Abstract
The interactions between muscle and bone are noted in the clinical relationships
between sarcopenia and osteoporosis. Myokines secreted from the skeletal muscles
play roles in muscle-bone interactions related to various physiological and
pathophysiological states. Although numerous evidence suggests that growth
hormone (GH) influences both muscle and bone, the effects of GH on the
muscle-bone interactions have remained unknown. We, therefore, investigated the
influences of GH administration for 8 weeks on muscle and bone, including
myokine expression, in mice with or without ovariectomy (OVX). GH administration
significantly increased muscle mass in the whole body and lower limbs, as well
as tissue weights of the extensor digitorum longus (EDL) and soleus muscles in
mice with or without OVX. Moreover, it markedly increased grip strength in both
mice. As for femurs, GH administration significantly increased cortical
thickness and area in mice with or without OVX. Moreover, GH significantly
blunted the decrease in the ratio of bone volume to tissue volume at the
trabecular bone in mice with OVX. GH administration significantly decreased
follistatin mRNA levels in the EDL, but not the soleus, muscles in mice with or
without OVX, although it did not affect the other myokines examined. However, GH
administration significantly elevated serum follistatin levels in mice. In
conclusion, this study indicates that GH administration increases skeletal
muscle mass and grip strength and cortical and trabecular bone-related
parameters obtained by micro-computed tomography analyses in mice. However,
myokine regulation might not be critical for the effects of GH on muscle and
bone.
Key words
Growth hormone - Myokine - Muscle - Bone
