Project description:Iron is an essential nutritional element; its deficiency in the body causes nutritional problems and a decrease in iron storage that can lead to anemia. The liver not only stores iron but is an important metabolic target as well. Dietary iron deficiency is associated with changes in the metabolism of nutrients such as lipids. However, to the best of our knowledge, a global analysis detailing the consequences of iron deficiency in the body has not yet been reported. We performed a comprehensive transcriptome analysis using DNA microarray technology to reveal the effects of iron deficiency on hepatic gene expression. Four-week-old rats were fed an iron-deficient diet or a control diet for 16 days. On day 17, the rats were sacrificed under anesthesia, and their livers were dissected for DNA microarray analysis. We identified 600 up-regulated and 500 down-regulated probe sets to characterize the iron-deficient diet group. The up-regulated probe sets contained genes for enzymes that are involved in cholesterol, amino acid, and glucose metabolisms, as well as in apoptosis. The down-regulated probe sets included genes for enzymes associated with lipid metabolism. Additionally, the 16-day iron-deficient diet induced anemia. Our gene expression analysis revealed that, as a result, cholesterol biosynthesis, gluconeogenesis, and apoptosis due to endoplasmic reticulum stress were accelerated, while fatty acid biosynthesis was suppressed by dietary iron deficiency. Our analysis also showed that cholesterol metabolism, including bile acid biosynthesis, was accelerated in the initial stages of cholesterol accumulation. Experiment Overall Design: Male 3-week-old Sprague Dawley rats were purchased from Charles River Japan (Kanagawa, Japan) and housed in a room conditioned at 24 Â± 1Â°C and 40 Â± 5% humidity with a 12-h light-dark cycle (lights on at 08:00). The rats were given a control diet and water for 24 h ad libitum. Diets for rats were obtained from Research Diets, Inc. (New Brunswick, NJ, USA). The composition of the control diet was based on the AIN93G diet , except that cellulose was replaced by Avicel, since cellulose is an ingredient of variable iron content. The iron-deficient diet was prepared by removal of iron (ferric citrate) from the control diet. At day 8, rats were divided into two groups comprising animals of similar body weights. One group (n = 6) was fed the control diet and the other group (n = 7) was fed the iron-deficient diet (iron-deficient diet group). After iron-deficient diet feeding was started, blood hemoglobin levels were measured every two days. Blood samples for hemoglobin measurements were collected from the tail vein, and hemoglobin levels were measured by using the Wako Hemoglobin B test (Wako Pure Chemical Industries, Osaka, Japan). On day 12 of the iron-deficient diet treatment, diets were removed at 17:00, and feeding was conducted between 09:00 and 17:00 for another 4 days. This protocol was intended to synchronize the ratsâ feeding behavior. On day 17 of the iron-deficient diet treatment, rats were fed for 1.5 h prior to sacrifice under anesthesia. Livers were then excised and subsequently immersed in RNAlater (Applied Biosystems Japan, Tokyo, Japan). Blood hemoglobin level of rats fed an iron-deficient diet decreased significantly over the course of the feeding. On day 17, the hemoglobin level in the iron-deficient diet group was 42% of that of the control diet group (P < 0.01).

Project description:Iron deficiency-induced anemia is generally a representative nutritional problem in most populations. We reported that the anemia due to dietary iron deficiency causes a variety of changes in nutrient metabolism, even leading to apoptosis as a result of associated endoplasmic reticulum (ER) stress in the rat liver. On the other hand, it appears that non-anemic iron-deficiency causes no serious problem because no appreciable down-regulation of hemoglobin synthesis occurs. Biochemically, iron is essential for activation of cytochrome-related enzymes and its deficiency should yield some physiological problems. We performed a comprehensive transcriptome analysis to define the effects of non-anemic iron deficiency on hepatic gene expression. Four-week-old rats were fed a low-iron diet (ca. 3 ppm iron) for 2 days. These rats were compared with those fed a control diet (48 ppm iron) by pair feeding. On day 3, the rats were sacrificed under anesthesia, and their livers were dissected for DNA microarray analysis. Rats in the iron-deficient diet group, showed that their serum ferritin and iron levels decreased with an increase in the serum total iron binding capacity (TIBC) level, while the hemoglobin level was not changed. In the DNA microarray study, we identified 91 up-regulated and 186 down-regulated probe sets that characterized the iron-deficient diet group. In the up-regulated probe sets, genes involved in glucose and lipid metabolic processes were significantly enriched, whereas genes related to organic acid metabolic process, cellular ketone metabolic process, lipid metabolic process, oxidation reduction, response to drug, response to extracellular stimulus and gas transport were significantly enriched in the down-regulated probe sets. These results suggest that even the non-anemic iron-deficiency exerts various influences on nutrient metabolisms in the liver. Three-week-old male rats (Sprague Dawley) were purchased from Charles River Japan (Kanagawa, Japan) and housed in a room maintained at 24 M-BM-1 1M-BM-0C and 40 M-BM-1 5% humidity with a 12-h light/dark cycle (light 08:00M-bM-^@M-^S20:00; dark 20:00M-bM-^@M-^S08:00). Rats were given a normal diet (Research Diets, Inc., New Brunswick, NJ, USA) as control and water for 24 h ad libitum. The composition of the control diet, 48 ppm iron, was based on the AIN-93G diet; Avicel was used in place of cellulose which may contain a trace amount of iron. On day 3, diet was removed at 18:00 and the feeding was conducted between 09:00 and 17:00 for another 4 days to synchronize the feeding behaviors. On day 8, rats were divided into two groups with similar average body weights. Rats in the one group (n = 5) were given ad libitum an iron-deficient diet, ca. 3 ppm iron, that was prepared by removal of iron (ferric citrate) from the control diet, and those in the other group (n = 5) were fed the control diet by pair feeding. On day 1 and day 3 of feeding with the experiment diet, the hemoglobin level of each rat was measured for the blood samples collected from the tail vein. On day 3, each rat was sacrificed under anesthesia after 1.5 h feeding, prior to excising the liver which was soon immersed in RNAlater.

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.

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