Latency to Leave an Elevated Platform, Activity in a Dark Chamber, and Weight in Aging Sprague-Dawley Rats

Abstract

Young adult, middle-aged, and old male Sprague-Dawley rats ( n = 42) were compared for differences in step-down latency and activity in a darkened chamber. Ad libitum weights also were recorded. Latencies to leave a step-down platform increased about 400% from 4 to 9 mo. and then stabilized, suggesting that performance in this apparatus, commonly used in memory research, is very sensitive to age changes in rats less than 1 yr. old. Activity in the darkened chamber continued to decrease linearly from young adulthood to senility. Thus decreases in activity with age follow differing slopes, depending upon the task. Ad libitum weights increased linearly from 5 to 22.5 mo. A possible methodological implication for between-age comparisons of learning ability motivated by food was noted.