Ana Uceda

Effect of dietary choline deficiency on immunocompetence in Wistar rats

In order to study the effect of dietary choline deficiency on immunity, adult Wistar rats were fed for two months with choline supplemented (CS, 0.35% choline chloride) or deficient (CD) diets and different parameters of immune response against sheep blood red cells or ovoalbumin (OVA) were evaluated. We found a significant reduction of haemagglutinating (HA) antibodies in sera (day 5 post-immunization: CD, 110 ± 12 HAU vs. CS 320 ± 40 HAU, p < 0.05) and only a slight difference in anti-OVA antibodies in CD group. Delayed type hypersensitivity was significantly impaired in CD group (footpad swelling in mm: CD, 0.97 ± 0.51 vs. CS, 2.32 ± 0.53, p < 0.05). In vitro, concanavalin A (Con A) stimulated proliferation of lymphocytes from spleen or lymph nodes of CD rats were diminished to 1:3 of control values while no difference was observed when lipopolisaccharide (LPS) was used as stimulus. So, we can conclude that choline dietary deficiency affects immune response in rats reducing host response to antigens.

Losartan prevents the imbalance between renal dopaminergic and renin angiotensin systems induced by fructose overload. l-Dopa/dopamine index as new potential biomarker of renal dysfunction

BACKGROUND The renin angiotensin system (RAS) and the renal dopaminergic system (RDS) act as autocrine and paracrine systems to regulate renal sodium management and inflammation and their alterations have been associated to hypertension and renal damage. Nearly 30-50% of hypertensive patients have insulin resistance (IR), with a strong correlation between hyperinsulinemia and microalbuminuria. OBJECTIVE The aim of this study was to demonstrate the existence of an imbalance between RAS and RDS associated to IR, hypertension and kidney damage induced by fructose overload (FO), as well as to establish their prevention, by pharmacological inhibition of RAS with losartan. MATERIALS/METHODS Ninety-six male Sprague-Dawley rats were randomly divided into four groups and studied at 4, 8 and 12 weeks: control group (C4, C8 and C12; tap water to drink); fructose-overloaded group (F4, F8 and F12; 10% w/v fructose solution to drink); losartan-treated control (L) group (L4, L8 and L12; losartan 30 mg/kg/day, in drinking water); and fructose-overloaded plus losartan group (F + L4, F + L8 and F + L12, in fructose solution). RESULTS FO induced metabolic and hemodynamic alterations as well as an imbalance between RAS and RDS, characterized by increased renal angiotensin II levels and AT1R overexpression, reduced urinary excretion of dopamine, increased excretion of l-dopa (increased l-dopa/dopamine index) and down-regulation of D1R and tubular dopamine transporters OCT-2, OCT-N1 and total OCTNs. This imbalance was accompanied by an overexpression of renal tubular Na+, K+-ATPase, pro-inflammatory (NF-kB, TNF-α, IL-6) and pro-fibrotic (TGF-β1 and collagen) markers and by renal damage (microalbuminuria and reduced nephrin expression). Losartan prevented the metabolic and hemodynamic alterations induced by FO from week 4. Increased urinary l-dopa/dopamine index and decreased D1R renal expression associated to FO were also prevented by losartan since week 4. The same pattern was observed for renal expression of OCTs/OCTNs, Na+, K+-ATPase, pro-inflammatory and pro-fibrotic markers from week 8. The appearance of microalbuminuria and reduced nephrin expression was prevented by losartan at week 12. CONCLUSION The results of this study provide new insight regarding the mechanisms by which a pro-hypertensive and pro-inflammatory system, such as RAS, downregulates another anti-hypertensive and anti-inflammatory system such as RDS. Additionally, we propose the use of l-dopa/dopamine index as a biochemical marker of renal dysfunction in conditions characterized by sodium retention, IR and/or hypertension, and as a predictor of response to treatment and follow-up of these processes.

Nitric oxide and AQP2 in hypothyroid rats: A link between aging and water homeostasis

OBJECTIVE Hypothyroid state and aging are associated with impairment in water reabsorption and changes in aquaporin water channel type 2 (AQP2). Nitric oxide (NO) is involved in AQP2 trafficking to the apical plasma membrane in medullary collecting duct cells. The purpose of this study was to investigate whether aging and hypothyroidism alter renal function, and whether medullary NO and AQP2 are implicated in maintaining water homeostasis. MATERIALS/METHODS Sprague-Dawley rats aged 2 and 18months old were treated with 0.02% methimazole (w/v) during 28days. Renal function was examined and NO synthase (NOS) activity ([(14)C (U)]-L-arginine to [(14)C (U)]-L-citrulline assays), NOS, caveolin-1 and -3 and AQP2 protein levels were determined in medullary tissue (Western blot). Plasma membrane fraction and intracellular vesicle fraction of AQP2 were evaluated by Western blot and immunohistochemistry. RESULTS A divergent response was observed in hypothyroid rats: while young rats exhibited polyuria with decreased medullary NOS activity, adult rats exhibited a decrease in urine output with increased NOS activity. AQP2 was increased with hypothyroidism, but while young rats exhibited increased AQP2 in plasma membrane, adult rats did so in the cytosolic site. CONCLUSIONS Hypothyroidism contributes in a differential way to aging-induced changes in renal function, and medullary NO and AQP2 would be implicated in maintaining water homeostasis.

Menhaden Oil Rich Diet and Experimental Renal Damage Due to Ischemia Reperfusion

Renal necrosis can be induced in weanling rats due to choline deficient diet. Menhaden oil has a protective effect against the development of renal necrosis in choline deficient weanling rats. The aim of this work was to determine the effects of menhaden oil in a model of acute kidney injury due to ischemia reperfusion. Wistar rats were divided into two groups and fed vegetable oils or menhaden oil as lipids. Unilateral renal ischemia was performed for 30 minutes and animals were sacrificed 48 hours later. Histopathological examination showed no significant differences between groups. Menhaden oil did not prevent histopathological lesions.

Characterization of placental and fetal development in an animal model of severe arterial hypertension

The objective was to determine the maternal and fetal levels of ICAM-1,VCAM-1, E-Selectin and P-Selectin endothelial cell adhesion molecules in Pre-Eclampsia (PE) and Eclampsia (E) in relation to normal pregnancy.Peripheral maternal plasma were collected from normal pregnant (n1⁄440), PE (n1⁄433) and E (n1⁄413).Fetal plasma samples from the umbilical vein of the corresponding fetuses were collected at delivery. A sandwich ELISA technique was employed to quantitate the concentration of soluble molecules.The concentrations of ICAM-1,VCAM-1 and E-Selectin were significantly elevated in PE and E when compared to normal pregnancy. The fetal concentrations of these molecules were markedly different from the corresponding maternal values. However, there was no difference in the fetal concentration of these molecules between normal pregnancy and the other groups. P-Selectin in maternal blood correlated with platelet count and with P-Selectin of the fetal blood. Conclusion: PE and E showed signs of endothelial cell dysfunction manifested by the increased endothelial cell adhesive molecules. The fetal circulation may not be affected by the factor(s) that may lead to disturbed endothelial cell function in PE or E. P-Selectin seems not to be involved in these conditions suggesting a selective dysregulation of some molecules rather than damage of the endothelial cells.

Short-term menhaden oil rich diet changes renal lipid profile in acute kidney injury.

Weanling male Wistar rats fed a choline-deficient diet develop acute kidney injury. Menhaden oil, which is a very important source of omega-3 fatty acids, has a notorious protective effect. The mechanism of this protection is unknown; one possibility could be that menhaden oil changes renal lipid profile, with an impact on the functions of biological membranes. The aim of this work was to study the renal lipid profile in rats fed a choline-deficient diet with menhaden oil or vegetable oil as lipids. Rats were divided into 4 groups and fed four different diets for 7 days: choline-deficient or choline-supplemented diets with corn and hydrogenated oils or menhaden oil. Serum homocysteine, vitamin B12, and folic acid were analyzed. Renal lipid profile, as well as the fatty acid composition of the three oils, was measured. Choline-deficient rats fed vegetable oils showed renal cortical necrosis. Renal omega-6 fatty acids were higher in rats fed a cholinedeficient diet and a choline-supplemented diet with vegetable oils, while renal omega-3 fatty acids were higher in rats fed a choline-deficient diet and a choline-supplemented diet with menhaden oil. Rats fed menhaden oil diets had higher levels of renal eicosapentaenoic and docosahexaenoic acids. Renal myristic acid was increased in rats fed menhaden oil. The lipid renal profile varied quickly according to the type of oil present in the diet.