Etiane M.H. Saccol

Resveratrol improves sperm motility, prevents lipid peroxidation and enhances antioxidant defences in the testes of hyperthyroid rats.

Hyperthyroidism may lead to a loss of sperm motility and an increase in oxidative stress (OS) in testes and may cause male reproductive disorders. Thus, the use of compounds with antioxidant properties may be a strategy for preventing these disorders. The effect of resveratrol (RSV) on sperm motility and on variables of the antioxidant status in the testes of rats with triiodothyronine-induced hyperthyroidism (100μg/kg) was investigated. Hyperthyroid rats presented lower sperm motility, higher levels of lipid hydroperoxides and thiobarbituric reactive substances, lower catalase and glutathione peroxidase activities and higher glutathione-S-transferase activity in their testes than control animals. RSV treatment (1mg/kg and 10mg/kg) was able to prevent these effects in the hyperthyroid rats and had no effect in the control animals. In conclusion, RSV might be a strategy for therapeutic intervention to preserve sperm motility and to prevent OS in testes, preserving testicular function in those with hyperthyroidism.

Effects of parboiled rice diet on oxidative stress parameters in kidney of rats with streptozotocin-induced diabetes.

The effect of parboiled rice (PR) and white rice (WR) diets on oxidative stress (OS) parameters was investigated in the kidneys of rats with streptozotocin-induced diabetes (40 mg kg(-1), iv). The experimental groups (n=8) were control fed with PR (CPR), control fed with WR, diabetic fed with PR, and diabetic fed with WR. After 30 days of treatment, all animals were anesthetized and exsanguinated before removal of kidneys, which were used to determine thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, carbonyl protein, superoxide dismutase, catalase, glutathione peroxidase (GPx), glutathione reductase, glutathione-S-transferase activities, and levels of glutathione (GSH). Total phenolic compounds were determined in WR and PR grains. Our data indicated that diabetes induced increase in TBARS and lipid hydroperoxides levels. Although PR has not prevented the rise in the levels of these measurements, its consumption by our animals resulted in higher GPx activity and GSH content than that of the CPR. Moreover, PR also presented concentration of total phenolic compounds 127% higher than WR grains. Thus, its consumption in this diabetic condition is suggested because this seems to confer greater protection against OS in the renal tissue of diabetic animals.

Myrcia sylvatica essential oil mitigates molecular, biochemical and physiological alterations in Rhamdia quelen under different stress events associated to transport

The effects of pre-transport handling and addition of essential oil of Myrcia sylvatica (EOMS) during transport on stress pathways activation in Rhamdia quelen were investigated. Fish (n=400, 25.2±2.9g) were captured in production ponds and transferred to 100-L tank (density 100g L-1). After 24h, 10 fish were sampled (before transport group). The remaining fish were placed in plastic bags (n=30 or 32 fish per bag, density 150g L-1) containing 5L of water (control), ethanol (315μLL-1, vehicle) or EOMS (25 or 35μLL-1), in triplicate, transported for 6h and sampled (n=10 animals per group). Indicators of stress and metabolism, as well as mRNA expression of brain hormones were evaluated. Previously, full-length cDNAs, encoding specific corticotropin-releasing hormone (crh) and proopiomelanocortins (pomca and pomcb), were cloned from whole brain of R. quelen. Crh expression increased after 24h of capture and handling, whereas cortisol and glucose plasmatics enhanced their values in the control group. Transport with EOMS reduced plasma cortisol and lactate levels, while ethanol and EOMS groups increased Na+/K+-ATPase gill activity compared to control. Gene expression of crh, pomcb, prolactin and somatolactin mRNAs were lower after transport with EOMS compared to control. EOMS was able to mitigate the stress pathways activation caused by transport, maintaining a balance in body homeostasis. Thus, EOMS is recommended as sedative in procedures as transport and the pre-transport handling requires greater attention and use of tranquilizers.

Oxidative stress parameters in juvenile Brazilian flounder Paralichthys orbignyanus (Valenciennes, 1839) (Pleuronectiformes: Paralichthyidae) exposed to cold and heat shocks

The aim of this study was to determine oxidative stress parameters in the liver and gill of Brazilian flounder juveniles (307.0 ± 16.0 g and 30.0 ± 4.0 cm) submitted to different water temperature (17.1, 23.0 and 28.8oC) for 72 h and maintained at salinity 25‰. After the acclimation of 7 days, in 23oC, fish were transferred to 200 L tanks containing seawater (salinity 25‰) at 28.8oC (heat shock), 17.1oC (cold shock) or 23.0oC (control), five replicates (five fish tank-1). The sampled collection occurred in 0 (pre-challenge), 3, 24, 48 and 72 h after temperature shock. Flounder exposed to 17.1oC and 28.8oC showed significantly higher TBARS levels and GST activity in the liver post-exposition (PE) in relation to the control (23oC). CAT activity in liver present a significantly increase at 17.1oC, in first 48 h, and subsequently decrease in 72 h PE in relation to 28.8oC. The gills of flounder showed significantly higher TBARS levels, GST and CAT activity when submitted at 17.1 and 28.8oC in relation to 23.0oC. There were observed changes in lipid peroxidation levels (LPO), CAT and GST activities in the liver and gill of Brazilian flounder in response to reactive oxygen species (ROS) produced by thermal shocks.

N-acetylcysteine protects the rat kidney against aspartame-induced oxidative stress.

Long-term intake of aspartame at the acceptable daily ingestion dose causes oxidative stress in the rat kidney through the dysregulation of glutathione homeostasis. N-acetylcysteine (NAC) provides the cystein required for the production of GSH, being effective in treating disorders associated with oxidative stress. The aim of this research was to investigate the effects of NAC on the aspartame-induced oxidative stress in the rat kidney. The animals received aspartame by gavage for six weeks (40mg/kg). From the 5th week, NAC (1mmol/kg, via intraperitoneal) was injected for two weeks. Then, they were anaesthetized for blood sample and euthanized for the kidney collection. The blood was centrifuged at 1800g for 15min and the serum was separated for creatinine measurement. The tissue was homogenized in 1.15% KCl buffer and centrifuged at 700g for 10min at 4°C. The supernatant fraction obtained was used to the measurements of oxidative stress biomarkers. The creatinine levels were enhanced in the serum of aspartame-treated rats. NAC caused a reduction in the thiobarbituric acid reactive substances, lipid hydroperoxides, carbonyl protein and hydrogen peroxide levels, which were increased in the kidney of aspartame-treated animals. Additionally, NAC caused an elevation in the glutathione peroxidase and glutathione reductase activities, total glutathione, ascorbic acid, and total reactive antioxidant potential levels, which were decreased in the kidney of aspartame-treated rats. In conclusion, NAC may be useful for the protection of the rat kidney against aspartame-induced oxidative stress.

Resveratrol prevents oxidative damage and loss of sperm motility induced by long-term treatment with valproic acid in Wistar rats

Valproic acid (VPA) is a drug widely use for the treatment of epilepsy in both children and adults. Evidence suggests that long-term use of VPA may lead to an impairment in the male reproductive function. Oxidative stress is considered to play a major role in VPA associated toxicity. In the present work, we demonstrated that the natural antioxidant compound resveratrol (RSV) can be use to prevent VPA oxidative damage. Wistar rats treated with VPA (400mgkg(-1)) by gavage for 28days showed decrease in sperm motility accompanied by increase in oxidative damage to lipids and proteins. Additionally, VPA administration leaded to depletion of reduced glutathione and decrease in total antioxidant potential in testes and epididymides of Wistar rats. The co-administration of RSV (10mgkg(-1)) efficiently prevented VPA pro-oxidant effects. In summary, RSV was shown to protect the reproductive system from the damage induced by VPA. Altogether, our data strongly suggests that RSV administration might be a valuable strategy to minimize reproductive impairment in patients requiring long-term VPA treatment.