Effects of dietary lipids on renal function of aged rats

Male and Female Intrauterine Growth-Restricted Offspring Differ in Blood Pressure, Renal Function, and Glucose Homeostasis Responses to a Postnatal Diet High in Fat and Sugar

It is well established that inadequate nutrition during fetal life followed by postnatal overabundance programs adiposity and glucose intolerance. Studies addressing sexual dimorphism in developmental responses to a dietary mismatch are limited; the effect on blood pressure and renal function is understudied. Therefore, this study tested the hypothesis that a mismatch of prenatal and postnatal nutrition heightens cardiorenal and metabolic risk, outcomes that may vary by sex. Male and female offspring from sham-operated (control) or reduced uterine perfusion dams (growth restricted) were fed regular chow or a diet high in fat and sugar (enriched diet) from weaning until 6 months of age. Male and female offspring were assessed separately; 2-way ANOVA was used to investigate interactions between intrauterine growth-restricted and enriched-diet. Blood pressure was increased in all enriched-diet groups but did not differ in enriched-diet male or female growth-restricted versus same-sex control counterparts. Glomerular filtration rate was reduced in male growth-restricted regardless of diet; a decrease exacerbated by the enriched-diet suggesting the pathogenesis of increased blood pressure induced via an enriched-diet differs between male growth-restricted versus male control. An enriched diet was associated with glucose intolerance in male and female control but not male growth-restricted; the enriched diet exacerbated glucose intolerance in female growth-restricted. Thus, these findings indicate male growth-restricted are resistant to impaired glucose homeostasis, whereas female growth-restricted are susceptible to metabolic dysfunction regardless of postnatal diet. Hence, moderation of fat and sugar intake may be warranted in those born low birth weight to ensure minimal risk for chronic disease.

Age-related changes in urinary protein excretion in relation to indices of renal function in Wistar rats

BACKGROUND

The study determined the fractions of proteins in the urine and plasma of rats at different ages, measured the plasma and urine concentrations of markers of renal function, with a view to determining the influence of proteinuria on renal function.

METHODS

Eighty Wistar rats were used for this study. Groups 1 and 2 each consisted of eight 1-month-old male and female rats; 3 and 4 had eight 3-month-old male and female rats; 5 and 6 had eight 6-month-old male and female rats; 7 and 8 had eight 9-month old male and female rats; and 9 and 10 had eight 12-month-old male and female rats.

RESULTS

A fraction of the molecular weight of protein in the urine of rats aged 1, 9 and 12 months was higher than that of 3 and 6 months. The total protein concentration in the urine of male and female rats aged 9 and 12 months was significantly higher than that of rats aged 1 and 3 months. The urine creatinine concentrations of male and female rats aged 9 months were significantly higher when compared with that of 1, 3, 6 and 12 months.

CONCLUSION

Our results suggest that the 3-month-old rats seem less affected by proteinuria, because they had the least urine protein, and consistent and reduced plasma and urine concentrations of markers of renal function. The results of this study may provide a foundation for future mechanistic inquiries as to why this age group was the least affected by proteinuria.

Quantitative analysis of the renal aging in rats. Stereological study

PURPOSE

To evaluate the renal function and the renal histological alterations through the stereology and morphometrics in rats submitted to the natural process of aging.

METHODS

Seventy two Wistar rats, divided in six groups. Each group was sacrificed in a different age: 3, 6, 9, 12, 18 and 24 months. It was performed right nephrectomy, stereological and morphometric analysis of the renal tissue (renal volume and weight, density of volume (Vv[glom]) and numerical density (Nv[glom]) of the renal glomeruli and average glomerular volume (Vol[glom])) and also it was evaluated the renal function for the dosage of serum creatinine and urea.

RESULTS

There was significant decrease of the renal function in the oldest rats. The renal volume presented gradual increase during the development of the rats with the biggest values registered in the group of animals at 12 months of age and significant progressive decrease in older animals. Vv[glom] presented statistically significant gradual reduction between the groups and the Nv[glom] also decreased significantly.

CONCLUSIONS

The renal function proved to be inferior in senile rats when compared to the young rats. The morphometric and stereological analysis evidenced renal atrophy, gradual reduction of the volume density and numerical density of the renal glomeruli associated to the aging process.

Associations of dietary fat with albuminuria and kidney dysfunction

BACKGROUND

Diet represents a potentially important target for intervention in nephropathy, yet data on this topic are scarce.

OBJECTIVES

The objective was to investigate associations between dietary fats and early kidney disease.

DESIGN

We examined cross-sectional associations between dietary fats and the presence of high albuminuria (an established independent predictor of kidney function decline, cardiovascular disease, and mortality) or estimated glomerular filtration rate (eGFR) <60 mL ⋅ min(-1) ⋅ 1.73 m(-2) at baseline in 19,256 participants of the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study, an ongoing cohort study in US adults aged ≥45 y at time of enrollment. We used logistic regression to assess associations between quintiles of total fat and subtypes of dietary fat (saturated, monounsaturated, polyunsaturated, and trans fat) and presence of high albuminuria or eGFR <60 mL ⋅ min(-1) ⋅ 1.73 m(-2).

RESULTS

After multivariable adjustment, only saturated fat intake was significantly associated with high albuminuria [for quintile 5 compared with quintile 1, odds ratio (OR): 1.33; 95% CI: 1.07, 1.66; P for trend = 0.04]. No significant associations between any type of fat and eGFR <60 mL · min(-1) · 1.73 m(-2) were observed. ORs between the highest quintile of saturated fat and eGFR <60 mL · min(-1) · 1.73 m(-2) varied by race with a borderline significant interaction term (ORs: 1.24 in whites compared with 0.74 in blacks; P for interaction = 0.05) in multivariable-adjusted models, but no other associations were significantly modified by race or diabetes status.

CONCLUSION

Higher saturated fat intake is significantly associated with the presence of high albuminuria, but neither total nor other subtypes of dietary fat are associated with high albuminuria or eGFR <60 mL · min(-1) · 1.73 m(-2).

Associations of diet with albuminuria and kidney function decline

BACKGROUND AND OBJECTIVES

Sparse longitudinal data exist on how diet influences microalbuminuria and estimated GFR (eGFR) decline in people with well-preserved kidney function.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

Of the 3348 women participating in the Nurses' Health Study who had data on urinary albumin to creatinine ratio in 2000, 3296 also had data on eGFR change between 1989 and 2000. Cumulative average intake of nutrients over 14 years was derived from semiquantitative food frequency questionnaires answered in 1984, 1986, 1990, 1994, and 1998. Microalbuminuria presence and eGFR decline > or = 30% were the outcomes of interest.

RESULTS

Compared with the lowest quartile, the highest quartile of animal fat (odds ratio (OR): 1.72; 95% confidence interval (CI): 1.12 to 2.64) and two or more servings of red meat per week (OR: 1.51; 95% CI: 1.01 to 2.26) were directly associated with microalbuminuria. After adjustment for other nutrients individually associated with eGFR decline > or = 30%, only the highest quartile of sodium intake remained directly associated (OR: 1.52; 95% CI: 1.10 to 2.09), whereas beta-carotene appeared protective (OR: 0.62, 95% CI: 0.43 to 0.89). Results did not vary by diabetes status for microalbuminuria and eGFR outcomes or in those without hypertension at baseline for eGFR decline. No significant associations were seen for other types of protein, fat, vitamins, folate, fructose, or potassium.

CONCLUSIONS

Higher dietary intake of animal fat and two or more servings per week of red meat may increase risk for microalbuminuria. Lower sodium and higher beta-carotene intake may reduce risk for eGFR decline.

Renal cortex remodeling in streptozotocin-induced diabetic spontaneously hypertensive rats treated with olive oil, palm oil and fish oil from Menhaden

We studied the effects of edible oils intake on the renal cortical structure of streptozotocin-induced diabetic (Db) and non-diabetic spontaneously hypertensive rats (SHR). Male SHR divided into 5 groups were studied during 6 weeks: one non-diabetic SHR group and four diabetic SHR groups (three groups received by gavage olive, palm or fish oil). Kidneys were analyzed by light microscopy and stereology. Oils intake did not change the plasma glucose levels. The blood pressure (BP) was lower in SHR-Db than in SHR, but SHR-Db-fish oil showed the lowest BP. Creatinine clearance was different between diabetic SHR and non-diabetic SHR, but not between treated SHR-Db and untreated SHR-Db. The renal cortex showed scars surrounding obsolete glomeruli with inflammatory infiltrate mainly in untreated SHR-Db. The olive oil, palm oil and mainly fish oil intake retard the usual loss of glomeruli and attenuate the renal cortex adverse remodeling of Db and non-Db SHR.

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.