Effect of cerium on the rat liver: an ultrastructural and biochemical study.

Beitr. Path. Bd. 157,23-44 (1976)

Institut de medecine et de chirurgie experimentales, Universite de Montreal, Quebec and Department of Pathology, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada

Effect of Cerium on the Rat Liver An Ultrastructural and Biochemical Study1) Die Cerium-Wirkung auf die Rattenleber Ultramikroskopische und biochemische Untersuchungen M. SALAS, B. TUCHWEBER, K. KOVACS, and B. D. GARG With 18 Figures and 3 Tables' Received April 24, 1975 . Accepted August 22, 1975

111

revised form

Key words: Cerium - Liver steatosis - Ultrastructure - ATP - Adenine

Summary In rats, liver steatosis and necrosis were induced by cerous chloride (CeCI3) and the evolution of these changes was examined. By electron microscopy, I7 hours after CeCb treatment, dilation, disorganization and degranulation of the rough endoplasmic reticulum (RER) were noted with an increase in the number and electron density of lysosome-like bodies. In addition, nuclear chromatin showed a marked focal electron density, and the nuclear membrane appeared to be interrupted. At 24 hours, the RER was markedly dilated and de granulated, with free ribosomes aggregated in the cytoplasm. The Golgi cisternae appeared to be empty. There was an increase in the number and size of lipid droplets, with depletion of glycogen. At 48 hours, a massive proliferation of smooth endoplasmic reticulum (SER) vesicles occurred. Large lipid droplets were scatetered throughout the cytoplasm, while the mitochondria displayed mild changes. By the 8th day, the number of lipid droplets returned to normal; no abnormalities were detected in the other cell organelles. Biochemically, the total hepatic ATP levels fell significantly by the 12th hour, dropping to a minimum by the 48th hour. The liver was gradually depleted of glycogen within the first 48 hours, while hepatic triglycerides increased rapidly, reaching a peak

1) Part of this work was presented at the 63rd annual meeting of the International Academy of Pathology, San Francisco, March 12-16, 1974.

24 . M. Salas, B. Tuchweber, K. Kovacs, and B. D. Garg at 96 hours. Exogenous administration of adenine, ATP (adenosine triphosphate), or tryptophan completely prevented CeCb-induced mortality; hepatic fat acwmulation and necrosis were markedly decreased. Glucose, dl-methionine, and choline had no protective effect. It appears that a defect in hepatocellular lipoprotein synthesis and/or release may be responsible for lipid accumulation.

The increased use of lanthanons, or rare earth metals, in modern industry has stimulated interest in their metabolism and toxicity (Magnusson, I 963; Haley, I 96 5). These metals posses a wide range of biologic properties. They exert marked anticoagulant effects (Vincke, I 960) and can induce thrombohemorrhagic lesion~ (Selye et al., I 96 5), hepatic steatosis (Snyder et al., I 960) as well a~ soft tissue calcification (Tuchweber and Savoie, 1968) in animals. The liver is the major deposition site for the lighter lanthanom, e.g. C~CI3, with the microsomal fraction showing the greatest uptake of the metal (Magnusson, I963; Haley, 1965). The CeCl3-induced biochemical changes preceding the liver steatosis and necrosis have attracted considerable attention (Snyder and Stephens, I96I; Magnusson, I963; Snyder and Kyker, I964), yet the mechanism of action is not clear. In this paper, we have followed the chronologie development of hepatic lesions caused by CeCl3 and attempted to correlate the ultrastructural and biochemical alterations. Since dl-methionine, choline, adenine, adenosine triphosphate (ATP), glucose, and tryptophan influence the steatogenic action of hepatotoxins, such as carbon tetrachloride, ethionine, and orotic acid (Gallagher, I960; Farber et al., I963; Farber and McConomy, I 966; Miyai et al., 1970), we tested the effects of these compounds on the lesions produced by CeCh.

Materials and Methods Animals and treatments

Female albino Sprague-Dawley rats (85-r05 gm), maintained ad libitum on Purina laboratory chow and tap water, were treated twice daily with 550 mg/kg of dl-methionine (N.B.C.) intraperitoneally, 125 mg/kg of choline (Eastman) intraperitoneally, )20 mg/ kg of adenine (Eastman) per as, 404 mg/kg of ATP (N.B.C.) subcutaneously, 5 g/kg of glucose (Merck Frosst) per as, or thrice daily with 600 mg/kg of tryptophan (Dow Chemicals) per as for 2 days prior to intravenous administration of ro mg/kg of CeCis (K. & K. Laboratories) in 0.5 ml distilled water (pH 4-5). The pretreatments were then continued to autopsy. The controls received 0.5 ml of distilled water (pH 4-5) intravenously, and all the animals were decapitated at the time intervals listed in the tables or their footnotes.

Cerium and Liver· 25 Histology

Fresh liver tissue from the left lateral lobe was fixed in alcohol-formol or neutral formalin, and embedded in paraffin. Sections (4-8 [tm thick) were cut and stained with hematoxylin-phloxine or by the Periodic Acid Schiff (PAS) technique, with or without diastase digestion. Frozen sections were stained with Oil red O. Necrosis and fat accumulation were evaluated in hematoxylin- and Oil red O-stained tissue samples respectively. Electron microscopy

Nine groups (each containing 6 rats) were treated with CeCI3. Their livers were removed, group by group, after I hour; 6, I2, I7, 24, 48, 96 hours; 8 and 10 days. Immediately after decapitation, a small portion of tissue was excised from the left lateral lobe of the liver and placed in Millonig's osmium fixative, where it was minced into tiny cubes and kept for one hour at 4 0 C. The specimens were dehydrated in graded ethanol and embedded in Epon resin. Sections (0.5 ~lm thick) were cut on a Porter-Blum MT-2 microtome, stained with toluidine blue, and examined with a light microscope. Ultrathin sections (approx. 50 nm) were cut from selected midzonal areas, stained with uranyl acetate and Reynolds' lead citrate, and examined with either a Carl Zeiss EM 9A or a Philips 300 electron microscope. Biochemical methods

Liver glycogen was determined according to the Montgomery method (Montgomery, I957). Triglycerides were measured according to the technique of Butler et a!. (I96I) and total serum bilirubin by a modification of Nosslin's method (Nosslin, I960) with an American Monitor Company kit. Serum glutamic pyruvic transaminase (SGPT) was determined according to the Reitman-Frankel (Reitman and Frankel, I957) method (Dade Kit®), and hepatic ATP by the modified technique of Adam (Adam, I 96 3) (Sigma Kit®).

Results Morphologic Studies Light Microscopy. No pathologic alterations were observed during the first 17 hours after CeCl;J treatment but, at 24 hours, there was mild vacuolization of the hepatocytic cytoplasm with evidence of lipid droplet accumulation, mainly in the centrilobular area. In some rats, glycogen granules were concentrated in the periportal regions, while in others this change was rare (Fig. 1). At 48 hours, the hepatocytic cytoplasm was greatly vacuolated and no glycogen was present. Massive lipid accumulation was observed throughout the liver lobules. No changes were apparent in the hepatic vasculature, but necrosis of individual cells was noted (Fig. 2). Round, homogeneous, PAS-positive globules of various sizes were seen in the cytoplasm of some cells. The hepatic structure was again normal by the 8th and loth days.

26 . M. Salas, B. Tuchweber, K. Kovacs, and B. D. Garg

Fig.

I

Cerium and Liver· 27

Fig.1. Liver sections stained according to the Periodic Acid Schiff (PAS) technique (X 390): A. Hepatic parenchymal cells of a centrilobular area in a control rat showing abundant glycogen granules; B. Note the PAS-positive granules (arrow) in the cytoplasm 24 hours after CeCl3 treatment; C. Also at 24 hours, glycogen depletion is limited to the centrilobular area.

Electron Microscopy Untreated Rats. Since the ultrastructural features of normal hepatocytes (Fig. 3) have been reported in great detail by several investigators, they are not described here. CeClrtreated Rats. The hepatocytes revealed a normal ultrastructure up to I2 hours after CeCl 3 administration. Rough endoplasmic reticulum (RER) often appeared as long parallel arrays, while the smooth endoplasmic reticulum (SER) formed short tubules in close proximity to each other. The Golgi apparatus showed several parallel saccules containing granules of moderate electron density. Mitochondria and other cytoplasmic components were abundant near the glycogen masses. There was a slight increase in the number of dense pericanalicular bodies. At I7 hours, the nuclei of most parenchymal cells exhibited distinct alterations in the form of electron-dense areas in the nucleolus and slight irregularities in the nuclear membranes. Glycogen masses were abundant. The RER showed some disorganization. Slightly dilated, rough-surfaced


Fig. 2 . Frozen liver stained with Oil red 0 ( X 390): A. Vacuolization of the hepatocytic cytoplasm, cell necrosis and acidophilic bodies can be seen in the liver 24 hours after CeCl3 administration; B. Hepatic fat accumulation in rat treated with CeCl3 and sacrificed 48 hours later.


Fig. 3. Portions of two hepatocytes of a control rat. Parallel stacks of RER, normal mitochondria (M), and abundant glycogen masses (GI) are evident, X I4,700.

Fig. 4. Hepatocytes of rat I7 hours after CeCb administration. RER appears slightly dilated. Mitochondria (M) are unaltered and glycogen (GI) masses are abundant. X 8,600.

30

.

M. Salas, B. Tuchweber, K. Kovacs, and B. D. Garg

Fig. 5. Hepatocyte of rat I7 hours after CeCb treatment. There is slight RER and SER dilation. The Golgi apparatus (G) and mitochondria are unaltered. A few glycogen rosettes (Gl) are interspersed among the cell organelles. X I4,700.

Fig. 6. Rat hepatocyte I7 hours after CeCb administration. Note the RER vesiculation and dilatation. Fewer ribosomes are attached to the membrane surfaces. The nucleolar material is markedly electron-dense (arrow). X 12,900.

Cerium and Liver . 3 I

cisternae revealed abnormally few attached ribosomes. Dense, osmiophilic bodies ("liposomes") were present in some of these RER cisternae. Lysosome-like structures appeared in significantly greater numbers, extending beyond the pericanalicular area (Figs. 3-6). In these early phases of CeCb treatment, the changes were prominent in centrilobular areas; later they also extended to the periphery of the lobule. The RER alterations were pronounced 24 hours after CeCl3 treatment. Ribosomes were not evident in the endoplasmic reticulum membranes but appeared to be free in the cytoplasm and dispersed individually. Concentric pairs of endoplasmic reticulum membranes encircled the mitochondria and lipid droplets, the latter being larger and more numerous than in the earlier time-periods. Some cells exhibited collapsed endoplasmic reticulum cisternae; their mebranes formed concentric lamellae and were ribosomefree (Figs. 7-ro). Glycogen appeared as isolated rosettes in some cells only. The Goigi saccules were enlarged and free of electron-dense particles (Fig. I I). The changes in the nucleus were similar to those observed at I7 hours. Focal interruptions of the nuclear membrane were noted with leakage of the nucleoplasm and conspicuously electron-dense chromatin (Fig. IO). The lesions, however, showed no further progression. The particulate and fibril-

Fig. 7. Liver of CeCla-treated rat killed after 24 hours. Concentric pairs of RER membranes enclose a mitochondrion (M). Highly electron-dense lysosome-like bodies and large lipid droplets (L) are abundant. X 19,430.


Fig. 8. At 24 hours after CeCl3 treatment, markedly electron-dense material can be seen in the nucleolus (arrow). The RER is dilated and many free ribosomes appear in the cytoplasm. An increase in the number and electron-density of lysosome-like bodies is apparent. X 24,200.

Fig. 9. Part of the cell from rat given CeC13 and killed 24 hours later, showing collapsed endoplasmic reticulum cisternae (RER) (forming concentric lamellae), and a loss of ribosomes. X I 1,500.


Fig. 10. Rat hepatocyte 24 hours after CeCb administration. A nuclear membrane shows focal disruption (arrows) and leakage of the nucleoplasm. There is moderate dilation of RER cisternae and a partial loss of ribosomes. Lipid (L) droplets of vanous sizes are visible in the cytoplasm. X 24,000.

Fig. I r. Portions of two hepatocytes of a rat 24 hours after CeClg treatment. The Golgi saccules (G) appear enlarged and free of electron-dense particles. Dilated RER and markedly electron-dense lysosome-like bodies are also noted. X 23,000. 3

Beitr. Path. Bd. 157


lar components of the nucleoli were intermingled. Neither fragmentation nor disorganization of the nucleolar components was observed at any time. In the hepatocytic cytoplasm, vacuoles of varying sizes were limited by a single membrane. They contained low-density homogeneous or dense amorphous material and/or organelles in various stages of degradation (Fig. 12). Swollen, pleomorphic mitochondria, lacking intramitochondrial granules, appeared only in the severely-damaged cells. These organelles were normal in all other aspects. The hepatocytes displayed numerous homogeneously-dense lipid droplets 48 hours after treatment. There was massive SER accumulation as well as SER membranous configurations which were continuous with RER membranes. The latter could also be considered to be neoformed endoplasmic reticulum (Figs. 13-16). The microvilli in the bile canaliculi seemed to be slightly hypertrophied. Hepatocellular inclusions in the form of spherical, electron-dense bodies (1-5 nm) were noted, and these corresponded to the PAS-positive granules observed by light microscopy (Fig. 15). Essentially similar changes were observed in the hepatocytes at 96 hours. The lesions produced in the cytoplasm by CeCl g regressed within

Fig. 12. Section of rat hepatocyte 24 hours after CeClg treatment. A large vacuole (V) containing both low-density, homogeneous and dense amorphous material is noted in the hepatocytic cytoplasm. X 22,900.

Cerium and Liver . 35

Fig. 13. Low-power micrograph of liver cells 48 hours after CeCl3 injection. SER and lipid droplet accumulation are noted. Membranous arrays surround nuclei. X 7,300.

Fig. 14. Rat liver 48 hours after CeCb administration, showing concentric membranous configuration of SER which surround cytoplasmic organelles 8.nd are continuous with RER membranes. Large lipid droplets (L) are also evident. X 19,070.


Fig. 15. Massive SER accumulation 48 hours after CeCl3 treatment. A dense body (DB) (probably corresponding to a PAS-positive globule seen by light microscopy) is surrounded by lysosome-like structures (arrow). The mitochondria (M) are remarkably unaltered. X 10,000.

Fig. 16. Rat liver 48 hours after injection of CeCb. Numerous membranous arrays devoid of particles, and SER in tubular form, occupy almost the entire hepatocytic cytoplasm. Dilated vesicles contain an electron-lucent material (lipids?). X 20,950.


5 to 8 days. The lipid droplets decreased in number by the 8th day. The RER cisternae were elongated and studded with ribosomes; occasionally, there was slight dilation of the rough membranes. Abundant glycogen rosettes were noted with a moderate increase of SER (Fig. 17). The mitochondria exhibited little change; some of them were pleomorphic and lacked intramitochondrial granules. The Golgi apparatus seemed to be normal and was filled with electron-dense particles. The nucleoli occasionally showed dense granular material, and singularly electron-dense, lysosomelike bodies were frequently observed. Hepatic Glycogen and Triglycerides. The liver glycogen values obtained at I, 3, and 6 hours did not differ from those of the controls; hence, they are not included in Fig. 18. Glycogen was significantly decreased at 24 hours, becoming virtually undetectable at 48 hours (0.47 ± 0.02 mg/g wet liver). The values remained low at 96 hours, yet they were still significantly higher than the 48 hour levels. Within the first 24 hours after CeC13, there was a slight increase of liver triglycerides. The levels were markedly elevated by 48 hours, and a further rise was evident by 96 hours. Liver glycogen and triglycerides returned to normal after 8 to 10 days. Hepatic ATP. Liver ATP concentrations decreased significantly at 12 hours, reaching a minimum by the 48th hour (Table I).

Fig. 17. Liver of rat given CeClg and sacrificed 8 days later. RER membranes studded with ribosomes form parallel arrays and coiled aggregates. Glycogen granules are interspersed among moderate amounts of SER. X 17,500.

38 . M. Salas, B. Tuchweber, K. Kovacs, and B. D. G ar g

Serum Bilirubin and SGPT. A slight rise in serum bilirubin was noted at 24 hours, followed by a striking increase at 48 hours. SGPT activity in plasma showed a significant elevation at 24 and 48 hours (Table 2).

o ~

70

Glycogen T(lglycendes

70

60

50

50

50

40

1.0

~ 30

30

:c

Ol

Cii

~ .,...

~ Q;

~

C\

E 20

20

10

10

0

96hr

Bdays

Ime af ter Ceel 3

Fig.

18.

Table Group

1.

0

10 days

Effect of CeCla on liver glycogen and triglyceride content.

Effect of CeCl3 on Hepatic ATP ATP ± S.E. ([tmoles/g wet liver)

Time after CeCb treatment (I mg, i.v.)

-- --

2.13

P values

±

0.19

(8) 6 hr.

2

2.60

±

0.35

NS

0.16

Cerium and Liver . 39 Table 2.

Effect of CeCl3 on Blood SGPT and Bilirubin

Group

Time after SGPT ± S.E. P values CeCl3 treatment (units/ml sen:m) (1 mg, i.v.) -

- _ .. _-

-

Bilirubin ± S.E. (mglroo ml serum) ---------

24 hr.

101 ±ILO (4)

3

48 hr.

10 5 ± 10·4 (3)

---------

--

--

--

..

-

0.8 ± 0.0 (6)

37·9 ± H (7) 2

P values

< 0.001

< 0.05

0.9 ± 0.0 (5 )

< 0.001

< 0.005

2·4 ± 0·4 (6) _

__ .. _ - - _ .. _ - - - - - - -

..

_-

----

Figures in parentheses indicate number of rats. The values of each group are compared with that of the controls (group I).

Table 3. Effect of Amino Acids, Adenine, ATP and Glecose on CeCb-Induced Hepatic Triglyceride Accumulation and Lethality P values

Lethality (death/total)

46.1 ± 6.2 (6)

NS

3/ 6

Choline

42.3 ± IL7 (5 )

NS

2/6

Tryptophan

IL2

< 0.001

0/6

< 0.001

0/6

< 0.001

0/6

NS

2/6

Treatment

Triglycerides ± S.E. (mg/g wet liver)

None

38. 8

2

Methionine

3 4

Group

± 5·7 (II)

± 3.1 (5 )

Adenine

8.1 ± LO (9)

6

ATP

10.3

± LO (I I)

7

Glucose

41.4

± 5·7 (6) -

-----

------ -

In addition, all animals received I mg of CeC13 i.v. on the 3rd day and were sacrificed 48 hours later. A triglyceride value of 4.10 ± 0.69 mg/g wet liver was obtained for the untreated controls. The number of samples per group is given in brackets. Mortality was recorded on the 8th day.


Effect of amino acids, adenine, ATP, and glucose on CeClr induced liver lesions Pretreatment with methionine, choline, or glucose did not alter the lethal effects of CeCla which, however, were totally abolished by adenine, ATP, or tryptophan (Table 3). Methionine, choline, or glucose did not influence the massive lipid accumulation and necrosis induced by CeCls whereas adenine, ATP, and tryptophan were very effective in this respect. Lipid accumulation was mild and restricted to the centrilobular area. Adenine, ATP, and tryptophan significantly lowered the elevated triglyceride levels in rats given CeCl 3 (Table 3).

Discussion The present results are consistent with the view that the hepatocytic endoplasmic reticulum is the primary target of CeClg (Magnusson, 1963). Electron microscopy revealed marked dilation and disorganization of the endoplasmic reticulum 17 hours after treatment. Small osmiophilic bodies first appeared within the dilated cisternae of the endoplasmic reticulum, and at later stages, large lipid bodies devoid of limiting membranes lay free in the cytoplasm. Such morphologic changes, as well as increased liver triglyceride levels, are characteristic responses to CeCl 3 and to many other hepatotoxins (e.g., ethionine, CCI 4, and orotic acid) against which A TP and adenine offer protection (Farber et al., 1964; Jatlow et al., 1965; Farber and McConomy, 1966). Although the exact mechanism may vary with the inducing agent, considerable evidence has been obtained to show that disorganization of the RER and concomitant inhibition of hepatic protein synthesis may be important factors in the pathogenesis of fatty liver (Smuckler and Arcasoy, 1969; Stenger, 1970). Impairment of protein synthesis in the liver after CeCl g is suggested by the ultrastructural abnormalities, i.e. fewer membrane-bound and more abundant free ribosomes were observed in the hepatocytic cytoplasm. Fat accumulation may result from a failure in the synthesis and/or secretion of lipoproteins into plasma (Lombardi, 1966; Stenger, 1970); the latter are formed in the endoplasmic reticulum and are the major carriers of triglycerides to extrahepatic tissue. If this process is impaired, triglycerides may accumulate in the cytoplasm, as is the case in CeCl3-intoxicated rats. When protein synthesis is suppressed, there is either adversely-affected conjugation of various lipoprotein components, or inhibition of their transport and release, or both. Golgi complexes also form carbohydrate moieties (e.g., glycolipoproteins), which are released


into the plasma (Neutra and Leblond, 1966). The altered carbohydrate metabolism-namely, the decreased blood glucose and hepatic glycogen (Magnusson, 1963; Holten et al., 1966; Oberdisse et al., 1973) observed after CeClg treatment-may decrease glycolipoprotein secretion. Electron microscopically, 24 hours after CeCl g, the Golgi complex showed dilatation with an absence of dense particles (either lipoproteins or their precursors) in the saccules. This change suggests suppression of the triglyceride secretory mechanism. The earliest biochemical change was seen at 12 hours in the form of a decrease of total hepatic ATP. A comparable fall in ATP levels had been noted after such hepatotoxins as CC1 4, azaserine, or orotic acid (Hyams et al., 1967), although the reduction was not as great as that following ethionine treatment (Farber et al., 1963; Farber et al., 1964). An increased ATP degradation, decreased ATP synthesis or formation of a complex by ATP and cerium may account for the lower levels in CeC13-treated rats (Neubert, 1963). In our studies, prior treatment with ATP or adenine, rather than their simultaneous administration with CeClg, virtually abolished triglyceride accumulation. Hence, formation of an adenine- or ATP-metal complex (Snyder and Stephens, 1961) can account only in part for their preventive action. Moreover, the ability of ATP and its precursor to curtail the hepatic influx of free fatty acids (Glaser and Mager, 1972a; Glaser and Mager, 1972b), may playa role in the protection against CeC13-induced fatty liver. The mitochondria were almost normal within 1 day of CeCl g administration, but exhibited ballooning and loss of cristae between 48 and 72 hours. This indicates that the damage is secondary to other lesions in the hepatocyte. Octanoate oxidation by mitochondria is also virtually inhibited by the 48th hour (Glenn et al., 1962). It is noteworthy that tryptophan, a precursor of pyridine nucleotides, prevented the mortality and fat accumulation caused by CeC13 • Nicotinic acid and tryptophan have been shown to reduce the mortality rate in CC1 4-treated rats, mainly because they counteract the loss of pyridine nucleotides from mitochondria (Gallagher, 1960). The failure of methionine and glucose to protect against CeC1 3 contrasts with the findings on the effects of ethionine (Farber et al., 1964; Miyai et al., 1970). Therefore, the mechanism of action of the metal may differ from that of ethionine; it is not solely due to ATP deficiency. Apart from lipid droplet accumulation, the other conspicuous change at 24 to 48 hours was an unusual augmentation of SER in paired rows or tubular aggregates. Although it is generally accepted that compounds, which elicit SER hypertrophy in the liver, also enhance drug-metabolizing

42 . M. Salas, B. Tuchweher, K. Kovacs, and B. D. Garg

activity, there are numerous exceptions, such as insecticides, CC1 4, etc., that induce hypertrophic yet hypoactive SER (Stenger, I970). Similarly, hepatic drug-metabolism is significantly decreased 24 hours after administration of CeC1 3 (Arvela and Kirki, I97I). The hepatic changes observed at 48 hours receded progressively between the 5th and 8th days after CeCl 3 treatment, despite the fact that the liver retained approximately 70 per cent of the dose of CeCl3 for up to r 2 days after its administration (Snyder et al., I960). Lanthanons usually localize in organs rich in reticuloendothelial cells and, hence, much of the cerium may have been taken up by the Kupffer cells of the liver. Electron microscopy revealed that these cells contained markedly electron-dense deposits, corresponding perhaps to cerium (Salas, I973).

Zusammenfassung Eine Leherverfettung und -nekrose wurden durch Ceriumchlorid (CeCb) in Ratten erzeugt. 17 Stunden nach CeCIs-Behandlung zeigt das rauhe endoplasmatische Retikulum eine Dilatation, Desorganization nehst Degranulation. Die Zahl und die Elektronendichte der Iysosomahnlichen Korperchen steigt an. Zusatzlich findet sich eine deutliche fokale Elektronendichte im Kernchromatin und die Kcrnmemhrane scheinen unterhrochen zu sein. Nach 24 Stunden ist das rauhe endoplasmatische Retiklllum hochgradig dilatiert und degranuliert. Die freien Rihosomen haufen sich im Zytoplasma. Die Golgi-Zisternen scheinen leer zu sein. Die Zahl und Gro6e der Fetttropfchen hat zugenommen, der Glykogengehalt ist vermindert. Nach 48 Stun den tritt eine massive Proliferation des glatten endoplasmatischen Retikulums ein. GroBe Fetttriipfmen sind im Zy£Oplasma ausgehreitet, wahrend die Mitochondrien nur leichte Veranderungen aufweisen. Normalwerte der Anzahl der Fetttriipfchen werden wieder am 8. Tage nach der Behandlung erreicht. Biomemische Untersuchungen zeigen, daB der £Otale ATP-Gehalt der Leher his wr 12. Stunde wesentlich abfallt und dann nach 48 Stunden auf ein Minimum absinkt. In den ersten 48 Stunden verliert die Leber sukzessive Glykogen, wahrend ihr Triglyzeridengehalt sehr schnell ansteigt und nach 96 Stunden einen Spitzenwert erreicht. Exogene Behandlung mit Adenin, ATP (Adenosintriphosphat) oder Tryptophan schutzt die Tiere vollstandig vor dem durch CeCl3 induzierten Mortalitatsanstieg und verringert die Leherverfettung und Nekrose. Glukose, dl-Methionin und Cholin uben keine Schutzwirkung aus. Es ist anzunehmen, daB fur die Pathogenese eine defekte Lipoproteid-Synthese und/oder Freisetzung fur die Verfettung vcrantwortlich ist. Acknowledgements This work was supported in part by the Ministere des Affaires Sociales, Quebec, the Medical Research Council of Canada (Block Term Grant MT-r829), Succession]. A. DeSeve, and the Cancer Research Society. M. Salas is a recipient of a studentship from the Quebec Medical Research Council.


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Cystic nephroma: an ultrastructural and biochemical study.

Effects of heat acclimation on the secretory products of the submaxillary gland of the rat. An ultrastructural and biochemical study.

Short- and long-term effects of vinblastine on the rat adrenal medulla. An ultrastructural and biochemical study.

An ultrastructural and biochemical study of hexachlorophane-induced fatty liver in sheep.

Effect of pentoxiphylline on the recovery of the preserved rat liver: 31P NMR and ultrastructural studies.

Ultrastructural and stereological study on the effect of vitamin E on liver mitochondrial membranes.

Effect of interferon on dimethyl sulfoxide-stimulated Friend erythroleukemic cells: ultrastructural and biochemical study.

Effect of albendazole on human hydatid cysts: an ultrastructural study.

An ultrastructural study of the red nucleus in the rat.

Histochemical, biochemical and ultrastructural studies on the liver of fasted rats.

Effect of fasting on the biochemical properties of perfused rat liver.

An ultrastructural study of ipsilateral corticospinal terminations in the rat.

Isolated pancreatic islets of the rat: an ultrastructural study.

Effect of polychlorinated biphenyl (PCB) on the thyroid gland of rats. Ultrastructural and biochemical investigations.

Effect of castration on the rat pineal gland: a fluorescence histochemical and biochemical study.

Ultrastructural and biochemical effects of prolonged oral arsenic exposure on liver mitochondria of rats.

Effect of an inhibiting factor isolated from rat liver on DNA polymerases in regenerating rat liver.

Interlaminer connections of rat visual cortex: an ultrastructural study.

The endoplasmic reticulum of the rat liver cell in experimental mechanical cholestasis. Correlated biochemical and ultrastructural-morphometric studies on structure and enzyme composition.

The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation.

Alleviative effect of quercetin on rat testis against arsenic: a histological and biochemical study.

The effect of phorbol myristate acetate on human lymphocytes. An ultrastructural study.

Functioning oxyphil adenoma of parathyroid gland. An ultrastructural and biochemical study.

An ultrastructural study of spontaneous and phenobarbitone-induced nodules in the mouse liver.