Brain regional thallium distribution in rats acutely intoxicated with Tl2SO4

The content of thallium in seven body organs and eight brain regions of rats acutely exposed to Tl₂SO₄ was compared. Rats received a single i.p. injection of Tl₂SO₄ at three doses: 16, 32 and 48 mg/kg. At 24 h after treatment, thallium content in kidney was higher than in all other organs studied and whole brain had the lowest thallium concentration. A thallium differential distribution was found among brain regions. The highest thallium concentration was found in the hypothalamus and the lowest in the cortex. This distribution pattern was similar with the three doses used. Time course of thallium accumulation in brain was found to be considerably more rapid in the hypothalamus than in other regions, particularly the cortex, suggesting differences in thallium entry into brain parenchyma. Thallium brain regional differential distribution might be related to some of the symptoms of thallium central neurotoxicity.     

Hepatoprotective and immunomodulatory properties of Tinospora cordifolia in CCl4 intoxicated mature albino rats

Effect of Tinospora cordifolia extract on modulation of hepatoprotective and immunostimulatory functions in carbon tetrachloride (CCl4) intoxicated mature rats is reported here. Administration of CCl4 (0.7 ml/kg body weight for 7 days) produces damage in the liver as evident by estimation of enzymes such as serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transminase (SGPT) and alkaline phosphatase (ALP) as well as serum bilirubin level. CCl4 administration also causes immunosuppressive effects as indicated by phagocytic capacity, chemotactic migration and cell adhesiveness of rat peritoneal macrophages. However, treatment with T. cordifolia extract (100 mg/kg body weight for 15 days) in CCl4 intoxicated rats was found to protect the liver, as indicated by enzyme level in serum. A significant reduction in serum levels of SGOT, SGPT, ALP, bilirubin were observed following T. cordifolia treatment during CCl4 intoxication. Treatment with T. cordifolia extract also deleted the immunosuppressive effect of CCl4, since a significant increment in the functional capacities of rat peritoneal macrophages (PM phi) was observed following T. cordifolia treatment. The results of our experiment suggest that treatment by T. cordifolia extract may be the critical remedy for the adverse effect of CCl4 in liver function as well as immune functions.     

Heterogeneity of changes on the disposition of aspirin in rats with CCl4-induced chronic liver damage

The profile of urinary salicylate metabolites was determined after the oral administration of acetylsalicylic acid (ASA) to CCl4-cirrhotic rats, CCl4-cirrhotic rats treated with colchicine for 1 month, and control groups. The following enzymatic activities were determined: liver and plasma ASA-esterase, liver UDP-glucuronyltransferase, and liver aniline hydroxylase. The time-course of plasma concentration of salicylates in similar groups was followed after the intraperitoneal administration of salicylic acid (SA) or gentisic acid (GA). The cirrhotic animals showed a lack of urinary glucuronates and an increase in urinary gentisic and salicylic acids. The activities of plasma and liver ASA-esterases were increased significantly in cirrhosis, whereas aniline hydroxylase was reduced and UDP-glucuronyltransferase remained unchanged. The plasma half-lives of salicylates were reduced in the cirrhotic animals regardless of the administered parent compound. Colchicine treatment reversed almost completely the alterations. The heterogeneity of liver metabolic dysfunctions present in chronic liver disease was demonstrated. It is emphasized that the pharmacokinetic alterations produced by liver damage are the result of a complex set of factors involving changes in the hepatic circulation, protein binding, and the existence of other routes of elimination.     

Haemodynamic alterations in anaesthetized and acutely intoxicated newborn piglets.

1. We investigated the haemodynamic alterations in 2-day old anaesthetized piglets after acute ethanol intoxication using the microsphere technique. 2. After ethanol infusion, mean arterial blood pressure (MABP) decreased by 6%, cardiac output (CO) decreased by 26%, heart rate (HR) increased by 20% and systemic vascular resistance (SVR) increased by 36%. 3. Arterial perfusion to the kidneys, gastrointestinal (GI) organs and carcass decreased by 39%, 34% and 26%, respectively. 4. In piglets pretreated with 4-methylpyrazole (4-MP), an alcohol dehydrogenase inhibitor, the decrease in MABP and increase in HR were not observed after ethanol infusion, but the reduction in CO and increase in SVR were maintained. 5. Arterial blood flow to the GI organs and carcass, but not the kidneys, remained at significantly reduced levels. 6. These observations indicate that ethanol can adversely affect CO and arterial perfusion to GI and musculoskeletal structures while metabolites of ethanol, such as acetaldehyde, affect MABP and HR. Therefore, the clinical effects observed after acute ethanol intoxication in neonates may vary with their rate of ethanol metabolism.     

Chlordecone potentiation of CCl4 hepatotoxicity in ovariectomized rats

Previous reports from this laboratory have established the propensity of chlordecone to potentiate the hepatotoxicity and lethality in male and female rats. The present study was designed to investigate the hepatotoxicity of CCl4 in chlordecone (CD) pretreated, ovariectomized rats. Ten days after bilateral ovariectomy, the rats were maintained on a dietary protocol of either 0 or 10 ppm chlordecone and on the day 15, they received a single i.p. injection of either corn oil (1 ml/kg) or 25 microliter CCl4/kg in corn oil. Hepatic function, serum enzyme levels and histopathological changes were assessed 24 h after CCl4 challenge as functional biochemical, and morphological parameters of hepatotoxicity. Hepatobiliary function was markedly impaired and serum enzyme levels were elevated in ovariectomized rats receiving the same treatment but not significantly different from normal females receiving the chlordecone and CCl4 combination. Histological findings indicated a greater degree of centrilobular hepatic necrosis accompanied by extensive fatty infiltration. This study suggests that chlordecone sensitizes the liver in ovariectomized rats as well to amplify the toxic effects of CCl4.     

Adrenocortical changes and uptake of 4-14C-corticosterone in rats intoxicated with fenitrothion

A significant increase in plasma corticosterone levels and depletion of ascorbic acid content in adrenal glands occurred in rats between 1 and 5 h after a single dose (50% LD₅₀) of fenitrothion, returning to normal levels within 12 h; brain AChE activity decreased to about 59–43% and significant inhibition of the enzyme was observed for up to 24 h after intoxication. Repeated dosing with fenitrothion (2.5% LD₅₀) for 14 days caused insignificant elevation of plasma corticosterone levels, while brain AChE activity was inhibited to about 19% of control values and uptake of 4-¹⁴C-corticosterone in tissues was significantly diminished.     

The impaired disposition of probe drugs is due to both liver and kidney dysfunctions in CCl(4)-model rats

The carbon tetrachloride (CCl(4))-treated model involving mature Sprague-Dawley rats has been historically relied upon to study liver injury and regeneration and to test drug efficacy and disposition. However, there few studies about phase II metabolic enzymes changes in CCl(4)-model rats. The metabolic and excretion tests of phenacetin and acetaminophen (APAP), and the mRNA test of cytochrome P4501A2 (CYP1A2) and phase II metabolic enzymes [sulfotransferase 1A1 (SULT1A1) and UDP-glucuronosyltransferase 1A6 (UGT1A6)] were studied in model rats after CCl(4) pretreatment. The result showed that the function and structure of liver and kidney was impaired by CCl(4) pretreatment, and a significant difference has been observed in the mRNA content of CYP1A2 (p<0.01) in model group, but there was no significant difference on the mRNA content of SULT1A1 and UGT1A6 in both groups. Compared to the control group, a significant higher content of phenacetin (p<0.01) and sulfate-APAP (AS, p<0.01) was observed in the metabolic tests of phenacetin and APAP. Statistically significant differences in cumulative urinary excretion levels of APAP, AG and AS for CCl(4) model rats were observed also. We have shown that impaired disposition of probe drugs in this model was due to both liver and kidney dysfunction in CCl(4)-model rats and we should consider the development of a new liver damage model without renal impairment.     

Pharmacokinetics of diclofenac in rats intoxicated with CCL4, and in the regenerating liver

The pharmacokinetics of an intravenous and oral diclofenac dose of 3.2 mg/kg was studied in male Wistar rats under control conditions, 1 and 3 days after liver damage and regeneration induced by an oral injection of CCl(4). One day after CCl(4) administration, indicators of necrosis (alanine aminotransferase), cholestasis (gamma-glutamyl transpeptidase) and regeneration (alpha-fetoprotein) were significantly increased; these effects were reversed after 3 days. In nonintoxicated rats, t(1/2) was 43.83 +/- 4.95 min, V(d) was 0.37 +/- 0.04 l/kg, Cl was 129.21 +/- 9.20 ml/min kg, AUC(i.v.) was 25.62 +/- 1.45 microg/min ml, and AUC(p.o.) was 20.21 +/- 1.03. One day after intoxication, when the liver was damaged and regenerating, the metabolism was decreased: diclofenac t(1/2) was increased to 258.21 +/- 30.80 min but V(d) did not change significantly, therefore Cl was reduced to 32.81 +/- 3.38 ml/min kg. By day 3 after intoxication, liver function, regeneration and pharmacokinetics returned to normal. The results show that liver damage and regeneration increases the bioavailability by decreasing elimination. The present observations suggest that reduction of the pharmacokinetic parameters may lead to drug accumulation in the regenerating-damaged liver with an attendant possible increase in toxic effects. The results in rats, also suggest that once hepatic injury is finished and regeneration is complete, diclofenac can be administered normally.     

Deferoxamine alleviates liver fibrosis induced by CCl4 in rats

Several chronic liver diseases can lead to the occurrence of hepatic fibrosis through the accumulation of iron, which causes induction of oxidative stress and consequently activation of fibrogenesis. The present study was designed to investigate the potential antifibrotic and anti‐oxidant effects of deferoxamine (DFO), a well‐known iron chelator in an experimental rat model of liver injury using carbon tetrachloride (CCl₄). First, the potential effective dose of DFO was screened against CCl₄‐induced acute hepatotoxicity. Then, rats were co‐treated with DFO (300 mg/kg, i.p.) for 6 weeks starting from the third week of CCl₄ induction of chronic hepatotoxicity. Liver function was assessed in addition to histopathological examination. Furthermore, oxidative stress and fibrosis markers were assessed. It was found that treatment of animals with DFO significantly counteracted the changes in liver function; histopathological lesions and hepatic iron deposition that were induced by CCl₄. DFO also significantly counteracted the CCl₄‐induced lipid peroxidation increase and reduction in antioxidant activities of superoxide dismutase and glutathione peroxidase enzymes. In addition, DFO ameliorated significantly liver fibrosis markers including hydroxyproline, collagen accumulation, and the expression of the hepatic stellate cells (HSCs) activation marker; alpha smooth muscle actin and transforming growth factor‐beta (TGF‐β). Together, these findings indicate that DFO possesses a potent antifibrotic effect due to its antioxidant properties that counteracted oxidative stress and lipid peroxidation and restored antioxidant enzymes activities as well as reducing HSCs activation and fibrogenesis.     

Antioxidant defense system in rats simultaneously intoxicated with agrochemicals

The effect of dimethoate, zineb and glyphosate administered alone or in combination on liver, kidney, brain and plasma antioxidant defense system was investigated. Lipid peroxidation, and RNS production were increased in all tissues studied, especially in those groups that received a combination of drugs. Intoxicated rats exhibited lower antioxidant ability, higher oxidized protein and glutathione levels in plasma with a decreased concentration of α-tocopherol in brain and liver, between 30% and 60% of control. Superoxide dismutase was decreased in liver and brain. Glutathione reductase was inhibited in liver while glutathione peroxidase and transferase were unaffected. Plasma lactate dehydrogenase and γ-glutamyl transpeptidase activities were both increased. The associations of drugs produce more damage than individual administration being the effects observed strongly dependent on the kind of tissue analyzed. In conclusion, the present paper evidenced both the role of the oxidative stress as a mechanism of action of some pesticides and the potential additive effects of a simultaneous exposure to more than one compound. In addition, results suggest a potential contribution of pesticide mixtures to the aetiology of some neurodegenerative diseases.     

3－硝基丙酸染毒大鼠的神经病理变化

用２０，４０和８０ｍｇ／ｋｇ三种剂量的３－硝基丙酸灌胃染毒２４只大鼠，观察中毒后神经病理改变。结果表明：３－硝基丙酸的主要损伤部位是尾－壳核。电镜检查可见神经元胞浆疏松，，核染色质积聚，最后胞浆和核均发生固缩。髓鞘变薄或断裂，轴索膜与髓鞘间水肿。星形胶质细胞水肿，血管周围有肿胀的突起，此与缺血性脑病理改变无明显差别。     

Accelerated liver recovery after acute CCl4 poisoning in rats treated with sodium phthalhydrazide

Pharmacotherapy of hepatobiliary disorders is an important issue due to the high prevalence of liver failure, toxic and viral hepatitis and cirrhosis. The number of stimuli that can potentially induce or accelerate liver recovery is limited; in our study we selected sodium phthalhydrazide, which has been found to promote liver regeneration after partial hepatectomy. We examined the effects of phthalhydrazide on liver morphometric, histological and biochemical parameters in rats intoxicated with CCl₄. Accelerated liver recovery after CCl₄ intoxication in phthalhydrazide-treated animals was evidenced by increased number of liver sinusoidal cells, reduced focal necrosis of hepatocytes and reduced perifocal leukocyte infiltration. Decreased plasma levels of pro-inflammatory cytokines TNF-α and IL-18 and decreased concentrations of IL-6 and IFN-γ in liver homogenates were associated with reduced severity of cholestasis and normalized hepatic protein synthesis in CCl₄-intoxicated rats exposed to phthalhydrazide. Anti-inflammatory and immunomodulating properties of phthahlhydrazide can be an important factor contributing to accelerated liver recovery at early stages of acute CCl₄-toxic liver impairment.     

软肝片抗肝纤维化作用的实验研究

目的探讨软肝片对四氯化碳中毒性肝纤维化的防治作用。方法用四氯化碳皮下注射造成大鼠肝纤维化模型 ,以联苯双酯作为阳性对照 ,测定血清丙氨酸氨基转移酶 (ALT)、天冬氨酸氨基转移酶 (AST)、玻璃酸(HA)、唾液酸及肝组织羟脯氨酸 (Hyp)、丙二醛 (MDA)、超氧化物歧化酶 (SOD)含量 ,以反映肝细胞损伤及肝纤维化程度。结果软肝片可明显降低肝纤维化大鼠血清ALT、AST、HA、唾液酸水平及肝组织Hyp和MDA水平 ,提高肝组织中SOD活力。结论软肝片具有一定的抗肝纤维化及抗脂质过氧化作用。     

Hepatic ATP content and hyperammonemia induced by CCl4 in rats

An investigation of the mechanism of development of hyperammonemia observed in CCl4-induced hepatic encephalopathy was performed in rats. CCl4 (1.0 ml/kg 3 times per week for over 10 weeks) caused a severe hyperammonemia and depletion of hepatic ATP contents in only those rats with hepatic encephalopathy. However, CCl4 (1.0 ml/kg 3 times per week for 7 weeks) did not cause hepatic encephalopathy and did not change in blood ammonia levels. Administration of 2,4-dinitrophenol (2,4-DNP) in these CCl4-treated rats caused hepatic encephalopathy within 30 min after injection and then the increase of 140 micrograms/dl in blood ammonia levels and the decrease of 80% in hepatic ATP contents were observed. However, the administration of 2,4-DNP in CCl4-untreated rats did not cause hepatic encephalopathy within 30 min after injection although the increase of 70 micrograms/dl in blood ammonia levels and the decrease of 80% in hepatic ATP contents were observed. Hepatic activities of carbamylphosphate synthetase (CPS) and argininosuccinate synthetase (ASS), important enzymes of the urea cycle, were significantly inhibited by 85% and 60% respectively, in rats treated with CCl4 plus 2,4-DNP. However, in rats treated with 2,4-DNP and without CCl4, the hepatic activities of CPS and ASS were inhibited only 25% and 0%, respectively. These findings suggest that the severe hyperammonemia, which may be produced by the decrease of hepatic ATP content and the inhibition of CPS and ASS, may play an important role in induction of hepatic encephalopathy.     

Biliary secretory function in rats chronically intoxicated with aluminum.

The effects of a chronic aluminum (Al) exposure on biliary secretory function, with special emphasis on hepatic handling of non-bile salt organic anions, was investigated. Male Wistar rats received, intraperitoneally, either 27 mg/kg body weight of Al, as Al hydroxide [Al (+) rats], or the vehicle saline [Al (-) rats] three times a week for 3 months. Serum and hepatic Al levels were increased by the treatment (approximately 9- and 4-fold, respectively). This was associated with enhanced malondialdehyde formation (+110%) and a reduction in GSH content (-17%) and in the activity of the antioxidant enzymes catalase (-84%) and GSH peroxidase (-46%). Bile flow (-23%) and the biliary output of bile salts (-39%), cholesterol (-43%), and proteins (-38%) also decreased. Compartmental analysis of the plasma decay of the model organic anion bromosulphophthalein revealed that sinusoidal uptake and canalicular excretion of the dye were significantly decreased in Al (+) rats (-53 and -43%, respectively). Expression of multidrug resistance-associated protein 2 (Mrp2), the main, multispecific transporter involved in the canalicular excretion of organic anions, was also decreased (-40%), which was associated with a significant decrease in the cumulative biliary excretion of the Mrp2 substrate, dinitrophenyl-S-glutathione (-50%). These results show that chronic Al exposure leads to oxidative stress, cholestasis, and impairment of the hepatic handling of organic anions by decreasing both sinusoidal uptake and canalicular excretion. The alteration of the latter process seems to be causally related to impairment of Mrp2 expression. We have addressed some possible mechanisms involved in these deleterious effects.     

Histochemical detection of the in vivo produced cellular aldehydes by means of direct Schiff's reaction in CCl4 intoxicated rat liver

A histochemical technique for detection of the in vivo induced cellular aldehydes based on the direct Schiff's reaction is reported in this paper. CCl₄-intoxicated rat liver was used as an experimental model. Fresh and non-pretreated rat liver cryostat sections fixed in 10% formol calcium solution and washed in distilled water were exposed to Schiff's reagent. The sections were then immersed in two baths of sodium bisulphite solution, then in water, dehydrated in ethanol, cleared in xylene and mounted in a synthetic anhydrous mounting medium. As Schiff positive areas presented well circumscribed foci which increased with time following intoxication, semiquantitative planimetric measurements were feasible. The direct Schiff's reaction detects cellular aldehydes in a sensitive, rapid, histologically and topographically estimable way. The appearance of these aldehydes precedes distinctly morphological alterations detectable by other histochemical or histological techniques. No positive results were obtained in control, non-intoxicated rat livers. Inhibition of this direct Schiff's reaction was obtained in positive control rat liver sections preincubated in solutions of aldehyde blockers. Histochemical detection of aldehydes may give useful information on different aspects of tissue and organ intoxication such as their topography, appearance, evolution, extension, consequences and effects of treatment. The direct Schiff's reaction can be considered as a valuable tool in fundamental and applied research dealing with various toxicological, environmental, pathological, cancer-related and therapeutic problems.     

Cardiomyopathy in Soman and Sarin intoxicated rats

Rats surviving various single dose of the organophosphorus anticholinesterase nerve agents Soman and Sarin were examined by light microscopy at intervals up to 35 days post-exposure. Brain lesions, identical to those that have been reported elsewhere were present, as well as a previously unreported finding associated with Soman or Sarin intoxication: half of all animals that had brain lesions also had areas of myocardial degeneration and necrosis. Depending upon the point in time at which cardiac tissues were examined, findings varied from areas of acute myolysis and necrosis to areas undergoing resolution of damage. The finding of brain lesions in those animals having cardiac lesions suggests a relationship between the convulsion induced neurologic and cardiac lesions. These studies suggest that convulsive doses of chemical warfare agents induce pathological changes in the cardiovascular system of laboratory animals.