Proteomic analysis of kidney in rats chronically exposed to fluoride

Abstract

Two-dimensional gel electrophoresis (2-DE) was used to better understand alterations in renal metabolism induced by fluoride (F). Three groups of weanling male Wistar rats were treated with drinking water containing 0 (control), 5, or 50 ppm F for 60 days (n=6/group). Kidneys were collected for proteomic and histological (HE) analysis. After protein isolation, renal proteome profiles were examined using 2-DE and Colloidal Coomassie Blue staining. Protein spots with a 2-fold significant difference as detected by quantitative intensity analysis (Image Master Platinum software) and t-test (p<0.05) were excised and analyzed by MALDI-TOF MS (matrix assisted laser desorption ionization-time-of-flight mass spectrometry). The histological analysis revealed no damage in kidneys induced by F, except for a vascular congestion in the 50 ppm F group. Between control vs 50 ppm F, and control vs 5 ppm F groups, 12 and 6 differentially expressed proteins were detected, respectively. Six proteins, mainly related with metabolism, detoxification and housekeeping, were successfully identified. At the high F group, pyruvate carboxylase, a protein involved in the formation of oxaloacetate was found to be downregulated, while enoyl coenzyme A hydratase, involved in fatty acids oxidation, was found to be upregulated. Thus, proteomic analysis can provide new insights into the alterations in renal metabolism after F exposure, even in low doses.

Alkaline phosphatase activity in plasma and liver of rats submitted to chronic exposure to fluoride

“…Whitford (1996) has reported that the fraction of ionic plasma fluoride increases with the intake and, in addition, when the entry of fluoride in the plasma exceeds the degree of removal, plasma concentrations also increase. In this work, the group treated with 5 ppm of fluoride in the water did not present fluoride levels significantly different from the control group, in agreement with other studies (Kobayashi et al, 2009). This could be explained by the incorporation of part of fluoride into mineralized tissues, while higher doses of fluoride could saturate the effect of its uptake into mineralized tissues (Ekstrand et al, 1977).…”

“…The increased fluoride concentrations in the kidneys of the animals treated with 15 and 50 ppm were expected, since kidneys were responsible for the excretion of fluoride (Whitford, 1996). Fluoride at 50 ppm was also capable to reduce the weight of the kidneys when compared to the control group, which was consistent to the findings of other studies demonstrating a nephrotoxic effect of fluoride at high doses (Kobayashi et al, 2009;Strunecka et al, 2007), with an altered proteomic profile, hydropic degeneration in epithelial cells and vascular congestion (Kobayashi et al, 2009;Oncu et al, 2004). The hydropic degeneration can cause shrinkage of glomeruli (Oncu et al, 2004), thus leading to a decrease in the weight of the organ.…”

“…The lower weight of the liver in the animals treated with 50 ppm fluoride supported the changes in the liver function induced by high levels of chronic fluoride intake. But on the other hand, Kobayashi et al (2009) described no differences on the total body weight of the animals after 60 days of fluoride treatment (weight: 265-275g). These results (the present results and Kobayashi' results) could be an indicative that some differences caused in the tissues by fluoride had targets more specifics like enzymes, and other microscopic alterations.…”

“…Additionally, fluoride might have systemic toxic effects in other tissues when ingested in levels higher than optimal (Buzalaf et al, 2004;Buzalaf et al, 2005;Leite et al, 2008;Kobayashi et al, 2009). Plasma is an important indicator of fluoride levels in the body in both acute (Buzalaf et al, 2004;Pessan et al, 2005) and chronic (Carvalho et al, 2006) exposures.…”

Ameliorative Effects of Quercetin on Sodium Fluoride-Induced Oxidative Stress in Rat’s Kidney

“…Hand in hand with the typical kidney pathology, fluoride-intoxicated rats showed an increased rate of reactive oxygen species (ROS) generation and lipid peroxidation. 5 Since antioxidants offer therapeutic values in reversing and/or preventing fluoride-mediated cell damage, several laboratories worldwide, including ours, are currently engaged in the search of potential remedies from synthetic and natural sources.…”