Project description:Vitamin A (retinol) is an essential precursor for the production of retinoic acid (RA), which in turn is a major regulator of gene expression, affecting cell differentiation throughout the body. Understanding how vitamin A nutritional status, as well as therapeutic retinoid treatment, regulates the expression of retinoid homeostatic genes is important for improving dietary recommendations and therapeutic strategies using retinoids. This study investigated genes central to processes of retinoid uptake and storage, release to plasma, and oxidation in the liver of rats under steady-state conditions after different exposures to dietary vitamin A (deficient, marginal, adequate and supplemented), and acutely after administration of a therapeutic dose of all-trans-RA. Over a very wide range of dietary vitamin A, lecithin:retinol acyltransferase (LRAT) as well as multiple cytochrome P450s (CYP26A1, CYP26B1, and CYP2C22) differed by diet and were highly correlated with one another and with vitamin A status assessed by liver retinol concentration (all correlations, P<0.05). After acute treatment with RA, the same genes were rapidly and concomitantly induced, preceding RARß, a classical direct target of RA. CYP26A1 mRNA exhibited the greatest dynamic range (change of log26 in 3 h). Moreover, CYP26A1 increased more rapidly in the liver of RA-primed rats than naïve rats. By in situ hybridization, CYP26A1 mRNA was strongly regulated within hepatocytes, closely resembling RBP4 in location. Overall, whether RA is produced endogenously from retinol or administered exogenously, changes in retinoid homeostatic gene expression simultaneously favor both retinol esterification and RA oxidation, with CYP26A1 exhibiting the greatest dynamic change. All rats were housed in a room maintained at 22°C with a 12-h dark:light cycle, and food and water were freely available. For the Steady-State Vitamin A Study (experiment 1) and the Retinoic Acid 16-hour Kinetic Study (experiment 2), lactating female Sprague-Dawley rats with 12 female pups (purchased from Charles River Laboratories, Willmington, MA) were fed a vitamin A-deficient purified diet [AIN-93G diet, prepared by Research Diets, New Brunswick, NJ] to reduce the transfer of vitamin A in milk from mother to pups prior to the start of the study. For experiment 1, from weaning, the offspring were fed the same diet modified to contain vitamin A at one of four levels: 0 (vitamin A deficient), 0.4 mg retinol/kg diet (vitamin A marginal), 4 mg retinol/kg diet (vitamin A adequate control), or 100 mg retinol/kg diet (vitamin A supplemented). All rats were studied at 8 weeks of age. Rats were euthanized by carbon dioxide asphyxiation and blood and liver were collected rapidly and frozen in liquid nitrogen for storage at -80°C before analysis. In experiment 2, at 8 weeks of age female vitamin A-deficient rats were treated with ~100 ug of All-trans-Retinoic acid (at-RA) for 0 (vehicle only), 3, 6, 10 or 16 h (n=3-4/group). Tissues were collected and RNA was prepared in the same manner as in experiment 1. In the 90-minute "first pass" kinetic study (experiment 3), female rats were purchased at 6 weeks of age and fed a stock rodent diet. When the rats were 8 weeks old they were assigned to a control (naïve) group. Rats in the naive group received an equal amount of vehicle only (vegetable oil/5% ethanol). Food was removed immediately. Sixteen hours after priming, each rat was lightly anesthetized by isoflurane-oxygen inhalation and treated with ~25 ug all-trans-RA bound to albumin [10 ug RA per 100 g bo dy weight], injected into the exposed left common iliac vein. The incision was closed with a surgical staple. The rats were allowed to recover from the anesthesia. Rats were killed at 0 minute (vehicle injection), and 30, 60, and 90 min (n = 3/group) after injection of the RA test dose. Rats were euthanized by carbon dioxide asphyxiation and blood and liver were collected rapidly and frozen in liquid nitrogen for storage at -80°C before analysis. For experiment 1, five biological repeats were Vitamin A deficient, seven biological repeats were Vitamin A marginal, six biological repeats were Vitamin A adequate, and two biological repeats were Vitamin A supplemented. In experiment 2, three biological repeats were performed for each of the following treatments: untreated, at-RA for 3 hours, at-RA for 6 hours and at-RA for 16 hours. Four biological repeats were treated with at-RA for 10 hours. For experiment 3, two biological repeats were untreated and three biological repeats were performed for each of the following at-RA treatment times: 30, 60 and 90 minutes. A total of 47 samples were analyzed.

Project description:Gene expression along the crypt-villus (C-V) axis was analyzed using cryostat sectioning to isolate fractions representing the crypts (bottom) and villus tops (top). These fractions were used for analyzing gene expression in iron replete Wistar rats (++), iron deficient Wistar rats (low iron), and in iron deficient Wistar rats fed iron for 3 and 6 days (iron-fed). Differences were observed between the crypts and villus tops in the expression of genes associated with Wnt and BNP signaling, cell proliferation and apoptosis, lipid and iron transport and metabolism. Gene expression in villus crypts and tops was also compared between Wistar and Belgrade rats (bb) and Belgrade rats fed iron (iron-fed) particularly as related to iron absorption and metabolism to define the affects of the mutation in DMT1 in the Belgrade rat on the expression of genes related to iron absorption and metabolism and the response to iron feeding. Keywords: iron stress response A colony of Wistar strain rats (++) and Belgrade (bb) rats on a Wistar background maintained in our animal quarters was used for this study. Twelve one-month old ++ rats were separated into 3 groups of four rats each. Group 1 rats (samples 1-8) were fed a normal diet and served as control animals. Group 2 (samples 9-16) and Group 3 rats (samples 17-22) were fed a low iron diet and bled 2-3 ml every three days for 4 weeks and served as iron deficient rats (low-iron). Group 3 rats, of which one rat died during anesthesia while undergoing phlebotomy, were fed iron supplementation in drinking water (50 ÂµM Ferric ammonium citrate) for the three days before sacrifice (iron-fed). Rats were fasted overnight, killed by injection of pentobarbital sodium and a 1-cm duodenal segment 1 cm distal from the pylorus was cryostat sectioned at the right angle to the crypt-villus axis and the sections representing the top one-third of villus (top) and the bottom one-third of the villus were pooled for RNA isolation. For the study of Belgrade rats, eleven bb rats were divided into 3 groups with the 4 rats in Group 1 (samples 23-30) maintained on a normal diet, the 4 rats in Group 2 (samples 31-38) fed iron for 3 days prior to sacrifice, and the 3 rats in Group 3 (samples 39-44) fed iron for 6 days prior to sacrifice. All procedures for the bb rats were the same as described above for the ++ rats. An additional ++ rat (samples 45-46) was similarly analyzed in a separate experiment.

Project description:Weanling rats fed a choline-deficient diet develop acute renal failure (ARF) after 6-7 days of receiving the experimental diet. Its pathogenesis is controversial. Menhaden oil has a protective effect in this experimental model. The aim of this study is to describe both the genetic profile and its changes when vegetable oils are replaced by menhaden oil. Wistar, weanling rats from the Animal Facility of the Centre of Experimental and Applied Pathology were divided into 4 groups and fed with the following diets: 1- Choline-deficient diet with vegetable oils as lipids (corn and hydrogenated oils); 2- Choline-supplemented diet with vegetable oils as lipids; 3- Choline-deficient diet with menhaden oil as lipid; and 4- Choline supplemented diet with menhaden oil as lipid. Animals were sacrificed after 6 days of receiving the experimental diets. The right kidney was cryopreserved. In this assay biological duplicated samples were used. In order to evaluate changes in gene expression WT Expression Kit (Ambion, USA) over the platform GeneChip® Gene 1.0 ST Rat Genome Array (Affymetrix Inc, USA) was used. Fluorescent distribution in the array was obtained using the language R (www-r-project.org), in house own algorithms and other formsbioconductor tools http://www.bioconductor.org/. We analyzed the differential gene expression, using as cut value p<0.01 with fdr control & |log FC|>1.5, in all groups. Rats fed with diets 2, 3 and 4 have similar genetic profiles. However, the comparison between rats fed with diets 2 and 4 showed 35 genes with diferential expression. As these rats did not have renal necrosis, we can hypothesize that the differential expression is due to the menhaden oil of the diet. In short, the massive analysis of genetic expression allowed to confirm that menhaden oil has a protective effect in this experimental model and to identify 35 genes that could be responsible of that protection. Twenty eight animals were sacrificed after 6 days of receiving the experimental diets. The right kidney was cryopreserved for microarray analysis. Cryopreserved kidney was pulverized under liquid-nitrogen conditions. Total RNA was purified from 30 mg of frozen rat kidney tissue. Each sample represents a pool of 3 animals (except CD+AM SN with 2 animals/pool), to reduce biological variation. In this assay biological duplicated samples were used.

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MiRNA_Taccioli_31_2013_Nat

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