Semi-Purified Egg-White Protein (EWP) Diet Improves Nutritional Status and Maintains Adequate Blood Pressure in Dahl Salt-Sensitive (Dahl-SS) Rats

Standardized diets for laboratory rodents become increasingly important. Dietary imbalances can negatively impact experimental outcomes. Commercially available diets often include ingredients that cannot be experimentally manipulated and may not meet all nutritional and experimental requirements. Current growth and maintenance diets for experimental animals are regulated by the American Institute for Nutrition (AIN). In our laboratory, we developed a diet based on egg-white protein (EWP) using endogenous ingredients that are safe for experimental rats and can be experimentally manipulated according to AIN standards. Therefore, this study aims to test and validate the nutritional quality of the EWP diet for the Dahl-SS rat strain, which is known to be nutrient-sensitive and genetically predisposed to develop hypertension. 14 pairs of Dahl-SS rats (14 females and 14 males) were used for mating. The rats were randomly divided into two groups: 7 pairs were fed a commercial standard diet, and the other 7 pairs were fed an EWP diet. From here, 10 pregnant rats (5 from each group), 14 weeks of age, and 1 week of gestation, were selected for the study and were fed their respective diets. The offspring were weighed at birth and weaned at 4 weeks of age. Five pups were randomly selected from each group (standard diet group and EWP diet group) and continued with their mother’s respective diets for an additional 6 weeks. During the study they were subjected to Biological (clinical-behavioral status, metabolic analysis, relative organ-weight), Biochemical (mineral analysis, hemogram, protein analysis) and Physiological parameters analysis (Blood Pressure determination, enzymatic activity of Na<sup>+</sup> and Na/K<sup>+</sup> pump in renal cortex). To complete analysis of the different parameters, at 10 weeks, the rats were sacrificed by exsanguination via cardiac puncture under intraperitoneal anesthesia with thiopental sodium (20-25 mg/kg). Blood was collected in heparinized and centrifuged tubes at 3500 g for 10 minutes at 4°C. Plasma was separated and stored at -20°C until analysis. The kidneys, heart, spleen, and liver were collected and weighed. Dahl-SS rats fed the EWP diet showed normal behavioral, motor and metabolic values, faster and greater body weight gain, blood and urine biochemistry values within normal range, stable blood pressure, normal enzyme activity, and adequate kidney function in comparison to the rats fed the standard diet. According to the parameters assessed, it was possible to conclude that the EWP diet has proven to be a suitable option for supporting maintenance, growth, and blood pressure regulation in Dahl-SS rats.