Moderate aging does not modulate morphological responsiveness of the neuromuscular system to chronic overload in Fischer 344 rats

• Published in: Neuroscience 2007-09, Vol.148 (4), p.970-977
• Main Authors: Deschenes, M.R, Tenny, K, Eason, M.K, Gordon, S.E
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - physiology; Aging - physiology; Animals; Biological and medical sciences; exercise; Fundamental and applied biological sciences. Psychology; hypertrophy; Muscle Fibers, Skeletal - pathology; Muscle Fibers, Skeletal - physiology; Muscle, Skeletal - pathology; Muscle, Skeletal - physiopathology; Muscular Atrophy - etiology; Muscular Atrophy - pathology; Muscular Atrophy - physiopathology; myofibers; Neurology; neuromuscular junction; Neuromuscular Junction - physiopathology; Rats; Rats, Inbred F344; resistance; synapse; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2007.06.033

Abstract The purpose of this investigation was to determine the effect of aging on neuromuscular adaptations to chronic overload. Eight young adult (8 months old) and eight aged (22 months old) Fischer 344 rats underwent unilateral synergist ablation to overload the plantaris and soleus muscles of that hindlimb and to provide control muscles from the contralateral hindlimb. Cytofluorescent staining and confocal microscopy were used to quantify pre- and post-synaptic features of neuromuscular junctions (NMJs). Histochemical staining and light microscopy were used to assess adaptations of myofibers to chronic overload. Results demonstrate that NMJs of young adult and aged muscles did not undergo morphological remodeling as a result of 4 weeks of chronic overload. In contrast, myofibers of young and aged rats displayed significant ( P