Effects of adult onset mild calorie restriction on weight of reproductive organs, plasma  parameters and gene expression in male mice

Rocha, J S; Bonkowski, M S; Masternak, M M; França, L R; Bartke, A

p. 40-51

Effects of adult onset mild calorie restriction on weight of reproductive organs, plasma parameters and gene expression in male mice

Rocha, J SBonkowski, M SMasternak, M MFrança, L RBartke, A

Calorie restriction (CR) extends lifespan and delays onset of age - related diseases in vari ous organisms, even when started later in life. Despite benefits for health and lifespan, CRs negative impact on reproduct ion is documented in some animals. Studies employing approximately 40% CR detected a delay in sexual maturation and impairment of fertility, which were combined with extension of the reproductive period. In contrast, mild CR (10 - 20%) is apparently not dele terious to reproduction. Hence, we hypothesized that mild CR started at 8 months of age would prolong reproductive capabilities and improve health parameters of male mice. To test this hypothesis, we assessed the effects of 10 and 20% CR on reproductive or gan weights, selected plasma parameters and hepatic/testicular gene expression in normal male mice of heterogeneous genetic background. Starting at 8 months of age (adult), mice were assigned to 3 regimen groups: 10% CR (n = 8), 20% CR (n = 9) or ad libitu m (AL ; n = 8). Four months of CR were sufficient to reduce glycemia in a non - fasted protocol. Mild CR initiated in adulthood did not significantly impact final body weight, most of the analyze d plasma parameters or weight of androgen - dependent organs. More over, CR did not interfere with expression of the assessed testicular genes, or most of the hepatic genes, but it did cause an increas e in the levels of peroxisome proliferator - activated receptor gamma ( Pparg ) and mouse sulfo transferase ( mSTa ); and a decre ase in glucose - 6 - phosphatase - α ( G6pc ) mRNA, which might signify improvement of body condition. The important finding of our study was that a mild CR regimen, as low as 10 and 20%, was sufficient to impair glycemia in a non - fasted state, and also the levels of plasma IGF - 1 , corroborating the concept that mild CR has the potential for improv ing health and longevity, even when started later in life.(AU)