13-cis-retinoic acid and hepatic steatosis in rats

The effect of administration of 13-cis-retinoic acid (100 mg/kg diet) on lipid metabolism was examined in male rats fed either a 20% casein + 0.3% methionine diet, a 20% casein diet, a 10% casein + 0.3% methionine diet, or a 10% casein + 0.6% methionine diet for 10 days. Hepatic triglyceride concentrations of rats fed either 10% casein diet were 3-fold greater than animals receiving diets containing 20% casein. The addition of 13-cis-retinoic acid to the diet further increased the total hepatic lipid (43-56%) and triglyceride (approximately 2-fold) concentrations in rats fed the 10% casein diets. 13-cis-Retinoic acid supplementation did not alter the total liver lipid or triglyceride concentrations in rats fed either of the 20% casein diets. Thus, under specific dietary conditions, the administration of 13-cis-retinoic acid resulted in a marked accumulation of hepatic lipids which did not appear to be related to the total methionine content of the diet nor to the hepatic concentrations of S-adenosylmethionine and glutathione. In addition, all four groups of 13-cis-retinoic acid-fed rats exhibited elevations in the concentration of serum triglycerides, and 10-20% reductions in serum cholesterol concentrations.

Targeted expression of a toxin gene to adipose tissue: transgenic mice resistant to obesity

Obesity is characterized by increased adipose tissue mass and is often accompanied by a number of other disorders, such as diabetes, hypertension, and hyperlipidemia. To investigate the interrelationship between excessive adipose tissue mass and these associated disorders, we have attempted to reduce adiposity via targeted expression of an attenuated diphtheria toxin A chain to adipose tissue, using the 5' regulatory region of the adipocyte P2 (aP2) gene. Transgenic mice with high levels of toxin expression developed chylous ascites and died shortly after birth. Transgenic mice expressing lower levels of the transgene had normal adiposity and survived to adulthood; however, they showed a complete resistance to chemically induced obesity. Nevertheless, these animals developed hyperlipidemia equal to or greater than their nontransgenic obese littermates. Moreover, MSG-treated transgenic females were fertile, unlike their obese nontransgenic littermates. These data demonstrate the feasibility of gentle manipulation of adiposity and allow a functional dissection of obesity and its metabolic sequelae.

On the mechanism of protective action of cold acclimatization against carbon tetrachloride- and ethionine-induced fatty liver

In this study the hepatic lipoprotein lipase (LPL) activity was evaluated in adult female mice acclimatized at 5 degrees C and submitted to carbon tetrachloride (CCl4) or ethionine, in order to determine the possible role of this enzyme in the fatty liver. The results were compared with those obtained in mice kept at room temperature (27 degrees C) that received the same hepatoesteatosis inducing agent. In contrast to animals kept at room temperature, in cold acclimatized mice neither the enhancement of the LPL-liver activity by the action of CCl4 or ethionine occurred nor the development of fatty infiltration in the liver was observed. We conclude that the low temperature induced a protective effect against CCl4- or ethionine-induced fatty liver that was correlated with the no-increase of the hepatic LPL activity.

Comparative effects of aflatoxins G1 and B1 at levels within human exposure limits on mouse liver and kidney

ddy mice were exposed to aflatoxins B1 and G1 via their feed (4.8 ng AFG1, 0.8 ng AFB1 or both/kg body wt./day) while in utero. At six months of age, hepatorenal studies were carried out. The AFG1 caused significant accumulation of only neutral fat in the liver, a slight rise in serum triglyceride and intensified hepatorenal inflammation, necrosis and bile duct proliferation. The AFB1, caused the accumulation of both neutral fat and fatty acids in the liver, and was cytotoxic to the liver and kidney. Iron storage of the liver, hematological indices, serum total protein and albumin levels were not affected by the aflatoxins.

Transient focal hepatic defects related to sustained-release niacin

Hepatotoxicity is a potential side effect of niacin therapy for hypercholesterolemia, ranging from mild aminotransferase elevation to fulminant hepatic failure. Although uncommon with plain forms, liver dysfunction has increasingly been associated with sustained-release preparations. This case illustrates transient focal liver defects seen on computed tomography with symptomatic elevation of liver-associated enzymes during treatment with sustained-release niacin. The masses were not evident on radionuclide liver scan, suggesting focal fatty liver. After niacin was discontinued, these abnormalities resolved, and aminotransferases returned to normal. This is the first such reported case.

A rat fatty liver transplant model

A rat model of fatty liver transplantation has been developed to study primary nonfunction in fatty liver grafts. ACI rats were fed with a diet deficient in choline and methionine for 7, 14, 28, and 42 days. Fat content in the pretransplant livers was examined by gas chromatography and histology. The main constituent of the fatty droplets was determined to be triglyceride. The triglyceride concentration reached a maximum by day 14 and remained constant for an additional 28 days. Histology revealed an absence of necrosis in 14- and 28-day fatty livers but scattered hepatocytic necrosis and inflammation in 42-day fatty livers. After being given cold (UW stored, 4 degrees C) or warm (37 degrees C) ischemia, the fatty liver was orthotopically transplanted into normal ACI rats. The one-week survival of fatty liver grafts after 6, 12, 18, and 24 hr cold preservation was 5/5, 5/6, 3/8, 0/6 for 14-day fatty liver and 5/5, 4/6, 0/8, 0/6 for 42-day fatty livers. The survival of normal liver grafts was 5/5, 6/6, 5/9, 2/8, respectively. Increased survival rate was correlated with the absence of hepatocytic necrosis. The survival after 15 and 30 min warm ischemia prior to transplant was 5/5, 2/6 for normal liver grafts and 4/7, 0/6 for 28-day fatty liver graft, respectively. Fatty livers were less resistant to damage induced by cold or warm ischemia.

Ethanol and hydrazine sulfate induced chronic hepatic injury in rats: the curative effect of administration of glucogenic amino acids

There is a widespread belief that when ethanol is fed to rats for a long time, it produces only fatty degeneration without necrosis or fibrosis. In this study, hydrazine sulfate, an inhibitor of low Km ALDH and gluconeogenetic enzymes, was fed with ethanol to rats, and produced more serious pathological changes compared with those found in Lieber's model. Male Sprague-Dawley rats were fed with a low fat liquid diet as a basal diet with ethanol (4%, w/v) and hydrazine sulfate for 4 weeks. At the end of the experiment, plasma aminotransferase levels were found to be elevated. Histological examination showed not only fatty degeneration but also pericellular fibrosis. Therefore, we have evaluated the curative effect of glucogenic amino acids, alanine and glutamine, on this hepatic injury model and found them to be partially protective.

Hepatobiliary complications of total parenteral nutrition

The relationships between various hepatobiliary disorders and the administration of total parenteral nutrition (TPN) were reviewed and, in particular, the role of TPN in their pathogenesis was critically evaluated. Several clinical and pathological entities including steatosis, steatohepatitis, cholestasis, and cholelithiasis have been commonly linked to TPN, and instances of chronic decompensated liver disease have been reported. However, it is concluded that it is often difficult to extricate the effects of TPN on hepatobiliary function from many other hepatotoxic factors that may be operative in these patients. Thus, whereas considerable evidence exists to support a role fro carbohydrate or calorie excess in TPN solutions in the pathogenesis of steatosis, a loss of enteric stimulation and not TPN per se may be the primary factor in the development of cholestasis, biliary sludge, and gallstones. The apparent predilection of infants to TPN-related cholestasis may be based on the relative immaturity of the neonatal biliary excretory system.

[The content of mitochondrial and microsomal cytochromes in liver tissue in experimental drug-induced fatty hepatosis]

Fatty tetracycline-induced steatosis is shown to reduce levels of mitochondrial and microsomal cytochromes. A decrease of microsomal cytochromes in the liver of hypoxia-resistant animals was similar to that of hypoxia-sensitive ones. This decrease was different for hypoxia-resistant and hypoxia-sensitive animals: for the former only cytochrome a declined, in the latter case cytochromes c+, c1 and a.

Induction of fatty liver in cows by ethionine administration and concomitant decreases of serum apolipoproteins B-100 and A-I concentrations

Ethionine, an analogue of methionine, induces fatty liver in rats by inhibiting protein synthesis, including that of apolipoproteins in liver. Ethionine was administered to cows to elucidate the participation in fatty liver development of impaired triglyceride secretion from liver attributable to decreased apolipoprotein synthesis. The administration resulted in a significant increase of liver triglyceride contents. Several apolipoproteins were found to have decreased concentrations. In particular, apolipoprotein B-100 in very low-density (0.95 to 1.006 g/ml) lipoprotein and in low-density (1.006 to 1.063 g/ml) lipoprotein fractions was greatly reduced. The decreases of apolipoprotein B-100 concentrations in the 2 lipoprotein fractions were at least partly correlated to the decreased triglyceride concentrations in the respective fractions. Decreased concentrations of apolipoprotein A-I in high-density (1.063 to 1.210 g/ml) lipoprotein were also observed, although not as distinctly as with apolipoprotein B-100. Total cholesterol and phospholipid concentrations in low- and high-density lipoprotein fractions were decreased. The decrease in cholesterol was attributed to reduced concentrations of cholesteryl esters. It was suggested that the impaired lipid secretion from liver attributable to the decreased apolipoprotein concentrations has a role in ethionine-induced fatty liver of cows.

Liver triglyceride concentration and body protein metabolism in ethanol-treated rats: effect of energy and nutrient supplementation

The objective of this study was to compare the metabolic effects of long-term ethanol consumption with oral (Lieber-DeCarli) and enteral feeding techniques. Enteral feeding allowed administration of greater amounts of energy and nutrients. After 21 days of treatment using the Lieber-DeCarli technique, the ethanol-treated rats had the following significant (P less than 0.05) differences from pair-fed controls: lower cumulative nitrogen balance (days 5-21; 2.8 +/- 0.1 g N vs. 3.5 +/- 0.1 g N), lower protein content of gastrocnemius muscle (289 +/- 17 mg vs. 358 +/- 11 mg) and intestinal mucosa (461 +/- 19 mg vs. 577 +/- 40 mg), higher plasma leucine concentration (147 +/- 8 mumol/L vs. 102 +/- 8 mumol/L), higher liver protein content (2222 +/- 122 mg vs. 1679 +/- 58 mg), and higher liver triglyceride concentration (38.4 +/- 2.8 mg/g vs. 8.7 +/- 1.0 mg/g). When rats received the same amount of nitrogen (1.5 g.kg-1.day-1) and ethanol (13 g.kg-1.day-1) but 16.3% more energy and nutrients by a surgically implanted gastric cannula (enterally fed), the effects of ethanol on nitrogen balance, tissue protein content, plasma leucine concentration, and liver triglyceride concentration were similar to those observed in the rats fed orally. It is concluded that the metabolic effects observed using the Lieber-DeCarli feeding technique are due to ethanol per se and not the synergism of ethanol and undernutrition as recently suggested.

Suppression of aflatoxin B1-induced lipid abnormalities and macromolecule-adduct formation by L-carnitine

The fatty liver and hypolipidemia caused by aflatoxin B1 (AFB1) were studied in male Sprague-Dawley rats fed Purina Rat Chow with or without L-carnitine supplement for 6 weeks. In Experiment 1, the rats (n = 20) were divided into four groups, i.e., nonsupplemented control (NSC), nonsupplemented AFB1 (NSA), carnitine supplemented control (CSC), and carnitine supplemented AFB1 (CSA). The NSA and CSA groups were given an oral dose of [3H]AFB1 (1 mg/kg) 6 hr before kill. In Experiment 2 (n = 10) there were only NSA and CSA groups and they were killed 24 hr post-AFB1 administration. Hepatic and plasma concentrations of total lipid, triglycerides, AFB1-macromolecules adducts and urinary excretion of AFB1 were determined. Carnitine supplementation ameliorated AFB1-induced hepatic steatosis and hypolipidemia. Supplementary carnitine reduced covalent binding of AFB1 to hepatic DNA, RNA, and protein. The carnitine effect was more pronounced after 24 hr than after 6 hr of AFB1 treatment. We conclude that supplementary carnitine suppressed AFB1-induced fatty liver and AFB1-macromolecule adduct formation in the rat.

Altered protein kinase C activity and its endogenous protein phosphorylation in rat liver after administration of ethionine

Ethionine, an ethyl analogue of methionine, induces fatty liver in rats. The effects of ethionine administration on protein kinase C (PKC) in rat liver was examined. By a single administration at a dose of 0.5 mg/g body wt., liver PKC activity was increased in both cytosolic and total particulate fractions. The increase in cytosol was significant, even at 4 h after administration, when compared with control rat liver cytosol. On the other hand, a 4-day consecutive administration (0.5 mg/g per day) resulted in decreased PKC activity, particularly in cytosol, when compared with the control. Protein phosphorylation in liver catalyzed by PKC was found to be enhanced by ethionine, irrespective of the mode of administration. The enhanced phosphorylation was observed in both cytosolic and total particulate fractions. The change of PKC activity, and the phosphorylation of its endogenous substrates, are postulated to be involved in the pathogenesis of ethionine-induced fatty liver of rats.

Changes in fibronectin production in rat liver during cirrhotic evolution due to treatment with CCl4 and steroid hormones: correlation with plasmatic fibronectin

Previous our studies showed that some steroid hormones, as pure crystalline Progesterone (pPc) and 17-alpha-hydroxyprogesterone capronate (17 alpha HPC) heightened the cirrhogenic action produced in rat liver by carbon tetrachloride. Medroxyprogesterone (MPA), however, did not appear to promote cirrhosis, but increased just steatosis. In the present paper, we have studied the above mentioned steroid hormones for their possible capability of inducing changes in plasma fibronectin concentration. For this purpose, the soluble plasma fibronectin level was measured in female rats 45 days after CCl4-induced cirrhosis, and it was compared with the insoluble fibronectin of liver (detected by immunostaining) and the collagen content in the organ. The results obtained show that, after treatment with CCl4 and MPA, both plasma and liver fibronectin content strongly increases, whereas liver collagen content lowers. However, after treatment with CCl4 alone or in association with the other two steroid hormones, any changes in fibronectin content is not observable, but, on the contrary, is evident a heightened collagen production associated with a cirrhotic change of liver.

[Toxicity of an organic Germanium compound: deleterious consequences of a "natural remedy"]

Reports mainly from Japan, recommend germanium (Ge)-containing compounds as "anti-cancer" and "immunostimulatory" remedies. We report on a 25-tear-old woman with stage II HIV disease who consumed a total of 47 g Ge as Ge-lactate-citrate 18%. She developed severe renal insufficiency (creatinine clearance 7 ml/min/1.73 m2, proteinuria 0.28 g/d) and hepatomegaly. Biopsies revealed tubulointerstitial nephropathy with vacuolar degeneration, mainly of distal tubular epithelia, and severe liver steatosis. Tissue Ge content in kidney and liver biopsy specimens was increased 68-and 140 fold respectively. In agreement with previous reports, renal dysfunction persisted 9 months later (creatinine clearance 11 ml/min/1.73 m2).

Decreased estradiol receptor concentrations in ethionine-induced fatty liver of rats

Ethionine, a methionine analogue, induces fatty liver in rats. The mechanism by which ethionine induces fatty liver is thought to be due to the inhibition of synthesis of very-low-density lipoprotein. Since the synthesis of lipoprotein is correlated with liver estradiol receptor concentrations, we examined the effect of ethionine on estradiol receptor concentrations in rat liver. Estradiol receptor concentrations in both cytosolic and nuclear fractions were greatly decreased by a single injection of ethionine at a dose of 0.5 mg/g body wt. In particular, the decrease in nuclear receptor concentrations was observed a few hours after the injection and correlated with the decrease in triglyceride content in the very-low-density lipoprotein fraction. These results suggest that liver estradiol receptor is involved in the pathogenesis of ethionine-induced fatty liver of rats.

Biochemical and immunohistochemical analysis of orotic acid-induced fatty liver

Orotic acid-induced fatty livers were examined by biochemical and immunohistochemical approaches. Lipid peroxide levels by the thiobarbituric acid method and glutathione-peroxidase (GSH-PO) activity in the liver homogenates from orotic administered rats were similar to those of controls. Immunohistochemical localization of GSH-PO in orotic acid-induced fatty liver was mainly observed in the portal zone of the hepatic lobules. This staining pattern of GSH-PO was similar to that of the controls. No remarkable changes in GSH-PO staining patterns were detected in orotic acid-induced fatty liver. Our data strongly suggested that no lipid peroxidation is actively involved in the genesis of fatty liver due to the administration of orotic acid, and GSH-PO a protective enzyme against lipid peroxidation, was not inhibited by orotic acid-induced fatty liver.

Multisystem failure and hepatic microvesicular fatty metamorphosis associated with tolmetin ingestion

Multisystem toxicity including both renal and hepatic failure has been reported with the use of nonsteroidal anti-inflammatory drugs. We report a fatal case of multisystem failure associated with tolmetin ingestion in a 15-year-old girl. Microvesicular fatty change was found in the liver at autopsy. To our knowledge, this is the first reported case of nonsteroidal anti-inflammatory drug-associated multisystem failure to have this histopathologic finding.

Acute encephalopathy with hepatic steatosis induced by pantothenic acid antagonist, calcium hopantenate, in dogs

In Japan, acute encephalopathy with hepatic steatosis resembling Reye's syndrome has been reported to occur after treatment with the pantothenic acid antagonist, calcium hopantenate. We studied the causal relationship and the pathogenesis in dogs. The agent was administered to seven dogs at increasing doses over a period of 8 weeks. Anorexia, vomiting, and diarrhea were common clinical findings. In four dogs, coma suddenly developed after the appearance of gastrointestinal signs. Three animals died during periods when they were not under direct observation. The effects of the agent appear to be related to dose. Laboratory findings representing significant changes at the time of coma included hypoglycemia, leukocytosis, hyperammonemia, hyperlactatemia, and elevated levels of serum transaminases. Microvesicular hepatic steatosis and mitochondrial abnormalities were consistent pathological findings. The hepatic mitochondria were enlarged and characterized by an increased number of cristae and the presence of crystalloid inclusions. In a second group of four dogs, pantothenic acid was given in addition to and in the same amount as calcium hopantenate at increasing doses over a period of 8 weeks. All four dogs survived the 8 weeks and only one developed mild anorexia. No significant biochemical changes were found and neither hepatic steatosis nor mitochondrial abnormalities were observed. The addition of pantothenic acid prevented the development of the disorder in the four animals. These results show that calcium hopantenate produces acute encephalopathy with hepatic steatosis in dogs, by inducing a deficiency of pantothenic acid. The hepatic mitochondrial changes of this reaction differ from those of Reye's syndrome.