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Effects of flavonoids on sphingolipid turnover in the toxin-damaged liver and liver cells.

Babenko NA, Shakhova EG - Lipids Health Dis (2008)

Bottom Line: Flavonoids affect sphingolipid metabolism and reduce the elevated ceramide level in the aged liver.CCl4 administration to the rats enlarged ceramide mass as well as neutral sphingomyelinase (SMase) activity and reduced ceramide degradation by the neutral ceramidase.Pretreatment of isolated hepatocytes with flavonoids abrogated the CCl4 effects on the cell membrane integrity and normalized the ceramide content.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology of Ontogenesis, Institute of Biology, Kharkov Karazin National University, 4, Svobody pl., Kharkov, 61077, Ukraine. babenko@univer.kharkov.ua

ABSTRACT

Background: The ceramide generation is an early event in the apoptotic response to numerous stimuli including the oxidative stress and ceramide analogs mimic the stress effect and induce apoptosis. Flavonoids of German chamomile are reported to exhibit the hepatoprotective effect. Flavonoids affect sphingolipid metabolism and reduce the elevated ceramide level in the aged liver. In the present paper, the ceramide content and production in the CCl4- and ethanol-treated liver and hepatocytes as well as the correction of sphingolipid metabolism in the damaged liver using the mixture of German chamomile flavonoids (chamiloflan) or apigenin-7-glucoside (AP7Glu) have been investigated.

Results: The experiments were performed in either the rat liver or hepatocytes of normal, CCl4- and ethanol-treated or flavonoid- and toxin plus flavonoid-treated animals. [14C]palmitic acid and [methyl-14C-phosphorylcholine]sphingomyelin were used to investigate the sphingolipid turnover. Addition of the CCl4 or ethanol to isolated hepatocyte suspensions caused loss of cell viability and increased the lactate dehydrogenase release from the cells into supernatant and ceramide level in the cells. CCl4 administration to the rats enlarged ceramide mass as well as neutral sphingomyelinase (SMase) activity and reduced ceramide degradation by the neutral ceramidase. Pretreatment of isolated hepatocytes with flavonoids abrogated the CCl4 effects on the cell membrane integrity and normalized the ceramide content. Flavonoid administration to the rats normalized the elevated ceramide content in the damaged liver via neutral SMase inhibition and ceramidase activation.

Conclusion: The data obtained have demonstrated that flavonoids affect sphingolipid metabolism in the CCl4- and ethanol-damaged liver and liver cells. Flavonoids normalized activities of key enzymes of sphingolipid turnover (neutral SMase and ceramidase) and ceramide contents in the damaged liver and liver cells, and stabilized the hepatocyte membranes.

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Effects of the flavonoids on the shingomyelinase activity and ceramide production induced in the liver by the CCl4. CCl4 (50% in corn oil, 4 mg/kg body weight) was injected to rats subcutaneously daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days Some of the animals were fed by chamiloflan (160 mg/kg body weight) daily for 4 days together with CCl4 injections and 2 days after last CCl4 treatment. Control rats were injected subcutaneously by corn oil (2 ml/kg body weight) daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days. Liver homogenates were used for the determination of the neutral SMase activity (pH 7.4) (A) and ceramide generation under neutral (pH 7.4) and acidic (pH 4.5) conditions (B) as described in the "Materials and Methods". The [methyl-14C-phosphorylcholine]sphingomyelin as a substrate was used. Results are mean ± S.E. of six experiments performed in duplicate. * P < 0.05, CCl4-treated rats vs. control; ** P < 0.05, CCl4+flavonoid-treated rats vs. CCl4-treated.
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Figure 5: Effects of the flavonoids on the shingomyelinase activity and ceramide production induced in the liver by the CCl4. CCl4 (50% in corn oil, 4 mg/kg body weight) was injected to rats subcutaneously daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days Some of the animals were fed by chamiloflan (160 mg/kg body weight) daily for 4 days together with CCl4 injections and 2 days after last CCl4 treatment. Control rats were injected subcutaneously by corn oil (2 ml/kg body weight) daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days. Liver homogenates were used for the determination of the neutral SMase activity (pH 7.4) (A) and ceramide generation under neutral (pH 7.4) and acidic (pH 4.5) conditions (B) as described in the "Materials and Methods". The [methyl-14C-phosphorylcholine]sphingomyelin as a substrate was used. Results are mean ± S.E. of six experiments performed in duplicate. * P < 0.05, CCl4-treated rats vs. control; ** P < 0.05, CCl4+flavonoid-treated rats vs. CCl4-treated.

Mentions: It has been demonstrated that CCl4 as well as ethanol lead to the pronounced accumulation of ceramide in the liver cells and stimulate the sphingolipid turnover in the liver. Using the [methyl-14C-phosphorylcholine]SM, it has been determined that under the neutral pH conditions the [14C-methyl]SM content drop, while [14C-methyl]phosphorylcholine release from the [14C-methyl]SM increased in the liver homogenates of CCl4-treated rats, as compared to the control animals (Figure 5A). The [14C-methyl]SM hydrolyses at neutral pH was accompanied by ceramide production in the liver homogenates of the toxin-treated animals as compared with the control rats (Figure 5B). The administration of the CCl4 to the rats did not change the ceramide production (Figure 5B) and [14C-methyl]SM degradation in the liver homogenates under the acidic pH (data not shown). The results obtained strongly demonstrated that the acidic SMase was not implicated in ceramide accumulation in the CCl4-treated liver.


Effects of flavonoids on sphingolipid turnover in the toxin-damaged liver and liver cells.

Babenko NA, Shakhova EG - Lipids Health Dis (2008)

Effects of the flavonoids on the shingomyelinase activity and ceramide production induced in the liver by the CCl4. CCl4 (50% in corn oil, 4 mg/kg body weight) was injected to rats subcutaneously daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days Some of the animals were fed by chamiloflan (160 mg/kg body weight) daily for 4 days together with CCl4 injections and 2 days after last CCl4 treatment. Control rats were injected subcutaneously by corn oil (2 ml/kg body weight) daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days. Liver homogenates were used for the determination of the neutral SMase activity (pH 7.4) (A) and ceramide generation under neutral (pH 7.4) and acidic (pH 4.5) conditions (B) as described in the "Materials and Methods". The [methyl-14C-phosphorylcholine]sphingomyelin as a substrate was used. Results are mean ± S.E. of six experiments performed in duplicate. * P < 0.05, CCl4-treated rats vs. control; ** P < 0.05, CCl4+flavonoid-treated rats vs. CCl4-treated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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Figure 5: Effects of the flavonoids on the shingomyelinase activity and ceramide production induced in the liver by the CCl4. CCl4 (50% in corn oil, 4 mg/kg body weight) was injected to rats subcutaneously daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days Some of the animals were fed by chamiloflan (160 mg/kg body weight) daily for 4 days together with CCl4 injections and 2 days after last CCl4 treatment. Control rats were injected subcutaneously by corn oil (2 ml/kg body weight) daily for 4 days and fed by ethanol (1 %, 5 ml/kg body weight) daily for 6 days. Liver homogenates were used for the determination of the neutral SMase activity (pH 7.4) (A) and ceramide generation under neutral (pH 7.4) and acidic (pH 4.5) conditions (B) as described in the "Materials and Methods". The [methyl-14C-phosphorylcholine]sphingomyelin as a substrate was used. Results are mean ± S.E. of six experiments performed in duplicate. * P < 0.05, CCl4-treated rats vs. control; ** P < 0.05, CCl4+flavonoid-treated rats vs. CCl4-treated.
Mentions: It has been demonstrated that CCl4 as well as ethanol lead to the pronounced accumulation of ceramide in the liver cells and stimulate the sphingolipid turnover in the liver. Using the [methyl-14C-phosphorylcholine]SM, it has been determined that under the neutral pH conditions the [14C-methyl]SM content drop, while [14C-methyl]phosphorylcholine release from the [14C-methyl]SM increased in the liver homogenates of CCl4-treated rats, as compared to the control animals (Figure 5A). The [14C-methyl]SM hydrolyses at neutral pH was accompanied by ceramide production in the liver homogenates of the toxin-treated animals as compared with the control rats (Figure 5B). The administration of the CCl4 to the rats did not change the ceramide production (Figure 5B) and [14C-methyl]SM degradation in the liver homogenates under the acidic pH (data not shown). The results obtained strongly demonstrated that the acidic SMase was not implicated in ceramide accumulation in the CCl4-treated liver.

Bottom Line: Flavonoids affect sphingolipid metabolism and reduce the elevated ceramide level in the aged liver.CCl4 administration to the rats enlarged ceramide mass as well as neutral sphingomyelinase (SMase) activity and reduced ceramide degradation by the neutral ceramidase.Pretreatment of isolated hepatocytes with flavonoids abrogated the CCl4 effects on the cell membrane integrity and normalized the ceramide content.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology of Ontogenesis, Institute of Biology, Kharkov Karazin National University, 4, Svobody pl., Kharkov, 61077, Ukraine. babenko@univer.kharkov.ua

ABSTRACT

Background: The ceramide generation is an early event in the apoptotic response to numerous stimuli including the oxidative stress and ceramide analogs mimic the stress effect and induce apoptosis. Flavonoids of German chamomile are reported to exhibit the hepatoprotective effect. Flavonoids affect sphingolipid metabolism and reduce the elevated ceramide level in the aged liver. In the present paper, the ceramide content and production in the CCl4- and ethanol-treated liver and hepatocytes as well as the correction of sphingolipid metabolism in the damaged liver using the mixture of German chamomile flavonoids (chamiloflan) or apigenin-7-glucoside (AP7Glu) have been investigated.

Results: The experiments were performed in either the rat liver or hepatocytes of normal, CCl4- and ethanol-treated or flavonoid- and toxin plus flavonoid-treated animals. [14C]palmitic acid and [methyl-14C-phosphorylcholine]sphingomyelin were used to investigate the sphingolipid turnover. Addition of the CCl4 or ethanol to isolated hepatocyte suspensions caused loss of cell viability and increased the lactate dehydrogenase release from the cells into supernatant and ceramide level in the cells. CCl4 administration to the rats enlarged ceramide mass as well as neutral sphingomyelinase (SMase) activity and reduced ceramide degradation by the neutral ceramidase. Pretreatment of isolated hepatocytes with flavonoids abrogated the CCl4 effects on the cell membrane integrity and normalized the ceramide content. Flavonoid administration to the rats normalized the elevated ceramide content in the damaged liver via neutral SMase inhibition and ceramidase activation.

Conclusion: The data obtained have demonstrated that flavonoids affect sphingolipid metabolism in the CCl4- and ethanol-damaged liver and liver cells. Flavonoids normalized activities of key enzymes of sphingolipid turnover (neutral SMase and ceramidase) and ceramide contents in the damaged liver and liver cells, and stabilized the hepatocyte membranes.

Show MeSH
Related in: MedlinePlus