Longitudinal muscle and myocellular changes in community-dwelling men over two decades of successful aging - The ULSAM cohort revisited

Abstract

Participants of the population-based Uppsala longitudinal study of adult men (ULSAM) cohort reaching more than 88 years of age (survivors, S) were investigated at age 70, 82, and 88-90 and compared at 70 years with non-survivors (NS) not reaching 82 years. Body composition, muscle mass and muscle histology were remarkably stable over 18 years of advanced aging in S. Analysis of genes involved in muscle remodeling showed that S had higher mRNA levels of myogenic differentiation factors (Myogenin, MyoD), embryonic myosin (eMyHC), enzymes involved in regulated breakdown of myofibrillar proteins (Smad2, Trim32, MuRF1,) and NCAM compared with healthy adult men (n = 8). S also had higher mRNA levels of eMyHC, Smad 2, MuRF1 compared with NS. At 88 years, S expressed decreased levels of Myogenin, MyoD, eMyHC, NCAM and Smad2 towards those seen in NS at 70 years. The gene expression pattern of S at 70 years was likely beneficial since they maintained muscle fiber histology and appendicular lean body mass until advanced age. The expression pattern at 88 years may indicate a diminished muscle remodeling coherent with a decline of reinnervation capacity and/or plasticity at advanced age.