Involvement of mitochondrial-mediated caspase-3 activation and lysosomal labilization in acrylamide-induced liver toxicity

Acrylamide (ACR) is a chemical frequently used in both industrial and synthetic processes and may be produced during food processing. ACR at very high concentrations is postulated to exert its toxicity through the stimulation of an oxidative stress. ACR in excessive doses induces the central nervous system, reproduction, and genetic toxicity. However, ACR effects on the liver, a major organ of drug metabolism, have not been adequately explored. In addition, the role of mitochondria in an ACR-mediated hepatotoxicity is still unclear. The aim of this study was to investigate the cytotoxic mechanisms attributed to ACR using isolated rat hepatocytes. Hepatocytes were isolated by the collagenase perfusion method and incubated with an EC50_2hr concentration of ACR for 3 hr. The EC50_{2 hr} of ACR on isolated rat hepatocytes was determined to be 1 mM. Based on our results, hepatocytes cytotoxicity of ACR (1 mM) was mediated by a reactive oxygen species formation and lipid peroxidation. Incubation of hepatocytes with ACR produced rapid hepatocyte glutathione depletion which is another marker of the cellular oxidative stress. ACR cytotoxicity was also associated with mitochondrial injury as evidenced by the decline of mitochondrial membrane potential and lysosomal membrane leakiness. Our results also showed that ACR induced caspase-3 activation, the final mediator of apoptosis signaling. These findings contribute to a better understanding underlying mechanisms involved in ACR hepatotoxicity originating from the oxidative stress and ending in mitochondrial/lysosomal damage and cell death signaling.     

Effectiveness of UV/SO32− advanced reduction process for degradation and mineralization of trichlorfon pesticide in water: identification of intermediates and toxicity assessment

Environmental Science and Pollution Research - This study aimed to investigate the degradability, mineralization, proposed decomposition pathway, intermediate products, and toxicity of effluent...     

Comparison of cellular and molecular cytotoxic mechanisms of Cochlodinium polykrikoides in isolated trout and rat hepatocytes

Harmful algal blooms produced by the marine ichthyotoxic dinoflagellate Cochlodinium polykrikoides are responsible for mass mortalities of wild and farmed fish globally. This study compared the cytotoxic mechanisms of C. polykrikoides total extract on both trout and rat liver hepatocytes. Trout hepatocytes were more sensitive than rat hepatocytes against C. polykrikoides extract. The effective concentration 50 after 3 hour incubation (EC50_3hr) concentrations found for C. polykrikoides extract in trout and rat hepatocytes (i.e., 50% membrane lysis in 3 hr) were Eq. 1 cell/ml and Eq. 240 cell/ml, respectively. C. polykrikoides extract exposure in both isolated trout and rat hepatocytes resulted in membrane lysis, reactive oxygen species formation, glutathione depletion, collapse of mitochondrial membrane potential, ATP depletion, increase in adenosine diphosphate (ADP)/adenosine triphosphate (ATP) ratio, cytochrome c release into the hepatocyte cytosol, and activation of caspases cascade. Trout hepatocyte toxicity was also associated with lysosomal membrane injury. Mitochondrial permeability transition in both trout and rat hepatocytes produced cytochrome c release from the mitochondrial intramembrane space into the cytosol. Thus, the cytochrome c release triggered activation of caspase-3 and apoptosis. Finally, data demonstrated that C. polykrikoides extract may induce more apoptotic phenotype in rat than trout hepatocytes, which in the latter favored predominantly necrotic mode of cell death.     

Toxicity of 4-methylimidazole on isolated brain mitochondria: using both in vivo and in vitro methods

4-methylimidazole (4MI) is a compound widely used in various industrial and consumer applications. The most important sources of exposure include chemical caramel coloring, ammoniated molasses, dyes and pigments, rube, cleaning and agricultural chemicals. Toxicity attributed to 4MI in foods has recently become a focus of research. Recent studies showed that 4MI induced adverse changes in various target tissues. Brain is known to be a target organ for 4MI-induced toxicity but its cytotoxic mechanisms have not yet been elucidated. In this study, experiments were divided into two parts: (1) using in vivo methodology, doses of 4MI at 100, 200, or 300 mg/kg were administered orally to mice daily for 14 to obtain brain mitochondria; and (2) utilizing in vitro methodology, brain mitochondria were incubated with 4MI at 400, 800, or 1600 μM concentrations. Subsequently, the neurotoxicity of 4MI was assessed using mitochondrial dysfunction tests, including reactive oxygen species (ROS) formation, mitochondrial membrane potential (MMP) collapse, mitochondrial swelling, and cytochrome c release. Our results from both in vivo and in vitro experiments on isolated brain mitochondria showed a significant decrease in complex II activity and also marked elevation in the ROS formation, MMP collapse, mitochondrial swelling, and enhanced release of cytochrome c. Data indicated that 4MI induced neurotoxicity through the impairment of electron transfer chain especially at complex II and elevated ROS formation leading to subsequent oxidative stress events including mitochondrial membrane depolarization, mitochondrial swelling, and release of cytochrome c, which is the starting point of mitochondrial-mediated apoptosis signaling and neurodegeneration.