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

The protective effect of misoprostol against doxorubicin induced liver injury

We investigated the potential hepatoprotective effects of misoprostol (MP) on doxorubicin (DOX) induced liver injury in rats using histology and biochemistry. We used 21 male Sprague-Dawley rats divided randomly into three groups: group 1, control; group 2, DOX; group 3, DOX + MP. The control group was injected intraperitoneally (i.p.) with 0.5 ml 0.9% w/v NaCl and given 1 ml 0.9% NaCl orally for 6 days. DOX was administered i.p. as a single dose of 20 mg/kg. MP, 0.2 mg/kg, was given orally for 6 days. Treatment with MP increased high density lipoprotein cholesterol levels and decreased serum alanine aminotransferase, aspartate aminotransferase, low density lipoprotein cholesterol, triglycerides and total cholesterol levels significantly in serum. Increased malondialdehyde level and decreased catalase, glutathione and superoxide dismutase levels caused by DOX were suppressed significantly in liver tissue by MP. DOX + MP reduced loss of body weight. Oxidative stress was decreased, antioxidant activity was increased and histopathological changes were reduced in the DOX + MP group compared to the DOX group. Liver injury caused by DOX was attenuated by MP treatment owing to the antioxidative and anti-apoptotic effects of MP, which might be useful for reducing the severity of DOX induced liver injury.

Anti-apoptotic and antioxidant effect of leptin on CCl₄-induced acute liver injury in rats

The aim of this study is to investigate the effect of leptin in rats on carbon tetrachloride (CCl(4)) induced acute liver damage using immunohistochemical methods for apoptosis and biochemical parameters. In this experimental study, 18 Spraque-Dawley rats were divided into three groups viz; control, CCl(4) and CCl(4)+leptin treatment. 0.8 ml/kg olive oil was administered intraperitoneally (i.p.) to the control group and 0.8 ml/kg CCl(4) (1:1 dissolved in olive oil) was administered i.p. to the CCl(4) and CCl(4)+leptin treatment groups, respectively. After 6 h of administrating CCl(4), CCl(4)+leptin treatment group was given i.p. leptin (10 μg/kg). Twenty-four hours after administrating CCl(4) all of the groups were euthanized. Biochemical assessments were performed using serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), plasma tumor necrosis factor alpha (TNF-α) levels and tissue malondialdehyde (MDA), and TNF-α levels. Histological assessments were then performed using Hematoxylin&Eosin (H&E) staining in light microscope and apoptosis assessment using Terminal Transferase dUTP Nick End Labeling (TUNEL)-staining. Serum AST, ALT, ALP and plasma TNF-α levels, tissue MDA and TNF-α levels had all increased in CCl(4) group, but were found to be significantly decreased in CCl(4)+leptin treatment group. Moreover, TUNEL-positive cell counts in liver had significantly increased in CCl(4) group, but decreased in CCl(4)+leptin treatment group (P < 0.05). The results of our study the biochemical, histological and TUNEL-staining showed that leptin has treatment effects on liver CCl(4) induced injury. It plays a role as a potent free radical scavenger, a powerful antioxidant and it also has anti-apoptotic effects.

Intracellular calcium signaling pathways during liver ischemia and reperfusion

Calcium plays a major role in intracellular signaling mechanisms during ischemia reperfusion (I/R) injury of a liver cell. Under ischemic conditions, the absence of oxygen arrests oxidative phosphorylation, thereby eliminating the energy source by which hepatocellular mechanisms maintain homeostasis of calcium. This, in turn, leaves nonselective plasma membrane influx pores unopposed and results in a net increase in intracellular calcium concentrations. Subsequent reperfusion marks the onset and progression of apoptosis and necrosis, as it involves inflammatory responses as well as free-radical formation due to re-oxygenation of cells. These processes destroy the structural integrity of organelles, leading to disruptive redistribution of calcium between cellular and subcellular compartments. This initial elevation and later imbalance of intracellular calcium concentrations associated with I/R induce various molecular responses within each organelle. In the cytoplasm, a series of pro-apoptotic pathways involving various calcium sensitive enzymes are activated. The injury is further exacerbated in the endoplasmic reticulum (ER) due to the malfunction of mechanisms responsible for intracellular calcium sequestration. Both the mitochondria and the nucleus are also adversely affected, as their structural integrity and physiologic functions are disrupted. To date, however, the precise pathophysiology of these calcium-mediated signaling pathways is not fully understood due to its complex nature. This review aims to systematically examine the current literature about individual molecular signaling pathways in the cytoplasm, ER, mitochondria, and the nucleus prior to causing time-sensitive progression of permanent tissue injury.

Effects of Dantrolene on Ischemia-Reperfusion Injury in Animal Models: A Review of Outcomes in Heart, Brain, Liver, and Kidney

Background/Objectives

Ischemia-reperfusion (IR) is the restoration of blood flow to a tissue that was formerly deficient of blood flow. Tissue damage after IR is considered an IR injury (IRI). During IR, there is an increased level of cytosolic calcium ([Ca2+]i) due to the release of calcium from mitochondrial, sarcoendoplasmic reticulum, and nuclear organelles. Dantrolene sodium (dantrolene) is a 1-[[[5-(4-nitrophenol)-2-furanyl]methylene]amino]-2, 4-imidazolidinedione sodium salt with a nonspecific mechanism, inhibiting organelle release of Ca2+ into the cytosol. This work reviews the outcomes of administering dantrolene in brain, heart, liver, and kidney animal models of IRI.

Methods

An extensive PubMed, MEDLINE, and MEDLAR literature review during the last 30 years on the effect of dantrolene in IRI in animal models was analyzed to determine the clinical implications of this important study. Particular attention was given to dantrolene in heart, brain, liver, and kidney IRI.

Results

Heart: Nine studies of heart IRI were reviewed and include an in vivo dog model (n = 1), in vivo rabbit model (n = 1), isolated dog myocardial fibers (n = 1), and isolated rat hearts (n = 6). Four studies showed decreased infarct size and increased cardiac function after IRI. One in vivo rabbit study found no difference in infarct size or cardiac function after IRI versus controls. Dantrolene may be protective or inductive of post-IRI arrhythmias depending on preestablished myocyte cycling times. Brain: Nine studies of brain IRI were reviewed and include an in vivo dog model (n = 1), in vivo gerbil model (n = 2), and in vivo rat models (n = 6). Dantrolene shows protective decreases in apoptotic markers in 6 studies, but it shows no effect on the necrotic core and mixed effects on reduction of infarct volume. One study found increased mortality in the dantrolene group. Liver: One study of in vivo rat liver IRI found that dantrolene decreased liver function tests, tissue necrosis factor α, tissue necrosis, and increased interleukin 10. Kidney: One study of in vivo rat kidney IRI showed that dantrolene had no effect.

Conclusions

Dantrolene shows protective effects in animal models of heart, brain, and potentially liver IRI, reinforcing the importance of calcium homeostasis during IRI. Variations of dose, timing of administration, route of administration, and outcomes between studies make definitive conclusions difficult. The nonspecific mechanism of action of dantrolene may also account for the variation among studies. Lack of studies in the liver and kidney makes any consensus in these organs premature, and thus, emphasis for this review was put on studies of the heart and brain.

Hepatoprotective effects of misoprostol and silymarin on carbon tetrachloride-induced hepatic damage in rats

The aim of this study was to investigate the effect of misoprostol, silymarin or the co-administration of misoprostol + silymarin on the carbon tetrachloride (CCl(4))-induced hepatic injury in rats. Misoprostol (10, 100, 1000 microg/kg), silymarin (25 mg/kg) or misoprostol (100 microg/kg) + silymarin (25 mg/kg) was given once daily orally simultaneously with CCl(4) and for 15 days thereafter. The results showed that misoprostol (10, 100 or 1000 microg/kg) conferred significant protection against the hepatotoxic actions of CCl(4) in rats, reducing serum alanine aminotransferase (ALT) levels by 24.7%, 42.6% and 49.4%, respectively compared with controls. Misoprostol, given at 100 or 1000 microg/kg, decreased aspartate aminotransferase (AST) by 28 and 43.6% and alkaline phosphatase (ALP) by 19.3% and 53.4% respectively. Meanwhile, silymarin reduced ALT, AST and ALP levels by 62.7%, 66.1% and 65.1% respectively. The co-administration of misoprostol (100 microg/kg) and silymarin (25 mg/kg) resulted in 61.4%, 66.1% and 57.5% reduction in ALT, AST and ALP levels respectively. Histopathological alterations and depletion of hepatocyte glycogen and DNA content by CCl(4) were markedly reduced after treatment with misoprostol, silymarin or misoprostol + silymarin. Image analysis of liver specimens revealed a marked reduction in liver necrosis; area of damage: 32.4%, 24% and 10.2% after misoprostol (10, 100 or 1000 microg/kg), 7.2% after silymarin and 10.9% after treatment with misoprostol 100 microg/kg + silymarin, compared with CCl(4) control group (46.7%). These results indicate that treatment with misoprostol protects against hepatocellular necrosis induced by CCl(4). This study suggests a potential therapeutic use for misoprostol in liver injury.

Misoprostol therapeutics revisited

Misoprostol, a prostaglandin E1 analog, is a racemate of four stereoisomers. On administration it rapidly de-esterifies to its active form, misoprostolic acid. Misoprostolic acid is 85% albumin bound and has a half-life of approximately 30 minutes. It is excreted in urine as inactive metabolites. No significant drug interactions have been reported. Besides its gastrointestinal protective and uterotonic activities, misoprostol regulates various immunologic cascades. It inhibits platelet-activating factor and leukocyte adherence, and modulates adhesion molecule expression. It protects against gut irradiation injury, experimental gastric cancer, enteropathy, and constipation. It improves nutrient absorption in cystic fibrosis. Misoprostol has utility in acetaminophen and ethanol hepatotoxicity, hepatitis, and fibrosis. It is effective in asthmatics and aspirin-sensitive asthmatic and allergic patients. It lowers cholesterol and severity of peripheral vascular diseases, prolongs survival of cardiac and kidney transplantation, synergizes cyclosporine, and protects against cyclosporine-induced renal damage. It works against drug-induced renal damage, interstitial cystitis, lupus nephritis, and hepatorenal syndrome. It is useful in periodontal disease and dental repair. Misoprostol enhances glycosoaminoglycan synthesis in cartilage after injury. It prevents ultraviolet-induced cataracts and reduces intraocular pressure in glaucoma and ocular hypertension. It synergizes antiinflammatory and analgesic effects of diclofenac or colchicine and has been administered to treat trigeminal neuralgic pain. It reduces chemotherapy-induced hair loss and recovery time from burn injury, and is effective in treating sepsis, multiple sclerosis, and pancreatitis.

Significance of early aminotransferase elevation after liver transplantation

BACKGROUND

We retrospectively reviewed 213 consecutive patients who received their first liver allograft between January 1 and December 31, 1993, in order to study the impact of ischemia/preservation/reperfusion injury (IPRI) on patient and graft outcome.

METHODS

The extent of IPRI was assessed by the peak value of aspartate aminotransferase (ASTmax) observed within the first 72 hr after transplant. For the purpose of univariate analysis, categorical classification of recipients was done based upon ASTmax as follows: group 1, ASTmax<600 U/L (n=46); group 2, ASTmax=600-2000 U/L (n=97); group 3, ASTmax>2000-5000 U/L (n=50), and group 4, ASTmax>5000 U/L (n=17). For multivariate analysis, stepwise Cox regression was performed with age, ASTmax, and United Network for Organ Sharing (UNOS) status as covariates.

RESULTS

Groups were comparable with respect to age, UNOS status at the time of transplantation, and diagnostic case mix. Median follow-up was 644 days. The overall incidence of primary graft nonfunction (PNF) was 7.6%. PNF incidence was significantly correlated with the severity of IPRI (0%, 4%, 10%, and 41% for groups 1 to 4, respectively, P < 0.0001), but this impact was confined to the respective rates of retransplantation as early patient survival was unaffected. The 1-year survival of patients whose initial grafts manifested extreme IPRI (group 4) was significantly inferior to recipients in the three other groups (77%, 71%, 73%, and 52% for groups 1 to 4, respectively, P=0.03). This increased mortality was confined to patients who never achieved discharge from their initial hospitalization, with no significant differences between groups being detected in the survival of those patients who were discharged (84%, 80%, 85%, and 81% for groups 1 to 4, respectively, P=NS). Although overall 1-year graft survival was strongly correlated with the extent of IPRI (77%, 67%, 62%, and 41% for groups 1 to 4, respectively, P=0.001), this correlation was abolished when survival of grafts not lost to PNF was examined at 1 and 2 years. Stepwise Cox regression analysis confirmed the independent association between ASTmax and patient and graft survival. The long-term quality of allograft function as well as the incidence of chronic rejection and biliary complications were unrelated to the extent of IPRI.

CONCLUSIONS

We conclude that: (1) patient survival is influenced by IPRI only when it is extreme (ASTmax>5000 U/L), provided parameters of graft function are used in conjunction with aminotransferase values to assess the need for prompt retransplantation; (2) short-term graft survival is proportional to the extent of IPRI, but grafts that are not lost to PNF have equivalent 1- and 2-year survival irrespective of the magnitude of IPRI; (3) 40% of grafts with extreme IPRI are lost to PNF, but the same proportion also provide long-term function; and (4) for surviving grafts, long-term biochemical function as well as the incidence of biliary complications and of chronic rejection are unrelated to the extent of IPRI.

Ischaemic preconditioning of the liver: a preliminary study

BACKGROUND

A phenomenon of 'preconditioning' exists for the heart, but has not been described for the liver. This study was undertaken to determine whether a brief episode of ischaemia (3 or 5 min) followed by a short reperfusion time (5 or 10 min) would precondition the liver to reduce subsequent injury from prolonged ischaemia (30 to 90 min).

METHODS

Male Wistar rats were allocated into five control (no preconditioning) and five preconditioned groups, each having a liver resection. The preconditioning times were 3 min ischaemia followed by 5 min reperfusion with a prolonged ischaemia of 60 or 90 min for the first two groups, and 5 min ischaemia followed by 10 min reperfusion with prolonged ischaemia times of 30 or 45 min for the other three groups.

RESULTS

Of rats resected with 3-5-60 min time sequence designed to assess survival, 9/10 died. However 9/10 died also in the matching control group with 60 min ischaemia. With a 5-10-45 min sequence, 9/10 survived more than 24 h in the preconditioned group and 1/10 in the non-preconditioned controls. With a 5-10-30+ sequence designed to measure liver function tests, the prothrombin time was significantly improved; bilirubin, serum alkaline phosphatase and the alanine aminotransferase improved but these did not reach significance.

CONCLUSION

A brief episode of ischaemia followed by an episode of reperfusion before a prolonged period of ischaemia ameliorated the effects of ischaemia-reperfusion injury in a rat liver resection model. If hepatic preconditioning is confirmed in humans, ischaemic preconditioning will have an important role for all liver surgery.