Free Fatty Acid Receptor G-protein-coupled Receptor 40 Mediates Lipid Emulsion-induced Cardioprotection

Vincamine as an agonist of G-protein-coupled receptor 40 effectively ameliorates diabetic peripheral neuropathy in mice

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes, which has yet no curable medication. Neuroinflammation and mitochondrial dysfunction are tightly linked to DPN pathology. G-protein-coupled receptor 40 (GPR40) is predominantly expressed in pancreatic β-cells, but also in spinal dorsal horn and dorsal root ganglion (DRG) neurons, regulating neuropathic pain. We previously have reported that vincamine (Vin), a monoterpenoid indole alkaloid extracted from Madagascar periwinkle, is a GPR40 agonist. In this study, we evaluated the therapeutic potential of Vin in ameliorating the DPN-like pathology in diabetic mice. Both STZ-induced type 1 (T1DM) and db/db type 2 diabetic (T2DM) mice were used to establish late-stage DPN model (DPN mice), which were administered Vin (30 mg·kg-1·d-1, i.p.) for 4 weeks. We showed that Vin administration did not lower blood glucose levels, but significantly ameliorated neurological dysfunctions in DPN mice. Vin administration improved the blood flow velocities and blood perfusion areas of foot pads and sciatic nerve tissues in DPN mice. We demonstrated that Vin administration protected against sciatic nerve myelin sheath injury and ameliorated foot skin intraepidermal nerve fiber (IENF) density impairment in DPN mice. Moreover, Vin suppressed NLRP3 inflammasome activation through either β-Arrestin2 or β-Arrestin2/IκBα/NF-κB signaling, improved mitochondrial dysfunction through CaMKKβ/AMPK/SIRT1/PGC-1α signaling and alleviated oxidative stress through Nrf2 signaling in the sciatic nerve tissues of DPN mice and LPS/ATP-treated RSC96 cells. All the above-mentioned beneficial effects of Vin were abolished by GPR40-specific knockdown in dorsal root ganglia and sciatic nerve tissues. Together, these results support that pharmacological activation of GPR40 as a promising therapeutic strategy for DPN and highlight the potential of Vin in the treatment of this disease.

Palmitic acid methyl ester induces cardiac hypertrophy through activating the GPR receptor-mediated changes of intracellular calcium concentrations and mitochondrial functions

Myocardial hypertrophy is associated with a significant increase in intracellular Ca²⁺ , which can be induced by long-chain fatty acid. Palmitic acid methyl ester (PAME), a fatty acid ester released from adipose tissue, superior cervical ganglion, and retina, has been found to have anti-inflammation, antifibrosis, and peripheral vasodilation effects. However, the effects of PAME on cardiomyocytes are still unclear. The aim of this study was to determine whether PAME could disrupt the intracellular Ca²⁺ balance, leading to cardiomyocyte hypertrophy. Neonatal rat cardiomyocytes were treated with various concentrations (10-100 μM) of PAME for 1-4 days. Cytosolic Ca²⁺ and mitochondrial Ca²⁺ concentrations were examined using Fura-2 AM and Rhod-2, respectively. After treatment with PAME for 4 days, mitochondrial Ca²⁺ , an indicator of the state of mitochondrial permeability transition pore (MPTP), and cell death were monitored by flow cytometric analysis. ATP levels were detected using the ATP assay kit. Cardiomyocyte hypertrophy was analyzed by measuring the cardiac hypertrophy biomarker and cell area using quantitative real time-polymerase chain reaction, Western Blot analysis and immunofluorescence analysis. Our results show that PAME concentration- and time-dependently increased cytosolic and mitochondria Ca²⁺ through the mitochondrial calcium uniporter. Moreover, treatment with PAME for 4 days caused MPTP opening, thereby reducing ATP production and enhancing reactive oxygen species (ROS) generation, and finally led to cardiomyocyte hypertrophy. These effects caused by PAME treatment were attenuated by the G-protein coupled receptor 40 (GPR40) inhibitor. In conclusion, PAME impaired mitochondrial function, which in turn led to cardiomyocyte hypertrophy through increasing the mitochondrial Ca²⁺ levels mediated by activating the GPR40 signaling pathway.

The Bupivacaine Story: A Tribute to George A. Albright, MD (1931-2020)

In 1979, George A. Albright, MD (1931-2020) published a controversial editorial in Anesthesiology that raised the question of bupivacaine cardiotoxicity. In it, he presented several cases of rapid cardiovascular collapse after administration of the highly lipophilic local anesthetic and called for further investigation. Although the scientific community initially resisted Dr Albright's idea, his editorial would ultimately lead to several important advancements in anesthesiology. In 1983, the US Food and Drug Administration issued a black box warning that recommended against the use of 0.75% bupivacaine in obstetric anesthesia. This warning would remain in place until 1999. In addition, Dr Albright's article led to the following changes: laboratory research that proved the cardiotoxicity of bupivacaine; the development of safer, stereoselective agents like ropivacaine; and the acceptance of lipid emulsion as a treatment for local anesthetic toxicity. In this article, C. Philip Larson, Jr, MDCM, Editor-in-Chief of Anesthesiology at the time of publication of Albright's manuscript, provides a unique perspective on the bupivacaine story.

A Myriad of Symptoms After Spinal Anesthesia: A Case Report of Local Anesthetic Systemic Toxicity

Local anesthetics are widely used by various medical professionals. Although their usefulness is unquestionable, as with any medication, there is a possibility of iatrogenic effects. When local anesthetic systemic toxicity occurs, it might be a life-threatening condition. Knowing its existence and how to act when it arises is crucial. The clinical presentation is wide-ranging, but globally it affects the neurological and cardiovascular system, with cardiac arrest being the extreme of its presentation. The treatment is mainly supportive with an attempt to reverse the effects of the anesthetic by administering a lipid emulsion. Here, we present a clinical case of difficult management with many complications.

Intralipid fails to rescue bupivacaine-induced cardiotoxicity in late-pregnant rats

Background

Females routinely receive bupivacaine for obstetric and regional anesthesia. An accidental overdose of bupivacaine can result in cardiotoxicity and cardiac arrest. Intralipid (ILP) rescues bupivacaine-induced cardiotoxicity in male rats. However, bupivacaine cardiotoxicity and ILP rescue have not been studied in non-pregnant and late-pregnant female rats. Here, we tested the hypothesis that an appropriate dose of ILP would rescue non-pregnant and late-pregnant rats from bupivacaine-induced cardiotoxicity.

Methods

Non-pregnant (n = 6) and late-pregnant (n = 7) female rats received intravenous bupivacaine (10-mg/kg bolus) to induce asystole. Resuscitation with 20% ILP (5-ml/kg actual body weight, single bolus, and 0.5-ml/kg/min maintenance) and chest compressions were continued for 10-min. Serial heart rate (HR), left ventricular ejection-fraction (LVEF%), and LV-fractional shortening (LVFS%) were recorded at baseline and 10-min after bupivacaine-induced cardiac arrest. Data are mean ± SD followed by 95% CI. P-values < 0.05 were considered statistically significant.

Results

All rats developed cardiac arrest within a few seconds after bupivacaine. All non-pregnant rats were successfully rescued by ILP, with a HR of 280 ± 32 bpm at baseline vs. 212 ± 18 bpm at 10-min post ILP (p < 0.01), LVEF of 70 ± 6% vs. 68 ± 5% (p = ns), and LVFS of 41 ± 5% vs. 39 ± 4% (p = ns). Interestingly, 6 out of 7 late-pregnant rats did not recover with ILP. Baseline HR, LVEF and LVFS for late-pregnant rats were 330 ± 40 bpm, 66 ± 5% and 38 ± 4%, respectively. At 10-min post ILP, the HR, LVEF, and LVFS were 39 ± 102 bpm (p < 0.0001), 8 ± 22% (p < 0.0001), and 5 ± 12% (p < 0.001), respectively.

Conclusions

ILP successfully rescued bupivacaine-induced cardiac arrest in non-pregnant rats, but failed to rescue late-pregnant rats.

Local anesthetic systemic toxicity: A narrative review for emergency clinicians

INTRODUCTION

Emergency clinicians utilize local anesthetics for a variety of procedures in the emergency department (ED) setting. Local anesthetic systemic toxicity (LAST) is a potentially deadly complication.

OBJECTIVE

This narrative review provides emergency clinicians with the most current evidence regarding the pathophysiology, evaluation, and management of patients with LAST.

DISCUSSION

LAST is an uncommon but potentially life-threatening complication of local anesthetic use that may be encountered in the ED. Patients at extremes of age or with organ dysfunction are at higher risk. Inadvertent intra-arterial or intravenous injection, as well as repeated doses and higher doses of local anesthetics are associated with greater risk of developing LAST. Neurologic and cardiovascular manifestations can occur. Early recognition and intervention, including supportive care and intravenous lipid emulsion 20%, are the mainstays of treatment. Using ultrasound guidance, aspirating prior to injection, and utilizing the minimal local anesthetic dose needed are techniques that can reduce the risk of LAST.

CONCLUSIONS

This focused review provides an update for the emergency clinician to manage patients with LAST.

Lung injury after cardiopulmonary bypass: Alternative treatment prospects

Although the lung injury caused by cardiopulmonary bypass (CPB) has been extensively investigated, the incidence and mortality of lung injury after CPB remain a prominent clinical problem. The poor outcome has been attributed to multifactorial etiology, including the systemic inflammatory response and ischemia reperfusion (I/R) injury during CPB. Lung injury after CPB is a complex pathophysiological process and has many clinical manifestations of mild to severe disease. Which is associated with prognosis. To alleviate this lung injury, interventions that address the pathogenesis are particularly important. This review summarizes the pathogenesis, mechanism and treatment options of lung injury after CPB, such as lung protection with intralipid.

Overexpression of G protein-coupled receptor 40 protects obesity-induced cardiomyopathy through the SIRT1/LKB1/AMPK pathway

Obesity has become a serious global public health problem, and cardiomyopathy caused by obesity has been paid more and more attention in recent years. As an important protein involved in glucose and lipid metabolism, G protein-coupled receptor 40 (GPR40) exerts cardioprotective effects in some disease models. The aim of this study was to explore whether GPR40 plays a protective role in obesity-induced cardiomyopathy. We established an obesity model by feeding rats with a high-fat diet, and H9c2 cells were stimulated with palmitic acid to mimic high-fat stimulation. Overexpression of GPR40 was achieved by infection with lentivirus or cDNA plasmids. Obesity-induced cardiac injury models exhibit cardiac dysfunction, myocardial hypertrophy and collagen accumulation, accompanied by increased inflammation, oxidative stress and apoptosis. However, GPR40 overexpression attenuated these alterations. Its anti-inflammatory effect may be through inhibiting the nuclear factor-κB pathway, and the anti-oxidative stress may be through activating the nuclear transcription factor erythroid 2-related factor 2 pathway. For the mechanism of GPR40 against obese cardiomyopathy, GPR40 overexpression not only activated the sirtuin 1 (SIRT1)- liver kinase B1 (LKB1)- AMP-activated protein kinase (AMPK) pathway, but also enhanced the binding of SIRT1 to LKB1. The anti-fibrotic, anti-inflammatory, anti-oxidative stress and anti-apoptotic effects of GPR40 overexpression were inhibited by SIRT1 small interfering RNA. In conclusion, GPR40 overexpression protects against obesity-induced cardiac injury in rats, possibly through the SIRT1- LKB1- AMPK pathway.

Methyl palmitate protects heart against ischemia/reperfusion-induced injury through G-protein coupled receptor 40-mediated activation of the PI3K/AKT pathway

This study aimed to investigate whether methyl palmitate (MP) exerts cardioprotective effect against the ischemia/reperfusion (I/R) injury and its mechanisms underlying. The cultured adult cardiomyocytes were treated with vehicle or lactic acid ischemic buffer (pH 6.8) during hypoxia/reoxygenation. In addition, the cardioprotective effect of MP was evaluated using the ex vivo heart model of I/R injury. Here, we found that MP significantly reduced the I/R-induced cardiomyocyte death. Treatment with GW1100 (a GPR40-antagonist) or wortmannin (a phosphatidylinositol 3-kinase, PI3K, specific inhibitor) significantly attenuated the level of phospho-AKT (p-AKT) and abolished the MP-induced cardioprotection against the I/R-induced injury. Using the ex vivo I/R model, we also demonstrated that pretreatment with MP significantly reduced the size of myocardial infarction and the levels of cleaved-caspase 3 and MDA, and increased the protein levels of GPR40 and p-AKT induced by I/R. The cardioprotective effect of MP was evaluated also using the in vivo heart model of I/R injury. We demonstrated that post-ischemic treatment with MP significantly attenuated the size of myocardial infarction and the serum level of CK-MB induced by in vivo I/R model. Taken together, our data suggest that MP could provide significant cardioprotection against the I/R injury, and the underlying mechanisms by which MP prevented the cardiomyocyte death might be mediated through the GPR40-activated PI3K/AKT signaling pathways. These findings suggest the potential applications of MP in the treatment of I/R-induced heart injury.

Intravenous lipid emulsion as an adjuvant therapy of acute clozapine poisoning

Introduction:

Clozapine is a frequently prescribed atypical antipsychotic drug. Various case reports documented the successful recovery of acute antipsychotics toxicity in association with the administration of intralipid emulsion (ILE).

Aim:

This study aimed to assess the adjuvant therapeutic role of SMOF Lipid administration on the outcomes of acute clozapine poisoning.

Methods:

Forty patients with acute clozapine poisoning were randomly allocated into two equal groups. The control group received the standard supportive treatment only, whereas the intervention group received the standard supportive treatment plus SMOF Lipid 20% infusion. All patients were subjected to history taking, full clinical examination, and laboratory investigations. The study outcomes were evaluated.

Results:

The mean Glasgow Coma Scale (GCS) at 6 hours (13.1 ± 2.3 vs 9.2 ± 2, p < 0.001) and 12 hours (14.3 ± 1.5 vs 9.6 ± 2, p < 0.001) after admission was significantly higher in the intervention group compared to the control group. The intervention group showed a significantly lower frequency of prolonged QTc interval 12 hours after admission (p = 0.003), as well as a significantly shorter hospital stay (p < 0.001).

Conclusions:

SMOF Lipid infusion seemed to have improved GCS, the prolonged QTc interval, and shortened the length of hospital stay. Furthermore, there were no adverse effects related to its administration.

Intralipid postconditioning in patients of cardiac surgery undergoing cardiopulmonary bypass (iCPB): study protocol for a randomized controlled trial

Background

Intralipid is a necessary fatty acid carrier that has been safely used as an energy supplier in the clinic. It has played an important role in rescuing the cardiac arrest caused by local anesthetic toxicity. In recent years, experimental studies have shown that intralipid postconditioning (ILPC) could reduce myocardial ischemic/reperfusion (I/R) injuries. Our research group has innovatively conducted a pilot randomized controlled trial (RCT), and the results showed that ILPC could reduce the release of cTnT and CK-MB, biomarkers of myocardial I/R injury, in valve replacement surgery. However, the potential effects of ILPC on the clinical outcome of adult cardiac surgery patients are unclear. Intralipid postconditioning in patients of cardiac surgery undergoing cardiopulmonary bypass (iCPB) trial is aimed to further study whether ILPC could improve short-term and long-term clinical outcome, as well as cardiac function in adult cardiac surgery patients.

Methods

The iCPB trial is an ongoing, single-center, prospective, double-blinded, large sample RCT. In total, 1000 adults undergoing cardiac surgery will be randomly allocated to either the ILPC group or the control group. The intervention group received an intravenous infusion of 2 mL/kg of 20% intralipid (medium-chain and long-chain fat emulsion injection C6~C24, Pharmaceutical) within 10 min before aortic cross-unclamping, and the control group received an equivalent volume of normal saline. The primary endpoints are complex morbidity of major complications during hospitalization and all-cause mortality within 30 days after surgery. The secondary endpoints include (1) all-cause mortality 6 months and 1 year postoperatively; (2) the quality of life within 1 year after surgery, using the QoR-15 questionnaire; (3) the postoperative cardiac function evaluated by LVEF, LVEDS, and LVEDD, and the myocardial injury evaluated by CK-MB, cTnT, and BNP; and (4) short-term clinical outcomes during hospitalization and total cost are also detailed evaluated.

Discussion

The iCPB trial is the first to explore ILPC on the clinical outcome of adult cardiac surgery patients. The results are expected to provide potential evidences about whether ILPC could reduce the morbidity and mortality and improve the cardiac function and quality of life. Therefore, the results will provide a rationale for the evaluation of the potentially clinically relevant benefit of intralipid therapy.

Trial registration

Chictr.org.cn ChiCTR1900024387. Prospectively registered on 9 July 2019.

Linolenic acid enhances contraction induced by phenylephrine in isolated rat aorta

This study examined the effect of linolenic acid on the contraction of isolated endothelium-intact and -denuded rat aorta induced by phenylephrine and its underlying mechanism. This was conducted in the presence or absence of N^W-nitro-L-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), methylene blue, and calmidazolium. The effects of linolenic acid on contraction induced by calcium chloride in calcium-free Krebs solution containing 60 mM potassium chloride were also examined. Moreover, the effect of linolenic acid on the association between intracellular calcium level ([Ca²⁺]_i) and tension induced by phenylephrine was examined. Finally, we examined the effects of linolenic acid on cGMP formation and endothelial nitric oxide synthase (eNOS) phosphorylation induced by phenylephrine. Linolenic acid (5 × 10^-5 M) increased phenylephrine-induced contraction in endothelium-intact aorta (standardized mean difference [SMD] of log ED₅₀: 2.23), whereas it decreased this contraction in endothelium-denuded aorta (SMD: 1.96). L-NAME, ODQ, methylene blue, and calmidazolium increased phenylephrine-induced contraction in endothelium-intact aorta. Linolenic acid decreased contraction induced by calcium chloride in calcium-free Krebs solution containing 60 mM potassium chloride in endothelium-denuded aorta. Linolenic acid caused an increase in [Ca²⁺]_i (SMD at 3 × 10^-7 M phenylephrine: 1.63) and calcium sensitivity induced by phenylephrine in endothelium-intact aorta. Conversely, linolenic acid decreased [Ca²⁺]_i (SMD: 0.99) induced by phenylephrine in endothelium-denuded aorta. Linolenic acid decreased cGMP formation and eNOS phosphorylation induced by phenylephrine. These results suggest that linolenic acid increases phenylephrine-induced contraction, which is attributed to linolenic acid inhibition of endothelial NO release rather than its decrease of [Ca²⁺]_i in vascular smooth muscle.

Activation of GPR40 Suppresses AGE-Induced Reduction of Type II Collagen and Aggrecan in Human SW1353 Chondrocytes

Introduction

Osteoarthritis (OA) is an age-related chronic degenerative disease. Accumulation of advanced glycation end products (AGEs) induces degradation of the articular extracellular matrix (ECM) and is considered a critical step toward the development and progression of OA. GPR40 is a well-known free fatty acid receptor, which possesses pleiotropic effects in different types of diseases. However, the biological function of GPR40 in OA is indistinct. The purpose of the present study was to determine the impact of the GPR40 agonist GW9508 on AGEs-treated chondrocytes.

Materials and Methods

Cultures of human SW1353 chondrocytes were stimulated with GW9508, followed by exposure to 100 µg/mL AGEs. Gene and protein expression of TNF-α, IL-6, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 were measured by real-time PCR and ELISA analysis. The levels of type II collagen, aggrecan, and nuclear NF-κB p65 were measured by Western blot analysis. A luciferase assay measured the transcriptional activity of NF-κB.

Results

The results show that treatment with AGEs decreased the expression of GPR40 in human SW1353 chondrocytes. Treatment with GW9508 plays a beneficial role in protecting type II Collagen and aggrecan from degeneration by attenuating the expression of MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5. Additionally, GW9508 reduces the appearance of pro-inflammatory cytokines and suppresses NF-κB activation in AGEs-induced chondrocytes. Notably, co-treatment with GW1100, a specific antagonist of GPR40, abolishes the beneficial role of GW9508 against AGEs, implying that GPR40 mediates these effects of GW9508.

Conclusion

Our results suggest that GPR40 is a novel therapeutic target for OA and that GPR40 agonists, including GW9508, may have therapeutic potential in preventing and slowing the progression of OA.