岗松挥发油对实验性肝损害的防治作用

本研究表明,岗松油对四氯化碳、硫代乙酰胺、醋酸强的松龙引起的小鼠SGPT升高有明显的降低作用,使BSP潴留量减少,相应肝组织病变减轻。此外,岗松油对四氯化碳损害小鼠和正常小鼠戊巴比妥钠的睡眠时间均能明显缩短。对巴豆油引起小鼠耳部炎症有明显的抗炎作用。岗松油的毒性很低,口服半数致死量(LD₅₀为3,758±539mg/kg,给兔灌胃687～1030mg/kg每天一次,连续30天,一般表现、血象、肝肾功能及病理检查均未见明显的改变。     

Protective effect of Pisonia aculeata on thioacetamide induced hepatotoxicity in rats

Objective

To evaluate the protective effect of Pisonia aculeata (P. aculeata) on thioacetamide induced hepatotoxicity in rats.

Methods

Male Wistar rats were administered 250 or 500 mg/kg p.o. of P. aculeata extract for 21 days and simultaneously administered thioacetamide (TAA) 50 mg/kg bw s.c. 1 h after the respective assigned treatments every 72 h. At the end of all experimental methods, all the animals were sacrificed by cervical decapitation. Blood samples were collected. Serum was separated and analyzed for various biochemical parameters.

Results

TAA induced a significant rise in aspartate amino transferase (AST), alanine amino transferase (ALT), alkaline phosphatase (ALP), total bilirubin, gamma glutamate transpeptidase (GGTP), lipid peroxidase (LPO) with a reduction of total protein, superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione S-transferase (GST). Treatment of rats with different doses of plant extract (250 and 500 mg/kg) significantly (P<0.001) altered serum marker enzymes and antioxidant levels to near normal against TAA treated rats. The activity of the extract at a dose of 300 mg/kg was comparable to the standard drug, silymarin (50 mg/kg, p.o.).

Conclusions

It can be concluded that P. aculeata extract possesses a remarkable hepatoprotective and antioxidant activity against TAA induced hepatotoxicity. More research is required to derive an optimal therapeutic dose.     

桃核承气汤对大鼠肝性脑病模型干预治疗的分析

目的探讨桃核承气汤(去甘草)对硫代乙酰胺(TAA)诱导的大鼠肝性脑病的干预治疗作用。方法通过TAA腹腔注射诱导建立大鼠肝性脑病模型,观察桃核承气汤(去甘草)颗粒对肝性脑病的神经行为改变、神经病学测试、血清生化指标及肝脏和脑病理损伤的影响。结果本实验成功构建了大鼠肝性脑病模型。桃核承气汤(去甘草)颗粒低、中、高剂量均能不同程度地改善TAA引起的HE大鼠的神经反射情况,降低HE级别,降低血氨和生化指标指数以及使病理结果均呈现减轻的现象,其中以高剂量组为最佳(P0.05),效果与阳性药相近。结论桃核承气汤(去甘草)对TAA引起的大鼠肝性脑病有较好的预防治疗作用,本实验为该方剂的临床肝性脑病的使用提供了坚实的实验依据。     

暴发性肝衰竭晚朝大鼠血液流变学变化与内毒素血症的研究

应用硫代乙酰胺灌胃复制暴发性肝衰竭大鼠模型，测定了肝衰竭晚期大鼠和正常大鼠血液流变学指标的变化及血浆内毒素含量。结果表明，暴发性肝衰竭晚期大鼠红细胞变形性与正常对照比较无明显差异，但红细胞的聚集指数、血浆粘度、全血粘度及血浆内毒素含量均显著高于正常对照组，且全血粘度的变化与血浆内毒素水平呈负相关。提示暴发性肝衰竭晚期伴有血液流变功能紊乱，且与内毒素血症相关。     

Effects of thioacetamide on pancreatic islet B-cell function

Thioacetamide (0.01–1.3 mM) fails to exert any significant immediate effect upon insulin release from rat isolated islets. However, when administered (4 μmol/g body wt) intraperitoneally 24 h before sacrifice, it reduced food intake and body weight and affected the secretory response of isolated islets to several secretagogues, despite unaltered insulin content of such islets. This coincided with a decrease in d-[U-¹⁴C]glucose oxidation, total islet calcium content and the ionized calcium content of secretory granules in islet B-cells, and changes in both ¹³³Ba and ⁴⁵Ca net uptake. Likewise, in islets prepared from thioacetamide-injected rats and prelabeled with ⁴⁵Ca before perifusion, the cationic and insulin secretory responses to d-glucose or gliclazide, but not to the association of Ba²⁺ and theophylline in the absence of extracellular Ca²⁺, often differed from that otherwise found in islets prepared from control rats. These findings are interpreted as indicative of an impaired capacity of Ca²⁺ sequestration by intracellular organelles in the islet B-cells of thioacetamide-treated rats.     

Protective Effects of Diallyl Sulfide against Thioacetamide-Induced Toxicity: A Possible Role of Cytochrome P450 2E1

Effects of diallyl sulfide (DAS) on thioacetamide-induced hepatotoxicity and immunotoxicity were investigated. When male Sprague-Dawley rats were treated orally with 100, 200 and 400 mg/kg of DAS in corn oil for three consecutive days, the activity of cytochrome P450 (CYP) 2E1-selective p-nitrophenol hydroxylase was dose-dependently suppressed. In addition, the activities of CYP 2B-selective benzyloxyresorufin O-debenzylase and pentoxyresorufin O-depentylase were significantly induced by the treatment with DAS. Western immunoblotting analyses also indicated the suppression of CYP 2E1 protein and/or the induction of CYP 2B protein by DAS. To investigate a possible role of metabolic activation by CYP enzymes in thioacetamide-induced hepatotoxicity, rats were pre-treated with 400 mg/kg of DAS for 3 days, followed by a single intraperitoneal treatment with 100 and 200 mg/kg of thioacetamide in saline for 24 hr. The activities of serum alanine aminotransferase and aspartate aminotransferase significantly elevated by thioacetamide were protected in DAS-pretreated animals. Likewise, the suppressed antibody response to sheep erythrocytes by thioacetamide was protected by DAS pretreatment in female BALB/c mice. Taken together, our present results indicated that thioacetamide might be activated to its toxic metabolite(s) by CYP 2E1, not by CYP 2B, in rats and mice.     

TAA可能诱发骨与关节病变

我国是世界上老年人口最多的国家,其数量占到了世界老年人口总量的五分之一。随着老年人口数量的持续增加,特别是肥胖老年人口的增多,骨与关节退行性疾病人群剧增。骨与关节退行性病变成为医学界关注的焦点之一,然而其临床治疗仍是难题,这个问题在进入老龄化的中国显得尤为重要。目前,很多研究退行性病的实验没有合适的动物模型,治疗骨与关节退行性变困难的原因之一是没有合适的动物模型进行药物的筛选。硫代乙酰胺(TAA)诱导的肝纤维化动物模型稳定且重复性较好,因此该药是制备肝纤维化动物模型的常用化学药剂,而本实验室在动物实验中发现TAA可以导致试验动物骨及关节的病变,也有不少文献报道TAA在诱发肝纤维化的同时可导致骨质的破坏,因此,我们推测可以通过TAA建立一种骨与关节退行性病变的动物模型。建立TAA诱发骨与关节退行性变动物模型不仅可以证实TAA导致骨与关节病变的因果关系,并能为研究骨与关节退行性病变的发病机制、临床治疗等提供研究平台;更能引发自然界中TAA的存在、转化形式、进入人体的途径、在人体特异蓄积部位以及对人体各器官的危害等重大社会环境问题的探讨。     

Analysis of the nitric oxide-cyclic guanosine monophosphate pathway in experimental liver cirrhosis suggests phosphodiesterase-5 as potential target to treat portal hypertension

AIM To investigate the potential effect of inhibitors of phosphodiesterase-5(PDE-5) for therapy of portal hypertension in liver cirrhosis.METHODS In the rat model of thioacetamide-induced liver fibrosis/cirrhosis the nitric oxide-cyclic guanosine monophosphate(NO-cGMP) pathway was investigated. Expression and localization of PDE-5, the enzyme that converts vasodilating cGMP into inactive 5'-GMP, was in the focus of the study. Hepatic gene expression of key components of the NO-cGMP pathway was determined by qRT-PCR: Endothelial NO synthase(eNOS), inducible NO synthase(iNOS), soluble guanylate cyclase subunits α1 and β1(sGCa1, sGCb1), and PDE-5. Hepatic PDE-5 protein expression and localization were detected by immunohistochemistry. Serum cGMP concentrations were measured using ELISA. Acute effects of the PDE-5 inhibitor Sildenafil(0.1 mg/kg or 1.0 mg/kg) on portal and systemic hemodynamics were investigated using pressure transducers.RESULTS Hepatic gene expression of eNOS(2.2-fold; P = 0.003), sGCa1(1.7-fold; P = 0.003), sGCb1(3.0-fold; P = 0.003), and PDE-5(11-fold; P = 0.003) was increased in cirrhotic livers compared to healthy livers. Overexpression of PDE-5(7.7-fold; P = 0.006) was less pronounced in fibrotic livers. iNOS expression was only detected in fibrotic and cirrhotic livers. In healthy liver, PDE-5 protein was localized primarily in zone 3 hepatocytes and to a lesser extent in perisinusoidal cells. This zonation was disturbed in cirrhosis: PDE-5 protein expression in perisinusoidal cells was induced approximately 8-fold. In addition, PDE-5-expressing cells were also found in fibrous septa. Serum cGMP concentrations were reduced in rats with cirrhotic livers by approximately 40%. Inhibition of PDE-5 by Sildenafil caused a significant increase in serum cGMP concentrations [+ 64% in healthy rats(P = 0.024), + 85% in cirrhotic rats(P = 0.018)]. Concomitantly, the portal venous pressure was reduced by 19% in rats with liver cirrhosis. CONCLUSION Overexpression and abrogated zonation of PDE-5 likely contribute to the pathogenesis of cirrhotic portal hypertension. PDE-5 inhibition may therefore be a reasonable therapeutic approach for portal hypertension.