Resolution of danazol-induced cholestasis with S-adenosylmethionine

Opposite action of S-adenosyl methionine and its metabolites on CYP2E1-mediated toxicity in pyrazole-induced rat hepatocytes and HepG2 E47 cells

S-adenosyl-L-methionine (SAMe) is protective against a variety of hepatotoxins, including ethanol. The ability of SAMe to protect against cytochrome P-450 2E1 (CYP2E1)-dependent toxicity was studied in hepatocytes from pyrazole-treated rats and HepG2 E47 cells, both of which actively express CYP2E1. Toxicity was initiated by the addition of arachidonic acid (AA) or by depletion of glutathione after treatment with L-buthionine sulfoximine (BSO). In pyrazole hepatocytes, SAMe (0.25-1 mM) protected against AA but not BSO toxicity. SAMe elevated GSH levels, thus preventing the decline in GSH caused by AA, and SAMe prevented AA-induced lipid peroxidation. SAMe analogs such as methionine or S-adenosyl homocysteine, which elevate GSH, also protected against AA toxicity. 5'-Methylthioadenosine (MTA), which cannot produce GSH, did not protect. The toxicity of BSO was not prevented by SAMe and the analogs because GSH cannot be synthesized. In contrast, in E47 cells, SAMe and MTA but not methionine or S-adenosyl homocysteine potentiated AA and BSO toxicity. Antioxidants such as trolox or N-acetyl cysteine prevented this synergistic toxicity of SAMe plus AA or SAMe plus BSO, respectively. In pyrazole hepatocytes, SAMe prevented the decline in mitochondrial membrane potential produced by AA, whereas in E47 cells, SAMe potentiated the decline in mitochondrial membrane potential. In E47 cells, but not pyrazole hepatocytes, the combination of SAMe plus BSO lowered levels of the antioxidant transcription factor Nrf2. Because SAMe can be metabolized enzymatically or spontaneously to MTA, MTA may play a role in the potentiation of AA and BSO toxicity by SAMe, but the exact mechanisms require further investigation. In conclusion, contrasting effects of SAMe on CYP2E1 toxicity were observed in pyrazole hepatocytes and E47 cells. In hepatocytes, SAMe protects against CYP2E1 toxicity by a mechanism involving maintaining or elevating GSH levels.

S-Adenosyl-l-methionine Attenuates Hepatotoxicity Induced by Agonistic Jo2 Fas Antibody following CYP2E1 Induction in Mice

S-Adenosyl-l-methionine (SAM) has been shown to be hepatoprotective against many toxic agents. Its possible effectiveness in protecting against CYP2E1-dependent toxicity is not known. We recently reported that treatment of mice with pyrazole to induce CYP2E1 increased hepatotoxicity produced by Fas agonistic Jo2 antibody. The current study was designed to investigate the effect of exogenous administration of SAM on the synergistic hepatotoxicity produced by Fas agonistic Jo2 antibody plus CYP2E1 following pyrazole pretreatment in C57BL/6 mice. Suboptimal administration of Jo2 Fas antibody combined with pyrazole pretreatment caused severe hepatotoxicity as determined by elevations in serum transaminase levels and histopathology. Exogenous administration of SAM (50 mg i.p./kg body weight every 12 h for 3 days) significantly decreased serum transaminases and ameliorated morphological changes of the liver. Addition of SAM elevated hepatic SAM and total reduced glutathione levels and inhibited CYP2E1 activity. SAM also lowered the elevated oxidative stress (lipid peroxidation, protein carbonyls, and superoxide production) and nitrosative stress (induction of inducible nitric-oxide synthase and 3-nitrotyrosine adducts) and increases in caspase-8 and -3 activation produced by the pyrazole plus Jo2 treatment. SAM did not prevent the increase in serum TNF-alpha levels or the decrease in catalase activity in this model. These results indicate that SAM can have an important hepatoprotective role as an effective reagent against Fas plus CYP2E1-induced hepatotoxicity by lowering oxidative and nitrosative stress.

The anabolic androgenic steroid oxandrolone in the treatment of wasting and catabolic disorders: review of efficacy and safety

There has been increasing interest in the development of effective agents that can be safely used to promote anabolism in the clinical setting for patients with chronic wasting conditions as well as in the prevention and treatment of frailty associated with loss of muscle tissue in aging (sarcopenia). One such agent is the anabolic androgenic steroid (AAS) oxandrolone, which has been used in such clinical situations as HIV-related muscle wasting, severe burn injury, trauma following major surgery, neuromuscular disorders and alcoholic hepatitis for over 30 years. In the US, oxandrolone is the only AAS that is US FDA-approved for restitution of weight loss after severe trauma, major surgery or infections, malnutrition due to alcoholic cirrhosis, and Duchenne's or Becker's muscular dystrophy. Our review of the use of oxandrolone in the treatment of catabolic disorders, HIV and AIDS-related wasting, neuromuscular and other disorders provides strong evidence of its clinical efficacy. Improvements in body composition, muscle strength and function, status of underlying disease or recovery from acute catabolic injury and nutritional status are significant in the vast majority of well designed trials. However, oxandrolone has not yet been studied in sarcopenia.Unlike other orally administered C17alpha-alkylated AASs, the novel chemical configuration of oxandrolone confers a resistance to liver metabolism as well as marked anabolic activity. In addition, oxandrolone appears not to exhibit the serious hepatotoxic effects (jaundice, cholestatic hepatitis, peliosis hepatis, hyperplasias and neoplasms) attributed to the C17alpha-alkylated AASs. Oxandrolone is reported to be generally well tolerated and the most commonly documented adverse effects are transient elevations in transaminase levels and reductions in high density lipoprotein cholesterol level.However, optimal risk:benefit ratios for oxandrolone and other agents in its class will need to be refined before widespread clinical acceptance of AASs as a therapeutic option in sarcopenia and other chronic wasting conditions.

Drug-induced cholestasis

Drugs may cause several overlapping syndromes of cholestasis, the pathophysiological syndrome resulting from impaired bile flow. These reactions comprise approximately 17% of all hepatic adverse drug reactions (ADRs) and they may be severe. Causes of 'pure' (bland) cholestasis include oestrogens and anabolic steroids; rarer associations are with antimicrobials and NSAIDs. 'Cholestatic hepatitis' is a common drug reaction in which liver injury and inflammation cause significant elevation of serum alanine aminotransferase (ALT) as well as cholestasis. Chlorpromazine and ketoconazole are classic examples, but it is now exemplified by amoxycillin-clavulanate and other oxy-penicillins. Chronic cholestasis results from small bile duct injury leading to the vanishing bile duct syndrome (VBDS), a disorder mimicking primary biliary cirrhosis, or from injury to larger bile ducts causing secondary sclerosing cholangitis. Whilst there is increasing evidence of a genetic predisposition to cholestatic drug reactions, there are currently no pretreatment tests to predict drug safety. Prevention of severe reactions therefore relies on early detection of liver injury and prompt drug withdrawal. Symptomatic management includes relief of pruritus and correction of fat-soluble vitamin deficiency. In small cohort studies, ursodeoxycholic acid (UDCA) arrested progressive cholestasis in two-thirds of cases, but evidence for use of corticosteroids is anecdotal. This review considers diagnosis, pathogenesis, prevention and management of drug-induced cholestasis, with particular reference to frequently- and newly-described causes.

S-adenosylmethionine protects post-ischemic mitochondrial injury in rat liver

BACKGROUND/AIMS

S-adenosylmethionine (SAM) is a thiol-containing compound with known therapeutic affects on cholestasis and hepatotoxicity. The aim of this study was to investigate the effect of SAM on the prevention of mitochondrial injury induced by hepatic ischemia and reperfusion.

METHODS/RESULTS

Rats were subjected to 60 min of hepatic ischemia and 1 and 5 h of reperfusion. 2 h prior to ischemia, the animals received either vehicle or SAM intraperitoneally. In the vehicle-treated ischemic animals, serum aspartate aminotransferase levels increased at 1 h and again at 5 h of reperfusion and were reduced by SAM pre-treatment. Similarly, mitochondrial lipid peroxidation was elevated in the vehicle-treated group, but this elevation was attenuated by SAM. In contrast, mitochondrial glutamate dehydrogenase activity and reduced glutathione concentration both decreased in the vehicle-treated group, and this decrease was also inhibited by SAM. Hepatic ATP levels in the vehicle-treated rats were found to be 42% lower 5 h after reperfusion, however, treatment with SAM elevated these ATP levels. SAM treatment increased the concentration of adenosine but inhibited the accumulation of hypoxanthine in the ischemic liver.

CONCLUSION

SAM protects against mitochondrial injury, which prevents mitochondrial oxidant stress and improves ischemia-induced hepatic energy metabolism.

Evidence that S-adenosyl-L-methionine diastereoisomers may reduce ischaemia-reperfusion injury by interacting with purinoceptors in isolated rat liver

1. Mechanisms underlying the haemodynamic activity of diastereoisomers of S-adenosyl-L-methionine (SAM) were investigated using inhibitors of purinoceptors and nitric oxide (NO) synthase in perfused rat livers damaged by sequential 24 h cold and 20 min rewarming ischaemia + reperfusion. 2. Stored livers were flushed with 10 ml saline alone (control) or with added (R,S) or (S,S) SAM (100 microM) and reperfused in the absence (control) or presence of 10 microM 8-phenyltheophylline (8-PT) or 100 microM L-N-monomethylarginine (L-NMMA). 3. Both SAM diastereoisomers rapidly increased blood flow and bile production versus controls (P<0.001) but the (R,S) isomer induced greater increases in blood flow and the (S,S) isomer greater increases in bile production: 625 versus 596 versus 518 ml blood flow and 100 versus 119 versus 56 mg bile production per g liver over 3 h in (R,S), (S,S) and control, respectively. 4. 8-PT prevented the enhancement of blood flow by (S,S) SAM (529 versus 596 ml g(-1) liver over 3 h for (S,S) SAM alone, P<0.001), but was without effect in control livers. 8-PT also reduced SAM-enhanced bile production: 51 versus 119 mg g(-1) liver over 3 h, P<0.001. L-NMMA reduced blood flow and bile production similarly in the absence or presence of (S,S) SAM. 5. Thus, SAM may improve liver perfusion after ischaemia-reperfusion injury via stimulation of P, (A2) purinoceptors at which SAM shows activity. The choleretic activity of (S,S) SAM is disproportionately greater than enhanced blood flow and may occur independently of a NO-dependent component of bile production.

Ultrastructural features of danazol-induced cholestasis: a case study

A case study of a severe cholestatic syndrome induced by danazol, with ultrastructural description of liver morphology, is reported. Cholestasis appeared after 3 months treatment with danazol (300 mg/daily) and completely resolved 2 months after withdrawal. In spite of the severe increase in serum bilirubin and total serum bile salts, transaminases were only slightly elevated and GGT and alkaline phosphatases were almost normal. Light microscopy shows a pattern of predominantly centrolobular cholestasis without necrosis, with minimal inflammatory infiltrate and with no sign of bile ductule involvement. At the ultrastructural level very dilated bile canaliculus predominate with stunted or loss of microvilli and dense bile material in the lumen. Nonspecific alterations were seen in hepatocyte intracellular organelles. It is suggested that danazol may cause a rare but severe hepatocanalicular cholestasis, differing from the "bland" cholestasis frequently described during therapy with other anabolic steroids.