Effect of granulocyte colony-stimulating-factor administration on tissue regeneration due to thioacetamide-induced liver injury in rats

It has been shown recently that granulocyte colony-stimulating factor (G-CSF) accelerates and enhances the hepatocyte proliferative capacity of partially hepatectomized rats. In the present study, we investigated the effect of G-CSF administration in a rat model of liver injury and regeneration, induced by thioacetamide (TAA) injection. TAA (300 mg/kg body weight) was injected intraperitoneally in male Wistar rats, and this was followed by administration of either saline (group A) or G-CSF at a dose of 150 mu g/kg body weight (group B), 24 hr later. The animals were killed at different time points after TAA treatment and the rate of tritiated thymidine incorporation into hepatic DNA, the activity of the enzyme thymidine kinase (EC 2.7.1.21) in the liver, and the assessment of the mitotic index of hepatocytes, were employed to estimate liver regeneration. The administration of TAA caused severe hepatic injury, recognized histopathologically and by the raised activities of the serum hepatic enzymes aspartate and alanine aminotransferases. The hepatic injury, which peaked 36 hr after TAA injection, was followed by a regenerative process of hepatocytes presenting peaks at time points of 48 and 60 hr (group A). The administration of G-CSF 24 hr after the injection of TAA (group B) caused a statistically significantly increase in the hepatocyte proliferation indices examined (P < 0.001), compared to those found in groupA at the same time points. It was concluded that G-CSF administration enhanced the hepatocyte proliferative capacity in this model of liver injury induced by TAA administration

Metallothionein expression in human neoplasia

The metallothionein family is a class of low-molecular-weight, cysteine-rich proteins with high affinity for metal ions. Four major isoforms (metallothionein-1, -2, -3, and -4) have been identified in mammals, involved in many pathophysiological processes, including metal ion homeostasis and detoxification, protection against oxidative damage, cell proliferation and apoptosis, drug and radiotherapy resistance and several aspects of the carcinogenic process. In the present review we examine the expression of metallothionein in different human tumours and its correlation with histopathological variables, tumour cell proliferation or apoptosis, resistance to radiation or chemotherapy, patient survival and prognosis. A variable profile of metallothionein and its isoforms’ expression has been observed in different cancer types. Although metallothionein expression has been implicated in carcinogenic evolution, its use as a marker of tumour differentiation, cell proliferation and prognosis predictor remains unclear. Detailed studies focused on the expression of metallothionein isoforms and isotypes in different tumour types could elucidate the role of this group of proteins in the carcinogenic process, delineating its possible clinical significance for the management of patients

Hepatic stimulator substance administration affects cadmium-induced hepatotoxicity in the rat

The effect of hepatic stimulator substance (HSS) administration on cadmium (Cd) induced hepatotoxicity was studied in the rat. HSS was extracted from the liver of weanling rats (Hepatology 1985; 7: 100-106). Rats were injected with 2.5 mg CdCl2/kg body weight to induce acute liver injury, evaluated 24 h later. Serum enzyme activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and histological parameters were used for the estimation of Cd-induced hepatotoxicity. HSS, at doses of 10, 20 and 30 mg protein/kg body weight, injected 10 h after Cd administration, caused dose-dependent decrease of hepatic injury. HSS suppressed the elevation of AST and ALT induced by Cat in a dose-dependent manner. Liver histological changes indicated that HSS reduced the severity of hepatic lesion induced by Cd administration and reversed Cd-induced hepatotoxicity. In conclusion, our results suggest that HSS administration protects the liver against Cd-induced injury

Metallothionein and heat shock protein expression during acute liver injury and regeneration in rats

Metallothioneins (MT) are cytosolic proteins rich in cysteine which play a physiological role in metal ion homeostasis. Heat shock proteins (HSPs) are expressed in various organs in response to different stress stimuli. The purpose of the present study was to examine the intrahepatic distribution of MT and HSP-27, -70 and -90 in two different experimental models of acute liver injury and regeneration, induced by either thioacetamide, or carbon tetrachloride administration in male Wistar rats. Toxicological endpoints and markers of hepatocellular regeneration were assessed at various time points following toxin administration. The enzymatic activities of aspartate and alanine aminotransferases in serum, and histological findings in the liver were used to estimate toxin-induced injury. Tritiated thymidine incorporation into hepatic DNA, liver thymidine kinase activity and hepatocyte mitotic index were used to estimate liver regeneration. MT and HSPs were detected immunohistochemically. At the time of maximum liver injury, moderate MT and intense HSPs expression was prominent in hepatocytes in the vicinity of necrotic areas. At the time of maximum hepatocellular proliferation, intense MT and HSP-90 staining was evident in all hepatocytes, while at the same time, mild HSP-27 and HSP-70 immunoreactivity was noted. Our findings indicate that the differential distribution of MT and HSPs in the liver after toxin-induced injury, in common with the observed pattern of staining, reflect liver proliferating capacity

Hepatic stimulator substance activity in the liver of thioacetamide-intoxicated rats

Aims/Background. Hepatic stimulator substance (HSS) is a known hepatic growth factor which appears to be organ-specific but species non-specific. We have recently shown that the administration of ass enhanced hepatocyte proliferation occurring due to thioacetamide (TAA)-induced liver injury in rats (Theocharis SE, et al., Scand J Gastroenterol 1998; 33: 656-63). In the present study, we examined the activity of the endogenously produced ass in the liver of TAA administered rats during injury and regeneration. Methods. TAA at a dose of 300 mg/kg of body weight was injected intraperitoneally in male Wistar rats. The animals were sacrificed at 0, 12, 24, 36, 48, 60 and 72 h after TAA administration. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of liver thymidine kinase and the assessment of mitotic index in hepatocytes were used to estimate liver regeneration. ass extract was obtained from the livers of TAA-treated rats, sacrificed at the above mentioned time points. This HSS extract was injected in 34% partially hepatectomized rats, to assess its activity. The ability of the injected HSS extract to increase hepatocellular proliferation over that normally occurring 24 h following 34% partial hepatectomy was used to express the activity of HSS by determining the above mentioned indices of liver regeneration. Results: The administration of TAA caused severe hepatic injury recognized histopathologically as well as by the increased activities of serum hepatic enzymes aspartate and alanine aminotransferases. The hepatic injury, which peaked at 24 and 36 h post-TAA treatment (p<0.001), was followed by hepatocyte proliferation, presenting peaks at 48 and 60 h (p<0.001). The activity of the endogenously produced HSS from livers of TAA-treated rats increased at 36 h after TAA administration as well as being highly expressed at 48 and 60 h thus coinciding with the peak of hepatocyte proliferation. At other time points, HSS activity was decreased. Conclusions: The observed variations of HSS activity in rat liver suggest active participation of this growth factor in hepatocyte replication which follows toxin-induced liver injury as a repair mechanism process

Putrescine Administration reverses cadmium-associated inhibition of liver regeneration

The liver is of central importance in the metabolism of essential and toxic metals such as cadmium. Cadmium pretreatment suppressed the liver regenerative response to partial hepatectomy, due to the inhibition of the enzymatic activity of thymidine kinase. Exogenous putrescine administration has been reported to stimulate liver regeneration in animal models of acute liver failure. The purpose of this study was to document whether the administration of this polyamine enhances the impaired regenerative capacity of hepatocytes in cadmium pretreated partially hepatectomized rats. The intraperitoneal administration of putrescine (1 or 10 mg/kg body weight), at the time of surgery and at 4 and 8 hr postoperatively partly restored the suppressed hepatocyte deoxyribonucleic acid (DNA) biosynthesis and thymidine kinase activity in cadmium-pretreated partially hepatectomized rats. Mitotic activity and the percentage of hepatocytes positive for proliferating cell nuclear antigen nuclei were in accordance with the liver proliferative status. Our results showed that exogenous putrescine administration is able to improve diminished liver regeneration after partial hepatectomy in this animal model of acute hepatic injury

Hepatic stimulator substance activity in animal model of fulminant hepatic failure and encephalopathy

Hepatic stimulator substance (HSS) is a known liver-specific but species-nonspecific growth factor. In the present study we examined the activity of the endogenously produced HSS in an established experimental model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA). FHF was induced by three consecutive intraperitoneal injections of TAA (400 mg/kg body weight) in rats, at time intervals of 24 hr. The animals were killed at 0, 6, 12, or 18 hr following the last injection of TAA. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of liver thymidine kinase (EC 2.7.1.21), and the assessment of mitotic index in hepatocytes were used to estimate liver regeneration. HSS extract obtained from the livers of TAA-treated rats, sacrificed at the above-mentioned time points was tested for its activity. Increased HSS activity was noted in all TAA-treated animals, presenting a peak at 12 hr following the third TAA dose, suggesting active participation of this growth factor in hepatocyte replication in this animal model of FHF and encephalopathy. It may also be suggested that up-regulation of HSS activity could be used in future as a therapeutic approach in FHF

Granulocyte-colony stimulating factor administration ameliorates liver regeneration in animal model of fulminant hepatic failure and encephalopathy

It has previously been shown that recombinant granulocyte-colony stimulating factor (rG-CSF) accelerates and enhances hepatocyte proliferation in partially hepatectomized rats. In the present study, we examined the effect of rG-CSF administration on liver injury, regeneration, and survival outcome in an experimental rat model of fulminant hepatic failure (FHF) and encephalopathy induced by repeated injections of thioacetamide (TAA). FHF was induced in adult male Wistar rats by three consecutive intraperitoneal injections of TAA, at intervals of 24 hr. The animals were also injected with either saline or rG-CSF. Serum biochemical parameters and blood ammonia levels, liver histology, stage of hepatic encephalopathy, and survival were statistically significantly improved in TAA-intoxicated and rG-CSF- treated rats compared to TAA-intoxicated and saline-treated ones. Furthermore, rG-CSF not only ameliorated the histologically evident liver injury in a statistically significant manner but also enhanced the proliferative capacity of the hepatocytes. Our data confirm the beneficial effect of rG-CSF administration in this animal model of FHF and encephalopathy, supporting evidence for a possible use of rG-CSF as supportive therapy in the management of FHF

Effect of two forms of granulocyte-colony-stimulating factor on hepatic regeneration after 70% partial hepatectomy in rats

1. The purpose of this study was to determine whether the commercially available forms of granulocyte-colony-stimulating factor exert the same beneficial effect on hepatic regeneration after 70% partial hepatectomy in rats, Adult male Wistar rats received either the two commercially available forms of granulocyte-colony-stimulating factor (Filgrastim or Lenograstim), or saline, simultaneously with partial hepatectomy, Hepatic regeneration was documented by determining [H-3]thymidine incorporation into hepatic DNA, liver thymidine kinase activity, mitotic index and proliferating cell nuclear antigen immunostaining, at various time points after partial hepatectomy. 2. DNA biosynthesis, liver thymidine kinase activity and mitotic index of hepatocytes were not only enhanced (P < 0.001) in rats that received 150 mu g of Filgrastim or Lenograstim/kg of body weight, but occurred earlier than in saline-treated partially hepatectomized rats, The administration of both forms of granulocyte-colony-stimulating factor, at the dose of 15 mu g/kg of body weight, did not affect liver proliferative capacity, compared with observations in simply partially hepatectomized rats. High mitotic and proliferating cell nuclear antigen indices appeared earlier than those estimated in simply partially hepatectomized rats, when 150 mu g of Filgrastim or Lenograstim/kg of body weight were administered. 3. These findings suggest that both pharmacologically available forms of granulocyte-colony-stimulating factor at a dose of 150 mu g/kg of body weight are able to augment liver regenerative capacity, to the same extent, in this animal model of controlled hepatic proliferation

Effect of interferon-alpha(2b) administration on rat liver regeneration after partial hepatectomy

The purpose of the present study was to delineate the effect of interferon-alpha(2b) (IFN-alpha(2b)) administration on the liver regenerative capacity after partial hepatectomy in rats. The administration of IFN-alpha(2b) simultaneously with partial hepatectomy did not affect hepatic proliferation in a statistically significant manner. When IFN-alpha(2b) was administered either 2 or 12 hr postoperatively, an inhibition of hepatocyte proliferation was observed 24 hr postoperatively, while at further time intervals up to 48 hr, DNA synthesis remained similar to that observed in the simply partially hepatectomized rats, The enzyme thymidine kinase (TK), has been implicated in the suppression of proliferation in interferon-treated cell cultures, In all IFN-alpha(2b)-treated groups of rats, alterations of TK activity were observed without being correlated to the liver regenerative status, Additionally, the administration of the polyamine putrescine in partially hepatectomized rats treated at the time of surgery with IFN strongly enhanced TK activity, but did not affect DNA biosynthesis, In the above-mentioned in vivo model of controlled cellular proliferation, the administration of IFN-alpha(2b) affected the rate of hepatocyte proliferation depending on the time of its administration; this effect was not correlated to the enzymatic activity of TK, as inhibited TK activity is responsible for the suppressed DNA synthesis in in vitro systems