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The effects of insulin pre-administration in mice exposed to ethanol: alleviating hepatic oxidative injury through anti-oxidative, anti-apoptotic activities and deteriorating hepatic steatosis through SRBEP-1c activation.

Liu J, Wang X, Peng Z, Zhang T, Wu H, Yu W, Kong D, Liu Y, Bai H, Liu R, Zhang X, Hai C - Int. J. Biol. Sci. (2015)

Bottom Line: Previous studies have showed that insulin, a classic regulator of glucose metabolism, has significant anti-oxidative function and plays an important role in maintaining the redox balance.First, we found insulin pre-administration alleviated acute ethanol exposure-induced liver injury and inflammation reflected by the decrease of serum AST and ALT activities, the improvement of pathological alteration and the inhibition of TNF-α and IL-6 expressions.Our study provided novel insight about the effects and mechanisms of insulin on ethanol-induced liver injury.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Toxicology, the Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, Shaanxi Provincial Key Lab of Free radical biology and medicine, School of Public Health, The Fourth Military Medical University, Xi'an, 710032, P. R. China;

ABSTRACT
Alcoholic liver disease (ALD) has become an important liver disease hazard to public and personal health. Oxidative stress is believed to be responsible for the pathological changes in ALD. Previous studies have showed that insulin, a classic regulator of glucose metabolism, has significant anti-oxidative function and plays an important role in maintaining the redox balance. For addressing the effects and mechanisms of insulin pre-administration on ethanol-induced liver oxidative injury, we investigated histopathology, inflammatory factors, apoptosis, mitochondrial dysfunction, oxidative stress, antioxidant defense system, ethanol metabolic enzymes and lipid disorder in liver of ethanol-exposed mice pretreatment with insulin or not. There are several novel findings in our study. First, we found insulin pre-administration alleviated acute ethanol exposure-induced liver injury and inflammation reflected by the decrease of serum AST and ALT activities, the improvement of pathological alteration and the inhibition of TNF-α and IL-6 expressions. Second, insulin pre-administration could significantly reduce apoptosis and ameliorate mitochondrial dysfunction in liver of mice exposed to ethanol, supporting by decreasing caspases-3 activities and the ratio of Bax/Bcl-2, increasing mitochondrial viability and mitochondrial oxygen consumption, inhibition of the decline of ATP levels and mitochondrial ROS accumulation. Third, insulin pre-administration prevented ethanol-mediated oxidative stress and enhance antioxidant defense system, which is evaluated by the decline of MDA levels and the rise of GSH/GSSG, the up-regulations of antioxidant enzymes CAT, SOD, GR through Nrf-2 dependent pathway. Forth, the modification of ethanol metabolism pathway such as the inhibition of CYP2E1, the activation of ALDH might be involved in the anti-oxidative and protective effects exerted by insulin pre-administration against acute ethanol exposure in mice. Finally, insulin pre-administration deteriorated hepatic steatosis in mice exposed to ethanol might be through SRBEP-1c activation. In summary, these results indicated that insulin pre-administration effectively alleviated liver oxidative injury through anti-inflammatory, anti-oxidative and anti-apoptotic activities but also deteriorated hepatic steatosis through SRBEP-1c activation in mice exposed to ethanol. Our study provided novel insight about the effects and mechanisms of insulin on ethanol-induced liver injury.

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Ethanol metabolism pathway modified by insulin pre-administration might be involved in the anti-oxidative and protective effects against acute ethanol exposure in mice. (A) Hepatic CYP2E1 mRNA level determinate by RT-PCR; (B) CYP2E1, ADH and ALDH2 protein expression in liver determinate by Western blotting; (C) Value of the CYP2E1, ADH and ALDH2 protein expression expressed as the folds of control; (D) Hepatic CYP2E1 activity; (E) Hepatic ADH activity; (F) Hepatic ALDH2 activity. Normalizations of Western blots were ensured by Tubulin. Data of A and C were expressed as the mean ± SD of three independent experiments (n = 3). Data of D-F were expressed as mean± SD (n = 8). *P< 0.05, compared to control group; #P < 0.05, compared to EtOH group.
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Figure 6: Ethanol metabolism pathway modified by insulin pre-administration might be involved in the anti-oxidative and protective effects against acute ethanol exposure in mice. (A) Hepatic CYP2E1 mRNA level determinate by RT-PCR; (B) CYP2E1, ADH and ALDH2 protein expression in liver determinate by Western blotting; (C) Value of the CYP2E1, ADH and ALDH2 protein expression expressed as the folds of control; (D) Hepatic CYP2E1 activity; (E) Hepatic ADH activity; (F) Hepatic ALDH2 activity. Normalizations of Western blots were ensured by Tubulin. Data of A and C were expressed as the mean ± SD of three independent experiments (n = 3). Data of D-F were expressed as mean± SD (n = 8). *P< 0.05, compared to control group; #P < 0.05, compared to EtOH group.

Mentions: Having demonstrated that insulin pre-administration reduced ethanol-induced liver injury, we further investigated whether modification of ethanol metabolism pathway is involved in this protective function. We first determined the mRNA expression of CYP2E1 in liver. As shown in Fig.6 A, mRNA expression of hepatic CYP2E1was significantly down-regulated in insulin group and significantly up-regulated in ethanol group. We also found that the up-regulation of CYP2E1 induced by ethanol was notably reversed by insulin pre-administration. We next investigated the protein expressions of hepatic CYP2E1, ADH and ALDH2 by Western blotting. As illustrated in Fig.6 B and C, in insulin administration group, hepatic CYP2E1 protein expression was also significantly down-regulated and hepatic ALDH2 protein expression was significantly up-regulated, but hepatic ADH protein expression had no significant change. However, insulin pre-administration effectively suppressed the increase of CYP2E1, ADH protein expressions and the decrease of ALDH2 protein expression in mice exposed to ethanol. To further study the role of these key ethanol metabolism enzymes in protection of insulin, we also determinate the activities of these enzymes. As demonstrated in Fig.6 D-F, our results revealed that ethanol markedly increased the activities of CYP2E1, ADH and decreased activity of ALDH compared with control group, and insulin pre-administration effectively alleviated these trends to normal control group, which is consistent with the results of protein expressions. Taken together, these data suggested that protective and antioxidative effects exerted by insulin pre-administration might involve in the modification of ethanol metabolism pathway.


The effects of insulin pre-administration in mice exposed to ethanol: alleviating hepatic oxidative injury through anti-oxidative, anti-apoptotic activities and deteriorating hepatic steatosis through SRBEP-1c activation.

Liu J, Wang X, Peng Z, Zhang T, Wu H, Yu W, Kong D, Liu Y, Bai H, Liu R, Zhang X, Hai C - Int. J. Biol. Sci. (2015)

Ethanol metabolism pathway modified by insulin pre-administration might be involved in the anti-oxidative and protective effects against acute ethanol exposure in mice. (A) Hepatic CYP2E1 mRNA level determinate by RT-PCR; (B) CYP2E1, ADH and ALDH2 protein expression in liver determinate by Western blotting; (C) Value of the CYP2E1, ADH and ALDH2 protein expression expressed as the folds of control; (D) Hepatic CYP2E1 activity; (E) Hepatic ADH activity; (F) Hepatic ALDH2 activity. Normalizations of Western blots were ensured by Tubulin. Data of A and C were expressed as the mean ± SD of three independent experiments (n = 3). Data of D-F were expressed as mean± SD (n = 8). *P< 0.05, compared to control group; #P < 0.05, compared to EtOH group.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4400388&req=5

Figure 6: Ethanol metabolism pathway modified by insulin pre-administration might be involved in the anti-oxidative and protective effects against acute ethanol exposure in mice. (A) Hepatic CYP2E1 mRNA level determinate by RT-PCR; (B) CYP2E1, ADH and ALDH2 protein expression in liver determinate by Western blotting; (C) Value of the CYP2E1, ADH and ALDH2 protein expression expressed as the folds of control; (D) Hepatic CYP2E1 activity; (E) Hepatic ADH activity; (F) Hepatic ALDH2 activity. Normalizations of Western blots were ensured by Tubulin. Data of A and C were expressed as the mean ± SD of three independent experiments (n = 3). Data of D-F were expressed as mean± SD (n = 8). *P< 0.05, compared to control group; #P < 0.05, compared to EtOH group.
Mentions: Having demonstrated that insulin pre-administration reduced ethanol-induced liver injury, we further investigated whether modification of ethanol metabolism pathway is involved in this protective function. We first determined the mRNA expression of CYP2E1 in liver. As shown in Fig.6 A, mRNA expression of hepatic CYP2E1was significantly down-regulated in insulin group and significantly up-regulated in ethanol group. We also found that the up-regulation of CYP2E1 induced by ethanol was notably reversed by insulin pre-administration. We next investigated the protein expressions of hepatic CYP2E1, ADH and ALDH2 by Western blotting. As illustrated in Fig.6 B and C, in insulin administration group, hepatic CYP2E1 protein expression was also significantly down-regulated and hepatic ALDH2 protein expression was significantly up-regulated, but hepatic ADH protein expression had no significant change. However, insulin pre-administration effectively suppressed the increase of CYP2E1, ADH protein expressions and the decrease of ALDH2 protein expression in mice exposed to ethanol. To further study the role of these key ethanol metabolism enzymes in protection of insulin, we also determinate the activities of these enzymes. As demonstrated in Fig.6 D-F, our results revealed that ethanol markedly increased the activities of CYP2E1, ADH and decreased activity of ALDH compared with control group, and insulin pre-administration effectively alleviated these trends to normal control group, which is consistent with the results of protein expressions. Taken together, these data suggested that protective and antioxidative effects exerted by insulin pre-administration might involve in the modification of ethanol metabolism pathway.

Bottom Line: Previous studies have showed that insulin, a classic regulator of glucose metabolism, has significant anti-oxidative function and plays an important role in maintaining the redox balance.First, we found insulin pre-administration alleviated acute ethanol exposure-induced liver injury and inflammation reflected by the decrease of serum AST and ALT activities, the improvement of pathological alteration and the inhibition of TNF-α and IL-6 expressions.Our study provided novel insight about the effects and mechanisms of insulin on ethanol-induced liver injury.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Toxicology, the Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, Shaanxi Provincial Key Lab of Free radical biology and medicine, School of Public Health, The Fourth Military Medical University, Xi'an, 710032, P. R. China;

ABSTRACT
Alcoholic liver disease (ALD) has become an important liver disease hazard to public and personal health. Oxidative stress is believed to be responsible for the pathological changes in ALD. Previous studies have showed that insulin, a classic regulator of glucose metabolism, has significant anti-oxidative function and plays an important role in maintaining the redox balance. For addressing the effects and mechanisms of insulin pre-administration on ethanol-induced liver oxidative injury, we investigated histopathology, inflammatory factors, apoptosis, mitochondrial dysfunction, oxidative stress, antioxidant defense system, ethanol metabolic enzymes and lipid disorder in liver of ethanol-exposed mice pretreatment with insulin or not. There are several novel findings in our study. First, we found insulin pre-administration alleviated acute ethanol exposure-induced liver injury and inflammation reflected by the decrease of serum AST and ALT activities, the improvement of pathological alteration and the inhibition of TNF-α and IL-6 expressions. Second, insulin pre-administration could significantly reduce apoptosis and ameliorate mitochondrial dysfunction in liver of mice exposed to ethanol, supporting by decreasing caspases-3 activities and the ratio of Bax/Bcl-2, increasing mitochondrial viability and mitochondrial oxygen consumption, inhibition of the decline of ATP levels and mitochondrial ROS accumulation. Third, insulin pre-administration prevented ethanol-mediated oxidative stress and enhance antioxidant defense system, which is evaluated by the decline of MDA levels and the rise of GSH/GSSG, the up-regulations of antioxidant enzymes CAT, SOD, GR through Nrf-2 dependent pathway. Forth, the modification of ethanol metabolism pathway such as the inhibition of CYP2E1, the activation of ALDH might be involved in the anti-oxidative and protective effects exerted by insulin pre-administration against acute ethanol exposure in mice. Finally, insulin pre-administration deteriorated hepatic steatosis in mice exposed to ethanol might be through SRBEP-1c activation. In summary, these results indicated that insulin pre-administration effectively alleviated liver oxidative injury through anti-inflammatory, anti-oxidative and anti-apoptotic activities but also deteriorated hepatic steatosis through SRBEP-1c activation in mice exposed to ethanol. Our study provided novel insight about the effects and mechanisms of insulin on ethanol-induced liver injury.

Show MeSH
Related in: MedlinePlus