长期电击对19月龄大鼠血浆性激素水平肝功能和脂质过氧化作用的影响

19月龄的雄性Wistar大鼠给予随机电击,平均1次/2min,每次持续0.6s,每天电击12h,持续25天,电流强度由1.0mA逐渐增加到9.5mA。长期电击使肾上腺指数明显升高(为对照组的223%,P<0.001)。对照组雄性大鼠的血浆睾酮(T)、雌二醇(E_2)水平分别为1.63±1.35ng/ml、6.36±3.25pg/ml((?)±SD,n=5)。长期电击使血浆T水平有所降低、血浆E_2水平明显升高(23.6±13.3pg/ml,(?)±SD,n=5,P<0.05),以致T/E_2比值明显下降(P<0.05)。长期电击使大鼠肝微粒体混合机能氧化酶(MFO)活力明显下降(1.03±0.10μg甲醛/mg蛋白/20min,(?)±SD,n=5,为对照组的44.5%,P<0.001)。长期电击后19月龄的雄性大鼠大脑皮层匀浆和线粒体、下丘脑匀浆以及肝微粒体的过氧化脂质(TBA反应测定)明显升高(P<0.05)。以上结果说明长期电击明显加速了19月龄的雄性大鼠的衰老过程。     

脂质灌注对大鼠血浆抵抗素和ghrelin的影响*

目的：探讨脂质灌注对大鼠血浆抵抗素和ghrelin的影响。 方法： 采用正糖钳夹技术，在钳夹前后分别测定生理盐水对照组和脂质灌注组血浆抵抗素和ghrelin浓度，并用［3H］-葡萄糖作为示踪剂测定外周组织和肝糖的代谢。 结果： 脂质灌注组大鼠血浆游离脂肪酸（FFA）明显增加（P<0.01），葡萄糖输注率（GIR）明显降低（P<0.01）。对照组肝糖产率（HGP）明显被抑制（88%）。脂质输注组胰岛素对HGP的抑制作用明显减弱。在钳夹期间，脂质组与对照组比葡萄糖清除率（GRd）轻度降低。在正糖钳夹术结束时，对照组血浆ghrelin水平与钳夹前相比明显降低(P<0.05)。4 h的脂质灌注也引起了血浆ghrelin浓度的明显下降(P<0.05)，但是在钳夹结束时和对照组比没有明显差异。相关性分析表明空腹血浆ghrelin水平与空腹胰岛素和血糖呈明显负相关（r=-0.52和r=-0.61, P<0.05）。脂质灌注后大鼠血浆抵抗素水平较灌注前和对照组明显升高（P<0.01），空腹血浆抵抗素浓度与空腹FFA（r=0.68, P<0.01）、血糖（r=0.66, P<0.01）呈明显正相关。 结论： 脂质灌注诱导了肝脏和外周的胰岛素抵抗，抵抗素在胰岛素抵抗的形成中可能具有重要作用。高胰岛素血症，而不是游离脂肪酸，降低了大鼠循环ghrelin水平。     

长期应激对成年大鼠操作性条件反射及性激素水平和脂质过氧化作用的影响

本文观察了长期电击刺激,长期低剂量γ射线照射以及两者相加的应激刺激对成年雄性大鼠机体功能的影响,结果表明:上述应激刺激均明显抑制成年大鼠生长,促进大鼠操作性条件反射的形成,仅电击条件下条件反射的消退延缓。三种刺激对血浆睾酮及睾酮与雌二醇比值无明显影响,但刺激8周后E_2水平有所升高,长期照射条件下血浆MDA升高。长期电击与电击加照射16周后大鼠胸腺萎缩明显加速。长期低剂量γ射线照射后全血白细胞计数明显下降,其中淋巴细胞比例减少,粒细胞比例升高。以上结果表明上述三种长期应激刺激对成年大鼠生长,操作性条件行为和性激素、脂质过氧化作用均有一定影响,而且不同的应激刺激具有不同的作用特点。     

吡格列酮对脂质灌注大鼠糖代谢和PPAR-γ表达的影响

目的：探讨吡格列酮 (Pio) 对游离脂肪酸诱导的胰岛素抵抗大鼠糖代谢和PPAR-γ表达的影响。方法:采用扩展正糖钳夹实验和［3-3H］标记葡萄糖示踪技术，观察了4 h脂质灌注导致大鼠血浆游离脂肪酸（FFA）升高引起糖代谢和脂肪组织PPAR-γ表达变化及Pio处理后的影响。 结果:在钳夹稳态期，对照组（N组）血浆FFA水平明显降低，而脂质灌注组（L组）和吡格列酮+脂质组（P/L组）FFA水平明显升高。 P/L组葡萄糖输注率(GIR)较N组明显降低（P<0.01）, 而L组又明显低于P/L组（P<0.01）；N组和P/L组肝糖输出 (HGP) 与基础值相比被明显抑制达85%（均P<0.01），在L组，胰岛素对HGP的抑制作用受到明显障碍（仅抑制8.7%）。L组和P/L组葡萄糖清除率（GRd）明显低于N组（P<0.01）。P/L组脂肪组织PPAR-γ表达明显增加。 结论:脂质灌注诱导了大鼠胰岛素抵抗。吡格列酮干预使大鼠脂肪组织PPAR-γ表达明显增加，并抑制了内源性肝糖产生，从而部分逆转了脂质诱导的胰岛素抵抗。     

硒和维生素E与内皮素在克山病心肌坏死发生中的作用

本研究以低硒和维生素Ｅ的克山病区粮饲养大鼠，用放免法测定其血浆和心肌的内皮素，发现克山病病区组ＥＴ水平明显高于其它各组；同时伴有谷胱甘肽过氧化物酶力下降，自由基净含量和脂质过氧化物浓度增高。     

氯丙烯对大、小鼠肝微粒体细胞色素P-450、谷胱甘肽和谷胱甘肽-S-转移酶的影响

本实验采用直接和间接方法研究了氯丙烯与肝微粒体细胞色素P-450(P-450_(LM))的相互作用,并对氯丙烯急性、多次性和亚急性染毒大鼠的肝、肾谷胱甘肽(GSH)含量、肝细胞溶质的谷胱甘肽与转移酶(GST)和P-450_(LM)的活性进行测定,以探索代谢途径与氯丙烯毒作用的关系。实验发现,小鼠用苯巴比妥(PB)和梯诺龙(Tiloron)预     

人血浆高密度脂蛋白对大鼠内毒素血症的治疗及防护作用研究

目的:观察人血浆高密度脂蛋白(HDL)对大鼠内毒素血症的治疗和防护效果。方法:采用鲎试剂法和放射免疫分析法于3个时点动态测定对照组、治疗组和防护组大鼠血浆内毒素(ET)水平和肿瘤坏死因子(TNF)浓度并观察血压及存活时间。结果:①输注ET后对照组大鼠血压进行性下降(P<0.01);治疗组大鼠输注HDL后其血压虽也降低但下降程度明显弱于对照组(P<0.01);防护组大鼠在输注ET后血压无明显下降(P>0.05)。治疗组及防护组大鼠存活时间均明显长于对照组(P<0.01)。②3组大鼠血浆ET水平在各时点均无明显变化(P>0.05)。③治疗组及防护组大鼠血浆TNFα水平于第3时点均明显降低(P>0.05)。结论:人血浆HDL能减轻或抑制内毒素血症大鼠血压下降并明显延长其存活时间,对内毒素血症具有良好的治疗和防护作用,此作用可能与其抑制TNF释放有关。     

姜黄素对哮喘大鼠支气管肺泡灌洗液和血浆表皮生长因子含量的影响

目的观察姜黄素对慢性过敏性哮喘模型大鼠支气管肺泡灌洗液(BALF)和血浆表皮生长因子(EGF)含量的影响,探讨姜黄素抑制哮喘大鼠气道炎症和改善气道重塑的作用机理。方法选择雄性SD大鼠随机分组,以卵清蛋白(OVA)和Al(OH)3建立慢性过敏性哮喘大鼠模型。应用双抗体夹心酶联免疫吸附试验法测定BALF和血浆EGF浓度,通过HE染色和透射电镜观察肺组织病理和超微结构。结果与正常对照组比较,哮喘模型组大鼠BALF和血浆EGF浓度显著高于正常对照组(P0.01),姜黄素组与地塞米松组之间BALF和血浆EGF浓度无明显统计学差异(P0.05);与哮喘模型对照组比较,除玉米油组外,其余干预组均显著低于哮喘模型对照组(P0.01);姜黄素可明显降低哮喘模型大鼠BALF和血浆EGF浓度,效果同地塞米松组相当,同时大鼠肺组织炎症性和结构性病理变化明显改善。结论 EGF在哮喘大鼠BALF和血浆中浓度增高,可能参与了哮喘发病和气道重塑过程。姜黄素能明显降低哮喘大鼠BALF和血浆EGF的水平,有助于抑制哮喘大鼠气道炎症和气道重塑的病理生理过程,其作用机理还有待进一步研究。     

阿托伐他汀对自发性高血压大鼠血压、循环和心肌血管紧张素Ⅱ水平的影响

目的：观察阿托伐他汀对自发性高血压大鼠（SHR）血压、循环和心肌血管紧张素Ⅱ(Ang Ⅱ)水平的影响。 方法: 24只SHR随机分为4组（每组6只）：SHR对照组、阿托伐他汀50 mg组、阿托伐他汀10 mg组和缬沙坦组, 6只WKY大鼠作为正常血压对照组（WKY组）。给药前和给药后每两周测量大鼠尾动脉收缩压（SBP）。测定血清脂质及血浆和心肌血管紧张素Ⅱ（AngⅡ）水平。 结果: SHR各组SBP于给药前无显著差异（P>0.05），但均显著高于WKY组（P<0.01）；给药后第4、6周,阿托伐他汀50 mg组SBP明显低于SHR对照组（P<0.01）,10 mg组则不明显；缬沙坦组自给药后第2周，SBP进行性下降（P<0.01）。SHR对照组与WKY组血脂各项指标无显著差异（P>0.05）；阿托伐他汀50 mg组TC、TG及LDL-C水平明显低于SHR对照组（P<0.05，P<0.01），10mg组仅LDL-C水平明显下低于SHR对照组（P<0.05）。SHR对照组血浆AngⅡ浓度无明显差异，但心肌AngⅡ浓度明显高于WKY组（P<0.05）；给药6周后，阿托伐他汀各剂量组和缬沙坦组血浆AngⅡ浓度显著高于SHR对照组（均P<0.01），而心肌AngⅡ浓度在阿托伐他汀50 mg组和缬沙坦组明显低于SHR对照组（P<0.05）。 结论: 阿托伐他汀能降低SHR的血压，机制可能与降低心肌AngⅡ浓度含量有关。     

内源性睾酮在雄性高脂血症大鼠早期动脉粥样硬化形成中的作用

目的：研究内源性睾酮对雄性高脂血症大鼠早期动脉粥样硬化形成的影响及其作用机制。方法：雄性Ｗｉｓｔａｒ大鼠随机均分为正常对照组,高脂对照组,高脂去势组（切除双侧睾丸及副睾）。实验时间１２周。结果：高脂去势组与高脂对照组相比,血浆总胆固醇（ＴＣ）,甘油三酯（ＴＧ）浓度相差不明显,低密度脂蛋白（ＨＤＬ）水平较高,低密度脂蛋白（ＬＤＬ）＋极低密度脂蛋白（ＶＬＤＬ）水平较低,血浆脂质过氧化物（ＬＰＯ）水平较     

In vitro effects of calcium channel blockers and beta-adrenergic blocking agents on microsomal lipid perocidation and cytochrome p-450 content.

The effects of the calcium channel blockers (CCB) nifedipine (N), verapamil (V) and diltiazem (D) and the beta adrenergic blocking agents (BAB) propranolol (P) and atenolol (A) administered alone or in combination on lipid peroxidation (LPO) and cytochrome p-450 content were studied in rat liver microsomes. The drugs were tested in concentrations of 1 mM. V, A and P alone significantly decreased TBARS formed after in vitro stimulation of LPO by Fe2+ and ascorbate, whereas no antioxidant effect was found for N and D. A correlation between the antioxidant capacity of the drugs and their ability to protect cytochrome p-450 after in vitro stimulation of LPO was observed except for propranolol. Moreover, propranolol abolished cytochrome p-450 protecting effect of verapamil when administered together. A direct, LPO-independent decreasing effect on cytochrome p-450 was observed upon in vitro incubation of microsomes with propranolol. The results are discussed in terms of LPO-dependent degradation of cytochrome p-450, formation of propranolol reactive metabolites and propranolol-dependent changes in cytochrome lipid environment.     

Selective enhancement of cytochrome p-450 activity in rat hepatocytes by in vitro heat shock

We investigated the effect of heat shock on cytochrome P-450 activity in rat hepatocytes and report a significant, selective, and time-dependent enhancement of cytochrome P-450 activity in heatshocked hepatocytes. Stable long-term cultures of rat hepatocytes were heat shocked (42.5 degrees C) for 1 to 3 h and allowed to recover at 37 degrees C. Cytochrome P-450-dependent ethoxyresorufin O-dealkylase (EROD) and benzyloxyresorufin O-dealkylase (BROD) activities were measured up to 48 h after heat shock treatment. In general, the optimal heat shock exposure time was between 2 and 3 h. BROD activity (induced by sodium phenobarbital) increased approximately 6-fold in hepatocytes heat shocked for 3 h in comparison with hepatocytes maintained at 37 degrees C. EROD activity (induced by 3-methylcholanthrene) increased 2-fold on exposure to heat shock for 2 h. The expression of inducible heat shock proteins Hsp70 and Hsp32 was verified by Western immunoblot analyses. In the absence of the appropriate inducer, heat shock treatment did not enhance cytochrome P-450 activity. Furthermore, enhanced P-450 enzyme activity was delayed for heat-shocked hepatocytes. It is hypothesized that heat shock treatment attenuates the negative effects triggered by the addition of the toxic inducers and possibly stabilizes the levels of cytochrome P-450 proteins. These results suggest that heat shock treatment may be used to enhance the functionality of hepatocytes, specifically, in bioartificial liver assist devices.     

Substrate specificity of age-related changes in the inducibility of hepatic microsomal monooxygenases in middle-aged rats

Hepatic microsomal monooxygenase induction was investigated in young-adult and middle-aged male Fischer 344 rats. Monooxygenase components and drug metabolism activities were determined in liver microsomes prepared from rats treated with phenobarbital (PB), β-naphthoflavone (BNF) or methyltestosterone (MT) and compared with values from untreated rats. PB and BNF effects on cytochrome P-450 concentration and cytochrome c reductase activity were similar in young-adult and middle-aged animals. However, the extent of cytochrome P-450 induction by MT was less in the older animals. The age-related changes in induction of drug metabolism activities differed with different substrates for the monooxygenase system. In contrast to the inducibility of benzphetamine N-demethylation and aniline hydroxylation, which was dimished in the older rats, the inducibility of nitroanisole O-demethylation was enhanced. The results imply that qualitative changes in the microsomal enzyme system occurred as the animals progresses from young to middle adulthood.     

Thymus influences liver functions through hypothalamus-pituitary-gonad axis in rats

The aim of the review is to summarize our recent studies on the influence of the thymus on liver functions and its intermediary pathway in rats. Young adult thymectomized rats were used as a model in the experiments, and either thymic peptides or sex hormones were supplemented to these animals. Liver microsomal cytochrome P-450 and aminopyrine-N-demethylase (ADM) activities were decreased in thymectomized rats, and the change in the male was more significant than that in female rats. An increase of liver malondialdehyde (MDA) and a decrease of liver glutathione (GSH) and superoxide dismutase activity were observed in the female thymectomized rats, but not in the males. Accompanied by the increase of MDA, a decline of membrane fluidity of liver microsomes and mitochondria and a decrease of Ca²⁺ uptake by liver microsomes were exhibited in the female thymectomized rats. Subcutaneous injection of thymic peptides decreased MDA level, and increased GSH content, membrane fluidity and Ca²⁺ uptake by microsomes in the liver of thymectomized rats. On the other hand, male thymectomized rats showed a decrease of hypothalamic luteinizing hormone-releasing hormone (LHRH), plasma luteinizing hormone (LH) and testosterone levels. Subcutaneous injection of testosterone propionate to these animals restored their liver P-450 and ADM activities to normal levels. Female thymectomized rats exhibited a decline of hypothalamic LHRH and plasma estradiol levels. Supplementation of estradiol benzoate reversed the increase of liver MDA in these animals. The data suggest that the thymus may influence liver functions through the hypothalamus-pituitary-gonad axis. Thus, a new ‘thymus-neuroendocrine-liver pathway’ is proposed, which may account for the significance of the thymus in maintaining homeostasis and integrative functions in the body.     

The effects of age on the pharmacokinetics and biotransformation of theophylline in vivo and in vitro in the Mongolian gerbil (Meriones unguiculatus).

The effect of post maturational aging on the in vivo disposition of theophylline was examined in the Mongolian gerbils (Meriones unguiculatus) aged 30-39 (old), 12-18 (middle-aged) and 3 (young) months following a 20 mg/kg i.p. dose. Biotransformation of theophylline was also examined in liver microsomes from non-induced and 3-methylcholanthrene induced gerbils. Analysis of theophylline plasma kinetics showed decreased clearance, increased half-life and increased volume of distribution in old vs. young animals. Clearance to the 1,3-dimethyluric acid metabolite was similar for all age groups, while clearance to the 1-methyluric acid metabolite was significantly lower in the middle-aged group compared to that of young and old gerbils. Urinary recovery of 1-methylurate was increased in old vs. young and middle-aged animals while recovery of theophylline was decreased. 3-Methylcholanthrene induction resulted in decreased recovery of theophylline and increased recovery of 1,3-dimethylurate and 1-methylurate in young and middle-aged gerbils compared to non-induced controls. Decreased microsomal protein content was observed in old vs. young and middle-aged gerbils and an age-related decrease in cytochrome P-450 content (nmol P-450/g liver) was also observed. The rate of dimethylurate formation was decreased 37% in microsomes from old vs. young and middle-aged gerbils. 3-Methylcholanthrene administration resulted in a 2- and 1.5-fold increase in the rate of 1,3-dimethylurate formation in young and middle-aged gerbils, respectively. The results of these experiments indicate that the Mongolian gerbil may be useful for the study of the biochemical mechanisms underlying age-related changes in the biotransformation and kinetics of theophylline.     

Effect of traditional Chinese herbal medicines on the pharmacokinetics of western drugs in Sprague-Dawley rats of different ages (II): Aminophylline-huan shao tan and aminophylline-pu chung yi chi tang.

The effect of Chinese herbal medicines (Huan Shao Tan and Pu Chung Yi Chi Tang) and western drugs (sodium phenobarbital and cimetidine) on the serum concentration and pharmacokinetic parameters of theophylline and cytochrome P-450 of Sprague-Dawley (SD) rats of three different ages were examined. The older rats without pretreatment with Chinese herbal medicines and western drugs exhibited higher serum theophylline concentration and lower pharmacokinetic parameters of theophylline than middle-aged and younger rats (P < 0.05), but there was no difference in cytochrome P-450 activity among the three different ages of rats. All rats when pretreated with sodium phenobarbital showed lower serum theophylline concentration and higher pharmacokinetics parameters of theophylline. Also, the activity of cytochrome P-450 was higher (P < 0.05). When cimetidine was pre-administered in SD rats of three age groups, all rats exhibited lower serum theophylline concentration and higher pharmacokinetics parameters (P < 0.05), but the activity of cytochrome P-450 remained unchanged (P > 0.05). The results were opposite to other studies, probably because the dose and dosing intervals were different. No single effect occurred on the younger and middle-aged rats after pretreatment with Huan Shao Tan and Pu Chung Yi Chi Tang: their serum theophylline concentration, pharmacokinetics parameters and cytochrome P-450 activity were the same as the control group. However, the older rats after pretreatment with Huan Shao Tan or Pu Chung Yi Chi Tang showed lower serum theophylline concentration and higher pharmacokinetics parameters than the younger and middle-aged rats pretreated with similar Chinese herbal medicines. This indicates that Huan Shao Tan and Pu Chung Yi Chi Tang may perhaps improve the elimination of theophylline in older rats. This might be attributed to the increase in hepatic blood flow or in liver volume, since the activity of cytochrome P-450 was not affected by the administration of Chinese herbal medicines.     

Influence of shock-induced fighting and social factors on pituitary-adrenal activity, prolactin and catecholamine synthesizing enzymes in rats

The present experiment investigated changes in pituitary-adrenal activity, prolactin and catecholamine synthesizing enzymes in rats exposed to electric shocks in pairs or individually, in comparison to animals receiving no shock and tested in pairs or alone. Pairs of rats repeatedly exposed to electric shocks displayed a lower activation of the pituitary-adrenal system but a stronger activation of the sympathetic-adrenal medullary system than rats shocked individually. There was no differential release of prolactin according to the social setting in which shock occurred. Social factors by themselves influenced plasma corticosterone levels but not plasma levels of ACTH and prolactin nor catecholamine synthesis. The results are discussed in relation to the postulated beneficial effects of fighting on physiological activation produced by electric shock.     

Hepatic microsomal cytochrome P450 system during experimental hookworm infection

Experimental infection of golden hamsters with the hookworm, Ancylostoma ceylanicum, caused a profound decline in the hepatic microsomal cytochrome P450 content. Concomitant decrease was also noticed in aminopyrine N-demethylase and benzo[a]pyrene hydroxylase activities. However, aniline hydroxylase activity was only marginally elevated during the infection. Microsomal markers, viz., cytochrome b5, NADH-cytochrome-c reductase, and glucose-6-phosphatase, were not significantly altered. Hepatic tissue exhibited an accumulation of lipids, especially phospholipids, triglycerides, and cholesterol, resulting in fatty necrosis around the central vein region. Isolated hepatic microsomes showed a decrease in phosphatidylcholine content. Impairment in hepatic mixed function oxidase (MFO) activities was further confirmed by prolongation in hexobarbital sleeping time and zoxazolamine-induced paralysis. The hepatic MFO system of A. ceylanicum-infected hamsters responded qualitatively and quantitatively in a manner similar to that of control hamsters, upon stimulation with selective chemical inducers like phenobarbitone and 3-methylcholanthrene. Kinetic and in vitro substrate binding studies revealed that for aminopyrine the substrate affinity and the maximum enzyme activity (Vmax) were decreased, while for aniline the binding affinity was decreased and the binding capacity was enhanced. Results indicate specific/selective impairment of the hepatic microsomal cytochrome P450 system during hookworm infection and may have many practical implications in toxicology and pharmacology.     

Metabolic activation of aflatoxin B1 by liver tissue from male fischer F344 rats of various ages

The effect of aging on the ability of the liver to activate chemical procarcinogens was studied using 12-, 18-, and 27-month-old male Fischer F344 rats. The cytochrome P-450 content of the S9 and microsomal fractions of the liver decreased approximately 30% between 12 and 18 months of age. The structural conformation of cytochrome P-450 in microsomes from 12-, 18-, and 27-month-old rats was studied using electron-spin resonance spectroscopy. An age-related decrease in the amount of cytochrome P-450 ferric iron in the liver microsomes was observed. The conversion of the chemical procarcinogen aflatoxin B1 to mutagenic compounds by the S9 and microsomal fractions of liver was measured using the Salmonella typhimurium bioassay. A 40-50% decrease in the metabolic activation of aflatoxin B1 was observed between 12 and 18 months of age. However, the activation of aflatoxin B1 did not change after 18 months of age. The age-related decrease in the activation of aflatoxin B1 by liver appears to be due to a decrease in the metabolic activity of the mixed-function oxidase system.