Effects of Mercury Exposure on Blood Chemistry and Liver Histopathology of Male Rats

Biochemical, morphological and molecular assessments of n butanol fraction of Phoenix dactylifera L. following exposure to inorganic mercury on the liver of Wistar rats

BACKGROUND

Mercury chloride (HgCl2) damages tissues it comes in contact with in sufficient concentration. This study evaluated the protective effects of n-butanol fraction of Phoenix dactylifera (BFPD) on mercury-triggered liver toxicity in Wistar rats. 25 male rats were divided into 5 groups of 5 rats each. Group I was administered 2 ml/kg of distilled water; group II was administered 5 mg/kg of HgCl2; group III was administered 500 mg/kg of BFPD + 5 mg/kg of HgCl2; group IV was administered 1000 mg/kg of BFPD + 5 mg/kg of HgCl2, while group V was administered 100 mg/kg of silymarin + 5 mg/kg of HgCl2. orally for 2 weeks. The rats were euthanized and liver tissue blood samples were collected for histological, histochemical, stereological, immunohistochemical, molecular, and biochemical studies.

RESULTS

The results revealed that HgCl2 induced oxidative stress in the rats evident by histoarchitectural distortions and altered levels of liver enzymes, proteins, and oxidative stress biomarkers when compared to the control. However, BFPD treatment restored these changes. Glutathione peroxidase levels decreased (p < 0.05) in the HgCl2-treated group when compared to the control and BFPD-treated groups. HgCl2 group revealed reduced reactivity with histochemical and immunohistochemical stains (Masson's Trichrome and B cell Lymphoma 2) when compared to the control, with a significant decrease in quantified liver Bcl-2 stain intensity when compared to the silymarin-treated group. BFPD administration revealed normal staining intensity comparable to the control. HgCl2 administration revealed a remarked decrease in the number of hepatocytes when compared to the control, BFPD, and silymarin groups. BFPD preserved (p < 0.05) the stereological features when compared to the HgCl2-treated group. GPx activity in the liver decreased (p < 0.05) with HgCl2 administration when compared to the control and silymarin-treated groups. BFPD attenuated GPx gene activity to levels similar to the control indicating some level of amelioration against HgCl2-induced toxicity.

CONCLUSIONS

The ability of BFPD to mitigate HgCl2 triggered liver alterations could be attributed to the antioxidant property of its flavonoid content. Therefore, BFPD may be a potential candidate for treating and managing liver-induced mercury intoxication.

Deleterious effects of mercury contamination on immunocompetence, liver function and egg volume in an antarctic seabird

Mercury (Hg) is a globally important pollutant that can negatively impact metabolic, endocrine and immune systems of marine biota. Seabirds are long-lived marine top predators and hence are at risk of bioaccumulating high Hg concentrations from their prey. Here, we measured blood total mercury (THg) concentrations and relationships with physiology and breeding parameters of breeding brown skuas (Stercorarius antarcticus) (n = 49 individuals) at Esperanza/Hope Bay, Antarctic Peninsula. Mean blood THg concentrations were similar in males and females despite the differences in body size and breeding roles, but differed between study years. Immune markers (hematocrit, Immunoglobulin Y [IgY] and albumin) were negatively correlated with blood THg concentrations, which likely indicates a disruptive effect of Hg on immunity. Alanine aminotransferase (GPT) activity, reflecting liver dysfunction, was positively associated with blood THg. Additionally, triacylglycerol and albumin differed between our study years, but did not correlate with Hg levels, and so were more likely to reflect changes in diet and nutritional status rather than Hg contamination. Egg volume correlated negatively with blood THg concentrations. Our study provides new insights into the sublethal effects of Hg contamination on immunity, liver function and breeding parameters in seabirds. In this Antarctic species, exposure to sublethal Hg concentrations reflects the short-term risks which could make individuals more susceptible to environmental stressors, including ongoing climatic changes.

Association between Pb, Cd, and Hg Exposure and Liver Injury among Korean Adults

BACKGROUND

Exposure to lead (Pb), cadmium (Cd), and mercury (Hg) has been reported to be associated with liver-related diseases. However, studies examining the association between heavy metal exposure and liver injury in a large population are scant and characterized by inconsistent results. This study aimed to evaluate the association between levels of heavy metal exposure and liver injury in the general population.

METHODS

Data for 2953 participants aged 19 years or more obtained from the Korean National Environmental Health Survey (KoNEHS) Cycle 3 (2015-2017) were used. The associations between levels of blood or urine heavy metals (Pb, Cd, and Hg) and liver function biomarkers [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT)] were evaluated using multiple linear regression analysis.

RESULTS

Regarding the blood Pb (BPb), AST was higher in those of the 4th quartile, ALT was higher in those of the 2nd and 4th quartiles, and GGT was higher in those of the 3rd and 4th quartiles than in the 1st quartile. For urinary Cd (UCd), AST was higher in those of the 4th quartile; ALT was higher in those of the 2nd, 3rd, and 4th quartiles; and GGT was higher in the 4th quartile than in the 1st quartile. For the blood Hg (BHg), AST was higher in those of the 2nd and 4th quartile, ALT was higher in those of the 2nd, 3rd, and 4th quartiles; and GGT was higher in those of the 3rd and 4th quartiles than in the 1st quartile. There was no significant difference between urinary Hg (UHg) and liver function markers.

CONCLUSION

Heavy metal exposure showed an association with liver injury among the general adult population in Korea. Further studies are required to clarify the relationship between heavy metals and liver injury.

Molecular mechanism of heavy metals (Lead, Chromium, Arsenic, Mercury, Nickel and Cadmium) - induced hepatotoxicity - A review

Heavy metals pose a serious threat if they go beyond permissible limits in our bodies. Much heavy metal's viz. Lead, Chromium, Arsenic, Mercury, Nickel, and Cadmium pose a serious threat when they go beyond permissible limits and cause hepatotoxicity. They cause the generation of ROS which in turn causes numerous injuries and undesirable changes in the liver. Epidemiological studies have shown an increase in the levels of such heavy metals in the environment posing a serious threat to human health. Epigenetic alterations have been seen in the event of exposure to such heavy metals. Apoptosis, caspase activation as well as ultrastructural changes in the hepatocytes have also been seen due to heavy metals. Inflammation involving TNF-alpha, pro-inflammatory cytokines, MAPK, ERK pathways have been seen in the event of heavy metal hepatotoxicity. All these have shown that these heavy metals pose a serious threat to human health in particular and the environment as a whole.

Mercury Exposure and Associations with Hyperlipidemia and Elevated Liver Enzymes: A Nationwide Cross-Sectional Survey

Mercury (Hg) has obesogenic properties. However, the associated health outcomes of population-level mercury exposure were unclear. This study investigated the relationships between blood mercury levels and obesity-related outcomes such as hyperlipidemia and elevated liver enzymes. Using the second cycle of the Korean National Environmental Health Survey (n = 6454), we performed logistic regression to examine the effects of Hg on hyperlipidemia and elevated liver enzymes. The blood mercury levels were significantly higher in the hyperlipidemia group (n = 3699, male: 4.03 μg/L, female: 2.83 μg/L) compared to the non-hyperlipidemia group (n = 2755, male: 3.48 μg/L, female: 2.69 μg/L), and high blood mercury levels were associated with an 11% higher risk of hyperlipidemia. The elevated liver enzymes group had higher mean blood mercury levels (n = 1189, male: 4.38 μg/L, female: 3.25 μg/L) than the normal group (n = 5265, male: 3.64 μg/L, female: 2.70 μg/L), and elevated blood mercury was associated with a 35% higher risk of elevated liver enzymes. Moreover, the effect was constant after adjusting for personal medications. These results indicate that mercury exposure is significantly associated with hyperlipidemia and elevated liver enzymes.

Induction of hepatic portal fibrosis, mitochondria damage, and extracellular vesicle formation in Sprague-Dawley rats exposed to copper, manganese, and mercury, alone and in combination

Increased anthropogenic activity and subsequent environmental exposure to heavy metals induce the production of reactive oxygen species (ROS), which increases oxidative stress and the risk of associated diseases. The aim of this study, in a subacute model of toxicity, was to investigate the effects of copper (Cu), manganese (Mn), and mercury (Hg) alone and in combination on the liver tissue of male Sprague-Dawley rats, exposed orally to 100 times the World Health Organization's acceptable water limits of each metal. General histological alterations as well as ultrastructural changes were investigated using light microscopy and transmission electron microscopy (TEM) respectively. Exposure to Cu, Mn, and Hg, alone and in combinations, caused hydropic swelling of the hepatocytes, dilation of the sinusoids, formation of binucleated hepatocytes with an increased inflammatory cell accumulation at the portal triad. Increased collagen deposition with associated fibrosis was also observed. Evaluation of hepatocyte ultrastructure revealed mitochondrial membrane damage and inner membrane swelling especially for hepatocytes exposed to Mn. Extracellular vesicle (EV) formation was observed in the liver tissue of all exposed rats. Furthermore, increased damage observed for metal combinations was possibly due to synergism. In conclusion, Cu, Mn, and Hg alone and as part of a mixture cause cellular damage, inflammation, and fibrosis increasing the risk of associated diseases.

Associations between mercury exposure and the risk of nonalcoholic fatty liver disease (NAFLD) in US adolescents

Little is known regarding the effects of environmental mercury (Hg) exposure on liver dysfunction in adolescents. We aimed to explore the association between Hg exposure and the risk of nonalcoholic fatty liver disease (NAFLD) in the adolescent population. The cross-sectional associations between blood Hg concentrations and serum alanine aminotransferase (ALT) levels, a surrogate for suspected NAFLD, were evaluated using data from adolescents (aged 12-17 years old) who participated in the National Health and Nutrition Examination Survey (NHANES), 1999-2014. A final sample of 6389 adolescents was analysed. Elevated ALT was defined as > 25 IU/L and > 22 IU/L for boys and girls ≤ 17 years old, respectively. Odds ratios (ORs) of Hg levels in association with serum ALT levels were estimated using a logistic regression after adjusting for gender, age, ethnicity, serum cotinine, body mass index, the poverty income ratio, and NHANES cycles. The median blood Hg level was 0.73 ± 0.91 μg/L amongst US adolescents. In the adjusted model, the ORs of elevated ALT levels of those in the 4th quartile were higher amongst non-Hispanic white adolescents (OR = 1.76, 95% CI 1.20, 2.59; P = 0.035) and those who were normal or underweight (OR = 1.41, 95% CI 1.08, 1.85; P = 0.020). No association was observed for the other variables. Our results indicate that the positive association between blood Hg exposure and the risk of NAFLD in US adolescents is the highest amongst non-Hispanic white and those who are normal or underweight, regardless of ethnicity. More research is necessary to confirm this association and to clarify the potential mechanisms.

In Vivo Biosensing Using Resonance Energy Transfer

Solution-phase and intracellular biosensing has substantially enhanced our understanding of molecular processes foundational to biology and pathology. Optical methods are favored because of the low cost of probes and instrumentation. While chromatographic methods are helpful, fluorescent biosensing further increases sensitivity and can be more effective in complex media. Resonance energy transfer (RET)-based sensors have been developed to use fluorescence, bioluminescence, or chemiluminescence (FRET, BRET, or CRET, respectively) as an energy donor, yielding changes in emission spectra, lifetime, or intensity in response to a molecular or environmental change. These methods hold great promise for expanding our understanding of molecular processes not just in solution and in vitro studies, but also in vivo, generating information about complex activities in a natural, organismal setting. In this review, we focus on dyes, fluorescent proteins, and nanoparticles used as energy transfer-based optical transducers in vivo in mice; there are examples of optical sensing using FRET, BRET, and in this mammalian model system. After a description of the energy transfer mechanisms and their contribution to in vivo imaging, we give a short perspective of RET-based in vivo sensors and the importance of imaging in the infrared for reduced tissue autofluorescence and improved sensitivity.

The Clinical Importance of the Mercury Problem in Artisanal Small-Scale Gold Mining

Artisanal small-scale mining is widely operated in various countries serving as a livelihood to many rural communities. However, it is a significant source of environmental mercury contamination which affects human health. Amalgamation and amalgam smelting, two significant steps in the artisanal small-scale mining operations generate lots of mercury vapors, leading to chronic exposure among miners. Thus, this article seeks to provide a topical review of recent findings on organ damage and metabolic disorders among mercury-exposed artisanal small-scale miners with emphasis on the contributing factors such as personal protective equipment usage and artisanal small-scale gold mining-specific occupational activities. Also, insights into the effect of mercury intoxication and mechanisms of action on organ and metabolic systems among exposed individuals are provided.

Toxicological Effects of Mercury Chloride on Laying Performance, Egg Quality, Serum Biochemistry, and Histopathology of Liver and Kidney in Laying Hens

The objective of this study was to determine the effects of mercury chloride (HgCl₂) on laying performance, egg quality, hepatic and renal histopathology, and serum biochemical profiles in laying hens. A total of 768 Hy-line brown laying hens aged 40 weeks were randomly allocated to four groups (8 pens per group and 24 hens per pen). The concentrations of mercury (Hg) in four groups were 0.280, 3.325, 9.415, and 27.240 mg/kg. Results revealed that dietary Hg could significantly reduce laying performance (P < 0.05) and egg quality (P < 0.05) and was dose-dependently deposited in albumen, yolk, eggshell, and whole egg. Meanwhile, the thicknesses of palisade layer, mammillary layer, and total layer, and the percent of palisade layer were significantly decreased (P < 0.05), while the percent of mammillary layer was sharply increased (P < 0.05) in eggshell. In addition, with increasing dietary dosage of Hg, accumulation of Hg in viscera was significantly increased (P < 0.05), and histopathological damages in liver and kidney were more and more severe. Serum alanine aminotransferase, aspartate aminotransferase, and globulin were significantly increased (P < 0.05), while serum albumin and albumin to globulin ratio were significantly decreased (P < 0.05) in 27.240 mg/kg Hg group. Blood urea nitrogen, uric acid, and creatinine were significantly increased (P < 0.05) in 3.325, 9.415, and 27.240 mg/kg Hg groups. These results suggested that dietary HgCl₂ could reduce laying performance and egg quality with hepatic and renal function disorders in laying hens.

Variation in thyroid hormone levels is associated with elevated blood mercury levels among artisanal small-scale miners in Ghana

Background

Mercury can be very toxic to human health even at low dose of exposure. Artisanal small-scale miners (ASGMs) use mercury in gold production, hence are at risk of mercury-induced organ dysfunction.

Aim

We determined the association between mercury exposure, thyroid function and work-related factors among artisanal small-scale gold miners in Bibiani- Ghana.

Method

We conveniently recruited 137 consenting male gold miners at their work site in Bibiani-Ghana, in a comparative cross-sectional study. Occupational activities and socio-demographic data of participants were collected using a questionnaire. Blood sample was analysed for total mercury and thyroid hormones.

Results

Overall, 58.4% (80/137) of the participants had blood mercury exceeding the occupational exposure threshold (blood mercury ≥5μg/L). T3(P<0.0001) and T4(P<0.0001) were significantly reduced among the exposed group compared to the non-exposed. TSH showed no significant variation between the exposed and non-exposed groups. Longer work duration (≥5years), gold amalgamation, gold smelting and sucking of excess mercury with the mouth were associated with increased odds of mercury exposure. Blood mercury showed negative correlation with T3(r = -0.29, P<0.0001), and T4(r = -0.69, P<0.0001) and positive correlation with work duration (r = 0.88, P<0.001). Even though a positive trend of association between blood mercury and TSH levels was recorded, it was not significant (r = 0.07, P = 0.4121)

Conclusion

Small scale miners in Bibiani are exposed to mercury above the occupational threshold which may affect thyroid hormone levels.

Mercury Exposure in Association With Decrease of Liver Function in Adults: A Longitudinal Study

Objectives

Although mercury (Hg) exposure is known to be neurotoxic in humans, its effects on liver function have been less often reported. The aim of this study was to investigate whether total Hg exposure in Korean adults was associated with elevated serum levels of the liver enzymes aspartate aminotransferase (AST), alanine transaminase (ALT), and gamma-glutamyltransferase (GGT).

Methods

We repeatedly examined the levels of total Hg and liver enzymes in the blood of 508 adults during 2010-2011 and 2014-2015. Cross-sectional associations between levels of blood Hg and liver enzymes were analyzed using a generalized linear model, and nonlinear relationships were analyzed using a generalized additive mixed model. Generalized estimating equations were applied to examine longitudinal associations, considering the correlations of individuals measured repeatedly.

Results

GGT increased by 11.0% (95% confidence interval [CI], 4.5 to 18.0%) in women and 8.1% (95% CI, -0.5 to 17.4%) in men per doubling of Hg levels, but AST and ALT were not significantly associated with Hg in either men or women. In women who drank more than 2 or 3 times per week, AST, ALT, and GGT levels increased by 10.6% (95% CI, 4.2 to 17.5%), 7.7% (95% CI, 1.1 to 14.7%), and 37.5% (95% CI,15.2 to 64.3%) per doubling of Hg levels, respectively, showing an interaction between blood Hg levels and drinking.

Conclusions

Hg exposure was associated with an elevated serum concentration of GGT. Especially in women who were frequent drinkers, AST, ALT, and GGT showed a significant increase, with a significant synergistic effect of Hg and alcohol consumption.

Gender differences in mercury-induced hepatotoxicity: Potential mechanisms

The accumulation of mercury in the liver causes hepatotoxicity. The organic anion transporter 3 (Oat3) and the multidrug-resistance associated protein 2 (Mrp2) are involved in the hepatic excretion of toxins and drugs and in the hepatic handling of mercury. The aim of this work was to study if there are gender-related differences in mercuric chloride (HgCl₂)-induced hepatotoxicity in rats. Total mercury levels and protein expressions of Oat3 and Mrp2 in liver samples were also assessed to clarify the mechanisms underlying mercury-induced liver damage in male and female rats. Control and HgCl₂-treated male and female Wistar rats were used. Hepatotoxicity was evaluated by plasma activity of transaminases and alkaline phosphatase, as well as by histopathological analysis. Oat3 and Mrp2 expression was assessed by immunoblotting. Female rats displayed a higher HgCl₂-induced hepatotoxicity than male rats as demonstrated by the higher alterations in the plasma markers of liver damage and in the histopathology. The sex-related differences observed in the hepatic damage can be explained by the higher accumulation of mercury in liver from female rats. In this connection, after mercury treatment the expression of Mrp2 decreased in both sexes and the expression of Oat3 decreased only in males. The decreased in Oat3 abundance in the hepatocytes membranes in mercury-treated males would limit the uptake of mercuric ions into the liver protecting them from mercury hepatotoxicity.

Curcuma longa Linn. extract and curcumin protect CYP 2E1 enzymatic activity against mercuric chloride-induced hepatotoxicity and oxidative stress: A protective approach

The present investigation has been conducted to evaluate the therapeutic potential of Curcuma longa (200mgkg^-1, po) and curcumin (80mgkg^-1, po) for their hepatoprotective efficacy against mercuric chloride (HgCl₂: 12μmolkg^-1, ip; once only) hepatotoxicity. The HgCl₂ administration altered various biochemical parameters, including transaminases, alkaline phosphatase, lactate dehydrogenase, bilirubin, gamma-glutamyl transferase, triglycerides and cholesterol contents with a concomitant decline in protein and albumin concentration in serum which were restored towards control by therapy of Curcuma longa or curcumin. On the other hand, both treatments showed a protective effect on drug metabolizing enzymes viz. aniline hydroxylase (AH) and amidopyrine-N-demethylase (AND), hexobarbitone induced sleep time and BSP retention. Choleretic, 1,1-diphenyl-2-picryl-hydrazil (DPPH)-free radical scavenging activities and histological studies also supported the biochemical findings. The present study concludes that Curcuma longa extract or curcumin has the ability to alleviate the hepatotoxic effects caused by HgCl₂ in rats.

Mercuric chloride induced hepatotoxic and hematologic changes in rats

This study focuses on investigating the possible protective effect of sodium selenite (Na2SeO3) and/or vitamin E against mercuric chloride (HgCl2)-induced hepatotoxicity in rat. Male rats were given HgCl2 (1 mg/kg body weight (bw)) and HgCl2 plus Na2SeO3 (0.25 mg/kg bw) and/or vitamin E (100 mg/kg bw) daily via gavage for 4 weeks. HgCl2-treated groups had significantly higher white blood cell and thrombocyte counts than the control group. Serum activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl-transferase, and lactate dehydrogenase significantly increased and serum levels of total protein, albumin, triglyceride, total cholesterol, and low-density lipoprotein cholesterol significantly decreased in the HgCl2-treated groups compared with control group. Malondialdehyde level significantly increased and superoxide dismutase, catalase, and glutathione peroxidase activities decreased in liver tissue of HgCl2-treated rats. Also, HgCl2 exposure resulted in histopathological changes. Supplementation of Na2SeO3 and/or vitamin E provided partial protection in hematological and biochemical parameters that were altered by HgCl2. As a result, Na2SeO3 and/or vitamin E significantly reduced HgCl2-induced hepatotoxicity, but not protected completely.

Protein expression of kidney and liver bilitranslocase in rats exposed to mercuric chloride--a potential tissular biomarker of toxicity

Bilitranslocase (BTL) is a plasma membrane carrier that transports organic anions of physiological and pharmacological interest. It is expressed in basolateral plasma membrane of kidney and liver. BTL has been recently described as a marker of transition from normal tissue to its neoplastic transformation in human kidney. Inorganic mercury is a major environmental contaminant that produces many toxic effects. Previous reports have described an interaction between BTL and mercuric ions. This study was designed to evaluate the renal and hepatic expression of BTL in rats exposed to a nephrotoxic and hepatotoxic dose of HgCl2. Male rats were treated with a single injection of HgCl2 at a dose of 4mg/kg body wt, i.p. (HgCl2 group). Control rats received the vehicle alone (Control group). Studies were carried out 18h after injection. Afterwards, the kidneys and livers were excised and processed for histopathological studies or immunoblot (homogenates and crude membranes) techniques. In rats treated with HgCl2, immunoblotting showed a significant decrease in the abundance of BTL in homogenates and plasma membranes from kidney and liver. BTL decrease of expression might reflect the grade of damage in renal tubule cells and in hepatocytes. Thus, BTL might be postulated as a new biomarker of tissue toxicity induced by mercury.

Pretreatment hepatoprotective effect of the marine fungus derived from sponge on hepatic toxicity induced by heavy metals in rats

The aim of this study was to evaluate the pretreatment hepatoprotective effect of the extract of marine-derived fungus Trichurus spiralis Hasselbr (TS) isolated from Hippospongia communis sponge on hepatotoxicity. Twenty-eight male Sprague-Dawley rats were divided into four groups (n = 7). Group I served as −ve control, group II served as the induced group receiving subcutaneously for seven days 0.25 mg heavy metal mixtures, group III received (i.p.) TS extract of dose 40 mg for seven days, and group IV served as the protected group pretreated with TS extract for seven days as a protection dose, and then treated with the heavy metal-mixture. The main pathological changes within the liver after heavy-metal mixtures administrations marked hepatic damage evidenced by foci of lobular necrosis with neutrophilic infiltration, adjacent to dysplastic hepatocytes. ALT and AST measurements show a significant increase in group II by 46.20% and 45.12%, respectively. Total protein, elevated by about 38.9% in induction group compared to the −ve control group, in contrast to albumin, decreased as a consequence of metal administration with significant elevation on bilirubin level. The results prove that TS extract possesses a hepatoprotective property due to its proven antioxidant and free-radical scavenging properties.

Syphilis and cirrhosis: a lethal combination in a XIX century individual identified from the medical schools collection at the university of Coimbra (Portugal)

Syphilis is a chronic infection that is categorized by a three-stage progression. The tertiary stage may affect bones and produce distinctive skull lesions called caries sicca. This paper aims to present an unusual case of syphilis associated with a diagnosis of cirrhosis, which was recorded as the cause of death in a 28-year-old female in 1899. The appearance and distribution of the lesions were compatible with acquired syphilis, as observed in the skull from the Medical Schools Collection of the University of Coimbra. However, the cause of death was recorded as "hypertrophic cirrhosis of the liver", this is a condition that is compatible with several liver disorders, including a primary liver disorder, such as cirrhosis provoked by alcoholism, infection of the liver by syphilis pathogens or by damage to the liver from the use of mercury compounds, which was the common treatment for syphilis at the time. This paper represents a contribution to the understanding of the natural evolution of syphilis.