DECLINE OF TASTE SENSITIVITY IN PROTEIN-DEFICIENT ADULT-RATS

The influence of dietary protein levels on taste sensitivity was studi ed in adult rats. Low protein diets of 0.0, 2.5, or 5.0% purified egg protein (PEP) were fed to animals for 28 days. Two bottle choice prefe rence tests between aqueous solutions of either 2, 9, 17, or 86 mM sod ium chloride and deionized water were conducted in an ascending order on days 14, 16, 18, and 20. Urine samples were collected for zinc and creatinine analysis. Blood samples were also collected for measuring s erum zinc and creatinine concentrations. Scanning electron microscopy was performed to observe rats' tongue epithelia. Protein free diet gro up showed significantly lower taste sensitivity and renal reabsorption rate than other protein containing diet groups, while serum zinc and creatinine concentrations, and creatinine clearance were not affected by dietary protein level. Degeneration of filiform papillae and imperf oration of taste pore of fungiform papillae were observed in protein f ree diet group. This experiment implies at least 2.5% dietary protein is required to manifest normal taste function in the adult.