Resistance wheel exercise from mid-life has minimal effect on sciatic nerves from old mice in which sarcopenia was prevented.

Abstract

The ability of resistance exercise, initiated from mid-life, to prevent age-related changes in old sciatic nerves, was investigated in male and female C57BL/6J mice. Aging is associated with cellular changes in old sciatic nerves and also loss of skeletal muscle mass and function (sarcopenia). Mature adult mice aged 15months (M) were subjected to increasing voluntary resistance wheel exercise (RWE) over a period of 8M until 23M of age. This prevented sarcopenia in the old 23M aged male and female mice. Nerves of control sedentary (SED) males at 3, 15 and 23M of age, showed a decrease in the myelinated axon numbers at 15 and 23M, a decreased g-ratio and a significantly increased proportion of myelinated nerves containing electron-dense aggregates at 23M. Myelinated axon and nerve diameter, and axonal area, were increased at 15M compared with 3 and 23M. Exercise increased myelinated nerve profiles containing aggregates at 23M. S100 protein, detected with immunoblotting was increased in sciatic nerves of 23M old SED females, but not males, compared with 15M, with no effect of exercise. Other neuronal proteins showed no significant alterations with age, gender or exercise. Overall the RWE had no cellular impact on the aging nerves, apart from an increased number of old nerves containing aggregates. Thus the relationship between cellular changes in aging nerves, and their sustained capacity for stimulation of old skeletal muscles to help maintain healthy muscle mass in response to exercise remains unclear.