Turnover of hepatic glutathione after acute lindane intoxication

Oxidative stress in liver and red blood cells in acute lindane toxicity in rats

The aim of our study was to determine the role and dynamics of oxidative and nitrosative stress, as well as superoxide dismutase (SOD) and catalase activity in the hepatocytes and erythrocytes in early phase of acute lindane intoxication. Male Wistar rats were divided into groups: control, dimethylsulfoxide and lindane-treated groups (L, 8 mg/kg, intraperitoneally). Animals were sacrificed 0.5 and 4 hours after treatment (L(0.5) and L(4) groups, respectively). Oxidative and nitrosative stress parameters and antioxidant enzymes were determined spectrophotometrically. Liver and plasma thiobarbituric acid reactive substances (TBARS) concentration were significantly increased 0.5 after lindane administration (p < .01), with subsequent additional rise within 4 hours (p < .01), while plasma nitrite + nitrate level was significantly higher only 4 hours after lindane treatment. Total liver SOD activity was significantly increased in L(4) group in comparison with control group (p < .01). In conclusion, oxidative and nitrosative stress play an important role in early phase of acute lindane hepatotoxicity. Antioxidant capacity of hepatocytes is partly increased, due to an adaptive increase in SOD activity.

Acute hexachlorocyclohexane-induced oxidative stress in rat cerebral hemisphere

Hexachlorocyclohexane (HCH) is reported to induce oxidative stress in liver and testis of rat. With an objective to examine its effect on brain tissue acute toxicity of HCH (10 and 20 mg/kg body wt, i.p.) on the antioxidant defense system of cerebral hemisphere of rat was evaluated. Lipid peroxidation (LPX) was elevated after 24 h in the crude homogenate and sub-cellular fractions (nuclear and mitochondrial) except the microsomal fraction in which LPX was induced after 6 h and remained elevated till 24 h. The pesticide elicited decrease in the activities of cytosolic total, CN(-)-sensitive (not at 24 h) and CN-resistant superoxide dismutases; total, Se-dependent and Se-independent glutathione peroxidases; and catalase throughout the measurement period. In contrast, glutathione reductase activity was elevated till 24 h after a fall at 6 h of pesticide exposure. Cerebral contents of glutathione and ascorbic acid were decreased in response to HCH. The results suggest the possible involvement of reactive oxygen species in the mechanism of HCH-induced neurotoxicity in rat.

Hepatic glutathione biosynthetic capacity in hyperthyroid rats

The influence of hyperthyroidism on the capacity of the liver to synthesize glutathione (GSH) was evaluated as a possible mechanism of depletion of the tripeptide. For this purpose, the effect of daily doses of 0.1 mg 3, 3',5-tri-iodothyronine (T3)/kg for 3 consecutive days on hepatic GSH biosynthetic capacity was assessed by a combined assay measuring gamma-glutamylcysteinyl synthase and GSH synthase simultaneously. T3 treatment induced a significant 56% depletion of liver GSH in parallel with an increase in the rate of GSH synthesis, the latter effect being completely abolished by L-buthionine sulfoximine. According to these data, the fractional rate of hepatic GSH turnover exhibited a 3.2-fold enhancement in hyperthyroid rats compared to control animals. It is concluded that the enhanced GSH utilization in the liver of hyperthyroid rats previously observed [Fernández et al., Endocrinology 129, 85-91, 1991], is accompanied by an increment in GSH synthesis that is insufficient to sustain the basal levels of the tripeptide observed in euthyroid animals, thus establishing a low steady-state content of GSH in the tissue.