Altered liver acini induced in diabetic rats by portal vein islet isografts resemble preneoplastic hepatic foci in their enzymic pattern.

As demonstrated previously, liver acini draining the blood from intraportally transplanted pancreatic islets in streptozotocin-diabetic rats are altered in various respects. The hepatocytes in these acini store glycogen and/or fat, and they show an increase in proliferation as well as in apoptotic activity. Thus, they are phenotypically similar to carcinogen-induced preneoplastic liver foci (glycogen-storing foci and sometimes also mixed cell foci). By means of catalytic enzyme histochemistry or immunohistochemistry, we investigated the activity of key enzymes of alternative pathways of carbohydrate metabolism and some additional marker enzymes (well known from studies on preneoplastic hepatic foci) in the altered liver acini surrounding the islet isografts. In addition, the expression of glucose transporter proteins 1 and 2 (GLUT-1 and GLUT-2) were investigated immunohistochemically. The activities of hexokinase, pyruvate kinase, glyceraldehyde-3-phosphate dehydrogenase, and glucose-6-phosphate dehydrogenase were increased, whereas the activities of glycogen phosphorylase, adenylate cyclase, glucose-6-phosphatase, and membrane-bound adenosine triphosphatase were decreased in the altered liver acini. The expression of GLUT-2 was also decreased. GLUT-1 and glutathione S-transferase placental form were not expressed, and the activities of glycogen synthase and gamma-glutamyl-transferase remained unchanged. All changes of the enzyme activities were in line with the well known effects of insulin and resembled alterations characteristic of preneoplastic liver foci observed in different models of hepatocarcinogenesis. It remains to be clarified in long-term experiments whether or not these foci represent preneoplastic lesions and may proceed to neoplasia.     

Hepatocellular alterations after intraportal transplantation of ovarian tissue in ovariectomized rats

The mechanisms of hepatocarcinogenesis by certain synthetic estrogens seem to involve both nongenotoxic and indirect genotoxic effects. However, the natural estrogen estradiol did not exert any carcinogenic effects in established experimental protocols. To elucidate specific long-term effects of natural estrogens on hepatocytes, small pieces of ovarian tissue were transplanted via the portal vein into the livers of ovariectomized female rats. One week, 3 weeks, and 3 months after transplantation the transplants were found to proliferate and to secrete estradiol. Three weeks after transplantation the hepatocytes of the liver acini downstream of the stimulated transplants already showed a remarkable loss of glycogen, distinct cytoplasmic amphophilia, enlargement of their nuclei, a strong increase in the number and size of peroxisomes, an increase in proliferative activity and apoptotic elimination, and changes in the activity of certain key enzymes of energy metabolism. All hepatocellular alterations could be inhibited by the estrogen receptor antagonist toremifene and are, therefore, attributed to specific effects of estradiol produced by the transplants. The observed alterations resemble in some respects amphophilic preneoplastic liver foci, which particularly occur after long-term administration of nongenotoxic hepatocarcinogens, including the adrenal steroid hormone dehydroepiandrosterone. In a preliminary experiment three of six animals exhibited a hepatocellular carcinoma, and another animal developed a hepatocellular adenoma 18 months after intrahepatic ovarian tissue transplantation.     

Transplanted hepatocytes engraft, survive, and proliferate in the liver of rats with carbon tetrachloride-induced cirrhosis

Repopulation of the cirrhotic liver with disease-resistant hepatocytes could offer novel therapies, as well as systems for biological studies. Establishing whether transplanted hepatocytes can engraft, survive, and proliferate in the cirrhotic liver is a critical demonstration. Dipeptidyl peptidase IV-deficient F344 rats were used to localize transplanted hepatocytes isolated from the liver of syngeneic normal F344 rats. Cirrhosis was induced by administration of carbon tetrachloride with phenobarbitone and these drugs were withdrawn prior to cell transplantation. Cirrhotic rats showed characteristic hepatic histology, as well as significant portosystemic shunting. When hepatocytes were transplanted via the spleen, cells were distributed immediately in periportal areas, fibrous septa, and regenerative nodules of the cirrhotic liver. Although some transplanted cells translocated into pulmonary capillaries, this was not deleterious. At 1 week, transplanted cells were fully integrated in the liver parenchyma, along with expression of glucose-6-phosphatase and glycogen as reporters of hepatic function. Transplanted cells proliferated in the liver of cirrhotic animals and survived indefinitely. At 1 year, transplanted hepatocytes formed large clusters containing several-fold more cells than normal control animals, which was in agreement with increased cell turnover in the cirrhotic rat liver. The findings indicate that the cirrhotic liver can be repopulated with functionally intact hepatocytes that are capable of proliferating. Liver repopulation using disease-resistant hepatocytes will be applicable in chronic conditions, such as viral hepatitis or Wilson's disease.     

Hepatocellular neoplasms induced by low-number pancreatic islet transplants in streptozotocin diabetic rats.

We have previously demonstrated in short-term experiments that altered hepatocytes in liver acini draining the blood from intraportally transplanted pancreatic islets in streptozotocin-induced diabetic rats with mild persisting diabetes resemble those in preneoplastic foci of altered hepatocytes. We now present the results of long-term studies (up to 22 months) in this animal model. Glycogen-storing foci (which were the first parenchymal alteration observed some days after transplantation) persisted at least for 6 months, when the first mixed-cell foci and the first hepatocellular adenoma emerged. After 15 to 22 months, 86% of the animals exhibited at least one hepatocellular adenoma and four animals (19%) showed a hepatocellular carcinoma. The transplants were found in a close spatial relationship with the preneoplastic foci and the hepatocellular neoplasms. The mitotic indices, the 5-bromo-2'-desoxyuridine labeling indices and the apoptotic indices showed significant differences between the unaltered liver parenchyma, different types of preneoplastic foci, and hepatocellular neoplasms. The immunohistochemical expression of transforming growth factor-alpha increased during the stepwise development from glycogen-storing liver acini to hepatocellular carcinomas. Hepatocarcinogenesis in this new animal model is probably due to the hormonal and growth-stimulating effects of insulin secreted by the intraportally transplanted islets of Langerhans in diabetic rats.     

Activation of glycolysis and apoptosis in glycogen storage disease type Ia

The deficiency of glucose-6-phosphatase (G6Pase) underlies glycogen storage disease type Ia (GSD-Ia, von Gierke disease; MIM 232200), an autosomal recessive disorder of metabolism associated with life-threatening hypoglycemia, growth retardation, renal failure, hepatic adenomas, and hepatocellular carcinoma. Liver involvement includes the massive accumulation of glycogen and lipids due to accumulated glucose-6-phosphate and glycolytic intermediates. Proteomic analysis revealed elevations in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and other enzymes involved in glycolysis. GAPDH was markedly increased in murine G6Pase-deficient hepatocytes. The moonlighting role of GAPDH includes increasing apoptosis, which was demonstrated by increased TUNEL assay positivity and caspase 3 activation in the murine GSD-Ia liver. These analyses of hepatic involvement in GSD-Ia mice have implicated the induction of apoptosis in the pathobiology of GSD-Ia.     

Islet graft-induced changes of beta-hydroxybutyrate dehydrogenase and glucose-6-phosphatase activity in liver cells of diabetic recipient rats.

It is known that the liver is a favourable site for implantation of pancreatic islets since the grafted islets remain metabolically intact and provide long-term normoglycemia in diabetic animals. However, the long-term effects exerted by the grafted tissue on the host organ are not well defined. We therefore investigated by light and electron microscopy the effects of syngeneic islets on the host organ after intraportal transplantation into the liver of streptozotocin (STZ)-induced diabetic LEW.1W rats. In addition, tissue sections of graft-bearing liver were stained by enzyme histochemical methods for beta-hydroxybutyrate dehydrogenase (HBDH) and glucose-6-phosphatase (G6Pase). At 12 weeks after transplantation, the changes seen in the hepatocytes surrounding the grafted islets were hyperproliferation and accumulation of glycogen. Hepatocytes adjacent to the implanted islets displayed increased HBDH activity, whereas G6Pase activity was variable, either decreased or increased. Increased HBDH activity was also observed in the periportal region and in liver cells extending to the central veins. The results demonstrate that intraportal islet grafts, in addition to normalizing glucose homeostasis, exert remarkable effects on the liver parenchyma of experimentally diabetic recipient rats.     

Hepatic dysfunction caused by dietary products of lipid peroxidation

Dietary products of lipid peroxidation cause hepatic dysfunctions such as reductions in activities of aldehyde dehydrogenase (mitochondrial NAD-dependent), succinate dehydrogenase, phosphoglucomutase, glucokinase, and glucose-6-phosphate dehydrogenase, and a depletion of coenzyme A. Toxic products in the peroxidation are considered to be the aldehydes among the decomposed products from hydroperoxides, because the decomposed products were incorporated into the liver but the other products were not when they were administered orally to rats. There are three current ideas on the causes of the dysfunctions: (a) direct attack of the incorporated aldehydes on the enzymes, (b) injury of the bio-membranes by the aldehydes, and (c) disturbance of the synthetic system for enzymes. In this study, to examine these ideas, a reasonable concentration of the peroxidation products to use in vitro was estimated from the amounts present in the liver after an oral dose of lipid peroxidation products. With respect to idea (a), when the peroxidation products were added to subcellular fractions of hepatocytes, the decomposed products specifically inactivated aldehyde dehydrogenase and glucose-6-phosphate dehydrogenase, and destroyed coenzyme A. For ideas (b) and (c), in which the parenchymal hepatocytes isolated from rat were used, the decomposed products did not seem to injure the bio-membrane, but they inhibited induction of glucokinase by hormones in the hepatocytes. It was concluded that in the hepatic dysfunction caused by the dietary products of lipid peroxidation the incorporated decomposed products in the liver directly inactivated the mitochondrial NAD-dependent aldehyde dehydrogenase and glucose-6-phosphate dehydrogenase, destroyed coenzyme A, and disturbed the synthetic system of glucokinase.     

Alterations in the fine structure of hepatocytes in hyperthyroid rats

Ultrastructural investigation of liver from ten radiothyridectomized adult male albino rats, made hyperthyroid by administration of desiccated thyroid for eight to ten weeks, revealed changes in hepatic organelles, but no differences between centrilobular, midzonal and periportal hepatocytes of a single lobule. The mitochondria were enlarged with an increase in matrix density, but no increase in number of mitochondria or alterations in membranes or criste was observed. The smooth endoplasmic reticulum appeared slightly increased and dilated in treated rats, while stacked cisternae of the rough endoplasmic reticulum were seldom seen. Large vacuoles, which often contained follicular material and frequently opened into the spaces of Disse, were observed at the periphery of hepatocytes. The vacuoles may arise from invaginations of the cell membrane along these spaces to increase the surface area and to act as channels for liver metabolites. Moreover, in hyperthyroid rats hepatic glycogen was uniformly depleted. Whether these changes were a primary effect of thyroid hormone or secondary to metabolic alterations is unclear.     

Morphologic and histochemical analysis of hepatocytes transplanted into syngeneic hosts.

Suspensions of freshly isolated hepatocytes were prepared by collagenase perfusion of livers of adult Fischer 344 female rats. The cells were injected into the dorsal fascia of 2/3 partially hepatectomized syngeneic hosts (10(6) cells per injection site) and were monitored from 3 days to 3 months after injection. Brown nodules developed at the transplantation site. Histologic examination of the nodules revealed that the hepatocytes were arranged in cords and clusters surrounded by fibrovascular connective tissue. Bile ductules were also seen. Hepatocytes were positive for glucose-6-phosphatase. Staining for gamma-glutamyltranspeptidase showed that the parenchymal hepatocytes were mostly (approximately 95%) negative, whereas bile ductules were positive. These histochemical findings were seen in hepatocytes up to 3 months after transplantation and did not vary with the age of the transplants. Electron-microscopic examination of the transplanted nodules demonstrated that the cells maintained the characteristics of hepatocellular cytoplasmic structure. The relationship between the bile canaliculi and the stromal vessels was found to be similar to the bile canaliculi and hepatic sinusoid polarity seen in the normal liver. Autoradiographic analysis showed that a fraction of the transplanted cells was active in DNA synthesis. This system may become a tool in the study of survival and neoplastic transformation of hepatocytes as a result of exposure to X-irradiation and chemical carcinogens.     

Carbohydrate metabolism in human renal clear cell carcinomas.

BACKGROUND: Renal cell carcinomas can be subclassified into clear cell carcinomas, chromophobe cell carcinomas, chromophilic cell carcinomas, and oncocytomas. Previous studies, in which no distinction among the different types of renal cell tumors and their grades of malignancy was performed, showed that these tumors had high glycolytic rates. EXPERIMENTAL DESIGN: The carbohydrate metabolism of control human kidney samples and renal clear cell carcinomas with different degrees of cytologic malignancy (G I, G II, and G III) was studied by determining the glycogen and glucose-6-phosphate levels and the activities of key enzymes involved in glycolysis (hexokinase, glucokinase, pyruvate kinase), gluconeogenesis (glucose-6-phosphatase, fructose-1,6-diphosphatase), and the pentose phosphate pathway (glucose-6-phosphate dehydrogenase) in these tissues and compared with those of a limited number of chromophilic cell carcinomas, chromophobe cell carcinomas, and oncocytomas. RESULTS: The glycogen and glucose-6-phosphate levels were significantly higher in G I, G II, and G III clear cut carcinomas than in control kidneys; glucokinase, hexokinase, and glucose-6-phosphate dehydrogenase activities remained unchanged, pyruvate kinase activity was enhanced, and glucose-6-phosphatase as well as fructose-1,6-diphosphatase activities were strongly reduced when compared with control kidney values. In chromophilic cell carcinomas glycogen content, glucose-6-phosphate dehydrogenase, and pyruvate kinase activities were elevated, while fructose-1,6-diphosphatase activity was reduced. In chromophobe cell carcinomas glycogen content was elevated and gluconeogenesis was reduced, whereas glycolysis was not activated. In oncocytomas glycogen was not detected and glucose-6-phosphate dehydrogenase, pyruvate kinase, and fructose-1,6-diphosphatase activities remained unchanged. CONCLUSIONS: It has been demonstrated that a series of characteristic changes occur in the carbohydrate metabolism of renal clear cell carcinomas: glycogen and glucose-6-phosphate levels increase, glycolysis is activated, and gluconeogenesis is reduced. Furthermore, the alterations of the carbohydrate metabolism within clear cell carcinomas are clearly distinct from those observed in chromophilic cell carcinomas, chromophobe cell carcinomas, and oncocytomas.     

Stem cell properties and repopulation of the rat liver by fetal liver epithelial progenitor cells

The potential of embryonal day (ED) 14 fetal liver epithelial progenitor (FLEP) cells from Fischer (F)344 rats to repopulate the normal and retrorsine-treated liver was studied throughout a 6-month period in syngeneic dipeptidyl peptidase IV (DPPIV-) mutant F344 rats. In normal liver, FLEP cells formed: 1) hepatocytic clusters ranging in size up to approximately 800 to 1000 cells; 2) bile duct structures connected to pre-existing host bile ducts; and 3) mixed clusters containing both hepatocytes and bile duct epithelial cells. Liver repopulation after 6 months was moderate (5 to 10%). In retrorsine-treated liver, transplanted cells formed large multilobular structures containing both parenchymal and bile duct cells and liver repopulation was extensive (60 to 80%). When the repopulating capacity of ED 14 FLEP cells transplanted into normal liver was compared to adult hepatocytes, three important differences were noted: 1) FLEP cells continued to proliferate at 6 months after transplantation, whereas adult hepatocytes ceased proliferation within the first month; 2) both the number and size of clusters derived from FLEP cells gradually increased throughout time but decreased throughout time with transplanted mature hepatocytes; and 3) FLEP cells differentiated into hepatocytes when engrafted into the liver parenchyma and into bile epithelial cells when engrafted in the vicinity of the host bile ducts, whereas adult hepatocytes did not form bile duct structures. Finally, after transplantation of ED 14 FLEP cells, new clusters of DPPIV+ cells appeared after 4 to 6 months, suggesting reseeding of the liver by transplanted cells. This study represents the first report with an isolated fetal liver epithelial cell fraction in which the cells exhibit properties of tissue-determined stem cells after their transplantation into normal adult liver; namely, bipotency and continued proliferation long after their transplantation.     

Control of glycogen metabolism in the developing turkey poult.

An experiment was conducted with young turkey poults to evaluate factors controlling glycogen metabolism in the period following hatching. Glucose and sucrose solutions were given along with a standard starter diet. Liver and carcass glycogen were measured on days 1, 4 and 6. Liver glycogen synthetase (EC 2.4.1.21) and phosphorylase (EC 2.4.1.1) were also assayed at these times. The characteristics of active and inactive glycogen synthetase at these times were determined and sensitivity of the active and inactive forms were related to physiological concentrations of glucose-6-phosphate. Supplemental glucose or sucrose increased carcass glycogen in comparison to controls; however, but sucrose was more effective than glucose in promoting liver glycogen synthesis in 4- and 6-day-old poults. There was an age dependent increase in carcass glycogen between days 1 and 6, but a decrease in liver glycogen between days 4 and 6. The activation of liver glycogen synthetase is incomplete in 1 day old poults but activity increases during the 1st week of life. Activation of glycogen synthetase decreased the apparent Ka for glucose-6-phosphate. Phosphorylase inactivation in vitro was not affected by age. Liver glucose-6-phosphate increases rapidly after hatching and the concentration is related to the in vitro Ka derived for both active and inactive synthetases. Both glucose and sucrose increased liver glucose-6-phosphate at days 4 and 6 as well as glycogen synthetase activity. The increase in enzyme activity may be caused indirectly by an allosteric effect of glucose-6-phosphate. Phosphorylase, while not affected by supplemental carbohydrates, did decrease in activity between days 4 and 6. The decrease in activity could affect the phosphorylase a/ synthetase a ratio and change glycogen metabolism.     

Effect of thyroid hormone on activity of enzymes of carbohydrate metabolism during tumor growth

Activity of hexokinase (HK) and its isozymes, glucose-6-phosphatase, and glucose-6-phosphate dehydrogenase and the effect of tri-iodothyronine (T₃) on this activity were investigated in the liver tissue of mice with transplanted hepatoma 22a at different times of growth of the tumor. Changes in the activity of individual enzymes in the liver were observed even while the tumor was small. Persistent changes in the activity of all enzymes studied, and also in the HK isozyme spectrum were observed starting from the 21st day after transplantation of the tumor. In the initial stages of hepatoma development the activity of the various enzymes in the liver is regulated by thyroid hormone. The inducing action of T₃ is gradually lost as the tumor grows in size.Institute of Experimental and Clinical Medicine, Ministry of Health of the Estonian SSR, Tallin. (Presented by Academician of the Academy of Medical Sciences of the USSR L. M. Shabad.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 71–74, July, 1979.     

Mechanisms of Hyperglycemic Effect of Calcitonin

We studied the effect of calcitonin on blood glucose level, total calcium content, and the main stages of carbohydrate metabolism: absorption in the intestine, transport from the blood to tissues, tissue sensitivity to insulin in the whole organism, glycogen content, and activity of glucose-6-phosphate dehydrogenase and lactate dehydrogenase in the liver. A hyperglycemic effect of calcitonin was demonstrated, a close negative correlation was found between glucose level and total calcium content (r=-0.834, p<0.02). Calcitonin had no effect on glucose absorption in the small intestine and its transport from the blood to tissues (glucose consumption by peripheral tissues at the organism level), but reduced glycogen content in the liver and increased activities of glucose-6-phosphate dehydrogenase and lactate dehydrogenase.     

Auxiliary liver organ formation by implantation of spleen-encapsulated hepatocytes

Hepatocyte transplantation is an attractive alternative to orthotopic liver transplantation. However, its application has been limited because of its short-term success only. Here we report a new approach to hepatocyte transplantation resulting in the generation of an auxiliary liver in vivo. Isolated primary hepatocytes were encapsulated in isolated spleens and then transplanted by attaching the spleens to the livers of recipient animals (mice or rats) using biodegradable adhesive. A vascular network was rapidly established, and protein molecules circulated freely between the transplanted spleen and the liver, to which they adhered. In contrast, the spleen, which did not adhere to the liver or adhered elsewhere (adipose tissue or peritoneum), did not become vascularized but shrank and died. Encapsulation of hepatocytes in an isolated spleen enhanced their survival significantly, and co-encapsulation of Engelbreth- Holm-Swarm gel together with the hepatocytes further enhanced it. The encapsulated hepatocytes expressed liver-specific differentiation genes for more than 3 weeks. Plasma albumin concentrations in Nagase analbuminemic rats began to increase 3 days after transplantation. The transplanted hepatic cells migrated into the liver parenchyma, whereas the spleen was absorbed. Thus, we have developed a novel, simple approach for the rapid and efficient formation of functional auxiliary liver using a modified hepatocyte transplantation method.     

The age-related changes in lipogenic enzymes: the role of dietary factors and thyroid hormone responsiveness.

To determine whether resistance to insulin or to thyroid hormones rather than an inherent defect in enzyme activity expression account for the age-related changes in lipogenic enzymes, the activities of malic enzymes (ME), fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G-6PD) and 6-phosphogluconate dehydrogenase (6-PGD) were assayed in hepatic, retroperitoneal fat and epididymal fat cytosol of male Fischer 344 rats at 3.5, 12 and 25 months of age. The rats were maintained on either regular rat chow with 62% of calories as complex carbohydrates or were given either high glucose or fructose diet with 65.7% of calories provided by glucose or fructose respectively. Additional groups of young and aged rats were treated with L-triiodothyronine (T3) (15 microg/100 g body weight) for 10 days. Treatment with T3 resulted in higher levels of hepatic ME activity regardless of the diet consumed or the age of the rats. T3 had no consistent effect on FAS, G-6PD or 6-PGD activities. ME response to T3 in young rats was significantly greater than that found in aged rats regardless of diet. The age-related decrease in basal hepatic ME activity was not apparent in rats maintained on the high glucose or the high fructose diets, yet the T3 responsiveness of ME in rats maintained on these diets was not normalized. In adipose tissue, with the exception of the age-related changes in basal activity of the lipogenic enzymes, neither T3 nor the feeding of the test diets had any consistent effects. Since insulin resistance induced by high fructose feeding did not reduce hepatic lipogenic enzymes, it is unlikely that the age-related increase in insulin resistance explains the reduced lipogenic enzyme activity in aged rats. However, resistance to thyroid hormone action found in aged rats may partly account for the reduced hepatic lipogenic enzyme activity.     

Increased viability of transplanted hepatocytes when hepatocytes are co-encapsulated with bone marrow stem cells using a novel method

This study is to investigate the viability of hepatocytes when transplanted into Wistar rats using co-encapsulated hepatocytes and bone marrow stem cells. Hepatocytes and bone marrow stem cells, isolated from Wistar rats, are co-encapsulated using either the standard single-step method or a novel two-step cell encapsulation method (www.artcell.mcgill.ca). After intraperitoneal transplantation into Wistar rats, the histology, fate of recovered microcapsules and viability of encapsulated hepatocytes are studied. When prepared using the standard method, there is excellent viability but only for up to 3 weeks. After this, there is extensive fibrous coating and severe fibrous adhesion and no microcapsules can be recovered. On the other hand, using the new two-step encapsulation method, the viability of the encapsulated hepatocytes can be followed for more than 4 months after transplantation. Even up to 4 months, there is significantly less host reaction when using the two-step encapsulation method and 50% of the microcapsules can be recovered. Co-encapsulated with bone marrow stem cells resulted in further increase in viability of the hepatocytes when followed up to 4 months after transplantation. This new approach may improve the potential feasibility of using co-encapsulation of hepatocytes and bone marrow stem cells in bio-artificial liver support for the treatment of liver failure, especially for acute liver failure.     

Histochemical studies on the early proliferative lesion induced in the rat liver by aflatoxin

Male inbred Fischer rats were fed a diet containing 5 p.p.m. aflatoxin for 1, 3, 4½ and 6 weeks at which times groups were killed for histological and histochemical study. Aflatoxin produced a scattered individual cell necrosis of parenchymal cells by 1 week. At 3 weeks small basophilic proliferative foci were seen which increased in size and abundance to 6 weeks. These foci showed starvation-resistant glycogen, variable depletion of glucose-6-phosphatase, succinic dehydrogenase, aniline hydrogenase, membrane ATPase and acid phosphatase. At 6 weeks the foci showed the presence of gamma glutamyl transpeptidase and glucose-6-phosphate dehydrogenase. The basophilic foci were not preceded by other focal histological and histochemical change. The basophilic proliferative lesions are observed when an irreversible change has been induced in the liver. The role of such lesions in the histogenesis of hepatocellular carcinoma is discussed.     

Glycogen-forming function of hepatocytes in cirrhotically altered rat liver after treatment with chorionic gonadotropin

Using cytofluorimetric and biochemical studies on serial supravital liver punctate biopsies, effects of chorionic gonadotropin (CG) on recovery of hepatocyte glycogen-forming function in the cirrhotically altered rat liver were analyzed. The biopsies were taken first from rats with experimental cirrhosis produced by their 6-month-long poisoning with the hepatotoxic poison CCl4, then from the same animals in 1, 3, and 6 month after cessation of their poisoning, either on treatment with CG or with no treatment. In smears of isolated hepatocytes, the contents of the total glycogen (TG) and of its labile and stable fractions (LF and SF, respectively) were measured. In liver homogenates, activities of glucose-6-phosphatase (G6Pase), glycogen phosphorylase, and glycogen synthetase were determined. It was found that the threefold increased TG content in hepatocytes of cirrhotic liver returned to the normal level in 3 months without treatment, while as soon as in 1 month in the case of the treatment with CG. The CG treatment for 3 months resulted in normalization of the glycogen fraction composition that had been changed in cirrhotic liver, whereas without treatment, the glycogen LF/SF ratio remained changed even after 6 months after cessation of the poisoning with CCl4. Activity of G6Pase was fourfold reduced in cirrhosis; in 3 months after the end of poisoning, under effect of CG, the activity increased to the normal level, but somewhat decreased subsequently. In the animals that were not treated with CG, the decrease in the G6Pase activity after the cessation of the CCl4 poisoning was even more marked than in the CG-treated rats. Activities of two other enzymes of glycogen metabolism did not differ statistically significantly from the norm throughout the entire experiment. The data obtained indicate that the use of CG for rehabilitation of the glycogen-forming function of the cirrhotically altered liver is more efficient than other ways of treatment studied previously, such as partial hepatectomy or a high-carbohydrate diet.