Exercise selectively increases G4 AChe activity in fast-twitch muscle

Abstract

Acetylcholinesterase (AChe) molecular forms were studied in hindlimb skeletal muscles from adult male Fischer 344 rats subjected to treadmill exercise for periods ranging between 1 and 30 days. Groups of three animals were exercised for 1 h/day at a treadmill speed of 8.5 m/min, with 1-min sprints at 15 m/min every 10 min. This exercise protocol led to a significant increase in the activity of G4 AChe in fast-twitch (gracilis and tibialis) but not in slow-twitch (soleus) muscles. Other AChe forms and muscle protein content remained unaltered. Such a selective enzymatic change was detected after a single exercise session, became more apparent after three daily sessions, and persisted for at least 30 days of exercise. A larger increment in G4 AChe activity was observed in gracilis muscle end-plate vs. non-end-plate regions. These findings show a specific adaptive reaction of fast-twitch muscles to enhanced motor activity, suggest that individual AChe forms in motor end plates are regulated through separate mechanisms, and support the hypothesis that membrane-bound G4 AChe plays an essential role in neuro-muscular transmission.

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

“…In particular, the present study produced additional evidence that the size of the G, pool characterizing fast muscles is independent of both the oxidative capacity and the content in AChE asymmetric forms of these muscles (Femandez and Donoso, 1988;Gisiger and Stephens, 1988). This fact strengthens the conclusion that, whereas the oxidative enzymes and the asymmetric forms implement their functional role at the level of each individual fiber, the G, pool, in turn, fulfills a specific global need of the entire muscle (or of an anatomical subunit if the muscle is subdivided into heads; Gisiger and Stephens, 1988).…”

Restricted localization of proline‐rich membrane anchor (PRiMA) of globular form acetylcholinesterase at the neuromuscular junctions – contribution and expression from motor neurons

“…In previous studies, G 4 AChE could only be identified by sucrose density gradients in the motor endplate region [16,26]. In this study, we have provided the first analysis of the expression of PRiMA at NMJs, using an antibody specific for the cytoplasmic domain of PRiMA I.…”

Termination and beyond: acetylcholinesterase as a modulator of synaptic transmission

“…The distinct AChE compositions may be altered by cross-innervating these muscles or by altering the mode of stimulation imposed upon them (Lomo et al 1985). Treadmill exercises produce a marked increase in G4 forms in fast, but not low, twitch muscles (Fernandez and Donoso 1988). This may reflect the finding that fast muscles are more readily affected by training than slow ones.…”