Correlation of changes in serum analytes and hepatic histopathology in rats exposed to carbon tetrachloride

Gestation Food Restriction and Refeeding Compensate Maternal Energy Status and Alleviate Metabolic Consequences in Juvenile Offspring in a Rabbit Model

Nutritional status during gestation can influence mother and offspring metabolism. Undernutrition in pregnancy affects women in both western and developing countries, and it is associated with a high prevalence of chronic diseases in later life. The present work was conducted in the rabbit model, as a longitudinal study, to examine the effect of food restriction during early and mid-gestation, and re-feeding ad libitum until the end of pregnancy on metabolic status and body reserves of mother and, its association with development and metabolism of fetuses and female offspring to the juvenile stage. Little changes in live body weight (LBW), compensatory feed intake, similar body reserves, and metabolism were observed in dams. Placenta biometry and efficiency were slightly affected, but fetal BW and phenotype were not modified. However, hyperinsulinemia, insulin resistance, and hypertriglyceridemia were demonstrated in pre-term fetuses. In the juvenile period, these changes were not evidenced, and a similar pattern of growth and serum metabolic parameters in offspring of food-restricted mothers were found, except in serum aminotransferases levels, which increased. These were associated with higher liver fibrosis. Maternal food restriction in the early and mid-pregnancy followed by re-feeding in our rabbit model established a compensatory energy status in dams and alleviated potential long-term consequences in growth and metabolism in the offspring, even if fetal metabolism was altered.

Acute, sub-acute, sub-chronic and chronic toxicity studies of four important Nigerian ethnomedicinal plants in rats

Background

Azadirachta indica,Khaya senegalensis,Anogeissus leiocarpusandTamarindus indicaare important ethnomedicinal plants used for health mitigation since the history of mankind. They are used discretionarily in folkloric medicine on the premise that they are natural products devoid of synthetic preservatives. However, nature endows plants with metabolites for warding off potential attacks from animals and the environment. Some of these metabolites are responsible for toxicity of some plants. Furthermore, drug-induced liver injuries and nephrotoxicity are the leading causes of pharmaceutical attrition of promising drug candidates in clinical trials. Thus, we aimed to evaluate the safety of four ethnomedicinal plants in short-, medium- and long-term usage.

Methods

Rats dosed once with 5000 mg/kg extracts of each of these plants served as acute study (AS) while rats dosed daily with 2000 mg/kg for 2, 12 and 14 weeks served as sub-acute (SAS), sub-chronic (SCS) and chronic (CS) studies, respectively. Rats administered distilled water served as the negative control (NC).

Results

A. leiocarpusandT. indicasignificantly reduced percentage weight gain in the SCS compared to the NC.A. leiocarpussignificantly (P< 0.05) increased transaminases and alkaline phosphatase in the AS only; and total protein (TP) in the AS, SAS, SCS and CS compared to the NC.K. senegalensissignificantly (P< 0.05) increased alanine aminotransferase but significantly (P< 0.05) decreased TP in the AS only compared to the NC. However,A. indica and T. indicasignificantly (P< 0.05) increased globulin and aspartate transaminase in the CS only. WhereasA. leiocarpusandK. senegalensissignificantly (P< 0.05) increased urea and creatinine in the AS than SAS, SCS and CS; Na+and K+were significantly higher in the SCS and CS studies compared to the NC. The histological lesions seen ranged from cellular degeneration, congestion, fibrosis to necrosis.

Conclusion

Thus, nonlethal, reversible toxic insults occur in short-term usage (AS); while, insidious lethal toxic effects occur in medium-term (SAS) and long-term usage (SCS and CS). The ability of these plant to maintain adequate hematological parameters, bodyweight and absence of mortality may explain free usage of preparations made from these plants in folkloric medicine.

The elderly as a sensitive population in environmental exposures: making the case

The US population is aging. CDC has estimated that 20% of all Americans will be 65 or older by the year 2030. As a part of the aging process, the body gradually deteriorates and physiologic and metabolic limitations arise. Changes that occur in organ anatomy and function present challenges for dealing with environmental stressors of all kinds, ranging from temperature regulation to drug metabolism and excretion. The elderly are not just older adults, but rather are individuals with unique challenges and different medical needs than younger adults. The ability of the body to respond to physiological challenge presented by environmental chemicals is dependent upon the health of the organ systems that eliminate those substances from the body. Any compromise in the function of those organ systems may result in a decrease in the body's ability to protect itself from the adverse effects of xenobiotics. To investigate this issue, we performed an organ system-by-organ system review of the effects of human aging and the implications for such aging on susceptibility to drugs and xenobiotics. Birnbaum (1991) reported almost 20 years ago that it was clear that the pharmacokinetic behavior of environmental chemicals is, in many cases, altered during aging. Yet, to date, there is a paucity of data regarding recorded effects of environmental chemicals on elderly individuals. As a result, we have to rely on what is known about the effects of aging and the existing data regarding the metabolism, excretion, and adverse effects of prescription medications in that population to determine whether the elderly might be at greater risk when exposed to environmental substances. With increasing life expectancy, more and more people will confront the problems associated with advancing years. Moreover, although proper diet and exercise may lessen the immediate severity of some aspects of aging, the process will continue to gradually degrade the ability to cope with a variety of injuries and diseases. Thus, the adverse effects of long-term, low-level exposure to environmental substances will have a longer time to be manifested in a physiologically weakened elderly population. When such exposures are coupled with concurrent exposure to prescription medications, the effects could be devastating. Public health officials must be knowledgeable about the sensitivity of the growing elderly population, and ensure that the use of health guidance values (HGVs) for environmental contaminants and other substances give consideration to this physiologically compromised segment of the population.

The antioxidant activity of chondroitin-4-sulphate, in carbon tetrachloride-induced acute hepatitis in mice, involves NF-kappaB and caspase activation

BACKGROUND AND PURPOSE

Reactive oxygen species (ROC) are the main causes of carbon tetrachloride (CCl4)-induced acute liver injury. Chondroitin-4-sulphate (C4S) is known to inhibit lipid peroxidation through antioxidant mechanisms. Activation of nuclear factor (NF)-kappaB and caspases may strongly intensify inflammation and cell damage, in addition to that directly exerted by ROS. We investigated whether treatment with C4S, besides exerting antioxidant activity, was able to modulate NF-kappaB and apoptosis activation in CCl4-induced liver injury in mice.

EXPERIMENTAL APPROACH

Acute hepatitis was induced in mice by an i.p. injection of CCl(4). Varying doses of C4S were administered i.p. 1 h before, 6 and 12 h after CCl4 injection. 24 h after CCl4 injection, the mice were killed for biochemical and histological analysis.

KEY RESULTS

CCl4 injection produced: marked elevation of alanine aminotransferase and aspartate aminotransferase; hepatic membrane lipid peroxidation, assayed by 8-isoprostane levels; and depletion of reduced glutathione and superoxide dismutase. CCl4 also decreased NF-kappaB translocation and IkBalpha, and increased gene expression of mRNA and protein of metalloproteases (MMP)-2 and -9, and of pro- and cleaved forms of caspases-3 and -7. There was also increased liver polymorphonuclear infiltration, evaluated by elastase assay, and hepatic cell disruption.C4S treatment inhibited lipid peroxidation; blocked NF-kappaB activation and IkBalpha protein loss; decreased mRNA and proteins for MMPs and caspases; restored endogenous antioxidants; limited hepatic polymorphonuclear accumulation and tissue damage.

CONCLUSIONS AND IMPLICATIONS

As antioxidants may inhibit NF-kappaB and caspase activation, we hypothesize that treatment with C4S was able to inhibit NF-kappaB and apoptosis activation in hepatic injury.

Administration of hyaluronic acid and chondroitin-4-sulfate limits endogenous antioxidant depletion and reduces cell damage in experimental acute pancreatitis

Several reports have described a loss of endogenous antioxidants and molecular oxidative damage during acute pancreatitis. Since hyaluronic acid and chondroitin-4-sulfate possess antioxidant properties, the effect of the administration of these glycosaminoglycans in a cerulein-induced acute pancreatitis in rats was investigated. Cerulein administration produced pancreatic edema and a marked increase in serum lipase and amylase activity; induced a severe depletion of reduced glutathione, catalase, and superoxide dismutase levels; primed lipid peroxidation; and promoted neutrophil intervention. Intraperitoneal pretreatment of rats with hyaluronic acid or chondroitin-4-sulfate or with both compounds ameliorated pancreatic cell conditions; restored the endogenous antioxidants reduced glutathione, catalase and superoxide dismutase; limited cell membrane peroxidation; and reduced neutrophil activation. Our data confirm the antioxidant activity of these 2 glycosaminoglycans.

Hyaluronic acid and chondroitin-4-sulphate treatment reduces damage in carbon tetrachloride-induced acute rat liver injury

Oxidative stress is involved in the pathogenesis of chemically mediated liver injury. Since glycosaminoglycans possess antioxidant activity, the aim of this work was to assess the protective effects of hyaluronic acid and chondroitin-4-sulphate treatment in a model of carbon tetrachloride-induced liver injury. Liver damage was induced in male rats by an intraperitoneal injection of carbon tetrachloride (1 ml/kg in vegetal oil). Serum alanine aminotransferase and aspartate aminotransferase, hepatic malondialdehyde, plasma TNF-alpha, hepatic reduced glutathione and catalase, and myeloperoxidase, an index of polymorphonuclear infiltration in the jeopardised hepatic tissue, were evaluated 24 h after carbon tetrachloride administration. Carbon tetrachloride produced a marked increase in serum alanine aminotransferase and aspartate aminotransferase activities, primed lipid peroxidation, enhanced plasma TNF-alpha levels, induced a severe depletion of reduced glutathione and catalase, and promoted neutrophil accumulation. Intraperitoneal treatment of rats with hyaluronic acid (25 mg/kg) or chondroitin-4-sulphate (25 mg/kg) failed to exert any effect in the considered parameter, while the combination treatment with both glycosaminoglycans (12,5 + 12,5 mg/kg) decreased the serum levels of alanine aminotransferase and aspartate aminotransferase, inhibited lipid peroxidation by reducing hepatic malondialdehyde, reduced plasma TNF-alpha, restored the endogenous antioxidants, and finally decreased myeloperoxidase activity. These results suggest that hyaluronic acid and chondroitin-4-sulphate possess a different antioxidant mechanism and consequently the combined administration of both glycosaminoglycans exerts a synergistic effect with respect to the single treatment.

Reduction of carbon tetrachloride-induced rat liver injury by IRFI 042, a novel dual vitamin E-like antioxidant

Carbon tetrachloride (CCl4 )-induced hepatotoxicity is likely the result of a CCl4 -induced free radical production which causes membrane lipid peroxidation and activation of transcription factors regulating both the TNF-alpha gene and the early-immediate genes involved in tissue regeneration. IRFI 042 is a novel vitamin E-like compound having a masked sulphydryl group in the aliphatic side chain. We studied the effect of IRFI 042 on CCl4 -induced liver injury. Liver damage was induced in male rats by an intraperitoneal injection of CCl4 (1 ml/kg in vegetal oil). Serum alanine aminotransferase (ALT) activity, liver malondialdehyde (MAL), hydroxyl radical formation (OH*), calculated indirectly by a trapping agent, hepatic reduced glutathione (GSH) concentration, plasma TNF-alpha, liver histology and hepatic mRNA levels for TNF-alpha were evaluated 48 h after CCl4 administration. Hepatic vitamin E (VE) levels were evaluated, in a separate group of animals, 2 h after CCl4 injection. A control group with vitamin E (100 mg/kg) was also treated in order to evaluate the differences versus the analogue treated groups. Intraperitoneal injection of carbon tetrachloride produced a marked increase in serum ALT activity (CCl4 = 404.61 +/- 10.33 U/L; Controls= 28.54 +/- 4.25 U/L), liver MAL (CCl4 = 0.67 +/- 0.16 nmol/mg protein; Controls= 0.13 +/- 0.06 nmol/mg protein), OH(7) levels assayed as 2,3-DHBA (CCl4 = 8.73 +/- 1.46 microM; Controls= 0.45 +/- 0.15 microM) and 2,5-DHBA (CCl4 = 24.61 +/- 3.32 microM; Controls= 2.75 +/- 0.93 microM), induced a severe depletion of GSH (CCl4 = 3.26 +/- 1.85 micromol/g protein; Controls= 17.82 +/- 3.13 micromol/g protein) and a marked decrease in VE levels (CCl4 = 5.67 +/- 1.22 nmol/g tissue; Controls= 13.47 +/- 3.21 nmol/g tissue), caused liver necrosis, increased plasma TNF-alpha levels (CCl4 = 57.36 +/- 13.24 IU/ml; Controls= 7.26 +/- 2.31 IU/ml) and enhanced hepatic mRNA for TNF-alpha (CCl4 = 19.22 +/- 4.38 a.u.; Controls= 0.76 +/- 0.36 a.u.). IRFI 042 (100 mg/kg, 30 min after CCl4 injection) blunted liver MAL (0.32 +/- 0.17 nmol/mg protein), decreased the serum levels of ALT (128.71 +/- 13.23 U/L), and restored the hepatic concentrations of VE (9.52 +/- 3.21 nmol/g tissue), inhibited OH* production (2,3-DHBA= 3.54 +/- 1.31 microM; 2,5-DHBA= 7.37 +/- 2.46 microM), restored the endogenous antioxidant GSH (12.77 +/- 3.73 mmol/g protein) and improved histology. Furthermore IRFI 042 treatment suppressed plasma TNF-alpha concentrations (31.47 +/- 18.25 IU/ml) and hepatic TNF-alpha mRNA levels (11.65 +/- 3.21 a.u.). The acute treatment with vitamin E failed to exert any protective effect against CCl4 -induced hepatotoxicity. These investigations suggest that IRFI 042 treatment may be of benefit during free radical-mediated liver injury.

Evaluation of urinary biomarkers for radical-induced liver damage in rats treated with carbon tetrachloride

Carbon tetrachloride (CCl4) is a model compound for inducing free radical damage in liver. In this study 10 biomarkers in rats treated i.p. with three different single doses of CCl4 (0.25, 0.50, and 1.00 ml/kg body wt) were measured dose and time dependently and compared to evaluate these urinary products as noninvasive biomarkers for radical damage. Eight degradation products of lipid peroxides, namely, formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, hexanal, and malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OH-dG) and coproporphyrin III were measured in this study. As general measures of toxicity, several clinical chemical parameters (n = 12) and histopathological damage were determined. A dose-dependent increase in both the clinical parameters and the lipid degradation products was found. Increases in lipid degradation products were statistically significant at doses of 0.5 and 1 ml/kg CCl4. An increase in these products was already found in the first 12 h after exposure. At the lowest dose, 0.25 ml/kg CCl4, acetaldehyde and propanal already showed a statistically significant increase as well. No change in the urinary levels of 8-OH-dG could be found in this study and a decrease in the urinary excretion of coproporphyrin III was found. It is concluded that 8-OH-dG and coproporphyrin III are not useful biomarkers for radical damage induced by CCl4. Lipid degradation products, however, are promising noninvasive biomarkers for in vivo radical damage, although the precise specificity of these biomarkers for damage induced by radicals needs to be further investigated.

Time course of hepatic injury and recovery following coadministration of carbon tetrachloride and trichloroethylene in Fischer-344 rats

Simultaneous administration of trichloroethylene (TCE), at an oral dose of 0.5 ml/kg, resulted in a marked potentiation of liver injury caused by an oral dose of carbon tetrachloride (CCl4, 0.05 ml/kg). Hepatic glutathione levels were depressed at 24 hr only in the rats given TCE and CCl4. Using serum enzyme (ALT and SDH) as indicators of hepatotoxicity, potentiation of CCl4-injury was most apparent at 24 hr. Upon histological examination of H&E stained liver sections, the differences between livers obtained from TCE and CCl4-treated rats versus CCl4-treated rats were most apparent at later time points (48 and 72 hr). At 48 hr after CCl4, livers showed a distinctive and uniform pattern of injury with regeneration features predominating over necrosis. At this time, livers from TCE and CCl4-treated rats were characterized by extensive zone 3 coagulative necrosis. Inflammatory infiltrations were less prominent. At 72 hr, morphological features of livers from TCE and CCl4 rats were similar to those from rats given CCl4 alone at 48 hr. From the results obtained, it appears that the regenerative activity of the liver may be delayed in rats simultaneously administered TCE and CCl4 as compared to rats administered only CCl4.