Hemoglobin degradation, lipid peroxidation, and inhibition of Na+/K(+)-ATPase in rat erythrocytes exposed to acrylonitrile

Acrylonitrile-induced reversible inhibition of uridine uptake by isolated rat intestinal epithelial cells

Isolated rat intestinal epithelial cells (IEC) were used to investigate the mechanism(s) of acrylonitrile (VCN)-induced gastro-intestinal damage. The isolated cells were 93% structurally intact for 60 min, as indicated by trypan blue exclusion. Uridine uptake by isolated IEC was linear from 6-20 min, after which a steady state was reached for up to 40 min. Exposure of isolated IEC to various concentrations of VCN reduced the ability of the cells to take up uridine in a concentration-dependent manner. A concentration of 82 mum VCN inhibited the [(3)H]uridine uptake of the cells by 50% (IU(50)). A time-course study indicated that the maximal inhibition of uridine uptake occurred at 15 min after exposure to VCN. The VCN-induced inhibition of uridine uptake was found to be reversible. IEC exposed to two sublethal doses of VCN (41 and 82 mum) for 15 min regained normal uridine uptake activity within 50 min after removal of VCN. The present study provides a sensitive approach for the detection and evaluation of cytotoxic risk of sublethal doses of the gastro-intestinal toxin VCN using IEC as target cells. The observed in vitro cytotoxicity of sublethal doses of VCN will be used to investigate further the mechanism of VCN-induced gastro-intestinal damage.

Effects of acrylonitrile on antioxidant status of different brain regions in rats

While the adverse effects of acrylonitrile (AN) on the central nervous system (CNS) are known to be mediated, at least in part, by the generation of free radicals and oxidative stress, there is a paucity of data on region-specific alterations in biomarkers of oxidative stress in the brain of AN-exposed animals. The present study was designed to examine the effects of AN on biomarkers of oxidative stress in several brain regions of adult Sprague-Dawley rats. Daily intraperitoneal (i.p.) treatment of animals to 0 (control, normal saline solution), 25, 50 or 75mgAN/kg body weight for 7 days resulted in statistically significant (p<0.05) increases in the levels of lipid peroxidation product, malondialdehyde (MDA), in the cortex and cerebellum; a statistically significant (p<0.05) decrease MDA levels were noted in the striatum. Contents of reduced glutathione (GSH) were significantly (p<0.05) decreased in cortex, cerebellum and hippocampus. The activities of the antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were differentially affected by AN and these effects were brain region-specific and AN dose-dependent. Taken together, these data suggest brain region-specific effects of AN on lipid peroxidation, activities of antioxidant enzymes and non-enzymatic antioxidant levels. These effects may provide biochemical evidence for AN-induced neurobehavioral damage and disturbance of monoamine neurotransmitters.

Effects of an oxidative stress on human hemoglobin: a multiwavelength visible spectrometry study

This study was carried out to investigate hemoglobin behavior and the role of cell membrane during oxidative stress of human red blood cells induced by a water-soluble radical initiator, 2,2'-azobis(amidino-propane) hydrochloride (AAPH) and compare the observed data to the one obtained with purified human haemoglobin solution. The different forms of hemoglobin were identified and quantified by multiwavelength visible spectrometry using multiple linear regression analysis. Hemolysis was quantified by the Drabkin method. Oxidative stress on purified hemoglobin solutions induced an early formation of Hb(+). In intact erythrocytes, no modified form of haemoglobin was found. Only the hemoglobin released by hemolysis in the extracellular medium was notified in the same way as purified haemoglobin. Thus, the cell membrane appears to protect intraerythrocytic hemoglobin toward an extracellular oxidative stress. Oxidative stress-induced by hemolysis does not seem to be due to changes in intraerythrocytic hemoglobin forms.

Assessment of the acute acrylonitrile-induced neurotoxicity in rats

Acrylonitrile (VCN) is an aliphatic nitrile which is used extensively in manufacturing of synthetic fibers, plastics, and rubber. Although the neurotoxicity of VCN is recognized, no thorough characterization of this effect has been reported. Current studies were designed to quantitatively characterize the acute phase of VCN-induced cholinomimetic neurotoxicity, and to determine the effects of dose, route of administration, and atropine on such toxicity. Administration of a single gavage or subcutaneous doses of 20, 40, or 80 mg VCN/kg to male Sprague-Dawley rats causes two distinctive phases of acute neurotoxic effects. Signs observed in the early phase had a rapid onset, and were cholinomimetic in nature. They included salivation, lacrimation, chromodacryorrhea, polyuria, miosis, vasodilatation in face, ears and extremities, increased gastric secretion, and diarrhea. A late phase developed hours after VCN dosing, and the toxic signs included depression, convulsions, and respiratory failure followed by death at high doses. These results revealed that the cholinomimetic toxicity induced by VCN was dose related regardless of the route of administration. In another study, rats were pretreated with atropine (1 mg/kg, IP) prior to VCN (40 mg/kg) in order to investigate the role of the cholinergic system. Atropine protected rats against VCN-induced cholinomimetic neurotoxicity, suggesting possible involvement of the cholinergic system. Finally, this work provides essential basic information for studying the biochemical, pharmacological, and neurological basis of VCN-induced neurotoxicity in the rat.