The DOX-induced MAPK activation and cell death were enhanced when DOX was co-administered with CB1agonists AEA or HU210 significantly. and MAPK activation induced by AEA, HU210, and DOX AEA/HU210 had been generally attenuated by Rabbit Polyclonal to RUFY1 possibly CB1antagonists (rimonabant and AM281) or by inhibitors of p38 and JNK MAPKs. Furthermore, HU210 or AEA in principal individual cardiomyocytes triggered improved reactive air species generation. == Bottom line == CB1activation in cardiomyocytes may amplify the reactive air/nitrogen species-MAPK activation-cell loss of life pathway in pathological circumstances when the endocannabinoid artificial or metabolic pathways are dysregulated by extreme irritation and/or oxidative/nitrosative tension, which may donate to the pathophysiology of varied cardiovascular illnesses. Keywords:Heart failure, CB1receptor, Endocannabinoids, Rimonabant, SR141716, AM281 == 1. Introduction == Numerous preclinical and clinical studies have reported increased endocannabinoid levels and implicated cannabinoid-1 (CB1) receptor activation by endocannabinoids in the Catharanthine hemitartrate pathogenesis of hypotension and/or cardiac dysfunction associated with various forms of shock and cardiomyopathies, as well as in the development of obesity, increased cardiometabolic risk, atherosclerosis, and impaired glucose tolerance.15Multiple studies found beneficial effects of CB1antagonists in these pathological conditions, both in animal models as well as in human trials. CB1activation may also lead to undesirable haemodynamic consequences in healthy volunteers depending on the duration of the use (bradycardia/tachycardia, hypotension, arrhythmias),6which can be attenuated by CB1blockade.7,8Furthermore several clinical cases of myocardial damage/cardiomyopathy associated with cannabis use have also been reported9(see also references within). The quinone-containing anthracycline doxorubicin (DOX) is usually a potent anti-tumour compound commonly used to treat several malignancies. The major limitation of this class of drug is usually its dose-dependent cardiotoxicity, resulting in the death of cardiomyocytes which often leads to irreversible myocardial dysfunction.10The pathogenesis of DOX-induced cardiomyopathy/heart failure is complex and may involve multiple mechanisms including increased oxidative/nitrosative stress,11,12mitochondrial dysfunction/damage,12alterations in the excitationcontraction (EC) coupling,13and activation of mitogen-activated protein(MAP)kinases,14just to name a few. We have recently exhibited that DOX increased endocannabinoid levels in cardiomyocytes bothin vivoandin vitro, and that the pharmacological inhibition of CB1attenuated the DOX-induced myocardial dysfunction in a clinically relevant mouse model of acute cardiomyopathy.15However, the role of the cardiovascular CB1cannabinoid receptors and its possible interplay with the oxidative/nitrosative stress and interrelated cell death signalling pathways, eventually culminating into cardiac dysfunction, have not been addressed; likewise the fundamentals of CB1-mediated signalling in human cardiomyocytes, and its possible role in cell death and reactive oxygen species generation are also elusive. Therefore, using human primary cardiomyocytes and CB1knockout mice we aimed to investigate the CB1-mediated signalling in cardiomyocytes and its possible role in oxidative stress, interrelated signalling and cell death pathways associated with clinically relevant acute and chronic cardiomyopathy models induced by DOX. In the chronic cardiomyopathy model, we also investigated the possible involvement of CB1receptors in myocardial fibrosis. == 2. Methods == == 2.1. Animals == Protocols involving the use of animals were approved by the Institutional Animal Care and Use Committees and were performed in line with the National Institutes of Health (NIH) guidelines for the care and use of laboratory animals (NIH Publication No. 85-23, revised 1996). Male CB1+/+or CB1/mice (2530 g), maintained at NIAAA’s breeding facility, were administered with single dose (20 mg/kg) of DOX-HCl (Sigma Chemicals, St Louis, MO) intraperitoneally (i.p.) or with multiple doses (5 mg/kg) at days 1, 7, 14, and 21. After 5 or 35 days, mice were subjected to haemodynamic measurements or hearts were excised and snap frozen in liquid nitrogen for biochemical measurements as described.15,16 == 2.2. Reagents and cell culture == DOX was purchased from Sigma chemicals (MO, USA); p38 myocardial mitogen-activated protein kinase (MAPK), JNK Catharanthine hemitartrate inhibitors (SB203580 Catharanthine hemitartrate and JNK inhibitor II, respectively) was obtained from Calbiochem, EMD (Gibbstown, NJ). Anandamine (AEA), (6aR,10aR)-9-(hydroxymethyl)-6,6dimethyl-3-(2-methyloctan-2-yl)-6a,7,10,10a-tetrahydrobenzo[c]chromen-1-ol (HU210), and 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-moepholinyl-1H-pyrazole-3-carboxamide (AM.