Physical Exercise Retards the Development of Chronic Nephropathy in the Ageing Rat as Efficiently as Food Restriction Does

Background: Obesity combined with decreasing physical fitness in the ageing Western populations promotes a number of degenerative diseases, including chronic kidney disease. It has further been shown in rodent models that prevention of obesity by food restriction mitigates development of kidney lesions. Whether lifelong physical activity also has a positive effect is not known. Objective: To compare the effects of physical exercise and food restriction on the development of chronic kidney lesions in ageing rats. Methods: Male Sprague-Dawley rats were divided into groups: voluntarily running in wheels (RW), food restriction to the degree necessary to attain pair weight to RW rats (PW), forced running in treadmills (TM) and sedentary controls housed individually (S1) or 4 in each cage (S4). The interventions began at the age of 5 months and kidneys were sampled and analysed histologically at the ages of 15, 19 and 23 months. Results: Total score for kidney lesions (sum of the scores for glomerular changes, interstitial non-purulent inflammation, proteinaceous casts in tubules and increased amount of connective tissue, the possible maximum being 10.0) increased from 0.5 ± 0.2 at 5 months of age to 1.6 ± 0.3 for RW, 2.3 ± 0.4 for PW, 4.5 ± 0.4 for TM, 3.6 ± 0.5 for S1 and 5.4 ± 0.6 for S4 at the age of 23 months. The increase from 5 months of age was gradual for all groups through 15, 19 and 23 months. The patterns for the various lesions followed the same pattern with the exception of connective tissue, which did not increase. Conclusion: Voluntary running in wheels is as effective in mitigating kidney lesions as is food restriction, while forced running in a treadmill is not effective in this respect.