THE EFFECTS OF OVERFEEDING AND DIETARY RESTRICTION ON SPRAGUE-DAWLEY RAT SURVIVAL AND EARLY PATHOLOGY BIOMARKERS OF AGING

A significant correlation exists between average daily food consumptio n and 2-yr survival in control ad libitum (AL)-fed Sprague-Dawley (SD) rats. SD rats were fed Purina Rodent Chow 5002 or a modified chow, 50 02-9, with lower protein, fat, metabolizable energy and increased fibe r AL or by dietary restriction (DR) to 65% of the AL amount by measure ment or time (6.5 hr). At 52 wk, food consumption and key pathology bi omarkers correlated with 106-wk survival. The modified chow, 5002-9 fe d AL, did not significantly improve survival. SD rats fed either diet AL consumed the greatest amount of feed and kcal/rat but consumed the same amount of feed per gram body weight as DR-fed rats. At 52 wk, AL rats fed either diet had the same brain weights as DR rats, but the AL -fed rats had greater body weight and body fat content and increased h eart, lung, kidney, liver, adrenal, thyroid, and pituitary weights as well as an increased incidence and severity of degenerative and/or pro liferative lesions in these organs. This study demonstrates that overf eeding best correlates with low 2-yr survival in SD rats and that simp le DR by caloric restriction modifies key pathology biomarkers in the pituitary, mammary gland, kidney, and heart of SD rats at 52 wk that a re predictive of 106-wk survival.