The effect of thioacetamide on the activity and expression of cytosolic rat liver glutathione-S-transferase

In vivo hepatoprotective effect of Morinda elliptica stem extract against liver fibrosis induced by thioacetamide

Morinda elliptica L. (Rubiaceae) is a phytomedicinal herb, used to treat gastrointestinal complications in Peninsular Malaysia. The study evaluates the in vivo hepatoprotective activity of ethanolic extract of M. elliptica stem in thioacetamide (TAA) induced liver fibrosis in male Sprague Drawly rats. Thirty adult rats were divided into five groups of six rats each. Rats of the normal control group received intraperitoneal injections (i. p.) of vehicle 10% Tween-20, 5 ml/kg, and hepatotoxic group 200 mg/kg TAA three times per week respectively. Three supplementary groups were treated with TAA plus daily oral silymarin (50 mg/kg) or M. elliptica (250 or 500 mg/kg). After 8 weeks of treatment, all rats were sacrificed. Liver fibrosis was assessed by gross macroscopic and microscopic tissue analysis, histopathological, and biochemical analysis. The livers of the TAA treated group showed uniform coarse granules, hepatocytic necrosis with lymphocytes infiltration. Contrary, the livers of M. elliptica treated groups (250 and 500 mg/kg) were much smoother and the cell damage was much lesser. The livers of M. elliptica treated groups rats showed elevated activity of SOD and CAT with a significant decrease in MDA level at p < .0001. The level of liver damage parameters, that is, ALP, ALT, and AST, bilirubin, total protein, and albumin were restored to the normal comparable to silymarin. M. elliptica stem extract significantly promoted normal rat liver architecture with significant perfections in biochemical parameters. The molecular contents of M. elliptica with hepatoprotective influence could be discovered, is the future prospective of this study.

α-mangostin preserves hepatic microvascular architecture in fibrotic rats as shown by scanning electron microscopy of vascular corrosion casts

Liver fibrosis is a dynamic condition caused by wound-healing in which scar tissue replaces the liver parenchyma following repetitive injuries. It is hypothesized that α-mangostin (AM), the major constituent of the xanthone fraction in extracts of Garcinia mangostana L., may protect the hepatic microvascular bed from thioacetamide (TAA)-induced fibrosis. In the present study, rats were divided into 4 groups: Control rats received no treatment; TAA-treated rats received 150 mg/kg TAA 3 times per week intraperitoneally; AM-treated rats received 75 mg/kg AM twice per week intraperitoneally; and TAA+AM-treated rats received both TAA and AM as described above. Rat livers were processed either for light microscopy or for vascular corrosion casting after 30 and 60 days of treatment. Vascular parameters were measured by 3D morphometry analysis of scanning electron micrographs. AM attenuated hepatocellular injuries and delayed both periportal and pericentral fibrosis in the TAA-treated rats. The comparison of findings at day 30 and 60 showed that TAA-induced fibrotic changes were progressive in time, and that the beneficial effects of AM only became apparent after prolonged treatment. The livers of rats treated with both TAA and AM had less space surrounding the portal vessels, improved preservation of the hepatic microvascular pattern, and minimally altered sinusoidal patterns with few signs of terminal portal venule remodeling. AM therefore partially protected the liver against hepatotoxin-induced fibrosis and the associated microvascular changes. The mechanism of the protective effect of AM on the liver remains to be investigated.

Physiological and histopathological study on the influence of Ocimum basilicum leaves extract on thioacetamide-induced nephrotoxicity in male rats

Kidney disease is a worldwide public health problem that affects millions of people worldwide. Globally, many risk factors for kidney disease progression have been identified. The global prevalence of acute and chronic forms of kidney disease is rising continuously. Nephrotoxicity is defined as rapid dysfunction of kidney due to toxic influence of medications and chemicals. Nephroprotective agents are material that has potential to minimize the effects of nephrotoxic agents. Plants have been shown to be potential therapeutic agents to protect against nephrotoxicity. The purpose of the present study was to evaluate the nephroprotective effect of basil leaves extract against thioacetamide (TAA) in male rats. Experimental male rats were divided into four groups. Rats of the first group were served as controls. Rats of the second group were exposed to TAA. Rats of the third group were treated with basil leaves extract and TAA. Rats of the fourth group were treated with basil leaves extract. After the end of experimental duration (6 Weeks), rats of the second group showed significantly increases of serum creatinine, blood urea nitrogen and uric acid levels, while the levels of serum superoxide dismutase and glutathione were significantly decreased. Histopathologically, renal sections from rats treated with only TAA showed several alterations in the structure of most renal corpuscles including a degeneration of glomeruli and Bowman's capsules. Treatment with basil leaves extract improved the observed biochemical and histopathological changes induced by TAA intoxication. These new findings indicate that the extract of basil leaves represent protective roles on biochemical and histopathological changes induced by TAA toxicity due to its antioxidant activities.

The potential protective influence of flaxseed oil against renal toxicity induced by thioacetamide in rats

The present study was aimed to evaluate the influence of flaxseed oil on renal toxicity induced by thioacetamide in male rats. The animals were distributed into four groups. Rats of the first group were served as control. Rats of the second group were exposed to thioacetamide. Rats of the third group were treated with flaxseed oil and thioacetamide. Rats of the fourth group were treated with flaxseed oil. Significant increases of blood creatinine and uric acid were observed in TAA-treated rats after three weeks. In thioacetamide group, the levels of serum creatinine, blood urea nitrogen and uric acid were significantly elevated after six weeks. Histopathologically, the renal sections from thioacetamide-treated rats showed severe alterations in the structure of renal corpuscles including a degeneration of glomeruli and Bowman's capsules. Administration of flaxseed oil protects the observed biochemical and histopathological alterations induced by thioacetamide exposure. Hence, the results of this study suggest that flaxseed oil protects against thioacetamide-induced renal injury and the protective influence of flaxseed oil may be attributed to its antioxidant role.

SPARC gene deletion protects against toxic liver injury and is associated to an enhanced proliferative capacity and reduced oxidative stress response

SPARC, also known as osteonectin and BM-40, is a matricellular protein with a number of biological functions. Hepatic SPARC expression is induced in response to thioacetamide, bile-duct ligation, and acute injuries such as concanavalin A and lipopolysacharide (LPS)/D-galactosamine. We have previously demonstrated that the therapeutic inhibition of SPARC or SPARC gene deletion protected mice against liver injury. We investigated the mechanisms involved in the protective effect of SPARC inhibition in mice. We performed a proteome analysis of livers from SPARC^+/+ and SPARC^−/− mice chronically treated with thioacetamide. Catalase activity, carbonylation levels, oxidative stress response, and mitochondrial function were studied. Genomic analysis revealed that SPARC^−/− mice had an increased expression of cell proliferation genes. Proteins involved in detoxification of reactive oxygen species such as catalase, peroxirredoxine-1, and glutathione-S-transferase P1 and Mu1 were highly expressed as evidenced by proteome analysis; hepatic catalase activity was increased in SPARC^−/− mice. Oxidative stress response and carbonylation levels were lower in livers from SPARC^−/− mice. Hepatic mitochondria showed lower levels of nitrogen reactive species in the SPARC^−/− concanavalin A-treated mice. Mitochondrial morphology was preserved, and its complex activity reduced in SPARC^−/− mice. In conclusion, our data suggest that the protection associated with SPARC gene deletion may be partially due to a higher proliferative capacity of hepatocytes and an enhanced oxidative stress defense in SPARC^−/− mice after liver injury.

Protective effect of calycosin-7-O-β-D-glucopyranoside against oxidative stress of BRL-3A cells induced by thioacetamide

Background:

Calycosin-7-O-β-D-glucopyranoside (CG) is a natural isoflavone found in traditional Chinese medicines Astragali Radix (AR).

Objective:

Calycosin-7-O-β-D-glucopyranoside, an isoflavone isolated from AR, has been found to have potent antioxidantive effects. This study was designed to investigate whether CG prevents oxidative stress induced by thioacetamide (TAA).

Materials and Methods:

BRL-3A cells were pretreated with different concentrations of CG (10, 20, 40 mg/mL) for 12 h and then exposed to 0.18 mol/L TAA for 2 h. The cell viability were examined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium assay, total antioxidant capacity, malondialdehyde (MDA) and the activity of antioxidant enzymes, including catalase, glutathione peroxidase and superoxide dismutase were determined by microplate method. Reactive oxygen species (ROS) generation was quantified by the 2’,7’-dichlorofluorescin-diacetate method. Protein and mRNA expression of CYP2E1 were determined by western blotting and real-time PCR.

Results:

The cell oxidative stress was significantly increased after 2 h of TAA exposure. Pretreatment of BRL-3A cells with CG significantly increased the activities of antioxidant enzymes, scavenged ROS and reduced MDA production. CG decreased the expression of CYP2E1, and ultimately decreased TAA-induced BRL-3A cells oxidative stress.

Conclusions:

Calycosin-7-O-β-D-glucopyranoside has a protective effect against TAA-induced oxidative stress in BRL-3A cells, and that the underlying mechanism involves in scavenging of ROS and the modulating expression of CYP2E1.

PASS-predicted hepatoprotective activity of Caesalpinia sappan in thioacetamide-induced liver fibrosis in rats

The antifibrotic effects of traditional medicinal herb Caesalpinia sappan (CS) extract on liver fibrosis induced by thioacetamide (TAA) and the expression of transforming growth factor β1 (TGF-β1), α-smooth muscle actin (αSMA), and proliferating cell nuclear antigen (PCNA) in rats were studied. A computer-aided prediction of antioxidant and hepatoprotective activities was primarily performed with the Prediction Activity Spectra of the Substance (PASS) Program. Liver fibrosis was induced in male Sprague Dawley rats by TAA administration (0.03% w/v) in drinking water for a period of 12 weeks. Rats were divided into seven groups: control, TAA, Silymarin (SY), and CS 300 mg/kg body weight and 100 mg/kg groups. The effect of CS on liver fibrogenesis was determined by Masson's trichrome staining, immunohistochemical analysis, and western blotting. In vivo determination of hepatic antioxidant activities, cytochrome P450 2E1 (CYP2E1), and matrix metalloproteinases (MPPS) was employed. CS treatment had significantly increased hepatic antioxidant enzymes activity in the TAA-treated rats. Liver fibrosis was greatly alleviated in rats when treated with CS extract. CS treatment was noted to normalize the expression of TGF-β1, αSMA, PCNA, MMPs, and TIMP1 proteins. PASS-predicted plant activity could efficiently guide in selecting a promising pharmaceutical lead with high accuracy and required antioxidant and hepatoprotective properties.

Reversing effects of silybin on TAA-induced hepatic CYP3A dysfunction through PXR regulation

AIM

Silybin (SB), a major constituent of the milk thistle, has been used to treat several liver disorders. However, liver diseases were always accompanied by CYP450 dysfunction. This study was designed to explore the relationship between the hepatoprotective effect and CYP3A regulation of SB during thioacetamide (TAA)-induced rat liver injury.

METHODS

Serum biochemical analysis and histopathological study were taken to evaluate the hepatoprotectinve effect of SB. α-SMA were detected by immunohistochemical analysis and cytokine release in rat liver was determined by ELISA assay. CYP3A and PXR expression were determined by RT-PCR and Western blot analysis, and CYP3A activity was based on the midazolam 4-hydroxylation reaction. Also, siRNA transfection was induced in HepG2 cells to evaluate the effect of PXR on cytotoxicity and CYP3A4 dysregulation caused by TAA.

RESULTS

SB showed powerful hepatoprotective effects, and anti-inflammatory and anti-fibrosis effects, and reversed the loss of CYP3A and PXR in TAA-injured rat liver, and decreased PXR translocation into the cell nucleus. PXR silencing weakened the effect of SB on cytoprotection and CYP3A regulation.

CONCLUSIONS

PXR was a very important factor of CYP3A regulation and might be the target of SB in TAA-induced liver disease. Also, because of the potential interactions of SB and co-administered medicines, it might be necessary to adjust the dosage in the clinical medication of liver disease.

Effect of oral administration of ethanolic extract of Vitex negundo on thioacetamide-induced nephrotoxicity in rats

BACKGROUND

Oxidative stress due to abnormal induction of reactive oxygen species (ROS) molecules is believed to be involved in the etiology of many diseases. Evidences suggest that ROS is involved in nephrotoxicity through frequent exposure to industrial toxic agents such as thioacetamide (TAA). The current investigation was designed to explore the possible protective effects of the leaves of Vitex negundo(VN) extract against TAA-induced nephrotoxicity in rats.

METHODS

Twenty four Sprague Dawleyrats were divided into four groups: (A) Normal control, (B) TAA (0.03% w/v in drinking water), (C) VN100 (VN 100 mg/kg + TAA) and (D) VN300 (VN 300 mg/kg + TAA). Blood urea and serum creatinine levels were measured,supraoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) levels of renal tissue were assayed. Histopathological analysis together with the oxidative stress nicotinamide adenine dinucleotide phosphate (NADPH) oxidase p22phox in kidney sections were examined in all experimental groups.

RESULTS

Blood urea and serum creatinine levels were increased in TAA group as a result of the nephrotoxicity compared to the VN100 and VN300 groups where, the levels were significantly decreased (p < 0.05). Renal MDA level was significantly decreased (p < 0.05) in the VN-treated groups with increased CAT and SOD activities compared to the TAA group. Light microscopic examination of renal tissues stained by H&E stain and Masson's Trichrome for TAA-treated groups revealed severe histopathological changes, whereas specimens obtained from VN-treated groups showed only mild changes. These findings were supported by immunohistochemical results.

CONCLUSIONS

VN extract acts as a natural potent antioxidant to prevent ongoing TAA-induced nephrotoxicity in rats, both biochemically and morphologically.

Hepatoprotective Role of Ethanolic Extract of Vitex negundo in Thioacetamide-Induced Liver Fibrosis in Male Rats

The hepatoprotective activity of ethanolic extract from the leaves of Vitex negundo (VN) was conducted against thioacetamide- (TAA-) induced hepatic injury in Sprague Dawley rats. The therapeutic effect of the extract was investigated on adult male rats. Rats were divided into seven groups: control, TAA, Silymarin (SY), and VN high dose and low dose groups. Rats were administered with VN extract at two different doses, 100 mg/kg and 300 mg/kg body weight. After 12 weeks, the rats administered with VN showed a significantly lower liver to body weight ratio. Their abnormal levels of biochemical parameters and liver malondialdehyde were restored closer to the normal levels and were comparable to the levels in animals treated with the standard drug, SY. Gross necropsy and histopathological examination further confirmed the results. Progression of liver fibrosis induced by TAA in rats was intervened by VN extract administration, and these effects were similar to those administered with SY. This is the first report on hepatoprotective effect of VN against TAA-induced liver fibrosis.

Expression analysis of early response-related genes in rat liver epithelial cells exposed to thioacetamide in vitro

Thioacetamide (TA) is a potent hepatotoxicant known to affect liver metabolism, inhibit mRNA transport and induce immune suppression. The genetic mechanism underlining this biological toxic compound is well understood using microarray technology. Thus, we used high-throughput rat genome oligonucleotide microarrays containing approximately 22,000 genes to investigate the genetic components of TA-related cytotoxicity in WB-F344 rat liver epithelial (WB-F344) cells. We treated cells with TA (two concentrations over five time periods, ranging from 1 to 24 hr), isolated total RNA at 1, 3, 6, 12 and 24 hr following TA treatment and hybridized the RNA to microarrays. Clustering analysis distinguished two groups of genes, early (1 and 3 hr) and late (6, 12 and 24 hr) phase genes. In total, 2,129 and 2,348 differentially-expressed genes were identified following treatment with low and high concentrations of TA, respectively. A common set of 1,229 genes that were differentially expressed following treatment with both low (1,000 muM) and high (10,000 muM) concentrations of TA had similar expression patterns. Interestingly, 1,410 genes at the low concentration and 1,858 genes at the high concentration were differentially expressed in the early phases, suggesting that these genes associated with the early response to TA may be useful as early markers of hepatotoxicity.

Metabolism of thioamides by Ralstonia pickettii TA

Information on bacterial thioamide metabolism has focused on transformation of the antituberculosis drug ethionamide and related compounds by Mycobacterium tuberculosis. To study this metabolism more generally, a bacterium that grew using thioacetamide as the sole nitrogen source was isolated via enrichment culture. The bacterium was identified as Ralstonia pickettii and designated strain TA. Cells grown on thioacetamide also transformed other thioamide compounds. Transformation of the thioamides tested was dependent on oxygen. During thioamide degradation, sulfur was detected in the medium at the oxidation level of sulfite, further suggesting an oxygenase mechanism. R. pickettii TA did not grow on thiobenzamide as a nitrogen source, but resting cells converted thiobenzamide to benzamide, with thiobenzamide S-oxide and benzonitrile detected as intermediates. Thioacetamide S-oxide was detected as an intermediate during thioacetamide degradation, but the only accumulating metabolite of thioacetamide was identified as 3,5-dimethyl-1,2,4-thiadiazole, a compound shown to derive from spontaneous reaction of thioacetamide and oxygenated thioacetamide species. This dead-end metabolite accounted for only ca. 12% of the metabolized thioacetamide. Neither acetonitrile nor acetamide was detected during thioacetamide degradation, but R. pickettii grew on both compounds as nitrogen and carbon sources. It is proposed that R. pickettii TA degrades thioamides via a mechanism involving consecutive oxygenations of the thioamide sulfur atom.

Reducing the expression of glutathione transferase D mRNA in Drosophila melanogaster exposed to phenol and aniline

Phenol and aniline are toxic to animals. The purpose of the present study was to examine the expression of glutathione transferase D mRNA in fruit flies altered by long-term exposure to phenol and aniline. Changes in the amount of mRNA were measured by a semiquantitative reverse-transcription polymerase chain reaction assay. The level of each glutathione transferase D mRNA expressed in the phenol-treated and aniline-treated strains of adult fruit flies differed after chemical treatment. Aniline was more potent than phenol in suppressing the expression of cytosolic glutathione transferase D mRNA. Aniline reduced the level of glutathione transferase mRNA expressed in the aniline-treated strain to less than a 0.5 fraction as compared to that measured in the wild-type strain. But phenol was only able to suppress the GstD7 and GstD4 mRNAs expressed in the phenol-treated strain. Neither aniline nor phenol reduced the expression of microsomal glutathione transferase mRNA in fruit flies.

Thioacetamide differentially affects the expression and activity of glutathione-S-transferase in the liver of Wistar rats

Glutathione-S-transferase (GST) is a family of enzymes involved in the detoxification of toxic and carcinogenic compounds. In the present study, the effect of thioacetamide (TA), a hepatotoxic and hepatocarcinogenic compound, on the activity and expression of GST of Wistar female rats was tested. Animals were treated with a single dose of TA (250 mg/kg) for 12, 24, 48 and 72 hours. GST activity toward the broad substrate 1-chloro-2,4-dinitrobenzene was enhanced by TA. The protein level of the GST classes alpha and mu as well as the mRNA level of several GST subunits were also positively affected by the TA treatment. Female Wistar rats of the same age but from two other different colonies had their GST activity either inhibited or not affected by TA. The basal mRNA level of class alpha and class mu GST was also tested in female Wistar rats obtained from five different sources. Differences in the basal level of class alpha mRNA were observed in rats from at least three different sources, while class mu mRNA level was distinct in two groups of animals.

Stress-dependent regulation of the gene encoding gamma-glutamylcysteine synthetase from the fission yeast

Glutathione (GSH), an important antioxidant involved in stress response, is synthesized in two sequential reactions. Gamma-glutamylcysteine synthetase (GCS) catalyzes the first step in GSH biosynthesis, which is usually known to be rate-limiting. In this work, regulatory patterns of the GCS gene from the fission yeast Schizosaccharomyces pombe have been investigated. The 607 bp upstream region from the translational initiation point was amplified by the two synthetic primers. The amplified DNA was ligated into the BamHI/HindIII site of the shuttle vector YEp367R to generate the fusion plasmid pUGCS101. The GCS-lacZ fusion gene construct was confirmed by restriction mapping and nucleotide sequencing. The GCS-lacZ fusion gene was used to study effects of various agents on the transcription of the GCS gene. The synthesis of beta-galactosidase from the fusion plasmid pUGCS101 was enhanced by metals, oxidative and nitrosative stresses, and glutathione-depleting agents. The GCS mRNA level in the wildtype S. pombe cells was significantly elevated by the treatment with sodium nitroprusside or menadione, which was detected by RT-PCR. It was also induced by low concentrations of glucose and sucrose. These results suggest that the expression of S. pombe GCS gene is regulated by various stresses and carbon sources.

Differentially expressed genes in the liver of thioacetamide treated rats

Thioacetamide is a hepatotoxic and hepatocarcinogenic compound that affects liver metabolism, inhibits mRNA transport and induces enlargement of the nucleolus. To investigate the effect of thioacetamide at the molecular level, differential display RT-PCR was conducted. Analysis of nineteen differentially expressed genes demonstrated that ten cDNAs have their expression inhibited while the other nine were positively affected by thioacetamide. Two of the cDNAs were homologous to known genes-TAP and ankyrin-binding glycoprotein-1, two corresponded to repetitive sequences and seven were homologous to expressed sequence tags. The differential expression of some of the isolated cDNAs was confirmed by northern hybridization. It is proposed that since the product of TAP is involved in mRNA transport, thioacetamide inhibition of TAP expression might, at least partially, explain the thioacetamide-induced swelling of the nucleolus.