Galactosamine-Induced Acute Liver Injury in Rats Reduces Hepatic .ALPHA.-Tocopherol Transfer Protein Production

Changes in the expression of α-tocopherol-related genes in liver and mammary gland biopsy specimens of peripartum dairy cows

Blood α-tocopherol (α-Toc) concentrations decline gradually throughout the prepartum period, reaching the nadir after calving in dairy cows. The 6 α-Toc-related molecules [α-Toc transfer protein (TTPA); afamin; scavenger receptor class B, Type I; ATP-binding cassette transporter A1; tocopherol-associated protein (SEC14L2); and cytochrome P450 family 4, subfamily F, polypeptide 2 (CYP4F2)] are expressed in liver and other peripheral tissues. These molecules could regulate α-Toc transport, blood concentrations, and metabolism of α-Toc. Therefore, the aim of this study was to evaluate the changes in the expression of α-Toc-related genes in liver and mammary gland tissues of dairy cows around calving, which have remained elusive until now. In experiment (Exp.) 1, 28 multiparous Holstein cows were used (from -5 to 6 wk relative to parturition) to monitor the changes in dietary α-Toc intake, blood concentrations of α-Toc, and lipoproteins; in Exp. 2, 7 peripartum Holstein cows were used (from -4 to 4 wk relative to parturition) for liver tissue biopsy; and in Exp. 3, 10 peripartum Holstein cows were used (from -8 to 6 wk relative to parturition) to carry out the mammary gland tissue biopsy and milk sampling. In Exp. 1, the serum α-Toc concentrations declined gradually with decreasing amount of α-Toc intake and plasma high-density lipoprotein concentrations toward calving time. However, in the early lactation period after calving, serum α-Toc concentrations remained at a lower concentration despite the recovery of α-Toc intake and plasma high-density lipoprotein concentrations. In Exp. 2, just after calving, the TTPA, SEC14L2, afamin, and albumin mRNA expression levels in the liver were temporarily downregulated, and the hepatic mRNA levels of endoplasmic reticulum stress-induced unfolded protein response markers and acute-phase response marker increased at calving. In Exp. 3, the concentrations of α-Toc in colostrum were greater than those in precolostrum (samples were collected at wk -1 relative to parturition) and mature milk. The expression of TTPA, SEC14L2, and CYP4F2 mRNA in bovine mammary gland tissue was detected. However, TTPA and SEC14L2 mRNA expressions showed the opposite trends: the expression levels of TTPA mRNA peaked whereas SEC14L2 mRNA reached a nadir at calving. These results indicate that the expression of α-Toc-related genes involved in specific α-Toc transfer and metabolism in the liver and mammary gland are altered during calving. Moreover, these changes might be associated with the maintenance of lower serum α-Toc concentrations after calving.

Dietary vitamin E deficiency increases anxiety-like behavior in juvenile and adult rats

Vitamin E deficiency from birth or infancy has recently been found to increase anxiety-like behavior in rodents. The present study was undertaken to elucidate the effect of dietary vitamin E deficiency on anxiety in adult rats in comparison with juvenile rats. Male Wistar rats, 3 or 10 weeks old, were divided into two groups and fed a control or vitamin E-deficient diet for 4 weeks. The results of behavioral analysis revealed that vitamin E-deficiency increased anxiety in both juvenile and adult rats. Plasma, liver, and brain α-tocopherol concentrations decreased significantly due to vitamin E deficiency in both age groups. Plasma corticosterone concentrations were higher in the vitamin E-deficient rats in response to the stress of a behavioral test. Based on these results, we conclude that dietary vitamin-E deficiency induces anxiety in adult rats as well as juvenile rats. This might be due to an elevated plasma corticosterone concentration.

Effect of globin digest on the liver injury and hepatic gene expression profile in galactosamine-induced liver injury in SD rats

AIMS

We investigated the effect of globin digest (GD) on the liver injury and hepatic gene expression profile in galactosamine (GalN)-induced liver injury.

MAIN METHODS

The effect of GD on the liver injury was examined by measuring the activities of serum transferases and hepatic antioxidant enzymes, histopathological analysis, gene expression profile, and proteins of the peroxisome proliferator-activated receptor alpha (PPARα) and met proto-oncogene (c-Met) in SD rats at 24 h after GalN administration. The effect of GD on the expression of PPARα and its target gene in AML-12 mouse hepatocytes was also examined.

KEY FINDINGS

GD suppressed the elevated activities of serum transferases in GalN-induced liver injury in SD rats. The thiobarbituric acid reactive substance content in GalN-injured liver was a decreasing tendency by GD. GD suppressed the increased oxidized glutathione content, and increased the decreased protein, reduced glutathione contents, and catalase activity in GalN-injured liver. GD may improve the antioxidant defense system and protein synthesis in GalN-injured liver. GD suppressed the elevated expression of the genes related to the inflammation, and decreased the histopathological grade value of inflammatory cell infiltration in GalN-injured liver. GD increased the expression of PPARα protein in GalN-injured liver, and also increased the expression of PPARα and its target gene in AML-12 hepatocytes. The total and phosphorylated c-Met proteins in GalN-injured liver were the increasing tendencies by GD.

SIGNIFICANCE

These findings indicate that GD has the hepatoprotective effect on GalN-induced liver injury in SD rats.

Effects of Oxidized Frying Oil on Proteins Related to alpha-Tocopherol Metabolism in Rat Liver

An oxidized frying oil (OFO) diet has been reported to induce an increase in lipid peroxidation and a reduction in vitamin E status in animal tissues. This study was performed to investigate how vitamin E metabolism is influenced by OFO. Male Wistar rats were divided into three groups, a control group (CO) and two OFO-fed groups (OF and OFE). The diet of the OFE group was supplemented with an extra 50 mg/kg of alpha-tocopherol acetate and thus contained twice as much vitamin E as that of the OF group. After six weeks on these diets, liver alpha-tocopherol levels in the OF group were the significantly lowest among the three groups. Excretion of the alpha-tocopherol metabolite, alpha-carboxyethyl hydroxychroman (alpha-CEHC) in the urine was significantly lower in the OF group than in the other two groups. There were no significant differences in protein levels of alpha-tocopherol transfer protein (alpha-TTP) and multidrug resistance protein among the three groups. Protein levels of cytochrome P450 monooxygenase (CYP) 3A, CYP4A, and catalase were markedly increased in both groups on the OFO diet. This suggests that an OFO diet may interfere with medicine metabolism and needs further investigation.

Effects of pregnenolone-16alpha-carbonitrile on vitamin E status and protein levels of antioxidant enzymes in male rats fed a vitamin E-supplemented diet

The aim of this study was to evaluate the effects of the administration of pregnenolone-16alpha-carbonitrile (PCN), an inducer of the cytochrome P450 3A gene in rats, on vitamin E status and antioxidant enzyme protein levels in rats fed a vitamin E-supplemented diet. Two groups of male Wistar rats were fed for 3 weeks with a basal diet containing 50 ppm of alpha-tocopherol or the same diet containing 10 times more alpha-tocopherol. In the final 3 days, each group was divided into two subgroups which were given a single daily intraperitoneal injection of PCN at 75 mg/kg (groups PCN and PCN+VE) or DMSO (groups DS and DS+VE). PCN treatment alone significantly reduced the alpha-tocopherol content of the liver and plasma and this effect was prevented by supplementation with 10-fold more alpha-tocopherol. alpha-Tocopherol levels in the kidneys, lung, heart, and testes were significantly higher in both vitamin E-supplemented groups than in the control groups. TBARS levels in the liver and lung were significantly increased in both PCN-treated groups, as shown by two-way ANOVA analysis. PCN also caused a significant reduction in protein levels of catalase and glutathione peroxidase (GPx) in both groups. Dietary vitamin E supplementation caused a decrease in liver protein levels of GPx and superoxide dismutase, but not catalase, in both groups and protected against PCN-induced lipid peroxidation, which was caused by CYP3A induction and a reduction in antioxidant enzyme levels.

Dietary vitamin E deficiency increases anxiety-related behavior in rats under stress of social isolation

It has been demonstrated that vitamin E deficiency from birth increases anxiety-related behavior using knockout animals with no vitamin E transfer proteins. The current study was undertaken to elucidate the effect of dietary vitamin E deficiency on anxiety-related behavior of rats in different housing conditions. Male Wistar strain rats were divided into two groups during the weaning period and fed a control or vitamin E-deficient diet. All rats were housed in groups (three rats per cage) for 3 weeks. In the fourth week, half of the rats in each dietary treatment were kept in social housing and the other half were kept in individual housing. Before sacrifice, rota-rod and elevated plus-maze (EPM) tests were performed to measure motor coordination and anxiety, respectively. The EPM test revealed that vitamin E-deficient rats spent less time in the open arms and showed more stretch-out posture than the control rats, showing that anxiety increased with dietary vitamin E deficiency. Furthermore, vitamin E deficiency-induced anxiety behavior was observed more prominent in individual housed rats than in social housed rats. On the basis of these results, we conclude that dietary vitamin E deficiency induces anxiety in rats especially under stress of social isolation.