Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The organ distribution and toxicity of p-DCB were compared in rats after either inhalation or oral administration. Male F344 rats were exposed to 500 or 125 ppm for 24 hr in a whole body inhalation chamber (H and L groups) or received a single dose of 300 mg/kg by gavage (PO group). The concentrations of p-DCB in the serum, liver, kidney and fatty tissues were measured by gas chromatography at intervals during and up to 24 hr after the treatment. Peak serum values for the L and H groups were lower than in the PO animals, but the organ/serum distribution ratios of p-DCB tended to be higher, in some cases markedly, in rats receiving the inhalation treatment. Significant increases in the levels of blood urea nitrogen, hepatic glutamic oxaloacetic transaminase and glutamic pyruvate transaminase and significant decreases in the levels of serum total cholesterol were observed only in the inhalation groups. Microscopically, the appearance of numerous eosinophilic droplets, together with swelling and desquamation of the proximal tubular epithelium of the kidney was especially noteworthy in H and L p-DCB treated groups. Thus, both biochemical and histopathological abnormalities induced by p-DCB were more pronounced in rats administered the compound by the inhalation route.
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PMID:Comparison of the toxicity of p-dichlorobenzene (p-DCB) administered to male F344 rats orally or by the inhalation route. 264 63

p-Dichlorobenzene (p-DCB) is widely used as a moth repellent and a space deodorant. In mice pretreated with DL-buthionine sulfoximine (BSO; 2 mmol/kg or higher doses, i.p.), an inhibitor of glutathione (GSH) synthesis, administration of p-DCB (100-400 mg/kg, p.o.) resulted in dose-dependent hepatotoxicity as judged by increased serum alanine aminotransferase (ALT) activities and liver calcium concentrations and by histological examination of the liver, p-DCB alone (up to 1200 mg/kg) resulted in no hepatotoxicity. Administration of GSH monoethyl ester, which is known as a useful means for increasing organ GSH levels, protected against the hepatotoxicity caused by p-DCB in combination with BSO. Treatment with inhibitors of hepatic cytochrome P-450-dependent monooxygenases, carbon disulfide, metyrapone and piperonyl butoxide also prevented the hepatotoxicity. These results suggest that p-DCB is activated by a cytochrome P-450-dependent metabolic reaction and that the hepatotoxicity is caused by inadequate rates of detoxification of the resulting metabolite in mice depleted of hepatic GSH by BSO treatment. The liver injury was preceded by an extensive depletion of hepatic GSH but not accompanied by significant changes in hepatic contents of lipid peroxides and protein thiols.
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PMID:p-Dichlorobenzene-induced hepatotoxicity in mice depleted of glutathione by treatment with buthionine sulfoximine. 780 30

This study examined the contribution of biotransformation by the mixed function oxidase system on hepatic and renal toxicity of 1,2-dichlorobenzene (1,2-DCB). Male Fischer 344 (F344) rats (190-250 g) were pretreated with phenobarbital (PB), beta-naphthoflavone (BNF), pyridine (PYR), piperonyl butoxide (PiBx) or vehicle prior to the administration of 2 or 3 mmol/kg of 1,2-DCB. Pair-fed control animals were treated with corn oil, (1 ml/kg). Plasma alanine amino-transaminase (ALT/GPT) was increased in a dose-dependent manner by 1,2-DCB. Pretreatment with PB, BNF or PB pretreatment prior to 1,2-DCB administration increased hepatic toxicity within 24 h. Toxicity was characterized by increased ALT/GPT activity and increased liver weight. Acute administration of 1,2-DCB produced renal alterations within 24 h. Renal toxicity was characterized by altered blood urea nitrogen (BUN) concentration and decreased renal cortical slice accumulation of p-aminohippurate (PAH) 24 h after injection of 3 mmol/kg 1,2-DCB. Pretreatment with PB, BNF or PYR increased the renal toxicity of 2 and 3 mmol/kg 1,2-DCB. Conversely, pretreatment with PiBx to inhibit P450 activity slightly decreased the hepatic and renal toxicity of 1,2-DCB. These results establish that the kidney was a target organ for 1,2-DCB toxicity and that the proximal tubule was a site of damage. Additionally, these studies indicate induction of P450 isozymes increased the hepatic and renal toxicity of 1,2-DCB. Further studies are needed to examine the specific role of P450 in generation of toxicity.
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PMID:Modification of P450 activity and its effect on 1,2-dichlorobenzene toxicity in Fischer 344 rats. 831 47

The hepatotoxicity of 1,2-dichlorobenzene (1,2-DCB) was studied in Fischer-344 (F344) rats administered methyl palmitate (MP) to inhibit Kupffer cell function or superoxide dismutase (conjugated to polyethylene glycol, i.e., PEG-SOD) to scavenge superoxide anions. In rats not pretreated with phenobarbital (PB), administration of either MP or PEG-SOD dramatically reduced the severity of 1,2-DCB-induced liver injury. Both agents reduced the elevations in plasma ALT activities by 80%. PEG-SOD conferred protection when administered 2 hr before or 2 hr after 1,2-DCB. Light microscopic examination of H & E-stained liver sections confirmed that the reductions in plasma ALT activities reflected protection from hepatocellular injury. Interestingly, MP did not protect against 1,2-DCB-induced hepatotoxicity in PB-pretreated rats. The degree of inhibition of 1,2-DCB hepatotoxicity by PEG-SOD in PB-pretreated animals was also less than that in normal rats and was not significantly different. The lack of a significant inhibition of the PB-potentiated hepatotoxicity by both PEG-SOD and MP suggests that reactive oxygen species released from a nonparenchymal source were not as crucial to the 1,2-DCB hepatotoxicity in the PB-pretreated rats as in the normal rats. Our results using both MP and PEG-SOD support the hypothesis that reactive oxygen species released from Kupffer cells play a major role in the progression of 1,2-DCB hepatotoxicity in the F344 rat.
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PMID:Modulation of 1,2-dichlorobenzene hepatotoxicity in the Fischer-344 rat by a scavenger of superoxide anions and an inhibitor of Kupffer cells. 838 65

The acute hepatotoxicity of isomers of dichlorobenzene (o-, m-, and p-DCB) was compared in livers of male B6C3F1 mice at different time points after a single intragastric administration. The highest doses of o-, m-, and p-DCB administered, 300, 300, and 1800 mg/kg, respectively, are below the lethal range. Acute hepatic injury was assessed by serum alanine aminotransferase (ALT) activity and hepatic histology. Hepatocyte replication was estimated by means of immunohistochemical demonstration of BrdU-labeled cells. Both o-DCB and m-DCB at a dose of 300 mg/kg produced significant elevations of liver weight and ALT activity as well as extensive liver cell necrosis. In contrast, p-DCB at a highest dose of 1800 mg/kg induced slight hepatocyte injury. Dose-response studies indicated that the rank order for acute hepatotoxicity of the isomers was m-DCB > o-DCB > or = p-DCB. However, p-DCB induced hepatocyte cell proliferation in spite of the lack of manifest hepatotoxicity. In contrast, increases of cell proliferation due to o- or m-DCB exposure occurred only after dosages that caused hepatic injury. These data suggest the hepatocyte proliferation induced by o- or m-DCB is compensatory regeneration while that induced by p-DCB is a response to mitogenic stimulation.
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PMID:Isomer-specific acute toxicity and cell proliferation in livers of B6C3F1 mice exposed to dichlorobenzene. 866 52

Fischer 344 (F344) rats are reportedly 75-fold more sensitive than Sprague Dawley (S-D) rats to 1,2-dichlorobenzene (o-DCB) hepatotoxicity. Lethality studies were conducted since no information was available regarding the ultimate consequence of this sensitivity in terms of animal survival in the two strains. LD50S for o-DCB (1.66 ml/kg and 1.76 ml/kg in male F344 and S-D rats, respectively) did not differ. Several studies have shown the importance of tissue repair on animal survival following exposure to toxic chemicals. The objective of this study was to investigate if differential rates of cell division and tissue repair might explain the lack of difference in LD50 dose between the two strains despite higher hepatotoxic injury in F344 rats. Age-matched male S-D and F344 rats were administered o-DCB (0.2, 0.6, 1.2 ml/kg, i.p.); injury and tissue repair occurring as two dynamic but opposing events were measured over time. Liver injury was assessed by measuring plasma alanine aminotransferase (ALT) and sorbitol dehydrogenase (SDH) activities and by liver histopathology. Higher plasma ALT elevations were observed in F344 rats following administration of 0.2 and 0.6 ml o-DCB/kg. Using SDH as a marker of liver injury, the strain difference was evident only at 0.2 ml o-DCB/kg. Liver regeneration was estimated by 3H-thymidine incorporation into hepatonuclear DNA and via proliferating cell nuclear antigen (PCNA) assay. Prompt and significantly higher hepatocellular regeneration beginning at 36 h was evident in F344 rats following administration of 0.2 and 0.6 ml o-DCB/kg. The significantly higher depletion of hepatic glycogen observed in F344 rats following administration of 0.2 and 0.6 ml o-DCB/kg occurred without significant changes in plasma glucose and is consistent with highly stimulated tissue repair seen in these rats at the corresponding doses. However, increasing the dose further to 1.2 ml o-DCB/kg results in a delayed (S-phase synthesis begins at 48 h) and diminished response to o-DCB. These findings suggest that a significantly higher rate of tissue repair in F344 rats helps them overcome higher liver injury inflicted by o-DCB. This differential in tissue repair in the two strains may play a vital role in equalizing the ultimate outcome of toxicity in the two strains.
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PMID:Strain differences in tissue repair response to 1,2-dichlorobenzene. 889 17

Although, hepatotoxic injury of 1,2-dichlorobenzene (o-DCB) is greater in Fischer 344 (F344) as compared to Sprague-Dawley (S-D) rats, this interstrain difference does not transcend into any difference in lethal effects of o-DCB. Interstrain difference in compensatory tissue repair has been suggested as the underlying mechanism for the lack of strain differences in lethality (S.G. Kulkarni, H. Duong, R. Gomila, and H.M. Mehendale, Strain differences in tissue repair response to 1,2-dichlorobenzene. Archives of Toxicology 1996; 70: 714-723). If higher tissue repair in F344 rats compensates for more severe liver injury, then antimitotic intervention after infliction of o-DCB-induced liver injury should lead to lethality in F344 rats. Colchicine (CLC, 1 mg/kg) functions as an effective antimitotic agent and does not cause any side effects apart from suppressing cellular proliferation. Two groups of male F344 rats (160-190 g) received a single dose of 0.6 ml o-DCB/kg: 30 h later one group of rats received CLC (1 mg/kg; i.p.) and the other received distilled water (1 ml/kg; i.p.). Liver injury was assessed by measuring plasma ALT and SDH activity, liver histopathology, and liver regeneration was estimated by [3H]thymidine incorporation into hepatonuclear DNA and proliferating cell nuclear antigen (PCNA) assay in both groups. Similar liver injury was noted in both the o-DCB + vehicle and o-DCB + CLC treated F344 rats at 36 h indicating that CLC does not interfere with the uptake, bioactivation and causation of injury by o-DCB. S-phase synthesis which occurred at 36 h in the o-DCB + vehicle group was blocked in the o-DCB + CLC group. CLC administration 6 h prior to S-phase stimulation selectively abolished S-phase stimulation at 36 h, and led to 50% lethality. Since the effect of CLC antimitosis was transient, S-phase synthesis occurring at 48 h was not blocked and was sustained up to 72 h thereby allowing the other 50% of rats to overcome liver injury induced by o-DCB and survive the lethal outcome. These findings suggest that a significantly higher rate of compensatory tissue repair in F344 rats enables them to overcome more severe liver injury inflicted by o-DCB.
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PMID:Antimitotic intervention with colchicine alters the outcome of o-DCB-induced hepatotoxicity in Fischer 344 rats. 918 94

1,2-Dichlorobenzene (1,2-DCB) is a potent hepatotoxicant in male Fischer 344 (F344) rats and previous studies have suggested that reactive oxygen species may play a role in the development of hepatotoxicity. Since reactive oxygen species can damage lipid membranes, this study was conducted to determine the extent of lipid peroxidation after administration of 1,2-DCB by immuno-histochemical analysis of 4-hydroxynonenal (4-HNE) protein adduct formation in liver and conjugated diene formation in liver and serum. The contribution of Kupffer cells to the lipid peroxidation was also investigated. Male F344 rats were administered 1,2-DCB (3.6 mmol/kg i.p. in corn oil) and killed at selected times between 3 and 48 h. Time course studies revealed the greatest abundance of 4-HNE protein adducts in the centrilobular regions of the liver 24 h after 1,2-DCB administration, with much lower levels at 16 h. Adducts were present in necrotic and vacuolized centrilobular hepatocytes of 1,2-DCB treated rats but not in livers of controls. Further, conjugated dienes were significantly increased in liver and serum 16 and 24 h after 1,2-DCB administration, peaking at 24 h. These data correlated with hepatocellular injury, determined by serum alanine aminotransferase activity and histopathological evaluation, which was markedly elevated within 16 h and peaked at 24 h. When rats were pretreated with gadolinium chloride (GdCl3; 10 mg/kg i.v. 24 h prior to 1,2-DCB), an inhibitor of Kupffer cells, hepatotoxicity was decreased by 89 and 86%, at 16 and 24 h, respectively. Conjugated diene concentrations were decreased to control values at these times after 1,2-DCB administration. Moreover, no 4-HNE protein adducts were detected in livers of 1,2-DCB-treated rats pretreated with GdCl3. Finally, Kupffer cells isolated from 1,2-DCB-treated rats produced significantly more superoxide anion than Kupffer cells isolated from vehicle controls. These data, along with previous findings, suggest that lipid peroxidation associated with 1,2-DCB is mediated in part by Kupffer cell-derived reactive oxygen species.
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PMID:1,2-Dichlorobenzene-induced lipid peroxidation in male Fischer 344 rats is Kupffer cell dependent. 1004 41

Subchronic inhalation toxicity of p-dichlorobenzene (p-DCB) was examined by exposing BDF1 mice and F344 rats of both sexes (6 h/d and 5 d/wk) to inhalation of 25, 55, 120, 270 or 600 ppm (v/v) p-DCB vapor for 13 wk. The exposure to p-DCB vapor retarded the growth rate in the male mice, and induced hepatotoxicity in the mice and rats of both sexes and renal and hematological toxicity in the male rats. Hepatotoxicity was characterized by increased liver weight, hepatocellular hypertrophy, and increased serum levels of total cholesterol. Liver necrosis and increased serum levels of AST and ALT were observed in the exposed mice, whereas these changes, which indicate hepatocellular death, did not occur in any of the exposed rats. p-DCB-induced renal lesions occurred only in the male rats. Hyaline droplets were observed in the proximal tubular epithelial cells, and were stained positively with anti-alpha2u-globulin, suggesting excessive accumulation of alpha2u-globulin in the epithelial cells. Granular casts were formed in the tubular lumen, resulting from the necrotic desquamation of the renal tubular epithelium. Papillary mineralization in the renal pelvis and increased serum levels of BUN and creatinine were noted. These renal changes indicated alpha2u-globulin nephropathy. Decreases in red blood cell counts, hemoglobin concentration, hematocrit and mean corpuscular volume and increased spleen weight occurred in the exposed male rats. The NOAEL was 120 ppm for the hepatic endpoint in mice and for the renal endpoint in rats. The maximum tolerated dose for a 2-yr bioassay inhalation study of rodent carcinogenicity was estimated to be 300 ppm, based on the present results.
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PMID:Thirteen-week inhalation toxicity of p-dichlorobenzene in mice and rats. 1595 47