Paeoniflorin attenuates ANIT-induced cholestasis by inhibiting apoptosis in vivo via mitochondria-dependent pathway.

Apoptosis induced by the bile acids in the liver is considered to play a pivotal role in the pathogenesis of cholestatic disease. Increasing evidence has demonstrated that Paeoniflorin (PF) exerts therapeutic effect on severe cholestatic liver diseases. However, whether PF could protect against alpha-naphthylisothiocyanate (ANIT)-induced cholestasis by inhibiting apoptosis remains unclear. In this study, we mainly investigated the effect and anti-apoptosis mechanism of PF on cholestasis. Experimental results indicated that PF pretreatment could attenuate liver damage and cholestasis by ANIT in rats, lift the biliary excretion in addition to decrease serum indices (ALT, AST, DBIL, TBIL, TBA, ALP and ϒ-GT) and conspicuous neutrophil infiltration and cell apoptosis in liver evidenced by TUNEL staining. Furthermore, the pro-apoptosis genes expression of Bax, Caspase-9 and Caspase-3 increased by ANIT were prominently reduced after PF treatment. The increase of anti-apoptosis gene and main regulator Bcl-2 in mitochondria by ANIT was largely reversed by PF pre-treatment. In summary, our study demonstrated that PF pre-treatment not only significantly attenuated ANIT-induced cholestasis and liver injury, but also largely reduced cell apoptosis in liver, thus may act as a potential therapeutic agent for cholestasis disease.

[6,8-Dimethyl-2-piperidinomethyl-2,3-dihydrothiazolo[2,3-f]xanthine: a new inductor of the monooxygenase system inhibits experimental intrahepatic cholestasis in rats]. / Novyi induktor monooksigenaznoi sistemy 6,8-dimetil-2-piperdinometil-2,3-digidrotiazolo[2,3-f]ksantin kak korrektor vnutripechenochnogo kholestaza v ékperimente.

6,8-Dimethyl-2-piperidinomethyl-2,3-dihydrothiazolo[2,3-f]xanthine, a new inductor of the monooxygenase system, inhibited the development of experimental intrahepatic cholestasis induced by alpha-naphthylisothiocyanate in rats. The drug stimulated the detoxicating function of liver, increased the survivability of rats, restored the level of microsomal protein and cytochrome P-450, decreased the cell-average erythrocyte fragility, and reduced the activity of cholestasis markers and the amount of TBA-active products in hepatocytes.

Vitamin A or zymosan pretreatment attenuates alpha-naphthylisothiocyanate-induced liver injury.

alpha-Naphthylisothiocyanate (ANIT) is a cholangiolitic hepatotoxicant that causes periportal hepatic injury in the rat that is neutrophil- and platelet-dependent. Since macrophages have recently been implicated as participants in some chemically induced hepatotoxicities, we evaluated the role of these cells in ANIT-induced hepatic injury. Rats were treated with gadolinium chloride (GdCl3), an agent which decreases hepatic macrophage numbers and activity, zymosan, an agent which increases hepatic macrophage numbers, or vitamin A, which increases hepatic macrophage activity. GdCl3 did not ameliorate ANIT-induced hepatotoxicity, as demonstrated by a lack of attenuation of any of the markers of hepatic insult evaluated. In contrast, pretreatment with either zymosan or vitamin A decreased ANIT hepatotoxicity. Zymosan administration reduced blood neutrophil numbers and influx of neutrophils into the peritoneum after intraperitoneal glycogen administration but did not affect hepatic neutrophil accumulation in ANIT-treated rats. To determine if macrophages were important in the protection by vitamin A, rats were cotreated with GdCl3 and vitamin A. GdCl3 did not alter the protection from ANIT hepatotoxicity afforded by vitamin A. Vitamin A treatment decreased ANIT and glutathione concentrations in bile at 1 and 4 hr after ANIT administration but had a minimal effect on plasma ANIT concentration. In summary, pretreatment of rats with zymosan or vitamin A but not GdCl3 attenuated ANIT-induced liver injury. The protection afforded by zymosan may derive from its effects on neutrophils or platelets. The protection by vitamin A appears to result from its effect on the transport of ANIT into bile. The results suggest that hepatic macrophages are not required for the manifestation of ANIT hepatotoxicity.

The inhibitory effect of SA3443, a novel cyclic disulfide compound, on alpha-naphthyl isothiocyanate-induced intrahepatic cholestasis in rats.

1. We investigated the effect of SA3443, a novel cyclic disulfide compound, on alpha-naphthyl isothiocyanate (ANIT)-induced intrahepatic cholestasis in rats. 2. SA3443 given orally at doses of 100 or 300 mg/kg, three times at 4h intervals, dose-dependently suppressed the elevation of serum total bilirubin, alkaline phosphatase activity and transaminase activities induced by administration of ANIT (80 mg/kg) 3h before the second dosages of SA3443. 3. SA3443 also significantly inhibited the reduction of bile flow in the ANIT-treated rats. 4. These findings indicated that SA3443 had a markedly inhibitory effect on ANIT-induced intrahepatic cholestasis in rats.

Protection against alpha-naphthylisothiocyanate-induced liver injury by decreased hepatic non-protein sulfhydryl content.

alpha-Naphthylisothiocyanate (ANIT) injures bile duct epithelium and hepatic parenchymal cells in rats. It is commonly believed that ANIT must undergo bioactivation by hepatic, cytochrome P450-dependent mixed-function oxidases (MFO), since agents which are inducers or inhibitors of hepatic MFO activity enhance or attenuate, respectively, the liver injury associated with ANIT. Several of these agents also affect hepatic glutathione (GSH) content and/or GSH S-transferase activity in a manner to suggest a causal role for GSH in ANIT-induced hepatotoxicity. To determine whether GSH might be involved in the mechanism of injury, buthionine sulfoximine (BSO), diethyl maleate (DEM), or phorone was used to reduce hepatic non-protein sulfhydryl (NPSH) content, an indicator of GSH content. Twenty-four hours after ANIT treatment, rats exhibited cholestasis and elevations in serum of total bilirubin concentration, total bile acid concentration, aspartate aminotransferase (AST) activity, and gamma-glutamyltransferase activity. Cotreatment of rats with BSO decreased NPSH content by 70% at 24 hr and prevented the cholestasis and elevations in serum markers of liver injury caused by ANIT. Likewise, cotreatment of rats with DEM afforded protection against markers of liver injury. Phorone treatment attenuated ANIT-induced elevations in serum total bilirubin concentration and AST activity. Although BSO treatment afforded protection against ANIT-induced liver injury at 24 hr, the injury was evident at 48 hr, and it appeared to coincide with a return of hepatic NPSH content. These results suggest that GSH plays a causal or permissive role in the liver injury caused by ANIT.

Effect of inhibitors of alpha-naphthylisothiocyanate-induced hepatotoxicity on the in vitro metabolism of alpha-naphthylisothiocyanate.

The role of S-oxidation in the toxic bioactivation of alpha-naphthylisothiocyanate (ANIT) was investigated. The effects of several thione compounds, inhibitors and an inducer of the cytochrome P-450-dependent mixed function oxidase systems on the in vitro metabolism of ANIT and aminopyrine were determined. Ethionamide, sodium diethyldithiocarbamate (Na-DDTC) and S-methyl diethyldithiocarbamate (Me-DDTC), three agents known to undergo metabolism by an S-oxidative pathway and diminish ANIT's toxicity, inhibited the in vitro enzymatic metabolism of ANIT by rat liver microsomes. Methimazole failed to alter either the hyperbilirubinemic response of ANIT or the in vitro metabolism of ANIT. All four thione compounds (i.e., ethionamide, Me-DDTC, Na-DDTC and methimazole) inhibited the enzymatic metabolism of aminopyrine by rat liver microsomes. Me-DDTC was the most potent, whereas methimazole was the least potent inhibitor of aminopyrine metabolism. Phenobarbital, which potentiates, and SKF-525A, which inhibits the hepatotoxicity of ANIT in vivo, correspondingly stimulated or inhibited the NADPH-dependent metabolism of ANIT and aminopyrine by liver microsomes. N-Decylimidazole (NDI), another classical inhibitor of cytochrome P-450-dependent monooxygenase system, inhibited both the in vivo toxicity and in vitro metabolism of ANIT. NDI also diminished the enzymatic metabolism of aminopyrine by liver microsomes. Thus the results of this study indicate that metabolism of ANIT is intimately related to its toxicity and that ANIT probably undergoes its toxic bioactivation via a cytochrome P-450-dependent S-oxidative pathway.