Hepatocyte ultrastructural alterations in cocaine users

The ultrastructural examination of liver biopsies from five male cocaine users showed hepatocytes presenting diverse alterations in rough and smooth endoplasmic reticulum, mitochondria, nuclei and microvilli. Lipid deposition and an increase of autophagic vacuoles were also observed. This study demonstrates that the hepatocyte is an important target cell for cocaine toxic effects in some patients.     

Action of metabolic hormones on the fine structure of liver cells. II. Effects of hypophysectomy and chronic administration of somatotropin

Electron microscopic studies of hepatocytes from sham-operated, hypophysectomized, and hypophysectomized rats treated with somatotropin were undertaken in order to obtain morphological information on the mechanism of hormone action at the cellular level. Fed and fasted animals from each of the above groups were studied. Hepatocytes from fed rats of the three groups showed similar characteristics: periportal cells contained large dense masses of glycogen throughout the cytosome with relatively little smooth endoplasmic reticulum; mid-lobular cells displayed small dense masses of glycogen with few associated elements of smooth endoplasmic reticulum; centrilobular hepatocytes showed dispersed glycogen and abundant smooth endoplasmic reticulum. Hepatocytes from hypophysectomized rats fasted fifteen hours showed significant alterations in structure when compared with liver cells from sham-operated animals. Differences noted were: decrease in mid-lobular cell size and amount of smooth endoplasmic reticulum; decrease in glycogen, number of ribosomes and polysomes per hepatocyte; disorganization of the rough endoplasmic reticulum; and swelling of mitochondria and increase in number per cytoplsmic volume. Periportal hepatocytes from fasted hypophysectomized rats treated with somatotropin for ten days contain numerous small masses of glycogen with elements of smooth endoplasmic reticulum at the periphery of the glycogen masses. Mid-lobular and centrilobular hepatocytes contain masses of dispersed glycogen with an abundance of smooth endoplasmic reticulum associated with the glycogen particles.     

Ultrastructural changes in the liver in heatstroke.

The ultrastructural changes in the human liver 24 to 96 hours after an attack of heatstroke are described. The alterations are most obvious along the vascular pole of the hepatocytes. These consist of degenerative changes or desquamation of sinusoidal lining cells, ballooning or flattening of microvilli, breaks in hepatocyte outer membranes, and electron-lucent vacuoles along the sinusoidal border. Also noteworthy is the appearance, in a number of cases, of basement membranes or ill-defined electron-dense material which may be of basement membrane character. Sinusoidal elements, such as erythrocytes, are found in hepatocytes, and hepatocellular debris appears in sinusoids. The membranes of hepatocytes and sinusoidal lining cells thus seem to be the prime targets of the hepatic injury in heatstroke. Other changes in the hepatocytes include vesiculation of endoplasmic reticulum, detachment of ribosomes, and alterations of mitochondria. Morphologic evidence of intravascular coagulation of intravascular hemolysis is often encountered. A comparison between the findings described here and those in experimental hyperthermia suggests that many of the hepatic changes seen in heatstroke are due to an excessively high tissue temperature per se but that some of the alterations are probably a consequence of complicating factors such as hypoxia, intravascular hemolysis, or disseminated intravascular coagulation.     

Histopathology of the liver and kidney during malaria: relation to malaria-induced dyslipoproteinemia

A kinetic study concerning histologic and cytologic alterations during Plasmodium chabaudi infection of Swiss mice has been carried out. In liver, a reversible focal and non ischemic necrosis and a vascular congestion were observed together with an accumulation of malarial pigment. The endoplasmic reticulum cisternae and Golgi saccules of hepatocytes were highly distended. Hepatocyte microvilli in biliary canaliculi and in Disse' spaces were markedly less developed and less numerous than in normal liver. Intracytoplasmic lipid globules were found in large amount in hepatocytes before the peak of parasitaemia. Their number and size gradually diminished thereafter. Hepatocytic mitochondria showed important unspecific modifications probably in relation, at last partly, to the tissue anoxia. Some hepatocytic changes (intracytoplasmic lipid globules, enlargement of endoplasmic reticulum cisternae and Golgi saccules) were consistent with an increased synthesis of lipoproteins (VLDL). The kidney showed only minor histological and ultrastructural changes. However haemosiderin was observed in proximal tubules and in their bordering cells. The deposit of immune complex reported previously do not appear associated with tissular or cellular important alterations.     

Ultrastructural studies of the hepatocytes after chronic exposure to low levels of halothane.

Adult rats were exposed to 10 ppm or 500 ppm halothane 8 hr/day and 5 days/wk for 8 wk or 4 wk, respectively. In the liver from animals which were exposed to 10 ppm of halothane, the rough endoplasmic reticulum in some hepatocytes accumulated a floccular, electron-dense material which gave the hepatocytes a dense and dark appearance. Increase in the matrical density and C-shaped transformation were observed in the mitochondria of some hepatocytes. In addition to these findings, areas of focal cytoplasmic degradation, dilatation of the bile canaliculi, peribiliary accumulation of lysosomes, and extensive dilatation of the smooth endoplasmic reticulum to form large cytoplasmic vacuoles were also observed in the hepatocytes of animals which had been exposed to 500 ppm halothane. Toxic potential of halothane upon chronic exposure is suggested.     

Ultrastructural alterations in livers with metastasis.

The electron microscopic examination of 13 biopsy specimens of livers that contained metastatic carcinoma revealed degenerative alterations of the mitochondria, cystic dilatation of the endoplasmic reticulum, increased amounts of osmiophilic material, some in various stages of autophagocytosis, and lipid vacuoles within the hepatocytes. In ten of 13 cases, the hepatocytes demonstrated mitochondrial paracrystalline inclusions. The observation of the latter structures in edematous hepatocytes containing phospholipid-rich osmiophilic deposits tends to confirm the experimental hypothesis that paracrystalline inclusions are caused by the precipitation of unmasked phospholipids. The spectrum of ultrastructural findings suggests hypoxia and impaired lipid metabolism of the hepatic tissue as a result of congestion and bile stasis caused by the tumor nodules.     

肝纤维化大鼠肝脏中内质网应激相关分子CHOP和TRB3的表达变化

 目的： 观察内质网应激相关分子CCAAT/增强子结合蛋白同源蛋白(CHOP）和Tribbles同源蛋白3（TRB3）在四氯化碳（CCl4）致大鼠肝纤维化过程中的表达变化,探讨其在肝纤维化过程中的可能作用。方法： 体重180～200　g的雄性Wistar大鼠随机分为正常4周组、正常8周组、肝纤维化4周组和肝纤维化8周组,肝纤维化组大鼠皮下注射40%CCl4制备肝纤维化模型,分别在4周和8周处死大鼠,观察肝组织病理改变,Western blotting检测肝脏活化转录因子6（ATF6）蛋白,免疫组化、Western blotting和real-time PCR分别检测肝脏CHOP和TRB3蛋白和mRNA表达变化,TUNEL法检测肝脏细胞凋亡。结果： 肝纤维化组大鼠肝脏可见假小叶形成,p90ATF6蛋白表达量较正常组明显减少（P<0.01）,p50ATF6蛋白表达量较正常组明显增加（P<0.01）,肝细胞胞浆CHOP和TRB3蛋白及mRNA表达量较正常组显著增加（P<0.01）,细胞凋亡率较正常组显著增加（P<0.01）。结论： 内质网应激相关分子CHOP和TRB3在CCl4致大鼠肝纤维化过程中蛋白及mRNA表达水平明显增加,其变化趋势与大鼠肝细胞凋亡率一致,提示内质网应激可能通过CHOP和TRB3促进肝细胞凋亡,参与肝纤维化发生发展。     

Ultrastructural changes of hepatocyte organelles induced by chemicals and their relation to fat accumulation in the liver

Fatty liver was induced in the rats shortly after administration of cycloheximide, ethionine, orotic acid, monensin or colchicine. It was strongly suggested that derangements in one or more of the hepatic lipoprotein metabolic steps, which occur at the levels of endoplasmic reticulum, Golgi apparatus and secretory vacuoles lead to an accumulation of triglyceride within hepatocytes.     

The effects of ethylene thiourea administration upon rat liver cells

The effect of ethylene thiourea (ETU) upon liver cells was evaluated in male Sprague-Dawley rats. ETU was administered ad libitum in drinking water at concentrations of 1, 5, 50, and 500 ppm for time intervals of 1, 2, and 5 days, 1 and 2 weeks, 1, 2, 4, and 8 months. Two additional groups of control animals received ETU-free drinking water or a diet supplemented with 0.06% 3-MeDAB. Electron microscopic evaluation of tissue samples could detect no changes in liver cell morphology of rats receiving 1, 5, or 50 ppm ETU for up to 8 months. By contrast, rats receiving 500 ppm ETU exhibited alterations in hepatic cell morphology after 4 months of exposure. These alterations included a dramatic increase in the amount of smooth endoplasmic reticulum (SER) with a concomitant reduction in rough endoplasmic reticulum (RER), and a relocation of microbodies and mitochondria to the periphery of the SER. No alterations were seen at the shorter time intervals. These changes probably represent a response to the sustained ingestion of high concentrations of highly toxic materials and most likely do not represent a specific response to ETU. No tumors were detected in any of the samples examined or in controls receiving ETU-free drinking water. Animals receiving 3-MeDAB in their diet all developed hepatic tumors within 4 months.     

ULTRASTRUCTURAL CHANGES OF HEPATOGYTE ORGANELLES INDUCED BY CHEMICALS AND THEIR RELATION TO FAT ACCUMULATION IN THE LIVER

Fatty liver was induced in the rats shortly after administration of cycloheximide, ethionine, orotic acid, monensin or colchicine. It was strongly suggested that derangements in one or more of the hepatic lipoprotein metabolic steps, which occur at the levels of endoplasmic reticulum, Golgi apparatus and secretory vacuoles lead to an accumulation of triglyceride within hepatocytes.     

A morphometric study of the effects of short-term starvation on rat hepatocytes

Short-term (24 h) starvation induced a significant decrease in the liver weight and in the average volume of hepatocytes, together with a notable decrease in the hepatic concentration of proteins, glycogen, cholesterol and triglycerides. Hepatocyte atrophy was due for about 95% to the decrease in the membrane space, in which glycogen and endoplasmic reticulum membranes are contained, and for about 5% to the depletion of lipid droplets, in which cholesterol and triglycerides are stored. Nuclei, mitochondria and rough endoplasmic reticulum did not display appreciable modifications. The smooth endoplasmic reticulum underwent a net decrease, comparable with the decrease in the liver protein content, and the volume of dense-body compartment was increased, mainly through the rise in the number of microautophagic vacuoles and secondary lysosomes. These last findings were interpreted as the morphological counterpart of the fasting-induced enhancement of protein degradation in rat liver.     

Ultrastructural changes in livers of tumour bearing rats.

An ultrastructural study of the livers of rats bearing transplanted mammary carcinomata from 4 to 12 weeks after transplantation revealed changes mainly in cytoplasmic structure of hepatocytes. The significant findings were pleomorphism of mitochondria, presence of large number of myelin figures, marked increase in microbodies, dilatation of rough endoplasmic reticulum, proliferation of smooth endoplasmic reticulum, intracytoplasmic cholesterol clefts and absence of increase in lysosomes. These alterations have been compared with that of others who have used different animal model systems to study the effect of tumour in livers of host. Centrioles in Küpffer cells are described for the first time in this study.     

Cadmium toxicity in the thyroid gland of pregnant rats

The toxic effects of cadmium on the thyroid gland of pregnant rats were studied with an electron microscope and an X-ray microanalyzer. Serum levels of thyroid hormones (T3 and T4) were also analyzed. Deterioration of the rough-surfaced endoplasmic reticulum occurred in the thyroid follicular epithelium on the fifth day of cadmium treatment. Large intracellular vacuoles, which arose from dilated cisternae of the rough-surfaced endoplasmic reticulum, were fused together, and marked swelling of the mitochondria was also noted. Thyroglobulin-secreting granules at the apical cytoplasm were decreased in number. By energy dispersive X-ray microanalysis, cadmium peaks were preferentially obtained from swollen mitochondria in the follicular epithelial cells. Serum levels of T3 and T4 were significantly decreased in cadmium-treated rats dams when compared to those of controls. In the present experiment, cycloheximide also caused degenerative changes in the rough-surfaced endoplasmic reticulum and the disappearance of thyroglobulin-secreting granules. Cycloheximide is a known inhibitor of protein synthesis on cytosolic ribosomes. These results indicated that accumulated cadmium in the mitochondria of thyroid follicular epithelial cells might disturb the oxidative phosphorylation of this organelle and the loss of energy supply possibly caused the inhibition of the synthesis and release of thyroid hormones.     

Hepatic morphologic and biochemical changes induced by subacute cocaine administration in mice.

The initial event and site of cocaine-induced hepatic injury have not been elucidated. In an attempt to identify the minimal effective dose and the site of injury, we have examined the livers of mice exposed to small daily doses of cocaine, using morphological and biochemical methods. All doses of cocaine greater than 5 mg/kg were able to cause significant elevation of serum glutamic pyruvic transaminase. Light microscopy revealed a progression of centrilobular necrosis as the dose increased from 10-30 mg/kg. The initial morphologic changes observed prior to necrosis included aggregation of intermediate filaments and dilation of rough endoplasmic reticulum with loss of ribosomes. Immunohistochemistry, using antibodies to cytokeratins, showed staining of individual hepatocytes in livers from cocaine-treated animals but not in controls. In contrast to earlier reports, we found little, if any, disruption of mitochondria. In vitro, the direct application of cocaine, norcocaine, and N-hydroxynorcocaine on isolated mitochondria had no effect on the ADP:O or respiratory control ratios, at concentrations up to 2.0 mM. Our studies demonstrate that any early cellular alterations in cocaine-induced hepatic injury are manifested in intermediate filaments and endoplasmic reticulum with no evidence of mitochondrial involvement.     

Chlordecone-induced potentiation of carbon tetrachloride hepatotoxicity: a light and electron microscopic study

Previous studies have shown that a chlorinated pesticide, chlordecone (Kepone), greatly potentiates carbon tetrachloride (CCl4) hepatotoxicity and lethality (Curtis, L.R., Williams, W.L., and Mehendale, H.M. (1979). Toxicol. Appl. Pharmacol. 51, 283-293; Curtis, L.R., and Mehendale, H.M. (1980). Drug Metab. Dispos. 8, 23-27). The present study describes sequential morphologic changes which occurred in livers of rats given a "nontoxic" level of chlordecone (10 ppm for 15 days) followed by a single injection of CCl4 (0.1 ml/kg). The hepatic alterations were examined 1 to 36 hr after exposure of the rats to CCl4. Those changes were compared to hepatic alterations which occurred in rats that received the same dose of chlordecone (10 ppm for 15 days) or a single injection of CClr (0.1 ml/kg) alone. The only change noted in livers from rats that received chlordecone alone was focal increase in smooth endoplasmic reticulum (SER) of hepatocytes at 24 hr and continuing throughout the time course of the experiment. Livers from animals that received CCl4 alone showed morphologic changes at 6 hr consisting of glycogen loss, increase in SER, and dilatation of rough endoplasmic reticulum (RER) in pericentral hepatocytes. Accumulation of small lipid droplets was also noted in midzonal hepatocytes. After 6 hr, there was no further increase in severity of injury. At 12 hr recovery was noticeable and, by 36 hr, livers from the CCl4 group appeared normal. Prior administration of chlordecone greatly potentiated pathologic changes in livers of animals that received CCl4. By 4 hr, there was total loss of glycogen in hepatocytes throughout the entire lobule. Small lipid droplets were present in pericentral, midzonal and periportal hepatocytes. Hepatocytes with extremely dilated RER were randomly scattered throughout the entire lobule. At 6 hr, there was further accumulation of lipid in the form of large droplets in hepatocytes. Focal, necrotic cells surrounded by polymorphonuclear leukocytes were randomly distributed throughout the lobule. The number of necrotic foci had progressively increased at the 12- and 24-hr intervals. By 36 hr, confluent areas of necrosis in pericentral and midzonal areas were observed in livers of some animals. This study indicates that although the combination of chlordecone and CCl4 produces much greater hepatic injury resembling damage due to a massive dose of CCl4, histologically, some differences in the progression and distribution of hepatocellular damage within the lobular architecture of the liver are evident.     

Rapid alterations induced by insulin in hepatocyte ultrastructure and glycogen levels

The speed with which insulin alters hepatocyte ultrastructure and glycogen levels in insulin-deficient rats has been studied. Insulin deficiency was induced with alloxan, followed by insulin treatment with regular and NPH insulin. Rats were killed at various times after the insulin injection, blood samples were obtained, plasma glucose levels were determined, and liver samples were prepared for electron microscopy and glycogen determinations. Plasma glucose levels in insulin-deficient rats declined to normal values by 4 hours post insulin, returning to insulin-deficient levels by 8 hours post insulin. Hepatic glycogen was considerably reduced in the insulin-deficient rats. By 1 hour post insulin hepatic glycogen increased, reached maximal levels by 8 hours, then declined to insulin-deficient levels by 36 hours. The ultrastructural appearance of both centrilobular and periportal hepatocytes from insulin-deficient rats showed abundant vesicular smooth endoplasmic reticulum (SER), decreased rough endoplasmic reticulum (RER), and enlarged RER intracisternal spaces. One-half hour post insulin, centrilobular hepatocytes were unchanged. In periportal hepatocytes, however, vesicular SER was no longer visible, the RER intracisternal spaces appeared normal, and the amount of RER had increased. By 1 hour post insulin the centrilobular hepatocytes showed similar ultrastructural changes. These changes became more pronounced in the next few hours and remained through 24 hours. By 36 hours both centrilobular and periportal hepatocytes appeared similar to those in the insulin-deficient rat. These results demonstrate the rapid and lobular-specific effects insulin has on the hepatocyte.     

Electron microscopic study on the injurious effects of chlorpromazine on rat liver cells.

The authors examined the effect of chlorpromazine administration on rat liver cells. The early alterations were limited to the pericanalicular region, but the dilatation of bile canaliculi and the destruction of canalicular microvilli, both characteristic of rats with cholestasis were not observed. It is suggested that beside the Golgi apparatus, the smooth surfaced endoplasmic reticulum, the plasma membranes of liver cells also have an important role in the formation of vesicles and vacuoles in the pericanalicular region. The progressive proliferation of the smooth surfaced endoplasmic reticulum is thought to be related to an increased overburdening of the biotransformation system of liver cells, which is the result of chronic drug administration. In the last period of the experiment there was a decrease in the quantity of rough surfaced endoplasmic reticulum and increased fatty infiltration, mitochondrial alterations in some liver cells and simultaneously numerous regenerating liver cells were observed. All these alterations are attributed by the authors to the direct liver injuring effect of chlorpromazine.     

The liver hemopoietic environment: I. Developing hepatocytes and their role in fetal hemopoiesis

Mouse fetal liver was studied ultrastructurally to identify and characterize the developing hepatic parenchyma or prehepatocyte which may be responsible for producing the liver hemopoietic environment. It was observed that as the liver develops, there is close association of endodermal and mesenchymal cells in the region of the septum transversum. Numerous intercellular adhesions were observed between endodermal cells and mesenchymal cells. Twenty-four after endodermal and mesenchymal cells first intermingle, the liver extravascular space consisted of spherical hemopoietic cells dispersed among a heterogenous population of dark and light cells. The reticulum of prehepatocytes formed a three-dimensional cellular network which structurally supported the hemopoietic cells residing in the liver. By 12 days of gestation, prehepatocytes were a homogenous population of dark, stellate cells joined together by numerous intercellular adhesions. Broad areas of intercellular association were noted between processes and prehepatocytes and hemopoietic cells; however, no intercellular junctions between these two disparate cell populations were observed at this or any stage in development. Characteristics reflecting a cell population capable of synthesis and secretion of proteinaceous substances, namely, dilated Golgi apparati, increased numbers of polyribosomes and profiles of rough endoplasmic reticulum (RER), two types of vacuoles and/or vesicles, and intercellular microvillus-lined spaces, were observed in the prehepatocytes between 12 and 17 days gestation. By day 17 of gestation, glycogen accumulation, biliary channel development, appearance of a subendothelial microvillus surface, nuclear shape and chromatin pattern, and arrangement of cytoplasmic organelles reflected the maturation of prehepatocytes into hepatocytes, the adult liver parenchyma.     

Stereology of PCB 128-induced ultrastructural alterations in the rat liver

Hepatocyte cytoplasmic alterations were stereologically determined in male and female Sprague-Dawley rats fed PCB congener 128 (2,2',3,3',4,4'-hexachlorobiphenyl) in concentrations of 0.05, 0.5, 5, 50 ppm, or corn oil in diets daily for 13 weeks. A significant increase (p < 0.05) in the volume-fraction of smooth endoplasmic reticulum (SER) was measured in the female rats fed a diet containing 5 or 50 ppm of the congener and a significant increase was revealed in the male rats at doses of 0.5 and 50 ppm. Because drug metabolizing enzymes are bound to the SER, proliferated profiles may imply heightened enzyme activity necessary to metabolize the PCB. An elevation in volume-fraction of rough endoplasmic reticulum (RER) was measured in the hepatocytes of the male rats fed 5 ppm of the congener and none of the concentrations significantly enhanced the level of RER profiles in the females. The volume-fraction values of mitochondria, peroxisomes or lipid droplets of the hepatocytes in either the males or the females were not significantly different, as were the baseline volume-fraction of parameters studied between the male and the female rats. We determined for PCB 128, when administered in a diet to Sprague-Dawley rats, the no observable adverse effect level (NOAEL) is < 0.5 ppm.     

Ultrastructural changes in the parenchymal liver cells of rats treated with high doses of rifampicin

Ultrastructural study of hepatic parenchyma was carried out in female Wistar rats after they had received high doses (400 mg X kg-1) of rifampicin for 1, 2, 4, 6 and 8 days. Morphological changes in the endoplasmic reticulum, Golgi apparatus and mitochondria were observed as early as day 1 of intoxication. These changes corroborate the biochemical data available regarding RFP-induced fatty liver.