Hepatic protection by 16, 16-dimethyl prostaglandin E2 (DMPG) against acute aflatoxin B1-induced injury in the rat

Arachidonic acid and lipoxin A4 attenuate alloxan-induced cytotoxicity to RIN5F cells in vitro and type 1 diabetes mellitus in vivo

OBJECTIVE

We studied whether polyunsaturated fatty acids (PUFAs) can protect rat insulinoma (RIN5F) cells against alloxan-induced apoptosis in vitro and type 1 diabetes mellitus (type 1 DM) in vivo and if so, mechanism of this beneficial action.

MATERIAL AND METHODS

In vitro study was conducted using RIN5F cells while in vivo study was performed in Wistar rats. The effect of PUFAs, cyclo-oxygenase and lipoxygenase inhibitors, various eicosanoids and PUFAs metabolites: lipoxin A4 (LXA4), resolvin D2 and protectin against alloxan-induced cytotoxicity to RIN5F cells and type 1 DM was studied. Expression of PDX1, P65 NF-kB and IKB in RIN5F cells and Nrf2, GLUT2, COX2, iNOS protein levels in the pancreatic tissue and plasma glucose, insulin and tumor necrosis factor-α and antioxidants, lipid peroxides and nitric oxide were measured.

RESULTS

Of all, arachidonic acid (AA) was found to be the most effective against alloxan-induced cytotoxicity to RIN5F cells and preventing type 1 DM. Both cyclo-oxygenase and lipoxygenase inhibitors did not block the beneficial actions of AA in vitro and in vivo. Alloxan inhibited LXA4 production by RIN5F cells and in alloxan-induced type 1 DM Wistar rats. AA-treatment restored LXA4 levels to normal both in vitro and in vivo. LXA4 protected RIN5F cells against alloxan-induced cytotoxicity and prevented type 1 DM and restored expression of Nrf2, Glut2, COX2, and iNOS genes and abnormal antioxidants to near normal.

DISCUSSION

AA seems to bring about its beneficial actions against alloxan-induced cytotoxicity and type 1 DM by enhancing the production of LXA4. © 2016 BioFactors, 43(2):251-271, 2017.

Expression of p53 during apoptosis induced by D-galactosamine and the protective role of PGE1 in cultured rat hepatocytes

p53 is a critical player in the prevention of tumor development. It can contribute directly to DNA repair and inhibition of angiogenesis and subsequently to the induction of apoptosis. The regulation of p53 expression is mediated by the transcription factor NF-kappaB. This includes regulation of p53 protein stability, control of its subcellular localization and conformational changes that allow activation of the DNA binding activity of p53. Rat hepatocytes were isolated from male Wistar rats following collagenase perfusion of liver. We examined the change in the expression level of p53 by western blotting in hepatocytes and its effect on apoptosis as a response of treatment with D-galactosamine, prostaglandin E1 and/or the Proteosome Inhibitor (PSI). A kinetic study of the extracellular lactate dehydrogenase activity, NF-kappaB activation, induced nitric oxide synthase expression and nitric oxide production was carried out in hepatocytes. The addition of prostaglandin E1 to control and D-galactosamine-treated hepatocytes increased p53 expression in the cytoplasm during 24 h. While the addition of PSI in the absence of prostaglandin E1 decreased p53 expression at 5 mM D-galactosamine. This inhibition is reversed in the presence of prostaglandin E1 at 5 and 40 mM D-galactosamine. The protective action of prostaglandin E1 against the apoptotic effect of D-galactosamine is mediated by NF-kappaB activation, induced nitric oxide synthase and p53 expression.

Effect of prostaglandins against alloxan-induced diabetes mellitus

Previously, we observed that alloxan-induced in vitro cytotoxicity and apoptosis in an insulin secreting rat insulinoma, RIN, cells was prevented by prior exposure to prostaglandin (PG) E(1), PGE(2), PGI(2), PGF(1)(alpha), and PGF(3)(alpha) (P<0.05 compared to alloxan), whereas thromboxane B(2) (TXB(2)) and 6-keto-PGF(1)(alpha) were ineffective. In an extension of these studies, we now report that prior intraperitoneal administration of PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) prevented alloxan-induced diabetes mellitus in male Wistar rats, whereas PGI(2), TXB(2), and 6-keto PGF(1)(alpha) were not that effective. PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) not only attenuated chemical-induced diabetes mellitus but also restored the antioxidant status to normal range in red blood cells and pancreas. These results suggest that PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) can abrogate chemically induced diabetes mellitus in experimental animals and attenuate the oxidant stress that occurs in diabetes mellitus.

Effect of prostaglandins against alloxan-induced cytotoxicity to insulin secreting insulinoma RIN cells in vitro

In the present study, we studied the effect of various prostaglandins (PGs) on alloxan-induced cytotoxicity to rat insulinoma (RIN) cells. Of all the PGs tested, PGE(1), PGE(2), PGI(2), PGF(1 alpha), and PGF(3 alpha) protected RIN cells from alloxan-induced cytotoxicity (P<0.05 compared to alloxan), whereas thromboxane B(2) and 6-keto-PGF(1 alpha) were not effective. PGE(1) induces a statistically significant increase in the activities of superoxide dismutase and glutathione peroxidase and decrease in lipid peroxides in alloxan-treated RIN cells (P<0.001). PGE(1) restored nitric oxide/lipid peroxide ratio to normalcy, suggesting that PGE(1) suppresses oxidant stress induced by alloxan in RIN cells in vitro. Furthermore, PGE(1) prevented DNA damage and apoptosis induced by alloxan. These results indicate that PGE(1) prevents alloxan-induced cytotoxicity to RIN cells in vitro.

Immunomodulatory activity of TNF-alpha during acute liver injury induced by D-galactosamine and its protection by PGE1 in rats

Tumour necrosis factor-alpha (TNF-alpha) mediates hepatocyte cell death by D-galactosamine (D-GalN) and its protection by prostaglandin E(1) (PGE(1)). The activation of immune system plays an important role in the development of liver injury. TNF-alpha and PGE(1) regulate the activity and cytokine release of different inflammatory cells. The present study was undertaken to determine if the noxious or hepatic protective properties of TNF-alpha during D-GalN-induced liver injury was related to an alteration by PGE(1) of the immunoregulatory activity of TNF-alpha. The role of TNF-alpha was assessed by anti-TNF-alpha antibodies to D-GalN-treated rats in the presence or absence of PGE(1). D-GalN enhanced the percentage of monocytes and T lymphocytes in the total peripheral blood mononuclear cells (PBMCs). D-GalN enhanced the activation degree of monocytes, but reduced that of T lymphocytes. D-GalN also enhanced TNF-alpha, IL-1alpha, IL-6 and IFN-gamma concentrations in blood. Anti-TNF-alpha antibodies abolished all immunological changes and greatly reduced liver damage induced by D-GalN. The protection by PGE(1) against D-GalN liver injury was associated with an increase in TNF-alpha concentration and a reduction of IL-1alpha and IL-6. These changes were associated with a reduction of monocyte activation degree and a recovery of that of T lymphocytes. Although anti-TNF-alpha antibodies abolished the protection by PGE(1) against D-GalN-liver injury, they did not essentially counteract the effect of the prostanoid in all immunological parameters studied. The present study showed that the protection against D-GalN liver damage by PGE(1) or anti-TNF-alpha was associated with similar effects on the inflammatory parameters studied. Nevertheless, the abolishment of liver protection by PGE(1) with anti-TNF-alpha in D-GalN-treated rats in the presence of a protective cytokine profile suggests that the release of TNF-alpha induced by PGE(1) pre-administration was exerting a direct protective effect on hepatocytes against D-GalN injury. Consequently, the effect of PGE(1) on inflammatory parameters studied during liver injury was unrelated to TNF-alpha.

Long-term administration of PGE1 increases liver fibrosis and collateral blood flow in bile-duct-ligated rats

BACKGROUND/AIMS

The aim of this study was to assess the effect of early and chronic administration of a prostaglandin E1 analogue (misoprostol) in the prevention of liver fibrosis and portal hypertension.

METHODS

Liver fibrosis was induced by bile duct ligation. Controls had a sham operation. Bile-duct-ligated rats were divided into two groups: placebo (vehicle only) and misoprostol (10 microg/d by gavage) for 4 weeks after surgery. Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline content and serum hyaluronate. Systemic and splanchnic hemodynamics were evaluated including spleno-renal shunt blood flow by the transit-time ultrasound technique.

RESULTS

Mean arterial pressure was significantly lower in the misoprostol group (p<0.01). There was an unexpected increase in fibrosis parameters in the misoprostol group compared to the placebo group, e.g. area of fibrosis: 9.5+/-4.0 vs 15.0+/-8.1% (p<0.05). Spleno-renal shunt blood flow was significantly higher in the misoprostol group than in the placebo group (4.6+/-3.7 vs 2.2+/-2.0 ml/min, p<0.05) while portal pressure was unchanged.

CONCLUSIONS

The early and chronic administration of misoprostol enhances porto-collateral circulation blood flow and the development of liver fibrosis in bile-duct-ligated rats.

Effect of PGE1 on TNF-alpha status and hepatic D-galactosamine-induced apoptosis in rats

Prostaglandin E1 has hepatoprotective properties in several clinical and experimental models of liver dysfunction. Hepatotoxicity induced by D-galactosamine (D-GalN) is a suitable animal model of human acute hepatic failure. The aim of the study was to investigate if prostaglandin E1 (PGE1) protection against hepatic D-GalN-induced apoptosis was related to tumour necrosis factor-alpha (TNF-alpha) content in serum. This cytokine is associated with in vitro apoptosis and general inflammatory disorders. In this study, PGE1 was administered 30 min before D-GalN to rats. In other experiments, several doses of TNF-alpha were administered 15min after PGE1 to D-Ga1N-treated rats. Several parameters related to apoptosis and necrosis were measured by flow cytometry, gel electrophoresis, biochemical analysis, and optical and electron microscopy. Tumour necrosis factor-alpha was quantified by competitive enzyme-linked immunosorbent assay (ELISA). PGE1 by itself did not modify the cell cycle of hepatocytes and liver toxicity, but increased TNF-alpha in serum in comparison with the control group. D-Galactosamine increased the percentage of hepatocytes in apoptosis and in the S phase of the cell cycle, and decreased those in G0/G1. Such an increase of hepatocytes in apoptosis was correlated with a higher number of apoptotic bodies and DNA fragmentation in liver than control samples. Also, D-GalN increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and TNF-alpha in serum compared with the control group. Pre-administration of PGE1 to D-GalN-treated rats reduced all the parameters of apoptosis and necrosis in liver, and increased additionallyTNF-alpha content in serum. In those experiments where low doses of TNF-alpha were administered to PGE1 and D-GalN-treated rats an inverse relationship appeared between TNF-alpha and ALT content in serum. In conclusion, the protective effects of PGE1 on D-GalN-induced apoptosis may be linked to its capacity to modulate cell division and/or its immunomodulatory activity. In this sense, our experimental results suggest that TNF-alpha could be involved in protection or exacerbation of liver damage in relation to the pathophysiological status of the liver.

Liver cirrhosis induces renal and liver phospholipase A2 activity in rats

Maintenance of renal function in liver cirrhosis requires increased synthesis of arachidonic acid derived prostaglandin metabolites. Arachidonate metabolites have been reported to be involved in modulation of liver damage. The purpose of the present study was to establish whether the first enzyme of the prostaglandin cascade synthesis, the phospholipase A2(PLA2) is altered in liver cirrhosis induced by bile duct excision. The mRNA of PLA2(group I and II) and annexin-I a presumptive inhibitor of PLA2 enzyme was measured by PCR using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an internal standard. The mean mRNA ratio of group II PLA2/GAPDH was increased in liver tissue by 126% (P < 0.001) and in kidney tissue by 263% (P < 0.006) following induction of liver cirrhosis. The increase in group II PLA2 mRNA in cirrhotic animals was reflected by an increase in PLA2 protein and enzyme activity in both liver and kidney tissues. Since the mRNA of group I PLA2 was not detectable and Group IV PLA2 activity measured in liver and kidney tissue samples was very low and not changed following induction of cirrhosis, it is likely that the major PLA2 activity measured in liver and kidney corresponds to group II PLA2 enzyme. The mean mRNA ratio of annexin-I/GAPDH was increased in liver tissue by 115% (P < 0.05) but unchanged in kidney tissue following induction of cirrhosis. The protein content of annexin-I and -V were not affected by bile duct excision in liver and kidney tissue indicating that upregulation of group II PLA2 activity was not due to downregulation of annexin-I or -V. Group II PLA2 activity of glomerular mesangial cells stimulated by interleukin-1 beta was enhanced by bile juice and various bile salts. In conclusion, activity of group II PLA2 is upregulated partly due to enhanced transcription and translation in cirrhosis and is furthermore augmented by elevated levels of bile salts.

Prostaglandins in liver disease and liver transplantation

This brief review summarizes the physiology and pharmacology of eicosanoids and describes how they have been tested for possible application in liver disease and transplantation. The objective is to trace the stepwise application from the laboratory to the bedside. Although many questions remain to be answered, the observations summarized in this article have opened up new and potentially rewarding prospects in application to liver disease.

Hepatic ischemia-reperfusion injury modification during liver surgery in rats: pretreatment with nifedipine or misoprostol

The aim of the study was to determine if pretreatment with misoprostol (a prostaglandin analogue) or nifedipine (a calcium antagonist), know protectants of the whole liver, would ameliorate the ischemia-reperfusion injury (IRI) of resected liver associated with vascular occlusion. Male Wistar rats were allocated to 5 groups (n = 20 each group): sham-operated, liver resection only, liver resection plus pretreatment with 0.1 mg/kg misoprostol, 10 mg/kg, or 2 mg/kg nifedipine during the 3 days before IRI with liver resection. Fifteen percent of the liver was made ischemic by 30-minute continuous vascular occlusion, and the remaining 85% nonischemic liver was resected. The model was designed to have survival of the rats so that liver function could be studied over 3 weeks. Seventeen of 20 control resection rats survived indicating a suitable model for study. The bilirubin level was reduced by 25% on postoperative days 3 through 23 with misoprostol. The serum alanine aminotransferase (ALT) peak was significantly lower on day 1 with misoprostol and high-dose nifedipine (both reduced to half the control resection value). There was a modest but significant reduction of serum alkaline phosphatase (SAP) for low-dose nifedipine on days 1, 2, and 23. Prothrombin had a lower peak and lower values on days 1 through 4 with misoprostol. Liver histological changes were minor, being cytoplasmic vacuolization only, and was slightly more marked in the nifedipine groups. Preoperative misoprostol 0.1 mg/kg and nifedipine 10 mg/kg each ameliorate the IRI associated with liver resection, as measured by liver function tests. Different aspects of liver function were altered by the different agents. These results justify initiating a trial for human liver resections.

Misoprostol protection against acetaminophen-induced hepatotoxicity in the rat

The hepatoprotective effects of misoprostol on acetaminophen (APAP)-induced toxicity were studied in the rat. Liver injury was evaluated at 36 hr after APAP administration by measuring serum ornithine carbamoyltransferase (OCT) and alanine aminotransferase (ALT) levels, by using tetranitroblue tetrazolium (TNBT) staining and by histological analysis. After APAP administration, peak serum levels of the drug were detected at 15 min. Liver GSH was depleted from control levels of 448 +/- 48 micrograms/g to 82 +/- 2 micrograms/g (P < 0.01) within 3 hr. Serum ALT levels increased significantly after 16 hr and H&E staining revealed significant hepatic necrosis after 12 hr. Rats treated with misoprostol before and after APAP administration showed reduced OCT and ALT levels at 36 hr of overdose (454 +/- 446 IU/liter and 2571 +/- 2944 IU/liter, respectively) compared to those without misoprostol treatment (1348 +/- 480 IU/liter and 6077 +/- 3025 IU/liter, respectively, P < 0.01). TNBT staining showed a reduced area of damage from 28.6 +/- 22.3% to 7.3 +/- 8.9% (P < 0.01), and H&E staining also showed less extensive hepatic necrosis in rats treated with misoprostol before and after the overdose. In a time sequence study, misoprostol treatment starting within 10 hr of overdose showed the same protective effect as when it was given before and after APAP ingestion. No protection was detected when the treatment was started during the development of hepatic injury. However, misoprostol given when injury was established seemed to be protective. Our results show that misoprostol protects the liver against APAP-induced injury if given within 10 hr of overdose.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of acetaminophen hepatitis by prostaglandin E2. A histopathological study

Acute acetaminophen hepatitis was produced in three groups of five rats given 1600 mg/kg by gavage. The protective effect of 16,16-dimethyl prostaglandin E2, 200 micrograms/kg administered subcutaneously 30 min later, was compared to the protective effect of N-acetylcysteine 1 g/kg similarly administered. All animals were killed at 24 hr, and liver tissues were compared histologically to the damage found in acetaminophen-treated controls and untreated anatomic controls. Serum transaminase values at 24 hr exceeded 1000 units in the acetaminophen control group, averaged 658 units in the acetylcysteine treated group, and were near normal (75 units) in the prostaglandin treated group (P < 0.02). Liver samples (1 cm3) were removed terminally at 24 hr. Liver damage was assessed without reference to precedent history. Histopathologically, damage was most severe in the acetaminophen control group, mainly in pericentral lobular zones. The prostaglandin-treated group showed considerably less damage, which was confined to the hepatic vein area. The acetylcysteine-treated group showed an intermediate degree of damage. We conclude that dmPGE2, given 30 min after ingestion of acetaminophen was found to be more effective in limiting liver damage than NAC in this rat model.

Liver cytoprotection by prostaglandins

During the last decade intensive work on the relationships between the liver and the arachidonic acid cascade has greatly expanded our knowledge of this area of research. The liver has emerged as the major organ participating in the degradation and elimination of arachidonate products of systemic origin. The synthesis in the liver of arachidonate products derived from the cyclooxygenase, lipoxygenase and cytochrome P450 system pathways has been demonstrated. The participation of leukotriene B4 and cysteinyl-leukotrienes as mediators of liver damage and the possible therapeutic usefulness of prostaglandins (PGs) in acute liver injury has attracted the interest of clinicians. This article reviews the essential features regarding the role of arachidonate metabolites in liver disease and specially focuses on the cytoprotective effects on the liver displayed by PGE2, PGE1, PGI2 and synthetic PG analogs in experimental models of liver damage induced by ischemia-reperfusion injury, carbon tetrachloride, bacterial lipopolysaccharide and viral hepatitis and on the possible mechanisms underlying liver cytoprotection in these experimental models. The therapeutic usefulness of PGs in clinical practice is critically analyzed on the basis of available evidence in patients with fulminant hepatic failure and primary graft nonfunction following liver transplantation.

Paracetamol toxicity and its prevention by cytoprotection with iloprost

In a well-established two phase model of paracetamol toxicity in hamster hepatocytes cell death was accompanied, but not preceded, by a rise in cytosolic free calcium [Ca2+]i. Cell death appears to involve reversible oxidative damage, possibly to the cytoskeleton or mitochondria. In this model low concentrations (10(-8) to 10(-14) M) of iloprost, a stable analogue of prostacyclin, offered protection against the toxic effects of paracetamol. In preliminary studies with a rat liver epithelial cell line transduced with murine P4501A2 the toxicity of paracetamol was attenuated by iloprost. Inhibition of protein synthesis with cycloheximide had no effect on paracetamol toxicity but abolished the cytoprotective effect of iloprost.

16,16-dimethyl prostaglandin E2 modulates aflatoxin B1-induced injury of rat hepatocytes in primary culture: possible role of cAMP

The hepatocellular cytoprotective effects of 16,16-dimethyl prostaglandin E2 (dmPGE2), an analogue of PGE2, were investigated using primary cultures of rat hepatocytes and aflatoxin B1 as the hepatotoxin. Lactic dehydrogenase (LDH) release by hepatocytes was used as an index of hepatotoxicity. When aflatoxin-treated hepatocytes were co-cultured with 16,16-dmPGE2 (0.01-0.5 micrograms/mL) LDH release was significantly reduced and ultrastructural changes of hepatocellular injury were markedly diminished. The magnitude of the cytoprotective effect was not dependent on the concentration of the prostaglandin over the range tested. A significant cytoprotective effect was also induced when hepatocellular cyclic AMP (cAMP) levels were increased by the addition of dibutyl-cAMP. In contrast to 16,16-dmPGE2, PGF2 alpha Tromethamine, an analogue of PGF2 alpha, which does not stimulate cAMP, induced insignificant changes in cytoprotection. These findings indicate that only a low concentration of 16,16-dmPGE2 (> or = 0.01 micrograms/mL) is necessary to induce a maximal hepatocellular cytoprotective effect and suggest that this effect may be dependent on activation of cAMP.

Arachidonate metabolism in D-galactosamine or carbon tetrachloride-induced acute and chronic liver injuries in rats

Arachidonate metabolism was examined in rats with experimentally induced acute and chronic liver injuries. Acute liver injury was induced by a single administration of D-galactosamine (D-Galn) and lipopolysaccharide (LPS) or carbon tetrachloride (CCl4). Chronic liver injury was produced by several administrations of CCl4 for 5 weeks. Non-parenchymal liver cells from rats with D-Galn/LPS-induced acute liver injury produced prominently leukotriene B4 and 5-hydroxy-arachidonic acid which were hardly synthesized by the normal rat liver. No apparent changes were observed in the arachidonate metabolism of the non-parenchymal cells of the acute CCl4-injured liver. In chronic liver injury, the production of 6-ketoprostaglandin F1 alpha, a stable metabolite of prostaglandin I2, by the non-parenchymal cell fraction was significantly enhanced in contrast with the fixed amount of the other arachidonate metabolites. These results suggested the arachidonate metabolism by non-parenchymal liver cells might change according to the pathogenesis of the liver disease.

Modulation of thioacetamide-induced hepatocellular necrosis by prostaglandins is associated with novel histologic changes

Cytoprotective effects of the prostaglandins 16,16-dimethyl PGE2 (dmPGE2) and PGF2 alpha tromethamine (PGF2 alpha) were evaluated in the rat model of acute hepatocellular necrosis induced by thioacetamide (TAA). dmPGE2 (100 micrograms/kg SC 8 hourly) did not induce a significant increase in survival when started after the onset of TAA-induced fulminant hepatic failure. However, priming with dmPGE2 (100 micrograms/kg SC 30 min before TAA) reduced TAA-induced elevations in serum ALT (684 +/- 68 (SEM) vs 274 +/- 135 IU/1, p less than 0.01). This phenomenon did not occur if dmPGE2 was administered after TAA or by the IP route. Modulation of TAA-induced centrizonal hepatocellular necrosis by dmPGE2 was associated with a striking increase in centrizonal ballooning of hepatocytes (p less than 0.01), and, as assessed by stereology, less hepatocellular necrosis and degenerative changes. PGF2 alpha, which in contrast to dmPGE2 does not act via cAMP, had no effect on TAA-induced changes in serum ALT or hepatic histology. These findings suggest that dmPGE2 decreases hepatocellular necrosis by activating surface membrane adenylate cyclase and consequently stimulating cAMP. Ballooning of hepatocytes could occur secondary to these membrane events and appears to be a marker of dmPGE2-induced cytoprotection in this model.

Cytoprotection by iloprost against paracetamol-induced toxicity in hamster isolated hepatocytes

1 The ability of iloprost (ZK36374) to protect hamster isolated hepatocytes from the toxic effects of paracetamol and its reactive metabolite N-acetyl-p-benzoquinoneimine (NABQI) was investigated. The cytoprotection provided by iloprost was compared with that of N-acetyl-L-cysteine. 2 Treatment of hepatocytes with either NABQI (0.4 mM) or paracetamol (2 mM) alone resulted in a considerable loss of cell viability, as assessed by trypan blue exclusion or leakage of lactate dehydrogenase, accompanied by an increase in the percentage of viable cells that were blebbed. N-acetyl-L-cysteine (1.25 mM) pretreatment diminished the loss of cell viability and the percentage of blebbed cells resulting from exposure to NABQI or paracetamol, whereas iloprost (10(-16) M to 10(-10) M) pretreatment reduced only the loss of cell viability, not the percentage of viable cells exhibiting blebbing. Pretreatment with N-acetyl-L-cysteine significantly attenuated the depletion by paracetamol of glutathione and decreased the covalent binding of [14C]-paracetamol to cellular proteins, whereas iloprost was without any such effects. 3 The effects of iloprost and N-acetyl-L-cysteine were also investigated by use of a model of paracetamol toxicity in which it is possible to study the biochemical events leading to cell injury separate from the generation of toxic metabolites. Hamster hepatocytes were incubated with paracetamol (4 mM) for 90 min at 37 degrees C during which metabolism of paracetamol occurs with minimal loss of cell viability. Following washing of cells, to remove paracetamol and its metabolites, there was a progressive loss of viability and increase in the percentage of cells exhibiting blebbing when incubated in buffer alone. Addition of either N-acetyl-L-cysteine (1.25 mM) or iloprost (10 14M to 10 -M), following washing, significantly reduced the expected loss of cell viability. Iloprost at concentrations outside this range was without effect.4. Paracetamol toxicity to isolated hepatocytes could be prevented or delayed by treatment with either N-acetyl-L-cysteine or iloprost, but whereas the former prevented or even reversed plasma membrane blebbing with a resultant reduction in the percentage of viable cells that were blebbed, the prostanoid appeared only to delay the progression from plasma membrane blebbing to loss of viability. Hence, the percentage of viable cells that were ultimately blebbed following exposure to paracetamol was not significantly reduced by addition of iloprost.5. Aspirin or ibuprofen exacerbated the loss of viability induced by prior incubation with paracetamol. Thus, there may be a role for endogenous prostaglandins in protecting hepatocytes from paracetamol toxicity.6. Iloprost is cytoprotective without any effect upon toxin metabolism or detoxication. The mechanism of action of iloprost probably does not involve induction of prostaglandin synthesis or activation of the previously-characterized prostacyclin receptor.

Successful reversal of primary graft non-function in a liver transplant patient treated with prostaglandin E1

A 63 year old woman with liver failure received a transplant from a 21 year old male diagnosed as brain dead following a motor accident. After the operation, bile production was virtually absent and aspartate transaminase (AST) values rose dramatically 40 h postoperatively. Primary non-function of the graft was diagnosed, and the patient put on an urgent list for retransplantation. At the same time a continuous intravenous infusion of PGE1 was administered. Aspartate transaminase levels decreased within 9 h and reached normal levels by the sixth postoperative day, when bile production began to increase. Liver function subsequently returned to normal.

Preventative effect of PGE1 for postoperative liver damage

The efficacy of a low dose of PGE(1)-use on the postoperative liver damage was evaluated. PGE(1) was infused in with the mean rate of 0.026 microg.kg(-1).min(-1) during surgical procedure to 93 patients under GO-enflurane anesthesia (the PG). Serum GOT, GPT and total bilirubin (TBIL) values measured before, at the end of (End) and 3 days (3d) after the operation were compared to those obtained from 43 patients without PGE(1) administration (the control). This dose of PGE(1) did not change blood pressure and heart rate, but slightly decreased Pa(O)(2). In patients with preoperative normal values of GOT, GPT and TBIL, increases in GOT, GPT and TBIL observed at End in the PG were significantly lower than those in the control (31.9 vs 72.2 IU, 25.9 vs 61.9 IU, 0.68 vs 0.83 mg.dl(-1), respectively). GOT, GPT and TBIL at 3d significantly increased in both groups, and these levels were identical between the two groups. In patients with preoperative abnormal values, only GOT at End increased in both groups, while no significant difference between the PG and the control group was noted. GOT at 3d and GPT at End and 3d did not significantly changed in either group. These results suggest that the low dose of PGE(1) administered during an operation prevents the development of postoperative liver damage, but does not treat the damaged hepatic cells.

Hepatocyte membrane stabilization by prostaglandins E1 and E2: favorable effects on rat liver injury

When prostaglandin (PG) E1 was continuously administered to rats from 24 hours before giving a dose of carbon tetrachloride, deranged serum glutamic pyruvic transaminase levels and prothrombin time were significantly reduced 12 hours after intoxication compared with controls. A similar effect of PGE1 was seen at 24 hours in D-galactosamine-intoxicated rats. Liver histology showed a comparable attenuation of injury in these rats. These results were consistent with reported effects of PGE2, suggesting that both prostaglandins may share a common pathway in protection against liver injury. When PGE1 or 16,16'-dimethyl PGE2 was added to the medium of primary cultured rat hepatocytes, lipid peroxidation-dependent killing of the cells by tert-butyl hydroperoxide was significantly attenuated without affecting the extent of malondialdehyde accumulation compared with controls. Both prostaglandins significantly reduced the extent of increased plasma membrane microviscosity of these cells assessed by 1-[4-(trimethyl-ammonio)phenyl]-6-phenyl-1,3,5-hexatriene. PGE1 and PGE2 may possess cytoprotective effects on liver parenchymal cells through stabilization of membrane microviscosity, which may contribute to protection against liver injury.

The effect of the prostaglandin analogue-misoprostol on rat liver mitochondria after chronic alcohol feeding

Rats fed ethanol (36% of total calories in a nutritionally adequate liquid diet) for 5 weeks develop functional alterations of hepatic mitochondria and steatosis of the liver. At the fatty liver stage, ADP-stimulated respiration of mitochondria was depressed in ethanol fed rats by 30% (p less than 0.001) with glutamate + malate and by 23% (p less than 0.001) with succinate as substrates. A similar decrease was noted in the respiratory control ratio (RCR) (34% and 29%, respectively). The total lipid content of the liver increased 2.6 fold (p less than 0.001). Mitochondrial dysfunction could be prevented, in part, by the treatment with a synthetic derivative of prostaglandin E1, misoprostol, at a mean daily dose of 80 micrograms/kg of body weight. The RCR with glutamate + malate as substrates was improved by 36% (p less than 0.05). We conclude that misoprostol attenuates several functional alterations in liver mitochondria during alcohol feeding.

Diagnosis and recommended management of esophageal perforation and rupture

Over the past 47 years (1937 to 1984), a total of 127 patients with esophageal perforation or rupture were evaluated at Duke Medical Center or the Durham Veterans Administration Medical Center. In 13 patients, the diagnosis was established at the time of autopsy and in the remaining 114, the diagnosis was established clinically. The etiology, radiological findings, underlying esophageal disease, time interval between onset of symptoms and therapy, and eventual outcome were evaluated. Patients with anastomotic leaks and those in whom carcinoma resulted in perforation or fistula were excluded. Iatrogenic causes were responsible for 55% of perforations, followed by spontaneous rupture in 15%, foreign body perforation in 14%, and traumatic perforation in 10%. Of the 127 patients, 114 underwent treatment involving primary closure (43%), drainage alone (28%), resection (9%), or nonoperative therapy (20%). The overall mortality among these 114 patients was 21%. Fourteen patients sustained a major complication requiring additional operative intervention. The overall mortality among patients requiring reoperation was 57%. Survival was significantly influenced by a delay in treatment of greater than 24 hours. With the exception of nonoperative therapy, survival was improved for all forms of treatment instituted within 24 hours. Primary closure within 24 hours resulted in the most favorable outcome (92% survival). In addition to early treatment, other factors associated with a favorable outcome included traumatic perforation (100% survival), foreign-body perforations (94% survival), and iatrogenic causes (80% survival). Spontaneous rupture resulted in the lowest survival (37%). The incidence of esophageal perforation has increased dramatically since 1967.(ABSTRACT TRUNCATED AT 250 WORDS)