Effects of Cold Temperature on the Activities of Glutathione Peroxidase, Lactate Dehydrogenase and Free Radicals Production in Uromastyx aegyptius

Potential diagnostic biomarkers for lead-induced hepatotoxicity and the role of synthetic chelators and bioactive compounds

Lead (Pb2+) poisoning is a public health concern of global dimensions. Although several public health guidelines and workplace safety policies are existing and enforced, lead toxicity cases are drastically increasing. Lead exposure leads to numerous harmful consequences and causes adverse effects on different body organs and systems, mainly via the generation of reactive oxygen species, leading to augmented oxidative stress, competing with metal ions, and binding with the sulfhydryl groups. In several instances, lead poisoning cases remain undiagnosed and untreated or receive only symptomatic treatment. Estimation of blood lead levels reflects only a recent exposure, however, which does not reveal the total body burden. This review summarizes the effects of lead with special reference to hepatotoxicity and some of the potential diagnostic biomarkers. Furthermore, it also focuses on synthetic chelators used in the treatment of lead poisoning and the advantage of using bioactive compounds with an emphasis on the ameliorative effect of garlic.

Antioxidant response to acute cold exposure and following recovery in juvenile Chinese soft-shelled turtles, Pelodiscus sinensis

The antioxidant defense protects turtles from oxidative stress caused by adverse environment conditions, such as acute thermal fluctuations. However, how these defenses work remains unclear. The present study examined changes in key enzymes of the enzymatic antioxidant system and the glutathione (GSH) system at both the mRNA and enzyme activity levels during acute cold exposure and following recovery in juvenile Chinese soft-shelled turtles, Pelodiscus sinensis. Transcript levels of the upstream regulator NF-E2 related factor 2 (Nrf2) were also measured. Turtles were acclimated at 28oC (3 wks), then given acute cold exposure (8oC, 12 h) and finally placed in recovery (28oC, 24 h). The mRNA levels of cerebral and hepatic Nrf2 and of downstream antioxidant enzyme genes did not change, whereas nephric Nrf2, Manganese superoxide dismutase (MnSOD) and glutathione peroxidase 4 (GPx4) mRNAs decreased in cold exposure. During recovery, Nrf2 mRNA remained stable in all three tissues, hepatic Cu/ZnSOD, MnSOD and catalase (CAT) mRNA levels increased, and nephric MnSOD and GPx4 mRNAs did not change from the values during cold exposure. In the GSH system, mRNA levels of most enzymes remained constant during cold exposure and recovery. Unmatched with changes in mRNA level, high and stable constitutive antioxidant enzyme activities were maintained throughout whereas GPx activity significantly reduced in kidney during cold exposure and in liver and kidney during recovery. Our results suggest that the antioxidant defense regulation in response to acute cold exposure in P. sinensis may not be achieved at the transcriptional level, but may rely mainly on high constitutive antioxidant enzyme activities.

Effects of acute cold exposure on oxidative balance and total antioxidant capacity in juvenile Chinese soft-shelled turtle, Pelodiscus sinensis

Acute cold exposure may disturb the physiological homeostasis of the body in ectotherms. To date, there has been no information on the effects of cold exposure on homeostasis of reactive oxygen species (ROS) or antioxidant defense response in the Chinese soft-shelled turtle, Pelodiscus sinensis. In this study, P. sinensis juveniles were acclimated at 28 °C, transferred to 8 °C as cold exposure for 12 h, then moved back to 28 °C rewarming for 24 h. We measured the ROS level and total antioxidant capacity (TAC) in the brain, liver, kidney and spleen at 2 and 12 h cold exposure, and at the end of the rewarming period. Malonaldehyde (MDA) and carbonyl protein were used as markers of oxidative damage. Turtles being maintained simultaneously at 28 °C were used as the control group. Cold exposure did not disturb the ROS balance in all 4 tissues, while rewarming raised the ROS level in the brain and kidney of P. sinensis. Cold exposure and rewarming decreased the TAC in the brain, liver and spleen but did not change the TAC in the kidney. MDA and carbonyl protein levels did not increase during the treatment, indicating no oxidative damage in all 4 tissues of P. sinensis. Our results indicated that extreme cold exposure did not impact the inner oxidative balance of P. sinensis, but more ROS was produced during rewarming. P. sinensis showed good tolerance to the harsh temperature change through effective protection of its antioxidant defense system to oxidative damage. This study provides basic data on the stress biology of P. sinensis.

Increased Antioxidant Potential and Decreased Free Radical Production in Response to Mild Injection of Crude Venom, Cerastes cerastes gasperetti

ABSTRACT The purpose of this study was to examine the effects of Cerastes cerastes gasperetti crude venom (CCV) on free radical (FR) production and biological antioxidant potential (BAP). Thirty male rats, matched with age and weight, were divided randomly into three groups: control (C), negative control (NC), and experimental (E). Animals in the control group served as control for needlestick and venom injection. Animals in the negative control group, which served as control for venom-induced effects, were injected intraperitoneally (IP) with saline for 8 days, whereas animals of the experimental group were injected IP with crude CCV, at a dose of 1/4 LD(50), for the same period. All animals of the three groups remained under normal laboratory and dietary conditions. Blood samples were collected by heart puncture technique and were analyzed immediately for FRs and BAP. ANOVA analysis indicated a significant difference (p < 0.05) among group means. Tukey-Kramer multiple comparisons showed that FRs increased significantly (p < 0.05) in the NC group, implying that needlestick during injection of saline for 8 days caused internal organ injury sufficient enough to induce reactive oxygen species (ROS) generation. Surprisingly, there were no significant (p > 0.05) changes in FRs in the E group as compared with the C group, which indicates that CCV counteracted the effects induced by ROS. BAP increased significantly (p < 0.05) in the E group as compared with the NC group, reflecting the activation of some antioxidant enzymes. Linear regression of FRs on BAP was significant (p < 0.05) in both the C and E groups. Based on the results of this study, it can be concluded that the CCV contains biochemical factors that activate antioxidant enzymes, as evident by elevation in the BAP that depresses ROS formation.

Effect of hyperoxia on the ultrastructural pathology of alveolar epithelium in relation to glutathione peroxidase, lactate dehydrogenase activities, and free radical production in rats, Rattus norvigicus

Hyperoxia (HP) exposure inducts reactive oxygen species (ROS) in the lungs that may result in lung injury, including alveolar epithelial and endothelial cells. Lactate dehydrogenase (LDH) activity relates to glycolysis, whereas glutathione peroxidase (Gpx) activity relies on the pentose phosphate pathway (PPP). The purpose of this study was to examine early ROS-induced alveolar pathological changes in relation to the activity of glutathione peroxidase (GPx) and lactate dehydrogenase (LDH) activity. Twenty adult male rats, matched with age and body weight, were randomly assigned to two groups, control and experimental. The experimental group was exposed to hyperoxia for 24 h. Ultrastructure examination showed degenerated pneumocyte type I, containing swollen mitochondria associated with dilated rough endoplasmic reticulum, and was projecting into the alveolar lumen. Pneumocyte II showed mitochondria swelling and hyperplasia and was desquamated in structure, depleted in surfactant, and falling into the alveolar lumen. Pulmonary capillary showed distention without observed damage in the endothelial layer. Following HP, the average (+/-) free radical (FR) production increased significantly (p<.05) from the baseline control of 181.20+/-30.06 to 260.30+/-68.10 (Carr U) and average (+/-SD) GPx activity also increased significantly (p<.05) from the baseline control of 8178.30+/-2402.62 to 19,589.50+/-2392.44 (U/L), whereas average (+/-SD) LDH activity decreased significantly (p<.05) from baseline control of 194.11+/-75.52 to 42.68+/-11.41 (U/L), which demonstrated slowing down of glycolysis. Based on these results it can be concluded that exposure to high inspired oxygen inducted the buildup of mitochondria-driven ROS that was related to early injury in the alveolar epithelium without obvious endothelium injury.