Effect of 5-HT7 receptor blockade on liver regeneration after 60-70% partial hepatectomy.

BACKGROUND: Serotonin exhibits a vast repertoire of actions including cell proliferation and differentiation. The effect of serotonin, as an incomplete mitogen, on liver regeneration has recently been unveiled and is mediated through 5-HT2 receptor. The aim of the present study was to investigate the effect of 5-HT7 receptor blockade on liver regeneration after partial hepatectomy. METHODS: Male Wistar rats were subjected to 60-70% partial hepatectomy. 5-HT7 receptor blockade was applied by intraperitoneal administration of SB-269970 hydrochloride two hours prior to and sixteen hours after partial hepatectomy and by intraperitoneal administration of SB-258719 sixteen hours after partial hepatectomy. Animals were sacrificed at different time points until 72 h after partial hepatectomy. Liver regeneration was evaluated by [(3)H]-thymidine incorporation into hepatic DNA, the mitotic index in hematoxylin-eosin (HE) sections and by immunochemical detection of Ki67 nuclear antigen. Reversion of 5-HT7 blockade was performed by intraperitoneal administration of AS-19. Serum and liver tissue lipids were also quantified. RESULTS: Liver regeneration peaked at 24 h ([(3)H]-thymidine incorporation into hepatic DNA and mitotic index by immunochemical detection of Ki67) and at 32 h (mitotic index in HE sections) in the control group of rats. 5-HT7 receptor blockade had no effect on liver regeneration when applied 2 h prior to partial hepatectomy. Liver regeneration was greatly attenuated when blockade of 5-HT7 receptor was applied (by SB-258719 and SB-269970) at 16 h after partial hepatectomy and peaked at 32 h ([(3)H]-thymidine incorporation into hepatic DNA and mitotic index by immunochemical detection of Ki67) and 40 h (mitotic index in HE sections) after partial hepatectomy. AS-19 administration totally reversed the observed attenuation of liver regeneration. CONCLUSIONS: In conclusion, 5-HT7 receptor is a novel type of serotonin receptor implicated in hepatocyte proliferation.

Evaluation of IScore validity in a Greek cohort of patients with type 2 diabetes.

BACKGROUND: Diabetes constitutes a risk factor for stroke that also aggravates stroke prognosis. Several prognostic models have been developed for the evaluation of neurologic status, severity, short-term functional outcome and mortality of stroke patients. IScore is a novel tool recently developed in order to predict mortality rates within 30 days and 1 year after ischemic stroke and diabetes is not included in the scoring scale of IScore. The aim of the present study was to evaluate and compare IScore validity in ischemic stroke patients with and without diabetes. METHODS: This prospective study included 312 consecutive Caucasian patients with type 2 diabetes and 222 Caucasian patients without diabetes admitted for ischemic stroke in a tertiary Greek hospital. Thirty-day and 1-year IScores were individually calculated for each patient and actual mortality was monitored at the same time intervals. IScore's predictive ability and calibration was evaluated and compared for ischemic stroke patients with and without diabetes. The performance of IScore for predicting 30 and 1-year mortality between patients with and without diabetes was assessed by determining the calibration and discrimination of the score. The area under the receiver operating characteristic curve was used to evaluate the discriminative ability of IScore for patients with and without diabetes, whereas the calibration of IScore was assessed by the Hosmer-Lemeshow goodness-of fit statistic. RESULTS: Baseline population characteristics and mortality rates did not differ significantly for both cohorts. IScore values were significantly higher for patients with diabetes at 30 days and 1 year after ischemic stroke and patients with diabetes presented more frequently with lacunar strokes. Based on ROC curves analysis IScore's predictive ability for 30 day mortality was excellent, without statistically significant difference, for both cohorts. Predictive ability for 1 year mortality was also excellent for both groups with significantly better ability for patients with diabetes especially at high score values. Calibration of the model was good for both groups of patients. CONCLUSIONS: IScore accurately predicts mortality in acute ischemic stroke Caucasian patients with and without diabetes with higher efficacy in predicting 1 year mortality in patients with diabetes especially with high scores.

Gadolinium chloride pretreatment ameliorates acute cadmium-induced hepatotoxicity.

Cadmium is a known industrial and environmental pollutant. It causes hepatotoxicity upon acute administration. Features of cadmium-induced acute hepatoxicity encompass necrosis, apoptosis, peliosis and inflammatory infiltration. Gadolinium chloride (GdCl3) may prevent cadmium-induced hepatotoxicity by suppressing Kupffer cells. The effect of GdCl3 pretreatment on a model of acute cadmium-induced liver injury was investigated. Male Wistar rats 4-5 months old were injected intraperitoneally with normal saline followed by cadmium chloride (CdCl2; 6.5 mg/kg) or GdCl3 (10 mg/kg) followed by CdCl2 (6.5 mg/kg; groups I and II, respectively). Rats of both the groups were killed at 9, 12, 16, 24, 48 and 60 h after cadmium intoxication. Liver sections were analyzed for necrosis, apoptosis, peliosis and mitoses. Liver regeneration was also evaluated by tritiated thymidine incorporation into hepatic DNA. Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also determined. Hepatic necrosis, hepatocyte and nonparenchymal cell apoptosis and macroscopic and microscopic types of peliosis hepatis were minimized by gadolinium pretreatment. Serum levels of AST and ALT were also greatly diminished in rats of group II. Tritiated thymidine incorporation into hepatic DNA was increased in gadolinium pretreatment rats. Kupffer cell activation was minimal in both the groups of rats. Gadolinium pretreatment attenuates acute cadmium-induced liver injury in young Wistar rats, with mechanisms other than Kupffer cell elimination.

Effect of 5-HT(2) receptor blockade on cadmium-induced acute toxicity.

The protective effect of 5-HT(2) receptor blockade with ketanserin or ritanserin against cadmium liver injury was investigated. Male Wistar rats were injected intraperitoneally with a sublethal dose of cadmium (3.5 mg/kg body weight). Rats were treated with normal saline (group I), ketanserin (3 mg/kg body weight; group II), or ritanserin (3 mg/kg body weight; group III) 2 hr prior and 4 hr after cadmium administration and killed at different time points. Hematoxylin/eosin-stained liver sections were assessed for necrosis, apoptosis, peliosis, mitoses, and inflammatory infiltration. Apoptosis was also quantified by the TUNEL assay. Nonparenchymal liver cells and activated Kupffer cells were identified histochemically. Necrosis, hepatocyte apoptosis, nonparenchymal cell apoptosis, and macroscopic and microscopic peliosis were markedly reduced or minimized in ketanserin- or ritanserin-treated rats. The observed protective effect was almost identical for both ketanserin and ritanserin administration. 5-HT(2) receptor blockade exerts a protective effect against acute cadmium-induced hepatotoxicity.

Peliosis hepatis: microscopic and macroscopic type, time pattern, and correlation with liver cell apoptosis in a model of toxic liver injury.

Macroscopic and microscopic types of peliosis hepatis, time pattern, and correlation with hepatocyte and sinusoidal cell apoptosis were investigated. Male Wistar rats were injected with a dose of cadmium (6.5 mg CdCl(2)/kg body weight, intraperitoneally; group I). Putrescine (300 micromol/kg body weight, intraperitoneally; group II) was injected at 2, 5, and 8 hours and vascular endothelial growth factor (VEGF; 400 ng/animal, intravenously; group III) at 2 hours. Animals from each group were humanely killed 0, 6, 12, 24, 48, or 60 hours after cadmium intoxication. Liver tissue was histologically assessed for necrosis, apoptosis, and peliosis. Apoptosis was also quantified by the TUNEL assay for hepatocytes and nonparenchymal liver cells. The discrimination between hepatic cell subpopulations was done histochemically. Sinusoidal cell apoptosis and macroscopic peliosis hepatis evolved in a monophasic pattern and correlated closely. Putrescine or VEGF administration totally reversed macroscopic peliosis. Putrescine exerted a major protective effect on hepatocytes, whereas the protective effect of VEGF was more pronounced for nonparenchymal liver cells. Microscopic peliosis also evolved in a monophasic pattern preceding macroscopic type. The extent of the lesion was reduced by putrescine and almost totally reversed by VEGF. Macroscopic peliosis progresses as a compound lesion closely correlating with nonparenchymal cell apoptosis. Both hepatocyte and nonparenchymal cell injury are prerequisites for the genesis of the lesion. Microscopic peliosis precedes macroscopic peliosis and up to a degree seems to be independent of initial hepatocyte injury, but it seems to depend on nonparenchymal cell injury.

The effect of hepatic stimulator substance (HSS) on liver regeneration arrest induced by 5-HT2 receptor blockade.

BACKGROUND: The restorative effect of hepatic stimulator substance (HSS) against hepatic regeneration arrest induced by 5-HT2 receptor blockade was investigated. MATERIALS AND METHODS: Male Wistar rats were subjected to 60-70% partial hepatectomy and to 5-HT2 receptor blockade at 16 h after partial hepatectomy by ketanserin administration (6 mg/kg bodyweight intraperitoneally; group I). HSS at the dose of 100 mg protein/kg bodyweight was administered at 10 or 17 h after partial hepatectomy in ketanserin-treated rats (groups II and III). The mitotic index in hematoxylin-eosin-stained liver sections, immunochemical detection of PCNA and Ki 67 nuclear antigens and the rate of [3H]-thymidine incorporation into hepatic DNA were used as indices of liver regeneration. RESULTS: Liver regeneration, as evaluated by [3H]-thymidine incorporation into hepatic DNA, mitotic index, PCNA and Ki67 nuclear antigens, peaked at 40 h in groups I, II and III of rats and no significant differences were observed between the studied groups. CONCLUSION: HSS administration is not capable of reversing the liver regeneration arrest induced by 5-HT2 receptor blockade.

The role of hepatic stimulator substance (HSS) on liver regeneration arrest induced by cadmium.

BACKGROUND: The mechanism of cadmium-induced liver regeneration arrest in relation to hepatic stimulator substance (HSS) biological activity was investigated. MATERIALS AND METHODS: In Wistar rats subjected to 65 - 70% partial hepatectomy, saline, cadmium, cadmium and HSS were administered. The rats were also subjected to 30 - 34% partial hepatectomy. Mitotic index, immunochemistry for PCNA, 3[H]-thymidine incorporation into DNA and thymidine kinase activity were used as indices of liver regeneration. HSS biological activity was evaluated in all groups of rats using a bioassay. RESULTS: Liver regeneration and HSS activity were arrested by cadmium during the first 24 h after partial hepatectomy. Both in normal and in cadmium-treated rats, the HSS activity was increased and liver regeneration coincided. HSS activity was stable in 30 - 34% hepatectomized rats. HSS administration was able to restore liver regeneration arrest induced by cadmium. CONCLUSION: The biological activity of HSS increased at the time of G1/S transition of hepatocytes in the cell cycle and no increase was observed with asynchronous G1/S transition (30 - 34% partial hepatectomy). The suppression of HSS biological activity by cadmium seems to represent an important factor for liver regeneration arrest induced by the metal and HSS administration is able to restore liver regeneration.

The hepatoprotective effect of hepatic stimulator substance (HSS) against liver regeneration arrest induced by acute ethanol intoxication.

Male Wistar rats were randomized to receive ethanol (2.5 ml/kg by gastric intubation every 8 hr; group I), equal volumes of isocaloric to ethanol sucrose solution (group II), or ethanol and HSS (100 mg/kg intraperitoneally 10 and 16 hr after partial hepatectomy; groups III and IV, respectively) for up to 96 hr after partial hepatectomy, with ethanol administration starting 1 hr prior to partial hepatectomy. Animals were killed at 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 60, and 96 hr after partial hepatectomy. The rate of liver regeneration was evaluated by the mitotic index in H&E-stained sections, immunochemical detection of Ki67 nuclear antigen, rate of [3H]thymidine incorporation into hepatic DNA, and liver thymidine kinase enzymatic activity. The biological activity of HSS in groups I and II rats was evaluated using a bioassay. Ethanol administration arrested liver regeneration during the first 32 hr after partial hepatectomy and suppressed HSS activity throughout the period examined. Liver regeneration progressed after 32 hr despite the low levels of HSS activity. HSS administration at 10 and 16 hr reversed liver regeneration arrest induced by ethanol. Acute ethanol administration induces cell cycle arrest during the first 32 hr after partial hepatectomy and suppression of HSS biological activity seems to contribute to this effect. HSS administration reversed the inhibitory effect of ethanol on liver regeneration and caused synchronized entrance of hepatocytes in the S phase of the cell cycle. HSS seems to participate in the network of growth factors controlling the G1/S cell cycle checkpoint.

The hepatoprotective effect of putrescine against cadmium-induced acute liver injury.

The hepatoprotective effect of putrescine against cadmium liver injury was investigated. Male Wistar rats were injected with a dose of cadmium (6.5 mg CdCl(2)/kg bodyweight, intraperitoneally). Normal saline (group I) or putrescine (300 micro mol/kg bodyweight; group II) were injected 2, 5 and 8 h later. A number of animals of both groups were killed 0, 12, 16, 24, 48 or 60 h after cadmium intoxication. Liver tissue was histologically assessed for necrosis, apoptosis, peliosis, mitoses, and inflammatory infiltration. Apoptosis was also quantified by the TUNEL assay for hepatocytes and nonparenchymal liver cells. The discrimination between hepatic cell subpopulations was achieved histochemically. The mitotic index in hematoxylin-eosin-stained sections and by the immunochemical detection of Ki67 nuclear antigen, (3)H-thymidine incorporation into hepatic DNA, and hepatic thymidine kinase activity were all used as indices of liver regeneration. Both hepatocyte apoptosis and liver necrosis evolved in a biphasic temporal pattern. Nonparenchymal cell apoptosis and peliosis hepatis evolved in a monophasic pattern and were correlated closely. Putrescine administration totally reversed liver necrosis and hepatocyte apoptosis. The time profile of nonparenchymal apoptosis was altered and peliosis hepatis was also totally attenuated. In conclusion, putrescine protected hepatocytes and modulated the mechanism of cadmium-induced acute hepatotoxicity.