Accordingly and in animal models a high fat diet

Accordingly and in animal models, a high-fat diet rich in CO (CO-HFD) impeded ventricular function and induced cardiac cell death and remodeling, at least, by down-regulating cell antioxidant defense systems and induction of oxidative stress [28], [29], [30], [31]. Interestingly, long chain fatty acids including CO and its metabolite, arachidonic acid, induced rapid increase in intracellular Ca2+ levels in cultured cardiomyocytes [32], [33] and pancreatic β cells [34]. Also, LA-induced Fas/FasL-mediated cell death in human gastric adenocarcinoma cells [35]. However, the impact of CO-HFD on Fas/FasL-mediated cell death in the heart of humans or animals is not documented yet under both healthy and diseased conditions. In addition, if CO-HFD contributes to potentiate hyperglycemia-induced Fas/FasL-induced cell death in the heart of animals or cultured cardiomyocytes was not studied yet, which is an interesting area of study given the high rate consumption of CO by healthy and DM patients. Based on the above-mentioned evidence and given that T1DM enhanced cardiac intracellular Ca2+ levels and activated NFAT4 in the extracardiac tissues including cerebral arteries and TCS PIM-1 1 [21], [25], [26], this study was designed with two aims. First to investigate if Fas/FasL-mediated cardiomyocytes death observed in hearts of T1DM-induced rats involves activation of calcineurin/NFAT/FasL axis. Second, to investigate the effect of chronic administration of CO-HFD on Fas/FAsL-induced death in the heart of healthy or T1DM-induced rats from the perspective of its effect on calcineurin/NFAT axis. Accordingly, our data are the first to show that calcineurin/NFAT/FasL axis was activated in the hearts of T1DM-induced rats or in cultured cells under hyperglycemic conditions and that concomitant chronic administration of CO-HFD rendered the hearts and cardiomyocytes more susceptible to hyperglycemia mediated Fas/FasL-induced apoptosis devoted by enhancement mRNA and protein levels of Fas.
Materials and methods
Results
Discussion The current evidence of this study shows that changes in plasma or extracellular glucose levels induces a rapid increase in the intracellular levels of ROS and Ca2+ in the cardiomyocytes and are readily detected, at least, by NFAT4 through direct activation of calcineurin. These findings illustrate that NFAT4 is a specific metabolic sensor of potential relevance in LV dysfunction and apoptosis in T1DM-induced animals and a major inducer of Fas/FasL-mediated apoptosis. In addition, it shows that chronic administration of CO-HFD to T1DM-induced rats or exposing the HG media-cultured cardiomyocytes to LA potentiates Fas/FasL-induced apoptosis through overexpression of Fas in a mechanism that devoted by an increase in levels of ROS. The first interesting observation in this study is the development of T2DM phenotype in rats chronically fed CO-HFD. This was evident by the significant increase in their final body weights, fasting hyperinsulinemia, stable fasting glucose levels and higher value of calculated HOMA-IRI, indicating a state of peripheral insulin resistance. Indeed, T2DM patient does not develop hyperglycemia due to the compensatory effect of β-cells [40]. In support, [41] have recently shown that CO-HFD reduces spontaneous locomotor activity and induces insulin resistance in mice. Also, n-6 PUFAs increased the secretion of insulin and/or reduces peripheral insulin catabolism and action in rodents [42], [43], [44]. Furthermore, arachidonic acid, a lipid metabolite of CO metabolism, up-regulates the expression of multiple adipogenic genes involved in pre-adipocyte differentiation through activation of cyclooxygenase/protein kinase A/PPARγ signaling pathway [45]. In addition to these changes, CO-HFD-fed rats showed a significant decrease in their heart weights which could be attributed to the active apoptosis induced by the CO-HFD as confirmed further in this study and discussed below.