Curcumin attenuates memory deficits and the impairment of cholinergic and purinergic signaling in rats chronically exposed to cadmium.

This study investigated the protective effect of curcumin on memory loss and on the alteration of acetylcholinesterase and ectonucleotidases activities in rats exposed chronically to cadmium (Cd). Rats received Cd (1 mg/kg) and curcumin (30, 60, or 90 mg/kg) by oral gavage 5 days a week for 3 months. The animals were divided into eight groups: vehicle (saline/oil), saline/curcumin 30 mg/kg, saline/curcumin 60 mg/kg, saline/curcumin 90 mg/kg, Cd/oil, Cd/curcumin 30 mg/kg, Cd/curcumin 60 mg/kg, and Cd/curcumin 90 mg/kg. Curcumin prevented the decrease in the step-down latency induced by Cd. In cerebral cortex synaptosomes, Cd-exposed rats showed an increase in acetylcholinesterase and NTPDase (ATP and ADP as substrates) activities and a decrease in the 5'-nucleotidase activity. Curcumin was not able to prevent the effect of Cd on acetylcholinesterase activity, but it prevented the effects caused by Cd on NTPDase (ATP and ADP as substrate) and 5'-nucleotidase activities. Increased acetylcholinesterase activity was observed in different brain structures, whole blood and lymphocytes of the Cd-treated group. In addition, Cd increased lipid peroxidation in different brain structures. Higher doses of curcumin were more effective in preventing these effects. These findings show that curcumin prevented the Cd-mediated memory impairment, demonstrating that this compound has a neuroprotective role and is capable of modulating acetylcholinesterase, NTPDase, and 5'-nucleotidase activities. Finally, it highlights the possibility of using curcumin as an adjuvant against toxicological conditions involving Cd exposure. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 70-83, 2017.

Grape Juice Concentrate Protects Rat Liver Against Cadmium Intoxication: Histopathology, Cytochrome C and Metalloproteinases Expression.

The aim of this study was to investigate if grape juice concentrate is able to protect rat liver against cadmium toxicity. For this purpose, histopathological analysis, cytochrome C expression and immunoexpresssion of metalloproteinases (MMP) 2 and 9 were investigated. A total of 15 Wistar rats weighing 250 g on the average, and 8 weeks age were distributed into 3 groups (n=5), as follows: Control group (non-treated group, CTRL); Cadmium group (Cd) and grape juice concentrate group (Cd+GJ). Histopathological analysis revealed that liver from animals treated with grape juice concentrate improved tissue degeneration induced by cadmium intoxication. Animals intoxicated with cadmium and treated with grape juice concentrate showed higher cytochrome C gene expression in liver cells. No significant statistically differences (p>0.05) were found to MMP 2 and 9 immunoexpression between groups. Taken together, our results demonstrate that grape juice concentrate is able to prevent tissue degeneration in rat liver as a result of increasing apoptosis.

α-Lipoic acid protects against the oxidative stress and cytotoxicity induced by cadmium in HepG2 cells through regenerating glutathione regulated by glutamate-cysteine ligase.

Alpha-lipoic acid (α-LA) is an important antioxidant that is capable of regenerating other antioxidants, such as glutathione (GSH). In the present study, we examined the protective effects of α-LA against the oxidative stress and cytotoxicity induced by cadmium in human hepatoma cell lines (HepG2) and investigated if the process was mediated through regenerating GSH. Our results showed that after exposure to 25 µM cadmium for 16 h, there was a significant decrease in the cell viability and glutathione levels and a significant increase in lipid peroxidation (p<0.01) compared with untreated cells. The presence of α-LA significantly attenuated cadmium-induced cytotoxicity and lipid peroxidation, and reversed cellular GSH levels compared with cadmium-treated cells (p<0.05). Compared with the cells treated with cadmium, co-treatment with α-LA and cadmium significantly increased the activities of γ-glutamylcysteine ligase (γ-GCL), the rate limiting enzyme in GSH biosynthesis and the mRNA and the protein levels of γ-GCL catalytic subunit (GCLC) and a modifier subunit (GCLM). In conclusion, our results indicated that α-LA is an effective agent to reduce the oxidative stress and cytotoxicity induced by cadmium by regenerating GSH levels through increasing the activities and the expressions of γ-GCL.

Palm oil induced changes in ocular tissue lipid peroxidation, antioxidant enzymes and ATPases of rabbits in cadmium toxicity.

This study determined the effect of supplementing rabbit diet with palm oil (PO) on lipid peroxidation, antioxidant enzymes and ATPases of different sections of the eyes in ocular cadmium toxicity. Twenty male New Zealand rabbits were randomly assigned to 4 groups of 5 rabbits in a study that lasted for 4 weeks. The control was given deionised water as eye drops and the other groups of rabbits were given eye drops of solution of 2mgkg(-1) body wt cadmium (as 3CdSO(4).8H(2)O). One test group was fed with the normal chow alone and the other test groups were fed with the chow fortified with either 5% or 10% palm oil. Ocular treatment of rabbit with cadmium significantly (P<0.05) reduced their weight compared with the control. Feeding the animals with palm oil (PO) improved the weights of the animals and decreased cadmium accumulation in the eye tissues. Lipid peroxidation level was raised by cadmium in the cornea, lens and retina with palm oil supplementation of the animal diet significantly (P<0.05) reducing the level of lipid peroxidation of the retina. Cadmium significantly (P<0.05) reduced antioxidant enzymes and ATPases in the eye tissues compared with the control. Feeding the rabbits with PO significantly (P<0.05) increased the activities of these enzymes in the retina to levels comparable with the control, with the 10% supplementation producing a more pronounced effect. The study shows that PO can alter cadmium accumulation, antioxidant enzymes and ATPases in ways which suggest that it offers protection of the eyes from ocular exposure to cadmium.

Short-interfering RNA-mediated silencing of thioredoxin reductase 1 alters the sensitivity of HeLa cells toward cadmium.

The mammalian thioredoxin reductase (TrxR) is a selenocysteine-containing flavoprotein that regulates the thioredoxin system, one of the major systems that maintain the intracellular redox balance. We previously reported that cytosolic TrxR (TrxR1), one of three mammalian TrxR isozymes, was induced by treatment with cadmium. In the present study, to study the role of cadmium-induced TrxR1 in cellular defense, we silenced the expression of TrxR1 in HeLa cells by using small interfering RNA and examined the effect of TrxR1 silencing on the sensitivity of the cells toward cadmium. We found that the gene silencing of TrxR1 had a dual effect on cadmium-induced cell death, depending on the concentration of cadmium. The TrxR1 silencing increased the sensitivity toward a low dose (less than 10 microM) of cadmium but decreased the sensitivity toward a high dose of cadmium. These results suggested that TrxR1 might play an important role in the cellular defense system against cadmium in two ways. TrxR1 might rescue the cells from a low dose of cadmium-induced moderate injury, while it might promote the death of cells severely injured by a high dose of cadmium.

Effect of green tea catechin on arachidonic acid cascade in chronic cadmium-poisoned rats.

The purpose of this study was to investigate the effect of green tea catechin on the cyclooxygenase and lipoxygenase pathways in chronic cadmium-poisoned rats. Sprague-Dawley male rats weighing 100 +/- 10 g were randomly assigned to one normal and three cadmium-poisoned groups. The cadmium groups were classified as catechin-free diet group (Cd-0C), 0.25% catechin diet group (Cd-0.25C) and 0.5% catechin diet group (Cd-0.5C), in accordance with the level of catechin supplement. The phospholipase A2 activity was remarkably increased 117% in the Cd-0C group and 60% in the Cd-0.25C group compared with the normal group, and the level in the Cd-0.5C group was the same as the normal group. Activity of platelet cyclooxygenase increased 284% in the Cd-0C group, 147% in the Cd-0.25C group and 193% in the Cd-0.5C group. The synthesis of platelet thromboxane A2 (TXA2) increased 157% in the Cd-0C group and 105% in the Cd-0.25C group, compared with the normal group. The Cd-0.5C group showed the same level as the normal group. Prostacyclin (PGI2) formation in the aorta decreased 24% in the Cd-0C group and 18% in the Cd-0.25C group. The ratio of PGI2/TXA2, the thrombocyte synthesis index, decreased 70% in the Cd-0C group and 59% in the Cd-0.25C group. The activity of 5'-lipoxygenase in the polymorphonuclear leukocyte was increased 40% in the Cd-0C group as compared with the normal group. Catechin-supplemented Cd-0.25C and Cd-0.5C groups showed the level of the normal group. In this study, the observed content of leukotriene B4, which induces the inflammatory process, increased 54% in the Cd-0C group, and in catechin-supplemented groups, showed the same level as in the normal group. The serum peroxide value increased 60% in the Cd-0C group compared with the normal group; but in the Cd-0.5C group, it showed the level of the normal group. These results indicate that chronic cadmium poisoning in rats accelerates arachidonic acid metabolism. Inhibition of arachidonic acid metabolism due to catechin supplementation, however, decreases platelet aggregation and inflammatory action. In conclusion, it would appear that green tea catechin supplementation in chronic cadmium-poisoned rats inhibits the arachidonic acid cascade by regulating the activity of phospholipase A2.

[Changes in organ-specific enzymes under the influence of an enriched food ration in experimental cadmium poisoning]. / Promeni v niakoi organospetsifichni enzimi pod vliianie na obogatena khranitelna dazhba pri eksperimentalna kadmieva intoksikatsiia.

During a 3-month experiment is studied the effect of enriched with iron, calcium, phosphorous and vitamin D2 food ration on the changes in the organospecific enzymes in everyday introduction in the organism of experimental animals of cadmium sulfate in dose 1/40 LD50 (7 mg/kg-1). The serum activity of GOT and GPT is traced in dynamics at the end of the first, second and third month, as well as the activity of gamma-GT, LAP and APh in homogenates of liver and kidneys. The changes established in most of the experimental groups and the dates of observation show an increase in the serum and tissue activity of the examined enzymes (GOT, GPT, LAP). The tissue activity of gamma-GT and the quantity of free sulfhydryl groups are decreased in some of the dates of observation (I and III month). Both the isolated effect of cadmium and enriched food ration and their combined effect are discussed.

Effect of cadmium chloride on the rat testicular soluble selenoenzyme, glutathione peroxidase.

Thirty-six hours after male rats were injected with 25 mumoles cadmium chloride/ml/kg of body weight they exhibited decreased plasma and testicular glutathione (GSH) peroxidase activity, testicular atrophy and necrosis, and increased testicular thiobarbituric acid-reactive products. Seven days after injection, only the plasma GSH peroxidase activity returned to normal. The decrease in testicular GSH peroxidase activity was not reversible by dialysis against buffer or by the addition of selenium as buffered selenomethionine. In vitro inhibition of testicular GSH peroxidase activity occurred at 0.3 mM cadmium. All in vivo effects were prevented by a prior injection of 25 mumoles sodium selenite/ml/kg of body weight. Testicular GSH peroxidase may be the direct or indirect target of cadmium-induced testicular damage, and this damage results in lipid peroxidation.