Examinando por Autor "Vassallo, Dalton Valentim"

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Chronic mercury at low doses impairs white adipose tissue plasticity
(Elsevier, 2019-02-23) Rizzetti, Danize Aparecida; Corrales, Patricia; Piagette, Janaina Trindade; Uranga, Jose Antonio; Vera, Gema; Peçanha, Franck Maciel; Vassallo, Dalton Valentim; Miguel, Marta; Wiggers, Giulia Alessandra
Introduction: The toxic effects of mercury (Hg) are involved in homeostasis of energy systems such as lipid and glucose metabolism, and white adipose tissue dysfunction is considered as a central mechanism leading to metabolic disorders. Objective: The aim of this study was to determine the effects of chronic inorganic Hg exposure at low doses on the lipid and glycemic metabolism. Methods: Male Wistar rats were divided into two groups and treated for 60 days with: saline solution, i.m. (Untreated) and mercury chloride, i.m. - 1st dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/day - (Mercury). Histological analyses, Hg levels measurement and GRP78, CHOP, PPARα, PPARγ, leptin, adiponectin and CD11 mRNA expressions were performed in epididymal white adipose tissue (eWAT). Glucose, triglycerides, total cholesterol and insulin plasma levels were also measured. Results: Hg exposure reduced the absolute and relative eWAT weights, adipocyte size, plasma insulin levels, glucose tolerance, antioxidant defenses and increased plasma glucose and triglyceride levels. In addition, CHOP, GRP78, PPARα, PPARγ, leptin and adiponectin mRNA expressions were increased in Hg-treated animals. No differences in Hg concentration were found in eWAT between the untreated and Hg groups. These results suggest that the reduction in adipocyte size is related to the impaired antioxidant defenses, endoplasmic reticulum (ER) stress, the disrupted PPARs and adipokines mRNA expression induced by the metal in eWAT. These disturbances possibly induced a decrease in circulating insulin levels, an imbalance between lipolysis and lipogenesis mechanisms in eWAT, with an increase in fatty acids mobilization, a reduction in glucose uptake and an activation of pro-apoptotic pathways, leading to hyperglycemia and hyperlipidemia. Conclusions: Hg is a powerful environmental WAT disruptor that influences signaling events and impairs metabolic activity and hormonal balance of adipocytes.
Egg White Hydrolysate as a functional food ingredient to prevent cognitive dysfunction in rats following long-term exposure to aluminum
(Nature, 2019-02-12) Silveira Martinez, Caroline; Alterman, Caroline; Vera, Gema; Márquez, Antonio; Uranga, Jose Antonio; Peçanha, Franck Maciel; Vassallo, Dalton Valentim; Exley, Christopher; Mello-Carpes, Pamela; Miguel, Marta; Wiggers, Giulia
Aluminum (Al), which is omnipresent in human life, is a potent neurotoxin. Here, we have tested the potential for Egg White Hydrolysate (EWH) to protect against changes in cognitive function in rats exposed to both high and low levels of Al. Indeed, EWH has been previously shown to improve the negative effects induced by chronic exposure to heavy metals. Male Wistar rats received orally: Group 1) Low aluminum level (AlCl3 at a dose of 8.3 mg/kg b.w. during 60 days) with or without EWH treatment (1 g/kg/day); Group 2) High aluminum level (AlCl3 at a dose of 100 mg/kg b.w. during 42 days) with or without EWH treatment (1 g/kg/day). After 60 or 42 days of exposure, rats exposed to Al and EWH did not show memory or cognitive dysfunction as was observed in Al-treated animals. Indeed, co-treatment with EWH prevented catalepsy, hippocampal oxidative stress, cholinergic dysfunction and increased number of activated microglia and COX-2-positive cells induced by Al exposure. Altogether, since hippocampal inflammation and oxidative damage were partially prevented by EWH, our results suggest that it could be used as a protective agent against the detrimental effects of long term exposure to Al.
Egg white hydrolysate promotes neuroprotection for neuropathic disorders induced by chronic exposure to low concentrations of mercury
(Elsevier, 2016-09-01) Rizzetti, Danize Aparecida; Fernández, Francisca; Silvia Moreno; Uranga Ocio, Jose Antonio; Franck Maciel Pecanha; Vera, Gema; Vassallo, Dalton Valentim; Miguel, Marta; Wiggers, Giulia Alessandra
This study aims to investigate whether the egg white hydrolysate (EWH) acts on the neuropathic disorders associated with long-term Mercury (Hg) exposure in rats. 8-week-old male Wistar rats were treated for 60 days with: a) Control - saline solution (i.m.); b) Mercury - HgCl2 (1st dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/day, i.m.); c) Hydrolysate - EWH (1 g/kg/day, gavage); d) Mercury and Hydrolysate. Mechanical allodynia was assessed using Von Frey Hairs test; heat hyperalgesia by the plantar test; catalepsy by a modification of the “ring test” and spontaneous locomotor activity by a photocell activity chambers. Analyses were performed at 0, 30 and 60 days of treatment. Brain and plasma MDA, plasma NPSH and TNF-α determination and skin immunohistochemistry were performed at 60 days. Hg induced a reduction in mechanical sensitivity threshold at 30 and 60 days and in thermal sensitivity threshold at 60 days. At the end of treatment catalepsy was developed, but there was not significant alteration in spontaneous locomotor activity. Hg also increased brain and plasma MDA, plasma NPSH and TNF- α levels and the number of Merkel cell–neurite complex in the skin. EWH prevented the development of mechanical allodynia, thermal hyperalgesia and catalepsy induced by Hg and the increase in MDA concentration in brain and plasma and in the number of Merkel cell–neurite complex in the skin. In conclusion, EWH promotes neuroprotection against the toxic effects caused by Hg, demonstrating a beneficial therapeutic potential.