Effect of gomisin A (TJN-101) on the arachidonic acid cascade in macrophages

It has been reported that leukotrienes (LTs) may play a role in inflammatory liver diseases, and several inhibitors of LTs show an inhibitory effect on experimental liver injuries. In this study, the effect of Gomisin A (TJN-101), which is a lignan component of schisandra fruits, on the arachidonic acid cascade in macrophages was examined to explain the mechanisms of the inhibitory effect of TJN-101 on liver injuries. The production of leukotriene B4 was suppressed by treatment with TJN-101, while the activity of 5-lipoxygenase was not affected. The release of arachidonic acid from macrophages stimulated with fMet-Leu-Phe or the Ca++ ionophore A23187 was suppressed by treatment with TJN-101. The activity of phospholipase A2 was not affected by treatment with TJN-101. These results suggested that TJN-101 produces an inhibitory effect on the biosynthesis of LTs by preventing the release of arachidonic acid, and it was thought that the preventive effect on the arachidonic acid cascade may be partially associated with the inhibitory effect of TJN-101 on liver injuries.     

Effect of gomisin A (TJN-101), a lignan compound isolated from Schisandra fruits, on liver function in rats

TJN-101 [+)-(6S, 7S, R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy- 6,7-dimethyl-10,11-methylenedioxy-6-dibenzo [a, c] cyclooctenol) is one of the lignan compounds isolated from Schisandra fruits. When TJN-101 was administered orally at the doses of 3-100 mg/kg/day for 4 days, bile secretion, hepatic excretion of dye or hepatic hemodynamics 24 hr after the last dose was investigated in comparison with the phenobarbital (100 mg/kg/day)-treated group. Bile flow was dose-dependently increased; in contrast, biliary concentration of bile acids was decreased in TJN-101 (30 and 100 mg/kg/day)-treated groups. Similar changes were also observed in the phenobarbital-treated group. These results suggested that the enhancement of bile secretion caused by TJN-101 or phenobarbital was due to an increase of a bile acid-independent fraction. In the bromosulfophthalein (BSP) clearance test for liver function, both TJN-101 (30 and 100 mg/kg/day) and phenobarbital accelerated the disappearance from the blood and biliary excretion of BSP. Hepatic hemodynamics was examined by the hydrogen clearance method and measurement of liver wet and dry weight. Liver blood flow tended to increase in the TJN-101 (10-100 mg/kg/day) or phenobarbital-treated group. On the other hand, TJN-101 (3-100 mg/kg/day) or phenobarbital hardly altered the water content of the liver. These results suggested that the liver enlargement caused by both compounds was not accompanied with hepatic edema and that the enhancement of bile secretion or hepatic excretion of BSP might be related to an increase of liver blood flow.     

Studies on the metabolic fate of gomisin A (TJN-101). I. Absorption in rats]

Gomisin A (TJN-101) is one of the lignan components isolated from Schisandra Fruits and expected to have some efficacies in clinical treatment of hepatitis. The serum concentrations of TJN-101 and Met. B, which was identified as a demethylenated substance and one of the major metabolites of TJN-101 in rats, were investigated. After intravenous administration at doses of 1.6, 4.0 and 10 mg/kg of body weight, the serum concentration of TJN-101 decreased biphasically, and the terminal elimination half-life at each dose was about 70 min. Dose-dependency was observed for the area under the concentration-time curve (AUC). On the other hand, the serum concentration of TJN-101 increased rapidly and reached maximum within 15 to 30 min when administered orally. This result was supported by the in situ roop method. The Cmax and the AUC values were not exactly dose-dependent, but the values increased with a dose-up of TJN-101. The biotransformation of TJN-101 to Met. B, was very rapid in both intravenous and oral administrations. The AUC value of Met. B after oral administration of TJN-101 at a dose of 1.6 mg/kg was relatively larger than any other dosages. It suggested that TJN-101 was extensively underwent the first pass effect in rats. More than 80% of TJN-101 was bound with rat serum protein in vitro and in vivo. Therefore, it seems to be necessary to pay attention when it was administered concurrently with high protein binding drugs.     

Determination of gomisin A (TJN-101) and its metabolite in rat serum by gas chromatography-mass spectrometry]

Gomisin A (TJN-101) is one of the lignan components isolated from Schisandra Fruits. A high sensitive and precise method for the determination of TJN-101 and its major metabolite (Met. B) in the rat serum was developed by selected ion monitoring (SIM) with gas chromatography-mass spectrometry (GC/MS) using a fused silica capillary column (SPB-1, Supelco). A 100 microliter serum sample was used for the solid phase extraction. The calibration curves of TJN-101 and Met.B both showed a good linearity between 2.0 and 2000.0 ng/ml. The analytical precision (intra-assay, C.V. less than 4.7%), recoveries (98.4 +/- 10.1%), and detection limit (2 ng/ml) of TJN-101 indicated that this system was suited for the determination of TJN-101 in biological fluid. In case of Met.B, the same results as TJN-101, were obtained. After oral administration of TJN-101 at a dose of 10 mg/kg to male rats, the average values of the maximal serum concentration of TJN-101 and Met.B were 1446.1 +/- 131.8 and 317.4 +/- 18.5 ng/ml, respectively. The serum concentrations of these substances could be monitored sufficiently for 8 h after dosing.     

Effects of TJN-101, a lignan compound isolated from Schisandra fruits, on liver fibrosis and on liver regeneration after partial hepatectomy in rats with chronic liver injury induced by CCl4

TJN-101 ((+)-(6S,7S,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy -6,7-dimethyl-10,11-methylenedioxy-6-dibenzo[a,c]cyclooctenol) is one of the lignan compounds isolated from Schisandra fruits. 1) Effect of TJN-101 on liver fibrosis was investigated in rats which were injected with CCl4 (1 ml/kg) subcutaneously twice a week for 12 weeks. TJN-101 was given orally at the dose of 10 or 30 mg/kg/day for 6 or 3 weeks beginning on the 6th or 9th week after the start of CCl4-intoxication, respectively. The elevations of serum transaminase activities and the increase of liver 4-hydroxyproline content were observed depending on the period of CCl4-intoxication. These changes were marked on the 9th and 12th weeks after. In the histopathological study, the degenerative fatty change on the 6th week after and the formation of pseudolobule caused by fibrosis proliferation on the 9th or 12th week after were mainly observed. When rats were treated with TJN-101, the abnormalities in biochemical parameters and the fibrosis proliferation caused by CCl4-intoxication were improved. 2) Chronic liver injury was induced by the treatment with CCl4 (1 ml/kg) subcutaneously twice a week for 10 weeks to investigate the effect of TJN-101 on liver regeneration after partial hepatectomy. TJN-101, which was given orally at the dose of 10, 30 or 100 mg/kg/day for 6 days from the 1st day after partial hepatectomy, dose-dependently increased the liver regeneration rate and improved the serum BSP retention rate. These results suggest that TJN-101 suppresses the fibrosis proliferation and accelerates both the liver regeneration and the recovery of liver function after partial hepatectomy in chronic liver injury.     

Studies on the metabolic fate of gomisin A (TJN-101). II. Absorption and excretion in CCl4 treated rats]

The absorption and excretion of gomisin A (TJN-101) in rats whose livers were injured by carbon tetrachloride (CCl4) were investigated. After intravenous administration of TJN-101 at a dose of 5 mg/kg, the terminal elimination half-life was 1.5 h in the CCl4-treated rats, which was two times that in normal rats. The mean area under the blood concentration-time curve (AUC) value of TJN-101 in the CCl4-treated rats was twice that in normal rats, and this difference was significant (p less than 0.05). Therefore, the total body clearance of TJN-101 in the CCl4-treated rats decreased less than half of that in normal rats. Similar results were observed when it was administered orally. In the CCl4-treated rats, the serum concentration of Met. B, which was identified as a demethylenated substance and one of major metabolites, tended to decrease more than that in normal rats. On the other hand, the cumulative biliary excretion ratio of TJN-101 in 24 h after dosing in the CCl4-treated rats was 2.5 times that in normal rats. The excretion rate of Met. B in the bile in the CCl4-treated rats tended to be delayed. However, the quantitative variance of biliary excretion of Met. B was not found in both groups. The urinary excretion of TJN-101 or Met. B in 72 h after dosing in the CCl4-treated rats was lower than that in normal rats. Similar results were also observed in excretion in the feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of immunomodulators on liver regeneration

The directed influence of immunomodulators on various chains of the immune system makes possible the control over liver restoration processes, as demonstrated on the model of hepatic resection. It is established that macrophages together with T-lymphocytes play a very important role in the process of liver regeneration.     

Effects of TJN-101 ((+)-(6s,7s,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy-6,7 -dimethyl-10,11-methylenedioxy-6-dibenzo [a,c] cyclooctenol) on liver regeneration after partial hepatectomy, and on regional hepatic blood flow and fine structure of the liver in normal rats

Effects of TJN-101, one of the components isolated from Schizandra fruits, on liver regeneration after partial hepatectomy, and on regional hepatic blood flow and fine structure of the liver were investigated in normal rats. TJN-101, which was administered orally at the doses of 10, 30 and 100 mg/kg/day for 4 days after partial hepatectomy, increased the regeneration rate of the liver and improved the serum retention rate of BSP which had been dose-dependently decreased after the operation. Elevation of serum protein to control levels, elevation of serum LCAT activity, decrease in plasma insulin and increase in plasma glucagon were all dose-dependent responses to TJN-101. The mitotic index on the 5th day after the operation was hardly influenced by TJN-101. Regional hepatic blood flow was increased after intraduodenal administration of TJN-101 (30 and 100 mg/kg). Ultrastructural studies of liver tissue using the transmission electron microscope revealed that TJN-101 stimulated an increase in rough and smooth endoplasmic reticulum in the groups receiving 100 and 300 mg/kg/day. These results suggest that TJN-101 accelerates both the proliferation of hepatocytes and the recovery of liver function after partial hepatectomy and increases hepatic blood flow. It is also thought that the liver enlargement caused by repeated administration of TJN-101 is associated with the proliferation of endoplasmic reticulum.     

Effect of polyunsaturated phosphatidylcholine on liver regeneration onset after hepatectomy in the rat.

The purpose of this study was to examine the effect of polyunsaturated phosphatidylcholine (PPC, Essentiale) on the onset of liver regeneration after partial hepatectomy (PH). Hepatectomy was carried out on rats, and immediately after operation doses of 25, 50 or 250 mg PPC/kg b.w. were injected into the vena femoralis. The control group consisted of saline-injected PH rats. The rats were killed 18, 21, 24 and 30 h after PH. The course of liver regeneration was assessed by measuring the incorporation of labelled thymidine into DNA and the hepatocyte mitotic activity. After PPC injection no values of liver DNA specific activity differing from baseline were observed. However, higher values of hepatocyte mitotic activity and lower liver triglyceride levels were found as compared to the saline-treated rats. These observations indicate that the administration of PPC has a favourable effect on liver regeneration after PH.     

A comparison of mirex-induced liver growth to liver regeneration

In intact rats given a single oral dose of mirex there was a dose-dependent increase in liver weight which peaked at 4 days. There were increases in hepatic RNA and protein, but DNA content per liver and DNA synthesis as measured by [3H]thymidine incorporation were unchanged. In partially hepatectomized rats dosed with mirex 24 h post-surgery, there was a dose-dependent increase in relative liver weight which peaked at 5 days. In partially hepatectomized rats simultaneously dosed with mirex, [3H]thymidine incorporation into DNA was unaltered. However, in rats dosed with mirex 24 h prior to partial hepatectomy, there was a 50% reduction in [3H]thymidine incorporation into hepatic DNA.     

Toll样受体4在肝脏缺血再灌注损伤和肝再生中的作用

Toll样受体(TLR)是近年来倍受关注的一种病原识别受体,可特异地识别病原相关分子模式,通过激活信号级联反应产生细胞因子和相关刺激因子,从而在天然免疫和获得性免疫中发挥重要的桥梁作用。近年来,TLR4在肝脏缺血/再灌注(I/R)损伤等非病原微生物性炎症和肝再生中的作用也日益受到重视,已知其参与肝脏I/R损伤的部分炎症反应,但其是否参与肝再生过程有待进一步研究。     

Effect of tritoqualine on liver regeneration after partial hepatectomy in rats

Effect of tritoqualine (TRQ) on liver regeneration after partial hepatectomy in normal rats and chronically injured rats treated with carbon tetrachloride (CCl4) for 12 weeks were investigated by the measurement of serum and liver biochemical parameters concerning the hepatic function. The results are as follows: 1) In normal rats, the liver regeneration rate after partial hepatectomy was increased dose-dependently with the administration of TRQ for 7 days after the operation. TRQ improved BSP retention rate which was decreased after partial hepatectomy. In addition, protein synthetic activity in the liver microsomes prepared from TRQ-administered rats was higher than that prepared from control rats, and the contents of serum total protein, serum albumin and liver protein were also higher in TRQ-administered rats. 2) In the rats treated with CCl4 for 12 weeks, the liver regeneration rate after partial hepatectomy was increased dose-dependently with the administration of TRQ for 6 days. TRQ also improved the contents of serum total protein, serum albumin and liver protein. Though the amount of collagen in the liver chronically injured by CCl4 increased more than twice compared with that in the normal liver, the amount of collagen in the regenerating liver of CCl4-treated rats whose liver regeneration was accelerated by TRQ was not different from that in the normal liver. These results suggest that TRQ has the effect of improving the various hepatic functions through the activation of the protein synthesis in hepatocytes.     

Effect of calcium channel blockers and trifluoperazine on rat liver regeneration

The activity of hepatic thymidylate synthetase and thymidine kinase at 24 h after 70% partial hepatectomy of rats was suppressed significantly compared with that in the control group by the administration of calcium channel blockers (verapamil, diltiazem and nifedipine) 8 h after partial hepatectomy. The decrease of thymidylate synthetase and thymidine kinase activities was accompanied by a reduction of DNA content in 24 h regenerating liver. Trifluoperazine showed an effect similar to that of the calcium channel blockers on DNA synthesis during liver regeneration. These results suggest that calcium entry into the hepatic cell is an essential event in liver regeneration.     

Platelet-activating factor (PAF) involvement in acetaminophen-induced liver toxicity and regeneration

Acetaminophen-induced toxicity has been attributed to cytochrome P-450-generated metabolites, which covalently modify target proteins. However, the mechanism of liver injury pathogenesis needs to be further elucidated. Platelet-activating factor (PAF) is one of the mediators involved in inflammatory tissue alterations associated with acute liver failure. In this study, alterations in blood PAF levels and the serum activity of PAF-acetylhydrolase (PAF-AH) were investigated over the time course of liver injury and regeneration induced by acetaminophen treatment in rats. The administration of a toxic dose of acetaminophen (3.5 g/kg) in rats caused acute hepatic injury, as evident by alterations of biochemical (serum enzymes: ALT, AST and ALP) and liver histopathological (degree of inflammation and apoptosis) indices between 20 and 40 h post-treatment. The hepatic damage was followed by liver regeneration, made evident by three independent indices ([3H]thymidine incorporation into hepatic DNA, liver thymidine kinase activity and hepatocyte mitotic index), presenting a peak at 72 h. The PAF levels were elevated at 24 and 28 h, presenting a remarkable peak at 32 h post-treatment. PAF-AH activity presented different kinetics to that of PAF. The enzyme activity was relatively low at all time points examined before the rise in PAF activity, peaking later, at 72, 84 and 96 h. Our data demonstrate that PAF is involved in the pathogenesis of acute liver failure and in augmented compensatory liver tissue repair post-acetaminophen treatment. However, the putative role of PAF during liver toxicity and regeneration remains to be established.