Enhancement of aflatoxin B1-induced hepatocarcinogenesis in rats by partial hepatectomy

The effect of enhanced cell replication induced by partial hepatectomy (PH) in aflatoxin B1 (AFB1)-induced hepatocarcinogenesis has been studied in rats of the inbred As2 strain. Animals were given 0.25 mg/kg body weight of AFB1 as a single intraperitoneal dose 24 h after PH. Non-hepatectomized animals given the same dose of AFB1 served as controls. Neoplastic nodules and hepatocellular carcinoma (HCC) were detected respectively in 100% and 90% of hepatectomized animals sacrificed between 55 and 65 weeks after AFB1 administration. None of the ten non-hepatectomized rats sacrificed at this time interval showed HCC or neoplastic nodules. On histochemical staining the tumour population was found to be heterogeneous. Thus PH resulted in enhancement of AFB1-induced hepatocarcinogenesis in rats of the AS2 strain.     

Effects of Shugan-Huayu powder, a traditional Chinese medicine, on hepatic fibrosis in rat model

Shugan-Huayu powder (SHP) has been administered to outpatients with chronic liver disease without clear anti-fibrosis mechanism. To investigate the anti-fibrotic effects of SHP on liver fibrosis in a rat model and in hepatic stellate cells (HSCs) in vitro, rats were gavaged with CCl4 at 1.0 g/kg body weight twice a week for 8 weeks to induce liver fibrosis and the rats were randomly assigned to one of the three groups: -CCl4 alone, low-dose SHP and high-dose SHP. SHP was given by gavages 5 times a week for 8 weeks. Serum, livers and HSCs were assayed for serology, pathology, western blot, zymography and quantitative RT-PCR. Hepatic function improved as decreased serum aspartate aminotransferase and alanine aminotransferase, and collagen deposition and active HSCs were significantly reduced in CCl4-induced liver by SHP treatment. The expression of matrix metalloproteinase-2 (MMP-2) and transforming growth factor-beta1 (TGF-beta1) mRNA in fibrotic liver showed significant downregulation after SHP treatment. In vitro, inhibition of alpha-smooth muscle actin (alpha-SMA) expression and MMP-2 secretion of active HSCs were also noticed by SHP treatment. SHP has an antifibrotic effect on CCl4-induced liver fibrosis in rats. Anti-fibrotic mechanisms were probably inhibiting activation of HSCs and decreased expression of MMP-2 and TGF-beta1.     

2-(Allylthio)pyrazine inhibition of aflatoxin B1-induced hepatocarcinogenesis in rats.

2-(Allylthio)pyrazine (2-AP), a synthetic pyrazine derivative with an allylsulfur moiety, has hepatoprotective effects against toxicants. Effect of 2-AP on hepatic tumorigenesis in association with glutathione S-transferase (GST) induction was examined in rats exposed to aflatoxin B1 (AFB1). Both AFB1-DNA adduct formation in the liver and urinary elimination of 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B1 (AFB1-N7-guanine) adduct were also determined. Male Sprague Dawley rats were treated with 2-AP at the daily oral doses of 10, 25 and 50 mg/kg for 16 consecutive days, during which four repeated doses of AFB1 (1.0 mg/kg) were given to the animals. Rats were then subjected to two-thirds of hepatectomy, followed by administration of phenobarbital (PB). Focal areas of hepatocellular alteration were identified after 44 days and preneoplastic foci expressing the placental form of glutathione S-transferase P (GST-P) were quantified by immunostaining of liver sections. 2-AP reduced the volume of liver occupied by GST-P foci by 65-96%. Under these experimental conditions, 2-AP treatment resulted in significant elevations in GST activity in the liver. Levels of radiolabeled AFB1 covalently bound to hepatic DNA, RNA and proteins were significantly reduced in rats treated with 2-AP for 5 days. 2-AP pretreatment also caused a 45% reduction in the urinary elimination of AFB1-N7-guanine adduct over the 24-h postdosing period. The present findings demonstrated that 2-AP exhibited protective effects against AFB1-induced hepatocarcinogenesis in rats with a marked decrease in the level of AFB1-DNA adduct. Reduction of hepatic DNA adducts might result from elevations of activity of GST, which catalyzes detoxification of the carcinogen.     

Protection against diethylnitrosoamine-induced hepatocarcinogenesis by an indigenous medicine comprised of Nigella sativa, Hemidesmus indicus and Smilax glabra: a preliminary study

BACKGROUND: A decoction comprised of Nigella sativa seeds, Hemidesmus indicus root and Smilax glabra rhizome is used to treat cancer patients in Sri Lanka. However, the anti-carcinogenic properties of this decoction have not been experimentally confirmed. The purpose of this study was to determine whether the above decoction could protect against chemically induce hepatocarcinogenesis. METHODS: The effects of this decoction on diethylnitrosamine (DEN) induced hepatocarcinogenesis were examined in male Wistar rats using the medium term bioassay system of Ito, based on a 2-step model of hepatocarcinogenesis. Rats were randomly divided into 6 groups of 10 each. Groups 1 to 4 were injected with DEN (200 mg/kg) to initiate carcinogenesis. Twenty-four hours later groups 1 and 2 were administered the decoction at 4 g/kg body weight/day (dose 1) and 6 g/kg body weight/day (dose 2), respectively. Group 3 and group 4 were given distilled water instead of the decoction and a suspension of garlic powder (20 g/kg body weight/day) in distilled water (positive control), respectively. Group 5 and 6 were injected with normal saline and twenty-four hours later group 5 was given distilled water (normal control) while group 6 was given decoction dose 2 (decoction control). Oral feeding continued for two weeks after which all rats were subjected to 2/3 partial hepatectomy to promote carcinogenesis. Oral feeding continued for eight more weeks. At the end of the 10th week, rats were sacrificed and samples of livers taken for immunohistochemical studies.Carcinogenic potential was scored by comparing the number, area and staining intensity of glutathione S-transferase placental form (GST-P) positive foci and the number of cells/cm2 of the positive foci in the livers of the six groups of rats. RESULTS: The number and area of DEN-mediated GST-P positive foci, number of cells/cm2 of foci and staining intensity of the foci were significantly (P > 0.001) reduced by the decoction and garlic in the order dose 2 = garlic >dose 1. CONCLUSION: Overall results indicate that the decoction comprised of N. sativa, S. glabra and H. indicus has the potential to protect rat liver against DEN induced hepatocarcinogenesis     

Suppressive effect of penta-acetyl geniposide on the development of gamma-glutamyl transpeptidase foci-induced by aflatoxin B(1) in rats

The suppressive effects of penta-acetyl geniposide, (Ac)(5)-GP, on the hepatotoxic lesions-induced by aflatoxin B(1) (AFB(1)) were investigated in male Wistar rats. Rats were divided into six groups: groups I and II served as normal and solvent control, respectively; group III was given AFB(1) (2 mg/kg body weight) alone; group IV was given (Ac)(5)-GP (2 mg/kg) alone; and groups V and VI received both AFB(1) (2 mg/kg body weight) and (Ac)(5)-GP (1 mg and 2 mg/kg body weight, respectively). Rats received treatments for 8 weeks, then were maintained on basal diet for 32 weeks. At the end of the experiment (week 40), the liver lesions (e.g. fatty change, eosinophilic and bile duct dilation) and preneoplastic changes in rats of groups V and VI were reduced when they were compared with group III. There were no liver lesions and preneoplastic changes in rats treated with (Ac)(5)-GP alone. Although no differences in the total number of gamma-glutamyl transpeptidase (GGT)-positive foci was observed between the groups treated with AFB(1) along with or without (Ac)(5)-GP, the treatment of (Ac)(5)-GP significantly reduced the number of AFB(1)-induced GGT positive foci (with diameter larger than 0.3 mm). These results indicated that the protective effect of (Ac)(5)-GP on early hepatocarcinogenesis-induced by AFB(1) was associated with the inhibition of GGT foci development.     

性激素对大鼠诱发肝癌中胎盘型谷胱甘肽S—转移酶（GST—P）表达的影响

Using Solt-Farber method for the induction of rat hepatocarcinoma, the changes of the activity of glutathione S-transferase (GST) and the content of placenta form GST (GST-P) were studied during hepatocarcinogenesis, then the effects of sex hormones on the hepatic expression of GST-P were observed using immunohistochemical method. The results showed that both GST activity and GST-P content began to increase at the 3rd week, and reached the highest level at the 5th week (Table 1). Therefore, the 5th week was selected for the study of GST-P expression in the livers of rats treated with different protocol (Fig. 1). It was found that GST-P was highly expressed in the livers of sham-castrated male rats after chemically induced hepatocarcinoma (PLATE I, Fig. 1A, Table 2). When estradiol was administrated to these rats, both the number and area of GST-P positive(+) foci decreased significantly (PLATE I, Fig. 1B, Table 2). While testosterone was administrated instead of estradiol, the decrease of the area but slight increase of the number of GST-P positive foci were found (PLATE I, Fig. 1C, Table 2). After orchiectomy, the areas of GST-P (+) foci in carcinogen treated liver of male rats were smaller than those in rats with sham-orchiectomy and same carcinogen treatment (PLATE I, Fig. 2A, B, Table 3). When the orchiectomized male rats were administrated with estradiol, the areas of GST-P (+) foci decreased further (PLATE I, Fig. 2C, Table 3). In contrast, after ovariectomy of the female rats, the areas of GST-P (+) foci in carcinogen treated livers were slightly increased as compared with those in the rats with sham-ovariectomy and same carcinogen treatment (PLATE I, Fig. 2D, E, Table 3). While the ovariectomized female rats were administrated with testosterone, the areas of GST-P (+) foci increased further (PLATE I, Fig. 2F, Table 3). Regardless of whether castrations were done or not, GST-P expression in livers of male rats induced hepatocarcinoma was higher than in livers of female rats (PLATE I, Fig. 2A, B, D, E, Table 3). These results indicated that estrogen may inhibit but androgen may promote the GST-P expression in the rat liver during hepatocarcinogenesis. This may be related to the higher incidence of liver carcinoma in male than in female.     

Effect of vitamin E on monosodium glutamate induced hepatotoxicity and oxidative stress in rats

Monosodium glutamate (MSG), administered to rats (by gavage) at a dose of 0.6 mg/g body weight for 10 days, significantly (P<0.05) induced lipid peroxidation (LPO), decreased reduced glutathione (GSH) level and increased the activities of glutathione-s-transferase (GST), catalase and superoxide dismutase (SOD) in the liver of the animals; these were observed 24 hr after 10 days of administration. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT) were also significantly increased in the serum, on MSG administration. Vitamin E (0.2 mg/g body wt) co-administered with MSG, significantly reduced the LPO, increased the GSH level and decreased the hepatic activities of GST, catalase and SOD. The activities of ALT, AST and GGT in the serum were also significantly reduced. The results showed that MSG at a dose of 0.6 mg/g body wt induced the oxidative stress and hepatotoxicity in rats and vitamin E ameliorated MSG-induced oxidative stress and hepatotoxicity.     

Non-invasive in vivo magnetic resonance imaging assessment of acute aflatoxin B1 hepatotoxicity in rats

Acute aflatoxin B1 (AFB1)-induced hepatotoxicity was assessed in vivo in male Sprague-Dawley rats (150-300 g) using magnetic resonance imaging (MRI). MRI results were compared to serum enzyme levels, histology and electron microscopy. Twenty-four hours following intraperitoneal delivery of AFB1 (3 mg/kg body weight in a saline/dimethyl sulfoxide (DMSO; 0.03 ml/kg body weight) solution), regions of damage, characterised by increased proton signal intensities in T2-weighted images, were observed in the vicinity of the hepatic portal vein (HPV) and in the right medial regions of the liver. Image analysis of regions of apparent damage around the HPV and right medial regions, following 24 h of AFB1 exposure, indicated statistically significant (P<0.05) increases in proton image signal intensities, when compared to saline/DMSO-treated rats. No significant difference in proton image signal intensities were observed 1-2 h following AFB1 exposure. Twenty-four hours following AFB1 exposure, histopathological assessment was characterised by portal/central vein/artery congestion, sinusoid congestion, nuclear pyknosis and karyolysis, and hepatocyte vacuolation; electron microscopy (EM) examination indicated nuclear debris, swollen cytoplasmic compartments, vacuolation, and the disappearance of the smooth endoplasmic reticulum, and elevated levels of serum aspartate aminotransferase and alanine aminotransferase were found to be significantly different (P<0.01) than controls.     

Aflatoxin B1 induced hepatocarcinogenesis in neonatal rats.

Role of cell replication on aflatoxin B1 (AFB1) induced hepatocarcinogenesis was investigated in neonatal rats showing persistence of cell replication in the liver for 21 days of post natal life. Adult (8-10 weeks old) rats displaying no hepatocytic proliferation served as controls. Three doses of AFB1 were administered to both the groups at intervals of 48 hr with the doses starting on 10th day of age in the neonatal group. Appearance of phenotypically altered preneoplastic hepatocytes was quantitated in both the groups. A significantly higher incidence of preneoplastic foci was recorded in neonatal rats as compared to adult animals. The results suggest that presence of cell replication in neonatal rats at the time of AFB1 administration enhances the process of hepatocarcinogenesis.     

性激素对大鼠诱发肝癌中胎盘型谷胱甘肽S-转移酶(GST-P)表达的影响

本实验利用Solt-Farber顺序诱发大鼠肝癌,观察肝组织中GST活性及GST-P含量在化学诱癌中的变化,并观察性激素对大鼠化学诱发肝癌的早期病变中GST-P表达的作用。结果显示无论是GST活性或GST-P的含量,在诱癌至第三周开始升高,第五周升至最高。利用此模式,选择诱癌至第五周,免疫组化法检测各种处理后肝组织中GST-P的表达。发现睾丸假切除的雄性大鼠经化学诱癌后,肝中有高的GST-P表达,睾丸假切除的雄性大鼠诱癌合并雌二醇处理,明显降低肝组织GST-P阳性灶的面积和数量;合并睾丸酮处理,虽减少GST-P阳性灶的面积,但其数量略有升高。与睾丸假切除后诱癌的雄性大鼠相比,切除睾丸的大鼠经诱癌,有更低的GST-P阳性灶的面积;睾丸切除合并雌二醇处理,GST-P阳性灶的面积进一步降低。与仅化学诱癌的卵巢假切除雌性大鼠比,卵巢切除鼠诱癌后,GST-P阳性灶的面积稍有增加;对卵巢切除合用睾丸酮的大鼠诱癌,阳性灶的面积进一部增加。无论性腺切除与否,雄性大鼠比雌性大鼠有更高的GST-P表达。这些结果提示雌激素可抑制而雄激素则可促进化学诱癌大鼠肝中GST-P的表达。这一结果可能与临床上男性较女性易患肝癌有关。     

Vanadium inhibits placental glutathione S-transferase (GST-P) positive foci in 1,2-dimethyl hydrazine induced rat colon carcinogenesis

Vanadium (V) has recently been found to possess potent anti-neoplastic activity in rat colon carcinogenesis. In the present study attempts have been made to investigate the expression of the number and area of aberrant crypt foci positive for placental glutathione S-transferase (GST-P) during 1,2-dimethyl hydrazine (DMH)-induced rat colon carcinogenesis. Male Sprague Dawley rats were randomly divided into four groups. Rats in group A were designed as normal controls. Group B animals received DMH once a week (20 mg/kg body wt.) intraperitoneally for 16 weeks. Group C rats received the same treatment of DMH as in group B, along with 0.5-ppm vanadium as ammonium monovanadate ad libitum in drinking water throughout the experiment. Vanadium alone was given to Group D rats without any DMH injection. The expression of the number and the area of aberrant crypt foci (ACF) positive for GST-P was maximum in DMH-treated group. Vanadium-treated rats significantly reduced (P < 0.001) the expression of GST-P positive ACF cells (by 71.13%) for the entire period of the study. Moreover the histopathological examination also showed that vanadium action could minimize the aberrant crypt foci (P < 0.001). Furthermore, vanadium supplementation also elevated SOD activities in both liver and colon (P < 0.01, P < 0.02 and P < 0.01, P < 0.02 respectively) when compared to their carcinogen counterparts. Our results confirm that vanadium is particularly effective in limiting the action of the carcinogen, thereby establishing its anticarcinogenicity in chemically induced rat colon carcinogenesis.     

Protective effects of garlic oil on hepatocarcinoma induced by N-nitrosodiethylamine in rats

To investigate the protective effects and the possible mechanisms of garlic oil (GO) against N-nitrosodiethylamine (NDEA)-induced hepatocarcinoma in rats, Wistar rats were gavaged with GO (20 or 40 mg/kg) for 1 week, and then were gavaged with GO and NDEA (10 mg/kg) for the next 20 weeks. The changes of morphology, histology, the biochemical indices of serum, and DNA oxidative damage of liver were examined to assess the protective effects. Lipid peroxidation (LPO), antioxidant defense system, and apoptosis-related proteins were measured to investigate potential mechanisms. At the end of the study (21 weeks), GO administration significantly inhibited the increase of the nodule incidence and average nodule number per nodule-bearing liver induced by NDEA, improved hepatocellular architecture, and dramatically inhibited NDEA-induced elevation of serum biochemical indices (alanine aminotransferase , aspartate aminotransferase, alkaline phosphatase and gamma-glutamyl transpeptidase) and hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in a dose-dependent manner. The mechanistic studies demonstrated that GO counteracted NDEA-induced oxidative stress in rats illustrated by the restoration of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) levels, and the reduction of the malondialdehyde (MDA) levels in liver. Furthermore, the mRNA and protein levels of Bcl-2, Bcl-xl, andβ-arrestin-2 were significantly decreased whereas those of Bax and caspase-3 were significantly increased. These data suggest that GO exhibited significant protection against NDEA-induced hepatocarcinogenesis, which might be related with the enhancement of the antioxidant activity and the induction of apoptosis.     

Combined supplementation of vanadium and 1alpha,25-dihydroxyvitamin D3 inhibit placental glutathione S-transferase positive foci in rat liver carcinogenesis

The combined effects of vanadium (V) and 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] in inhibiting diethylnitrosamine (DEN)-induced and phenobarbital (PB) promoted hepatocarcinogenesis were examined in male Sprague-Dawley rats. All the rats were subjected to 70% partial hepatectomy (PH) at week 4 and 24h later were administered either solvent trioctanoin (Group B, D, F and H) or 10 mg DEN/kg (Group A, C, E and G) by gavage. Briefly after two weeks of DEN administration, PB were administered (0.05% in basal diet) to all the DEN-treated rats and continued till the completion of the experiment. Supplementary V at the dose of 0.5 ppm in drinking water ad libitum (Group C and D), 1,25(OH)2D3 at the dose of 3 microg/ml in propylene glycol per os twice a week (Group E and F) or both V and 1,25(OH)2D3 at the same above given doses (Group G and H) were started 4 weeks prior to DEN administration (week 0) and continued thereafter till week 15. The expression of the number and area of altered hepatocyte foci (AHF) positive for placental glutathione S-transferase (GST-P) was maximum in DEN-treated and PB promoted group (Group A). V (Group C) and 1,25(OH)2D3 (Group E) treatment significantly reduced the expression of GST-P-positive hepatocytes by 36.02% and 45.16% respectively but an additive protective action (61.46%) was found in Group G which received both V and 1,25(OH)2D3 for the entire period of the study. Moreover, histopathological examination and the incidence of hepatic hyperplastic nodules showed that combined action of V and 1,25(OH)2D3 can able to minimize the appearance of nodules as well and maintain the normal cellular architecture than V and 1,25(OH)2D3 when given alone. These results suggest that, when given together V and 1,25(OH)2D3 could be the chemopreventive agents for rat liver carcinogenesis.     

Effect of probiotic fermented milk and chlorophyllin on gene expressions and genotoxicity during AFB₁-induced hepatocellular carcinoma

The aim of this study was to investigate the chemopreventive effect of probiotic fermented milk and chlorophyllin on aflatoxin B? (AFB?) induced hepatocellular carcinoma. In vivo trials were conducted on 200 Wistar rats allocated to eight groups. Rats in the positive control group were given intraperitoneal injection of aflatoxin B? at 450 μg/kg body weight twice a week for 6 weeks. The rats were sacrificed and dissected at 25th week of the experiment, and comet assay was carried out in hepatic cells to assess the genotoxicity or DNA damage. The tumour incidence was decreased by approximately one-third than AFB? control group. The expression of c-myc bax, bcl-2, cyclin D1, p53 and rasp-21 genes was also studied. A significant (P<0.05) reduction in DNA damage was observed in probiotic fermented milk with chlorophyllin group as compared to aflatoxin B? control group. The c-myc, bcl-2, cyclin D1 and rasp-21 level was found to be highest in AFB? control group as compared to the treatment group. The results advocate the enhanced protective potential of probiotic fermented milk and chlorophyllin against AFB?-induced molecular alterations in hepatic cells during carcinogenesis.     

Modulation of DMBA-induced biochemical changes by organoselenium compounds in blood of rats

The protective role of two synthetic organoselenium compounds 1-isopropyl-3-methylbenzimidazole-2-selenone (SeI) and 1, 3-di-p-methoxybenzylpyrimidine-2-selenone (Sell) was examined against the 7,12-dimethylbenz[a]anthracene (DMBA)-induced changes in biochemical parameters in blood of rats. Albino Winstar rats (150-200 g body wt) were treated with single dose of DMBA (50 mg/kg body wt) and organoselenium compounds (25 micromol/kg) for 4 weeks at two days internal. Blood was taken from the anaesthetized rats ventricle from their hearts for biochemical analysis. Administration of DMBA resulted in elevation of urea, uric acid and creatinine levels as well as AST, ALT and LDH activities and decrease in levels of total proteins, albumin and globulin. SeI and SeII caused a significant (p<0.05) decrease in urea, uric acid and creatinine levels and alanine aminotransferase (ALT); aspartate aminotransferase; (AST) and lactate dehydrogenase (LDH) activities and significantly increased the levels of total protein and albumin (p<0.05). These organoselenium compounds are likely to be beneficial in human health.     

CCAAT enhancer-binding protein alpha suppresses the rat placental glutathione S-transferase gene in normal liver

The rat placental glutathione S-transferase (GST-P), an isozyme of glutathione S-transferase, is not expressed in normal liver but is highly induced at an early stage of chemical hepatocarcinogenesis and in hepatomas. Recently, we reported that the NF-E2 p45-related factor 2 (Nrf2)/MafK heterodimer binds to GST-P enhancer 1 (GPE1), a strong enhancer of the GST-P gene, and activates this gene in preneoplastic lesions and hepatomas. In addition to the positive regulation during hepatocarcinogenesis, negative regulatory mechanisms might work to repress GST-P in normal liver, but this remains to be clarified. In this work, we identify the CCAAT enhancer-binding protein alpha (C/EBPalpha) as a negative regulator that binds to GPE1 and suppresses GST-P expression in normal liver. C/EBPalpha binds to part of the GPE1 sequence, and the binding of Nrf2/MafK and C/EBPalpha to GPE1 is mutually exclusive. In a transient-transfection analysis, C/EBPalpha activated GPE1 in F9 embryonal carcinoma cells but strongly inhibited GPE1 activity in hepatoma cells. The expression of C/EBPalpha was specifically suppressed in GST-P-positive preneoplastic foci in the livers of carcinogentreated rats. A chromatin immunoprecipitation analysis showed that C/EBPalpha bound to GPE1 in the normal liver in vivo but did not bind in preneoplastic hepatocytes. Introduction of the C/EBPalpha gene fused with the estrogen receptor ligand-binding domain into hepatoma cells, and subsequent activation by beta-estradiol led to the suppression of endogenous GST-P expression. These results indicate that C/EBPalpha is a negative regulator of GST-P gene expression in normal liver.     

Phospholipid hydroperoxide accumulation in liver of rats intoxicated with carbon tetrachloride and its inhibition by dietary alpha-tocopherol

The formation and accumulation of phospholipid hydroperoxides, especially of phosphatidylcholine hydroperoxide (PCOOH), a primary peroxidation product of phosphatidylcholine (PC), in livers of carbon tetrachloride-intoxicated rats was investigated. PCOOH in liver and blood plasma was measured by a chemiluminescence-high-performance liquid chromatography procedure originally developed by Miyazawa et al. (Anal. Lett. 20, 915, 1987; Free Radical Biol. Med. 7, 209, 1989). Male Sprague-Dawley rats (120 g body wt., 5 weeks of age) were used in the experiments. The amount of PCOOH in the liver of control rats (CCl4-untreated) was 160 +/- 20 pmol/100 mg protein (mean +/- SD) and the PCOOH/PC molar ratio was 1.1 +/- 0.1 X 10(-5). In CCl4 (0.1 ml/100 g body wt.)-dosed rats, the liver PCOOH was 289 +/- 65 pmol/100 mg protein (PCOOH/PC = 2.4 +/- 0.4 X 10(-5], 764 +/- 271 pmol/100 mg protein (PCOOH/PC = 5.2 +/- 1.7 X 10(-5], and 856 +/- 165 pmol/100 mg protien (PCOOH/PC = 6.0 +/- 0.8 X 10(-5] at 6 h, 24 h, and 1 week after the dose, respectively. Under such conditions, the liver phosphatidylethanolamine hydroperoxide (PEOOH) level was not altered and the concentration was less than 100 pmol/100 mg protein even after the dose. The increments of liver PCOOH were suppressed 56% by the oral supplementation of DL-alpha-tocopherol (5 mg/100 g body wt./day) for a week before CCl4 administration. A relatively larger amount of PEOOH was found after stimulation of PC hydroperoxidation in the liver of rats with a large amount of CCl4 (0.25 ml/100 g body wt.) rather than with the small amount of CCl4 (0.1 ml/100 g body wt.).(ABSTRACT TRUNCATED AT 250 WORDS)     

Aflatoxin-albumin adduct formation after single and multiple doses of aflatoxin B(1) in rats treated with Thai medicinal plants.

The objective was to conduct an assessment of the ability of two Thai medicinal plants, Cymbopogon citratus Stapf and Murdannia loriformis, to modulate levels of serum aflatoxin-albumin (AF-albumin) adducts following aflatoxin B(1) (AFB(1)) exposure in rats. The influence of the plant extracts on AF-albumin adduct formation after a single exposure to 250 microg/kg body weight (bw) AFB(1) was measured over a 48-h period. Rats received M. loriformis extract (3 g/kg bw) or C. citratus Stapf extract (5 g/kg bw) daily for the week prior to the AFB(1) administration. In control rats, maximum adduct levels were observed 12 h post-AFB(1) treatment but in the animals receiving Murdannia extract, maximum levels occurred earlier, at 4 h post-treatment. No such effect was observed with the Cymbopogon extract. Daily treatment of rats with AFB(1) at 250 microg/kg bw for 3 weeks caused serum AF-albumin adduct levels to accumulate over a 10-14 day period and reach plateau levels 4.4-fold higher than observed after a single dose. Treatment with Murdannia extract for 1 week before and then throughout the AFB(1) exposure period resulted in a slight decrease in the AF-albumin adduct levels in the first week of the intervention. After that time, however, the reduction in adduct levels in the Murdannia extract group did not differ significantly from controls. No significant alteration in the biomarker levels was seen with the Cymbopogon extract treatments compared to control rats.