Effects of calorie restriction and exercise on mammary gland gene expression in C57BL/6 mice. Mus musculus

We performed a factorial experiment examining the effects of calorie restriction (CR) and exercise (EX) in mice. CR mice received 70% of calories but 100% of all other nutrients compared to AL mice. Food consumption, weight gain, and physical activity levels were recorded for 6 weeks. Diet and exercise treatments, both alone and in combination, had significant effects on body composition and levels of physical activity. Affymetrix oligo microarrays were used to determine global gene expression patterns in mammary gland total RNA. CR and EX had some overlapping but primarily unique effects on mammary gene expression, with CR affecting a much larger number of genes. The gene changes presented suggest that CR and EX influence mammary gland development and potentially carcinogenesis through distinct pathways. Keywords: 2 X 2 factorial mouse experiment; ad lib; calorie restriction; exercise; exercise + calorie restriction. Endpoints: body composition; bone density; gene expression in mammary gland Overall design: Female C57BL/6 mice (9 weeks old) were randomized into 4 experimental groups: 1) food consumed ad libitum (AL); 2) AL with access to running wheels (AL+EX); 3) 30% CR; and 4) 30% CR with access to running wheels (CR+EX). RNA samples from animal mammary glands were analysed by Affymetrix oligo-microarray platform, in particular 10 samples from AL group (control), 9 samples from AL+EX group, 9 samples from CR group and 9 samples from CR+EX group were analysed.