Grip strength is potentially an early indicator of age-related decline in mice

Abstract

The hand grip test has been correlated with mobility and physical performance in older people and has been shown to be a long-term predictor of mortality. Implementation of new strategies for enhancing healthy aging and maintaining independent living are dependent on predictable preclinical studies. The mouse is used extensively as a model in these types of studies, and the paw grip strength test is similar to the hand grip test for people in that it assesses the ability to grip a device with the paw, is non-invasive and easy to perform, and provides reproducible information. However, little has been reported on how grip strength declines with increasing age in mice. This report shows that grip strength was decreased in C57BL/6 (B6) NIA and C57BL/6×BALB/c F1 (CB6F1) NIA male mice at 12 months of age compared to 8-month-old mice, and continued a robust decline to 20 months and then 28 months of age, when the study was terminated. The decline was not related to lean muscle mass, but extensive age-related carpal and digital exostosis could help explain the decreased grip strength times with increasing age. In conclusion, the grip strength test could be useful in mouse preclinical studies to help make translational predictions on treatment strategies to enhance healthy aging.

Keywords: aging; arthropathy; grip strength; mice.

Fig. 1

(a) B6 mouse paw strength declined from 121.8±18.5 to 106.2±15.1 to 92.1±15.7 to 88.6±10.9 from ages 4, 12, 20, and 28 months, respectively. Following the same pattern, CB6F1 mouse grip strength declined from 119.2±12.3 to 105.0±15.7 to 93.2±14.0 to 87.9±16.0 through the four age groups. (b) B6 mice had average masses of 31.75±2.1, 33.19±2.19, 33.40±3.73, and 35.60±7.59 g at the 4, 12, 20, and 28 months of age, respectively. CB6F1 mice had increased body weights in the 12- and 20-month age groups compared to 4- and 28-month age groups. The B6 mice had mean masses of 38.57±3.24, 42.93±3.29, 43.19±3.27, and 39.09±2.54 g at 4, 12, 20, and 28 months of age, respectively. Strain, age groups, and the interaction between strain and age were all significant (p<0.001, p=0.001, p=0.001, respectively).

Fig. 2

(a) B6 mice at 4, 12, 20, and 28 months of age had mean lean mass percentages of 79.0±1.4, 77.0±2.1, 78.8±2.4, and 79.4±2.0, respectively. CB6F1 mice at 4, 12, 20, and 28 months of age had mean lean mass percentages of 75.8±2.1, 70.2±3.8, 69.7±5.2, and 74.1±4.7, respectively. (b) B6 mice at 4, 12 20, and 28 months of age had mean percent fat masses of 11.1±1.6, 14.1±1.8, 12.7±2.4, and 11.8±2.1, respectively. CB6F1 mice at 4, 12, 20, and 28 months of age had mean percent fat masses of 16.3±1.7, 21.9±3.3, 21.6±5.2, and 17.3±5.7, respectively.

Fig. 3

Exostosis is a significant lesion seen with increasing age in carpal bones of mice. (a) Severe exostosis in a CB6F1 mouse in the oldest age cohort (28 months). (b) Absence of exostosis in a CB6F1 mouse in the youngest age cohort (4 months).