Fast axonal transport of labeled proteins in motoneurons of exercise-trained rats

Abstract

In this study, the fast orthograde axonal transport of radiolabeled proteins was measured to determine the effects of endurance-running training on transport velocity and amounts of transported proteins in rat sciatic motoneurons. Female rats were subjected to a progressive running-training program for 10-12 wk. Twenty-four hours after the last training session, rats underwent right L4-L5 dorsal root ganglionectomy. The next day, 20 microCi of [3H]leucine was injected bilaterally in the vicinity of the motoneuronal cell bodies supplying the sciatic nerve, to study axonal transport parameters. Results showed that peak and average transport velocities of labeled proteins were significantly (P less than 0.05) increased by 22 and 29%, respectively, in the deafferented nerves of the runners as compared with controls. Moreover, the amount of total transported protein-bound radioactivity was increased in both left (40%) and right (37%) sciatic nerves of the runners. An exhaustive exercise session reduced (P less than 0.05) peak displacement (8%) and total transported protein-bound radioactivity (36%) in the sciatic nerves of control rats, whereas no changes were noticed in trained animals. The data suggest that chronic endurance running induces significant adaptations in the fast axonal transport of labeled proteins.

Regulation by exercise of the pool of G4 acetylcholinesterase characterizing fast muscles: opposite effect of running training in antagonist muscles

“…In GAST, PL, EDL, and SOL, the increases were of similar magnitude (35-38%; p < 0.02) while in TA, the change was limited to 9% (not significant). Such increases in citrate synthase activity were similar to what is usually reported for the type of training used in this study (Baldwin et al, 1972;Holloszy and Booth, 1976;Jasmin et al, 1988).…”

Neurodegenerative diseases: exercising towards neurogenesis and neuroregeneration

“…There are also evidences to suggest that exercise could in fact enhance neurogenesis (Aberg et al, 2008; Naylor et al, 2008; Van Praag, 2008; Wu et al, 2008). Furthermore, sustained exercise could in fact facilitate axonal transport of certain proteins such as acetylcholinesterase (Jasmin et al, 1988). Pertinent to this review, there is some evidence from animal studies that exercise could help to alter the antioxidant status in the brain under certain circumstances (Ozkaya et al, 2002).…”

Transitions of muscle fiber phenotypic profiles

“…Degenerative processes in the central nervous system (selective loss of fast α-motor neurons) and/or peripheral nervous system, as well as inactivity and altered thyroid hormone levels, may all contribute to the observed atrophy and potential loss of fast motor units and fast fibers. Exercise has been shown to enhance fast axonal transport in rat muscle (Gharakhanlou et al 1999;Jasmin et al 1988;Kang et al 1995). In addition, there appears to be a reduced number of motor units with increased size in aging muscles (Booth et al 1994).…”