Evandro Gomes da Silva

All-trans retinoic acid induces free radical generation and modulate antioxidant enzyme activities in rat sertoli cells.

In this work we investigated the effects of retinoic acid (RA) in Sertoli cells. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with RA for 24 h. RA at high doses (1–10 μM) increased TBARS levels and induced a decrease in cell viability. At low doses (0.1–100 nM) RA did not increase TBARS level. RA also did not increase cell death at these doses. In order to investigate changes in antioxidant defenses we measured the CAT, SOD and GPx activities in Sertoli cells treated with RA. Compared to control, RA increased around 200% SOD activity in all doses tested (0.1–100 nM); GPx activity was increased 407.49, 208.98 and 243.88% (0.1, 1 and 10 nM, respectively); CAT activity was increased 127% with RA 1 nM. To clarify if RA induces ROS production per se, we performed experiments in vitro using 2-deoxyribose as specific substrate of oxidative degradation by •OH radical as well as TRAP assay. RA at 10 μM increased 2-deoxyribose degradation, suggesting that some of the RA-induced effects are mediated via •OH formation. Furthermore, the total reactive antioxidant potential (TRAP) of the RA was determined. At low concentrations RA has induced no redox activity. Conversely, higher concentration of RA (1–10 μM) increased chemiluminescence. The chemiluminescence produced was directly proportional to radical generation. We provide, for the first time, evidence for a free radical generation by RA. Our results demonstrated that RA plays an important role in Sertoli cells and these effects appear to be mediated by ROS.

Pancreas β-cells morphology, liver antioxidant enzymes and liver oxidative parameters in alloxan-resistant and alloxan-susceptible Wistar rats : a viable model system for the study of concepts into reactive oxygen species

The aim of this study was to investigate biochemical and antioxidant parameters in alloxan‐resistant (ALR) and alloxan‐susceptible (ALS) rats. Diabetes was induced in 60‐day‐old male Wistar rats by a single intraperitonial injection of alloxan (AL, 150 mg/kg). Ten days after induction, a group of rats showed a significant decrease in glycemia. This group was named alloxan‐resistant group. Susceptible rats showed a remarkable increase in the plasma lipid content, blood glucose and HbA1. Glycogen content in the liver decreased significantly in the ALS group (2.08 ± 0.41 mg%) compared with ALR group (4.22 ± 0.18). Aspartate aminotransferase and alanine aminotransferase activities were quantified in the plasma. Interestingly, ALR rats showed a decrease in both activities (42.1 ± 6.11 and 21.7 ± 5.54 U/mL) when compared with ALS rats (59.1 ± 6.55 and 58.1 ± 7.28 U/mL). The TBARS index was significantly increased in the ALS liver (0.38 ± 0.08 nm/mg protein) when compared with the ALR liver (0.18 ± 0.04). Superoxide dismutase and catalase activities in the ALR (230 ± 13 and 131 ± 15 U/mg protein) liver showed a marked increase when compared with the ALS liver (148 ± 13 and 68 ± 5 U/mg protein). The immunohistochemical and hematoxilin–eosin analysis also revealed that pancreatic islets of ALR rats display a different morphology amongst the groups. These results suggest an increased regenerative or recovery process in the ALR rat pancreatic islets and an increased hepatic antioxidant defenses in these group of alloxan‐resistant rats.

Oxidative damage in brains of mice treated with apomorphine and its oxidized derivative

Increasing evidence suggests that some of the neurobiological and neurotoxic actions of apomorphine and other dopamine receptor agonists might be mediated by their oxidation derivatives. The aim of the present study was to evaluate the effects of apomorphine and its oxidation derivative, 8-oxo-apomorphine-semiquinone (8-OASQ), on oxidative stress parameters and antioxidant enzyme activity. Adult male CF-1 mice were treated with a systemic injection of apomorphine (0.4, 4.0 or 40.0 mg/kg) or 8-OASQ (0.4, 4.0 or 40.0 mg/kg). Animals were sacrificed by decapitation 24 h after treatment, and the forebrains were collected for analysis of thiobarbituric acid reactive species, protein carbonyls, the total radical-trapping antioxidant parameter, catalase and superoxide dismutase. These treatments did not induce lipid peroxidation at any dose tested. In contrast, apomorphine induced an increase in protein carbonylation and a decrease in total radical-trapping antioxidant parameter at all doses tested. 8-OASQ induced an increase in protein carbonylation and a decrease in total radical-trapping antioxidant parameter only at the higher dose tested. All apomorphine doses tested induced an increase in catalase, but not superoxide dismutase activities. In contrast, 8-OASQ induced a dose-dependent increase in CAT activity. The results suggest that apomorphine and its oxidation product, 8-OASQ, induce differential effects on CNS oxidative parameters.