Effects of dietary polyunsaturated fatty acid supplementation in early renal insufficiency in dogs

Effect of chronic fish oil supplementation on renal function of normal and cachectic rats

In the present study we determined the effect of chronic diet supplementation with n-3 PUFA on renal function of healthy and cachectic subjects by providing fish oil (1 g/kg body weight) to female rats throughout pregnancy and lactation and then to their offspring post-weaning and examined its effect on renal function parameters during their adulthood. The animals were divided into four groups of 5-10 rats in each group: control, control supplemented with fish oil (P), cachectic Walker 256 tumor-bearing (W), and W supplemented with fish oil (WP). Food intake was significantly lower in the W group compared to control (12.66 +/- 4.24 vs 25.30 +/- 1.07 g/day). Treatment with fish oil significantly reversed this reduction (22.70 +/- 2.94 g/day). Tumor growth rate was markedly reduced in the P group (16.41 +/- 2.09 for WP vs 24.06 +/- 2.64 g for W). WP group showed a significant increase in mean glomerular filtration rate compared to P and control (1.520 +/- 0.214 ml min-1 kg body weight-1; P < 0.05). Tumor-bearing groups had low urine osmolality compared to control rats. The fractional sodium excretion decreased in the W group compared to control (0.43 +/- 0.16 vs 2.99 +/- 0.87%; P < 0.05), and partially recovered in the WP group (0.90 +/- 0.20%). In summary, the chronic supplementation with fish oil used in this study increased the amount of fat in the diet by only 0.1%, but caused remarkable changes in tumor growth rate and cachexia, also showing a renoprotective function.

Effects of chronic high fat diets on renal function and cortical structure in rats

Four groups (n = 5) of male Wistar rats were fed with different high-fat diets from 21 days to 18-mo-old: soybean oil (SO), canola oil (CA), lard and egg yolk (LE) or CA+LE. Blood lipids, serum creatinine and proteinuria as well as the cortical stereology were analyzed. The cholesterol, HDL-C and triglycerides were highest in CA group. No significant differences were found among the groups to serum creatinine and proteinuria. The BP was highest in LE group and intermediate in CA+LE group. SO and CA groups showed glomeruli most preserved in number and size. Absolute volume of tubuli was greatest in LE group. Renal cortical interstitium was greatest in SO group and smallest in CA group. Cortical vessels showed smallest indices in LE group and greatest ones in CA group; SO and CA+LE groups were intermediate. Chronic administration of different types of dietetic lipid can significantly alter blood biochemistry, BP and renal cortical structure in rats. Considering these features, canola oil was the more beneficial lipid, while lard and egg yolk mixture was the worst lipid. The addition of canola oil in the LE mixture normally was not efficient to alter the renal damage except in the cortical vessels.

Functional foods and the urinary tract

There is no universally accepted definition of a commonly used term for a functional food: nutraceutical. For the purposes of this article, a nutraceutical is any ingredient found in foods that has a demonstrated (or proposed) physiologic benefit. Although a nutraceutical is generally taken to be an ingredient that can be isolated or purified from food, plants, or marine products and made available in medicinal form, this article also considers claims of benefit to the urinary tract for foods or food supplements in which the active ingredient has not yet been characterized or isolated.

Creatinine in the Dog: A Review

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.

Aorta wall quantitative alterations due to different long-term high-fat diet in rats

Twenty Wistar male rats, with ages varying from 21 days to 12 months, were fed with diets supplemented by soybean oil (S group), canola oil (CA group), lard and egg yolk (LE group), and canola plus lard and egg yolk (CA+LE group). The LE group presented the highest heart mass/body mass ratio and the highest blood pressure as well. The aortic structure suffered a number of alterations, from CA rats group (minor alterations) to LE and CA+LE rats group (major alterations). The CA group showed the smallest aorta thickness. No significant differences among groups were found concerning the number of aortic lamellae and the density of tunica media smooth muscle nuclei. Surface density of the aortic lamellae was greater in the CA group and smaller in the LE group. These results suggest that the dietary intake of canola oil could attenuate the aorta structure aging process with a favorable BP maintenance.

Detrimental effects of a high fat diet in early renal injury are ameliorated by fish oil in Han:SPRD-cy rats

Dietary fish oils containing (n-3) fatty acids can modulate renal inflammatory injury. We previously demonstrated that a high fat (HF) diet worsens early renal disease progression in the Han:SPRD-cy rat model of polycystic kidney disease (PKD). Therefore, using HF (20 g/100 g diet) and low fat (LF; 5 g/100 g diet) diets, we compared the effects of menhaden oil (MO), soybean oil (SO) and cottonseed oil (CO) on renal function and histology in male Han:SPRD-cy rats fed the diets for 6 wk in the early stages of renal disease. Overall, rats fed HF compared with those fed LF diets had larger kidneys, more renal fibrosis and lower creatinine clearance (main effects of fat level). Rats fed MO rather than CO and SO diets had significantly lower kidney weights, kidney water content, cyst volumes and serum cholesterol and triglyceride concentrations (main effects of fat type). Rats fed MO diets also had less renal fibrosis than those fed CO diets, but the least fibrosis was in rats fed SO diets. Analysis of simple effects (due to interactions between fat level and type) revealed that HF diets increased renal inflammation in rats fed CO diets, but reduced inflammation was present in those fed SO and MO diets; HF diets also increased compared with LF diets serum urea nitrogen concentrations in rats fed the MO and CO diets, but not the SO diet. These results confirm that high dietary fat worsens early disease progression in this model of renal disease, and further demonstrate that diets with oils containing (n-3) fatty acids ameliorate some of the detrimental effects of a high fat diet.