Antihepatotoxic activity of monomethyl fumarate isolated from Fumaria indica

Monomethyl fumarate, isolated for the first time from the methanolic extract of the whole plant of Fumaria indica, was characterised and screened for its antihepatotoxic activity in albino rats. The compound showed significant (P<0.01) antihepatotoxic activity against thioacetamide in vitro, and against hepatotoxicities induced by carbon tetrachloride, paracetamol and rifampicin in vivo to an extent almost similar to that of silymarin, a known antihepatotoxic agent.     

The effect of melatonin treatment on oxidative and nitrosative stress in rats with thioacetamide-induced hepatic damage.

BACKGROUND:: The following study aimed to clarify the importance of arginase and NOS activities in thioacetamide-induced hepatic damage and to evaluate the underlying mechanism of proposed protection provided by melatonin, using commonly applied therapeutic dose. METHODS:: Rats were randomly assigned to four groups (n=5): control, melatonin (10mg/kg i.p.), thioacetamide (200mg/kg i.p., two doses with a 24h interval) and thioacetamide+three doses of melatonin (10mg/kg i.p., prior- and post-treatment with a 24h interval before thioacetamide administrations) treated groups. RESULTS:: Thioacetamide administration caused hepatic damage creating oxidative and nitrosative stress accompanying perivenous necrosis and eosinophil infiltration. The significant elevation of total nitrite level in livers of thioacetamide treated groups reflected the activation of inducible nitric oxide synthase activity. The decrease in arginase activity indicated hepatic damage. Non-altered specific activity of arginase in the livers of thioacetamide treated groups did not overcome the elevation of NO production. Melatonin treatment did not modulate the levels/activities significantly. CONCLUSIONS:: Our results have indicated that nitrosative stress seems to be essentially critical in thioacetamide-induced hepatic failure in rats. Possible regulatory effect of arginase on NO production and applied dose of melatonin could not prevent hepatic damage.     

Chronic High Doses of Thioacetamide Followed by Vitamin A Modify Dolichol,Dolichol Isoprenoids,and Retinol Content in Rat Liver Cells

Our line of researches follows the hypothesis that dolichol and retinol metabolism might be interrelated and involved in liver fibrosis. To this end, in this study rats were subjected to chronic treatment with thioacetamide (TAA) (300 mg/L liquid diet) for 1 and 2 months and, after liver damage had occurred, supplemented with vitamin A before sacrifice. Dolichol, dolichol isoprene units, and retinol content were determined in isolated parenchymal and sinusoidal liver cells (hepatic stellate cells; Kupffer cells; sinusoidal endothelial cells). Dolichol increased in hepatocytes after TAA treatment, with or without vitamin A. Dolichol decreased in the other cells. Retinol in general decreased. In hepatocytes, retinol decreased only on normal nutrition, while the vitamin A load was taken up normally. The percentages of dolichol isoprene units (Dol-16 to Dol-20, in rats) confirm that Dol-18, which was not modified in percentage by TAA on normal nutrition, did not increase after vitamin A, as it did in control cells (7–12%). The behavior of Dol-18 was similar in all the cells studied. Vitamin A might reveal a latent damage produced by TAA on dolichol homologues. These data support previous hypotheses that the action of TAA depends on the administration modality, the dosage, and the diet, and that Dol-18 might have different functions and compartmentalization in the cells. Furthermore, the resultssupport the hypothesis that dolichol chain length might be interrelated with retinol metabolism, perhaps through their metabolites.     

Inhibition of experimentally-induced liver cirrhosis in rats by a nonpeptidic mimetic of the extracellualr matrix-associated Arg-Gly-Asp epitope

Aims/Methods: in the present study, we examined whether a nonpeptidic mimetic of Arg-Gly-Asp (RGD), which specifically inhibits RGD-dependent adhesion of CD4⁺ T lymphocytes or fibroblasts to fibronectin, can prevent thioacetamide-induced liver cirrhosis in rats. The nonpeptidic RGD mimetic, rather than the RGD peptide was utilized, since the peptide is rapidly degraded, and therefore, relatively ineffective for in vivo use.Results: We now report that rats treated with thioacetamide and the RGD analogue SF-6,5 for 12 weeks had lower histopathologic scores than those treated with thioacetamide alone. Further improvement in liver histology was observed after another 8 weeks of treatment with the analogue SF-6,5. Quantitative microscopic analysis by computerized imaging morphometry of liver biopsies from the three groups and controls confirmed the semi-quantitative histopathologic scores (pτ0.001). After 3 months of treatment, the spleen weights in the SF-6,5-treated rats were 30% less than those of rats and that received only thioacetamide, which indicated that the analogue-treated rats were less portal hypertensive.Conclusions: The observed inhibition of the progression of cirrhosis in rats by the nonpeptidic RGD analogue suggests that RGD mimetics may be useful therapeutically in inhibiting pathological processes that involve RGD recognition.     

台盼蓝肝脏原位灌流在研究肝微循环变化中的应用

探讨台盼蓝肝脏原位灌流在研究肝微循环变化中的应用。方法采用台盼蓝肝脏原位灌流的方法观察硫代乙酰胺（ｔｈｉｏａｃｅｔａｍｉｄｅ，ＴＡＡ）所致大鼠肝脏损伤时的微循环状态。结果内毒素血症的严重程度、反映缺血性肝损伤程度的ＬＤＨ活性、以及表示肝微循环灌注状况的台盼蓝在肝内的分布时间与肝的病理形态学改变，在ＴＡＡ损伤作用的不同时间，其变化趋势都是一致的。结论１内毒素血症在肝微循环障碍发生发展中具有重要作用。     

Additive Inhibitory Effect of Experimentally Induced Hepatic Cirrhosis by Agonists of Peroxisome Proliferator Activator Receptor γ and Retinoic Acid Receptor

Peroxisome proliferator activator receptor (PPAR) ligands prevent liver fibrosis, while the role of all-trans retinoic acid (ATRA) and its metabolite 9-cis retinoic acid (9-cis RA) is less clear. We have investigated the ability of the combination of PPARγ ligand rosiglitazone (RSG) and of ATRA to prevent liver fibrosis. In vivo treatment with RSG or ATRA reduced fibrotic nodules, spleen weight, and hydroxyproline levels in rat model of thioacetamide-induced liver fibrosis. The combination of ATRA + RSG caused the strongest inhibition, accompanied by decreased expression of collagen I, α-smooth muscle actin, TGFβ1, and TNFα. In vitro studies showed that PPARγ ligand 15-deoxy-Δ12,14-prostaglandinJ(2)[PJ(2)] and RXR ligand 9-cis RA or PJ(2) and ATRA inhibited proliferation of hepatic stellate cells HSC-T6. 9-cis RA inhibited c-jun levels and also inhibited expression of its receptor RXRα in HSC-T6 cells. The combination of PPAR-γ and RAR agonists demonstrated an additive effect in the inhibition of TAA-induced hepatic fibrosis, due to inhibition of HSC proliferation and reduction of profibrotic TGFβ1 and proinflammatory TNFα.     

硫代乙酰胺诱导的急性肝损伤大鼠肝组织Norrin/Frizzled-4表达的变化*

目的 建立硫代乙酰胺（TAA）诱导的大鼠急性肝损伤模型,探讨Norrin/Frizzled-4在肝损伤间质重建中的作用。 方法 随机将32只SD大鼠分为正常对照组（N组）8只和TAA诱导组（M组）24只。建立TAA诱导的肝损伤大鼠模型。采用ELISA法检测血清CD105和血管内皮细胞生长因子（VEGF）水平,采用Western blot法检测原代肝星状细胞和肝组织Norrin/Frizzled-4信号通路中细胞外配体蛋白Norrin和细胞膜特异性受体蛋白Frizzled-4的表达。 结果 24只TAA诱导组大鼠死亡11只（45.8%）;病理学检查显示急性肝损伤大鼠模型建立成功;对照组血清CD105水平为（2.18±0.05） ng/mL,显著低于TAA处理1 w组的（2.36±0.07） ng/mL或2 w组的（2.42±0.03） ng/mL,差异均有显著性（P<0.05）;对照组血清VEGF为（61.48±0.39） pg/mL,显著低于模型组的（64.52±0.25） pg/mL,差异均有显著性（P<0.01）;原代肝星状细胞和正常肝组织不表达Norrin蛋白或Frizzled-4蛋白,或表达量很低,急性肝损伤大鼠肝组织Norrin/Frizzled-4表达显著高于正常对照组,差异均有显著性（P<0.01）。 结论 急性肝损伤大鼠肝组织Norrin/Frizzled-4蛋白表达上调,可能与急性肝损伤初期维持血管网络形态及肝间质重建有关。     

Involvement of P53 and Bax/Bad triggering apoptosis in thioacetamide-induced hepatic epithelial cells

AIM: Thioacetamide (TAA) has been used in studying liver fibrosis and cirrhosis, however, the mechanisms of TAA-induced apoptosis in liver are still unclear. The hepatic epithelial cell line clone 9 was cultured and treated with TAA to investigate the causes of cell death. METHODS: The cell viability of TAA-induced clone 9 cells was determined using MTT assay. Total cellular GSH in TAA-induced clone 9 cells was measured using a slight modification of the Tietze assay. The activity of caspase 3 in TAA-induced clone 9 cells was monitored by the cleavage of DEVD-p-nitroanaline. TUNEL assay and flow cytometry were applied for the determination of DNA fragmentation and the proportion of apoptosis in TAA-induced clone 9 cells, respectively. The alterations of caspase 3, Bad, Bax and Phospho-P53 contents in TAA-induced clone 9 cells were measured by Western blot. RESULTS: The experimental data indicated that TAA caused rat hepatic epithelial cell line clone 9 cell death in a dose-and time-dependent manner; 60% of the cells died (MTT assay) within 24 h after 100 mg/L TAA was applied. Apoptotic cell percentage (TUNEL assay) and caspase 3 activities were highest after 100 mg/L TAA was added for 8 h. The release of GSH and the elevation in caspase content after TAA treatment resulted in clone 9 cell apoptosis via oxidative stress and a caspase-dependent mechanism. The phospho-p53, Bax and Bad protein expressions in clone 9 cells were increased after TAA treatment. CONCLUSION: These results reveal that TAA activates p53, increases caspase 3, Bax and Bad protein contents, perhaps causing the release of cytochrome c from mitochondria and the disintegration of membranes, leading to apoptosis of cells.     

解毒化瘀方对轻微型肝性脑病大鼠行为学、学习记忆能力、血浆内毒素、血氨、肝功能及肝脏病理影响随机平行对照研究

[目的]观察解毒化瘀方对轻微型肝性脑病大鼠行为学、学习记忆能力、血浆内毒素、血氨、肝功能及肝脏病理的影响。[方法]使用随机平行对照方法,将60只SD雄性大鼠编号按随机数字表法随机分为正常对照组A、模型组B、中药组C、乳果糖组D、中药+乳果糖组E(12只/组)。除正常对照组,各组皆予小剂量硫代乙酰胺(TAA)200mg/kg隔日腹腔注射建立MHE模型,造模前5日至造模后3天B、C、D、E组分别给予生理盐水、解毒化瘀汤剂、乳果糖、解毒化瘀汤剂+乳果糖灌胃10天。观察行为学、学习记忆能力变化,检测血浆内毒素、血氨、肝功能、肝组织病理变化。[结果]模型组大鼠学习和记忆功能下降,血浆内毒素、血氨、肝功等明显升高,出现肝细胞气球样变和中央静脉为中心的肝小叶点状坏死,炎性细胞浸润明显。中药组、乳果糖组、中药+乳果糖组大鼠学习和记忆功能、血浆内毒素、血氨、肝功、肝脏病理等较之明显好转(P<0.05);三者差异无显著性(P>0.05)。[结论]解毒化瘀方对TAA诱导的MHE大鼠有一定的保护作用。     

During Thioacetamide-Induced Acute Liver Failure, the Proliferative Response of Hepatocytes to Thyroid Hormone Is Maintained, Indicating a Potential Therapeutic Approach to Toxin-Induced Liver Disease

In toxic liver injury, proliferation of preexisting hepatocytes helps restore liver mass and function. While loss of liver mass per se stimulates hepatocyte proliferation, exogenous mitogens have a potential role in enhancing liver regeneration. The aim of this study was to characterize the effects of the mitogen, tri-iodothyonine, on the regenerative capacity of hepatocytes during thioacetamide-induced liver failure. Rats received (two) thioacetamide injections and, 12 hr later, either tri-iodothyonine or vehicle-only control. Liver cell proliferation was assessed and comparison made with other control groups receiving tri-iodothyonine or vehicle only. In rats with thioacetamide-induced hepatitis the proportion of hepatocytes in S-phase was greater in the tri-iodothyonine group (27±3.5%) compared to the vehicle-only group (20±2.5%; P < 0.05), with, notably, a greater number of midzonal (BrdU) positive hepatocytes in the tri-iodothyonine group. We conclude that the ability of hepatocytes in the midzonal areas of rat liver to proliferate in response to tri-iodothyonine is maintained during severe acute toxic injury.