Implication of vitamin A deficiency on vascular injury related to inflammation and oxidative stress. Effects on the ultrastructure of rat aorta.

BACKGROUND: Vitamin A deficiency induces activation of NF-kB and impairs activities of antioxidant enzymes in aorta. AIM OF THE STUDY: We study the effect of vitamin A deficiency on the aorta histoarchitecture and the possibly contribution of its prooxidant and inflammatory effects to artery alterations. METHODS: Twenty-one-day-old Wistar male rats were fed during 3 months with vitamin A-deficient diet (-A, n = 8) or the same diet containing 8 mg of retinol palmitate/kg of diet (+A, control, n = 8). In aortas, thiobarbituric reactive substances and reduced glutathione levels were measured by spectrophotometry. Expressions of TNF-alpha, NOX-2, VCAM-1, and TGF-beta1 were assessed by RT-PCR and Western Blot. The morphology of aorta was examined by light and transmission electron microscopy. RESULTS: In -A rats, high levels of TBARS in serum and aorta and low levels of GSH in aorta were found. An increased expression of TNF-alpha, NOX-2, VCAM-1, and TGF-beta1 in aorta from -A rats was observed. Examination of the intimal layer by light microscopy indicated the presence of an irregular surface in -A aortas. TEM studies showed large vacuoles and multivesicular bodies along the endothelium and also multivesicular bodies in the subendothelial space of aortas from -A rats. Furthermore, the histological appearance of internal elastic lamina was different from control. Small vesicles in the medial layer were observed in aortas from vitamin A-deficient rats. CONCLUSIONS: Vitamin A deficiency produces histoarchitectural alterations in aorta, which can be associated, at least in part, to the oxidative stress and inflammation induced by vitamin A deficiency.

The DUX4 protein is a co-repressor of the progesterone and glucocorticoid nuclear receptors.

DUX4 is a transcription factor required during early embryonic development in placental mammals. In this work, we provide evidence that DUX4 is a co-repressor of nuclear receptors (NRs) of progesterone (PR) and glucocorticoids (GR). The DUX4 C-ter and N-ter regions, including the nuclear localization signals and homeodomain motifs, contribute to the co-repressor activity of DUX4 on PR and GR. Immunoprecipitation studies, using total protein extracts of cells expressing tagged versions of DUX4 and GR, support that these proteins are physically associated. Our studies suggest that DUX4 could modulate gene expression by co-regulating the activity of hormone NRs. This is the first report highlighting a potential endocrine role for DUX4.

Vitamin A deficiency modifies lipid metabolism in rat liver.

Liver fatty acid metabolism of male rats fed on a vitamin A-deficient diet for 3 months from 21 d of age was evaluated. Vitamin A restriction produced subclinical plasma and negligible liver retinol concentrations, compared with the control group receiving the same diet with 4000 IU vitamin A (8 mg retinol as retinyl palmitate)/kg diet. Vitamin A deficiency induced a hypolipidaemic effect by decreasing serum triacylglycerol, cholesterol and HDL-cholesterol levels. The decrease of liver total phospholipid was associated with low phosphatidylcholine synthesis observed by lower [14C]choline incorporation into phosphatidylcholine, compared with control. Also, liver fatty acid synthesis decreased, as was indicated by activity and mRNA expression of acetyl-CoA carboxylase (ACC), and incorporation of [14C]acetate into saponified lipids. A decrease of the PPARalpha mRNA expression was observed. Liver mitochondria of vitamin A-deficient rats showed a lower total phospholipid concentration coinciding with a decrease of the cardiolipin proportion, without changes in the other phospholipid fractions determined. The mitochondria fatty acid oxidation increased by 30 % of the control value and it was attributed to a high activity and mRNA expression of carnitine palmitoyltransferase-I (CPT-I). An increase in serum beta-hydroxybutyrate levels was observed in vitamin A-deficient rats. Vitamin A deficiency alters the mitochondria lipid composition and also enhances fatty acid oxidation by modifying the production of malonyl-CoA, the endogenous inhibitor of CPT-I, due to decreased activity of liver ACC. The incorporation of vitamin A into the diet of vitamin A-deficient rats reverted all the changes observed.

Alterations in the lipid metabolism of rat aorta: effects of vitamin a deficiency.

Antioxidants are known to reduce cardiovascular disease by reducing the concentration of free radicals in the vessel wall and by preventing the oxidative modification of low-density lipoproteins. The prooxidative effect of a vitamin-A-deficient diet on the aorta has previously been demonstrated by us. In this study, the lipid metabolism in the aorta of rats fed on a vitamin-A-deficient diet was evaluated. Vitamin A deficiency induced a hypolipidemic effect (lower serum triglyceride and cholesterol levels) and a decreased serum paraoxonase 1/arylesterase activity. The concentrations of triglycerides, total cholesterol, free and esterified cholesterol, and phospholipids were increased in the aorta of vitamin-A-deficient rats. The phospholipid compositions showed an increase in phosphatidylcholine (PC), phosphatidylinositol plus phosphatidylserine and phosphatidylethanolamine, a decrease in sphingomyelin, and no change in phosphatidylglycerol. In the aorta, the increase in triglycerides was associated with an increased fatty acid synthesis and mRNA expression of diacylglycerol acyltransferase 1. The increased PC content was attributed to an increased synthesis, as measured by [methyl-(14)C]choline incorporation into PC and high CTP:phosphocholine cytidylyltransferase-alpha mRNA expression. The cholesterol synthesis, evaluated by [1-(14)C]acetate incorporated into cholesterol and mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase, did not change. The lipoprotein lipase and lectin-like oxidized low-density lipoprotein receptor 1 mRNA expression levels increased in the aorta of vitamin-A-deficient animals. The incorporation of vitamin A into the diet of vitamin-A-deficient rats reverted all the changes observed. These results indicate that a vitamin-A-deficient diet,in addition to having a prooxidative effect, alters the aorta lipid metabolism.