Alterations in the hepatic enzymes following experimental lead poisoning

Quercetin as a Dietary Supplementary Flavonoid Alleviates the Oxidative Stress Induced by Lead Toxicity in Male Wistar Rats

Quercetin is a naturally existing plant pigment belonging to the flavonoid group; it is contained in a wide range of vegetables and fruits. The accumulated evidence points to the potential uses of quercetin in protection of some disease conditions. Lead is one of the highly toxicant heavy metals that are widely spread in the environment and implicated in a wide spectrum of industries. No previous study has been reported to evaluate the effect of quercetin on lead toxicity. Therefore, the present study was conducted to elucidate some aspects of quercetin bioactivities in regard to its ability to combat the oxidative stress induced by lead toxicity. For this purpose, a total of sixty male Wistar rats were randomly and equally divided into three groups of 20 animals each; untreated control animals (group 1), lead-exposed animals (group 2; exposed to lead daily by oral gavage at the dose of 80 mg/Kg b.w.), and group 3 of animals, which were exposed to lead and daily received quercetin (10 h gap time between lead exposure and the receiving of quercetin) by oral gavage at the dose of 350 mg/Kg b.w. The experiment period was 8 weeks. All the assayed hematological and biochemical parameters of animals exposed to lead were significantly altered compared with the untreated control levels. Animals exposed to lead (group 2) exhibited significant decrements of the erythrocytic and total leucocytic counts, hemoglobin concentration, packed cell volume percent, total proteins, albumin and globulin. These animals also disclosed significantly decreased levels of antioxidant markers including total thiols, catalase and glutathione. On the other hand, these animals demonstrated significant increments in the levels of bilirubin, urea, creatinine, BUN, serum enzymes, H₂O₂ and MDA. Animals exposed to lead and given quercetin (group 3) exhibited improvement of these parameters, which were brought back at varying degrees toward the untreated control levels. Basing on the improvements of the assayed hematological and biochemical parameters, it was concluded that quercetin as a dietary supplement can act efficiently as an antioxidant to counteract the oxidative stress induced by lead toxicity and to maintain the oxidant antioxidant balance.

Effect of gervital in attenuating hepatotoxicity caused by methotrexate or azathioprine in adult albino rats

Methotrexate (MTX) and azathioprine (AZA) are chemotherapeutic, antimetabolic, and immunosuppressive agents with substantial risks such as oxidative lesions to the liver. This study examined the effect of grape seed extract (GSE; gervital) in attenuating hepatotoxicity caused by MTX or AZA treatment. Rats were divided into six groups (six rats per group): Group I, normal control group; Group II, GSE (150 mg/kg/day); Group III, MTX (8 mg/kg/week); Group IV, AZA (15 mg/kg/day); Group V, GSE (150 mg/kg/day) + MTX (8 mg/kg/week); and Group VI, GSE (150 mg/kg/day) + AZA (15 mg/kg/day). After 35-day experimental period, all rats were sacrificed and blood was collected for biochemical study and hemoglobin (Hb) assessment. The liver was weighed and triaged for histological, ultrastructural, and biochemical studies. MTX and AZA treatment decreased Hb levels, increased relative liver weight, increased the activity of glutamate pyruvate transaminase (ALT) and glutamate oxaloacetate transaminase (AST) aminotransferase (ALT) and aspartate aminotransferase (AST) values, and displayed histopathological and ultrastructural alterations. These changes included the disorganization of hepatocytes, pyknosis, karyolysis of some nuclei, and mononuclear leukocytic infiltration. The liver with significant oxidative stress (OS) showed decreased reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) and increased malondialdehyde (MDA) levels. In contrast, GSE administration ameliorated ALT, AST, and all histopathological and ultrastructural changes. GSE treatment also reduced MDA levels but increased the antioxidant parameters. In conclusion, it was concluded that GSE supplementation could be considered as a promising antioxidant in reducing OS, histopathological and ultrastructural alterations induced by MTX and AZA.

Parental Lead Exposure Promotes Neurobehavioral Disorders and Hepatic Dysfunction in Mouse Offspring

Lead (Pb) induces neurotoxicity in both children and adults. Children are more vulnerable to Pb toxicity than adults. Little is known about the effects of Pb on the mental health of the children who are prenatally exposed. Therefore, we designed an animal experiment to compare the adverse effects of Pb on neurobehavioral and hepatic functions between Pb-exposed (Pb mice) and parental Pb-exposed (P-Pb mice) group mice. Mice were treated with Pb-acetate (10 mg/kg bodyweight/day) via drinking water. Male mice from unexposed parents treated with Pb for 90 days were defined as Pb mice, whereas male mice from Pb-exposed parents treated with Pb for further 90 days were defined as P-Pb mice. Anxiety-like behavior and spatial memory and learning were assessed by elevated plus maze and Morris water maze. Serum hepatic enzyme activities and butyrylcholinesterase activity were measured by an analyzer. P-Pb mice displayed increased anxiety-like behavior and memory and learning impairments compared to Pb mice. BChE activity was significantly decreased in P-Pb mice compared to Pb mice. Pb levels in the brains of P-Pb mice were significantly higher than those of Pb mice. The activities of serum hepatic enzymes of P-Pb mice were also higher than those of Pb mice. Additionally, histopathology data revealed that hepatic tissue injury was more pronounced in P-Pb mice than in Pb mice. Thus, the results suggest that persistent exposure to Pb from fetus to adult causes more severe neurobehavioral changes and hepatic toxicities than adult exposure only.

Lead exposure induces metabolic reprogramming in rat models

Lead is a toxin of great public health concern affecting the young and aging population. Several factors such as age, gender, lifestyle, dose, and genetic makeup result in interindividual variations to lead toxicity mainly due to variations in metabolic consequences. Hence, the present study aimed to examine dose-dependent lead-induced systemic changes in metabolism using rat model by administering specific doses of lead such as 10 (low lead; L-Pb), 50 (moderate lead; M-Pb), and 100 mg/kg (high lead; H-Pb) body weight for a period of one month. Biochemical and haematological analysis revealed that H-Pb was associated with low body weight and feed efficiency, low total protein levels (p ≤ 0.05), high blood lead (Pb-B) levels (p ≤ 0.001), low ALAD (δ-aminolevulinate dehydratase) activity (p ≤ 0.0001), high creatinine (p ≤ 0.0001) and blood urea nitrogen (BUN) (p ≤ 0.01) levels, elevated RBC and WBC counts, reduced haemoglobin and blood cell indices compared to control. Spatial learning and memory test revealed that H-Pb exposed animals presented high latency to the target quadrant and escape platform compared to other groups indicating H-Pb alters cognition function in rats. Histopathological changes were observed in liver and kidney as they are the main target organs of lead toxicity. LC-MS analysis further revealed that Butyryl-L-carnitine (p ≤ 0.01) and Ganglioside GD2 (d18:0/20:0) (p ≤ 0.05) levels were significantly reduced in H-Pb group compared to all groups. Further, pathway enrichment analysis revealed abundance and significantly modulated metabolites associated with oxidative stress pathways. The present study is the first in vivo model of dose-dependent lead exposure for serum metabolite profiling.

Elevated, sustained, and yet reversible biotoxicity effects of lead on cessation of exposure: Melatonin is a potent therapeutic option

Melatonin (Mel) is known to prevent and mitigate lead (Pb)-induced gonadotoxicity. However, there is no report in literature on the endogenous levels of different biomarkers after the cessation of Pb exposure, with or without treatment with Mel. Fifty adult male Wistar rats were divided into five groups (N = 10), which included control ((vehicle (normal saline) - treated) - 0.1 ml/day); lead chloride (PbCl₂) untreated (3 weeks vehicle + 3 weeks Pb); Pb recovery (3 weeks Pb + 3 weeks vehicle); Pb + Mel (3 weeks Pb + 3 weeks Mel); and Mel (3 weeks vehicle + 3 weeks Mel) groups. Pb and Mel were administered at 50 and 10 mg/kg B.W. (p.o.), respectively. The results showed that Pb caused significant decreases in total bilirubin (TB), phospholipids (PLP), superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (TAC), but significant elevations in alkaline phosphatase (ALP), aspartate aminotransferase (AST), triglyceride (TG), and malondialdehyde (MDA). Although the adverse effects of Pb on TB, ALP, AST, SOD, MDA, and TAC were sustained after the cessation of exposure, a reversal was observed in total cholesterol (TC), TG, PLP, CAT, and c-reactive protein (CRP) results. Nevertheless, the detrimental effects of Pb on alanine aminotransferase (ALT), albumin, and globulin were only expressed post-exposure. Treatment with Mel caused no significant effect on TB and albumin levels. However, unlike TAC and CRP, the hormone significantly reduced ALP, AST, ALT, TC, low-density lipoprotein cholesterol, PLP, SOD, CAT, MDA, and globulin to levels comparable to the control group. In conclusion, following the cessation of Pb exposure, alterations in physiological balance could be elevated, sustained, or reversible. However, Mel enhanced the reestablishment homeostatic status after Pb administration.

Lead Affects Vitamin D Metabolism in Rats

A negative association between blood lead and vitamin D concentrations has been reported, however, experimental data on the effect of lead (Pb) on vitamin D metabolism is scarce. We investigated the effects of Pb on serum vitamin D metabolites, vitamin D activating enzymes and vitamin D receptor (VDR) in rats. Newborn Wistar rat pups were exposed to 0.2% Pb-acetate via their dams’ drinking water from post-natal day (PND) 1 to 21 and directly in drinking water until PND30. Serum 25-hydroxyvitamin D was analyzed with LC-MS/MS and 1,25-dihydroxyvitamin D with an immunoassay. Tissue expression of vitamin D activating enzymes and VDR were measured by Western blot and immunohistochemistry. Serum 25-hydroxyvitamin D was significantly decreased at both PND21 and PND30, whereas 1,25-dihydroxyvitamin D was decreased (p < 0.05) only at PND21 in the Pb-exposed rats. Expression of renal 1-α-hydroxylase was decreased by Pb only at PND21 (p < 0.05) but the brain 1-α-hydroxylase was not affected. Hepatic 25-hydroxylase expression was significantly decreased at PND21 but significantly increased at PND30 by Pb exposure. VDR expression in the brain was increased at both PND21 and PND30 (p < 0.05). These results suggest that Pb interferes with vitamin D metabolism by affecting the expression of its metabolizing enzymes.

Role of caftaric acid in lead-associated nephrotoxicity in rats via antidiuretic, antioxidant and anti-apoptotic activities

Background Lead is a toxic metal that is widely distributed in the environment where caftaric acid (CA) is the ester form of caffeic acid where CA is the major dietary polyphenol present in various foods and beverages. The aim of this study was to evaluate the effect of CA in lead acetate (LA)-associated nephrotoxicity through antidiuretic, antioxidant and anti-apoptotic activities. Methods Forty-eight male albino rats divided into six equal groups; group 1 control injected intraperitoneally (ip) with saline (1 mL/kg of bw) over two weeks period, group 2 injected ip with CA (80 mg/kg of bw) over two weeks period, groups 3, 4, 5 and 6 injected ip with 100 μmol/kg of bw LA over two weeks period where groups 4, 5 & 6 co-injected ip with 1-deamino-8-D-arginine vasopressin (dDAVP) drug (1 mg/kg of bw), CA (40 mg/kg of bw), and CA (80 mg/kg of bw), respectively. Results The results obtained revealed that LA induced a significant decrease in kidney weight and serum sodium, potassium and chloride, but caused a significant increase in urinary volume, urinary excretion of sodium, potassium and chloride, serum urea, creatinine and uric acid. The LA also caused a significant decrease in kidney superoxide dismutase, glutathione peroxidase and induced a significant decrease in glutathione level while caused an increase in lipid peroxidation level. In addition, LA caused a decrease in p53 expression while induced an increase in bcl-2 expression in the kidney tissues. Co-injection of CA to LA-treated group restored all the above parameters to approach the normal values. The results supported with histopathological examinations. Conclusions In conclusion, the effect of CA on LA-related nephrotoxicity was occurred through antidiuretic, antioxidant, anti-apoptotic activities where the effect of CA was dose dependent.

Histological and biochemical biomarkers analysis reveal strong toxicological impacts of pollution in hybrid sparrow (Passer domesticus × Passer hispaniolensis) in southern Tunisia

Environmental pollution is a great concern worldwide. Our aim was to investigate the histopathological injuries and oxidative stress induced by exposure to contaminants in liver tissues of hybrid sparrows (Passer domesticus × Passer hispaniolensis) living in Gabès city, which is one of the most polluted hot spot in Tunisia. Our results show evidence of a pronounced impairment in liver function which is confirmed by histopathological changes as well as remarkable blood chemical alterations in sparrows living near the Gabès-Ghannouche factory complex of phosphate treatment. Moreover, a significant decrease in the hepatic activities of superoxide dismutase (SOD) and catalase (CAT) was observed in birds from Ghannouche when compared to other distant areas. Our study revealed also a significant increase in the liver levels of thiobarbituric acid reactive substances (TBARS), in sparrows living in Ghannouche, indicating oxidative damage to membrane lipids. Overall, our results suggest that the hybrid sparrow offers a suitable model for biomonitoring programs of atmosphere pollutants and the selected biomarkers may function as useful tool to evaluate the effects of pollutants on living organisms.

Bioactive peptide carnosin protects against lead acetate-induced hepatotoxicity by abrogation of oxidative stress in rats

Context Oxidative stress is a common mechanism of liver injury. Carnosine is a dipeptide having strong antioxidant effects. Objectives We investigated the effects of carnosine on lead-induced hepatotoxicity and oxidative stress in rats. Materials and methods Animals received an aqueous solution of lead acetate (500 mg Pb/L in the drinking water) and/or daily oral gavage of carnosine (10 mg/kg) for 8 weeks. Rats were then weighed and used for the biochemical (commercial kits), molecular (standard chemical methods) and histological (microscopic) evaluations. Results Lead-induced oxidative stress in liver tissue was indicated by a significant increase in the level of malondialdehyde (MDA) (8.25 ± 0.15 nmol/mg) as well as decrease in the level of total antioxidant capacity (TAC) (1.72 ± 0.25 μmol/g) and total thiol (SH) groups) 1.9 ± 0.22 μmol/g). Carnosine treatment decreased MDA (4 ± 0.08 nmol/mg), whereas it increased the contents of total thiol (3.25 ± 0.04 μmol/g) and TAC (3.44 ± 0.32 μmol/g) in the lead group. Carnosine also prevented the decreased body weight (p < 0.001), albumin (p < 0.05) and total protein levels (p < 0.001) and increased liver weight (p < 0.05) and activates of hepatic enzymes (p's < 0.001) (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase) in the lead group. Furthermore, histopathological study showed that carnosine attenuates liver damage by decreasing necrosis and infiltration of inflammatory cells. Conclusion Carnosine prevented lead-induced hepatotoxicity, indicated by molecular, biochemical and histopathological analyses through inhibiting lipid peroxidation and enhancing antioxidant defence systems. Therefore, carnosine makes a good candidate to protect against the deleterious effect of chronic lead intoxication.

Histochemical Characterization of Renal Phosphatases in Rats Treated With Lead

Seven groups of 84 male white rats ( Rattus norvegicus) were exposed to lead acetate (0, 0.125, 0.25, 0.5, 1.0, 2.0, and 4% for 1 to 5 months) in drinking water to investigate possible histochemical changes in the activity of renal phosphatases due to lead intoxication. In comparison with respective control rats, chronic exposure to subtoxic doses of lead increased the activities of acid-, neutral-, alkaline-, and membrane-bound Na+-K+ adenosine triphosphatase and glucose-6-phosphatase. In contrast, significant reduction in the activities of 5-nucleotidase and mitochondrial adenosine triphosphatase was observed. Changes in the activity of renal phosphatases were seen mainly in the epithelium of the proximal tubules and, to a lesser extent, in the medullary interstitial cells and the glomeruli as well. These histochemical findings led us to conclude that such changes in the activity of phosphatases were due to long-term exposure to subtoxic doses and could be an adaptation to the metabolic, structural, and functional alterations in the organelles of the renal cells due to lead intoxication.

Histological and histochemical alterations in the liver induced by lead chronic toxicity

Adult males of the Wistar albino rats (Rattus norvegicus) were exposed to lead acetate trihydrate in drinking water (0.0%, 0.25%, 0.5%, 1% and 2% for 1-12 months) to investigate histological and histochemical alterations induced by lead intoxication in the liver. Chronic exposure to subtoxic concentrations of lead produced changes in the hepatocytes, portal triads and the sinusoids. The alterations in the hepatocytes were mainly anisokaryosis, nuclear vesiculation, binucleation, cytoplasmic inclusions, cytoplasmic swelling, hydropic degeneration, necrosis and reduction in glycogen content. In addition, portal triads mild chronic inflammation, Kupffer cells hyperplasia and occasional fatty change were seen together with hemosiderosis. No portal fibrosis or cirrhosis was detected due to chronic subtoxic doses of lead exposure in the liver of any member of the dose groups over the entire period of the study. Chronic lead exposure also increased the activities of alkaline phosphatase and α-glycerophosphate-dehydrogenase which might be an adaptation to the metabolic, structural and functional changes in the organelles of hepatic cells due to lead intoxication. The findings revealed that chronic exposure to lead produced significant histological and histochemical changes in the liver of the Wistar albino rats.

Protective effect of Aquilegia vulgaris (L.) against lead acetate-induced oxidative stress in rats

Oxidative stress has been proposed as a possible mechanism involved in lead toxicity. The current study was carried out to evaluate the antioxidant activity of the ethanol extract of Aquilegia vulgaris (L.) against lead acetate (LA)-induced oxidative stress in male rats. Tested animals were treated orally with A. vulgaris extract (100 ppm) in combination with, before, or after LA treatment (20 ppm). The results indicated that the extract alone did not induce any significant changes in body weight gain, food intake, serum biochemical chemistry or the histological picture of the liver and kidney. However, it increased significantly the level of Glutathione (GSH). On the other hand, LA decreased food intake, body weight gain and induced oxidative stress as indicated by the significant changes in serum biochemical parameters and histological picture of liver and kidney and increased lipid peroxide and reduces GSH levels in liver tissues. The extract succeeded to improve the histological pictures of liver and kidney and the biochemical parameters towards the normal values of the control. Moreover, this improvement was pronounced in the animals treated with the extract after LA intoxication.

Combined efficacies of lipoic acid and 2,3-dimercaptosuccinic acid against lead-induced lipid peroxidation in rat liver

Oxidative stress with subsequent lipid peroxidation has been postulated as one mechanism for lead toxicity. Hence in assessing the protective effects of lipoic acid (LA) and meso 2,3-dimercaptosuccinic acid (DMSA) on lead toxicity, they were tested either separately or in combination for their effects on selected indices of hepatic oxidative stress. Elevated levels of lipid peroxides were accompanied by altered antioxidant defense systems. Lead acetate (Pb - 0.2%) was administered in drinking water for five weeks to induce toxicity. LA (25 mg kg(-1) body wt. day(-1) i.p) and DMSA (20 mg kg(-1) body wt. day(-1) i.p) were administered individually and also in combination during the sixth week. Lead damage to the liver was evident in the decreases in hepatic enzymes alanine transaminase (-38%), aspartate transaminase (-42%) and alkaline phosphatase (-43%); increases in lipid peroxidation (+38%); decreases in the antioxidant enzymes catalase (-45%), superoxide dismutase (-40%), glutathione peroxidase (-46%) and decreases in glutathione (-43%) and decreases in glutathione metabolizing enzymes, glutathione reductase (-59%), glucose-6-phosphate dehydrogenase (-27%) and glutathione-S-transferase (-42%). In combination LA and DMSA completely ameliorated the lead induced oxidative damage. Either compound alone was however only partially protective against lead damage.

Histochemical demonstration of changes in the activity of hepatic phosphatases induced by experimental lead poisoning in male white rats (Rattus norvegicus)

Seven hepatic phosphatases were histochemically investigated in male white rats (Rattus norvegicus) pretreated with chronic subtoxic doses of lead acetate. Lead has increased the activities of alkaline-, acid-, neutral-, adenosine mono- and glucose-6-phosphatase, but has markedly decreased the activity of membrane-bound Na+-K+, ATPase while the activity of mitochondrial Mg2+-ATPase was not altered. It has also produced heterogenous alterations in the distribution patterns, sites of the enzymatic activities and in the intensity of phosphatase activities among the same type of cells in the terminal afferent and efferent venules of the hepatic lobules. The obtained histochemical findings indicate that the alterations in the activities of hepatic phosphatases could be an adaptation to the metabolic, structural and functional changes in the organelles of hepatic cells due to lead intoxication.