Endocannabinoids and cannabinoid receptors in ischaemia-reperfusion injury and preconditioning

Depression exacerbates myocardial ischemia-reperfusion injury in mice via CNR2 gene and MIF-AMPK signaling pathway

BACKGROUND

Myocardial ischemia-reperfusion(I/R)injury constitute the fundamental pathophysiology of acute myocardial infarction (AMI). Ischemic heart releases macrophage migration inhibitory factor (MIF), which activates MIF- AMPK signaling pathway. Depression is a significant risk factor for AMI. In a state of depression, peripheral expression of cannabinoid receptor 2 (CNR2) genes was downregulated.

AIMS

We investigated the mechanism by which depression exacerbates myocardial I/R injury through the CNR2 and MIF-AMPK signaling pathways.

METHODS

We established mouse models of depression and myocardial I/R. Left ventricular function was assessed using cardiac ultrasound and TTC staining. The protein levels of myocardial CNR2, MIF, AMPK, and ACC were determined by Western blot, while the expression level of CNR2 was measured using RT-qPCR. Additionally, MIF content in peripheral blood was quantified using ELISA.

RESULTS

After I/R, the expression level of CNR2 was found to be lower in the depression group, leading to a deterioration in left heart function. Depressed mice exhibited lower secretion of MIF, accompanied by a decrease in the activation of the MIF-AMPK signaling pathway. However, injection of CNR2 agonist JWH133 prior to ischemia increased the activation of the MIF-AMPK signaling pathway, while CNR2 inhibitor AM630 decreased the activation.

LIMITATIONS

Further research is needed to investigate the specific neuroendocrine mechanism affecting myocardial CNR2 expression in depression. And these experimental conclusions require further verification at the cellular level.

CONCLUSIONS

The activation of CNR2 in myocardium following I/R is impeded by depression, thereby exacerbating myocardial I/R injury through attenuation of the MIF-AMPK signaling pathway activation.

The action mechanism by which C1q/tumor necrosis factor-related protein-6 alleviates cerebral ischemia/reperfusion injury in diabetic mice

JOURNAL/nrgr/04.03/01300535-202409000-00034/figure1/v/2024-01-16T170235Z/r/image-tiff Studies have shown that C1q/tumor necrosis factor-related protein-6 (CTRP6) can alleviate renal ischemia/reperfusion injury in mice. However, its role in the brain remains poorly understood. To investigate the role of CTRP6 in cerebral ischemia/reperfusion injury associated with diabetes mellitus, a diabetes mellitus mouse model of cerebral ischemia/reperfusion injury was established by occlusion of the middle cerebral artery. To overexpress CTRP6 in the brain, an adeno-associated virus carrying CTRP6 was injected into the lateral ventricle. The result was that oxygen injury and inflammation in brain tissue were clearly attenuated, and the number of neurons was greatly reduced. In vitro experiments showed that CTRP6 knockout exacerbated oxidative damage, inflammatory reaction, and apoptosis in cerebral cortical neurons in high glucose hypoxia-simulated diabetic cerebral ischemia/reperfusion injury. CTRP6 overexpression enhanced the sirtuin-1 signaling pathway in diabetic brains after ischemia/reperfusion injury. To investigate the mechanism underlying these effects, we examined mice with depletion of brain tissue-specific sirtuin-1. CTRP6-like protection was achieved by activating the sirtuin-1 signaling pathway. Taken together, these results indicate that CTRP6 likely attenuates cerebral ischemia/reperfusion injury through activation of the sirtuin-1 signaling pathway.

A Highly Potent, Orally Bioavailable Pyrazole-Derived Cannabinoid CB2 Receptor- Selective Full Agonist for In Vivo Studies

The cannabinoid CB2 receptor (CB2R) is a potential therapeutic target for distinct forms of tissue injury and inflammatory diseases. To thoroughly investigate the role of CB2R in pathophysiological conditions and for target validation in vivo, optimal pharmacological tool compounds are essential. Despite the sizable progress in the generation of potent and selective CB2R ligands, pharmacokinetic parameters are often neglected for in vivo studies. Here, we report the generation and characterization of a tetra-substituted pyrazole CB2R full agonist named RNB-61 with high potency (K i 0.13-1.81 nM, depending on species) and a peripherally restricted action due to P-glycoprotein-mediated efflux from the brain. 3H and 14C labeled RNB-61 showed apparent K d values of <4 nM toward human CB2R in both cell and tissue experiments. The 6,800-fold selectivity over CB1 receptors and negligible off-targets in vitro, combined with high oral bioavailability and suitable systemic pharmacokinetic (PK) properties, prompted the assessment of RNB-61 in a mouse ischemia-reperfusion model of acute kidney injury (AKI) and in a rat model of chronic kidney injury/inflammation and fibrosis (CKI) induced by unilateral ureteral obstruction. RNB-61 exerted dose-dependent nephroprotective and/or antifibrotic effects in the AKI/CKI models. Thus, RNB-61 is an optimal CB2R tool compound for preclinical in vivo studies with superior biophysical and PK properties over generally used CB2R ligands.

Exploring the Possible Role of Cannabinoids in Managing Post-cardiac Surgery Complications: A Narrative Review of Preclinical Evidence and a Call for Future Research Directions

ABSTRACT

Open-heart surgery with cardiopulmonary bypass often leads to complications including pain, systemic inflammation, and organ damage. Traditionally managed with opioids, these pain relief methods bring potential long-term risks, prompting the exploration of alternative treatments. The legalization of cannabis in various regions has reignited interest in cannabinoids, such as cannabidiol, known for their anti-inflammatory, analgesic, and neuroprotective properties. Historical and ongoing research acknowledges the endocannabinoid system's crucial role in managing physiological processes, suggesting that cannabinoids could offer therapeutic benefits in postsurgical recovery. Specifically, cannabidiol has shown promise in managing pain, moderating immune responses, and mitigating ischemia/reperfusion injury, underscoring its potential in postoperative care. However, the translation of these findings into clinical practice faces challenges, highlighting the need for extensive research to establish effective, safe cannabinoid-based therapies for patients undergoing open-heart surgery. This narrative review advocates for a balanced approach, considering both the therapeutic potential of cannabinoids and the complexities of their integration into clinical settings.

Re-evaluation of the cardioprotective effects of cannabinoids against ischemia-reperfusion injury according to the IMproving Preclinical Assessment of Cardioprotective Therapies (IMPACT) criteria

Ischemic heart disease, associated with high morbidity and mortality, represents a major challenge for the development of drug-based strategies to improve its prognosis. Results of pre-clinical studies suggest that agonists of cannabinoid CB2 receptors and multitarget cannabidiol might be potential cardioprotective strategies against ischemia-reperfusion injury. The aim of our study was to re-evaluate the cardioprotective effects of cannabinoids against ischemia-reperfusion injury according to the IMproving Preclinical Assessment of Cardioprotective Therapies (IMPACT) criteria published recently by the European Union (EU) CARDIOPROTECTION COST ACTION. To meet the minimum criteria of those guidelines, experiments should be performed (i) on healthy small animals subjected to ischemia with reperfusion lasting for at least 2 hours and (ii) confirmed in small animals with comorbidities and co-medications and (iii) in large animals. Our analysis revealed that the publications regarding cardioprotective effects of CB2 receptor agonists and cannabidiol did not meet all three strict steps of IMPACT. Thus, additional experiments are needed to confirm the cardioprotective activities of (endo)cannabinoids mainly on small animals with comorbidities and on large animals. Moreover, our publication underlines the significance of the IMPACT criteria for a proper planning of preclinical experiments regarding cardiac ischemia-reperfusion injury.

A highly potent, orally bioavailable pyrazole-derived cannabinoid CB2 receptor-selective full agonist for in vivo studies

The cannabinoid CB2 receptor (CB2R) is a potential therapeutic target for distinct forms of tissue injury and inflammatory diseases. To thoroughly investigate the role of CB2R in pathophysiological conditions and for target validation in vivo, optimal pharmacological tool compounds are essential. Despite the sizable progress in the generation of potent and selective CB2R ligands, pharmacokinetic parameters are often neglected for in vivo studies. Here, we report the generation and characterization of a tetra-substituted pyrazole CB2R full agonist named RNB-61 with high potency (K i 0.13-1.81 nM, depending on species) and a peripherally restricted action due to P-glycoprotein mediated efflux from the brain. 3H and 14C labelled RNB-61 showed apparent K d values < 4 nM towards human CB2R in both cell and tissue experiments. The >6000-fold selectivity over CB1 receptors and negligible off-targets in vitro, combined with high oral bioavailability and suitable systemic pharmacokinetic (PK) properties, prompted the assessment of RNB-61 in a mouse ischemia-reperfusion model of acute kidney injury (AKI) and in a rat model of chronic kidney injury/inflammation and fibrosis (CKI) induced by unilateral ureteral obstruction. RNB-61 exerted dose-dependent nephroprotective and/or antifibrotic effects in the AKI/CKI models. Thus, RNB-61 is an optimal CB2R tool compound for preclinical in vivo studies with superior biophysical and PK properties over generally used CB2R ligands.

CB2 Cannabinoid Receptor as a Potential Target in Myocardial Infarction: Exploration of Molecular Pathogenesis and Therapeutic Strategies

The lipid endocannabinoid system has recently emerged as a novel therapeutic target for several inflammatory and tissue-damaging diseases, including those affecting the cardiovascular system. The primary targets of cannabinoids are cannabinoid type 1 (CB1) and 2 (CB2) receptors. The CB2 receptor is expressed in the cardiomyocytes. While the pathological changes in the myocardium upregulate the CB2 receptor, genetic deletion of the receptor aggravates the changes. The CB2 receptor plays a crucial role in attenuating the advancement of myocardial infarction (MI)-associated pathological changes in the myocardium. Activation of CB2 receptors exerts cardioprotection in MI via numerous molecular pathways. For instance, delta-9-tetrahydrocannabinol attenuated the progression of MI via modulation of the CB2 receptor-dependent anti-inflammatory mechanisms, including suppression of pro-inflammatory cytokines like IL-6, TNF-α, and IL-1β. Through similar mechanisms, natural and synthetic CB2 receptor ligands repair myocardial tissue damage. This review aims to offer an in-depth discussion on the ameliorative potential of CB2 receptors in myocardial injuries induced by a variety of pathogenic mechanisms. Further, the modulation of autophagy, TGF-β/Smad3 signaling, MPTP opening, and ROS production are discussed. The molecular correlation of CB2 receptors with cardiac injury markers, such as troponin I, LDH1, and CK-MB, is explored. Special attention has been paid to novel insights into the potential therapeutic implications of CB2 receptor activation in MI.

Neuroadaptive Biochemical Mechanisms of Remote Ischemic Conditioning

This review summarizes the currently known biochemical neuroadaptive mechanisms of remote ischemic conditioning. In particular, it focuses on the significance of the pro-adaptive effects of remote ischemic conditioning which allow for the prevention of the neurological and cognitive impairments associated with hippocampal dysregulation after brain damage. The neuroimmunohumoral pathway transmitting a conditioning stimulus, as well as the molecular basis of the early and delayed phases of neuroprotection, including anti-apoptotic, anti-oxidant, and anti-inflammatory components, are also outlined. Based on the close interplay between the effects of ischemia, especially those mediated by interaction of hypoxia-inducible factors (HIFs) and steroid hormones, the involvement of the hypothalamic-pituitary-adrenocortical system in remote ischemic conditioning is also discussed.

Goods and Bads of the Endocannabinoid System as a Therapeutic Target: Lessons Learned after 30 Years

The cannabis derivative marijuana is the most widely used recreational drug in the Western world and is consumed by an estimated 83 million individuals (∼3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the United States and worldwide. Compelling research evidence and the Food and Drug Administration cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS)-made of receptors, metabolic enzymes, and transporters-that is also regulated by phytocannabinoids. The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of the ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here a critical review of our knowledge of the goods and bads of the ECS as a therapeutic target is presented to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health. SIGNIFICANCE STATEMENT: The endocannabinoid system plays important roles virtually everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like cannabinoid receptors 1 and 2) and metabolic enzymes (like fatty acid amide hydrolase and monoacylglycerol lipase), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels, providing new opportunities to treat patients.

Cannabinoid Signaling in Kidney Disease

Endocannabinoid signaling plays crucial roles in human physiology in the function of multiple systems. The two cannabinoid receptors, CB1 and CB2, are cell membrane proteins that interact with both exogenous and endogenous bioactive lipid ligands, or endocannabinoids. Recent evidence has established that endocannabinoid signaling operates within the human kidney, as well as suggests the important role it plays in multiple renal pathologies. CB1, specifically, has been identified as the more prominent ECS receptor within the kidney, allowing us to place emphasis on this receptor. The activity of CB1 has been repeatedly shown to contribute to both diabetic and non-diabetic chronic kidney disease (CKD). Interestingly, recent reports of acute kidney injury (AKI) have been attributed to synthetic cannabinoid use. Therefore, the exploration of the ECS, its receptors, and its ligands can help provide better insight into new methods of treatment for a range of renal diseases. This review explores the endocannabinoid system, with a focus on its impacts within the healthy and diseased kidney.

Cannabinoid Receptor 1 Agonist ACEA and Cannabinoid Receptor 2 Agonist GW833972A Attenuates Cell-Mediated Immunity by Different Biological Mechanisms

Cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) are components in the endocannabinoid system that play significant roles in regulating immune responses. There are many agonists for the cannabinoid receptors; however, their effects on T cell regulation have not been elucidated. In the present study, we determined the effects of the CB1 selective agonist ACEA and the CB2 selective agonist GW833972A on T cell responses. It was found that both agonists impaired anti-CD3 monoclonal antibody induced T cell proliferation. However, ACEA and GW833972A agonists down-regulated the expression of activation markers on CD4+ and CD8+ T cells and co-stimulatory molecules on B cells and monocytes in different manners. Moreover, only GW833972A suppressed the cytotoxic activities of CD8+ T cells without interfering in the cytotoxic activities of CD4+ T cells and NK cells. In addition, the CB2 agonist, but not CB1 agonist, caused the reduction of Th1 cytokine production. Our results demonstrated that the CB1 agonist ACEA and CB2 agonist GW833972A attenuated cell-mediated immunity in different mechanisms. These agonists may be able to be used as therapeutic agents for inducing T cell hypofunction in inflammatory and autoimmune diseases.

Systemic Changes in Endocannabinoids and Endocannabinoid-like Molecules in Response to Partial Nephrectomy-Induced Ischemia in Humans

Renal ischemia-reperfusion (IR), a routine feature of partial nephrectomy (PN), can contribute to the development of acute kidney injury (AKI). Rodent studies show that the endocannabinoid system (ECS) is a major regulator of renal hemodynamics and IR injury; however, its clinical relevance remains to be established. Here, we assessed the clinical changes in systemic endocannabinoid (eCB) levels induced by surgical renal IR. Sixteen patients undergoing on-clamp PN were included, with blood samples taken before renal ischemia, after 10 min of ischemia time, and 10 min following blood reperfusion. Kidney function parameters (serum creatinine (sCr), blood urea nitrogen (BUN), and serum glucose) and eCB levels were measured. Baseline levels and individual changes in response to IR were analyzed and correlation analyses were performed. The baseline levels of eCB 2-arachidonoylglycerol (2-AG) were positively correlated with kidney dysfunction biomarkers. Unilateral renal ischemia increased BUN, sCr, and glucose, which remained elevated following renal reperfusion. Renal ischemia did not induce changes in eCB levels for all patients pooled together. Nevertheless, stratifying patients according to their body mass index (BMI) revealed a significant increase in N-acylethanolamines (anandamide, AEA; N-oleoylethanolamine, OEA; and N-palmitoylethanolamine, PEA) in the non-obese patients. No significant changes were found in obese patients who had higher N-acylethanolamines baseline levels, positively correlated with BMI, and more cases of post-surgery AKI. With the inefficiency of 'traditional' IR-injury 'preventive drugs', our data support future research on the role of the ECS and its manipulation in renal IR.

How do phytocannabinoids affect cardiovascular health? An update on the most common cardiovascular diseases

Cardiovascular disease (CVD) causes millions of deaths worldwide each year. Despite the great progress in therapies available for patients with CVD, some limitations, including drug complications, still exist. Hence, the endocannabinoid system (ECS) was proposed as a new avenue for CVDs treatment. The ECS components are widely distributed through the body, including the heart and blood vessels, thus the action of its endogenous and exogenous ligands, in particular, phytocannabinoids play a key role in various pathological states. The cardiovascular action of cannabinoids is complex as they affect vasculature and myocardium directly via specific receptors and exert indirect effects through the central and peripheral nervous system. The growing interest in phytocannabinoid studies, however, has extended the knowledge about their molecular targets as well as therapeutical properties; nonetheless, some areas of their actions are not yet fully recognized. Researchers have reported various cannabinoids, especially cannabidiol, as a promising approach to CVDs; hence, the purpose of this review is to summarize and update the cardiovascular actions of the most potent phytocannabinoids and the potential therapeutic role of ECS in CVDs, including ischemic reperfusion injury, arrhythmia, heart failure as well as hypertension.

Protective effect of fatty acid amide hydrolase inhibitor URB597 and monoacylglycerol lipase inhibitor KML29 on renal ischemia-reperfusion injury via toll-like receptor 4/nuclear factor-kappa B pathway

BACKGROUND

Arachidonoyl ethanolamide (anandamide, AEA) and 2-arachidonoylglycerol (2-AG) are the most studies endocannabinoids. AEA and 2-AG are degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes, respectively. FAAH and MAGL enzymes are widely expressed in many tissues, including kidney. Recent works have depicted that AEA and 2-AG levels are associated with ischemia-reperfusion (IR) injury. In this study, we investigated the effects of MAGL inhibitor KML29 and FAAH inhibitor URB597 against kidney IR injury.

METHODS

The kidneys of the rats underwent ischemia for 45 min and then reperfusion for 24 h. KML29 and URB597 were administered intraperitoneally with kidney IR to two different treatment groups.

RESULTS

IR application increased serum blood urea nitrogen (BUN), creatinine (Cre), interleukin-18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) levels, while these parameters were decreased following KML29 and URB597 administration. KML29 and URB597 administration also reduced the increased toll-like receptor-4 (TRL-4), phosphorylated-NF-κB, phosphorylated-IκB-α, tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-6 (IL-6), caspase-3 levels and histopathological damage in kidney tissue.

CONCLUSIONS

Our results reveal that MAGL inhibitor KML29 and FAAH inhibitor URB597 have a protective effect on kidney IR injury by preventing apoptosis and inflammation. Inhibition of MAGL and FAAH may be a new therapeutic strategy to prevent kidney IR injury.

Endocannabinoids and related compounds as modulators of angiogenesis: Concepts and clinical significance

Vasculogenesis (the process of differentiation of angioblasts toward endothelial cells and de novo formation of crude vascular networks) and angiogenesis (the process of harmonized sprouting and dispersal of new capillaries from previously existing ones) are two fundamentally complementary processes, obligatory for maintaining physiological functioning of vascular system. In clinical practice, however, the later one is of more importance as it guarantees correct embryonic nourishment, accelerates wound healing processes, prevents uncontrolled cell growth and tumorigenesis, contributes in supplying nutritional demand following occlusion of coronary vessels and is in direct relation with development of diabetic retinopathy. Hence, discovery of novel molecules capable of modulating angiogenic events are of great clinical importance. Recent studies have demonstrated multiple angio-regulatory activities for endocannabinoid system modulators and endocannabinoid-like molecules, as well as their metabolizing enzymes. Hence, in present article, we reviewed the regulatory roles of these molecules on angiogenesis and described molecular mechanisms underlying them.

N-Stearoylethanolamine Inhibits Integrin-Mediated Activation, Aggregation, and Adhesion of Human Platelets

N-stearoylethanolamine (NSE), a lipid mediator that belongs to the N-acylethanolamine (NAE) family, has anti-inflammatory, antioxidant, and membranoprotective actions. In contrast to other NAEs, NSE does not interact with cannabinoid receptors. The exact mechanism of its action remains unclear. The aim of this study is to evaluate the action of NSE on activation, aggregation, and adhesion of platelets that were chosen as a model of cellular response. Aggregation of platelets was measured to analyze the action of NSE (10^-6-10^-10 M) on platelet reactivity. Changes in granularity and shape of resting platelets and platelets stimulated with ADP in the presence of NSE were monitored by flow cytometry, and platelet deganulation was monitored by spectrofluorimetry. In vivo studies were performed using obese insulin-resistant rats. Binding of fibrinogen to the GPIIb/IIIa receptor was estimated using indirect ELISA and a scanning electron microscopy (SEM). It was found that NSE inhibits the activation and aggregation of human platelets. Our results suggest that NSE may decrease the activation and subsequent aggregation of platelets induced by ristocetin, epinephrine, and low doses of ADP. NSE also reduced the binding of fibrinogen to GPIIb/IIIa on activated platelets. These effects could be explained by the inhibition of platelet activation mediated by integrin receptors: the GPIb-IX-V complex for ristocetin-induced activation and GPIIb/IIIa when epinephrine and low doses of ADP were applied. The anti-platelet effect of NSE complements its anti-inflammatory effect and allows us to prioritize studies of NSE as a potent anti-thrombotic agent. SIGNIFICANCE STATEMENT: N-stearoylethanolamine (NSE) was shown to possess inhibitory action on platelet activation, adhesion, and aggregation. The mechanism of inhibition possibly involves integrin receptors. This finding complements the known anti-inflammatory effects of NSE.

Predicting futile recanalization, malignant cerebral edema, and cerebral herniation using intelligible ensemble machine learning following mechanical thrombectomy for acute ischemic stroke

Purpose

To establish an ensemble machine learning (ML) model for predicting the risk of futile recanalization, malignant cerebral edema (MCE), and cerebral herniation (CH) in patients with acute ischemic stroke (AIS) who underwent mechanical thrombectomy (MT) and recanalization.

Methods

This prospective study included 110 patients with premorbid mRS ≤ 2 who met the inclusion criteria. Futile recanalization was defined as a 90-day modified Rankin Scale score &gt;2. Clinical and imaging data were used to construct five ML models that were fused into a logistic regression algorithm using the stacking method (LR-Stacking). We added the Shapley Additive Explanation method to display crucial factors and explain the decision process of models for each patient. Prediction performances were compared using area under the receiver operating characteristic curve (AUC), F1-score, and decision curve analysis (DCA).

Results

A total of 61 patients (55.5%) experienced futile recanalization, and 34 (30.9%) and 22 (20.0%) patients developed MCE and CH, respectively. In test set, the AUCs for the LR-Stacking model were 0.949, 0.885, and 0.904 for the three outcomes mentioned above. The F1-scores were 0.882, 0.895, and 0.909, respectively. The DCA showed that the LR-Stacking model provided more net benefits for predicting MCE and CH. The most important factors were the hypodensity volume and proportion in the corresponding vascular supply area.

Conclusion

Using the ensemble ML model to analyze the clinical and imaging data of AIS patients with successful recanalization at admission and within 24 h after MT allowed for accurately predicting the risks of futile recanalization, MCE, and CH.

Prussian Blue Scavenger Ameliorates Hepatic Ischemia-Reperfusion Injury by Inhibiting Inflammation and Reducing Oxidative Stress

Oxidative stress and excessive inflammatory responses are the two critical mechanisms of hepatic ischemia-reperfusion injury (HIRI) encountered in many clinical settings, including following hepatectomy and liver transplantation. Effective anti-inflammatory and anti-oxidative pharmacological interventions are urgently needed to counter HIRI. The present study showed that a biocompatible Prussian blue (PB) scavenger with reactive oxygen species (ROS) scavenging and anti-inflammatory properties might be used a promising treatment for HIRI. Following intravenous administration, PB scavenger was mainly distributed in the liver, where it showed excellent ability to alleviate apoptosis, tissue injury and organ dysfunction after HIRI. PB scavenger was found to protect liver tissue by scavenging ROS, reducing neutrophil infiltration and promoting macrophage M2 polarization. In addition, PB scavenger significantly reduced oxidative stress in primary hepatocytes, restoring cell viability under oxidative stress condition. PB scavenger effectively reduced lipopolysaccharide-stimulated inflammation in RAW 264.7 cells. These findings indicate that PB scavenger may be a potential therapeutic agent for the treatment of HIRI, providing an alternative treatment for ROS-associated and inflammatory liver diseases.

Role of cannabinoids and the endocannabinoid system in modulation of diabetic cardiomyopathy

Diabetic complications, chiefly seen in long-term situations, are persistently deleterious to a large extent, requiring multi-factorial risk reduction strategies beyond glycemic control. Diabetic cardiomyopathy is one of the most common deleterious diabetic complications, being the leading cause of mortality among diabetic patients. The mechanisms of diabetic cardiomyopathy are multi-factorial, involving increased oxidative stress, accumulation of advanced glycation end products (AGEs), activation of various pro-inflammatory and cell death signaling pathways, and changes in the composition of extracellular matrix with enhanced cardiac fibrosis. The novel lipid signaling system, the endocannabinoid system, has been implicated in the pathogenesis of diabetes and its complications through its two main receptors: Cannabinoid receptor type 1 and cannabinoid receptor type 2, alongside other components. However, the role of the endocannabinoid system in diabetic cardiomyopathy has not been fully investigated. This review aims to elucidate the possible mechanisms through which cannabinoids and the endocannabinoid system could interact with the pathogenesis and the development of diabetic cardiomyopathy. These mechanisms include oxidative/ nitrative stress, inflammation, accumulation of AGEs, cardiac remodeling, and autophagy. A better understanding of the role of cannabinoids and the endocannabinoid system in diabetic cardiomyopathy may provide novel strategies to manipulate such a serious diabetic complication.

Cannabis sativa and/or melatonin do not alter brain lipid but alter oxidative mechanisms in female rats

Background

Lipid profile and redox status play a role in brain (dys)functions. Cannabinoid and melatonergic systems operate in the brain and contribute to brain (patho)physiology, but their roles in the modulation of brain lipid and redox status are not well-known. We studied the effect of ethanol extract of Cannabis sativa (CS) and/or melatonin (M) on the lipid profile and anti-oxidant system of the rat brain.

Methods

We randomly divided twenty-four (24) female Wistar rats into 4 groups (n = 6 rats each). Group 1 (control) received distilled water mixed with DMSO. Groups II–IV received CS (2 mg/kg), M (4 mg/kg), and co-administration of CS and M (CS + M) respectively via oral gavage between 8:00 am and 10:00 am once daily for 14 days. Animals underwent 12-h fasting after the last day of treatment and sacrificed under ketamine anesthesia (20 mg/kg; i.m). The brain tissues were excised and homogenized for assay of the concentrations of the total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), nitric oxide (NO), malondialdehyde (MDA), and the activities of glucose-6-phosphate dehydrogenase (G6PD), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and acetylcholinesterase (AChE). One-way analysis of variance (ANOVA) was used to compare means across groups, followed by the least significant difference (LSD) post-hoc test.

Results

CS and/or M did not affect the lipid profile parameters. However, CS increased the G6PD (from 15.58 ± 1.09 to 21.02 ± 1.45 U/L; p = 0.047), GPx (from 10.47 ± 0.86 to 17.71 ± 1.04 U/L; p = 0.019), and SOD (from 0.81 ± 0.02 to 0.90 ± 0.01 μM; p = 0.007), but decreased NO (from 9.40 ± 0.51 to 6.75 ± 0.21 μM; p = 0.010) and had no effect on MDA (p = 0.905), CAT (p = 0.831), GR (p = 0.639), and AChE (p = 0.571) in comparison with the control group. M augmented the increase in G6PD (from 21.02 ± 1.45 U/L to 27.18 ± 1.81 U/L; p = 0.032) and decrease in NO (from 6.75 ± 0.21 to 4.86 ± 0.13 μM; p = 0.034) but abolished the increase in GPx (from 17.71 ± 1.04 to 8.59 ± 2.06 U/L; p = 0.006) and SOD (from 0.90 ± 0.01 to 0.70 ± 0.00 μM; p = 0.000) elicited by CS in the rat brain in comparison with the CS group.

Conclusions

CS and M do not alter brain lipid profile. Our data support the contention that CS elicits an anti-oxidative effect on the brain tissue and that CS + M elicits a pro-oxidant effect in rat brain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42238-021-00095-9.

The Critical Role of Cannabinoid Receptor 2 in URB602-Induced Protective Effects Against Renal Ischemia-Reperfusion Injury in the Rat

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and even induces remote organ damage. Accumulating proofs demonstrates that the endocannabinoid system may provide a promising access for treatment strategy of renal IRI associated AKI. In the current study, using the established renal IRI model of rat, we tested the hypothesis that pretreatment of URB602, 30 min before renal IRI, alleviates kidney injury and relevant distant organ damage via limiting oxidative stress and inflammation. Using Western blot analysis and LC-MS/MS, renal IRI showed to increase the levels of 2-arachidonoylglycerol (2-AG) in kidneys as well as COX-2, PGE2, TXA2, and decrease N-arachidonoylethanolamine (anandamide, AEA); the expressions of renal cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) were unchanged. The URB602 pretreatment in renal IRI, further enhanced renal 2-AG which is high affinity to both CB1 and CB2, and reduced renal COX-2 which is involved in the regulation of renal perfusion and inflammation. AM630 (CB2 antagonist) almost blocked all the antioxidant, anti-inflammatory and nephroprotective effects of URB602, whereas AM251 (CB1 antagonist) showed limited influence, and parecoxib (COX-2 inhibitor) slightly ameliorated renal function at the dose of 10 mg/kg. Taken together, our data indicate that URB602 acts as a reactive oxygen species scavenger and anti-inflammatory media in renal IRI mainly depending on the activation of CB2.

Pharmacological Properties, Therapeutic Potential and Molecular Mechanisms of JWH133, a CB2 Receptor-Selective Agonist

The endocannabinoid system has attracted attention as a pharmacological target for several pathological conditions. Cannabinoid (CB2)-selective agonists have been the focus of pharmacological studies because modulation of the CB2 receptor (CB2R) can be useful in the treatment of pain, inflammation, arthritis, addiction, and cancer among other possible therapeutic applications while circumventing CNS-related adverse effects. Increasing number of evidences from different independent preclinical studies have suggested new perspectives on the involvement of CB2R signaling in inflammation, infection and immunity, thus play important role in cancer, cardiovascular, renal, hepatic and metabolic diseases. JWH133 is a synthetic agonist with high CB2R selectivity and showed to exert CB2R mediated antioxidant, anti-inflammatory, anticancer, cardioprotective, hepatoprotective, gastroprotective, nephroprotective, and immunomodulatory activities. Cumulative evidences suggest that JWH133 protects against hepatic injury, renal injury, cardiotoxicity, fibrosis, rheumatoid arthritis, and cancer as well as against oxidative damage and inflammation, inhibits fibrosis and apoptosis, and acts as an immunosuppressant. This review provides a comprehensive overview of the polypharmacological properties and therapeutic potential of JWH133. This review also presents molecular mechanism and signaling pathways of JWH133 under various pathological conditions except neurological diseases. Based on the available data, this review proposes the possibilities of developing JWH133 as a promising therapeutic agent; however, further safety and toxicity studies in preclinical studies and clinical trials in humans are warranted.

Cannabinoid Receptors in Myocardial Injury: A Brother Born to Rival

Cannabinoid receptors typically include type 1 (CB1) and type 2 (CB2), and they have attracted extensive attention in the central nervous system (CNS) and immune system. Due to more in-depth studies in recent years, it has been found that the typical CB1 and CB2 receptors confer functional importance far beyond the CNS and immune system. In particular, many works have reported the critical involvement of the CB1 and CB2 receptors in myocardial injuries. Both pharmacological and genetic approaches have been used for studying CB1 and CB2 functions in these studies, revealing that the brother receptors have many basic differences and sometimes antagonistic functions in a variety of myocardial injuries, despite some sequence or location identity they share. Herein, we introduce the general differences of CB1 and CB2 cannabinoid receptors, and summarize the functional rivalries between the two brother receptors in the setting of myocardial injuries. We point out the importance of individual receptor-based modulation, instead of dual receptor modulators, when treating myocardial injuries.

The endocannabinoidome in neuropsychiatry: Opportunities and potential risks

The endocannabinoid system (ECS) comprises two cognate endocannabinoid receptors referred to as CB1R and CB2R_. ECS dysregulation is apparent in neurodegenerative/neuro-psychiatric disorders including but not limited to schizophrenia, major depressive disorder and potentially bipolar disorder. The aim of this paper is to review mechanisms whereby both receptors may interact with neuro-immune and neuro-oxidative pathways, which play a pathophysiological role in these disorders. CB1R is located in the presynaptic terminals of GABAergic, glutamatergic, cholinergic, noradrenergic and serotonergic neurons where it regulates the retrograde suppression of neurotransmission. CB1R plays a key role in long-term depression, and, to a lesser extent, long-term potentiation, thereby modulating synaptic transmission and mediating learning and memory. Optimal CB1R activity plays an essential neuroprotective role by providing a defense against the development of glutamate-mediated excitotoxicity, which is achieved, at least in part, by impeding AMPA-mediated increase in intracellular calcium overload and oxidative stress. Moreover, CB1R activity enables optimal neuron-glial communication and the function of the neurovascular unit. CB2R receptors are detected in peripheral immune cells and also in central nervous system regions including the striatum, basal ganglia, frontal cortex, hippocampus, amygdala as well as the ventral tegmental area. CB2R upregulation inhibits the presynaptic release of glutamate in several brain regions. CB2R activation also decreases neuroinflammation partly by mediating the transition from a predominantly neurotoxic "M1" microglial phenotype to a more neuroprotective "M2" phenotype. CB1R and CB2R are thus novel drug targets for the treatment of neuro-immune and neuro-oxidative disorders including schizophrenia and affective disorders.

Role of liver sinusoidal endothelial cells in liver diseases

Liver sinusoidal endothelial cells (LSECs) form the wall of the hepatic sinusoids. Unlike other capillaries, they lack an organized basement membrane and have cytoplasm that is penetrated by open fenestrae, making the hepatic microvascular endothelium discontinuous. LSECs have essential roles in the maintenance of hepatic homeostasis, including regulation of the vascular tone, inflammation and thrombosis, and they are essential for control of the hepatic immune response. On a background of acute or chronic liver injury, LSECs modify their phenotype and negatively affect neighbouring cells and liver disease pathophysiology. This Review describes the main functions and phenotypic dysregulations of LSECs in liver diseases, specifically in the context of acute injury (ischaemia-reperfusion injury, drug-induced liver injury and bacterial and viral infection), chronic liver disease (metabolism-associated liver disease, alcoholic steatohepatitis and chronic hepatotoxic injury) and hepatocellular carcinoma, and provides a comprehensive update of the role of LSECs as therapeutic targets for liver disease. Finally, we discuss the open questions in the field of LSEC pathobiology and future avenues of research.

Beta-Caryophyllene, a CB2R Selective Agonist, Protects Against Cognitive Impairment Caused by Neuro-inflammation and Not in Dementia Due to Ageing Induced by Mitochondrial Dysfunction

BACKGROUND

Dementia is a neurodegenerative disorder majorly evidenced by cognitive impairment. Although there are many types of dementia, the common underlying etiological factors in all the types are neuro-inflammation or aging induced apoptosis. β-caryophyllene, a cannabinoid type-2 receptor agonist, has been reported to have promising neuroprotective effects in cerebral ischemia and neuro-inflammation.

OBJECTIVE

In the present study, we evaluated the effects of β-caryophyllene against animal models of dementia whose etiology mimicked neuro-inflammation and aging.

METHODS

Two doses (50 and 100 mg/kg of body weight) of β-caryophyllene given orally were tested against AlCl₃-induced dementia in male Sprague Dawley (SD) rats using the Morris water maze test. Subsequently, the effect of the drug was assessed for episodic memory in female SD rats using novel object recognition task in doxorubicin-induced neuro-inflammation and chemobrain model. Moreover, its effects were evaluated in D-galactose-induced mitochondrial dysfunction leading to dementia.

RESULTS

β-caryophyllene, at both doses, showed significant improvement in memory when assessed using parameters like target quadrant entries, escape latency and path efficiency in the Morris water maze test for spatial memory. In the doxorubicin-induced chemobrain model, β-caryophyllene at 100 mg/kg significantly elevated acetylcholinesterase and catalase levels and lowered lipid peroxidation compared to the disease control. In the novel object recognition task, β-caryophyllene at 100 mg/kg significantly improved recognition index and discrimination index in the treated animals compared to the disease control, with a significant increase in catalase and a decrease in lipid peroxidation in both hippocampus and frontal cortex. However, in the D-galactose-induced mitochondrial dysfunction model, β-caryophyllene failed to show positive effects when spatial memory was assessed. It also failed to improve D-galactose-induced diminished mitochondrial complex I and II activities.

CONCLUSION

Hence, we conclude that β-caryophyllene at 100 mg/kg protects against dementia induced by neuro-inflammation with no effect on neuronal aging induced by mitochondrial dysfunction.

Synthetic Cannabinoids and Cathinones Cardiotoxicity: Facts and Perspectives

New psychoactive substances (NPS) constitute a group of psychotropic substances, designed to mimic the effects of traditional substances like cannabis, cocaine, MDMA, khat, which was not regulated by the 1961 United Nations Convention on Narcotics or the 1971 United Nations Convention on Psychotropic Substances. Illegal laboratories responsible for their production regularly developed new substances and placed them on the market to replace the ones that have been banned; for this reason, during the last decade this class of substances has represented a great challenge for the public health and forensic toxicologists. The spectrum of side effects caused by the intake of these drugs of abuse is very wide since they act on different systems with various mechanisms of action. To date most studies have focused on the neurotoxic effects, very few works focus on cardiotoxicity. Specifically, both synthetic cannabinoids and synthetic cathinones appear to be involved in different cardiac events, including myocardial infarction and sudden cardiac death due to fatal arrhythmias. Synthetic cannabinoids and cathinones cardiotoxicity are mainly mediated through activation of the CB1 receptor present on cardiomyocyte and involved with reactive oxygen species production, ATP depletion and cell death. Concerns with the adrenergic over-stimulation induced by this class of substances and increasing oxidative stress are mainly reported. In this systematic review we aim to summarize the data from all the works analyzing the possible mechanisms through which synthetic cannabinoids and synthetic cathinones damage the myocardial tissue.

Targeting of G-protein coupled receptors in sepsis

The Third International Consensus Definitions (Sepsis-3) define sepsis as life-threatening multi-organ dysfunction caused by a dysregulated host response to infection. Sepsis can progress to septic shock-an even more lethal condition associated with profound circulatory, cellular and metabolic abnormalities. Septic shock remains a leading cause of death in intensive care units and carries a mortality of almost 25%. Despite significant advances in our understanding of the pathobiology of sepsis, therapeutic interventions have not translated into tangible differences in the overall outcome for patients. Clinical trials of antagonists of various pro-inflammatory mediators in sepsis have been largely unsuccessful in the past. Given the diverse physiologic roles played by G-protein coupled receptors (GPCR), modulation of GPCR signaling for the treatment of sepsis has also been explored. Traditional pharmacologic approaches have mainly focused on ligands targeting the extracellular domains of GPCR. However, novel techniques aimed at modulating GPCR intracellularly through aptamers, pepducins and intrabodies have opened a fresh avenue of therapeutic possibilities. In this review, we summarize the diverse roles played by various subfamilies of GPCR in the pathogenesis of sepsis and identify potential targets for pharmacotherapy through these novel approaches.

Dexmedetomidine Ameliorates Lung Injury Induced by Intestinal Ischemia/Reperfusion by Upregulating Cannabinoid Receptor 2, Followed by the Activation of the Phosphatidylinositol 3-Kinase/Akt Pathway

Intestinal ischemia/reperfusion (I/R) is a clinical emergency, which often causes lung injury with high morbidity and mortality. Although dexmedetomidine has been identified to have a protective effect on lung injury caused by intestinal I/R, its specific mechanism is still elucidated. In recent years, the cannabinoid (CB₂) receptor pathway has been found to be involved in I/R injury of some organs. In the current study, we investigated whether the CB₂ receptor pathway contributes to the protective effect of dexmedetomidine on the intestinal I/R-induced lung injury in rats. Dexmedetomidine treatment upregulated the expression of CB₂ receptor and suppressed the I/R-induced increases in lung injury scores, inflammatory cell infiltration, lung wet/dry ratio, MPO activity, MDA level, inflammatory cytokines, and caspase-3 expression while augmenting SOD activity and Bcl-2 expression, indicating attenuation of lung injury. Dexmedetomidine treatment also increased the expression of Akt. The protective effects of dexmedetomidine treatment were reversed by the CB₂ receptor antagonist AM630 or the PI3K inhibitor wortmannin. And the CB₂ receptor antagonist AM630 also downregulated the expression of Akt. Thus, our findings suggest that treatment with dexmedetomidine provides a protective role against lung injury caused by intestinal I/R in rats, possibly due to the upregulation of the CB₂ receptor, followed by the activation of the PI3K/Akt pathway.

Bioactive Lipid Signaling in Cardiovascular Disease, Development, and Regeneration

Cardiovascular disease (CVD) remains a leading cause of death globally. Understanding and characterizing the biochemical context of the cardiovascular system in health and disease is a necessary preliminary step for developing novel therapeutic strategies aimed at restoring cardiovascular function. Bioactive lipids are a class of dietary-dependent, chemically heterogeneous lipids with potent biological signaling functions. They have been intensively studied for their roles in immunity, inflammation, and reproduction, among others. Recent advances in liquid chromatography-mass spectrometry techniques have revealed a staggering number of novel bioactive lipids, most of them unknown or very poorly characterized in a biological context. Some of these new bioactive lipids play important roles in cardiovascular biology, including development, inflammation, regeneration, stem cell differentiation, and regulation of cell proliferation. Identifying the lipid signaling pathways underlying these effects and uncovering their novel biological functions could pave the way for new therapeutic strategies aimed at CVD and cardiovascular regeneration.

Innovative Therapeutic Potential of Cannabinoid Receptors as Targets in Alzheimer’s Disease and Less Well-Known Diseases

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The discovery of cannabinoid receptors at the beginning of the 1990s, CB1 cloned in 1990 and CB2 cloned in 1993, and the availability of selective and potent cannabimimetics could only be justified by the existence of endogenous ligands that are capable of binding to them. Thus, the characterisation and cloning of the first cannabinoid receptor (CB1) led to the isolation and characterisation of the first endocannabinoid, arachidonoylethanolamide (AEA), two years later and the subsequent identification of a family of lipid transmitters known as the fatty acid ester 2-arachidonoylglycerol (2-AG).

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The endogenous cannabinoid system is a complex signalling system that comprises transmembrane endocannabinoid receptors, their endogenous ligands (the endocannabinoids), the specific uptake mechanisms and the enzymatic systems related to their biosynthesis and degradation.

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The endocannabinoid system has been implicated in a wide diversity of biological processes, in both the central and peripheral nervous systems, including memory, learning, neuronal development, stress and emotions, food intake, energy regulation, peripheral metabolism, and the regulation of hormonal balance through the endocrine system.

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In this context, this article will review the current knowledge of the therapeutic potential of cannabinoid receptor as a target in Alzheimer’s disease and other less well-known diseases that include, among others, multiple sclerosis, bone metabolism, and Fragile X syndrome.

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The therapeutic applications will be addressed through the study of cannabinoid agonists acting as single drugs and multi-target drugs highlighting the CB2 receptor agonist.

Role of CB2 Receptor in the Recovery of Mice after Traumatic Brain Injury

Cannabis is one of the most widely used plant drugs in the world today. In spite of the large number of scientific reports on medical marijuana, there still exists much controversy surrounding its use and the potential for abuse due to the undesirable psychotropic effects. However, recent developments in medicinal chemistry of novel non-psychoactive synthetic cannabinoids have indicated that it is possible to separate some of the therapeutic effects from the psychoactivity. We have previously shown that treatment with the endocannabinoid 2-AG, which binds to both CB1 and CB2 receptors 1 h after traumatic brain injury in mice, attenuates neurological deficits, edema formation, infarct volume, blood-brain barrier permeability, neuronal cell loss at the CA3 hippocampal region, and neuroinflammation. Recently, we synthesized a set of camphor-resorcinol derivatives, which represent a novel series of CB2 receptor selective ligands. Most of the novel compounds exhibited potent binding and agonistic properties at the CB2 receptors with very low affinity for the CB1 receptor, and some were highly anti-inflammatory. This selective binding correlated with their intrinsic activities. HU-910 and HU-914 were selected in the present study to evaluate their potential effect in the pathophysiology of traumatic brain injury (TBI). In mice and rats subjected to closed-head injury and treated with these novel compounds, we showed enhanced neurobehavioral recovery, inhibition of tumor necrosis factor α production, increased synaptogenesis, and partial recovery of the cortical spinal tract. We propose these CB2 agonists as potential drugs for development of novel therapeutic modality to TBI.

Activation of cannabinoid type 2 receptor protects skeletal muscle from ischemia-reperfusion injury partly via Nrf2 signaling

AIMS

Cannabinoid type 2 (CB₂) receptor activation has been shown to attenuate IRI in various organs. NF-E2-related factor (Nrf2) is an anti-oxidative factor that plays multiple roles in regulating cellular redox homeostasis and modulating cell proliferation and differentiation. The protective effects of CB₂ receptor activation on skeletal muscle IRI and the underlying mechanism that involves Nrf2 signaling remain unknown.

MAIN METHODS

We evaluated the in vivo effect of CB₂ receptor activation by the CB₂ receptor agonist AM1241 on IR-induced skeletal muscle damage and early myogenesis. We also assessed the effects of CB₂ receptor activation on C2C12 myoblasts differentiation and H₂O₂-induced C2C12 myoblasts damage in vitro, with a focus on the mechanism of Nrf2 signaling.

KEY FINDINGS

Our results showed that CB₂ receptor activation reduced IR-induced histopathological lesions, edema, and oxidative stress 1 day post-injury and accelerated early myogenesis 4 days post-injury in mice. Nrf2 knockout mice that were treated with AM1241 exhibited deteriorative skeletal muscle oxidative damage and myogenesis. In vitro, pretreatment with AM1241 significantly increased the expression of Nrf2 and its nuclear translocation, attenuated the decrease in H₂O₂-induced C2C12 cell viability, and decreased reactive oxygen species generation and apoptosis. CB₂ receptor activation also significantly enhanced C2C12 myoblasts differentiation, which was impaired by silencing Nrf2.

SIGNIFICANCE

Overall, CB₂ receptor activation protected skeletal muscle against IRI by ameliorating oxidative damage and promoting early skeletal muscle myogenesis, which was partly via Nrf2 signaling.

AM-1241 CB2 Receptor Agonist Attenuates Inflammation, Apoptosis and Stimulate Progenitor Cells in Bile Duct Ligated Rats

BACKGROUND:

The cannabinoid receptor 2 (CB2) plays a pleiotropic role in the innate immunity and is considered a crucial mediator of liver disease. Cannabinoid CB2 receptor activation has been reported to attenuate liver fibrosis in CCl4 exposed mice and also plays a potential role in liver regeneration in a mouse model of I/R and protection against alcohol-induced liver injury.

AIM:

In this study, we investigated the impact of CB2 receptors on the antifibrotic and regenerative process associated with cholestatic liver injury.

METHODS:

Twenty-six rats had bile duct ligation co-treated with silymarin and AM1241 for 3 consecutive weeks. Serum hepatotoxicity markers were determined, and histopathological evaluation was performed.

RESULTS:

Following bile duct ligation (BDL) for 3 weeks, there was increased aminotransferase levels, marked inflammatory infiltration and hepatocyte apoptosis with induced oxidative stress, as reflected by increased lipid peroxidation. Conversely, following treatment with the CB2 agonist, AM-1241, BDL rats displayed a reduction in liver injury and attenuation of fibrosis as reflected by expression of hydroxyproline and α-smooth muscle actin. AM1241 treatment also significantly attenuated lipid peroxidation end-products, p53-dependent apoptosis and also attenuated inflammatory process by stimulating IL-10 production. Moreover, AM1241 treated rats were associated with significant expression of hepatic progenitor/oval cell markers.

CONCLUSION:

In conclusion, this study points out that CB2 receptors reduce liver injury and promote liver regeneration via distinct mechanisms including IL-10 dependent inhibition of inflammation, reduction of p53-reliant apoptosis and through stimulation of oval/progenitor cells. These results suggest that CB2 agonists display potent hepatoregenrative properties, in addition to their antifibrogenic effects.

Posttreatment With the Fatty Acid Amide Hydrolase Inhibitor URB937 Ameliorates One-Lung Ventilation-Induced Lung Injury in a Rabbit Model

BACKGROUND

One-lung ventilation (OLV)-induced inflammation is a risk factor for acute lung injury that is responsible for 20% of postoperative pulmonary complications after lung resection. Inflammation is an important trigger for acute lung injury. Fatty acid amide hydrolase (FAAH) is the major enzyme that degrades the endocannabinoid arachidonoylethanolamine (AEA), an important regulator of inflammation, and its downstream metabolites such as arachidonic acid (AA) are also involved in inflammation. Importantly, AEA is also found in lung parenchyma. However, it remains unclear whether pharmacological inhibition of FAAH inhibitor using compounds such as URB937 can attenuate OLV-induced lung injury.

MATERIALS AND METHODS

New Zealand white rabbits were anesthetized to establish a modified OLV-induced lung injury model. Twenty-four male rabbits were randomly divided into four groups (n = 6): TLV-S (2.5-h two-lung ventilation [TLV] + 1.5 mL/kg saline + 1-h TLV), OLV-S (2.5-h OLV + 1.5 mL/kg saline + 0.5-h OLV + 0.5-h TLV), U-OLV (1.5 mL/kg URB937 + 3.0-h OLV + 0.5-h TLV), and OLV-U (2.5-h OLV + 1.5 mL/kg URB937 + 0.5-h OLV + 0.5-h TLV). Arterial blood gases, lung wet/dry ratio, and lung injury score of the nonventilated lungs were measured. The levels of AEA, AA, prostaglandin I2 (PGI2), thromboxane A2 (TXA2), and leukotriene B4 (LTB4) in the nonventilated lung were also quantified.

RESULTS

The arterial oxygenation index (PaO₂/FiO₂) decreased after 0.5-h OLV in the three OLV groups. The PaO₂/FiO₂ in the OLV-U group was better than that in the OLV-S and U-OLV groups and was accompanied with reductions in the wet/dry ratio and lung injury scores of the nonventilated lungs. The FAAH inhibitor URB937 administered not before but 2.5 h after OLV attenuated OLV-induced lung injury by increasing AEA levels and reducing the levels of downstream metabolites including AA, PGI2, TXA2, and LTB4.

CONCLUSIONS

Posttreatment with the FAAH inhibitor URB937 attenuated OLV-induced lung injury in rabbits and was associated with increased AEA levels and decreased levels of AA and its downstream metabolites.

Endocannabinoid Virodhamine Is an Endogenous Inhibitor of Human Cardiovascular CYP2J2 Epoxygenase

The human body contains endogenous cannabinoids (endocannabinoids) that elicit effects similar to those of Δ9-tetrahydrocanabinol, the principal bioactive component of cannabis. The endocannabinoid virodhamine (O-AEA) is the constitutional isomer of the well-characterized cardioprotective and anti-inflammatory endocannabinoid anandamide (AEA). The chemical structures of O-AEA and AEA contain arachidonic acid (AA) and ethanolamine; however, AA in O-AEA is connected to ethanolamine via an ester linkage, whereas AA in AEA is connected through an amide linkage. O-AEA is involved in regulating blood pressure and cardiovascular function. We show that O-AEA is found at levels 9.6-fold higher than that of AEA in porcine left ventricle. On a separate note, the cytochrome P450 (CYP) epoxygenase CYP2J2 is the most abundant CYP in the heart where it catalyzes the metabolism of AA and AA-derived eCBs to bioactive epoxides that are involved in diverse cardiovascular functions. Herein, using competitive binding studies, kinetic metabolism measurements, molecular dynamics, and wound healing assays, we have shown that O-AEA is an endogenous inhibitor of CYP2J2 epoxygenase. As a result, the role of O-AEA as an endogenous eCB inhibitor of CYP2J2 may provide a new mode of regulation to control the activity of cardiovascular CYP2J2 in vivo and suggests a potential cross-talk between the cardiovascular endocannabinoids and the cytochrome P450 system.

Effects of monoacylglycerol lipase inhibitor URB602 on lung ischemia-reperfusion injury in mice

Lung ischemia-reperfusion injury (LIRI) is a common and severe postoperative pathologic complication that often occurs when the oxygen supply disrupted to the lung tissue fallowed by reperfusion period, in most cases after lung transplantation and cardiopulmonary bypass. Endocannabinoids such as 2-arachidonoylglycerol (2-AG) have very important role as regulators of inflammation. Monoacylglycerol lipase (MAGL) is the main 2-AG-degrading enzyme, and the downstream metabolites of 2-AG play a role in the inflammation. Ischemia reperfusion (IR) was induced by clamping the left pulmonary hilum for 60 min, followed by 120 min of reperfusion in male C57BL/6 mice. Effects of URB602, a MAGL inhibitor, were evaluated in a preventive or therapeutic regimen (5 min before ischemia or reperfusion, respectively). Oxygenation index, wet-to-dry weight ratio and lung injury score were analyzed. Endocannabinoids including 2-AG, anandamide (AEA) and arachidonic acid (AA) levels, metabolites such as Prostaglandin I₂ (PGI₂), Thromboxane B₂ (TXB₂) and Leukotrienes B₄ (LTB₄) and inflammatory markers (Interleukin 6 (IL-6) andTumor necrosis factor-α (TNF-α)) in lung tissues were measured by using mass spectrometry or ELISA analyses. We found that IR increased the wet-to-dry weight ratio of lung and lung injury score and decreased oxygenation index as compared to the sham group. Moreover, treatment with URB602 in preventive or therapeutic regimen reduced the wet-to-dry weight ratio and lung injury score while increased oxygenation index when compared with the IR group, with a more improvement in the preventive regimen group. In addition, treatment with URB602 before ischemia increased 2-AG level but decreased metabolites (AA, PGI₂, TXB₂, LTB₄) and inflammatory markers (IL-6, TNF-α). Thus, our study demonstrated that a pretreatment with URB602 significantly reduced IR-induced lung injury and inflammation. URB602 inhibited LIRI and inflammation by increasing 2-AG level and reducing downstream metabolites from AA to PGI₂, TXB₂ and LTB₄ in lung tissues.

Modulation of the Oxidative Stress and Lipid Peroxidation by Endocannabinoids and Their Lipid Analogues

Growing evidence supports the pivotal role played by oxidative stress in tissue injury development, thus resulting in several pathologies including cardiovascular, renal, neuropsychiatric, and neurodegenerative disorders, all characterized by an altered oxidative status. Reactive oxygen and nitrogen species and lipid peroxidation-derived reactive aldehydes including acrolein, malondialdehyde, and 4-hydroxy-2-nonenal, among others, are the main responsible for cellular and tissue damages occurring in redox-dependent processes. In this scenario, a link between the endocannabinoid system (ECS) and redox homeostasis impairment appears to be crucial. Anandamide and 2-arachidonoylglycerol, the best characterized endocannabinoids, are able to modulate the activity of several antioxidant enzymes through targeting the cannabinoid receptors type 1 and 2 as well as additional receptors such as the transient receptor potential vanilloid 1, the peroxisome proliferator-activated receptor alpha, and the orphan G protein-coupled receptors 18 and 55. Moreover, the endocannabinoids lipid analogues N-acylethanolamines showed to protect cell damage and death from reactive aldehydes-induced oxidative stress by restoring the intracellular oxidants-antioxidants balance. In this review, we will provide a better understanding of the main mechanisms triggered by the cross-talk between the oxidative stress and the ECS, focusing also on the enzymatic and non-enzymatic antioxidants as scavengers of reactive aldehydes and their toxic bioactive adducts.

Neuroprotection in Oxidative Stress-Related Neurodegenerative Diseases: Role of Endocannabinoid System Modulation

SIGNIFICANCE

Redox imbalance may lead to overproduction of reactive oxygen and nitrogen species (ROS/RNS) and subsequent oxidative tissue damage, which is a critical event in the course of neurodegenerative diseases. It is still not fully elucidated, however, whether oxidative stress is the primary trigger or a consequence in the process of neurodegeneration. Recent Advances: Increasing evidence suggests that oxidative stress is involved in the propagation of neuronal injury and consequent inflammatory response, which in concert promote development of pathological alterations characteristic of most common neurodegenerative diseases.

CRITICAL ISSUES

Accumulating recent evidence also suggests that there is an important interplay between the lipid endocannabinoid system [ECS; comprising the main cannabinoid 1 and 2 receptors (CB1 and CB2), endocannabinoids, and their synthetic and metabolizing enzymes] and various key inflammatory and redox-dependent processes.

FUTURE DIRECTIONS

Targeting the ECS to modulate redox state-dependent cell death and to decrease consequent or preceding inflammatory response holds therapeutic potential in a multitude of oxidative stress-related acute or chronic neurodegenerative disorders from stroke and traumatic brain injury to Alzheimer's and Parkinson's diseases and multiple sclerosis, just to name a few, which will be discussed in this overview. Antioxid. Redox Signal. 29, 75-108.

Targeting pain at its source in sickle cell disease

Sickle cell disease (SCD) is a genetic disorder associated with hemolytic anemia, end-organ damage, reduced survival, and pain. One of the unique features of SCD is recurrent and unpredictable episodes of acute pain due to vasoocclusive crisis requiring hospitalization. Additionally, patients with SCD often develop chronic persistent pain. Currently, sickle cell pain is treated with opioids, an approach limited by adverse effects. Because pain can start at infancy and continue throughout life, preventing the genesis of pain may be relatively better than treating the pain once it has been evoked. Therefore, we provide insights into the cellular and molecular mechanisms of sickle cell pain that contribute to the activation of the somatosensory system in the peripheral and central nervous systems. These mechanisms include mast cell activation and neurogenic inflammation, peripheral nociceptor sensitization, maladaptation of spinal signals, central sensitization, and modulation of neural circuits in the brain. In this review, we describe potential preventive/therapeutic targets and their targeting with novel pharmacologic and/or integrative approaches to ameliorate sickle cell pain.

Experimental ischemia/reperfusion model impairs endocannabinoid signaling and Na+/K+ ATPase expression and activity in kidney proximal tubule cells

LLC-PK1 cells, an immortalized epithelial cell line derived from pig renal proximal tubules, express all the major players of the endocannabinoid system (ECS) such as CB1, CB2 and TRPV1 receptors, as well as the main enzymes involved in the biosynthesis and degradation of the major endocannabinoids named 2-arachidonoylglycerol, 2-AG and anandamide, AEA. Here we investigated whether the damages caused by ischemic insults either in vitro using LLC-PK1 cells exposed to antimycin A (an inductor of ATP-depletion) or in vivo using Wistar rats in a classic renal ischemia and reperfusion (IR) protocol, lead to changes in AEA and 2-AG levels, as well as altered expression of genes from the main enzymes involved in the regulation of the ECS. Our data show that the mRNA levels of the CB1 receptor gene were downregulated, while the transcript levels of monoacylglycerol lipase (MAGL), the main 2-AG degradative enzyme, were upregulated in LLC-PK1 cells after IR model. Accordingly, IR was accompanied by a significant reduction in the levels of 2-AG and AEA, as well as of the two endocannabinoid related molecules, oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) in LLC-PK1 cells. In kidney cortex homogenates, only AEA levels were significantly decreased. In addition, we found that in both the in vitro and in vivo model IR caused a reduction in the expression and activity of the Na⁺/K⁺ ATPase. These changes were reversed by the CB1/CB2 agonist WIN55,212, in a CB1-receptor dependent manner in the LLC-PK1 IR model. In conclusion, the ECS and Na⁺/K⁺ ATPase are down-regulated following IR in LLC-PK1 cells and rat kidney. We suggest that CB1 agonists might represent a potential strategy to reverse the consequences of IR injury in kidney tissues.

Limb Remote Ischemic Conditioning: Mechanisms, Anesthetics, and the Potential for Expanding Therapeutic Options

Novel and innovative approaches are essential in developing new treatments and improving clinical outcomes in patients with ischemic stroke. Remote ischemic conditioning (RIC) is a series of mechanical interruptions in blood flow of a distal organ, following end organ reperfusion, shown to significantly reduce infarct size through inhibition of oxidation and inflammation. Ischemia/reperfusion (I/R) is what ultimately leads to the irreversible brain damage and clinical picture seen in stroke patients. There have been several reports and reviews about the potential of RIC in acute ischemic stroke; however, the focus here is a comprehensive look at the differences in the three types of RIC (remote pre-, per-, and postconditioning). There are some limited uses of preconditioning in acute ischemic stroke due to the unpredictability of the ischemic event; however, it does provide the identification of biomarkers for clinical studies. Remote limb per- and postconditioning offer a more promising treatment during patient care as they can be harnessed during or after the initial ischemic insult. Though further research is needed, it is imperative to discuss the importance of preclinical data in understanding the methods and mechanisms involved in RIC. This understanding will facilitate translation to a clinically feasible paradigm for use in the hospital setting.

Acute administration of beta-caryophyllene prevents endocannabinoid system activation during transient common carotid artery occlusion and reperfusion

BACKGROUND

The transient global cerebral hypoperfusion/reperfusion achieved by induction of Bilateral Common Carotid Artery Occlusion followed by Reperfusion (BCCAO/R) has been shown to stimulate early molecular changes that can be easily traced in brain tissue and plasma, and that are indicative of the tissue physiological response to the reperfusion-induced oxidative stress and inflammation. The aim of the present study is to probe the possibility to prevent the molecular changes induced by the BCCAO/R with dietary natural compounds known to possess anti-inflammatory activity, such as the phytocannabinoid beta-caryophyllene (BCP).

METHODS

Two groups of adult Wistar rats were used, sham-operated and submitted to BCCAO/R. In both groups, 6 h before surgery, half of the rats were gavage-fed with a single dose of BCP (40 mg/per rat in 300 μl of sunflower oil as vehicle), while the second half were pre-treated with the vehicle alone. HPLC, Western Blot and immunohistochemistry were used to analyze cerebral cortex and plasma.

RESULTS

After BCCAO/R, BCP prevented the increase of lipoperoxides occurring in the vehicle-treated rats in both cerebral cortex and plasma. In the frontal cortex, BCP further prevented activation of the endocannabinoid system (ECS), spared the docosahexaenoic acid (DHA), appeared to prevent the increase of cyclooxygenase-2 and increased the peroxisome-proliferator activated receptor-alpha (PPAR-alpha) protein levels, while, in plasma, BCP induced the reduction of arachidonoylethanolamide (AEA) levels as compared to vehicle-treated rats.

CONCLUSIONS

Collectively, the pre-treatment with BCP, likely acting as agonist for CB2 and PPAR-alpha receptors, modulates in a beneficial way the ECS activation and the lipoperoxidation, taken as indicative of oxidative stress. Furthermore, our results support the evidence that BCP may be used as a dietary supplement to control the physiological response to the hypoperfusion/reperfusion-induced oxidative stress.

Pepcan-12 (RVD-hemopressin) is a CB2 receptor positive allosteric modulator constitutively secreted by adrenals and in liver upon tissue damage

Pepcan-12 (RVD-hemopressin; RVDPVNFKLLSH) is the major peptide of a family of endogenous peptide endocannabinoids (pepcans) shown to act as negative allosteric modulators (NAM) of cannabinoid CB1 receptors. Noradrenergic neurons have been identified to be a specific site of pepcan production. However, it remains unknown whether pepcans occur in the periphery and interact with peripheral CB2 cannabinoid receptors. Here, it is shown that pepcan-12 acts as a potent (K_i value ~50 nM) hCB2 receptor positive allosteric modulator (PAM). It significantly potentiated the effects of CB2 receptor agonists, including the endocannabinoid 2-arachidonoyl glycerol (2-AG), for [35S]GTPγS binding and cAMP inhibition (5–10 fold). In mice, the putative precursor pepcan-23 (SALSDLHAHKLRVDPVNFKLLSH) was identified with pepcan-12 in brain, liver and kidney. Pepcan-12 was increased upon endotoxemia and ischemia reperfusion damage where CB2 receptors play a protective role. The adrenals are a major endocrine site of production/secretion of constitutive pepcan-12, as shown by its marked loss after adrenalectomy. However, upon I/R damage pepcan-12 was strongly increased in the liver (from ~100 pmol/g to ~500 pmol/g) independent of adrenals. The wide occurrence of this endogenous hormone-like CB2 receptor PAM, with unforeseen opposite allosteric effects on cannabinoid receptors, suggests its potential role in peripheral pathophysiological processes.

Interactions between the Kynurenine and the Endocannabinoid System with Special Emphasis on Migraine

Both the kynurenine and the endocannabinoid systems are involved in several neurological disorders, such as migraine and there are increasing number of reports demonstrating that there are interactions of two systems. Although their cooperation has not yet been implicated in migraine, there are reports suggesting this possibility. Additionally, the individual role of the endocannabinoid and kynurenine system in migraine is reviewed here first, focusing on endocannabinoids, kynurenine metabolites, in particular kynurenic acid. Finally, the function of NMDA and cannabinoid receptors in the trigeminal system-which has a crucial role in the pathomechanisms of migraine-will also be discussed. The interaction of the endocannabinoid and kynurenine system has been demonstrated to be therapeutically relevant in a number of pathological conditions, such as cannabis addiction, psychosis, schizophrenia and epilepsy. Accordingly, the cross-talk of these two systems may imply potential mechanisms related to migraine, and may offer new approaches to manage the treatment of this neurological disorder.