Diet supplemented either with dried chicory root or chicory inulin significantly influence kidney and liver mineral content and antioxidative capacity in growing pigs

According to the Regulation No. 1831/2003 of the European Parliament and European Union Council, the use of antibiotics as a dietary supplements has been prohibited. It seems that the administration of prebiotics, instead of antibiotics, into the pig's diet, may regulate the intestinal microbiota and has a long-term health-related impact on the host. Inulin-type fructans can stimulate mineral absorption from the gut. Additionally, it may regulate energy metabolism and activate enzymatic mechanisms preventing oxidative stress. The goal of the present study was to estimate the influence of dietary supplementation with dried chicory root or native chicory inulin on 1) liver histology; 2) liver and kidney lipid metabolism indices, activity of selected enzymes, concentration of macro- and micronutrients and heavy metals; 3) blood plasma, liver and kidney oxidative stress biomarkers and 4) blood plasma water-electrolyte homeostasis indices in growing pigs. The nutritional study was conducted on 24 piglets assigned to 3 dietary groups (n = 8): control (C) fed a basal diet and two experimental groups receiving basal diet supplemented with 2% of inulin (IN) either 4% of dried chicory root (CR). The animals were fed with a group-specific diets for 40 days and then subjected to euthanasia. Subsequently, blood, liver and kidney samples were harvested for further processing. In the control and experimental groups, no apparent morphological abnormalities in the liver tissues were seen. The percent of periodic acid Schiff positive glycogen liver cells was significantly lower in the CR group as compared to C and IN groups (P < 0.001). Chicory root supplementation improved blood plasma prooxidative-antioxidative balance - PAB (P < 0.001) and liver PAB (P < 0.01) and thiobarbituric acid reactive substances - thiobarbituric acid-reactive substances (P < 0.05). Feeding the CR diet increased calcium (P < 0.001) and potassium (P < 0.05) and decreased cadmium (P ≥ 0.05) content in the liver when compared to the C group. Administration of the CR and IN diets increased selenium (Se) and sodium concentrations, whereas decreased zinc content both in the liver (P < 0.01; P < 0.05 and P < 0.05, respectively) and in the kidney (P < 0.01; P < 0.001 and P < 0.001, respectively) of pigs. Additionally, a higher concentration of lead (P < 0.05) was observed in the kidney of pigs fed the CR diet. In conclusion, both dietary supplements had a potential to significantly improve the Se status and oxidoreductive homeostasis in growing pigs.

Aquaporin 2: Identification and analysis of expression in calves’ urine during their first month of life

Michałek, K., Dratwa-Chałupnik, A., Ciechanowicz, A. K. and Malinowski, E. 2014. Aquaporin 2: Identification and analysis of expression in calves’ urine during their first month of life. Can. J. Anim. Sci. 94: 653–659. Aquaporin 2 (AQP2) is a vasopressin-regulated water channel of the renal collecting duct and is excreted into urine. Renal excretion of AQP2 has been studied in humans, dogs, rats and mice. The aim of this study was to identify and analyze expression of AQP2 in calves’ urine. Short and controlled diarrhea was induced in the calves in order to determine any change in renal excretion of AQP2 and to evaluate a possible role of this channel in water balance during the neonatal period. For this purpose, an additional portion of lactose was administered to the calves with a milk replacer. The present work shows that after transient diarrhea associated with excessive supply of lactose in the diet, a significant increase in renal AQP2 excretion was reported in the first 3 wk of the calves’ lives. Renal excretion of this protein in the urine increased significantly despite the absence of changes in the concentration of vasopressin or the osmotic pressure of the blood plasma. The increase observed in the expression of the protein might be associated with the reduction of the total Ca2+ concentration in the blood plasma of calves. The results clearly indicate a different mechanism regulating urinary excretion of AQP2 in newborn calves, hitherto unknown. Although elevated renal excretion of AQP2 was observed, there was no increase in the osmolality of the urine in the calves tested.

Immunohistochemical identification of aquaporin 2 in the kidneys of young beef cattle

Aquaporin 2 (AQP2) is a small, integral tetrameric plasma membrane protein that is expressed in mammalian kidneys. The specific constitution of this protein and its selective permeability to water means that AQP2 plays an important role in hypertonic urine production. Immunolocalization of AQP2 has been studied in humans, monkeys, sheep, dogs, rabbits, rats, mice and adult cattle. We analyzed the expression of AQP2 in kidneys of 7-month-old Polish-Friesian var. black and white male calves. AQP2 was localized in the principal cells of collecting ducts in medullary rays penetrating the renal cortex and in the collecting ducts of renal medulla. AQP2 was expressed most strongly in the apical plasma membrane, but expression was observed also in the intracellular vesicles and basolateral plasma membrane. Our study provides new information concerning the immunolocalization of AQP2 in calf kidneys.