Metoprolol and propranolol treatment in carbon tetrachloride-induced hepatic injury.

The effects of beta 1-selective metoprolol (CAS 37350-58-6) and the nonselective beta-adrenoceptor antagonist propranolol (CAS 525-66-6) were investigated in healthy and CCl4 damaged male rats. Treatments were performed for 16 days, orally with dosages reducing heart beat/min by 25% (metoprolol 10 mg/kg, propranolol 1 mg/kg). Liver glycogen content was not influenced by either beta-blocker in healthy animals. CCl4-induced loss of glycogen was equally moderated by metoprolol and propranolol. Blood glucose increased in metoprolol treated healthy and liver damaged rats after a single dosage likewise following prolonged treatment. Propranolol was without effect on blood glucose level. Cytochrome P-450 decline in microsomal fraction was greater in metoprolol, than in propranolol treated healthy animals. However, the severe fall elicited by liver injury was moderated by metoprolol and normalised by propranolol. Cytochrome b5 seems to be involved in metoprolol metabolism. Cytochrome P-450-dependent aminopyrine-N-demethylase was impeded by metoprolol in animals with healthy liver. The serious inhibition caused by CCl4 was moderated by metoprolol and with a better result by propranolol. The high serum bilirubin level in liver lesion was lowered by metoprolol and particularly by propranolol. Neither phase I metabolic process aminopyrine-N-demethylation nor phase II glucuronidation were normalised. A comparison of this data with the results of a previous 12-day treatment schedule indicates that no changes in efficacy occurred with longer treatment. The present results pertain to the importance of the selection of beta-adrenoceptor blocker in liver lesion.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of diazepam in the recovery of rabbits from acute acetaminophen intoxication.

We have recently shown that diazepam can reduce mortality of acute iron overdose in rats. The mechanism for that effect is not yet defined. Our objective in the present study was to assess whether diazepam can similarly reduce mortality of experimental acute acetaminophen intoxication. Survival of rabbits was compared among four groups receiving 3 g/kg (body weight) of acetaminophen (LD40) orally each, followed by: 1) nothing (group I), 2) one oral dose of 140 mg/kg N-acetylcystein (NAC) an hour later (group II), 3) intramuscular injection of 7 mg/kg diazepam (group III), 4) intramuscular injection of 7 mg/kg diazepam and one oral dose of 140 mg/kg NAC an hour later (group IV). 37.5% of rabbits in group I died after 16 hours, whereas none of the rabbits in group III died, (p = 0.04). No animal died during the 96-hour observation period in groups II and IV. Two and four hours post drug administration, acetaminophen plasma concentrations (APC) were significantly lower among rabbits in group III than in group I (p = 0.0007 and 0.01, respectively) and significantly lower among rabbits in group IV than in those in group II (p<0.0001 and p = 0.03, respectively). Acetaminophen plasma concentrations 2 hours after drug administration were also significantly lower among rabbits in group III than in those in group II (p = 0.0002). Seven and 24 hours after dosage, APC tended to be higher among rabbits in group III than in those in group I, but not significantly so. Administration of diazepam without NAC did not prevent liver and renal dysfunction. We conclude that early administration of diazepam in acute experimental acetaminophen overdose in rabbits reduced APC and mortality, probably by slowing intestinal motility, which resulted in delayed acetaminophen absorption from the gastrointestinal tract.     

Stress-induced lidocaine modification in serum and tissues.

The aim of this study is to examine the influence of acute (trauma) and chronic (cold swimming and adjuvant rheumatoid arthritis) stress on lidocaine concentrations in plasma. Forty male Wistar rats were used. The animals were divided into four groups. Group A served as control. Group B underwent mandible osteotomy. Group C was submitted to swimming stress in cold water 4 degrees C for ten minutes daily for 15 minutes, while group D underwent experimental arthritis with Freud's adjuvant. All groups received lidocaine i.m (2.5 mg/kg). Blood samples were collected and FFA (free fatty acid), unbound-lidocaine, albumin and a1-acid glycoprotein concentrations were estimated. Furthermore, the adrenals, heart and liver were isolated. The adrenals' relative weight (adrenal weight/body weight) was assessed, while lidocaine concentrations in the heart and the liver incubation medium were measured by intertechnic a-counter. Lidocaine and FFA levels in serum as well as the adrenal weights demonstrated a significant elevation in stress-groups as compared to the control group. Furthermore, in the stress-groups, lidocaine concentrations in heart tissue were significantly increased, whereas in the liver they were significantly reduced as compared to the control group. Our results indicate that stress can alter lidocaine levels in plasma and tissues, suggesting that stress should be considered an important factor when determining the dosage of lidocaine in clinical application.     

Hepatoprotective Effects and Safety Evaluation of Coumarinolignoids Isolated from Cleome viscosa Seeds

The aim of the present work was to investigate the in vivo hepatoprotective potential of coumarinolignoids (cleomiscosins A, B, and C) isolated from the seeds of C. viscosa. The study was performed against CCl(4)-induced hepatotoxicity in albino rats. Rats were divided into four groups. The animals of group I served as normal and was given only vehicle. Group II served as toxin control and administered with CCl(4) (50% solution liquid paraffin, 2 ml/kg intraperitoneally). The animals of group III received coumarinolignoids (50 mg/kg) for six days orally as well as CCl(4) (2 ml/kg) on 4(th) day i.p. Similarly animals of group IV received silymarin (50 mg/kg) for six days orally as well as CCl(4) on 4(th) day i.p. On 7(th) day various parameters viz. serum glutamyl oxaloacetic transaminase, serum glutamyl pyruvate transaminase, serum alkaline phosphatase, serum bilirubin, liver glycogen were estimated and histopathology was performed. Additionally, acute oral toxicity of the said coumarinolignoids was carried out in swiss albino mice. The coumarinolignoids were found to be effective as hepatoprotective against CCl(4)-induced hepatotoxicity as evidenced by in vivo and histopathological studies in small animals. Safety evaluation studies also exhibit that coumarinolignoids are well tolerated by small animals in acute oral toxicity study except minor changes in red blood cell count and hepatic protein content at 5000 mg/kg body weight as a single oral dose. Coumarinolignoids which is the mixture of three compounds (cleomiscosin A, B and C) is showing the significant protective effects against CCl(4)-induced hepatotoxicity in small animals and also coumarinolignoids are well tolerated by small animals in acute oral study.     

Potentiation of paracetamol and carbon tetrachloride-induced hepatotoxicity in rodents by the food additive vanillin.

The potential of vanillin to potentiate the paracetamol and carbon tetrachloride (CCl4)-induced hepatotoxicity was investigated in rats. Vanillin when given alone (15 mg/kg, orally), did not modify liver function in rats as the values of serum enzymes of alkaline phosphatase (ALP) and aminotransaminases (AST and ALT) were found similar to those in the normal animals. However, when given repeatedly before the administration of the subtoxic dose of paracetamol (500 mg/kg) or CCl4 (1 ml/kg), vanillin caused liver damage, as manifested by the significant increase in the serum levels of hepatic enzymes. When tested for its possible interaction with pentobarbital (75 mg/kg, i.p.) and strychnine (0.9 mg/kg, i.p.), it caused reduction in pentobarbital-induced sleep in mice as well as preventing the animals against the lethal effect of strychnine, suggestive of an induction of microsomal drug metabolizing enzymes. These results indicate that vanillin potentiates the hepatotoxic potential of paracetamol and CCl4 in rats probably through an enzyme induction process.     

Du-Zhong (Eucommia ulmoides Oliv.) leaves inhibits CCl4-induced hepatic damage in rats.

The protective effects of water extract of Du-Zhong (Eucommia ulmoides Oliv.) leaves (WEDZ) and its active compound (protocatechuic acid; PCA) on liver damage were evaluated by carbon tetrachloride (CCl4)-induced chronic hepatotoxicity in rats. Wistar rats were orally treated with WEDZ (0.1, 0.5, and 1.0 g/kg bw) or PCA (0.1 g/kg bw) with administration of CCl4 (0.5 ml/rat, 20% CCl4 in olive oil) for 28 consecutive days. It showed that CCl4-treated rats increased the relative organ weights of liver and kidney. CCl4-induced rats liver damage and significantly (p<0.05) increased the GOT, GPT, LDH and ALP levels in serum as compared with the control group. Treatment with WEDZ or PCA could decrease the GOT, GPT, LDH and ALP levels in serum when compared with CCl4-treated group. CCl4-treated rats also significantly (p<0.05) decreased the GSH content in liver and trolox equivalent antioxidant capacity (TEAC) in serum whereas increased (p<0.05) MDA content in liver as compared with the control group. Treatment with WEDZ or PCA also significantly (p<0.05) increased the GSH content and significantly (p<0.05) decreased the MDA content in liver. Administration of WEDZ or PCA could increase the activities of GPx, GRd and GST in liver. Liver histopathology showed that WEDZ or PCA reduced the incidence of liver lesions including hepatic cells cloudy swelling, lymphocytes infiltration, cytoplasmic vacuolization, hepatic necrosis and fibrous connective tissue proliferated induced by CCl4 in rats. The data suggest that oral administration with WEDZ for 28 consecutive days significantly decrease the intensity of hepatic damage induced by CCl4 in rats.     

Effect of carbon tetrachloride on blood coagulation and fibrinolytic activities in rats

Blood coagulation and fibrinolytic activities were studied in rats with hepatic injury induced by carbon tetrachloride (CCl4). Acute hepatic injury was induced by single oral administration of 0.5, 1.0, 2.0 and 3.0 ml/kg of CCl4. Experiments were performed on the parameters of blood coagulation activities (TEG, HPT, TT, PRCT, PT, PTT, fibrinogen, factor XIII and AT III) and those of fibrinolytic activities (PLG, alpha 2PI) and plasma total protein, GOT, GPT, Ht, L/B ratio. All determinations were measured at 24 hr after administration of CCl4. Blood coagulation and fibrinolytic activities in rats were weakened in accordance with the dosage of CCl4 administration. Below CCl4 administration of 1.0 ml/kg, the GOT and GPT values increased in accordance with the dosage. However, with CCl4 administration of above 1.0 ml/kg, these values stayed at almost the same level. On the other hand, the relationship between the dosage of CCl4 and logarithmic values of HPT, PT, PTT, factor XIII and PLG all showed a good straight line.     

Cytoprotective effect of mangiferin on benzo(a)pyrene-induced lung carcinogenesis in swiss albino mice

Antioxidants are one of the key players in tumourigenesis, and several natural and synthetic antioxidants have been shown to have anticancer effects. In the present investigation, the efficacy of mangiferin on the antioxidant status of benzo(a)pyrene-induced lung carcinogenesis in Swiss albino mice was assessed. The animals were divided into five groups. The animals in groups I and V were normal control and mangiferin control, respectively. Groups II, III and IV were administered with benzo(a)pyrene (50 mg/kg body weight, orally) for 4 weeks (twice a week) to induced lung carcinogenesis. Starting 1 week prior to benzo(a)pyrene administration, group III animals were treated with mangiferin (100 mg/kg body weight) in the diet for 18 weeks; 12 weeks after benzo(a)pyrene administration, group III animals were treated with mangiferin that continued until the end of the experiment period (18 weeks). At the end of the experiment period, the reactive oxygen species, glutathione and the activities of antioxidant enzymes were assessed in both lung and liver tissues. The levels of glutathione, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, vitamin E and vitamin C were decreased in group II animals. However, in the mangiferin + benzo(a)pyrene-treated groups III and IV, the levels of GSH and the activities of antioxidant enzymes in both lung and liver were improved when compared with benzo(a)pyrene-induced group II animals. In addition, the finding that mangiferin decreased reactive oxygen species levels and enhanced antioxidant status suggests that this polyphenol might also be of value in the prevention of benzo(a)pyrene-induced lung carcinogenesis.     

Beta receptor blockade and liver function

The effects of propranolol on liver functions of healthy rats were studied administering daily doses of 1 mg/kg. Beta receptor blockade has been investigated in carbontetrachloride induced liver cirrhosis. Normal liver functions were unchanged with the exception of an increase in Glucos-6-Phosphatase. The severe cirrhotic injuries were counteracted or moderated when propranolol administration started the same day as CCl4 injection. The amount and function of mixed-function-monooxygenases were normalised. Carbohydrate and protein metabolism impairments were moderated. Serum triglyceride and HDL-cholesterin levels were however uninfluenced. The metabolic properties of propranolol seem to be advantageous in chronic liver impairments.     

大黄酸抑制四氯化碳诱导的大鼠肝纤维化形成

目的:观察大黄酸对实验性肝纤维化的影响.方法:采用60％的四氯化碳(CCl_4)及5％的乙醇制备肝纤维化动物模型,分别用小剂量、大剂量大黄酸(25 mg/kg,100 mg/kg体重)干预,测定血清丙氨酸氨基转移酶(ALT)、透明质酸(HA)、Ⅲ型前胶(PC-Ⅲ)及肝组织丙二醛(MDA)含量,免疫组化方法观察转化生长因子 β1(TGF-β1)、α平滑肌肌动蛋白(α-SMA)的表达情况,并观察肝组织胶原面积及病理变化.结果:大黄酸组较模型组:(1)血清ALT、HA、PC-Ⅲ水平及肝组织中MDA含量显著降低(P<0.01);(2)肝组织中TGF-β1,α-SMA的表达显著减少(P<0.05或P<0.01);③肝组织胶原面积明显减少,纤维化程度明显改善(P<0.05或P<0.01).结论:大黄酸具有保肝作用和抑制肝纤维化作用,其作用机制可能与其抗炎、抗氧化作用及抑制HSC活化、抑制TGF-β1作用有关.     

Modulation of the course of CCl4-induced liver injury by the anti-calmodulin drug thioridazine

Thioridazine (TDZ) administration to rats (50 mg/kg i.p.) 6 or 10 h after CCl4 treatment (1 ml/kg in olive oil i.p.) partially prevented necrogenic effects of this compound at 24 h but not at 72 h. TDZ did not have inhibitory effects on CCl4 activation, covalent binding (CB) of reactive metabolites to cellular constituents or CCl4-induced lipid peroxidation (LP). Moreover, TDZ had enhancing effects on both LP and CB. TDZ was able to increase protein and phospholipid synthesis and slightly but significantly enhanced protein but not phospholipid degradation in livers from control rats. TDZ administration decreased calcium liver content in CCl4-poisoned animals but did not change the intensity of CCl4-induced fatty liver. TDZ lowered body temperature in CCl4-treated animals during the 24 h observation period. These results and previous studies from our laboratory suggest calcium and calmodulin (CaM) participation in the CCl4 necrogenic effects on the liver but not in the hepatotoxin-induced fatty liver. TDZ-lowering effects on body temperature might also be a determinant in the delaying effects of this drug on the onset of CCl4-induced necrosis. Present experiments did allow discrimination between these two or other possible mechanisms for TDZ modulation effects.     

Excessive hepatic accumulation of intracellular Ca2+ in chlordecone potentiated CCl4 toxicity

The possible role of Ca2+ in chlordecone potentiation of CCl4 hepatotoxicity was examined in male Sprague-Dawley rats. The rats were maintained on a diet containing either 0, 10, 25, 50 or 100 ppm chlordecone for 15 days. On day 15, they received a single i.p. injection of corn oil (1 ml/kg) or CCl4 (100 microliter/kg) in corn oil vehicle. The animals were killed at 1, 6, or 12 h after the oil or CCl4 challenge for hepatic Ca2+ determinations. Ca2+ in whole liver, mitochondria, microsomes or in cytosolic fraction was unaltered in any group of animals receiving chlordecone + oil treatments, indicating that chlordecone alone does not alter whole liver content or hepatic subcellular distribution of Ca2+, even after exposure to toxic levels (50 or 100 ppm). Administration of CCl4 at an otherwise non-toxic dose to chlordecone treated animals resulted in significant increases of whole liver and subcellular Ca2+ as compared to chlordecone alone and CCl4 alone with a characteristic biphasic response. These increases were significant at all 3 time points in whole liver, cytosolic and mitochondrial fractions. Microsomal Ca2+ increased only at 12 h after CCl4. The increases were all progressive with increases in dietary levels of chlordecone, indicating that chlordecone-induced sensitivity is responsible for CCl4 elicited perturbations in whole liver and intracellular Ca2+ levels. This study suggests that chlordecone modifies the liver plasma membrane to amplify the CCl4 elicited perturbations in hepatocellular Ca2+ homeostasis especially during 6-12 h after CCl4 administration. This perturbation of Ca2+ homeostasis may be related to the arrested repair and regeneration of damaged liver tissue leading to progressive deterioration observed in previous histomorphometric studies.     

Improvement of phase I drug metabolism with Schisandra chinensis against CCl4 hepatotoxicity in a rat model

The seed extract of Schisandra chinensis was investigated in the rat for its restorative or therapeutic effect on Phase I hepatic drug metabolism following intoxication by carbon tetrachloride (CCl4). Male Sprague Dawley rats (220-250 g) were divided into two sets, one included rats with or without CCl4 intoxication, the other included CCl4 intoxicated rats with or without treatment of Schisandra extract. With the treatment regimen, rats received four oral doses of Schisandra (160 mg/kg) or the same volume of water at 8, 24, 32 and 48 h after CCl4 intoxication. A single oral dose (80 mg/kg) of antipyrine, a conventional probe for oxidative drug metabolism, was then administered. The levels of liver serum transaminases and cytochrome P450 were measured and the pharmacokinetics of antipyrine were assessed using a non-compartmental approach via WinNonlin. In comparison to the rats without CCl4 intoxication (t1/2: 2.2 +/- 0.9 h; Cl/F: 0.30 +/- 0.01 L/h/Kg; P450: 0.611 +/- 0.190 nmol/mg protein), CCl4 administration significantly decreased elimination (t1/2: 12.0 +/- 3.9 h) and oral clearance (Cl/F: 0.049 +/- 0.018 L/h/kg) of antipyrine, and markedly reduced the content of P450 (0.075 +/- 0.011 nmol/mg protein). Data obtained from intoxicated animals treated by Schisandra extract, compared to those without treatment, showed significant (p < 0.05) improvement in the t1/2 (4.45 +/- 1.7 h) and Cl/F (0.096 +/- 0.018 ml/h) estimates of antipyrine and a 2-3 fold increase in P450 level (0.190 +/- 0.072 nmol/mg protein). Findings in this study suggest that the seed extract of Schisandra appeared to be a promising agent for the improvement of Phase I oxidative metabolism in the liver damaged by CCl4.     

Development of dosage design of hepatic metabolizing drugs using serum albumin level in chronic hepatic failure

We have previously reported good correlations among serum aminotransferase (AST) activity, metabolic enzyme activity of CYPs, and total clearance (CL(tot)) of probe drugs in rats with acute hepatic failure induced by CCl4. In this study, we searched for new biochemical indicators that correlate with hepatic function and tried to simulate appropriate drug dosage in chronic hepatic failure. Model rats were prepared by administration of CCl4 (1 ml/kg, s.c., 3 times/week) and used at 48 h after the last administration. Serum albumin concentration was time-dependently decreased and correlated well with 3 major biologic determinants of drug clearance, hepatic blood flow (HBF), intrinsic clearance (CL(int)), and the unbound fraction of drugs in plasma (fp) after intravenous administration of cyclophosphamide, tolbutamide, zonisamide, and chlorzoxazone (as probe drugs for low hepatic extraction) and propranolol and lidocaine (as high-hepatic extraction drugs). By calculating these parameters based on prediction equations by the level of albumin, CL(tot) was obtained. As a result of having evaluated this model using administration of cyclosporin, there was a statistically significant relationship between predicted CL(tot) and observed CL(tot). In conclusion, the value of serum albumin level is a useful parameter that correlates well with chronic hepatic function. We have shown that this quantitative administering design using serum albumin level can predict appropriate dosages of hepatic metabolizing drugs in chronic hepatic failure.     

人工虫草菌丝及锌减少肝纤维化大鼠肝脏胶原的沉积

目的观察人工虫草菌丝及葡萄糖酸锌对大鼠四氯化碳实验性肝纤维化肝内胶原沉积的作用.方法用四氯化碳制造雄性Wistar大鼠肝纤维化模型,根据在动物饮水中加入不同药物分为小剂量人工虫草组、大剂量人工虫草组、葡萄糖酸锌组、对照组,并设正常组(不造模).12周后处死动物进行检测.结果造模的4组动物肝脏质量及血清丙氨酸转氨酶(ALT)水平高于正常组,体质量增长低于正常组(均P＜0.05或P＜0.01),人工虫草组及葡萄糖酸锌组动物肝脏羟脯氨酸含量低于对照组(均P＜0.05).病理结果证实对照组肝纤维化程度重于各治疗组.人工虫草组动物尿量多于葡萄糖酸锌组(均P＜0.01).结论人工虫草菌丝和葡萄糖酸锌均可减少大鼠四氯化碳实验性肝纤维化肝内胶原的沉积,机制有待进一步研究.     

The reproductive and developmental toxicity of the antifungal drug Nyotran (liposomal nystatin) in rats and rabbits.

Nyotran is a liposomally encapsulated i.v. formulation of the antifungal polyene nystatin. This drug was evaluated in a series of reproductive toxicity studies, according to the guidelines outlined by the International Conference on Harmonization (ICH). A fertility and early embryonic development study (SEG I) and a prenatal and postnatal development (SEG III) study were conducted in rats, and embryo-fetal development (SEG II) studies were conducted in rats and rabbits. Nyotran was administered iv in all studies. In SEG I and SEG III, rats were administered daily doses of 0.5, 1.5, or 3.0 mg/kg Nyotran. In both studies, parental mortality and toxicity in the 3.0 mg/kg dose group necessitated the lowering of the high dose to 2.0 mg/kg/day. Parental toxicity, in the form of decreased body weights, decreased food consumption, and piloerection were also observed at the 1.5 mg/kg/day dose level in the SEG I and SEG III studies. Despite the parentally toxic doses in the SEG I study, there was no effect of Nyotran on F0 male or female fertility or early embryonic development of F1 offspring. In the SEG III study, lactational body weights of the F1 generation were decreased at all Nyotran dose levels. There was no effect on pre-wean developmental landmarks, but post-wean development was affected by Nyotran administration at all dosage levels. Preputional separation was delayed in the 1.5 and 3.0/2.0 mg/kg/day F1 offspring, auditory startle function was decreased in F1 females at all dose levels, and motor activity was decreased in male F1 offspring at all dose levels. However, there were no treatment-related effects on the subsequent mating of the F1 generation and resulting F2 offspring. In SEG II studies, rats and rabbits were also administered 0.5, 1.5, or 3.0 mg/kg/day of Nyotran during gestation. The high dose in these SEG II studies was not lowered, as the maternal animals were able to tolerate the shorter duration of dosing. Maternal effects in rabbits were observed only in the high-dose group and were limited to decreased food consumption and decreased absolute and relative liver weight. Decreased food consumption in high-dose dams and clinical weight loss in some animals at the mid- and high-dose levels evidenced maternal toxicity in rats. Nyotran did not have any effect on Caesarian section parameters in either rats or rabbits and no effect on the incidence of fetal malformations in rabbits. A statistically significant increase in mild hydrocephaly, observed in 4 rat fetuses, was seen at the highest dose level of 3.0 mg/kg/day. The biological significance and relationship to Nyotran treatment of this finding is not clear. This finding may represent a change in the background incidence or a change in the pattern of responsiveness of this strain of rat fetus to the test chemical. Toxicokinetic data were also collected in the SEG II rabbit and rat studies for comparison to human exposures. In both species, systemic exposure to the nystatin at effective antifungal concentrations was demonstrated. The systemic exposures in rats and rabbits were, however, considerably less than have been reported in humans administered clinical doses of 2 or 4 mg/kg/day Nyotran. Thus, humans tolerate higher dosages and systemic exposures of Nyotran relative to rats and rabbits and there is no margin of safety in either dosage level or systemic exposure to drug. Given this lack of a margin of safety and the effects on postnatal development in F1 rats, caution should be exercised when using this drug in females of childbearing potential.     

三氧化二砷、黄磷、四氯化碳的急性肝脏毒作用的研究

大鼠每日分别经口染毒三氧化二砷（45mg/kg)、黄磷（3mg/kg)、四氯化碳（990mg/kg)，连续4日后，均出现肝脏病理改变，黄磷及四氯化碳组大鼠的血清GPT和GOT活性明显升高，但三氧化二砷组则无显著变化，三个染毒组大鼠的血清和肝微粒体过氧化脂质含量、血清IgM和补体C3含量均较对照组显著升高。     

Cardiovascular effects of 3-mercaptopropionic acid and levels of GABA in regions of the brain of guinea-pigs

3-Mercaptopropionic acid (3-MP), an inhibitor of the synthesis of gamma-aminobutyric acid (GABA), was administered to anesthetized rats and guinea-pigs in order to examine the relationship between the effect of this agent on regional levels of GABA in the brain and cardiovascular function. After a latent period, 3-mercaptopropionic acid (0.16 ml/kg, i.p.) produced initial increases in blood pressure and heart rate in rats followed by vagal bradycardia and hypotension. Guinea-pigs treated with 3-mercaptopropionic acid developed one of three patterns of cardiovascular changes. The type I response consisted of a period of sympathetically-mediated hypertension and tachycardia followed by vagal bradycardia. Type II animals exhibited increased arterial pressure and heart rate, but no vagal activation. Type III and control animals exhibited no significant cardiovascular changes following administration of 3-mercaptopropionic acid or appropriate vehicle. Regional levels of GABA in brain, measured at 90 min after treatment were significantly lower than control in type I and II animals in 3 of 4 areas of the brain measured, but not in type III guinea-pigs. When decreases in levels of GABA were compared to the changes in cardiovascular parameters for individual animals, the decrease in heart rate at the time of sacrifice was directly correlated with the decrease in medullary levels of GABA in type I animals. Conversely, in type II guinea-pigs, decreases in hypothalamic levels of GABA correlated inversely with heart rate at sacrifice. These results suggest that activation of cardiac sympathetic and parasympathetic nervous pathways following the administration of 3-mercaptopropionic acid may result from decreased levels of GABA in different regions of the brain.     

Protective mechanism of salvia miltiorrhiza on carbon tetrachloride-induced acute hepatotoxicity in rats

The purpose of this study was to investigate the possible mechanisms of Salvia miltiorrhiza (Sm) in carbon tetrachloride (CCl(4))-induced acute hepatotoxicity in rats. Male Wistar rats received a single dose of CCl(4) (2 ml/kg in corn oil, intraperitoneally). Three hours after CCl(4) intoxication, rats received either Sm (100 mg/kg) or silymarin (100 mg/kg) by gastrogavage twice a day for 2 consecutive days. CCl(4)-induced liver damage was shown by significant elevation of serum aminotransferase levels. Additionally, a significant decrease was observed in hepatic microsomal P450 2E1 protein content and hepatic concentrations of antioxidant enzymes. In contrast, rats given both Sm and silymarin supplement had less elevation of serum aminotransferase concentrations associated with less severe lobular damage of hepatocytes than rats receiving CCl(4) alone. Sm administration restored the reduction of hepatic microsomal P450 2E1 protein content as well as inducing an increase in hepatic glutathione concentration. On the other hand, administration of silymarin resulted in an elevation of hepatic superoxide dismutase levels. Moreover, both Sm and silymarin treatment inhibited the elevation of hepatic inducible nitric oxide (iNOS) protein content and nitrite concentration in liver homogenate 24 h after CCl(4) intoxication. We concluded that administration of Sm is effective in amelioration of CCl(4)-induced hepatotoxicity. This effect may be due to its ability to decrease the metabolic activation of CCl(4) by an increase in P450 2E1 protein content and its antioxidant activity associated with less increase in hepatic iNOS protein content.