Comparative study on the influence of fluoride on lipid peroxidation and antioxidants levels in the different brain regions of well-fed and protein undernourished rats

Carnosine supplementation and retinal oxidative parameters in a high-calorie diet rat model

BACKGROUND

To assess oxidative effects induced by a high-calorie diet on the retina of Wistar rats and test the antioxidative effects of carnosine supplementation.

METHODS

Wistar rats were randomly divided into the following groups: standard diet (SD), high-calorie diet (HcD), standard diet + carnosine (SD + Car), and high-calorie diet + carnosine (HcD + Car). The body weight, adiposity index, plasma glucose, total lipids, high-density lipoprotein (HDL), low-density lipoprotein (LDL), uric acid, creatinine, and triglycerides of the animals were evaluated. The retinas were analyzed for markers of oxidative stress. Hydrogen peroxide production was assessed by 2',7'-dichlorodihydrofluorescein diacetate (DCF) oxidation. The total glutathione (tGSH), total antioxidant capacity (TAC), protein carbonyl, and sulfhydryl groups of the antioxidant system were analyzed.

RESULTS

TAC levels increased in the retinas of the SD + Car group compared to the SD group (p < 0.05) and in the HcD + Car group compared to the HcD group (p < 0.05). The levels of GSH and the GSSH:GSSG ratio were increased in the HcD + Car group compared to the SD + Car group (p < 0.05). An increase in the retinal carbonyl content was observed in the HcD group compared to the SD group (p < 0.05) and in the HcD + Car group compared to the SD + Car group (p < 0.05). A high-calorie diet (HcD) was also associated with a decrease in retinal sulfhydryl-type levels compared to the SD group (p < 0.05).

CONCLUSION

The results suggest that feeding a high-calorie diet to rats can promote an increase in carbonyl content and a reduction in sulfhydryl groups in their retinas. The administration of carnosine was not effective in attenuating these oxidative markers.

TRIAL REGISTRATION

Animal Ethics Committee of Botucatu Medical School - Certificate number 1292/2019.

Protective role of maize purple plant pigment against oxidative stress in fluorosis rat brain

In fluorosis-endemic areas, exposure to high levels of fluoride causes neurotoxicity such as lowered intelligence and cognitive impairment. Oxidative damage is critical to pathophysiologic processes of fluoride intoxication, and neurotoxicity of fluoride may be associated with oxidative stress. In previous studies, maize purple plant pigment (MPPP), which was rich in anthocyanins, showed a strong scavenging activity in vitro and in vivo. The present study aimed to determine whether treatment with MPPP can alleviate fluoride-induced oxidative damage in rat brain. After 3 months of experiment, brain tissues were assayed for oxidative stress variables, histological and Western blotting examinations. Our results showed that MPPP reduced the elevated malondialdehyde levels, increased superoxide dismutase activity, and further attenuated histopathological alterations and mitigated neuronal apoptosis. Importantly, MPPP also reversed changes in Bax and Bcl-2. Therefore, it was speculated that MPPP protects brain tissue from fluoride toxicity through its antioxidant capacity.

Alterations in the memory of rat offspring exposed to low levels of fluoride during gestation and lactation: Involvement of the α7 nicotinic receptor and oxidative stress

Daily exposure to fluoride (F) depends mainly on the intake of this element with drinking water. When administered during gestation and lactation, F has been associated with cognitive deficits in the offspring. However, the mechanisms underlying the neurotoxicity of F remain obscure. In the current study, we investigated the effects of oral exposure to low levels of F during the gestational and lactation periods, on the memory of adult female rat offspring. We also considered a possible underlying neurotoxic mechanism. Our results showed that this exposure reduced step-down latency in the inhibitory avoidance task, and decreased both mRNA expression of the α7 nicotinic receptor (nAChR) and catalase activity in hippocampus. Our data indicates that low F concentrations administrated during gestation and lactation decrease the memory of 90-day-old female offspring. This suggests that the mechanism might be connected with an α7 nAChR deficit in the hippocampus, induced by oxidative stress.

Effect of acetylcholinesterase inhibitors donepezil and rivastigmine on the activity and expression of cyclooxygenases in a model of the inflammatory action of fluoride on macrophages obtained from THP-1 monocytes

Inflammation is an important factor in the development of many diseases of the central nervous system, including Alzheimer's disease and other types of dementia. ‪Given that acetylcholinesterase inhibitors are also currently believed to have anti-inflammatory properties, the purpose of this study was to investigate the effect of acetylcholinesterase inhibitors (rivastigmine, donepezil) on cyclooxygenase activity and expression using the proinflammatory action of fluoride (F^-) on cultured macrophages obtained from THP-1 monocytes. COX-1 and COX-2 activity was determined through measurement of the products of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) in cell culture supernatants. Expression of COX-1 and COX-2 proteins was examined immunocytochemically, and mRNA expression was determined by qRT PCR. ‪‪ Our study confirmed the inhibitory effects of donepezil and rivastigmine on the production of PGE2, TXB2, COX-1 and COX-2 mRNA and protein expression in macrophages. We also demonstrated that the pro-inflammatory effect of fluoride may be reduced by the use of both drugs. The additive effect of these drugs cannot be ruled out, and effects other than those observed in the use of one drug should also be taken into account.

Effect of dietary protein or calcium supplement on the expression of collagen I and dentine phosphoprotein of rats with dental fluorosis

This study aims to assess the roles of dietary protein (Pr) and calcium (Ca) levels associated with excessive fluoride (F) intake and the impact of Pr, Ca, and F on expression of collagen I (COL I) and dentine phosphoprotein (DPP) in rat incisors. Seventy-two rats were randomly allotted to six groups (NC, NC + F, LPrLCa, LPrLCa + F, HPrLCa + F and LPrHCa + F). F, Pr, and Ca were orally administrated to rats for 120 days. The genes and proteins expression levels were quantified. We found that levels of COL1A1 and DSPP gene were respectively decreased by 41.9% and 43.1% in the NC + F group compared with NC group, were respectively decreased by 47.9% and 40.8% in the LPrLCa + F group compared with LPrLCa group, were respectively increased by 71.8% and 39.5% in the HPrLCa + F group and increased by 26.5% and 21.1% in the LPrHCa + F group compared with LPrLCa + F group. Meanwhile, the proteins' expression display with the genes' expression changes were consistent. This study demonstrated that the gene and protein expressions of COL I and DPP were reduced by F both in normal nutrition and malnutrition, and it was reversed by Pr and Ca supplementation, with the effect of Pr being greater than that of Ca.

Proteomic analysis of hippocampus in offspring male mice exposed to fluoride and lead

Fluoride and lead are two common pollutants in the environment. Previous investigations have found that high fluoride exposure can increase the lead burden. In this experiment, in order to study on the molecular mechanisms of central neural system injury induced by the above two elements, differently expressed protein spots in hippocampus of male mice treated with 150 mg sodium fluoride/L and/or 300 mg lead acetate/L in their drinking water were detected by two-dimensional electrophoresis (2-DE) and mass spectrometry (MS). The behavior tests showed that 56 days of fluoride and lead administration significantly reduced the vertical activity and lowered the memory ability of mice. In addition, results of 2-DE and MS revealed that nine spots demonstrated above a twofold change in the same trend in all treatment groups, which were mainly related with (1) energy metabolism, (2) cell stress response/chaperones, (3) cytoskeleton development, (4) protein metabolism, and (5) cell surface signal transduction. The findings could provide potential biomarkers for lesion in nervous system induced by fluoride and lead exposure.