocardial enzyme levels, improving cardiac function compared with that in the I/R group. C48/80 combined with I/R exacerbated these changes. However, pretreatment with CLE for C48/80 combined with I/R significantly reversed these injuries. In addition, CLE pretreatment improved the vitality of RBL cells and reduced tryptase release in vitro. Similarly, the supernatant of RBL cells pretreated with CLE decreased the cytotoxicity, TUNEL-positive cell rate, and BAX expression of conditioned H9C2 cells and increased the cell vitality and expression of Bcl-2. These results suggested that pretreatment with CLE confers protection against I/R injury by inhibiting MC degranulation.